Effect of pancreatic secretions upon ileal disaccharidase activities of neonatal miniature pigs

Summary Mechanisms by which pancreatic secretions influence disaccharidase activities in the distal small intestine have been investigated in 1-week-old miniature pigs. Using a combination of biochemical, cytochemical and morphological techniques it has been found that the decrease in lactase specific activity is due solely to a reduction in villus surface area. By contrast, the increased sucrase-isomaltase activities, which occur despite the reduction in villus surface area, are due entirely to increased enzyme expression during enterocyte differentiation.     

Factors influencing the intestinal phase of pancreatic exocrine secretion in the turkey

The present study was done to investigate the factors regulating the intestinal phase of exocrine pancreatic secretion in the turkey. The intestine of turkeys equipped with pancreatic fistulas was perfused with peptone solution, fat emulsion and hydrochloric acid (HCl), and pancreatic flow and protein output were measured. Neither peptone solution nor fat emulsion had any effects on pancreatic secretion. HCl enhanced the flow rate of pancreatic juice but not protein output. To clarify the neural mechanism of this phenomenon, the vagal postganglionic blocker atropine was continuously infused and pancreatic secretion in response to intestinal HCl was measured. Atropine completely suppressed both pancreatic flow and protein output. It is suggested that the avian intestinal phase of pancreatic secretion is mainly controlled by cholinergic action though HCl stimulation.     

Impaired insulin release in aging rats: Metabolic and ionic events

We investigated the effect of aging on glucose uptake, glucose-induced O₂ consumption, glucose-induced⁴⁵Ca movements, and calmodulin content to elucidate age-related impairment of glucose-induced insulin release in pancreatic islets of Wistar rats. Intact pancreatic islets from old (24-month-old) rats showed impaired glucose-induced insulin release; glucose uptake and O₂ consumption were lower in old than in young (2-month-old) or adult (12-month-old) rats. Moreover,⁴⁵Ca uptake and calmodulin content were decreased in pancreatic islets from older rats, which explained the impairment in glucose-induced insulin release in aging. No major differences between the 3 age groups in glucose-induced⁴⁵Ca efflux in pancreatic islets were observed.     

Cytosolic free Ca2+ in insulin secreting cells and its regulation by isolated organelles

Summary The role of Ca²⁺ in secretagogue-induced insulin release is documented not only by the measurements of⁴⁵Ca fluxes in pancreatic islets, but also, by direct monitoring of cytosolic free Ca²⁺, [Ca²⁺]_i. As demonstrated, using the fluorescent indicator quin 2, glyceraldehyde, carbamylcholine and alanine raise [Ca²⁺]_i in the insulin secreting cell line RINm5F, whereas glucose has a similar effect in pancreatic islet cells. The regulation of cellular Ca²⁺ homeostasis by organelles from a rat insulinoma, was investigated with a Ca²⁺ selective electrode. The results suggest that both the endoplasmic reticulum and the mitochondria participate in this regulation, albeit at different Ca²⁺ concentrations. By contrast, the secretory granules do not appear to be involved in the short-term regulation of [Ca²⁺]_i. Evidence is presented that inositol 1,4,5-trisphosphate, which is shown to mobilize Ca²⁺ from the endoplasmic reticulum, is acting as an intracellular mediator in the stimulation of insulin release.     

Sexual dimorphism in the defensive secretion of a carabid beetle

Summary The defensive secretions of male and femaleOodes americanus display striking qualitative differences. Altogether 13 carboxylic acids were identified in the secretions of the two sexes. Methacrylic, crotonic, and tiglic acids are produced exclusively by the female; the male lacks these unsaturated components, but produces their saturated analogs. 2-Methylbutyric acid is a major component produced by both sexes. Shared components also include hexanoic, (E)-2-hexenoic, benzoic, and (E)-2-octenoic acid, of which the latter two had not previously been reported from carabid beetles.Paper no. 98 in the series Defense Mechanisms of Arthropods; no. 97 is by Smedley et al., J. Lepid. Soc., in press.     

In vivo effects of epinephrine in a freshwater fish

Summary In vivo effects of epinephrine were investigated in a freshwater teleost,Barbus conchonius Hamilton. Fish given 2 mg/kg epinephrine in a single i.m. dose showed significant hypocholesterolemia and elevated, liver and kidney cholesterol levels 1–8 h postinjection. Plasma amino nitrogen evinced a transient yet significant fall at 2 h followed by a significant increase after 24 h. A marked reduction occurred in the plasma FFA and organic PO₄ levels after 1–8 h. The results offer little evidence for a lipolytic effect of epinephrine in this species, and the changes in metabolite levels are attributable, in part, to the catecholamineinduced modification of insulin secretion.N.K. thanks the U.G.C. for the award of a research fellowship.     

DhHP-6及Exenatide对胰岛β细胞的协同作用

采用葡萄糖和棕榈酸钠(Glu-Pal)联合诱导大鼠胰岛瘤RINm-5F细胞凋亡,用噻唑蓝比色(MTT)实验检测次血红素六肽(DhHP-6)和Exenatide分别或联合作用对细胞凋亡的影响.结果表明:DhHP-6和Exenatide均显著抑制Glu-Pal诱导β细胞凋亡,但二者无协同作用;DhHP-6和Exenatide均明显促进RINm-5F细胞增殖,且有显著的协同作用.     

无指盘臭蛙栖息地环境微生物及皮肤分泌物初步分析

在贵州水城县、云南官渡区、四川会理县和四川冕宁县采集了无指盘臭蛙动物样品,收集了其栖息地的水样及土样、以及环境因子.对所获土样和水样中的微生物进行了计数,并鉴定了优势细菌的种类及其丰度.进行了细菌总数和非优势细菌比例对无指盘臭蛙皮肤分泌物体重比关系的］初步分析.结果表明无指盘臭蛙皮肤分泌物体重比与土样中的细菌总数极显著地线性相关(p＜0.01),而分泌物体重比与土壤非优势细菌比例仅呈现粗略的对数关系(p＜0.1).     

尼克酰胺与exendin-4诱导胰腺干细胞向β细胞定向分化研究

目的体外分离胰腺干细胞,选择最佳培养条件探索胰腺干细胞在体外环境下向β细胞的分化情况.方法取SD大鼠胰腺组织,胶原酶消化,密度梯度离心获得纯化的胰腺导管上皮细胞.采用分步诱导法诱导胰腺导管上皮细胞向胰岛β细胞分化;用胰岛素释放实验检测胰岛功能,免疫荧光法检测nestin,PDX-1,CK-19,CK-20胰岛素及胰高血糖素等的表达.结果胰腺消化培养6～12h,可看到胰腺导管上皮细胞贴壁生长,通过4步诱导培养,nestin阳性细胞快速生长,并可分泌胰岛素.结论体外分离的成人胰岛前体细胞,在诱导因子的作用下,胰腺干细胞可定向分化为β细胞,有望应用于糖尿病的治疗.