Hepatic levels of prostaglandins F2α and I2 (prostacyclin) and of thromboxane A2 in dogs developing hemorrhagic shock

Professorial Department of Surgery, L'vov Medical Institute. L'vov Branch, Kiev Research Institute of Hematology and Blood Transfusion. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Savel'ev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 2, pp. 134–135, February, 1992.     

Artificial liver

Without transplantation, approximately 90% of patients with fulminant hepatic failure die. If patients receive a liver transplant, there is often a lag between the need for and the availability of a donor liver. Therefore, there is a definite need for a liver support system to support the patient's own liver function in fulminant hepatic failure and while awaiting transplantation. We have developed an artificial liver system that not only eliminates lipophilic toxins such as phenols, fatty acids, and mercaptans, but also hydrophilic ones such as ammonia. This artificial liver system consists of a monitor, an extracorporeal blood circuit that uses a hydrophilic polysulfone high-flux dialyzer to remove water-soluble metabolites, and a novel hydrophilic liquid membrane filter to remove lipophilic toxins. In more than 100 in vitro experiments using porcine (5 I) blood, the system was evaluated for its ability to remove toxins that are normally increased in hepatic failure. We found that phenol, cresol, and short- and medium-chain fatty acids can be almost completely eliminated from the blood within 5 h. In animal experiments using pigs, we also found no significant changes of blood gases, liver parameters, electrolytes, and blood cell counts.     

The role of spontaneous portosystemic shunts in the course of orthotopic liver transplantation

Spontaneous portosystemic shunts are commonly found in cirrhotic patients. Not yet established is their role after orthotopic liver transplantation (OLTx), especially when an increase in portal pressure develops, as during early acute rejection. In this study, 34 cirrhotic patients in a series of 70 OLTx are considered. Each patient had preoperative angiographic assessment, and, in 21 (62%), large spontaneous portosystemic shunts were evident. In 12 cases the shunts were not affected by the surgical procedure and were present during the postoperative period; in 9 the hepatectomy itself involved interruption of the shunts. The patient population was divided into two groups: patients with postoperative shunts (n=12) and those without (n=22). The two groups were similar in age, sex, Child's stage, transplantation variables, and number and grade of rejection episodes. However, mean transaminases (AST) values in the first 2 weeks were significantly higher levels in shunt versus nonshunt patients (421±335 vs 183±126; P<0.025), and this was even more evident when rejection occurred (626±375 vs 195±129; P<0.001). Furthermore, during an acute rejection reaction, three cases showed a true steal phenomenon through the large reopened shunts with ischemic damage to the grafts. The data indicate a possible detrimental effect of the spontaneous shunts on graft perfusion and suggest the prophylactic surgical interruption of the residual shunts during the transplantation.     

Sonographic patterns of Caroli's disease: report of 5 new cases.

We have reviewed 5 cases of Caroli's disease, studied from 1982 to 1987, in order to define the validity of its sonographic signs. The "intraluminal portal vein" sign, found in all the cases, is emphasized. This sign may be easily identified and it is never encountered in other diseases. Recessive polycystic kidney disease was present in 3 cases, and congenital hepatic fibrosis was demonstrated in the 2 cases studied by liver biopsy.     

Receptor-recycling model of clearance and distribution of insulin in the perfused mouse liver

Summary After perfusion of mouse livers with A₁₄-¹²⁵I-insulin for designated intervals, an acid-wash technique was employed to separately measure the surface-bound (X_s) and intracellular (X_i) A₁₄-¹²⁵I-insulin, as well as intracellular degradation products (X_deg) of labelled insulin. From the perfusate concentrations (C_p) of A₁₄-¹²⁵I-insulin, the apparent intrinsic hepatic clearance of labelled insulin at a high dose (0.2 nmol/l) was shown to be 60% smaller than that at a low dose (0.018 nmol/l), indicating that the cellular uptake of insulin is remarkably nonlinear at the concentration range examined. From the time courses of C_p, X_s, X_i and X_deg, the hepatic insulin disposition was shown to be largely accounted for by the receptor-mediated endocytosis. The observed data at the low dose were analysed to estimate biochemical parameters, (i.e., total receptor number, endocytotic rate constant and intracellular degradation rate constant) according to receptor-recycling and non-receptor-recycling models, using a computer-aided optimization procedure. The receptor-recycling model could not only adequately explain the C_p, X_s, X_i and X_deg at the low dose, but also predict the C_p at the high dose. On the other hand, a non-receptor-recycling model, in which recycling of receptors was not assumed, could also explain the observed data at the low dose, but failed to predict the C_p at the high dose, indicating that the receptor recycling process is necessary to explain the hepatic insulin clearance at high insulin concentrations, at which hepatic insulin clearance should be limited by the rate of receptor recycling. However, the applicability of our model might be limited within the physiologic insulin concentrations, because of the negative co-operativity of insulin-receptor interaction and a high-capacity, non-degradative and more rapidly recycling pathway for receptors that may occur at high concentrations of insulin. In conclusion, we have developed a mathematical model of hepatic insulin clearance and distribution under physiological conditions, including receptor binding, receptor-mediated endocytosis and receptor recycling, which has been so far demonstrated using isolated hepatocytes.     

Prognostic value of galactose elimination capacity,aminopyrine breath test,and ICG clearance in patients with cirrhosis

Seventy-eight patients with cirrhosis were prospectively followed for up to 20 months, on the average. At entry into the study, galactose elimination capacity, aminopyrine breath test, and ICG clearance were measured. At the end of the study, 27 patients had died. Univariate analysis using the Kaplan-Meier method showed that both quantitative liver function tests (galactose elimination capacity:P<0.025; aminopyrine breath test:P<0.001; ICG clearance:P<0.005) and common clinical and biochemical data (encephalopathy:P<0.001; ascites:P<0.001; serum bilirubin:P<0.005; serum albumin:P<0.001; prothrombin index:P<0.05) were significant predictors of survival. To investigate whether quantitative liver function tests could contribute to a better definition of the prognosis, once Pugh score had already been taken into account, a multiple regression analysis according to the Cox model was performed. Pugh score and galactose elimination capacity resulted in the only independent prognostic covariates. From them a prognostic index was calculated, and the model was validated in an additional sample of 70 patients investigated according to the same protocol. The contribution GEC gave to the assessment of overall prognosis over that obtained using the Pugh score was slight, as estimated by the statistical parameters of the Cox's model, but was significant as assessed by a ROC curve analysis (P=0.05). These data show that all quantitative liver function tests were predictors of survival in cirrhosis, and that the galactose elimination capacity added some new prognostic information to those already available using the Child-Turcotte-Pugh classification.This study was supported in part by a grant from the Italian Ministry of Education (National Project Liver Cirrhosis). Part of this study was presented at the 22nd Meeting of the European Society for Clinical Investigation, Graz, Austria, April 20–23, 1988.     

Protooncogenes and growth factors associated with normal and abnormal liver growth

Hepatocyte replication during liver regeneration depends on extrinsic (circulating) and intrinsic (intrahepatic) factors. Two important growth factors produced in the regenerating liver are discussed, TGF, an autocrine, stimulatory growth factor, and TGF, a paracrine inhibitory factor. The balance between the activities of these factors is likely to play an important role in regulating hepatocyte proliferation. The experession of some protooncogenes occurs sequentially during the first few hours after partial hepatectomy and is a marker for the entry of hepatocytes into the cell cycle (proliferative competence). As hepatocytes become competent to proliferate, they respond to TGF and other growth factors and enter a proliferative phase. It is possible that TGF1 serves as a stop signal for liver regeneration but the mechanisms by which TGF inhibits hepatocyte DNA synthesis are still unknown.Presented at the Proceedings of the International Meeting on Normal and Neoplastic Growth in Hepatology, Bari, Italy, June 1989.     

Chain length heterogeneity of nucleosomal DNA in mouse liver after dimethylnitrosamine administration

The effect of dimethylnitrosamine on the nucleosomal structure of mouse liver chromatin was studied. After a single oral dose of dimethylnitrosamine (2–75 mg/kg body weight 45 min before sacrifice) liver nuclei were isolated and incubated with micrococcus nuclease. Nucleosomes were separated on sucrose density gradients. There were no differences in nucleosomal sedimentation velocities between preparations from control and dimethylnitrosamine treated animals. The supernatant obtained after centrifugation of the lysed nuclei (2 min at 4,000 g _av) and nucleosomal peak fractions were used for isolation of DNA. DNA was heat denatured in 7 M urea or formamide. After electrophoresis on polyacrylamide gels areas under mononucleosomal DNA and smaller fragments were measured and compared with the total DNA area. The increase in DNA fragmentation was dimethylnitrosamine dose response dependent. When expressed as per cent of controls it amounted to 106% for 2 mg; 115% for 10 mg; 127% for 25 mg; 164% for 75 mg dimethylnitrosamine/kg body weight. A good correlation between mobility and log of chain length of 174 RF DNA-Hae III digest was obtained in nondenaturing 5% polyacrylamide gels and denaturing non-aqueous formamide polyacrylamide gels but not in 12% polyacrylamide gels containing 7 M urea. DNA of mononucleosomal peak fractions contained 200 and that of dinucleosomal peak fractions 400 nucleotides. Fragmentation of DNA was closely related to in vivo dimethylnitrosamine treatment but was not detected in measurements of protein-DNA complexes in the chromatin. It was disclosed on denaturation of DNA followed by polyacrylamide gel electrophoresis.Abbreviations DMN dimethylnitrosamine - SDS sodium dodecyl sulfate The work was supported by Grant Number 1 R0 1 CA26642-01, awarded to A.v.d.D. by the National Cancer Institute, DHEW     

Diazepam metabolism in human foetal and adult liver

Summary Diazepam was metabolized by human foetal liver microsomes to N-desmethyldiazepam and N-methyloxazepam as early as the 13th week of gestation. The metabolic activity was lower than that of microsomes from adult human liver. Diazepam was shown mainly to be hydroxylated to N-methyloxazepam at substrate concentrations higher than 0.1 mM. Diazepam levels above 1.0 mM were inhibitory to the overall metabolic reaction. SKF 525-A inhibited diazepam metabolism by foetal liver microsomes at a concentration of 0.1 mM. The addition of diazepam to foetal and adult human liver microsomes resulted in a type II spectral change. Its inhibition by carbon monoxide indicated that biotransformation of diazepam was performed by the cytochrome P-450-linked mono-oxygenase system.     

The significance of covalent binding of catechols to proteins in vivo

When rats were dosed with 14 g/kg ³H-isoproterenol, ³H-radioactivity was measurable in the liver until 48 h. This amount was not different in livers of animals which have been pretreated with diethyl maleate.After exhaustive extraction, a significant amount of ³H-radioactivity from isoproterenol could be detected in the proteins of total liver (homogenate), of cytosol and of microsomes. In the cytosol fraction of diethyl maleate pretreated animals twice the amount of isoproterenol-radioactivity was found in the extracted proteins compared to controls. In the microsomal fraction there was no difference between diethyl maleate pretreated and control animals in the amount of radioactivity incorporated into proteins.In all fractions the radioactivity measurable in the extracted proteins declined with a half life time of about 24 h.The in vivo results on covalent binding of isoproterenol are compared to the irreversible protein binding of ethinyloestradiol in vivo. Quantitatively, these in vivo data are compared to the results on irreversible protein binding obtained during incubations of isoproterenol or ethinyloestradiol with rat liver microsomes.Presented at the Symposium Influence of Metabolic Activations and Inactivations on Toxic Effects held at the 18th Spring Meeting of the Deutsche Pharmakologische Gesellschaft, Section Toxicology, D-6500 Mainz, March 15, 1977