Search PubMed⌕ Search

Biomedical subjects

B Dupont

Publications and source records attributed to B Dupont.

At least 145 records · Page 8Linked to original sources
PubMed1995

[Uncommon fungal maxillary sinusitis of dental origin due to Scedosporium prolificans].

This is the first case report of an exceptional maxillary infection due to Scedosporium prolificans. This recently discovered fungus was identified in the sinus. In the literature, it has been observed at different locations. Identification requires careful sample taking for mycology and pathology studies emphasizing the importance in maxillary surgery. This pathogenic fungus is very invasive, particularly in immunodepressed or immunocompromised patients. Therapeutic modalities vary with the patient's immune status.

Adult↗
PubMed1994

[Prevention of Pneumocystis carinii pneumonia associated with HIV infection using pentamidine aerosols. Retrospective study of 465 cases].

OBJECTIVES: At least 80% of human immunodeficiency virus (HIV)-positive patients not given prophylaxis therapy against Pneumocystis carinii develop pneumonia, a major cause of morbidity and mortality. We therefore retrospectively evaluated prophylaxis protocols given from March 1988 to July 1991 at the Pasteur Institute Hospital. METHODS: Pentamidine aerosols were prescribed for 456 HIV-positive patients as primary or secondary prophylaxis. From March 1988 to November 1989 the dose was 4 mg/kg pentamidine mesylate once a month for primary prophylaxis and 4 mg/kg twice a month for secondary prophylaxis. From November 1989 pentamidine isethionate was given at the dose of 300 mg once a month. RESULTS: Tolerance was generally good, treatment had to be discontinued in only 2 of the 456 patients due to side effects. Pneumocystis carinii pneumonia was diagnosed in 4.9% of the treated patients, but in only 2.9% of those who were compliant. Pneumocystis carinii pneumonia occurred in very immunodepressed patients and radiologically appeared as an interstitial or alveolo-interstitial syndrome, often with a macronodular element, in 65% of the patients. CONCLUSION: The results of this retrospective study confirm the prophylactic value of pentamidine aerosols given after trimethoprim-sulfamethoxasol.

AIDS-Related Opportunistic Infections↗
PubMed1994

CD28 is associated with and induces the immediate tyrosine phosphorylation and activation of the Tec family kinase ITK/EMT in the human Jurkat leukemic T-cell line.

T lymphocytes require two signals to be activated. The antigen-specific T-cell receptor can deliver the first signal, while ligation of the T-cell surface molecule CD28 by antibodies or its cognate ligands B7-1 (CD80) or B7-2 has been demonstrated to be sufficient for the delivery of the second signal. Signaling via CD28 and the T-cell receptor results (i) in their costimulation of T cells to produce numerous lymphokines including interleukin 2 and (ii) in the prevention of anergy induction. Little is known about the pathway by which CD28 mediates its signals except that protein-tyrosine phosphorylation is involved. We show here in human Jurkat cells that the Tec-family protein-tyrosine kinase ITK/EMT (p72ITK/EMT) is associated with CD28 and becomes tyrosine-phosphorylated and activated within seconds of CD28 ligation. This tyrosine phosphorylation of p72ITK/EMT is rapid (within 30 sec), occurs in the absence of LCK activation, and precedes tyrosine phosphorylation of the guanine nucleotide exchange factor VAV. Secondary crosslinking of CD28 is unnecessary for the induced tyrosine phosphorylation of p72ITK/EMT. Thus, tyrosine phosphorylation of p72ITK/EMT may represent one of the earliest events in CD28 signaling. This demonstrates that a member of the Tec family of protein tyrosine kinases, similar to members of the Src and Syk families, plays a role in the activation of T cells. Furthermore, the data demonstrate that p72ITK/EMT, and by analogy other members of the Tec family, responds to extracellularly generated signals.

CD28 Antigens↗
PubMed1994

Activation of src family kinase lck following CD28 crosslinking in the Jurkat leukemic cell line.

T lymphocytes require a signal via their antigen specific receptors (the T cell receptors) and an antigen independent costimulatory signal. Signals through CD28 can costimulate T cells in the presence of limiting amounts of T cell receptor signal, or in the presence of PMA, providing this second signal. CD28 signaling is known to involve the activation of protein tyrosine kinases. Using the Jurkat leukemic cell line as a model, we have tested CD28 crosslinking for its effects on the protein tyrosine kinases p56lck. We report that following crosslinking of CD28, p56lck kinase activity is increased. Crosslinking CD28 causes a shift in the relative mobility of p56lck from 56 to 60 kD similar to that seen after crosslinking of CD2 and CD4, cell surface receptors known to be associate with and activate p56lck. Finally, lck could be found in anti-CD28 immunoprecipitates in exponentially growing Jurkat and in "activated" CD28 (i.e., cross linked), but not in CD28 in resting Jurkat cells. These findings suggest an important role for p56lck in CD28 signal transduction.

Animals↗
PubMed1994

pH and temperature effects on kinetics of creatine kinase in aqueous solution and in isovolumic perfused heart. A 31P nuclear magnetization transfer study.

Phosphorylated metabolites concentrations and creatine kinase kinetics are measured by 31P NMR in solution and in isovolumic perfused rat hearts submitted to hypo- and hyperthermia as well as to acidosis (37 degrees C). In the organ, temperature variation from 40 to 25 degrees C induces an increase of phosphocreatine (PCr) stores, a decrease of Pi and ADP concentrations, but does not affect the ATP pool. Creatine kinase forward flux (Vfor) is gradually reduced when the temperature is lowered both in vitro and in perfused heart. In normothermic and hypothermic conditions, a relationship is found between cardiac performance (rate pressure product, RPP), Vfor and ATP synthesis estimated through the myocardial oxygen consumption rate (MVO2). At 40 degrees C however, the RPP is reduced although both Vfor and MVO2 increase. In vitro experiments show an optimum pH of 7.7 for the forward creatine kinase reaction. In perfused heart submitted to acidosis, a decrease of PCr concentration is observed, whereas ATP and ADP contents remain unchanged. Heart creatine kinase flux increased as in hyperthermia. These high fluxes are attributed to the coupling of the creatine kinase reaction with energy consuming or producing reactions: the increase of energy demand related to non-contractile processes could explain the high MVO2 and Vfor observed in those conditions.

Adenosine Triphosphate↗
PubMed1994

Aspergillus fumigatus metalloproteinase that hydrolyses native collagen: purification by dye-binding chromatography.

A proteinase was purified from the human pathogenic fungus Aspergillus fumigatus. The four chromatographic steps, a "negative" dye column, a "positive" dye column, hydroxyapatite Ultrogel, and modified TSK gel (HW 55), gave a 14% overall yield. The protein migrated as a single band on SDS-PAGE and isoelectric focusing, with an M(r) of 82,000 and a pI of 5.6. Inhibitor studies suggested that the enzyme was a metalloproteinase. It hydrolyzed phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-Arg and cleaved native rat type I collagen.

Amino Acid Sequence↗
PubMed1994

A natural focus of Histoplasma capsulatum var. duboisii is a bat cave.

The natural reservoir of Histoplasma capsulatum var. duboisii, the etiological agent of histoplasmosis duboisii (African histoplasmosis) is not yet known. We report the isolation of H. capsulatum var. duboisii from soil admixed with bat guano and from the intestinal contents of a bat in a sandstone cave in a rural area, Ogbunike in Anambra State of Nigeria. Eight of 45 samples of soil admixed with bat guano yielded H. capsulatum var. duboisii. Of the 35 bats belonging to the species Nycteris hispida and Tadirida pumila examined, only one (N. hispida) yielded this fungus from its intestinal contents. Identification of the isolates as Histoplasma was confirmed by exoantigen tests and by mating with tester strains of H. capsulatum. In vitro conversion to large yeast from suggestive of H. capsulatum var. duboisii was obtained on brain heart infusion agar supplemented with sheep blood and glutamine or cysteine. Pathogenicity tests with mice for all the isolates confirmed their identity by the demonstration of large yeast forms (8-15 microns in diameter) within giant cells in the infected tissues. Investigations on the possible occurrence of human infections in the area are in progress.

Animals↗
PubMed1994

CD28 of T lymphocytes associates with phosphatidylinositol 3-kinase.

T lymphocyte activation requires recognition of antigen by the antigen specific TCR as well as second co-stimulatory signals. This recognition event results in the activation of non-TCR linked protein tyrosine kinases (PTKs). The mechanism of co-stimulation of T cells is unknown except for the involvement of PTKs. The T cell surface molecule CD28 is effective in delivering co-stimulatory signals and prevents T cell anergy by inducing T cell proliferation in TCR stimulated T cells, primarily due to an increase in IL-2 production. The mechanism by which CD28 mediates this effect is currently unknown. Some conventional receptor molecules possess intrinsic tyrosine kinase and as a consequence of cross-linking or ligand binding, phosphorylate numerous tyrosines within their cytoplasmic tail, leading these tyrosines to become 'activated' and bind cytoplasmic effector molecules possessing Src homology 2 domains which specifically recognize phosphorylated tyrosines. One such cytoplasmic effector molecule is the phosphatidylinositol-3-phosphate kinase (PI3 kinase) which recognizes the motif phosphotyrosine-methione/valine-X-methionine (X being any amino acid) within the cytoplasmic tails of numerous receptor tyrosine kinases. As CD28 contains a copy of the PI3 kinase binding motif within its cytoplasmic tail, we investigated CD28 signaling and PI3 kinase activation. Here we demonstrate using the Jurkat cell line that CD28 becomes tyrosine phosphorylated following CD28 cross-linking and associates with PI3 kinase. Furthermore, a synthetic peptide representing the YM/VXM motif within the cytoplasmic tail of CD28 also interacts with PI3 kinase only when the tyrosine is phosphorylated.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Cardiac lymphoma presenting as atrial flutter in an AIDS patient.

An increasing number of patients with the acquired immunodeficiency syndrome (AIDS) and cardiac lymphoma have been documented. Antemortem diagnosis of cardiac non-Hodgkin lymphoma in AIDS is difficult because of the non-specificity of the clinical findings. Rapid progression of cardiac dysfunction is common after symptoms appear. We report the case of a patient with AIDS and cardiac lymphoma revealed by an atrial flutter.

Atrial Flutter↗
PubMed1994

Primary central nervous system malignant non-Hodgkin's lymphomas from HIV-infected and non-infected patients: expression of cellular surface proteins and Epstein-Barr viral markers.

The increased incidence of primary central nervous system malignant non-Hodgkin's lymphomas (PCNSL) in HIV- and non-HIV-infected patients and the demonstration of Epstein-Barr virus (EBV) in these tumours may indicate relationships between PCNSL and EBV. Consequently expression of EBV-induced antigens and cellular markers were studied in 11 HIV-infected and seven non-infected patients by in situ hybridization (ISH) and immunocytochemistry in monoclonal B cell PCNSL. In HIV-infected patients EBV genome was present in 9/11 cases, LMP in 11/11 cases and EBNA2 in 10/11 cases. The expression of adhesion and activation molecules was low or absent. In HIV non-infected patients, EBV genome was present in 5/7 cases, with LMP in 4/7 cases. EBNA2 was never detected. All these lymphomas expressed LFA1beta. Whatever the population, no lytic cycle EBV markers were detected. Compared with other types of EBV lymphomas, our results suggest a different EBV latency state in primary B cell lymphomas of the CNS from HIV-infected or non-infected patients.

Adult↗