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Biomedical subjects

P Gilbert

Publications and source records attributed to P Gilbert.

At least 217 records · Page 12Linked to original sources
PubMed1984

The DNA sequence of the mercury resistance operon of the IncFII plasmid NR1.

The DNA sequence has been determined for a 3.8-kilobase region which encodes the mercury resistance (mer) operon of the IncFII plasmid NR1. The sequence reveals four open reading frames which could encode proteins of 12,391, 9,429, 14,965, and 58,781 daltons. On the basis of their sizes, amino acid compositions, hydropathicities, and estimated isoelectric points, the peptides encoded by these open reading frames correspond to the four previously described Hg-inducible proteins detected in minicells carrying mer+ plasmids. The NR1 mer locus is 63.4% GC overall, and the Hg(II) reductase protein sequence is 90% homologous to that of Tn501. The region encoding the merR (positive regulatory) function has three open reading frames. The smallest of these possible merR peptides (6,457 daltons) begins approximately 280 bp to the right of the adjacent IS1b and reads towards the structural genes of the mer operon. The next largest reading frame (13,139 daltons) in the merR region begins 37 bp to the left of the beginning of the smallest peptide and also reads towards the structural genes. The largest reading frame (15,907 daltons) in the merR region lies on the complementary strand and reads away from the structural genes towards IS1b. Although attempts to visualize the merR gene product were not successful, in vitro mutagenesis allows us to eliminate the largest reading frame as a merR candidate. We were also able to show that approximately 50% of the smallest detectable mer peptide (9,429 daltons) is located in the periplasm.

Bacterial Proteins↗
PubMed1983

A monoclonal antibody which detects a cell surface antigen on murine embryonal carcinoma and early mouse embryo stages may recognize a carbohydrate determinant involving alpha-linked galactose.

A rat monoclonal antibody (5D4) apparently specific for murine embryonal carcinoma cells and cells of the pre-implantation embryo is described. It does not react with differentiated cells from a variety of different tumours and tissues of the mouse. Biochemical studies show that the molecules that carry 5D4 antigen are resistant to protease digestion on the cell surface but susceptible to procedures which affect carbohydrate structure. It is likely that this antibody detects a carbohydrate bearing determinant which may include an alpha-linked galactose residue.

Animals↗
PubMed1983

A note on inoculum reproducibility: a comparison between solid and liquid culture.

The level of reproducibility for replicate determinations of drug sensitivity was significantly greater for liquid than for solid cultures and decreased markedly with the density of colonies upon seeded agar plates. Inocula of Escherichia coli and Pseudomonas aeruginosa were significantly less sensitive towards chlorhexidine when derived from liquid rather than solid culture. We therefore suggest that only liquid cultures be used for the preparation of challenge inocula for regulatory tests of antimicrobial activity.

Bacteriological Techniques↗
PubMed1983

Antimicrobial activity and physico-chemical properties of some alkyldimethylbenzylammonium chlorides.

A series of alkyldimethylbenzylammonium chlorides have been synthesized with n-alkyl chain lengths of C1 leads to C18. Octanol/water partition coefficients were determined and the antimicrobial activity assessed as the minimum growth inhibitory concentrations towards twelve strains of micro-organisms, representative of Gram-negative and Gram-positive bacteria, yeasts and fungi. The data were subjected to a numerical analysis. Antimicrobial activity of the compounds was found to be a parabolic function of their lipophilicity and maximized with n-alkyl chain lengths of between C12 and C16. The data fit to quadratic functions estimated for low (C1-C7) and high (C8-C16) alkyl chain length compounds was better than for a single quadratic describing the activity of the complete series (C1-C18). These maximized at log P values corresponding to alkyl-chain lengths of approximately C7 and C14 respectively, and were suggestive of low and high affinity binding sites upon the cell surface. The data analysis allowed the chain lengths of compounds with optimal activity towards the various groups of organisms to be determined. Generally yeasts and fungi were most sensitive towards C12, Gram-positive bacteria towards C14, and the Gram-negative bacteria towards C16. Gram-negative cells were the most resistant towards all the compounds and Gram-positive cells the least.

Bacteria↗
PubMed1983

[Cervical aortic arch. Apropos of a case].

A new case of left cervical aorta is described, affecting a 12-year-old girl. Haemodynamic, CT scan and radiological investigations are described. The only associated abnormality in the present case was hypoplasia of the left vertebral artery. There were two spicules on the medial surface of the descending aorta, possibly embryonic rests. A review is made of the literature and there is discussion of the contribution of different diagnostic techniques to determination of the embryological origin or the abnormality and its possible treatment.

Aorta, Thoracic↗
PubMed1982

Immunocytochemical cell identification in nervous system culture combined with intracellular injection of a blue fluorescing dye (SITS).

SITS, a stilbene isothiocyanate derivative, was injected by iontophoresis into neurons and oligodendrocytes in cultures of mouse spinal cord. The dye readily stains the entire cell. When excited with ultraviolet light it emits a blue fluorescence. Thus, SITS-injected cells may be distinguished from those injected with Lucifer yellow CH. Furthermore, the blue cells can be identified in culture after the cells have been labeled with two different antibodies using rhodamine (TRITC) or fluorescein (FITC) as fluorochromes by the use of appropriate filter combinations.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1982

Flow cytometry of human testicular tissue.

Flow cytometry of testicular tissue from autopsies showed differences in the proportion of substained spermatozoa (1 CA), spermatids (1 CB), diploid 2C nuclei and premeiotic spermatozoa in the 4 C class. The evaluation of the histograms was performed with computer assistance. Healthy accident cases or those delivered in forensic medicine furnished the control values. Patients with hepatic cirrhosis showed a nearly complete loss of the haploid class, while cases with fatty degeneration of the liver demonstrated a reduction. Circulatory insufficiency in cases of acute shock resulted in an increase in the 4C values of meiotic prophase I and a decrease of spermatids. Spermatozoa were normal in these cases. After prolonged shock a nearly complete breakdown of spermatogenesis was observed. In cases of atherosclerosis an irregular degree of reduction was seen. Cancer patients showed a reduction of spermatogenesis in correlation to therapy.

Adult↗
PubMed1982

A laboratory evaluation of a new disinfectant cleaner for fibreoptic instruments.

The antimicrobial activity of Dettox ABC (DTX), a new disinfectant cleaner, developed for use in endoscopy, has been evaluated against sixteen strains of micro-organisms, nine of which were clinical isolates obtained from endoscope washings. In all cases the maximum growth inhibitory and lethal dilutions were considerably greater than those recommended for use (1/25). Time-survival data was determined for DTX (1/750), in hard water, against Pseudomonas aeruginosa, and the effects of horse blood, yeast cells, serum and porcine mucin evaluated. These date indicated that the activity of the product was adversely affected at this dilution by organic matter. Levels of organic debris, which were found capable of neutralizing a 1/750 DTX dilution were included in a multiple challenge of the product with P. aeruginosa at dilutions of 1/25, 1/50 and 1/100 prepared in hard water. Its performance was satisfactory. Similarly, the activity of DTX at these dilutions upon Staphylococcus aureus cells dried in blood and mucin on glass surfaces was satisfactory. The levels of organic debris used in this study were considerably greater than those expected in practice with endoscopes.

Bacteria↗
PubMed1981

Mutagenicity of n-nitrosodiethanolamine and its acetyl derivatives.

The mutagenicity of N-nitrosodiethanolamine and its mono- and di-acetyl derivatives was tested in the S. typhimurium test system, in cytogenetic studies and in the micronucleus test. N-nitrosodiethanolamine had no mutagenic effects towards several strains of S. typhimurium either in the absence or in the presence of metabolic activating systems. Its diacetyl derivative exerted mutagenic effects towards the S. typhimurium strains TA1530 and TA100. Neither compound increased significantly the nubmer of chromosomal aberrations or of micronuclei in mice.

Animals↗
PubMed1981

Application of models for envelope growth to cell length distribution data for Pseudomonas aeruginosa at various specific growth rates.

Cell length distributions were determined for magnesium-limited steady-state populations of Pseudomonas aeruginosa grown in a chemostat at a variety of specific growth rates (0.037-0.621 h-1). The data were subjected to numerical analysis using an iterative procedure based upon the Collins and Richmond (1962) equation and various models for envelope growth. The cell length distributions of cultures growing at specific growth rates in excess of 0.276 h-1 could be modelled assuming constancy of the rate of increase in cell length, and the Zaritsky-Pritchard (1973) step growth model. Cultures growing at microns less than 0.276 h-1 had length distributions which skewed markedly towards the shorter length cells, and were not consistent with either linear, exponential nor step growth models. Pierucci (1978), however, proposed a model of linear envelope growth, which for slowly growing cultures predicted periods without envelope synthesis at the beginning of each division cycle. Application of such a model for slowly growing cultures produced similar skews in the cell length distributions, but could only adequately model the data when the periods of no-growth occurred in mid-cycle.

Models, Biological↗
PubMed1981

Influence of low intensity 2,450 MHz microwave radiation upon the growth of various micro-organisms and their sensitivity towards chemical inactivation.

The non-lethal effects of 2,450 MHz radiation upon vegetative cell of P. aeruginosa and S. aureus have been assessed at low power intensities (1 joule min-1 ml-1) over a prolonged time period (16 h). Results indicated that the cell envelope was a primary target for such radiation. Growth of micro-organisms in the presence of microwaves produced minor structural changes in their cell envelopes which resulted in an alteration of preservative sensitivity. Such changes were not sufficiently great as to result in any alteration of specific growth rates during continuous microwave exposure, neither was motility nor cellular morphology affected.

Benzalkonium Compounds↗
PubMed1980

Genetic effects of chlorinated anilines and azobenzenes on Salmonella typhimurium.

The mutagenicity of 19 herbicide-derived chlorinated azobenzenes and structurally related chlorinated anilines and nitrobenzenes was assayed towards several strains of S. typhimurium, using the plate incorporation method and the fluctuation test, in the presence or in the absence of liver post-mitochondrial fractions, in aerobic and anerobic conditions. Positive results were obtained with 4,4'-dichloroazobenzene, 4,4'-dichloroazoxybene, 3,4-dichloronitrobenzene and, to a much lesser extent, with 3,4,3',4'-tetrachloroazobenzene. No mutagenic effect was observed with 2,3,7,8-tetrachlorodibenzo-p-dioxin in any condition.

Aerobiosis↗
PubMed1980

Continuity of care: does it contribute to quality of care?

Continuity of care is defined and measured in terms of care received from a single physician, from several physicians practicing as a group and from physicians seen through referrals. All patients receiving tonsillectomy and adenoidectomy (T and As) in Manitoba for one year, as well as a group of similar individuals treated with respiratory illnesses but not having T and As, were studied. Several patient and physician characteristics were examined to determine their relationship to continuity of care. Continuity consistently increased with patient age, but appeared unrelated to several other variables. The links between continuity of care and quality of care were explored using process and outcome measures of quality. A cross-lagged panel analysis suggested no casual relationship between continuity and quality. These results contradict those of several other studies; they are important in that continuity of care is shown not to reduce one type of error of commission made by practitioners.

Adenoidectomy↗