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Biomedical subjects

T E West

Publications and source records attributed to T E West.

At least 37 records · Page 2Linked to original sources

Detection of encapsulation in Staphylococcus aureus by use of antiserum agar.

We examined an antiserum agar method to study its reliability in screening Staphylococcus aureus strains for capsule production. The encapsulated S. aureus Smith diffuse strain was compared with its nonencapsulated variant, Smith compact, in CCY medium containing 0.5% NaCl and 5.0% Smith diffuse rabbit antiserum. A halo was visible surrounding colonies of the Smith diffuse strain but not the Smith compact strain. On this same medium, the protein A-producing Cowan I strain possessed a halo that was visible on photographs. Single high-salt medium is known to inhibit protein A production, halo formation by the strains was also compared in 7.5% NaCl medium. The halo surrounding the Cowan I strain was not present when the salt content of the medium was increased. In contrast, the halo surrounding the Smith diffuse strain persisted in the 7.5% NaCl medium. By use of this medium, the antiserum agar technique may be valuable for the identification of encapsulated staphylococci without appreciable interference from protein A.

Agar↗

Detection of anti-teichoic acid immunoglobulin G antibodies in experimental Staphylococcus epidermidis endocarditis.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of rabbit immunoglobulin G (IgG) antibodies to purified cell wall teichoic acids from the Staphylococcus aureus Lafferty strain and three strains of coagulase-negative staphylococci. Significant immunological cross-reactivity occurred only between the teichoic acid of S. aureus and one coagulase-negative preparation. The ELISA was used to determine the serum IgG response to Staphylococcus epidermidis in a rabbit model of aortic valve endocarditis. Blood samples were drawn before inoculation and then every 5 days until death or sacrifice at 32 to 35 days postinoculation. Valve vegetations were culture positive at autopsy in 16 (59%) of the 27 catheterized rabbits. Antibody titers in this culture-positive group and the culture-negative group began to rise as early as day 6. Although both groups demonstrated an antibody response, the culture-positive group attained a significantly higher titer on days 26 and 31. Antibodies also rose in a control group of rabbits without a heart catheter but which were inoculated with bacteria. Again, the antibody titer was significantly less than that for the culture-positive group. This ELISA may be useful for the diagnosis of coagulase-negative staphylococcal infections in humans.

Animals↗

Evaluation of a commercial counterimmunoelectrophoresis kit for detection of Staphylococcus aureus teichoic acid antibodies.

A commercial kit from Diagnostica, Inc., Miami Fla., was studied for its ability to detect antibodies to the teichoic acids of Staphylococcus aureus. A comparative study of the Diagnostica counterimmunoelectrophoresis (CIE) system and our gel double-diffusion method was undertaken with 156 serum samples from 142 patients. Included were 25 cases of staphylococcal and non-staphylococcal endocarditis, 30 cases of S. aureus bacteremia, 19 cases of nonbacteremic S. aureus infection, 39 cases of hospitalized patients without a staphylococcal infection, and 29 normal controls. Agreement between methodologies was attained in 138 (88.5%) of the 156 samples tested and in 127 (89.4%) of the 142 patients. Of 13 patients with culture-proven S. aureus endocarditis, significant antibody titers were found in all patients (100%) by CIE and in 12 patients (92.3%) by double diffusion. No significant titers were found in normal sera by CIE, but four sera were positive by double diffusion. Of 80 sera from patients with no evidence of S. aureus infection, 4 (5.0%) were positive by CIE and 7 (8.8%) were positive by double diffusion. The Diagnostica CIE kit appears to provide a suitable means for the detection of deep-seated S. aureus infections.

Antibodies, Bacterial↗

The effects of energy and carbohydrate restriction in patients with chronic diabetes mellitus.

Thirty-five freshly presenting, diabetic patients received 5 hour, 100 g oral glucose tolerance tests when first seen and after a period of carbohydrate and energy restriction. After treatment, the significant improvement in glucose tolerance was accompanied by increased insulin secretion and lower concentrations of blood ketone bodies, lactate, glycerol, FFA, triglycerides, cholesterol and pre-beta lipoprotein. There were no significant changes in serum growth hormone or blood pyruvate concentrations. Improvement in glucose tolerance was greater in patients who were obese (greater than 115% of desirable body weight for height) on presentation and was related to the improvement in insulin secretion and the diminished lipolysis. An hypothesis to explain the changes in insulin secretion is prosposed. Eleven out of the 35 patients showed sufficient improvement in glucose tolerance to require no treatment other than diet.

Adolescent↗

Is the growth-hormone response to insulin due to hypoglycaemia, hyperinsulinaemia or a fall in plasma free fatty acids?

Seven normal male volunteers were given a 2 h intravenous infusion of insulin (2 mu kg-1 min-1). During the first hour, in which nomoglycaemia was maintained by glucose infusion, no detectable increase in growth hormone (GH) secretion occurred. When controlled symptomatic hypoglycaemia was produced during the second hour of the insulin infusion a brisk rise in plasma GH concentration was observed in all the subjects studied. Since it was possible that the falls in the concentration of plasma free fatty acids (FFA) occurring during infusion of insulin also acted as a stimulus to GH release the study was repeated in four subjects but normoglycaemia was maintained throughout the entire 2 h period of insulin infusion. In these experiments there was no rise in plasma GH concentration although a similar fall in plasma FFA was produced. These results clearly indicate that hypoglycaemia per se was the important stimulus to GH secretion and not hyperinsulinaemia or a lowering of plasma FFA. Furthermore there appeared to be a threshold hypoglycaemic stimulus to GH secretion. In no subject was a rise in plasma GH seen without a fall in plasma glucose greater than 1.4 mmol/l. Prolonged mild hypoglycaemia did not stimulate GH secretion.

Blood Glucose↗

Evaluation in clinical practice of Dextrostix and the Eyetone Reflectance Meter.

Venous blood glucose concentration measured by Dextrostix-Eyetone Reflectance Meter method were compared with conventional enzymatic measurements of plasma glucose in the same 373 blood samples over the range of 0.55-22.2 mmol/l (10-400 mg/100 ml). Agreement between the two methods was good up to 5.5 mmol/l (100 mg/100 ml) but above 11.1 mmol/l (200 mg/100 ml) the Dextrostix-Eyetone method gave higher results for glucose concentration. The Dextrostix-Eyetone method is a reliable means of confirming or refuting the clinical diagnosis of hypoglycaemia and is useful in the day-to-day management of diabetes mellitus in situations where insulin dosage requirements are varying and where access to clinical laboratory facilities are not readily available.

Blood Glucose↗

Horner's syndrome and headache due to carotid artery disease.

Horner's syndrome was accompanied by ipsilateral pain in the head, face, or neck in eight patients. In all cases angiography showed narrowing of the internal carotid artery in a pattern compatible with dissection within the arterial wall. In one patient in whom this diagnosis was substantiated by surgical exploration biopsy of the arterial wall showed changes typical of cystic medial necrosis. It is suggested that this clinical presentation constitutes a distinct syndrome.

Adult↗

Acromegaly caused by pulmonary carcinoid tumours.

Two patients are described whose acromegaly was cured by removal of a bronchial carcinoid tumour. One had an enlarged pituitary fossa and evidence is presented that in this patient the tumour was not secreting growth hormone. The evidence available suggests that the tumour was producing a growth hormone releasing substance. It is suggested that some cases of the pluriglandular syndrome may be secondary to small bronchial carcinoid tumours that produce substances as yet unidentified, that stimulate the growth and hyperactivity of other endocrine tissue.

Acromegaly↗