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Results for “PORTACAVAL ANASTOMOSIS”

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PubMed1977

[Hexobarbital-oxidation in vivo and in vitro in rats after phenobarbital-pretreatment or after portacaval anastomosis (author's transl)].

Male rats were pretreated with phenobarbital for 5 days or received portacaval anastomosis 3 weeks before. Hexobarbital was applicated intravenously and hexobarbital plasma concentrations were followed up gaschromatographically in arterial blood samples. Hexobarbital clearance was calculated from the plasma concentration curve versus time. Liver microsomes were prepared and cytochrome P 450 and the hexobarbital oxidation rate was determined. After portacaval shunt the animals showed a small liver, a reduced cytochrome P 450 and diminished hexobarbital oxidation rate. Hexobarbital clearance in vivo was reduced, too. After phenobarbital pretreatment liver weight increased and cytochrome P 450 and hexobarbital oxidation rate were distinctly enhanced. The hexobarbital clearance in vivo were increased. Since the plot of hexobarbital clearance in vivo versus cytochrome P 450 or versus hexobarbital oxidation rate in vitro gave a good correlation, it is concluded that hexobarbital clearance in vivo may be a good estimate for hepatic cytochrome P 450 and hepatic hexobarbital oxidation rate.

Animals↗
PubMed1978

[Acid-base metabolism in patients with hepatic cirrhosis treated with portacaval anastomosis at various intervals after the operation].

In a series of 68 cirrhotics subjected to portacaval anastomosis for digestive haemorrhage, alterations in the acid base balance, 3, 6, 12, 24 and 48 weeks after anastomosis, were examined. Following operation, an increase in the incidence of the usual acid base disturbances of liver cirrhosis is observed. Respiratory alkalosis increases with no direct relationship to teh postoperative increase in ammoniemia, the main stimulating agent of the resporatory centres. This is probably because the active fraction on the nerve cells is the non-ionized one only, freely diffusible through the haematoencephalic barrier, the plasma concentration of which is a function of blood pH. Postoperative metabolic alkalosis is secondary to the potassium and chloride depletion consequent on operative trauma, on the malnutrition syndrome and, in the case of potassium, on secondary hyperaldosteronism which, unlike what is observed in the other groups of cirrhotics, is uncorrected by anastomosis. After the shunt, metabolic acidosis may be the expression of an increase in lactates and pyruvates following on further liver function deterioration, and of a functional renal insufficiency which anastomosis makes more manifest.

Acid-Base Equilibrium↗
PubMed1985

Hyperplastic foci in the atrophic liver of rats after portacaval anastomosis.

Hyperplastic focal areas were investigated in livers of male rats 1 and 9 months after portacaval anastomosis (PCA) by light and electron microscopy. These alterations, predominantly found in periportal areas, were characterized by light microscopy as clusters of enlarged hepatocytes along narrowed sinusoids, contrasting in the remaining liver acinus with smaller hepatocytes along widened sinusoids. No differences were observed between 1 and 9 months PCA except for glycogen content, which was homogeneously distributed in the liver at 1 month but completely lacking in foci at 9 months. The most striking ultrastructural alterations were the sinusoids delimited in these hyperplastic areas by a thickened barrier consisting of thick endothelial cells encircled by numerous subendothelial processes of the perisinusoidal fat-storing cells. Deep and widened recesses of the sinusoidal lumen separated the two-cell-thick plates of the hyperplastic cells. Hepatocytes in foci, thought to represent regenerative areas, tend to increase their exchange surface. Their progressive loss in glycogen and their two-cell-thick plates architecture should be in favour of a potential malignancy. However, the spontaneous evolution of these foci which do not necessarily give rise to nodules, as well as the lack of other features of transformation, do not support this possibility.

Animals↗
PubMed1983

Regional cerebral glucose utilization in rats with portacaval anastomosis.

Regional cerebral glucose utilization was measured using [2-14C]glucose in rats with an end-to-side portacaval anastomosis. The experiments were conducted in two groups of rats 4 to 8 weeks after portacaval shunting was established. One group was paralyzed and given N2O:O2 (70:30), whereas the other was conscious, unstressed, and unaware of the experiment. In both groups the rate of glucose utilization was decreased in almost all brain structures by an average of 20% after portacaval shunting. The results showed definitively that cerebral energy metabolism was reduced at a time when there were no obvious neurological abnormalities.

Animals↗
PubMed1996

A low-protein diet ameliorates disrupted diurnal locomotor activity in rats after portacaval anastomosis.

In previous studies we noted a disruption of the circadian locomotor activity rhythm in rats after portacaval anastomosis (PCA). To examine whether this abnormality is related to factors that aggravate hepatic encephalopathy in humans, we studied the effect of dietary formulation and protein content on body weight, locomotor activity, and entrainment to the light-dark cycle in rats after PCA or sham operation. Postoperative weight loss was prevented by pair-feeding with a purified liquid diet. However, the behavioral abnormalities persisted in PCA rats fed a high-protein diet, with a reduction in total activity and entrainment to the light-dark cycle. These were ameliorated by a low dietary protein content. Since this treatment reduces the load of gut-derived nitrogenous substances that might alter brain metabolism, our data strengthen the hypothesis that the abnormal circadian activity patterns in PCA rats may be part of the spectrum of hepatic encephalopathy.

Animals↗
PubMed1984

Spontaneous motor activity increases after portacaval anastomosis in rats.

Spontaneous motor activity was monitored in rats at various times, up to 14 weeks, after portacaval anastomosis (PCA) or sham operation. Total 24 hour activity scores rose significantly after PCA and remained significantly higher than those of sham operated rats for twelve weeks. After PCA, activity during the twelve hour lighted period was greatly increased, whereas dark period activity was unchanged. Increased activity in the light period was found to be well correlated with the degree of elevation in brain concentrations of tryptophan, tyrosine, phenylalanine and glutamine. These results are consistent with previously reported EEG studies and suggest that motor-activity measurement may facilitate the correlation of biochemical changes with behaviour in rats with portal systemic shunting.

Amino Acids↗
PubMed1980

Effect of portacaval anastomosis on hypersplenism.

Leukopenia, thrombocytopenia, and hemolytic anemia occur commonly in advanced cirrhosis. Some investigators have reported that portacaval anastomosis (PCA) abolished hypersplenism while others have not found PCA to be uniformly beneficial. We compared the frequency of hypersplenism before and after admission to a controlled investigation of the effects of PCA in 52 unoperated control subjects and 38 patients with patent PCA. The two groups were followed for an average period of 5 1/2 years. On admission to the study leukopenia was present in about 2% of patients, thrombocytopenia in 6%, and hemolytic anemia in 4%. Splenomegaly was present in 48% and hypersplenism in 11%. After randomization splenomegaly disappeared more frequently in the shunted group. In addition, fewer patients with PCA developed splenomegaly for the first time after inclusion into the study than did unoperated control subjects. Leukopenia, thrombocytopenia, and hemolytic anemia, when present at inclusion into the study, disappeared with equal frequency in the shunted and unshunted patients, and appeared with equal frequency in both groups after randomization in previously unaffected patients. In no instance was hypersplenism clinically significant nor was splenectomy considered or carried out in any of these 90 patients. In additional uncontrolled studies we observed that therapeutic PCA did not affect hypersplenism differently from prophylactic PCA. We conclude that PCA has neither clinically nor statistically significant effects on hypersplenism.

Anemia, Hemolytic↗
PubMed1994

Effects of portacaval anastomosis on pancreatic islets of the rat.

The pancreatic islets of rats with surgically constructed end-to-side portacaval anastomosis were studied immunocytochemically, morphometrically, and ultrastructurally, and the plasma levels of glucose, insulin, and glucagon determined. The results of the current study show that, four weeks after surgery, hypoglycemia, normal insulinemia, and hyperglucagonemia occur and that these hematologic changes are associated with immunocytochemical and ultrastructural signs of impairment of the secretory activity of islet B cells and normal secretion pattern of the remaining islet cell types. The causes and the meaning of the hematologic and islet cell changes are discussed, and the hypothesis has been drawn that they are primarily related to the functional deterioration of the liver, which follows the diversion of the portal blood in the systemic circulation.

Animals↗
PubMed1987

Experimental intrahepatic portacaval anastomosis: use of expandable Gianturco stents.

Original Gianturco expandable stents and their modifications were used to create an experimental intrahepatic portacaval anastomosis (EIPCA) in 30 young domestic swine without portal hypertension. The study focused on the design of a suitable stent, the technique of its application, and the evaluation of short-term patency of the EIPCA. A stent with a 2.5-cm-long body and wire skirts on both ends was most suitable for EIPCA creation. Well-positioned stents shunted most of the portal blood in the inferior vena cava circulation and remained patent for 4-6 weeks. Ingrowth of liver parenchyma and abundant proliferation of the intima and connective tissue inside the stent lumen in these rapidly growing animals gradually decreased EIPCA patency, and thrombus formation with diminished blood flow closed them completely.

Animals↗
PubMed1983

Portacaval anastomosis in rats: effects on behavior and brain serotonin metabolism.

The behavior of male rats with chronic end-to-side portacaval shunts or control surgery were evaluated in a complex enclosed maze, an open-field arena, and a swim canal. Subsequently, serotonin and 5-hydroxyindoleacetic acid levels were measured for hypothalamus, striatum, hippocampus, and midbrain-medulla. Chronic portacaval anastomosis did not significantly alter any of the behavioral parameters evaluated in the diverse test situations studied, despite a significant elevation of 5-hydroxyindoleacetic acid levels in all brain regions analyzed and the elevation of serotonin levels in hypothalamus and midbrain-medulla.

Animals↗
PubMed1986

Regional blood-brain barrier transport of glucose after portacaval anastomosis.

The regional influx of glucose across the blood-brain barrier was measured in rats 5 to 6 weeks after a portacaval anastomosis or sham operation. D-[14C]Glucose was infused intravenously for 15 sec while arterial blood was sampled continuously for measurement of plasma radioactivity and glucose concentration. Brain tissue radioactivity was measured by quantitative autoradiography. Glucose influx and plasma clearance (permeability times surface area; PS) were calculated from the net disintegrations per minute per gram in brain, the plasma radioactivity integral, and the plasma glucose concentration. In shunted rats influx was decreased by about 22% (in the brain as a whole) compared to that in controls. This decrease was almost entirely due to the decrease in plasma glucose concentrations (27%). The PS, normalized to take plasma concentrations into account, showed a slight decrease in most of the brain except the telencephalon. For the brain as a whole this decrease amounted to 11%. The regional PS and glucose utilization are known to be coupled and the relationship between these was the same in sham-operated and shunted rats. The decrease in PS observed in shunted rats was commensurate with their lower rates of glucose use; thus, the transport process of glucose from plasma to brain appeared to be unaffected by portacaval shunting.

Animals↗
PubMed2003

Vasopressin accelerates experimental ammonia-induced brain edema in rats after portacaval anastomosis.

BACKGROUND/AIMS: Cerebral hyperemia is an important contributor to the development of brain edema in fulminant hepatic failure. Rats receiving an ammonia infusion after portacaval anastomosis (PCA) demonstrate a rise in cerebral blood flow (CBF) with brain edema at 180 min. Vasopressin (VP), a systemic vasoconstrictor which in the rat dilates cerebral vessels through V(2) receptors, was used to ascertain the effects of increasing CBF. METHODS: Changes in CBF were measured with Laser Doppler flowmetry (LDF). Absolute CBF was measured with radioactive microspheres to calculate oxygen and ammonia uptake. RESULTS: Compared to the NH(3)+Vehicle group, VP+NH(3) infusion accelerated the rise in CBF (117+/-21 vs. -6+/-12%, P<0.01), and the development of brain edema (81.09+/-0.17 vs. 80.29+/-0.06%, P<0.01). Radioactive microspheres confirmed these results (254+/-44 vs. 106+/-9.5 ml/min/100 g, P<0.01). Oxygen uptake was similar. Ammonia uptake was more than twofold higher in the VP+NH(3) group. A V(1) antagonist negated the higher mean arterial pressure (MAP) that occurs with VP but cerebral hyperemia still occurred. A V(2) antagonist resulted in similar systemic pressures, CBF and brain water compared to the VP+NH(3) group. CONCLUSIONS: In this model, an increase in CBF with VP hastens the development of brain edema while increasing ammonia delivery to the brain.

Ammonia↗
PubMed1999

Effect of portacaval anastomosis on glutamine synthetase protein and gene expression in brain, liver and skeletal muscle.

The effects of chronic liver insufficiency resulting from end-to-side portacaval anastomosis (PCA) on glutamine synthetase (GS) activities, protein and gene expression were studied in brain, liver and skeletal muscle of male adult rats. Four weeks following PCA, activities of GS in cerebral cortex and cerebellum were reduced by 32% and 37% (p<0.05) respectively whereas GS activities in muscle were increased by 52% (p<0.05). GS activities in liver were decreased by up to 90% (p<0.01), a finding which undoubtedly reflects the loss of GS-rich perivenous hepatocytes following portal-systemic shunting. Immunoblotting techniques revealed no change in GS protein content of brain regions or muscle but a significant loss in liver of PCA rats. GS mRNA determined by semi-quantitative RT-PCR was also significantly decreased in the livers of PCA rats compared to sham-operated controls. These findings demonstrate that PCA results in a loss of GS gene expression in the liver and that brain does not show a compensatory induction of enzyme activity, rendering it particularly sensitive to increases in ammonia in chronic liver failure. The finding of a post-translational increase of GS in muscle following portacaval shunting suggests that, in chronic liver failure, muscle becomes the major organ responsible for the removal of excess blood-borne ammonia.

Ammonia↗
PubMed1985

Relationship of brain glutamine and brain neutral amino acid concentrations after portacaval anastomosis in rats.

Evidence from several sources suggest that blood-brain transport of the large neutral amino acids (NAA) is abnormal in animals with a portacaval anastomosis (PCA) and in patients with liver cirrhosis and portal-systemic shunting and encephalopathy, but the underlying mechanisms are unknown. After PCA, the concentration of glutamine (Gln) in brain is markedly increased as a by-product of cerebral ammonia detoxification, and the rate of efflux of Gln from brain is also increased. The following studies were undertaken to clarify the relationships among plasma and brain concentrations of NAA after PCA in rats and to examine the relationship of brain Gln concentration to plasma and brain NAA concentrations. After PCA plasma phenylalanine, tyrosine and histidine were elevated and leucine, isoleucine and valine were lowered. In brain, phenylalanine, tyrosine, histidine and methionine were markedly elevated after PCA and their concentrations in brain far exceeded the concentrations in plasma. Analyses of single, partial and multiple correlations of plasma NAA ratios expressed as plasma competitor function (PCF), brain NAA and brain Gln showed significant correlations between PCF nd brain NAA in shunted rats. A better correlation was found between brain NAA and brain Gln. Correlation coefficients obtained from multiple correlation analysis equalled or exceeded those obtained in the partial correlation or in the single correlation, suggesting that the effects of PCF and brain Gln on brain NAA were separate and additive. Gln was shown to compete with other NAA for blood brain transport by inhibiting brain 14C phenylalanine uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1983

A morphometric and ultrastructural study of the long term effect of portacaval anastomosis on the liver of normal male rats.

A morphometric analysis of the lobular components of the liver of normal male rats up to 6 months from portacaval anastomosis revealed that the mean volume of each hepatocyte decreased about 30-40% in normally fed rats and this was associated with a shrinkage of the lobular tissue. A 10% reduction of the total hepatocyte volume density in the lobule and a net increase in time of the fat storing cell volume density could be measured, whereas the intralobular collagen decreased. Within the hepatocytes a persistent significant increase of fat globules was observed; an increase in the first period, followed by a decrease of the lysosomal component. The Golgi complex tended to decrease in the first period, then exhibited a volume density even higher than in the controls. A small reduction of the rough endoplasmic reticulum and a conspicuous reduction of the smooth endoplasmic reticulum and, in fed animals, of the glycogen content were also observed. These alterations were persistent with periods of up to 6 months from the anastomosis and were present in all the functionally distinct lobular zones. From the ultrastructural point of view, apart from variations due to the quantitative changes described above, both lobular and hepatocytic components were identical to those of age matched controls at all times from the intervention. The ultrastructural damages described by others could not be observed.

Animals↗