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Biomedical subjects

C R Wilson

Publications and source records attributed to C R Wilson.

At least 91 records · Page 5Linked to original sources
PubMed1978

Rapid procedure for the detection of plasmids in Staphylococcus epidermidis.

A rapid, reproducible, mini-volume assay capable of detecting staphylococcal plasmid DNA in the range of 0.8 to 32 megadaltons has been developed. The assay employs lysostaphin-mediated lysis of cells followed by a short, low-speed centrifugation and does not require treatment with ribonuclease or protease or deproteinization with phenol. A period of only 24 h may be required to detect the presence and size of a plasmid once an organism has been isolated. This method has been used to study the plasmid ecology of Staphylococcus epidermidis and to correlate the presence or absence of plasmids with tetracycline, chloramphenicol, neomycin, penicillin, and cadmium resistances.

Anti-Bacterial Agents↗
PubMed1978

Characterization and construction of molecular cloning vehicles within Staphylococcus aureus.

Four chloramphenicol resistance (Cm) and four tetracycline resistance (Tc) plasmids from Staphylococcus aureus were characterized by restriction endonuclease mapping. All four Tc plasmids had molecular masses of 2.9 megadaltons (Mdaltons) and indistinguishable responses to seven different restriction endonucleases. The four Cm plasmids (pCW6, pCW7, pCW8, and pC221) had molecular masses of 2.6, 2.8, 1.9, and 2.9 Mdaltons, respectively. The four Cm plasmids also differed both in the level of resistance to Cm and in susceptibility to retriction endonucleases. Single restriction endonuclease sites contained within each plasmid included the following: in pCW6 for HindIII, XbaI, HpaII, and BstEII; in pCW7 for HindIII, BstEII, BglII, HaeIII, and HpaII; in pCW8 for HindIII, HaeIII, and HpaII; in pC221 for HindIII, BstEII, and EcoRI. The molecular cloning capabilities of pCW8 and pC221 were determined. Cm and erythromycin resistance (Em) recombinant plasmids pCW12, PCW13, and pCW14 were constructed and used to transform S. aureus 8325-4. A 2.8-Mdalton HindIII fragment from plasmid pI258 was found to encode Em resistance and contain single sites for the retriction endonucleases BglII, PstI, HaeIII, and HpaII. The largest EcoRI fragment (8 Mdaltons) from pI258 contained the HindIII fragment encoding Em resistance intact. Cloning of DNA into the BglII site of pCW14 did not alter Em resistance. Cloning of DNA into the HindIII site of pCW8 and the HindIII and EcoRI sites of pC221 did not disrupt either plasmid replication of Cm resistance.

Anti-Bacterial Agents↗
PubMed1978

Xenon contrast enhancement in computed body tomography.

Xenon has been investigated as a contrast medium for conventional radiography, and in vitro as a contrast medium for computed tomography. The authors evaluated xenon contrast enhancement in vivo for CT body scanning. Nine healthy subjects had CT scans before and during xenon inhalation. Concentrations of xenon used varied from 10--50%. Consistent useful changes in attenuation from inhaled xenon were found in the lung but not in abdominal organs. Lung attenuation varied linearly with the xenon concentration in the inhaled gas. Inhalation of xenon concentrations greater than 30% resulted in side effects. Further studies are required to demonstrate whether xenon contrast enhancement is of diagnostic value in computed tomography.

Clinical Trials as Topic↗
PubMed1977

Psychiatric morbidity in a tropical diseases unit.

A sample of 208 consecutive admissions to the Hospital for Tropical Diseases was screened for psychiatric illness. A psychiatric morbidity of 31-8% was found. If severe personality disorders are included in the figures then the overall psychiatric morbidity rises to 49-6%. The reasons for these findings are discussed.

Adolescent↗
PubMed1977

Comparison of methods for the isolation of Salmonella from imported frog legs.

Four methods of sample preparation were compared for their relative efficiency in recovering Salmonella from imported frog legs. No significant difference (P greater than 0.10) was observed in the efficiency of submersion, blending, and stomaching methods, but rinsing recovered significantly fewer (P less than 0.01) Salmonella-positive frog legs than the other three methods. No significant difference (P less than 0.25) was observed in the number of positive frog legs recovered by selenite cystine or tetrathionate broth. Salmonella-Shigella agar, when streaked from either of these broths, gave significantly fewer (P less than 0.01) Salmonella-positive frog legs than brilliant green, bismuth sulfite, xylose lysine deoxycholate, and Hektoen-enteric agars. Use selective agars, resulted in detection of an additional 11 and 6 Salmonella-positive frog legs, respectively. A variety of serotypes, mostly uncommon, was recovered. One Salmonella serotype (6,14,24:r,i:e,n,z15), possessing a heretofore unreported antigenic formula, was isolated.

Bacteriological Techniques↗
PubMed1977

Bone-mineral content of the femoral neck and spine versus the radius or ulna.

The interrelationship between the bone-mineral content of sites on the radius or ulna and that of the femoral neck and lower thoracic vertebrae of twenty-four human skeletons was determined. The average correlation coefficients, -/r, were 0.82 and 0.57. Regression analysis showed that the bone-mineral content of the radius provides a good estimate of the bone-mineral content of the femoral neck (standard error of estimate approximately 16 per cent). Multiple regression analysis using the age of the subject and the bone-mineral content of the radius provides an equation with a similar standard error of estimate for the vertebrae.

Adult↗
PubMed1976

A study of the symptom patterns of psychiatric referrals in a tropical diseases unit.

Undoubtedly the commonest psychiatric conditions seen in patients from the tropics are reactive depression and hysterical illness. These may both be seen as responses to stress, often over a prolonged period. Although typical depressive and hysterical syndromes are seen in all races, severe tiredness seems to be the principal hysterical symptom amongst Europeans as opposed to bizarre somatic symptoms in Negroes and Asians. Headaches are an important depressive sign in Negroes and Asians. Diarrhoea and abdominal pains may be linked directly to anxiety and depression or may emerge as an unconscious defence against insoluble problems.

Abdomen↗
PubMed1976

Analysis of autolysins in temperature-sensitive morphological mutants of Bacillus subtilis.

The content and distribution of autolysin were measured in temperature-sensitive morphological mutants of Bacillus subtilis. Strains RUB1000 and RUB1012 grew as rods at 30 C. At 45 C the mutants contained disproportionately less teichoic acid than peptidoglycan and grew as irregular spheres. The amount of enzyme that could be extracted from rods was at least 31 times the amount extracted from spheres. The rate of autolysis of cell walls was 7- to 28-fold greater in rods than in spheres. The low activity found associated with the cell walls of spheres was not compensated for by larger amounts of autolytic activity in the cytoplasm. No activity was found in the growth medium at either temperature. The failure of the mutant cells to autolyze was due to low amidase activity and relatively resistant cell walls. Revertants of RUB1012 were isolated that had 13, 23, and 55% of the normal proportions of teichoic acid when grown at the nonpermissive temperature. Cell walls from the revertants were as sensitive to added amidase as the wild-type strain. None of the revertant strains regained the wild-type ability to produce more amidase at 45 C. However, the deficiency in autolysin observed with RUB1012 was partially restored in revertants containing higher proportions of teichoic acid.

Amidohydrolases↗
PubMed1976

Culture method for detection of Salmonella in dried active yeast: collaborative study.

A method for detecting Salmonella in dried active yeast was subjected to collaborative study. This method employs trypticase soy broth as the pre-enrichment medium, a sample-to-broth ratio of 1:10, and subsequent transfers to lauryl sulfate tryptose broth and tetrathionate before streaking onto selective agars. Each collaborating analyst received ten 25 g samples of dried active yeast. Duplicate 25 g samples were each inoculated with Salmonella oranienburg at a low level (28 cells) and a high level (107 cells). Similarly, duplicate 25 g samples were each inoculated with S. senftenberg at a low level (30 cells) and a high level (114 cells). The remaining 2 of 10 samples were not inoculated. Results from 12 of 13 collaborators were evaluated. Only 2 (8.2%) of the 24 low level S. oranienburg samples were reported incorrectly as negative. Twelve of the analysts detected S. senftenberg at both levels and S. oranienburg at the high level in the inoculated samples. Results from 12 collaborators used in the final evaluation show that 117 of 119 (98.3%) collaborative determinations are in agreement. The official final action method for the detection and identification of Salmonella, 46.013-46.026, has been revised official first action to include applicability to dried active yeast.

Culture Media↗
PubMed1975

Evaluation of a medium for the rapid recovery of Escherichia coli from shellfish.

A medium (A-1) which shortens the time necessary to identify and enumerate Escherichia coli found in estuarine water was evaluated for use for recovery of E. coli found in shellfish. Productivity of E. coli by this medium was comparable to that of the lengthier American Public Health Association method, and the occurrence of false positives was substantially reduced.

Bivalvia↗
PubMed1975

The moroccan food snail, Helix aspersa, as a source of Salmonella.

A total of 270 samples, nine lots of 30 samples each, of imported Moroccan food snails was examined for the presence of Salmonella. Eighty-four samples (an overall incidence of 31.11%) and all nine lots contained Salmonella. No significant difference (P greater than 0.25) in the number of positive samples was observed by using either selenite cystine both or tetrathionate broth when the samples had been pre-enriched in lactose broth. When used as direct selective enrichments with samples not pre-enriched in lactose broth, tetrathionate broth was significantly (P less than 0.05) more productive than selenite cystine broth. The overall detection of Salmonella-positive samples by direct enrichment was significantly greater (P less than 0.001) than by pre-enrichment. A variety of uncommon serotypes occurrence and incidence, and the concomitant human health potential, of Salmonella in one species of live, imported food snails.

Culture Media↗
PubMed1975

Thermal susceptibility of Salmonella in the Moroccan food snail, Helix aspersa.

Thirty samples of 10-15 Helix aspersa food snails were examined for Salmonella by a surface rinsing method and by analysis of whole snails rinsed with 70% ethanol. Thirteen samples were positive by the rinsing method and 6 were positive by whole snail analysis, with this difference being significant (P less than 0.01). Although Salmonella contamination in H. aspersa appeared to be predominantly surface, the pathogen was also found within the snail meat. The ability of surface and subsurface Salmonella organisms to survive in cooked snails was determined in 90 samples. Thermocouple readings indicated that an internal temperature of at least 200 degrees F (93 degrees C) was reached within the snail meat during cooking by a typical recipe. This temperature was sufficient to kill both surface and subsurface Salmonella in 29 samples positive for the pathogen prior to heating. A variety of serotypes representing several somatic groups was isolated.

Food Contamination↗
PubMed1971

Salmonella screening procedure with tests for beta-galactosidase and flagellar antigens.

Differentiation of Salmonella from other gram-negative bacilli requires several biochemical and serological tests. A simplified 24-hr screening procedure has been devised which allows discarding of large numbers of isolates (picked from selective plating media) before they are subjected to this extensive testing. Cultures of gram-negative organisms isolated to triple sugar-iron slants during routine examination of products for Salmonella were tested for the presence of beta-galactosidase and Salmonella flagellar antigens. beta-Galactosidase-positive cultures which did not agglutinate in polyvalent flagellar antiserum were considered to be nonsalmonellae. Of 1,103 Salmonella cultures tested, none of the 61 different serotypes was missed by this procedure, whereas 673 (82.3%) of 818 nonsalmonellae were excluded from further testing. This screening procedure eliminates most nonsalmonellae and augments the proportion of cultures undergoing further biochemical and serological testing which will be confirmed as Salmonella.

Agglutination Tests↗
PubMedDate not supplied

Taxines: a review of the mechanism and toxicity of yew (Taxus spp.) alkaloids.

This literature review summarizes relevant information and recent progress regarding the scientific investigations of taxine alkaloids. Taxines are the active, poisonous constituents in yew plants (Taxus spp.) and have been implicated in animal and human poisonings. Several taxine alkaloids have been isolated and characterized through the use of high performance liquid chromatography, mass spectroscopy, and nuclear magnetic resonance. Recently, as a result of electrophysiological investigations, significant progress has been made with regard to their pharmacological and toxicological mechanisms of action. Current investigations suggest that their chief action is on cardiac myocytes resulting in heart failure and death in instances of animal and human poisoning.

Alkaloids↗
PubMedDate not supplied

Dichromatic absorptiometry of vertebral bone mineral content.

A dichromatic photon absorptiometric technique for the in vivo measurement of the bone mineral of the spine is discussed. A high purity, high activity 153Gd source which has photons of predominantly 44 and 100 keV was used as the transmission source. The transmission scans were performed on a modified Ohio Nuclear whole body rectillinear scanner. The precision of four measurements on three individuals and three measurements on one individual over a one month period was 2.3% (coefficient of variation). The accuracy determined by measurements of phantoms with known concentrations of dipotassium hydrogen phosphate solutions was 1.2% (standard error of estimate). This technique can be applied in most well equipped nuclear medicine departments.

Absorption↗