bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the mercury exposure of dental amalgam patients by the Mercury Triple Test
Authors: Hansen G , Victor R , Engeldinger E , Schweitzer C 
Published: May 2004

Aims:To establish and analyse reference data for the mercury burden of patients with and without amalgam fillings.Methods:Atomic absorption spectroscopy was used to quantify Hg concentrations in the scalp hair and urine (before and after application of dimercaptopropane sulphonate), and Hg release from dental amalgams (using a newly developed, amalgam specific chew test), in 2223 subjects.Results:50th centiles were 1.3 μg Hg/g creatinine in basal urine, 32 μg Hg/g creatinine after DMPS application, 454 ng Hg/g in hair, and 27 μg Hg per g of chewing gum, which corresponds to about 1 μg Hg released per minute of chewing. Total Hg intake (from ambient air, drinking water, food, and amalgams) of most patients is well below the provisioned tolerable weekly intake (PTWI) defined by the WHO, unless extremely Hg rich food is consumed on a regular basis. However, for patients exceeding the 75thcentile in chew tests, total Hg intake exceeds the PTWI by about 50%, even at the low limit of intake from food. In the absence of occupational exposure, significant Hg release from dental amalgams is a necessary but insufficient condition to obtain a high long term body burden. After removal of dental amalgams, chew tests no longer exhibit oral Hg exposure, while basal urine Hg content and DMPS induced excretion display a exponential decrease (half life about 2 months in both cases).Conclusions:A standardised procedure for evaluation of the magnitude and origin of the Hg burden of individuals has been developed, which, by comparison with the database presented here for the first time, can serve as a diagnostic tool.
Perceived muscular tension, job strain, physical exposure, and associations with neck pain among VDU users; a prospective cohort study
Authors: Wahlström J , Hagberg M , Toomingas A , Wigaeus Tornqvist E 
Published: May 2004

Aims:To determine whether perceived muscular tension, job strain, or physical exposure are associated with increased risk of developing neck pain among VDU users.Methods:A baseline questionnaire was answered by 1283 respondents, of whom 671 were free from neck pain at baseline. Perceived muscular tension, job strain, and physical exposure were assessed at baseline. Information about newly developed neck pain was collected in 10 follow up questionnaires and the case definition was the first report of such pain in any of the follow up questionnaires. Median follow up time was 10.9 months.Results:Both men and women who perceived muscular tension at least a few times per week, compared to those who had not perceived muscular tension the preceding month, had an incidence rate ratio (IRR) of 1.9 (95% CI 1.25 to 2.93) for developing neck pain, when stratifying for sex. High perceived muscular tension was associated with an increased risk (IRR 1.6, 95% CI 1.02 to 1.91), even when controlling for job strain, physical exposure, and age in the model stratified by sex.Conclusions:Perceived muscular tension was associated with an increased risk of developing neck pain among VDU users. The combination of high job strain and high perceived muscular tension was associated with higher risk of developing neck pain than the combination of high physical exposure and high perceived muscular tension. There was an indication of an excess risk due to interaction between high physical exposure and high job strain.
Summer work and injury among middle school students, aged 10–14 years
Authors: Zierold K M , Garman S , Anderson H 
Published: May 2004

Background:Little information exists on injury and factors associated with injury in working youth aged 10–14 years. Most studies do not involve children younger than 15.Methods:A cross-sectional anonymous survey was administered to middle school students in five school districts and one large urban school in October 2001.Results:Of the 3189 working middle school students who responded to the survey, the majority were employed in informal job settings, such as working for someone in a home, newspaper delivery, and working on family farms or in family businesses. Overall, 18% of children reported being injured at work. Of those injured, 26% reported that their injury was severe enough to affect their activities for more than three days. Variables that were associated with injury included having a “near-miss” incident at work (AOR 6.61, 95% CI 4.92 to 8.89), having a co-worker injured (AOR 2.65, 95% CI 1.95 to 3.60), and being asked to do something dangerous (AOR 2.25, 95% CI 1.61 to 3.14).Conclusions:Children are working and being injured in jobs that are not covered by existing child labour laws. Injury rates in non-covered occupations are high, warranting review of current laws.
Atherosclerotic Plaque Smooth Muscle Cells Have a Distinct Phenotype
Authors: Mulvihill Eileen R. , Jaeger Jochen , Sengupta Rimli , Ruzzo Walter L. , Reimer Cecile , Lukito Sheila , Schwartz Stephen M. 
Published: May 2004

Objective—The present study addresses the question, “Are plaque smooth muscles cells (SMCs) genetically distinct from medial SMCs as reflected by the ability to maintain a distinctive expression phenotype in vitro?”Methods and Results—Multiple cell strains were developed from carotid endarcterectomy specimens, and quadruplicate array hybridizations were completed for each sample. A new normalization protocol was developed and used to analyze the data. Permutation analysis suggests that most of the significant differences in expression could not have occurred by chance. A broad pattern of significant expression differences, consisting of almost 5% of the genes probed, was detected. Quantitative polymerase chain reaction (QPCR) confirmation was found in 70% of a subset of genes selected for validation.Conclusions—The SMC cultures were nearly indistinguishable by morphological features, population doubling time, and sensitivity to cell death induced by Fas cross-linking. Surprisingly, array expression analysis identified differences so extensive that we conclude that plaque and medial SMCs are distinctly different SMC cell types.
Female Choice and Male Courtship Behaviour in the Beaugregory Damselfish
Authors: Haley  , Itzkowitz  , Smith  
Published: May 2004

AbstractDuring courtship in the beaugregory (Stegastes leucostictus), a coral reef fish, males turn the dorsal half of their bodies from dull brown to bright yellow, and perform a series of rapid dipping movements in front of females. To look for evidence that females select males on the basis of these characteristics, we provided males with artificial breeding sites in the field, measured their reproductive success, and videotaped courtship. Reproductive success was measured by monitoring both the number and size of egg clutches present in the breeding site that was defended by the male. Both unmanipulated and experimentally induced courtship events were videotaped in separate groups of 88 (of which 32 were videotaped courting females) and 30 males, respectively. Experimental induction of courtship was done by placing a female in a clear plastic cylinder 0.5 m away from the breeding site of a territorial male; each of the 30 males received 8 different female presentations, but never more than one a day, and with a different female every time. We compared (i) the cumulative amount of eggs and number of clutches with the amount of yellow colouration and dipping rate for individual males in both the observational and experimental groups, (ii) individual variation in percentage yellow and dipping rate (for the experimental group only) with reproductive success on the same day when courtship was videotaped, and (iii) egg survivorship (ratio of final to early stage eggs) with yellow colouration and dipping rate, to see if these characteristics indicate male parental ability. Individual variation in courtship characteristics was not correlated with reproductive success on that day. In contrast, however, mean values of percentage yellow and dip rate were correlated with both the number of clutches and amount of eggs, for both the observational and experimental group of males, indicating that females preferentially spawn with males that have the brightest yellow colouration and the highest dip rate. Percentage yellow colouration was correlated with egg survival in the unmanipulated males, but not in the experimental group, while dipping rate was not correlated with egg survival in either group. We argue here that female assessment of male courtship is part of a complex process of female choice, in which females either simultaneously or sequentially examine territorial, breeding site, and male characteristics, and thereby attempt to enhance the survivorship of their offspring.
Social Play in Arabian Babblers
Authors: Zahavi Avishag , Zahavi Amotz , Pozis-Francois Orit 
Published: May 2004

AbstractSocial play behavior was studied in eleven groups of tame, color-ringed Arabian babblers (Turdoides squamiceps) at the Shezaf nature reserve near Hazeva in the Rift Valley in Israel. 2500 instances of play were recorded in 950 hours of observations carried out from July 1981 to June 1983. Four hours of play interactions were recorded on video-tape and were analyzed using slow-motion techniques. Babblers' play fits all the criteria for 'social play' described by Loizos (1967) and by Muller-Schwarze (1978). The most common forms of play observed were wrestling, displacement (king-of-the-hill), chases, and tug-of-war. Several play-signals were identified: crouching, rolling over, elevation of sticks, play bow, establishing eye contact and freezing briefly in the middle of play. No vocal play-signals were observed. The ontogeny of play is briefly described. Play activity diminishes with age. Dominants play less than subordinates. Babblers tend to play with individuals close to them in rank. Breeding females rarely play. There was no effect of age, dominance or gender on the type of play. When playing, dominants use play-signals more often than subordinates do. Social tension in a group inhibited play activity. Babblers play more in summer than in winter. Bouts of play tend to alternate with bouts of allopreening. Food supplementation increased both activities. Play is more demanding than allopreening, both physically and socially. It is suggested that in babblers testing the social bond is a major component in both social play and allopreening.
Symmetry Preference as a Cognitive By-Product in Starlings
Authors: Swaddle John , Clelland R. Earl , Che Judy 
Published: May 2004

AbstractThere has been a great deal of interest in whether animals use trait symmetry as a visual cue to mediate behavioural interactions. In bilaterally symmetric traits, small asymmetries (termed fluctuating asymmetry) appear due to increased developmental stress and/or genes for poor developmental homeostasis. Hence, researchers have hypothesized that symmetry can reveal the developmental history and, perhaps, fitness of an individual and this is why symmetry preferences have been observed. However, an additional theory suggests that symmetry could be preferred merely because it represents the average expression of bilateral traits. Animals can learn to respond to signals by generalizing (or averaging) stimulus sets. As the average expression of a trait showing fluctuating asymmetry is zero asymmetry, theory predicts that animals could develop a symmetry preference as a by-product of learning. Here, we test this prediction empirically with European starlings (Sturnus vulgaris) and show that symmetry preferences can emerge as an outcome of generalized learning processes. Our results indicate that symmetry does not initially need to be associated with fitness to be an apparent cue in behavioural interactions and that symmetry preferences observed in nature could be independent of any putative fitness relationships.
Plume Variation, Breeding Performance and Extra-Pair Copulations in the Cattle Egret
Authors: Green David , Krebs Elizabeth , Hunte Wayne 
Published: May 2004

AbstractWe investigate how variation in breeding plumes influences pairing patterns, extra-pair copulations and breeding performance in the colonial cattle egret (Bubulcus ibis ibis). The breeding plumes of both male and female cattle egrets varied from almost none, to lush head, back and scapular plumes. Overall, male breeding plumes were longer and darker than those of females, but we observed the full range of plume development in both sexes. Plume development was positively correlated within breeding pairs. Females may be more selective in mate choice since they only paired with males with similar or better plumes and only accepted extra-pair copulations when the male had plumes that were greater than or equal to those of their mates. Males, in contrast frequently paired with females of lower plume development, and did not target well plumed females for extra pair copulations. Females may obtain direct benefits from pairing with well plumed males since these males copulated and fed chicks at a higher rate, although this did not lead to higher fledging success in our study. Well plumed females did not have higher nest attendance, nestling attendance, feeding rates or fledging success. Nevertheless, males appeared to invest more in a breeding attempt when paired to a well plumed female by increasing copulation rates, mate attendance and nest site attendance. Breeding plumes may therefore signal both parental and genetic quality to prospective mates.
The Frequency and Timing of Courtship and Copulation in Blackbirds, Turdus Merula, Reflect Sperm Competition and Sexual Conflict
Authors: Halupka Konrad , Wysocki Dariusz 
Published: May 2004

AbstractIn a long-term field study we estimated the number of copulations per pair in blackbirds at 24.2 in a single reproductive cycle. Thus it seems unlikely that the only function of copulation behaviour is just to guarantee fertilization. We considered three other hypotheses which might explain frequent pair copulation: (1) as an effect of sperm competition, (2) cooperation between pair members aiming at increasing joint production of offspring; or, (3) sexual conflict resulting in female manipulation of allocation of time and energy of the male. We found no positive correlation between the copulation frequency and reproductive performance, a result that essentially falsifies the cooperation hypothesis. Only two extra-pair copulations were recorded. However, attempts at forced extra-pair copulation were very common and a high pair copulation rate might have evolved in response to sperm competition. Alternately, relatively high copulation rate in the pre-fertile stage of the reproductive cycle and female control over timing and frequency of copulation (via solicitation of copulation and/or rejection of courtship by the male) also supports the sexual conflict scenario. We suggest that our findings support the idea that the female prolongs the period of sexual activity to induce her partner to guard her (which reduces sexual coercion from other males) and to monopolise his parental effort (the male while mate guarding cannot pursue extra-pair activity or search for better mating options).
17β-Estradiol (E2) modulates cytokine and chemokine expression in human monocyte-derived dendritic cells
Authors: Bengtsson Åsa K. , Ryan Elizabeth J. , Giordano Daniela , Magaletti Dario M. , Clark Edward A. 
Published: May 2004

AbstractThe effects of estrogen on the immune system are still largely unknown. We have investigated the effect of 17β-estradiol (E2) on human monocyte-derived immature dendritic cells (iDCs). Short-term culture in E2 had no effect on iDC survival or the expression of cell surface markers. However, E2 treatment significantly increased the secretion of interleukin 6 (IL-6) in iDCs and also increased secretion of osteoprotegerin (OPG) by DCs. Furthermore, E2 significantly increased secretion of the inflammatory chemokines IL-8 and monocyte chemoattractant protein 1 (MCP-1) by iDCs, but not the production of the constitutive chemokines thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC). However, after E2 pretreatment the lipopolysaccharide (LPS)–induced production of MCP-1, TARC, and MDC by DCs was clearly enhanced. Moreover, mature DCs pretreated with E2 stimulated T cells better than control cells. Finally, we found that E2 provides an essential signal for migration of mature DCs toward CCL19/macrophage inflammatory protein 3β (MIP3β). In summary, E2 may affect DC regulation of T-cell and B-cell responses, as well as help to sustain inflammatory responses. This may explain, in part, the reason serum levels of estrogen correlate with the severity of certain autoimmune diseases.
Role of G protein–gated inwardly rectifying potassium channels in P2Y12 receptor–mediated platelet functional responses
Authors: Shankar Haripriya , Murugappan Swaminathan , Kim Soochong , Jin Jianguo , Ding Zhongren , Wickman Kevin , Kunapuli Satya P. 
Published: May 2004

AbstractThe role of the Gi-coupled platelet P2Y12 receptor in platelet function has been well established. However, the functional effector or effectors contributing directly to αIIbβ3 activation in human platelets has not been delineated. As the P2Y12 receptor has been shown to activate G protein–gated, inwardly rectifying potassium (GIRK) channels, we investigated whether GIRK channels mediate any of the functional responses of the platelet P2Y12 receptor. Western blot analysis revealed that platelets express GIRK1, GIRK2, and GIRK4. In aspirin-treated and washed human platelets, 2 structurally distinct GIRK inhibitors, SCH23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride) and U50488H (trans-(±)-3,4-dichloro-N-methyl-N-[2-(pyrrolidinyl)cyclohexyl] benzeneacetamide methanesulfonate), inhibited adenosine diphosphate (ADP)–, 2-methylthioADP (2-MeSADP)–, U46619-, and low-dose thrombin–mediated platelet aggregation. However, the GIRK channel inhibitors did not affect platelet aggregation induced by high concentrations of thrombin, AYPGKF, or convulxin. Furthermore, the GIRK channel inhibitors reversed SFLLRN-induced platelet aggregation, inhibited the P2Y12-mediated potentiation of dense granule secretion and Akt phosphorylation, and did not affect the agonist-induced Gq-mediated platelet shape change and intracellular calcium mobilization. Unlike AR-C 69931MX, a P2Y12 receptor–selective antagonist, the GIRK channel blockers did not affect the ADP-induced adenlylyl cyclase inhibition, indicating that they do not directly antagonize the P2Y12 receptor. We conclude that GIRK channels are important functional effectors of the P2Y12 receptor in human platelets.
Multiple patients with revertant mosaicism in a single Wiskott-Aldrich syndrome family
Authors: Wada Taizo , Schurman Shepherd H. , Jagadeesh G. Jayashree , Garabedian Elizabeth K. , Nelson David L. , Candotti Fabio 
Published: May 2004

Abstract
We previously reported on a 43-year-old patient with Wiskott-Aldrich syndrome (WAS) who experienced progressive clinical improvement and revertant T-cell mosaicism. Deletion of the disease-causing 6-bp insertion was hypothesized to have occurred by DNA polymerase slippage. We now describe 2 additional patients from the same family who also had revertant T lymphocytes that showed selective in vivo advantage. Somatic mosaicism was demonstrated on leukocytes cryopreserved in the first patient when he was 22 years old, 11 years before his death from kidney failure. The second patient is now 16 years old, has a moderate clinical phenotype, and developed revertant cells after the age of 14 years. These results support DNA polymerase slippage as a common underlying mechanism, and they indicate that T-cell mosaicism may have different clinical effects in WAS.
Synergistic effects on erythropoiesis, thrombopoiesis, and stem cell competitiveness in mice deficient in thrombopoietin and steel factor receptors
Authors: Antonchuk Jennifer , Hyland Craig D. , Hilton Douglas J. , Alexander Warren S. 
Published: May 2004

Abstract
The degree of redundancy between thrombopoietin (Tpo) and steel factor (SF) cytokine pathways in the regulation of hematopoiesis was investigated by generating mice lacking both c-Mpl and fully functional c-Kit receptors. Double-mutant c-Mpl–/–KitWv/Wv mice exhibited reduced viability, making up only 2% of the offspring from c-Mpl–/–KitWv/+ intercrosses. The thrombocytopenia and megakaryocytopenia characteristic of c-Mpl–/– mice was unchanged in c-Mpl–/–KitWv/Wv mice. However, the number of megakaryocytic colony forming units (CFU-Mks) was significantly reduced, particularly in the spleen. While KitWv/Wv mice, but not c-Mpl–/– mice, are anemic, the anemia was more severe in double-mutant c-Mpl–/–KitWv/Wv mice, indicating redundancy between Tpo and SF in erythropoiesis. At the primitive cell level, c-Mpl–/– and KitWv/Wv mice have similar phenotypes, including reduced progenitors, colony forming units–spleen (CFU-Ss), and repopulating activities. All of these parameters were exacerbated in double-mutant mice. c-Mpl–/–KitWv/Wv mice had 8-fold fewer clonogenic progenitor cells and at least 28-fold fewer CFU-Ss. c-Mpl–/– mice also demonstrated a reduced threshold requirement for nonmyeloablative transplant repopulation, a trait previously associated only with KitW mice, and the level of nonmyeloablative engraftment was significantly greater in c-Mpl–/–KitWv/Wv double mutants. Thus, c-Mpl–/–KitWv/Wv mice reveal nonredundant and synergistic effects of Tpo and SF on primitive hematopoietic cells.
Cell lineage tracing duringXenopustail regeneration
Authors: Gargioli Cesare , Slack Jonathan M. W. 
Published: May 2004

The tail of the Xenopus tadpole will regenerate following amputation, and all three of the main axial structures – the spinal cord, the notochord and the segmented myotomes – are found in the regenerated tail. We have investigated the cellular origin of each of these three tissue types during regeneration.We produced Xenopus laevis embryos transgenic for the CMV (Simian Cytomegalovirus) promoter driving GFP (Green Fluorescent Protein) ubiquitously throughout the embryo. Single tissues were then specifically labelled by making grafts at the neurula stage from transgenic donors to unlabelled hosts. When the hosts have developed to tadpoles, they carry a region of the appropriate tissue labelled with GFP. These tails were amputated through the labelled region and the distribution of labelled cells in the regenerate was followed. We also labelled myofibres using the Cre-lox method.The results show that the spinal cord and the notochord regenerate from the same tissue type in the stump, with no labelling of other tissues. In the case of the muscle, we show that the myofibres of the regenerate arise from satellite cells and not from the pre-existing myofibres. This shows that metaplasia between differentiated cell types does not occur, and that the process of Xenopus tail regeneration is more akin to tissue renewal in mammals than to urodele tail regeneration.
Spectroelectrochemical Determination of the Redox Potential of P700 in Spinach with an Optically Transparent Thin-layer Electrode
Authors: Nakamura Akimasa , Suzawa Tomoyuki , Watanabe Tadashi 
Published: May 2004

Abstract
Optimization of experimental conditions for spectroelectrochemistry with an optically transparent thin-layer electrode allowed us to determine the redox potential of spinach P700, the primary electron donor of photosystem I, to be +469 mV vs. SHE with significantly high reproducibility (±2 mV for 12 independent samples).