[Plasma and urine beta-thromboglobulin determination in the detection of thrombocyte hyperactivation in diabetic nephropathies]

Serum creatinine, immunoreactive serum and urine beta-2-microglobulin, plasma and urine thromboglobulin, plasma thromboxane-B2 levels and daily protein excretion were determinated in 61 insulin treated diabetic patients, comparing the different patient groups (complication free, nephropathy without azotaemia and nephropathy with azotaemia) with the control subjects. In the groups of all diabetic patients plasma and urine beta-thromboglobulin and plasma thromboxane-B2 levels were higher that in the controls. There was a positive significant correlation between urine beta-thromboglobulin and beta-2-microglobulin in the group without complication, and between the plasma beta thromboglobulin and beta-2-microglobulin, and plasma beta thromboglobulin and thromboxane levels in the diabetic group with azotaemia. In contradiction to some previous assumptions, the increased level of plasma beta-thromboglobulin reflects a real platelet hyperactivation also in patients with diabetic nephropathy. At the same time urine beta-thromboglobulin also increases. Determination of urine beta-thromboglobulin is more simple with less possibility of methodological error.

Platelet membrane fluidity in type IIA, type IIB and type IV hyperlipoproteinemia

Fluorescence spectroscopy, a very sensitive index for measuring the biophysical properties of living cell systems, was used to examine the structural order of intact, resting, gel-filtered platelets from hyperlipidemic subjects (n = 48, 25-70 years) and normolipemic subjects (n = 34, 19-68 years). Fluorescence anisotropy (r[s]), which is inversely related to membrane fluidity, was estimated using 3 different fluorescent dyes, DPH, TMA-DPH, and 6-AS, known to label different regions of biological membranes. Increased membrane fluidity was observed in type IIB (n = 24, 36-62 yrs; r[s] = 0.0692 +/- 0.09) and type IV (n = 10, 33-57 yrs; r[s] = 0.058 +/- 0.006) hyperlipidemics in comparison to type IIA (n = 14, 25-70 yrs; r[s] = 0.086 +/- 0.019) and control subjects (n = 24, 28-68 yrs; r[s] = 0.079 +/- 0.012). The temperature dependency of r[s]-DPH values was significantly different (P less than 0.01) in platelets from type IIB and type IV patients compared to type IIA and control subjects of similar age. A significant positive correlation (P less than 0.005) between membrane fluidity and age was found only in healthy control subjects (n = 34, 19-68 yrs). Despite significant (P less than 0.01) differences in plasma lipid concentrations in hyperlipidemic patients and controls, significant ex vivo relations between membrane fluidity and lipoprotein concentrations, free fatty acid distribution, and increased age were found only in healthy control subjects. Plasma levels of thromboxane as well as serum selenium concentrations did not significantly differ between hypercholesterolemic, hypertriglyceridemic, and control subjects.

[Plasma concentration of lipoprotein(a) and distribution of its subtypes in the healthy population of Hungary]

Authors determined the plasma levels of total cholesterol, HDL-cholesterol, apoprotein B-100 (apo B-100), apoprotein A-I (apo A-I) and lipoprotein(a) in 202 (139 female and 63 male) randomized blood donors. The phenotypes of lipoprotein(a) were detected by SDS-polyacrylamide gelelectrophoresis and Western blotting. The average plasma total cholesterol concentration of this Hungarian population was 5.7 +/- 1.1 mmol/l. The other lipoprotein parameters were HDL-cholesterol: 1.36 +/- 0.04 mmol/l; and the apoprotein B-100 concentration: 70 +/- 17.4 mg/dl. In these parameters no difference between males and females could be found. The average plasma apoprotein A-I in females was 156.3 +/- 23.6 mg/dl and in males 143.8 +/- 26.8 mg/dl and the difference was statistically significant (p less than 0.01). The average lipoprotein(a) concentration of this population was 10.5 +/- 13.5 mg/dl and there was no significant difference between males and females (9.0 +/- 10.7 and 13.9 +/- 17.7 mg/dl, respectively). The distribution of plasma Lp(a) was highly skewed in the direction of low concentration values. In females a moderate bimodial distribution could be demonstrated. Documented by several authors lipoprotein(a) level higher than 30 mg/dl serves as an independent risk factor for atherosclerosis. In this population only 9.4% of subjects had lipoprotein(a) concentrations over this limit (5.9% female and 3.5% male). The relative alle frequency of different phenotypes showed the following distribution: B 0.007, S1 0.015, S2 0.154, S3 0.231, S4 0.230 and null 0.362. In this population the F phenotype could not be detected.

Physiological and clinical importance of lipoprotein(a)

Lipoprotein(a) is a genetically regulated trait, and its concentration in serum seems to be independent from that of other lipoprotein classes. It can be detected by ultracentrifugation in the d = 1.05-1.12 g/ml density range. Based on epidemiological observations Lp(a) is an independent risk factor for coronary heart disease. Its structure resembles LDL, but contains, in addition to apolipoprotein B 100, the disulphide-linked apoprotein(a). Apoprotein(a) shares a striking homology with plasminogen, consisting multiple repeating domains similar to kringle IV, a single kringle V and an inactive protease segment. The heterogeneity of Lp(a) complex is determined by the apoprotein(a) moiety. It seems so, that atherogenic properties of Lp(a) can be explained by its binding to glycosaminoglycans and inhibition of fibrinolysis. This latter effect is carried out by the kringle domains, which can interact with the plasminogen activators and plasmin binding sites on endothelial surface. The atherogenic properties of Lp(a) are expressed over 30 mg/dL serum concentration. Well-known antilipidemic drugs do not affect its serum level and genetically determined phenotype. Diseases leading to secondary hyperlipoproteinemia may influence the lipoprotein(a) level, too.

[Necrobiosis lipoidica]

Authors report results of light and electron microscopic studies of dermal symptoms of 8 patients with non-diabetic lipoid necrobiosis. In all cases microangiopathy in skin, characterized by thickening of basal lamina and its becoming multilayered, and by narrowing of lumen of veins. Histological picture of dermal symptoms showed tuberculoid structure, which is characteristic of symptoms of non-diabetic necrobiosis. Orgastoplasmatic corpuscles found in plasma cells are conditioned upon atypical immune globulin synthesis.

The effect of Etofibrate (Lipo-Merz) on "in vitro" cellular immune response and on lipid parameters of men with myocardial infarction and with arteriosclerosis obliterans

Earlier specific cell-mediated immune reactions and their modulation by different drugs were reported against human vascular antigens in patients with vascular diseases. Presently the effect of Etofibrate (Lipo-Merz) was studied on cellular immune reactions induced by human aorta with lipid plaques and on serum lipid parameters in 46 men with acute myocardial infarction and in 48 men with arteriosclerosis obliterans compared to 40 healthy controls. Leucocyte migration test and lymphocyte-mediated cytotoxicity were repeatedly investigated in the presence of human aortic extract with or without Etofibrate (2 micrograms/50 microliters). The degree of leucocyte migration inhibition and of lymphocyte-mediated cytotoxicity proved to be similar in hypherlipaemic and in normolipaemic groups. Etofibrate could decrease cellular immune reactions both in hyperlipaemic and normolipaemic patients, but its effect was more expressive in the hyperlipaemic than normolipaemic group. Three months later a reduction of cellular immune reactions was found mainly in normolipaemic patients. Ten patients with myocardial infarction and 10 arteriosclerosis obliterans patients were treated with Etofibrate (900 mg/day) for 12 weeks. After therapy, cholesterol, triglycerides, LDL concentrations were reduced, HDL level was increased and the rate of LDL:HDL decreased. Leucocyte migration inhibition and lymphocyte-mediated cytotoxicity were also diminished. This time the cellular immune reactions of treated patients were only slightly reduced "in vitro" by Etofibrate in contrast with non treated hyper- and normolipaemic patients in whom cellular immune reactions were decreased by Etofibrate similarly to the first determinations. On the basis of our observations Etofibrate may be useful in the therapy of arteriosclerotic vascular diseases with or without hyperlipaemia, because it could decrease the cellular sensitization against aortic tissue.

[Correlation of thrombocyte reactivity and serum levels of HbA1c, cholesterol and creatinine in diabetes mellitus]

The thrombocyte reactivity and values of HbA1c, serum cholesterine and creatinine have been examined in 121 insulin-treated and 70 not-insulin-treated diabetic patients and in 98 healthy persons. The thrombocyte functions of patients ranged according to the microangiopathic complications and of control groups matched according to age and sex were analysed with comparative statistics. Positive correlation was found in diabetes between the serum creatinine and cholesterine levels and the aggregating agents' (adrenaline, ADP, and collagen) limit concentrations (p less than 0,05-0,001). Close correlation seems to be between the worsening of renal functions and the decrease of thrombocyte sensitivity in diabetes: The hypercholesterinemia observable in nephropathic diabetes did not lead to the hyperaggregability known in familial hypercholesterinemia. Thus it appears likely that the cholesterine-level increase in the serum does not influence directly, but rather by the effects in connection with its origin, differently the thrombocyte reactivity.

[Necrobiosis lipoidica without diabetes mellitus (diagnostic and therapeutic possibilities)]

The goal of the present study was to follow the clinical behaviour of 6 non diabetic patients (5 females and 1 male, aged 23-68) suffering from necrobiosis lipoidica. Thickening of the basalmembrane of capillaries could be confirmed by electron microscopy, although the histological structure of skin alterations are not different from those observed in diabetes mellitus. Three patients (2 females and one male) showed impaired glucose tolerance, 2 other patients had increased levels of total cholesterol, whereas one patient suffered from both metabolic disturbances. After treatment with ASA (acetylsalicylic acid, 1.0 g/day) and dipyridamole (200 mg/day) for six weeks, the decrease of platelet in vitro aggregation in platelet rich plasma could be observed by stimulation with arachidonic acid, epinephrine, ADP and collagen, respectively. Healing of the exulceration of skin lesion could be detected by the use of the combined treatment of ASA and dipyridamole in 4 cases.

Lp(a) lipoprotein concentration in serum of patients with heavy proteinuria of different origin

We measured serum cholesterol, triglyceride, and lipoprotein Lp(a) concentrations in serum of 37 patients with massive proteinuria of different origin, comparing values with those for age- and sex-matched controls and finding significantly increased Lp(a) concentration in the total group of patients compared with controls. Lp(a) concentration was not correlated with serum cholesterol, triglyceride, serum creatinine, daily urinary protein loss, or selectivity index. Selecting the patients according to their histological diagnosis obtained by renal needle biopsy, we found divergent results in seven patients with minimal change disease (MCD) compared with 11 patients with membranoproliferative glomerulonephritis. Lp(a) in MCD patients did not differ from that controls (101 +/- 102 and 90 +/- 115 mg/L) and correlated positively with total daily urinary protein loss (r = 0.7962, P less than 0.05). In contrast, the patients with membranoproliferative glomerulonephritis had significantly higher Lp(a) values than the controls (219 +/- 222 mg/L), and Lp(a) concentrations correlated negatively with the daily protein loss in urine (r = -0.6545, P less than 0.05). The most surprising results were the marked Lp(a) concentrations in serum of three patients with primary amyloidosis and nephrosis syndrome. Our results indicate a regulatory role of the kidney in the metabolism of Lp(a) and different effects on the serum Lp(a) concentration, depending on the type of damage to renal tissue.

[Distribution of lipoprotein fractions in men with arteriosclerosis obliterans]

The fasting serum total cholesterol, triglyceride, LDL-cholesterol, VLDL-cholesterol and HDL-cholesterol were determined in fifty male patients with arteriosclerosis obliterans (ASO) confirmed by angiography. Twenty five of the patients were hyperlipidemic and significantly elevated concentration of atherogenic lipoproteins could be demonstrated compared to age matched control group of healthy subjects (n = 20). The HDL-cholesterol level in the patient group was significantly decreased even if comparing normolipemic patients to controls. In the postprandial phase of cholesterol loading (600 mg) the serum total cholesterol, LDL-cholesterol and HDL-cholesterol levels did not change in both groups. A marked increase in serum total triglyceride, VLDL-cholesterol and VLDL/HDL-cholesterol ratio was detected and the differences between the two groups regarding these lipoprotein fractions were increased. The importance of cholesterol-rich VLDL in ASO and its relationship to familial dysbetalipoproteinemia are discussed.

Binding of fibronectin to human lipoproteins

High molecular mass adhesive glycoprotein plasma fibronectin binds to isolated HDL and LDL lipoprotein fractions in a solid phase radioimmunoassay. Mean dissociation constants of interaction of fibronectin and immobilized HDL and LDL lipoproteins isolated from eight patients with type IIa and type IV hyperlipoproteinemia are 7.8 +/- 3.2 X 10(-7) mol/l and 6.8 +/- 2.6 X 10(-7) mol/l, respectively. Fibronectin can also bind to HDL and LDL isolated from six healthy subjects with mean dissociation constants of 2.07 +/- 0.45 X 10(-6) mol/l and 2.25 +/- 0.48 X 10(-6) mol/l, respectively. The binding is not dependent on the presence of divalent cations. Fibronectin-lipoprotein interaction is inhibited by soluble lipoproteins. There is no observable interaction between fibronectin and VLDL fraction. Binding of fibronectin to HDL and LDL lipoproteins can have an in vivo significance, since the interaction may play a role in the metabolism, deposition of lipoproteins into the vessel wall and in atherogenesis.

[Differences in platelet aggregation in various microangiopathic complications of diabetes mellitus]

In vitro platelet aggregometry with epinephrine, adenosine-diphosphate, collagen and arachidonic acid was performed in 201 patients with diabetes, and in 106 healthy subjects. Those patients who were free of nephropathy showed hyperaggregability to collagen and arachidonic acid, and also to epinephrine and adenosine diphosphate, when neuropathy occurred. Patients with nephropathy, both with and without azotaemia, had diminished platelet responses to each of the four aggregating agents as compared to age- and sex-matched controls. Aggregability was not dependent on type of diabetes. It is concluded that diabetic nephropathy is characterized by decreased in vitro reactivity of platelets. Further researches are necessary to explain in vitro hypoaggregability besides the numerous evidence of in vivo hyperfunction of platelets in diabetes.

The effects of probucol on QT/QS2 relation and systolic time intervals

The QT, QTc, QS2 intervals, pre-ejection period-left ventricular ejection time ratios and serum lipoprotein levels were measured in 8 patients with primary hypercholesterolemia before and after a 3-month therapy with probucol, 1 g/day. Both QT and QTc intervals increased significantly, whereas no significant changes were observed between the pre- and post-treatment QT/QS2 and pre-ejection period-left ventricular ejection time ratios. These results help to explain why treatment with probucol, while effecting a prolongation of the QTc interval, does not result in serious arrhythmias in man.

Lipoprotein (a) and plasminogen are immunochemically related

Earlier studies demonstrated that lipoprotein (a), a lipoprotein of high atherogenicity, possesses proteolytic activity. In this report, we provide evidence that the lipoprotein (a)-specific antigen, apoprotein (a) is immunochemically related to plasminogen. This was demonstrated by polyclonal antisera from rabbit, sheep and horse, and with three monoclonal antibodies from mouse. Using immunospecific adsorbers against lipoprotein (a), all plasminogen could be adsorbed from lipoprotein (a)-positive and apparently lipoprotein (a)-negative plasma. As an additional similarity to plasminogen, lipoprotein (a) binds selectively to lysine-Sepharose, but with a somewhat lower affinity. In an assay system for measuring the fibrinolytic activity challenged with streptokinase, lipoprotein (a) prolonged strikingly the fibrinolysis time under certain experimental conditions.

Platelet hyper- and hypoaggregability in different microangiopathic complications of diabetes mellitus

In vitro platelet aggregometry was performed in 201 patients with diabetes mellitus, and in 106 controls. The complication-free and retinopathic patients showed hyperaggregability to collagen and arachidonic acid, and also to epinephrine and adenosine diphosphate when neuropathy occurred. Patients with nephropathy, both with and without azotemia, had diminished in vitro platelet responses to each of the four stimuli as compared to age- and sex-matched controls. These characteristics were independent of the type of diabetes. It is concluded that diabetic nephropathy is characterized by reduced platelet in vitro reactivity. Further research is necessary to explain in vitro hypoaggregability in contrast to the numerous proofs of in vivo hyperfunction of platelets in diabetes.

Effect of growth hormone on serum lipoproteins in growth hormone deficiency

The effect of growth hormone treatment on the plasma lipoproteins was studied in 13 growth hormone deficient children. The pretreatment total cholesterol level was moderately (p less than 0.05) higher in growth hormone deficiency and it decreased significantly under the effect of growth hormone administration. This decrease was due to the reduction of HDL-cholesterol in the first week and to the decrease of LDL-cholesterol after one month of treatment. The level of LDL-cholesterol returned to normal at one month. The plasma triglyceride level increased significantly under the effect of growth hormone in the first week and returned to normal after one month. This change was due to the increase of VLDL-triglyceride level. There was no difference in the cholesterol and triglyceride concentrations of growth hormone deficient children with normal or subnormal plasma thyroxine concentrations.

[Cholesterol elimination in the urinary tract]

The case of a 50-year-old female patient who had been passing "calculi" containing cholesterol for 10 years is presented. Previously, abdominal surgical interventions had been carried out several times and therefore a fistula between the digestive and urogenital system was suspected. This, however, could not be confirmed either by radiological or laboratory techniques. A II/a type of hyperlipoproteinemia was found in the serum, but its correlation to the calculi could be excluded.