Dietary stearic acid reduces plasma and hepatic cholesterol concentrations without increasing bile acid excretion in cholesterol-fed hamsters

Although there is general agreement that saturated fatty acids elevate plasma cholesterol concentrations, the relative effects of individual fatty acids on cholesterol and bile acid metabolism are less clear. In this study, cholesterol and bile acid responses to diets enriched in different saturated fatty acids were investigated in hamsters. The six diets examined were as follows: 5% fat (g/100 g) enriched in palmitic acid (16:0) with no cholesterol, 5% fat 16:0-enriched, 0.05% cholesterol (wt/wt), and four diets containing 0.05% cholesterol and 15% fat with each diet enriched in lauric (12:0), myristic (14:0), palmitic (16:0), or stearic acid (18:0). Total plasma cholesterol concentration was significantly greater in hamsters fed the 14:0-enriched diet relative to those fed the 18:0-enriched diet (P < 0.05). Both plasma and liver cholesterol concentrations of hamsters fed 18:0 did not differ from those of the group fed no dietary cholesterol. In all instances, differences in total plasma cholesterol were accounted for within the HDL fraction; no significant treatment differences in VLDL or LDL cholesterol were found. Total daily fecal bile acid excretion was higher in hamsters fed the 15% fat 16:0 diet compared with those fed no dietary cholesterol (P < 0.05), but not significantly different from other treatment groups. There was greater deoxycholic acid excretion (P < 0.05) from hamsters fed the 14:0 and 16:0 diets compared with those fed the 18:0-enriched diet. Small intestinal + gallbladder bile acids, an index of pool size, did not differ significantly among the groups. The observed relative hypocholesterolemic effect of stearic acid was not mediated by increased bile acid excretion.     

Induction of biologically active IL-1 beta-converting enzyme and mature IL-1 beta in human keratinocytes by inflammatory and immunologic stimuli

IL-1beta, a major mediator of inflammatory and immunologic skin disease, undergoes post-translational site-specific cleavage by a novel cysteine protease termed IL-1beta-converting enzyme (ICE). Although in human skin keratinocytes produce significant amounts of the 31-kDa IL-1beta precursor protein, they fail under nonpathologic conditions to convert it to the 17.5-kDa bioactive form. In this study, we examined whether haptens and inflammatory agents might serve as stimuli for ICE activity in human keratinocytes, and, if so, whether ICE activity might precipitate enzymatic processing of IL-1beta to its 17.5-kDa form. Baseline levels of ICE mRNA were detected in keratinocyte cultures devoid of Langerhans cells and were up-regulated by nontoxic concentrations of the reactive hapten urushiol and by the irritant chemicals sodium lauryl sulfate and PMA. Although untreated keratinocytes expressed the 31-kDa form of the protein, 17.5-kDa IL-1beta was easily detected in keratinocytes and keratinocyte supernatants treated with either urushiol or the irritant chemicals. Enzymatic conversion from the 31-kDa to the 17.5-kDa form of IL-1beta was blocked by addition of a highly specific aldehyde inhibitor that contained a tetrapeptide recognition sequence specific for ICE, but not by an aldehyde inhibitor of a related ICE-like cysteine protease. Induction of IL-1beta-converting enzyme by immunologic and inflammatory stimuli may be one of the key regulatory elements in the pathogenesis of allergic and irritant contact hypersensitivity.     

NS2000监控系统操作经验总结

本文归纳了工程技术人员初次使用NS2000(FJNT版)后台监控系统容易出现操作“卡壳”的地方,并给出正确操作方法。可帮助初次使用NS2000(FJNT版)后台监控系统的技术人员不重复走弯路,也可供开发该软件的公司作改进之用。     

Theoretical and practical considerations for the measurement of P-glycoprotein function in acute myeloid leukemia

This paper summarizes experimental data and theoretical considerations, that are important for the measurement of P-glycoprotein (Pgp) function in acute myeloid leukemia (AML). The data are presented in subdivisions based on the techniques used, which will facilitate finding specific information. Based on our extensive experience with Pgp analysis, which includes radioactive assays, flow cytometry and fluorescence microscopy, we recommend a flow cytometry-based assay, that measures the effect of 2 microM PSC 833 on rhodamine 123 (R123) accumulation as the most practical and sensitive functional Pgp test. In combination with the flow cytometric measurement of Pgp using an antibody against an extracellular epitope (eg MRK16), this offers a sensitive and reproducible method for Pgp detection in AML, which is also rapid and practical. Furthermore, an R123 accumulation assay is specific for Pgp, because R123 is transported much less efficiently by the multidrug resistance protein (MRP) than by Pgp. Another probe of similar sensitivity and specificity is 3,3'-diethyloxacarbocyanine iodide. Alternatively, especially for the analysis of small numbers of cells (for example sorted subpopulations of leukemic cells), convenient and sensitive procedures are being developed by using DNA-binding Pgp substrates which remain fixed in the nuclei of the cells upon formaldehyde exposure for quantitative fluorescence laser scanning microscopy with image analysis. Less experimental data have been published to establish the optimal conditions for dual parameter flow cytometry (Pgp function, in eg Pgp+ or CD34+ cells). However, laboratories with flow cytometry experience will be able to implement this useful option to analyze subpopulations of cells.     

Dietary fats and lung cancer risk among women: the Missouri Women's Health Study (United States)

In a population-based case-control study of women in Missouri (United States), most of whom were smokers, we obtained information on adult diet to evaluate the effects of dietary fats in relation to lung cancer risk. All newly diagnosed, primary lung cancer cases among women 35 to 84 years of age reported to the Missouri Cancer Registry from 1 January 1993 to 31 January 1994 were invited to participate, as were population-based controls. The analysis focused on interviews obtained from 624 controls and 587 cases. In-person interviews were obtained from 99.0 percent of controls and 60.6 percent of cases. Age and energy-adjusted relative risks suggested a direct relation between risk of lung cancer and intake of dietary fats (e.g., total fat, saturated fat) and frequency of meat consumption. After adjusting for confounders, dietary fats were no longer associated with risk, but the adverse effect of frequent consumption of meat persisted. Risk was elevated about 90 percent (95 percent confidence interval = 1.2-3.0) among women in the highest quintile of red meat intake compared with those in the lowest quintile. Risk estimates associated with red meat consumption, however, were dependent on interview status; the effect was restricted to cases whose dietary information was provided by proxy. In summary, after adjusting for potential confounders and removing data obtained from proxy respondents, dietary fats and consumption of red meat were not associated with lung cancer risk among women in Missouri.     

Energy availability and mammary carcinogenesis: effects of calorie restriction and exercise

The purpose of this experiment was to compare the carcinogenic response in the mammary gland among groups of rats whose energy metabolism had been modulated by restricting dietary calories and/or by increasing energy expenditure via exercise. Female F344 rats (n = 132) were injected i.p. with 1-methyl-1-nitrosomethylurea (50 mg/kg at 50 and 57 days of age) and were randomized into one of four treatment groups: (i) unrestricted, sedentary; (ii) calorie-restricted, sedentary; (iii) unrestricted, exercised; (iv) calorie-restricted, exercised. The targeted level of calorie-restricted was 20% and exercise was achieved by treadmill-running (20 m/min at a 15% grade for 30 min, 5 days/week). During the 20.5 week study, rats were palpated twice a week for detection of mammary tumors and urine was collected for determination of 24-h cortical steroid excretion. At the end of the study, all mammary lesions were histologically classified. Carcass composition and carcass energy were determined. Mammary carcinogenesis was inhibited among calorie-restricted, sedentary rats compared with unrestricted, sedentary rats (79% inhibition, P < 0.001). No inhibition of carcinogenesis was observed among exercised rats (unrestricted or calorie-restricted) relative to the unrestricted, sedentary rats. Within the present experimental design, exercise had no effect on carcinogenesis despite significant reductions of carcass fat and carcass energy among both groups of rats that exercised. Cortical steroid level was significantly higher only in calorie-restricted, sedentary rats (P < 0.05). These results do not support the hypothesis that reductions of body weight gain, carcass fat or carcass energy are sufficient conditions to inhibit mammary carcinogenesis. The results do suggest that changes in urinary cortical steroid excretion may predict whether an energy-related intervention is likely to alter mammary carcinogenesis.     

Kennedy's disease: clinical and molecular study of two Italian families

Kennedy's disease, or spinal and bulbar muscular atrophy (SBMA), is a rare X-linked motoneuron disorder with variable signs of androgen insensitivity. It is associated with the expansion of a trinucleotide CAG repeat within the androgen receptor (AR) gene. We here report our clinical and molecular findings in two Italian families with Kennedy's disease. The increased size of the CAG repeat was demonstrated in four affected males and seven carrier females.     

Angiogenesis promoted by vascular endothelial growth factor: regulation through alpha1beta1 and alpha2beta1 integrins

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a cytokine of central importance for the angiogenesis associated with cancers and other pathologies. Because angiogenesis often involves endothelial cell (EC) migration and proliferation within a collagen-rich extracellular matrix, we investigated the possibility that VEGF promotes neovascularization through regulation of collagen receptor expression. VEGF induced a 5- to 7-fold increase in dermal microvascular EC surface protein expression of two collagen receptors-the alpha1beta1 and alpha2beta1 integrins-through induction of mRNAs encoding the alpha1 and alpha2 subunits. In contrast, VEGF did not induce increased expression of the alpha3beta1 integrin, which also has been implicated in collagen binding. Integrin alpha1-blocking and alpha2-blocking antibodies (Ab) each partially inhibited attachment of microvascular EC to collagen I, and alpha1-blocking Ab also inhibited attachment to collagen IV and laminin-1. Induction of alpha1beta1 and alpha2beta1 expression by VEGF promoted cell spreading on collagen I gels which was abolished by a combination of alpha1-blocking and alpha2-blocking Abs. In vivo, a combination of alpha1-blocking and alpha2-blocking Abs markedly inhibited VEGF-driven angiogenesis; average cross-sectional area of individual new blood vessels was reduced 90% and average total new vascular area was reduced 82% without detectable effects on the pre-existing vasculature. These data indicate that induction of alpha1beta1 and alpha2beta1 expression by EC is an important mechanism by which VEGF promotes angiogenesis and that alpha1beta1 and alpha2beta1 antagonists may prove effective in inhibiting VEGF-driven angiogenesis in cancers and other important pathologies.