Integrin alpha1beta1 mediates a unique collagen-dependent proliferation pathway in vivo

Activation of integrins upon binding to extracellular matrix proteins is believed to be a crucial step for the regulation of cell survival and proliferation. We have used integrin alpha1-null mice to investigate the role of this collagen receptor in the regulation of cell growth and survival in vivo. alpha1-deficient animals, which are viable and fertile, have a hypocellular dermis and a deficiency in dermal fibroblast proliferation as embryos. In vitro analysis of alpha1-null embryonic fibroblasts has revealed that their proliferation rate is markedly reduced when plated on collagenous substrata, despite normal attachment and spreading. Moreover, on the same collagenous matrices, alpha1-null fibroblasts fail to recruit and activate the adaptor protein Shc. The failure to activate Shc is accompanied by a downstream deficiency in recruitment of Grb2 and subsequent mitogen-activated protein kinase activation. Taken together with the growth deficiency observed on collagens, this finding indicates that the alpha1beta1 is the sole collagen receptor which can activate the Shc mediated growth pathway. Thus, integrin alpha1 has a unique role among the collagen receptors in regulating both in vivo and in vitro cell proliferation in collagenous matrices.     

Estimating country-specific cost-effectiveness from multinational clinical trials

Awareness of the insufficient degree to which mainstream research has created useful knowledge about women's health has drawn many researchers to feminist methodologies. Such approaches tend to privilege qualitative designs, emancipatory objectives, and cooperative strategies. They challenge the notions of expert power, the appropriation of voice, and ownership of the research products. By uncovering the extent to which power inequities are embedded in our research traditions, including such issues as who conducts research, which questions are studied, and how they are studied, feminist critique can be a powerful tool toward stronger research with more socially relevant findings. However, taken to extremes, feminist methodological requirements can immobilize and discourage active inquiry. In this paper, we articulate major directives of a feminist stance, explain the extremes at which they become problematic, and propose responsive options for women's health researchers. We intend such analysis to overcome divisiveness and promote inclusiveness without sacrificing excellence in research and action.     

Repeated exposure of adult rats to Aroclor 1254 causes brain region-specific changes in intracellular Ca2+ buffering and protein kinase C activity in the absence of changes in tyrosine hydroxylase

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants, some of which may be neurotoxic. In vitro studies from this laboratory indicated that noncoplanar PCBs perturbed intracellular signal transduction mechanisms including Ca2+ homeostasis, receptor-mediated inositol phosphate production, and translocation of protein kinase C (PKC). In the present study, we examined the effects of PCBs in vivo by dosing adult male Long-Evans rats orally with Aroclor 1254 (0, 10, or 30 mg/kg/day; 5 days/week for 4 weeks) in corn oil. At 24 h after the last dose, rats were tested for motor activity in a photocell device for 30 min. Immediately, the rats were euthanized, blood was collected for thyroid hormone analysis, and brains were removed, dissected into regions (cerebellum, frontal cortex, and striatum), and subcellular fractions were obtained for neurochemical analysis. Following Aroclor 1254 treatment, body weight gain in the high-dose group was significantly lower than the control and low-dose groups. Horizontal motor activity was significantly lower in rats dosed with 30 mg/kg Aroclor 1254. Ca2+ buffering by microsomes was significantly lower in all three brain regions from the 30 mg/kg group. In the same dose group, mitochondrial Ca2+ buffering was affected in cerebellum but not in cortex or striatum. Similarly, total cerebellar PKC activity was decreased significantly while membrane-bound PKC activity was significantly elevated at 10 and 30 mg/kg. PKC activity was not altered either in cortex or the striatum. Neurotransmitter levels in striatum or cortex were slightly altered in PCB-exposed rats compared to controls. Furthermore, repeated oral administration of Aroclor 1254 to rats did not significantly alter forebrain tyrosine hydroxylase immunoreactivity or enzymatic activity. Circulating T4 (total and free) concentrations were severely depressed at both doses in Aroclor 1254-exposed rats compared to control rats, suggesting a severe hypothyroid state. These results indicate that (1) in vivo exposure to a PCB mixture can produce changes in second messenger systems that are similar to those observed after in vitro exposure of neuronal cell cultures; (2) second messenger systems seem to be more sensitive than alterations in neurotransmitter levels or tyrosine hydroxylase involved in dopamine synthesis during repeated exposure to PCBs; and (3) the observed motor activity changes were independent of changes in striatal dopamine levels.     

Methotrexate or total lymphoid radiation for treatment of persistent or recurrent allograft cellular rejection: a comparative study

Chlorpyrifos, one of the most widely used pesticides, exhibits greater toxicity during development than in adulthood. We administered chlorpyrifos to neonatal rats in doses spanning the threshold for systemic toxicity and examined developing brain regions (brainstem, forebrain, cerebellum) for signs of interference with cell development using markers for cell packing density and cell number (DNA concentration and content) and cell size (protein/DNA ratio). Neonatal rats given 5 mg/kg of chlorpyrifos on postnatal days 1-4 showed significant mortality and the survivors exhibited severe cell loss in the brainstem; brainstem growth was maintained by enlargement of the remaining cells. This effect was not seen at 1 mg/kg, a dose that did not compromise survival or growth, nor was there any adverse effect at either dose in the forebrain, despite the fact that both brainstem and forebrain possess comparable cholinergic projections. When chlorpyrifos was administered later, on days 11-14, the major target for cell loss shifted from the brainstem to the forebrain and in this case, effects were seen at doses that did not compromise survival or growth. The loss of forebrain cell number occurred between 15 and 20 days of age rather than during the chlorpyrifos treatment. The cerebellum differed from the other regions in that it showed short-term elevations of DNA after chlorpyrifos exposure in either early or late postnatal periods; nevertheless, values then regressed to subnormal in parallel with the loss of cells in other regions. Thus, chlorpyrifos likely causes delayed cell death. Although regions rich in cholinergic projections, such as brainstem and forebrain, may be more affected than noncholinergic regions (cerebellum), the maturational timetable of each region (brainstem earliest, forebrain intermediate, cerebellum last) appears to be more important in setting the window of vulnerability. These results indicate that, even when growth or survival are unaffected, chlorpyrifos produces cellular deficits in the developing brain that could contribute to behavioral abnormalities.     

The Glasgow Coma Score: reliable evidence?

This study examined the selected hormonal responses to, and hormone-mediated glucose metabolism during minimally invasive surgery in, patients undergoing laparoscopic cholecystectomy for symptomatic gallstone disease. Thirty-two patients with symptomatic gallstone disease were included in this study and scheduled for open or laparoscopic procedure in a randomized trial. Results are expressed as mean and standard error of the mean. Statistical evaluations were performed with Mann-Whitney U and Wilcoxon signed-rank tests. Blood cortisol, glucagon, insulin, and glucose concentrations were measured immediately in the preoperative period and 6 h after surgery. Blood cortisol, glucagon, and glucose concentrations increased significantly after open and minimally invasive surgery, while insulin levels and the insulin:glucagon ratio remained unchanged. The rise of glucagon and cortisol values was found to be significantly higher in the postoperative period of the open procedure, than in the laparoscopic approach. However, in the patients who underwent open surgery, the increase in glucose concentrations was not significantly higher in the postoperative period. Surgery-induced hormonal effects on the islets increase glucagon and suppress insulin secretion. The glucagon-mediated increase in hepatic glucose production is excluded by the posttraumatic insulin levels from the insulin-sensitive tissues. A bihormonal setting favors a greater rate of hepatic glucose production in both open and laparoscopic surgery. Hormonal changes do reflect the degree of surgical stress, but their metabolic consequences are not parallel to the grade of surgical trauma in minimally invasive surgery.     

Measurement of adenosine concentration in aqueous and vitreous

PURPOSE: The release of adenosine by the ischemic retina may be an initial signal in the development of ischemic macular edema and neovascularization. The levels of adenosine have never been quantified in ocular fluids. In this study, a technique was developed for in vivo measurement of the concentration of adenosine in aqueous and vitreous. METHODS: Aqueous and vitreous samples were obtained from bovine eyes after death and from live porcine eyes with the subject under general anesthesia. Samples from live eyes were immediately incubated in the sampling syringe with pentoxifylline, erythro-9-(2-hydroxy-3-nonyl) adenine, and dipyridamole to prevent synthesis or degradation of adenosine during the collection procedure, filtered, and flash-frozen in liquid nitrogen. All samples were then filtered and purified on phenylboronate agarose columns and incubated with chloroacetaldehyde to convert the adenosine present in the sample to the fluorescent derivative 1,N6-ethenoadenosine. The 1,N6-ethenoadenosine was separated by high-pressure liquid chromatography and then measured by fluorometry. RESULTS: Levels of adenosine as low as 0.5 pmole could be detected with this procedure, compared with 20 pmoles by UV detection. By using this technique to measure adenosine levels in the eyes of normal weanling domestic pigs, it was determined that the adenosine concentration in the aqueous was 321.3 +/- 164.9 nM and in the vitreous was 210.8 +/- 41.5 nM. CONCLUSIONS: The conversion of adenine-containing compounds to fluorescent 1,N6-etheno derivatives offers analytical advantages of selectivity and sensitivity for the quantitative determination of these compounds, with the fluorometric detection providing substantially greater sensitivity than direct detection by UV absorption. The levels obtained in vivo from anesthetized but otherwise healthy pigs presumably reflected basal aqueous and vitreous adenosine levels under the described conditions. This method should be useful in investigating more directly the role of adenosine in models of retinal or ocular ischemia in vivo and in measuring adenosine levels in vitreous or aqueous samples from human patients.     

淬火销轴表面质量检测的涡流探伤与着色探伤法对比

通过制作符合要求的试块调整探伤灵敏度,用涡流探伤替代着色探伤对淬火磨削轴表面质量进行检测。     

宁夏学校布局调整综合效能实证研究

本文在考量了学校布局调整的积极和消极制约因素的基础上,提出了学校布局调整的综合效能和正反效能阶段性的观点,并将宁夏所有学校的教育相关统计数据,以SPSS10.0为计量工具进行了实证研究.