Oxidation and uptake of LDL by monocyte-derived macrophages from blood of patients with IHD

The main goal of this study was to test our hypothesis that monocyte-derived macrophages of patients with ischemic heart disease (IHD, MP_IHD) are in vivo prestimulated (primed) or stimulated cells. Their capacity for LDL oxidation and uptake exceeds that of macrophages from healthy donors (MP_N). Monocytes were isolated from blood of 18 healthy donors and 25 IHD patients and LDL preparations were obtained from plasma of 16 healthy donors (LDL_N) and 15 patients with familial hypercholesterolemia (LDL_H). Aerobic incubation of LDL_N or LDL_H with MP_IHD resulted in earlier accumulation (by 1 h) of TBARS in LDL, earlier aggregation of LDL (1 h vs 3 h in the case of MP_N), more pronounced LDL apoB fragmentation as well as increased LDL uptake with the increase in accumulation of total cholesterol (TCh; by 1.8–2.1-fold, p < 0.05–0.01) and the decrease in cell viability compared with MP_N (p < 0.01). MP_IHD and MP_N exhibited more effective oxidation and uptake of LDL_H than LDL_N and in most tests this capacity (to oxidize and uptake LDL) increased under hypoxic conditions. These results demonstrate that macrophages of IHD patients are in vivo stimulated cells and that this stimulation, especially in combination with hypercholesterolemic LDL and local or generalized hypoxia, represent serious predisposition for onset or progression of atherosclerosis in IHD patients. The express test model based on MP_IHD may be used for estimation of monocyte/macrophage stimulation in IHD patients as well as for optimization of drug therapy and screening new antiatherosclerotic and antiischemic drugs.     

Lipid composition of cells and low-density lipoproteins in blood serum of human and some vertebrate species

To establish interaction of atherogenic low-density lipoproteins (LDL) with the erythrocyte membrane, the content of lipid components in blood cells and serum LDL was studied in healthy people (donors) and in 12 species of vertebrates (the mammals non-predisposed to atherosclerosis — birds and fish). Lipid composition of blood cells and LDL was also analyzed in patients with pathologies: ischemic heart disease (IHD), bronchial asthma (BA), and chronic obstructive bronchitis (COB), as well as in 2 species of mammals predisposed to atherosclerosis, in whose blood LDL predominated. The content of lipids in the blood cells and LDL of the studied vertebrates has been found to depend on their taxonomy and on the clear trends either for an increase in the cholesterol content and a decrease in the phosphatidylcholine level in patients, particularly with IHD, or for a rise of the ratio of the content of the more saturated sphingomyelin and cholesterol to the less saturated phosphatidylcholine from the lower to the higher organisms, including humans (donors). The highest levels of free cholesterol in blood cells of total cholesterol in LDL, as well as of parameters of ratio of the cholesterol/phosphatidylcholine content have been revealed in patients, especially with IHD, and in the mammals predisposed to atherosclerosis, i.e. in representatives with predominance of blood LDL, in contrast to donors and the mammals resistant to atherosclerosis. The highest parameters of lipid components were determined in blood cells and LDL in patients with IHD. The lipid LDL composition affects directly the composition and ratio of lipids in blood cells.     

Insulin and Non-esterified Fatty Acid Metabolism in Asymptomatic Diabetics and Atherosclerotic Subjects

Glucose, insulin and non-esterified fatty acid (NEFA) metabolism was studied in 18 patients (mean age 49) with ischemic heart disease (IHD) who did not have any concurrent disorder known to affect glucose tolerance.Significant hyperglycemia and hyperinsulinemia were observed in the IHD patients after oral glucose. The serum NEFA declined to a lower level in IHD patients than in normal subjects who received glucose.In response to hypoglycemia following the oral administration of sodium tolbutamide the serum NEFA in IHD patients rose to a higher level in the rebound phase than in normal subjects. This rise was preceded by a sharp decline in the concentration of circulating insulin.In 72% of the patients (IHD sub-group) the blood glucose values after oral glucose satisfied the criteria for the diagnosis of diabetes mellitus. The metabolic changes following oral glucose in the IHD sub-group and in asymptomatic diabetics (AD), free of clinical atherosclerosis and with similar impairment in glucose tolerance, were compared. Despite insignificantly lower insulin concentrations, the AD showed a significantly lesser fall in circulating NEFA than did the patients in the IHD sub-group. After oral sodium tolbutamide the IHD sub-group patients showed a greater insulin response and a greater rebound increase in circulating NEFA than did the AD.These differences in response to oral glucose and to sodium tolbutamide suggest that the pathogenesis of the impaired glucose tolerance in IHD may be different from that responsible for abnormal carbohydrate tolerance in asymptomatic diabetics without evident atherosclerosis. The abnormalities demonstrated in glucose, insulin and NEFA metabolism may play a role in the genesis of the hyperlipoproteinemia and atherosclerosis of IHD. One possible mechanism leading to hyperlipoproteinemia in ischemic heart disease compatible with the data is discussed.     

The charge and atherogenicity of low density lipoproteins.

It is concluded on the basis of literature data, that apolipoprotein B-100 is the most high-molecular, hydrophobic, and positive charged protein compared to the other apoproteins of the plasma lipoproteins. Low density lipoproteins of healthy subjects, mainly containing apo B-100, have little heterogeneity on both charge and isoelectric point, in spite of heterogeneity on sizes and apolipoprotein composition. The reason of formation of subfraction with elevated negative charge is the damage with the free radicals and/or aldehydes. The reason of formation of more cationized subfraction is unclear. LDL charge changes are noted in some diseases and syndromes (ischemic heart diseases, familial hyper-alpha-lipoproteinemia, Tangier disease, X-bound ichthyosis and, possibly, others). Some IHD patients treatment with antioxidants leads to the disappearance of negative charged LDL subfraction, that shows participation of peroxidation products in their formation. Electrical characteristics of LDL of tissue fluids and of aorta wall differ essentially from those of the same class plasma lipoproteins. Lipid peroxidation and influences of several enzymes play the main role in these differences.     

Content of the main lipid components in blood serum lipoproteins of human and of some animal species

Using precipitation method, low-density (LDL) and high-density (HDL₂ and HDL₃) lipoproteins were isolated from blood serum of human (donors and patients with ischemic heart diseases—IHD, bronchial asthma—BA, chronic obstructive bronchitis—(COB) and mammals predisposed (pig, rabbit) and resistant (rat, mink, Arctic fox) to atherosclerosis, of birds (hen, pigeon), of bony fish (trout, white-fish, pike-perch, pike, bream, burbot), and of cartilaginous fish (sturgeon, white sturgeon). From each lipoprotein group, lipids were extracted, separated by thin-layer chromatography, and analyzed quantitatively by spectrophotometric method. In phosphatidylcholine and HDL₂ cholesterol esters, bound fatty acids (FA) were determined by gas-liquid chromatography. The main amount of total cholesterol has been established to be present in human LDL, especially in the cases of IHD, and in LDL in mammals predisposed to atherosclerosis. In mammals resistant to atherosclerosis and in fish the almost entire cholesterol was revealed in HDL. The phospholipid (phosphatidylcholine) was represented by the ω6-series. Acids of the ω3-series accounted for a negligible percentage, especially in IHD. On the contrary, the HDL FA composition in poikilothermal animals (fish) was characterized by a very high content of polyunsaturated FA of the ω3-series. It is concluded that by the example of several studied species and of human, composition of lipid components in animal lipoproteins has a non-stable character and is submitted to changes. Their most pronounced modifications with a negative trend were revealed in human LDL and HDL in IHD.     

Lipid composition of cells and low-density lipoproteins in blood serum of humans and some vertebrates species

To investigate interaction of atherogenic low-density lipoproteins (LDL) with erythrocytic membrane, the content of lipid components in blood cells and serum LDL was studied in human in norm (donors) and in 12 species of vertebrates (the mammals non-predisposed to atherosclerosis - birds and fish). Lipid composition of blood cells and LDL was analyzed also in patients with pathologies: ischemic heart disease (IHD), bronchial asthma (BA), and chronic obstructive bronchitis (COB), and in 2 species of mammals predisposed to atherosclerosis, in whose blood LDL predominates. The content of lipids in cells and LDL of the studied vertebrates has been found to depend on their taxonomy and the clear trends both to an increase of the cholesterol content and to a decrease if the phosphatidylcholine level in patients, particu- larly with IHD, and on a rise of the ratio of the content of the more saturated sphingomyelin and cholesterol to the less saturated phosphatidylcholine from the lower to the higher organisms, including humans (donors). The highest levels of free cholesterol in blood cells, of total cholesterol in LDL, and of ration of the cholesterol/phosphatidylcholine content have been revealed in patients, especially with 1HB, and in the mammals predisposed to atherosclerosis, i. e., in representatives with predominance of blood LDL, unlike donors and the mammals resistant to atherosclerosis. The highest parameters of lipid components were determined in cells and LDL inhuman with IHD. The lipid LDL composition affects directly the composition and ratio of lipids in blood cells.     

Surface binding and catabolism of low-density lipoprotein by circulating lymphocytes from patients with abetalipoproteinaemia, with observations on sterol synthesis in lymphocytes from one patient.

Surface binding of low-density lipoprotein (LDL), degradation of LDL protein and sterol synthesis were investigated in freshly isolated lymphocytes from normal and abetalipoproteinamic human subjects. LDL binding as a function of LDL concentration showed no evidence of the presence of high-affinity binding sites in fresh lymphocytes from either group of subjects. The rate of degradation of LDL protein by lymphocytes from the patients was no greater than that from the normal subjects and, in the fresh lymphocytes of the one patient studied, sterol synthesis was not increased. We conclude that the formation of LDL receptors and the synthesis of sterol in circulating lymphocytes are largely suppressed and that in normal subjects this may be due to the presence of some plasma constituent other than LDL, possibly the apoE protein. This conclusion is discussed in relation to the possible contribution of LDL receptors to the degradation of LDL protein in vivo.     

Native and modified low-density-lipoprotein interaction with human platelets in normal and homozygous familial-hypercholesterolaemic subjects.

The binding of low-density lipoproteins (LDL) as well as LDL modified by cyclohexanedione (CHD-LDL) to gel-filtered platelets (GFP) and its effect on platelet function were studied in normal and in homozygous familial hypercholesterolaemic (HFH) subjects. Only normal-derived LDL could significantly compete with normal 125I-labelled LDL for binding to normal platelets. When GFP from normal subjects were incubated with normal LDL at concentrations of 25-200 micrograms of protein/ml, platelet aggregation in the presence of thrombin (0.5 i.u./ml) was increased by 65-186%. CHD-LDL, at similar concentrations, caused the opposite effect and decreased platelet aggregation by 26-47%. Both LDL and CHD-LDL (100 micrograms/ml) from HFH patients, when incubated with normal GFP, caused a significant reduction in platelet aggregation (33 and 50% respectively). When HFH-derived platelets were used, both patient LDL and CHD-LDL (but not the normal lipoprotein) could markedly compete with the patient 125I-labelled LDL for binding to the platelets. LDL and CHD-LDL (100 micrograms/ml) from normal subjects decreased aggregation of HFH-platelets by 52 and 85% respectively, while corresponding concentrations of LDL derived from HFH subjects (HFH-LDL) and CHD-LDL derived from HFH subjects (CHD-HFH-LDL) increased platelet aggregation by 165 and 65% respectively. The present results support the following conclusions: platelet activation by LDL in normal subjects is through the arginine-rich apoprotein-binding site; more than one binding site for LDL exists on platelets; under certain circumstances, LDL binding can cause a reduction in platelet activity; specificity for LDL binding to the platelets resides in different regions of the lipoprotein in HFH and in normal subjects. We have thus suggested a model for LDL-platelet interaction in normal and in HFH subjects.     

Quantifying effect of statins on low density lipoprotein cholesterol, ischaemic heart disease,and stroke: systematic review and meta-analysis

Objectives To determine by how much statins reduce serum concentrations of low density lipoprotein (LDL) cholesterol and incidence of ischaemic heart disease (IHD) events and stroke, according to drug, dose, and duration of treatment.Design Three meta-analyses: 164 short term randomised placebo controlled trials of six statins and LDL cholesterol reduction; 58 randomised trials of cholesterol lowering by any means and IHD events; and nine cohort studies and the same 58 trials on stoke.Main outcome measures Reductions in LDL cholesterol according to statin and dose; reduction in IHD events and stroke for a specified reduction in LDL cholesterol.Results Reductions in LDL cholesterol (in the 164 trials) were 2.8 mmol/l (60%) with rosuvastatin 80 mg/day, 2.6 mmol/l (55%) with atorvastatin 80 mg/day, 1.8 mmol/l (40%) with atorvastatin 10 mg/day, lovastatin 40 mg/day, simvastatin 40 mg/day, or rosuvastatin 5 mg/day, all from pretreatment concentrations of 4.8 mmol/l. Pravastatin and fluvastatin achieved smaller reductions. In the 58 trials, for an LDL cholesterol reduction of 1.0 mmol/l the risk of IHD events was reduced by 11% in the first year of treatment, 24% in the second year, 33% in years three to five, and by 36% thereafter (P < 0.001 for trend). IHD events were reduced by 20%, 31%, and 51% in trials grouped by LDL cholesterol reduction (means 0.5 mmol/l, 1.0 mmol/l, and 1.6 mmol/l) after results from first two years of treatment were excluded (P < 0.001 for trend). After several years a reduction of 1.8 mmol/l would reduce IHD events by an estimated 61%. Results from the same 58 trials, corroborated by results from the nine cohort studies, show that lowering LDL cholesterol decreases all stroke by 10% for a 1 mmol/l reduction and 17% for a 1.8 mmol/l reduction. Estimates allow for the fact that trials tended to recruit people with vascular disease, among whom the effect of LDL cholesterol reduction on stroke is greater because of their higher risk of thromboembolic stroke (rather than haemorrhagic stroke) compared with people in the general population.Conclusions Statins can lower LDL cholesterol concentration by an average of 1.8 mmol/l which reduces the risk of IHD events by about 60% and stroke by 17%.     

Molecular variation at the apolipoprotein B gene locus in relation to lipids and cardiovascular disease: a systematic meta-analysis

Apolipoprotein B (apoB) is the sole protein component of low-density lipoprotein (LDL) and is thought to play an important role in atherogenesis. We performed a meta-analysis of the associations between the three most frequently investigated polymorphisms (XbaI, signal peptide insertion/deletion, EcoRI) in the apolipoprotein B (APOB) gene, lipid parameters, and the risk of ischemic heart disease (IHD). We restricted our analysis to Caucasians. Homozygotes for the XbaI X+ allele had significantly elevated levels of LDL cholesterol (LDL-C) and apoB, but a decreased risk (OR=0.80; 95%CI: 0.66–0.96) of IHD. Homozygosity for the signal peptide deletion allele was associated with similarly increased levels of LDL-C and apoB, and with an increased risk of IHD (OR=1.30; 95%CI: 1.08–1.58). Subjects homozygous for the rare EcoRI allele had significantly decreased levels of total and LDL cholesterol, but unaltered risk of IHD. We conclude that all three polymorphic apoB sites are associated with altered lipid levels, but not necessarily with a consistently altered risk of IHD. These data suggest that the relationship between apoB levels, hypercholesterolemia and IHD risk cannot have a simple molecular basis in the apoB gene.     

Desialylated low density lipoproteins--atherogenic lipoproteins occurring in blood of patients with coronary atherosclerosis

We have recently established that LDL of most patients with coronary atherosclerosis differ from the LDL of most healthy subjects by the ability to cause primary atherosclerotic changes, i.e. the accumulation of intracellular cholesterol in the cells of smooth muscle origin cultured from unaffected intima of human aorta. We assumed that patients LDL is modified lipoprotein differing from native LDL by chemical composition. It has been established in the present study that patients LDL has a substantially lower content of sialic acid as compared with the LDL of healthy subjects. Desialylation of native LDL of healthy subjects with neuraminidase makes them atherogenic, therefore, capable of causing the accumulation of intracellular cholesterol similarly to patients LDL.     

Content of the main lipid components in blood serum lipoproteins of human and of various animal species

Using precipitation method, low-density (LDL) and high-density (HDL2 and HDL3) lipoproteins were isolated from blood serum of human (donors, patients with ischemic heart) diseases--IHD, with bronchial asthma--BA, with chronic obstructive bronchitis--COB), of mammals predisposed (pig, rabbit) and resistant (rat, mink, Arctic fox) to atherosclerosis, of birds (hen, pigeon), of bony fish (trout, white-fish, pike-perch, pike, bream, burbot), and of cartilaginous fish (sturgeon, white sturgeon). From each lipoprotein group, lipids were extracted, separated by thin-layer chromatography, and analyzed quantitatively by the spectrophotometric method. In phosphatidylcholine and HDL2 cholesterol esters, bound fatty acids (FA) were determined by the method of gas-liquid chromatography. The main amount of total cholesterol has been established to be concentrated in human LDL, especially in the cases of IHD, and in LDL in mammals predisposed to atherosclerosis. In mammals resistant to atherosclerosis and in fish the almost entire cholesterol was revealed in HDL. The phospholipid content in HDL was lower in patients with pathologies and in mammals predisposed to atherosclerosis, while the highest content--in fish and mammals resistant to atherosclerosis. In homoiothermal animals and in human the main FA amount in HDL was represented by the omega6-series. Acids of the omega3-series amounted to a negligible percentage, especially in IHD. On the contrary, the HDL FA composition of poikilothermal animals (fish) had a very high content of polyunsaturated FA of the omega3-series. A conclusion is made that composition of lipid components in animal lipoproteins by the example of several studied species and of human has a non-stable character and is submitted to changes. Their most pronounced modifications with a negative trend took place in human LDL and HDL in IHD.     

Metabolism of low-density lipoproteins by cultured hepatocytes from normal and homozygous familial hypercholesterolemic subjects

The profoundly elevated concentrations of low-density lipoproteins (LDL) present in homozygous familial hypercholesterolemia lead to symptomatic cardiovascular disease and death by early adulthood. Studies conducted in nonhepatic tissues demonstrated defective cellular recognition and metabolism of LDL in these patients. Since mammalian liver removes at least half of the LDL in the circulation, the metabolism of LDL by cultured hepatocytes isolated from familial hypercholesterolemic homozygotes was compared to hepatocytes from normal individuals. Fibroblast studies demonstrated that the familial hypercholesterolemic subjects studied were LDL receptor-negative (less than 1% normal receptor activity) and LDL receptor-defective (18% normal receptor activity). Cholesterol-depleted hepatocytes from normal subjects bound and internalized 125I-labeled LDL (Bmax = 2.2 micrograms LDL/mg cell protein). Preincubation of normal hepatocytes with 200 micrograms/ml LDL reduced binding and internalization by approx. 40%. In contrast, 125I-labeled LDL binding and internalization by receptor-negative familial hypercholesterolemic hepatocytes was unaffected by cholesterol loading and considerably lower than normal. This residual LDL uptake could not be ascribed to fluid phase endocytosis as determined by [14C]sucrose uptake. The residual LDL binding by familial hypercholesterolemia hepatocytes led to a small increase in hepatocyte cholesterol content which was relatively ineffective in reducing hepatocyte 3-hydroxy-3-methylglutaryl-CoA reductase activity. Receptor-defective familial hypercholesterolemia hepatocytes retained some degree of regulatable 125I-labeled LDL uptake, but LDL uptake did not lead to normal hepatocyte cholesterol content or 3-hydroxy-3-methylglutaryl-CoA reductase activity. These combined results indicate that the LDL receptor abnormality present in familial hypercholesterolemia fibroblasts reflects deranged hepatocyte LDL recognition and metabolism. In addition, a low-affinity, nonsaturable uptake process for LDL is present in human liver which does not efficiently modulate hepatocyte cholesterol content or synthesis.     

Protein conformation and localization in low density lipoproteins in health and in ischemic heart disease

The study has shown that the ratio of elements in the secondary structure of LDL protein from patients with the coronary heart disease from health subjects is similar. However LDL protein is displaced by 0.5 nm towards the water phase in patients with CHD comparing with healthy subjects. It is likely that such differences are a result of the lower stability of LDL protein in CHD. It is supposed that the damage of lipoprotein particles (premodification) in CHD becomes atherogenic in the vessel wall after the action of additional factors.     

Isolation of desialylated low density lipoproteins from the blood of patients with ischemic heart disease by affinity chromatography

The attempt was performed to isolate desialylated low density lipoproteins (LDL) from the blood of healthy subjects and patients with coronary heart disease by affinity chromatography with immobilized agglutinin of Ricinus communis, a lectin that interacts specifically with galactose residues. A part of LDL was bound to sorbent and could be replaced by galactose but not other saccharide constituents of the LDL molecule. Bound LDL subfraction had a 2-3-fold lower content of desialylated LDL in CAD patients was about 3-fold higher than in healthy subjects. Desialylated LDL induced a 2- to 4-fold increase of total cholesterol content in cultured human aortic intimal cells, whereas unbound LDL had no effect on intracellular cholesterol level. It is assumed that the subfraction of desialylated LDL may be responsible for the atherogenic properties of LDL in CAD patients.     

Pathophysiological significance of the global and regional left-ventricular ejection fraction (LV-EF) on ischaemic heart disease patients at rest and during ergometric exercise load (from radiocardio-cyclography (RKG-RCG) to parametric amplitude and phase scan)

As early as in the graphical RKG-RCG period a close inverse correlation could be established between the LV-EF and the serum myoglobin level during the acute course of myocardial infarction, in 10 patients in repeated follow up examinations. Corr. coeff. -0.91, p less than 0.01. In the mid seventies it could be shown by RKG-RCG, in 15 IHD patients with angina pectoris that the decrease of the basal LV-EF during ergometric load reflected the severity of IHD, compared with the increasing LV-EF tendency of 15 normal subjects. This fact could be verified on 19 middle age males (mean age, 41 years) by 99mTc RBC gamma camera ventriculography, i.e. that under modest load (100 W ergometry) a more than 10% decrease was a non-specific sign of main branch or three-vessel coronary heart disease. So in this extreme case our nuclear stethoscope-like RKG-RCG method alone may be satisfactory for staging and screening of coronary ischaemic heart disease (IHD) patients. All the 11 normal subjects belonged to the load-reaction group with more than 5% LV-EF increase, while the extensive anterior and inferior scar patients reacted without exception with more than 10% deficit (their basal LV-EF value was already under 45%). Supported by data in the literature in the comparison of load ECG and coronarography and two-step load, we could gain more refined data, but in accordance with the one-step load on the same patients. As regards the reproducibility of our global LV-EF investigations with gamma camera computer program Supersegams, it was within 5%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Abnormal low density lipoprotein metabolism in apolipoprotein E deficiency

Apolipoprotein(apo) E deficiency is an inherited disease characterized by type III hyperlipoproteinemia and less than 1% normal plasma apoE concentration. The role of apoE in LDL metabolism was investigated by quantitating the metabolism of radiolabeled normal and apoE-deficient LDL in both normal and apoE-deficient subjects. ApoE deficiency resulted in an accumulation of plasma IDL, and a decreased synthesis of LDL consistent with a block in the conversion of IDL to LDL. The LDL isolated from the apoE-deficient patient was similar to normal LDL in hydrated density, size, and composition. However, the apoE-deficient LDL was kinetically abnormal with delayed catabolism in both normal subjects and the apoE-deficient patient. In addition, the catabolism of normal LDL in the apoE-deficient subject was increased. These results were interpreted as indicating that apoE is necessary for the conversion of IDL to LDL and the formation of kinetically normal LDL. The rapid catabolism of normal LDL in the apoE-deficient patient suggests an up-regulation of the hepatic LDL receptor pathway. Based on these results, apoE is proposed to play an important role in the conversion of IDL to LDL, the formation of kinetically normal LDL, and the regulation of LDL receptor function.     

Isolation of atherogenic modified (desialylated) low density lipoprotein from blood of atherosclerotic patients: separation from native lipoprotein by affinity chromatography

A part of low density lipoproteins (LDL) isolated from the blood of healthy subjects and patients with coronary atherosclerosis bind to a Sepharose-linked Ricinus communis agglutinin, a lectin that interacts specifically with galactose residues. Bound LDL can be replaced by galactose, but not other saccharide constituents of the LDL molecule (mannose, glucose, N-acetylglucosamine, sialic acid). Bound LDL subfraction has a 2-3-fold lower content of sialic acid as compared with unbound LDL. The blood content of desialylated LDL in atherosclerotic patients was about 3-fold higher (1.5- to 6-fold) than in healthy subjects. Desialylated LDL induced a 2- to 4-fold more intensive accumulation of total cholesterol in cultured human aortic intimal cells. Unbound LDL had no effect on intracellular deposition of lipids. It is suggested that the subfraction of desialylated LDL may be responsible for the atherogenicity of LDL isolated from blood of atherosclerotic patients.     

Adaptive changes in the myocardium of patients with ischemic heart disease

Changes in the human heart muscle resulting from chronic coronary insufficiency have been analyzed using biopsies taken during surgery from nine patients with ischemic heart disease (IHD) and six patients with the WPW syndrome (without IHD). Histochemical analysis have shown that the atrial myocardium in IHD patients is characterized by an increased density of the microvascular network, increased phosphorylase activity, and decreased succinate dehydrogenase activity. Virtually the same changes have proved to occur in the myocardium of rats adapted to hypoxia by means of repeated exposure in a low-pressure chamber. According to the results of two-dimensional electrophoresis and immunoblotting, acid (but not alkaline) isoforms of inducible HSP70 proteins appear in the myocardium of IHD patients. It is concluded that the myocardium of IHD patients undergoes adaptive changes at the tissue level in response to repeated exposure to ischemia in the course of development of this disease. It is proposed that activation of the synthesis of alkaline HSP70 isoforms in the myocardium of cardiological patients may provide the possibility of improving its resistance to the impact of ischemia and reperfusion (this possibility is not realized under conditions of IHD).     

Degradation by cultured monocyte-derived macrophages from normal and familial hypercholesterolaemic subjects of modified and unmodified low-density lipoproteins.

Human blood monocyte-derived macrophages that had been cultured for 7 days in the presence of 20% whole human serum exhibited saturable degradation of low-density lipoprotein (LDL). This degradation could be abolished by pre-incubating the cells with a high concentration of LDL in the medium and increased by pre-incubating the cells in medium containing lipoprotein-deficient serum. Cells obtained from the blood of homozygous familial-hypercholesterolaemic (FH) patients only exhibited a low rate of non-saturable degradation of LDL, even when pre-incubated without lipoproteins. Thus the saturable degradation of LDL by normal cells was mediated by the LDL receptors that are defective in FH patients and little LDL was taken up and degraded through any of the other endocytotic processes present in macrophages. Degradation by normal cells pre-incubated with lipoprotein-deficient serum had a higher apparent affinity for LDL than that of cells maintained in whole serum, which suggests that incubation with lipoprotein-deficient serum may not only induce the formation of LDL receptors but may also have a direct effect on the receptors themselves. Monocyte-derived macrophages from normal and FH subjects showed similar saturable degradation of acetylated LDL and also of LDL complexed with dextran sulphate. Maximal degradation of each was in the same range as the degradation of unmodified LDL by normal cells, and was not increased if the cells were pre-incubated with lipoprotein-deficient serum.