bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracluster correlation coefficients from the 2005 WHO Global Survey on Maternal and Perinatal Health: implications for implementation research
Authors: Taljaard Monica , Donner Allan , Villar José , Wojdyla Daniel , Velazco Alejandro , Bataglia Vicente , Faundes Anibal , Langer Ana , Narváez Alberto , Valladares Eliette , Carroli Guillermo , Zavaleta Nelly , Shah Archana , Campodónico Liana , Romero Mariana , Reynoso Sofia , De Pádua Karla Simônia , Giordano Daniel , Kublickas Marius , Acosta Arnaldo ,   the World Health Organization 2005 Global Survey on Maternal and Perinatal Health Research Group
Published: February 2008

Cluster‐based studies involving aggregate units such as hospitals or medical practices are increasingly being used in healthcare evaluation. An important characteristic of such studies is the presence of intracluster correlation, typically quantified by the intracluster correlation coefficient (ICC). Sample size calculations for cluster‐based studies need to account for the ICC, or risk underestimating the sample size required to yield the desired levels of power and significance. In this article, we present values for ICCs that were obtained from data on 97 095 pregnancies and 98 072 births taking place in a representative sample of 120 hospitals in eight Latin American countries. We present ICCs for 86 variables measured on mothers and newborns from pregnancy to the time of hospital discharge, including ‘process variables’ representing actual medical care received for each mother and newborn. Process variables are of primary interest in the field of implementation research.

We found that overall, ICCs ranged from a minimum of 0.0003 to a maximum of 0.563 (median 0.067). For maternal and newborn outcome variables, the median ICCs were 0.011 (interquartile range 0.007–0.037) and 0.054 (interquartile range 0.013–0.075) respectively; however, for process variables, the median was 0.161 (interquartile range 0.072–0.328). Thus, we confirm previous findings that process variables tend to have higher ICCs than outcome variables. We demonstrate that ICCs generally tend to increase with higher prevalences (close to 0.5). These results can help researcherscalculate the required sample size for future research studies in maternal and perinatal health.
Variation in season of birth in singleton and multiple births concordant for autism spectrum disorders
Authors: Lee Li‐Ching , Newschaffer Craig J. , Lessler Justin T. , Lee Brian K. , Shah Rashmi , Zimmerman Andrew W.
Published: February 2008

Patterns of seasonal variation in births in some neuropsychiatric conditions have been found in previous research; however, no study to date has examined these disorders for seasonal variation in singletons and multiple births separately. This study aimed to determine whether the birth date distribution for individuals with autism spectrum disorders (ASD), including singletons and multiple births, differed from the general population. Two ASD case groups were studied: 907 singletons and 161 multiple births concordant for ASD. Two control groups were obtained from registered births of singletons and multiples.

Results of the non‐parametric time‐series analyses, where day of birth was used, suggested there were three peaks in ASD singletons and ASD concordant multiple births. Roughly, the peaks were in April, June and October for singletons and about 2–4 weeks earlier in multiples. Results from multivariable Poisson regression, where month of birth was used, indicated that ASD concordant multiple births in males tended to be higher than expected in March, May and September (with borderline statistical significance), but were 87% less in December (P < 0.05), as compared with January. Overall, the patterns of relative risk estimates from Poisson regression are similar to findings from the non‐parametric time‐series approach, but are not exactly congruent. It is important to note that indications of seasonality may be sensitive to the selection of time cut‐points and therefore an arbitrary binning of time can either mask existing trends or falsely indicate the presence of a trend. The presence of seasonal trends in ASD singletons and concordant multiple births suggests a role for non‐heritable factors operating during the pre‐ or perinatal period, even among cases with a genetic susceptibility.
Histological Changes of the Feline Cervix, Endometrium and Placenta after Mid‐gestational Termination of Pregnancy with Aglepristone
Authors: Georgiev P , Wehrend A , Penchev G , Vodenicharov A , Kauffold J , Leiser R
Published: February 2008

Contents

This study was conducted to investigate endometrial and placental structural changes that occurred in response to mid‐gestational termination of pregnancy in queens using aglepristone, a progesterone receptor antagonist. Thirteen European Shorthair pregnant queens were either treated with aglepristone (10 mg/kg body weight; subcutaneously) twice on days 25 and 26 after first mating (am; group I; n = 9), or remained untreated and served as control (group II; n = 4). Queens of group I were ovariohysterectomized between days 30 and 41 am, either at the onset (n = 3) or during (n = 1) abortion and 12 h (n = 1), 24 h (n = 3) or 10 days after abortion (n = 1). Queens of group II were ovariohysterectomized on day 30 am. Tissue was collected from the cervix, and the interplacental zone as well as the paraplacenta/placental girdle of the uterus, subjected to standard histological procedures and evaluated using light microscopy. During abortion, gaps appeared within the paraplacenta and the placental girdle which were filled with blood, leading to an embryo‐maternal disconnection. Blood was also observed within the uterine lumen as well as the interstitial mucosal stroma of the cervix and the placental girdle zone and probably originated from damaged venules, whilst arterioles remained intact. As the interval between abortion and surgery increased, the interstitial and luminal haemorrhages became less pronounced and completely disappeared except interstitial remnants 10 days after abortion. The endometrial regeneration was not fully completed on day 10 after abortion and a few cystically dilated glands were evident. In conclusion, abortion of queens through aglepristone given during mid‐gestation is assumed to be the result of damage of uterine venules. This leads to an interstitial haemorrhages and bleeding into the uterine lumen, subsequently resulting in utero‐placental detachment.
Co‐culture of Buffalo Preantral Follicles with Different Somatic Cells
Authors: Ramesh HS , Gupta PSP , Nandi S , Manjunatha BM , Kumar V Girish , Ravindra JP
Published: February 2008

Contents

The effect of co‐culture of buffalo preantral follicles (PFs) with different somatic cells, i.e, cumulus, granulosa, ovarian mesenchymal and oviductal epithelial cells was studied. Large PFs (250–450 μm) were isolated by microdissecting the trypsin (1%) digested ovarian cortical slices. Cumulus cells were isolated by repeated pipetting of oocytes, granulosa cells were isolated by aspirating from punctured PFs and ovarian mesenchymal cells were isolated from ovarian cortex by scraping the cortical slices and passing through 20 μm filter. Preantral follicles were cultured in standard culture medium without somatic cells or co‐cultured with cumulus cells, granulosa cells, ovarian mesenchymal cells and oviductal epithelial cells for 80 days. The growth rate (μm/day) of the PFs was monitored by measuring follicular diameter on day 0, 30, 60 and 80 days of culture. The viability of PFs was evaluated by trypan blue staining. The results indicated that PFs co‐cultured with cumulus, granulosa and ovarian mesenchymal cells had a better development and survivality compared with control and those co‐culture with oviductal epithelial cells. Maximum growth and survivality of PFs were achieved when cultured with cumulus cells. It is concluded that inclusion of somatic cells in PF culture media had beneficial effect on the growth of PFs and cumulus cells supported maximum growth and survivality of PFs in vitro of all somatic cells tested.
Prognostic significance of adjuvant cisplatin‐based combination chemotherapy following radical cystectomy in patients with invasive bladder cancer
Authors: Muramaki Mototsugu , Miyake Hideaki , Kurahashi Toshifumi , Takenaka Atsushi , Inoue Taka‐Aki , Fujisawa Masato
Published: February 2008

Objectives:  The objectives of this study were to retrospectively examine the outcomes of adjuvant cisplatin‐based combination chemotherapy following radical cystectomy in patients with invasive bladder cancer in order to identify parameters predicting the prognosis of these patients.

Methods:  This study included a total of 51 patients with muscle invasive bladder cancer who underwent radical cystectomy between January 1995 and December 2004, and subsequently received at least two cycles of either MVAC (methotrexate, vinblastine, doxorubicin and cisplatin) or MVP‐CAB (methotrexate, doxorubicin, vincristine, cyclophosphamide, bleomycin and cisplatin) chemotherapy in an adjuvant setting because of the presence of diseases corresponding to pT3/4 and/or pN1/2 without clinical evidence of metastasis. The significance of several clinicopathological factors as predictors of disease recurrence and cancer‐specific death was evaluated using univariate and multivariate analyses.

Results:  During the observation period of this study (median, 26.5 months), disease‐recurrence and cancer‐specific death were observed in 21 and 16 patients, respectively. The 5‐year recurrence‐free and cancer‐specific survival rates were 48.6% and 54.1%, respectively. Among several factors examined in this series, lymph node metastasis and concomitant carcinoma in situ (CIS) were identified as significant predictors of both disease‐recurrence and cancer‐specific death, and these were also independently associated with disease‐recurrence and cancer‐specific death.

Conclusions:  Adjuvant cisplatin‐based combination chemotherapy for patients with extravesically extended bladder cancer following radical cystectomy resulted in comparatively unsatisfactory outcome concerning cancer‐control; accordingly, it would be necessary to develop a more efficacious therapeutic strategy for such patients, particularly for those with lymph node metastasis and/or concomitant CIS.
Developmental trajectories for spatial frames of reference in Williams syndrome
Authors: Nardini Marko , Atkinson Janette , Braddick Oliver , Burgess Neil
Published: February 2008

Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body‐, environment‐, and object‐based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body‐ and environment‐based frames of reference. Crucially, object‐based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark‐based representations supplement those based on the body and on self‐motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.
Convincing Claims? Democracy and Representation in Post-9/11 Britain
Authors: Giles Moss , Ben O'Loughlin
Published: February 2008

This article is about political representation and representative claim making, taking as its backdrop the ongoing public controversy and disaffection concerning the British government's policy and conduct in the ‘war on terror’. We investigate ethnographic-style data that chart the responses of citizens to foreign and domestic policy in the war on terror and in particular their responses to the representation and justification of policy decisions by political leaders. Our focus is not on political representatives and their intentions, but on the representations of objects and identities in political discourse and how citizens respond to these representations. We suggest that despite the existence of matters of potentially shared concern, such as ‘Iraq’ and ‘terrorism’, the representations offered by the British government have often been too certain, fixed and direct, making it difficult for citizens to comprehend or connect to their representations as meaningful and negotiable. Following Bruno Latour, we describe this mode of representation as ‘fundamentalist’, and contrast it with a ‘constructivist’ mode of more contingent representations where politicians take into account and can be taken into account. Our analysis suggests citizens respond to fundamentalist claims in several ways. For some, the response has been antagonism, alienation and a lack of belief in the ability of democratic politics to arrive at responsible decisions on shared problems and concerns. For others, however, inadequate representative claims generate a demand for the construction of more nuanced, complex representations, even acting as a spur for some to contest the claims through political engagement.
Compensation of Regional Unemployment in Housing Markets
Authors: VERMEULEN WOUTER , VAN OMMEREN JOS
Published: February 2008

Why are regional unemployment differentials in Europe so persistent if, as the wage curve literature demonstrates, there is no compensation through wages? Using Urban Audit data for 142 cities over 12 EU countries, as well as a Dutch household survey, we estimate relationships between local labour market indicators and the average house price level. The evidence suggests that workers are compensated in housing markets to a significant extent, so that regional differences in unemployment may reflect an equilibrium outcome.
Inbreeding and Loss of Genetic Variation in a Reintroduced Population of Mauritius Kestrel
Authors: EWING STEVEN R. , NAGER RUEDI G. , NICOLL MALCOLM A. C. , AUMJAUD AURELIEN , JONES CARL G. , KELLER LUKAS F.
Published: February 2008

Abstract:  Many populations have recovered from severe bottlenecks either naturally or through intensive conservation management. In the past, however, few conservation programs have monitored the genetic health of recovering populations. We conducted a conservation genetic assessment of a small, reintroduced population of Mauritius Kestrel (Falco punctatus) to determine whether genetic deterioration has occurred since its reintroduction. We used pedigree analysis that partially accounted for individuals of unknown origin to document that (1) inbreeding occurred frequently (2.6% increase per generation; NeI= 18.9), (2) 25% of breeding pairs were composed of either closely or moderately related individuals, (3) genetic diversity has been lost from the population (1.6% loss per generation; NeV= 32.1) less rapidly than the corresponding increase in inbreeding, and (4) ignoring the contribution of unknown individuals to a pedigree will bias the metrics derived from that pedigree, ultimately obscuring the prevailing genetic dynamics. The rates of inbreeding and loss of genetic variation in the subpopulation of Mauritius Kestrel we examined were extreme and among the highest yet documented in a wild vertebrate population. Thus, genetic deterioration may affect this population's long‐term viability. Remedial conservation strategies are needed to reduce the impact of inbreeding and loss of genetic variation in this species. We suggest that schemes to monitor genetic variation after reintroduction should be an integral component of endangered species recovery programs.
Balanced translocation in a patient with severe myoclonic epilepsy of infancy disrupts the sodium channel gene SCN1A
Authors: Møller Rikke S. , Schneider Lizette M. , Hansen Christian P. , Bugge Merete , Ullmann Reinhard , Tommerup Niels , Tümer Zeynep
Published: February 2008

Summary

In a patient with severe myoclonic epilepsy of infancy (SMEI), we identified a de novo balanced translocation, t(2;5)(q24.3,q34). The breakpoint on chromosome 2q24.3 truncated the SCN1A gene and the 5q34 breakpoint was within a highly conserved genomic region. Point mutations or microdeletions of SCN1A have previously been identified in SMEI patients, but this is the first report of a balanced translocation disrupting the SCN1A gene in an epilepsy patient. We therefore recommend that SMEI patients without SCN1A microdeletions or point mutations should be investigated for chromosomal rearrangements.
Thermophysical Properties of ZrB2 and ZrB2–SiC Ceramics
Authors: Zimmermann James W. , Hilmas Gregory E. , Fahrenholtz William G. , Dinwiddie Ralph B. , Porter Wallace D. , Wang Hsin
Published: February 2008

Thermophysical properties were investigated for zirconium diboride (ZrB2) and ZrB2–30 vol% silicon carbide (SiC) ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and densities. The thermal conductivity of ZrB2 increased from 56 W (m K)−1 at room temperature to 67 W (m K)−1 at 1675 K, whereas the thermal conductivity of ZrB2–SiC decreased from 62 to 56 W (m K)−1 over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared with previously reported thermal conductivities for ZrB2 and ZrB2–SiC.
A Study of Drug Detection in a Postmortem Pediatric Population
Authors: Naso Claire , Jenkins Amanda J. , Younger Douglas
Published: February 2008

Abstract:  At The Office of the Cuyahoga County Coroner (CCCO), Cleveland, Ohio, it is customary to perform an autopsy and conduct toxicological testing on decedents less than 19 years of age. This study provides a retrospective evaluation of drugs detected in a pediatric postmortem population between the years 1998 and 2002 (n = 730). Demographic information, cause and manner of death, and toxicological results were examined. Blacks comprised 54% of cases, males 59%, and 48% were less than one year of age or stillborn. Forty‐two percent of deaths were ruled natural, 27% accident, 13% undetermined, 5% suicide, and 2% homicide. Of the 640 cases subjected to comprehensive testing, 38% of the cases were positive for at least one compound. Resuscitative/treatment drugs were detected most frequently (56% of positive results), followed by illicit drugs (26%), ethanol (11%), carbon monoxide (8%), and antihistamines (6%). Eighty‐seven cases contained more than one drug. The deaths of 47 individuals were drug related (6%). In this population, it is recommended that illicit drugs and ethanol are targeted for testing, especially when limited specimens are available for analysis.
Acute sleep‐promoting action of the melatonin agonist, ramelteon, in the rat
Authors: Fisher Simon P. , Davidson Kathryn , Kulla Alexander , Sugden David
Published: February 2008

Abstract:  Insomnia, which is severe enough to warrant treatment, occurs in ∼10% of the general population. It is associated with a range of adverse consequences for human health, economic productivity and quality of life. In animal and human studies, administration of melatonin has been reported to promote sleep, although there has been controversy regarding its effectiveness. The present study used a chronically implanted radiotelemetry transmitter to record electroencephalogram (EEG) and electromyogram (EMG) to enable discrimination of wake (W), nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep in un‐restrained rats. The acute action of melatonin and ramelteon, a melatonin agonist recently approved for long‐term treatment of insomnia in the USA, was examined. Radioligand binding assays on recombinant human MT1/MT2 receptors showed that both the melatonin and ramelteon were both high affinity, nonsubtype selective ligands. Both compounds acted as potent full agonists on a cellular model of melatonin action, the pigment aggregation response in Xenopus laevis melanophores. Both melatonin and ramelteon (10 mg/kg, i/p), administered close to the mid‐point of the dark phase of the L:D cycle, significantly reduced NREM sleep latency (time from injection to the appearance of NREM sleep). Both the drugs also produced a short‐lasting increase in NREM sleep duration, but the NREM power spectrum was unaltered. Neither drug altered REM latency, REM sleep duration nor power spectrum during REM sleep. In conclusion, ramelteon administration, like melatonin, exerted an acute, short‐lasting sleep‐promoting effect in the rat, the model most commonly used to evaluate the activity of novel hypnotic drugs.
Desquamative gingivitis: retrospective analysis of disease associations of a large cohort
Authors: Leao JC , Ingafou M , Khan A , Scully C , Porter S
Published: February 2008

Background:  Desquamative gingivitis (DG) is usually a manifestation of immunologically mediated mucocutaneous disorders, although it was previously suggested to be hormonally related.

Methods:  One hundred and eighty‐seven Caucasian UK residents with clinical features of DG (126 female, median age of 51 years, range 23–93 years) were retrospectively evaluated.

Results:  It was established that, in this population, the largest cohort yet reported, oral lichen planus was most common (70.5%) while mucous membrane pemphigoid (14%), pemphigus vulgaris (13%), linear IgA disease (1.6%), dermatomyositis (0.5%) and mixed connective tissue disease (0.5%) were less common.

Conclusion:  Oral lichen planus is the main disorder associated with DG. However, DG may be a feature of bullous disease and connective tissue disease.
Comparison of Line‐Drive and Push‐Pull Flushing Schemes
Authors: Boving T.B. , Blanford W.J. , McCray J.E. , Divine C.E. , Brusseau M.L.
Published: February 2008

The performance of cyclodextrin (CD)‐enhanced push‐pull (PP) and line‐drive (LD) approaches to remediation of a site contaminated with a multicomponent dense nonaqueous phase liquid (DNAPL) present in a surficial sandy aquifer was evaluated in this field study. The treatment techniques were compared to each other and to the projected performance of a conventional water‐flushing system. Performance was assessed based on contaminant mass removed per unit volume of extraction solution and per unit time of operation. As expected, the CD‐enhanced LD and PP approaches to remediation were more efficient than conventional flushing with water. Between the two techniques, the PP approach performed 1.5 to 2 times better than the LD approach, particularly for higher DNAPL saturation of the source zone. This result suggests that forcing the flushing solution directly into and through the DNAPL source zone minimized flow bypassing and consequently resulted in a more efficient transfer of contaminant mass between the DNAPL phase and the flushing solution. Nonuniform treatment zone contaminant concentrations and changes in contaminant composition influenced the treatment performances, but these effects were small and still permitted the comparison of successive tests. Although CD was used as the solubility‐enhancing flushing agent in this study, it is likely that the results can be transferred to other chemically enhanced flushing technologies that use, for example, surfactants or alcohols.
Effects of Hydraulic Variables and Well Construction on Horizontal Borehole Flowmeter Measurements
Authors: Wu Y.‐S. , Lee C.‐H. , Yu J.‐L.
Published: February 2008

Due to differences in hydraulic conductivity and effects of well construction geometry, ground water flow in a wellbore typically differs from the flow field in the surrounding porous media. These differences must be well understood to use borehole flowmeters for ground water velocity and direction measurement. In this work, a lab‐scale sand tank test and a small‐scale field test were conducted to explore the differences between average linear velocities in the borehole and in the formation and flow directions. In the sand tank test, six variables were studied, colloidal borescope meters were used to measure flows in wellbores, and correction factors (= linear velocity in center of borehole/average linear velocity in the surrounding formation away from the well) for flow velocity were determined. In these tests, correction factors ranged between 3 and 6 for all conditions studied, without any strong correlation between correction factor and most of the variables studied. The most obvious relationship was that the correction factor appeared to increase with decreasing ground water velocity; when the flow velocity decreased to near or below 2 × 10−3 m/s, the value of the correction factors increased to equal or exceed 10. In the field test, two different types of flowmeter—the colloidal borescope meters and heat‐pulse flowmeters—were used under natural gradient and forced hydraulic gradient conditions. Field test results showed no differences in correction factors when either type of borehole meters or hydraulic conditions were used. The correction factors remained between 3.9 and 6.0 consistent with other previously published results. The flow directions measured by borehole flowmeters in wellbores were consistent with the flow directions in the geological formation. The results of the sand tank test indicated the larger well screen diameter and the lower hydraulic gradient seem to have the more accurate flow directions measured by borehole flowmeters. Field and lab measurements suggested that the errors of flow direction were less than 15°, with a maximum of 21°.
Influence of Sodium Chloride and Glucose on the Aggregation Behavior of Heat‐Denatured Ovalbumin Investigated with a Multiangle Laser Light Scattering Technique
Authors: Choi S.J. , Moon T.W.
Published: February 2008

ABSTRACT: The molecular characteristics of ovalbumin aggregates formed by heating with NaCl and glucose were investigated with a multi‐angle laser light scattering system. The presence of NaCl and glucose affected the formation and molecular structure of the aggregates. Specifically, glucose increased the denaturation temperature of ovalbumin due to thermal stabilization of the native state of ovalbumin, regardless of the content of added NaCl. The surface hydrophobicity of the aggregates was increased by the addition of NaCl, which induced the denaturation of ovalbumin at a lower temperature. Aggregates with a larger weight‐average molar mass (Mw) and root mean square radius (Rg) formed from heat‐denatured ovalbumin with NaCl and glucose. The presence of NaCl during heat denaturation caused the formation of aggregates with a largerMw(1.9 × 105and 3.5 × 106g/mol for 0 and 10 mM NaCl, respectively) andRg(14.8 and 80.4 nm for 0 and 10 mM NaCl, respectively). Over a certain amount of NaCl, the addition of more glucose resulted in the formation of more aggregates with greaterMwandRgvalues. In sum, the thermostability of ovalbumin was affected primarily by glucose, but the molecular characteristics of the soluble aggregates formed by heat denaturation varied primarily with NaCl content.
Effect of Food Characteristics, Storage Conditions, and Electron Beam Irradiation on Active Agent Release from Polyamide‐Coated LDPE Films
Authors: Han J. , Castell‐Perez M.E. , Moreira R. G.
Published: February 2008

ABSTRACT:  We investigated the effect of electron beam irradiation, storage conditions, and model food pH on the release characteristics of trans‐cinnamaldehyde incorporated into polyamide‐coated low‐density polyethylene (LDPE) films. Active agent release rate on irradiated films (up to 20.0 kGy) decreased by 69% compared with the nonirradiated controls, from 0.252 to 0.086 μg/mL/h. Storage temperature (4, 21, and 35 °C) and pH (4, 7, and 10) of the food simulant solutions (10% aqueous ethanol) affected the release rate of trans‐cinnamaldehyde. As expected, antimicrobial release rate decreased to 0.013 μg/mL/h at the refrigerated temperature (4 °C) compared to the higher temperatures (0.029 and 0.035 μg/mL/h at 21 and 35 °C). The fastest release rate occurred when exposed to the acidic food simulant solution (pH 4). In aqueous solution, trans‐cinnamaldehyde was highly unstable to ionizing radiation, with loss in concentration from 24.50 to 1.36 μg/mL after exposure to 2.0 kGy. Fourier transform infrared (FTIR) analysis revealed that exposure to ionizing radiation up to 10.0 kGy did not affect the structural conformation of LDPE/polyamide films and the trans‐cinnamaldehyde in the films, though it induced changes in the functional group of trans‐cinnamaldehyde when dose increased up to 20.0 kGy. Studies with a radiation‐stable compound (naphthalene) showed that ionizing radiation induced the crosslinking in polymer networks of LDPE/polyamide film and caused slow and gradual release of the compound. This study demonstrated that irradiation serves as a controlling factor for release of active compounds, with potential applications in the development of antimicrobial packaging systems.
Fermentation of Reconstituted Skim Milk Supplemented with Soy Protein Isolate by Probiotic Organisms
Authors: Pham T.T. , Shah N.P.
Published: February 2008

ABSTRACT:  Utilization of lactose and production of organic acid were determined in reconstituted skim milk (RSM) and RSM supplemented with soy protein isolate (SPI) (RSMS) by 6 probiotic organisms, including L. acidophilus 4461, L. acidophilus 4962, L. casei 290, L. casei 2607, B. animalis subsp. lactis bb12, and B. longum 20099. The viable counts of probiotic organisms of RSM and RSMS were enumerated and pH measured during fermentation. Our results showed that 3% to 10% more lactose was utilized by all the 6 probiotic microorganisms from RSMS than RSM. All 6 probiotic organisms produced significantly more acetic acid in RSMS than RSM. However, the viable microbial populations in RSMS were lower than those in RSM due to lower pH of the former. It appears that addition of SPI enhanced lactose utilization and acetic acid production but slightly reduced the lactic acid production and the growth of probiotic microorganisms.
Stability of Isoflavone Daidzein and Genistein in Riboflavin, Chlorophyllb, or Methylene Blue Photosensitization
Authors: Yang Seungok , Lee Seungwook , Chung Hyun , Lee Jaehwan
Published: February 2008

ABSTRACT: Effects of photosensitizers including riboflavin, chlorophyllb, or methylene blue on the stability of daidzein and genistein were studied in model systems by high‐performance liquid chromatography (HPLC). Concentration of daidzein and genistein in 80% methanol with riboflavin under light for 7 h was significantly decreased with the apparent 1st‐order rate constants of 0.234 and 0.193/h, respectively, (P< 0.05), while those without riboflavin under light did not change significantly (P> 0.05). The stability of isoflavone aglycones in the dark did not change significantly irrespective of the presence of riboflavin (P> 0.05). The concentrations of daidzein and genistein in chlorophyllbor methylene blue model systems under light were not significantly different from those in the dark for 7 h (P> 0.05). Addition of sodium azide increased the stability of daidzein and genistein in riboflavin photosensitization with concentration dependent manner. However, the protective effects of β‐carotene addition on the photodegradation of isoflavones were not high. The stability difference of daidzein and genistein in riboflavin photosensitization may be due to the high reactivity of riboflavin through type I pathway, although singlet oxygen may be involved in part.
Heat-Induced Changes in the Mechanical Behavior of Passive Coronary Arteries
Authors: Kang T. , Resar J. , Humphrey J. D.
Published: February 2008

We performed in vitro pressure-diameter and axial force-length experiments on nondiseased, passive bovine coronary arteries subjected to bath temperatures from 21 to 80° C for 90 s to 4 hr. Over the strain ranges studied, we found that: (a) vessel behavior remained the same over 20 min of testing at 21 to 55° C, (b) vessels stiffened multiaxially after 5 min of exposure to 60° C and continued to stiffen over 20 min of testing, (c) dramatic multiaxial vessel stiffening and shrinkage occurred after 90 s of exposure to 70 and 80° C, and (d) heat-induced changes at 70° C depended on the intraluminal pressure during heating. Thus, passive bovine coronary arteries exhibit a complex thermomechanical behavior that depends on the temperature, duration of thermal exposure, and the mechanical loads applied during heating.
Direct In Vitro Determination of the Patellofemoral Contact Force for Normal Knees
Authors: Singerman R. , Berilla J. , Davy D. T.
Published: February 2008

Results of the direct in vitro measurement of the full three-dimensional representation of the patellofemoral contact force and the point of application on the patella of the resultant contact force for eleven normal knees are presented. The applied knee moment versus flexion angle pattern was similar to that experienced when rising from a chair. There was a wide variability of the details of the patellofemoral force interaction among the specimens tested. The magnitude of the resultant contact force increased approximately linearly with flexion angle for some knees while in others the force leveled off or decreased at higher flexion angles. The change in direction of the resultant contact force with respect to the patella was relatively small compared to the angular rotation of the patella. The medial-lateral component of the contact force exhibited substantial variability among knees. The direction of this force (medially or laterally directed) varied among knees and, in some knees, changed direction as a function of flexion angle. The point of application on the patella of the resultant contact force migrated superiorly from 20 to 90 deg flexion. Above 90 deg flexion this point tended to migrate inferiorly. The only significant and consistent effect of varying the direction of the quadriceps extension force was a change in the medial-lateral component of the contact force. In all cases, the tendency to sublux laterally increased when the extensor force was rotated 10 deg laterally and decreased when the extensor force was rotated 10 deg medially.
A Three-Dimensional Computational Investigation of Intraventricular Fluid Dynamics: Examination Into the Initiation of Systolic Anterior Motion of the Mitral Valve Leaflets
Authors: Yoganathan Ajit P. , Lemmon Jack D. , Kim Young H. , Levine Robert A. , Vesier Carol C.
Published: February 2008

Systolic anterior motion of the mitral valve leaflets (SAM) is a disease of the left ventricle which results from an abnormal force balance on the mitral valve. The mechanism by which is initiated is poorly understood, and a complete understanding of this mechanism is required for effective treatment of SAM. There are currently two theories for the initiation mechanism of SAM, the Venturi hypothesis and the altered papillary muscle-mitral valve geometry theory (PM-MV). The Venturi hypothesis states that abnormally high ejection velocities create Venturi forces which initiate SAM. The PM-MV theory asserts that SAM is the result of abnormally distributed chordal forces which are incapable of preventing SAM. To investigate the initiation mechanism of SAM, a computer model of early systolic flow in an anatomically-correct human left ventricle was developed using Peskin’s immersed boundary algorithm. The computer model was used to determine the effect of chordal force distribution and septal thickness of the intraventricular flow field. The results show that the degree of SAM is inversely proportional to the amount of chordal restraint applied to the central portion of the leaflets. Also, the results support the PM-MV theory and indicate the following: (i) fluid forces capable of initiating SAM as always present in a normal human ventricle; (ii) SAM does not occur normally because of the presence of chordal forces on the central portion of the mitral leaflet; (Hi) SAM will occur when these central chordal forces are sufficiently low; (iv) the extent of SAM is inversely proportional to these central chordal forces; and (v) Venturi forces alone can not cause SAM.
The Mechanical Behavior of a Mammalian Lung Alveolar Duct Model
Authors: Denny E. , Schroter R. C.
Published: February 2008

A model for the mechanical properties of an alveolar duct is analyzed using the finite element method. Its geometry comprises an assemblage of truncated octahedral alveoli surrounding a longitudinal air duct. The amounts and distributions of elastin and collagen fiber bundles, modeled by separate stress-strain laws, are based upon published data for dogs. The surface tension of the air-liquid interface is modeled using an area-dependent relationship. Pressure-volume curves are computed that compare well with experimental data for both saline-filled and air-filled lungs. Pressure-volume curves of the separate elastin and collagen fiber contributions are similar in form to the behavior of saline-filled lungs treated with either elastase or collagenase. A comparison with our earlier model, based upon a single alveolus, shows the duct to have a behavior closer to reported experimental data.
Cancellous Bone Young’s Modulus Variation Within the Vertebral Body of a Ligamentous Lumbar Spine—Application of Bone Adaptive Remodeling Concepts
Authors: Goel Vijay K. , Ramirez Steven A. , Kong Weizeng , Gilbertson Lars G.
Published: February 2008

Bone remodeling theory based on strain energy density (SED) as the feedback control variable was used in conjunction with the finite element method to analyze the shape of the vertebral bodies within the ligamentous motion segment. The remodeling theory was once again applied to the altered two motion segments model to predict the Young’s modulus distribution of the cancellous bone within the vertebral bodies. A three-dimensional finite element model of the two motion segments ligamentous lumbar spine (L3-5) was developed. Bone remodeling response (external as well as internal) of the motion segments to a uniaxial compressive load of 424.7 N was studied. The external shape of the converged model matched the normal shape of a vertebral body. The internal remodeling resulted in regional cancellous bone Young’s moduli (or bone density) distributions similar to those reported in the literature; posterocentral regions of the vertebrae were predicted to have greater values of the elastic modulus than that of the outer regions. The results of the present study suggest that vertebral body assumes an adequate/optimum structure in terms of both its shape and its elastic moduli distribution within the cancellous region in response to the applied load. Extensions of the present model and its clinically relevant applications are discussed.
A Constitutive Relationship for Large Deformation Finite Element Modeling of Brain Tissue
Authors: Mendis K. K. , Stalnaker R. L. , Advani S. H.
Published: February 2008

Finite element modeling of the finite deformation response of soft tissues presents a formidable challenge. This paper discusses the use of a large strain constitutive relationship suitable for modeling brain tissue as well as other soft biological tissue. Available experimental data on the finite deformation response of brain tissue is used to characterize the constitutive properties. Analytical modeling and finite element simulations of the experiment are performed using the proposed constitutive formulation. The numerical results compare favorably with the experimental data.
Modeling and Simulation of Paraplegic Ambulation in a Reciprocating Gait Orthosis
Authors: Tashman S. , Zajac F. E. , Perkash I.
Published: February 2008

We developed a three dimensional, four segment, eight-degree-of-freedom model for the analysis of paraplegic ambulation in a reciprocating gait orthosis (RGO). Model development was guided by experimental analysis of a spinal cord injured individual walking in an RGO with the additional assistance of arm crutches. Body forces and torques required to produce a dynamic simulation of the RGO gait swing phase were found by solving an optimal control problem to track the recorded kinematics and ground reaction forces. We found that high upper body forces are required, not only during swing but probably also during double support to compensate for the deceleration of the body during swing, which is due to the pelvic thrust necessary to swing the leg forward. Other simulations showed that upper body forces and body deceleration during swing can be reduced substantially by producing a ballistic swing. Functional neuromuscular stimulation of the hip musculature during double support would then be required, however, to establish the initial conditions needed in a ballistic swing.
Dynamic Models for Sideways Falls From Standing Height
Authors: van den Kroonenberg A. J. , Hayes W. C. , McMahon T. A.
Published: February 2008

Despite our growing understanding of the importance of fall mechanics in the etiology of hip fracture, previous studies have largely ignored the kinematics and dynamics of falls from standing height. Beginning from basic principles, we estimated peak impact force on the greater trochanter in a sideways fall from standing height. Using a one degree-of-freedom impact model, this force is determined by the impact velocity of the hip, the effective mass of that part of the body that is moving prior to impact, and the overall stiffness of the soft tissue overlying the hip. To determine impact velocity and effective mass, three different paradigms of increasing complexity were used: 1) a falling point mass or a rigid bar pivoting at its base; 2) two-link models consisting of a leg segment and a torso; and 3) three-link models including a knee. The total mechanical energy of each model before falling was equated to the total mechanical energy just prior to impact in order to estimate the hip impact velocity. In addition, the configuration of the model just before impact was used to estimate the effective mass. Our model predictions were compared with the results of an earlier experimental study with young subjects falling on a 10-inch thick mattress. Values from literature were used to estimate the soft tissue stiffness. For the models, predicted values for hip impact velocity and effective mass ranged from 2.47 to 4.34 m/s and from 15.9 to 70.0 kg, respectively. Predicted values for the peak force applied to the greater trochanter ranged from 2.90k to 9.99k N. Based on comparisons to the experimental falls, impact velocity and impact force were best predicted by a simple two-link model with the trunk at 45 degrees to the vertical at impact. A three-link model with a quadratic spring incorporated in the knee of the model was the best predictor of effective mass. Using our most accurate model, the peak impact force was 2.90k N for a 5th percentile female and 4.26k N for a 95th percentile female, thereby confirming the widely held perception that “the bigger they are, the harder they fall.”
A Six-Degree-of-Freedom Test System for the Study of Joint Mechanics and Ligament Forces
Authors: Hollis J. M.
Published: February 2008

A joint testing system was designed to transmit a specified motion or force to a joint in all six degrees of freedom (d.o.f.) using a spatial linkage system for position feedback. The precise reproducibility of position provided by this method of position feedback allows determination of in situ ligament forces for external joint loadings. Load on the structure of interest is calculated from six d.o.f. load cell output after the loaded position is reproduced with all other structures removed. In a test of this system, measured loads showed good agreement with applied loads.
Physical Response of Collagen Gels to Tensile Strain
Authors: O¨zerdem Baris , To¨zeren Aydin
Published: February 2008

Extra cellular matrix, which provides physical support to epithelial and endothelial cells and to fibroblasts, also affects a number of important cell biological phenomena, such as cell motility and angiogenesis. Although type I collagen has long been recognized as the primary structural component of the extra cellular matrix, little is known about the physical properties of collagen gels. In this study, we used a servo-controlled linear actuator to impose quick stretches on dilute collagen gels. An axial strain imposed on the gel within few milliseconds resulted in a rapid development of gel tension in the direction of the strain. The gel tension then decayed toward a steady-state value within several seconds. The instantaneous gel stiffness increased and the relaxed gel stiffness decreased with the extent of gel stretching. These rheological parameters were also dependent on the density of the collagen network. Taken together the results indicated that collagen gels possess nonlinear viscoelastic properties.
Hemodynamics of the Fontan Connection: An In-Vitro Study
Authors: Kim Young H. , Walker P. G. , Fontaine A. A. , Panchal S. , Ensley A. E. , Oshinski J. , Sharma S. , Ha B. , Lucas C. L. , Yoganathan A. P.
Published: February 2008

The Fontan operation is one in which the right heart is bypassed leaving the left ventricle to drive the blood through both the capillaries and the lungs, making it important to design an operation which is hemodynamically efficient. The object here was to relate the pressure in Fontan connections to its geometry with the aim of increasing the hemodynamically efficiency. From CT or magnetic resonance images, glass models were made of realistic atrio-pulmonary (AP) and cavo-pulmonary (CP) connections in which the right atrium and/or ventricle are bypassed. The glass models were connected to a steady flow loop and flow visualization, pressure and 3 component LDA measurements made. In the AP model the large atrium and curvature of the conduit created swirling patterns, the magnitude of which was similar to the axial velocity. This led to an inefficient flow and a subsequent large pressure loss (780 Pa). In contrast, the CP connection with a small intra-atrial chamber had reduced swirling and a significantly smaller pressure loss (400 Pa at 8 l.min) and was therefore a more efficient connection. There were, however, still pressure losses and it was found that these occurred where there was a large bending of the flow, such as from the superior vena cava to the MPA and from the MPA to the right pulmonary artery.
Anti-BK Virus Activity of Nucleoside Analogs
Authors: Randhawa Parmjeet , Zemlicka Jiri , Sauerbrei Andreas , Meier Chris , Hostetler Karl Y. , Beadle James R. , Farasati Noush Afarin , Huang Yuchen , Bradley Matthews
Published: February 2008

Polyomavirus BK is an important pathogen in transplant recipients with no effective therapy. This study demonstrates that alkoxyalkyl esters of (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine and fatty acid derivatives of 9-[2-(phosphonomethyoxy)ethyl]adenine (P393 and P405) are potent and selective inhibitors of BK virus replication in vitro, with a 50% effective concentration in the micromolar-to-nanomolar range.
Attenuated Vancomycin Bactericidal Activity against
Staphylococcus aureus hemB
Mutants Expressing the Small-Colony-Variant Phenotype
Authors: Tsuji Brian T. , von Eiff Christof , Kelchlin Pamela A. , Forrest Alan , Smith Patrick F.
Published: February 2008

The in vitro bactericidal activities of vancomycin against
Staphylococcus aureus hemB
mutants displaying the small-colony-variant phenotype and their parental strains were evaluated. Vancomycin killing activities against
hemB
mutants were markedly attenuated, demonstrating approximately 50% less effect, a result which was well described by a Hill-type pharmacodynamic model.