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71.
Understanding diet and energy balance as risk factors for breast, colon,
and other cancers requires information on the contribution of each factor
and of interactions among factors to cancer risk. Rodent models for breast
cancer provide extensive data on effects of dietary fat and calories,
energy balance, body weight gain, and physical activity on tumor
development. Analyses of the combined data from many studies have shown
clearly that quality and quantity of dietary fat and energy balance
contribute independently to increased mammary gland tumorigenesis. These
findings were seen in female rats fed diets high in fat (35-40% of
calories) compared to rats fed control diets, with approximately 10% of
calories as fat (Fay and Freedman, 1997, Breast Cancer Res. Treat. 46,
215-223). The methods used permit comparison of experimental and
epidemiological data, and they may be useful in extrapolating between
species and developing public health recommendations. In addition to the
contributions of lifetime-diet composition, intake, energy balance, and
physical activity to cancer risk, there are questions about the timing and
duration of alterations in these factors and about the "dose-response"
characteristics of cancer risk to the factors. Endocrine mechanisms may be
significant in mammary gland tumor risk, but experimental and
epidemiological data indicate that cancers at other sites, such as colon
and liver, also are influenced by the factors listed. Other diet and
lifestyle factors that influence energy, or specifically fat, metabolism
may also affect risk for cancers that are promoted by increased intake of
fat and calories. Studies of separate and interactive effects of dietary
fat, black tea, weight gain, and mammary gland tumorigenesis (Rogers, et
al, 1998, Carcinogenesis 19, 1269-1273) have been analyzed. Using
adjustment of carcinogenesis endpoints for body weight, tumor burden, and
latency, they were found to be related to weight gain within treatment
groups in 2 of 3 experiments.
相似文献
72.
Gendron FP Halbfinger E Fischer B Duval M D'Orléans-Juste P Beaudoin AR 《Journal of medicinal chemistry》2000,43(11):2239-2247
To elucidate the physiological role played by nucleoside triphosphate diphosphohydrolase (NTPDase; EC 3.6.1.5), adenine nucleotide analogues, modified on the purine ring, have been synthesized and tested as potential inhibitors. Resistance of ATP analogues to hydrolysis and their potency as NTPDase inhibitors were evaluated. For this purpose, a particulate fraction isolated from bovine spleen was used as the enzyme source. Among the synthesized analogues, 8-thiobutyladenosine 5'-triphosphate (8-BuS-ATP) was found to be the most effective nonhydrolyzable competitive inhibitor, with an estimated K(i) of 10 microM. This nonhydrolyzable analogue did not exert any P2X-receptor-mediated effect on endothelium-denuded blood vessels, from the guinea pig mesenteric bed. In agreement with this observation, infusion of the analogue did not cause any significant blood pressure variations of the precontracted vessel. Because in previous studies on isolated turkey erythrocytes and rat astrocytes 8-BuS-ATP was not able to trigger any P2Y(1)-receptor-mediated effect, it therefore appears that this NTPDase inhibitor does not interfere with purinergic receptors. 相似文献
73.
74.
Intracranial abnormalities in infants treated with extracorporeal membrane oxygenation: imaging with US and CT 总被引:1,自引:0,他引:1
Findings at neuroimaging in 100 consecutive infants treated with extracorporeal membrane oxygenation (ECMO) are presented. Imaging in these infants consisted of pretreatment cranial ultrasonography (US), daily US studies while on ECMO, and follow-up cranial computed tomography (CT) after treatment. There were findings of abnormalities in 43 patients. Thirty had intracranial bleeding, often of unusual extent and distribution. Thirteen additional infants had nonhemorrhagic abnormalities alone. Bleeding considered to be major was seen in 12% of infants. Large parenchymal hemorrhages and infarcts, cerebellar hemorrhages, and diffuse edema were the most significant abnormalities, with a 50% mortality (eight of 16 patients). No lateralization was noted with respect to distribution of bleeding sites or areas of nonhemorrhagic abnormalities. US was a sensitive but imperfect screening tool for intracranial abnormalities. Abnormalities missed with US included peripheral and small parenchymal lesions, subarachnoid hemorrhage, cerebral atrophy, and sagittal sinus thrombosis. 相似文献
75.
Post-poliomyelitis syndrome refers to new symptoms that may occur years after recovery from poliomyelitis. The most common of these symptoms are new weakness, fatigue, and pain. This article describes electrodiagnostic studies--conventional electromyography (EMG), single fiber electromyography (SFEMG), and macroelectromyography (macro-EMG)--that have provided information on the post-polio motor unit and on the possible etiology of some post-polio syndrome symptoms. Muscular fatigue, and indirectly, general fatigue, may be due to neuromuscular junction transmission defects in some post-polio individuals, as suggested by reduction of the compound motor action potentials on repetitive stimulation, and increased jitter and blocking on SFEMG. Progressive weakness and atrophy in post-polio syndrome is probably due to a distal degeneration of post-polio motor units with resultant irreversible muscle fiber denervation. Electrodiagnostic evidence of ongoing denervation includes fibrillation and fasciculation potentials on conventional EMG, increased jitter and blocking on SFEMG, and smaller macro-EMG amplitudes in newly weakened post-polio muscles. However, even though electrodiagnostic studies have provided insight into the possible causes of some post-polio syndrome symptoms, no specific electrodiagnostic test for the syndrome is currently available. 相似文献
76.
77.
Estrogens play a major role in the sexual differentiation, gonad development, and oocyte growth of most oviparous organisms. They also stimulate vitellogenesis, the formation of high‐density glycolipophosphoprotein that serves as an energy source for the developing embryo. Surface waters from the St. Lawrence River, obtained in the vicinity of an urban area (Montreal, Quebec, Canada), were studied with respect to their estrogenic potential to the freshwater mussel Elliptio complanata. Estrogenicity was measured in water extracts by means of a competitive assay of estradiol binding to cytosolic proteins and by the vitellin‐inducing ability of mussel hemolymph following direct extract injection. Surface‐water samples drawn downstream of a municipal outfall plume and in a river draining a large farming and agricultural area had high levels of total and fecal coliform bacteria. High levels of estrogen competitors were also found and were able to induce vitellins in injected mussels. Moreover, the estrogen‐competing potential of the extracts was found to be significantly correlated with total and fecal coliform bacteria (R=0.9, p<0.01) and with the levels of vitellins in the hemolymph (R=0.62, p=0.03). The results indicate that water samples drawn from within the municipal effluent plume and from a river draining an agricultural area are estrogenic to freshwater mussels. Thus, the environmental inputs of estrogens are likely to be associated with human sewage and pesticide products. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 260–268, 2001 相似文献
78.
Daniel TP Fong Mak-Ham Lam Miko LM Lao Chad WN Chan Patrick SH Yung Kwai-Yau Fung Pauline PY Lui Kai-Ming Chan 《Journal of orthopaedic surgery and research》2008,3(1):7
Background
Excessive pronation (or eversion) at ankle joint in heel-toe running correlated with lower extremity overuse injuries. Orthotics and inserts are often prescribed to limit the pronation range to tackle the problem. Previous studies revealed that the effect is product-specific. This study investigated the effect of medial arch-heel support in inserts on reducing ankle eversion in standing, walking and running. 相似文献79.
C Gendron 《Revue canadienne de recherche en sciences infirmières》1991,23(3):21-32
The purpose of this article is to present a questionnaire that permits the identification of women victims of their male partner's violence. Four indicators inspired by Orem's theory (1985) of nursing care were utilized to elaborate the different items in this research instrument: self-esteem, autonomy, social interaction and prevention of life hazards. The content validation process involved presenting 178 items for validation to 20 expert female judges. Then, the predictive value of 106 out of these items was tested with two comparable groups of women: one group of 81 women victims of family violence and another of 203 women identified as having never been victims. T-tests (p less than .05) were calculated on each of these 106 items, but finally it was the difference between the averages obtained by the t-tests that was used as the criterion of selection. Correlations item-total and correlations inter-item were run on the 49 items remaining, and this procedure brought to 30 the number of items retained for the questionnaire. Finally, factorial analysis showed that the degree of variance explained by the four indicators is about 18%, and that these indicators constituted many different facets of the same construct. 相似文献
80.
Migraine-associated vertigo 总被引:2,自引:0,他引:2
PA Savundra JD Carroll RA Davies LM Luxon 《Cephalalgia : an international journal of headache》1997,17(4):505-510
A retrospective analysis was performed on consecutive series of 363 patients presenting with vertigo; 32% had migraine. Of the 224 patients with no pathology other than migraine or vestibular dysfunction, migraineurs had a significantly higher prevalence of normal, central, and combined central and peripheral vestibular dysfunction compared to non-migraineurs. The combination of central and peripheral vestibular signs was a feature of migraine with aura. The results support the hypothesis that migraine-associated vertigo is a diagnostic entity. 相似文献