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Biomedical subjects

J R Walton

Publications and source records attributed to J R Walton.

89 records · Page 5Linked to original sources
PubMed1969

New hemolysin (gamma) produced by Escherichia coli.

A new hemolysin (gamma) of Escherichia coli, active in the absence of viable bacteria, has been recognized in mutants resistant to nalidixic acid. Nalidixic acid affects either the production or release of the hemolysin.

Animals↗
PubMedDate not supplied

An investigation of the prevalence of the toxigenic types of Clostridium perfringens in horses with anterior enteritis: preliminary results.

Equine anterior enteritis is an acute syndrome with unknown aetiology, although salmonellosis and infection with Clostridium perfringens have both been suggested as potential causes. The main aim of this preliminary study was to compare the prevalence of toxigenic types of C. perfringens in clinically healthy horses and in horses with anterior enteritis. From horses admitted with colic at Phillip Leverhulme Large Animal Hospital in 1995-1996, samples of gastric reflux, small intestinal contents and faeces were taken for isolation of C. perfringens. Five of those horses were admitted as anterior enteritis cases, of which C. perfringens was isolated in pure culture in all five horses. Two of the anterior enteritis cases from which viable bacterial counts had been performed revealed 10(6) CFU/g faeces C. perfringens. Samples of gastric reflux and small intestinal contents submitted from one of these horses revealed 10(4) CFU/mL and 10(5) CFU/mL respectively. The number of C. perfringens observed in the gastric reflux was considered significant as the total volume removed was 12 L. The counts observed in faeces taken from horses admitted with anterior enteritis, were significantly higher than the <10(2) CFU/g faeces observed in faeces from healthy horses and horse presenting with colic and with other diagnoses. The major toxigenic types of C. perfringens in both healthy and diseased horses are being investigated using the polymerase chain reaction (PCR) to amplify target DNA sequences of the toxin genes. Primers have been designed from the published DNA sequences of the enterotoxin, alpha, beta, epsilon and iota toxin genes. PCR products obtained from NCTC strains of C. perfringens have been cloned and the sequenced, to verify that the amplicon sequence is correct. Initial typing suggests that C. perfringens type A is the predominant toxin type isolated from healthy horses and horses with colic with other diagnoses.C. perfringens strains isolated from horses with anterior enteritis are of type D.

Journal Article↗
PubMedDate not supplied

Low tryptophan diets delay reproductive aging.

Newly weaned female rats fed diets severely deficient in the essential amino acid tryptophan show marked delays in reproductive aging, with conception and delivery occurring as late as 36 months. The rate of aging in these rats seems inversely related to both their early growth rates and the accessibility of brain tryptophan. The subsequent age retardation may depend on a reduction in both early cell loss and rate of brain maturation.

Animals↗
PubMedDate not supplied

Salmonellosis.

Explore the source record for details and available documents.

Animals↗
PubMedDate not supplied

A bright field/fluorescent stain for aluminum: its specificity, validation, and staining characteristics.

A sensitive bright field/fluorescent histochemical staining method has been developed that reveals endogenous aluminum in subcellular structures. The method, achievable within 30 min, is based on phloxine B and phosphotungstic acid, with ethanol differentiation. Hematoxylin is used for nuclear and fast green FCF for cytoplasmic counterstaining. To test the method's specificity, we incubated living neuroblastoma cells overnight in culture media containing aluminum, calcium, iron, copper or zinc, or no added metal ions. After fixing the cells and applying the staining method, only cultures exposed to aluminum stained magenta. Applying the method to paraffin embedded tissue sections pretreated with one of two chelating agents that remove aluminum demonstrated less magenta staining in the chelated sections than in adjacent unchelated sections. Immersing sections overnight in solutions containing exogenous aluminum had no observable effect on staining for endogenous aluminum; therefore, it is unlikely that any exogenous aluminum present in histological reagents would alter the method's staining results.

Aluminum↗