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Biomedical subjects

V David

Publications and source records attributed to V David.

At least 19 recordsLinked to original sources
PubMed1992

Endoplasmic reticulum resident protein of 90 kilodaltons associates with the T- and B-cell antigen receptors and major histocompatibility complex antigens during their assembly.

In the endoplasmic reticulum (ER), newly synthesized subunits of the T-cell antigen receptor (TCR), membrane-bound immunoglobulin (mIg), and major histocompatibility complex (MHC) class I antigens must fold correctly and assemble completely into multimeric protein complexes prior to transport to the cell surface. Although folding and assembly may occur spontaneously, the concept that molecular chaperones facilitate these events is emerging. Here, an intracellular protein of 90-kDa apparent molecular mass, denoted IP90, was shown to be an ER resident protein that associated with partial complexes of the TCR, mIg, and MHC class I proteins but was absent from fully assembled complexes. We speculate that IP90 might participate in folding and assembly processes of these and other multisubunit protein complexes during their transit through the ER.

Animals↗
PubMed1992

A continuous restriction map from HLA-E to HLA-F. Structural comparison between different HLA-A haplotypes.

The class I region of the human major histocompatibility complex contains genes encoding the classical transplantation antigens (HLA-A, B, and C), at least three new class I genes (HLA-E, F, and G) and many class I pseudogenes (including HLA-H). By pulse field gel electrophoresis and using five rare cutter enzymes, we have constructed a precise and continuous map of 1200 kilobases (kb) around HLA-A. The blots were hybridized with HLA-A, E, and F-specific probes and with new probes derived from yeast artificial chromosomes and cosmids of the class I region. We have compared the genomic organization of the same 1200 kb in three homozygous lymphoblastoid cell lines corresponding to three different HLA haplotypes (A3, A24, and A31). The differences in size observed may have been caused by insertions and deletions and may prove valuable in understanding the evolution of the HLA chromosomal region.

Genes, MHC Class I↗
PubMed1992

Germ line variable regions that match hypermutated sequences in genes encoding murine anti-hapten antibodies.

We asked whether there are germ line immunoglobulin variable (V) segments that match sites of hypermutation in V regions encoding murine antibodies. Murine germ line DNA was probed with a panel of short deoxyoligonucleotides identical in sequence to segments of hypermutated V regions from hybridomas generated in the BALB/c response to the hapten 2-phenyloxazolone (Ox). Germ line sequences that match mutations in both heavy and kappa light chain V regions were identified, and clones of some of these germ line V segments were obtained. Comparison of these clones with hypermutated V regions revealed regions of identity ranging in size from 7 to over 50 nucleotides. In an effort to separate the effects of antigen selection from the mutagenic process, we also searched for matches to a panel of silent mutations in VH regions from germinal center B cells. Fourteen silent mutations occur among a collection of 36 hypermutated VH regions from two separate germinal centers of C57BL/6 mice stimulated with the hapten 4-hydroxy-3-nitrophenyl. Matches to nine of these silent mutations can be found among published sequences of C57BL/6 VH regions of the J558 family. Taken together, these data are consistent with the possibility that a template-dependent mutational process, like gene conversion, may contribute to somatic hypermutation.

Animals↗
PubMed1992

Familial screening for genetic haemochromatosis by means of DNA markers.

Genetic haemochromatosis (HFE) is a frequent and potentially fatal disease. Early phlebotomies may prevent complications. The recessive gene for HFE is unknown but closely linked to the HLA-A locus. No direct test for homozygosity for HFE is currently available, apart from HLA typing within the family of a patient with confirmed HFE. During a reverse genetic approach to identify the gene, we found three anonymous genomic probes (P3, P5, and I.82) derived from previously cloned YACs and physically mapped in the HLA class I region. P3 and P5 probes recognise 3 loci (P3A, P3B, P5) and I.82 one locus about 100 kb from HLA-A. Using five biallelic polymorphisms (I.82/BglII, P3B/EcoRV, P3B/PstI, P5/HindIII, P3A/PstI), we tested 198 HLA typed subjects from the families of 22 haemochromatosis patients. The information from the five polymorphisms was sufficient to identify unequivocally extended restriction haplotypes in all families. The restriction haplotypes cosegregate with the HFE allele and enable identification of genotypically identical sibs in all families studied. The linked DNA markers described in this article avoid the disadvantages of HLA serological typing and can be used in genetic counselling of HFE families.

DNA↗
PubMed1991

Polymorphism in a ferritin H gene from chromosome 6p.

This paper addresses the question of whether abnormalities in ferritin expression in the iron storage disease hemochromatosis (HC) involve major deletions or alterations in regions containing the two ferritin H genes that lie near the disease locus on chromosome 6p. We present evidence from analyses of Southern blots that neither gene is deleted in hemochromatosis. We also describe a polymorphism in one of the genes that we have previously shown to be a processed pseudogene. This polymorphism does not correlate with the presence of HC. The PIC value for this polymorphism was calculated as 0.49.

Blotting, Southern↗
PubMed1991

Proliferation of resting lymphocytes is induced by triggering T cells through an epitope common to the three CD18/CD11 leukocyte adhesion molecules.

LFA-1, Mac-1, and p150,95 are a family of functionally important leucocyte integrins that share a common beta-subunit and participate in cellular adhesion. Monoclonal antibody to LFA-1 were described to block T-cell-mediated killing by inhibiting adhesion to target cells and to decrease T cell responses by preventing cell-cell contact. Recently it was demonstrated that LFA-1 molecule was involved in signal transduction. We report here that a monoclonal antibody termed 6.7 reacting with the three members of the leucocyte integrins is able in the presence of monocytes to directly induce the proliferation of resting peripheral blood T cells obtained from normal individuals. These results suggest the possibility that LFA-1 molecules could trigger T lymphocyte activation in addition to their role in homing, growth, and differentiation.

Antibodies, Monoclonal↗
PubMed1991

Differential effects of naloxone on approach and escape responses induced by electrical stimulation of the lateral hypothalamus or the mesencephalic central gray area in mice.

BALB/c mice implanted with a bipolar electrode were trained in a shuttle-box to initiate and to terminate a continuous electrical stimulation applied in the lateral hypothalamus (LH) or in the mesencephalic central gray area (CG). Following stabilization of the baseline response latencies, the subjects were subcutaneously injected with isotonic NaCl or with naloxone HCl (0.5, 2 or 10 mg/kg) 15 min or 45 min before a test session. In LH-stimulated animals no modification of the behavioral responses was observed after injection of 0.5 mg/kg of naloxone. The 2 mg/kg dose increased the value of escape latency (ON time) but had no effect on approach latency (OFF time). The 10 mg/kg dose also increased ON time. At this dose, an increase of OFF time was simultaneously observed but only 15 min after the injection. In CG-stimulated mice an increase of OFF time and a reduction of ON time were recorded 15 min after the injection of 0.5 mg/kg. Only the reduction of ON time was detected for the 45-min delay. The 2 mg and 10 mg/kg doses simultaneously increased OFF time and reduced ON time for the two delays. These results demonstrate 1) that the effects of naloxone on self-stimulation varied as a function of the structure considered 2) that the predominant characteristic of the considered structure (essentially "rewarding" as the LH or "aversive" as the CG) governs the modulations induced by naloxone.

Animals↗
PubMed1991

Short-term prednisolone followed by recombinant human alpha-interferon alone or combined with adenine-arabinoside in chronic hepatitis B. A prospective and randomized trial.

Twenty-nine patients with chronic hepatitis B, presenting both hepatitis B surface antigen and hepatitis B virus deoxyribonucleic acid in serum, were studied in a randomized trial treatment consisting of oral prednisolone for 28 days followed 14 days after steroid withdrawal, by either a 55 s.c. injection course of 5 M unit recombinant human alpha-interferon (group 1, 14 patients) or by adenine-arabinoside (for 21 days) combined from the fourteenth day on with the same 55 s.c. injection schedule of interferon (IFN) (group 2, 15 cases). The two groups were well matched with respect to demographic, biochemical, virological and histologic features. Significant side-effects leading to premature discontinuation of interferon were observed in only four cases in group 2 and were always reversible. Efficacy was judged on a mean follow-up period of 17 months. For the whole population, 17 patients (59%) exhibited a sustained serum hepatitis B virus deoxyribonucleic acid disappearance which corresponded to a marked improvement in liver function as demonstrated by a quasi-normalization of their serum transaminase values (ALT with n less than 22 UI/l: 23 +/- 24 vs. 139 +/- 115 before treatment; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Pulmonary arteriovenous fistula].

A case of pulmonary arteriovenous fistula in a 6 1/2 year-old girl is reported. The fistula which was first seen on X-ray films resulted in low arterial oxygen saturation, asthenia and dyspnea during exercise. It was confirmed by right catheterism and angiography. The child was cured after left inferior lobectomy. No other vascular malformations could be demonstrated in the child or in her family. Literature data are reviewed.

Arteriovenous Fistula↗
PubMed1990

Identification of a novel 110-kilodalton structure expressed on a subset of T cell receptor-gamma delta-bearing cloned lymphocytes.

A small percentage of circulating CD3+ cells express a heterodimeric gamma delta receptor. Most of these cells do not express the surface marker CD4 and only a fraction of them bear CD8 molecules. The specificity and function of TCR-gamma delta are unclear. We obtained a murine mAb produced against an IL-2-dependent human T cell clone defining a novel molecule sTA which is not expressed on resting human peripheral blood CD3+ cells but strongly expressed on a fraction of TCR-gamma delta-bearing clones. Like receptors for growth factors such as IL-2, the sTA Ag is present on clones and cell lines according on the cell cycle. SDS-PAGE analysis of sTA immunoprecipitates from 125I-labeled sTA+ clone lysate demonstrated a single band of molecular mass 110 kDa under reducing conditions. Triggering with anti-sTA mAb did not result in [Ca2+]i mobilization of sTA+ clones. Additionally, the presence of anti-sTA did not alter the cytotoxicity of these sTA+ clones neither against tumor target cells nor against specific PHA blast cells. Interestingly, due to the fact that most sTA+ clones fail to proliferate in response to CD3 triggering, it appears that sTA may serve as a useful marker to study the functional heterogeneity of TCR-gamma delta expressing cells.

Antibodies, Monoclonal↗
PubMed1990

HLA class I gene polymorphism in genetic hemochromatosis.

The authors have studied HLA class I polymorphism in an attempt to identify a genomic marker of the hemochromatosis gene. Five enzymes were used (HindIII, EcoRI, EcoRV, PvuII, and HincII) in 47-106 unrelated patients and 71-91 controls. Both populations were HLA-typed. The relationship between the restriction fragments and HLA-A antigens was considered. Comparison of the two groups revealed a significantly high frequency of one 14 kb EcoRI fragment among the HLA-A3 hemochromatosis patients. The fragment hybridizes to an HLA-A specific probe but not to an HLA-B specific probe, and is associated with the hemochromatosis gene, which is itself associated with HLA-A3.

HLA Antigens↗
PubMed1989

Ferritin H gene polymorphism in idiopathic hemochromatosis.

The authors studied the H ferritin restriction polymorphism in 83 hemochromatosis patients and 84 controls as well as in 19 nuclear families. No significant difference was found with the ten restriction enzymes used (HindIII, EcoRI, EcoRV, PvuII, BamHI, PstI, Bg/I, Bg/II, HincII, and TaqI). Hence, the genomic abnormality responsible for idiopathic hemochromatosis is not a major deletion of an H ferritin gene. A higher frequency of one HindIII fragment, although nonsignificant when the number of comparisons made is taken into account, was observed in the patients. This HindIII fragment hybridizes with the H ferritin probe and with a 28 S ribosomal probe, and its segregation with HLA haplotypes (hence its assignment to chromosome 6) is uncertain. Its possible meaning in the expression of the disease is discussed.

Chromosome Mapping↗