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Biomedical subjects

L Bernier

Publications and source records attributed to L Bernier.

At least 37 records · Page 2Linked to original sources
PubMed1996

Identification of numerous hepatitis C virus genotypes in Montreal, Canada.

Hepatitis C virus genotypes were determined for 358 viremic individuals in Montreal, Canada, by restriction endonuclease analysis of PCR products and phylogenetic analysis of core gene sequences. Types 1, 2, and 3 occurred in 62.8, 14.2, and 13.7%, respectively; types 4 and 5 were found in 3.9 and 4.5%, respectively; and genotypes 6a and 7c and a novel genotype each occurred in 0.3%. Types 4, 6, and 7 and the novel genotype were mostly from persons who had immigrated to Canada.

Adult↗
PubMed1995

Inheritance of chromosome-length polymorphisms in Ophiostoma ulmi (sensu lato).

We have investigated the mitotic and meiotic transmission of chromosome-length polymorphisms in Ophiostoma ulmi s.l., the causal agent of Dutch elm disease. The North-American aggressive (NAN) strain CESS16K has an atypical electrophoretic karyotype, carrying two chromosome-sized DNAs (chDNAs) that have not been observed in other members of the NAN biotype. Independent CESS16K chDNA preparations, even after repeated inoculation and recovery from the elm host, and analysis of 16 progeny strains after a cross between the NAN strains FG245Br-O and CESS16K, demonstrated that these unique chDNAs are integral components of the CESS16K genome. Analysis of the progeny, by electrophoretic karyotyping and hybridizations with probes specific to individual chDNAs, presented evidence that genome rearrangements can occur as a consequence of meiosis. Even though novel electrophoretic karyotypes and a novel-sized chromosome were observed in the karyotypes of the progeny strains, the low level of reassortment between the chromosomes carrying length polymorphisms presented evidence that there are constraints to genome plasticity for this fungus.

Ascomycota↗
PubMed1994

Biochemical mapping of neurofibrillary degeneration in a case of progressive supranuclear palsy: evidence for general cortical involvement.

A biochemical study was performed to quantify and map the neurodegenerating process in cortical and subcortical brain areas from a case of progressive supranuclear palsy (PSP). Our approach was based on a Western blot analysis of pathological Tau proteins, which are the basic components of neurofibrillary lesions. We found that: (i) the abnormal Tau proteins can be detected in all cortical areas, sometimes in larger amounts than in some subcortical areas; (ii) these abnormal Tau proteins consist of a doublet called Tau 64 and 69, except for in the entorhinal cortex where we detected, as for Alzheimer brains, the triplet of Tau proteins called Tau 55, 64 and 69; (iii) the amounts of abnormal Tau proteins were higher in some neocortical regions, especially in the frontal lobe, than in the hippocampal formation. Our results show that the neocortical pathology in PSP, as revealed by the presence of pathological proteins, is more extended than thought so far. Our biochemical approach appears to be more sensitive than the immunohistochemical one and can clearly differentiates between two types of neurofibrillary pathology, the Alzheimer type with a triplet of abnormal Tau proteins (Tau 55, 64 and 69) and the PSP type with a characteristic doublet (Tau 64 and 69).

Aged↗
PubMed1994

Comparison of ribosomal DNA length and restriction site polymorphisms in Gremmeniella and Ascocalyx isolates.

The small subunit (SSU) and the internal transcribed spacer (ITS) of nuclear ribosomal DNA genes from 27 specimens of the fungal genera Gremmeniella and Ascocalyx were amplified by PCR. Length polymorphisms were observed in the SSU and allowed the differentiation of four groups among the isolates tested: (i) Ascocalyx abietis; (ii) Gremmeniella isolates from Picea spp.; (iii) Gremmeniella isolates from Abies balsamea; and (iv) Gremmeniella isolates from Abies sacchalinensis, Larix spp., and Pinus spp. The amplified ITS was the same length for all Gremmeniella specimens and was 60 bp longer in A. abietis. Phylogenetic analysis of length polymorphisms and of 24 restriction sites in the SSU and ITS showed that Gremmeniella isolates were more related to each other than to the Ascocalyx isolate. Furthermore, seven groups were evident within the genus Gremmeniella. Our results confirm that Gremmeniella and Ascocalyx should be kept as different taxa and suggest that the taxonomy of the former could be revised to consider isolates from Abies balsamea and from Picea spp. to be two different varieties while incorporating Gremmeniella laricina into G. abietina, as a new variety.

Base Sequence↗
PubMed1993

Electrophoretic karyotypes of the elm tree pathogen Ophiostoma ulmi (sensu lato).

Pulsed field gel electrophoresis using OFAGE, TAFE, and CHEF systems has been used to more fully characterize karyotypic variation within the two closely related fungal species of Ophiostoma ulmi sensu lato. Twelve wild-type and laboratory strains, representing the less aggressive species O. ulmi and both of the biotypes of the more aggressive species O. novo-ulmi were studied and their karyotypes determined. Depending on the strain, a minimum of four to a minimum of eight chromosomal DNA bands were present that fall into three distinct size classes, with one exception. Strain CESS16K (O. novo-ulmi, North American aggressive subgroup) contains a unique chromosomal DNA band which comigrated near a Saccharomyces cerevisiae chromosome of 0.95 Mb. This unique band was the smallest O. ulmi s. l. chromosomal DNA observed. Seven of the twelve strains shared a common chromosomal DNA banding pattern, whereas each of the other five had a unique karyotype. There was no correlation between chromosome profile and species, as some O. novo-ulmi and O. ulmi strains shared common electrophoretic karyotypes.

Chromosomes, Fungal↗
PubMed1993

Juxtaglomerular cell tumor of the kidney: report of two cases with a papillary pattern.

We report the clinicopathologic, immunohistochemical, and electron microscopic study of two cases of juxtaglomerular cell tumor of the kidney with a hitherto unreported dominant papillary pattern. Both tumors were associated with high blood pressure that did not respond to medical therapy, but that returned to normal after removal of the kidney. They were well delineated, tan, and had no necrosis. The cores of the papillary structures consisted of polygonal cells found to express renin by immunohistochemistry and to contain renin protogranules by electron microscopy. The papillary fronds were covered by one layer of cuboidal epithelial cells that did not stain for renin and had ultrastructural features reminiscent of the collecting duct epithelium. These tumors must be differentiated from malignant papillary tumors of the kidney, such as papillary clear cell carcinoma, transitional cell carcinoma, and collecting duct carcinoma.

Adenocarcinoma↗
PubMed1993

Identification of Gremmeniella abietina Races with Random Amplified Polymorphic DNA Markers.

Seven random amplified polymorphic DNA (RAPD) markers amplified from four oligonucleotides (10-mers) by the polymerase chain reaction were used to distinguish between the North American and European races of Gremmeniella abietina, the causal agent of Scleroderris canker of conifers. Forty-three isolates of the pathogen from 11 different host species originating from 11 countries, states, and provinces were tested; race designation was consistent with results from immunogenic and soluble-protein assays. By using RAPD markers, it was possible to identify G. abietina races by DNA amplifications directly from fruiting bodies, thus eliminating the need to culture the fungus, as is necessary with immunogenic and soluble-protein assays. Two isolates which had been previously classified as intermediate were clearly identified as belonging to either one of the two races by using RAPD markers. No interracial hybrids were detected in our survey. Patterns of amplification products from the European race in North America were identical to patterns of European isolates, further substantiating that this is an introduced race to the North American continent.

Journal Article↗
PubMed1991

Isoprenoid modification permits 2',3'-cyclic nucleotide 3'-phosphodiesterase to bind to membranes.

The myelination-related enzyme 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a relatively abundant protein in the CNS possesses the C-terminal isoprenylation consensus domain found in a small family that includes the ras oncoproteins and their relatives, some G-proteins, and nuclear lamins. We found that CNP, like these other proteins, is modified posttranslationally by an isoprenoid derived from mevalonic acid. It appears that only the smaller of the two CNP isoforms (CNP1) is isoprenylated, but similar modification of CNP2 cannot be excluded. Inhibition of isoprenoid synthesis by Lovastatin blocks the binding of newly synthesized CNP to cell membranes; binding is restored upon addition of mevalonate to the culture medium. This shows that isoprenylation is permissive for the well-known avid association of CNP with membranes.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Monoclonal antibody against a tumor-associated sialoglycoprotein of superficial papillary bladder tumors and cervical condylomas.

A mouse IgG1 monoclonal antibody (MAb), 19A211, defining a tumor-associated cell-surface antigen of superficial papillary bladder tumors, was generated by immunizing with fresh bladder tumor cells mice neonatally injected with normal human urothelial cells. The reactivity of the antibody with cell lines was examined by indirect immunofluorescence staining and was restricted to 3/14 bladder cancer lines and 3/31 cancer cell lines of non-bladder origin, including HeLa cervical cancer. No normal fibroblast, kidney cells, EBV-lymphocytes, erythrocytes or leukocytes expressed the antigen. Reactivity of MAb 19A211 was well preserved on tissue paraffin sections. Immunoperoxidase staining of normal adult or fetal tissues showed no reactivity except for a patchy or uniform staining of umbrella cells in 6/23 adult and 1/4 fetal urothelium samples. Positive and often heterogeneous staining was observed on 24/38 papillary superficial tumors (Ta) and 4/5 carcinoma in situ bladder lesions but on only 4/20 infiltrating tumors. It was also observed on 5/6 cervical condylomas and one bladder condyloma, but none of 6 penile or vulvar condylomas. All other tumors tested were negative. The antigenic determinant is present on a heterogeneous group of proteins with molecular weights ranging from 90 to 200 kDa. It is sensitive to periodate treatment and to neuraminidase but only partially sensitive to proteases. MAb 19A211 is different from other reported MAbs with similar reactivity to superficial bladder tumors and umbrella cells of normal urothelium. When tested in competition assays, several of these MAbs, but not 19A211, were found to react with Lewis X blood group determinant. Our results suggest that 19A211 may be useful for detection and stratification of bladder tumors.

Antibodies, Monoclonal↗
PubMed1990

Expression of the oligodendrocyte marker 2'3'-cyclic nucleotide 3'-phosphodiesterase in non-glial cells.

The 46 kD isoform of the 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPI) was expressed in HeLa cells by transfection of its cDNA clone. The distribution of this polypeptide as mapped by indirect immunofluorescence and conventional epifluorescence microscopy appeared diffuse and generally uniform throughout the cytoplasm. Confocal microscopic imaging and analysis of pseudocolored images confirmed this distribution but also revealed that there was a high concentration of CNPI near the plasma membrane of the cell. This pattern is very similar to that observed by immunoelectronmicroscopy of myelinating oligodendrocytes (Trapp et al.: J Neurochem 51:859-868, 1988; Braun et al.: J Neurosci 8: 3057-3066, 1988). These results suggest that CNP may interact with a membrane-associated molecule that is not unique to oligodendrocytes.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Identification of GTP-binding proteins in myelin and oligodendrocyte membranes.

Myelin membranes purified from mouse and rat brain are associated with alpha subunits of four signal transducing guanosine triphosphate (GTP)-binding proteins: Go, Gi, Gs, and ras. Four low-molecular-weight (Mr) GTP-binding proteins are also present, as demonstrated by the binding of GTP to proteins immobilized in nitrocellulose. This latter group is more prominent at early stages of myelination and remains associated with isolated myelin membranes despite repetitive cycles of purification. At least one nonmyelin subcellular membrane fraction possesses the same proteins. The total membrane fraction of cultured oligodendrocytes is associated with both groups of GTP-binding proteins. None of the well-known myelin proteins bound GTP by the procedure described.

Animals↗
PubMed1990

Biosynthesis of the myelin 2',3'-cyclic nucleotide 3'-phosphodiesterases.

We have investigated the site of synthesis of the 2',3'-cyclic nucleotide 3'-phosphodiesterases (CNPs I and II) in rat brain. Rapid kinetics of incorporation of CNPs into oligodendrocyte plasma membrane in the intact brain are consistent with their synthesis on free polysomes. This hypothesis was confirmed by the translation in vitro of RNA isolated from free and bound polysomes, respectively. Unlike myelin basic protein (MBP) mRNAs, CNP mRNAs are not enriched in a myelin-associated pool of RNA. MBPs, but not CNPs, were found to readily associate in vitro with membrane vesicles derived from rough endoplasmic reticulum. The avidity of MBPs in binding to membranes is probably related to the previously observed spatial segregation of MBP mRNAs into actively myelinating cellular processes of the oligodendrocyte. Such a segregation would ensure that newly synthesized MBPs are immediately incorporated into myelin. In contrast, the CNPs probably associate with the cytoplasmic surface of the oligodendrocyte plasma membrane through interaction with a membrane-bound receptor.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Physiologic properties of myelin proteins revealed by their expression in nonglial cells.

The transfection paradigm described herein can be used to investigate the functional properties of individual nervous system proteins in ways that have not been explored before. In particular, observations on the "structural" proteins of myelin are being made that have already yielded certain unique insights into the physiologic properties of these polypeptides. The ease with which site-directed mutagenesis procedures can be applied to these systems should eventually enable us to define with great precision the "functional domains" within each myelin protein.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1989

Developmental expression of myelin proteolipid, basic protein, and 2',3'-cyclic nucleotide 3'-phosphodiesterase transcripts in different rat brain regions.

RNA was extracted from five different rat brain regions during development, starting from embryonic day 15 (E15) until postnatal day 60 (P60). These RNA preparations were analyzed by both Northern and dot blot for their content of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), myelin proteolipid protein (PLP), and myelin basic protein (MBP) -specific transcripts. CNPase mRNA was readily detectable at E15 and PLP mRNA at P1 in all brain regions examined. In contrast, expression of MBP mRNA followed a caudorostral gradient. It was first observed at P1 in the mesencephalon and at P9-P11 in the olfactory bulb. Expression of these three transcripts displayed two types of developmental profiles. One was termed biphasic because the specific mRNA level increased regularly and then reached a plateau level. The other developmental profile was termed triphasic, because there was a gradual increase in the level of specific transcripts with a sudden appearance of a sharp peak followed by a decline to a plateau level. When the triphasic pattern was observed, the date of the peak appearance was probe-, but not region-, dependent. It was P15 for CNPase, P18 for MBP, and P21 for PLP. As these peaks occurred at a time during development when myelination was the most active, we postulate the existence of a transient external signal, perhaps neuronal, which would be responsible for this increased amount of myelin-related transcripts.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1988

Chromosomal locations of genes encoding 2',3' cyclic nucleotide 3'-phosphodiesterase and glial fibrillary acidic protein in the mouse.

Cyclic nucleotide phosphodiesterase (CNP) and glial fibrillary acidic protein (GFAP) are useful markers of myelin and astroglia, respectively. Two proteins with CNP activity are known to exist in brain and lymphoid tissues. They appear to be the products of several distinct but related messenger ribonucleic acid (mRNA) species. GFAP is a single protein encoded by a single mRNA. We have localized the GFAP gene to distal chromosome 11 in the mouse. There are two genetic loci identified by CNP probes, one is closely linked to the GFAP gene, and the other maps to chromosome 3.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗