PubMed Health⌕ Search

Biomedical subjects

W Jaross

Publications and source records attributed to W Jaross.

At least 37 records · Page 2Linked to original sources
PubMed1999

Mutations of the human hepatic lipase gene in patients with combined hypertriglyceridemia/hyperalphalipoproteinemia and in patients with familial combined hyperlipidemia.

Hepatic lipase is an enzyme which hydrolyzes triglycerides from plasma lipoproteins and thus takes part in the metabolism of intermediate density lipoproteins and high-density lipoproteins. The search described here concentrated on mutations of the HL gene in 129 patients with combined hypertriglyceridemia/hyperalphalipoproteinemia and in 184 members of 19 families with familial combined hyperlipidemia. Controls were 100 subjects with favorable lipid values (age 46-51 years). Mutation screening and analysis were performed by temperature-gradient gel electrophoresis, allele-specific restriction genotyping, and sequencing. Six different missense mutations and four different silent mutations were found in the HL gene. The alleles Phe-267 and Gln-343 were detected only once in the patient group with hypertriglyceridemia and hyperalphalipoproteinemia and were not detected in the control group. The allele Met-383 was rare in both patients and controls. We found 9.3% of the patients and only 3.0% of controls to be carrying the Val-73-Met missense mutation. The allele Phe-334 was found in 5.43% of patients and in 2.0% of controls. The difference between the frequencies of these alleles was significant between male patients and male controls (Met-73 P=0.044; Phe-334 P=0.047). Also, the summarized odds ratio of 3.28 (95% confidence interval 1.23-8.73) demonstrates that mutation carriers are significantly more prevalent in the patients. Fifteen carriers of the Met-73 allele were found in six families of the familial combined hyperlipidemia group. Furthermore, six carriers of the Phe-334 allele were found in three families of the same group. In comparison to the controls the summarized odds ratio of 2.45 (95% confidence interval 0.89-6.71) barely missed the level of significance. The linkage between genotype and phenotype was incomplete. These results show an association of the missense mutations Val-73-Met and Leu-334-Phe as susceptibility alleles for combined forms of hyperlipidemia.

Adolescent↗
PubMed1999

Analysis of secretory group II phospholipase A2 expression in human aortic tissue in dependence on the degree of atherosclerosis.

Secretory non-pancreatic (group II) phospholipase A2 (sPLA2) releases precursors of important mediators of inflammation from phospholipids. Based on the inflammatory character of atherosclerosis we previously described the identification of sPLA2 in human atherosclerotic plaques. In vitro studies on lipoproteins have shown that sPLA2 is able to favour the formation of foam-like cells representing a typical feature of early atherosclerotic lesions. In the present study the expression of sPLA2 in relation to the degree of atherosclerosis was investigated. Aortic tissue samples of 25 autopsy cases ranging in age from 1 to 77 years were taken from 2 cm above the heart and 3 cm below the renal arteries. The material was classified regarding the degree of atherosclerotic changes based on staining with haemalaun and eosine as well as on staining according to Goldner. Furthermore, immunohistochemical procedures detecting sPLA2, macrophages and smooth muscle cells were performed. The study has shown that in the abdominal aorta the enzyme was present in all advanced atherosclerotic lesions, but only in some preatheromas and precursors of atherosclerosis. However, this correlation did not occur in the thoracic aorta, where sPLA2-positive results showed a similar frequency in all degrees of atherosclerotic lesion. The enzyme was found in all three layers of the vessel wall without significant differences. Round cells, scarcely smooth muscle cells and endothelial cells were identified as sPLA2-positive. However, these data do not allow a conclusion as to which type of cell is responsible for the secretion of sPLA2. In summary, the correlation between the expression of this enzyme and the degree of atherosclerosis underlines the possible importance of sPLA2 in atherogenesis.

Adolescent↗
PubMed1999

Determination of cholesterol in atherosclerotic plaques using near infrared diffuse reflection spectroscopy.

The aim of this investigation was to examine whether near infrared diffuse reflection spectroscopy is an acceptable tool for the determination of cholesterol content in atherosclerotic plaques. Using an FT-spectrophotometer (lambda=1000-2500 nm) and fiberoptic systems (d=4 mm), the cholesterol content could be determined in mixtures of the primary compounds of the aortic wall with acceptable precision. Considering the inhomogeneous distribution of cholesterol and cholesterol esters in atherosclerotic plaques the determination of total cholesterol using this method is of acceptable efficacy, even though the calibration procedure did not reflect the composition correctly. Using an energy dose of less than 100 mW/cm(2) to avoid damage to endothelial cells, arterial tissue of about 170-200 microm thickness attenuates the reflected NIRS signal by up to 50%. Cholesterol levels could be determined accurately in atherosclerotic lesions in human aortic specimens obtained by autopsy. The correlation coefficient between the NIRS results and those of HPLC analysis calculated in the investigation of 82 different areas of 18 human aortic specimens was 0.926 (y=0.869x+0. 771, external validation). Acceptable results were also achieved by means of a coronary-catheterlike fiberoptic strand (d=l mm), despite the worsened signal/noise ratio. The results show that the development of a coronary catheter using NIRS appears to be possible in principle.

Arteriosclerosis↗
PubMed1998

Even moderate cigarette smoking influences the pattern of circulating monocytes and the concentration of sICAM-1.

The pattern of circulating monocyte subtypes and the concentration of the soluble intercellular adhesion molecule-1 (ICAM-1) were compared in middle-aged female moderate smokers and lifetime non-smokers. Total leukocyte and monocyte counts were higher in smokers. The pattern of circulating monocytes of smokers was changed toward lower absolute counts of activated (CD16+/CD64+) monocytes and (CD16+/CD14+) monocyte-macrophages and higher counts of nonactivated monocytes. The serum concentration of soluble ICAM-1 was significantly higher in smokers than in non-smokers. It is supposed that even moderate cigarette smoking leads to an activation of the circulating monocytes and their increased adhesion to the endothelium.

Antigens, CD↗
PubMed1998

Food supply abundant increase of serum selenium concentrations in middle-aged Dresden women between 1990 and 1996. DRECAN-Team. Dresden Cardiovascular Risk and Nutrition.

Serum selenium concentration was measured in middle-aged Dresden (East Germany) women in 1990 and 1996. In 1990, the serum concentration of selenium in middle-aged women was higher than in men living under the same environmental conditions (0.98 +/- 0.32 vs 0.82 +/- 0.19 micromol/l). In 1996, the serum concentration of selenium in middle-aged women was significantly higher than in 1990 (1.19 +/- 0.34 micromol/l). This increase seems to be caused by the changed foodstuff supply after the reunification of Germany. Selenium values did not correlate with age, blood pressure or daily energy intake. Moderate smoking and menopausal status did not influence the selenium levels. In 1990, the serum concentration of selenium was the highest in those women who consumed the lowest amounts of carbohydrates or fibers, or who had the highest consumption of meat, fresh fish or potatoes.

Adult↗
PubMed1998

18 bp insertion/duplication with internal missense mutation in human hepatic lipase gene exon 3. Mutations in brief no. 181. Online.

Human hepatic lipase (hHL) plays an important role in hydrolysis of triglycerides from plasma lipoproteins. The enzyme also hydrolyzes HDL2 lipids resulting in smaller HDL particles with a lower cholesterol content and properties similar to HDL3. hHL is localized in liver sinusoids, ovary and adrenal gland. These findings propose an influence on processing of cholesterol. Here we report an insertion mutation in exon 3 of hHL. The 18 bp duplication contains an additional internal point mutation (GenBank-Accession #AF037404). The female mutation carrier suffered from severe adiposity with total cholesterol of 291,6mg/dl, HDL-cholesterol of 55,3mg/dl, LDL-cholesterol of 206,8mg/dl and triglycerides of 80,8mg/dl. Following cloning of a PCR-amplified fragment the mutation was confirmed by cycle sequencing. Sequence analysis revealed an inserted repeat of 18 nucleotides. Furthermore the patient carries an additional missense mutation A-->G at nucleotide 9 of the repeat which results in an amino acid exchange from Ile-->Val at codon 4 of the repeat. These data enable us to report the insertion of HisTyrThrValArgVal which might be responsible for the moderate shift in lipid metabolism of the heterozygous patient.

DNA Transposable Elements↗
PubMed1997

Minimal oxidation and storage of low density lipoproteins result in an increased susceptibility to phospholipid hydrolysis by phospholipase A2.

In vitro-studies have shown that phospholipid hydrolysis of low density lipoproteins (LDL) by bee venom or porcine pancreatic phospholipase A2 (PLA2) leads to an increased uptake of these lipoproteins by macrophages transforming them into foam cells. Recently, a secretory phospholipase A2, group II, was detected in human atherosclerotic plaques. In order to investigate the role of this enzyme in the pathogenesis of atherosclerosis, a structurally identical human secretory PLA2 was purified from the medium of HepG2 cells stimulated with interleukin-6 and tumor necrosis factor-alpha. The activity of the purified enzyme towards the phospholipids of native and modified low density lipoproteins was compared with the activity towards Escherichia coli-membranes and other phospholipid substrates. Compared to E. coli-membranes, native LDL proved to be a poor substrate for group II PLA2. After mild oxidation induced by copper ions or by 2,2-azobis(2-amidinopropane) (AAPH), the susceptibility of LDL to phospholipid hydrolysis was found to be increased by 25 and 23%, respectively, whereas extensive copper-mediated oxidation caused a decreased hydrolysis. Aging of LDL at 6 degrees C for weeks or at 37 degrees C for hours resulted in an increase in PLA2-catalyzed phospholipid hydrolysis of up to 26-fold. LDL protected from oxidation by probucol during aging showed a lesser increase in susceptibility to phospholipid hydrolysis. Our results suggest that PLA2, group II, can increase the atherogenicity of LDL by its ability to hydrolyze the phospholipids of these lipoproteins, especially after modifications that are likely to occur in vivo.

Cell Line↗
PubMed1997

Effects of fluvastatin therapy on lipids, antioxidants, oxidation of low density lipoproteins and trace metals.

OBJECTIVE: Oxidation of low density lipoproteins (LDL) is thought to be an important step in the development of atherosclerosis. Trace metals are involved in oxidative processes. It was of interest to determine whether lipid-lowering therapy with fluvastatin, a potent HMGCoA reductase inhibitor, affected LDL oxidation and trace metal levels. METHODS: Twenty hypercholesterolemic patients were treated with fluvastatin (40 mg twice daily) or placebo for 8 weeks in a double-blind, randomized study. LDL composition, antioxidants and oxidizability as well as plasma zinc, copper, selenium and manganese concentrations were investigated. RESULTS: After fluvastatin treatment, total cholesterol was reduced by 24%, triglycerides fell by 26% and plasma Zn fell by 8%. Cu, Se and Mn changed insignificantly. LDL were separated by ultracentrifugation. LDL were reduced by 18%, LDL-C by 29% and LDL-TG by 19%. The concentrations of alpha-tocopherol and retinol in LDL changed insignificantly. LDL preparations were incubated with copper ions (204 mumol.1(-1) LDL-C/3.2 mumol.1(-1) Cu) and formation of conjugated dienes was monitored at 234 nm for 5 h. Treatment with fluvastatin caused a reduction of diene production by 16% and of diene production rate by 14%, effects being significantly different from placebo (P = 0.02). The change of the lagtime did not reach significance; however, it was positively correlated with the change in LDL alpha-tocopherol. In the placebo group, no significant effects were observed. CONCLUSION: Fluvastatin therapy had lipid-lowering and antioxidative effects.

Anticholesteremic Agents↗
PubMed1997

Simultaneous determination of fecal fat, nitrogen, and water by near-infrared reflectance spectroscopy.

BACKGROUND: Determinations of fecal fat and nitrogen reveal evidence of malabsorption and assist in estimating the efficacy of pancreatic enzyme treatment. Seventy-two-hour stool collection, with chemical analysis of fecal fat, and Kjeldahl's method for measurement of fecal nitrogen are generally accepted as standard methods for making these determinations. However, these traditional methods are expensive, time-consuming, and cumbersome. This study evaluated the efficiency and validity of an alternative method, using near-infrared reflectance spectroscopy (NIRS) and compared results with those of the standard methods. METHODS: Near-infrared reflectance spectroscopy is a secondary method: The instrument first has to be calibrated with samples analyzed by the standard method. Sixty-three stool samples with known fat content (range 4.79-292.5 mg/g), 24 samples with known nitrogen content (range 5.36-19.38 mg/g), and 24 samples with known water concentration (range 60.1-82.22%) served for calibration. A further 69 samples were analyzed to validate the procedure. RESULTS: There was a satisfactory correlation between the measurements produced by near-infrared reflectance spectroscopy and those produced by standard methods: fat r = 0.97; nitrogen r = 0.94; water r = 0.96. CONCLUSIONS: Near-infrared reflectance spectroscopy appears to be a reliable, simple, and rapid method of measuring different fecal components-as precise and accurate as the standard methods. Stool samples should be analyzed immediately after collecting or stored only a few days before analyzing.

Adolescent↗
PubMed1996

Impact of concentrations of glycated hemoglobin, alpha-tocopherol, copper, and manganese on oxidation of low-density lipoproteins in patients with type I diabetes, type II diabetes and control subjects.

The late organ complications in diabetic patients are associated with enhanced oxidation of low-density lipoproteins (LDL). The role of vitamin and trace metal concentrations in this process is not clear. Therefore, we compared the oxidative susceptibility and alpha-tocopherol concentration of LDL with the levels of glycated hemoglobin (HbA1c), copper and manganese. Sixty-three diabetic patients (23 female and 40 male; 53 of type II, 10 of type I) and 35 control subjects (17 female and 18 male) were investigated. The in vitro-formation of conjugated dienes in purified LDL preparations in the presence of copper was followed as absorbance at 234 nm. LDL exhibited a shorter lagtime (44.5 +/- 10.1 vs. 67.8 +/- 16.0 and 50.1 +/- 14.3 vs. 68.8 +/- 14.6 min) for type I and type II diabetic patients vs. sex and age-matched controls, P < 0.001. For all subjects together the lagtime was inversely correlated to HbA1c (r = -0.230, P = 0.023) and positively correlated to LDL alpha-tocopherol/LDL (mol/mol). This ratio was lower in diabetic patients (P < 0.01 for type II) than in control subjects. The copper and manganese plasma levels were not different between diabetic and nondiabetic groups. However, parameters of LDL oxidizability (amount and rate of oxidation) were positively correlated with both copper and manganese concentrations. We conclude that in diabetes the resistance of LDL against oxidation is diminished in relation to the quality of glucose control.

Adult↗
PubMed1996

Alterations in the physiochemical characteristics of low and high density lipoproteins after lipolysis with phospholipase A2. A spin-label study.

Human low and high density lipoproteins (LDL and HDL, respectively) were treated with porcine pancreatic phospholipase A2 (PLA2) in the presence of albumin resulting in hydrolysis of 40-84% of the lipoproteins phospholipids. The resulting PLA2-treated LDL and HDL and concurrent control lipoproteins incubated without PLA2 were reisolated by ultracentrifugation and labelled with 5-doxyl- and 16-doxyl-stearic acid, and with a spin-labelled analogue of maleimide. Analysis of ESR spectra showed that phospholipid hydrolysis both of LDL and HDL resulted in an increase in order, micro-viscosity and polarity of lipid regions in the surface monolayer of the particles. In the temperature range from 3 degrees C to 50-60 degrees C, Arrhenius plots of a spectral parameter of LDL and HDL labelled with 5-doxyl-stearate exhibited alterations which suggest an increase in free cholesterol content near the surface of the lipoproteins after PLA2-treatment. ESR spectra of the maleimide analogue bound covalently to the protein moiety of the lipoproteins have demonstrated that, following phospholipid hydrolysis, the conformation of the apoproteins became more condensed, with more masked domains. The possible implications of the revealed alterations for enhanced delivery of LDL and HDL cholesterol to cells after phospholipolysis of the lipoproteins are discussed.

Ascorbic Acid↗
PubMed1996

Fast amplification of the low density lipoprotein receptor gene and detection of a large deletion by means of long polymerase chain reaction.

To demonstrate the usefulness of Long PCR in analyzing gene structures and large deletions we have developed a method to amplify the entire LDL receptor gene, including the promoter region and intron 1. This opens new ways for studies of the gene and allows the detection of certain LDL receptor-specific deletions. For the amplification of the LDL receptor gene, spanning approximately 45.5 x 10(3) bases and divided into 18 exons and 17 introns, we have designed overlapping PCR products (ranging from 4 to 16 x 10(3) bases in length), which can be amplified simultaneously overnight for fast results. It was possible to positively identify two samples from heterozygote carriers of the "5 kB French-Canadian" deletion using this method. As a side result the length of intron 1 of the LDL receptor gene could be established to be approximately 9.5 x 10(3) bases. The method is sensitive enough to detect deletions in 1:10 mixes of positive control with wildtype DNA.

Gene Deletion↗
PubMed1996

Increased clearance of low density lipoprotein precursors in patients with heterozygous familial defective apolipoprotein B-100: a stable isotope approach.

In familial defective apolipoprotein B-100 (FDB) the presence of a mutant apolipoprotein (apo) B-100 (FDB3500Q/W) in LDL markedly reduces their affinity for the LDL receptor, leading to elevated LDL cholesterol levels. However, the hypercholesterolemia in most FDB patients is relatively mild when compared with, e.g., familial hypercholesterolemia (FH). In order to study mechanisms that may partly alleviate the clinical consequences of FDB, we investigated the in vivo kinetics of apoB-100-containing lipoproteins in five FDB heterozygotes (total cholesterol: 7.84 +/- 1.37 mmol/I; total apoB: 1.68 +/- 0.37 g/l; mean +/- SD) and six normolipidemic controls (4.61 +/- 0.62 mmol/l; 0.98 +/- 0.12 g/l) using a stable isotope approach. During and after a 10-12 h primed, constant infusion of either [13C6]phenylalanine or [2H3]leucine, tracer enrichment was determined in apoB-100 from ultracentrifugally isolated VLDL1 (Sf 60-400), VLDL2 (Sf 20-60), IDL (Sf 12-20), LDL1 (Sf 7-12), and LDL2 (Sf 0-7). The rates of apoB-100 production, catabolism, and transfer were estimated by model-based compartmental analysis. The overall fractional catabolic rate (FCR) of IDL apoB-100 in FDB was substantially increased (2.99 +/- 0.68 pools/day vs. 1.70 +/- 0.23 pools/day in controls, P < 0.01). The fractional rate of apoB-100 transfer from IDL to LDL in FDB was decreased (0.97 +/- 0.13 pools/day vs. 1.24 +/- 0.10 pools/day, P < 0.05). The FCR of LDL apoB-100 in FDB was decreased (0.18 +/- 0.07 pools/day vs. 0.56 +/- 0.05 pools/, P < 0.01). Finally, the input rate of LDL apoB-100 in FDB was markedly decreased (9.45 +/- 2.96 mg/kg day1 vs. 15.54 +/- 1.70 mg/kg day1, P < 0.05). Our data suggest that the relatively small increase of LDL concentrations in FDB is due to an increased clearance of LDL precursor particles via the LDL-receptor and apoE-receptors as well as a decreased conversion of IDL to LDL - two mechanisms that distinguish FDB from FH.

Adult↗
PubMed1995

Changes in epitope exposition of apolipoprotein A-I on the surface of high density lipoproteins after phospholipase A2 treatment.

The immunoreactivity of high density lipoprotein (HDL) modified by treatment with porcine pancreatic phospholipase A2 (PLA2) was studied in a competitive radioimmunoassay using 6 different monoclonal apolipoprotein (apo) A-I antibodies. The competition tests have shown that after PLA2 treatment the immunoreactivity of selected epitopes of apo A-I changed in different ways. While the binding behavior of two epitopes remained unchanged, three epitopes exhibited decreased immunoreactivities after phospholipids hydrolysis. In contrast to the latter epitopes, the immunoreactivity of an epitope located on the cyanogen bromide fragment 4 of apo A-I increased with the degree of lipolysis. A loss of apo A-I from HDL as a consequence of PLA2-treatment did not occur as shown by the determination of the apo A-I concentration in HDL before and after treatment with PLA2. Using overlapped synthetic decapeptides it could be shown that the epitope increasingly exposed on the particle surface of PLA2-modified HDL consists of the amino acid residues 162-173 and 212-229. These residues are characterized by high hydrophobic indices as determined by hydropathy analysis. Furthermore, these regions belong partially to the proposed receptor-binding domain of apo A-I. Thus, an increased exposition of this epitope might result in elevated cellular binding affinities of HDL occurring after modification of lipoproteins by PLA2-treatment.

Amino Acid Sequence↗
PubMed1995

Secretory group II phospholipase A2 in human atherosclerotic plaques.

Atherosclerotic plaques exhibit a series of features that are similar to those of chronic inflammation. Based on the fact that during inflammation several cell types synthesize and secrete a group II phospholipase A2 (PLA2), an immunohistochemical study was undertaken to explore whether this enzyme can be identified in human atherosclerotic lesions. Tissue specimens obtained from 13 patients who had undergone arteriectomy and three specimens with advanced atherosclerotic plaques obtained at autopsy were analyzed and compared to arteries free of atherosclerosis. The results showed that in all areas with atherosclerotic lesions, a staining with monoclonal antibodies raised against group II PLA2 was evident. In normal arteries without thickened intima, this immunostaining was completely negative. With the use of specific monoclonal antibodies against macrophages (anti-KP-1) and smooth muscle cells (anti-alpha-actin), PLA2-positive cells were identified as foam cells mainly derived from macrophages. In addition to these cells, other regions of the thickened intima gave a partially positive reaction with anti-PLA2 antibodies, but could not be stained with either anti-KP-1 or anti-alpha-actin. Some of these regions were localized on edges of calcification and cell necrosis. Other PLA2-positive regions seem to be associated with extracellular matrix structures. In summary, the findings of this study may be regarded as further evidence to support the link between atherosclerosis and chronic inflammatory processes. In view of the fact that the in vitro modification of lipoproteins by PLA2-treatment induces lipid deposition in macrophages, the results of this study suggest that group II PLA2 may actively be involved in the formation of foam cells in vivo.

Aged↗
PubMed1995

Exposure of macrophages to PLA2-modified lipoproteins leads to cellular lipid accumulations.

After a 24-h exposure of mouse peritoneal macrophages to LDL, of which the phospholipids were reduced to 30% by phospholipase A2 (PLA2)-treatment, the cellular level of free and esterified cholesterol was elevated 1.9- and 5.0-fold, respectively. Furthermore, the activity of the cytosolic acyl-CoA cholesterol acyl-transferase (ACAT), which was calculated from the rate of 14C-oleate incorporation into the cellular cholesteryl esters, increased with the degree of LDL hydrolysis. The incubation of macrophages with native HDL led to decreased labeling of cellular cholesteryl esters. However, after PLA2-treatment of HDL the esterification rate increased with the degree of hydrolysis analogous to PLA2-modified LDL. The formation of numerous intracellular lipid droplets was observed by light microscopy after staining with Sudan-III. These data suggest that phospholipases A2 may play a role in the transformation of macrophages into foam-cells, a hallmark of early atherosclerotic lesions.

Animals↗