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Biomedical subjects

B Lewis

Publications and source records attributed to B Lewis.

At least 289 records · Page 16Linked to original sources
PubMed1976

Metabolism of very low density lipoproteins in hyperlipidaemia: studies of apolipoprotein B kinetics in man.

The metabolism of very low density lipoprotein-B (VLDL-B) peptide was studied in nineteen subjects with endogenous hypertriglyceridaemia (Types V, IV and IIb), three patients with heterozygous familial hyperbetalipoproteinaemia (Type IIa) and eight healthy subjects, by reinjecting autologous radioiodinated VLDL. The kinetics of VLDL-B peptide were followed. The mean turnover rate of VLDL-B peptide was significantly higher in the hypertriglyceridaemic group than in the control group but a considerable overlap in turnover rate was found between these groups. The patients with heterozygous familial hyperbetalipoproteinaemia had a normal turnover rate of VLDL-B peptide. A significant positive correlation was found between the turnover rate of VLDL-B peptide and VLDL-triglyceride concentration in the whole series. It is concluded that the underlying defect in endogenous hypertriglyceridaemia is heterogeneous. Overproduction of VLDL is a major determining factor in some patients whereas a reduced clearance is the determining factor in others.

Adult↗
PubMed1976

Intravenous fat-tolerance test in ischaemic heart disease and peripheral vascular disease.

1. The intravenous fat-tolerance test and serum lipid and lipoprotein measurements were carried out in ninety-three normal subjects, fifty-one patients with ischaemic heart disease and thirty patients with peripheral vascular disease. 2. The fractional turnover rate of exogenous triglyceride was significantly slower in patients with ischaemic heart disease and in patients with peripheral vascular disease than in normal men. The rate was also slower in normal men than normal women. 3. Serum triglyceride and cholesterol concentrations were higher in both vascular disease groups than in control subjects. 4. The proportion of both groups of patients who had a subnormal fractional turnover rate of exogenous triglyceride was 35%, and 32% of patients had hypertriglyceridaemia in the fasting state; 27% of patients were hypercholesterolaemic. 5. Although the intravenous fat-tolerance test did not provide significantly better discrimination between cardiovascular patients and control subjects than did measurement of serum triglyceride, the results suggest that hypertriglyceridaemia in such patients may be separable into a group in which impaired triglyceride clearance may be partly responsible, and a group in which overproduction of serum triglyceride may be the major mechanism of the hyperlipidaemia.

Adult↗
PubMed1976

The evaluation of lipoprotein changes during gemfibrozil treatment.

During treatment with gemfibrozil, 1200 mg daily, total serum triglyceride levels were reduced in 7 of the 11 patients, owing chiefly to a fall in VLDL triglyceride levels. Total serum cholesterol responded variably, falling in a majority of patients with hypercholesterolaemia. High density lipoprotein cholesterol rose during treatment in patients who had either hypertriglyceridaemia or hypercholesterolaemia.

Cholesterol↗
PubMed1975

Plasma-lipids and glucose/insulin relationship in non-insulin-requiring diabetics with and without retinopathy.

Serum-lipid concentrations and their relationship to blood-glucose and serum-insulin were examined in non-insulin-requiring diabetics, 62 with and 45 without retinopathy. The age, sex-body-weight, and duration of known diabetes was comparable in the two groups. All were treated by diet only or diet and oral hypoglycaemic agents. Patients with retinopathy had higher fasting serumtriglyceride and serum--cholesterol levels than those without. Compared with a non-diabetic population, significantly more diabetics with retinopathy had raised derum-lipids. The lipid concentrations did not correlate with body-weight, serum-thyroid-stimulating-hormone levels, renal involvement, or fasting blood-sugar. While the blood-sugar concentrations were similiar in the two groups the absolute insulin increment and the relative insulin response to a 50 g. oral glucose load were significantly lower in those with retinopathy than in those without. The impairment of insulin response correlated significantly with the frequency of hyperlipidaemia. It is suggested that insulin deficiency with secondary hyperlipidaemia is characteristic of diabetic patients with retinopathy.

Adult↗
PubMed1975

The relationship between dietary fat composition and plasma cholesterol esterification in man.

1. Cholesterol esterification has been studied in the plasma of subjects on diets rich in saturated or polyunsaturated fat. 2. The diet rich in polyunsaturated fat was associated with lower rates of plasma cholesterol esterification in vitro. The data suggest that there was a reduction of plasma lecithin-cholesterol acyltransferase activity as well as decreased ability of the lipoprotein substrates of the enzyme to support esterification. 3. On this diet, there was no change in the proportion of the plasma cholesterol esterified but the plasma cholesterol and triglyceride concentrations were reduced.

Adult↗
PubMed1975

Conversion of very low density lipoprotein to low density lipoprotein. A metabolic study of apolipoprotein B kinetics in human subjects.

The interrelationship between apolipoprotein B in very low density lipoprotein (VLDL-B) and in low density lipoprotein (LDL-B) was studied in seven normal and hyperlipidemic men and women, with purified radioiodinated VLDL. The time-course of the appearance of radioactivity in LDL was followed. As the specific activity curves intersected at the masimal height of the LDL-B curve, it was inferred that all or most LDL-B peptide is derived from VLDL-B peptide. This transfer was further quantitated in seven normotriglyceridemic subjects by simultaneous i.v. injection of purified 131I-VLDL and 125I-LDL. By a deconvolution method, a quantitative description of the rate of entry of 131Ivldl-b into 131I-LDL-B was derived by analysis of 131I-LDL-B and 125I-ldl-b radioactivity in plasma. The results indicate that approximately 90% of VLDL-B mass is converted into LDL-B in subjects with normal serum triglyceride concentrations. The synthetic rates of VLDL-B and LDL-B peptide were simultaneously measured in six normal subjects, and two patients with heterozygous familial hypercholesterolemia (type IIa). The turnover rates for VLDL-B and LDL-B peptide were similar in these subjects. The findings in the three parts of this study were consistent with the view that most if not all VLDL-B is converted into LDL-B peptide, and most if not all LDL-B is derived from VLDL-B peptide in normotriglyceridemic subjects.

Adult↗
PubMed1975

Serum lipoprotein abnormalities in ischaemic heart disease.

Quantitative lipoprotein level data was obtained from healthy subjects and patients with ischaemic heart disease or peripheral vascular disease in four European communities. Hypertriglyceridaemia, due mainly to an increase in VLDL triglyceride, was commoner in London and Uppsala than in Naples and Geneva. In three communities there were significant increases in total serum cholesterol due to both increases in LDL and in VLDL cholesterol. Hypercholesterolaemic and hypertriglyceridaemic status were over-represented in both ischaemic heart disease and peripheral vascular disease patients.

Cholesterol↗
PubMed1974

Serum lipoprotein abnormalities in patients with ischaemic heart disease: comparisons with a control population.

The frequency and nature of abnormalities of serum lipoproteins have been studied, using quantitative techniques, in 143 patients with ischaemic heart disease (I.H.D.). Rigorous selection criteria were used. The findings were related to the distribution of lipoprotein concentrations in a carefully screened control population. Hyperlipoproteinaemia occurred in 55% of patients and in 11 out of 15 patients aged less than 40 years. Raised triglyceride and cholesterol concentrations in very low density lipoprotein were the most frequent abnormalities followed by raised cholesterol content of low density lipoprotein. In young patients high density lipoprotein levels were subnormal. Hyperlipoproteinaemia of W.H.O. types IIa, IIb, III, IV, and V all seemed to be over-represented in I.H.D. I.H.D. patients with type IIa, IIb, and IV abnormalities were all significantly younger than I.H.D. patients with normal lipoprotein levels.

Adult↗
PubMed1974

Experience with simplified scheme of treatment of hyperlipidaemia.

A series of 57 hyperlipidaemic patients have been investigated clinically and by measurement of cholesterol and triglyceride levels and inspection of stored serum. Two had secondary (alcoholic) hyperlipidaemia. Those with primary disorders were allocated to three groups believed to require different optimal therapy. At one year 51 of these 55 patients had lipid levels within a predetermined normal range and two others showed improvement. Despite the large number of primary hyperlipidaemic states our results suggest that in most patients successful treatment can be given according to simple classification into three therapeutic categories.

Alcoholism↗