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Biomedical subjects

P Leclerc

Publications and source records attributed to P Leclerc.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Foreign body granuloma mimicking bronchial tumor. Aspects in x-ray computed tomography with views by virtual endoscopy].

The aim of this study is to report the spiral CT findings of an endobronchial foreign body (chicken's bone) unknown on the postero-anterior chest radiograph and on the first bronchoscopy. The double originality of this case is the association with endobronchial actinomycosis mimicking a bronchial neoplasm and the utilization of virtual endoscopy by endoluminal 3D reconstruction in this context which has never been reported. The endoluminal 3D reconstruction of the bronchial tree could help guide the endoscopic procedure by better localization of the lesions.

Bronchi↗
PubMed1996

Phosphorylation of Triton X-100 soluble and insoluble protein substrates in a demembranated/reactivated human sperm model.

Sperm motility is a process which involves a cascade of events mediated by cAMP and Ca2+, cAMP in the initiation of flagellar movement, and Ca2+ in the regulation of beat asymmetry, and it has been suggested that these two messengers act through phosphorylation/ dephosphorylation of axonemal proteins. Only a few studies on human sperm protein phosphorylation have been reported and no relation of this process with motility or other function has been established. In the present study, phosphorylation of human sperm proteins was performed using detergent-demembranated spermatozoa, in which motility is reactivated by the addition of ATP. This system allows direct accessibility of intracellular kinases to [32P] gamma ATP and allows some relation between protein phosphorylation and flagellar movements. After electrophoresis and autoradiography, numerous phosphoproteins were detected. Phosphorylation of 2 proteins (36 and 51 kDa) was stimulated by cAMP in a concentration-dependent manner, and this increase was prevented by inhibitors of cAMP-dependent protein kinase. In order to characterize phosphoproteins originating from the cytoskeleton or axoneme, detergent extracted spermatozoa were also subjected to phosphorylation. Three major phosphorylated proteins (14.8, 15.3, and 16.2 kDa) were detected, the first two expressing cAMP-dependency according to their cAMP concentration-dependent increase in phosphorylation and the reversal of this effect by inhibitors of cAMP-dependent protein kinase. Proteins phosphorylation during the reactivation of demembranated spermatozoa previously immobilized H2O2, xanthine + xanthine oxidase-generated reactive oxygen species, or the oxidative phosphorylation uncoupler rotenone, revealed increases in cAMP-independent phosphorylation of proteins of 16.2, 46, and 93 kDa. These results documenting human sperm phosphoproteins form a base for further studies on the role of protein phosphorylation in sperm functions.

Cyclic AMP-Dependent Protein Kinases↗
PubMed1996

Cyclic adenosine 3',5'monophosphate-dependent regulation of protein tyrosine phosphorylation in relation to human sperm capacitation and motility.

The involvement of cAMP in the process of sperm capacitation has been the subject of several studies. In addition, the importance of protein-tyrosine phosphorylation in this process has been investigated, although only a few studies have been reported in the human. Since agents regulating the intracellular concentrations of cAMP affect sperm capacitation rates, the role of cAMP on the expression of phosphotyrosine-containing proteins was investigated during human sperm capacitation. Fetal cord serum ultrafiltrate, a known capacitation inducer in human spermatozoa, caused an increase in the phosphotyrosine content of 105- and 81-kDa proteins (p105 and p81), the two major phosphotyrosine-containing proteins of human spermatozoa. Similar effects were observed when spermatozoa were incubated with phosphodiesterase inhibitors or cell-permeant cAMP analogs, suggesting that cAMP is involved in these two processes. Forskolin, an adenylyl cyclase activator, also caused an increase in both sperm capacitation rates and tyrosine phosphorylation of p105 and p81, while 12-O-tetradecanoyl phorbol 13-acetate stimulated both capacitation and tyrosine phosphorylation of p105 and p81 only when spermatozoa were incubated in the presence of bicarbonate, in agreement with its reported effects on cAMP production and hamster sperm capacitation. The inhibition of these phenomena by cAMP-dependent protein kinase inhibitors, and the stimulation by protein phosphatase inhibitors, suggest that Ser/Thr protein phosphorylation plays an important role in the regulation of both sperm capacitation and protein-tyrosine phosphorylation pathways. However, observations that both calyculin A and okadaic acid stimulated sperm capacitation, whereas only calyculin A increased p105 and p81 phosphotyrosine content and sperm velocity, suggest that protein phosphatase PP1 is involved in the two latter phenomena while PP2A mediates sperm capacitation. These results suggest that divergent pathways might regulate tyrosine phosphorylation of p105 and p81 and sperm capacitation after cAMP-dependent phosphorylation of an intermediate protein.

Adenylyl Cyclases↗
PubMed1995

HIV infection among women undergoing abortion in Montreal.

OBJECTIVE: To determine the seroprevalence and correlates of HIV infection in a subpopulation of women of childbearing age in Montreal. DESIGN: Anonymous unlinked seroprevalence study. SETTING: Pregnancy termination unit in a teaching hospital in Montreal. PARTICIPANTS: Women presenting for abortion from July 1989 to June 1993 who resided in Quebec and were not known to have HIV infection; 12,017 (99.6%) of 12,068 eligible women were included in the study. INTERVENTION: HIV antibody testing of serum left over from samples obtained for routine Rh typing; the same algorithm as for serodiagnostic testing, namely enzyme immunoassay (EIA) followed by confirmatory testing of repeatedly EIA-reactive samples, was used. OUTCOME MEASURES: HIV serostatus by age, marital status, region of residence (metropolitan Montreal versus other), country of birth and number of living children. RESULTS: Most (84.7%) of the subjects resided in metropolitan Montreal. The median age was 27.0 (range 13 to 50) years. The serum samples of 22 women were confirmed to be HIV positive, for an overall seroprevalence rate of 1.8 per 1000 (95% confidence interval 1.1 to 2.8). The seroprevalence rate did not vary significantly by age, marital status, region of residence or study year. However, it was strongly correlated with country of birth: Canada 0.16, Haiti 23.5, HIV-endemic countries other than Haiti 5.3 and non-HIV-endemic countries other than Canada 0.0 per 1000. The seroprevalence rate among women born in Haiti was 147 times higher than that among women born in Canada (p < 0.0001). Of the women born in Haiti the rate was 3.0 times greater among those who immigrated to Canada in 1985 or later than among those who immigrated earlier (p = 0.047). CONCLUSIONS: The results of this study indicate that the HIV seroprevalence rate among women in Montreal is strongly associated with country of birth, women born in HIV-endemic countries, especially Haiti, having the highest rate. These results will help in the development of policies regarding HIV antibody testing and prevention of HIV transmission in Quebec.

Abortion, Legal↗
PubMed1995

Mouse sperm adenylyl cyclase: general properties and regulation by the zona pellucida.

It has been shown that the cAMP concentrations in capacitated mouse sperm can be increased in response to the egg's extracellular matrix, the zona pellucida (ZP), during the acrosome reaction. However, it is not known whether this cAMP elevation is caused by a stimulation of adenylyl cyclase (AC) activity or a decrease in cyclic nucleotide phosphodiesterase activity. In the present study using capacitated mouse spermatozoa, 20% and 30% of the total AC activity in the presence of Mg2+ and Mn2+, respectively, was measured in the sperm membrane fraction that contained the highest specific AC activity. As reported in other studies of sperm AC, Mn(2+)-supported AC activity was 15-30 times higher than Mg(2+)-supported AC activity. Interestingly, when the membrane fraction was solubilized with Lubrol-PX, an increase in specific and total Mg(2+)-supported AC activity was obtained while a decrease in both the specific and total Mn(2+)-supported AC activity was observed. In the absence of detergent, the ZP stimulates the membrane AC in a concentration-dependent manner, but this stimulation is observed only when the enzyme activity is measured in the presence of Mg2+. Forskolin also stimulates the Mg(2+)-but not the Mn(2+)-supported AC activity, and this effects is not additive to or synergistic with the ZP stimulation of the membrane AC. Results reported in this study suggest that ZP-mediated stimulation of membrane-associated AC may represent a mechanism by which the ZP affects sperm functions.

Adenylyl Cyclases↗
PubMed1995

Capacitation of mouse spermatozoa. II. Protein tyrosine phosphorylation and capacitation are regulated by a cAMP-dependent pathway.

In the accompanying report (Visconti, P.E., Bailey, J.L., Moore, G.D., Pan, D., Olds-Clarke, P. and Kopf, G.S. (1995) Development, 121, 1129-1137) we demonstrated that the tyrosine phosphorylation of a subset of mouse sperm proteins of M(r) 40,000-120,000 was correlated with the capacitation state of the sperm. The mechanism by which protein tyrosine phosphorylation is regulated in sperm during this process is the subject of this report. Cauda epididymal sperm, when incubated in media devoid of NaHCO3, CaCl2 or bovine serum albumin do not display the capacitation-associated increases in protein tyrosine phosphorylation of this subset of proteins. This NaHCO3, CaCl2 or bovine serum albumin requirement for protein tyrosine phosphorylation can be completely overcome by the addition of biologically active, but not inactive, cAMP analogues. Addition of the active cAMP analogues to sperm incubated in media devoid of NaHCO3, CaCl2 or bovine serum albumin overcomes the inability of these media to support capacitation, as assessed by the ability of the cells to acquire the pattern B chlortetracycline fluorescence, to undergo the zona pellucida-induced acrosome reaction and, in some cases, to fertilize metaphase II-arrested eggs in vitro. The effects of the cAMP analogues to enhance protein tyrosine phosphorylation and to promote capacitation appears to be at the level of the cAMP-dependent protein kinase (PKA), since two specific inhibitors of this enzyme (H-89 and Rp-cAMPS) block the capacitation-dependent increases in protein tyrosine phosphorylation in sperm incubated in media supporting capacitation. Capacitation, as assessed by the aforementioned endpoints, also appears to be inhibited by H-89 in a concentration-dependent manner. These results provide further evidence for the interrelationship between protein tyrosine phosphorylation and the appearance of the capacitated state in mouse sperm. They also demonstrate that both protein tyrosine phosphorylation and capacitation appear to be regulated by cAMP/PKA. Up-regulation of protein tyrosine phosphorylation by cAMP/PKA in sperm is, to our knowledge, the first demonstration of such an interrelationship between tyrosine kinase/phosphatase and PKA signaling pathways.

1-Methyl-3-isobutylxanthine↗
PubMed1994

p95, the major phosphotyrosine-containing protein in mouse spermatozoa, is a hexokinase with unique properties.

Mouse sperm contain a major phosphotyrosine-containing protein of M(r) 95,000 (nonreducing conditions) which has been implicated as a sperm membrane receptor for the egg zona pellucida glycoprotein, ZP3 (Leyton, L., and Saling, P. (1989) Cell 57, 1123-1130; Leyton, L., LeGuen, P., Bunch, D., and Saling, P. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 11692-11695). This protein was purified and subjected to limited tryptic digestion and subsequent amino acid analysis. Three sequenced peptides revealed 100% amino acid identity to a mouse hepatoma hexokinase (Arora, K. K., Fanciulli, M., and Pederson, P. L. (1990) J. Biol. Chem. 265, 6481-6488). The purified protein, which migrated at M(r) 116,000 under reducing conditions (p95/116), reacted with an antiserum to the purified rat brain hexokinase, type 1, and comigrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the purified rat brain enzyme under both nonreducing and reducing conditions. Unlike p95/116, the rat brain enzyme was not a phosphotyrosine-containing protein. The p95/116 protein could be immunoprecipitated with the hexokinase antiserum or an O-phosphotyrosine antibody. Limited tryptic digestion of the purified p95/116 and the rat brain enzyme generated subsets of identical peptides which reacted with the hexokinase antiserum. However, p95/116 also contained phosphotyrosine-containing peptides that were not present in the rat brain hexokinase. When different mouse tissues were probed with the hexokinase antiserum all tissues, with the exception of liver, contained immunoreactive protein. In contrast, only sperm and testis possessed a phosphotyrosine-containing form of hexokinase. These data suggest that the germ cell component of the testis possesses a unique tyrosine-phosphorylated form of hexokinase.

Amino Acid Sequence↗
PubMed1994

Antioxidant status and lipid peroxidation in patients infected with HIV.

Deficiency in antioxidant micronutrients have been observed in patients with AIDS. These observations concerning only some isolated nutrients demonstrate a defect in zinc, selenium, and glutathione. An increase in free radical production and lipid peroxidation has been also found in these patients, and takes a great importance with recent papers presenting an immunodeficiency and more important an increase in HIV-1 replication secondary to free radicals overproduction. We have assessed different studies, trying to obtain a global view of the antioxidant status of these patients. In adults we observe a progressive decrease for zinc, selenium, and vitamin E with the severity of disease, except that selenium remains normal at stage II. However, the main dramatic decrease concerns carotenoids whose level at stage II is only half the normal value. To understand if these decreases in antioxidant and increases in oxidative stress occur secondary to the aggravation of the disease or, conversely, are responsible for it, we undertook a longitudinal survey of asymptotic patients. The preliminary results of this evaluation are presented. Paradoxically, lipid peroxidation is higher at stage II than at stage IV. This may be consecutive to a more intense overproduction of oxygen free radicals by more viable polymorphonuclear (PMN) at the asymptomatic stage. The free radicals production and lipid peroxidation seem secondary to a direct induction by the virus of PMN stimulation and cytokines secretion. N-Acetyl cysteine or ascorbate have been demonstrated in cell culture to be capable of blocking the expression of HIV-1 after oxidative stress and N-acetyl cysteine inhibits in vitro TNF-induced apoptosis of infected cells. In regard to all these experimental data, few serious and large trials of antioxidants have been conducted in HIV-infected patients, although some preliminary studies using zinc or selenium have been performed. In our opinion it is now time to evaluate in humans the beneficial effect of antioxidants. The more promising candidates for presenting synergistic effects when associated with N-acetyl cysteine seem to be beta-carotene, selenium and zinc.

Acquired Immunodeficiency Syndrome↗
PubMed1994

A new rapid immunoinhibition pancreatic amylase assay: diagnostic value for pancreatitis.

A new rapid immunoinhibition pancreatic amylase assay was compared to total amylase and lipase in an unbiased sample of 1005 emergency department patients with suspicion of pancreatitis, of which 55 had a final diagnosis of pancreatitis. Imprecision of the assays for both amylases (less than 2.5%) were better than for lipase (less than 6.1%). Correlation (R2) of pancreatic amylase with total amylase was 0.991 but only 0.789 with lipase. Using Receiver Operator Characteristics analysis, the best diagnostic cutoff point for all three enzymes was near the upper limit of the reference interval. With pancreatic amylase, sensitivity, specificity, and predictive values for positive and negative results are, respectively, 85.5, 92.5, 39.8, and 99.1%; we found similar values for lipase but poorer values (78.2, 92.0, 36.1, and 98.7%) for total amylase. Tests combination did not improve the diagnostic performance significantly. In the diagnosis of pancreatitis, pancreatic amylase (p = 0.037) and lipase (p = 0.049) had better diagnostic performance than total amylase. The correct diagnosis of pancreatitis could be achieved in 47 instead of 43 patients with either pancreatic amylase or lipase as opposed to total amylase among 1005 patients in this study. We conclude that pancreatic amylase and lipase are incrementally better diagnostic tools than total amylase for the diagnosis of pancreatitis.

Acute Disease↗
PubMed1993

Early termination of pregnancy with mifepristone (RU 486) and the orally active prostaglandin misoprostol.

BACKGROUND AND METHODS: The combination of mifepristone (RU 486) and a prostaglandin analogue given either intramuscularly or intravaginally is effective in terminating early pregnancy, but the prostaglandin component of the regimen is cumbersome to administer and has side effects. We conducted two studies to determine the efficacy of 600 mg of mifepristone followed by a small dose of misoprostol, an orally active prostaglandin E1 analogue, for the same purpose. In the first study, 505 women who had had amenorrhea for less than 50 days received 400 micrograms of misoprostol 48 hours after receiving mifepristone, if the pregnancy was not terminated within that period. In the second study, 390 women initially received the same treatment, but if the pregnancy was not terminated within four hours after the administration of misoprostol, they were offered an additional 200-micrograms dose of misoprostol. RESULTS: In study 1, the rate of success (termination of pregnancy and complete expulsion of the conceptus) was 96.9 percent (95 percent confidence interval, 94.1 to 97.7 percent)--similar to the success rate of approximately 95 percent for mifepristone followed by the intramuscular or intravaginal administration of prostaglandin. Abortion occurred in 2.9 percent of the women within 48 hours after the administration of mifepristone, in 60.9 percent within 4 hours after the administration of misoprostol, and in 33.2 percent thereafter. The failures included ongoing pregnancies in four women (0.8 percent) and incomplete abortions in nine (1.8 percent); two other women (0.4 percent) required vacuum aspiration for prolonged uterine bleeding. In study 2, pregnancy was terminated in 5.5 percent of the women before the administration of misoprostol and within four hours after the first dose of misoprostol in 69.1 percent. Among the 71 women who received a second dose of misoprostol, 67 had complete abortions, 2 had partial retention of the conceptus, 1 had synechia with ongoing pregnancy, and 1 had an ectopic pregnancy. One ongoing pregnancy, which was terminated by vacuum aspiration, was recorded among the 27 women who declined to take the second dose of misoprostol. The overall rate of success of the regimen with the optional second dose of misoprostol was 98.7 percent (95 percent confidence interval, 96.8 to 99.5 percent). No woman had any serious adverse event. CONCLUSIONS: The combination of mifepristone and misoprostol is effective for the termination of early pregnancy in terms of success, tolerance, safety, and practicality.

Abortion, Induced↗
PubMed1993

Superior vena cava syndrome in small-cell lung cancer.

BACKGROUND: The aim of this study was to analyze the features of the superior vena cava syndrome (SVCS) as initial characteristics in small-cell lung cancer: incidence, dissemination of disease, diagnostic procedures, efficacy and toxic effects of chemotherapy, and median survival in patients with SVCS. METHODS: In a prospective series of 724 patients with biopsy-proved small-cell lung cancer seen during a 6-year period, we reviewed data from patients who also had SVCS. RESULTS: The incidence of SVCS was 87 of 724 at the time of diagnosis. Initial emergency radiation therapy was not used in these patients. Diagnostic procedures in these patients were not associated with mortality. Rapid initiation of intensive chemotherapy, often with heparin therapy, resulted in complete or partial responses in 81% and no response in 12%; data were not evaluable in 7%. Two of these 87 patients died of aplasia within 4 weeks of chemotherapy. Median survival was not significantly different in the patients with SVCS (median, 42 weeks) and without SVCS (median, 40 weeks). A significant increase in initial brain metastases at the time of diagnosis was observed in patients with SVCS (22% vs 11%). CONCLUSIONS: Intensive chemotherapy is the first line of therapy in small-cell lung cancer. Histologic diagnostic procedures must be performed in patients with SVCS to adapt the treatment to the underlying cause. Initial emergency radiotherapy, before diagnosis or chemotherapy, does not seem to be useful in these patients. Computed tomography of the brain should be performed routinely in patients with SVCS, and prophylactic brain irradiation could be helpful in such patients. Apparently SVCS is not a poor prognostic factor in treated small-cell lung cancer.

Adult↗
PubMed1992

Decrease in calmodulin concentrations during heparin-induced capacitation in bovine spermatozoa.

Concentrations of the intracellular Ca(2+)-mediator calmodulin (CaM), were measured by radioimmunoassay during heparin-induced capacitation of bull spermatozoa. Heparin reduced sperm CaM concentrations in a dose-dependent manner corresponding with an increase in in-vitro fertilization rates. Such reductions were observed after heparin treatment for 4-6 h, which is in agreement with the length of the capacitation period in bulls and was concomitant with an increase in CaM concentration in the incubation medium, suggesting translocation of CaM from the spermatozoa to the surrounding milieu. This CaM translocation was inhibited partly by the protease inhibitor benzamidine, suggesting a role for the sperm protease in this process.

Acrosome↗
PubMed1990

Decreased binding of calmodulin to bull sperm proteins during heparin-induced capacitation.

The 125I-calmodulin gel overlay procedure was used to evaluate the effect of a heparin treatment on the calmodulin-binding proteins of bull spermatozoa. At concentrations that increase the in vitro fertilization rate of in vitro-matured oocytes, heparin induced a decrease in the binding to calmodulin (CaM) in 3 sperm proteins of 28, 30, and 49 kDa. The binding of these proteins to CaM was higher when Ca2+ was absent from the overlay procedure, and this binding was negatively correlated to the fertilization rate. These results suggest that sperm capacitation is associated with a decrease in the binding of CaM to the 28, 30, and 49 kDa sperm CaM-binding proteins. Implications of such a decrease are discussed.

Animals↗
PubMed1989

Effect of heparin on the expression of calmodulin-binding proteins in bull spermatozoa.

A 125I-labelled calmodulin gel overlay procedure in the presence and the absence of Ca2+ was used to evaluate bull spermatozoa calmodulin-binding proteins. Frozen spermatozoa were thawed, washed and incubated for 6 h before being processed for SDS polyacrylamide gel electrophoresis and the 125I-labelled calmodulin gel overlay procedure. In non-incubated spermatozoa, up to 14 binding proteins were detected. Some exhibited greater calmodulin binding in the presence of Ca2+ while others exhibited greater binding when Ca2+ was absent. When heparin (2 micrograms/ml) was present in the incubation medium, a decrease in the calmodulin binding to the proteins of Mr 28,000 and 30,000 was detected in the presence of Ca2+ and EGTA. This effect of heparin was time- and dose-dependent and was increased by the presence of the acrosin inhibitor benzamidine. Sperm capacitation could thus be related to a decrease in the binding of calmodulin to these proteins.

Animals↗
PubMed1989

[Comparison of 2 systems of blood culture: Signal and Bactec].

Two Bactec bottles (aerobic and anaerobic) and one single bottle Signal were used for detecting bacteremia in 405 patients (47 children and 358 adults). The two blood culture Signal and Bactec aerobic were continuous shaking for up to 24 hours. 10.3 p. cent of patients had positive cultures (62.3 p. cent Gram +, aero-anaerobic bacteria). Nine bacteremia were detected by only one system (4 for signal, 4 for Bactec) 77.1 p. cent of 83 strains were positive on the two systems together, but 7.2 p. cent only in the Bactec and 15.6 p. cent only in the Signal. The delay of growth give an advantage to the Bactec (67 p. cent in 24 hours). The advantages and the disadvantages of the two systems were analysed.

Adolescent↗