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C Antoine

Publications and source records attributed to C Antoine.

At least 37 records · Page 2Linked to original sources
PubMed1995

Nature and bioactivity of gonadotropin-releasing hormone (GnRH) secreted during the GnRH surge.

Previous studies have demonstrated a neural action of estradiol in inducing a surge of GnRH in the ewe. However, although the GnRH and LH surges began concurrently, the GnRH surge consistently continued well beyond the surge of LH. Three experiments were conducted to test the hypothesis that the termination of the LH surge results from the secretion of a relatively inactive variant of GnRH during the later phases of the GnRH surge. In the first experiment, hypophyseal portal blood collected during an estrogen-induced LH surge was analyzed for GnRH immunoreactivity using two antibodies having specificity for the N- or C-terminal portion of the GnRH molecule. The duration, amplitude, and time course of the GnRH surge were found to be similar irrespective of the antisera used. In a second experiment, a competitive GnRH antagonist was administered at the beginning of the estrogen-induced GnRH/LH surge at a dose capable of blocking pituitary responsiveness for approximately half the duration of the GnRH surge. Antagonist treatment did not result in any change in the time of onset of the GnRH surge, but there was no increase in LH that naturally occurs coincident with onset of the GnRH surge. Rather, a persistent increase in LH secretion was observed during the latter stages of the GnRH surge, indicating that the GnRH molecules secreted at this time were biologically active. Finally, a sensitive and specific ovine pituitary cell bioassay was used to test bioactivity of GnRH in hypophyseal portal blood during different phases of the GnRH surge. GnRH bioactivity in samples collected early in the GnRH surge was greater than that before the onset of the GnRH surge but no greater than that collected during the descending limb of the surge. The results of all three experiments fail to support the hypothesis that the LH surge ends because of a change in the nature of the GnRH secreted. Rather they show that GnRH secreted throughout the surge is biologically active. Thus, the termination of the LH surge before that of the GnRH surge occurs for reasons other than lack of a bioactive GnRH signal.

Animals↗
PubMed1995

[Comparative study of four commercialized serologic methods for the diagnosis of gastric Helicobacter pylori infection].

OBJECTIVE: Four commercially available enzyme-linked immunosorbent assays (ELISA) were evaluated for serological diagnosis of Helicobacter pylori (H. pylori) infection in 79 untreated patients. METHODS: Infection has been diagnosed in 40 patients, in whom culture and/or urease test and histopathology from antral biopsies, were positive for H. pylori. RESULTS: Sensitivity (Se) and specificity (Sp) of these tests, calculated with indeterminate serological results (9 patients) classified as positive (ind +) or negative (ind -), were not statistically different: GAP-test (Bio-Rad), Se = 95% (ind +), 90% (ind -), Sp = 84.6% (ind +), 89.7% (ind -); Pylori-Stat (Biowhittaker), Se = 97.5% (ind + or -), Sp = 71.8% (ind +), 71.9% (ind -); Premier H. pylori (Biomedical Diagnostics), Se = 92.5% (ind +), 90% (ind -), Sp = 84.6% (ind +), 81.2% (ind -); Cobas-Core (Roche), Se = 92.5% (ind + or -), Sp = 76.9% (ind +), 79.5% (ind -). There was a strong correlation between mucosal inflammation and H. pylori status. Discrepancies between infectious status and at least one serology result were observed in 16 patients (11 H. pylori negative and 5 H. pylori positive patients). CONCLUSION: These 4 tests are of equivalent diagnostic value. Thus, the selection of one of them should take into account cost and practicability.

Adolescent↗
PubMed1992

Time-dependent utilization of platelet arachidonic acid by the neutrophil in formation of 5-lipoxygenase products in platelet-neutrophil co-incubations.

The biosynthesis of leukotrienes is known to occur through a series of complex processes which, in part, can be influenced by cell-cell interactions. Several studies have suggested that arachidonic acid availability is a major limiting step for leukotriene biosynthesis and that its transfer between cells can represent a significant source of this precursor. Accordingly, effect of time and source of arachidonic acid on transcellular leukotriene synthesis was studied in mixed platelet/neutrophil populations challenged with the calcium ionophore A23187. A time-dependent contribution of platelet-derived as well as neutrophil-derived arachidonate was found in the selective formation of neutrophil 5-lipoxygenase metabolites. Utilization of platelet or neutrophil arachidonate was followed by incorporation of radiolabeled arachidonic acid into platelet or neutrophil phospholipids prior to stimulation. Specific activity of liberated arachidonic acid along with numerous 5-lipoxygenase products (including LTB4, 20-hydroxy-LTB4, 5-HETE and LTC4) was determined in order to follow mass and radiolabel. A large amount of platelet-derived arachidonic acid was released in the first 1.5 min, whereas 10 min platelet-derived arachidonate was much lower in amount but significantly higher in specific activity, suggesting different precursor pools. The platelet-derived arachidonate was heavily utilized by the neutrophils at the early time points for formation of 5-HETE and delta 6-trans-LTB4 isomers, but appeared to contribute only marginally to the constitutive metabolism of neutrophil arachidonate into LTB4. Results from these experiments suggest different pools of 5-lipoxygenase in the neutrophil and indicate a time and source dependent modulation of arachidonate metabolism in mixed cell interactions.

Arachidonate 5-Lipoxygenase↗
PubMed1992

Entry rate and metabolism of leukotriene C4 into vascular compartment in healthy subjects.

We measured the excretion of a major urinary metabolite of leukotriene (LT) C4, i.e., LTE4, during the infusion of exogenous LTC4 to enable estimation of the rate of entry of endogenous LTC4 into the bloodstream. Four healthy volunteers received 2-h intravenous infusions of vehicle alone and LTC4 at 0.063, 0.32, 1.6, and 2.9 pmol.kg-1.min-1 in random order. Urinary LTE4 was measured before, during, and up to 24 h after the infusions. The fractional elimination of LTE4 was independent of the rate of LTC4 infusion and averaged 4.3 +/- 0.9%. Calculation of the mean rate of entry of LTC4 into the circulation was found to be 0.06 pmol.kg-1.min-1. In addition, we characterized further metabolism of [14C]LTC4. The two major urinary metabolites were the omega- and beta-oxidation products (16-COOH-LTE4 and 14-COOH-LTE3), which accounted for 6-8% of the total infused amount of [14C]LTC4. We conclude that 1) LTC4 is produced at a low rate under physiological circumstances and is rapidly converted in the vasculature to LTE4, 2) changes in the urinary excretion of the latter may reliably reflect short-term changes in the rate of secretion of LTC4, and 3) measurement of the omega- and beta-oxidation products may reflect chronic changes in cysteinyl leukotriene biosynthesis.

Adult↗
PubMed1991

Development of enzyme immunoassays for leukotrienes using acetylcholinesterase.

We have developed sensitive solid phase enzyme immunoassays (EIA) to analyze quantitatively leukotrienes (LTs) using acetylcholinesterase from Electrophorus electricus as a label for LTB4, LTC4 and LTE4. However, because of problems specific to LTs, we used different coupling procedures to prepare LTs conjugates necessary for the production of antibodies and for the preparation of enzymatic tracers. For the immunogens, all LTs were coupled to bovine serum albumin using glutaraldehyde (ethylene diamine was used to add an amino group to LTB4). Immunizations in rabbits were done following classical procedures. For the enzymatic tracers, succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate was selected to conjugate the LTs via their amino groups to acetylcholinesterase. Titers of the different antisera ranged from 1:30,000 (LTE4), 1:40,000 (LTC4) to 1:50,000 (LTB4) and sensitivities (IC50) were 5.5 pg, 4.3 pg and 2.4 pg, respectively. Cross reactivities were also examined against other LTs. Sensitivities and specificities of the different systems were dependent on the conditions of incubation (temperature). Validation of the technique was done (i) after spiking known amounts of LTC4 in plasma and measuring the substance added after prior extraction and purification, (ii) by analyzing the supernatant of human neutrophils suspended in buffer or in plasma, (iii) by measuring LTE4 in urine. Due to the background provided by these complex matrixes, quantitation was performed after addition of [3H]LTs for recovery, protein precipitation, extraction by Sep-PakR and purification by HPLC. Measurement of LTs can be done in biological fluids with the same ease and advantages as other enzyme immunoassays that we have previously developed for eicosanoids analysis.

Acetylcholinesterase↗
PubMed1991

Pathology and human immunodeficiency virus expression in placentas of seropositive women.

The pathology of term placentas from seropositive human immunodeficiency virus (HIV)-infected and seronegative women was investigated by routine histologic, immunocytochemical, and in situ hybridization techniques. Placentas were evaluated for evidence of villitis, chorioamnionitis, and funisitis. Membranes, trophoblast, and decidua were also examined by immunohistochemistry using monoclonal HIV p24 antibody. Twenty placentas were evaluated by combined immunochemical and in situ hybridization techniques, using a 35S-labeled RNA probe complementary to the 3' long terminal repeat and envelope region of HIV-1. HIV-seropositive placentas did not show significant villitis; however, the incidence of chorioamnionitis increased (P less than .01). HIV antigens and nucleic acids were identified in the trophoblast of 10% of the placentas that also showed chorionitis. Term HIV-positive placentas may show histologic changes that may or may not be directly related to the virus. Analysis of tissues from earlier gestational placentas may prove more informative in clarifying the mechanism of maternal-fetal HIV transmission.

Chorion↗
PubMed1991

Normal expression of the adhesive structure Mo-1 on monocytes from patients with Glanzmann's thrombasthenia.

The glycoprotein complex GPIIb-IIIa of the platelet membrane and CD18 of the monocyte membrane have been established as being the central figure for the adhesion processes of the corresponding cells. The molecular structure of these 2 GPs bears some similarities. It was proposed recently that LFA-1 and Mo-1 (CD18 family) and GPIIb-IIIa might be encoded by the same gene. For this purpose, we studied the expression of Mo-1, Mo-2 (as control) receptors on monocytes and GPIIIa and GPIIb-IIIa on platelets of two GT patients as compared to normal healthy subjects. Monoclonal antibodies anti Mo-1, MO-2, AP-3 and AP-2 were used to measure the expression of the respective antigens by indirect immunofluorescence procedure. The fluorescence of the labelled cells was analysed with an Ortho Cytofluorograph 50-H. The resulting Mean Fluorescence Intensity (MFI) values of AP-2 and AP-3 showed that the patients had a total absence of GPIIb-IIIa antigens. However, Mo-1, as well as those of control Mo-2, in patients (MO-1: 672 and 716; Mo-2: 453 and 637) were similar to that of normal subjects (Mo-1: 735 +/- 74; Mo-2: 585 +/- 35; mean +/- SEM). Therefore, the normal expression of Mo-1 receptors on the monocytes of Glanzmann's thrombasthenia patients suggests different genomic regulations for Mo-1 antigens on the monocyte and GPIIb-IIIa complex on the platelet.

Cell Adhesion Molecules↗
PubMed1989

[Eye manifestations of Horton's disease].

Ocular complications occurring in temporal arteritis are of different severities. These manifestations of the disease occurred in a population of 57 patients with diagnosis of temporal arteritis, in 16 of them (28%). The diagnosis was suggested by finding an inflammatory syndrome (high erythrocyte sedimentation rate) and confirmed by temporal artery biopsy. In making this diagnosis, it was helpful to find a history of characteristic temporal headaches, neckache, jaw claudication, fever and malaise or weight loss in addition to polymyalgia and polyarthralgia. 6 patients presented with diplopia and different ocular muscle or nerve palsies. The 10 others came for sudden loss of vision due to ischemic anterior or posterior neuropathy and in one case, central artery obliteration. Prompt treatment with steroids gave good results on oculomotor troubles and in preventing the risk of involvement of the fellow eye. But loss of vision did not regress with this treatment. That means the importance in making this diagnosis and starting very promptly this treatment.

Blepharoptosis↗
PubMed1988

Pregnancy post-Stevens-Johnson syndrome: case report and review of the literature.

A pregnancy complicated by vaginal stenosis six years after diagnosis of Stevens-Johnson syndrome is described. The pathologic changes in the vagina have not previously been reported. The basic pathology of severe mucosal erythema multiforme was present, as well as ectasia of the superficial capillaries and small venules. The effect of the vaginal scars on the mode of delivery is discussed.

Adult↗