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R Dargel

Publications and source records attributed to R Dargel.

At least 91 records · Page 5Linked to original sources
PubMed1984

Studies on the fatty acid synthesis of the perfused cirrhotic liver.

The fatty acid synthesis rate (using 3H2O incorporation experiments) and bile composition were studied in thioacetamide induced cirrhotic rat livers. The results show that the fatty acid synthesis rate of cirrhotic livers expressed as mumoles newly synthesized fatty acids per g liver is smaller than that of controls. Transient changes were observed in the incorporation pattern of newly synthesized fatty acids into individual lipid classes between cirrhotic and control livers. The output of bile acids is significantly decreased in cirrhotic livers.

Animals↗
PubMed1984

Structural and functional impairment of mitochondria from rat livers chronically injured by thioacetamide.

The effect of prolonged application of thioacetamide (TAA) on structural and functional properties of isolated liver mitochondria from rats was studied. Mitochondria prepared either from micronodularly cirrhotic livers (TAA application for 3 months) or from macronodularly cirrhotic ones (TAA application for 6 months) exhibited loss of respiratory control due to increased state 4 respiration and decreased state 3 respiration. The mitochondrial content of cytochromes aa3 and b was lowered only after 6 months exposure to TAA. The Mg2+ content of mitochondria from macronodularly cirrhotic livers was reduced to 50%. Mitochondria isolated from rats chronically treated with TAA exhibited lowered Ca2+ uptake rates and a decreased Ca2+ retention time. The analysis of mitochondrial phospholipid fatty acids revealed marked alterations in phosphatidylcholine and cardiolipin leading to a decreased 20:4/18:2 ratio. The functional and structural alterations of the liver mitochondria from chronically treated rats remained unaffected for at least 2 weeks after cessation of TAA application.

Acetamides↗
PubMed1984

A simple method for the isolation of highly enriched hormone-sensitive parenchymal liver cells from fetal rats.

A well reproducible method for preparing isolated parenchymal cells from fetal rat liver on the 22nd day of gestation by tryptic digestion is described including criteria for assessing their viability. The content of parenchymal liver cells was higher than 90% as could be demonstrated by light microscopic analysis of thin sections of the pelleted hepatocytes. Electron microscopic examination of the freshly prepared suspension revealed a well preserved ultrastructure of the hepatocytes. The metabolic competence of the isolated fetal hepatocytes was tested by alpha- and beta-adrenergic stimulation of glycogenolysis and glycogenolytic glucose release.

Animals↗
PubMed1983

Qualitative and quantitative changes in hepatic lipoprotein particles following acute injury of the rat liver induced by thioacetamide.

Acute intoxication of the rat liver with a single dose of 100 mg thioacetamide (TAA)/kg body weight causes within 48 h a fatty liver and a heterogeneous reaction in the hepatocytes. This affects principally the centrilobular liver parenchymal cells (zone 3) and to a lesser extent the periportal ones (zone 1). Ultrastructural analysis was performed to determine to what extent the formation of lipid-carrying particles of the very low density type (VLDL) is changed in affected hepatocytes in zones 1 and 3. Being morphologically the most conspicuous site of VLDL processing, the Golgi complex was chosen for quantitation by measuring its volume, VLDL content and particle size. The concentration and composition of the liver lipids were determined, biochemically. After TAA treatment of the liver the number of Golgi-VLDL particles is significantly reduced to about 50% in both the lobular zones examined. In addition, distinct classes of size-modified Golgi-VLDL particles appear which show an abnormally wide size distribution pattern. In periportal hepatocytes the size distribution of Golgi-VLDL particles shows a clear shift towards smaller particles homogeneous in size (mean diameter 39 nm). In contrast, centrilobular hepatocytes contain particles of very heterogeneous size, the mean diameter of which is nearly doubled (77 nm). The decrease in VLDL particle number and their size modification induced by TAA is not accompanied by significant changes in the volume of the Golgi complex. Biochemical analysis showed that the accumulation of lipids in the TAA-treated liver, mainly evident morphologically as drop-like deposits in the central area of the liver lobules, is due to an increase in triglycerides (TG) by 23 mumol/g liver wet weight, which represents nearly 95% of the accumulated lipids. Despite the striking elevation of the absolute cholesterol ester (CHOL-E) content (2 mumol/g liver wet weight), this corresponds to only 5% of the newly accumulated lipids. Our electron optical and biochemical results support the suggestion that, in spite of the markedly different intralobular reaction of TAA-intoxicated hepatocytes, the formation of triglyceride-carrying particles is altered significantly in both lobular zones examined.

Acetamides↗
PubMed1983

Effect of glucagon, phenylephrine, and isoproterenol on glycogenolysis and glucose release from fetal rat hepatocytes in suspension.

Fetal hepatocytes isolated at day 22 of gestation by trypsin digestion of rat liver retain their responsiveness to hormones. Glucagon significantly stimulates glycogenolysis and glucose release to 115 and 124%, respectively. The effect of alpha- and beta-agonists is more pronounced enhancing glycogen breakdown and glucose release to 133 and 147% (L-phenylephrine) and 183 and 202% (isoproterenol), respectively. The isolated fetal hepatocytes obtained by trypsin digestion are a useful tool for studying the hormonal control of liver metabolism during the perinatal stage without limitations met otherwise with extrahepatic factors and the effect of altered blood flow.

Animals↗
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↗
PubMed1982

[Effect of normoxic and anoxic liver perfusion as well as ischemic liver storage on parameters of mitochondrial respiration and swelling].

Using the model of Hb-free perfused rat liver, the influence of normoxic or anoxic perfusion, as well as ischemic storage of the liver on parameters of respiration and on swelling has been studied comparatively. The system used for Hb-free perfusion ensures at normoxic perfusion of the liver the functional integrity of isolated mitochondria for a period of investigation of 180 min. Normothermal ischemia of the liver leads, already after 20 min, to a significant decline of the ADP/O quotient and of the respiration control coefficient of the isolated mitochondria, as well as to mitochondrial swelling. Hypothermal ischemia of the liver (25 degrees C) clearly diminishes the mitochondrial functional loss. As far as the liver disposes of an endogenous glycogen store, the integrity of the mitochondria isolated after anoxic liver perfusion (25 degrees C) is retained and longer than after hypothermal ischemia of the liver. Mitochondria isolated after anoxic perfusion from glycogen-deprived liver swell and uncouple as fast as mitochondria prepared after ischemic storage of the glycogen-containing liver. Normoxic reperfusion of the ischemically pre-damaged liver leads to partial recovery of the mitochondria, if reoxygenation of the liver is started no later than after 80 min of ischemic storagel.

Animals↗
PubMed1981

[Heterogeneity of antimitochondrial antibodies: evidence for antigens in the mitochondrial matrix and outer membranes (author's transl)].

Human sera of patients with liver diseases (n = 7) and with systemic lupus erythematosus (n = 1) containing different antimitochondrial and other antibodies detected by immunofluorescence were reexamined after absorption with various subcellular mitochondrial fractions (whole extract, enriched inner and outer membranes, matrix, respectively). The findings were compared with those of the complement binding tests. The results suggest, that the antimitochondrial antibodies are directed against different antigens localized in the inner as well as in the outer membranes, in the matrix, and in other compartments of mitochondria, especially antibodies of type 4, 5, 7 and 8.

Adolescent↗
PubMed1980

[Development of brain lipids in rats receiving a fat-free diet with respect to myelinization].

Wistar rats were fed during the whole time of gestation with a fat-free diet. The diet regime was continued for the pups and mothers after term up to day 56 post partum. Phospholipids, cholesterol, and cerebrosides were estimated in the fetal brain at the 22nd day of gestation and in the brains of the new born animals at the 14th and 56th day post partum. The molar ratios typical for mature of myeline were followed up. Fat-free diet caused a reduction of brain weight by 50 per cent in fetuses at day 22 of gestation if compared with control animals. At day 14 and 56 post partum, however, this differences has been adjusted. Within the main phase of myelinization (14th-56th day) the brains of the diet animals showed an increased accumulation of phospholipids, a lower rise in cholesterol, and a strongly depressed accumulation of cerebrosides if compared with the control group. The results support the view that the fat-free diet may lead to a persistence of early states in mature of the myeline with an enrichment in membrane structures corresponding to early myeline.

Aging↗
PubMed1979

Effect of in vivo and in vitro application of glucagon, insulin and epinephrine on Ca++-transport properties of liver mitochondria.

In vivo administration of glucagon, insulin or epinephrine, respectively, gives rise to an increase of Ca++-retention time as well as of the Ca++-uptake rate in subsequently isolated rat liver mitochondria. Whereas the changes of Ca++-transport properties after pretreatment with glucagon or epinephrine occur already 6--15 min after their administration, the effect of insulin is observed not earlier than 30 min after its application. Under diabetic and starving conditions the Ca++-retention time of isolated liver mitochondria is prolonged, whereas no alteration of the uptake rate occurs. Since alloxan as well as streptozotocin induced qualitatively similar changes, a specific action of alloxan on liver mitochondria can be ruled out. Application of insulin 60--90 min prior to decapitation normalizes the changes of mitochondrial Ca++-transport observed under chronic alloxan diabetic conditions. Cycloheximide abolishes the prolongation of Ca++-retention in mitochondria from alloxan diabetic rats, but has no influence on the changes induced by glucagon pretreatment.

Animals↗
PubMed1978

[Control of mitochondrial Mg++-efflux].

Inorganic phosphate stimulates the release of Mg++ from liver mitochondria, depending on concentration; a concentration as low as 0.1 mM phosphate is already effective. The process is dependent on the electron transfer of the respiratory chain, and its rate is highest under conditions of endogenous respiration and with ascorbate and TMPD as substrates, respectively. The phosphate stimulated release of Mg++ is followed, with a pronounced delay, by a Ca++ efflux and a swelling of mitochondria. Addition of EGTA strongly reduced the rate of Mg++ liberation in the presence and absence of inorganic phosphate. Exogenous Ca++ is able to abolish the EGTA effect. ADP and ATP inhibit the phosphate stimulated release of Mg++. Phosphoenol pyruvate and free fatty acids enhance the rate of Mg++ and Ca++ efflux from the mitochondria. The results permit the conclusion that inorganic phosphate, Ca++ and various metabolites of the cell metabolism influence the Mg++ distribution between the extra- and intramitochondrial space, thus controlling the permeability of the mitochondrial inner membrane for monovalent cations.

Animals↗
PubMed1978

[Induction of mitochondrial volume changes by homologous O-acyl carnitines].

The volume changes of isolated rat liver mitochondria induced by O-acylcarnitines are dependent on the optical isomery and the length of the apolar hydrogen chain in the acyl residue. Within the homologous series of the straight-chain O-acyl carnitines the swelling-inducing effect increases from decanoyl carnitine to the palmitoyl carnitine. The contraction is observed only under the effect of O-acylL(--)carnitines, while isomers add up in their swelling-inducing effect. The surface activity of the O-acyl carnitines increases with increasing chain length, and the critical micellar concentration decreases logarithmically. The comparison of the tenside properties with the swelling- and contraction-inducing effects shows that the swelling is brought about by hydrophobic interactions with the membranes, while the contraction is the consequence of energy-dependent metabolic processes which are connected with the influx of acyl carnitines and the efflux of the ions from the mitochondria.

Animals↗