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Biomedical subjects

P Simard

Publications and source records attributed to P Simard.

At least 19 recordsLinked to original sources
PubMed1998

JC9813-A putative novel human papillomavirus identified by PCR-DS.

Papillomaviruses consist of more than 130 viral types described so far. Most of them are human papillomaviruses (HPV) of supergroup A, demonstrating ano-genital tropism and characterized as etiological agents for benign and malignant cervical lesions in women. A PCR-direct sequencing (PCR-DS) approach with P-33 labeled dideoxynucleotides was used to detect and type human papillomaviruses in cervical biopsies. One novel sequence was identified in a LSIL (low-grade squamous intraepithelial lesions) specimen from an HIV-positive English Canadian patient. The structure of the viral gene L1 was determined, yielding a putative novel HPV type of supergroup A (clade A8) named JC9813.

Adult↗
PubMed1996

Aeromonas hydrophila isolated from food and drinking water: hemagglutination, hemolysis, and cytotoxicity for a human intestinal cell line (HT-29).

Aeromonas hydrophila isolated from food and drinking water was tested for pathogenicity by studying its hemolysis, hemagglutination, and cytotoxicity. Hemolysis, tested on erythrocytes from six different species, was more frequently seen with water isolates (64%) than with food isolates (48%). Hemagglutination was more frequently encountered with food isolates (92%) than with water isolates (73%). Cytotoxicity, evaluated on seven cell lines, was frequently observed with food isolates (92%) and with water isolates (73%). Heat treatment (56 degrees C for 10 min) of culture supernatant fluids inhibited the toxicity of some but not all toxin-producing isolates. Our results suggest that the human intestinal cell line HT-29 could be a useful complement for testing A. hydrophila exotoxins and for studying the enteropathogenicity of this species for humans.

Aeromonas hydrophila↗
PubMed1996

Differential media for quantitative recovery of waterborne Aeromonas hydrophila.

Because of the ubiquity of Aeromonas spp., their prevalence in drinking water, and the increasing number of reports on Aeromonas sp.-related infections, a standard method for routine and quantitative recovery had to be defined. On the basis of a survey of 10 media for recovery analysis and subsequent differentiation assays in mixed cultures, we conclude that ampicillin-dextrin agar performed the best for the recovery of Aeromonas spp. in drinking water and the differentiation by simple criteria of that genus from other common waterborne bacteria.

Aeromonas hydrophila↗
PubMed1995

Evidence for functional interaction between the HIV-1 Tat transactivator and the TATA box binding protein in vivo.

Tat strongly activates transcription of the HIV-1 provirus by stimulating both initiation and elongation. This transactivator binds to the TAR RNA element, but can also associate with cellular transcription factors, interacting with upstream promoter sequences. To achieve a better understanding of the role of Tat in the assembly of the transcriptional initiation complex in the living cell, we have examined how the activity of this protein is modified when the general transcription factor involved in the first step of this process, TBP, is overexpressed. The activity of Tat, either wild-type or fused to the DNA binding domain of GAL4 (GBTat), was tested using reporter constructs containing GAL4 binding sites upstream of a minimal promoter corresponding to the HIV-1 TATA box, with or without the TAR element. We found that overexpression of TBP led to a dramatic increase in the activity of the GBTat protein. In order to activate GBTat, TBP must be able to interact with the TATA box. Analysis of several Tat mutants indicated that both the cysteine-rich and the core domains of this transactivator are necessary and sufficient to activate transcription when TBP is overexpressed. In vitro experiments showed that Tat binds specifically to TBP. There was a correlation between the ability of different Tat mutants to bind TBP and their capacity to activate transcription in vivo. With the natural HIV-1 promoter, overexpression of TBP first stimulated and then suppressed the Tat-induced activity. This inhibition was abrogated by an increase in the intracellular levels of Tat. These experimental data indicate that Tat stimulates initiation of transcription by interacting with TBP in vivo.

DNA-Binding Proteins↗
PubMed1994

Comparison of the microbiological quality of water coolers and that of municipal water systems.

The microbiological quality of tap water and that of water from 50 water coolers located in residences and workplaces were comparatively studied. In addition, difference factors that might influence the bacteriological contamination of water dispensers were examined. Aeorbic and facultative anaerobic heterotrophic bacteria, total coliforms, and two indicators for fecal contamination (fecal coliforms and fecal streptococci) as well as three types of pathogenic bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, and Aeromonas spp.) were enumerated. It was found that 36 and 28% of the water dispenser samples from the residences and the workplaces, respectively, were contaminated by a least one coliform or indicator bacterium and/or at least one pathogenic bacterium. The respective proportions of tap water samples contaminated in a similar fashion were 18 and 22%, much less than those observed for water coolers (Chi2(1) = 3.71, P = 0.05). We were unable to discern the dominant factors responsible for the contamination of water coolers, but cleaning the water dispenser every 2 months seemed to limit the extent of contamination.

Drinking↗
PubMed1993

Impact of the ring-billed gull (Larus delawarensis) on the microbiological quality of recreational water.

We evaluated the impact of the ring-billed gull (Larus delawarensis) on the microbiological quality of water. We measured fecal coliforms, Salmonella spp., and Aeromonas spp. in the gull droppings and the number of fecal coliforms in the water prior to and after attracting these birds to the beach with food. Gulls can contribute to the bacteriological degradation of recreational water.

Aeromonas↗
PubMed1993

The transcriptionally active factors mediating the effect of the HTLV-I Tax transactivator on the IL-2R alpha kappa B enhancer include the product of the c-rel proto-oncogene.

The transactivator HTLV-I Tax activates the promoter of the gene coding for the interleukin 2 alpha-chain receptor (IL-2R alpha) via a kappa B site that can bind several protein species of the rel family. Tax1 strongly activates the enhancer activity of this motif, in both epithelial HeLa and lymphoid Jurkat cells. This activation was not observed in undifferentiated embryocarcinoma F9 cells. Overexpression of the p50, p65 and Rel proteins in these cells showed that significant activation of the IL-2R alpha kappa B site was observed only with Rel and Rel plus p65. Moreover, whereas both Tax and phorbol 12-myristate 13-acetate (PMA) are able to efficiently induce the binding of NF-kappa B to the IL-2R alpha kappa B site, PMA is functionally inactive. Using the DNA affinity precipitation assay, we observed that Tax1 is able to efficiently induce the binding of Rel, whereas PMA is not. This established a clear difference between both stimuli, indicating that Rel is the functionally active factor. We conclude from these results that the functional activity of members of the rel family is regulated by their interaction with DNA and that Rel can be a potent transcriptional activator on specific kappa B sites.

Base Sequence↗
PubMed1990

Epstein-Barr virus polymorphic B-cell lymphoma associated with leukemia and with congenital immunodeficiencies.

Polymorphic B-cell lymphoma seen in four patients with congenital immunodeficiencies and in two patients with leukemia receiving chemotherapy was associated with the Epstein-Barr virus (EBV). The tumors had characteristic histologic features: they were polymorphic consisting of a mixture of lymphoblasts and differentiated cells including plasma cells, and areas of hemorrhagic necrosis were prominent. The tumors were either polyclonal, monoclonal, or multiclonal. Patients with congenital immunodeficiencies who developed these tumors died despite radiotherapy, corticosteroids plus acyclovir, or a combination of intravenous (IV) immunoglobulins and alpha 2 interferon. Patients with leukemia recovered when immunosuppressive drugs were discontinued and leukemia has not recurred over a period of 2 and 4 years, respectively, in the two patients.

Antineoplastic Agents↗
PubMed1988

A twenty-year experience with thyroid carcinoma in children.

During the past 20 years, 23 patients (7 males, 16 females) were operated on for thyroid carcinoma in our institution. The average age was 13.6 years (range, 22 months to 27 years). Our series includes papillary carcinoma in 11, follicular carcinoma in four, and medullary thyroid carcinoma in eight patients. Follow-up ranged from 8 months to 20.3 years, with an average of 7.5 years for well-differentiated carcinomas and 4.3 years for medullary thyroid carcinomas. All patients are presently alive with no evidence of progressive disease. Patients with papillary and follicular carcinomas underwent partial thyroidectomy; those with medullary carcinoma underwent total thyroidectomy. Serious complications included three permanent hypoparathyroidism and two tracheostomies, all after secondary neck explorations. The overall results observed in our series of patients seem to support the current conservative approach to well-differentiated thyroid carcinoma, reserving total thyroidectomy for medullary cancer of the thyroid. A more aggressive search for familial medullary carcinoma through use of pentagastrin stimulation leads to early detection and more effective therapy.

Adenocarcinoma↗
PubMed1987

Management of thyroid nodules in children: a 20-year experience.

The medical records and surgical slides of 58 patients with the diagnosis of thyroid nodules (solitary nodule in 50 patients) are reviewed. The most common cause of thyroid nodules in this series is follicular adenoma (27 patients or 46%). A nuclear scan (technetium or radioactive iodine) was performed in 55 patients, of which 40 showed a cold nodule. Twelve of the 40 cold nodules were malignant (30%). However, for solitary nodules the incidence of cancer is 27%. This last figure is significantly greater than the one recently reported by Hung et al (18.5%). Available diagnostic methods are reviewed and the clinical management as derived from our experience is presented.

Adolescent↗
PubMed1987

Influence of growth medium and supplement on growth of Haemophilus influenzae and on antibacterial activity of several antibiotics.

In the present study, five non-beta-lactamase- and five beta-lactamase-producing strains of Haemophilus influenzae were used to determine whether three different growth media, Mueller-Hinton broth and agar, brain heart infusion broth and agar, and tryptic soy broth and agar, and their added supplements (0.2% hemin-0.1% IsoVitaleX, 1% hemin-1% IsoVitaleX, 2% sheep blood, 10% Fildes enrichment, 5% Fildes enrichment, 1% supplement B, 5% horse erythrocytes, and 2% hemoglobin-1% IsoVitaleX) would influence the growth rate of this microorganism and the antibacterial activity of eight antibiotics, including ampicillin, tetracycline, chloramphenicol, gentamicin, cefamandole, erythromycin, trimethoprim-sulfamethoxazole (TMP-SMX), and cefoperazone. The growth curve studies were carried out with an initial inoculum of 10(4) bacteria per ml, and MICs were determined with an inoculum of 5 X 10(5) microorganisms. Mueller-Hinton broth, brain heart infusion broth, and tryptic soy broth enriched with 5% Fildes resulted in a maximal growth of more than 10(8) CFU/ml at 24 h. When 10% Fildes or 2% sheep blood was added as enrichment to Mueller-Hinton broth, a considerable reduction in the growth rate of H. influenzae strains resulted (P less than 0.01). Significant variations in MICs (P less than 0.01) were observed with chloramphenicol, TMP-SMX, erythromycin, and cefoperazone when brain heart infusion agar, Mueller-Hinton agar, or tryptic soy agar was used. Chloramphenicol, gentamicin, erythromycin, and TMP-SMX were all affected by the different enrichments added to Mueller-Hinton agar. MICs were in general higher with 5% Fildes enrichment and lower with 1% supplement B. Cefoperazone was the only drug which exhibited a lower MIC in 5% Fildes enrichment for ampicillin-resistant H. influenzae strains.

Ampicillin↗
PubMed1986

Influence of three modes of administration on the penetration of latamoxef into interstitial fluid and fibrin clots and its in-vivo activity against Haemophilus influenzae.

The extravascular penetration and bactericidal activity of latamoxef against beta-lactamase positive Haemophilus influenzae were studied in a rabbit model. All groups of animals received over 24 h an identical dose of 100 mg/kg of latamoxef given by three different intravenous modes of administration including a single large injection of 100 mg/kg, four 25 mg/kg intermittent injections every 6 h, and a continuous infusion of 100 mg/kg over 24 h. A single large injection resulted in significantly higher peak levels and higher initial area under the curve of concentrations of drug in serum, interstitial fluid, and fibrin clots than other modes of administration. Continuous infusion resulted in an accumulation of drug in clots which rose from 1.0 microgram/g at 4 h to 4.9 micrograms/g at 24 h (P value less than 0.01). The rate of killing of H. influenzae imbedded in fibrin clots was greatly influenced by the different modes of therapy. Even though all regimens resulted in peak concentrations which were more than 80 times the MIC (0.03 mg/l) in the fibrin clots, rapid killing (from 10(7) to less than 10(2) micro-organisms per g of clots in less than 6 h) was only observed with a single bolus. Continuous infusion and intermittent injections of latamoxef resulted in limited in-vivo bactericidal activity. Large doses of latamoxef given at long intervals may be more effective than intermittent dosing or continuous infusion.

Animals↗
PubMed1986

Isolation, purification and culture of Sertoli cells from immature piglet testes.

Several studies suggest a role of Sertoli cells in the control of Leydig cell steroidogenesis. In order to verify this hypothesis, we have developed a system for the purification of pig Sertoli cells. These cells were then characterized by their morphological appearance in light and electron microscopy, their ability to bind [125I]follicle stimulating hormone (FSH) and their functional capacity as evaluated by adenosine 3',5' monophosphate (cAMP) accumulation and lactate production when in primary culture under basal and FSH-stimulated conditions. Crude Sertoli cell suspensions from immature porcine testes were fractionated on discontinuous Percoll gradients (densities 1.025, 1.039, 1.055, 1.080 g/ml). Highly purified Sertoli cells were contained in the second band (d: 1.039) generated on the gradient. These cells demonstrated morphological and functional integrity as evidenced by binding specifically [125I] FSH and by responding to FSH stimulation (by an increased production of cAMP and lactate after 3 days in primary culture), but not to human chorionic gonadotrophin (hCG). This preparation represents a useful model for the study of Sertoli cell functions and their interation with Leydig cells in the regulation of testicular steroidogenesis.

Animals↗