The canals of Hering and hepatic stem cells in humans

Small, extraportal, hepatic parenchymal cells, positive for biliary-type cytokeratins, may represent hepatic stem cells, canals of Hering (CoH), and/or ductal plate remnants. We evaluated these cells 3 dimensionally in normal human liver and massive necrosis. Tissues from normal human livers and from 1 liver with acetaminophen-induced massive necrosis were serially sectioned, immunostained for cytokeratin 19 (CK19), and sequentially photographed. Images were examined to determine 3-dimensional relationships among CK19-positive cells. Immunostains for other hepatocyte and progenitor cell markers were examined. In normal livers, intraparenchymal CK19-positive cells lined up as linear arrays in sequential levels. One hundred of 106 (94.3%) defined, complete arrays within levels examined, most having 1 terminus at a bile duct, the other in the lobule, beyond the limiting plate. In massive necrosis, there were 767 individual CK19-positive cells or clusters around a single portal tract, 747 (97.4%) of which were spatially related forming arborizing networks connected to the interlobular bile duct by single tributaries. C-kit was positive in normal CoH. CK19 co-expressed with HepPar1, c-kit, and alpha-fetoprotein (AFP) in parenchymal cells in massive necrosis. Small, extraportal, biliary-type parenchymal cells represent cross-sections of the CoH that radiate from the portal tract, usually extending past the limiting plate into the proximate third of the hepatic lobule. The 3-dimensional structure of ductular reactions in massive necrosis suggests that these reactions are proliferations of the cells lining the CoH. Therefore, the CoH consist of, or harbor, facultative hepatic stem cells in humans.     

A rat model of acute liver necrosis induced by a monoclonal antibody to liver-specific antigen and complement.

Acute massive hepatic injury was induced in rats by a monoclonal antibody against a rat liver-specific membrane antigen, and its histological characteristics were investigated. A single intravenous injection of murine ascites containing a monoclonal antibody produced numerous hemorrhagic foci of degenerated and necrotic liver cells predominantly in zones 1 (the periportal area) and 2 (the area of transition between the periportal zone and the perivenular zone) of the liver lobule within 10 min. Massive hepatocellular necroses were observed 1 hr later, but no inflammatory cell infiltration occurred in and around the necrotic foci. Immunohistological study demonstrated marked deposition of the third component of the complement system in the necrotic area. Serum complement activity was sharply decreased immediately after the injection of the antibody, suggesting that the hepatic necrosis is ascribable to a complement-mediated immune attack on the liver cell membrane induced by the antigen-antibody reaction. The hepatic necrosis in response to monoclonal-antibody injection did not progress to a chronic disease and healed almost completely, changing to scar tissues within 2 wk. Although it is not clear whether this hepatic injury has any clinical relevance, this antibody/complement model may be useful for investigating the cause and therapy of hepatic diseases such as fulminant hepatitis.     

Diffuse hepatocellular calcification developing in a patient on chronic hemodialysis after ischemic hepatitis

Diffuse hepatic calcification is a rare condition. Previous reports have described patients with end-stage renal disease who developed diffuse hepatic calcification after ischemic hepatitis caused by shock. We herein present a similar case. A 41-year-old man on chronic hemodialysis developed ischemic hepatitis due to shock induced by ventricular tachycardia, followed by progressive hepatic failure. Necropsy of the liver revealed diffuse hepatocellular calcification. Given the similarity by which our case and previously reported cases developed this rare condition, we postulate that chronic renal failure is involved in the pathogenesis of diffuse hepatic calcification.     

Focal spared area in fatty liver mimicking a tumor

A focal fatty liver change may be associated with several conditions related to diffuse hepatic steatosis, such as a diffuse fatty liver change. Using ultrasonography, the focal fatty liver change appears more frequently as hyperechoic and less frequently as hypoechoic areas in the liver. We report a rare case of a focal fatty liver change in which an area was spared in fatty liver. The patient was a 42-year-old man. Abdominal ultrasonography showed focal hypoechogenicity with an irregular margin in S8 within a bright liver. Abdominal computed tomography and enhanced computed tomography showed a high-density mass in S8 of the right lobe. A microscopic examination of the specimens from the liver biopsy from the hypoechoic region revealed normal hepatic parenchymal cells, while tissue samples from the surrounding liver had a high fat deposition.     

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.     

Hepatic non-parenchymal cells and extracellular matrix participate in oval cell-mediated liver regeneration

AIM： To elucidate the interaction between non- parenchymal cells, extracellular matrix and oval cells during the restituting process of liver injury induced by partial hepatectomy （PH）. METHODS： We examined the localization of oval cells, non-parenchymal cells, and the extracellular matrix components using immunohistochemical and double immunofluorescent analysis during the proliferation and differentiation of oval cells in N-2- acetylaminofluorene （2-AAF）/PH rat model. RESULTS： By day 2 after PH, small oval cells began to proliferate around the portal area. Most of stellate cells and laminin were present along the hepatic sinusoids in the periportal area. Kupffer cells and fibronectin markedly increased in the whole hepatic Iobule. From day 4 to 9, oval cells spread further into hepatic parenchyma, closely associated with stellate cells, fibronectin and laminin. Kupffer cells admixed with oval cells by day 6 and then decreased in the periportal zone. From day 12 to 15, most of hepatic stellate cells （HSCs）, laminin and fibronectin located around the small hepatocyte nodus, and minority of them appeared in the nodus. Kupffer cells were mainly limited in the pericentral sinusoids. After day 18, the normal liver Iobule structures began to recover.CONCLUSION： Local hepatic microenvironment may participate in the oval cell-mediated liver regeneration through the cell-cell and cell-matrix interactions.     

Influence of hemorrhagic shock on hepatic energy metabolism in carbon tetrachloride-induced cirrhotic rats

The influence of hemorrhagic shock on hepatic energy metabolism was investigated in carbon tetrachloride (CCl4)-induced cirrhotic rat. In normal and CCl4-treated rats, the hepatic mitochondrial redox state and phosphorylative activity decreased significantly (P less than 0.001) following hemorrhagic shock, with mean arterial blood pressure at 30 mmHg. In normal rats, they were immediately restored upon reinfusion of shed blood after 2 hr of hemorrhagic shock, followed by marked enhancement 120 min later. By contrast, in cirrhotic rats redox state and phosphorylative activity in hepatic mitochondria did not recover immediately, and there was neither elevation of redox state nor enhancement of phosphorylative activity in hepatic mitochondria. The survival rate at 24 hr was 10% in contrast to 90% in normal rats. These results suggest that the absence of early recovery followed by enhancement of mitochondrial function in the cirrhotic liver is fundamentally related to the mechanism of hepatic failure following hemorrhagic shock.     

Formation and clinical significance of reddish markings on the liver surface: Activity of chronic liver disease

Background: The aim of this study was to clarify the clinical significance of reddish markings appearing on the surface of the liver. Methods: Subjects were patients with Hepatitis B virus‐related (n = 232) or Hepatitis C‐related (n = 246) chronic liver disease. Reddish lesions were obtained from this population using punch biopsy (n = 30) or wedge biopsy (n = 4), then studied histopathologically. In addition, the incidence and macroscopic forms of reddish markings in each laparoscopic stage for the 478 subjects were examined to determine when reddish markings appeared. Results: Reddish markings on the liver surface appeared only after the appearance of hepatic parenchymal destruction subjacent to the liver capsule, rather than with the appearance of piecemeal necrosis in the portal area. Moreover, following expansion of necrotic hepatic parenchyma subjacent to the liver capsule and distortion of hepatic lobular architecture in this lesion, net‐like or hemorrhagic fleck‐like reddish markings appeared. Therefore, this was recognized as changes at the liver capsule, such as capillary proliferation and dilatation, and blood flow changes in both the capsule and hepatic parenchymal lesions subjacent to the liver capsule. With regards to timing, reddish markings were most frequently observed in the transition to liver cirrhosis. After the appearance of reddish markings on the liver surface, chronic hepatitis rapidly progressed to liver cirrhosis. Conclusion: Reddish markings correspond to hepatic parenchymal destruction subjacent to the liver capsule, and not to piecemeal necrosis. Reddish markings appear in the transition to liver cirrhosis and might offer a useful marker of the progression to liver cirrhosis.     

Mechanism for Selective Perivenular Hepatotoxicity of Ethanol

Chronic alcohol administration to baboons results in perivenular lesions in the liver. To study possible mechanisms, the effect of ethanol on splanchnic oxygen consumption was measured. Acute ethanol administration increased splanchnic oxygen consumption in the control baboons, but the consequences of this effect on oxygenation of the perivenular zones were offset by a concomitant rise in blood flow, resulting in unchanged hepatic venous oxygen tensions. In alcohol-fed baboons, splanchnic oxygen consumption was not increased, either in the withdrawal state or after ethanol infusion. To study the magnitude of the shift in redox state induced by ethanol in the perivenular zones, we compared the effects of ethanol on the lactate/pyruvate ratio in hepatic venous blood (an approximation of that in perivenular hepatocytes) with the ratio in total liver. Prior to ethanol infusion, the lactate and pyruvate were the same in liver and in hepatic venous blood. By contrast, in all baboons, ethanol produced a much greater rise in the lactate/pyruvate ratio and decreased pyruvate more in hepatic venous blood than in total liver. Moreover, in isolated rat hepatocytes, the ethanoMnduced redox shift was markedly exaggerated by oxygen tensions similar to those found in centrolobular zones. This suggests that the normally low oxygen tensions existing in perivenular zones exaggerate the ethanol-Induced redox shift, a change which may contribute to the exacerbation of the damage in the perivenular area of the hepatic lobule.     

Hepatic volumetry to predict adverse events in percutaneous ablation of hepatocellular carcinoma

BACKGROUND/AIMS: This study aimed to clarify the relation of hepatic volumetry to adverse events after percutaneous transhepatic ablation for hepatocellular carcinoma. METHODOLOGY: One hundred and forty-nine patients with hepatocellular carcinoma who underwent percutaneous ablation sessions with complete ablation of cancer nodules, underwent volume measurement of the entire liver, tumor, and ablated area using computed tomography. The parenchymal ablation rate was calculated: (ablated volume-tumor volume)/(entire liver volume-tumor volume) x 100 (%). Other clinical parameters were also analyzed to determine their relationship to adverse events. RESULTS: The median adjusted liver volume was 591 mL/body surface area (m2) (range: 300 to 1197 mL/m2). The median parenchymal ablation rate was 2.3% (range: 0.2% to 20.2%). Adverse events were observed in 17 patients after percutaneous ablation: liver abscess in 3, hepatic infarction in 3, portal vein thrombus in 3, hemobilia in 1, pleural effusion and/or ascites in 6, and gastric ulcer in 1. Multivariate analysis showed that Child B or C (P = 0.0009), adjusted liver volume < 600 mL/m2 (P = 0.0004), and parenchymal ablation rate > 5% (P = 0.0320) were independent risk factors for adverse events. CONCLUSIONS: Measurement of liver volume and parenchymal ablation rate are useful to predict the presence of percutaneous ablation-related adverse events.     

Signal intensity of the liver parenchyma in microbubble contrast agent in the late liver phase reflects advanced fibrosis of the liver.

BACKGROUND: Microbubble of Levovist accumulates in liver parenchyma, and the phenomenon has been reported as late liver-specific parenchymal. The aim of the present study was to compare the parenchymal enhancement effect of Levovist with the degree of liver dysfunction. PATIENTS AND METHODS: Sixty consecutive patients who consented to be treated were enrolled in this study. Pulse-inversion ultrasonography (US) in the liver parenchymal phase of enhancement with Levovist was performed in a preoperative examination. The mechanical index of pulse-inversion US was set at 1.3. The gray-scale intensity of the non-tumor area of the liver parenchyma at the level of the focal zone was measured. The hepatic fibrosis index was measured in each liver by morphometric analysis. The correlation between the gray-scale intensity of the non-tumor area of the liver parenchyma and the hepatic fibrosis index was assessed. RESULTS: There was a significant inverse correlation between the gray scale of the liver parenchyma and the hepatic fibrosis index (r = -0.809, P < 0.01). The average signal intensity of the liver parenchyma was 144.5 in a normal liver, 133.6 in chronic hepatitis, and 102.6 in liver cirrhosis, demonstrating a significant difference between a normal and cirrhotic liver (P < 0.01). CONCLUSIONS: The signal intensity of a microbubble disruption of the liver parenchyma in the late phase of enhancement with Levovist was considered to reflect the degree of hepatic fibrosis.     

Quantitative immunohistochemical analysis of lymphocyte subsets in alcoholic liver disease

Abstract To investigate the role of lymphocytes frequently observed in the parenchyma of alcoholic liver disease (ALD), lymphocytes infiltrating into the liver were stained immunohistochemically with monoclonal antibodies (MoAb) and were quantitatively assessed by a morphometric analysis in 17 patients with ALD and, for comparison in five patients with chronic active hepatitis B (B-CAH). In patients with alcoholic hepatitis, the number of CD8⁺ lymphocytes in the hepatic lobule was similar to that in patients with B-CAH but was significantly greater than that in alcoholics with hepatic fibrosis (HF). The CD4/CD8 ratio in the hepatic lobule was low in both alcoholic hepatitis and B-CAH compared with that of alcoholic patients with HF. When Mallory bodies (MB) and lymphocytes were simultaneously stained with a specific antibody against MB and MoAb, respectively, only CD3⁺ and CD8⁺ lymphocytes were found to have a close contact with MB. These results suggest that in alcoholic hepatitis, hepatocyte necrosis may be partly mediated by immunological mechanisms involving cytotoxic T cells infiltrating into the hepatic lobule.     

Inhibitory effect of acyclic retinoid (polyprenoic acid) on hepatic fibrosis in CCl4-treated rats

A study was conducted to examine the inhibitory effect of acyclic retinoid (polyprenoic acid) on the development of hepatic fibrosis induced by CCl4 in rats. Oral administration of the compound brought about a significant reduction in both serum and tissue levels of immunoreactive prolyl hydroxylase, a key enzyme of collagen formation. The result indicated that the rate of collagen synthesis in the liver was decreased which was consistent with histological findings. Acyclic retinoid also decreased both AST and ALT activities in serum, demonstrating the reduction in hepatic parenchymal damage. This cytoprotective effect on parenchymal cells may be related, at least in part, to inhibition of hepatic fibrosis. No significant side effects were observed, despite a long-term administration of the acyclic retinoid. The present findings suggest the potential scope of therapy of hepatic fibrosis by retinoid.     

Lobular distribution of alcohol dehydrogenase in the rat liver

The hepatic lobular localization of alcohol dehydrogenase was determined in male, female and castrated male rats. Alcohol dehydrogenase immunoreactive protein and activity were increased in female and castrated rats as compared to normal male rats. By immunohistochemistry, alcohol dehydrogenase protein was found localized principally in the perivenous area of the hepatic lobule in all of the animals. Alcohol dehydrogenase activity eluted from the male rat liver, during bidirectional digitonin perfusion, exhibited a pattern characteristic of cytosolic enzymes predominantly localized to the perivenous area. The elution of the enzyme was more rapid during cava-porta than porta-cava perfusion occurring in close association with the elution of glucokinase, an enzyme localized principally in the perivenous area. By contrast, elution of lactate dehydrogenase, which is located predominantly in the periportal area, preceded elution of alcohol dehydrogenase during porta-cava perfusion, but followed it during cava-porta perfusion. These differences were less apparent in the cava-porta than in the porta-cava direction. The predominant localization of alcohol dehydrogenase immunoreactive protein and activity to the perivenous area of hepatic lobule was not affected by sexual difference or increase in the enzyme following castration.     

清肝活血方对酒精性肝病大鼠肝组织Ⅰ型胶原表达的影响

目的 :观察清肝活血方对酒精性肝病大鼠肝组织 型胶原表达的影响。方法 :4 5只大鼠用乙醇、玉米油、吡唑等制备酒精性肝病大鼠模型 ,随机均分为模型组 ,清肝活血方低、高剂量组 ,小柴胡冲剂组 ,用免疫组化观察肝组织 型胶原的分布 ,RT- PCR法检测大鼠肝组织 型胶原 m RNA表达 ,并与对照组比较。结果 :酒精性肝病大鼠模型表现为肝功能异常 ,以门冬氨酸氨基转移酶 (AST)变化为显著 ,模型组大鼠肝组织在汇管区有少量 型胶原的分布 ,部分向小叶内延伸 ;正常组大鼠几乎无 型胶原 m RNA表达 ,模型组有明显表达 ,清肝活血方高剂量组 型胶原及其 m RNAR的表达均明显下降 (P <0 .0 5 )。结论 :清肝活血方能有效预防酒精引起的肝损伤、肝纤维化的发生、发展 ,其机制可能与其抑制 型胶原 m RNA表达有关     

Inhibitory effect of acyclic retinoid (polyprenoic acid) on hepatic fibrosis in CCl4-treated rats

A study was conducted to examine the inhibitory effect of acyclic retinoid (polyprenoic acid) on the development of hepatic fibrosis induced by CC1₄ in rats. Oral administration of the compound brought about a significant reduction in both serum and tissue levels of immunoreactive prolyl hydroxylase, a key enzyme of collagen formation. The result indicated that the rate of collagen synthesis in the liver was decreased which was consistent with histological findings. Acyclic retinoid also decreased both AST and ALT activities in serum, demonstrating the reduction in hepatic parenchymal damage. This cytoprotective effect on parenchymal cells may be related, at least in part, to inhibition of hepatic fibrosis. No significant side effects were observed, despite a long-term administration of the acyclic retinoid. The present findings suggest the potential scope of therapy of hepatic fibrosis by retinoid.     

Lack of susceptibility to ischemic necrosis of the remnant liver following partial hepatectomy in the rat

BACKGROUND/AIMS: The increase in liver lobule dimensions that occurs following partial hepatectomy could predispose living related donors to ischemic hepatic injury were shock-like states to occur in the future. METHODOLOGY: In the present study, rats that had undergone 70% partial hepatectomies or sham surgery six weeks earlier were progressively bled to a maximum of 40% total circulating blood volume. RESULTS: Despite significant increases in liver lobule dimensions (1.5x controls), hepatectomized rats did not manifest biochemical or histologic evidence of early or more extensive hepatic injury when compared to sham-operated controls. CONCLUSIONS: The results of this study suggest that despite theoretical concerns, living related donors are not predisposed to develop ischemic hepatic injury were shock-like states to develop in the future.     

The Immunological Localization of Factor V in Human Tissue

Antibody to factor V was produced by immunizing rabbits with purified factor V from human plasma. Various tissues were examined for the presence of factor-V antigen using this antiserum. It was consistently demonstrated in homogenates of liver and spleen by means of an antibody (coagulation inhibitor) neutralization technique. The antigen was further localized histologically by the indirect fluorescent antiglobulin technique. It was present on the endothelium of normal blood vessels in all organs examined. In the liver it was detected in hepatic parenchymal cells and a distinctive pattern of fluorescence in the spleen suggested that it was being detected on platelets. Results were negative in all other tissues examined. The findings confirm the presence of factor V in hepatic parenchymal cells and support the suggestion that endothelial coagulation factors may play a role in haemostasis and thrombosis.     

Periportal and pericentral pyridine nucleotide fluorescence from the surface of the perfused liver: evaluation of the hypothesis that chronic treatment with ethanol produces pericentral hypoxia.

Pyridine nucleotide fluorescence made from the surface of the hemoglobin-free perfused rat liver was measured continuously by using a "micro-light guide" placed on selected periportal and pericentral regions of the liver lobule. From the portal oxygen tension at which pyridine nucleotide reduction first occurred in pericentral regions, the oxygen gradient across the liver lobule was estimated in livers from rats treated chronically with ethanol or sucrose. Chronic treatment with ethanol increased the average lobular oxygen gradient from 275 to 400 torr (1 torr = 133 Pa), primarily due to the increase in the oxygen gradient in pericentral regions. Ethanol treatment also increased hepatic oxygen uptake significantly, from 110 to 144 (mumol/g)/hr. Treatment with the antithyroid drug 6-propyl-2-thiouracil reversed the effect of ethanol on O2 uptake and on the lobular oxygen gradient. The oxygen gradients measured with the micro-light guide were confirmed by direct measurement of tissue oxygen tensions in periportal and pericentral areas by using an oxygen electrode. These data are consistent with the hypothesis that chronic treatment with ethanol causes the pericentral region of the liver lobule to become susceptible to hypoxic cellular injury. This may be responsible, at least in part, for the localized hepatotoxic effects of ethanol.     

Hepatic disease in erythropoietic protoporphyria.

Two sisters had erythropoietic protoporphyria and a spectrum of liver disease. One (F.B.) died in hepatic failure within 3 months after the development of jaundice. Only 10 months before she died, she had exhibited only bromsulfalein retention and a borderline increase in serum transaminase. Surgical exploration because of the jaundice revealed patency of the bile ducts which was confirmed at autopsy. Wedge biopsy and autopsy specimens of liver showed an active cirrhosis with massive amounts of protoporphyrin in Kupffer cells, portal histiocytes, bile canaliculi and parenchymal cytoplasm. The other sister (L.R.) had never had symptomatic liver disease and only a slight increase in serum transaminase and bromsulfalein retention. On needle biopsy, the liver specimen showed portal inflammation with erosion of limiting plates, occasional bridging between triads and central areas of cell dropout. Protoporphyrin pigment was present in portal histiocytes, areas of central collapse and, more rarely, in parenchymal cytoplasm. These studies demonstrate that significant, progressive hepatic disease may occur insidiously in erythropoietic protoporphyria, and that once jaundice appears it may be followed rapidly by fatal hepatic failure.