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51.
Chemoprevention refers to suppression or reversal of the carcinogenic process using pharmacologic or nutritional agents. Colorectal
carcinogenesis is a protracted, multistep process that offers opportunities for prevention. Aspirin and selective cyclooxygenase-2
inhibitors (coxibs) have been evaluated for the prevention of sporadic adenoma recurrence. Aspirin was shown to reduce adenoma
recurrence rates in patients with prior colorectal neoplasms; however, the optimal dosage remains unclear. Recent studies
of coxibs indicate that these agents are effective in reducing sporadic adenoma recurrence, but chronic use can result in
serious cardiovascular toxicity. These data underscore the need for chemopreventive agents with acceptable risk-to-benefit
ratios. In this regard, nitric-oxide-releasing aspirin shows chemopreventive efficacy in preclinical models and holds promise
for reduced toxicity in humans. Furthermore, ongoing chemoprevention trials are evaluating nutritional supplements, such as
folic acid and selenium, and results are eagerly awaited. 相似文献
52.
PURPOSE: Two experiments explored the extent to which induced blur, reduced luminance, and reduced visual fields affect drivers' steering performance in a driving simulator. METHODS: In experiment 1, ten young participants (M = 21.2 years) drove at approximately 89 km/h (55 mph) along a curvy roadway while being exposed to blur (0 to + 10 D), luminance (0.003 to 16.7 cd/m), and visual field (1.7 and 150 degrees) manipulations. In experiment 2, a new group of ten young participants (M = 18.5 years) drove while exposed to seven visual field sizes (1.7 to 150 degrees). RESULTS: Steering was sensitive to a reduced field size but not to the blur and luminance challenges. Acuity, on the other hand, was sensitive to the blur and luminance challenges but not to reduced field size. DISCUSSION: In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night. 相似文献
53.
Death of sensory ganglion neurons after acute withdrawal of nerve growth factor in dissociated cell cultures 总被引:1,自引:0,他引:1
The time course of dependence on nerve growth factor (NGF) for survival in sensory neurons in vitro was examined with microscopic and biochemical methods. Primary dorsal root ganglion (DRG) cultures from embryonic-day-15 (E-15) and day-19 (E-19) rats were maintained with standard dissociated cell culture techniques in the absence of most non-neuronal cells. After various times in culture, neurons were acutely deprived of neurotrophic support by changing to NGF-free medium and adding NGF antiserum to eliminate any residual NGF. Neuronal cultures were examined with phase microscopy; and, their metabolic activity was measured with a protein assay at various time points after NGF deprivation. E-15 neurons grown in culture for 5 days were exquisitely sensitive to acute NGF deprivation. By 12 h after NGF deprivation, neuronal morphology was severely disrupted and the majority of neurons appeared dead. E-15 neurons grown in culture for 8 or 11 days showed progressively less dependence on NGF for survival. These older neurons did not die until 24 and 48 h, respectively, following NGF withdrawal. Neurons grown in culture for 20 days did not show any morphologic changes by phase microscopy up to 4 days after NGF deprivation. Protein incorporation progressively decreased between 12 and 48 h after NGF withdrawal in E-15 neurons grown in culture for 5, 8, or 11 days.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
54.
Taylor Moran-Gates Christopher Grady Young Shik Park Ross J Baldessarini Frank I Tarazi 《European neuropsychopharmacology》2007,17(6-7):448-455
The atypical antipsychotic risperidone is often prescribed to pediatric patients with neuropsychiatric disorders, though its effects on the developing brain remain unclear. Accordingly, we studied the effects of repeated treatment of risperidone on dopamine receptors in brain regions of juvenile rat. Levels of dopamine receptors (D(1), D(2), D(3), D(4)) in forebrain regions of juvenile rats were quantified after 3 weeks of treatment with three different doses of risperidone (0.3, 1.0 and 3.0 mg/kg) and compared findings to those in adult rats treated with risperidone (3.0 mg/kg/day) previously. Risperidone (at 1.0 and 3.0 mg/kg/day) increased levels of D(1) receptors in nucleus accumbens and caudate-putamen of juvenile, but not adult rats. Conversely, all three doses of risperidone dose-dependently increased D(2) labeling in medial prefrontal cortex and hippocampus, and D(4) receptor in nucleus accumbens, caudate-putamen and hippocampus of juvenile animals as well as in adults. Only the high dose of risperidone (3.0 mg/kg) increased D(2) receptors in caudate-putamen in both juvenile and adult brain. D(3) receptors were not altered by risperidone in any brain region at any dose or age. The findings indicate dose-dependent effects of risperidone on dopamine receptors in developing animals, and that juvenile animals are more sensitive than adults to the cerebral effects of risperidone. 相似文献
55.
Katie S Lekx Maryam Fathimani Yves Bureau Gerald Wisenberg Jane Sykes Frank S Prato 《Journal of cardiovascular magnetic resonance》2006,8(5):731-739
PURPOSE: To evaluate qualitative wall motion assessment vs. quantitative wall thickening for the assessment of subtle changes in myocardial systolic function using cine MRI. METHODS: Cine MR images were obtained in 5 canines with a significant coronary artery stenosis and in 2 controls on a 1.5T scanner. Qualitative results were obtained using a numerical scoring system; quantitative analysis was performed using a semi-automatic segmentation program. The techniques were matched and compared using Spearman correlations. RESULTS: All correlations in the experimental group revealed significant but weak to moderate relationships between the qualitative and quantitative results (e.g., at-risk tissue rho = 0.363, p < 0.0001; remote tissue rho = 0.275, p = 0.0002), with each identifying changes in regional function that ensued following creation of the stenosis. Intra-observer variability was reasonable in both methods when repeat analysis on a subset of the data was performed, with both techniques showing a significant correlation between the repeated measurements (quantitative - rho = 0.52, p < 0.0001; qualitative - rho = 0.54, p < 0.0001). CONCLUSION: Both methods were able to detect very limited wall motion abnormalities present in the canines with significant stenosis and either method gives comparable results. 相似文献
56.
Mohammed E Abushaiqa Frank K Zaran David S Bach Richard T Smolarek Margo S Farber 《American journal of health-system pharmacy》2007,64(11):1170-1173
PURPOSE: Educational interventions to reduce the use of abbreviations and dosage designations that were deemed unsafe at a level 1 trauma center are described. SUMMARY: Strategies to reduce the use of unsafe abbreviations at Detroit Receiving Hospital were studied. Six abbreviations and dosage designations were deemed as unsafe by the site's medication-use and patient medical safety committees: (1) U for units, (2) microg for microgram, (3) TIW for three times a week, (4) the degree symbol for hour, (5) trailing zeros after a decimal point, and (6) the lack of leading zeros before a decimal point. Data on abbreviation use was collected starting in September 2003 by examining copies of patients' order sheets, which are sent from nursing units to the pharmacy for processing. Data were collected during three 24-hour periods each month, with 7-10 days between each period. A data collection sheet was developed to assist in documenting the number of opportunities for each unsafe abbreviation and the actual incidence of each. Educational strategies were developed and implemented starting in October 2003 to decrease the use of the unsafe abbreviations. These strategies included inservice education programs for the medical, pharmacy, and nursing staffs; laminated pocket cards; patient chart dividers; stickers; and interventions by pharmacists and nurses during medication prescribing. During the eight-month evaluation period, 20,160 orders were reviewed, representing 27,663 opportunities to use a designated unsafe abbreviation. Educational interventions successfully reduced the overall incidence of unsafe abbreviations from 19.69% to 3.31%. CONCLUSION: Educational interventions markedly reduced the use of unsafe abbreviations in medication orders over an eight-month evaluation period. 相似文献
57.
Martine C M Willems L W Ernest van Heurn Geert W Schurink Frank M van der Sande Jan H M Tordoir 《Nephrology, dialysis, transplantation》2006,21(12):3583-3584
58.
Deborah P Jones Carlos A Camargo Frank E Speizer R Graham Barr 《The Journal of asthma》2007,44(4):291-295
The authors tested the hypothesis that short stature predicts adult-onset asthma independent of obesity among women in the Nurses' Health Study. Height, weight, and physician-diagnosed asthma were assessed with validated questionnaire items. Proportional hazard models adjusted separately for weight and body mass index. The rate of newly diagnosed asthma was 1.55 times greater in the shortest versus the tallest quintile after adjustment for weight (95% CI, 1.26-1.91). After adjustment for body mass index, the rate ratio was 1.16 (95% CI, 0.94-1.42). Short stature predicted adult-onset asthma in a large cohort of women, but this association was not independent of obesity. 相似文献
59.
Diane C. Mitchell Author Vitae Frank R. LawrenceAuthor Vitae Terryl J. HartmanAuthor Vitae Julianne M. CurranAuthor Vitae 《Journal of the American Dietetic Association》2009,109(5):909-913
The US Department of Agriculture's MyPyramid guidelines introduced a near doubling of the dietary recommendations for vegetables. These recommendations target specific subgroups of vegetables, including dry beans and peas. Dry beans and peas provide an array of nutrients and phytochemicals that have been shown to have beneficial health effects, yet consumption levels in the United States are quite low. Few studies have examined the influence of legume consumption on nutrient intakes. Therefore, the purpose of this study was to assess nutrient and food group intakes of dry bean and pea consumers compared to nonconsumers. Dietary intake data from the 1999-2002 National Health and Nutrition Examination Survey for adults aged ≥19 years was used. Results show that on any given day only 7.9% of adults are consuming dry beans and peas; Mexican Americans or other Hispanics are more likely to be consumers than nonconsumers. Consuming approximately ½ c dry beans or peas resulted in higher intakes of fiber, protein, folate, zinc, iron, and magnesium with lower intakes of saturated fat and total fat. These data support the specific recommendation for dry beans and peas as part of the overall vegetable recommendation. Increased consumption of dry beans and peas—economical and nutrient-rich foods—could improve the diet quality of Americans. 相似文献
60.