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Biomedical subjects

J Boyer

Publications and source records attributed to J Boyer.

At least 235 records · Page 13Linked to original sources
PubMed1984

[Bronchogenic cysts and their atypical localizations. A case of pleuro-diaphragmatic cyst].

Bronchogenic cysts represent about 10 p. 100 of all surgical tumours of the mediastinum. They can never be diagnosed with absolute certainty prior to the operation, but when they arise in their typical sites, they can be suspected with a high probability. However, they can occur in very atypical sites, in which case the diagnosis remains very hypothetical until the operation. The authors report a case of a cyst which developed under the diaphragmatic pleura, in direct contact with the dome of the diaphragm and attached to the mediastinum by a fine vascular pedicle which inserted in the root of the triangular ligament.

Adult↗
PubMed1984

[External genital endometriosis. Endemiologic, diagnostic, therapeutic and prognostic aspects].

189 cases were selected, representing 26 admissions per 1 000. From their analysis of the case files, the authors conclude that the development of endometriosis does not need any specific anatomical or hormonal condition and that it is difficult to determine the role of endometriosis and associated lesions in the production of symptoms. The responsibility of endometriosis in sterility has not been always, even in cases with frank lesions. The treatment is aimed at eradicating the lesions which should be followed up with laparoscopy.

Adolescent↗
PubMed1983

Deacylation and uptake of the fatty acyl chain from enantiomeric dialkylacylglycerol by intact rat fat cells.

Isolated rat fat cells hydrolyze the ester bond in position 3 of enantiomeric dialkyl[3H]acylglycerol added as triester-analogue substrate. This lipolytic system constitutes an integrated model which allows, in the absence of di- and monoesters, specific determinations of both the rate-limiting step in triacylglycerol breakdown and the uptake of acyl residues in cell lipids. Splitting of the ester bond was catalyzed by a cell-bound acylhydrolase which exhibited the characteristic properties of lipoprotein lipase. About 70% of the total amount of 3H-labelled fatty acid released during hydrolysis were concomitantly taken up by the cells and reesterified, mainly as triacylglycerol, in cell lipids. The acyl residues appeared to penetrate the cells directly after lipoprotein lipase hydrolysis, without entering the extracellular compartment. This, along with previous finding of a high positive correlation between rates of lipolytic activity and fatty acid uptake (Vérine, A., Salers, P. and Boyer, J. (1982) Am. J. Physiol. 243, E175-E181), suggests that the uptake process is directly related to enzyme action. These results are consistent with the concept that lipoprotein lipase, besides being an acylhydrolase, could also function as acyltransferase.

Adipose Tissue↗
PubMed1983

Early increase of a 105,000-dalton phosphoprotein during meiotic maturation of Xenopus laevis oocyte.

In ovo [32P] phosphoproteins were analyzed during meiotic maturation of Xenopus laevis oocytes. A phosphoprotein of 105,000-dalton was found to increase early (one hour) after progesterone induction of meiosis. The pure heat-stable inhibitor (PKI) of cAMP-dependent protein kinase, which induces maturation, was microinjected into oocytes. Again the early increase in the 105,000-dalton [32P] phosphoprotein occurred. The burst in protein phosphorylation, which takes place at the period of germinal vesicle breakdown, was quantitatively and qualitatively comparable in progesterone and PKI-stimulated oocytes. In order to confirm the inverse relationship between the 105,000 dalton [32P] phosphoprotein increase and cAMP-dependent protein kinase activity, purified C-subunit of the kinase has been microinjected into oocytes. C-subunit which inhibits maturation did not increase significantly the 105,000-dalton [32P] phosphoprotein whereas it increased the total level of in ovo phosphorylation. Enucleation experiments favour the localization of the 105,000-dalton protein in both the oocyte cytoplasm and nucleus. Furthermore the progesterone-induced increase in the phosphorylation of the 105,000-dalton protein was found in the cytoplasmic compartment after oocyte enucleation.

Animals↗
PubMed1983

On the similarity of triacylglycerol and acylcholesterol lipases in rat brain.

Previously, we described a similar stimulating effect of adrenocorticotrophic hormone (ACTH) and ACTH-related synthetic peptides on triacylglycerol (TAGL) and acylcholesterol (ACL) lipase activities of rat brain. In present study, TAGL and ACL activities from rat brain were further investigated and compared through the use of tri-[3H]oleoylglycerol and [14C]oleoylcholesterol, respectively, as the substrates. A number of specific properties proved to be similar for both activities: (a) comparable rates of activity decay were observed upon heat treatment, (b) similar reaction kinetics as determined at different substrate concentrations with and without ACTH (10(-4) M), (c) both activities showed a common susceptibility to the presence of sodium taurocholate (5 mM) or trace amounts (5 microliter/ml) of organic solvent in the assay medium, (d) the distributions of the two activities in various brain regions were comparable. Taken together, these data, along with the similar activability by ACTH, suggest a common structural basis for TAGL and ACL activities in rat brain.

Adrenocorticotropic Hormone↗
PubMed1983

Characterization of a diester lipase activity in human erythrocytes.

A diester lipase activity is described in human red blood cells (RBC). Diester lipase activity acts as a membrane-bound enzyme and is assayed using intact RBC as the enzyme source. An emulsion of di-[3H]-oleoylglycerol (0.6 mM) serves as the substrate. The optimum pH for the reaction is 7.8 at 37 degrees C. Lipolytic rates are monitored by quantitation of the amount of [3H]-oleic acid released during 20 min of incubation after a two-step purification procedure. [3H]-oleic acid is first extracted from the incubation mixture by means of a liquid-liquid partition system and further isolated by thin-layer chromatography. Suspensions of purified RBC obtained from 36 healthy adult subjects had a diester lipase activity of 196 +/- (SD) 45 mU/10(12) RBC, with no difference between men and women.

Adult↗
PubMed1983

[Monoclonal antibody typing of sub-populations of T lymphocytes in the blood and broncho-alveolar lavage (BAL) in sarcoidosis].

Cell typing of sub-populations of lymphocytes is facilitated by using monoclonal antibodies (OKT); with this technique we determined the relative proportions of "helper" T-lymphocytes (OKT4) and "Suppressor" T-lymphocytes (OKT8) in the blood and the LBA of 13 patients suffering from pulmonary sarcoidosis. In the control subjects the OKT4/OKT8 ratio was 1.9 +/- 0.3 in the blood (38 subjects) and of 2 +/- 0.2 in the LBA (6 subjects). Six patients suffering from inactive sarcoidosis (stabilised) had an OKT4/OKT8 ratio on average of 1.2 +/- 0.39 in the blood and of 1.86 +/- 0.46 in the LBA. By contrast in 7 patients suffering from "active" sarcoidosis, on average the ratio was 1.88 +/- 1.20 in the blood but 5.13 +/- 3.51 in the LBA; this ratio was notably raised in the LBA in 5 cases and was due as much to an increase in the T-"Helper" (OKT4) percentage as to a fall in the T-"Suppressor" (OKT8). It is probable that the T-"Helper" lymphocytes found in great numbers in the lung in active sarcoidosis cases participate in the formation of sarcoid granulomas and attract phagocytic mononuclear cells. This phenomenon seems to correspond to a local immune disturbance without producing a similar result in the peripheral blood of the patients.

Adult↗
PubMed1982

Effects of Cations and Abscisic Acid on Chlorophyll a Fluorescence in Guard Cells of Vicia faba.

The effects of cations and abscisic acid on chloroplast activity in guard cells of Vicia faba were investigated by analysis of the transient of chlorophyll a fluorescence. When epidermal strips containing guard cells as the only living cells were incubated in water and illuminated with strong light, chlorophyll a fluorescence rose rapidly to a high intensity and then declined slowly to a stationary level. The rate of this decline was enhanced by K(+) or Na(+), and the effect of these cations was greater when added with phosphate than with chloride as the anion. Ca(2+) suppressed the enhancement by Na(+) and, to a lesser extent, that by K(+). Abscisic acid also suppressed the enhancement by K(+) and Na(+). Since the fluorescence decline reflects the increase of intrathylakoid H(+) concentration necessary for photophosphorylation, the acceleration of the decline by K(+) (or Na(+) in the absence of Ca(2+)) implicates chloroplast activity in ion accumulation by guard cells in the light. The differential effects of phosphate and chloride suggest that chloroplast activity may be involved in malate formation in guard cells in the light.

Journal Article↗
PubMed1982

Clearance mediated by splenic macrophage membrane receptors for immune complexes in cutaneous vasculitis.

This study concerns 11 patients with immune complex associated cutaneous vasculitis (5 leukocytoclastic vasculitis or Gougerot Ruiter's disease, 3 essential mixed cryoglobulinaemia, 2 Henoch-Schönlein purpura and 1 Waldenström's hypergammaglobulinaemic purpura). By determining the clearance of 51Cr-labeled IgG sensitized erythrocytes we showed a slight modification in the splenic mononuclear phagocyte system. In patients with Gougerot-Ruiter's disease the clearance of the autologous IgG-coated erythrocytes was delayed in 1 patient, and normal in 2 patients. In contact, the 8 other patients showed accelerated rates of IgG-mediated clearance. There was no statistically significant correlation between clearance rate, serum complement component levels and composition and/or levels of circulating immune complexes. Thus, the accelerated clearance rate suggests an enhanced activity of the mononuclear phagocyte system IgG-Fc receptors.

Adolescent↗
PubMed1982

Monoester lipase activity in the red cells of patients with various blood disorders.

Membrane-bound monoester lipase (MEL) activity was measured by a radiochemical assay in intact red blood cells (RBC) from 77 patients with various blood disorders. MEL activity levels in their RBC were compared with levels in normal subjects. The increase in MEL activity was greatest in RBC of regenerative anaemias (N = 8) and blastic crisis of chronic granulocytic leukaemias (7) whereas a lesser, although significant, increase was found in acute non-lymphoblastic leukaemias (14). MEL activity was markedly decreased in RBC of erythroleukaemias (N = 5) and decreased to a lesser extent in acute lymphoblastic leukaemias (10) and in chronic myeloproliferative disorders other than chronic granulocytic leukaemias (8). MEL activity levels were roughly correlated with reticulocyte counts, but the relationship was not of predictive value in individual cases. Further exploration of the possible diagnostic or prognostic implications of these variations in enzyme levels seems warranted.

Adolescent↗
PubMed1982

Effects of apoproteins C on lipoprotein lipase activity bound to rat fat cells.

During short-term incubation, a suspension of fat cells isolated from female rats hydrolyzed tri[3H]oleyl[14C]glycerol added as substrate and incorporated an average of 42% of the amounts of [3H]oleic acid released. Lipolysis was catalyzed by cell-bound lipoprotein lipase (LPL), whose activity was influenced by apoproteins (apo) C purified from human plasma. ApoC-II enhanced 12-fold the hydrolysis rates with cells from fed rats versus 3,4-fold with cells from fasted rats. In both cases, the stimulation by apoC-II was greater than that by whole serums from led or fasted rats. Maximal LPL activity at the cell surface depended more on the preexisting nutritional state of the cell than on apoC-II or serums added extracellular. ApoC-I, apoC-III1 and apoC-III2 had no or moderate direct effects on LPL activity, whereas apoC-III1 and apoC-III2 reduced markedly the stimulating effect of apoC-II. At all levels of LPL activity, the amounts of [3H]oleic acid liberated by hydrolysis and incorporated as [3H]acylglycerol in cell lipids were highly correlated with LPL activity, suggesting that the uptake process was directly related to enzyme action.

Adipose Tissue↗
PubMed1982

Diode array digital radiography: initial clinical experience.

Initial clinical results are described for a new method of digital radiography based on high-detail self-scanning linear diode arrays which overcome many of the limitations of present film or other digital methods. The technique uses a fan-shaped x-ray beam to produce a nearly scatter-free image on a phosphor strip that is fiber-optically coupled to six self-scanning arrays of light-sensitive diodes spaced 0.025 mm, thus providing 6,144 discrete sensors across the field of view. Because these diodes have a greatly expanded dynamic range and operate at very low noise, it becomes possible to visualize small density differences or contrast below 1% both in the light and dark areas of the image. Because of the efficiency of detection and display, radiation doses can be reduced for a given information content. Our preliminary clinical studies have shown to broad application of our method in examining the chest and abdomen and in performing intravenous digital arteriography.

Angiography↗