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Biomedical subjects

K G Taylor

Publications and source records attributed to K G Taylor.

72 records · Page 4Linked to original sources

Lipoprotein lipase and adipose tissue and plasma triglyceride clearance in patients with primary hypertriglyceridaemia.

1. The activity of lipoprotein lipase (E.C.3.1.1.3) extracted and released from adipose tissue has been measured in obese subjects with mild or severe hypertriglyceridaemia. The Intralipid tolerance test has been studied as a measure of in vivo clearance of exogenous triglyceride from plasma. 2. Plasma triglyceride clearance was reduced in patients with severe hypertriglyceridaemia (> 4 mmol/l) and this was associated with reduced activities of extracted lipoprotein lipase in adipose tissue compared to patients with mild hypertriglyceridaemia (2--4 mmol/l). 3. A course of insulin therapy (20 u/day) for 1 week increased the extracted, but not the released component of the enzyme from adipose tissue of hypertriglyceridaemic patients. 4. Serum (25% v/v) potentiated the release of lipoprotein lipase from adipose tissue of normo- but not hypertriglyceridaemic patients. 5. The effect of serum on enzyme release was abolished if lipoprotein-deficient serum was used. Addition of very low density lipoprotein (VLDL) or high density lipoprotein (HDL) restored the ability of delipidated serum to augment release of enzyme from adipose tissue, but this was not observed with low density lipoprotein (LDL). 6. It is suggested that a defect in the release of lipoprotein lipase activity in adipose tissue may contribute to the development of hypertriglyceridaemia in this group of patients.

Adipose Tissue↗

Association of protein with the cell wall of Streptococcus mutans.

Cell walls from Streptococcus mutans were prepared by conventional technique and subjected to a series of extraction procedures involving classical protein solvents. The extracted walls contained several non-peptidoglycan amino acids and were also amenable to radiolabeling with [125I]sodium iodide and chloramine T. The cell walls could be chemically modified with tetranitromethane and diazo-1H-tetrazole, suggesting the presence of tyrosine or histidine or both. Flourescence spectra of the walls revealed the presence of either tyrosine or tryptophan. Several proteases, including pronase, trypsin, subtilisin, and proteinase K, removed some of the label from the walls. In contrast, treatment of the walls with salts or denaturants did not result in the solubilization of label. When the walls were solubilized with mutanolysin and subjected to chromatography, three peaks of radioactivity with apparent molecular weights of 73,000, 39,000, and 9,600 were observed. Wall digests subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single band of radioactivity corresponding to an apparent molecular weight of 79,000. Isoelectric focusing of labeled wall digest gave rise to two major bands of radioactivity with isoelectric points of approximately 2.4 and 5.6. The results suggest that the cell wall of S. mutans contains tightly and possibley covalently bound polypeptide molecules. We propose that the cell wall polypeptides of S. mutans serve as factors in the attachment of the bacteria to smooth surfaces.

Amino Acids↗

Insulin-independent diabetes: a defect in the activity of lipoprotein lipase in adipose tissue.

The activity of lipoprotein lipase (E.C.3.1.1.3.) has been measured in adipose tissue from insulin-independent diabetics with hypertriglyceridaemia, non-diabetics with hypertriglyceridaemia and control patients, all of whom were obese. Although all groups showed an increase of plasma insulin after oral glucose, both the diabetic and nondiabetic hypertriglyceridaemics had impaired activities of lipoprotein lipase in adipose tissue compared to the obese normals (p less than 0.02, p less than 0.03, respectively). A course of insulin therapy (20 u.o.d.) for one week increased the activity of lipoprotein lipase extracted from adipose tissue, lowered plasma triglycerides and improved triglyceride clearance from plasma in a group of diabetics with hypertriglyceridaemia (mean plasma triglyceride 8.7 mmol/l). Our results suggest that a feature in the development of insulin resistance in adult diabetics may be a failure of maintenance of key intracellular enzyme activities involved in lipid metabolism.

Adipose Tissue↗

Lipoprotein lipase activity in human adipose tissue during induced hypertriglyceridaemia.

Needle biopsies of adipose tissue and blood samples were obtained before and at short intervals after a "bolus" injection of 10% Intralipid. Lipoprotein lipase activities were measured in acetone--ether extracts of the tissue samples. Levels of serum triglyceride began to fall less than 5 min after the injection of the Intralipid with a half-life of 20 min. During this time interval, no significant changes were observed in the activities of lipoprotein lipase in adipose tissue. A patient with a severe hypertriglyceridaemia (Type V) underwent plasma exchange with a reduction in serum triglyceride levels from 11 to 4 mm/l. There was a parallel fall in adipose tissue lipoprotein lipase activity. We conclude that lipoprotein lipase in adipose tissue is unaltered during experimental hypertriglyceridaemia and that the activity of the enzyme in adipose tissue is probably not reduced as a secondary feature of an elevated plasma triglyceride level.

Adipose Tissue↗

Clofibrate increases lipoprotein-lipase activity in adipose tissue of hypertriglyceridaemic patients.

Clearance of plasma-triglycerides and activity of lipoprotein lipase in adipose tissue were studied in six hypertriglyceridaemic patients before and after a week of clofibrate therapy (2 g/day). Plasma-triglycerides decreased significantly from 6.85 +/- 1.1 to 2.66 +/- 0.29 mmol/l and triglyceride clearance increased significantly from 1.3 +/- 0.2 to 2.4 +/- 0.4%/min. There were concomitant significant increases in heparin-releasable lipoprotein lipase (95 +/- 16 to 181 +/- 34 nmol free fatty acids/10(6) cells/h) and in extractable lipase (88 +/- 14 to 179 +/- 28 nmol free fatty acids/10(6) cells/h). It is concluded that an important effect of clofibrate may be to increase the levels of adipose-tissue lipoprotein lipase and thereby improve the clearance of plasma-triglycerides.

Adipose Tissue↗

Sex differences in the relationships between obesity, alcohol consumption and cigarette smoking and serum lipid and apolipoprotein concentrations in a normal population.

In this study of a normal population from a Midland factory, obesity showed a direct relationship to serum triglyceride and cholesterol levels in males but not in females. High-density lipoprotein (HDL) cholesterol and apolipoprotein A1 levels were not related to obesity in either sex. Alcohol consumption was associated with increased serum triglyceride levels in males but not in females and serum HDL cholesterol levels were also higher in male drinkers only. Cigarette smoking was associated with increased serum triglyceride levels in both sexes but HDL cholesterol levels were reduced only in female smokers. Apolipoprotein A1 levels were not related to smoking in females.

Alcohol Drinking↗

The treatment of poorly controlled non-insulin-dependent diabetic subjects with granulated guar gum.

The treatment of poorly controlled, non-compliant non-insulin-dependent diabetic subjects for one month with guar granules (Guarem) was associated with significant improvements in fasting serum glucose and insulin and urinary glucose excretion. No significant change was observed in either oral glucose tolerance, erythrocyte insulin receptor binding, serum calcium, cholesterol, triglyceride or HbA1. Subjects reported significant side effects including excessive flatus, increased bowel frequency and fullness. The limited advantages of Guarem treatment must be measured against the possibility of these side effects which to a large extent may be avoided by special attention to the means of administration. Prudent supplementation of the diet with Guarem has undoubted potential for diabetic control.

Blood Glucose↗

Hyperthyroidism associated with hyperemesis gravidarum.

Hyperemesis gravidarum is an uncommon presentation of hyperthyroidism in pregnancy which is usually attributable to autoimmune (Graves') disease. While this condition necessitates treatment with antithyroid drugs, a syndrome of transient hyperthyroidism associated with hyperemesis gravidarum that resolves spontaneously is also recognised. Differentiation between these two conditions may prove problematic in practice. We report two cases of hyperthyroidism associated with severe hyperemesis gravidarum. Intractable hyperemesis continued in one patient despite normalisation of circulating free thyroid hormone concentrations with carbimazole. Neither patient exhibited clinical or immunological features of autoimmune thyroid disease, suggesting in retrospect that they had the syndrome of transient hyperthyroxinaemia associated with hyperemesis gravidarum rather than Graves' disease. The role of antithyroid drugs in the treatment of self-limiting transient hyperthyroidism associated with hyperemesis gravidarum requires clarification.

Adult↗

A 'fail-safe' screening programme for diabetic retinopathy.

OBJECTIVE: To improve screening for diabetic retinopathy in a hospital diabetic clinic through the use of the audit process. DESIGN: Comparison of an existing system of screening for diabetic retinopathy (a specialist optometrist using ophthalmoscopy alone) with a new system in which a specialist optometrist examined retinal Polaroid photographs taken through pharmacologically dilated pupils and combined this with ophthalmoscopy in all cases except when the photographs were perfect and definitely showed no retinopathy. In this new system, the optometrist could discuss cases of uncertainty with a diabetes physician while the patient was still in the clinic with eyes dilated. SETTING: Inner city hospital diabetes clinic. SUBJECTS: 289 hospital diabetic clinic patients not already attending an ophthalmologist; a consecutive series of 144 such patients for the first audit, 145 for the repeat audit. MAIN OUTCOME MEASURES: Assessment of each screening system against a gold standard. For the first audit this was agreement by two of four diabetes physicians, who combined examination of the photographs with the findings from dilated ophthalmoscopy, on the classification of the retinae of each patient, guided by standard European criteria. For the second audit, the gold standard was enhanced by discussing the photographs and findings of all patients with an independent ophthalmologist. For patients requiring referral, a second ophthalmologist also commented on the case. RESULTS: The addition of retinal photography to universal pupil dilatation, and the availability of diabetes physician backup to discuss cases of uncertainty, greatly increased the optometrists' detection rate. Sensitivities for the first (ophthalmoscopy only) and second (ophthalmoscopy plus photography plus diabetologist back-up) audits were, respectively, 71.4% vs 100% for sight-threatening retinopathy, 33% vs 100% for retinopathy requiring six-month review, and 40.3% vs 97.2% for any retinopathy (p = 0.002). CONCLUSIONS: Optometrists specialising in diabetic retinopathy using Polaroid retinal photography and ophthalmoscopy, both through dilated pupils, backed up by experienced diabetologists to discuss cases of uncertainty, could form the basis of a retinopathy screening service that accurately identifies and categorises retinopathy and does not miss sight-threatening cases.

Diabetic Retinopathy↗