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M Houde

Publications and source records attributed to M Houde.

At least 37 records · Page 2Linked to original sources
PubMed1990

Localization of vitamin B12 binding in Euglena gracilis.

Different fractionation procedures were used to determine the location of vitamin B12 binding sites in Euglena gracilis. Using uptake measurements, cell fractionation, and light and electron microscopy, the cuticle of the cell was found to be the fraction containing the majority of B12 binding sites. The apparent distribution of vitamin binding sites differed according to the cell lysis method used. The cuticle fraction was responsible for the binding of 80% of the vitamin taken up by the cell during both the rapid and the slow phase of uptake. These results suggest that vitamin B12 binding is regulated, in part, at the cuticle level, and support our previous conclusion that the secondary phase of uptake represents the synthesis of new receptor sites and not the unloading of vitamin inside the cell.

Animals↗
PubMed1989

Divergence of the nucleotide sequences encoding xanthine dehydrogenase in Calliphora vicina and Drosophila melanogaster.

We present here two nucleotide sequences, from two different alleles encoding xanthine dehydrogenase in Calliphora vicina. One sequence covers the first exon with 1529 bp upstream from the initial ATG and 1737 bp downstream from the donor end of the first intron. The other sequence starts 2537 bp upstream from the acceptor site of the first intron, and ends 662 bp downstream from the putative polyadenylation site of the transcript. Comparison with the homologous gene from Drosophila melanogaster (rosy) reveals extensive divergence, with differences in the splicing patterns and no detectable homology between introns or flanking regions. Nevertheless, there is 76% identity between the amino acid (aa) sequences. The pattern of aa differences has been analysed and correlated with predicted three-dimensional (3-D) parameters. These studies consistently suggest that the evolution of the protein was strongly biased for conservation of its 3-D structure. Possible functional significance of the aa changes is discussed.

Amino Acid Sequence↗
PubMed1989

Proportions of H1 histone subspecies in human fibroblasts shift during density-dependent growth arrest independent of replicative senescence.

H1 histone subspecies have been reported to vary during tissue differentiation, during aging of mammalian tissues, and as a function of DNA replicative activity. Since cultured human fibroblasts have a limited replicative life span which features arrest in the G1 phase of the cell cycle, we sought to distinguish whether any changes in the proportions of the principal H1 histone subspecies (H1A, H1B, and H1o) in late-passage fibroblasts were specific for senescent loss of replicative potential, or rather ensued as a result of prolonged inhibition of cell division. We observed an identical shift in the proportions of H1 histone subspecies during prolonged density-dependent inhibition of growth in both early-passage and late-passage cells. Since under these conditions there were no passage-specific changes, replicative senescence of human fibroblasts does not appear to involve a defect in the control of H1 histone proportions.

Cell Cycle↗
PubMed1989

Human influenza virus neuraminidase, but not hemagglutinin, induces murine macrophage interleukin 1 in vivo and in vitro.

Since our previous studies showed that the viral glycoproteins of influenza virus, hemagglutinin (HA) and neuraminidase (NA), are involved in stimulating the human and mouse natural killer (NK) cell activities, it was considered appropriate to study the effect of these glycoproteins on macrophages, another component of nonspecific resistance mechanisms. The glycoproteins HA and NA, of the strain A/USSR/90/77 (H1N1), were purified electrophoretically and were tested in vitro using the adherent peritoneal macrophages of C3H/HeN mice elicited with thioglycolate. IL-1 activity of culture supernatants, collected 24 h after the addition of viral proteins, was evaluated by the standard IL-1 assay using C3H/HeJ thymocytes. Viral NA, but not HA, induced a significant increase of IL-1 activity (p less than 0.05) at dilutions ranging from 1:2 (about thirty-fold augmentation) to 1:256 (nine-fold augmentation) compared to control. The in vivo data showed that intraperitoneal administration of either glycoprotein (2 micrograms) alone did not increase the IL-1 activity; but a six-fold increase (p less than 0.05) of IL-1 activity was observed when the adherent macrophages prepared from NA-primed mice (24 h and 96 h postinoculation) were restimulated in vitro with NA. Similar experiments carried out with HA showed no increase in the IL-1 activity. These and other results suggest that influenza virus NA is superior to HA in stimulating some components of the nonspecific resistance mechanisms.

Animals↗
PubMed1988

Purified glycoproteins of influenza virus stimulate cell-mediated cytotoxicity in vivo.

Previously, we reported that purified surface influenza viral glycoproteins can induce cell-mediated cytotoxicity (CMC) in vitro. Both neuraminidase (NA) and hemagglutinin (HA) were equally good stimulators, on an equimolar basis. In order to broaden the scope of these observations, we examined whether these glycoproteins stimulate natural killer (NK) activity in vivo. Biologically active preparations of glycoproteins NA and HA were purified from virus A/USSR/90/77 (H1N1) and recombinant virus A/USSR/92/77 (H1) x A/Prague/1/56 (N7), respectively. The studies were carried out using the optimal doses of NA and HA. In a 4-hour NK assay, using NK-sensitive YAC-1 cells as targets, both viral glycoproteins stimulated the NK activity of splenocytes of BALB/c and C3H mice. This stimulation was independent of the route of administration (intravenous or intraperitoneal) of the antigen. The observed NK activity was viral antigen-specific and could be modulated to levels comparable to those observed with the standard stimulator, polyinosinic acid-polycytidylic acid, by the use of an appropriate synthetic adjuvant, stearyl tyrosinate. Direct and indirect evidences suggest that the enhanced CMC is due to NK cells. These observations imply that enhancement of NK activity is the intrinsic property of influenza NA and HA.

Adjuvants, Immunologic↗
PubMed1987

Cloning and partial characterization of the xanthine dehydrogenase gene of Calliphora vicina, a distant relative of Drosophila melanogaster.

In vitro enzymatic assays have shown that an enzyme with typical xanthine dehydrogenase (XDH) activities and electrophoretic mobility slightly different from that of Drosophila XDH is present in Calliphora tissues. A Calliphora genomic sequence has been isolated by low-stringency hybridization to the Drosophila rosy gene (XDH), and partially sequenced. This sequence has been shown to be unique, polymorphic, and it maps on chromosome I. Sequence comparisons provide compelling evidence that it belongs to the XDH gene of Calliphora. Interspecies transformation experiments, aimed at investigating functional as well as structural divergence of the XDH genes of Calliphora and Drosophila, are now possible.

Amino Acid Sequence↗
PubMed1986

Renal cell carcinoma presenting as multilocular cystic mass.

We report a case of a multilocular cystic mass that was erroneously labeled multilocular cystic nephroma at ultrasound and computerized tomography, thus leading to a partial nephrectomy; however the final histologic diagnosis was a multilocular cystic renal cell carcinoma. Only 1 similar case has been reported previously. The radiologic and surgical implications are discussed.

Carcinoma, Renal Cell↗
PubMed1984

In vitro enhancement of human natural cell-mediated cytotoxicity by purified influenza virus glycoproteins.

The role of the glycoproteins of influenza virus, hemagglutinin (HA), and neuraminidase (NA) in the in vitro stimulation of natural cell-mediated cytotoxicity (NCMC) or natural killer activity of human peripheral blood lymphocytes was evaluated with radiolabeled K562 cells as target cells in an overnight chromium release assay. Three different approaches were used. (i) Purified viral proteins were obtained by extraction with Nonidet P-40, separation on a sucrose gradient, and further purification by affinity chromatography. Ficoll-Hypaque-purified peripheral blood lymphocytes exposed to HA or NA individually or to a mixture of both significantly increased NCMC (32 to 50%). (ii) Treatment of HA and NA with their respective homologous antisera or F(ab')2 antibody abrogated the stimulation of NCMC by these glycoproteins. (iii) Virions treated with proteolytic enzymes resulted in viral cores lacking either HA or NA or both activities. Compared to whole virions, viral cores devoid of HA activity only induced a 50% increase in NCMC, whereas viral cores lacking HA activity and with traces of NA activity stimulated only 10% of the NCMC. These results suggest that influenza virus-induced cell-mediated cytotoxicity is largely due to its glycoproteins.

Antibodies, Viral↗
PubMed1983

Nephrogenic adenoma of the bladder after kidney transplantation: spontaneous improvement with azathioprine removal; surgical trauma and cytomegalovirus infection as possible etiologic factors.

We report 2 cases of nephrogenic adenoma several years after successful cadaver kidney transplantation. In 1 case the lesion had cytomegalovirus inclusions, and we observed a marked and sustained reduction in the extension of the lesion with cessation of azathioprine. Surgical trauma and cytomegalovirus infections are discussed as etiologic factors. Conservative treatment seemed appropriate.

Adenoma↗