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Biomedical subjects

G Kostner

Publications and source records attributed to G Kostner.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Mesangial lipidosis associated with cholesterol polycoria].

Accumulation of glomerular foam cells were seen in a kidney biopsy of a 59-years old patient with persistent proteinuria and mild renal insufficiency. Further investigations revealed hypercholesterolemia, hypertriglyceridemia, normal activity of LCAT, absence of lipoprotein x. Foam cells which were shown by histochemical methods to be loaded with intracytoplasmic cholesterol were found in bone marrow. These findings strongly suggest cholesterol-ester-storage disease with glomerular involvement.

Cholesterol↗
PubMed1979

Lipoprotein (a) is not a metabolic product of other lipoproteins containing apolipoprotein B.

125I-Labeled autologous very low density lipoprotein (VLDL) was injected intravenously into three lipoprotein (a) positive individuals. One other lipoprotein (a) positive subject received 125I-labeled VLDL from a a lipoprotein (a) negative donor. Specific activity of apolipoprotein B in VLDL, low density lipoprotein (LDL) and lipoprotein (a) was measured for 5 days. In the lipoprotein (a) fraction only traces of radioactivity could be detected, which were caused by contamination with labeled LDL. No precursor-product relationship existed between apolipoprotein B in VLDL or LDL and apolipoprotein B in lipoprotein (a). One lipoprotein (a)-positive individual was kept on a fat-free diet for 4 days to prevent chylomicron formation; no change in the serum level of lipoprotein (a) could be detected under these conditions. The data of this study indicate that lipoprotein (a) is not a metabolic product of VLDL or LDL. Also chylomicrons are not likely to play role as a precursor for lipoprotein (a). It is concluded that lipoprotein (a) is synthesized as a separate lipoprotein.

Adult↗
PubMed1978

The structure of human-plasma low-density lipoprotein B. An X-ray small-angle scattering study.

1. X-ray small-angle scattering of human plasma lipoprotein B of the low-density fraction (rho = 1.016--1.060 g.cm-3) has been recorded to high precision at different electron density contrasts. 2. The overall structure of the particles is characterized by a quasi-spherical shape and radial symmetry. A maximum diameter of 23 nm and a molecular weight of 2.4 X 10(6) have been determined. 3. The internal structure is described in terms of a model consisting of spherical layers with different electron densities indicating that the neutral lipids are arranged in the core of the molecule up to a radius of about 8 nm surrounded by a monolayer of free cholesterol, phospholipids and protein. The neural lipids are shown to be in an ordered, liquid crystalline state at 4 degrees C and to undergo a thermotropic transition into a disordered state at higher temperatures.

Cholesterol↗
PubMed1978

Studies on the metabolism of the lipoprotein Lp (a) in man.

Lp(a) was isolated and labeled by reductive alkylation. Radioactivity only entered the protein moiety of the lipoprotein. No change in the immunological or physicochemical properties of Lp(a) was noted after the radiomethylation. After incubation of labeled Lp(a) with whole serum for 24 h in vitro, more than 99% of the radioactivity of the incubated sample was found in Lp(a). In 4 subjects Lp(a) was injected intravenously. A linear decline of the specific activity of Lp(a) in the serum was found when it was plotted semilogarithmically against time. Half-lives of Lp(a) in the serum were 35, 38, 53 and 58 h. In one subject, the "soluble" and the "insoluble" apoproteins of Lp(a) showed the same half-life as the whole Lp(a) molecule. This suggests that no exchange of Lp(a) apoproteins with lipoproteins of other density classes took place. At different times after the injection of Lp(a), 3--8% of the radioactivity of the serum was found in Lp B, and less than 2% of the radioactivity was detectable in VLDL and the fraction having a density of greater than 1.110 g/ml.

Adult↗
PubMed1977

The structure and morphology of the abnormal serum lipoprotein-X.

The structure and morphology of an abnormal lipoprotein particle present in the serum of patients with obstructive jaundice has been investigated by gel filtration, electron microscopy and NMR spectroscopy. Lipoprotein-X is a spherical lipoprotein particle with an average Stokes diameter of approximately 40 nm and a wide size distribution ranging from 20 to 70 nm. Different from all lipoprotein structures known so far lipoprotein-X is a hollow particle (= vesicle) with a water-filled internal cavity surrounded by a continuous, single bilayer which is impermeable to cations and K3Fe(CN)6. The packing of the bilayer is tighter and the segmental motion of both the polar group and the hydrocarbon chains are significantly reduced relative to typical phosphatidylcholine bilayers. In terms of segmental motion and anisotropy of packing the lipoprotein-X bilayer closely resembles a model bilayer system consisting of phosphatidylcholine, lysophosphatidylcholine, sphingomyelin and cholesterol mixed in the same molar ratio as in lipoprotein-X. In that model system the phospholipid distribution between the two layers of the bilayer is asymmetric with (sphingomyelin + lysophosphatidylcholine) being preferentially located on the inner layer and phosphatidylcholine preferentially on the outer layer of the bilayer. By analogy with the model system the phospholipid distribution in lipoprotein-X bilayers is proposed to be also asymmetric.

Cholestasis↗
PubMed1977

The lipid bilayer structure of the abnormal human plasma lipoprotein X. An X-ray small-angle-scattering study.

The structure of the abnormal lipoprotein X occurring in the plasma of patients with obstructive jaundice was investigated by X-ray small-angle scattering. The data were analyzed by discussing the distance distribution functions obtained directly from the experimental data by Fourier transformation, involving no a priori assumptions. The results provide evidence for lipoprotein X being essentially a random distribution of lamellae with a thickness of 5.1 nm and are consistent with hollow spherical (vesicular) structures of outer diameters greater than 30 nm with some overall size heterogeneity. Under the experimental conditions chosen, lipoprotein concentrations between 0.01 and 0.18 g/ml in in buffers of low ionic strength, lateral stacking as observed in negative-stain electron microscopy does not occur. The electron density profile perpendicular to the lamellar plane indicates that a lipid bilayer is the underlying structural principle, with the protein moieties partly bound within the polar head-group regions and partly occluded in soluble form in the vesicle interior.

Cholestasis↗
PubMed1977

Familial hyper-alpha-lipoproteinaemia. Further studies on serum lipoproteins and some serum enzymes.

Some new data are given concerning a family whose members are characterized by high levels of alpha-(HDL)-cholesterol. Data from the new members of the family, not previously studied, confirm that the defect is not associated with any cardiac or neurological defect nor with xanthomata. Studies performed to assess the polypeptide composition of HDL of the affected members resulted in completely normal results. The post-heparin lipolytic activity (PHLA), the liver lipase and the lecithin-cholesterol acyltransferase (LCAT) activities also proved to be within the normal limits.

Acyltransferases↗
PubMed1976

Alteration of serum lipid values and lipoproteins by bacteria as a possible cause of artifacts in the screening of dyslipoproteinemias.

The intriguing observation of phospholipid deficiency in serum is described. The most prominent feature of sera was the completely abnormal lipoprotein electrophoretic pattern. The predominant occurrance of the phenomenon in the warm season suggested bacterial growth producing phospholipase C. B. cereus could be isolated from sera. In order to prevent these artifacts it is suggested to add 1 mg of Na2-EDTA to each ml of sample before dispatch.

Bacillus cereus↗
PubMed1974

Separation of the main lipoprotein density classes from human plasma by rate-zonal ultracentrifugation.

The major lipoprotein density classes (chylomicrons-VLDL, LDL, HDL(2) and HDL(3)) were isolated from human plasma in a two-step ultracentrifugal procedure using the Ti-14 zonal rotor. The isolation of the two major high density lipoprotein subclasses (HDL(2) and HDL(3)) was achieved in a 24-hr run using a nonlinear NaBr gradient in the density range of 1.00-1.40. The lipoproteins with a density < 1.063 found in the rotor's center were isolated in a second run of 140 min duration using a continuous linear NaBr gradient in the density range of 1.00-1.30. The isolated lipoproteins were analyzed for chemical composition and for electrophoretic mobility; purity of isolated fractions was checked by immunochemistry. The lipoproteins exhibited flotation rates, chemical compositions, and molecular weights similar to those found with the common sequential procedures in angle-head rotors. The amount of lipoprotein lipids in the bottom fraction of the zonal rotor was comparable to that of the angle-head rotor. The described method yields the main lipoprotein density classes free from albumin in a very short running time; compared with the rate-zonal techniques already in use, this method allows the quantitative separation of an additional lipoprotein density class (HDL(2)) without increasing the running time. Furthermore, this procedure proved to be suitable for isolation of plasma lipoproteins from subjects with various types and varying degrees of hyperlipoproteinemia.

Adolescent↗