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P Leclerc

Publications and source records attributed to P Leclerc.

At least 37 records · Page 2Linked to original sources
PubMed2001

Characterization of an 80-kilodalton bull sperm protein identified as PH-20.

This paper presents the partial characterization and the identification of an 80-kDa protein detected in bull spermatozoa using a monoclonal antibody directed against a 16-amino acid long peptide from the N-terminal domain of the protooncogene p60(src) from the Rous Sarcoma Virus When subjected to two-dimensional electrophoresis, this 80-kDa protein migrated as several isoforms, with an isoelectric point ranging from 7.4 to 8.2. Amino acid sequence analysis of a peptide obtained following trypsin digestion of the bull sperm protein showed homology to the PH-20/hyaluronidase precursor sperm protein. As for PH-20, this bull sperm 80-kDa protein is located at the plasma membrane surface in the postacrosomal region of the head. An increased immunolabeling in the anterior head region of fixed/permeabilized spermatozoa was observed when these cells were incubated under capacitating conditions, whereas most sperm cells challenged with the calcium ionophore A23187 to acrosome react lost their labeling almost completely. As for the PH-20 protein, the 80-kDa bull sperm protein possesses a hyaluronidase activity that is higher at pH 7.0 than at pH 4.0 in an in-gel assay. Unlike what has been observed in the guinea pig, mouse, and human PH-20, this 80-kDa protein was not released from the surface of bull spermatozoa by treatment with phosphatidylinositol-specific phospholipase C or with trypsin. However, this protein was not sedimented by a 100,000 x g centrifugation after nitrogen cavitation, which suggests that the 80-kDa protein is loosely attached to the sperm membrane by a yet-unknown mechanism. These results suggest that the 80-kDa bull sperm protein shares many homologies with the sperm PH-20 protein reported in the literature and, most likely, is the bull sperm homologue of the PH-20.

Acrosome Reaction↗
PubMed2000

Assessment of sex chromosome aneuploidy in sperm nuclei from 47,XXY and 46,XY/47,XXY males: comparison with fertile and infertile males with normal karyotype.

Sex chromosome aneuploidy was assessed in spermatozoa from a 47,XXY male and a 46,XY/47,XXY male using three colour fluorescence in-situ hybridization (FISH) and compared with two control groups. The first group included subjects of proven fertility and the second infertile males with normal constitutional karyotype. The frequencies of XX and YY disomic, XY hyperhaploid and diploid spermatozoa were significantly increased in the 47,XXY male compared to subjects from the two control groups (P < 0.0001). For the 46,XY/47,XXY sample, the same results were observed, except that the incidence of YY disomic spermatozoa did not differ significantly from the rate obtained in infertile patients. The frequency of sex chromosome aneuploidy did not differ significantly between the 47,XXY and the 46,XY/47,XXY males, except for XX disomic sperm nuclei which was higher in the 47,XXY patient. The frequency of chromosome 12 disomy was also increased in the two XXY individuals (0.42 and 0.49% respectively; P < 0.0001). The meiotic abnormalities observed in the two XXY patients arose through segregation errors in XY germ cells. The increased number of meiotic non-disjunctions observed in the germ cells of infertile males may be a common feature of the deficient oligo- or azoospermic testis. Patients with Klinefelter's syndrome with oligozoospermia have an increased risk of both sex chromosome and autosome aneuploidy in their progeny.

Adult↗
PubMed2000

Distribution and localization of calmodulin-binding proteins in bull spermatozoa.

Previous studies from our laboratory have shown that a decrease in the calmodulin binding properties of a few sperm proteins occurs during the capacitation process, an effect associated with a decrease in intracellular calmodulin concentrations. Using biotinylated-calmodulin nitrocellulose overlay assay on protein extracts of subcellular fractions of bull spermatozoa, one of these proteins (p32) is detected in the flagellar-enriched fractions, whereas p30 is found in the fraction enriched with sperm heads. This latter calmodulin binding protein, p30, appears to be associated with the perinuclear theca. None of these binding proteins was solubilized by nonionic detergents. Sodium dodecyl sulfate was effective solubilizing p32, whereas p30 was extracted only in conditions reported to isolate the perinuclear theca. Cellular localization of calmodulin binding proteins was also achieved by incubating spermatozoa fixed on slides with biotinylated calmodulin and revealed in a further step by fluorescein-conjugated streptavidin. Using this procedure, it was found that calmodulin binds to the sub- and postacrosomal areas of the sperm head along with the midpiece in the presence of Ca(2+). Only a sharp band of fluorescence at the subacrosomal area was observed when this procedure was performed in the absence of Ca(2+) in the presence of EGTA. The pattern of cellular calmodulin binding was highly decreased when spermatozoa were incubated under capacitating conditions, in the presence of heparin, in agreement with the published effect of capacitation on calmodulin binding proteins.

Acrosome↗
PubMed2000

Cryptogenic organizing pneumonia. Characteristics of relapses in a series of 48 patients. The Groupe d'Etudes et de Recherche sur les Maladles "Orphelines" Pulmonaires (GERM"O"P).

Cryptogenic organizing pneumonia (COP) is a clinicopathologic syndrome characterized by rapid resolution with corticosteroids, but frequent relapses when treatment is tapered or stopped. We retrospectively studied relapses in 48 cases of biopsy-proven COP. One or more relapses (mean 2.4 +/- 2.2) occurred in 58%. At first relapse, 68% of patients were still under treatment for the initial episode. Compared with the no-relapse group, nine patients with multiple (>/= 3) relapses had longer delays between first symptoms and treatment onset (22 +/- 17 versus 11 +/- 8 wk, p = 0.02), and elevated gamma-glutamyltransferase (124 +/- 98 versus 29 +/- 13 IU/L, p = 0.001) and alkaline phosphatase (190 +/- 124 versus 110 +/- 68 IU/L, p = 0.04) levels. Relapses did not adversely affect outcome. Corticosteroid treatment side effects occurred in 25% of patients. Standardized treatment in 14 patients allowed a reduction of prednisone cumulated doses (p < 0.05) without affecting outcome or relapse rate. We conclude that: (1) delayed treatment increases the risk of relapses; (2) mild cholestasis identifies a subgroup of patients with multiple relapses; (3) relapses do not affect outcome, and prolonged therapy to suppress relapses appears unnecessary; (4) a standardized treatment allows a reduction in steroid doses.

Adult↗
PubMed2000

Prevalence of HIV infection and risk behaviours among Montreal street youth.

We aim to estimate HIV prevalence and associated risk factors among street youth in Montreal, Canada. We conducted a one-year cross-sectional anonymous study in 1995. We recruited youth aged 13-25 years meeting specific criteria for itinerancy through the 20 major Montreal street youth agencies. Participation included a structured interview and provision of an oral specimen for HIV testing. Among the 909 subjects studied, 99.3% had been sexually active, 25.9% had exchanged sex for money, gifts, drugs, a place to sleep, or other things; 31.8% reported anal sex; and 36.4% reported having ever injected drugs. Overall, HIV prevalence was 1.9% (1.1% in girls and 2.2% in boys). Multivariate logistic regression showed that being over 20 years of age (adjusted odds ratio (AOR) 7.09), having injected drugs (AOR 4.48), having engaged in prostitution (AOR 3.32), and being born outside Canada (AOR 4.41) were all independently associated with HIV infection.

Adolescent↗
PubMed2000

[Aggressive osteoblastoma of the carpal scaphoid bone].

We report a case of aggressive osteoblastoma of the scaphoid bone and discuss the features of this tumor. The few reported cases emphazise the rarity of osteoblastoma in hand and wrist localizations. Pathological examination is mandatory before treatment due to lack of distinctive clinical and radiological features. In our case, the rapidiy aggressive progression, similar to a malignant tumor, required radical treatment with scaphoïdectomy.

Adult↗
PubMed1999

A randomized clinical trial comparing concurrent and alternating thoracic irradiation for patients with limited small cell lung carcinoma. "Petites Cellules" Group.

BACKGROUND: Although thoracic radiotherapy is considered to be useful for the treatment of patients with small cell lung carcinoma (SCLC), its optimal administration schedule is still controversial. METHODS: In a multicenter clinical trial, 164 patients with limited SCLC (of whom 156 were eligible for the study) were randomized to receive either concurrent thoracic irradiation, initiated immediately after the second cycle of chemotherapy (Days 30-64) at a dose of 50 grays in 20 fractions, or alternating thoracic irradiation, scheduled in 3 courses between the second, third, fourth, and fifth cycles of chemotherapy with a 7-day rest period after and before chemotherapy at a dose of 20 grays in 8 fractions (Days 36-47 and Days 64-75) and then 15 grays in 6 fractions (Days 92-101). The same chemotherapy regimen (cyclophosphamide-doxorubicin or vindesine-etoposide) was administered every 4 weeks in both groups. RESULTS: Concurrent radiotherapy-induced lung toxicity led to early termination of this trial when a significant difference was observed (6 cases vs. 1, P = 0.05, 2-sided log rank test). Objective response rates were 89% in the 82 patients of the concurrent radiotherapy group and 95% in the 74 patients of the alternating radiotherapy group. Median survival periods were 13.5 and 14.0 months, respectively, with no significant difference between the two survival distributions (P = 0.15, 2-sided log rank test). Toxic deaths due to bone marrow hypoplasia were similar in both groups (3 vs. 2), but mortality due to lung toxicity (pulmonary fibrosis) was more frequent with concurrent radiotherapy (6 patients) than with alternating radiotherapy (1 patient) in long term analysis (P = 0.05, 2-sided log rank test). CONCLUSIONS: Although no statistically significant overall survival difference was observed between the two radiation therapy schedules, the better tolerance of the alternating schedule justifies the choice of this schedule with this chemotherapy regimen, although it may not be applicable to other chemotherapy regimens.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Hepatitis B virus infection among street youths in Montreal.

BACKGROUND: Street youths are at high risk for many health problems, including sexually transmitted diseases and bloodborne infections. The authors conducted a cross-sectional anonymous study from December 1995 to September 1996 involving street youths in Montreal to estimate the prevalence of risk behaviours for hepatitis B virus (HBV) infection and of markers of past and present HBV infection. METHODS: Participants were 437 youths aged 14 to 25 meeting specific criteria for itinerancy who were recruited in collaboration with the 20 major street youth agencies in Montreal. Sociodemographic and lifetime risk factor data were obtained during a structured interview, and a blood sample was taken to test for HBV markers (hepatitis B surface antigen and antibodies to the hepatitis B core antigen). Univariate analyses and multivariate logistic regressions were conducted. RESULTS: The mean age of the subjects was 19.5 years; 69.3% (303/437) were males. Many subjects had high-risk behaviours: 45.8% (200/437) had injected drugs, 24.5% (107/436) had engaged in prostitution, and 8.7% (38/437) reported having a sexual partner with a history of unspecified hepatitis. The prevalence rate for one or both HBV markers was 9.2% (40/434) (95% confidence interval [CI] 6.7%-12.3%). Multivariate logistic regression analysis showed that being over 18 years of age (adjusted odds ratio [OR] 4.5, 95% CI 1.8-11.7), having injected drugs (adjusted OR 3.5, 95% CI 1.5-8.3) and having had a sexual partner who had unspecified hepatitis (adjusted OR 3.2, 95% CI 1.3-7.5) were all associated with HBV infection. INTERPRETATION: Street youths are at high risk for HBV infection. Early and complete HBV vaccination among this vulnerable population is urgently needed.

Adolescent↗
PubMed1999

Delimitation of two regions in the 90-kDa heat shock protein (Hsp90) able to interact with the glucocorticosteroid receptor (GR).

The role of the 90-kDa heat shock protein (Hsp90) as a chaperone and its regulatory functions for cellular proteins such as the glucocorticosteroid receptor (GR) depends on the direct interaction of the Hsp90 with the corresponding protein as part of a multiprotein complex. The search for the amino acid sequence(s) in Hsp90 involved in interaction with the human GR has been carried out by mutational deletion analysis in whole cells, studying the effects of interaction on the nucleocytoplasmic distributions of transiently expressed Hsp90 and GR derivatives in COS-7 cells. Using a recently developed confocal microscopic immunofluorescence method that allows quantification of the nucleocytoplasmic ratios of the proteins in individual cells and statistical comparison of cell populations, two subregions of the Hsp90 molecule have been defined that allow interaction with GR (residues 206-291 and 446-581). The latter region may play a fundamental role in the interaction, while the former may merely stabilize the binding to GR of the intact Hsp90 molecule. Moreover, the dissection of the Hsp90 molecule allowed us to define two regions displaying nuclear localization activity (residues 1-206 and 381-581), followed by two regions having a predominantly cytoplasmic localization activity (residues 287-381 and 581-728) and counteracting the nuclear localization activities.

Animals↗
PubMed1999

[Anterior trans-scaphoid-lunate luxation of the wrist. Apropos of a case].

About one uncommon case of anterior perilunate fracture-dislocation, the authors show the interest of posterior approach of the wrist to treat all the lesions. The scaphoïd is screwing proximally to distally and a pin is used to stabilise the pyramidolunare articulation. The clinical results are good on motion, on strength; the lunate doesn't present necrosis on radiology at 4 years.

Aged↗
PubMed1998

Quantification of the nucleocytoplasmic distribution of wild type and modified proteins using confocal microscopy: interaction between 90-kDa heat shock protein (Hsp90 alpha) and glucocorticosteroid receptor (GR).

The investigation of molecular interactions in whole cells by immunofluorescence was developed recently, based on the targeting of the protein partners to different cellular compartments and analysis of the modifications in their subcellular distribution resulting from their interaction. This paper describes the adaptation of the confocal microscopy to the quantification of the partitioning of transiently coexpressed proteins between nucleus and cytoplasm. We defined a nucleocytoplasmic ratio R, corresponding to the difference between nuclear and cytoplasmic fluorescence intensities divided by their sum (N - C/N + C), which does not refer to absolute fluorescence intensities. Interaction was detected by statistically comparing the distribution of R value frequencies in cell populations expressing one or both proteins. The convenience of this whole cell method was demonstrated by detecting and analyzing interaction between the human glucocorticosteroid receptor (GR) and the chick 90-kDa heat shock protein (Hsp90), using various combinations of wild-type and nuclear- or cytoplasmic-targeted GR and Hsp90. In addition, three Hsp90 deletion/ truncation mutants were tested: the C-terminal truncated mutant NC4 interacted slightly, indicating the contribution of this part of the molecule to the interaction with GR, while the shorter truncated mutant NC6 did not interact with GR, likely resulting from an incorrect folding of the molecule. No role for the first charged region (delta A') was found as shown by the strong interaction detected for the delta A'Hsp90. This method can fruitfully be applied to the delimitation of the amino-acid sequences involved in protein-protein interaction by mutational analysis, especially to seek confirmation of other methods or when other approaches have failed.

Animals↗
PubMed1998

Regulated expression of cadherin-6 and cadherin-11 in the glandular epithelial and stromal cells of the human endometrium.

The cadherins are key morphoregulators. A switch in the cadherin subtype(s) expressed by a population of cells has been associated with the differentiation and formation of tissues during embryonic development. To date, the role(s) of the cadherins in the highly regulated remodeling processes which occur in the human endometrium in preparation for the implanting embryo remain poorly characterized. Here we report that two atypical cadherins, known as cadherin-6 and cadherin-11, are spatiotemporally expressed in the human endometrium during the menstrual cycle. Cadherin-6 levels are high in both the glandular epithelium and stroma of the endometrium during the follicular phase and decline as the cycle enters the luteal phase. The down-regulation of cadherin-6 in the glandular epithelium during the luteal phase does not effect the levels of cadherin-11 in this cell type. In contrast, the loss of cadherin-6 expression in endometrial stroma cells is concomitant with an increase in the levels of cadherin-11. Collectively, these observations suggest that multiple factors regulate the expression of these two endometrial cadherins. As a first step in identifying these factors, we examined the effects of progesterone on cadherin-6 and cadherin-11 expression in isolated endometrial stromal cells. Progesterone was capable of differentially regulating the expression of these two stromal cell adhesion molecules. These findings lend further support to our hypothesis that steroids are key regulators of cadherin expression in mammalian tissues.

Cadherins↗
PubMed1998

Interaction and dissociation by ligands of estrogen receptor and Hsp90: the antiestrogen RU 58668 induces a protein synthesis-dependent clustering of the receptor in the cytoplasm.

The in vivo interaction of estrogen receptor (ER) and Hsp90, demonstrated in the absence of hormone by a nuclear cotranslocation assay of the cytoplasmic Hsp90 with the karyophilic receptor, was disrupted by agonist and antagonist ligands, which, after dissociating the Hsp90, allowed the chaperone protein to be relocalized in the cytoplasm. The pure antiestrogen RU 58668 (RU), which was unable to stimulate an estrogen-dependent reporter gene and completely inhibited its estradiol-induced activity, also profoundly modified the subcellular distribution of ER in a specific time- and dose-dependent manner; ER appeared as speckled fluorescent clusters mainly located in the perinuclear region of the cytoplasm. The kinetics of appearance and reversal of the RU-dependent ER mislocalization in the presence or absence of cycloheximide demonstrated 1) that this effect was reversed by RU withdrawal or estradiol (E2) treatment, and 2) that cycloheximide with RU inhibited and reversed the ER cytoplasmic mislocalization induced by RU alone. These results point to a protein synthesis-dependent step in the mechanism of action of this antiestrogen. After RU treatment, a large portion of ER was found in the particulate fraction of the cytoplasm. However, confocal and electron microscopic analysis showed that ER clusters were not associated with specific cytoplasmic organelles or compartments. Using ER mutants, it was found that the ligand binding domain was sufficient for RU to produce receptor mislocalization, while the constitutive nuclear localization signals were dispensable. We propose that the antiestrogenic properties of RU are primarily due to the induction of an aggregation-prone receptor conformation that cannot undertake the constitutive and the ligand-induced nuclear localization function of the receptor because it is sequestered in the cytoplasm by fast turning over protein(s). We predict that antiestrogens able to block ER nuclear localization will behave as pure antihormones and will inhibit all the nuclear action of ER elicited by agonistic ligands or by ligand-independent mechanisms such as growth factor stimulation.

Animals↗
PubMed1998

Prognostic significance of supraclavicular lymph nodes in small cell lung cancer: a study from four consecutive clinical trials, including 1,370 patients. "Petites Cellules" Group.

STUDY OBJECTIVE: To determine the prognostic significance of supraclavicular lymph node (SCLN) involvement in small cell lung cancer. MATERIALS AND METHODS: Patients (1,370) with small cell lung cancer were included in four consecutive clinical trials and classified as having either limited or extensive forms of disease using the Veterans Administration staging system. RESULTS: SCLN was present in 17% of patients (n = 234). Median survival was 258 days for patients with SCLN (n = 234) and 297 days for patients without SCLN (n = 1136) (p = 0.002). SCLN involvement was correlated with the presence of distant metastases at baseline (169 vs 65, p = < 0.001). Median survival was 375 days for patients with limited forms without SCLN (n = 529), 332 days for those with limited forms with SCLN (n = 65) (p = 0.12), 244 days for those with extensive forms without SCLN (n = 604), and 228 days for those with extensive forms with SCLN (n = 169) (p = 0.94). The 2-year survival rates were 17%, 12%, 2%, and 4%, respectively. Cox models confirmed that SCLN did not provide any significant additional prognostic information. CONCLUSION: SCLN is highly correlated with extensive forms explaining its overall prognostic value. In limited disease, SCLN is only a minor poor prognostic factor, not justifying any amendment to the staging system currently used.

Adult↗
PubMed1997

Regulation of protein-tyrosine phosphorylation and human sperm capacitation by reactive oxygen derivatives.

Spermatozoa undergoing capacitation, a necessary prerequisite event to successful fertilization that can be induced in vitro by reactive oxygen species (ROS), generate superoxide anion (O2.-). Because, in neutrophils, the generation of O2.- is associated with tyrosine phosphorylation of several proteins, the aim of the present study was to investigate the association between protein-tyrosine phosphorylation and ROS-induced human sperm capacitation. Human spermatozoa express two major phosphotyrosine-containing proteins of 105 and 81 kDa, the phosphotyrosine content of which is increased when spermatozoa are incubated under capacitating conditions. Superoxide dismutase and catalase abolish both sperm capacitation and tyrosine phosphorylation of p105 and p81, suggesting the involvement of O2.- and hydrogen peroxide in these two processes. Inhibitors of NADPH oxidase, the enzyme responsible for the neutrophil's respiratory burst, decrease both p105 and p81 tyrosine phosphorylation and sperm capacitation while hydrogen peroxide stimulates these two processes. Tyrosine phosphorylation of p105 and p81 occurs through a herbimycin A-sensitive tyrosine kinase, and sperm incubation with phosphotyrosine-protein phosphatase inhibitors results in an increase in phosphotyrosine content of these two proteins. Indirect immunocytochemical studies reveal phosphotyrosine-containing proteins mostly in the principal piece of the flagellum, in agreement with the localization of p105 and p81 in the human sperm fibrous sheath. Although tyrosine phosphorylation of p105 and p81 and sperm capacitation are related in a time-dependent fashion, some discrepancies are observed in the regulation of these two processes according to the redox status of the spermatozoa.

Enzyme Inhibitors↗
PubMed1997

Capacitation as a regulatory event that primes spermatozoa for the acrosome reaction and fertilization.

Capacitation is defined as the series of transformations that spermatozoa normally undergo during their migration through the female genital tract, in order to reach and bind to the zona pellucida, undergo the acrosome reaction, and fertilize the egg. During this process, extensive changes occur in all sperm compartments (head and flagellum; membrane, cytosol, cytoskeleton), factors originating from epididymal fluid and seminal plasma are lost or redistributed and membrane lipids and proteins are reorganized; ion fluxes induce biochemical modifications and controlled amounts of reactive oxygen species are generated; spermatozoa develop hyperactivated motility; and complex signal transduction mechanisms are initiated. The main purpose of capacitation is to ensure that spermatozoa reach the eggs at the appropriate time and in the appropriate state to fertilize these eggs, by finely-controlling the rate of the changes necessary to prime spermatozoa and by activating all the mechanisms needed for the subsequent acrosome reaction. The reversibility of some of the mechanisms leading to sperm capacitation may therefore be a very important aspect of the fine regulation and perfect timing of this process.

Acrosome↗