Biomedical subjects
Publications and source records attributed to R Bakir.
The very rare inherited hypolipoproteinemias are of great help to understand the relations between lipoproteins and atherosclerosis; moreover, they raise questions in this field, which are discussed in this paper.
The authors recall the clinical and histo-chemical aspects of xanthomas and their relations with serum lipids and lipoproteins disturbances. The experimental works in animals and in human clinic are then reviewed. At the light of these results the xanthoma development physiopathology and its relation to atherogenesis is considered.
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Three cases of bowel angiodysplasia with digestive bleeding were reported. In all cases, diagnosis was confirmed by arteriographic and/or histological data. Angiodysplasia of the colon was the most often an acquired and degenerative disease, and most commonly affecting patients after the seventh decade of life. This condition was a frequent and misinterpreted cause of bleeding per rectum in patients after fifty years. Selective superior mesenteric angiography, after colonoscopy (except during major bleeding) was the best investigation, showing pathognomonic images and specifing the site, often located in the caecum and/or ascending colon. Treatment was surgical, but endoscopic methods provided encouraging results.
A 76-year-old man was found to have a false hypertriglyceridemia due to a 40-fold increased glycerolemia. This metabolic change was due to a deficiency in glycerol kinase (ATP:glycerol phosphotransferase, EC 2.7.1.30) activity in the cells of this patient as shown by incubation of his white blood cells with [14 C]glycerol. Several chromatographic analyses and quantitative assays were performed on plasma and urine of this patient and of his relatives. The small number of this family's members did not allow to specify the mode of transmission of this genetic trait.
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In a retrospective study about 600 hyperlipoproteinaemic patients (390 men and 210 women, mean age 47), xanthelasma palpebrarum was infrequent (25 cases or 4.16 p. 100), since it was only at the third rank of chronic extra-vascular lipid deposits after arcus corneus and tendineous xanthomas. It was twice as frequent in men (5.12 p. 100) as in women (2.38 p. 100) and of regularly increasing occurrence until the sixth decade. Among the atherosclerotic risk factors, only obesity was significantly associated. The existence of atherosclerotic diseases was observed more frequently in patients with xanthelasma palpebrarum (40 p. 100) than in total hyperlipoproteinaemic population (28 p. 100). In a second retrospective study concerning 29 patients (15 men and 14 women, mean age 50), selected from the only presence of one or several xanthelasma palpebrarum, a lipoproteinaemic abnormality was observed in 27 cases (93 p. 100): 23 patients (71 p. 100) were hyperlipoproteinaemic (type IIa, IIb or IV) and in 4 out of 6 normolipidemic patients we observed an abnormal lipoprotein cholesterol distribution (LDL + VLDL cholesterol increase and HDL cholesterol decrease). In this group, we observed in nine patients (31 p. 100) unknown atherosclerotic diseases and tendineous xanthomas in other nine patients (31 p. 100).
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A 56-year-old woman with familial heterozygous type II hyperlipoproteinaemia and tendinous xanthomas, presented the unusual findings of acquired supravalvular aortic stenosis associated with a congenital stenosis of the orifice. Analysis of clinical, paraclinical, and particularly pathological data confirmed the existence of several associated lesions: congenital hypoplasia of the aortic ring and proximal aorta, calcified valve stenosis probably increased by the dyslipidaemia, and finally and principally, supravalvular stenosis formed of a veritable circular rim of atheromatous material, making up a second haemodynamic obstacle. It is probable that the pre-existing congenital aortic lesions in this case, apart from the hyperlipoproteinaemia, account for the observation, not previously reported in a heterozygous type II hyperlipoproteinaemia, of massive supravalvular atheromatous deposits. This latter of acquired lesion is described in 9 cases reported in the literature with a homozygous form of familial hypercholesterolaemic xanthomatosis, the atheromatous deposits in the proximal aorta appearing earlier in these patients, and in the absence of pre-existing anatomical anomalies.
In a study started in 1973 and still in progress (1100 patient-years so far) fenofibrate in daily doses of 200-400 mg consistently proved effective, without any loss of activity with time. The drug lowered serum total cholesterol levels by 17-27% in type IIa, IIb and III primary hyperlipoproteinaemia (HLP) and serum triglyceride levels by 35-51% in type IIb and III HLP and by 46-54% in type IV HLP. Clinically and biologically fenofibrate was always well tolerated, even after 5 years' treatment. Side-effects were uncommon (4%) and mild, and they obliged to discontinue treatment in only 1% of the patients. Abnormal manifestations encountered during therapy appeared to be fortuitous. The effects of the drug on cardiovascular morbidity and mortality could not be determined from this trial. In a short-term study involving 21 patients with type IIa and IIb primary HLP, fenofibrate in doses of 200-400 mg/day produced a significant decrease in total cholesterol, LDL-cholesterol and apoprotein B. It is also reduced triglycerides and VLDL-triglycerides in type IIb HLP. The increase in HDL-cholesterol observed under fenofibrate was significant in type IIa HLP but not in type IIb HLP. In both types, there was a significant rise in HDL: LDL + VLDL ratio.
Probucol was used to treat 16 patients with atherogenic hyperlipoproteinaemia. The duration of treatment varied between 30 days (16 patients) and 510 days (4 patients). The drug was found to be remarkably well tolerated, without any clinical or biological side-effects. There was an 8 to 13 p. cent reduction in plasma total cholesterol, a 4 to 17 p. cent reduction in LDL cholesterol and a very favorable increase (19 to 23 p. cent) in the HDL/LDL + VLDL cholesterol ratio. Little or no change was found in triglyceride and HDL cholesterol levels.
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The authors determined in 3 populations (37 controls, 59 asymptomatic hyperlipemias, and 20 cases of arterial hyperlipemia) the total cholesterol, the HDL cholesterol and the LDL + VLDL cholesterol and their ratio by two methods : precipitation by concanavalin A and ultracentrifugation (AirFuge). These various lipid parameters were compared between 3 populations in order to determine their more or less discriminant character; furthermore, was established the degree of correlation between the results obtained by precipitation with concanavalin A and by ultracentrifugation. The results show : firstly, that the LDL + VLDL was significantly higher and the ratio HDL/LDL + VLDL significantly lower in hyperlipemia and in arterial disease compared with controls ; the HDL was significantly lower in arterial disease than in controls. No lipid parameter permitted one to differentiate between asymptomatic hyperlipemia and arterial disease. Furthermore, the correlation determined by the chi square method was very strong between the results obtained by precipitation with concanavalin A and ultracentrifugation as the coefficient of simple linear regression is very little different from the value + 1. They emphasize the interest of the method of precipitation by concanavalin A which is simple, rapid and very reliable.