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16817525 | An efficient method for estimating semantic similarity based on feature overlap: reliability and validity of semantic feature ratings. | Two studies were conducted in which human participants rated pairs of words according to the perceived degree to which the words' referents shared semantic features. The participants found thetask intuitive, simple, and quick plete. The ratings were reliable and valid. Interrater and interstudy correlations were high, and ratings were good predictors of known feature overlap values obtained from existing semantic feature norms. |
16817526 | Using personal digital assistants (PDAs) for the collection of safety belt use data in the field. | From 1975 through 2003, because of the use of safety belts, an estimated 180,000 deaths from traffic crashes have been prevented. In order to assess the gains that have been made in safety belt use across the U.S., in individual states, and munities, belt use surveys are conducted at regular intervals to determine use rates. The most valid method for surveying safety belt use is through direct observation. Direct observation surveys are conducted along roadways by trained researchers looking into passing vehicles and recording safety belt use. This method of data collection has been effective in the past through the use of paper-and-pencil data recording, yet it could be improved through the use of electronic munication technology. Reported here is a study designed pare electronic data collection, using personal digital assistants (PDAs), with collection using the traditional paper-and-pencil method during the annual statewide survey of safety belt use in Michigan that we have been conducting since 1984. The goals of the study were to develop a PDA database program for data entry in the field, to pare the PDA data collection process with the paper-and-pencil method on both accuracy and speed, and to assess mechanical and environmental factors, such as battery life, screen visibility, and reaction to adverse weather, that may act as limitations to the PDA method, parison with the paper-and-pencil method. In a parison of methods, two observers collected data at the same roadway intersections, one using paper and a pencil and one using a PDA equipped with our custom software. The study showed that the PDA method was as fast and as accurate as the paper-and-pencil method. There were no adverse effects on the PDA caused by environmental conditions. The PDA was superior to the paper-and-pencil method in rainy weather and for data collector supervision. In addition, the use of the PDA obviated the need for entry of paper-recorded data into an electronic format. We conclude that the use of PDAs for safety belt field data collection is superior to the paper-and-pencil method. A Web address is given where the custom PDA safety belt data collection software can be obtained free of charge. |
16817527 | Comparing observational software with paper and pencil for time-sampled data: a field test of Interval Manager (INTMAN). | In this article, we describe the Interval Manager (INTMAN) software system for collecting time-sampled observational data and present a preliminary paring the program with a traditional paper-and-pencil method. INTMAN is puter-assisted alternative to traditional paper-and-pencil methods for collecting fixed interval time-sampled observational data. The INTMAN data collection software runs on Pocket PC puters and includes a desktop application for Microsoft Windows that is used for data analysis. Standard analysis options include modified frequencies, percent of intervals, conditional probabilities, and kappa agreement matrices and values. INTMAN and a standardized paper-and-pencil method pared under identical conditions on five dimensions: setup time, duration of data entry, duration of interobserver agreement calculations, accuracy, and cost. Overall, puter-assisted program was a more efficient and accurate data collection system for time-sampled data than the traditional method. |
16817528 | A PC parallel port button box provides millisecond response time accuracy under Linux. | For psychologists, it is sometimes necessary to measure people's reaction times to the nearest millisecond. This article describes how to use the PC parallel port to receive signals from a button box to achieve millisecond response time accuracy. The workings of the parallel port, the corresponding port addresses, and a simple Linux program for controlling the port are described. A test of the speed and reliability of button box signal detection is reported. If the reader is moderately familiar with Linux, this article should provide sufficient instruction for him or her to build and test his or her own parallel port button box. This article also describes how the parallel port could be used to control an external apparatus. |
16817529 | Cyberball: a program for use in research on interpersonal ostracism and acceptance. | Since the mid-1990s, research on interpersonal acceptance and exclusion has proliferated, and several paradigms have evolved that vary in their efficiency, context specificity, and strength. This article describes one such paradigm, Cyberball, which is an ostensibly online ball-tossing game that participants believe they are playing with two or three others. In fact, the "others" are controlled by the programmer. The course and speed of the game, the frequency of inclusion, player information, and iconic representation are all options the researcher can regulate. The game was designed to manipulate independent variables (e.g., ostracism) but can also be used as a dependent measure of prejudice and discrimination. The game works on both PC and Macintosh (OS X) platforms and is freely available. |
16817530 | Allelic divergence precedes and promotes gene duplication. | One of the striking observations from recent parisons is that changes in the number of specialized genes in existing gene families, as opposed to novel taxon-specific gene families, are responsible for the majority of the difference in position between major taxa. Previous models of duplicate gene evolution focused primarily on the role that neutral processes can play in evolutionary divergence after the duplicates are already fixed in the population. By instead including the entire cycle of duplication and divergence, we show that specialized functions are most likely to evolve through strong selection acting on segregating alleles at a single locus, even before the duplicate arises. We show that the fitness relationships that allow divergent alleles to evolve at a single locus largely overlap with the conditions that allow divergence of previously duplicated genes. Thus, a solution to the paradox of the origin of plexity via the expansion of gene families exists in the form of the deterministic spread of novel duplicates via natural selection. |
16817531 | A general multivariate extension of Fisher's geometrical model and the distribution of mutation fitness effects across species. | The evolution plex organisms is a puzzle for evolutionary theory because beneficial mutations should be less frequent plex organisms, an effect termed "cost plexity." However, little is known about how the distribution of mutation fitness effects (f(s)) varies across genomes. The main theoretical framework to address this issue is Fisher's geometric model and related phenotypic landscape models. However, it suffers from several restrictive assumptions. In this paper, we intend to show how several of these limitations may be e. We then propose a model of f(s) that extends Fisher's model to account for arbitrary mutational and selective interactions among n traits. We show that these interactions result in f(s) that would be predicted by a much smaller number of independent traits. We test our predictions paring empirical f(s) across species of various gene numbers as a surrogate plexity. This survey reveals, as predicted, that mutations tend to be more deleterious, less variable, and less skewed in higher organisms. However, only limited difference in the shape of f(s) is observed from Escherichia coli to nematodes or fruit flies, a pattern consistent with a model of random phenotypic interactions across many traits. Overall, these results suggest that there may be a cost to plexity although much weaker than previously suggested by earlier theoretical works. More generally, the model seems to qualitatively capture and possibly explain the variation of f(s) from lower to higher organisms, which opens a large array of potential applications in evolutionary genetics. |
16817532 | Reinforcement and sex linkage. | We present a general model for the effect of sex linkage on the evolution of reinforcement of mating preferences on an island. We find that the level of reinforcement can vary up to 80% depending on the mode of inheritance of the female preference and male trait. When reinforcement is driven mainly by selection in the male trait and intrinsic hybrid patibilities are weak, sex-linked preferences and autosomal male traits are the most conducive to reinforcement, whereas autosomal preferences and X-linked traits are the least. Surprisingly, the effect of mode of inheritance on reinforcement is poorly predicted by its effect on the genetic correlation between the male trait and female preference. Sex-linkage of genetic patibility loci increases reinforcement, though this is not due solely to the occurrence of Haldane's rule. We find that reinforcement can lead plete reproductive isolation in some cases but not others and that the mode of inheritance can determine which e occurs. |
16817533 | Testing for different rates of continuous trait evolution using likelihood. | Rates of phenotypic evolution have changed throughout the history of life, producing variation in levels of morphological, functional, and ecological diversity among groups. Testing for the presence of these rate shifts is a ponent of evaluating hypotheses about what causes them. In this paper, general predictions regarding changes in phenotypic diversity as a function of evolutionary history and rates are developed, and tests are derived to evaluate rate changes. Simulations show that these tests are more powerful than existing tests using standardized contrasts. The new approaches are distributed in an application called Brownie and in r8s. |
16817534 | A model of the evolution of dichogamy incorporating sex-ratio selection, anther-stigma interference, and inbreeding depression. | Historically, explanations for the evolution of floral traits that reduce self-fertilization have tended to focus on selection to avoid inbreeding depression. However, there is growing support for the hypothesis that such traits also play a role in promoting efficient pollen dispersal by reducing anther-stigma interference. The relative importance of these two selective pressures is currently a popular topic of investigation. To date, there has been no theoretical exploration of the relative contributions of selection to avoid the genetic costs of self-fertilization and selection to promote efficient pollen dispersal on the evolution of floral traits. We developed a population genetic model to examine the influence of these factors on the evolution of dichogamy: the temporal separation of anther maturation and stigma receptivity. Our analysis indicates that anther-stigma interference can favor dichogamy even in the absence of in-breeding depression. Although anther-stigma interference and inbreeding depression are the key forces driving the initial evolution of dichogamy, selection to match the timing of pollen dispersal to the availability of ovules at the population level es a more potent force opposing the further evolution of dichogamy as the extent of temporal separation increases. This result may help to explain otherwise puzzling phenomena such as why dichogamy is plete in nature and why dichogamy tends to be associated with asynchronous flower presentation. |
16817535 | The evolution of parasites in response to tolerance in their hosts: the good, the bad, and apparent commensalism. | Tolerance to parasites reduces the harm that infection causes the host (virulence). Here we investigate the evolution of parasites in response to host tolerance. We show that parasites may evolve either higher or lower within-host growth rates depending on the nature of the tolerance mechanism. If tolerance reduces virulence by a constant factor, the parasite is always selected to increase its growth rate. Alternatively, if tolerance reduces virulence in a nonlinear manner such that it is less effective at reducing the damage caused by higher growth rates, this may select for faster or slower replicating parasites. If the host is able pletely tolerate pathogen damage up to a certain replication rate, this may result in mensalism, whereby infection causes no apparent virulence but the original evolution of tolerance has been costly. Tolerance tends to increase disease prevalence and may therefore lead to more, rather than less, disease-induced mortality. If the parasite is selected, even a highly efficient tolerance mechanism may result in more individuals in total dying from disease. However, the evolution of tolerance often, although not always, reduces the individual risk of dying from infection. |
16817536 | Imperfect vaccines and the evolution of pathogens causing acute infections in vertebrates. | A study by Gandon et al. (2001) considered the potential ways pathogens may evolve in response to vaccination with imperfect vaccines. In this paper, by focusing on acute infections of vertebrate hosts, we examine whether imperfect vaccines that do pletely block a pathogen's replication (antigrowth) or transmission (antitransmission) may lead to evolution of more or less virulent pathogen strains. To address this question, we use models of the within-host dynamics of the pathogen and the host's immune responses. One advantage of the use of this within-host approach is that vaccination can be easily incorporated in the models and the trade-offs between pathogen transmissibility, host recovery, and virulence that drive evolution of pathogens in these models can be easily estimated. We find that the use of either antigrowth or antitransmission vaccines leads to the evolution of pathogens with an increased within-host growth rate; infection of unvaccinated hosts with such evolved pathogens results in high host mortality and low pathogen transmission. Vaccination of only a fraction of hosts with antigrowth vaccines may prevent pathogens from evolving high virulence due to pathogen adaptation to unvaccinated hosts and thus protection of vaccinated hosts from pathogen-induced disease. In contrast, antitransmission vaccines may be beneficial only if they are effective enough to cause pathogen extinction. Our results suggest that particular mechanisms of action of vaccines and their efficacy are crucial in predicting longterm evolutionary consequences of the use of imperfect vaccines. |
16817537 | Identifying fitness and optimal life-history strategies for an asexual filamentous fungus. | Filamentous fungi are ubiquitous and ecologically important organisms with rich and varied life histories, however, there is no consensus on how to identify or measure their fitness. In the first part of this study we adapt a general epidemiological model to identify the appropriate fitness metric for a saprophytic filamentous fungus. We find that fungal fitness is inversely proportional to the equilibrium density of uncolonized fungal resource patches which, in turn, is a function of the expected spore production of a fungus. In the second part of this study we use a simple life history model of the same fungus within a resource patch to show that a bang-bang resource allocation strategy maximizes the expected spore production, a critical ponent. Unlike bang-bang strategies identified in other life-history studies, we find that the optimal allocation strategy for saprophytes does not entail the use of all of the resources within a patch. |
16817538 | Plasticity of physiology in Lobelia: testing for adaptation and constraint. | Phenotypic plasticity is thought to be a major mechanism allowing sessile organisms such as plants to adapt to environmental heterogeneity. However, the adaptive value of mon plastic responses has not been tested by linking these responses to fitness. Even when plasticity is adaptive, costs of plasticity, such as the energy necessary to maintain regulatory pathways for plastic responses, may constrain its evolution. We used a greenhouse experiment to test whether plastic physiological responses to soil water availability (wet vs. dry conditions) were adaptive and/or costly in the congeneric wildflowers Lobelia cardinalis and L. siphilitica. Eight physiological traits related to carbon and water uptake were measured. Specific leaf area (SLA), photosynthetic rate (A), stomatal conductance (gs), and photosynthetic capacity (Amax) responded plastically to soil water availability in L. cardinalis. Plasticity in Amax was maladaptive, plasticity in A and g(s) was adaptive, and plasticity in SLA was adaptively neutral. The nature of adaptive plasticity in L. cardinalis, however, differed from previous studies. Lobelia cardinalis plants with more conservative water use, characterized by lower g(s), did not have higher fitness under drought conditions. Instead, well-watered L. cardinalis that had higher g(s) had higher fitness. Only Amax responded plastically to drought in L. siphilitica, and this response was adaptively neutral. We detected no costs of plasticity for any physiological trait in either L. cardinalis or L. siphilitica, suggesting that the evolution of plasticity in these traits would not be constrained by costs. Physiological responses to drought in plants are presumed to be adaptive, but our data suggest that much of this plasticity can be adaptively neutral or maladaptive. |
16817539 | Community heritability measures the evolutionary consequences of indirect genetic effects on community structure. | The evolutionary analysis munity organization is considered a major frontier in biology. Nevertheless, current explanations munity structure exclude the effects of genes and selection at levels above the individual. Here, we demonstrate a genetic basis munity structure, arising from the fitness consequences of genetic interactions among species (i.e., interspecific indirect genetic effects or IIGEs). Using simulated and munities of arthropods inhabiting North American cottonwoods (Populus), we show that when prising munities are summarized using a multivariate statistical method, nonmetric multidimensional scaling (NMDS), the resulting univariate scores can be analyzed using standard techniques for estimating the heritability of quantitative traits. Our estimates of the broad-sense heritability of munities on known genotypes of cottonwood trees mon gardens explained 56-63% of the total variation munity phenotype. To justify and help interpret our empirical approach, we modeled munities in which the number, intensity, and fitness consequences of the genetic interactions among prising munity were explicitly known. Results from the model suggest that our empirical estimates of munity heritability arise from heritable variation in a host tree trait and the fitness consequences of IGEs that extend from tree trait to arthropods. When arthropod traits are heritable, interspecific IGEs cause species interactions to change, munity evolution occurs. Our results have implications for establishing the genetic foundations munities and ecosystems. |
16817540 | Using coalescent simulations to test the impact of quaternary climate cycles on divergence in an alpine plant-insect association. | The Quaternary climate cycles forced species to repeatedly migrate across a continually changing landscape. How these shifts in distribution impacted the evolution of unrelated but ecologically associated taxa has remained elusive due to the stochastic nature of the evolutionary process and variation in species-specific biological characteristics and environmental constraints. To account for the uncertainty in genealogical estimates, we adopted a coalescent approach for testing hypotheses of population divergence in coevolving taxa. pared genealogies of a specialized herbivorous insect, Parnassius smintheus (Papilionidae), and its host plant, Sedum lanceolatum (Crassulaceae), from the alpine tundra of the Rocky Mountains to null distributions from coalescent simulations to test whether tightly associated taxa shared mon response to the paleoclimatic cycles. Explicit phylogeographic models were generated from geologic and biogeographic data and evaluated over a wide range of divergence times given calibrated mutation rates for both species. Our analyses suggest that the insect and its host plant responded similarly but independently to the climate cycles. By promoting habitat expansion and mixing among alpine populations, glacial periods repeatedly reset the distributions of genetic variation in each species and inhibited continual codivergence among pairs of interacting species. |
16817541 | Selection and inbreeding depression: effects of inbreeding rate and inbreeding environment. | The magnitude of inbreeding depression in small populations may depend on the effectiveness with which natural selection purges deleterious recessive alleles from populations during inbreeding. The effectiveness of this purging process, however, may be influenced by the rate of inbreeding and the environment in which inbreeding occurs. Although some experimental studies have examined these factors individually, no study has examined their joint effect or potential interaction. In the present study, therefore, we performed an experiment in which 180 lineages of Drosophila melanogaster were inbred at slow and fast inbreeding rates within each of three inbreeding environments (benign, high temperature, petitive). The fitness of all lineages was then measured in mon benign environment. Although slow inbreeding reduced inbreeding depression in lineages inbred under high temperature stress, a similar reduction was not observed with respect to the benign petitive treatments. Overall, therefore, the effect of inbreeding rate was nonsignificant. The inbreeding environment, in contrast, had a larger and more consistent effect on inbreeding depression. Under both slow and fast rates of inbreeding, inbreeding depression was significantly reduced in lineages inbred in the presence of petitor D. melanogaster strain. A similar reduction of inbreeding depression occurred in lineages inbred under high temperature stress at a slow inbreeding rate. Overall, our findings show that inbreeding depression is reduced when inbreeding takes place in a stressful environment, possibly due to more effective purging under such conditions. |
16817542 | Specificity and specialization of congeneric monogeneans parasitizing cyprinid fish. | Patterns and likely processes connected with evolution of host specificity in congeneric monogeneans parasitizing fish species of the Cyprinidae were investigated. A total of 51 Dactylogyrus species was included. We investigated (1) the link between host specificity and parasite phylogeny; (2) the morphometric correlates of host specificity, parasite body size, and variables of attachment organs important for host specificity; (3) the evolution of morphological adaptation, that is, attachment organ; (4) the determinants of host specificity following the hypothesis of specialization on more predictable resources considering maximal body size, maximal longevity, and abundance as measures of host predictability; and (5) the potential link between host specificity and parasite diversification. Host specificity, expressed as an index of host specificity including phylogenetic and taxonomic relatedness of hosts, was partially associated with parasite phylogeny, but no significant contribution of host phylogeny was found. The mapping of host specificity into the phylogenetic tree suggests that being specialist is not a derived condition for Dactylogyrus species. The different morphometric traits of the attachment apparatus seem to be selected in connection with specialization of specialist parasites and other traits favored as adaptations in generalist parasites. Parasites widespread on several host species reach higher abundance within hosts, which supports the hypothesis of ecological specialization. When separating specialists and generalists, we confirmed the hypothesis of specialization on a predictable resource; that is, specialists with larger anchors tend to live on fish species with larger body size and greater longevity, which could be also interpreted as a mechanism for optimizing morphological adaptation. We demonstrated that ecology of host species could also be recognized as an important determinant of host specificity. The mapping of morphological characters of the attachment organ onto the parasite phylogenetic tree reveals that morphological evolution of the attachment organ is connected with host specificity in the context of fish relatedness, especially at the level of host subfamilies. Finally, we did not find that host specificity leads to parasite diversification in congeneric monogeneans. |
16817543 | River capture, range expansion, and cladogenesis: the genetic signature of freshwater vicariance. | River capture is potentially a key geomorphological driver of range expansion and cladogenesis in freshwater-limited taxa. While previous studies of freshwater fish, in particular, have indicated strong relationships between historical river connections and phylogeographic pattern, their analyses have been restricted to single taxa and geological hypotheses were typically constructed a posteriori. Here we assess the broader significance of river capture among taxa by testing multiple species for the genetic signature of a recent river capture event in New Zealand. During the Quaternary an upper tributary of the Clarence River system was diverted into the headwaters of the Wairau River catchment. Mitochondrial DNA (control region and cytochrome b) sequencing of two native galaxiid fishes (Galaxias vulgaris and Galaxias divergens) supports headwater exchange: populations from the Clarence and Wairau Rivers are closely related sister-groups, whereas samples from the geographically intermediate Awatere River are genetically divergent. The upland bully Gobiomorphus breviceps (Eleotridae), in contrast, lacks a genetic signature of the capture event. We hypothesize that there is an increased likelihood of observing genetic signatures from river capture events when they facilitate range expansion, as is inferred for the two galaxiid taxa studied here. When river capture merely translocates genetic lineages among established populations, by contrast, we suggest that the genetic signature of capture is less likely to be retained, as might be inferred for G. breviceps. Rates of molecular evolution calibrated against this recent event were elevated relative to traditional estimates, consistent with the contribution of polymorphisms to branch lengths at shallow phylogenetic levels prior to fixation by purifying selection and drift. |
16817544 | Delimiting species: comparing methods for Mendelian characters using lizards of the Sceloporus grammicus (Squamata: Phrynosomatidae) complex. | Species form the fundamental units of analysis in many areas of biology and, therefore, rigorous delimitation of this unit is important to a broad array of researchers. Recently, many new empirical methods have been proposed to delimit species in nature, and a large literature exists on the theoretical merit and superiority of each method. However, few empirical studies pare the results of these methods applied in the same study system. We used a large allozyme and chromosome dataset to apply a number of genetic-distance, character-based, and tree-based methods to a well-studied, data-rich system: the Sceloporus grammicus plex of central Mexico. We hypothesized species boundaries under a general lineage or evolutionary species conceptual framework in an a priori fashion using mapped restriction-site data (mitochondrial DNA and nuclear rDNA), allozymes, and morphology. We pared the ability of different methods to recover the "hypothesized evolutionary species" (HES). Highton's genetic-distance method and a tree-based method consistently recovered all four HES, although sometimes with weak support. With two exceptions, other methods recovered the same HES, but additional groups were weakly delimited and nested within the HES. Given the apparent recent divergence of some of the chromosome races and distinct populations in plex, these are encouraging results. We emphasize the value of specifying testable criteria as clearly as possible and testing these with methods that make use of different properties of a single dataset. |
16817545 | Convergent evolution of embryonic growth and development in the eastern fence lizard (Sceloporus undulatus). | Theory predicts that cold environments will select for strategies that enhance the growth of ectotherms, such as early emergence from nests and more efficient use of resources. We used mon garden experiment to detect parallel clines in rates of embryonic growth and development by eastern fence lizards (Sceloporus undulatus). Using realistic thermal conditions, we measured growth efficiencies and incubation periods of lizards from five populations representing two distinct clades. In both clades, embryos from cold environments (Indiana, New Jersey, and Virginia) grew more efficiently and hatched earlier than embryos from warm environments (Florida and South Carolina). Because eggs from cold environments were larger than eggs from warm environments, we experimentally miniaturized eggs from one population (Virginia) to determine whether rapid growth and development were caused by a greater maternal investment. Embryos in miniaturized eggs grew as efficiently and incubated for the same duration as embryos in unmanipulated eggs. Taken together, our results suggest countergradient variation has evolved at least twice in S. undulatus. |
16817546 | An eye for detail: selective sexual imprinting in zebra finches. | To investigate the idea that sexual imprinting creates incipient reproductive isolation between phenotypically diverging populations, I performed experiments to determine whether colony-reared zebra finches would imprint on details of artificial white crests. In the first experiment, adults in one breeding colony wore white crests with a vertical black stripe, while in another colony adults wore crests having a horizontal black stripe; except for their crests, breeders possessed wild-type plumage and conformation. Offspring of both sexes reared in these colonies developed mate preferences for opposite-sexed birds wearing the crest type with which they were reared; neither sex developed a social preference for crested individuals of the same sex. In a second experiment, females reared by crested parents preferred crested males versus males with red leg bands, while control females (reared in a colony of wild-type, uncrested birds) preferred red-banded males in the same test. Results of a third experiment that used sexually dimorphic crest phenotypes indicate that both sexes of offspring imprinted on maternal crest patterns. Results support the hypothesis that sexual imprinting can facilitate isolation both by engendering a preference for population-typical traits and by prioritizing such an imprinting-based preference over species-typical preferences for other traits used in mate choice. Comparison with results of other recent studies indicates that imprinting tendencies of both sexes vary with the characteristics of traits presented as an imprinting stimuli. Tendency to imprint may vary with the perceived information content (e.g., kin, sex, or population indicator) of parental traits, a process dubbed selective sexual imprinting. |
16817547 | Evolutionary significance of geographic variation in a plumage-based foraging adaptation: an experimental test in the slate-throated redstart (Myioborus miniatus). | Geographic variation in the plumage pattern of birds is widespread but poorly understood, and in very few cases has its evolutionary significance been investigated experimentally. Neotropical warblers of the genus Myioborus use their contrasting black-and-white plumage to flush insect prey during animated foraging displays. Although previous experimental work has demonstrated that white plumage patches are critical to flush-pursuit foraging success, the amount of white in the plumage shows considerable interspecific and intraspecific geographic variation. We investigated the evolutionary significance of this geographic variation by experimentally decreasing or increasing the amount of white in the tail of slate-throated redstarts (Myioborus ptus) from Monteverde, Costa Rica, to mimic the natural extremes of tail pattern variation in this species. In addition to measuring the effects of plumage manipulation on foraging performance, we performed field experiments measuring the escape response of mon insect prey species (an asilid fly) using model redstarts representing four different Myioborus plumage patterns. Our experiments were designed to test four hypotheses that could explain geographic variation in plumage pattern. Compared to controls, experimental birds with reduced-white tails that mimic the plumage pattern of M. miniatus hellmayri of Guatemala showed significant reductions in flush-pursuit foraging performance. In contrast, the addition of white to the tail to mimic the plumage pattern of M. miniatus verticalis of Bolivia had no significant effect on foraging performance of Costa Rican redstarts. In field experiments with asilid flies, model redstarts simulating the plumage of M. ptus of Costa Rica and M. miniatus verticalis of Bolivia elicited greater responses than did models of other Myioborus taxa with either less or more white in the plumage. The results of our experiments with both birds and insects allow us to reject two hypotheses for geographic variation in plumage pattern: (1) that geographic variation is a nonadaptive result of genetic drift, and (2) that selection for enhanced flush-pursuit foraging performance generally favors increased white in the plumage, but evolutionary trade-offs constrain the evolution of extensive patches of white in some geographic regions. Instead, our results suggest that geographic variation in the plumage pattern of Myioborus redstarts reflects adaptation to regional habitat characteristics that enhances flush-pursuit foraging performance. |
16817548 | The distribution of plant mating systems: study bias against obligately outcrossing species. | Early models of plant mating-system evolution argued that predominant outcrossing and selfing are alternative stable states. At least for animal-pollinated species, recent summaries of empirical studies have suggested the opposite-that outcrossing rates do not show the expected bimodal distribution. However, it is generally accepted that several potential biases can affect conclusions from surveys of published outcrossing rates. Here, we examine one potential bias and find that published studies of outcrossing rates contain far fewer obligate outcrossers than expected. We approximate the magnitude of this study bias and present the distribution of outcrossing rates pensating for it. Because this study examines only one potential bias, and finds it to be large, conclusions regarding either the frequency of mixed mating or the shape of the distribution of outcrossing rates in nature are premature. |
16817549 | Very low additive genetic variance and evolutionary potential in multiple populations of two rainforest Drosophila species. | Most quantitative traits are thought to exhibit high levels of genetic variance and evolutionary potential. However, this conclusion may be biased by a lack of studies on nonmodel organisms and may not generalize to restricted species. A recent study on a single, southern population of the rainforest-restricted Drosophila birchii failed to find significant additive genetic variance for the desiccation resistance trait; however, it is unclear whether this pattern extends to other D. birchii populations or to other rainforest species. Here we use an animal model design to show very low levels of additive genetic variance for desiccation resistance in multiple populations of two highly sensitive rainforest species of Drosophila from tropical northeastern Australia. In contrast, relatively high levels of genetic variance were found for morphological traits in all populations of the species tested. This indicates limited evolutionary potential for evolving increased desiccation resistance in these rainforest restricted species. |
16817550 | [Surgical treatment for respiratory organ fistulas]. | The paper pools the experience accumulated since 1965 at the Russian Surgery Research Center, Russian Academy of Medical Science, in treating 185 patients with respiratory organ fistulas. Medical and surgical treatments were performed in 23 and 162 patients, respectively. Radical operations were made in 124 patients, palliative ones in 38. The radical operation is to disconnect organs, by suturing the fistulous opening. If there were irreversible changes in the organs, their resection was simultaneously made. Palliative operations were performed as an auxiliary intervention before or during a radical operation. A palliative operation as an independent intervention was made only in a patient's severe general condition or in purulent plications. The findings suggest that radical surgery is the method of choice in the treatment of patients with respiratory organ fistulas. |
16817551 | [Long-term results of bronchial resection and plastic repair in patients with lung cancer]. | Thoracic units perform plastic operations on the bronchi in 5-10% of all radical interventions for lung cancer. This figure was 7.5% at our unit. A total of 184 patients were operated on, with a mortality rate of 9.7% (18 patients died). Lobectomy with circulatory resection of the main bronchus is the optimal plastic operation on the bronchi in lung cancer. Long-term results following bronchial resection and plastic repair suggest the oncological rationale for these operations. These operations make it possible to preserve functionally significant lung tissue, thus assuring the high quality of life in the patient. |
16817552 | [Current endoscopic treatments for cicatricial stenoses of the trachea]. | Endoscopic techniques in the treatment of patients with cicatricial stenoses of the trachea have e customary in clinical practice. They may be used alone and bination with open surgery. The present paper discusses various endoscopic therapy modalities. The long-term results of stenting of the trachea for its stenosis are recent and of practical importance, which permits revision of the established opinion on this treatment option. |
16817553 | [Long-term results of correction of extensive tracheal defects by means of microsurgical technologies]. | Up to date, the problem in the correction of extensive tracheal defects has not been solved and remains urgent. For this, the use of microsurgical technologies is promising and these operations have e customary in clinical practice. The Russian Surgery Research Center has gained experience in treating 29 patients undergone correction of extensive tracheal defects, by implanting a revascularized radial autograft into the tracheal defect. After working through the technical aspects of an operation and the specific features of postoperative management, the frequency of plication is minimal both at the site of tracheal defect and in the donor area. Transplantation of revascularized autotissues with backing fabrics ensures the patency of a newly formed trachea and resistance to infection and prevents degenerative tissue changes. The patients have no problems associated with transplanting the autograft into the tracheal defect in the late postoperative period. Autograft blood supply retains its main type several years after surgery. |
16817554 | [Clinical assessment of various treatments for tracheal stenosis]. | The paper deals with the management of cicatricial stenoses of the trachea, which is a topical problem of modern thoracic surgery. Surgical techniques and endoscopic operations aimed at expanding and maintaining the lumen of the airways have been employed. Original types of surgical operations and new endoscopic tools are proposed. |
16817555 | [The problem of treatment in patients with laryngeal and tracheal stenoses, as viewed by an ENT specialist]. | Based on their 40 years' clinical experience in treating patients with laryngeal and cervical tracheal stenoses of various etiology, the authors consider that circular trachectomy, by anastomosing laryngeal cartilages, may be performed by highly skilled specialists only at specialized and well-equipped institutions. In cases of chondroperichondritis of cartilages of the larynx or trachea in the presence of paralysis of the vocal folds, it is necessary to make stepwise reparative and plastic operations that can be performed at the ENT clinics having experience in laryngeal surgery. |
16817556 | [Individual tuberculin diagnosis by the prick test]. | The graded dermal tuberculin test, as described by N. N. Grinchar-Karpilovsky, which is carried out using 100%, 25%, 5%, and 1% tuberculin solution, is monly used for individual tuberculin diagnosis. The use of a prick lancet in a test (the prick test) makes the latter easier and standardized, ensures the equal depth of skin lesion, and requires the less surface of the skin. Assessment of the test (measurement of the diameter of a papule) es simpler and it is objective. The Grinchar-Karpilovsky prick test using a prick lancet significantly upgrades the quality of individual tuberculin diagnosis. |
16817557 | [The use of factorial correlation-regression analysis in the evaluation of the efficiency of BCG immunization in children]. | The paper analyzes the results of a factorial correlation regression analysis of the impact of tuberculosis immunization (BCG vaccination and revaccination) in Omsk under specific epidemiological conditions. The protective effect of BCG vaccination was observed in 58% of cases and that of the first revaccination was in 72%. |
16817558 | [Implication of tuberculosis antibodies in the determination of tuberculous infection]. | The summary serum pool of specific tuberculosis IgG, IgA, IgM antibodies to Mycobacterium tuberculosis (MBT) antigens was studied in children aged under 7 years who had tuberculosis or latent tuberculous infection. The test system "AT-Tub-Best-strip" (ZAO "Vector-Best", Novosibirsk) was applied. The determination of the total level of antibodies to MBT antigens makes it possible to establish the latent activity of tuberculous infection in children, to form high tuberculosis-risk groups, and to select patients for preventive medicine. It is also of value in diagnosing the minor forms of tuberculosis of intrathoracic lymph nodes in children. |
16817559 | [Limited epidemic of tuberculosis among young socially dysadapted individuals]. | Two epidemic outbreaks of tuberculosis were observed among young socially dysadapted individuals at a juvie. They were liquidated, by chiefly implementing social preventive measures and by introducing new chemotherapy regimens. |
16817560 | [The clinicobiological status of patients with pulmonary tuberculosis concurrent with chronic hepatitis B and/or C]. | Examination was made in 155 patients, including 60 patients were diagnosed as having hepatitis, hepatic lesion being first detected by a screening survey for markers of hepatitis. The antipyrine test was carried out. Patients with slow and rapid hydroxylation were identified. No changes were found in the biotransformation functions of the liver in patients with pulmonary tuberculosis 6 months after intravenous intermittent chemotherapy twice a week from the beginning of therapy; however, there was inhibition of the activity of monooxygenases and a two-fold increase in the number of patients with slow hydroxylation among patients with itant chronic hepatitis B and/or C. The best results of chemotherapy were found in tuberculous patients with slow hydroxylation: they less frequently underwent surgical interventions since decay cavities were therapeutically closed. |
16817561 | [A surgical approach to tuberculosis of the thoracic spine and kyphotic deformity and compression of the spinal cord]. | In patients with tuberculosis of thoracic vertebrae, kyphotic deformity pression of the spinal cord involves resection of the involved portion and revision of the vertebral column. Resection was performed with a chisel that has an edge stop. Thus, 2 anterior and 2 posterior incisions (grooves) and a cross bed between them are prepared after resection on adjacent surfaces. The anterior epidural space is revised, by setting the spinal cord free pressing agents. Three-four posterior rib ends are preliminary crossed above or below the apex of the hump at the level of the ends of transverse processes (desirably on both sides). A spinal deformity-correcting prises an anterior loose half and posterior active part. Their bases are fixed on the laths of an operating table at the level of gibbus. The thrust pelots of an anterior tubule are adapted at the level of the presternum and, lower, at the base of the xiphisternum. Active pelots are set paragibbaly. By rotating the holder of the posterior tubule, the vertebral column is pressed down, correcting deformity by 30-40 degrees. A long posterior autograft and an anterior autograft are placed into the prepared incisions, by making spondylodesis and plastic repair of the anterior wall of the vertebral column. Short autografts cut from the posterior rib ends (which ing superfluous) are tightly inserted between them. The grafts are covered with soft tissues and mediatinal pleura; the ends of the crossed ribs are sown together with transcostal sutures. The operative wound are sown with transcostal and intercostal sutures. A drain is taken through the ninth intercostal space. |
16817562 | [A diagnosis for active urinary tract tuberculosis]. | The paper details the procedure of a modified tuberculin challenge test, by keeping in mind the new parameters--the microcirculation of the urinary tract mucosa, which is recorded by Doppler laser flowmetry. The efficiency of the procedure was evaluated in 55 patients, including 25 patients diagnosed as having urinary tract tuberculosis and 30 with nonspecific infections. The urethral microcirculatory parameters studied during the tuberculin challenge confirmed the changes available in all the patients with urinary tract tuberculosis while they were absent in patients with nonspecific pathology. The proposed procedure may objectively record a diagnostic parameter. which improves the quality of diagnosis. |
16817563 | [Cattle Mycobacterium xenopi infection]. | Cattle mycobacteriosis caused by achromous M. xenopi strains was identified in two stock farms. The most typical strain of M. xenopi is the copyrolysis detected by tests and position of high molecular-weight mycolates containing 22, 24, and 26 hydrocarbon atoms and having typical double peaks of saturated and unsaturated acids. |
16817566 | Nurse-initiated retinoblastoma service in New Zealand. | A diagnosis of retinoblastoma is devastating not only for the parents of the children but also for the ophthalmic staff who are involved in the provision of care. In Auckland, New Zealand, the Ophthalmology Department provides specialist ophthalmic care for children and their families diagnosed with retinoblastoma. It became clear to nurses with an interest in retinoblastoma that the service provided was not meeting the needs of patients and families, particularly since the numbers had increased over the past two years. Improving our service was essential, but it had to be done in a cost-effective way. We have been successful in implementing a dedicated support network and service for these patients and families with very little additional resources, and we are extremely proud of these achievements. |
16817567 | Macugen treatment for wet age-related macular degeneration. | Macugen (pegaptanib sodium), manufactured by Eyetech Pharmaceuticals, Inc., and Pfizer, Inc., is the first treatment approved by the U.S. Food and Drug Administration for all forms of wet macular degeneration. Although the cause of wet macular degeneration is not known, it is believed that vascular endothelial growth factor (VEGF) induces angiogenesis, resulting in a neovascular process, the hallmark of wet macular degeneration. Macugen is a VEGF antagonist. In two controlled, double-blinded identical studies, Macugen 0.3 mg was shown to slow the progression of wet macular degeneration. Using strict aseptic technique, Macugen 0.3 mg is administered via intravitreal injection every six weeks for one to two years. Serious adverse reactions include endophthalmitis, retinal detachment, and iatrogenic traumatic cataract. Macugen is administered after a topical anesthetic, a subconjuctival block, or bination of both is used to numb the injection site on the temporal sclera. Post-procedure patients may plain of transient vision loss, burning, pressure, eye pain, or "floaters". At time of discharge, patients should be informed of the signs and symptoms of infection and instructed in the administration of antibiotic drops and in proper follow-up care. Most patients are seen for follow up one week after injection and again in five weeks for additional treatment. |
16817568 | A short history of corneal transplantation: commemorating 100 years. | Corneal transplantation is the monly performed transplant surgery in the world today. This procedure replaces all or some of the recipient cornea with a cadaveric donor cornea. It has been 100 years since the first successful human allograft corneal transplantation was performed. This article provides the reader with a brief history of corneal transplantation. |
16817576 | Biomechanics of the aging spine. | Experimental studies indicate age and degeneration affect spinal biomechanics. In vitro biomechanical experimentation is used to validate finite element cervical spine models. A high percentage of experimental studies have utilized older specimens. Computer models based on these experimental studies may not accurately represent the normal population. Younger full-column and C5-C6 motion segments were tested under pure sagittal plane moments. A review of literature was conducted, and results from previous studies pared to present data to determine whether age was an influencing factor in spinal biomechanics. Findings indicate younger specimens under equivalent pure moment loading magnitudes underwent greater ranges of motion between 0.5 and 2.5 Nm. Based on these preliminary findings, validation of finite element modeling to ensure biofidelity should consider age as a factor that may affect biomechanics. |
16817577 | Evaluating eye injury risk of Airsoft pellet guns by parametric risk functions. | Over 2.4 million eye injuries occur each year in the United States as a result of trauma. New toy monly referred to as Airsoft guns are increasingly ing responsible for ocular injuries in children. The purpose of this study was to determine the ocular injury risk of these Airsoft guns by experimental testing and the use of previously generated ocular injury risk functions. A total of 26 Airsoft pellet impact tests were performed on both post-mortem human and porcine eyes in a laboratory environment. Projectile parameters of diameter, mass, and velocity were used to calculate the injury potential of these impacts for five different ocular injuries: corneal abrasion, lens dislocation, hyphema, retinal damage, and globe rupture. Globe rupture was not observed in any of the experimental tests, which is consistent with that reported in the literature. The two most likely ocular injuries caused by these Airsoft guns are corneal abrasion and hyphema, at nearly a 100% and a greater than 75% risk of injury, respectively. This is consistent with the types of injuries reported in the literature, with corneal abrasion and hyphema being the most frequently occurring ocular injuries due to Airsoft guns. More experimental data on retinal injuries is necessary to make an accurate assessment of the risk of retinal damage from blunt impacts. In summary, the potential for ocular injury from Airsoft guns is great and protective equipment such as protective eyewear should be considered mandatory during operation. |
16817578 | Prevention of facial fractures from night vision goggle impact. | Facial bone fractures in the military can result from direct loading of night vision goggles on the orbital region. Facial fracture research has shown that increasing the area over which the load is applied increases the load tolerance. The purpose of this study is to apply this concept to reducing the risk of facial bone fracture from night vision goggle impacts. The effectiveness of countermeasures in prevention of orbital fracture was evaluated using a vertical drop tower with two impact velocities of 2.6 m/s and 3.6 m/s. The countermeasure used was a rigid plastic custom face shield made from a plaster impression of each head. In addition to two human cadaver subjects, one male and one female, tests pleted on a Hybrid III 50th percentile dummy head. Three impacts to the dummy headform included no countermeasure, safety glasses, and a custom face shield. These tests yielded peak loads of 8700 N, 7500 N, and 5640 N respectively. Using the female subject, impacts were preformed successively until injury occurred. These two impacts to the subject wearing a custom face shield resulted in peak loads of 4025 N and 5158 N. The highest load corresponds to an impact velocity of 3.6 m/s and a nasal bone fracture. Two impacts to the male subject with a custom face shield resulted in peak loads of 4554 N and 5101 N with no injury. The final impact to the male subject had a peak load of 2010 N plete orbital fracture due to the absence of a countermeasure. From these tests it is shown that facial fracture risk from night vision goggle impact can be reduced using a contoured rigid face shield. |
16817579 | A finite element study of age-based size and shape variation of the human rib cage. | To fully understand the effects of aging on the integrity of the normal skeleton, detailed geometric models are needed plement material property data. The purpose of this research is to develop a predictive model for age-related changes in rib-cage geometry using the generalized Procrustes approach, an advanced method of shape analysis. This predictive model is coupled with the finite element method to isolate the effects age-related size and shape change have on the structural response of the rib cage. Using a relatively small sample set (n = 12), trends in the age-related size and shape change of the human thorax consistent with clinical observations are identified. Finite element models constructed from landmark datasets generated via the generalized Procrustes approach demonstrate a decrease with age in the energy absorbing capacity of the thorax during a blunt impact. |
16817580 | The effect of gender and body size on linear accelerations of the head observed during daily activities. | The purpose of this study was to determine the effect of gender and body size on peak linear head accelerations during daily activities. Head accelerations were measured for 18 volunteers using a biteplate system. Each subject performed seven activities: sitting in a chair, sitting quickly in a chair, walking at 1.3 m/s, running at 2.7 m/s, performing jumping jacks, doing a vertical leap, and jumping off a step approximately 20 cm high. Peak resultant head accelerations for each subject and activity pared to determine if there were statistically significant differences based on variables such as gender and size. All measured accelerations were below 10 g with a maximum peak acceleration of 9.54 g recorded during the vertical leap activity. Larger head accelerations were measured during the jumping activities, while lower accelerations occurred during the sitting, walking, and running events. Based on the statistical analysis, it was determined that gender and size do not have a statistically significant effect on peak linear accelerations of the head during daily activities. |
16817581 | The effects of growth factors on the production of osteopontin and osteocalcin. | Bone morphogenetic proteins (BMPs) are a group of structurally related proteins in the transforming growth factor-beta (TGF-beta) family which have been shown to stimulate bone formation in vivo. Since these proteins are concentrated in the organic matrix of bone and would be released after a fracture or during bone resorption, they are likely to have a profound effect on bone remodeling and may provide a link between bone resorption and bone formation. The hypothesis of this study was that osteoblast-like cells (OBs) treated with demineralized bone matrix (DBM) would have similar levels of secretion of osteopontin (OPN) and osteocalcin (OCN) to that of OBs treated with insulin-like growth factor-1 (IGF-1), while OBs treated with bone morphogenetic protein-7, also called osteogenic protein-1 (OP-1), would secrete levels of OPN and OCN less than the DBM group. Specifically, the aims of this study were to evaluate osteoblast-like cells (MG-63 cell line) for secretion of both OPN and OCN after treatment with DBM, OP-1, or pared to control, at 24, 48, and 72 hours. After each incubation period, ELISA kits were used to determine the levels of osteopontin and osteocalcin production. The results clearly demonstrated a rise of OCN at 48 hours and a fall at 72 hours for all samples, including control groups. However, there was no significant difference between groups (p > 0.05). With the OPN assay, results showed no significant difference between groups until 72 hours (p = 0.022), where the IGF-1 group was significantly higher than the Control and DBM groups (p = 0.003 and p = 0.021, respectively). This information is important for understanding the signaling pathways that may be initiated in the osteoblast following stimulation with growth factors. |
16817582 | Effects of thymoquinone, lycopene, and selenomethione in the presence of estrogen on the viability of SiHa cells in vitro. | This study investigated the antioxidants thymoquinone, selenomethione and lycopene on SiHa, a cervical cancer cell line preinfected with human papillomavirus. The hypothesis was that bination of thymoquinone, selenomethione, and lycopene would have a detrimental effect on the viability, and biochemical analysis of SiHa cells. The specific aims were to establish the role of selenomethione, lycopene and thymoquinone on SiHa cells in the presence of, or in the absence of estrogen, and to determine if bination of estrogen, lycopene, selenomethione, and/or thymoquinone are more effective in slowing the proliferation of SiHa cells then when used alone. Results indicated that selenomethione alone appeared to be chemoprotective, but when used bination with estrogen, lycopene and TQ caused cellular damage as evidenced by decreased proliferation rate, increased glutathione levels, and increased MDA levels. |
16817583 | Preliminary evaluation of a load-bearing BMP-2 carrier for segmental defect regeneration. | Large segmental defects in bones can result from tumor removal, massive trauma, congenital malformation, or non-union fractures. Such defects often are difficult to manage and require multiple-phase surgery to achieve adequate union and function. In this study, we propose a novel design of bone morphogenetic protein 2 (BMP-2) carrier for tissue engineering of segmental defect regeneration. The tube-shaped BMP-2 carrier was fabrication from a poly(propylene fumarate)/tricalcium phosphate posite via casting technique developed in our laboratory. An in vitro evaluation showed that pressive strength of the carrier decreased about 48% in 12 weeks while maintained a pH in the 6.8-7.4 range. In vivo study was conducted by implanting carriers loaded with 10 microg of BMP-2 in 5 mm rat femur gap model for 15 weeks. X-ray evidence of bridging was first found in the BMP group at 3 weeks. Bridging in all animals (N = 4) in the BMP group was found at 9 weeks. No x-ray evidence of bridging was found in the No BMP group (N = 3). pQCT analysis indicated that the bone mineral density of the callus in the BMP group has reached the level of native femur at 15 weeks after implantation, while the callus in the No BMP group has a bone mineral density at a lower level of 84% to the native femur. Histology analysis shows that a normal fatty bone marrow was restored and mineralized callus formed and bridged the segmental defect. |
16817584 | The effects of PMMA particle number on MG-63 osteoblast cell function. | Implants used for joint replacement are often cemented into place to increase stability. As the person ambulates, the implanted materials slide against each other producing small wear debris particles. There is increasing evidence that wear debris particles that are present in periprosthetic tissues have direct effects on osteoblasts. Particles resulting from polymethylmethacrylate (PMMA) cements used for fixation may also be involved directly in aseptic loosening of implants. However, it is not known if these particles have a direct or indirect effect on bone formation. The objective of this study was to determine the effect of PMMA particle number on osteoblast cells. MG-63 osteoblast-like cells were challenged with 200 microg/mL, 20 microg/mL and 2 microg/mL PMMA diluted in culture medium. Cells were incubated with the particles for 24, 48, and 72 hours. MG-63 cellular proliferation was unaffected at 24 and 48 hours regardless of the concentration. However, at 72 hours, the low and high dose treatments resulted in a 50% reduction in cell numbers. Interestingly, at 72 hours cellular protein levels were increased in all treated groups by at least 50%. Cellular damage was evident as early as 24 hours in all experimental groups and continued for the duration of the study. Morphological observations showed significant vacuole formation in all experimental groups. Also, there was an overall increase in cell size that coincided with increasing levels of PMMA with noted micronucleoli at the highest dosage. The increase in micronucleoli may be reflective of increased cellular damage. Overall, a PMMA particle challenge resulted in significant membrane perturbations, and that phenomenon was found to be dose and time dependent. |
16817585 | The effects of IGF-1 on cellular phospholipids. | Signals are transduced across the cell membrane through a series of events that are triggered by the activation of receptors or opening of ion channels. It is evident that the stimulation of cells can elicit a series of catabolic cascades, which cause degradation of several membrane phospholipids. Several breakdown products participate directly in the intracellular signaling cascade. The objective of this study was to establish the changes in phospholipid pools of MG-63 cells in 15 and 30 minutes after stimulation with IGF-1, which is a known growth factor. After collection of the cells, methods were performed to prepare the samples for thin-layer chromatography. Silica gel plates were analyzed for each experiment for quantitative and qualitative data. The cells were also tested for alkaline phosphatase activity. The highest percent of radioactivity was within the phosphatidylcholine fraction of control cells at 15 minutes and phosphatidylserine at 30 minutes. The highest percent of radioactivity was in the phosphatidylserine fraction at 15 minutes and increased after 30 minutes in IGF-1 treated cells. |
16817586 | Effects of growth factors on cell migration and alkaline phosphatase release. | Segmental defects in long bones pose a clinical challenge in orthopaedic surgery. These defects often require multiple surgeries to achieve the desired bridging and union. Bone morphogenetic protein 2 (BMP-2) has been used extensively to facilitate regeneration in these large defects. The two important roles that BMP-2 has to play in large defect regeneration are chemotaxis to bone cells to migrate and induction of bone matrix production. Experiments were designed to study the effect of BMP-2 on alkaline phosphatase (ALP) production in cells that have migrated through a porous membrane in a cell migration chamber under the influence of culture media supplemented with BMP-2. Two cell lines, UMR cells and MC3T3-E1 cells, were used. A modified Boyden chamber with 8 microm membrane filter was used. Cell migration under the influence of BMP-2 concentration of 1, 10, 100, and 1000 ng/ml was studied. In both cells, the highest chemotactic effect was observed at 10 ng/ml. The ALP activity in the migrated cell was then characterized. A pattern of increase in ALP activity with increased BMP-2 dose was observed in the migrated cells. |
16817587 | The effects of demineralized bone matrix proteins and osteogenic protein-1 on bone cells isolated in culture. | With the growing number of bone-related traumas and the limitations of traditional bone repair, alternative methods of bone management must be investigated. Demineralized bone matrix protein (DBX) has been used to reconstruct bone. DBX, a type of demineralized bone matrix, is bination of several different proteins including osteogenic protein-1 (OP-1). Osteogenic protein-1 or Bone Morphogenic Protein-7 (BMP-7) was the first BMP approved for clinical use in the United States. Previous studies have shown that proliferation of osteoblasts (bone forming cells) was stimulated by OP-1. However, the effects of DBM and OP-1 at the cellular level have not been clearly defined. MG-63 a cells were utilized as a model and subsequently plated onto 24 well tissue culture plates at a density of 1x 10(5) ml/well. Cells were exposed to different concentrations of DBX demineralized bone matrix and OP-1 for periods of 24, 48, and 72 hours pared with untreated controls. After each incubation period, cell morphology, cell damage, cell number, and protein concentrations were determined. Results indicate a significant increase in cell number at 72 hours in cells treated with 30% (5.66 x 10(5)) and 100% (6.3 x 10(5)) DBX treated groups pared with the control (1.4 x 10(5)). OP-1 results do not indicate a significant increase in cell number at the 24 and 48 hour treatment phases pared with the control (p > 0.05), however, results do show a statistically significant difference (approximately twofold, p < 0.05) between the control cells (1.9 x 10(4)) and those cells treated with low (3.9 x 10(4)) and high (4.1 x 10(4)) concentrations of OP-1 at the 72 hour time phase. The increases in cell number indicate that both DBX and OP-1 are effective in stimulating cell growth. paring the results of the DBX treatments with those of the OP-1 treatments, the cells treated with DBX showed a more substantial increase in bone cell proliferation after treatment than those cells treated with OP-1. This does suggest that DBX provides the most effective treatment for bone cell proliferation. Closer evaluation of the morphology especially the changes occurring at the nuclear level need to be addressed in future studies. |
16817588 | Pathophysiological responses of MRC-5 cells exposed to various doses of x-ray radiation. | The numbers of x-ray procedures used as diagnostic tools are on the rise; these procedures are being used more frequently than ever before. The radiation effect from these procedures are said to be minimal, however there is a significant increase in cellular damage that may lead to cellular aberrations. The objective of this study was to expose human lung fibroblast (MRC-5) cells to various doses of x-ray radiation and evaluate its effects on the proliferation and morphology of the cells. Based on the review of the literature, we selected doses similar to other researchers, the doses were 2, 6 and 10 (Gy), evaluated after 24, 48 and 72 hours of incubation. The results indicated a 25% decrease in the cell number after 48 and 72 hours (p < 0.05), in all groups exposed to either dose of radiation. After 24 hours, there was not a statistically significant difference between the groups exposed to either dose of radiation. Morphologically, the cells exhibited significant changes when exposed to either, 2, 6 or 10 Gy of radiation. The cells showed multiple nucleoli with all doses, and mitotic figures were observed with a dose of 2 Gy. After a dose of 6 Gy, hydropic swelling due to excess fluid in the cytoplasm was noted as well as multiple nucleoli. After 48 and 72 hours, severe vacuolization with various degrees of hypertrophy and atrophy was noted with a dose of 10 Gy. Further analysis revealed that the higher the radiation dose, the more severe the damage after 48 and 72 hours, however, significant damage was evident with all doses, even as low as 2 Gy. |
16817589 | Pathophysiological changes associated with the exposure of sustained delivery of glucocorticoids on pituitary adenoma cell line. | Glucocorticoid receptor rich tissues such as pituitary cells express tissue specific 11 beta hydroxysteroid type 1 enzyme, which causes cortisol to act as an autocrine, anti-proliferative, pro-differentiation stimulus in normal tissue. In pituitary tumor cells there is a strong correlation indicating a shift from 11 beta hydroxysteroid type 1 enzyme activity to 11 beta hydroxysteroid type 2 enzyme activity. This shift causes an anti-proliferative effect, which may be effective in suppressing tumor activity. Overall, the results indicated a decreased in cell number for both acute and chronic administration over a 96 hour period without inducing cellular damage (MDA), reactive nitric intermediates (nitric oxide) or reducing cellular antioxidant status (glutathione). Cortisol administration cause an increase in the number of hyperchromic nuclei suggesting cell cycle regulation. These findings conclude that cortisol administration to pituitary tumor cells may offer a future means of treatment for hypophysectomized patients. |
16817590 | Pathophysiological response of rhesus monkey kidney epithelial cells exposed to cyclosporine A. | Cyclosporine A (CsA) is extracted from Tolypocladium inflatum Gams, which is metabolized through the superfamily of hepatic isoenzymes P-450. CsA has a mean life of 6.4-8.7 h, although this varies among different individuals. Ninety percent of the drug is excreted through biliary excretion and only 6% appears unchanged in the urine. The exact mechanism of action of CsA is unknown; however, CsA has the ability to act on the immune system by blocking the biosynthesis of some lymphokines produced by T lymphocytes and interleukin-2 synthesis at the transcriptional level. It has been suggested that CsA interacts with the cytoplasmic membrane and activates the intracellular calcium pathway, or binds to cytoplasmic proteins (Parra, 2003). The specific objective of this study was to investigate the effects of various concentrations of CsA on the proliferation and viability of Rhesus Monkey Kidney epithelial cells (RMKEC) in culture. Thirty-five wells were plated with RMKEC and sub-divided into five equal groups. Group 2 was treated with 10 mL of ETOH (vehicle for CsA). Groups 3-5, were treated with 10, 25, and 50 uM of CsA, respectively. Data obtained suggests that: (1) there was no significance difference observed using CsA 10 uM and CsA 25 uM parison to the control, (2) the use of 50 uM CsA suppressed cell proliferation parison to the control and caused an increase in all biochemical markers (MDA, Protein, and Nitric oxide), (3) the vehicle resulted in an increase in cell proliferation and a decrease in the biochemical markers MDA and Glutathione. The data suggests that further studies need to be conducted to determine the full impact of CsA on Kidney Epithelial function. |
16817592 | The temporal changes of arterial blood flow dynamics. | Computer simulation of hydrodynamic models, using two dimensional T-junction geometry and experimentally determined arterial wave velocities, shows turbulent blood flow behavior of varying degrees at different critical points of the cardiac cycle. The flow disturbances get stronger when the waveform changes from systolic acceleration to diastolic deceleration. Finally, in the region of diastolic endpoints the flow demonstrates transition to stability due to subsiding blood pressure and arterial wall remodeling effect as a preparation for the start of more streamlined flow at the subsequent cycle. Such flow variations have implications on the initiation of atherosclerosis and interventional surgical procedures designed to alleviate such diseases. First, oscillating wall shear stress can induce different cell signaling pathways which can facilitate the initiation and progression of arterial diseases. Second, through advective transport of atherogenic plasma proteins, filtration to the artery wall is known to be regulated. Third, such constantly changing flows can cause early failure of arterial grafts and could also negatively affect patibility with the host tissue. |
16817591 | A technique for tracking intravascular fluorescent microspheres for the determination of arteriolar blood flow in rats. | Fluorescent microspheres have been used in multiple particle tracking studies. Our laboratory is working towards the use of fluorescent microsphere particle tracking in the study of the retinal circulation. The first stage of this project was to develop a technique for measurement and analysis of the particle tracking data. We intravenously injected 2.0 microm diameter, polystyrene microspheres, labeled with fluorescent dye, in anesthetized rats. Using a microscope with a fluorescence attachment, we viewed the fluorescent particles flowing through the surface vessels of the intestine. Data was recorded then analyzed frame by frame. The path of each microsphere was plotted on a transparency sheet and measured. Using a magnification ratio, the velocity and blood flow rate were calculated for 235 particles in five different blood vessels. We found this technique to be an effective method for studying blood flow in an arteriole. The results parable to other blood flow studies and showed characteristic trends of typical laminar blood flow. |
16817593 | Further safety enhancement of a specialized power assisted tricycle for a child with osteogenesis imperfecta type III and design of an adjustble hand power tricycle. | Several tricycles, one a customized power assisted tricycle, and the second a hand powered tricycle were developed, which offered a unique opportunity to serve multiple purposes in several children's development throughout Wyoming. In Both cases these tricycles provide the children with the opportunity to gain muscle mass, strength, coordination, and confidence. The power assisted tricycle pleted as a senior design project in 2002, and over time safety enhancements have pleted to make the tricycle safer for operation. Unfortunately, the safety system enhancements were not acceptable for it to be released for use. For this reason the tricycle was further redesigned to include more redundant safety systems which will allow the tricycle to be safe for the child's use. The second tricycle was designed to allow for a group of children who have limited use of their legs, to be able to use the same tricycle to give them more upper body strength. A gear system using multiple gear sprockets was adapted to a preexisting tricycle to provide hand power rather than foot power. Without these improvements, the children would not have the opportunity to use these tricycles to help with their development. |
16817594 | Interface parameters of impact-induced mild traumatic brain injury. | Commonly considered a continuum of injuries, diffuse brain injury (DBI) ranges from mild concussion to severe diffuse axonal injury. The lower end of the spectrum is generally referred to as mild traumatic brain injury (MTBI). More severe forms of DBI have garnered extensive experimentation while these milder cases are considerably less explored. Recently, a new device was designed to generate DBI in the rodent using impact-induced angular acceleration. This device is modifiable so the entire spectrum of DBI can be investigated. Severity of DBI is critically dependent on magnitude of angular acceleration. A small animal surrogate like a rodent has a relatively small brain mass. This constraint poses a unique problem because the angular acceleration necessary for DBI is inversely related to brain mass. Prior experimentation estimated an angular acceleration of approximately 350 krad/s2 is necessary for the induction of mild traumatic brain injury (MTBI) in the rodent. To induce these magnitudes of angular acceleration in a repeatable manner, the impacting interface must be critically analyzed. This investigation uses a mathematical model based on parameters of a previously developed experimental model to assess the impacting interface such that angular accelerations are sufficient to produce MTBI in the rodent. |
16817595 | Retrospective identification of subject anthropometry using computed tomography of the leg. | Lower extremity injuries from car crashes are associated with decreased quality of life. To better evaluate the forces seen by the lower extremity during car crashes accurate models of the lower extremities must be created. This effort is motivated by a need to identify CT scans of a 5th female and a 50th and 95th male leg for use in finite element model development. Our goal is to outline a method for obtaining retrospective data on skeletal anthropometry and relate this data to the population when subject anthropometry is unavailable. Landmark data was collected from axial slices of lower extremity CT scans without skeletal pathology and CT scout films. The two methods used to collect data pared and published data was used to create normal distribution curves for the leg lengths of males and females across the adult population. Knowledge of how lower extremity geometry quantitatively relates to subject height was also used to find patient scans representing lower extremity lengths of the 5th female, and 50th and 95th percentile male standard models. From the data collected on the two methods we found that CT 3-D reconstructions are superior for assessing pared to using CT scouts. This methodology is useful for mining the large database of clinical patient scans retrospectively to create models that can predict injury in humans of all shapes and sizes. |
16817596 | Metabolic effects of fructose 1,6-bisphosphate in normoxic and hypoxic states of MG63 osteosarcoma cells. | Glycolysis is a very important process which contains very intricate steps that play a role in cellular performance and viability. Fructose 1,6-bisphosphate (FBP) is a glycolytic intermediate that has proven to improve cellular conditions under hypoxic and ischemic conditions. Osteoblasts are key regulators of skeletal matrix synthesis and degradation. Thus, considering FBP's positive effects on ameliorating hypoxia-induced injuries, the objective of this study was to determine its effects parative effects on osteoblast cells under normoxic and hypoxic states. MG63 osteoblast-like cells were cultured in 24-well culture plates and treated with high, medium and low dosages of FBP at 24, 48, and 72 hours. At the end of each time period, cellular number, damage by a malondialdehyde assay (MDA), and glutathione levels were evaluated. There was a significant increase in cell number for the low level of FBP in normoxia at 48 hours (p < 0.05). For the cells in hypoxia, there was a significant decrease in cell number for the medium level at 48 hours (p < 0.05). At 48 hours there was a significant decrease in cell damage through MDA measurement for the cells in normoxia and hypoxia pared to the control. Cellular damage was not evident in the supernatant in either oxygen condition for the duration of the study. A significant decrease in glutathione levels was also noted for the cells in hypoxia. Cellular morphology included multiple nucleoli, vacuolated cytoplasm, abnormal cells, and web-like cytoplasm. The results indicate that FBP does protect bone cells exposed to hypoxic injuries, and while doing so, ameliorating the states of the cells in shock. |
16817597 | Effects of sustained release of statin by means of tricalcium phosphate lysine delivery system in defect and segmental femoral injuries on certain biochemical markers in vivo. | Statins, which are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are widely used for the treatment of hyperlipidemia, and recent studies and animal data suggest that statins promote osteogenesis and increase bone strength. However, little is known about the effects of statins delivered by sustained delivery system to a target site of a defect and segmental bone fractures on certain biochemical markers including reproductive hormones. The purpose of this study was to develop a targeted statin delivery system using Tricalcium Phosphate Lysine (TCPL) for defect and segmental femoral injuries and evaluate the effects on alkaline phosphatase, total protein, malinodialdehyde, glutathione, total cholesterol, testosterone, luteinizing hormone, statins, and follicle-stimulating hormone. Because of the influence oral intake of statins might have on certain body organs, we also examine the histomorphology of the vital and reproductive organs of the animals receiving statins for a period of 30 days and 12 weeks post surgery. Simvastatin used in this study significantly increased fracture healing and without significant influence on the body weights and the weights and morphology of the vital and reproductive organs. There was a significant reduction in the cholesterol levels on the 3rd week in both phases of the study and at the conclusion of the study the difference in the cholesterol levels was no more significant in both phases. Other biochemical markers including plasma LH, FSH and testosterone levels were not affected by active treatment with simvastatin. In conclusion, short and long-term simvastatin treatment delivered at a fracture target site did not influence vital and reproductive organs, the systemic levels of the biochemical markers studied, but was able to effectively stimulate bone formation in simple plicated segmental fractures. |
16817598 | Identifying anxiety states using broad sampling and advanced processing of peripheral physiological information. | Advances in biosignal acquisition and processing have provided an effective window to plex peripheral physiology related to human emotions. Numerous cardiovascular measures have been used for assessing the activity of the sympathetic and parasympathetic branches of the autonomic nervous system. More recently, respiratory parameters have shown promise for the assessment of anxiety. Current theoretical accounts of anxiety mend a broad assessment of anxiety responses involving measures from the physiological, behavioral and verbal-cognitive domain. However, practical and statistical considerations put restrictions on the number of dependent variables used in studies on emotion. In a laboratory experiment we assessed a large number of psychophysiological parameters to identify their relative utility for differentiating between a neutral (quiet sitting) and an anxious state induced by threat of shock. High effect sizes were found in all psychophysiological systems with electrodermal and behavioral responses demonstrating the highest, and respiratory and cardiovascular responses yielding medium and small effect sizes. A bination of the six most powerful variables was highly significant in distinguishing the neutral from the anxious state and resulted in 83.3% correct classification. Results demonstrate the necessity to include measures from multiple response domains for an adequate assessment of anxiety states. Furthermore, our results point to the significance of respiratory parameters in anxiety assessment. |
16817599 | Predicting zygoma fractures from baseball impact. | The purpose of this study is to develop injury risk functions that predict zygoma fracture based on baseball type and impact velocity. Zygoma fracture strength data from published experiments were mapped with the force exerted by a baseball on the orbit as a function of ball velocity. Using a normal distribution, zygoma fracture risk functions were developed. Experimental evaluation of these risk functions was performed using six human cadaver tests and two baseballs of different stiffness values. High speed video measured the baseball impact velocity. Post test analysis of the cadaver skulls was performed using CT imaging including three-dimensional reconstruction as well as autopsy. The developed injury risk functions accurately identify the risk of zygoma fracture as a result of baseball impact. The experimental results validated the zygoma risk functions at the lower and upper levels. The injuries observed in the post test analysis included fractures of the zygomatic arch, frontal process and the maxilla, zygoma suture, binations of these minuted, tripod fractures of the zygoma. Tests with a softer baseball did result in injury but these had fewer resulting zygoma bone fragments and occurred at velocities 50% higher than the major league ball. |
16817600 | Acquiring non-censored rib fracture data during dynamic belt loading. | The purpose of this paper is to present a method to determine the exact timing of all rib fractures during dynamic belt loading tests on the thorax of human cadavers. In order to generate non-censored rib fracture data, a total of 47 strain gages were placed throughout the thorax of two human cadavers (1 male, 1 female). In order to simulate thoracic loading from a severe car crash, a table-top belt loading device was developed that utilizes a servo-hydraulic test machine to apply a dynamic input. The belt load pulse was configured to result in 40% pression through a 150 ms load and unload cycle. Potentiometers and accelerometers measured the pression and acceleration at three locations, load cells in line with the belt provided belt loads, and load cells on the posterior side of the thorax measured the reaction loads. The time histories of each strain gage were analyzed to determine the time of fracture which could then pared directly to the reaction loads and chest displacements at that exact time, thereby creating a non-censored data set. In both cadavers, all fractures (20 for female and 12 for male) occurred within the first pression of the thorax. By utilizing this technique, the exact timing of an injury level can be characterized relative to the mechanical parameters. |
16817601 | Biomechanical modeling of pregnant occupants in far-side vehicle crashes. | Automobile crashes are the largest single cause of death for pregnant women and the leading cause of traumatic fetal injury mortality in the United States. The purpose of this paper is to evaluate the risk of fetal injury in pregnant occupants exposed to far-side vehicle crashes. A test matrix of puter simulations was performed using putational model of a 30-week pregnant occupant. Three separate far-side impact severities were modeled including velocity changes of 5 mph, 15 mph, and 25 mph over the same 100 ms period. Three restraint conditions were modeled including no restraint, lap-belt only, and the three-point belt. All simulations at 5 mph resulted in very low risk of maternal or fetal injury. The simulations at 15 mph and 25 mph demonstrated the protective benefit of the three-point belt as both the lap-belt and no restraint tests resulted in the mother's head contacting the opposite door resulting in severe head injuries with HIC values above 2000. All simulations at 15 mph and 25 mph indicate possible fetal injury risk regardless of restraint condition as the peak strain values at the utero-placental interface were between 27.1% and 44.9% which equate to fetal injury risks between 36.9% and 61.0%. Direct abdominal contact from the shoulder strap of the three-point belt caused this strain in contrast to the inertial loading induced strain in the lap-belt and unbelted cases. Overall, the console was not a potential fetal injury mechanism in these simulations as the occupant either passed over it in the unrestrained simulations or rotated above it for the lap-belt and three-point belt tests. The results of this study are consistent with previous studies that show the three-point belt is the best and most important safety device for protecting pregnant occupants. |
16817602 | Calculation of tibial loading using strain gauges. | The standard methodology for measuring loads in long bones is the in situ load cell, which enables direct measurements, but alters the stiffness and mass of the subject bone. Bone loading can also be calculated by applying linear beam theory to measurements from strain gauges affixed to the bone surface. The efficacy of the strain gauge method was assessed in this study by mounting three strain gauge rosettes to the midshaft of the tibia in two cadaveric above-knee leg specimens. The specimens were subjected to quasistatic pression tests, and then the tibia was removed and subjected to four-point bending tests. Linear beam theory for an irregularly shaped cross-section was used to calculate the axial load and bending moments in the tibia. It was possible to accurately calculate the bending moments in the bone, but the calculated axial loads appeared to be grossly in error (up to nearly 50%). This error was attributed to bone curvature and deviations from assumptions of bone homogeneity and linearity. The errors in the axial load results could be corrected by calculating an "effective" centroid for each bone, which was found to be approximately 1.5 mm away from the location of the area centroid as determined from CT scans. In spite of the error associated with calculating axial loads, this methodology shows promise for straight bones and for biomechanical experiments in which long bone bending is the parameter of greatest interest and implanting a load cell is problematic (e.g., vehicle-pedestrian tests). |
16817603 | Development of point mass occupant injury criteria using event data recorders. | This paper presents an estimate of the probability of serious occupant injury in frontal crashes based on vehicle kinematics information. Occupant injury risk is developed by modeling the human as a point mass puting the occupant impact velocity (OIV) using the flail space model. Event Data Recorder data provide vehicle kinematics information for real world crashes with known injury es. A data set of 211 cases is used for methodology development and preliminary insight to the injury prediction capability of the metric. Using logistic regression, injury risk curves are generated for all data, a belted occupant subset and an unbelted occupant subset. Based on the models, an occupant restrained by an airbag and safety belt is found to have a lower risk of injury than an occupant only restrained by an airbag. A 50% probability of serious injury is found to correspond to an OIV of 11.2 m/s and 15.9 m/s for unbelted and belted occupants, respectively. |
16817604 | Mechanical properties of human lung parenchyma. | In order to have a detailed analysis of the distribution of stresses in the lung, one needs to understand the mechanical behavior of the lung material. For the stress-strain relationship of human lung, the present state of the art is that the form of the constitutive equations is known, but associated material constants are unknown. In this study, biaxial loading experiments were done on specimens of excised cadaver lung parenchyma without the effects of large blood vessels, bronchi, and pleura. Curves of strain vs. stress were recorded. A non-linear form of strain energy function was used to examine the stress-strain relationship. This relationship fits the experimental data well. The analysis based on data from 11 specimens of excised human lung parenchyma yielded that the physical constants are C/delta = 3.06 +/- 0.84 K x dyn/cm2, alpha = 4.47 +/- 1.94, and beta = -4.20 +/- 2.55. |
16817605 | Effects of polystyrene particle density on type II pneumocytes. | Studies into the effects of ultrafine particles on the lung have shown adverse es and are do in part to the particle size. Inhalation of small particles is associated with exacerbation of respiratory diseases in epidemiological studies. Ultrafine particles have been hypothesized to play an important role, but it is unclear as to whether a dose response type of relationship exists. The aim of the present study was to investigate the role of ultrafine particle number on lung cells and to describe the effects due to phagocytosis of particles by the cells. A549 cells are a transformed cell line similar to type II lung pneumocytes. A549 cells seeded at a density of 5 x 10(4) cells were treated with 1000, 5000, and 10,000 polystyrene particles and incubated at 37 degrees C for periods of 24, 48, and 72 hours. Cell number, protein, and MDA levels were determined on the treated cells pared with untreated controls. The lung cells were also observed microscopically to assess cell damage. Lung cells exposed for 24 hours with 1,000 and 5,000 particles showed the greatest increase in cell number. Cellular protein levels were similar for all groups (p > 0.05) for the duration of the study. MDA levels for treated groups at 24 and 72 hours were not statistically different from the control groups. Cells treated at 48 hours with 5,000 and 10,000 particles showed slight increases in the MDA levels above low particle number and control treated groups. Morphological evaluation of the cells revealed increased inclusions with increasing dose. The results from this study indicate the ability of A549 cells to respond to a challenge with ultrafine particles. The concentrations tested caused an initial stimulation cell proliferation at 24 hours followed by increased damage at 48 hours. Future studies will focus on the inflammatory products formed by ingestion of the ultrafine particles. |
16817606 | Mesh development for a finite element model of the carotid artery. | A technique for developing a structured, hexahedral and quadrilateral mesh for use in finite element analyses of the carotid artery is presented. The model is reconstructed from 270 Computed Tomography (CT) images (slice thickness 0.625mm) of a 57 year old male subject and extends from the arch of the aorta to the base of the jaw. The structured mesh was generated using an unstructured, automatically generated tetrahedral mesh of the intimal surface of the carotid artery and its branches. A parametric meshing software package was used to create the structured mesh, facilitating mesh density studies. The change in volume and surface area introduced when converting the mesh from tetrahedral to hexahedral elements (+1.5% change in volume, -1.4% change in surface area) is small parison to estimated error introduced in the segmentation process. The technique introduced will benefit finite element and fluid dynamic studies of the carotid artery investigating mechanically induced pathology at both physiologic loading rates (i.e., atherosclerotic plaque formation) and high strain rates (i.e., blunt trauma). |
16817607 | Reliability of respiratory tidal volume estimation by means of ambulatory inductive plethysmography. | Ambulatory monitoring of ventilatory parameters in everyday life, field research and clinical situations may offer new insights into respiratory functioning in health and disease. Recent technological advances that employ ambulatory inductive plethysmography could make monitoring of respiration outside the clinic and laboratory feasible. Inductive plethysmography provides a method for nonintrusive assessment of both timing (e.g. respiration rate) and volumetric parameters (e.g. tidal volume and minute ventilation), by which tidal volume is initially calibrated to direct measures of volume. Estimates of tidal volume assessed by this technique have been validated in laboratory investigations, usually examining within-individual relations to direct measures over a large range of tidal volume variation. However, the reliability of individual differences in tidal volume or other breathing parameters has not been tested under naturalistic measurement conditions using inductive plethysmography. We examined the test-retest reliability of respiration rate, tidal volume and other volumetric parameters of breathing over a period of six weeks of repeated measurements during baseline conditions and breathing exercises with 16 healthy freely moving volunteers in a Yoga course. Reliability of measurement was evaluated by calculating the average week-to-week between-subject correlation coefficients for each physiological measure. Additionally because body-mass index has been previously positively correlated to tidal volume, we also assessed this relationship as an external criterion of validity of tidal volume estimation. Regarding the latter, similar correlations to those previous studies were found (r = 0.6). Furthermore, reliability estimates were high and consistent across respiratory measures (typically r's = 0.7-0.8). These results suggest the validity of ambulatory inductive plethysmographic measurement of respiration, at least under relatively sedentary conditions. Findings also point to the stability of individual differences in respiratory parameters over consecutive weeks. |
16817608 | Automating 3D meshing method for patient-specific modeling. | The purpose of this study was to develop an automating meshing method for patient-specific modeling. Three-dimensional geometries of two six-month-old infant heads were reconstructed from the CT data. Finite element meshes including cranial bone of skull, brain, and suture were generated. Both static and dynamic analyses were performed to verify the models. The study for blunt impact of infant head was performed by using these patient-specific models. |
16817609 | Numerical simulation of a cellular-level experiment to induce traumatic injury to neurons. | Previous research has developed a pneumatically driven device for delivering a controlled mechanical insult to cultured neurons. The neuronal cell culture was injured by applying a transient air pulse to a culture well fitted with a highly elastic Silastic culture well bottom. In response to the pressure pulse, he Silastic culture well bottom deformed, stretched the attached cell culture, and resulted in observable cell injuries and death. The goal of this paper was putationally model the spatial distribution of membrane strain, stress, and strain rate to which these cultures were subjected. The simulation results, using a finite element model of the culture well pared well with the results from the original experiments. When peak air pressure was varied from 69 kPa to 345 kPa (10 to 50 psig), numerical simulations showed that the corresponding membrane strains varied from 20 to 95% and the stress response varied from 0.5 to 1.2 MPa. |
16817610 | Instrumented sparring vest to aid in martial arts scoring. | Competitors in certain martial arts, such as Taekwondo, are required to wear protective vests petition. This article outlines the design and fabrication of an instrumented martial arts sparring vest that will aid in martial arts scoring, which is currently a work in progress. After fabrication, this instrumented vest and associated system will not only provide the same protection as before modification, but will also report the location and force magnitude of strikes applied to the vest. This will aid in scoring of martial petitions, as it will determine if a strike is forceful enough to be considered deliberate and therefore is a valid point-scoring strike. This will make scoring petitions unbiased and equal for petitors, something that is difficult to achieve based solely on a judge's assessment by observation. The system will also indicate the probable injury resulting from a strike, for example, no injury, bruising or bone fracture. If petitor's strike force is excessive and serious injury could result, the system will indicate this so action can be taken, such as penalty or disqualification of petitor. Both tissue testing and force testing will be conducted prior to vest fabrication to determine estimates of forces that will damage tissue and typical forces experienced petition. After testing plete, the system will be fabricated and the testing results will be implemented into the associated software. |
16817611 | A mobile phone-based ECG monitoring system. | We have developed a telemedicine system for monitoring a patient's electrocardiogram during daily activities. The recording system consists of three ECG chest electrodes, a variable gain instrumentation amplifier, a low power 8-bit single-chip puter, a 256 KB EEPROM and a 2.4 GHz low transmitting power mobile phone (PHS). plete system is mounted on a single, lightweight, chest electrode array. When a heart fort is felt, the patient pushes the data transmission switch on the recording system. The system sends the recorded ECG waveforms of the two prior minutes and ECG waveforms of the two minutes after the switch is pressed, directly in the hospital puter via the PHS. The puter sends the data to the physician on call. The data is displayed on the doctor's Java mobile phone LCD (Liquid Crystal Display), so he or she can monitor the ECG regardless of their location. The developed ECG monitoring system is not only applicable to at-home patients, but should also be useful for monitoring hospital patients. |
16817612 | Macrophages and fibroblasts respond differently to PMMA particles and mechanical strain. | A primary factor limiting the long-term e of total joint arthroplasty is the aseptic loosening of ponents. The bone-host interface of an unstable implant is associated with large quantities of wear debris as well as an altered mechanical environment. In vitro cellular studies on the effects of particulate biomaterials have been conducted under static conditions. The principal objective of this study was to test the hypothesis that the application of cyclic tensile strain to cultured macrophages and fibroblasts alters the response of these cells to particulate polymethylmethacrylate. P388D1 macrophages and three human synovial fibroblast cells were exposed to particulate PMMA (0, 0.4, 4.0, and 40.0 mg/well) (n = 3) and tested under static or dynamic [cyclic tensile strain (0.5 Hz, 0.2 strain)] conditions. Cellular proliferation was determined by autoradiography following 3H-thymidine incorporation. IL-1beta, TNF-alpha, and IL-6 were identified using immunocytochemistry. Exposure of macrophages to particulate PMMA and/or cyclic tensile strain resulted in a decrease in DNA synthesis. Neither treatment altered the proliferative capacity of fibroblasts. Macrophages and fibroblasts stained positively for IL-1beta, TNF-alpha, and IL-6 under all of the experimental conditions tested. Our study provides evidence that macrophages, but not fibroblasts, exhibit decreased proliferative capacity when exposed to particulate PMMA and mechanical stimuli. |
16817613 | Biomechanical response of the human clavicle subjected to dynamic bending. | The purpose of this study was to determine the biomechanical response of human clavicles when subjected to dynamic three-point bending. A total of 10 human cadaver clavicles were tested at an anatomical impact of 0 degrees relative to the transverse plane. Each clavicle was instrumented with a strain gage located under the impactor. Two load cells were used to capture the impactor and reaction loads. The average failure load was 732 +/- 175 N and the average failure moment was 28.3 +/- 7.8 m. The average failure strain was 19738 +/- 2927 microstrain. Using the cross-sectional geometry properties of each bone obtained from CT scans and the strain gage data, the average elastic modulus was 20.8 +/- 5.7 GPa for the linear region of the loading phase. The data presented in this paper is useful to understand clavicle fractures as well as to develop advanced putational models. |
16817614 | A single moving dipole model of ventricular depolarization. | Modeling abnormal depolarization of the ventricles may provide a means to localize sites of arrhythmia foci from the body surface recordings. In this paper, we present a single moving dipole (SMD) model of the ventricular depolarization. The model can reproduce characteristic QRS parable to the clinical recordings when it is located in an inhomogeneous torso model. Our approach involves estimating a series of dipole moments based on vectocardiograms and estimating trajectories based on the three-dimensional isochrone of the ventricular activation. The patterns of body surface potential isochrones are consistent with those from previous studies. The SMD model was also used to simulate posterior wall infarction, which matched the criteria for this diagnosis. In conclusion, our SMD model provided a base for further ventricular depolarization studies and this equivalent dipole approach might be useful in investigating ventricular arrhythmias and their site of origin. |
16817615 | Pattern extraction in interictal EEG recordings towards detection of electrodes leading to seizures. | This study introduces an algorithm for a new application dedicated at discriminating between electrodes leading to a seizure onset and those that do not lead to seizure using interictal subdural EEG data. The significance of this study is in determining among all of these channels, all containing interictal spikes that are asynchronously, independent of region and time, which are selected randomly (these EEG portions may or may not contain spikes), and yet through the developed algorithm, we are able to classify those channels that lead to seizure and those that do not. The main zones of ictal activity are supposed to evolve from the tissue located at the channels that present interictal activity, but sometimes this is no the case. The purpose is to gain a better understanding of the dynamics of the human brain through a study of subdural EEG, with an emphasis on attempting to characterize mon behaviors of interictal EEG channels prior to an ictal activity. The study will try to correlate the clinical features with the EEG findings and to determine whether the patient has a consistent source of ictal activity, which ing from the location of the group of channels that present interictal activity. If a method was found to detect the electrodes that present interictal activity, with the most potential to lead to an pileptic seizure, then the epilepsy focus could be located with a higher degree of certainty. This analysis allows for the detection of neurological disorders due to epileptic activity in the brain, and rings out how different patients react prior to a seizure. |
16817616 | Enhanced real-time cursor control algorithm, based on the spectral analysis of electromyograms. | This paper presents a new version of an EMG-based, hands-free, cursor control system, pares its performance to that of a previous version. Both systems use classification algorithms that rely on the periodogram estimation of the power spectral density (PSD) of electromyogram (EMG) signals from muscles in the face. The older system requires three electrodes for EMG input, and utilizes an algorithm that calculates partial power accumulations over the frequency ranges of 0Hz - 145Hz and 145Hz - 600Hz in the PSDs of the EMG signals. The new system requires four electrodes for EMG input, and utilizes an algorithm that calculates mean power frequency (MPF) values to assist in distinguishing the cranial muscle that contracted. An experiment was devised to gauge the point-and-click capabilities of both systems. The experimental results were evaluated using Fitts' Law analysis. The results show that the new algorithm provides improved point-and-click performance over the old algorithm. |
16817617 | A new technique for imaging the human spinal cord in vivo. | Diffusion tensor imaging has been used extensively in the brain for identifying morphological characteristics based on gray and white matter structures; however, similar applications in the spinal cord have not been as successful. Spatial resolution and limited contrast have undermined accurate delineation between gray and white matter in the spinal cord. This study applied fuzzy logic to diffusion tensor images of the human spinal cord to discriminate between gray and white matter. The technique mon anisotropy indices and newly developed indices based on properties of the diffusion ellipsoid. Preliminary applications to subjects with varying levels of spinal cord injury are also presented in this study. Results indicated larger contrast between gray and white pared to the traditional fractional anisotropy index and thus presents a superior technique for determining precise morphology of the spinal cord. |
16817618 | Optimizing the classification of acute lymphoblastic leukemia and acute myeloid leukemia samples using artificial neural networks. | Accurate classification of human blood cells plays a decisive role in the diagnosis and treatment of diseases. Artificial Neural Networks (ANN) have been consistently used as a trusted classification tool for this type of analysis. In this study, a new Artificial Neural Network approach is proposed for the multidimensional classification of two of the mon forms of leukemia: Acute Lymphoblastic Leukemia (ALL) and Acute Myeloid Leukemia (AML), also sometimes called Acute Myelogenous Leukemia. Beckman-Coulter Corporation supplied flow cytometry data of 120 patients that were used in the training and testing phases. The ANN algorithm was thus developed to exploit the different features of the different blood cells provided in an optimized fashion. The goal was to establish a programming tool, supported through this new ANN development, for the identification of normal and abnormal blood samples and provide information to medical doctors in the form of diagnostic references for the specific disease state that is considered for this study. The application of the ANN algorithm produced remarkable classification accuracy results that show a 95% classification accuracy for the normal blood samples and 90% classification accuracy for the abnormal samples even under the ubiquitous problem of overlap. |
16817619 | Comparison between mevinolin and PTH action on MG63 osteoblast-like cells. | Increasing osteoblast activity in an anabolic fashion may offer an ideal therapeutic treatment for various plications including osteoporosis. The purpose of this study was to evaluate the effect of mevinolin, a clinical statin drug, on osteoblast function (MG 63 Cell Line) pare its mode of action with the conventionally utilized parathyroid hormone (PTH). MG63 cells were treated with different concentrations (control, low (100 nM), medium (1 uM), and high (10 uM)) of mevinolin or Parathyroid hormone. The cells were incubated for 24, 48, and 72 hours at 37 degrees C in a 95% air and 5% CO2 environmental chamber. Data obtained in this study revealed that: (I) there were significant decreases in cell number after 24 hours upon the exposure of medium and high doses of mevinolin, (II) cell numbers rebounded back toward control after 48 hours and were similar in number at 72 hours, and (III) there were no significant changes in calcium or alkaline phosphatase activity were observed throughout the study. Morphologically, the cells treated with various doses of Mevinolin expressed similar structural changes to those observed using PTH. These changes included pleomorphic characteristics and an occasional hyperchromatic pattern during the entire duration of the study (72 Hours). Other structural features observed were spindle shapes, cluster arrangements and multinucleation. The majority of cells had multiple nucleoli in all treated pared to controls. The overall conclusion of this investigation demonstrated that the concentrations used (100 nM and 10 microM) did not appear to affect the mitotic activities of immature phenotypic MG-63 cells. In addition, the concentrations of mevinolin used did not trigger the differentiation process of the cells throughout the experimental phases. This observation led us to suggest that the reason for such an e could be attributed to the lack of a response in calcium production or alkaline phosphatase activity (stimulator to differentiation and mineralization process). |
16817620 | The response of osteoblast-like cells to dexamethasone and cyclic loading. | The aim of this study was to investigate whether cyclic loading can alter the response of osteoblasts to dexamethasone. Proliferation of osteoblast-like cells (MG-63) was assessed by determining uptake of 3H-thymidine. Three doses of dexamethasone were tested: 0.001 nM, .001 nM, or 0.1 nM. Exposure to increasing levels of dexamethasone resulted in decreased proliferation of osteoblast-like cells. Although there was a slight decrease in proliferation seen in the controls (no dexamethasone) with cyclic loading, cyclic loading did not affect the response of osteoblast-like cells to dexamethasone under these test conditions. Varying loading conditions and the potential effect on metabolic and synthetic activity of the osteoblast-like cells need further study. |
16817621 | Design variables for mechanical properties of bone tissue scaffolds. | The reconstruction of segmental defect in long bone is a clinical challenge. Multiple surgeries are typically required to restore the structure and function of the affected defect site. In order to e this defect a biodegradable bone tissue engineering scaffold is used. This scaffold acts as a carrier of proteins and growth factors, while also supporting the load that the bone would normally sustain, until the natural bone can regenerate in its place. Work was done to optimize an existing solid free-form scaffold design. The goal of the optimization was to increase the porosity of the scaffold while maintaining the strength of a previously-tested prototype design. With this in mind, eight new designs were created. These designs were drawn using CAD software and then through the use of finite element analysis the theoretical pressive strength of each design was obtained. Each scaffold design was constructed by casting a thermal-curable poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) suspension into wax molds fabricated on inkjet printing rapid prototyping machine. The constructs were then experimentally tested by applying a pressive load. The theoretical and experimental values of pressive strength and specific strength of each design pared. Theoretically, the best scaffold design produced from this work improved upon the current design by increasing the porosity by 46% and also increasing the pressive strength by 27%. The experimental data was found to match the theoretical strength in four designs, but deviate from the theoretical strength in five designs. The reasons for the deviations and their relation to the rapid prototyping manufacturing technique were discussed. The results of this work show that it is possible to increase the porosity and strength of a bone tissue engineering scaffold through simple iterations in architectural design. |
16817622 | The biomechanical response of human bone: the influence of bone volume and mineral density. | The purpose of this study was to investigate the relationship between bone mineral density and the biomechanical response. This study presents results from 117 human rib cortical bone coupon tests from six cadavers, three male and three female, ranging in age from 18 to 67 years old. First, the material properties of human rib cortical bone were determined using dynamic tension coupon testing. The rib sections were taken from the anterior, lateral, and posterior regions on ribs 1 through 12 of each cadaver's rib cage. The cortical bone was isolated from each rib section with a low speed diamond saw, and milled into dog bone shaped tension coupons using a puter numerical control machine. A high-rate servohydraulic Material Testing System equipped with a custom slack adaptor, to provide constant strain rates, was used to apply tension loads to failure at an average rate of 0.5 strains/sec. The elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, and strain energy density were determined from the resulting stress versus strain curves. Second, two measures of bone mineral density (BMD) were determined: the global BMD of each cadaver through standard radiographic scaling, and the percent mineralization of each coupon through ash analysis. Overall, the global BMD was correlated with the biomechanical properties, but the local apparent density was not. The global BMD is actually a surrogate for the volume of bone present and it is highly correlated with subject age. In contrast, the apparent density is the true local BMD and it was not correlated with subject age. This is consistent with previous research and illustrates that the overall structural biomechanics of bone are related to the volume of bone, or global BMD, while they are much less related to the apparent density, or local BMD, which varies much less with age. |
16817623 | Mechanical strength repercussions of various fixative storage methods on bone. | This pensates for the lack of literature on the actual effects that various fixative storage methods have on the mechanical strength characteristics of bone and attempts to identify the ideal fixative method for preservation of all tissues while maintaining in vivo bone strength. Researchers currently use a wide variety of storage methods that lessen the mechanical strength to varying degrees. Differences could introduce error into a great number of bone fracture studies if an inexact discrepancy in the mechanical properties of fixed bone does actually exist. Furthermore, such disparities could go on to pose clinical risks for patients. This study focuses on the mechanical strength testing of four different groups of rat femora that were retrieved at various times and subjected to differing storage procedures. The first, Group N, were fresh, new femora retrieved just days before testing. The second, Group F, were femora that have been fixed in a 10% formalin bath for just over a year prior to testing. The third, Group W, are femora that have also been fixed in 10% formalin for just over a year but were washed out just prior to testing. The fourth, Group P, were femora that were retrieved from rats that were perfused with formalin immediately following euthanasia. Mechanical strength tests on the four groups revealed that fixing bone in a 10% formalin bath significantly reduces the mechanical fracture strength properties of the bone regardless of whether the formalin is washed out prior to testing. Testing also revealed that bone from perfused animals behaves more similarly to fresh bones from non-perfused animals suggesting that the formalin did not entirely infiltrate the bone and permanently fix the material. These results could have profound implications on how studies equate the behavior of in vitro bone to in vivo bone which could manifest as plications for patients. |
16817624 | Bovine albumin release and degradation analysis of dicalcium phosphate dihydrate cement. | Dicalcium phosphate dihydrate (DCPD) cement was effective in our prior study as a bone morphogenetic protein-2 (BMP-2) delivery vehicle in a rat segmental defect regeneration study. In this study, we investigated the effects of liquid-to-powder (L/P) ratio on the in vitro degradation and protein release behavior of this material. The L/P ratios used in this study ranged from 0.50 to 0.83. DCPD cylinders were formed with a diameter of 1/4" and a height of 1/4". The effect of L/P on the pressive strength was found to be related to the porosity of the material at different L/P level. The strength of the material in phosphate buffered solution was found to degrade roughly 20% in 14 days. The relation between the final porosity and pressive strength after degradation was modeled with Ryshkewitch equation. A liquid-to-powder ratio of 0.55, 0.7, and 0.8 was then used to fabricate samples for the protein release kinetic study. The low porosity (L/P = 0.55) group was found to have the fastest release rate, while the L/P = 0.8 group had the lowest. More then 60% of the loaded protein was released after 10 hours in all three groups with a final total release ranging between 75% and 93%. The findings suggested that the protein release profile of DCPD cements can be adjusted by the L/P ratio. |
16817625 | Characterization of pulsed magnetic field therapy in a rat model for rheumatoid arthritis. | Recent studies have shown that pulsed magnetic fields (PMF) provide a practical, exogenous method for inducing cell and tissue modifications, as therapy for selected pathological states. A number of clinical studies, in vivo animal experiments and in vitro cellular and membrane research reports suggest that PMF stimulation can significantly reduce pain and accelerate the healing process. However, PMFs are still not widely used in clinical medicine. This research examines the effects of PMFs using an animal model that resembles human rheumatoid arthritis. Using serum protein electrophoresis (SPE) and joint edema evaluation, we were able to monitor disease progression and PMF therapeutic effectiveness. We have used these methods to correlate changes in an acute phase serum protein, alpha-2-macroglobulin, with other indicators of rheumatoid arthritis in Lewis rats treated daily with PMF therapy. The results indicate that PMFs may be a promising non-invasive treatment for chronic inflammatory diseases like rheumatoid arthritis. |
16817626 | Quantitative studies on biological water oxidation: a novel mechanism of T cells and antibodies. | Prior studies show that purified T cell receptors (TCRs) and antibodies catalyze the oxidation of water to H2O2 in the presence of singlet oxygen, but parative efficiencies of TCRs and antibodies in this process have not been reported. Since H2O2 has been shown to activate TCRs and selectively regulate redox sensitive TCR signaling pathways, it is important to understand the physiological significance of these recently uncovered processes. This new information might be used to develop new therapeutic tools for immune and inflammatory diseases. In this paper, we present data showing that under equivalent conditions Jurkat T cell membranes produce H2O2 at a rate of 457 pM/min/mg protein/muW/cm2 while IgG antibodies produce H2O2 at a rate of 192 pM/min/mg protein/muW/cm2. Taking into account the number of catalytic sites in a milligram of T cell membranes and IgGs, we calculate that TCRs catalyze H2O2 production at a specific rate that is about 10(6) times greater than the rate of IgGs. Based on these observations and calculations, we conclude that paratively high rate of H2O2 production by TCRs makes it more likely that this is a physiologically relevant process than the H2O2 production by IgGs. In addition, the catalytic rate for H2O2 production by TCRs parable to the rates of other physiologically important processes, such as catalysis by enzymes. This suggests that singlet oxygen-dependent, TCR mediated, H2O2 production is likely to be physiologically important, perhaps as H2O2 being a small molecule regulator of TCR signal transduction or a modulator of T cell gene transcription. |
16817627 | Personal communicator. | An assistive technology (AT) device was originally created for a young child who has municating. The child is not able to talk and is not old enough to read yet. This rules out munication devices that this child could use municate. A device was requested by the child's educator that would talk for the child. Originally it needed to be wristwatch size and able to visually cue the child so that the child would know what was going to be said. The project's first prototype was built by a senior design student. Although the basic features of the prototype functioned properly, it was not practical for day to day use. Originally a rebuild was requested by the educator but after further investigation it was decided that a new design was needed so that it could better cue the child. A new device was built using a high resolution graphic liquid crystal display (LCD), a voice recording chip and a microcontroller. The wristwatch size requirement was changed to meet available technology and the device was packaged to be used on a lanyard. |
16817628 | Biometric identification using 3D face scans. | Biometrics is an emerging area of bioengineering that pursues the characterization of a person by means of something that the person is or produces. Face recognition is a particularly attractive biometric challenge. Most of the face recognition research performed in the past used 2D intensity images. However, algorithms based on 2D images are not robust to changes of illumination in the environment or orientation of the subject. The ability to acquire 3D scans of human faces removes those ambiguities, since they capture the exact geometry of the subject, invariant to illumination and orientation changes. Unencumbered by those limitations, research in 3D face recognition is now beginning to address a different source of error in biometric recognition: facial geometry deformation caused by facial expressions, which can make 3D algorithms which treat 3D faces as rigid surfaces fail. In this paper, a 3D face recognition framework is proposed to tackle this problem. The framework posed of three subsystems: expression recognition system, expressional face recognition system and neutral face recognition system. In particular, a system for the recognition of faces with one type of expression (smile) and neutral faces was implemented and tested on a database of 30 subjects. The results proved the feasibility of this framework. |
16817629 | 3-D brain segmentation towards the integration of DTI and MRI modalities. | This study introduces a 3-D segmentation method together with a graphical user interface (GUI) as means to effectively automate the process of segmentation with the ultimate objective of integrating and visualizing diffusion tensor imaging (DTI) with magnetic resonance imaging (MRI) in a fully automated 3-D brain imaging system. A secondary objective is to reduce significantly the segmentation time required to extract key landmarks of the brain in contrast to the manual process currently used at many hospital settings. The results provided will prove this important assertion. The inter-correlation coefficient revealed 96.1% accuracy in segmenting all of the processed data, which consequently led to effective registration of the DTI and MRI modalities since they involve the same landmarks. The average speed of segmentation was just 35 seconds, a reduction of over 20 times of what is required for manual segmentation. In order to create a highly integrated interface, the segmentation results serve as input to a registration algorithm we are currently investigating and whose preliminary results support the significance of relying on an effective segmentation process. T1-weighted 3D Gradient Echo MR and DT images from 16 patients at Miami Children's Hospital were used for evaluation purposes. |
16817630 | The effect of conventional and sustained delivery of thymoquinone and levodopa on SH-SY5Y human neuroblastoma cells. | The objective of this study was to determine the effects of thymoquinone on the viability and metabolic activity of SH-SY5Y human neuroblastoma cells alone or challenged with levodopa (L-dopa) using conventional and sustained drug delivery routes. The findings suggest that thymoquinone may protect SH-SY5Y cells against L-dopa toxicity to some degree although the exact mechanism for this is unknown. Thymoquinone may be a viable option to prevent quinone formation as a result of L-dopa auto-oxidation and could be investigated as a neuroprotective agent given the fact that inflammatory etiologies are strongly implemented in the pathogenesis of Parkinson's disease. |
16817631 | The role of glucosamine, chondroitin and thymoquinone on the viability and proliferation of a HTB-93 rheumatoid arthritis cell model. | Glucosamine (GS), chondroitin (CD), and thymoquinone (TQ) are plementary medicines under investigation in this study. Glucosamine is a naturally occurring glycoaminoglycan that contributes to the development of proteoglycans needed for the development of cartilage development and regeneration. Chondroitin is also a naturally occurring glycoaminoglycans (GAG) that seems to support the efforts of glucosamine as well as provide chondroprotection while serving as a 'water magnet' within the joint matrix. Thymoquinone is derived naturally from the black seed plant that is extremely popular within Middle Eastern countries. Its benefits are multiple, including both antioxidant and anti-inflammatory properties. These products were administered to HTB-93 synovial cells and cell viability, damage, and alterations in morphology were analyzed after 72 hours. Preliminary results revealed that chondroitin increased cell number in the high treatment group with increased nitric oxide production and decreased glutathione pared to the control, glucosamine, and TMQ. Decreased glutathione levels were seen in the medium and high doses of both glucosamine and chondroitin. Increased levels of glutathione were seen with increasing TMQ, without changes in cell numbers or nitric oxide. The data indicates that medium and high doses of glucosamine and chondroitin may be cytotoxic to HTB-93 synovial cells. |
16817632 | Differential effects of cortisol on MRC-5 fibroblasts and hypertrophic LL-29 fibroblasts. | Cortisol is a glucocorticoid secreted by the adrenal cortex that helps facilitate the body's response to stress and regulates the immune system. Glucocorticoid receptors can be found on most cell types and as a consequence, cortisol hormone plays an essential role on the body's physiologic systems. Cortisol has been shown to elicit differing responses from normal fibroblasts parison to hypertrophic fibroblasts. The purpose of this experiment was to analyze the differential effects of cortisol on normal MRC-5 fetal lung fibroblasts and hypertrophic LL-29 lung fibroblasts from a patient with idiopathic pulmonary fibrosis. The objectives of the experiment are to obtain and culture normal and hypertrophic lung fibroblasts, to challenge cells with subphysiological, physiological, and supraphysiological doses of cortisol (0.01 microg/dL, 0.2 microg/dL, 1 microg/dL) for 24, 48, and 72 hour incubation periods and to analyze cellular activity using the methods of cell count, protein assay, MDA, and morphological evaluation. Data collected from this study demonstrated variable response to cortisol by both cell lines. Striking results revealed that in LL-29 cells, supraphysiological dose of cortisol stimulated cell growth only in the 24-hour incubation period without showing any changes in number of micronucleoli or structural damage. In contrast, MRC-5 cells showed increased growth at a later stage (48 hours) with a dose specific increase with significantly increased micronucleoli numbers. In conclusion, the two cell lines differ in their response to cortisol concentration in a dose and time dependent manner. Cortisol concentrations did not induce structural damage throughout the experiment. These observations could help significantly in minimizing the traumatic side effects induced through stress conditions by employing intervention modalities to regulate systemic cortisol. |
16817633 | Comparison of potential chemotherapeutic agents, 5-fluoruracil, green tea, and thymoquinone on colon cancer cells. | Antioxidants have been found to be quite successful in deterring certain disease processes for years, especially cancer. Antioxidants protect the body by neutralizing the free radicals and donating one of their own electrons, thus ending the scavenger reaction. Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, is a valuable scavenger of reactive oxygen species in vitro as well as in vivo. Thymoquinone (TQ), a major ponent of black seed (Nigella sativa), is also known for its powerful scavenger abilities as an inhibitor of oxidative stress and has been utilized in the Middle East for centuries for healing properties. These two potent antioxidants pared to the chemotherapeutic drug of choice, 5-fluorouracil (5-FU), have demonstrated incredible chemotherapeutic responses to the SW-626 cell line. The objective of this study was to evaluate pare the effects of SW-626 colon cancer cells after a 24, 48, and 72 hour incubation periods with low, medium, and high doses of EGCG, TQ, and 5-FU. Cell viability, cell number, cellular morphology, and cellular metabolism pared for the control and treatment groups. The results of this study evidenced a similar significant decrease in cell number as early as 24 hours in the groups treated with TQ and pared to 5-FU. Increases in cellular damage were evident after 24, 48, and 72 hours and in all treated pared with the control. Reduced cell numbers in the treated groups suggests the possibility that TQ and EGCG may have similar chemotherapeutic effects on cancer cells as 5-FU. |