HLA Antigens in 16 Families with Xeroderma Pigmentosum

Xeroderma pigmentosum is an autosomal recessive disease. HLA-A and -B typing was performed on peripheral blood lymphocytes and platelets. Sixteen Tunisian families were typed with 37 patients and 108 relatives. Genetic transmission of the disease and of the HLA system seemed to be independent in this study. Comparison of HLA gene frequencies between (unrelated) parents of patients and a control population showed no difference, proving that there is no clear association in populations between deleterious XP genes and a particular HLA gene. However, an excess of identical HLA among pairs of diseased siblings would suggest that the disease is polymorphic and a form of the XP could be linked to HLA.     

The role of accessory cells and T cell-growth factor in induction of cytotoxic T lymphocytes against herpes simplex virus antigens.

The roles of accessory cells and T cell-growth factor (TCGF) in the in vivo induction of herpes simplex type 1 (HSV) specific cytotoxic lymphocytes (CTL) were evaluated. Spleen cells from animals infected with HSV 4-6 weeks previously were depleted of adherent cells by passage over Sephadex G10. Unlike intact cells, such depleted spleen cells failed to respond by producing H-2 restricted virus-specific CTL upon culture for 5 days with infectious HSV. The CTL response could be restored either by adding normal genetically compatible peritoneal cells as accessory cells or by the addition of TCGF. To obtain optimum restoration accessory cells needed to be added soon after culture initiation but with TCGF addition, partial restoration was evident when added as late as 72 hr after culture. TCGF also permitted intact spleen cells to respond to heat-inactivated virus. The results are interpreted to indicate that accessory cells are essentially required for the presentation of virus to specific helper cells with such cells responding by the production of TCGF. The results also indicate that certain forms of virus may trigger the response of CTL precursors but not the response of helper cells.     

Inhibition of the insulin receptor kinase phosphorylation by nitric oxide: functional and structural aspects

Previous studies on cultured skeletal muscle cells have indicated that the insulin-induced expression of GLUT4 transporter protein is inhibited by nitric oxide (NO). Therefore, we determined the effect of NO on the insulin-induced autophosphorylation of the insulin receptor kinase (IRK), i.e., the first step in the insulin-mediated signal transduction pathway. The experiments showed that the insulin-induced autophosphorylation of the insulin receptor beta-chain is strongly inhibited by the NO donors 1,1-diethyl-2-hydroxy-2-nitrosohydrazine (DEA-NO) or S-nitroso-N-acetylpenicillamine (SNAP). The inhibitory effect was ameliorated in cells depleted of glutathione (GSH), suggesting the possibility that S-nitroso-glutathione may operate as an intermediate NO donor. Complementary experiments with different Cys --> Ala mutant proteins showed, surprisingly, that all mutant proteins were inhibited by DEA-NO. Three-dimensional models of the nonphosphorylated IR beta-chain nitrosylated at the accessible cysteine residues 1056, 1138, 1234, or 1245 revealed that derivatization of any of these four cysteine residues leads essentially to the same structural changes of the IRK domain. These changes involve a movement of the amino-terminal lobe against the carboxy-terminal lobe in a direction opposite to the direction of the "lobe closure" that was previously proposed to facilitate the accessibility for ATP and the expression of catalytic activity. Our findings suggest that the occurrence of several functionally relevant cysteine residues in distinct regions of the IRK protein increases the probability of regulatory redox interactions and thus the redox sensitivity of the IRK.     

Frequency and spectrum of p53 mutations in gastric cancer — a molecular genetic and immunohistochemical study

The p53 tumour-suppressor gene plays an important role in gastric carcinogenesis. In an analysis of the spectrum of mutations of the p53 gene seen in 56 primary gastric carcinomas of various types and grades of differentiation, the entire coding sequence (exons 2–11) of the p53 gene was screened by single-strand conformation polymorphism analysis and direct genomic sequencing of polymerase chain reaction products. Intragenic restriction site polymorphisms and the probe YNZ22 were used for the detection of loss of heterozygosity (LOH) of the p53 gene locus on chromosome 17p. p53 overexpression was studied with the anti-p53 antibody CM-1. A total of 21 somatic alterations of the p53 gene were found. Twenty were base-pair substitutions, and one was an eight base-pair deletion. Six tumours with p53 mutations revealed LOH. Abnormalities in p53 expression were found in 17 tumour samples, of which 16 had gene mutations. The spectrum of mutations observed was consistent with the predicted spectrum for dietary mutagens associated with the metabolism of nitrogenous compounds, resulting in deamination of nucleic acids. Our findings suggest that p53 could be a primary target for mutations associated with dietary carcinogens in gastric carcinogenesis.     

The sensitivity of posturographic parameters to acquisition settings

The objective of this study was to evaluate the sensitivity of posturographic parameters (PP) to changes in acquisition settings. A group of eight young adults underwent a set of typical orthostatic posture trials, and selected PP were then calculated from a set of centre of pressure (CoP) displacement time series obtained by applying different cut-off frequencies to the same set of raw data. Four PP out of 11 showed significant changes with respect to cut-off frequency. Statistical mechanics parameters exhibited smaller sensitivity than summary measures. On the basis of the results obtained, a proposal for a standard cut-off frequency and a sampling rate value is embodied in the paper together with some suggestions on measurement settings, with a view to standardized use of instrumentation for quantitative analysis in orthostatic posturography.     

Expression of B-cell antigens by Hodgkin''s and Reed-Sternberg cells.

Twenty frozen and 55 paraffin sections of lymphnode specimens from 55 patients with pretreatment Hodgkin's disease (nodular sclerosis Hodgkin's disease, n = 45; mixed cellularity Hodgkin's disease, n = 10) were studied by immunohistochemistry and molecular analysis to determine the phenotype of Hodgkin's and Reed-Sternberg cells (HRS). In all cases the HRS cells were CD45-, and CD30+, and in 43/55 (78%) cases they were CD15+. In 48/55 cases (87%) HRS cells were reactive with at least one B-cell marker (CD19, CD20, CD22, CDw75, MB2), 8/55 cases (14.5%) showed reactivity (mainly cytoplasmic) of a subpopulation of HRS cells with the T-cell markers CD3 and beta F1. All cases that expressed T-cell antigens were also reactive with at least one B-cell marker. In frozen sections, a minority of HRS cells in each case studied showed cytoplasmic positivity for bcl-2 protein. Rearrangement of immunoglobulin heavy chain genes was detected in one case and of T-cell receptor beta chain genes in none. The authors were unable to confirm previous reports of bcl-2 gene rearrangement in Hodgkin's disease. The results strongly support a B lymphocytic origin of HRS cells.     

Allergologic exploration of germins and germin-like proteins,a new class of plant allergens

BACKGROUND: Germins and the related germin-like proteins (GLPs) are glycoproteins expressed in many plants in response to biotic and abiotic stress. To test the potential impact of germins and GLPs, recombinant germin from Triticum aestivum (tGermin) and GLPs from Arabidopsis thaliana (tGLP), both produced in transformed tobacco plants, were used. METHODS: Sera from 82 patients with type I allergy to birch, grass or mugwort pollen and/or wheat were tested in immunoblot for IgE binding to tGermin and tGLP, and the IgE reactivity after chemical and enzymatic deglycosylation was analysed. The biological activity of tGermin and tGLP was determined in a histamine release assay and in skin prick testing (SPT). RESULTS: In an immunoblotting assay, 24 out of 82 tested sera (29.26%) from allergic patients showed IgE-binding to tGermin, and 18 of these sera (21.95%) displayed also IgE-binding to tGLP. The deglycosylation experiments indicated that glycan moieties contribute significantly to the IgE-binding of tGermin and tGLP. Both tGermins and tGLP induced specifically histamine release in an in vitro assay as well as in SPT. CONCLUSION: Our in vitro and in vivo findings demonstrate that germin and GLPs are capable to bind IgE most likely via carbohydrate determinants, and represent allergenic molecules.