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排序方式: 共有143条查询结果,搜索用时 15 毫秒
81.
G Rhys Williams MS 《BMC neurology》2001,1(1):2-6
Background and Purpose
Stroke, increasingly referred to as a "brain attack", is one of the leading causes of death and the leading cause of adult disability in the United States. It has recently been estimated that there were three quarters of a million strokes in the United States in 1995. The aim of this study was to replicate the 1995 estimate and examine if there was an increase from 1995 to 1996 by using a large administrative claims database representative of all 1996 US inpatient discharges. 相似文献82.
Estrella Klinzing MS Pechenik JA 《Journal of experimental marine biology and ecology》2000,252(2):255-279
Disproportionately large feeding structures have been used to infer food limitation in some marine invertebrate larvae, but few studies have investigated whether other factors alter larval morphology in similar ways. In this study, larvae of Crepidula fornicata were reared either at five different food concentrations of Isochrysis galbana (clone T-ISO) at a single temperature (22 degrees C) (Experiments I and II); or on three different phytoplankton species (Isochrysis galbana, Dunaliella tertiolecta, and Pavlova lutheri) at both high and low concentrations at a single temperature (22 degrees C) (Experiment III); or at high and low concentrations of Isochrysis galbana at four different temperatures between 16 and 25 degrees C (Experiment IV). Shell lengths and velar lobe dimensions were determined for individual larvae at intervals to monitor relative rates of velar and shell growth. In addition (Experiment V), fast growing and slow growing larvae in Experiment I were examined separately to determine whether velar lobes developed at similar rates (relative to shell growth) for fast and slow growing larvae within individual cultures. In general, velar lobes grew significantly larger, relative to shell length, when larvae were reared at low food concentrations (P<0.0001); for larvae of similar shell length, the velar lobes of those fed 1x10(4) cells ml(-1) were on average 17.7% larger than those of larvae fed 18x10(4) cells ml(-1) of T-ISO. In contrast, larvae fed different phytoplankton species at equivalently high food concentrations did not differ in relative velum size (P=0.2666), even though shell growth rates differed significantly for larvae raised on the different diets, indicating substantial variation in food quality. We also found that relative rates of velum and shell growth differed among fast and slow growing individuals within treatments. Temperature had no significant effect on relative rates of velar and shell growth within the 16-25 degrees C range tested (P=0.121), but may have altered the relationship between food concentration and relative velar growth. These results indicate that dramatically reduced food concentration induces disproportionate growth in the velar lobes of C. fornicata, but that interpretation of data from field-collected individuals of this species will be made difficult by the potentially confounding effects of temperature, food quality, and differences in individual growth potential. Assessments of food limitation using morphological measurements for field-collected larvae will need to be supplemented with other indicators before convincing conclusions about the extent of food limitation in C. fornicata can be drawn. 相似文献
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Genotoxicity of diacetoxyscirpenol (DAS) was studied on laboratory mice after intraperitoneal injection with single and repeated
doses. DAS was administrated at three different dose levels (0.5, 0.75, and 1.0 mg/kg body weight). The study was conducted
on both somatic and germ cells additional to the sperm morphology analysis. DAS treatment resulted in a significant reduction
(P<0.01) in mitotic activity at all levels of doses tested, confirming that DAS is a potent protein and DNA synthesis inhibitor.
At somatic cells (bone marrow) both structural and numerical chromosome abnormalities were observed. Single dose treatment
showed significant abnormalities only with high dose treatment. In contrast, at repeated dose similar abnormalities were also
observed with some significance but no systematic relation between the administrated dose and abnormalities ratio could be
settled. In germ cells (testicles), structural and numerical abnormalities were also observed. In general, the frequencies
of scored abnormalities at germ cells were lower than that the somatic cells. Sperm count test revealed a decrease in the
number of released sperm after toxin treatment. Abnormalities of sperm shape (head and tail) were observed, confirming the
positive correlation between cytogenetic damage and sperm abnormality.
The results also proved that DAS is a very toxic mycotoxin, in addition to inducing chromosomal abnormalities, it causes a
severe inhibition of DNA synthesis which subsequently affects the cell cycle and cell division. A good system for good harvesting
practice and good food technology can lower the risk for the consumers. 相似文献
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Margaret K. Hargreaves Jianguo Liu Maciej S. Buchowski Kushal A. Patel Celia O. Larson David G. Schlundt Donna M. Kenerson Kristina E. Hill Raymond F. Burk William J. Blot 《PloS one》2014,9(1)
Biomarkers of selenium are necessary for assessing selenium status in humans, since soil variation hinders estimation of selenium intake from foods. In this study, we measured the concentration of plasma selenium, selenoprotein P (SEPP1), and glutathione peroxidase (GPX3) activity and their interindividual differences in 383 low-income blacks and whites selected from a stratified random sample of adults aged 40–79 years, who were participating in a long-term cohort study in the southeastern United States (US). We assessed the utility of these biomarkers to determine differences in selenium status and their association with demographic, socio-economic, dietary, and other indicators. Dietary selenium intake was assessed using a validated food frequency questionnaire designed for the cohort, matched with region-specific food selenium content, and compared with the US Recommended Dietary Allowances (RDA) set at 55 µg/day. We found that SEPP1, a sensitive biomarker of selenium nutritional status, was significantly lower among blacks than whites (mean 4.4±1.1 vs. 4.7±1.0 mg/L, p = 0.006), with blacks less than half as likely to have highest vs. lowest quartile SEPP1 concentration (Odds Ratio (OR) 0.4, 95% Confidence Interval (CI) 0.2–0.8). The trend in a similar direction was observed for plasma selenium among blacks and whites, (mean 115±15.1 vs. 118±17.7 µg/L, p = 0.08), while GPX3 activity did not differ between blacks and whites (136±33.3 vs. 132±33.5 U/L, p = 0.320). Levels of the three biomarkers were not correlated with estimated dietary selenium intake, except for SEPP1 among 10% of participants with the lowest selenium intake (≤57 µg/day). The findings suggest that SEPP1 may be an effective biomarker of selenium status and disease risk in adults and that low selenium status may disproportionately affect black and white cohort participants. 相似文献
88.
Adult white rats were kept on natural diet containing various doses of Dithane M-45 (Mn and Zn ethylene-bisdithiocarbamate). Oxygen uptake (VO2), metabolic rate and energy balance were determined at intervals of several days. Oxygen uptake and metabolic rate were not significantly changed in animals receiving Dithane M-45 in concentrations of 5 and 50 ppm but they were significantly decreased in the animals kept on the diet containing the preparation in concentrations of 500, 2000 and 5000 ppm. The authors conclude that changes in body weight of animals after poisoning with Dithane M-45 are due, both to reduced supply and requirements for energy. 相似文献
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90.
Maciej S. Buchowski Nobuko Hongu Sari Acra Li Wang Joshua Warolin L. Jackson Roberts II 《PloS one》2012,7(10)