737 research outputs found
A methodology for the capture and analysis of hybrid data: a case study of program debugging
No description supplie
Male reproductive health and environmental xenoestrogens
EHP is a publication of the U.S. government. Publication of EHP lies in the public domain and is therefore without copyright.
Research articles from EHP may be used freely; however, articles from the News section of EHP may contain photographs or figures copyrighted by other commercial organizations and individuals that may not be used without obtaining prior approval from both the EHP editors and the holder of the copyright.
Use of any materials published in EHP should be acknowledged (for example, "Reproduced with permission from Environmental Health Perspectives") and a reference provided for the article from which the material was reproduced.Male reproductive health has deteriorated in many countries during the last few decades. In the 1990s, declining semen quality has been reported from Belgium, Denmark, France, and Great Britain. The incidence of testicular cancer has increased during the same time incidences of hypospadias and cryptorchidism also appear to be increasing. Similar reproductive problems occur in many wildlife species. There are marked geographic differences in the prevalence of male reproductive disorders. While the reasons for these differences are currently unknown, both clinical and laboratory research suggest that the adverse changes may be inter-related and have a common origin in fetal life or childhood. Exposure of the male fetus to supranormal levels of estrogens, such as diethlylstilbestrol, can result in the above-mentioned reproductive defects. The growing number of reports demonstrating that common environmental contaminants and natural factors possess estrogenic activity presents the working hypothesis that the adverse trends in male reproductive health may be, at least in part, associated with exposure to estrogenic or other hormonally active (e.g., antiandrogenic) environmental chemicals during fetal and childhood development. An extensive research program is needed to understand the extent of the problem, its underlying etiology, and the development of a strategy for prevention and intervention.Supported by EU Contract BMH4-CT96-0314
Body fatness and physical activity at young ages and the risk of breast cancer in premenopausal women
We examined the relationship between body fatness, sports participation and breast cancer risk in 1560 premenopausal cases and 1548 controls, from three related population-based case–control studies in the UK. Half of the women with breast cancer were aged less than 36 years at diagnosis. Women who perceived themselves as plump at age 10 years had a relative risk of 0.83 (95% confidence interval 0.69–0.99, P=0.03) as compared with those who perceived themselves as thin. Self-reported obesity compared with leanness at diagnosis was associated with a relative risk of 0.78 (95% confidence interval 0.56–1.06, P=0.11). Women who reported having been plump at age 10 years and overweight or obese at diagnosis had a relative risk of 0.75 (95% confidence interval 0.56–1.01, P=0.06) as compared with those who reported being thin at age 10 years and at diagnosis. Findings for three related measures of body fatness suggested that obesity is associated with a reduced risk of premenopausal breast cancer. There was no association between sports participation and breast cancer risk in these premenopausal women. The relative risk for spending an average of more than 1 h per week in sports compared with less from ages 12 to 30 years was 1.00 (95% CI 0.86–1.16, P=0.98)
Validation and Norms of Cognition and Spaceflight Assessments with Senior Military Leaders
Spaceflight hazards include risks to cognitive performance. NASA requires sensitive neuropsychological screening tools to determine changes to cognitive risks to crew health and performance. Currently, NASA uses WinSCAT (Spaceflight Cognitive Assessment Tool for Windows) for neurocognitive screening and to monitor the status of astronauts during spaceflight. The CognitionTest Battery was recently developed by NASA-funded researchers at UPenn as part of the Behavioral Health and Performance component of NASA Standard Measures. This research provides independently validated norms and psychometric properties to compare WinSCAT to Cognition using a military population who operates in high demand, extreme environments similar to those experienced by astronauts (deployments, isolation, extreme environments)
Cognitive Performance in Military Senior Leaders: Analysis & Implications
No abstract availabl
Characterization of TgPuf1, a member of the Puf family RNA-binding proteins from Toxoplasma gondii
A Positive Feedback Synapse from Retinal Horizontal Cells to Cone Photoreceptors
Cone photoreceptors and horizontal cells (HCs) have a reciprocal synapse that
underlies lateral inhibition and establishes the antagonistic center-surround
organization of the visual system. Cones transmit to HCs through an excitatory
synapse and HCs feed back to cones through an inhibitory synapse. Here we report
that HCs also transmit to cone terminals a positive feedback signal that
elevates intracellular Ca2+ and accelerates neurotransmitter
release. Positive and negative feedback are both initiated by AMPA receptors on
HCs, but positive feedback appears to be mediated by a change in HC
Ca2+, whereas negative feedback is mediated by a change in
HC membrane potential. Local uncaging of AMPA receptor agonists suggests that
positive feedback is spatially constrained to active HC-cone synapses, whereas
the negative feedback signal spreads through HCs to affect release from
surrounding cones. By locally offsetting the effects of negative feedback,
positive feedback may amplify photoreceptor synaptic release without sacrificing
HC-mediated contrast enhancement
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