Criteria for assessment of functional impairment in patients with cirrhosis of the liver

Non-alcoholic steatohepatitis, but not simple steatosis, disturbs the functional homogeneity of the liver - a human galactose positron emission tomography study

BACKGROUND

The disease severity of non-alcoholic fatty liver disease (NAFLD) and the distinction between simple steatosis and non-alcoholic steatohepatitis (NASH) are based on the pathohistological presence of steatosis, inflammation, ballooning and fibrosis. However, little is known about the relation between such structural changes and the function of the afflicted liver.

AIMS

To investigate in vivo effects of hepatic fat fraction, ballooning and fibrosis on regional and whole liver metabolic function assessed by galactose elimination in NASH and simple steatosis.

METHODS

Twenty-five biopsy-proven, nondiabetic patients with NAFLD (13 NASH with low-grade fibrosis, 12 simple steatosis with no fibrosis) underwent 2-[¹⁸ F]fluoro-2-deoxy-d-galactose positron emission tomography and magnetic resonance imaging-derived proton density fat fraction of the liver. Nine healthy persons were included as controls.

RESULTS

In the NASH patients, the standardised hepatic uptake of 2-[¹⁸ F]fluoro-2-deoxy-d-galactose was reduced to 13.5 (95% confidence interval, 12.1-14.9) as compared with both simple steatosis and controls (16.4 (15.6-17.1), P < 0.001). Thus, the NASH patients had reduced regional metabolic liver function. The liver fat fraction diluted the standardised uptake equally in NASH and simple steatosis but the fibrosis and ballooning of NASH were associated with a further decrease. Moreover, the NASH livers exhibited increased variation in their standardised uptake values (coefficient of variation 13.8% vs 11.6% in simple steatosis and 10.2% in controls, P = 0.02), reflecting an increased functional heterogeneity.

CONCLUSIONS

In NASH, the regional metabolic liver function was lower and more heterogeneous than in both simple steatosis and healthy controls. Thus, NASH disturbs the normal homogeneous metabolic function of the liver.

Decreased splanchnic oxygen uptake and increased systemic oxygen uptake in cirrhosis are normalized after liver transplantation

The aim of this study is to (1) characterize the impact of orthotopic liver transplantation (OLT) on splanchnic and systemic oxygen uptake (VO(2)) in patients with liver cirrhosis, and (2) investigate possible influencing factors, as well as metabolic consequences, of reduced splanchnic VO(2) in patients with cirrhosis. Therefore, we measured systemic VO(2) (indirect calorimetry), portal pressure (hepatic venous pressure gradient), hepatic blood flow (HBF; primed continuous infusion of indocyanine green), and hepatic turnover (arteriohepatic venous concentration differences multiplied by HBF) of oxygen, glucose, free fatty acids (FFAs), and aromatic amino acids (AAAs) in 52 patients with advanced cirrhosis and 16 patients with a clinically stable long-term course after OLT. Systemic VO(2) was significantly increased in patients with cirrhosis (261 +/- 7 mL/min) and normalized after OLT (216 +/- 8 mL/min; P < .001). Arterial and hepatic venous oxygen saturation and splanchnic oxygen extraction (in percent) were not different between patients with cirrhosis and after OLT. Splanchnic VO(2) was decreased in patients with cirrhosis (41 +/- 3 mL/min, representing 16% +/- 1% of systemic VO(2)) and normalized after OLT (69 +/- 6 mL/min; P < .001, representing 32% +/- 3% of systemic VO(2); P < .001). In patients with cirrhosis, a decrease in HBF was associated with decreased splanchnic VO(2) (r = 0.74; P < .001). Conversely, decreased splanchnic VO(2) reflected a decrease in hepatic glucose production (r = 0.34; P = .01) and hepatic extraction of FFAs (r = 0.40; P < .01) and AAAs (r = 0.30; P < .05). These results show that (1) splanchnic and systemic VO(2) normalize after OLT, indicating correction of hepatic and extrahepatic metabolic derangements; (2) in cirrhosis, HBF becomes limiting for hepatic oxygen supply; and (3) impaired splanchnic VO(2) reflects a decrease in metabolic liver function.

Myofibroblasts in the cirrhotic rat liver reflect hepatic remodeling and correlate with fibrosis and sinusoidal capillarization

BACKGROUND/AIMS

Myofibroblasts are essential in fibrogenesis during development of cirrhosis. In the present study we stereologically quantitated MFB's and correlated them with fibrosis and sinusoidal capillarization.

METHODS

Male SD rats were rendered cirrhotic by chronic exposure to phenobarbital/CCl4, (CIR; n = 16); untreated littermates served as controls (CTR; n = 10). Sinusoidal capillarization was assessed by a multiple indicator dilution technique as previously described. The volume fractions of myofibroblasts and other liver components were estimated by morphometry.

RESULTS

Myofibroblasts averaged 15.7 +/- SD 0.7% in CIR as compared to 6.7% +/- SD 0.4% in CTR (p < 0.01). An extra-littoral compartment of myofibroblasts was found in portal tracts and within fibrous septa. In CIR, hepatocytes showed a bimodal distribution of volume fractions, and hepatocyte volume distribution disclosed a mirror image of that of myofibroblasts. Connective tissue was markedly increased in CIR, averaging 13.2 +/- 1.2% in CIR vs. 1.2 +/- 0.3% in CTR (p < 0.0001). Extravascular albumin space--a measure of sinusoidal capillarization--was reduced by 44% in CIR (0.028 +/- 0.017 vs. 0.050 +/- 0.010 ml/g; p < 0.001). The volume fraction of myofibroblasts correlated best with extravascular albumin space (r = -0.84, p < 0.001). Multiple regression analysis selected only extravascular albumin space and connective tissue to be determined by the volume fraction of myofibroblasts (r = 0.923; p < 0.001).

CONCLUSION

We conclude that increased myofibroblasts reflect the degree of hepatic remodeling rather than cirrhosis inasmuch as myofibroblast volume fraction inversely reflects that of hepatocyte bimodality. Myofibroblasts form an extra-littoral compartment in this model of CIR and correlate with hepatic fibrosis and sinusoidal capillarization.

Hepatic blood flow and splanchnic oxygen consumption in patients with liver failure. Effect of high-volume plasmapheresis

Liver failure represents a major therapeutic challenge, and yet basic pathophysiological questions about hepatic perfusion and oxygenation in this condition have been poorly investigated. In this study, hepatic blood flow (HBF) and splanchnic oxygen delivery (DO2, sp) and oxygen consumption (VO2,sp) were assessed in patients with liver failure defined as hepatic encephalopathy grade II or more. Measurements were repeated after high-volume plasmapheresis (HVP) with exchange of 8 to 10 L of plasma. HBF was estimated by use of constant infusion of D-sorbitol and calculated according to Fick's principle from peripheral artery and hepatic vein concentrations. In 14 patients with acute liver failure (ALF), HBF (1.78 +/- 0.78 L/min) and VO2,sp (3.9 +/- 0.9 mmol/min) were higher than in 11 patients without liver disease (1.07 +/- 0.19 L/min, P <.01) and (2.3 +/- 0.7 mmol/min, P <.001). In 9 patients with acute on chronic liver disease (AOCLD), HBF (1.96 +/- 1.19 L/min) and VO2,sp (3.9 +/- 2.3 mmol/min) were higher than in 18 patients with stable cirrhosis (1.00 +/- 0.36 L/min, P <.005; and 2.0 +/- 0.6 mmol/min, P <.005). During HVP, HBF increased from 1.67 +/- 0.72 to 2.07 +/- 1.11 L/min (n=11) in ALF, and from 1.89 +/- 1.32 to 2.34 +/- 1.54 L/min (n=7) in AOCLD, P <.05 in both cases. In patients with ALF, cardiac output (thermodilution) was unchanged (6.7 +/- 2.5 vs. 6.6 +/- 2.2 L/min, NS) during HVP. Blood flow was redirected to the liver as the systemic vascular resistance index increased (1,587 +/- 650 vs. 2, 020 +/- 806 Dyne. s. cm-5. m2, P <.01) whereas splanchnic vascular resistance was unchanged. In AOCLD, neither systemic nor splanchnic vascular resistance was affected by HVP, but as cardiac output increased from 9.1 +/- 2.8 to 10.1 +/- 2.9 L/min (P <.01) more blood was directed to the splanchnic region. In all liver failure patients treated with HVP (n=18), DO2,sp increased by 15% (P <.05) whereas VO2,sp was unchanged. Endothelin-1 (ET-1) and ET-3 were determined before and after HVP. Changes of ET-1 were positively correlated with changes in HBF (P <.005) and VO2,sp (P <.05), indicating a role for ET-1 in splanchnic circulation and oxygenation. ET-3 was negatively correlated with systemic vascular resistance index before HVP (P <.05) but changes during HVP did not correlate. Our data suggest that liver failure is associated with increased HBF and VO2, sp. HVP further increased HBF and DO2,sp but VO2,sp was unchanged, indicating that splanchnic hypoxia was not present.

Hepatic plasma flow estimated according to Fick's principle in patients with hepatic encephalopathy: evaluation of indocyanine green and D-sorbitol as test substances

The magnitude of hepatic plasma flow in patients with liver failure and hepatic encephalopathy (HE) is unknown because a reliable flow estimate has not been available. The purpose of this study was to estimate hepatic plasma flow in patients with HE and to evaluate indocyanine green (ICG) and sorbitol as test compounds. Fourteen patients with acute liver failure (ALF) and nine patients with chronic liver failure (CLF), all with HE grade II or more, were studied. After hepatic vein catheterization, hepatic plasma flow was estimated by use of constant infusion, simultaneous arterial and hepatic vein concentration measurements, and calculated according to Fick's principle. The hepatic extraction fraction of D-sorbitol 0.179+/-0.144 (mean+/-SD) was higher than the hepatic extraction fraction of ICG 0.054+/-0.085 (P < .001). The low hepatic extraction fraction of ICG rendered this compound unfit for estimation of hepatic plasma flow in these patients. In contrast, by using D-sorbitol the hepatic plasma flow could be estimated in 21 of 23 patients with a median SD of 8.4% (range, 2.6% to 29%). The D-sorbitol estimated hepatic plasma flow was 1.2+/-0.5 L/min (n = 12) in patients with ALF and 1.4+/-0.9 L/min (n = 9) in patients with CLF. These values are higher than what has been reported in normal subjects and in patients with cirrhosis without HE. An elevated hepatic flow should increase oxygen delivery and may enhance the failing liver's ability to remove substances from the blood. At the same time, hepatic first pass metabolism is reduced. We conclude that an elevated hepatic flow in these patients is of clinical importance.

Alterations in hepatic fructose metabolism in cirrhotic patients demonstrated by dynamic 31phosphorus spectroscopy

Quantitative liver function tests are based on the clearance concept and measure the plasma disappearance of a test compound such as galactose. Metabolism is inferred to be predominantly hepatic, and usually no knowledge is obtained of the true time course of metabolite formation. Dynamic 31phosphorus magnetic resonance spectroscopy after intravenous administration of fructose directly measures hepatic sugar metabolism. To determine the feasibility and the utility of 31P magnetic resonance spectroscopy, we studied the responses of six healthy subjects and nine patients with nonalcoholic cirrhosis to a fructose load. Results were related to the impairment of hepatic function assessed by the galactose-elimination capacity test. Liver spectra were acquired in a 1.5 T whole-body nuclear magnetic resonance unit with a surface coil (9-cm diameter) placed ventrally on the liver; the one-dimensional chemical-shift imaging technique was used to obtain spectra from tissue slices parallel to the surface coil. After a basal spectrum had been obtained, fructose (250 mg/kg) was injected intravenously, and further spectra were collected sequentially every 6 min for 1 hr. Formation of monophosphate esters (9% +/- 5% vs. 20% +/- 8% of total area; p less than 0.01) and utilization of inorganic phosphate (5% +/- 4% vs. 11% +/- 3% of total area; p less than 0.005) were markedly decreased in cirrhotic patients. These measures correlated with the severity of the impairment of liver function measured by the galactose-elimination capacity (r = 0.53 to 0.69; p less than 0.05). We conclude that dynamic 31P magnetic resonance spectroscopy is a safe, clinically feasible test that allows detailed insights into biochemical events in liver disease.

Accurate prediction of death by serial determination of galactose elimination capacity in primary biliary cirrhosis: a comparison with the Mayo model

We retrospectively analyzed the predictive accuracy of serial determinations of galactose elimination capacity in 61 patients with primary biliary cirrhosis. Death was predicted from the time that the regression line describing the decline in galactose elimination capacity vs. time intersected a value of 4 mg.min-1.kg-1. Thirty-one patients exhibited decreasing galactose elimination capacity; in 11 patients it remained stable and in 19 patients only one value was available. Among those patients with decreasing galactose elimination capacity, 10 died and three underwent liver transplantation; prediction of death was accurate to 7 +/- 19 mo. This criterion incorrectly predicted death in two patients with portal-vein thrombosis; otherwise, it did better than or as well as the Mayo clinic score. The latter was also tested on our patients and was found to adequately describe risk in yet another independent population of patients with primary biliary cirrhosis. Cox regression analysis selected only bilirubin and galactose elimination capacity, however, as independent predictors of death. We submit that serial determination of galactose elimination capacity in patients with primary biliary cirrhosis may be a useful adjunct to optimize the timing of liver transplantation and to evaluate new pharmacological treatment modalities of this disease.

Determination of liver volume in vivo in rats using MRI

Accurate estimation of the liver volume may be important for the diagnosis of several pathological processes in patients and for the study of new therapies in experimental oncology. Although sonography and computed tomography (CT) have been used for this purpose in patients, the lack of spatial resolution and tissue differentiation is a source of measurement errors which, at present, makes it impossible to accept sonography and CT widely for the determination of the liver volume. In the present study, the liver volumes of seven rats were measured by magnetic resonance imaging (MRI) and an automated image analysis system before and after the animals were killed. Volume computation was carried out by adding up the individual volumes in the sequential MR sections. Adequate MR images with high contrast between the liver and surrounding structures were obtained with spin echo pulse sequence and retarded phase encoding while no contrast material was used. The mean volumes of the livers measured by MR in vivo and in cadavers were 11.91 +/- 0.40 and 11.92 +/- 0.45 ml, respectively. When compared with the actual liver volumes measured in vitro after resection, the errors of determinations in vivo and in cadavers were as small as 3.1 and 2.1%, respectively. These data indicate that MR imaging is an accurate means to determine the liver volume in vivo and that it may be potentially useful to measure small intrahepatic lesions in patients.

Evaluation of patients with portal hypertension

In order to select the most suitable management of portal hypertension, a full evaluation of the patient is desirable. The aspects studied should include the possible causes of portal hypertension and the disease and function of the liver, as well as the psychosocial aspects of this condition. The usual reason to investigate the presence and causes of portal hypertension is the detection of gastroesophageal varices. The estimated probability of bleeding from the varices and the cause of the varices should be investigated. If cirrhosis is detected, then its cause or mechanism should be clarified and the activity of the process estimated in semiquantitative terms. If therapy is available, it should be initiated. The evaluation of liver function is based on quantitative measurements of hepatocellular metabolic function (such as the galactose elimination capacity or antipyrine clearance), liver volume (weight), liver blood flow, and systemic hemodynamics (cardiac output index).

Superiority of the Child-Pugh classification to quantitative liver function tests for assessing prognosis of liver cirrhosis

To evaluate the prognostic value of quantitative liver function tests in comparison with established prognostic variables, the data of 47 patients with liver cirrhosis were analysed. A total of 16 variables, comprising the galactose elimination capacity and the indocyanine green clearance, the Child-Pugh classification, and several clinical and biochemical variables were subjected to Kaplan-Meier life-table analysis and Cox proportional hazards regression analysis. As independent variables, poor prognosis was associated significantly with increasing Child-Pugh score (p less than 0.00001), whereas the galactose elimination capacity (p = 0.03) and the indocyanine green clearance (p less than 0.001) were less sensitive indicators. The regression analysis showed prognostic value in decreasing sequence for Child-Pugh classification, age, sex, history of upper GI haemorrhage, and alkaline phosphatase activity. The quantitative liver function tests evaluated in the present work have less prognostic value than routinely accessible variables.

Correlation of caffeine elimination and Child's classification in liver cirrhosis

Apparent pharmacokinetic parameters of caffeine elimination from the circulation were determined in 27 patients with histologically confirmed liver cirrhosis, 8 patients with miscellaneous liver disease, and 8 patients with other than liver disease. The usefullness of this quantitative test to assess the severity of liver cirrhosis was compared to the Child-Turcotte or Child-Pugh classification score as well as to the galactose elimination capacity of these patients. Using reversed-phase high pressure liquid chromatography caffeine, paraxanthine, theophylline, and theobromine were analysed in blood plasma collected before and after an oral dose of caffeine. Compared to apparent caffeine pharmacokinetics in patients with normal livers or miscellaneous liver disease, cirrhosis was characterized by a statistically significant reduction in apparent caffeine clearance and prolongation in half-life. The reduced apparent plasma disappearance rate of caffeine in cirrhotics was related to the retarded formation of paraxanthine which was the main metabolite of caffeine in blood plasma both in the absence or presence of liver disease. The apparent caffeine clearance in cirrhosis decreased with increasing Child-Turcotte classification score: Child's class A patients differed significantly from Child's class B or Child's class C patients, whereas the difference between Child's class B and C patients did not reach statistical significance (Wilcoxon's rank test). In addition there was a strong correlation between the Child-Pugh classification score and apparent caffeine clearance (P less than 0.001). However, no correlation existed between Child's classification and galactose elimination capacity. Our data emphasize the value of the Child-Turcotte or Child-Pugh classification in assessing the severity of liver cirrhosis in a simpler and less time-consuming way than using quantitative liver function tests.

Determinants of hepatic function in liver cirrhosis in the rat. Multivariate analysis

We investigated the determinants of hepatic clearance functions in a rat model of liver cirrhosis induced by phenobarbital/CCl4. Aminopyrine N-demethylation (ABT), galactose elimination (GBT), and serum bile acids (SBA) were determined in vivo. The livers were then characterized hemodynamically: intrahepatic shunting (IHS) was determined by microspheres and sinusoidal capillarization by measuring the extravascular albumin space (EVA) by a multiple indicator dilution technique. The intrinsic clearance was determined by assaying the activity of the rate-limiting enzymes in vitro. Hepatocellular volume (HCV) was measured by morphometry. ABT and SBA, but not GBT, differentiated cirrhotic from normal liver. IHS ranged from normal to 10%; all cirrhotic livers showed evidence of sinusoidal capillarization (reduced EVA). The cirrhotic livers showed a bimodal distribution of HCV, HCV being decreased in 50% of the cirrhotic livers. Multivariate analysis showed EVA and portal flow to be the main determinants of microsomal (ABT) and cytosolic (GBT) clearance function; SBA, by contrast, were determined solely by IHS. We conclude that sinusoidal capillarization is the main determinant of hepatic clearance, while serum bile acids reflect intrahepatic shunting. These findings emphasize the importance of alterations of hepatic nutritional flow to explain reduced clearance function in cirrhosis of the liver.

Age-related changes in liver size and hepatic blood flow. The influence on drug metabolism in the elderly

The propensity of elderly people to suffer from dose-dependent adverse drug reactions is well known. This may be largely related to reduced drug clearance. Changes in liver size and liver blood flow are probably the main reason for this decline in drug elimination with age. This review focuses on methods of measuring liver size and blood flow, on changes which have been reported in the elderly and on the clinical implications of these changes.

Steady-state extrarenal sorbitol clearance as a measure of hepatic plasma flow

Hepatic plasma flow was assessed with sorbitol (hepatic extraction = 0.96) at steady state. After infusion of 50 mg/min for 3 h, total and renal sorbitol clearances were calculated, and the extrarenal clearance was obtained by taking the difference between the two. In normal volunteers, the mean (+/- SD) extrarenal sorbitol clearance was 10.6 +/- 2.1 ml/min.kg. In patients with various liver diseases, it was correlated more closely to the fractional clearance of indocyanine green (r = 0.83, n = 57) than the galactose elimination capacity (r = 0.66, n = 55). Hepatic vein catheterization showed that the hepatic extraction of sorbitol was always much higher than the extraction of indocyanine green; there was no evidence for extrahepatic, extrarenal sorbitol elimination. On the basis of these findings, sorbitol is kinetically superior to indocyanine green and, although the noninvasively determined extrarenal sorbitol clearance at steady state may not be equal to total hepatic plasma flow, it may at least be regarded as a measure of parenchymal liver plasma flow.

Aminopyrine N-demethylation by rats with liver cirrhosis. Evidence for the intact cell hypothesis. A morphometric-functional study

The intact cell hypothesis states that a reduced number of intrinsically normal hepatocytes, together with hemodynamic alterations, explains decreased drug metabolism in cirrhosis. We explored this hypothesis by comparing results of the aminopyrine breath test with in vitro measurements of aminopyrine N-demethylation and morphometrically determined liver cell volume in a rat model of cirrhosis. Aminopyrine N-demethylation in vivo (ABT-k) was 0.98 +/- 0.10/h (mean +/- SD) in controls. The cirrhotic rats were separated into those with normal (NCR) and those with abnormal ABT-k (PCR). Microsomal aminopyrine N-demethylase averaged 2.08 +/- 0.77 and 2.09 +/- 0.54 mumol/min in controls and NCRs, respectively; it was reduced to 1.00 +/- 0.81 mumol/min (p less than 0.02) in PCRs. Morphometrically determined hepatocellular volume was 18.8 +/- 2.8, 17.1 +/- 1.9, and 11.6 +/- 6.1 ml in controls, NCRs, and PCRs, respectively, PCRs being lower than controls (p less than 0.01) and NCRs (p less than 0.05). When N-demethylase and cytochrome P450 were related to hepatocellular volume (in milliliters), no significant difference between the three groups was apparent. We conclude that reduced aminopyrine N-demethylation in progressed cirrhosis is mainly due to a loss of liver cell volume. The function per liver cell volume remains constant, however, thus favoring the intact cell hypothesis for the handling of slowly metabolized compounds such as aminopyrine.

The evolution of changes in quantitative liver function tests in a rat model of biliary cirrhosis: correlation with morphometric measurement of hepatocyte mass

The aim of this study was to determine the prognostic significance of functional changes in the liver during progression of cirrhosis. Liver function was quantitated weekly by the aminopyrine breath test (measuring microsomal function) and the galactose breath test (measuring cytosolic function) in rats made cirrhotic by bile duct ligation (n = 14) and in sham-surgery controls (n = 9). Nine rats died spontaneously of cirrhosis. Both the aminopyrine breath test and galactose breath test were sensitive (89%) predictors of death within 1 week, but the galactose breath test was more specific (83%). Morphometric measurements of livers from surviving cirrhotic animals and controls (n = 5 each) showed that mean hepatocyte mass was maintained in the cirrhotic livers [cirrhosis (17.0 +/- 2.0) vs. controls (13.9 +/- 0.9 gm)]. The galactose breath test was also maintained, whereas the aminopyrine breath test was significantly decreased in the surviving cirrhotics. The galactose breath test, but not the aminopyrine breath test, correlated with hepatocyte mass (r = 0.67). The aminopyrine breath test correlated with microsomal aminopyrine N-demethylase activity (r = 0.78). Serial use of quantitative liver tests allows prediction of time of death from cirrhosis in this model.

Estimated hepatic oxygen consumption in patients with chronic liver diseases as assessed by organ reflectance spectrophotometry

We investigated the estimated hepatic oxygen consumption by reflectance spectrophotometry during peritoneoscopy and the rate of in vitro oxygen consumption of liver slices obtained by liver biopsy using the oxygen electrode apparatus in patients with chronic liver diseases. The estimated hepatic oxygen consumption decreased concomitantly with the decrease in blood supply, expressed as the regional hepatic blood hemoglobin concentration, and it was significantly decreased in cirrhosis compared to chronic hepatitis. The estimated hepatic oxygen consumption also was significantly correlated with the serum albumin level, 15-min retention rate of indocyanine green, and prothrombin time. There was no correlation between the estimated hepatic oxygen consumption calculated from the reflectance spectra and the rate of in vitro oxygen consumption measured by the oxygen electrode apparatus. Most cirrhotic liver slices had a respiratory rate comparable to that in chronic hepatitis. Thus, it is concluded that the reduction of estimated hepatic oxygen consumption in cirrhosis of the liver is mainly due to the reduction of oxygen supply secondary to the decrease of hepatic blood flow.

Hepatic hemodynamics and oxygen consumption in alcoholic fatty liver assessed by organ-reflectance spectrophotometry and the hydrogen clearance method

Hepatic blood flow and estimated hepatic oxygen consumption were studied in rats treated chronically with ethanol by organ-reflectance spectrophotometry and the hydrogen clearance method. In the withdrawal state from ethanol, the concentration of hemoglobin in the hepatic tissue (delta Er569-650), the estimated hepatic oxygen consumption (estimated VO2) and the regional liver blood flow decreased significantly in rats treated chronically with ethanol in comparison with their controls. On the other hand, there was no significant difference in the estimated oxygen saturation of the hepatic blood hemoglobin (estimated SO2) between both groups. That is, an increase in oxygen extraction, which was exhibited by a decrease in the estimated SO2, did not occur in rats treated chronically with ethanol in spite of a decrease in blood supply. Thus, in the withdrawal state from ethanol, both oxygen delivery to the liver and oxygen utilization in the liver were disturbed at the stage of alcoholic fatty liver.

Mesocaval and distal splenorenal shunts: effect on hepatic function, hepatic hemodynamics, and portal systemic encephalopathy

The effect of the mesocaval interposition shunt (n = 12) and the distal splenorenal shunt (n = 9) on the wedged hepatic venous pressure, the estimated hepatic blood flow, quantitative hepatic function, and the rate of portal systemic encephalopathy was evaluated in 21 patients who had bled from esophageal varices. After mesocaval shunt the wedged hepatic venous pressure was significantly reduced by 42% (from 26 +/- 3 mm Hg to 15 +/- 5 mm Hg, P less than 0.001) compared to 16% only (from 25 +/- 3 mm Hg to 21 +/- 2 mm Hg, P less than 0.005) after distal splenorenal shunt. The estimated hepatic blood flow also decreased significantly after mesocaval shunt by 61% (from 1.45 +/- 0.46 l/min to 0.56 +/- 0.25 l/min, P less than 0.001) compared to 29% (from 1.29 +/- 0.32 l/min to 0.91 +/- 0.39 l/min, P less than 0.05) after distal splenorenal shunt. Despite significantly different influences of both types of shunt operations on wedged hepatic venous pressure and estimated hepatic blood flow (P less than 0.001), postoperative changes of hepatic function were comparable in both groups of patients. The galactose elimination capacity, the initial plasma disappearance rate of Bromsulphalein, and the plasma ratio of valine, leucine, and isoleucine to phenylalanine and tyrosine were reduced by 13%, 26%, and 29%, respectively, after mesocaval shunt, compared to 12%, 25%, and 17% after distal splenorenal shunt. Only two patients of the mesocaval shunt group with the largest decrease in estimated hepatic blood flow developed portal systemic encephalopathy postoperatively, and the distal splenorenal shunt patients with their minor hemodynamic sequelae remained free of portal systemic encephalopathy.

Effect of cimetidine on the hepatic extraction of indocyanine green, the portal pressure and the systemic circulation in patients with cirrhosis of the liver

The effect of cimetidine on hepatic and systemic haemodynamic parameters was studied in seven patients with portal hypertension due to alcohol-induced cirrhosis of the liver and in one patient with peliosis hepatis following oral contraceptive steroids. The intravenous administration of cimetidine (350 mg as bolus, followed by 2 mg/min over 60 min) reduced the hepatic extraction of continuously infused indocyanine green (ICG) by 27%; this was statistically significant (P less than 0.01). Since the ICG clearance, calculated independently of hepatic perfusion, was lowered by 19%, this effect seems to be mainly due to a reduced capacity of the liver to remove the dye from the blood, rather than due to changes in perfusion. Cimetidine did not influence the elevated portal pressure in the patients with cirrhosis, or the normal pressure in the patient with peliosis hepatis. No significant effect was observed on heart rate, mean arterial pressure, pulmonary artery pressure, pulmonary capillary pressure and cardiac output. These studies indicate that the reduction of the hepatic ICG extraction following cimetidine is more the result of an inhibited capacity of the liver to remove the dye than of changes in the hepatic perfusion or in the systemic circulation.

A morphometric analysis of the hypertrophy of experimental liver cirrhosis

The objective of this study was to better elucidate the composition of the hypertrophic cirrhotic liver. We induced cirrhosis with hypertrophy in rats by simultaneous treatment with CCl4 and phenobarbital (PB) and devised a hierarchy of structure applicable to the sampling and morphometric analysis of untreated and PB-treated control livers and of cirrhotic livers. Our analysis demonstrated that the hepatomegaly attributable to cirrhosis is virtually the total result of an increase in the specific volume (ml/100 g body weight) of the non-parenchyma, most of which is connective tissue and vascular lumen volume. Inconsequential to the hepatomegaly but statistically significant were the volumetric increases found in the following parenchymal compartments: hepatocyte nucleus, Kupffer/endothelial cell nucleus, Ito cell nucleus and cytoplasm, and bile canaliculus. The change in the hepatocyte nucleus is the result of an increase in size rather than in number. Sinusoidal space is the only compartment that showed a significant decrease. This study shows the practicality and usefulness of applying morphometric methods to cirrhotic liver.

Plasma concentrations of mebendazole during treatment of echinococcosis: preliminary results

High oral doses of mebendazole are used experimentally for the treatment of human alveolar and cystic echinococcosis. In order to assess bioavailability of this drug 1.5 g doses were given to 3 volunteers. Measurable plasma concentrations of 17 to 134 nmol/l were found only if mebendazole was given together with a fatty meal. In a patient with cholestasis plasma concentrations were higher than in the 3 normal subjects. In patients on long term treatment the increase in plasma concentration after administration of a 1 g dose varied between 0 and 500 nmol/l. It is concluded that systemic availability of mebendazole is enhanced by concomitant food intake. In view of the large intra- and interindividual variation in plasma concentration, monitoring plasma levels during long term therapy appears advisable.

Liver function in physically trained subjects: galactose elimination capacity, plasma disappearance of indocyanine green, and aminopyrine metabolism in long-distance runners

Physical exercise and physical training are known to affect several aspects of hepatic metabolism. To assess whether adaptation to long-lasting exercise modifies microsomal drug metabolism, 8 long-distance runners were compared with a group of medical students having significantly lower maximal rates of oxygen consumption. At rest the hepatic galactose elimination capacity and the indocyanine green plasma disappearance rate used as reference methods were the same in both groups. The plasma clearance of ([14C]dimethylamine) aminopyrine and the kinetics of 14CO2 in breath did not differ either. It is concluded that adaptation to long-lasting exercise can occur without evidence for changes in hepatic galactokinase activity, liver blood flow, or microsomal metabolism of aminopyrine.

Liver size and indices of drug metabolism in alcoholics

The role of liver size in drug metabolism was investigated in 34 chronic alcoholics and 28 controls by comparing antipyrine half-life with biopsy content and total amount of hepatic cytochrome P-450 (P-450) and liver weight. Liver size was significantly greater in alcoholics than in controls. Total P-450 was increased and antipyrine metabolism was enhanced in alcoholics with normal histology of the liver. In subjects with alcoholic hepatitis or cirrhosis, the antipyrine half-life was prolonged and P-450 was decreased. Alcoholics with fatty liver had a reduced P-450 content, but the total amount of P-450 and the antipyrine half-life were normal. The results demonstrate in alcoholics that an enlarged liver of normal histological appearance is associated with enhanced drug metabolism. In subjects with fatty liver the drug metabolizing capacity per unit weight of liver is often impaired, but the increase in liver size leads to undisturbed total oxidizing capacity and normal in vivo metabolism. In alcoholic hepatitis drug metabolism is impaired in spite of hepatomegaly. In cirrhosis the enlargement of the liver appears to compensate for the decreased P-450 content resulting in only slightly decreased total P-450, and the severly impaired in vivo drug metabolism may be due to derangement of blood flow.