Glucose-dependent insulinotropic polypeptide-producing K cells in dexamethasone-treated rats.

Some studies indicate that diabetes mellitus exerts an influence on the gastrointestinal tract and its diffuse neuroendocrine system (DNES) in regard to cellular density and neuroendocrine content. Since there is no data about relationship between experimentally induced non-insulin-dependent (type 2) diabetes mellitus (NIDDM) on the gut K cells, the aim of our study was to investigate immunohistochemical, stereological and ultrastructural changes of rat K cells after 12 days of dexamethasone treatment. Twenty male Wistar rats aged 30 days were given daily intraperitoneally 2 mg kg(-1) dexamethasone (group DEX, 10 rats) or saline (group C, 10 rats) for 12 days. Tissue specimens were obtained from each antrum with corpus and different parts of the small (SI) and large intestine (LI) of all animals. Immunohistochemistry was carried out using antisera against the GIP and insulin. Transmission electron microscopy was also used. Although, according to the literature data, rat K cells are present in the duodenum and jejunum and, to a lesser extent, in the ileum, in the present study we observed that those cells were abundant also in all parts of the LI. We observed generally that GIP-producing K cells were augmented in all parts of SI and decreased in the LI of DEX rats. Insulin immunoreactivity (ir) coexpressed with GIP-ir in K cells and was stronger in the SI of DEX rats as compared with C rats. We also found by electron microscopy that small intestinal K cells have features not only of GIP-secreted but also of insulin-secreted cells. We concluded that dexamethasone treatment caused proliferation of K cells in the rat SI, and simultaneously transformation of GIP-producing K cells to insulin-synthesizing cells.

Measurements of environmental background radiation at location of coal-fired power plants.

Environmental radiation monitoring in the vicinity of coal-fired power plants which are used primarily to determine the variability in measured background exposures are presented in this article; this is in order to estimate the contribution due to the plants' operation. Measurements have been done using a multi-element, high sensitive dosemeter system composed of three solid, properly filtered, sintered CaSO4:Dy thermoluminescent detectors, and one low-atomic number, MgB4O7:Dy,Na thermoluminiscencent detector produced at the Vinca Institute. The dosemeters were deployed quarterly 1 m above ground level at locations within 20 km of the power plants. Twenty urban and suburban measured stations were established. Measurements were carried out over one year period, from the beginning of the summer of 1995 to the end of the spring of 1996. The registered annual absorbed dose in air, from all of the 20 stations, vary from 0.91 to 1.46 mGy a(-1). One of the highest values of the annual absorbed dose was measured at the station near to the plant, i.e. at the place the most exposed to the lighter fly ash from the plant stack, as it was expected. The annual absorbed dose registered at the measuring stations that were selected as a control because they were situated practically away from possible influence of the plants were from 0.91 to 0.98 mGy a(-1). The above values of absorbed doses become very important, by concurrence of the circumstances, because they represent the zero background radiation level before the incidence of depleted uranium over former Yougoslav territory in the Kosovo region in the spring of 1999. These measured absorbed dose exposures have to be compared with corresponding absorbed dose rates from the natural sources, such as soil having an exposure of 18-93 nGy h(-1) (average 35 nGy h(-1)) according to the UNSCEAR 2000 Report. This investigation has been primarily done in order to check the impact of coal-fired power plants on the background radiation level in its vicinity. According to the experimental results, influence was confirmed both qualitatively and quantitatively.

Pancreatic polypeptide cells of rat pancreas after chronic ethanol feeding.

Male Wistar rats, (2 months old) were randomly divided into two groups according to the diet offered (C-control and E-ethanol treated rats). Final body weight was significantly increased but pancreatic weight as a percentage of body weight was decreased in ethanol treated rats. Volume density, number of pancreatic poly peptide (PP)-cells per islet and per micron 2 of islet were significantly increased. PP-cells were abundant and occupied the whole periphery of islets in the splenic part of the pancreas. Those cells showed strong immunopositivity. At the ultrastructural level PP granules had predominantly less electron density. The mean diameter of PP granules was significantly increased and the number of granules of larger diameter was greater in the E group of rats, than in the controls.

Rat pancreatic B-cells after chronic alcohol feeding. A morphometric and fine structural study.

Quantitative analysis of the light microscopic and fine structure of rat islet B-cells was carried out in chronic alcoholism. Absolute pancreatic weight and volume were similar in groups C (control) and E (ethanol), but relative pancreatic weight in group E rat was decreased. The results for fasting blood glucose and insulin levels were similar in the two groups of animals. There was a significantly reduced total pancreatic islet volume in E rats. The total number of endocrine cells both per islet and per microns2 of islet was similar in the two groups of animals. The volume density and number of B-cells per islet and per microns2 of islet were not changed in ethanol-treated rats as compared with the control. On the other hand, diameter, surface area and volume of the B-cells and their nuclei were found to be statistically significantly decreased. Histological examination revealed that islet blood vessels were dilated in alcoholic rats. Over the 4-month period of ethanol intake a significant decrease in cell profile area, nuclear profile area and volume density of cytoplasmic granules and an increase in the profile area and volume density of endoplasmic reticulum occurred. The gross histological alteration seen in most B-cells of the ethanol-treated rats was irregularity of the nuclear envelope with deep invagination and with margination of heterochromatin and many empty granules or granules without clear electron dense crystals of insulin. The present results indicate some optical and structural abnormalities of B-cells in chronic alcoholism that may be related to cell dysfunction and may contribute, at least in part, to the endocrine pancreas functional disturbance.