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C Remacle

Publications and source records attributed to C Remacle.

At least 91 records · Page 5Linked to original sources
PubMed1987

Localization of high-affinity GABA uptake and GABA content in the rat duodenum during development.

The localization of high-affinity uptake sites for 3H gamma-aminobutyric acid (3H-GABA) was investigated in the rat duodenum during ontogenesis and also at the adult stage (from 15.5 days of fetal life up to 105 days post natum) by means of low- and high-resolution autoradiography. At all stages studied, specific endocrine cell types of the epithelium were labelled and an intense uptake was detected in the nervous tissue, especially in glial cells but also in scarce neurones. When the incubation medium was supplemented with beta-alanine (1 mM), a blocker of the glial uptake for GABA, the labelling persisted only in endocrine cells and in few neurones. The intensity and the frequency of the labelling decreased at later periods compared to the earlier developmental stages. The GABA content of the duodenum as measured by a new ion-exchange column chromatography-HPLC-coupled method was higher in the early postnatal period compared to later stages. These observations suggest that GABA, in addition to being a neurotransmitter, may play an important role during development of the duodenum.

Aging↗
PubMed1987

Ultrastructural aspects of streptozotocin cytotoxicity on rat pancreatic islets in vitro. Test of a protective effect of zinc.

Pancreatic islets, newly formed in vitro were incubated in the presence of streptozotocin (STZ; 0.4 mM) for up to 6 h. Ultrastructural changes first appeared between 2 and 4 h; heterochromatization, was followed by swelling of nuclear and reticular membranes, vesiculation of the Golgi apparatus, fragmentation of cell membranes and finally mitochondrial destruction. At the end of the experiment all the B cells were destroyed, whereas the other cell types remained intact. Exogenous ZnSO4 was added during preincubation periods to increase the intrainsular zinc content and to determine any protective effect against STZ-cytotoxicity. Since the addition of zinc had no obvious effect, it is suggested that STZ cytotoxicity on B cells cannot be attributed to competition for zinc between copper-zinc superoxide dismutase (Cu-Zn-SOD) and the crystallization of insulin.

Animals↗
PubMed1987

Effect of aging on the morphology of epididymal adipose tissue in the rat.

Quantitative morphometrical parameters were compared in epididymal adipose tissue of adult (6 months old) and old (24 months old) Wistar rats, using light and electron microscopy of embedded material and freeze-etch replicas, and taking into account the functional unit of adipose tissue: the capillary-adipocyte. Despite an insignificant reduction of the adipocyte number and size in old rats when the whole population was sampled, the confounding factor of size of adipocytes could be excluded from morphometric computations in adult and old rats. Morphometric measures were performed on the whole transit from capillaries to adipocytes. They revealed that the plasma membranes, as seen in freeze etching, and the thicknesses of endothelial and adipocyte cytoplasms, as seen in ultra-thin sections, remained unaltered with aging. By contrast, the basement membranes were changed but differently around capillaries and adipocytes. The capillary-adipocyte distances were shorter and the vascularization density was higher in old rats.

Adipose Tissue↗
PubMed1987

Lessons from the pathology of the diabetic pancreas.

Different events such as virus infections, toxins, nutritional factors, antiinsulin antibodies may be rendered responsible for the pathological changes in the pancreatic B-cell and result in a diabetic state in the postnatal, adolescent or adult age. These different interferences which may lead to the diabetic state need full consideration and assessment if prevention and cure are to be considered.

Adult↗
PubMed1986

Morphology and fibrinolytic activity of canine autogenous mesothelium used as venous substitute.

Autogenous mesothelium was used as venous substitute in ten dogs. Patches of mesothelium of three different origins were grafted into the anterior wall of the common iliac veins (CIV): peritoneum taken from and including the posterior rectus sheath (PRS), simple peritoneum (P) and mesentery (M). Animals were killed after 2, 4, 8, and 16 days and after 3 months. The segments of CIV, including the patches, were removed for study. On light microscopy, the PRS grafts showed a normal mesothelium but marked submesothelial fibrosis. The M and P grafts showed normal mesothelium and only mild fibrous thickening. On scanning electron microscopy, there was a perfect continuity of the mesothelial cells and the normal endothelium at the suture line. In the center of the graft, the cells had become elongated along the axis of blood flow. Fibrinolytic activity (FA) was measured by a standardized fibrin plate technique and quantitated in tissue activator units per gram of tissue (TAU/g). The mean FA of iliac vein specimens was 1101.7 +/- 133.3 TAU/g (mean +/- SEM). The mean FA determined before grafting for each kind of mesothelium was the following: PRS = 418.8 +/- 26.9 TAU/g; P = 873.0 +/- 107.1 TAU/g; M = 1142.3 +/- 91.4 TAU/g where only PRS showed values significantly lower than iliac vein mean FA (P less than 0.001). Postoperatively, the mesothelial FA, after an initial reduction, increased on day 4 and reached values significantly higher than the control values (1445.7 +/- 204.1 TAU/g tissue vs 853.1 +/- 62.3 TAU/g tissue; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Cell interactions during the in vitro neoformation of fetal rat pancreatic islets.

As shown by scanning electron microscopy, transmission electron microscopy and membrane labeling analysis, the in vitro neoformation of rat pancreatic islets arose from two main processes: a budding from explants containing duct cells, and a competition between endocrine monolayers and fibroblasts on the culture substratum. The stronger cytoskeleton of fibroblasts and their higher adhesive properties, probably related to their more homogeneous distribution of membrane charges, may explain the spherization of the islets. The pure endocrine cell population of neoformed islets was composed mainly of insulin-secreting cells, and the other types of endocrine cells were distributed in the periphery. Preformed extracellular matrices of osmotically disrupted fibroblasts enhanced the yield of the cultures by increasing the anchorage of endocrine cells and slowing down the fibroblastic growth.

Animals↗
PubMed1986

Ultrastructural analysis of the in vitro differentiation of female rat preadipocytes.

In an attempt to characterize the preadipocytes of the adipose tissue of female rat, we studied by electron microscopy the differentiation of the cells into mature adipocytes in in vitro cultures. The preadipocytes arose from the stroma-vascular fraction of perirenal and perigenital adipose tissue. Culture of the preadipocytes in an enriched medium consisting of Dulbecco's medium supplemented with 10% fetal calf serum, antibiotics, rat triglycerides (0.5%), insulin (290 nM) and Tween 80 (0.1 mg/ml) induced their adipose conversion. The morphology of preadipocytes changed progressively. They accumulated fat granules, droplets and finally globules, which fused together. The cell organelles featured qualitative and quantitative modifications. The nucleus migrated with most mitochondria and a part of the Golgi system towards the cell periphery; the rough endoplasmic reticulum, dilated at the initial stage of differentiation became less and less conspicuous; the perinuclear Golgi system was dispersed between lipid droplets during fat accumulation; thick bundles of microfilaments, localized beneath the plasma membrane disappeared; large lipid droplets were surrounded by a network of microfilaments; many microvesicles and some "rosettes" typical of mature adipocytes could be observed. Nevertheless, the ultrastructural criteria did not allow to clearly discriminate the undifferentiated cells: early preadipocytes (without lipid droplets), adipoblasts and fibroblasts, all of these being probably present in the culture system.

Adipose Tissue↗
PubMed1985

Morphological and functional characteristics of islets neoformed during tissue culture of fetal rat pancreas.

Cell suspensions prepared by collagenase digestion of the pancreas of rat fetuses (21.5 days) were cultured for 7-9 days in RPMI medium containing 10 mM glucose. Exocrine cells disappeared rapidly, whereas fibroblasts and endocrine cells proliferated. These latter were first arranged in monolayers but progressively reorganized in neoformed islets essentially composed of B-cells. Total insulin content of the culture dishes increased until day 9, and fractional insulin release was about 20% per day. After 1 week, islets incubated in glucose-free medium released less than 1% of their insulin content over 2 h. Glucose (16.7 mM) caused a slower and weaker (3-fold) stimulation than 10 mM leucine or arginine (3-5-fold). The effects of the three secretagogues were potentiated by theophylline, but only those of glucose and leucine were inhibited by diazoxide. These neoformed islets thus retain a fetal character (relatively low responsiveness to glucose), but the stimulus-specificity of the inhibition by diazoxide is the same as in adult islets. This technique may be useful for studying the mechanisms which govern the organization of pancreatic endocrine cells in islets, and which underlie their functional maturation during the perinatal period.

Amino Acids↗
PubMed1984

Localization of GABA high-affinity binding sites in the pancreas of neonatal rat.

The localization of gamma-aminobutyric acid (GABA) high-affinity binding sites was investigated in the exocrine and endocrine pancreas of neonatal rats by means of 3H-GABA autoradiography. GABA-binding was identified on Schwann cells and on the cells of the intralobular excretory ducts. In the endocrine part of the pancreas, no labelling was observed except in peripheral islet cells which, on the basis of their scarcity and distribution, could be somatostatin cells. Furthermore, peri-insular innervation showed considerable labelling.

Animals↗
PubMed1984

Cell proliferation in pancreatic islets of rat fetuses and neonates from normal and diabetic mothers. An in vitro and in vivo study.

The influence of diabetic pregnancy on the fetal and newborn endocrine pancreas of rats was investigated in vitro and in vivo. A mild diabetic state was induced experimentally in the mother with 30 mg streptozotocin injected in the vein of the tail on the first day of gestation. The maternal blood sugar was 326 +/- 28 mg/dl at the end of the gestation. The in vitro experiment was performed on fetuses of 21.5 days. The endocrine pancreases were cultured during four or seven days and incubated the last 24 hours with tritiated thymidine. The healthy state of the islet cells after the two respective periods of culture was confirmed by an electron microscope study. After incubation with tritiated thymidine, a significantly higher percentage of labelled nuclei was observed in the islets of the diabetic group when compared with the controls. This was apparent after four days (diabetics: 54% - controls: 50%) and is obvious after seven days (diabetics: 28.8% - controls: 18%). For the in vivo experiment, two day old rats born at term from normal or diabetic mothers were injected (s.c.) with tritiated thymidine and killed two hours later. The proliferative capacity of the islet cells of pups born from diabetic mothers compared to the controls was higher when the percentage of labelled nuclei was calculated (respectively 5.4% versus 3.8%). An islet hypertrophy was also found in the diabetic group. In conclusion, our results combining in vitro techniques with in vivo observations demonstrate the higher proliferative rate of the fetal endocrine pancreas induced by a mildly diabetic feto-maternal environment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Organ culture of the Islets of Langerhans from young and senescent rats.

The B-cells of the endocrine pancreas constitute an adequate model for in vitro study of the aging process in highly differentiated cells. In the present study, collagenase-isolated islets of Langerhans from young and senescent rats were cultured up to 28 days. The response of the B-cells to the stimulatory conditions of the culture medium involved the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, and secretory granules. Correlated data from light microscopy, electron microscopy, and insulin radioimmunoassay show that the differentiation and function of senescent B-cells are maintained in culture, as it has been proven for the B-cells of younger animals. On the other hand, signs of cytological deficiency not directly concerned with the specific function of B-cells were observed: abnormal mitochondria and lysosomes are more numerous in the senescent B-cells. The proliferative capacity of the B-cells of aged rats is reduced.

Aging↗
PubMed1980

Nuclear events in B-cells of young and senescent rat islets in organ culture.

In vitro, B-cells maintain their capacity to multiply. However, the number of mitotic figures observed in cultured rat Langerhans islets is far larger for young donnor animals than for old ones. The same observation is true for the number of nuclei incorporating tritiated thymidine in vitro. These data are in agreement with the principal observation resulting from the study of senescence on different in vitro cellular models: the decrease of the replication potential with increasing age. The stimulation of DNA synthesis by glucose, however, does not seem to be altered with aging.

Aging↗
PubMed1977

Gonads of Carassius auratus (teleosts) in organ culture: a new technique and the effects of testosterone.

The use of a semi-natural medium (Eagle's MEM supplemented with chicken embryo extract) appears to be satisfactory for ovarian and testicular fragment cultures of Carassius auratus. The male germ cells show a normal degeneration which might be attributed to a lack of pituitary hormones: gonadotropic and, possibly, somatotropic hormone. The ovarian fragments maintain a normal organization during 21 days of culture. Only the oocytes in late vitellogenesis massively atresiate at the beginning of culture. The addition of fetal bovine serum to this medium produces surprising effects on the testicular explants, particularly on the spermatogonial mitoses. This might be attributed to the presence of STH and androgen in the serum. The modifications of ovarian explants, on the other hand, are identical to those observed with Eagle's MEM supplemented with chicken embryo extract. M 199 has been tested as a synthetic medium; the preliminary results are encouraging. Testosterone, when added to the semi-natural medium, permits complete spermatogenesis in the testicular fragments during the 21 days of culture, but does not produce any effect on the ovarian explants.

Animals↗