Reconstruction of thickness and composition of stratified materials by means of 3D micro X-ray fluorescence spectroscopy.

The recently developed 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) enables three-dimensional resolved, nondestructive investigation of elemental distribution in samples in the micrometer regime. Establishing a reliable quantification procedure is the precondition to render this spectroscopic method into a true analytical tool. One prominent field of application is the investigation of stratified material.

Expression of insulin-like growth factor-I and insulin-like growth factor binding proteins during thioacetamide-induced liver cirrhosis in rats.

Objective: The liver plays a central role in insulin-like growth factor (IGF) homeostasis providing the majority of circulating IGF-I and some of its binding proteins (IGFBPs). In liver cirrhosis the IGF axis is severely disturbed, and these alterations are associated with reduced IGF-I, IGFBP-3 but elevated IGFBP-1 serum levels.

Methods: By Northern blotting and in situ hybridization (ISH), hepatic expression of IGF-I and of IGFBP was studied in a rat model of liver cirrhosis induced by thioacetamide.

Postnatal development of hepatocellular apolipoprotein B assembly and secretion in the rat.

In this study, we explored the paradox that in suckling rats the serum concentration of LDL is high although the liver secretes only minimal quantities of VLDL, the presumed precursor of LDL. Freshly isolated hepatocytes and hepatocytes in primary culture obtained from adult (90 days old) and suckling (17 days old) rats were used to investigate the synthesis and secretion of apolipoprotein B (apoB) and lipids as well as the density profile of secreted apoB-containing lipoproteins. Furthermore, the effects of dexamethasone and oleate on apoB biogenesis were investigated in primary cultures of hepatocytes from adult and suckling rats.

Effect of bile acids on the proliferative activity and apoptosis of rat hepatocytes.

Bile acids are known to have damaging as well as protective effects on liver cells. A likely candidate for bile acid-mediated hepatocellular injury during cholestasis is glycochenodeoxycholic acid (GCDCA), a hydrophobic bile acid with a direct cytotoxic effect on hepatocytes. In contrast, ursodeoxycholic acid was shown to exhibit protective effects.

Separation of the intracellular secretory compartment of rat liver and isolated rat hepatocytes in a single step using self-generating gradients of iodixanol.

A novel method is described for the separation on a single gradient of the major intracellular organelles of the secretory pathway, the Golgi, the smooth endoplasmic reticulum, and the rough endoplasmic reticulum. Total microsomes were prepared from rat liver by differential centrifugation and resuspended in 20% iodixanol. The microsomal suspension was then layered between a 30% iodixanol cushion and a layer of 15% iodixanol and centrifuged in a vertical rotor for 2 h.

Chronic liver injury alters basal and stimulated nitric oxide production and 3H-thymidine incorporation in cultured sinusoidal endothelial cells from rats.

Background/aim: Under pathological conditions the nitric oxide synthase (NOS)-mediated nitric oxide production of sinusoidal endothelial cells might be altered. Therefore, studies were performed to evaluate the nitrite formation by cultured sinusoidal endothelial cells from rat livers chronically injured by thioacetamide and the effect of endogenously or exogenously generated nitric oxide on their proliferative activity.

Methods: Basal and stimulated nitrite formation, expression of NOS and DNA synthesis were examined in sinusoidal endothelial cells isolated and cultivated from livers with incipient or advanced chemically-induced cirrhosis.

Expression of tenascin, fibronectin, and laminin in rat liver fibrogenesis--a comparative immunohistochemical study with two models of liver injury.

The aim of this study was to follow semiquantitatively by immunohistochemical means the alterations of the expression of the hepatic glycoproteins tenascin, fibronectin, and laminin in two different models of chronic liver injury, i.e. thioacetamide-induced liver cirrhosis and fibrosis after bile duct ligation.

Differential effects of exogenous and endogenously generated H2O2 on phagocytic activity and glucose release of normal and cirrhotic livers.

Background/aims: Reactive oxygen species play an essential role in necro-inflammatory processes. Therefore, the aim of the present studies was to investigate the effect of exogenous and endogenously produced H2O2 on the phagocytic capacity and glucose release of perfused cirrhotic rat livers in comparison with that on the controls.

Methods: Complete septal cirrhosis was achieved by oral treatment of rats with thioacetamide for 6 months.

The lipid peroxidation end product 4-hydroxy-2,3-nonenal up-regulates transforming growth factor beta1 expression in the macrophage lineage: a link between oxidative injury and fibrosclerosis.

An increasing number of reports underscore the frequent association of fibrosclerotic diseases of lung, liver, arterial wall, brain, etc., with the accumulation of oxidatively modified lipids and proteins. A cause-and-effect relationship has been proposed between cellular oxidative damage and increased fibrogenesis based on the fact that experimental treatment with antioxidants either prevents or quenches the fibrotic process.

Histological and biochemical changes induced by total bile duct ligation in the rat.

The aim of the present investigation was to assess in a correlated biochemical and morphological study the dynamics of fibrogenesis after bile duct ligation and to compare the time course of alterations with those occurring in thioacetamide induced liver fibrosis. The data show that, after bile duct obstruction, the deposition of connective tissue elements and formation of ductular proliferates rapidly set in. The index of fibroplasia correlated well with the changes of the OH-proline concentration of the liver.

Macrophages from rat livers with micronodular and macronodular cirrhosis differ with respect to mediator release and DNA-synthesis.

Background/aims: Liver macrophages play an essential role in necro-inflammatory liver damage which leads to fibrosis and cirrhosis. The aim of the present study was to compare the mediator release and the DNA synthesis of macrophages at an early and at a later stage of liver cirrhosis induced by thioacetamide.

Methods: Liver macrophages were isolated by an enzymic digestion method, followed by elutriation.

Antioxidative effect of prostaglandin E2 in thioacetamide-induced liver cirrhosis.

Several studies provided evidence that various prostaglandins exhibited a hepatoprotective effect in vivo as well in vitro the mechanism of which is still in debate. Therefore, the aim of our studies was to examine the effect of PGE2 on some biochemical and morphological alterations in chemically induced liver cirrhosis in rats. A micronodular liver cirrhosis was induced by treatment of rats with thioacetamide for 3 months.

Oxygen radical formation, proliferative activity and phagocytic capacity of cultivated macrophages from cirrhotic rat livers.

A method to isolate and cultivate macrophages from Macronodular-cirrhotic rat livers was developed in order to characterize them biochemically, by comparing various functional parameters in macrophage cell cultures from controls and cirrhotic livers. Cells were prepared from female Wistar rats, made cirrhotic by treatment with thioacetamide, by means of a pronase-collagenase digestion method followed by a nycodenz gradient and elutriation. The yield of macrophages was 8.

Dexamethasone enhanced by insulin, but not by thyroid hormones stimulates apolipoprotein B mRNA editing in cultured rat hepatocytes depending on the developmental stage.

The increase of hepatic apolipoprotein B (apoB) mRNA editing during rat development was not affected by hypothyroidism. Furthermore, the addition of 3,3',5'-triiodothyronine (T3) to cultured hepatocytes taken from fetal, neonatal and adult rats had no effect on apoB mRNA editing. In contrast, dexamethasone markedly stimulated apoB mRNA editing in hepatocytes taken from neonates.

Luminol-and lucigenin-amplified chemiluminescence with rat liver microsomes. Kinetics and influence of ascorbic acid, glutathione, dimethylsulfoxide, N-t-butyl-a-phenyl-nitrone, copper-ions and a copper complex, catalase, superoxide dismutase, hexobarbital and aniline.

For the investigation of luminol (LM)-and lucigenin (LC)-amplified chemiluminescence (CL) in rat liver microsomes using both a liquid-scintillation counter (LKB/Wallac 1219 Rackbeta) and a Berthold luminometer (AutoLumat LB 953) optimal incubation mixtures and conditions and basic kinetics have been established. Whereas calibration curves for both LM- and LC-CL are performed with hydrogenperoxide (LC quantum yield is 6.25 fold higher as that of LM), distinct differences were revealed with microsomes, indicating that different reactive oxygen species (ROS) are determined: Both LM- and LC-CL follow the kinetics of enzymatic reactions in terms of dependence on protein and NADPH or NADH concentration, time course, temperature etc.

Phagocytic function and metabolite production in thioacetamide-induced liver cirrhosis: a comparative study in perfused livers and cultured Kupffer cells.

Background/aims: The aim of the study presented here was to evaluate the basal and stimulated phagocytic activities and the metabolite production of isolated perfused livers, and also the phagocytic capacity of cultured Kupffer cells from rats with macronodular cirrhosis.

Methods: Rats were made cirrhotic by oral administration of thioacetamide. The phagocytic activity was assessed by the rate of removal of colloidal carbon.

The pattern of apolipoprotein B100 containing lipoprotein subclasses produced by the isolated visceral rat yolk sac depends on developmental stage and fatty acid availability.

Explants of visceral rat yolk sacs from gestational days 16, 18 and 22 were used for studying developmental changes of secretion and density distribution of lipoproteins, particularly of those containing apoB. Moreover, the influence of fatty acid supply on the amount and density distribution of secreted apolipoproteins was studied on day 18 of gestation. Active lipoprotein production was observed in yolk sacs taken on days 16 and 18 of gestation.

Metabolism of leukotrienes is impaired in hepatocytes from rats with thioacetamide-induced liver cirrhosis.

It is likely that the hepatocellular metabolism of potent mediators of inflammation is impaired in chronic liver injury. Therefore, in this study the degradation of the leukotrienes LTC4, LTE4 and LTB4 was investigated in isolated liver parenchymal cells (LPC) from rats with thioacetamide-induced macronodular liver cirrhosis or after bile duct ligation. The degradation of LTE4 as well as the formation of N-acetyl-LTE4 was significantly delayed in LPC from macronodular cirrhotic rats but not in those from bile duct-ligated rats.

Quantitative and qualitative characterization of apolipoprotein B containing lipoproteins produced by the visceral rat yolk sac in two different in vitro systems: organ culture and isolated epithelial cells in suspension culture.

Tissue pieces as well as isolated epithelial cells taken from visceral rat yolk sacs at the 18th day of gestation were able to synthesize and to secrete apo B containing lipoproteins floating in the density ranges of VLDL, IDL and LDL. In all three density classes only the high molecular weight apo B was detectable. VLDL secreted from yolk sac tissue or isolated epithelial cells lacked apo E and apo C.

Zonal differences in lipoprotein formation in the thioacetamide-induced micronodular-cirrhotic rat liver.

The aim of the studies was to answer the question to what extent thioacetamide-induced structural alterations of hepatic architecture leading to fibrosis and micronodular pseudolobuli affect the formation of very low density lipoproteins and the zonation of lipoprotein metabolism observed in normal and acutely injured livers. Therefore, the number of the VLDL particles/Golgi complex and the relative specific volume of Golgi complexes as well as the number and relative specific volume of VLDL-filled vesicles was determined in lobular and nodular zones of normal and the micronodular-cirrhotic livers, respectively. The perinodular and centrinodular regions were morphometrically analysed in nodules with diameters between 0.

[Isolation and characterization of hepatocytes from chronic cholestatic damage to rat livers after bile duct ligation].

The aim of these investigations was the isolation and characterisation of hepatocytes from chronic injured rat livers after bile duct ligation. In three months old female Uje:WIST rats the distal common bile duct was double ligated. 14 days after the ligation 80% of the rats survived.

Stimulation of bile flow and inhibition of biliary secretion of taurocholate and leukotriene C4 in thioacetamide-induced liver fibrosis.

In order to study the relation of hepatic fibrogenesis to biliary elimination, female Uje:WIST rats were treated with thioacetamide (TAA). This treatment results in single cell necrosis, fibrosis, nodular parenchyma und proliferation of bile ducts. In isolated perfused livers from pretreated rats, liver hemodynamics, bile flow, and secretion of taurocholate and leukotriene C4 were determined.

Low-density lipoprotein catabolism does not respond to estrogen in the fetal and newborn rat.

The elimination of native and methylated low-density lipoprotein (LDL) from serum and the effect of estradiol on the serum LDL-apoB pool, the uptake of homologous [125I]-LDL into liver and adrenals, and the fractional catabolic rate (FCR) of [125I]-LDL was studied in fetal (22nd day of gestation), newborn (15th day postpartum), and adult rats. In fetal rats the receptor-mediated LDL decay accounted only for 47%, whereas in adults it was calculated to 65%. In the latter, estrogen caused (1) a diminution of the serum LDL-apoB pool by 85%; (2) an enhancement of the LDL uptake into the liver and the adrenals by 5- and 10-fold, respectively, and (3) an acceleration of the [125I]-LDL decay in the serum with a rise of the FCR by 3-fold.

Lipid peroxidation--a common pathogenetic mechanism?

Lipid peroxidation is considered at present as one of the basic mechanisms involved in reversible and irreversible cell and tissue damage. The current knowledge about the role of peroxidative breakdown of polyunsaturated fatty acids in the pathogenesis of various diseases has been reviewed. Lipid peroxidation leads to degradation of the lipid membrane, interaction of degradation products with intra- and extracellular targets and to the production of new reactive oxygen species during the course of the chain reaction thus leading to damage of cells and tissues.