Portal Branch Ligation Research Articles

Elevated mitochondrial gene expression during rat liver regeneration after portal vein ligation

We explored the molecular basis of mitochondrial energy production during rat liver regeneration after portal vein ligation. Ligation of the left branch of the portal vein induces an increase in the weight of the nonligated lobe, counterbalancing the reduced weight of the ligated lobe. Using this model, we investigated changes in mitochondrial DNA-binding proteins, mitochondrial DNA, and mitochondrial messenger RNA (mRNA) in rat hepatocytes of the nonligated lobes. The amount of mitochondrial DNA-binding protein increased maximally (200% to 300% of the preoperative level) at 12 hours after the operation, before an increase (390%) in mitochondrial DNA content at 24 hours, and parallel to an increase (240%) in mitochondrial mRNA levels at 12 hours. These results suggest that the energy supply for liver regeneration is achieved through enhancement of mitochondrial DNA replication as well as transcription, in which the mitochondrial DNA-binding proteins probably play regulatory roles. We also found that in the nonligated lobes, mRNA levels of hepatocyte growth factor increased to a detectable level only 12 hours after the operation. These molecular biochemical data help explain why preoperative portal vein embolization, which is a modification of portal vein branch ligation, is an effective method to prevent posthepatectomy liver failure.

Compensatory hepatic hypertrophy after occlusion of branches of the portal vein or bile duct

The effect on the liver of portal or bile duct branch occlusion was examined in rabbits by measuring hepatic tissue blood flow and cellular kinetics, using the bromodeoxyuridine labeling index. The portal branch bile duct branch, or both, to the main lobe and caudate lobe (80.4% of total liver weight) were ligated or embolized just above the right posterior lobe (19.6%), resulting in compensatory hypertrophy of the right posterior lobe and atrophy of the main and caudate lobes. Twenty-four days after ligation, the degree of compensatory hypertrophy in the different groups was comparable. There were significant differences in the pattern of the development of hypertrophy. Ligation of both a portal branch and the corresponding bile duct resulted in more rapid hypertrophy and atrophy than ligation of a portal branch alone. Ligation of a branch of the bile duct resulted in slow development of hypertrophy and atrophy. In the embolization group, the increase in the right posterior lobe stopped 6 days after the operation, resulting that it was about 40% thereafter. Histological findings showed that the fibrin clot had contracted and was floating in the portal branch to the main lobe. These results suggested that portal blood flow to the main lobe had resumed and was gradually increasing as the clot contracted. Portal branch ligation gave results superior to those with portal branch embolization with regard to application to preoperative procedure in extended hepatobiliary surgery.

The ultrastructure, kinetics and intralobular distribution of apoptotic hepatocytes after portal branch ligation with special reference to their relationship to necrotic hepatocytes.

Apoptosis was originally defined as shrinkage necrosis, as a distinct mode of cellular death from coagulative necrosis in the rat liver lobes after portal branch ligation. To reveal the functional role of the apoptosis of hepatocytes in the volume reduction and recovery of normal hepatic architecture in portal-deprived liver lobes, we ligated the portal vein branch supplying the left and median liver lobes in Wistar rats. The liver lobes were perfusion-fixed with glutaraldehyde solution via the proximal site of the ligated portion of the portal vein on Days 1, 2, 4, 7 and 14 after operation and examined light and electron microscopically. On Day 2 after ligation, massive necrosis of hepatocytes occurred in the central to intermediate zones of the liver lobule, and apoptotic hepatocytes were observed in the boundary region between necrotic and normal areas. Such necrotic area-associated apoptosis of hepatocytes was most frequent on Day 2, declining thereafter. The sequential changes of the cell organelles in apoptotic hepatocytes were distinct from those in necrotic hepatocytes. On Day 7, when necrotic areas had almost disappeared the apoptosis of hepatocytes occurred mostly between intact hepatocytes in the "combined hepatic cell cords" which included no obvious sinusoidal lumen between hepatic cell cords. Such necrotic area-nonassociated apoptosis began to increase in frequency on Day 4, reached a peak on Day 7 and was gone by Day 14, when normal hepatic architecture was recovered. The present study suggests that both necrotic area-associated and non-associated apoptosis of hepatocytes may be induced by mild ischemia and contribute in part to the volume reduction of ligated liver lobes. It further reveals that the necrotic area-non-associated apoptosis of hepatocytes plays a role in reconstructing the architecture of hepatic cell cords after necrotic hepatocytes have undergone dissolution in the liver lobule.

The effect of ligation of portal branch on the growth of implanted tumor of the liver in rats.

Small masses of Walker 2 56 carcinosarcoma were implanted into the liver lobe of wistar rats. And at same time, a branch of the portal vein of the involved liver lobe was ligated. After 18 days, the growth of implanted tumor in ligation group was much slower than that in control group, namely, the diameter and wet weight of implanted tumor in ligation group were much smaller and lighter than those in control group. Furthermore, there were no ascites and lung metastases in ligation group. These results suggested that simple ligation of portal branch could apparently inhibit the growth and development of implanted tumor in the liver.

Influence of portal branch ligation on the outcome of repeat dearterializations of an experimental liver tumor in the rat.

It has been suggested that the portal vein should be occluded during intermittent hepatic dearterialization in order to induce a more complete ischemia of the tumor. In this experiment the influence of portal branch ligation in combination with repeat dearterializations on a liver tumor was investigated. Twenty-seven rats were randomly allocated to sham treatment (n = 6); portal branch ligation (PBL) (n = 7); 120 min of repeat dearterialization (n = 7); and portal branch ligation (PBL) in combination with 50 min of repeat dearterialization (n = 7) (once a day during 5 days). The results showed that portal branch ligation alone did not alter the tumor growth compared with sham treatment (P > 0.05), nor did portal branch ligation in combination with repeat dearterializations for 50 min (P > 0.05). However, tumor growth delay was achieved following 120 min of repeat dearterializations without occlusion of the portal branch (P < 0.01 versus all the other groups). There was a significant weight loss of the lobe undergoing PBL, whether dearterialization was added or not (P < 0.001). The liver nucleotide/DNA and RNA/DNA ratio significantly decreased as well. Histological examination showed that > 50% of tumor cells became necrotic after repeat dearterializations for 2 hr indicating a significant damage to tumor tissue. In contrast, PBL in combination with repeat dearterializations for 50 min induced extensive liver necrosis without having any influence on tumor growth.

Plasma membrane fluidity during regeneration and atrophy of the rat liver following portal branch ligation.

Dynamic changes in liver plasma membrane fluidity caused by regeneration and atrophy were assessed in rats following portal branch ligation (PBL). The portal branch, which perfuses 70% of the liver, was ligated with 5-0 prolene, and liver plasma membranes were isolated by ultracentrifugation. The membrane fluorescence polarization was measured as an index of membrane fluidity using 1,6-diphenyl-1,3,5-hexatriene (DPH) as the probe dye. In nonligated lobes, a significant decrease in fluorescence polarization was observed 12 and 24 h after PBL (0.171 +/- 0.004, p < 0.01 and 0.165 +/- 0.005, p < 0.001, respectively) as compared to the controls (0.181 +/- 0.002). The fluorescence polarization values then gradually returned to near control levels. In contrast, in the ligated lobes, the fluorescence polarization had increased by 12 hours after PBL (0.196 +/- 0.002, p < 0.01), and remained significantly elevated (p < 0.01) for up to 1 week after PBL, gradually returning to control levels within 3 weeks. The membrane composition was also evaluated by analyzing the cholesterol/phospholipid (C/P) ratio. A significant increase in the C/P ratio was detected in the ligated lobes 12 h and 3 days after PBL, but there was no significant difference in fluorescence polarization values between nonligated lobes and controls. These results suggest that alterations in membrane fluidity play an important role in the regenerative and atrophic processes of the liver following portal branch ligation.

Hemodynamic changes after ligation of a major branch of the portal vein in rats: Comparison with rats with portal vein constriction

In chronic portal-hypertensive rat models, such as portal vein constriction or cirrhosis, the portal blood flow that effectively perfuses the hepatocytes is substantially reduced because of anatomical or functional shunts. It is possible therefore that a feedback mechanism from the liver to the splanchnic bed is responsible for the splanchnic hyperemia observed in chronic portal hypertension. To investigate the possible role of such a feedback mechanism, we examined the chronological changes in both portal and systemic hemodynamics in rats after ligation of a major branch of the portal vein that supplies about 80% of the liver circulation. Rats submitted to sham surgery and portal vein-constricted rats were also studied. Blood flow and portal-systemic shunting were measured by radioactive microsphere techniques. For 7 days after portal-branch ligation, transient portal hypertension resulted from an elevated portal resistance. However, no significant changes in portal venous inflow or splanchnic arteriolar resistance were found in the portal branch-ligated rats, whereas in the portal vein-constricted rats significant hyperdynamic changes in these parameters were noted. On the other hand, transient hyperdynamic changes occurred in the systemic circulation during the period from the fourth to the sixth day after portal-branch ligation, similar to those observed in the portal vein-constricted rats. The lack of hyperdynamic changes in the portal territory of the portal branch-ligated rats suggests that the splanchnic hyperemia found in chronic portal-hypertensive states is unlikely to be caused by a feedback mechanism from the ischemic hepatic parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

New technique of experimental partial liver transplantation: hemodynamic study during surgery.

Orthotopic liver transplantation of children is often limited by the scarcity of an appropriately size-matched donor organ. The transplantation of a reduced liver was thus conceived to solve this problem. A new technique of partial liver transplantation in mongrel dogs is reported, which partially retains the recipient's liver and uses an Ameroid constrictor to occlude the recipient's portal branch gradually. The donor's right and median lobectomy was performed in situ. The donor's left lobe was perfused in situ and removed as a graft. It was then transplanted orthotopically in the space after a left and median lobectomy of the recipient. An Ameroid constrictor was applied around the recipient's right portal branch for a gradual occlusion of the host hepatic blood supply (the Ameroid group). To compare the hemodynamic stability during surgery with this technique, two other methods were also performed. The mean systemic blood pressure of orthotopic liver transplantation with a passive venovenous bypass during the anhepatic period (the Bypass group, n = 5) was lower than that of the Ameroid group (n = 16). Instead of fitting an Ameroid constrictor, an orthotopic partial liver transplantation with ligation of the right portal branch (the Ligation group) was performed. The mean systemic blood pressure of the Ligation group (n = 10) was lower than that of the Ameroid group (n = 11) after either fitting a constrictor or performing a ligation.(ABSTRACT TRUNCATED AT 250 WORDS)

Incorporation of 5-fluorouracil into rat liver tumor and normal tissues and the liver nucleotide profile after administration by the hepatic artery during portal venous branch ligation.

A therapeutic dose of labelled 5-fluorouracil (5-FU) was infused via the hepatic artery during 30 min with or without ligation of the left portal venous branch in Wistar rats with a secondary liver cancer in the left lateral lobe. After another 60 min, the incorporation of 5-FU into the acid soluble fraction (ASF), ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), was determined in tumor, ligated and unligated liver lobes, small intestine, kidney, and bone marrow. The liver nucleotide profile was examined with isotachophoresis. Portal venous branch ligation (PVBL) caused the following changes, compared with the unligated control group: in the tumor, the incorporation of 5-FU into RNA and DNA decreased and the ratio RNA/acid-soluble fraction labelling decreased. The incorporation increased in intestinal and bone marrow RNA. It was unchanged in liver and kidney. The ratio of tumor to peripheral normal-tissue (small intestine, bone marrow, and kidney) labelling of RNA and DNA decreased. Liver nucleotides (F)UTP, (F)UDP-glucuronic acid, (F)UDP-N-acetylhexosamine, and NAD were lower in the ligated than in the unligated liver lobe. ATP and energy charge did not decrease significantly. In conclusion, PVBL in conjunction with hepatic arterial administration of 5-FU increased systemic drug exposure and possibly decreased hepatic tumor anabolism. It has not been examined how this interferes with the therapeutic effect.

A model for directed foreign gene delivery to rat liver cells in vivo

A novel technique for directed delivery of retroviral genes to rat liver cells in vivo is described. Vascular isolation of the liver was achieved in situ and perfusate containing retrovirus expressing the bacterial gene conferring resistance to Hygromycin-B was delivered selectively to the posterior liver lobes. After 15 min, normal blood flow to the liver was restored. The portal venous branch supplying the two anterior liver lobes was ligated either at the same time (Group I, n = 4) or 20 hr prior to perfusion (Group II, n = 4) to stimulate DNA synthesis in the posterior lobes. Controls (Group III, n = 4) were perfused with retrovirus without portal branch ligation. Hepatocyte transduction was assessed 7 days later by isolating the cells and assessing their viability in a selection medium. In Group I and II rats, 9.2 ± 0.5 and 16.0 ± 1.0%, respectively, of harvested hepatocytes, expressed the Hygromycin-B gene. In contrast, a significantly smaller number of hepatocytes (2.8 ± 0.9%, P < 0.003) expressed the gene in the absence of stimulation of DNA synthesis.

Liver cirrhosis in rats: Regeneration and assessment of the role of phenobarbital

A common model for producing experimental liver cirrhosis is the administration of CCl 4 to phenobarbital (PhB)-stimulated rats. However, concern may arise due to the complex actions of PhB upon liver metabolism. This study examined the role of PhB in the production of CCl 4-induced liver cirrhosis in the rat. In addition, regenerative capacity of the liver after partial hepatectomy (PH) or portal branch ligation (PBL) was studied in cirrhotic rats, rats treated with CCl 4 alone, and in PhB-treated controls. In rats given PhB throughout the CCl 4-induction period, ascitic form of micronodular cirrhosis was found in 93% with only 3% mortality. In contrast, rats pretreated with PhB for only 2 weeks followed by CCl 4 alone for 18 weeks did not develop liver cirrhosis. In most of the cirrhotic rats, PH induced hepatic regeneration associated with improved liver histology. PBL was less effective. Treatment with PhB alone for 10 weeks resulted in liver atrophy and reduced hepatic regenerative capacity. Impaired regeneration response was also found in rats treated with CCl 4 alone. In conclusion, treatment with PhB throughout the CCl 4-induction period seems necessary for the production of liver cirrhosis in rats. However, prolonged treatment with PhB alone results in liver atrophy and an impaired regenerative response. Therefore, though necessary for the cirrhotic model, PhB by itself has negative hepatotrophic influences which questions the thoroughness of the PhB/CCl 4 experimental model.

Introduction of monoclonal antibodies to bromodeoxyuridine to monitor hepatic regeneration

The effect on the liver of portal vein and/or bile duct branch ligation was examined in rabbits by measuring cellular kinetics using the bromodeoxyuridine labeling index. Twenty-four days after ligation of a portal vein and/or bile duct branch, similar degrees of compensatory regeneration were observed. However, there were significant differences in the pattern in which regeneration developed. Compensatory regeneration after ligation of a bile duct follows a different pattern than that after portal vein branch ligation.

A SURGICAL CASE OF INTRAHEPATIC PORTO-VENOUS SHUNT WITH PORTAL SYSTEMIC ENCEPHALOPATHY

Intrahepatic porto-venous shunt is a very rare disease. According to retrieval by the author, only 19 cases including the author's have been reported in Japan. Of these, portal systemic encephalopathy occurred in 8 cases, portal branch ligation was performed only 1 case, and the author's was the first hepatectomy case reported among them.The case is a 61-year-old female. She visited the hospital with the chief complaints of lalopathy, dystropy and syncope. Slight liver dysfunction, hyperammonemia and high ICG levels were observed. Abdominal ultrasonic and CT examinations revealed a vascular abnormality in the left hepatic lobe. angiography of the celiac artery detected a shunt between the left portal branch and left hepatic vein. The initial conservative therapy proved ineffective. The lateral hepatic region was resected, so the patient was in good general condition and no severe liver disorder was observed. The neurotic symptoms also disappeared after the operation along with the normalization of various laboratory data. The patient's progress has been good to data without any findings suggestive of portal hypertension. It was considered that cases like the present one showing hepatic encephalopathy with good general condition and good hepatic condition and a shunt localized to one lobe are possible candidates for hepatectomy.

Effects of partial deprivation of portal blood on arterial blood ketone body ratio in rabbits.

To examine the effects of portal blood deprivation on energy metabolism of the liver, we studied: (1) the ketone body ratio (acetoacetate/beta-hydroxybutyrate) in liver tissue, which is in equilibrium with the free NAD+/NADH ratio in liver mitochondria, in the ligated lobe (LL) and nonligated lobe (NLL), (2) the hepatic energy charge [EC = (ATP + 1/2 ADP)/(ATP + ADP + AMP)] in both LL and NLL, and (3) the arterial blood ketone body ratio (BKBR) after left portal vein branch ligation (PBL) in rabbits. As found in LL after PBL, portal blood deprivation decreased the tissue ketone body ratio. The EC in LL significantly decreased after PBL, but recovered 7 days after PBL since the LL became atrophic. The BKBR remained within the normal range, even when 60% of the total liver was deprived of portal blood.

Effect of portal branch ligation on polyamine metabolism in rat liver

The activity of ornithine decarboxylase and the intracellular concentrations of putrescine and spermidine in the non-ligated lobes of the liver increased after portal branch ligation. These changes were followed by increased [ 3H]thymidine uptake into the acid-insoluble fraction of the liver. The induction of ornithine decarboxylase and changes in intracellular polyamines are important biochemical events in liver regeneration, so our results suggest that portal branch ligation causes formation of some stimuli that trigger liver regeneration. Changes were less with ligation than with partial hepatectomy.

Hepatotrophic effect of portal blood during hepatic arterial recirculation.

Portal branch ligation (PBL) is known to induce a rapid and progressive atrophy in the liver parenchyma without portal blood flow and compensatory hyperplasia in the segments receiving the whole portal flow. In this study, the hepatotrophic effect of portal blood was studied in rats with PBL and after this procedure was combined with different portosystemic shunts. After 2 weeks, the most severe atrophy was found in ligated lobes of rats with PBL alone. In shunted animals, the atrophy was significantly inhibited and in relation to the magnitude of portal flow bypassed the liver. This suggests that in shunted rats, the portal-bone hepatotrophic factors undergo systemic recirculation and affect the liver by way of the hepatic artery. Simultaneously, in PBL + shunt rats, the rate of atrophy normally induced by a shunt was also dependent on the amount of portal blood available to this part of the liver. By a balance between these 2 processes, the total liver mass was maintained at the level found in sham PBL + shunt control rats.

Hepatic blood flow in rats with portal branch ligation.

Hepatic arterial blood flow (HABF) in the liver lobes and splanchnic nonhepatic arterial blood flow were measured in rats with and without right portal branch ligation for 1 month using 57Co microspheres. Portal branch ligation led to 60% atrophy of the ligated lobe and to hypertrophy of the nonligated lobe. In nonligated lobes of the portal branch ligation model and in the lobes of controls, HABF expressed per gram liver was comparable. In both models splanchnic non-HABF was also comparable. In the atrophic lobe, HABF remained constant; expressed per gram liver, it increased. In this lobe the net result was a significant decrease in total hepatic blood flow (ml/min/g liver).

Tumor growth in liver atrophy and growth. An experimental study in rats

Despite vast knowledge on liver regeneration, little is known about the effect of active liver atrophy and regeneration on tumor growth. Ligation of a branch of the portal vein to the one or two anterior lobes was performed in inbred Wistar rats. This induces acute atrophy of the anterior and regeneration of the other lobes. During the same operation a tumor cell suspension (NGW 1 — adenocarcinoma) was inoculated in liver lobes undergoing atrophy and regeneration. Tumor volume and weight were measured and the histologic appearance was assessed. During the early and active phases the tumor growth was significantly accelerated in regenerating lobes and partially inhibited in rapidly atrophied segments. After the regeneration and atrophy was completed the normal pattern of growth was re-established in both parts of the liver. The results suggest that tumor growth is affected in proportion to regenerative response. They further suggest that portal branch ligation is of limited value in surgical palliation of liver tumors. The risk for further induction of growth of clinically undetected tumor foci in the remaining liver tissue appears to be small, although a significant, but short-lasting, stimulatory response was found.

Acute hepatotoxicity of carbon tetrachloride. Different liver lobes response in rats with portal branch ligation

Portal branch ligation (PBL) leads to atrophy of the corresponding lobe (AL) and hypertrophy of the non ligated lobes (HL). Liver architecture of AL is preserved. In this model we assessed in rats, one month after PBL, the acute hepatotoxicity of carbon tetrachloride (CCl4) given i.p. or i.v. Grading of necrosis, steatosis and ballooning demonstrated that at 24 and 48 h, AL were less severely damaged than HL and lobes of sham operated rats. Changes in hepatic blood flow, drug metabolism and/or in sinusoidal cells may represent causes involved in the partial hepato-protection.

Systemic and regional treatment of primary carcinoma of the liver

IX. Summary Primary cancer of the liver is rare in the United States but much more common in Asian and African populations. The median survival after diagnosis for symptomatically treated patients is less than 4 months. Surgical resection is the treatment of choice whenever possible. The reported resectability rate varies from zero to 30%, and the operative mortality from 12.5 to 34%. Although the majority of cases die with recurrent disease, patients whose lesion can be resected have the longest survival (5-year survival rate = 10 to 15%). Radiotherapy has been shown to be of limited benefit for primary carcinoma of the liver. In the past, systemic chemotherapy using a variety of single agents or various combinations produced a low response rate and did not prolong survival times. Two recent reports gave great hopes. In an uncontrolled study (74), 7 of 19 patients had objective response to combinations of 5FU and BCNU, and three patients were in complete remission for 3, 4 and 6 years. In another study (82), all 11 patients responded to adriamycin (median survival = 8 months), with three exhibiting complete tumor regression and surviving 8, 9 and 13 months. Regional chemotherapy to the liver has the advantages of achieving higher local concentrations of drug, prolonging the contact of drug and tumor cells, and reducing systemic toxicity. Several reports showed that intra-arterial infusion of chemotherapeutic agents (5FU, FUDR, methotrexate and mitomycin) can give response in 50 to 75% of the cases, and prolonging survival over untreated patients or patients receiving other routes of chemotherapy. Studies of both animal and human tumors have demonstrated that both primary and metastatic tumors in the liver receive their blood supplies almost exclusively from the hepatic arterial system, whereas normal liver tissue has a double supply: the hepatic artery(s) and the portal vein. Thus, deliberate ligation of the hepatic artery has been used as treatment of primary tumors of the liver. Excluding patients with cirrhosis, massive involvement of the liver and far advanced hepatic decompensation, the overall operative mortality associated with hepatic artery ligation is about 19%, with 4% directly attributable to ligation of the artery. Although selective necrosis of tumor nodules has been demonstrated after ligation of the hepatic artery, there is always a shell of viable malignant cells left at the periphery. Thus, several series have administered chemotherapeutic agents either to branches of the portal vein or to the distal hepatic artery to prevent tumor regrowth. However, currently for primary carcinoma of the liver, there is no definite evidence that hepatic artery ligation, with or without added infusion chemotherapy to the liver, gives better response and/or survival results than infusion chemotherapy to the hepatic artery alone. Thus, carefully controlled and randomized prospective clinical trials are urgently needed to compare these different treatment modalities. Other therapeutic approaches such as infusion chemotherapy via the portal vein, ligation of portal vein branches, and liver transplantation have not shown definite benefit. On the other hand, 2 cases of spontaneous regression of hepatoma and 3 cases of documented cure after 5FU or 5FU-BCNU combination chemotherapy have been reported. In conclusion, primary carcinoma of the liver is a virulent and fatal disease. For non-resectable lesions, regional and systemic chemotherapeutic treatment is available. With the availability of adriamycin and newer combinations of effective agents, the outlook for such patients may be greatly improved.