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Biomedical subjects

M Houde

Publications and source records attributed to M Houde.

At least 19 recordsLinked to original sources
PubMed1992

A molecular marker to select for freezing tolerance in Gramineae.

We isolated, and expressed in Escherichia coli, a gene (Wcs120) that is strongly induced during cold acclimation of wheat. The gene product was purified and used to produce antibodies. Immunoblotting experiments with the anti-WCS120 antibody identified several cold-induced proteins named FTMs for Freezing Tolerance Markers since they are associated with the development of freezing tolerance. This protein family was found to be coordinately regulated specifically by low temperature, highly hydrophilic, stable to boiling, and to have a pI above 6.5. The accumulation kinetics during the acclimation period indicated a positive correlation with the capacity of each genotype to develop freezing tolerance. Accumulation of the proteins was higher in the freezing-tolerant genotype than in the less tolerant one. In addition, their accumulation was more pronounced in the crown and leaf tissues compared with roots, confirming a relationship to the capacity of the different tissues to develop freezing tolerance. Analysis of different species (eight monocots and four dicots) indicated that this protein family is specific for freezing-tolerant cereals. The antibody did not cross-react with any of the non-cereal species examined. The anti-FTMs antibody represents a potential tool for breeders to select for freezing tolerance traits in the Gramineae.

Adaptation, Physiological↗
PubMed1992

Peritonitis in continuous ambulatory peritoneal dialysis: impact of a compulsory switch from a standard to a Y-connector system in a single North American Center.

One hundred one continuous ambulatory peritoneal dialysis (CAPD) patients from a single North American center were analyzed in a retrospective and cross-over study for peritonitis rates using a standard system (Travenol System II) or a Y-shaped disconnect-disinfectant system (Travenol O-set). Twenty-one of 34 patients using the standard set (group I) had 53 episodes of peritonitis in 508 patient-months or one episode per 9.6 patient-months. Nine of 17 patients switching from the standard to the disconnect-disinfectant system (group II) experienced 22 episodes of peritonitis in 275 patient-months or one episode per 12.5 patient-months on the standard set, while six patients had 10 episodes of peritonitis in 275 patient-months or one episode per 27.5 patient-months on the disconnect-disinfectant system (P less than 0.04). Twenty-eight of 67 new CAPD patients starting on the disconnect-disinfectant system (group III) had 37 episodes of peritonitis in 1,086 patient-months or one episode per 29.4 patient-months (P less than 0.01 v group I). Exit-site infections (ESI) occurred in 35.3% of patients using the standard set versus 34.3% of those using the O-set. The presence of an ESI was not associated with a higher risk of peritonitis, but modified the bacteriological profile of subsequent peritonitis episodes in patients using the O-set, favoring the organisms isolated from the exit site. Decreases in peritonitis rates with the O-set were due to a reduction of peritonitis episodes secondary to most bacterial agents and not only to skin organisms. Diabetics using intraperitoneal insulin had similar peritonitis and ESI rates as nondiabetics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Modulation of murine macrophage responses stimulated with influenza glycoproteins.

Previously it was reported that influenza virus stimulated, nonspecific resistance was largely due to its glycoproteins, hemagglutinin (HA) and neuraminidase (NA). The enhancement of natural killer cell activity was the intrinsic property of NA and HA. In the present study, the stimulatory effect of these glycoproteins on the murine peritoneal macrophages was studied. Electrophoretically purified glycoproteins, NA and HA, of influenza virus A/USSR/90/77 (H1N1) were administered intraperitoneally to C3H/HeN mice, with or without stearyl tyrosine (ST). Macrophages were isolated and were restimulated with phorbol myristate acetate. H2O2 secretion was determined by horseradish peroxidase dependent oxidation of phenol red assay. HA enhanced H2O2 secretion only in the presence of ST (60 nmol.mg-1.h-1), whereas NA alone stimulated H2O2 secretion (83 nmol.mg-1.h-1), by 6-fold over control (13 nmol.mg-1.h-1), and this stimulation was further increased (136 nmol.mg-1.h-1) in the presence of ST. Interleukin 1 (IL-1) activity was determined by using D10.G4.1 cells. There was a little stimulation of IL-1 activity (less than 1 U/mL) of macrophages isolated from HA-primed of HA+ST-primed mice restimulated with HA. On the other hand, IL-1 activity of macrophages isolated from NA-primed mice restimulated with NA significantly increased (102 U/mL) over control (less than 1 U/mL), and an additional 2-fold increase (231 U/mL) resulted when macrophages from NA+ST-primed mice were used. Tumor necrosis factor (TNF) activity was examined by using L929 cells. Negligible TNF activity was observed in macrophages isolated from either HA-primed or HA+ST-primed mice restimulated with HA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1991

Inter-species complementation of a rosy deficiency in Drosophila melanogaster.

A chimeric Xdh gene was constructed in vitro, by recombining DNA sequences from the Dipterans Drosophila melanogaster and Calliphora vicina. The ry506 strain, an eye-colour mutant of Drosophila that is deficient for Xdh, was genetically transformed with the recombinant gene. Transformed flies with ry+ eye phenotype and increased resistance to purine were obtained, showing that the chimeric XDH is physiologically active in Drosophila. XDH activity was detected in crude extracts from transformed flies, yet at lower levels than in wild-type controls. The amounts of Xdh transcripts in the transformants were found to be 8 to 16% of the amount of wild-type ry mRNA, suggesting that Calliphora Xdh sequences may be relatively inefficient for mRNA production in Drosophila, or may produce unstable mRNA.

Animals↗
PubMed1991

Treatment of mild-to-moderate hypertension: comparison between a calcium-channel blocker and a potassium-sparing diuretic.

In a multicenter study, 61 patients, 18-70 years of age, with mild-to-moderate hypertension [diastolic blood pressure (DBP) 95/114] completed a 28-week treatment. After initial placebo washout, patients were randomly allocated either to diltiazem or hydrochlorothiazide/triamterene. At the end of 12 weeks, the patients continued on the same medication if their goal blood pressure achieved (DBP less than 90; or 10 mm Hg below baseline). If not, the alternate agent was added (either diltiazem + hydrochlorothiazide/triamterene or hydrochlorothiazide/triamterene + diltiazem). At the end of 28 weeks, the intent-to-treat analysis showed that 90% on diltiazem alone, 73.7% on hydrochlorothiazide/triamterene alone, 71.4% on (diltiazem + hydrochlorothiazide/triamterene), and 57.1% on (hydrochlorothiazide/triamterene + diltiazem) achieved goal BP. End point mean values of BP and heart rate after adjusting for sex, baseline values, age, and weight showed no significant difference between groups. Forty-six percent on hydrochlorothiazide/triamterene alone and 24% on diltiazem alone reported one or more adverse events, possibly related to study medication. Patients with diltiazem as the first choice had better BP control than those on hydrochlorothiazide/triamterene alone (81.5% vs. 69.7%). Furthermore, among non-goal achievers at week 12, there was a greater response in the group when hydrochlorothiazide/triamterene was added to diltiazem than when diltiazem was added to hydrochlorothiazide/triamterene. This study suggests that in mild-to-moderate hypertension, diltiazem is better than hydrochlorothiazide/triamterene as first line therapy.

Adolescent↗
PubMed1990

Alpha 1 beta 1 integrin heterodimer functions as a dual laminin/collagen receptor in neural cells.

A monoclonal antibody (3A3) raised against a rat neural cell line (PC12) was shown previously to bind to the surfaces of these cells, inhibiting substratum adhesion. Immunochemical and other data indicated that the heterodimer recognized by 3A3 was a member of the integrin family of adhesive receptors and had a beta 1 subunit. The relationship of the alpha subunit to other integrins was unknown. Here we show that 3A3 recognizes in rat tissues a heterodimer (approximately 185 kDa, approximately 110 kDa; unreduced) that is electrophoretically and immunochemically indistinguishable from the antigen in PC12 cells. Immunoaffinity purification of the heterodimer from neonatal rats and protein microsequencing indicate that the alpha subunit is identical at 11 or 13 N-terminal residues with VLA-1, an integrin on human hematopoietic cells. Monoclonal antibody 3A3 inhibits the attachment of rat astrocytes to laminin or collagen but not to fibronectin or polylysine. These data suggest strongly that the integrin recognized by 3A3 is the rat homologue of VLA-1, i.e., alpha 1 beta 1, and that alpha 1 beta 1 is a dual laminin/collagen receptor.

Amino Acid Sequence↗
PubMed1990

Stimulation of tumor necrosis factor secretion by purified influenza virus neuraminidase.

We showed that purified neuraminidase (NA) of influenza virus, but not hemagglutinin (HA), possessed the potential to increase in vitro and in vivo the interleukin 1 (IL 1) activity of mouse peritoneal macrophages. In this study, we report the effect of NA and HA on the secretion of tumor necrosis factor (TNF) activity by murine peritoneal macrophages. TNF being a cytokine sharing many related and overlapping biological functions with IL 1. The two glycoproteins of the strain A/USSR/90/77 (H1N1) were purified electrophoretically and were tested in vitro at doses ranging from 0.5 to 5.0 micrograms using the adherent peritoneal macrophages of C3H/HeN mice elicited with thioglycolate. The TNF activity of culture supernatants, collected 24 hr after stimulation with viral protein, was evaluated by the standard cytolytic assay using L929 and WEHI.164 cells. No increase of the TNF activity was observed at 0.5 micrograms of NA (4.8 Units (U)/ml in the L929 assay and 20.4 U/ml in the WEHI assay) but further increase of NA to 1.0 microgram had a significant effect on the TNF activity (39.7 and 88.8 U/ml, respectively). Higher concentrations of NA (2.0 and 5.0 micrograms) did not improve the TNF activity. The addition of a rabbit anti-TNF-alpha serum to the assay system reduced the lysis of L929 cells by 85%, suggesting that the observed activity was due to TNF. In parallel, the enhancement of IL 1 activity due to NA was reverified using D10.G4.1 cells instead of the C3H/HeJ thymocytes assay used previously. NA augmented the IL 1 activity up to 1.0 micrograms (25.8 U/ml). The addition of monoclonal anti-IL 1 antibodies (100 neutralizing units) to the supernatants reduced the incorporation of [3H]-thymidine by 90 to 95%, suggesting that the observed activity was due to IL 1. Comparative results of NA and HA showed that only NA stimulated the TNF and IL 1 activities of murine macrophages.

Animals↗
PubMed1990

Molecular cloning of the rat integrin alpha 1-subunit: a receptor for laminin and collagen.

Integrin heterodimers mediate a variety of adhesive interactions, including neuronal attachment to and process outgrowth on laminin. We report here the cloning and primary sequence of an M-200 kD integrin alpha subunit that associates with the integrin beta 1 subunit to form a receptor for both laminin and collagen. Similarities in ligand-binding specificity, relative molecular mass and NH2-terminal sequence make this a strong candidate for the rat homologue of the alpha subunit of the human integrin VLA-1. The full-length rat alpha 1 cDNAs encode a protein containing a purative signal sequence and a mature polypeptide of 1,152 amino acids, with extracellular, transmembrane and cytoplasmic domains. Several structural features are conserved with other integrin alpha chains, including (a) a sequence motif repeated seven times in the NH2-terminal half; (b) potential Ca2+/Mg2+ binding sites in repeats 5, 6, and 7, and (c) alignment of at least 14 of 23 cysteine residues. This rat alpha 1 sequence also contains a 206-amino acid I domain, inserted between repeats 2 and 3, that is homologous to I domains found in the same position in the alpha subunits of several integrins (VLA-2, Mac-1, LFA-1, p150). The rat alpha 1 and human VLA-2 apha subunits share greater than 50% sequence identity in the seven repeats and I domain, suggesting that these sequence identities may underlie some of their similar ligand-binding specificities. However, the rat integrin alpha 1 subunit has several unique features, including a 38-residue insert between two Ca2+/Mg2+ binding domains, and a divergent 15-residue cytoplasmic sequence, that may potentially account for unique functions of this integrin.

Adrenal Gland Neoplasms↗
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↗
PubMed1977

[The renin-angiotensin-aldosterone system in hypertensive patients. II. Diagnosis of primary hyperaldosteronism].

Twenty patients suffering from primary hyperaldosteronism were studied. Sixteen had a single adenoma of the adrenal and four had bilateral hyperplasia affecting both adrenals. Cases of primary hyperaldosteronism due to a tumour were characterised by a higher degree of hypermineralocorticism than was seen in the patients with hyperplasia. Plasma aldosterone, after acute volaemic expansion, did not fall below 13 ng/100 ml in the adenoma patients whilst it was lower in the case of hyperplasia. Adrenal phlebography is a useful tool in preoperative diagnosis.

Adenoma↗