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G Chevalier

Publications and source records attributed to G Chevalier.

At least 91 records · Page 5Linked to original sources
PubMed1980

Electrophysiological evidence for non-dopaminergic mesocortical and mesolimbic neurons in the rat.

The neurons located in the ventromedial tegmentum (VMT) and projecting either to the frontal cortex, to the septum or to the nucleus accumbens were identified by the antidromic activation method in normal rats and in animals whose dopaminergic (DA) systems had been previously lesioned by microinjections of 6-hydroxydopamine (6-OHDA). Two groups of VMT neurons innervating each structure could be distinguished. The first group (group S) are slow conducting neurons whose number is reduced in 6-OHDA lesioned rats and which may correspond to A10 DA neurons. The second group (group F) are fast conducting neurons which are resistant to 6-OHDA treatment and therefore probably non-DA VMT cells.

Animals↗
PubMed1980

Vasoactive intestinal peptide control of cyclic adenosine 3':5'-monophosphate levels in seven human colorectal adenocarcinoma cell lines in culture.

This study was undertaken to assess the role of vasoactive intestinal peptide (VIP) in the control of cyclic adenosine 3':5'-monophosphate production in colonic tumor cells. Seven human colorectal adenocarcinoma cell lines in culture were investigated (HT-29, HRT-18, SW-480, Caco-2, CO-115, CO-125, and HCT-8R). These cell-lines had a cyclic adenosine 3':5'-monophosphate production system which was very sensitive to VIP but less so to prostaglandin E1 and/or isoproterenol. Nonintestinal human malignant epithelial cells, such as HeLa (cervix) and Caki-1 and Caki-2 (kidney), by contrast, did not respond to VIP. The dose-response relationships of malignant colorectal cells were compared to those obtained with epithelial cells of normal human colon and showed that: (a) maximal responses were observed with 0.1 micro M VIP in both malignant and normal cells; (b) half-maximal responses were elicited by VIP concentrations in the 0.3 to 2 nM range in malignant cells (1.2 nM in normal cells), thus indicating the high apparent affinity of the cells to VIP; and (c) the magnitudes of the responses (stimulated:basal ratios) were highly variable in malignant cells, ranging from 225 in HT-29 cells to 3.5 in Caco-2 cells, but were more constant, in the order of 25, in normal cells. Secretin, a VIP agonist in intestinal tissue, stimulated cyclic adenosine 3':5'-monophosphate accumulation in all colorectal cells, but with a 1000- to 5000-fold lower potency than did VIP. These results show that the VIP-sensitive adenylate cyclase system operates in malignant as well as in normal colon epithelial cells.

Adenocarcinoma↗
PubMed1980

Growth-related glycogen levels of human intestine carcinoma cell lines grown in vitro and in vivo in nude mice.

The relationship known to exist in vitro between glycogen accumulation and the growth of malignant human intestine epithelial cells was investigated in vivo. The glycogen concentration of 7 human intestine carcinoma cell lines (Caco-2, HT-29, HRT-18, HCT-8R, CO-115, SW-480, and HuTu 80) was measured during cell growth for the in vitro series and during the course of tumor growth for the in vivo series. The glycogen stores were compared for these cells in vitro and after their injection in noninbred Swiss athymic nude mice. The tumors and cultured cells were ranked identically on the basis of glycogen level (Caco-2 > HRT-18 > HT-29 > HCT-8R > CO-115 > SW-480 > HuTu 80). Values for the tumors ranged from 128.8 +/- 10.8 micrograms glycogen/mg protein for Caco-2 tumors down to 2.9 +/- 0.9 micrograms for HuTu 80 tumors; similar values were found for the exponentially growing corresponding cultured cells. The tumor glycogen concentration was independent of the host's nutritional state: Glycogen concentration differed from one type of tumor to another despite its constant level in the liver; fasting did not cause tumor glycogenolysis. By the two experimental approaches, results varied during the growth phases: Stationary phase glycogen concentration increased threefold to fourfold for all cultured cell lines; tumor glycogen concentration, by contrast, was stable throughout the growth period. An inverse relationship was nonetheless found between the rate of tumor growth and tumor glycogen concentration; the highest glycogen content was associated with the slowest growing tumors, and conversely. Apparently, elevated glycogen concentration is regularly associated with decreased cell division rates in vitro and in vivo.

Adenocarcinoma↗
PubMed1979

Presence and cell growth-related variations of glycogen in human colorectal adenocarcinoma cell lines in culture.

The presence and kinetics of intracellular glycogen levels were studied, in relationship to cell growth, in asynchronous and in synchronized cultures of four human colorectal adenocarcinoma cell lines (HT-29, HRT-18, SW-480, and Caco-2). The results show that a specific pattern of glycogen accumulation occurs during the process of cell growth of the studied cell lines. The kinetics of glycogen accumulation in asynchronous cultures were similar from one cell line to another and were characterized by a low amount in the exponential phase of growth, followed by a 3- to 4-fold increase in the stationary phase. The quantities found in either phase were specific for each cell line. The maximum values found in Caco-2, HRT-18, HT-29, and SW-480 cells were, respectively, 258.5 +/- 6.9 (S.D.), 88.9 +/- 2.6, 87.5 +/- 3, and 17.5 +/- 1.8 microgram of glycogen per mg of proteins. The kinetics of glycogen accumulation during the cell cycle was also studied in synchronized cultures of HT-29 and HRT-18 cell lines. Both cell lines exhibited a common pattern of low glycogen quantities during S, G2, and M followed by an increase beginning with G1 and peaking (2.5 to 3 times the initial values) in the middle of this phase. This was followed by a symmetrical decrease in the second half of G1.

Adenocarcinoma↗
PubMed1978

[Phenotypic expression of colon polymorphic antigens (WZ) in human colon adenocarcinomas].

Human colon adenocarcinomas from 52 patients were investigated for the presence of the colon polymorphic antigens WZ. The patients were typed for their WZ phenotype, using the immunofluorescence method on non tumoral colon mucosa sections: 27 patients were found W+ Z+, 18 W- Z+, and 7 W- Z-. The tumors were tested for the presence of the WZ phenotypes, using the immunofluorescence method and a radio-immunoassay. The WZ phenotypes were not expressed in the non secreting tumors, whatever the patient's phenotype. They were expressed in the secreting tumors and had the same phenotype as found in the corresponding normal mucosa. The WZ phenotypes were present in human developed into "nude" Mice inoculated either with differentiated colon carcinomas, or with a human colon carcinoma cell line (HT-29).

Adenocarcinoma↗
PubMed1978

Vasoactive intestinal peptide: a potent stimulator of adenosine 3':5'-cyclic monophosphate accumulation in gut carcinoma cell lines in culture.

Vasoactive intestinal peptide (VIP) is a potent and efficient stimulator of adenosine 3':5'-cyclic monophosphate (cAMP) accumulation in a human colon carcinoma cell line, HT 29. cAMP accumulation is sensitive to a concentration of VIP as low as 3x10(-12) M. Maximum VIP-induced cAMP levels were observed with 10(-9) M VIP and are about 200 times above the basal levels. Half-maximum cAMP production was obtained at 3x10(-10) M VIP. (125)I-Labeled VIP was found to bind to HT 29 cells; this binding was competitively inhibited by concentrations of unlabeled VIP between 10(-10) and 10(-7) M. Half-maximum inhibition of binding was observed with 2x10(-9) M VIP. Secretin also stimulated cAMP accumulation in HT 29 cells, but its effectiveness was 1/1000 that of VIP. The other peptides tested at 10(-7) M, such as insulin, glucagon, bovine pancreatic polypeptide, somatostatin, octapeptide of cholecystokinin, neurotensin, and substance P, did not stimulate cAMP accumulation. Prostaglandin E(1) and catecholamines stimulated cAMP production but were 1/2.3 and 1/5.5 as efficient as VIP, respectively. Another malignant cell line from the gut, the human rectal tumor cell line HRT 18, is also sensitive to VIP. In HRT 18 cells, VIP stimulated cAMP accumulation with a maximal effect at 10(-8) M; half-maximum stimulation was observed at about 10(-9) M. These results demonstrate the presence of VIP receptors in two malignant human intestinal cell lines (HT 29 and HRT 18) in culture and provide a model for studying the action of VIP on cell proliferation.

Adenocarcinoma↗
PubMed1977

[Identification and quantitation of impurities from benorilate (Salipran) by high-performance liquid chromatography (author's transl)].

High-performance liquid chromatography is used for identification and quantitation of impurities which may be encountered in a new antalgic, benorilate (or Salipran), an ester of aspirin with paracetamol. Gradient elution is carried out using a stationary phase consisting of porous 10-micron silica beads bonded to alkylnitrile (Micropak CN), and a mixture of hexane-methylenechloride-methanol-acetic acid with varying methanol percentage as mobile phase. The following impurities were separated from benorilate: acetylsalicylic anhydride, aspirin, acetylsalicylsalicylic acid, salophene, amino-4-phenylacetoxy-2-benzoate, paracetamol, p-aminophenol. The repeatability of the quantitative analysis is good with a standard variation of 0.54% for benorilate (7 injections). Detection is by UV absorption at 254 nm, and detectability is between 2-10(-9) moles for p-aminophenol and 4-10(-11) moles for salophene.

Chromatography, High Pressure Liquid↗
PubMed1977

Morphological aspects of type II alveolar pneumocytes following treatment with puromycin in vivo.

Ultrastructural modifications of type II pneumocytes (PNM-II) in mice were analysed 125 and 155 minutes after puromycin treatment (12 mg/100 gm at 0, 30, 60 and 90 minutes). A quantitative evaluation of the cell compartments was carried out and the inhibition of protein synthesis in PNM-II was monitored by light microscopic radioautography, following 3H-leucine injection. In electron micrographs, following a 125-minute puromycin treatment, the number and size of lamellar bodies, the precursors of lung surfactant material appeared markedly reduced. The multivesicular bodies (MVB), which are normally very frequent in PNM-II, had almost completely disappeared, as had composite bodies. Golgi saccules were dilated, while the area occupied by Golgi vesicles was enlarged. Observations following the 155-minute puromycin treatment showed a strong enhancement of these modifications. Smooth and coated vesicles of the Golgi area, as well as peroxisomes, did not appear modified by puromycin. Elongated zones of autophagy were more prevalent after 125-minute treatment than after the 155-minute one. Small bodies were frequently observed in the cytoplasm, near the Golgi zone. They were bounded by a smooth membrane and contained tiny vesicles and/or electron-dense lamellae similar to those present within the lamellar bodies. Parallel membranes formed folds, some of them in continuity with lamellar bodies, thus encircling portions of cytoplasm. These structures, which were few in number in controls, were very frequently observed in treated cells, mainly after the 125-minute treatment. These extensive alterations of PNM-II morphology appeared to be related to a disturbed production of pulmonary surfactant.

Animals↗
PubMed1977

Absorption and elution of anti-DLA-A and B antibodies with acetone-dried dog spleen powder.

Acetone-dried powders were prepared from the spleens of DLA-serotyped dogs and assayed for their specific absorptive properties for anti-DLA-A and B antisera. The specific activity of two different antisera (anti-DLA-A9 and anti-DLA-B13) was readily absorbed with acetone-dried powders prepared from the spleens of dogs of the corresponding DLA types. This specific activity was recovered by the elution of the powder used for the serum absorption. The same method was used to narrow the specificity of a highly polyspecific antiserum. The comparison of the absorption properties of acetone-dried spleen powder versus fresh spleen cells shows that the treatment with acetone does not modify qualitatively and quantitatively the DLA specificities.

Acetone↗
PubMed1977

Radioimmunoassay of the WZ polymorphic antigens of normal human colon and their relationship with ABH antigenic determinants.

Heat resistant, high mol. wt glycoproteins of the three WZ phenotypes (W+Z+, W-Z+ and W-Z-) were extracted from normal human colonic mucosa and labelled with 125I. More than 80 per cent of the radioactivity of the W+Z+ antigens labelled with I125, was precipitated by natural or immune anti-W antibodies. About 60 per cent of the W-Z+ 125I-labelled antigens were precipitated by immune anti-Z antibodies. No specific precipitation could be detected with W-Z- 125I-labelled antigens. All the precipitin reactions were quantitatively inhibited with the crude antigen extracts of the corresponding phenotypes. The W and Z antigens were only found in the intestinal mucosa and there was a 100-fold increase in the relative concentrations between the small bowel and the rectum. As opposed to this, the ABH antigens were found in all the digestive secretions studied, except those of the rectum, and their relative concentrations progressively decreased by about 100 between the small intestine and the recutm. The decrease in ABH concentration seems to be correlated to a WZ increase in the same regions.

ABO Blood-Group System↗
PubMed1976

[High-performance liquid chromatography of penimocycline (author's transl)].

Penimocycline is an antibiotic obtained by Mannich reaction between tetracycline and ampicilline. Separation of penimocycline from tetracyclines and other impurities has been studied by high-performance liquid chromatography. The most effective method is liquid-liquid partition on a Micropak CH column (non-polar hydrocarbon bonded on porous silica microparticles) and gradient elution with water-methanol, 0.02 M phosphate buffer (pH 7.6) and 1 mM EDTA. Some results on hydrolysis of penimocycline are given.

Ampicillin↗