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Biomedical subjects

R Julien

Publications and source records attributed to R Julien.

At least 91 records · Page 5Linked to original sources
PubMed1988

In situ flow cytometric analysis of nonyl acridine orange-stained mitochondria from splenocytes.

Due to its spectral characteristics, the fluorochrome nonyl acridine orange (NAO) (lambda abs:489 nm, lambda em:525 nm), which is spontaneously incorporated by mitochondria with a high relative specificity, provides a new probe for the in situ study of these organelles by flow cytometry. In 15 min at 20 degrees C, the dye at 4.75 X 10(-6) M saturates the mitochondrial binding sites present in 1.5 X 10(6) cells. Unlike Rh 123, the fixation of the probe is not affected by the action of uncouplers and ionophores. Unlike acridine orange, its binding is not sensitive to nucleases. By studying the mitochondrial incorporation of the fluorochrome during the cell cycle of murine splenocytes, it was possible to show that the biogenesis of NAO-stained mitochondrial constituents mainly occurs during the G1 phase.

Acridine Orange↗
PubMed1987

Studies on the effect of bile and lipolysis products on pancreatic lipase and colipase activity in vitro.

This study shows that human bile, at a concentration in the range of that found in the intestinal lumen, inhibited the hydrolysis of emulsified triolein by pancreatic lipase in vitro. The addition of colipase in excess to lipase failed to restore lipolytic activity. In contrast, a partially degraded emulsion of triolein containing diacylglycerol, monoacylglycerol and free fatty acid was hydrolysed by lipase and colipase in the presence of bile. The results presented in this paper allow to conclude that triacylglycerol digestive products associated with emulsified lipid played an important role in the intraluminal degradation of dietary fat by pancreatic lipase and colipase in the presence of bile.

Bile↗
PubMed1987

Establishment, identification and characterization of a new sheep sinus tumor cell line.

A cell line designated SRT was established from a sheep sinus tumor. Following primary culture, the cells were serially passaged 40 times. SRT cells maintained an epithelioid fibroblast-like appearance and had a population doubling time of approximately 18 hr. Karyotype analysis of 14th passage cells showed the modal 2n chromosome number to be between 46 to 60, due to a large variation in acrocentric chromosome number. The electrophoretic mobilities of enzymes extracted from SRT cells were identical with those from normal sheep sinus cells. It propagated a number of ovine, bovine and canine viruses. Some virus-like particles (80-120 nm) were observed under the electron microscope. The tumor origin, good growth and wide range of virus susceptibility make SRT a highly suitable cell line for in vitro cancer research and for comparative virology studies.

Animals↗
PubMed1986

Catalytic activity of a copper(II)-oxidized glutathione complex on aqueous superoxide ion dismutation.

The study of the catalytic activity of a Cu(II)-oxidized glutathione system upon the disproportionation of superoxide radicals shows that the mononuclear complex MA catalyzes dismutation in the pH range 7-9. The corresponding first-order rate constant of value kcat congruent to 6 X 10(6) M-1 sec-1 is pH independent, whereas the second-order rate constant ks for the reference solutions is pH dependent. The kcat constant is about 10-, 100-, and 300-fold higher than the ks constant at pH 7, 8, and 9, respectively. The measured effect is explained in terms of free axial sites in the square-planar arrangement around the copper ion.

Copper↗
PubMed1986

Variation of cellular mitochondrial activity in culture: analysis by flow cytometry.

Cytometric analysis of various cultured cells using fluorescent probes to stain mitochondria, in combination with other methods, has shown that mitochondrial activity is an essential part of cell cycle completion. Among the existing fluorochromes, Rhodamine 123 is most often used for analyses of growth and cellular differentiation, and the action of various compounds. These studies permit a better understanding of the role of the mitochondria in situ and especially of the interactions that occur between the cytoplasm and the nucleus. However, the development of this type of study is limited by the small number of specific fluorochromes available.

Animals↗
PubMed1985

Radioimmunoassay for 21-deoxycortisol: clinical applications.

A radioimmunoassay for 21-deoxycortisol is described. The immunogen, 21-deoxycortisol-3-(0-carboxymethyl) oxime-bovine serum albumin, was prepared, the antisera raised against it were studied and the reliability of the assay was checked. The antiserum selected cross-reacted with 11-deoxycortisol (0.08%), corticosterone (0.25%), cortisol (0.6%) and 17-hydroxyprogesterone (1.6%). 21-deoxycortisol was separated by celite partition chromatography and eluted in the 70/30 (v/v) isooctane/ethyl acetate fraction together with 11-deoxycortisol and corticosterone. The radioimmunoassay was used to measure 21-deoxycortisol in the plasma of normal subjects and patients with androgen excess. In normal subjects, men (0.19 ng/ml +/- 0.08) and women (0.18 ng/ml +/- 0.09) had similar basal levels (mean +/- SD). One hour after ACTH stimulation, these levels were increased by a factor of 3.5. In 7 patients treated for classical congenital adrenal hyperplasia associated with 21-hydroxylase deficiency, basal values varied between 9.1 and 39.9 ng/ml (measured at 8 a.m.). In 7 untreated women with late-onset congenital adrenal hyperplasia (with 21-hydroxylase deficiency), ACTH-stimulated levels were increased to between 9 and 25.5 ng/ml. In 14 heterozygous carriers of 21-hydroxylase deficiency, diagnosed by HLA genotyping, all ACTH-stimulated levels were well above the highest corresponding levels in normal subjects, whereas 17-hydroxyprogesterone levels remained within the normal range in 9 of the cases.

17-Hydroxycorticosteroids↗
PubMed1984

Inhibition of pancreatic and microbial lipases by proteins.

We have compared the effect of several proteins, including melittin, beta-lactoglobulin A, serum albumin, ovalbumin and myoglobin, on the hydrolysis of tributyrin and triolein by lipases from various origins. All proteins tested inactivate pancreatic lipase in absence of colipase and bile salt. Inhibition is not significantly reversed by colipase in absence of bile salt except in systems containing tributyrin and melittin or triolein and beta-lactoglobulin A. In all other cases, activation of pancreatic lipase by colipase in presence of inhibitory protein requires the presence of bile salt. Lipase from Rhizopus delemar is also inhibited by the proteins that inactivate pancreatic lipase. In contrast, the activity of lipase from Rhizopus arrhizus is not affected by the proteins in the same concentration range. Inhibition of lipase activity by amphiphiles such as proteins or detergents appears to be a general phenomenon not directly related to a decrease in tension at the triacylglycerol-water interface. Inhibition could be the result of desorption of lipase from its substrate due to a change in interfacial quality.

Animals↗
PubMed1984

[Cushing's syndrome: a diagnostic strategy].

Biologic and radiologic investigations in the diagnosis of Cushing syndrome are evaluated. A two-step diagnostic procedure is propounded. The combination of absence of overnight suppression of plasma cortisol by dexamethasone and elevation of urinary free cortisol and midnight plasma cortisol levels establishes the diagnosis of Cushing syndrome in most patients. The next step is to determine the precise cause of Cushing syndrome by baseline plasma ACTH assays, the high-dose dexamethasone test and the visualization of the adrenals by iodocholesterol scintigraphy and/or computed tomography.

17-Hydroxycorticosteroids↗
PubMed1984

Studies on the inhibition of pancreatic and microbial lipases by soybean proteins.

A protein, molecular weight 70,000 that inhibits pancreatic lipase has been isolated from soybean seeds. Inhibition is not reversed by colipase unless bile salts are added to the assay system. Inhibitory properties of the purified protein are very similar to those of serum albumin or alpha-lactoglobulin. It has been confirmed that, during intestinal lipolysis of dietary fats, bile salts play an essential role for the activation of the lipase-colipase system in the presence of inhibitory proteins. The purified soybean lipase inhibitory protein was shown to be highly surface-active and able to penetrate monomolecular films of various glycerides and phospholipids at high surface pressure. Inhibition of pancreatic lipase by proteins is related to their capacity to interact with lipids and to modify the quality of the substrate-water interface. The protein isolated from soybeans inhibits pancreatic and Rh. delemar lipase in contrast to the Rh. arrhizus enzyme.

Amino Acids↗
PubMed1983

Glutamyl-tRNA synthetases from wheat. Isolation and characterization of three dimeric enzymes.

Three dimeric glutamyl-tRNA synthetases (GluRS) were isolated from extracts of quiescent wheat germ and wheat chloroplasts. The chloroplast enzyme (Mr = 110 000), called GluRS C, exhibits a prokaryotic (Escherichia coli) tRNA specificity. Two enzymes were found in the quiescent germ and were separated on phosphocellulose P11: one called GluRS P, probably the mitochondrial enzyme, has the same tRNA specificity as GluRS C; the other, called GluRS E, has eukaryotic (wheat germ) tRNA specificity. Both enzymes exhibit a molecular weight close to 160 000. Each of these enzymes co-eluate on hydroxyapatite and phosphocellulose chromatographies with an unstable active monomer whose molecular weight is approximately half that of the corresponding dimer. Two assumptions are discussed about these monomers.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Dimeric glutamyl-tRNA synthetases from wheat. Kinetic properties and functional structures.

The Michaelis constants in the tRNA aminoacylation reaction have been studied for the three dimeric glutamyl-tRNA synthetases C, P and E. The values were found to be: for tRNA, 0.20 microM, and 0.44 microM; for glutamic acid, 10 microM, 83 microM and 83 microM; for MgATP, 0.46 mM, 0.38 mM and 0.26 mM. MgATP concentrations higher than 2 mM induce pronounced inhibition. The presence of the cognate tRNA is required for [32P]PPi-ATP isotopic exchange. In the absence of tRNA no hyperbolic saturation of the enzymes by glutamic acid occurs in our experimental conditions. Analysis of the enzymic activity as a function of enzyme concentration leads to the conclusion that the active forms are dimers which are in equilibrium with inactive monomers. The values of the dissociation constants Kd were found to be 43 nM, 53 nM and 87 nM for glutamyl-tRNA synthetases C, P and E respectively.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Evidence for adrenal and/or ovarian dysfunction as a possible etiology of idiopathic hirsutism.

Thirty-one cases of idiopathic hirsutism, characterized biochemically in the basal state by increased levels of urinary 3 alpha-androstane-5 alpha, 17 beta-diol and normal levels of the main androgens, were studied. In order to determine a possible etiologic heterogeneity of idiopathic hirsutism, pituitary gonadotropin responses to synthetic luteinizing-releasing hormone (LRH) and adrenal steroid responses to adrenocorticotropic hormone (ACTH) stimulation were evaluated and the results were compared to those in six normal women. On the basis of the results obtained in each hirsute patient after LRH and ACTH tests, two groups were identified. The majority, 23 of 31 hirsute patients (group I), had results similar to those in the control group. In the other eight patients (group II), biologic abnormalities were disclosed and suggested a partial adrenal 11 beta-hydroxylase defect in two patients, an incomplete form of adrenal 3 beta-ol deficiency in one patient, an adrenal hyperreactivity without evident cause in two patients, and polycystic ovary syndrome in association with an adrenal hyperreactivity in three patients. As a group, the eight patients showed ACTH-stimulated increments in testosterone, delta 4-androstenedione, dehydroepiandrosterone, and 17-ketosteroids that were significantly greater (p less than 0.01) than the mean responses in the control group. The conclusion is that some women who previously were designated as having "idiopathic" hirsutism had an adrenal and/or ovarian component to their hyperandrogenism which could be shown only by appropriate dynamic tests.

17-Ketosteroids↗
PubMed1983

Studies on the detergent inhibition of pancreatic lipase activity.

Pancreatic lipase requires colipase, a protein cofactor, to counteract the in vitro inhibition by bile salt. Lipase activity is inhibited by nonsteroidic detergents regardless of their charge and structure. Detergent-inhibited lipase is reactivated by colipase but in all cases activation is limited to a narrow range of detergent concentration. Complementary studies on the bile salt and detergent effect on lipase activity and on interfacial tension at the substrate-water interface show that inhibition is not related to the interfacial surface tension. It is hypothesized that absorption of amphiphilic compounds to the substrate surface modifies the distribution of the enzyme between the lipid surface and the aqueous phase. The activity of detergent-inhibited lipase is fully restored by adding bile salt to the reaction system. Bile salt might play a critical role during in vivo lipolysis by desorbing surface-active substances from the lipid-water interface thus allowing lipase and colipase to interact with substrate.

Animals↗
PubMed1981

Isolation and partial structural characterization of chicken pancreatic colipase.

Colipase has been isolated from acidic extracts of chicken pancreatic tissue homogenized with Triton X-100. The cofactor fully activates bile salt inhibited mammalian lipases. The amino terminal sequence of the avian protein has been determined up to position 39 and compared to the homologous region of the mammalian colipases (pig, horse, man) previously studied. From this comparison, it appears that a high degree of homology exists between the proteins.

Amino Acid Sequence↗