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Biomedical subjects

R Simard

Publications and source records attributed to R Simard.

At least 19 recordsLinked to original sources
PubMed2000

Clinical and molecular aspects of juvenile hemochromatosis in Saguenay-Lac-Saint-Jean (Quebec, canada).

We report the clinical, biochemical, and genetic characteristics of 13 hemochromatosis patients from Saguenay-Lac-Saint-Jean in whom the first symptoms appeared before age 30. Although the mean age at onset of the first symptoms was 21. 5 years, their mean age at diagnosis was 23.8 years; the diagnosis was particularly delayed among women. Seventy-seven percent of the patients had hypogonadotrophic hypogonadism and 69% heart failure and/or cardiac arrhythmias. Genetic analysis of the HFE gene revealed heterozygosity for the C282Y mutation in 2 patients and for the S65C mutation in 2 others and homozygosity for the H63D mutation in 1 patient. The remaining 8 patients had no identified mutation in the HFE gene, although sequencing of all seven codons and intron-exon junctions was performed (5 patients). All 13 patients fulfill the clinical criteria of juvenile hemochromatosis and represent the largest cluster thus far reported.

Adolescent↗
PubMed2000

Mutation analysis in the HFE gene in patients with hereditary haemochromatosis in Saguenay-Lac-Saint-Jean (Quebec, Canada).

A mutation analysis of the HFE gene followed, when applicable, by sequencing was performed on 47 patients with hereditary haemochromatosis (HH) living in Saguenay-Lac-Saint-Jean. The C282Y and H63D mutations were present on 50% and 20.3% of the HH chromosomes respectively. These frequencies were very different from those found in other populations and could be, at least partially, the result of a founder effect. No new mutation was identified among the remaining 28.1% of the HH chromosomes. Five of the eight probands with no mutation in the HFE gene had a severe and early onset suggestive of juvenile haemochromatosis.

Alleles↗
PubMed1998

Release of enzymes from liposomes during cheese ripening.

Changes in proteolysis and in residual enzymatic activity as a function of time were compared in model cheeses, made with either free enzymes or liposomes containing enzymes and in control model cheeses. Cheeses were ripened under different conditions of pH, fat content and temperature. The release of enzymes from liposomes was significantly stimulated by increasing the fat content from 0 to 20% and the pH from 4.9 to 5.5. Ripening temperature (6 degrees C or 13 degrees C) did not affect 2 months of ripening, proteolysis was 30% lower in liposome-than in free enzyme-treated cheeses, indicating a possible inhibition of released enzymes.

Calcium-Binding Proteins↗
PubMed1998

Immunodot detection of nisin Z in milk and whey using enhanced chemiluminescence.

A highly specific antisera was produced in New Zealand white rabbits against nisin Z, a 3400 Da bacteriocin produced by Lactococcus lactis ssp. lactis biovar. diacetylactis UL 719. A dot immunoblot assay was then developed to detect nisin Z in milk and whey. As few as 1.5 10(-1) international units per ml (IU ml-1), corresponding to 0.003 microgram ml-1 of pure nisin Z, were detected in carbonate-bicarbonate buffer within 6 h using chemiluminescence. When milk and whey samples were tested, approximately 0.155 microgram ml-1 (7.9 IU ml-1) of nisin Z was detected. The detection limit obtained was lower than that of traditional methods including microtitration and agar diffusion.

Animals↗
PubMed1997

A population-based, randomized clinical trial on back pain management.

STUDY DESIGN: Population-based randomized clinical trial. OBJECTIVES: To develop and test a model of management of subacute back pain, to prevent prolonged disability. SUMMARY OF BACKGROUND DATA: The present management of back pain seems inadequate, and development of innovative models has been urged. METHODS: A model for the treatment of subacute work-related back pain has been developed and evaluated in a population-based randomized clinical trial. Workers (n = 130) from eligible workplaces in the Sherbrooke area (N = 31), who had been absent from work for more than 4 weeks for back pain, were randomized, based on their workplace, in one of four treatment groups: usual care, clinical intervention, occupational intervention, and full intervention (a combination of the last two). The duration of absence from regular work and from any work was evaluated using survival analysis. Functional status and pain were compared at study entry and after 1 year of follow-up. RESULTS: The full intervention group returned to regular work 2.41 times faster than the usual care intervention group (95% confidence interval 1.19-4.89; P < 0.01). The specific effect of the occupational intervention accounted for the most important part of this result, with a rate ratio of return to regular work of 1.91 (95% confidence interval = 1.18-3.10; P < 0.01). Pain and disability scales demonstrated either a statistically significant reduction or a trend toward reduction in the three intervention groups, compared with the trend in the usual care intervention group. CONCLUSIONS: Close association of occupational intervention with clinical care is of primary importance in impeding progression toward chronicity of low back pain.

Adolescent↗
PubMed1994

Management of occupational back pain: the Sherbrooke model. Results of a pilot and feasibility study.

OBJECTIVES: The aim was to combat occurrence of chronic occupational back pain. METHODS: A multidisciplinary model to manage back pain that includes both clinical and ergonomic approaches has been developed. Early detection, early clinical and ergonomic evaluations, and early active treatment make up the cornerstone of management. Detection of cases starts after four weeks of absence from work. An ergonomic intervention is implemented at six weeks. A medical specialist is involved at eight weeks. If return to work is not possible after 12 weeks, a functional recovery therapy followed by a therapeutic return to work is implemented. A multidisciplinary team decides if return to original or modified work is possible or if vocational rehabilitation is necessary. This model has been implemented by the investigators in the Sherbrooke (Quebec, Canada) area, and is presently being evaluated through a randomised trial in 31 industrial settlements (about 20,000 workers). A cluster randomisation of industries and workers will allow separate testing of ergonomic and clinical interventions. RESULTS: One year after implementation, 31 of 35 of the eligible industrial sites participated in the study and 79 of 88 of the eligible workers affected by recent back pain had agreed to participate. Ergonomic and clinical interventions have been implemented as planned. Only three workers dropped out. Hence this global clinical and ergonomic management programme has been shown to be feasible in a general population. CONCLUSION: A global management programme of back pain joining ergonomic and clinical intervention with a multidisciplinary approach has not been tested yet. Linking these two strategies in a same multidisciplinary team represents a systemic approach to this multifactorial ailment. During the first year of this trial we did not find any conflict between these two interventions from the employer's or worker's point of view.

Adult↗
PubMed1991

Upper eyelid movements measured with a search coil during blinks and vertical saccades.

Upper eyelid movements were recorded in nine human subjects by mounting a miniature coil of wire directly on the eyelid and subjecting the search coil to a vertically directed alternating magnetic field. The metrics of blinks and lid movements accompanying saccades were described by "main sequence" relationships, linking maximum velocity to amplitude and duration to amplitude. In general, lid movements were faster than those reported previously in the literature, but there was considerable intersubject variability. On average, the main sequence relationships for blinks were independent of either starting lid position or whether the blinks were generated spontaneously, reflexively, or voluntarily. For the down phase of the average blink, both the maximum velocity and duration increased almost linearly with amplitude. The maximum velocity of the down phase was faster than that of the up phase. For lid movements accompanying vertical saccades, the maximum velocities in the up and down directions were similar and increased nonlinearly with amplitude, saturating at about 120 mm/sec (approximately 450 degrees/sec). Duration increased approximately linearly with amplitude. The down phases of blinks were much faster than those of saccade-related lid movements. By comparison, the maximum velocities of the up phase of blinks and of saccade-related lid movements were almost equal. The large intersubject variability suggests caution when using normative data to interpret abnormal lid motion for clinical purposes.

Adult↗
PubMed1987

DNA-binding proteins of herpes simplex virus type 1-infected BHK cell nuclear matrices.

The nuclear matrix is involved in the replicative cycle of herpes simplex virus type 1 (HSV-1) and in at least some cases viral DNA has been shown to be closely associated with this structure. In this communication, we report the presence of five DNA-binding proteins in the nuclear matrix of HSV-1-infected BHK cells. These proteins (p114, p89, p77, p37 and p29) were detected by probing with 32P-labelled HSV DNA after Western blotting of nuclear matrix proteins. Three were identified as virion components: p89 as VP12, p77 as VP13 and p37 as the capsid protein VP22a. These polypeptides were detected in cells and nuclei and found to be associated with the nuclear matrix late during the lytic cycle, long after the onset of viral DNA replication. The nuclear matrix-binding capacity of VP22a depended on viral DNA replication, since after DNA polymerase inhibition it was still synthesized and transported into the nucleus but was no longer associated with the nuclear matrix. After inhibition of viral DNA synthesis, VP13 was no longer found in cells, nuclei or nuclear matrices. These results suggest a possible involvement in anchoring viral progeny DNA to the nuclear matrix.

Animals↗
PubMed1986

Role of the nuclear matrix in adenovirus maturation.

The nuclear matrix has been implicated in several important cellular processes. In this paper, we investigate the role of the nuclear matrix in adenovirus type 2 assembly. Electron microscopic examination of nuclear matrices isolated from adenovirus infected Hep-2 cells clearly reveals that late in the lytic cycle, adenovirus capsids are intimately associated with the nuclear matrix. SDS-PAGE analysis showed that the viral core polypeptides V, PVII and 11 kDa were enriched in the nuclear matrix fraction. After a 3 h chase period a constant high ratio of PVII to VII prevailed in the nuclear matrix suggesting that mostly young virions and viral cores are bound to this structure. Most of the virus maturation endoproteinase activity co-purified with the nuclear matrix and the data suggest that the enzyme may be released from fragile young virions or assembly intermediates. Together these experiments suggest that the nuclear matrix is the site of adenovirus assembly and that mature virions may be released from the matrix by the viral endoproteinase.

Adenoviruses, Human↗
PubMed1985

Detection in BHK cells of a precursor form for lamin A.

Lamins are structural proteins found in the fibrous lamina underlining the nuclear envelope. In vitro translation of polyadenylated RNA or polysomes followed by immunoprecipitation with a serum raised against BHK nuclear matrix proteins showed that lamin A (72 kD) is synthesized as a high molecular weight precursor (74 kD) (Laliberté et al., J Cell Biol 98 (1984) 980) [23]. We have thus investigated the presence in BHK cells of this putative precursor by in vivo labelling with [35S]methionine and immunoprecipitation of lamin proteins. Short labelling times, ranging from 5 to 60 min reveal the presence of the 74 kD protein. Pulse-chase experiments indicate that the half-life of the precursor is about 60 min. On two-dimensional gel, the 74 kD protein is resolved in a cluster of isovariants between pH 7.4 and 6.6, which are generally slightly more alkaline than their counterparts in lamin A. These results indicate that lamin A is synthesized as a precursor of 74 kD; the long half-life further suggests that pre-lamin A might accumulate in some sort of cellular pool before undergoing post-transcriptional modification(s) to give the mature form of lamin A.

Animals↗
PubMed1985

In situ localization of the major capsid protein during lytic infection by herpes simplex virus.

The intracellular localization of the major capsid protein (ICP5) of herpes simplex virus was studied during virogenesis. Except for a brief period at the onset of synthesis, this protein was found almost exclusively inside the nucleus. Its localization was not at random since 80% was tightly bound to the nuclear matrix as early as 4 h after infection. Discrete modifications of the fluorescence pattern occurred in an orderly fashion during the progression of the infection. Immunoelectron microscopic studies using Protein A-gold labelling demonstrated that this protein is synthesized on cytoskeleton-bound polyribosomes and accumulates in the central part of the nucleus where formation of viral capsids occurs; no gold particles were found in association with the peripheral chromatin or with the nucleolus.

Animals↗
PubMed1985

Nuclear matrix modifications at different stages of infection by herpes simplex virus type 1.

In BHK-21 cells infected with herpes simplex virus type 1 many virus-induced proteins were found attached to the nuclear matrix. To understand the role of this cell fraction during virogenesis, matrix-associated proteins were analysed at different stages of infection. All the immediate-early protein species were bound to the nuclear matrix and their association with this structure was stable. During the first few hours of infection, the pattern of virus-induced proteins attached to the nuclear matrix remained identical, indicating that polypeptides from the early group are not associated with this cell fraction. Among the late proteins, which are generally structural proteins, 60% of the nuclear proteins were tightly bound to the nuclear matrix. This suggests that the nuclear matrix is involved in at least two different events during virogenesis, regulation of viral infection and assembly of viral capsids.

Animals↗
PubMed1984

Characterization of lamin proteins in BHK cells.

Lamins are structural proteins found in rat liver nuclear envelope and are major constituents of the nuclear matrix. 2-D gel electrophoresis indicates that BHK cell nuclear matrix is composed of four major proteins (62 kD, 68 kD, 70 kD and 72 kD). Three of these proteins are very similar to lamins A, B and C of rat liver nuclear envelope according to their molecular mass and isoelectric points. An anti-serum specific to BHK matrix proteins has been raised. On 2-D immunoblot, this serum detects all the 62, 68 and 72 kD polypeptide isovariants but only one of the two isovariants of the 70 kD polypeptide. Rat lamins A, B and C react with the anti-BHK matrix serum. However, when a monoclonal antibody to rat liver lamins A, B and C is used (Burke, B, Tooze, J & Warren, G, EMBO j 2 (1983) 361 [23]), only the 72 kD (lamin A-like) and the 62 kD (lamin C-like) BHK polypeptides are detected. Our results suggest that although a strong similarity exists between BHK and rat lamins, there is no identical cross-reactivity between the two species.

Animals↗
PubMed1984

Identification of distinct messenger RNAs for nuclear lamin C and a putative precursor of nuclear lamin A.

The lamins are the major components of the nuclear matrix and are known as lamins A, B, and C with Mr 72,000, 68,000, and 62,000 when analysed by SDS PAGE. These three polypeptides are very similar, as determined by polypeptide mapping and immunological reactivity. Lamins A and C are so homologous that a precursor-product relationship has been proposed. Using an antiserum against nuclear matrix proteins that specifically immunoprecipitates the three lamins, we examined their synthesis in the rabbit reticulocytes lysate. Four bands of Mr 62,000, 68,000, 70,000, and 74,000 were specifically immunoprecipitated when polysomes or polyadenylated RNA were translated in vitro. By two-dimensional gel electrophoresis, the 68,000- and the 62,000-mol-wt proteins were identified as lamins B and C, respectively, and the 74,000-mol-wt polypeptide had properties of a precursor of lamin A. The mRNAs of lamin C and of the putative precursor of lamin A were completely separated by gel electrophoresis under denaturing conditions, and their respective sizes were determined. These results suggest that lamin A is not a precursor of lamin C.

Animals↗
PubMed1984

Distribution of U3 snRNA in the nucleolus of CHO cells.

Localization of snRNA at the ultrastructural level was studied in the nucleolus of CHO cells by EM autoradiography. In conditions where snRNA U3 is the only RNA species labelled in the nucleolus, silver grains were largely found at the periphery, over the granular ribonucleoprotein component and the perinucleolar condensed chromatin; this enrichment was quantitatively significant. Inhibition of pre-rRNA synthesis with actinomycin D did not alter the concentration or the distribution of U3 inside the nucleolus. The results are consistent with the demonstration that U3 is hydrogen-bonded to 28S pre-rRNA, and thus should be found in the granular compartment where 32S-28S pre-rRNA is assembled into 55s RNP.

Animals↗
PubMed1983

Localization of small nuclear RNA by EM autoradiography in Chinese hamster ovary (CHO) cells.

The ultrastructural localization of small nuclear RNA (snRNA) was studied by EM autoradiography in Chinese Hamster Ovary (CHO) cells. Conditions were set where most (greater than 85%) of the nuclear [3H]uridine label consisted of snRNA, the most abundant species being U1, U2 and the nucleolar species U3. The label was found in highest density in the peripheral part of the nucleus, especially over areas of condensed chromatin. A quantitative analysis of grain distribution showed that the enrichment observed in the periphery was significant (P less than 0.001). Labelling was also observed over the nucleolus. Labelling conditions using inhibitors of RNA synthesis provided additional evidence that the precursor was incorporated into snRNA. Our results show that in interphasic CHO cells, the greatest abundance of snRNA is found, in situ, over areas enriched in condensed chromatin. Whereas the nature of this association remains to be elucidated, these findings suggest that some species of snRNA might be involved in the structure of chromatin; among the various species, U2 appears as the best candidate.

Amanitins↗
PubMed1983

Localization of the 70 000 dalton heat-induced protein in the nuclear matrix of BHK cells.

The exposure of exponentially growing BHK cells to supranormal temperatures (41-44 degrees C, for 15 min to 1 h) induces the synthesis of a new set of proteins, the heat shock proteins, while the synthesis of proteins made before heat shock is repressed at 43 degrees C. Among the two major heat shock proteins induced, of molecular weight 70 K and 68 K, only the 70 kD protein is found bound to the nuclear matrix. This protein is resolved differently from the normal matrix proteins by isoelectric focusing and, when blotted, does not react with antibodies directed against nuclear matrices. These results show that the 70 kD heat shock protein is a new protein transferred from the cytoplasm to the nucleus, where it binds to the nuclear matrix, suggesting a structural role for this protein.

Animals↗