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Biomedical subjects

L Winkler

Publications and source records attributed to L Winkler.

At least 55 records · Page 3Linked to original sources
PubMed1987

Preparation of apoE-free rat low density lipoprotein for catabolic studies.

The use of serum from rat fetuses instead of serum from adult rats for preparation of LDL by preparative ultracentrifugation leads to an LDL fraction containing apoB-100 and apoB-95 as the only protein moieties without need for any further purification. The yield of LDL is five times greater compared to the use of adult rat serum. Lipid composition and particle size of LDL from fetal and adult rats are quite similar. The method described allows a simple way for preparation of sufficient amounts of apoE-free LDL for use in metabolic studies.

Animals↗
PubMed1987

Very-low-density lipoproteins in the fetal rat at term.

VLDL triglyceride influx into fetal serum and the composition of fetal serum VLDL was studied in rats at term. By use of the Triton WR 1339 method the rate of VLDL triglyceride influx into fetal circulation was calculated to be 0.1 mmol/h X 1 serum in comparison to 4.2 mmol/h X 1 in adult rats. Fetal VLDL exhibit a composition differing from that of adults. The experimental data indicate that the main fraction of fetal serum VLDL represents intermediates of VLDL metabolism converted already to apolipoprotein C-free, relatively triglyceride-depleted particles.

Animals↗
PubMed1986

The role of lipoproteins in the degradation of platelet-activating factor.

Measuring both platelet-stimulating activity and liberation of acetate, the capacity of serum and individual lipoproteins to degrade the platelet-activating factor (PAF) was studied. The highest degrading effect relative to the protein content was found in very low density lipoproteins (VLDL) and in low density lipoproteins (LDL). The effect is about 10- and 100-fold higher than that of high density lipoproteins (HDL) and serum, respectively. In lipoprotein deficient serum (LPDS) less than 5% of serum activity is detectable. Considerable individual variations are observed measuring the degradation of PAF under standard conditions in plasma from 37 healthy volunteers. Moreover, this activity is shown to correlate strongly with the plasma concentration of LDL. On the other hand, a significant negative correlation was found between the PAF-degrading capacity and the plasma concentration of HDL. In contrast, the PAF-degradation is unrelated to the concentration of plasma triglycerides. The results point to a possible role of plasma lipoproteins in regulating the degradation of PAF released into the circulation.

Humans↗
PubMed1986

Endogenous lipoproteins modify the thromboxane formation capacity of platelets.

A significantly negative correlation was demonstrated between HDL-cholesterol levels of serum and the thromboxane B2 (TXB2) formation in clotted whole blood, whereas a significantly positive correlation was estimated between the LDL cholesterol or apolipoprotein B (apo B) levels and the TXB2 formation in clotted whole blood. Similar relationships were observed between the HDL and apo B serum levels and the thrombin-induced malondialdehyde formation in platelet-rich plasma. The levels of HDL2 cholesterol, total cholesterol, apo A-I and of triglycerides were not significantly correlated with the TXB2 or malondialdehyde formation in both systems. The results in this study support the hypothesis that the TXB2 formation may be modulated by endogenous lipoproteins: high level of LDL stimulates and high level of HDL inhibits the TXB2 formation.

Adult↗
PubMed1985

Glucocorticoid receptors in sheep brain tissues during development.

In this study we describe changes in the number of glucocorticoid binding sites that occur in cytosols of pituitary, hypothalamic, and hippocampal tissue obtained from fetal, newborn, and adult sheep. We observed specific, saturable binding of [3H]triamcinolone acetonide by cytosols of all three tissues. There were both age-related and tissue-related differences in the number of binding sites observed. By midgestation (70 days) significant quantities of binding sites were present in pituitary and brain tissues, and the number remained relatively constant throughout gestation and in the neonatal period. The number of binding sites declined markedly in cytosols from adult tissues. At all ages there were more binding sites present in pituitary cytosols than in cytosols of hypothalamus and hippocampus. The sucrose density gradient profile of the radioactive ligand-binding site complex is characteristic of a glucocorticoid receptor. Thus, by midgestation at least a portion of the biochemical machinery mediating glucocorticoid effects is present in the fetal pituitary and in specific brain tissues considered important in the modulation of ACTH secretion by corticosteroids.

Animals↗
PubMed1985

[Stomach cancer survival rates].

The cumulative 5-year survival rates in the case material of the years 1979-1983 with endoscopically-histologically confirmed gastric carcinoma were compared to those of the 1974-1978 period, particularly with reference to operative therapy and the histological type of carcinoma. The percentage of curatively operated patients increased from 40.6 to 49.7%, the rate of non-operated patients fell from 42.5 to 22.4%. The histological evaluation revealed a rise in the percentage of the adenocarcinoma from 37.1 to 53.5%-while the percentage of the solid carcinoma decreased from 29.1 to 15.5%. Following curative therapy, the calculated cumulative 5-year survival rate rose from 35.6 to 51.8% in men, however, fell from 66.2 to 48.3% in women. Most recent investigations showed men with curatively operated adenocarcinoma to have the best survival rate (60.6%); in women, this is true of mixed-type carcinoma.

Adenocarcinoma↗
PubMed1983

[The lipoprotein status of fetal minipigs].

VLDL, LDL and HDL of fetal minipigs were isolated by preparative ultracentrifugation from serum at term. Concentration and lipid composition were evaluated in the fractions and compared with the corresponding data obtained in the adult animal. The concentration of VLDL lipids in fetal serum amounts to 50% (p less than 0.05), that of HDL lipids to 63% (p less than 0.01), and that of LDL lipids to 75% (n. s.) of the values seen in adult minipigs. With the exception of the increased cholesterol content of fetal VLDL there were no significant differences in the composition of the density classes between fetuses and the adult animals. Our results demonstrate a general difference between the lipoprotein pattern in the fetal state of minipigs and of human beings brought about, in particular, by the pronounced disparity of the materno-fetal gradient of VLDL, LDL, and HDL.

Aging↗
PubMed1982

[Electrophoresis studies of the pre-natal status of serum lipoproteins of various species].

The relative proportions of alpha-, beta-, and pre-beta-lipoproteins in the fetal serum of mouse, rat, rabbit, guinea pig, mini-pig, and man were determined by agarose gel electrophoresis and subsequent scan evaluation. No distinct species-independent, fetal-specific common features could be detected. In mouse, rabbit and rat an increase in alpha-lipoproteins and a decrease of the proportion of beta-lipoproteins can be observed during prenatal development. In human cord serum of the 30th week alpha-LP are prevalent; at delivery their proportion is still 50%, like in the serum of adults. Five of the species investigated reveal low, if any, pre-beta-lipoprotein levels in fetal serum, while those in the adult organism amount to 19-33%. The lipoprotein spectrum of the mini-pig at the end of the gestational period is identical with that of the adult animal. In the serum of the fetal and adult guinea pig no alpha-lipoprotein band is detectable. On the other hand, a pre-albumin fraction appeared in the prenatal period, amounting to 25% of total lipoproteins. In total, the findings reported here reflect a largely species-specific development of the fetal lipoprotein patterns.

Animals↗