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Biomedical subjects

J Duval

Publications and source records attributed to J Duval.

At least 163 records · Page 9Linked to original sources

[Encapsulation of GnRH in liposomes: effects on the release of hypophyseal LH].

The GnRH has been entrapped in liposomes. The infusion of this trapped GnRH in a pituitary superfusion system allows us to show that it mimics only the phase II of the GnRH stimulated LH release. We show that cycloheximide seems to interact at the level of the natural GnRH penetration mechanism in the cytoplasm. One of the places where calcium is suspected to be potent has been located at the expression level of the message transmitted to the cytoplasm by the trapped GnRH.

Animals↗

[Bacterial septicemia in neutropenia patients].

Two hundred bacterial septicemia occurring in neutropenic patients (PMN less than 1,000 microliter) were analyzed. Most of these patients had hematologic malignancies. The underlying disease, the degree of neutropenia the association of septic focus with the bacteremia, the responsive microorganisms and their evolution during hospitalization were studied as prognosis factors. The overall mortality was 32.5 p. 100. The mortality was higher in patients whose granulocyte count was lower than 500 microliter. The occurrence of major septic focus (pulmonary, perineal infection, diarrhea with abdominal distension, ORL, or cutaneous extensive focus) during bacteremia was a highly significant factor of bad prognosis. The mortality of bacteremias with and without major septic focus was respectively 62 p. 100 and 15 p. 100. A study of the distribution of the bacterias was performed in terms of mortality and duration of hospitalization. "Escherichia coli" and gram positive cocci were predominant during the two first days and mortality was then low. After that time, others Gram-negative bacterias appeared, especially "Pseudomonas aeruginosa" and the mortality was increasing until the twentieth day. Therefore, the authors raise the opportunity of antibiotic therapy according to the duration between the beginning of the hospitalization and the occurrence of sepsis in neutropenic patients. The role of the extensive use of a curative antibiotic association using colistine and nalidixic acid between 1974 and 1976 is discussed in the emergence of more gram positive cocci bacteremias between 1976 and 1978 than between 1974 and 1976 in the same intensive care unit.

Agranulocytosis↗

[In vitro antibacterial activity of dibekacin on staphylococci, streptococci and aerobic Gram negative bacilli].

Dibekacin is a new aminoglycoside derived semi-synthetically from kanamycin B. Its in vitro antibacterial activity, evaluated by the study of 43 reference strains and 1,177 clinical isolates, was found to be very similar to that of gentamicin, tobramycin, sisomicin and netilmicin on strains sensitive to these aminoglycosides; in the case of strains carrying plasmidic resistance factors, dibekacin behaves like tobramycin; it is inactivated by the same bacterial enzymes.

Aminoglycosides↗

[Antibacterial spectrum of mezlocillin and MIC/disc correlations (author's transl)].

Mezlocillin is a semi-synthetic antibiotic belonging to the ureidopenicillin group. A study of its activity against a wide range of organisms shows that it is a broad-spectrum antibiotic. However, mezlocillin differs from aminopenicillins and carbenicillin by its activity against numerous strains of klebsiella spp. (modal MIC 4 micrograms/ml). It is also slightly more active than carbenicillin against Pseudomonas spp. (modal MIC 16 micrograms/ml). The regression line relating MICs and disc zone diameters was calculated by the least square method. The correlation coefficient was 0.85.

Acinetobacter↗

[Human pharmacology of ceftriaxone (author's transl)].

The human pharmacology of ceftriaxone was studied in five healthy adult subjects receiving a 500 mg dose intravenously. Evolution of serum levels represents a two compartment open model; the distribution volumes, central and peripheric, were low (about 3 L); the elimination half-life was particularly long : 7.87 hours; the renal and serum clearances and low. These data are probably related to the high affinity of the drug for serum proteins (95 p. cent bound); they suggest once daily parenteral dosing.

Adult↗

Changes in cAMP metabolism during phagocytosis of S. aureus by human monocytes.

Involvement of cyclic adenosine 3',5'-mono-phosphate (cAMP) in the phagocytosis of staphylococci by human monocytes was demonstrated by assay of adenylate cyclase and cAMP phosphodiesterase (PDE). Monocyte adenylate cyclase and PDE activities were assayed on cell homogenates prepared from monocytes isolated by plate adherence. Phagocytosis of staphylococci was associated with diminished adenylate cyclase activity, which reached a minimum after 10 min of incubation (p less than 0.05), and an increase in PDE activity (p less than 0.005). Transmission electron microscopy provided evidence that these changes coincide with peak phagocytic activity occurring between 10 and 20 min after the start of phagocytosis but could not be assigned to a particular stage in the phagocytic process.

3',5'-Cyclic-AMP Phosphodiesterases↗

[In vitro antibacterial activity of eight third generation cephalosporins (author's transl)].

This work report a study of antibacterial activity of eight third generation cephalosporins : cefotaxime, moxalactam, cefoperazone, cefotiam, ceftazidime, ceftriaxone, cefmenoxime and cefotetan. The essential interest of these antibiotics is their activity against Enterobacteriaceae resistant to cefalothin ; however, five of them are clearly superior ; cefotaxime, moxalactam, cefmenoxime, ceftriaxone and ceftazidime. Ceftazidime is the best against Pseudomonas aeruginosa and moxalactam against the Bacteroides group. Against others bacterial groups, these new cephalosporins are not superior to former products.

Acinetobacter↗

[Evolution of bacteria in hospital (author's transl)].

This study reports the evolution of bacterial ecology during twelve years in a general hospital : prevalence of the different species isolated and their resistance to antibiotics. It appears, in the etiology of serious infections, a great stability in the repartition of bacterial groups responsible. Likewise, the evolution of bacterial resistance during this period did not show a gradual increase. A certain balance seems to occur in function of local conditions, among which a controlled use of antibiotics is certainly an important factor.

Adult↗

[Preparation of specific pituitary cells by centrifugal elutriation].

The cells of the male rat pituitary were enzymatically dispersed with trypsin and then separated by centrifugal elutriation. The commercial equipment requires minor modifications, especially the infection system. Using a gradient of flow, enriched gonadotrop cells are obtained. The results compare favourably with those obtained by sedimentation at unit gravity.

Animals↗

[In vitro activity of cefotaxime on anaerobes (author's transl)].

The comparative activity of cefotaxime, cefazolin, cefamandole and cefoxitin was studied on 80 strains of anaerobic bacterial species: 14 Clostridia, 60 Bacteroides fragilis, 6 Peptococcus. The new cephalosporins showed an increase in the in vitro activity against Bacteroides fragilis, but their efficacy was still inferior to that of the 5-nitro-imidazole derivatives.

Anaerobiosis↗

Gonadotrophin release by gonadotrophs incubated with gonadotrophin-releasing hormone is independent of intracellular cAMP accumulation.

Rat pituitary cells were dispersed with trypsin and separated by sedimentation at unit gravity. The distributions of prolactin (Prl), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were determined, and two enriched cell populations (mammotrophs and gonadotrophs) were subsequently cultured. During a 4 h incubation, gonadotrophin-releasing hormone (GnRH) stimulated the release of LH and of FSH by both the unfractionated population and the enriched gonadotrophs; the magnitude of this stimulation increased with the length of the pre-culture periods, and the amount of LH released into the medium correlated strongly with the amount of FSH, whatever the length of the pre-culture period. The cellular cAMP content was also enhanced during the 4 h incubation, but no correlation was found between the hormone release and the cAMP accumulation. Furthermore, during the first 30 min of incubation with GnRH there was no increase of cellular cAMP, whatever cell population used. We conclude that the gonadotrophin release was independent of the cAMP accumulation observed in pituitary cells several hours after stimulation by GnRH; consequently, the late increase in the nucleotide is suggested to be a non-specific secondary process.

Animals↗

[Dexamethasone regulation of the prolactin release induced by vasoactive intestinal peptide (VIP)].

The regulation of prolactin (PRL) secretion induced by the vasoactive intestinal peptide (VIP) has been studied on purified male Rat Pituitary PRL cells obtained by means of velocity sedimentation at unit gravity. Dexamethasone (10(-9) M) in the incubation medium inhibits the stimulatory effect of VIP (10(-7) M) on PRL release. This result suggests that glucocorticoids play an important role in the regulation of VIP effects at the effects at the pituitary level.

Animals↗

[Metabolism of guanine in the adenohypophysis of the male rat during growth and after castration].

During incubation of the male Rat pituitary, guanine is metabolized according to two ways: the first one leads to the guanylic nucleotides subsequently incorporated into the RNA; the second one produces xanthine and uric acid. If guanosine is used as a precursor, the nucleoside is converted into guanine before utilisation thus suggesting a low level of guanosine kinase activity. The production of xanthine is higher in adult animals than in immature ones and it is increased following gonadectomy. It follows that the pituitary guanine deaminase could be considered as an enzyme regulated by sexual hormones.

Aging↗

Effect of vasoactive intestinal peptide (VIP) on the release of adenohypophyseal hormones from purified cells obtained by unit gravity sedimentation. Inhibition by dexamethasone of vip-induced prolactin release.

The effect of vasoactive intestinal peptide (VIP) on the release of prolactin (PRL), gonadotropins (LH and FSH), growth hormone (GH) and corticotropin (ACTH) was studied using purified rat anterior pituitary cells obtained by means of velocity sedimentation at unit gravity. VIP, at concentrations ranging from 10(-10) to 10(-7) M, stimulated PRL secretion in a dose-dependent manner with an ED50 of 2 nM and a maximal response of 530% of control values. In contrast, similar concentrations of VIP did not affect the release of either LH, FSH, GH or ACTH from the corresponding enriched cell populations. Addition of dexamethasone (10(-9) M) to both preincubation and incubation medium of PRL cells completely inhibited VIP-induced PRL release. The present results further support the hypothesis that VIP is of physiological importance in the control of PRL secretion and demonstrate that corticosteroids can modify the responsiveness of PRL cells to VIP.

Animals↗

Erythromycin pharmacokinetics in man.

This study shows that high serum concentrations are reached after either ethylsuccinate or lactobionate erythromycin administration. But the short elimination half-life implies repetitive administration to obtain efficacy, the ideal being represented by continuous infusion.

Administration, Oral↗