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G Pernod

Publications and source records attributed to G Pernod.

At least 37 records · Page 2Linked to original sources
PubMed1999

Gas chromatographic-mass spectrometric determination of total homocysteine in human plasma by stable isotope dilution: method and clinical applications.

The detection and quantitation of slight increases of plasma homocysteine levels is of growing interest. This has prompted us to develop a highly sensitive and accurate capillary gas chromatography-mass spectrometry (GC-MS) method. The method proved to be highly sensitive (DL=0.17 micromol/l) with between- and within-run precision less than 6% and 7%, respectively. Reference values of plasma total homocysteine have been determined for men (n=39) and women (n=36), showing a significant difference (P=0.003) between gender. Preliminary results in cerebrovascular accidents and in venous thrombosis are presented.

Adult↗
PubMed1999

Factor IX gene analysis in 70 unrelated patients with haemophilia B: description of 13 new mutations.

Seventy unrelated patients suffering from haemophilia B have been screened for determining the molecular defect and for evaluating the spectrum of factor IX mutations in the Rhône Alpes region in France. Most patients were characterized with respect to factor IX antigen and factor IX coagulant activity. We have used denaturing gradient gel electrophoresis to obtain a full scanning of the whole coding, promoter, and exon flanking sequences of the factor IX gene. This technique enabled us to determine the molecular defect in 68 out of 70 families (97%), and the mutation was further identified in the two last patients with a direct sequencing of the gene. A total of 2 complete gene deletions in patients with antifactor IX inhibitor, 6 small insertions/deletions and 62 point mutations were found. Two of these nucleotide substitutions (Arg145His and Ala233Thr) were detected in 21 patients (30%) suggesting the existence of a local founder effect. Thirteen mutations were previously undescribed, including 7 missense mutations. The detection of mutations in patients affected with haemophilia B may shed some light in the structure-function relationship of factor IX molecule within the coagulation system.

Amino Acid Substitution↗
PubMed1998

Residual bodies stimulate rat Sertoli cell plasminogen activator activity.

Previous studies suggested indirectly that residual bodies (RB) may play a role in the regulation of the proteolytic system within the testis and in the coordination of the spermatogenetic process. In the present study, we examined the effects of RB recovered from adult rat testes by centrifugal elutriation on Sertoli cell plasminogen activator (PA) levels, by zymography and ELISA procedures. Addition of RB to Sertoli cell cultures prepared from 20-day-old rat testes resulted in a dramatic stimulation of PA. Effects were dose- and time-dependent. Phagocytosis of RB by Sertoli cells leads to a rapid stimulation of Sertoli cell interleukin-1alpha (IL-1alpha), a cytokine potentially involved in the regulation of spermatogenesis; the effects of IL-1alpha were investigated. We found that IL-1alpha augmented PA levels and that immunodepletion of Sertoli cell-RB cocultures with anti-IL-1alpha antibodies abrogated the stimulatory effects of RB on PA. Together, the present findings indicate that RB enhance Sertoli cell PA and that IL-1alpha may be involved in that control.

Animals↗
PubMed1998

Plasminogen activator inhibitor-1 is expressed in cultured rat Sertoli cells.

Sertoli cells secrete plasminogen activators (PAs) on both sides of the blood-testis barrier, i.e., in the basal and apical compartments of the seminiferous tubules, whereas peritubular cells secrete plasminogen activator inhibitor-1 (PAI-1), a fast-acting and specific PA inhibitor. While it is likely that PAI-1 produced by peritubular cells counteracts the basal secretion of PA, the nature of the PA inhibitor acting in the apical compartment remains to be demonstrated. In the present study, we showed that Sertoli cells recovered from 20-day-old rats and cultured contained a transcript of 3-3.2 kilobases, which hybridized specifically to a PAI-1 cDNA probe (Northern blot). We verified that the observed PAI-1 transcript could not result solely from the peritubular cells (weakly contaminating the Sertoli cell cultures), by comparing PAI-1 mRNA levels of Sertoli and peritubular cells recovered from 20-day-old rats and cultured. We also demonstrated that cultured Sertoli cells secreted a protein that complexed with tissue-type PA (zymography), indicating that it was biologically active. This protein comigrated with purified PAI-1 as a doublet of 46 and 49 kDa (Western blot). The trophic hormone FSH decreased PAI-1 messenger RNA as well as immunoreactive PAI-1 protein (probably via the cAMP protein kinase A pathway), whereas transforming growth factor ss1 and basic fibroblast growth factor (in a nanomolar concentration) increased both of these. These observations support the hypothesis that PAI-1 is expressed by Sertoli cells and is under a complex hormonal (FSH) and paracrine and/or autocrine control exerted at least by basic fibroblast growth factor and transforming growth factor ss1.

Alkaline Phosphatase↗
PubMed1998

French previously untreated patients with severe hemophilia A after exposure to recombinant factor VIII : incidence of inhibitor and evaluation of immune tolerance.

Fifty French previously untreated patients with severe hemophilia A (factor VIII < 1%), treated with only one brand of recombinant factor VIII (rFVIII), were evaluated for inhibitor development, assessment of risk factors and outcome of immune tolerance regimen. The median period on study was 32 months (range 9-74) since the first injection of rFVIII. Fourteen patients (28%) developed an inhibitor, four of whom (8%) with a high titer (> or = 10 BU). All inhibitor patients but one continued to receive rFVIII either for on-demand treatment or for immune tolerance regimen (ITR). Among these patients, inhibitor was transient in 2 (4%), became undetectable in 6 and was still present in 6. The prevalence of inhibitor was 12%. Presence of intron 22 inversion was found to be a risk factor for inhibitor development. Immune tolerance was difficult to achieve in our series despite a follow-up period of 16 to 30 months: immune tolerance was complete in only one out of the 3 patients undergoing low dose ITR and in one out of the 5 patients with high dose ITR.

Child↗
PubMed1997

Tumor necrosis factor-alpha regulates plasminogen activator inhibitor-1 in rat testicular peritubular cells.

We examined the regulation by tumor necrosis factor-alpha (TNF alpha) of plasminogen activator inhibitor-1 (PAI-1) in cultured peritubular cells recovered from 20-day-old rat testes. We demonstrated that TNF alpha in a nanomolar dose range stimulated PAI-1 messenger RNA (mRNA; Northern blots) as well as immunoreactive (Western blots) and bioactive (Stachrom) PAI-1 protein. Induction of PAI-1 mRNA started 4 h after the addition of TNF alpha (2.5-fold increase) and peaked (7-fold increase) after 24 h of treatment. Actinomycin D and cycloheximide inhibited the effects of TNF alpha on PAI-1 mRNA, suggesting that ongoing RNA and protein syntheses were required. The combined actions of transforming growth factor-alpha (TGF alpha), a potent inducer of PAI-1, and TNF alpha on PAI-1 were less than additive, suggesting the activation of some common pathway. TNF alpha action on PAI-1, like that of TGF alpha demonstrated previously, was masked by a preexposure to phorbol myristate acetate (a stimulator of protein kinase C) and strongly reduced by staurosporine (an inhibitor of the protein kinase C). Furthermore, using genistein to inhibit tyrosine kinase activity, we not only blocked the action of TGF alpha on PAI-1 [initiated upon binding to the tyrosine kinase epidermal growth factor/TGF alpha receptor (EGFR)], but also markedly reduced that of TNF alpha. Finally, TNF alpha, at a dose range that stimulated PAI-1, enhanced EGFR mRNA levels and EGF binding. Together, the present findings suggest that some of the biological effects of TNF alpha on PAI-1 might be secondary to de novo synthesis of EGFR. Because TNF alpha probably originates from testicular macrophages, such a regulation of PAI-1 by TNF alpha may occur in the context of physiological interactions between the testis and the immune system.

Animals↗
PubMed1996

Influence of cytokines on Toxoplasma gondii growth in human astrocytoma-derived cells.

The effects of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin 1-alpha (IL-1-alpha), and interleukin 6 (IL-6) on the growth of the Toxoplasma gondii RH strain were studied in vitro using a human astrocytoma-derived cell line. Cells were treated with cytokines at different concentrations at 24 h prior to infection with T. gondii tachyzoites. IFN-gamma did not induce any modification in T. gondii growth, whatever the concentration used. TNF-alpha induced a significant decrease in the total number of tachyzoites, whereas IL-1-alpha surprisingly induced an increase in the number of tachyzoites. Our results show that the effects of cytokines on T. gondii growth may be of great importance in the control of cerebral toxoplasmosis but that they can vary, depending on the cell type considered.

Animals↗
PubMed1996

Plasminogen activator inhibitor-1 regulation in cultured rat peritubular cells by basic fibroblast growth factor and transforming growth factor-alpha.

In the present study we examined the in vitro regulation of plasminogen activator inhibitor I (PAI-1) expression in peritubular cells recovered from 20-day-old rat testes. We tested two growth factors, basic fibroblast growth factor (bFGF) and transforming growth factor-alpha (TGF alpha). They are synthesized by Sertoli cells, and peritubular cells exhibit the corresponding high affinity receptors. After exposure to bFGF or TGF alpha (0.1-30 ng/ml), PAI-1 messenger RNA levels, as determined by Northern hybridization analysis, increased in a dose-dependent manner. The first significant effects were noted after 2-h exposure to bFGF or TGF alpha (10 ng/ml), and PAI-1 messenger RNA levels were maximally stimulated approximately 12-fold (bFGF) and 8-fold (TGF alpha) after 4 h. The two growth factors increased the amount of immunoreactive (Western blots) and biologically active (Stachrom) PAI-1 measured in the culture medium. Actinomycin D inhibited the effects of these factors, whereas cycloheximide augmented them. Phorbol myristate acetate, an activator of protein kinase C, mimicked the effects of bFGF and TGF alpha. Interestingly, long term (24-h) pretreatment with phorbol myristate acetate resulted in a severe loss of responsiveness to bFGF or TGF alpha. Staurosporine, an inhibitor of protein kinase C, also significantly reduced the effects of bFGF and TGF alpha. Given that PAI-1 inhibits Sertoli cell plasminogen activator activity and that bFGF and TGF alpha are synthesized by Sertoli cells, these factors are likely to interact to regulate protease activity in localized regions of the seminiferous tubule.

Animals↗
PubMed1996

Retinoids induced t-PA synthesis by C6 glioma cells--role in tumoral haemorrhagic necrosis.

Treatment of rat C6 glioma with high doses of 13 cis-retinoic acid (cRA) was responsible for death related to haemorrhagic necrosis localized to the tumor. Our aim was to explore this adverse effect of retinoid treatment. We show that cRA-treated C6 glioma at 25 mg/kg/day for 18 days exhibits in vivo an increase T-PA activity, which is responsible for a localized tumor fibrinolytic activity. Production of t-PA is supported by specific enhancement of gene expression, as was shown by the increase in t-PA mRNA (x 2.3). This production is a direct effect of cRA when treating the tumor, since tumor cells themselves do not produce enough t-PA and treatment of control rats does not increase the t-PA level. T-PA production by rat C6 glioma is in vivo related to the specific synthesis of t-PA by the C6 cell-line. The stimulation of C6 cell-line by cRA in vitro is dose-dependent and reached a maximum for 3 and 30 microM at the 72nd h. So cRA-treated C6 glioma cells produce t-PA which appears to be the major species associated with the fibrinolytic activity-induced intra-tumoral haemorrhage after exposure to retinoid treatment.

Animals↗
PubMed1996

Combined hereditary disorders of haemophilia B Leyden (-6 G-->A) and type 1 von Willebrand disease.

Multiple coagulation disorders are unusual. We report here a combination of haemophilia B Leyden with type 1 von Willebrand disease (vWD) affecting different members of the same family. Haemophilia B Leyden was due to a -6 G-->A mutation within the promoter of the factor IX gene and was responsible for a mild haemophilia in the father of the proband. The proband and her sister (age 4 and 6) exhibited a twofold lower level of factor IX activity (0.4 IU/ml) than the paternal grandmother (0.95 IU/ml). The differences in F IX levels in the three carriers of the same -6 G-->A mutation suggest the implication of an age-related mechanism responsible for the increase in factor IX plasma level. Haemophilia B Leyden patient and carriers suffered also from a mild von Willebrand disease. The diagnosis of this associated type 1 vWD was performed by assaying plasma von Willebrand factor together with multimer electrophoretic studies and DDAVP test. The inheritance of this vWD was investigated by haplotype analysis of the vWF gene. Individuals affected by such an association are actually asymptomatic, but per- and post-operative bleeding risk remains to be evaluated.

Adenine↗