Ultrastructural study of the different zones of the rat liver acinus after portacaval anastomosis]

Liver atrophy is a main feature in rats with a porto caval shunt. Histological studies revealed small size hepatocytes. Ultrastructural differences between periportal and centrolobular zones were noticed, in particular, the dilatation of the nuclear envelope and of the rough endoplasmic reticulum which appeared dilated, desorganized and sometimes without ribosomes, was more pronounced in the periportal zone. Hepatocytes of this zone might be more sensitive to the decrease of O2 and/or hepatotrophic factors.     

Effect of portacaval anastomosis on rat lipoproteins

The distribution of cholesterol (C), triglycerides (TG), phospholipids (PL) and protein in the different lipoproteins was studied in male Wistar rats under 2 conditions: control and 2 months after portacaval anastomosis (PCA). PCA decreased the levels of cholesterol and the other components in chylomicrons (-90%), very low density lipoproteins (-65 to -78%), LDL2 (1.040 less than d less than 1.063 g/ml; -51 to -61%) and HDL (1.063 less than d less than 1.21 g/ml), whereas no change was observed in LDL1 (1.006 less than d less than 1.040 g/ml). Apoprotein C contents were decreased in all lipoproteins. The relative proportions of C, TG, PL and proteins in lipoproteins were essentially unchanged by the shunt, suggesting a reduced number of lipoprotein particles in plasma after PCA. It was concluded that PCA reduced the levels of all lipoproteins secreted by liver and/or the intestine without modifying those of intraplasmatic origin (LDL1).     

Promoting effect of portacaval anastomosis in experimental hepatic carcinogenesis

A promoting effect of portocaval anastomosis in a triphasic model of rat hepatocarcinogenesis is demonstrated since after initiation and selection premalignant lesions and hepatocellular carcinomas increase. This demonstrates that chronic administration of an exogenous compound is not the only way to promote cancer development.     

Altered expression of genes regulating skeletal muscle mass in the portacaval anastomosis rat

We examined the temporal relationship between portacaval anastomosis (PCA), weight gain, changes in skeletal muscle mass and molecular markers of protein synthesis, protein breakdown, and satellite cell proliferation and differentiation. Male Sprague-Dawley rats with end to side PCA (n=24) were compared with sham-operated pair-fed rats (n=24). Whole body weight, lean body mass, and forelimb grip strength were determined at weekly intervals. The skeletal muscle expression of the ubiquitin proteasome system, myostatin, its receptor (the activin 2B receptor) and its signal, cyclin-dependent kinase inhibitor (CDKI) p21, insulin-like growth factor (IGF)-I and its receptor (IGF-I receptor-alpha), and markers of satellite cell proliferation and differentiation were quantified. PCA rats did not gain body weight and had lower lean body mass, forelimb grip strength, and gastrocnemius muscle weight. The skeletal muscle expression of the mRNA of ubiquitin proteasome components was higher in PCA rats in the first 2 wk followed by a lower expression in the subsequent 2 wk (P<0.01). The mRNA and protein of myostatin, activin 2B receptor, and CDKI p21 were higher, whereas IGF-I and its receptor as well as markers of satellite cell function (proliferating nuclear cell antigen, myoD, myf5, and myogenin) were lower at weeks 3 and 4 following PCA (P < 0.05). We conclude that PCA resulted in uninhibited proteolysis in the initial 2 wk. This was followed by an adaptive response in the later 2 wk consisting of an increased expression of myostatin that may have contributed to reduced muscle protein synthesis, impaired satellite cell function, and lower skeletal muscle mass.     

Morphofunctional express-diagnosis of liver conditons]

Methods of simultaneous detection of the vitally-essential indices of the hepatic tissue status by injecting neutral red vital dye into the portal vein are described. The liver tissue morphological status, the hepatic cell absorbing capacity, the blood microcirculatory efficacy and the pH shift were assessed on a histological preparation from the liver slice. The dye was extracted from the other portion of the same liver slice and the total amount of the dye absorbed was estimated.     

Morphofunctional aspects of the head capsule topography in Aculeata (Hymenoptera)]

According to degree of segmental fusion insect head is the most integrated part of the body. Head skeleton subdivides into capsule and skeleton of appendages. Exo- and endoskeleton (tentorium) of head capsule have complex segmental origin. Marked margins are generally absent between such traditionally discriminated capsule parts as clypeus, frons, vertex, occiput, genae, etc. Relative position to marked structures (appendages, eyes, ocelli, occipital foramen and etc.) defines the capsule parts, but homologization of last ones is complicated both by absence of substantive functions and complex segmental origin. Based on the technological point of view author characterizes head capsule construction in Aculeata. Capsule parts were studied as components of six technological systems associated with the head: maxillolabial, antennal, pharyngeal, optical, cranio-articulate and mandibular. Spatial relations, named by I.I. Schmalhausen as topographical co-ordinations, integrate head systems. Therefore relative position of the capsule parts incorporated in such systems is unvaried under any reconstruction. At the same time varieties of their forms and proportions reflect on form and topography of capsule as a whole. Comparative analysis of the capsule construction in Bethyloidea, Formicoidea, Sphecoidea, Vespoidea, Pompiloidea and Scolioidea has shown that many differences are determined by mutual modification of technological systems. In particular the increase in head elevation related with reconstruction of cranio-articulate system is accompanied with the shift of antennae to anterior end of the head. The capsule construction in Aculeata considered to be represented by hypognathous, prognathous and hypo-prognathous morphological types that determine head orientation towards longitudinal body axis. The role of topographical co-ordinations in formation of prognathous or hypognathous condition of the head in Aculeata is discussed.     

Regional alterations of dopamine and its metabolites in rat brain following portacaval anastomosis

Hyperammonemia and changes in brain monoamine metabolism have been proposed to contribute to the pathogenesis of the neuropsychiatric symptoms characteristic of human portal-systemic encephalopathy (PSE) resulting from chronic liver disease. Portacaval anastomosis (PCA) in the rat leads to sustained hyperammonemia and mild encephalopathy. In order to evaluate the role of dopamine (DA) metabolism in PSE, levels of DA and its metabolites were measured by HPLC with electrochemical detection in brain regions of rats with PCA at various stages of encephalopathy precipitated by ammonium acetate administration. Following ammonium acetate administration, rats with PCA rapidly develop severe neurological signs of encephalopathy progressing through loss of righting reflex to coma; sham-operated control animals administered ammonium acetate showed no such neurological deterioration. Concentrations of the DA metabolites DOPAC and HVA as well as [DA metabolites]/[DA] ratios, an indirect measure of DA turnover in brain, were increased in caudate-putamen, in cingulate and pyriform entorhinal cortices as well as in raphe nucleus and locus coeruleus. Increased DA metabolites, however, did not worsen at coma states of PSE. Increased DA turnover thus appears to relate to early neuropsychiatric and extrapyramidal symptoms of PSE.     

Effect of portacaval anastomosis on the activities of hepatic enzymes related to cholesterol and bile acid metabolism in rats.

1. The effect of a portacaval anastomosis on the activities of hepatic enzymes related to cholesterol metabolism was investigated in rats. 2. Portacaval anastomosis led to a fall in body weight and liver weight/body weight ratio, and to a rise in the activities of hydroxymethylglutaryl-CoA reductase and cholesterol 7alpha-hydroxylase per g of liver. The net effect was to maintain a normal activity of both enzymes per 100 g of rat. Diurnal rhythm in the activities of both enzymes was maintained after portacaval anastomosis. 3. The rate of excretion of total bile acids, per 100 g of rat, in bile fistula rats was not significantly decreased by portacaval anastomosis.     

Ultrastructural organization of the septum pellucidum in dogs subjected to long-term partial intraspecific isolation

The dogs have been kept under conditions of a partial intraspecific isolation for a long time, beginning from early stages of the postnatal ontogenesis. The reactive changes in neurons, interneuronal contacts are shown to produce proliferation of neuroglial cells and a number of their ultrastructural reorganizations. Phagocytic cells--astrocytes and microgliocytes--activate. However, enhancement of trophic processes is noted, manifesting itself as hyperplasia of lamellar processes of astrocytes in the neuropil, as an increased number of neurons with subsurface cisterns, in their area an astrocyte process is constantly revealed.