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Biomedical subjects

J Boyer

Publications and source records attributed to J Boyer.

At least 199 records · Page 11Linked to original sources
PubMed1987

[Mixed carcinoid tumor-adenocarcinoma of the stomach. Review of the literature, apropos of a case].

We report a case of mixed tumor of the stomach with a double histological population: carcinoid and adenocarcinoma. The carcinoid component presented an usual morphological pattern with "atypical" elements, and without argyrophilic cells; the carcinoid cells were exclusively marked by an anti-serotonin serum. The other component was a poorly differentiated carcinoma, with muco secretion, which was not marked by and anti-carcino-embryonic antigen serum. The limit between the two components was sharp. The association of mucin in the carcinoma and serotonin in the carcinoid component was an argument in favour of the diagnosis of mixed tumor carcinoid-adenocarcinoma (composite tumor) of the stomach. The evolution after operation leaded to a local recurrence and to the death 10 months later, in spite of chemotherapy. The existence of composite tumors raises nosological, histogenetical and diagnostic problems, which are discussed in this work. The prognosis of these tumors is unknown and therapeutic possibilities seem to be scanty.

Adenocarcinoma↗
PubMed1986

Use of specific collagenases for the isolation of rat liver cells with preserved lipase activities.

The heparin-releasable neutral lipase (EC 3.1.1.3) from rat liver is inactivated by the common preparations of collagenases (EC 3.4.24.3) used for the isolation of liver cells. We show that two collagenases purified from Clostridium histolyticum allow both the complete preservation of this lipolytic activity and a good viability of liver cells isolated by the usual perfusion protocol.

Animals↗
PubMed1986

Progesterone and cAMP-dependent protein kinase regulate in vivo the level of phosphorylation of two proteins (Mr 20,000 and Mr 32,000) in Xenopus oocytes.

The [32P]phosphoproteins and [35S]thiophosphoproteins were analyzed by electrophoresis and autoradiography after microinjection of [gamma-32P]ATP or of [35S]ATP-gamma-S into living Xenopus oocytes. The level of 32P incorporation into a 20-kDA protein was decreased following progesterone treatment (between 1 and 2 hr). This 20-kDa protein was partially thiophosphorylated in vivo by [35S]ATP-gamma-S. Furthermore it was found that this phosphoprotein was partially purified by TCA (1%) extraction and heat treatment. Microinjection of the C-subunit of cAMP-dependent protein kinase (0.6 to 1.2 pmole) inhibited maturation and provoked an increase in the level of phosphorylation of the 20-kDa protein and of a 32-kDa protein, indicating that both proteins were in vivo substrates (directly or indirectly) for cAMP-dependent protein kinase. When inhibitor-1 of protein phosphatase-1 was microinjected (5 to 10 pmole per oocyte) meiotic maturation was inhibited and the level of phosphorylation of the 32-kDa protein was increased; the same result was obtained following ATP-gamma-S (1 mM) microinjection. Altogether these results suggest that a 20-kDa phosphoprotein, whose level of phosphorylation is decreased by progesterone, could be involved in the regulation of maturation by lowering the level phosphorylation of a 32-kDa phosphoprotein. An attractive hypothesis would be that the 20-kDa phosphoprotein is an inhibitor of protein phosphatase-1.

Adenosine Triphosphate↗
PubMed1986

Effects of 2-fluoroestradiol on lipid metabolism in the ovariectomized rat.

Biological activities of estrogen molecules are altered by fluorination of ring A, and the resulting impairment to form catechols. 2-fluoroestradiol (2-F-E2) has been found to be devoid of carcinogenic action despite its high estrogenic potency; its metabolic effects are so far unknown. This study was designed to investigate the effects of 2-F-E2 on lipid metabolism, as compared to those of estradiol-17 beta(E2). Ovariectomized rats received E2 or 2-F-E2 by s.c. injection at a dose of 60 micrograms for three consecutive days. Parameters measured were weights of parametrial fat depots, fat cell volumes, levels of triacylglycerol and acylcholesterol in plasma, and enzymatic responses to the estrogens in isolated parametrial fat cells as evaluated in terms of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) activities. 2-F-E2 and E2 were found to produce comparable decreases in fat depots, cell volumes and plasma levels of acylcholesterol whereas plasma triacylglycerol was unchanged. Both estrogens decreased LPL, and increased HSL activities to the same extent. Thus, 2-F-E and E2 exhibited comparable effects on lipid metabolism. These effects appeared to depend mainly on the estrogenic potency of these molecules, and to be distinct from their carcinogenic action. Despite its high estrogenic potency, 2-F-E2 was found to be slightly less estrogenic than E2.

Adipose Tissue↗
PubMed1986

Ethynylestradiol alters lipid composition and phosphatidylethanolamine metabolism in red blood cells.

Treatment of female rats with ethinylestradiol at a dose of 60 micrograms/rat, daily for 21 days, produced marked changes in red blood cell lipids. Cholesterol was decreased by 22% and total phospholipids were increased by 13%, resulting in a 31% decrease in the cholesterol to phospholipid ratio. The mass distribution of phosphatidylcholine and phosphatidylethanolamine relative to total phospholipids was unchanged. Whereas control red cells incorporated preferentially fatty acids in phosphatidylcholine, ethinylestradiol stimulated their incorporation specifically in phosphatidylethanolamine, where increases occurred with palmitic acid (+75%), oleic acid (+68%) and arachidonic acid (+31%). Incorporation in phosphatidylcholine was unaffected with any of the 3 fatty acids. The stimulation of fatty acid incorporation in phosphatidylethanolamine is likely to reflect an estrogen-dependent increase in turnover rate of fatty acids in this phospholipid. Such alterations in lipid composition and fatty acid incorporation in red cell phospholipids may have significant effects on membrane function.

Animals↗
PubMed1986

Stimulation of brain lipase activity by polyamines. Comparison with the effect of ACTH.

Polyamines, as well as ACTH, strongly stimulate at pH 5.75 triacylglycerol lipase (TAGL) activity from rat brain. Whether the activating potency is expressed in terms of molar concentration or amount of positive charges, polyarginine, polylysine, spermine and spermidine exhibit, in this order, decreasing potencies. By contrast to other lipases, heparin (25 micrograms/ml) inhibits brain TAGL. Polyarginine, polylysine and spermine reverse the heparin-dependent inhibition and further stimulate TAGL activity above basal values; spermidine is much less potent. In the presence of heparin, ACTH has the greatest stimulating effect, being 1.6-fold and 3.3-fold more potent than polyarginine and polylysine, respectively. Taken together, the data suggest that polybasic effectors modify the interaction of TAGL with its substrate, resulting in increased levels of TAGL activity. In the presence of heparin, the enzyme charge density is mandatory for determining the stimulation process. Such cationic interactions appear to be specific of brain TAGL and should be considered in assessing any direct neuro-hormonal role to ACTH or physiological polyamines in brain.

Adrenocorticotropic Hormone↗
PubMed1986

Increased monoester lipase activity of red blood cells in alcoholism.

Monoester lipase activity was assayed by a radiochemical assay in the red blood cells (RBC) from 50 chronic alcoholic patients within 48 hr after discontinuation of chronic alcohol intake and from 40 nonalcoholic control subjects. The mean value of lipase activity was increased to 1213 +/- 229 milliunits/10(12) RBC in the alcoholics as compared with a value of 997 +/- 120 milliunits/10(12) RBC in the controls (p less than 0.001). The lipase increase was associated with increased values of the mean cellular volume of RBC. A subgroup (64%) of 32 alcoholic subjects with macrocytosis (mean cellular volume greater than 96 femtoliters) showed the highest mean lipase activity (1276 +/- 224 milliunits/10(12) RBC) as compared with a value of 1101 +/- 196 milliunits/10(12) RBC in the normocytic alcoholic subgroup (p less than 0.05). This latter subgroup had a mean value higher (p less than 0.05) than that in the control group. The relationship between values of mean cellular volume and lipase activity was not of predictive value in individual cases. The enzymatic increase was not related to a direct effect of alcohol on the intact RBC. It is postulated that this alteration might result from changes in the chemical and/or physical state of the plasma membrane induced by ethanol during RBC formation. In any event, the increased lipolytic activity of RBC represents a new biological characteristic of alcoholic subjects. Its determination might represent a noninvasive way of evaluating the influence of alcohol on a tissue parameter.

Adult↗
PubMed1986

Increased monoester lipase activity in red blood cells during hyperthyroidism.

Human red blood cells (RBC) contain a monoester lipase (MEL) activity which is tightly associated with the cell membrane and has its active site externally oriented, as inferred from the ability of the intact cell to hydrolyse an exogenously added lipid substrate. Membrane-bound MEL activity was measured by a radiochemical assay in intact RBC from 29 untreated hyperthyroid patients. The mean (+/- S.D.) MEL level was higher (P less than 0.01) in these patients (1220 +/- 212 mu./10(12) RBC) than in the control group (1010 +/- 120 mu./10(12) RBC). There was no difference between men and women. The increase in MEL values was associated with significantly (P less than 0.001) decreased values of mean cellular volume and mean cellular haemoglobin content. A continued study of 13 patients, who became euthyroid with treatment, showed a normalization of the MEL values in RBC. The increased lipolytic potency of RBC represents a new characteristic of hyperthyroid patients. Further exploration of the possible diagnostic or prognostic implications of this enzymatic change seems warranted.

Adolescent↗