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Biomedical subjects

C Simard

Publications and source records attributed to C Simard.

At least 73 records · Page 4Linked to original sources
PubMed1991

The effect of anti-neoplastic drugs on murine acquired immunodeficiency syndrome.

The murine acquired immunodeficiency syndrome (MAIDS) is associated with proliferation of target cells that have been infected by a defective retrovirus. To control the growth of this primary neoplasia, virus-inoculated mice were treated with anti-neoplastic drugs. Paradoxically, cyclophosphamide, which is also immunosuppressive, was very effective in preventing the appearance and progression of the disease, in restoring a normal T cell function, and in depleting the number of infected target cells. This result suggests that the proliferating infected target cells were responsible for the immunodeficiency.

Animals↗
PubMed1991

Characterization of a cDNA encoding a PSII-associated chlorophyll a/b-binding protein (CAB) from Chlamydomonas moewusii fitting into neither type I nor type II.

A full-length 1010-bp cDNA clone from Chlamydomonas moewusii coding for the precursor of a chlorophyll a/b-binding protein (CAB) was characterized. Northern analysis shows hybridization to a single 1150-base light-stimulated mRNA. Complementary hybrid-selected mRNAs were translated in vitro; SDS-PAGE indicates the synthesis of three polypeptides of 25, 27 and 28 kDa. Comparison of the deduced polypeptide sequence with other published CABs reveals greater similarity with PSII-associated proteins but, as with other algal CABs, our sequence does not meet established criteria for inclusion into either type I or type II, so branching of CABs into two types seems to have occurred after the divergence between algae and land plants.

Amino Acid Sequence↗
PubMed1991

Synthetic peptides corresponding to the F protein of RSV stimulate murine B and T cells but fail to confer protection.

We have previously located a major neutralization site of the fusion protein of respiratory syncytial virus (RSV) in the polypeptide region extending from amino acids Ile221 to Glu232. In this report, 8 peptides corresponding to the six major hydrophilic regions of the F1 subunit were selected to analyse their immunogenic and protective capacities as well as their ability to block the high neutralization activities of 4 monoclonal antibodies (MAbs). Only 5 of the 8 peptides tested induced specific antibodies while all induced an in vitro interleukin-2 response of splenocytes from immunized mice. Peptide 3 (Ile221-Phe237) was able to elicit neutralizing antibodies, confirming our previous hypothesis concerning the location of a neutralization site. However, immunization with the latter did not induce significant reduction of virus in lungs of BALB/c mice upon challenge, probably due to an inadequate level of circulating neutralizing antibodies. Interestingly, peptides 2 (Asn216-Glu232), 3 (Ile221-Phe237), and 5 (Ser275-Ile288) blocked in vitro neutralization by four different F1 specific MAbs. A hypothesis is proposed to explain these results.

Amino Acid Sequence↗
PubMed1991

The majority of cells infected with the defective murine AIDS virus belong to the B-cell lineage.

Murine AIDS (MAIDS) is caused by a defective retrovirus which encodes a gag fusion protein (Pr60gag). We previously reported that this virus induced an oligoclonal proliferation of infected cells and suggested that this cell expansion was an important event in the pathogenesis of MAIDS. To identify these target cells, we constructed novel defective viruses whose genomes could be detected with specific probes. Helper-free stocks of these viruses induced MAIDS. Using in situ hybridization and immunocytochemistry and Southern analysis, we found that most infected cells belong to the B-cell lineage. Transformation of these B cells appears to be the primary event responsible for the development of immunodeficiency. This animal model may be relevant to our understanding of AIDS, of the immunodeficiencies associated with B-cell lymphoproliferative disorders, and of the role of B-cell proliferation and transformation in the effects of superantigens, since Pr60gag appears to be a superantigen.

Animals↗
PubMed1991

Genomic heterogeneities in bovine herpesvirus type 1 viral isolates: a major variant selected from a field isolate.

We have analyzed viral DNA patterns, obtained following digestion of six different infectious bovine rhinotracheitis isolates, using a panel of restriction enzymes. Several differences in profiles were observed, particularly for a Canadian viral strain which presumably contained a genome that was larger than the other five infectious bovine rhinotracheitis genomes. Also, an insertion/deletion of a HindIII restriction site was found in the DNA of a Danish strain; this additional HindIII site was localized precisely within the original HindIII E fragment of the infectious bovine rhinotracheitis virus. Interestingly, results could be used to distinguish each viral strain examined from the others by simple digestion with the appropriate enzyme.

DNA, Viral↗
PubMed1991

Seroprevalence of maedi-visna in Canadian sheep.

A serological survey of Canadian sheep over one year of age was conducted to estimate the seroprevalence of maedi-visna. An indirect enzyme-linked immunosorbent assay was used. An analysis of 14,047 sera from 286 randomly selected flocks provided an estimate of the seroprevalence of 19% and a mean flock prevalence of 12%. Sixty-three percent of the sampled flocks had one or more seropositive sheep. There appeared to be higher prevalences in sheep in Quebec (40%) and Nova Scotia (27%). An increased prevalence with increased age and flock size was noted.

Age Factors↗
PubMed1990

Gene mapping of infectious bovine rhinotracheitis viral DNA genome.

A bovine herpesvirus I (BHV-I) HindIII genomic bank spanning 89% of the entire genome was constructed and individual fragments analyzed for their capacity to select specific mRNAs which were then expressed by in vitro translation assays. This procedure allowed the mapping of more than 20 viral polypeptides to discrete regions of the DNA genome. Some polypeptides map in neighboring HindIII fragments while most seem encoded in single fragments. In particular, the coding sequences for an abundant 94 kDa polypeptide, which is the potential unglycosylated precursor of gII glycoprotein, have been assigned to the small 3.6 kbp HindIII genomic fragment M. The localization of structural and non-structural gene-coding sequences will help to characterize viral polypeptides and eventually, a better understanding of BHV-I infection will be gained.

Chromosome Mapping↗
PubMed1990

Effects of electrical stimulation on the activity of hexokinase in the medial gastrocnemius muscle of aged rats after hindlimb suspension.

1. The activity of the enzyme Hexokinase (E.C. 2.7.1.1.) has been measured after a 21 day period of hindlimb suspension and a 14 day period of recovery with or without electrical stimulation in the old rat Medial Gastrocnemius muscle divided in its white and red parts. 2. After suspension, the activity of the enzyme increased in both parts of the muscle and returned near its control value more rapidly in the red part of the muscle when electrical stimulation was applied.

Adaptation, Physiological↗
PubMed1989

Immunodeficiency and clonal growth of target cells induced by helper-free defective retrovirus.

The murine acquired immunodeficiency syndrome is induced by a defective retrovirus. To study the role of virus replication in this disease, helper-free stocks of defective Duplan virus were produced. These stocks were highly pathogenic in absence of detectable replicating murine leukemia viruses (MuLVs) other than xenotropic MuLV. They induced expansion of the infected cell population (over 1000-fold), and this cell expansion was oligoclonal in origin and, most likely, arose through cell division. These results suggest that this defective virus is oncogenic, inducing a primary neoplasia associated with an acquired immunodeficiency syndrome as a paraneoplastic syndrome. These data emphasize the need to determine whether virus replication is necessary for the progression of other immunodeficiency diseases, including acquired immunodeficiency syndrome, and whether these diseases also represent paraneoplastic syndromes.

Animals↗
PubMed1989

Comparison of caprine, human and bovine strains of respiratory syncytial virus.

A new continuous ovine kidney cell line allowing the growth of caprine, human and bovine respiratory syncytial virus was used to minimize host cell related variations for the direct comparison of the viral ultrastructures, serological relationships and structural protein profiles. Results show that all three strains are closely related although a closer relationship was found between bovine and caprine RS.

Animals↗
PubMed1989

Experimental polyvalent ISCOMs subunit vaccine induces antibodies that neutralize human and bovine respiratory syncytial virus.

The purpose of the present study was to evaluate experimentally, in guinea-pigs, the immunogenicity of respiratory syncytial (RS) virus subunit vaccines. Immunostimulating complexes (ISCOMs), made from the surface proteins of both human (Long) and bovine (A-51908) RS strains adsorbed to the adjuvant Quil A, were assayed for their capacity to induce neutralizing antibodies, in comparison to experimental live virus vaccines. Serums from animals vaccinated with either the human or bovine RS subunit vaccines were equally efficient in neutralizing human or bovine RS virus. ISCOMs prepared with bovine RS virus proteins were significantly (p less than 0.05%) more efficient than their human counterpart, in inducing neutralizing antibodies, suggesting their greater potential as a subunit vaccine.

Adjuvants, Immunologic↗
PubMed1989

Effect of the androgenic status on the phenotype of the plantaris muscle of the rat.

1. The early demonstration of specific androgen binding sites in skeletal muscle suggested that androgen might be involved in the homeostasis of the tissue in adult mammals. 2. Following five weeks of androgen withdrawal, a noticeable increase in the plantaris (PLT) myosin heavy chain cleavage occurs. No other alteration of the contractile proteins pattern was detected. 3. No effect on the template activity of major mRNAs associated with the polysomal fraction was observed in GDX or GDX + TP group compared to control rats. 4. As opposed to the PLT muscle, the template activity of polyribosomes isolated from the androgen sensitive levator ani muscle displays a severe alteration following GDX. 5. Force-frequency analysis of PLT indicated however that the MHC modification was of no functional significance.

Androgens↗
PubMed1989

Maturation and subcellular compartmentation of potato starch phosphorylase.

The subcellular localization and maturation of starch phosphorylase (EC 2.4.1.1) was studied in developing potato tubers. The enzyme is localized inside the stroma of amyloplasts in young tubers, whereas in mature tubers it is found within the cytoplasm in the immediate vicinity of the plastids. A phosphorylase cDNA clone was isolated and used in RNA gel blot experiments to demonstrate that phosphorylase mRNAs are of the same size and abundance in both young and mature tubers. In vitro translation of mRNAs followed by immunoprecipitation with a phosphorylase antiserum indicates that the enzyme is synthesized as a higher molecular weight precursor in both young and mature tubers. The presence of a transit peptide at the N terminus of the protein was confirmed by the sequencing of the phosphorylase cDNA clone. The transit peptide has several structural features common to transit peptides of chloroplast proteins but contains a surprisingly large number of histidine residues. The mature form of the enzyme is present in both young and mature tubers, suggesting that a similar processing of the transit peptide may take place in two different subcellular locations.

Amino Acid Sequence↗
PubMed1988

Cloning and sequencing of a cDNA encoding the small subunit precursor of ribulose-1,5-bisphosphate carboxylase from Chlamydomonas moewusii. Evolution of RUBISCO SS polypeptide.

We have isolated and characterized a full-length cDNA clone encoding the precursor of the small subunit (pSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase (RUBISCO) from the green alga, Chlamydomonas moewusii. Comparison with the C. reinhardtii rbcS1 gene sequence reveals that both small subunit (SS) coding regions are 75% homologous and that their predicted mature polypeptide chains are each composed of 140 amino acids. In contrast, their transit peptides appear to be divergent. We also show that transcription of the C. moewusii rbcS gene(s) which generates a 1,230 and a 930 base mRNA species are light-stimulated/or accumulated during the light period of the cell cycle. Finally, the SS polypeptide sequences of fifteen different photosynthetic organisms are compared; this analysis reveals at least five well-conserved polypeptide domains.

Amino Acid Sequence↗
PubMed1988

Contractile and histochemical properties of young and old medial gastrocnemius muscle after suspension hypokinesia/hypodynamia.

In order to determine if the atrophic process was different in the young and in the aged fast twitch medial gastrocnemius muscle, in which the aging process is clearly apparent, hindlimb hypokinesia/hypodynamia (H/H) was induced on rats. After 3 weeks, we measured speed-related indices, tension indices and tension producing capacities. Fiber type composition and fiber cross-sectional area were also determined. The body weight and muscle weight decreased. The ratio of muscle weight to body weight was greater in the 3-month-old control group than in the 22-month-old group. However, the ratio was not altered by H/H. In both groups, contraction time, half relaxation time and twitch tension did not vary with H/H but maximally developed tension and force generated per gram of muscle were decreased. For the histochemical analysis, the medial gastrocnemius muscle was divided in its red and white parts. Fiber type composition remained the same after H/H in both parts of the muscle and in both groups of age except for an increase of the FOG fiber type proportion in the red part of the old group. Fiber cross-sectional area increased with age and decreased after the suspension except for the fast fibers in the white part of the aged muscle. The most affected group in fiber cross-sectional (SO-FOG-FG) area after suspension was the white part of medial gastrocnemius in the young group. The suspension atrophy appeared to be independent of age in the medial gastrocnemius at the contractile level whereas atrophy was greater at the histochemical level in the young muscle. With age, fiber cross-sectional area increased particularly in the red part of the muscle.

Aging↗
PubMed1987

Effects of hypokinesia/hypodynamia on contractile and histochemical properties of young and old rat soleus muscle.

To determine if the atrophic process was different in the young and in the aged slow-twitch soleus muscle, in which the aging process is clearly apparent, hind limb hypokinesia/hypodynamia was induced. After 3 weeks, we measured speed-related indices, tension indices, and tension producing capacities. Fiber type composition and fiber cross-sectional area were also investigated. After the treatment, body weight and muscle weight decreased, the most important loss being measured in the young group. The ratio of muscle weight to body weight was not altered by hypokinesia/hypodynamia but this ratio was greater in the 3-month-old control group than in the 22-month-old group. Contraction time and half-relaxation time decreased in both groups. In the control group, the old soleus muscle was slower to contract and relax than in the young muscle. Tension indices and tension producing capacities decreased. These included twitch tension, maximally developed tension, force generated per gram muscle, and specific tension. The mean muscle area and muscle weight of the young soleus decreased more than that of the old soleus. The fiber cross-sectional area was reduced in both groups whereas fiber type composition remained the same after hypokinesia/hypodynamia. The suspension atrophy appeared to be independent of age in the soleus at the contractile level whereas atrophy was greater in the young muscle at the morphometric level.

Adenosine Triphosphatases↗
PubMed1987

Use of a phage vector for rapid synthesis and cloning of single-stranded cDNA.

We have developed a technique for synthesis of single stranded complementary DNA (ss cDNA) using specifically designed phage ssDNA as vector primer. This vector (pPBS27) was constructed by introducing a poly(dT) tail adjacent to the XbaI site of pTZ18R, which can exist either as a plasmid in Escherichia coli or as a ssDNA phage. The pPBS27 phage vector is linearized with XbaI using a restriction-site-directed fragment and used to anneal a mixture of poly(A) + RNA for cDNA synthesis by reverse transcriptase. The RNA is then hydrolysed with NaOH and a poly(dG) tail added to the 3' end of the vector-cDNA with terminal transferase. The linear hybrid ssDNA is then closed by annealing with a 15-mer site-directed fragment oligodeoxynucleotide molecule and ligated with T4 DNA ligase. Almost 10(5) E. coli transformants per microgram of vector primer can be obtained in two days.

Base Sequence↗