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Biomedical subjects

J R Patsch

Publications and source records attributed to J R Patsch.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cholesteryl ester transfer protein gene expression is not specifically regulated by CCAAT/enhancer-binding protein in HepG2-cells.

Cholesteryl ester transfer protein (CETP) mediates the exchange of neutral lipids among plasma lipoproteins and is expressed predominantly in liver and intestine. In band shift assays employing nuclear extracts of HepG2 cells we identified C/EBPbeta as the predominant C/EBP isoform involved in binding to the C/EBP consensus sequence within the 5' upstream region of the CETP gene. This was demonstrated by supershift experiments using antibodies specific for C/EBPalpha, C/EBPbeta and C/EBPdelta and an oligonucleotide containing a single point mutation (CAAT-->CTAT) in this site. Expression of a CETP promoter-fragment/luciferase construct in transiently transfected HepG2 and CaCo-2 cells and enhancement of promoter activity by co-transfection with human C/EBPalpha in HepG2 cells could be influenced neither by the mutation in the consensus sequence nor by elimination of this site together with a second potential binding site for C/EBP. Furthermore, transfection of HepG2 with human C/EBPalpha did not influence the synthesis of CETP by these cells. Our results indicate that the expression of C/EBP in HepG2 cells is not able (1) to influence specifically the expression of a transfected CETP promoter dependent reporter through binding to C/EBP sites in the promoter region and (2) to significantly enhance expression of the endogenous CETP gene.

Apolipoproteins↗
PubMed1999

Leptin receptor in human term placenta: in situ hybridization and immunohistochemical localization.

In the present study, we investigated the expression and localization of leptin receptors in human term placentae. On human term placenta tissue slices, digoxigenin-UTP labelled RNA-probe detected the long form of the leptin receptor ObR(L)mRNA in syncytiotrophoblasts of the villi, whereas the haematological subtype of the leptin receptor ObR/B219.1 was detected in blood cells of the intervillous space and fetal vessels. Immunohistochemistry, with two polyclonal antibodies to the N-terminus recognizing ObR(L)and ObR(S)of the leptin receptors and one to the C-terminus recognizing the long form of the leptin receptor ObR(L), localized leptin receptor protein at the apical membrane of the syncytiotrophoblasts. Our results show that the long form of the leptin receptor ObR(L)is expressed in human term placentae. We localized the long form of leptin receptor mRNA to the cytoplasm of syncytiotrophoblasts and leptin receptor proteins in human term placentae to the apical membrane of syncytiotrophoblasts. We conclude that in term placentae, leptin could mediate a growth promoting effect in the fetoplacental unit through the long form of the leptin receptor localized in the syncytiotrophoblasts. In contrast, the haematological subtype of the leptin receptor is not expressed in placental cells, but solely by blood cells in the intervillous space and fetal vessels.

Carrier Proteins↗
PubMed1999

[Prevention of coronary heart diseases in clinical practice. Comment on the recommendations of the Second Joint Task Force of European Societies for Prevention of Coronary Disease].

The Second Joint Task Force of European Societies on Coronary Prevention (EAS-European Atherosclerosis Society, ESC-European Society of Cardiology, ESH-European Society of Hypertension) have established recommendations for the prevention of coronary heart disease in cooperation with the representatives of the International Society of Behavioral Medicine, the European Society of General Medicine/Family Medicine, and the European Heart-Network. These recommendations of the year 1998 are commented by Austrian cardiologists and lipidologists and supplemented with recent clinical findings.

Anticholesteremic Agents↗
PubMed1999

[Statins in diabetic hyperlipidemia].

Several placebo-controlled prospective multicenter trials showed convincing evidence that cholesterol lowering with statins reduced mortality due to coronary heart disease. Subgroup analyses of diabetic patients demonstrated significant reduction of coronary death rates in diabetics even more pronounced than that observed with the nondiabetic population. In some studies significant reduction of strokes was also achieved by lipid lowering. In one diabetic subgroup stroke reduction nearly reached significance despite low number of patients. New studies are currently in progress investigating the effect of lipid lowering specifically for diabetic patients. Some of these studies are designed to evaluate the effects of drugs acting primarily on triglycerides, such as the fibrates, or showing both, triglyceride and cholesterol reduction, like some newer statins, especially atorvastatin. The dyslipidemia encountered most frequently with diabetics is an increase of triglycerides and low HDL-cholesterol. Because of the high cardiovascular risk of diabetics the target levels of LDL-cholesterol in secondary and primary prevention should not exceed 100 mg/dl as in secondary prophylaxis in patients without diabetes.

Anticholesteremic Agents↗
PubMed1998

[Leptin--an interim evaluation].

The discovery of leptin, the product of the obese (ob)-gene, has broadened the horizons of research on energy balance. This hormone, produced and secreted by adipose tissue and some placental cells, finds its way to the hypothalamus, where it binds to the leptin receptors and signals satiety through the neuroendocrine axis. The fact that adipose tissue is not merely a storage depot, but also an important endocrine tissue, has revived the interest in the "lipostatic" theory of body fat regulation and has initiated many research efforts in the field of obesity, anorexia nervosa, bulimia, reproduction and haematology.

Adipose Tissue↗
PubMed1998

Influence of hyperinsulinemia on lipoproteins after pancreas transplantation with systemic insulin drainage.

Successful pancreas transplantation with systemic drainage is followed by a normalization of carbohydrate and lipid metabolism with low levels of plasma cholesterol and triglycerides. HDL cholesterol concentration and CETP plasma levels were found to be increased and the composition of lipoproteins altered in that LDL and HDL2/HDL3 were enriched in UC, HDL2 enriched in PL, and LDL depleted in PL. The mechanisms by which hyperinsulinemia may cause the observed changes in surface composition of plasma lipoproteins are unknown, as is their clinical relevance. It remains to be seen whether these changes counterbalance the favorable effects of an increased triglyceride clearance capacity on the cardiovascular risk of diabetic patients.

Adult↗
PubMed1998

Hypertriglyceridemia and insulin resistance.

Although the association between insulin resistance and hypertriglyceridemia has long been recognized, the question of the causal relationship of these two entities is still a matter of debate. To gain more insight into the relationship between hypertriglyceridemia and insulin resistance, we studied insulin sensitivity in two severely hypertriglyceridemic subjects in whom insulin resistance as a cause for hypertriglyceridemia could be positively ruled out. Rather, lipoprotein lipase deficiency due to a mutation in the lipoprotein lipase gene was identified as the cause. In the two study subjects, whole body glucose utilization was measured during a continuous infusion of somatostatin, glucose and insulin. Mean values of plasma glucose and insulin concentrations at 150, 160, 170 and 180 minutes were used to calculate steady state plasma glucose (SSPG) and steady state plasma insulin (SSPI) concentrations. SSPG of the two hypertriglyceridemic patients was in the range of those reported in the literature for healthy subjects without insulin resistance did not differ from those of two control subjects with normal plasma lipid levels. Therefore, the dyslipidemic state of the two patients, characterized by extreme elevation of triglyceride rich plasma lipoproteins and a severe reduction of HDL cholesterol, was clearly not associated with insulin resistance. From these findings we conclude that hypertriglyceridemia per se is not an obligatory cause for insulin resistance.

Adult↗
PubMed1998

Modulation of iron metabolism in monocytic THP-1 cells and cultured human monocytes by the acute-phase protein alpha1-antitrypsin.

The reticuloendothelial (RE) system plays an important role in the changes in iron metabolism associated with the anemia of chronic disease (ACD). We previously reported that the acute-phase protein alpha1-antitrypsin (alpha1-AT) reduced growth and proliferation in cells of the erythroid cell system by interfering with transferrin (Tf)-mediated iron uptake. The regulation of iron metabolism in cells of the RE system is distinctly different from that in other cell systems; moreover, monocytes and macrophages play an essential part in the regulation of the production and clearance of alpha1-AT. In the present study we examined the effect of alpha1-AT on cells of the monocyte-macrophage lineage. Alpha1-AT completely inhibited the binding of Tf to its receptor (TfR) on THP-1 human myelomonocytic cells and cultured human monocytes. Results of equilibrium saturation and kinetic studies indicated that this inhibition was competitive. No other acute-phase protein demonstrated the same inhibitory potency. Furthermore, alpha1-AT almost completely prevented internalization of the Tf-TfR complex in a dose-dependent manner. Interestingly, and in sharp contrast to the results of our studies with erythroid cells, this inhibition did not reduce the growth and proliferation of THP-1 cells. Furthermore, alpha1-AT significantly increased the concentration of intracellular ferritin in THP-1 cells and monocytes, whereas the number of TfR remained unchanged. Because alpha1-AT showed no enhancing effect on ferritin transcription and translation, we believe that an as-yet unidentified posttranslational mechanism may be responsible for this phenomenon. In addition, our results indicate that the increase in ferritin concentration caused by alpha1-AT is mediated independently of iron supply, as has previously been shown for several proinflammatory cytokines. These data provide further evidence that alpha1-AT is a mediator of the alterations in iron metabolism characteristic of ACD.

Cell Division↗
PubMed1997

Complement activation by HIV-1-infected cells: the role of transmembrane glycoprotein gp41.

To characterize the mechanisms of complement activation by human immunodeficiency virus type 1 (HIV-1)-infected cells, Cl-4 cells stably expressing the envelope glycoproteins of HIV-1 and the parent African green monkey cell line CV-1 were tested for C1q binding and complement activation. While the parent cell line CV-1 only showed a weak spontaneous activation of the alternative pathway, Cl-4 cells additionally triggered the classical pathway of complement activation independent of anti-HIV antibodies by direct C1q binding. Earlier studies had shown different complement activating potential of cells infected with various HIV isolates. Recombinant soluble CD4-induced shedding of gp120 from the surface of HIV-1-infected cells converted a weak activator isolate (MVP-899) into a strong complement activator. The increase in complement activation was paralleled by the concomitant unmasking of a previously hidden gp41 epitope comprising the major complement-activating domain of gp41 (aa. 601-613). Our results strongly suggest that the transmembrane protein gp41 induces the activation of complement on the surface of infected cells as has been described previously for purified HIV-1 virions. Furthermore, we present evidence that the different potential of HIV isolates to activate the complement system on the cell surface is caused by different degrees of spontaneous gp120 shedding by various HIV isolates.

Animals↗
PubMed1997

Deficiency of cholesteryl ester transfer protein. Description of the molecular defect and the dissociation of cholesteryl ester and triglyceride transport in plasma.

A patient is described who exhibited, despite excessively high postprandial triglyceride levels, high levels of HDL cholesterol. Measurement of CETP activity and mass in the patient's plasma showed values of less than 5% and 2%, respectively, of a normolipidemic plasma pool. The CETP cDNA of the patient exhibited a mutation (T-->G), turning codon 57 (TAT) of exon 2 into a stop codon (TAG) and abolishing a, XcmI restriction site. Digestion of directly amplified CETP cDNA from the patient with XcmI indicated the exclusive presence of CETP cDNA containing the mutation. Analysis of the corresponding region of the CETP gene indicated the patient to be heterozygous for the nonsense mutation at codon 57, a finding that can only be explained by the presence of a null allele in addition to the allele with the nonsense mutation. The combination of TG intolerance of uncertain cause, together with CETP deficiency due to a novel mutation, produced the paradoxical constellation--high levels of HDL cholesterol (172 mg/dL) associated with a high post-prandial lipemia of 1460 mg triglycerides/dL.8 hours--and provided further insight into the role of CETP as mediator between pools of triglycerides and cholesteryl esters in plasma.

Aged↗
PubMed1996

Lipoprotein(a) is increased in triglyceride-rich lipoproteins in men with coronary heart disease, but does not change acutely following oral fat ingestion.

Association of apo(a)/Lp(a) with triglyceride-rich lipoproteins (TGR-Lps) is determined by different factors that are poorly understood. Some previous studies suggested that apo(a) in TGR-Lps may affect the atherogenicity of the TGR particles. To study whether there are any peculiarities in postprandial (pp) Lp(a) metabolism, we have determined apo(a) phenotypes and Lp(a) concentrations in 46 subjects with coronary heart disease (CHD) and in six normolipidemic individuals at different time points (4, 6 and 8 h) following an oral fat tolerance test. While mean triglyceride concentration reached its maximum 6 h after a standardized fat meal, no change in total cholesterol and in mean Lp(a) plasma concentration was detected at any time point after the fat load. In 6 normolipidemic probands and in 8 patients with CHD, who were matched for apo(a) phenotype, lipoprotein levels, age and body weight, we followed the distribution of apo(a) in plasma density gradient fractions in the fasting and pp state. In the CHD patients a significant larger percentage of apo(a) reactivity was detected in TGR-Lps in the pre- as well as in the postprandial state, compared to control subjects. The fat intake did not induce a significant change of apo(a) reactivity in the TGR-Lp fractions in both groups. The apo(a) isoform-size and the Lp(a) plasma concentration in the fasting state had no influence on the individual variation of the Lp(a) concentration in pp TGR-Lp fractions. Our results provide evidence that TGR-Lp fractions of CHD patients are enriched in apo(a) reactivity compared to healthy controls, but do not support the hypothesis that Lp(a) acts atherogenically through a pp increase of its plasma concentration.

Adult↗
PubMed1996

Effects of pancreas transplantation on distribution and composition of plasma lipoproteins.

In type I (insulin-dependent) diabetic patients, peripheral hyperinsulinemia due to subcutaneous insulin treatment is associated with increased high-density lipoprotein (HDL) cholesterol, and also with an altered surface composition of HDL. Pancreas grafts also release insulin into the systemic rather than into the portal venous system, giving rise to pronounced peripheral hyperinsulinemia. We hypothesized that if peripheral hyperinsulinemia is responsible for high HDL cholesterol and/or altered surface composition of HDL in diabetic subjects, similar changes in the lipid profile should be present in pancreas-kidney transplant recipients (PKT-R). Using zonal ultracentrifugation, we isolated HDL2, HDL3, very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) from fasting plasma of 14 type I diabetic PKT-R, eight nondiabetic kidney transplant recipients (KT-R), and 14 healthy control subjects and determined the level and composition of the above lipoproteins. HDL2 cholesterol was increased in PKT-R as compared with KT-R and healthy controls (both P < .05), whereas HDL3 cholesterol was unchanged. However, an altered lipoprotein surface composition was evident in PKT-R: HDL2, HDL3, and LDL were enriched in unesterified cholesterol ([UC] PKT-R v KT-R, P=.13, P < .005, and P < .05, respectively; PKT-R v controls, all P < .005); HDL2 was enriched in phospholipids; and LDL was depleted of phospholipid. KT-R, in contrast, showed no changes in lipoprotein surface composition but a substantial triglyceride enrichment of HDL2 as compared with PKT-R and healthy controls (both P < .05). LDL size as determined by gradient gel electrophoresis was increased in PKT-R compared with controls (P < .005). The plasma concentration of cholesteryl ester (CE) transfer protein (CETP), involved also in phospholipid transfer, was increased in both transplant groups compared with healthy controls (both P < .05). Insulin concentrations in fasting plasma were directly related to CETP levels and to the weight-percentage of UC in HDL3, and inversely to the weight-percentage of phospholipids in LDL (all P < .05). We explain the increase in HDL2 cholesterol and LDL size in PKT-R by their high lipoprotein lipase (LPL) activity conferring an excellent capacity to clear chylomicron triglycerides. Effective handling of postprandial triglycerides, high HDL2 cholesterol, and predominance of LDL pattern A, respectively, are established indicators of a low risk of atherosclerosis. However, it is presently unclear what effects the compositional changes on the surface of HDL and LDL may have on cardiovascular risk in clinically stable PKT-R.

Adult↗
PubMed1996

The human immunodeficiency virus type 1 transmembrane gp41 protein is a calcium-binding protein and interacts with the putative second-receptor molecules in a calcium-dependent manner.

Fusion is a crucial event in the life cycle of the human immunodeficiency virus (HIV); is is initiated by the high-affinity binding between gp120, the external surface glycoprotein of HIV-1, and the differentiation antigen CD4 and finally results in the insertion of the hydrophobic amino terminus of the gp41 envelope glycoprotein into the plasma membrane of the target cell. Recent results suggest that this process is dependent upon calcium ions, but the mechanism or the proteins involved are not understood. Computer-assisted sequence analysis revealed a putative calcium-binding site within the extracellular part of gp41 that was highly reminiscent of the calcium-binding EF-hand structure. To test this hypothesis, calcium-binding experiments were performed. Binding of a recombinant soluble form of the transmembrane protein (rsgp41) to its putative second-receptor molecules in equilibrium was dependent upon calcium. The affinity was not influenced by calcium, but the maximum binding was increased in a dose-dependent manner. Radioactive calcium bound to rsgp41 covalently attached to Sepharose but not to bovine serum albumin. Binding was inhibited by the addition of nonradioactive calcium, indicating that binding was specific. Neither magnesium nor manganese inhibited the binding of labeled calcium to rsgp41. Binding was dependent on the oxidative state of the rsgp41 molecule, suggesting the functional importance of the correctly folded structure of the rsgp41 protein. In this report, we demonstrate that the HIV-1 transmembrane protein gp41 is a calcium-binding protein and interacts with the putative second-receptor molecules in a calcium-dependent manner.

Amino Acid Sequence↗
PubMed1996

Relationship of plasma cholesteryl ester transfer protein to HDL cholesterol. Studies in normotriglyceridemia and moderate hypertriglyceridemia.

To evaluate the independent effect of cholesteryl ester transfer protein (CETP) on HDL concentrations in humans, we measured lipids, lipoproteins, postprandial lipemia after an oral fat load, CETP mass, and the activities of CETP, lipoprotein lipase (LPL), and hepatic lipase in 16 healthy, normotriglyceridemic men and in 23 men with moderate, primary hypertriglyceridemia on an American Heart Association Step I diet. Fasting triglycerides and postprandial lipemia were increased and HDL cholesterol (HDL-C) was decreased in hypertriglyceridemic men compared with control subjects (P < .001). In the normotriglyceridemic group, CETP mass (P < .001) and activity (P < .005) were directly related to LPL activity After statistical adjustment for this close association, no significant relationship of CETP to HDL-C independent of LPL activity could be demonstrated in the normotriglyceridemic subjects. In contrast, CETP was unrelated to LPL activity in the hypertriglyceridemic subjects, but CETP concentrations showed a close inverse relationship to HDL-C (r = -.504, P = .014). Structural equation modeling of the association structures between HDL and fasting and postprandial triglycerides, endothelial lipases, and CETP in both groups indicated that the overall regression models for the two groups differed (P < .05). Specifically, the associations between CETP mass and activity and HDL-C differed between both groups (both P < .01). We conclude that high-normal CETP levels lower HDL-C in nonsmoking, nonobese men with moderate, primary hypertriglyceridemia on a hypolipidemic diet, but not in healthy, normotriglyceridemic men on an unrestricted diet. Thus, variation in CETP plasma concentrations may contribute to the high-triglyceride, low-HDL phenotype.

Adult↗
PubMed1996

Apolipoprotein A-II influences the substrate properties of human HDL2 and HDL3 for hepatic lipase.

Hepatic lipase has a demonstrated dual role in plasma lipid transport in that it participates in the removal of remnants of triglyceride-rich lipoproteins from the circulation and in the metabolism of plasma HDL. The study presented here investigated the substrate properties for hepatic lipase of HDL differing in density and apolipoprotein (apo) composition. Rates of fatty acid liberation were twofold higher in HDL2 compared with the respective HDL3 subspecies. Within each density class, enzyme-catalyzed fatty acid release was nearly twofold higher from HDL containing apoA-II compared with HDL devoid of apoA-II. When native HDL3 devoid of apoA-II was reconstituted with dimeric apoA-II in vitro, rates of fatty acid liberation in reconstituted particles were similar to those in native HDL3 containing apoA-II. HDL containing apoA-II competed more effectively with small VLDL for binding of hepatic lipase than HDL devoid of apoA-II. HDL3, particularly apoA-II-containing HDL3, reduced lipolysis of triglyceride and total fatty acid liberation in small VLDL. We conclude that the substrate properties of HDLs for hepatic lipase are influenced by both their size and apoA-II content. Moreover, size as well as apoA-II content may indirectly affect remnant clearance.

Apolipoprotein A-II↗
PubMed1995

Relationship of high-density lipoprotein subfractions and cholesteryl ester transfer protein in plasma to carotid artery wall thickness.

High plasma concentrations of high-density lipoprotein (HDL) cholesterol are a powerful indicator of low vascular risk. By decreasing HDL cholesterol, cholesteryl ester transfer protein (CETP) could perhaps constitute an atherogenic protein. We measured HDL cholesterol and HDL subfractions and quantified CETP mass in fasting plasma in 21 asymptomatic probands, and related these variables to the mean intima media thickness of the extracranial carotid arteries. HDL2 cholesterol, the less dense HDL subfraction, was inversely related to carotid wall thickness (r = -0.378; P < 0.05), and CETP was directly related to carotid wall thickness (r = 0.436; P < 0.05). In plasma CETP is associated mostly with the HDL3 subfraction. We therefore calculated from our measurements the relative CETP content of HDL3, i.e., CETP/HDL3 cholesterol. This ratio was correlated with carotid wall thickness stronger than any other variable measured (r = 0.718, P < 0.001). We conclude that variation in HDL subfractions and CETP may be more closely associated with carotid intima media thickness than the accepted strong risk factor of HDL cholesterol.

Adult↗
PubMed1995

Treatment of primary mixed hyperlipidemia with etophylline clofibrate: effects on lipoprotein-modifying enzymes, postprandial lipoprotein metabolism, and lipoprotein distribution and composition.

In 17 patients with primary mixed hyperlipidemia we studied levels and composition of lipoproteins in fasting plasma, lipoprotein-modifying enzymes, and postprandial lipoprotein metabolism after an oral fat-tolerance test supplemented with vitamin A before, and 12 weeks after treatment with etophylline clofibrate. With treatment, fasting plasma cholesterol, triglycerides, and the levels of very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), and low density lipoproteins (LDL) decreased significantly; high density lipoprotein (HDL) cholesterol increased significantly. Treatment caused also an increase in the protein content of IDL, a decrease in the triglyceride content of LDL, and an increase in the size of LDL as assessed by gradient gel electrophoresis. Concentrations of triglycerides, chylomicrons, and chylomicron remnants after an oral fat load supplemented with vitamin A decreased by 33%, 30% and 6%, respectively (P < 0.005; P < 0.01; and P < 0.05). The activity of lipoprotein lipase and hepatic lipase in postheparin plasma increased by 51% and 45%, respectively (P < 0.01; P < 0.05). We found a decrease in the mass concentration of cholesteryl ester transfer protein (P < 0.05). Stepwise multiple regression analysis showed that the triglyceride content of LDL is determined primarily by fasting triglycerides (r = + 0.53, P < 0.05;baseline) and cholesteryl ester transfer protein (r = + 0.49, P < 0.05; 12 weeks); in contrast, the triglyceride content of HDL3 is determined exclusively by accumulation of postprandial triglycerides (r = + 0.67; P < 0.05; baseline) and postprandial chylomicrons (r = +0.87; P < 0.005; 12 weeks). We conclude that hypolipidemic treatment with etophylline clofibrate favorably affects the cardiovascular risk factor profile in primary mixed hyperlipidemia.

Carrier Proteins↗