bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods for confidence interval estimation of a ratio parameter with application to location quotients
Authors: Beyene Joseph , Moineddin Rahim
Published: October 2005

Background

The location quotient (LQ) ratio, a measure designed to quantify and benchmark the degree of relative concentration of an activity in the analysis of area localization, has received considerable attention in the geographic and economics literature. This index can also naturally be applied in the context of population health to quantify and compare health outcomes across spatial domains. However, one commonly observed limitation of LQ is its widespread use as only a point estimate without an accompanying confidence interval.

Methods

In this paper we present statistical methods that can be used to construct confidence intervals for location quotients. The delta and Fieller's methods are generic approaches for a ratio parameter and the generalized linear modelling framework is a useful re-parameterization particularly helpful for generating profile-likelihood based confidence intervals for the location quotient. A simulation experiment is carried out to assess the performance of each of the analytic approaches and a health utilization data set is used for illustration.

Results

Both the simulation results as well as the findings from the empirical data show that the different analytical methods produce very similar confidence limits for location quotients. When incidence of outcome is not rare and sample sizes are large, the confidence limits are almost indistinguishable. The confidence limits from the generalized linear model approach might be preferable in small sample situations.

Conclusion

LQ is a useful measure which allows quantification and comparison of health and other outcomes across defined geographical regions. It is a very simple index to compute and has a straightforward interpretation. Reporting this estimate with appropriate confidence limits using methods presented in this paper will make the measure particularly attractive for policy and decision makers.
Serum hyaluronate as a non-invasive marker of hepatic fibrosis and inflammation in HBeAg-negative chronic hepatitis B
Authors: Montazeri Ghodrat , Estakhri Arezoo , Mohamadnejad Mehdi , Nouri Negin , Montazeri Farhad , Mohammadkani Ashraf , Derakhshan Mohammad Hossain , Zamani Farhad , Samiee Shahram , Malekzadeh Reza
Published: October 2005

Background

HBV infection is a serious global heath problem. It is crucial to monitor this disease more closely with a non-invasive marker in clinical trials. We aimed to evaluate the predictive value of serum hyaluronate for the presence of extensive liver fibrosis and inflammation.

Methods

28 healthy volunteers and 65 patients with HBeAg negative chronic hepatitis B were enrolled. Liver biopsies scored according to Ishak system. Association of serum hyaloronate with liver fibrosis and inflammation were assessed, and cut off points for serum hyaluronate levels were identified by receiver operating characteristics (ROC) curves and their values for prediction of fibrosis and inflammation were assessed.

Results

In patients with CHB serum hyaluronate had the most significant correlation and predictive values for the liver fibrosis and inflammation comparing to the other variables. At the cut off point of 126.4 ngm/ml it could discriminate extensive fibrosis from milder ones with sensitivity of 90.9% and specificity of 98.1%. With the same value it could discriminate extensive inflammation from their milder counterparts with sensitivity of 63.6% and specificity of 92.6%.

Conclusion

Serum hyaluronate was the best predictor of extensive liver fibrosis and inflammation and it could discriminate subgroups of patients with chronic hepatitis B. It could be used as a non-invasive test to monitor these patients more closely with developing anti viral agents in clinical trials.
The McKenzie method for the management of acute non-specific low back pain: design of a randomised controlled trial [ACTRN012605000032651]
Authors: Machado Luciana AC , Maher Chris G , Herbert Rob D , Clare Helen , McAuley James
Published: October 2005

Background

Low back pain (LBP) is a major health problem. Effective treatment of acute LBP is important because it prevents patients from developing chronic LBP, the stage of LBP that requires costly and more complex treatment.

Physiotherapists commonly use a system of diagnosis and exercise prescription called the McKenzie Method to manage patients with LBP. However, there is insufficient evidence to support the use of the McKenzie Method for these patients. We have designed a randomised controlled trial to evaluate whether the addition of the McKenzie Method to general practitioner care results in better outcomes than general practitioner care alone for patients with acute LBP.

Methods/design

This paper describes the protocol for a trial examining the effects of the McKenzie Method in the treatment of acute non-specific LBP. One hundred and forty eight participants who present to general medical practitioners with a new episode of acute non-specific LBP will be randomised to receive general practitioner care or general practitioner care plus a program of care based on the McKenzie Method. The primary outcomes are average pain during week 1, pain at week 1 and 3 and global perceived effect at week 3.

Discussion

This trial will provide the first rigorous test of the effectiveness of the McKenzie Method for acute non-specific LBP.
Laparoscopic repair of high rectovaginal fistula: Is it technically feasible?
Authors: Kumaran Saravanan S , Palanivelu Chinnusamy , Kavalakat Alfie J , Parthasarathi Ramakrishnan , Neelayathatchi Murugayyan
Published: October 2005

Background

Rectovaginal fistula (RVF) is an epithelium-lined communication between the rectum and vagina. Most RVFs are acquired, the most common cause being obstetric trauma. Most of the high RVFs are repaired by conventional open surgery. Laparoscopic repair of RVF is rare and so far only one report is available in the literature.

Methods

We present a case of high RVF repaired by laparoscopy. 56-year-old female who had a high RVF following laparoscopic assisted vaginal hysterectomy was successfully operated laparoscopically. Here we describe the operative technique and briefly review the literature.

Results

The postoperative period of the patient was uneventful and after a follow up of 6 months no recurrence was found.

Conclusion

Laparoscopic repair of high RVF is feasible in selected patients but would require proper identification of tissue planes and good laparoscopic suturing technique.
Development and validation of a quality of life questionnaire for patients with colostomy or ileostomy
Authors: Prieto Luis , Thorsen Hanne , Juul Kristian
Published: October 2005

Background

Quality of life of stoma patients is increasingly being addressed in clinical trials. However, the instruments used in the majority of these studies have not been validated specifically for stoma patients. The aim of this paper is to describe the development and validation of a quality-of-life instrument, "Stoma-QOL", specifically for patients with colostomy or ileostomy.

Methods

Potential items were formulated in English on the basis of the results of a series of semi-structured interviews with 169 adult stoma patients. The process resulted in a preliminary 37-item version, which was translated into French, German, Spanish and Danish, and administered repeatedly to 182 patients with colostomy or ileostomy. A psychometric selection of items was performed through Rasch Analysis. The measurement properties of the final questionnaire version were subsequently tested.

Results

The 20 items in the final questionnaire covered four domains – sleep, sexual activity, relations to family and close friends, and social relations to other than family and close friends. These items were found to define a unidimensional variable according to Rasch specifications (Infit MNSQ < 1.3). Internal consistency reliability calculated as Cronbach's alpha was 0.92, i.e., highly reliable. Spearman's correlation coefficients of scores across times of administration was >0.88 (p < 0.01), indicating a high test-retest reliability. Item calibrations by country calculated as ICC were 0.81 (0.67–0.91 95% CI), confirming cross-cultural comparability across the European countries included in the study.

Conclusion

Given the adequacy of the metric properties of the Stoma-QOL suggested by the psychometric analyses, this study confirms the suitability of the instrument in clinical practice and in clinical research.
“Personality and Social Psychology”: Retrospections and Aspirations
Authors: Smith M. Brewster
Published: October 2005

Drawing on 6 decades of participant observation in personality and social psychology, this article provides comments on the qualities of the founding generation at mid-20th century (e.g., Allport, Lewin, Murphy, Murray, Newcomb, and Sherif). Their breadth, commitment to a humane science, and interest in its social applications have since been in short supply. The juncture of personality psychology and social psychology has become problematic. Reasons for this are explored. Holistic personology may presentlyfind a more congenial setting in life span developmental psychology than in social psychology.
Why Are Modern Families Small? Toward an Evolutionary and Cultural Explanation for the Demographic Transition
Authors: Newson Lesley , Postmes Tom , Lea S. E. G , Webley Paul
Published: October 2005

As societies modernize, they go through what has become known as “the demographic transition;” couples begin to limit the size of their families. Models to explain this change assume that reproductive behavior is either under individual control or under social control. The evidence that social influence plays a role in the control of reproduction is strong, but the models cannot adequately explain why the development of small family norms always accompanies modernization. We suggest that the widening of social networks, which has been found to occur with modernization, is sufficient to explain the change in reproductive norms if it is assumed that (a) advice and comment on reproduction that passes among kin is more likely to encourage the creation of families than that which passes among nonkin and (b) this advice and comment influence the social norms induced from the communications. This would, through a process of cultural evolution, lead to the development of norms that make it increasingly difficult to have large families.
Loss ofDrosophila borealincauses polyploidy, delayed apoptosis and abnormal tissue development
Authors: Hanson Kirsten K. , Kelley Ann C. , Bienz Mariann
Published: October 2005

The chromosomal passenger complex (CPC) is a key regulator of mitosis in many organisms, including yeast and mammals. Its components co-localise at the equator of the mitotic spindle and function interdependently to control multiple mitotic events such as assembly and stability of bipolar spindles,and faithful chromosome segregation into daughter cells. Here, we report the first detailed characterisation of a CPC mutation in Drosophila,using a loss-of-function allele of borealin (borr). Like its mammalian counterpart, Borr colocalises with the CPC components Aurora B kinase and Incenp in mitotic Drosophila cells, and is required for their localisation to the mitotic spindle. borr mutant cells show multiple mitotic defects that are consistent with loss of CPC function. These include a drastic reduction of histone H3 phosphorylation at serine 10 (a target of Aurora B kinase), a pronounced attenuation at prometaphase and multipolar spindles. Our evidence suggests that borr mutant cells undergo multiple consecutive abnormal mitoses, producing large cells with giant nuclei and high ploidy that eventually apoptose. The delayed apoptosis of borr mutant cells in the developing wing disc appears to cause non-autonomous repair responses in the neighbouring wild-type epithelium that involve Wingless signalling, which ultimately perturb the tissue architecture of adult flies. Unexpectedly, during late larval development, cells survive loss of borr and develop giant bristles that may reflect their high degree of ploidy.
microPrimer: the biogenesis and function of microRNA
Authors: Du Tingting , Zamore Phillip D.
Published: October 2005

Discovered in nematodes in 1993, microRNAs (miRNAs) are non-coding RNAs that are related to small interfering RNAs (siRNAs), the small RNAs that guide RNA interference (RNAi). miRNAs sculpt gene expression profiles during plant and animal development. In fact, miRNAs may regulate as many as one-third of human genes. miRNAs are found only in plants and animals, and in the viruses that infect them. miRNAs function very much like siRNAs, but these two types of small RNAs can be distinguished by their distinct pathways for maturation and by the logic by which they regulate gene expression.
MicroRNA functions in animal development and human disease
Authors: Alvarez-Garcia Ines , Miska Eric A.
Published: October 2005

Five years into the `small RNA revolution' it is hard not to share in the excitement about the rapidly unravelling biology of microRNAs. Since the discovery of the first microRNA gene, lin-4, in the nematode Caenorhabditis elegans, many more of these short regulatory RNA genes have been identified in flowering plants, worms, flies, fish, frogs and mammals. Currently, about 2% of the known human genes encode microRNAs. MicroRNAs are essential for development and this review will summarise our current knowledge of animal microRNA function. We will also discuss the emerging links of microRNA biology to stem cell research and human disease, in particular cancer.
Restrictedteashirtexpression confers eye-specific responsiveness to Dpp and Wg signals during eye specification inDrosophila
Authors: Bessa José , Casares Fernando
Published: October 2005

In Drosophila, the eye primordium is specified as a subdomain of the larval eye disc. Here, we show that the Zn-finger transcription factor teashirt (tsh) marks the region of the early eye disc where the eye primordium will form. Moreover, tsh misexpression directs eye primordium formation in disc regions normally destined to form head capsule,something the eye selector genes eyeless (ey) and twin of eyeless (toy) are unable to do on their own. We present evidence that tsh induces eye specification, at least in part, by allowing the activation of eye specification genes by the wingless(wg) and decapentaplegic (dpp) signaling pathways. Under these conditions, though, terminal eye differentiation proceeds only if tsh expression is transient.
Sonic hedgehog maintains the identity of cortical interneuron progenitors in the ventral telencephalon
Authors: Xu Qing , Wonders Carl P. , Anderson Stewart A.
Published: October 2005

Fate determination in the mammalian forebrain, where mature phenotypes are often not achieved until postnatal stages of development, has been an elusive topic of study despite its relevance to neuropsychiatric disease. In the ventral telencephalon, major subgroups of cerebral cortical interneurons originate in the medial ganglionic eminence (MGE), where the signaling molecule sonic hedgehog (Shh) continues to be expressed during the period of neuronogenesis. To examine whether Shh regulates cortical interneuron specification, we studied mice harboring conditional mutations in Shh within the neural tube. At embryonic day 12.5, NestinCre:ShhFl/Flmutants have a relatively normal index of S-phase cells in the MGE, but many of these cells do not co-express the interneuron fate-determining gene Nkx2.1. This effect is reproduced by inhibiting Shh signaling in slice cultures, and the effect can be rescued in NestinCre:ShhFl/Fl slices by the addition of exogenous Shh. By culturing MGE progenitors on a cortical feeder layer, cell fate analyses suggest that Shh signaling maintains Nkx2.1 expression and cortical interneuron fate determination by MGE progenitors. These results are corroborated by the examination of NestinCre:ShhFl/Fl cortex at postnatal day 12, in which there is a dramatic reduction in cell profiles that express somatostatin or parvalbumin. By contrast, analyses of Dlx5/6Cre:SmoothenedFl/Flmutant mice suggest that cell-autonomous hedgehog signaling is not crucial to the migration or differentiation of most cortical interneurons. These results combine in vitro and ex vivo analyses to link embryonic abnormalities in Shh signaling to postnatal alterations in cortical interneuron composition.
Switching Plane Design for the Sliding Mode Control of Systems with Elastic Input Constraints
Authors: Bartoszewicz A , Nowacka A
Published: October 2005

In this paper a new sliding mode control algorithm for the third-order non-linear, time-varying, uncertain system subject to unknown disturbance is proposed. Since the conventional input constraints expressed by inequalities are often impractical, in this paper the situation is considered where the input signal is subject to elastic constraint. It is assumed that the threshold value of the system input signal is known and exceeding this value is undesirable but possible if justified by essential improvement of the system performance. The proposed algorithm employs a time-varying switching plane. At the initial time the plane passes through the point determined by the system initial conditions in the error state space and afterwards moves with a constant velocity to the origin of the space. The plane is designed in such a way that fast error convergence is achieved using limited control input. By this means, the reaching phase is eliminated, insensitivity of the system to external disturbance is ensured from the very beginning of the control action, and fast, monotonic error convergence to zero is achieved. Moreover, it is demonstrated that the conventional input constraint expressed by an inequality is a limit case of the elastic constraint considered in the paper.
Modelling and Control of a Hydraulically Actuated Two-Degree-of-Freedom Inertial Platform
Authors: Yeh T-J , Su C-Y , Wang W-J
Published: October 2005

This paper investigates modelling and control issues associated with a two-degree-of-freedom inertial platform for naval applications. In the modelling part, the dynamics of the system are physically characterized and then experimentally identified. It is found that due to the inverted-pendulum structure and the use of hydraulic actuators, the system is open-loop unstable and exhibits different frequency responses when the amplitude of the input signal changes. Moreover, the identification experiment reveals that the inclinometer used has a major resonant peak that will limit the control system performance. Therefore, a complimentary filter scheme is proposed to condition the sensor signals so as to produce a more acceptable absolute-angle measurement. In the control part, two proportional-integral-derivative (PID) controllers, whose control parameters are computed using a non-linear optimization scheme to achieve optimal disturbance rejection with reasonable robustness and noise sensitivity properties, are respectively designed for the pitch and the roll subsystems. Experimental results indicate that when the platform's base frame encounters a biaxial sea-wave motion, the resulted control system can attenuate the vibration to within 10 per cent.
Adaptive Inverse-Dynamic and Neuro-Inverse-Dynamic Active Vibration Control of a Single-Link Flexible Manipulator
Authors: Shaheed M H , Poerwanto H , Tokhi M O
Published: October 2005

This paper presents investigations into the development of adaptive inverse-dynamic and neuro-inverse-dynamic control strategies for a flexible manipulator system employing a combined collocated and non-collocated control structure. Collocated control is utilized to track the position of the system while the non-collocated inverse and neuro-inverse control are utilized to reduce the vibration of the system. The controllers are developed in two phases: a collocated position control loop using proportional-derivative feedback control is developed and combined first with an adaptive inverse non-collocated control loop using a recursive least-squares algorithm and then with a neuro-inverse model using a multi-layered perceptron neural network. The problem of instability of the non-collocated control loop arising from the non-minimum phase characteristics of the plant is solved in the former case by reflecting the non-invertible plant zeros into the stability region. In the case of the neuro-inverse model, the problem of instability of the control loop is accounted for through the neuro-inverse learning process. The performances of both the proposed control strategies are assessed within a simulation environment of a single-link flexible manipulator and it is demonstrated that a significant reduction in the level of structural vibration of the system is achieved with both techniques. The significance of the neuro-inverse model approach in achieving stable control is demonstrated.
Anisotropic Creep Behaviour of Bridgman Notch Specimens
Authors: Hyde T H , Jones I A , Peravali S , Sun W , Wang J G , Leen S B
Published: October 2005

A series of finite element anisotropic creep analyses of a Bridgman notch specimen have been performed. The anisotropic creep analysis is based on Hill's anisotropic yield model and the Norton creep law. An anisotropic parameter, p, is defined in order to quantify the degree of bulk material anisotropy which exists in a weld metal. The effects of p and the Norton stress exponent, n, on the stationary-state stresses, at the minimum cross-section of the notch, are presented. The material constants were chosen to include the practical range for engineering materials. Indications of the practical application of anisotropic analyses to welds are given.
The Carbon Fibre Structure for the Extreme Ultraviolet Imaging Spectrometer on the Solar-B Satellite
Authors: Castelli C , Hagood R , Mapson-Menard H , Winter B
Published: October 2005

The Extreme Ultraviolet Imaging Spectrometer (EIS) is a core instrument on the Japanese Solar-B mission and is due for launch in the summer of 2006. EIS is a 3.2 m long telescope employing grating optics and a pair of charge coupled device imaging cameras working in the extreme ultraviolet (EUV) region in two separate wavelength bands between 170-210 and 240-290 Å. To house all the telescope subsystems, a novel carbon fibre reinforced plastic structure was developed in collaboration with McLaren Composites Limited (UK) to meet a set of the demanding performance requirements in terms of dimensional stability, rigidity, and structural cleanliness as well as being able to survive the harsh launch environment of the Japanese M-V rocket. The final design was based on a honeycomb panel structure using stiff carbon fibre laminates. This case study describes some of the design challenges that were overcome for this project to produce the engineering, mechanical, and thermal models. Particular attention is given to the cleanliness control strategy to preserve the EUV optical throughput, the method of attachment to the spacecraft, and of optical subsystems as well as the instrument thermal design.
Centenary of tele-electrocardiography and telephonocardiography
Authors: Hjelm N M , Julius H W
Published: October 2005

In the history of electrocardiography the names of two physiologists stand out: Augustus Waller (1865–1922) and Willem Einthoven (1860–1927). Waller was the first to show that the beating heart produces a weak electric potential, which can be registered by a measuring device connected to electrodes attached to the skin. Einthoven developed a 'string' galvanometer, which was much faster and more sensitive than the system used by Waller. Einthoven's electrocardiograph was ready for use in 1903. To facilitate investigations of patients Einthoven connected his instrument to the Academic Hospital in Leyden, by a telephone line, as suggested by his engineering colleague Johannes Bosscha in Delft. The first successful tele-electrocardiogram was transmitted on Sunday 22 March 1905. The heart tones were registered by wiring a specially developed microphone placed on the subject's chest to another string galvanometer. The event was therefore a first both for tele-electrocardiography and for telephonocardiography. We are still awaiting the full-scale implementation of these achievements, 100 years later.
Kapillarelektrophorese in der Urin-Diagnostik Urine diagnostics by capillary electrophoresis
Authors: Marti Ulrich
Published: October 2005

Die Kapillarelektrophorese wird in einigen medizinischen Laboratorien seit mehreren Jahren zur Serumprotein-Elektrophorese verwendet. Der Einsatz der Kapillarelektrophorese in der Urindiagnostik beschränkt sich hingegen bis heute auf einige wenige Machbarkeitsstudien und Forschungsanwendungen. Diese Arbeit zeigt die Entwicklung der Kapillarelektrophorese bis zu einer gerade kürzlich erschienenen neuen Version einer kommerziellen Urinelektrophorese von Beckman Coulter. Man kann gespannt sein auf die ersten Berichte zu dieser Anwendung.
FISH-Diagnostik bei hämatologischen Neoplasien FISH diagnostics in hematological malignancies
Authors: Schoch Claudia , Kern Wolfgang , Schnittger Susanne , Haferlach Torsten
Published: October 2005

Die Technik der Fluoreszenz-in-situ-Hybridisierung (FISH) ist eine wichtige Methode, mit welcher Nukleinsäuresequenzen im Zellkern nachgewiesen werden können. Sie hat inzwischen in der Diagnostik und Klassifikation von hämatologischen Neoplasien einen festen Stellenwert. Die Durchführung eines diagnostischen FISH-Assays setzt voraus, dass die Sequenz der zu untersuchenden genetischen Region bekannt ist. Durch das zunehmende Wissen über die genetischen Veränderungen bei Tumoren konnten FISH-Assays für viele klinisch relevante Fragestellungen entwickelt werden. Grundsätzlich können für diverse Fragestellungen Sonden für eine FISH-Untersuchung hergestellt werden, sofern die zu untersuchende genetische Veränderung molekular aufgeklärt und prinzipiell mit FISH erfassbar ist, wie dies bei Deletionen, Translokationen, Duplikationen, Inversionen sowie Zugewinnen und Verlusten ganzer Chromosomen der Fall ist. Kleine Mutationen innerhalb eines einzelnen Gens sind nicht erfassbar. Viele für die Diagnostik wichtige Sonden sind bereits kommerziell erhältlich. Eine Empfehlung zum Einsatz der FISH-Diagnostik bei Leukämien wird zur Zeit im Rahmen des Europäischen Leukämie-Netzes erarbeitet (www.leukemia-net.org).
Differentiation of anti-platelet antibodies using microspheres and flow cytometry Einsatz von Mikrosphären und Durchflusszytometrie für die Differenzierung von Antithrombozyten-Antikörpern
Authors: Woetzel Michael , Schroeder Sabine , Sack Ulrich
Published: October 2005

Background: Allo- and autoantibodies against membrane structures of human platelets cause different types of immune thrombocytopenic disorders and require a sensitive and specific assay. The well-established monoclonal antibody immobilization of platelet antigens (MAIPA) test is able to distinguish between specifically bound immunoglobulins and coating of membrane-associated immune complexes; but MAIPA is rather time consuming and requires 2×107 platelets or more. For patients with very low platelet count and for little children with small blood volume, this may present a serious limitation.

Methods: The advantages of flow cytometry and of modern microsphere technology were combined with the selectivity of MAIPA to overcome the disadvantages of this assay. In order to compare different types of beads, i) goat anti-mouse Ig-labelled magnetic beads, ii) dyed polymeric beads designed for multiplexed assays, and iii) blanc polymeric beads have been studied. After loading with glycoprotein-specific or anti-β2-microglobulin-specific antibodies, these beads could be stored for months at 4°C without substantial loss of sensitivity.

Glycoproteins from platelet membranes, loaded with platelet-specific auto-/alloantibodies, have been immobilized on the bead surfaces during detergent solubilization of platelets prior to labelling with anti-human IgG-Biotin and Extravidin® R-Phycoerythrin.

Results: Magnetic beads are very easy to handle, show strong signals and low nonspecific binding, but have stronger autofluorescence compared to polymeric beads. Polymeric beads have low autofluorescence but stronger tendency to nonspecific binding. All types of beads tested in this study can be used to detect antibodies against platelet antigens, even against glycoproteins with low frequency such as anti-HPA-5 autoantibodies and with as few as 106 platelets or less. In multiplexed settings, they are suitable for simultaneous detection of multiple antibodies.

Conclusions: Flow cytometry is a fast and sensitive method for a bead-based MAIPA assay and is especially useful for low platelet counts and for pediatric patients. It is further improved by the use of multiplexed beads.
Thrombozytenaktivität und Thrombozyten-Leukozyten-Konjugate als Marker in der Sportmedizin Platelet activity and platelet-leukocyte conjugate formation as markers in sports medicine
Authors: Hilberg Thomas
Published: October 2005

Thrombozyten haben eine zentrale Bedeutung bei der Arteriosklerose und auch bei akuten thrombotischen Ereignissen. Körperliche Aktivität besitzt ein hohes Potential zur Vermeidung von Gefäßerkrankungen, dagegen wird intensiven Belastungen ein mögliches Risikopotential bei der Auslösung kardiovaskulärer Ereignisse zugeschrieben. Bei den notwendigen Untersuchungen thrombozytärer Funktionszustände nach körperlicher Belastung und Training werden zunehmend flowzytometrische Methoden eingesetzt, weil diese Technik die Möglichkeit impliziert, Veränderungen direkt auf der Oberfläche von Thrombozyten zu verifizieren. Da diese Veränderungen nach körperlichen Belastungen recht moderat ausfallen, sind Verfahren mit hoher Sensitivität notwendig. Zur Untersuchung dieser Veränderungen wurden vier Assays aufgebaut: a) Spontanexpression von Aktivierungsantigenen, b) Stimulationsassay, c) Thrombozyten-Leukozyten-Konjugate spontan und d) stimuliert.

In einigen Untersuchungen konnte eine erhöhte CD62P- und PAC-1-Expression auf der Oberfläche von Thrombozyten nach körperlicher Belastung bei Gesunden nachgewiesen werden. Während die Untersuchungen der CD62P-Expression auf unstimulierten Thrombozyten nach körperlicher Belastung bei geringen Veränderungen uneinheitliche Resultate zeigen können, führen körperliche Belastungen im Stimulationsversuch regelhaft zu einer erhöhten Thrombozytenreaktivität. Obwohl der Bildung von Thrombozyten-Leukozyten-Konjugaten zunehmende analytische Bedeutung zukommt, wurden belastungsinduzierte Veränderungen der Konjugate bisher kaum untersucht. In den wenigen vorliegenden Studien konnte aber gezeigt werden, dass es nach körperlichen Belastungen zu einer Zunahme an Thrombozyten-Leukozyten-Konjugaten sowie auch ihrer Subpopulationen kommt, welche sich aber sehr schnell wieder auflösen.

Die Ergebnisse zeigen, dass ein Stimulationsassay sowie die Bestimmung der Thrombozyten-Leukozyten-Konjugate sensitivere Verfahren darstellen als die Bestimmung von spontanen Aktivitätsmarkern wie z.B. das CD62P.

Zusammenfassend sind die beschriebenen Methoden nicht nur für Untersuchungen von physiologischen Veränderungen bei Thrombozyten einsetzbar, sondern können auch ohne weiteres bei der Untersuchung von pathologischen Zuständen verwendet werden.
The Family of GFP‐Like Proteins: Structure, Function, Photophysics and Biosensor Applications. Introduction and Perspective
Authors: Wachter Rebekka M.
Published: October 2005

In this issue, we offer a symposium‐in‐print that is focused on several new advancements in fundamental research related to the family of GFP (green fluorescent protein)‐like proteins. A few applied aspects are also included to illustrate the impact this amazing set of colored proteins has made on our understanding of cell biology at the molecular level. The six articles presented here cut across several disciplines ranging from biological function to protein structure to photophysical aspects. These highly original pieces of work include both experimental and computational approaches, and will provide the reader with significant insight into current, state‐of‐the‐art research activities in this very dynamic and fast‐paced field. In the first part of this perspective, I will give a brief overview of the history and salient features of GFPs, cite some examples that illustrate their impact on biotechnology, and provide a brief review of the structural and chemical features that lend these proteins their fascinating appearance. In the second part, I will introduce each of the peer‐reviewed contributions of the participating authors.
A field assessment of long-term laboratory sediment toxicity tests with the amphipod Hyalella azteca
Authors: Ingersoll Christopher G. , Wang Ning , Hayward Jeannie M. R. , Jones John R. , Jones Susan B. , Ireland D. Scott
Published: October 2005

Response of the amphipod Hyalella azteca exposed to contaminated sediments for 10 to 42 d in laboratory toxicity tests was compared to responses observed in controlled three-month invertebrate colonization exposures conducted in a pond. Sediments evaluated included a sediment spiked with dichlorodiphenyldichloroethane (DDD) or dilutions of a field sediment collected from the Grand Calumet River (GCR) in Indiana (USA) (contaminated with organic compounds and metals). Consistent effects were observed at the highest exposure concentrations (400 μg DDD/goc [DDD concentrations normalized to grams of organic carbon (goc) in sediment] or 4% GCR sediment) on survival, length, and reproduction of amphipods in the laboratory and on abundance of invertebrates colonizing sediments in the field. Effect concentrations for DDD observed for 10-d length and 42-d reproduction of amphipods (e.g., chronic value [ChV] of 66 μg DDD/goc and 25% inhibition concentration [IC25] of 68 μg DDD/goc for reproduction) were similar to the lowest effect concentrations for DDD measured on invertebrates colonizing sediment the field. Effect concentrations for GCR sediment on 28-d survival and length and 42-d reproduction and length of amphipods (i.e., ChVs of 0.20–0.66% GCR sediment) provided more conservative effect concentrations compared to 10-d survival or length of amphipods in the laboratory or the response of invertebrates colonizing sediment in the field (e.g., ChVs of 2.2% GCR sediment). Results of this study indicate that use of chronic laboratory toxicity tests with H. azteca and benthic colonization studies should be used to provide conservative estimates of impacts on benthic communities exposed to contaminated sediments. Bioaccumulation of DDD by oligochaetes colonizing the DDD-spiked sediment was similar to results of laboratory sediment tests previously conducted with the oligochaete Lumbriculus variegates, confirming that laboratory exposures can be used to estimate bioaccumulation by oligochaetes exposed in the field.
Genotoxic activity and inhibition of soil respiration by ptaquiloside, a bracken fern carcinogen
Authors: Schmidt Bjørn , Rasmussen Lars Holm , Svendsen Gitte Winkel , Ingerslev Flemming , Hansen Hans Christian Bruun
Published: October 2005

Ptaquiloside (PTA) is a natural toxin produced by bracken (Pteridium aquilinum [L.] Kuhn). Assessment of PTA toxicity is needed because PTA deposited from bracken to soil may leach to surface and groundwater. Inhibition of soil respiration and genotoxic activity of PTA was determined by a soil microbial carbon transformation test and an umu test, respectively. In the carbon transformation test, sandy loam soil was incubated at five different initial concentrations of PTA for a period of 28 d, after which glucose was added and respiration measured for 12 consecutive hours. The tests were performed at 20°C and soil moisture content of approximately 15%. For soil material sampled in the autumn, initial PTA concentrations ranging from 0.008 to 40.6 μg PTA/g dry soil were tested. From fitting of data by a sigmoidal function, a 10% effect dose (ED10) was estimated to 13 μg PTA/g dry soil, with an upper 95% confidence limit of 43 μg PTA/g dry soil and a 95% lower confidence limit of — ∞ μg PTA/g dry soil. For soil material sampled in late winter, initial PTA concentrations ranging from 1.56 to 212 μg PTA/g dry soil were tested, resulting in an ED10 value of 55 μg PTA/g dry soil, with an upper 95% confidence limit of 70 μg PTA/g dry soil and a 95% lower confidence limit of 40 μg PTA/g dry soil. The genotoxic activity of PTA was determined using the umu test without and with metabolic activation (addition of S9 rat liver homogenate). In tests with addition of S9, the induction ratio exceeded the critical ratio of 1.5 at a PTA concentration of 46 ± 16 μg/ml and, in tests without S9, the eritical ratio was exceeded at a PTA concentration of 279 ± 22 μg/ml. The genotoxicity of PTA is comparable to that of quercetin, another bracken constituent. The toxicity of PTA toward microorganisms prolongs the persistence of PTA in terrestrial environments, increasing the risk of PTA leaching to drainage and groundwater.
Effects of environmental pollution on microsatellite DNA diversity in wood mouse (Apodemus sylvaticus) populations
Authors: Berckmoes Veerle , Scheirs Jan , Jordaens Kurt , Blust Ronny , Backeljau Thierry , Verhagen Ron
Published: October 2005

Ten microsatellite DNA loci were surveyed to investigate the effects of heavy metal pollution on the genetic diversity and population genetic structure of seven wood mouse (Apodemus sylvaticus) populations along a heavy metal pollution gradient away from a nonferrous smelter in the south of Antwerp (Flanders, Belgium). Analysis of soil heavy metal concentrations showed that soil Ag, As, Cd, Cu, and Pb decreased with increasing distance from the smelter. Genetic analyses revealed high levels of genetic variation in all populations, but populations from the most polluted sites in the gradient did not differ from those of less-polluted sites in terms of mean observed and expected heterozygosity level and mean allelic richness. No correlation was found between measures of genetic diversity and the degree of heavy metal pollution. However, an analysis of molecular variance and a neighbor-joining tree suggested a contamination-related pattern of genetic structuring between the most polluted and less polluted sites. Pairwise FST values indicated that populations were significantly genetically differentiated, and assignment tests and direct estimates of recent migration rates suggested restricted gene flow among populations. Additionally, genetic differentiation increased significantly with geographical distance, which is consistent with an isolation-by-distance model. We conclude that, at least for our microsatellite DNA markers, genetic diversity in the studied wood mouse populations is not affected greatly by the heavy metal pollution.
Microbial characterization of artificial sediment and comparisons with natural sediments—implication for toxicity testing
Authors: Goedkoop Willem , Widenfalk Anneli , Haglund Ann-Louise , Steger Kristin , Bertilsson Stefan
Published: October 2005

The development and activity of microbiota in artificial sediment may have strong implications for the fate of test compounds and the outcome of toxicity tests. In this study, we compare a number of microbial variables in the artificial sediment commonly used in toxicity testing with that of natural sediments. Bacterial abundance of artificial sediment ranged 5.7 to 7.1 × 108 cells/g wet weight, which is about two orders of magnitude lower than values commonly reported for natural sediments. Similarly, alternative estimates of microbial biomass (sum of phospholipid fatty acid, ergosterol, adenosine triphosphate) were several times lower for artificial sediment compared with natural sediment. Bacterial activity (3H-thymidine incorporation) ranged 4.0 to 7.4 pmol g−1 h−1 (or 0.062–0.113 μg C g−1 h−1) in artificial sediments, which is low compared with values commonly reported for freshwater sediments. Community respiration in artificial sediment was 34 to 93 μg CO2 g−1 d−1. Bacterial community composition assessed by terminal restriction fragment length polymorphism of polymerase chain reaction amplified 16S rRNA genes demonstrated that natural bacterial communities appear to be more diverse than their counterparts in artificial sediment. The average similarity of the microbial communities obtained by this method was less than 40%, and different operational taxonomic units appeared to dominate the artificial and natural sediment, respectively. These results and supporting data from previous studies in natural sediments suggest that the artificial sediment has a poorly developed microbial component that differs substantially from that in natural sediments.
Effects of chlorpyrifos on the catalytic efficiency and expression level of acetylcholinesterases in the bivalve mollusk Scapharca inaequivalvis
Authors: Romani Rita , Isani Gloria , De Santis Alessandra , Giovannini Elvio , Rosi Gabriella
Published: October 2005

Three acetylcholinesterase (AChE) forms were detected and recovered from foot or gill tissues of the benthonic bivalve mollusk Scapharca inaequivalvis. A study was performed to investigate changes in catalytic and hydrodynamic features of these enzymes, as well as in their expression levels, after a 4-d or a 15-d exposure to a sublethal concentration (0.1 μl/L) of the pesticide chlorpyrifos (CPF). Both considered organs hold, in either CPF-exposed or untreated animals, two nonamphiphilic AChE forms, G2 and G4, which copurified on a procainamide-containing affinity gel and were separated by density gradient centrifugation. A third AChE form, an amphiphilic membrane-anchored G2, was also purified on the same affinity matrix from both organs. All enzymatic forms are true AChEs and are poorly inhibited by CPF. They show different increases in the maximum velocity (Vmax) and in the Michaelis constant (Km) values after CPF exposure. Consequently, catalytic efficiency of AChEs, as defined by the ratio Vmax:Km, rises in the gills and drops in the foot. This would produce an overexpression of AChE-specific mRNAs. The effect was longer lasting in the foot. The combined results indicate that overexpression of enzymes in the presence of organophosphate (OP) may be a consequence of OP resistance itself. Again, the resistance of the organism to CPF seem to depend mainly on the resulting increase in AChE content.
Bioconcentration of persistent organic pollutants in four species of marine phytoplankton
Authors: Gerofke Antje , Kömp Peter , McLachlan Michael S.
Published: October 2005

The uptake of polychlorinated biphenyls (PCBs) was studied in four species of marine algae. A novel experimental system to establish and maintain constant dissolved concentrations of PCBs was employed. Headspace sampling was used to verify that the freely dissolved concentrations remained constant with time. The headspace analysis also allowed sorption to dissolved organic carbon (DOC) to be quantified for all but the most lipophilic PCB congeners. Equilibration with the dissolved phase was rapid for three of the four algae species (<1 d for the majority of congeners). Organic carbon—normalized algae/water partition coefficients (KAlgW) were similar for three of the four species, but were lower by a factor of 10 to 20 for Phaeodactylum tricornutum. The KAlgW values of the first three species were similar to the octanol/water partition coefficient (KOW) for those PCB congeners for which DOC sorption could be quantified. These KAlgW values also agreed well with organic carbon—normalized bioconcentration factors for PCBs in suspended particulate matter (BCFSPM) sampled in Baltic Sea surface water during the summer.
Measuring the partitioning of silver to organic carbon using solubility enhancement
Authors: Rader Kevin J. , Shadi Timothy S. , Mahony John D. , Di Toro Dominic M.
Published: October 2005

Ionic silver is toxic to aquatic organisms at low concentrations. However, complexation to binding sites on natural organic matter has been shown to reduce silver toxicity. Research indicates that there is a need to develop reliable methods for characterizing silver binding at very low silver ion concentrations where strong binding sites have a significant influence on silver speciation. This study provides an analytical method for measuring silver binding using a solubility-enhancement procedure. Preliminary experimental results are provided that demonstrate strong silver binding in the presence of natural organic matter at very low silver ion concentrations.
Impact of activated sludge-derived colloidal organic carbon on behavior of estrogenic agonist recombinant yeast bioassay
Authors: Holbrook R. David , Novak John T. , Love Nancy G.
Published: October 2005

The impact of size-fractionated colloidal organic carbon (COC) originating from a biological wastewater treatment facility on the sensitivity of the yeast estrogen screen (YES) bioassay containing the human estrogen receptor (hER) gene was evaluated. Dose-response curves of serially diluted 17β-estradiol (E2), both in the presence and absence of COC, were generated by the YES bioassay. The concentration of E2 leading to a 50% YES response (effective concentration 50%, or EC50) was used to evaluate quantitatively the estrogenic activity of the different COC-E2 mixtures. The EC50 values for all COC size fractions, including COC-free samples (<1 kD), were statistically greater than the controls using Milli-Q water. Normalized EC50 values significantly increased as a function of COC concentration for the larger size fractions (>0.22 μm), but were not significantly affected by smaller COC material at environmental levels (1–5 mg/L), while both colloidal polysaccharide concentrations and colloidal fluorophores (measured at an excitation/emission wavelength pair of 350 nm/450 nm) appear to have an important role in the sensitivity of the YES bioassay. Estimates of the colloid-associated E2 fraction did not predict accurately increases in EC50 values. Matrix effects of the specific environment being tested with the YES bioassay need to be evaluated closely due to the sensitivity of the hER and reporter plasmid.
Comparison of relative binding affinities of endocrine active compounds to fathead minnow and rainbow trout estrogen receptors
Authors: Denny Jeffrey S. , Tapper Mark A. , Schmieder Patricia K. , Hornung Michael W. , Jensen Kathleen M. , Ankley Gerald T. , Henry Tala R.
Published: October 2005

Twelve chemicals were tested for binding affinity to rainbow trout liver estrogen receptor (rbtER) and fathead minnow liver ER (fhmER). The chemicals included estradiol (E2), diethylstilbestrol (DES), ethinylestradiol (EE2), estrone (E1), estriol, tamoxifen (TAM), genistein (GEN), p-nonylphenol (PNP), p-tert-octylphenol (PTOP), methoxychlor (MXC), testosterone, and methyltestosterone (MT). Relative binding affinity (RBA) was calculated for each chemical as a function of E2 binding to the receptor. The estrogens DES, EE2, and E1 bound with high affinity to both receptors, with respective RBAs of 583, 166, and 28% (fathead minnow) and 179, 89, and 5% (rainbow trout). Relative binding affinity of E3, TAM, and GEN for both fhmER and rbtER were moderate, with values between 0.3 and 5%. The alkylphenols had weak affinity for the ERs with RBAs for the fhmER of 0.1 and 0.01 for PNP and PTOP, respectively. Corresponding values for the rbtER are 0.027 and 0.009. Estradiol ([3H]E2) only partially was displaced from both the fhmER and the rbtER by MXC, T, and MT. Comparison of RBAs of the chemicals tested for fhmER and rbtER indicates that the rank order of RBAs essentially are the same for both species.