On the pathogenesis of portal hypertension in cirrhosis of the liver

To investigate the localization of increased vascular resistance in the cirrhotic liver, blood pressures at key points in hepatic vascular pathways were measured in the cirrhotic rat produced by carbon tetrachloride injections. Blood pressures in the portal vein, the terminal portal venule, the terminal hepatic venule and the inferior vena cava were 110, 68, 28 and 20 mm H2O respectively in normal rats, and 211, 112, 34 and 24 mm H2O respectively in rats with liver cirrhosis. These values suggested that the increased vascular resistance in the cirrhotic liver was in the intrahepatic portal vein and the sinusoids, and not in the intrahepatic hepatic vein, although marked distortion of the intrahepatic hepatic vein branches was found in the cirrhotic liver. The increase in sinusoidal vascular resistance was associated with sinusoidal stenoses and a decrease in the sinusoidal space due to the hepatic cell swelling, and that in the intrahepatic portal vein might result from distortion of the peripheral branches of the vein.

On the pathogenesis of hepatic dysfunction and necrosis following acute circulatory failure

To clarify whether diminished hepatic blood flow and portal endotoxaemia interact in the pathogenesis of hepatic dysfunction secondary to acute circulatory failure, such as shock, prolonged hypotension, or left-sided heart failure, the present study was undertaken in rats. Reduced hepatic perfusion, which was produced by partial obstruction of the portal vein, caused elevation of serum transaminase activities and electron microscopic abnormalities of hepatocytic structure, namely, disruption of plasma membrane, swelling of mitochondria, vesiculation and disruption of endoplasmic reticulum, etc. Portal endotoxaemia, which was induced by infusion of endotoxin into the portal vein, led to a rise of serum transaminase activities and random, focal coagulative hepatocellular necrosis. In contrast, massive hepatic necrosis and excessive elevation of serum transaminase activities, which are similar to those seen in patients with shock, etc., were produced when portal endotoxaemia was superimposed upon poor hepatic perfusion. These experimental results suggest that acute hepatic failure and massive hepatic necrosis secondary to acute circulatory failure may be induced by the coexistence of reduced hepatic blood flow and portal endotoxaemia.

Pancreatic venous stasis and endotoxaemia as aetiologic factors in acute haemorrhagic pancreatitis

The present study was undertaken to assess the possible significance of endotoxaemia and venous stasis of the pancreas in the pathogenesis of acute haemorrhagic pancreatitis. Complete obstruction of the venous drainage of the pancreas in rats induced acute haemorrhagic pancreatic necrosis. Partial venous obstruction caused only oedema and haemorrhage in the interstitium. Systemic endotoxaemia produced slight superficial pancreatic necrosis and fat necrosis, but not oedema or haemorrhage. The administration of endotoxin to the rats with partial obstruction of pancreatic venous outflow caused severe haemorrhagic pancreatic necrosis and a large number of fibrin thrombi in the capillaries and venules in and around the necrotic areas, although the severity of the lesions was less severe when compared with those induced by complete obstruction of pancreatic venous drainage. These findings suggest that acute haemorrhagic pancreatitis can be induced by the coexistence of endotoxaemia and partial venous obstruction of the pancreas. The mechanism may be that the endotoxin-induced capillary and venous fibrin thrombi superimposed upon the venous stasis lead to obstruction of venous drainage of the pancreas severe enough to produce haemorrhagic pancreatic necrosis.

Enhanced hepatotoxicity of endotoxin by hypoxia

Pathogenesis of hepatic injury often seen in patients with congestive heart failure is obscure, but hepatic hypoxia and endotoxaemia resulting from congestive heart failure may relate to it. The present study was undertaken in rats to ascertain whether hepatic hypoxia potentiates endotoxin-induced hepatotoxicity. Hypoxic condition of hepatocytes ws induced by exposure to 7% oxygen for 3 hours or administration of ethanol. When endotoxin was given immediately before or several hours after hypoxia, elevation of activities of serum transaminases and focal random hepatocellular necrosis in the lobules were induced, although these functional and morphological changes were not observed in rats with hypoxia or endotoxaemia alone. This finding indicates that hepatic hypoxia leads to a potentiation of sensitivity to endotoxin hepatotoxicity which persists for several hours after recovery from hypoxia. Moreover, these experimental data suggest that hepatic injury in patients with congestive heart failure may be caused by enhancement of endotoxin hepatotoxicity by hepatic hypoxia.

Sinusoidal circulatory disturbance by microthrombosis as a cause of endotoxin-induced hepatic injury

The present study was undertaken in rats to examine the significance of sinusoidal circulatory disturbance by microthrombosis in the pathogenesis of hepatic damage and dysfunction due to endotoxin. Administration of endotoxin induced fibrin deposits and infiltration of polymorphonuclear leukocytes in the sinusoids, focal random coagulative hepatocellular necrosis and elevation of serum transaminase activities. When heparin was given simultaneously with endotoxin, the formation of fibrin thrombus in the sinusoids was prevented, and the endotoxin-induced morphological and functional changes in the liver were markedly inhibited. Infusion of thrombin into the portal vein induced a large amount of fibrin thrombi in the sinusoids, focal random necrotic foci resembling the lesions produced by endotoxin and elevation of levels of serum transaminases. These experimental data suggest that disturbance of hepatic microcirculation by sinusoidal thrombosis is the necessary and sufficient condition for the development of endotoxin-induced hepatic injury.

The role of hepatic venous congestion and endotoxaemia in the production of fulminant hepatic failure secondary to congestive heart failure

The present study was undertaken to clarify the role of congestion of the liver and endotoxemia in the production of fulminant hepatic failure secondary to congestive heart failure. Induction of congestion of the liver, i.e. an elevation of hepatic venous pressure, in rats was accomplished by partial obstruction of the inferior vena cava. A close relationship was demonstrated between venous pressure and serum levels of transaminases as a measure of hepatic dysfunction. Hepatic dysfunction was mild in rats with venous hypertension alone, and only centrilobular congestion was seen on microscopy. In contrast, severe abnormalities of hepatic function were induced by venous hypertension and endotoxaemia. Histologically, the liver revealed bridging centrilobular necrosis as seen in patients with congestive heart failure who develop fulminant hepatic failure. These data suggest that coexistence of endotoxaemia and congestion of the liver may induce fulminant hepatic failure, and that the latter alone is associated only with slight hepatic dysfunction and liver damage.

Potentiation of carbon tetrachloride hepatotoxicity by hypoxia

To determine the cause of hepatic injury in patients with hypoxaemia, the persistence of liver susceptibility to toxic injury after hypoxia was investigated in rats. Centrilobular necrosis and marked elevation of serum glutamic-pyruvic transaminase (SGPT) and serum glutamic-oxaloacetic transaminase (SGOT) activities were induced by carbon tetrachloride (0.1 ml/kg body weight) given in the period between 3 h before and 21 h after exposure to 7% oxygen for 3 h. This observation, that a short period of hypoxia results in a prolonged sensitivity to carbon tetrachloride-induced liver injury, has not been described previously. The mechanism of the phenomenon is obscure. These observations suggest that the hepatic injury in patients with hypoxaemia may be caused not only by the hypoxia per se or chemicals administered before or during hypoxia, but also by chemicals given within 24 h of hypoxaemia.

An experimental study into the cause of acute haemorrhagic gastritis in cirrhosis

To clarify the role of endotoxaemia and congestion of the stomach in the development of acute haemorrhagic gastritis in cirrhotic patients and to investigate the mechanisms of gastric mucosal haemorrhage, the present study was undertaken using rats. Congestion of the stomach was produced by the ligation of gastric veins. Congestion of the stomach or endotoxaemia could not produce gastric mucosal haemorrhage by itself. However, petechial haemorrhage was induced when endotoxin was given to the rats with congestion of the stomach, and the gastric mucosal haemorrhage was largely prevented by administration of gabexate mesilate, an anti-kallikrein drug. Administration of bromelain, which releases prekallikrein and high molecular weight kininogen, instead of endotoxin, also induced gastric mucosal haemorrhage. These findings suggest that the cause of acute haemorrhagic gastritis may be the coexistence of endotoxaemia and congestion of the stomach due to liver cirrhosis and portal hypertension. The mechanisms of the haemorrhage may be as follows: Endotoxin-induced bradykinin acts on the dilated capillaries and small veins in the mucosa and markedly increases their permeability.

An experimental study on the pathogenesis of acute haemorrhagic enteropathy--significance of congestion and endotoxaemia

To clarify the pathogenesis of acute haemorrhagic enteropathy, the present study was undertaken using the ileum of rats. The ligation of marginal veins of the ileum or the injection of endotoxin to the intact rats induced only slight mucosal haemorrhage. On the other hand, the injection of endotoxin into rats with ligation of the marginal veins led to severe mucosal haemorrhage. The severe mucosal haemorrhage was markedly inhibited by suppression of the production of bradykinin. These experimental results suggest that some cases of acute haemorrhagic enteropathy may be induced by the co-existence of endotoxaemia and congestion of the intestine. Thus, the mechanism of severe mucosal haemorrhage may be as follows: bradykinin, induced by endotoxin, acts to dilate capillaries and small veins in the mucosa and markedly increases their permeability.

Localization of increased hepatic vascular resistance in liver cirrhosis

To determine the localization of increased vascular resistance in cirrhotic liver, blood pressures were measured by a direct cannulation method at several key points in the hepatic vascular pathway in normal and cirrhotic rats. Cirrhosis was produced by feeding a choline-deficient diet. Blood pressures in normal rats were 110 mm H2O in the portal vein, 68 mm H2O in the terminal portal venule, 28 mm H2O in the terminal hepatic venule and 20 mm H2O in the inferior vena cava. In cirrhotic rats, blood pressures in the portal vein and the terminal portal venule were 173 and 100 mm H2O, respectively, while those in the terminal hepatic venule and the inferior vena cava were elevated only slightly above normal. These hemodynamic data suggest that an increase in vascular resistance in cirrhotic liver is present in the intrahepatic portal vein and sinusoids, but not in intrahepatic hepatic vein. In cirrhotic liver, stenosis and distortion were found in peripheral branches of the portal vein, and sinusoidal stenoses and a decrease in sinusoidal space were recognized. Accordingly, it is suggested that the increase in vascular resistance in the intrahepatic portal vein and sinusoids correlate with these structural changes. Although severe stenoses and distortion were found in hepatic vein branches, it was thought that they do not contribute to portal hypertension because of lack of increase in vascular resistance in the intrahepatic hepatic vein.

The morphogenesis of the vacuolation of liver cells

The morphogenesis of the vacuolation of liver cells caused by congestion was studied in the rat. Congestion of the liver was produced by constriction of the inferior vena cava just below the diaphragm. Vacuoles appeared within 5 min after the constriction (inferior vena cava pressure: 50 mm H2O or more). Vacuolation began as a small and saccular invagination of the sinusoidal surface of the liver cell membrane, and at the initial stage the vacuolar lumen connected with the space of Disse through a narrow slit. The small vacuoles increased in size and became larger by fusing with each other. The limiting membrane of vacuoles showed identical enzymological activities to those in the liver cell membrane. Vacuoles contained some components of blood and horseradish peroxidase injected into the femoral vein. These findings suggest that vacuolation of liver cells is formed by invaginations of liver cell membrane.

The protective effect of polyriboinosinic acid-polyribocytidylic acid against the occurrence of galactosamine-induced liver cell injury in rat

A marked increase of serum transaminase activities, histological changes of livers similar to those seen in viral hepatitis in man, and inhibition of hepatic protein synthesis were observed in rats following a single injection of D-galactosamine-HCl. These galactosamine-induced phenomena were prevented by the pretreatment of polyriboinosinic acid-polyribocytidylic acid 24 h before the galactosamine administration.

Creutzfeldt-Jakob disease with demonstration of virus-like particles

Two kinds of virus-like particles, doughnut-shaped particles and particles with dense core, were discovered in a brain tissue from a patient with Creutzfeldt-Jakob disease. The two types of virus-like particles are similar to immature type C and type C particles. although no direct relationship between Creutzfeldt-Jakob disease and these virus-like particles can be established, these facts may suggest that viruses play some role in the pathogenesis of Creutzfeldt-Jakob disease.

Electroncytochemical and biochemical demonstration of guanylate cyclase activity in the pancreatic islet

With a cytochemical method using guanylyl imidodiphosphate as a substrate, the guanylate cyclase activity was localized on the plasma membrane of A, B and D cells of islets of Langerhans isolated from the rat. Adequate control experiments were performed by a double-blind method. Parallel biochemical assay showed that guanylate cyclase activity was not completely lost after fixation with 1% glutaraldehyde and incubation with 4 mM lead nitrate. Furthermore, the depressed activity was still stimulatable with acetylcholine.

Sipple's syndrome with peculiar changes in pancreatic islets--an autopsy case

A diagnosis of the heritable disorder Sipple's syndrome was made in a Japanese male aged 28 years. The coexistence of bilateral phenochromocytomas, bilateral medullary thyroid carcinomas and secondary hyperplasia of parathyroid was confirmed at the time of autopsy. Pancreatic islets were hyperplastic with marked proliferation of A and D cells. Transition of the ductal cell to the islet, i.e. "nesidioblatosis" was observed. There was no proliferation of B cells, but a retention of B cell granules, a manifestation of suppressed secretion of insulin attributed to the overproduction of catecholamines was evident. In the stomach, numerous petechial hemorrhages and proliferation of gastrin cells were found. The pathogenesis of changes in the pancreatic islets and stomach is discussed from the viewpoint of hormonal disorders induced by pheochromocytoma and medullary thyroid carcinoma such as are found in Sipple's syndrome.