Biliary excretion of exogenous cadmium and manganese in Long-Evans Cinnamon (LEC) rats characterized by an inherently gross amount of copper-metallothionein in the liver

Long-Evans Cinnamon (LEC) rats are characterized by the sudden onset of hepatitis around 4 months after birth and the gross accumulation of hepatic copper (Cu) accompanied by metallothionein (MT). The biliary excretion of manganese (Mn) and cadmium (Cd) injected intravenously was studied in 3-month-old LEC rats without signs of hepatitis. Injected Mn was excreted into the bile in LEC and Fischer rats used for comparison. However, increased biliary excretion of Cd was found not in the LEC rat but in the Fischer rat. Excretion of horseradish peroxidase (HRP) injected along with the metal mixture was significantly lower in the LEC group than in the Fischer group. Our results suggest that Mn excretion is not related to the existence of a gross amount of Cu-MT. Reduced excretion of Cd may be partly due to binding to Cu-MT in the liver. Decreased excretion of HRP implies the existence of an inherent defect in the bile excretion route for endo- and exogenous substances. Received: 31 January 1994 / Accepted: 11 April 1994     

Two-dimensional Electrophoretic Analysis of Hepatitis-associated Polypeptides in Liver of LEC Rats Developing Spontaneous Hepatitis

High-resolution two-dimensional polyacrylamide gel electrophoresis in combination with silver staining was used to analyze between 800 and 1000 cytosolic and particulate polypeptides from age-matched livers of normal male Long-Evans rat with Agouti coat color (LEA) and Long-Evans rat with Cinnamon-like coat color (LEC) rats with hereditary trait of hepatitis at ages long before, immediately prior to, and just after the onset of hepatitis. Although the electrophoretic patterns of polypeptide expression were very similar with respect to the overall spot patterns, a number of polypeptides which differed either qualitatively or quantitatively were noted. Two constitutively expressed cytosolic polypeptides, P29.5 (M_r 29.5 kDa/pI 6.73) and P30 (30 kDa/6.70), were not detected in livers of LEC animals at any age. In the normal LEA rats both P29.5 and P30 were detected as early as one day after birth and both were expressed at similar concentrations at all ages. In the LEC rats P30-C (30 kDa/6.68) was constitutively expressed in close proximity to the expected position of P30, and P30-C was not detected in the LEA rats. By means of non-equilibrium pH gradient electrophoresis two relatively basic polypeptides were detected in the LEC rats. P18ne was detected immediately prior to and P27ne immediately after the clinical manifestation of hepatitis. Experiments in F₁ backcross ([LEA × LEC] × LEC) animals, however, failed to demonstrate any genetic link between either the expression or lack of expression of P29.5, P30, P30-C, or P18ne and hepatitis development. P27ne was detected in all backcross animals exhibiting hepatitis, but was never observed in LEC rats prior to the onset of hepatitis. Although we were unable to identify any unique loss of expression of polypeptides which are genetically linked to hepatitis susceptibility in LEC rats, specific subsets of quantitatively modulated polypeptides were detected.     

Abnormal Copper Accumulation in Non-cancerous and Cancerous Liver Tissues of LEC Rats Developing Hereditary Hepatitis and Spontaneous Hepatoma

We studied the copper concentrations in the non-cancerous and cancerous liver tissues of LEC rats with hereditary hepatitis and spontaneous hepatoma by atomic absorption spectrophotometry. Copper concentration in the non-cancerous livers of 29-month-old male LEC rats was comparable to that in the livers of LEC rats aged 2, 3 and 8 months whose hepatic copper concentrations were more than 40 times those of normal LEA rats. Copper concentration in spontaneously developed hepatocellular carcinomas of the 29-month-old male LEC rats was lower than that in the surrounding non-cancerous liver tissues, but was still more than 39 times that of 8-month-old male LEA rats. These findings suggest that in LEC rats an abnormal copper metabolism may be maintained during the process of hepatic carcinogenesis.     

High Susceptibility to Hepatocellular Carcinoma Development in LEC Rats with Hereditary Hepatitis

A remarkably high incidence of hepatocellular carcinomas was observed in long-surviving LEC rats with hereditary hepatitis. Among the 60 LEC rats examined between 12 and 28 months of age from F₂₉, and F₃₀, 55 (92%) developed putative preneoplastic and neoplastic lesions such as hyperplastic foci and nodules, and hepatocellular carcinomas. Of these, hepatocellular carcinomas were observed with a high frequency (46/55; 84%). All rats of advanced age that survived more than 18 months developed hepatocellular carcinomas. These results suggest that the development of liver tumors in LEC rats is an age-associated phenomenon with serial hepatic alterations after the subsidence of acute hepatitis. The long-surviving rats had no normal tissue and showed chronic hepatitis in nontumorous tissues of the liver. Cholangiofibrosis was also found in most rats with hepatic lesions. Metastasis of hepatocellular carcinomas was found in four rats. Histologically, the hepatocellular carcinomas were of a well-differentiated type with a typical trabecular structure. Thus, LEC rats seem to be a promising animal model for studying the pathogenesis of hepatitis and hepatocellular carcinoma.     

Immunohistological,microscopical and neurochemical studies on encephalitides

Summary LEC virus derived from a patient with SSPE was inoculated intracerebrally into beagle puppies. All three animals that received cell-associated virus and two of three animals inoculated with cell-free virus developed encephalitis. None of the other animals inoculated with cell-free and cell-associated wild measles or attenuated measles virus developed any disease. Whereas the animals that received inoculation of measles virus developed an antibody response, the animals with encephalitis due to the SSPE virus remained free of antibodies up to the point of death. These results are consistent with those previously reported by us for calves and lambs.This investigation was supported in part by: Hartford Foundation Grant. Deutsche Forschungsgemeinschaft (AZ: Me 270/8), and grants from Sonderforschungsbereich (33), the Stiftung Volkswagenwerk, the Forschungsmittel des Landes Niedersachsen, and Freudenberg Stiftung.These studies have been carried out in collaboration with Drs. S. L. Notermans and W. F. Tijl of the Department of Neurology, Katholieke Universiteit, Nijmegen, Holland. The results of their neurophysiologic studies will be published elsewhere.     

Endothelial cell markers from clinician's perspective

Endothelial cell markers are membrane-bound or cytoplasmic molecules expressed by endothelial cells, which help their easier identification and discrimination from other cell types. During vasculogenesis, endothelial cells differentiate from hemangioblasts to form new blood vessels. With the discovery of endothelial progenitor cells (EPC) and their ability to form new blood vessels, the term vasculogenesis is not only reserved for the embryonic development. Possibility of de novo blood vessel formation from EPC is now widely explored in different ischemic conditions, especially in cardiovascular medicine. Numerous clinical trials have tested enhancing tissue vascularization by delivering hematopoietic cells that expressed endothelial markers. This therapeutic approach proved to be challenging and promising, particularly for patients who have exhausted all conventional therapeutic modalities.Angiogenesis, which refers to the formation of new blood vessels from existing vasculature, is indispensable process during tumor progression and metastasis. Blockage of tumor angiogenesis by targeting and inhibiting endothelial cell has emerged as novel safe and efficacious method to control many advanced malignant diseases. Numerous clinical studies are currently testing new antiangiogenic drugs which target and inhibit endothelial cell markers, receptors or molecules which transmit receptor-mediated signals, therefore inhibiting endothelial cell proliferation, migration and vascular tube formation. Many of these drugs are now widely used in clinical settings as first- or second-line chemotherapy in advanced malignant conditions.So far, these therapeutic approaches gave modest, yet encouraging clinical improvements, prolonging survival and improving functional capacity and quality of life for many terminally ill patients.Here we present the most commonly used endothelial cell markers along with their applicability in contemporary clinical practice.     

Mild zinc deficiency and dietary phytic acid accelerates the development of fulminant hepatitis in LEC rats

BACKGROUND AND AIM: Restriction of copper intake delays hepatic copper accumulation in Long-Evans Cinnamon (LEC) rats, which are animal models of Wilson's disease. Involvement of zinc is suggested to develop hepatitis in the disease; however, this has not been clarified. The aims of this study were to investigate the effects of mild zinc deficiency on the development of hepatitis and to determine the relationship between the absorption and hepatic levels of copper, zinc and iron. METHODS: Male LEC and F344 (wild type atp7b) rats were fed a low zinc, phytate-containing or control diet. The onset of hepatitis (Experiment 1), and absorptive rates of copper, zinc and iron and hepatitis indices in 4 weeks (Experiment 2) were observed. RESULTS: The onset of fulminant hepatitis in LEC rats was much earlier in the low zinc and phytate groups (mean 94.6 +/- 2.74 days and 82.8 +/- 3.56 days old, respectively) than in the control group (136 +/- 2.11 days old) with worse hepatitis indices. Hepatic copper levels were much higher in LEC rats than F344 rats, but were not largely different among the diet groups without prominent changes in copper absorption. Hepatic levels and intestinal absorption of zinc and iron were lower in the phytate group than in the control group. CONCLUSION: Mild zinc deficiencies caused by a low zinc or phytate-containing diet accelerate the onset of hepatitis in LEC rats without increasing copper absorption, and zinc and iron metabolism may be involved in the earlier onset of jaundice of LEC rats.     

人ATP7B基因在转基因大鼠的铜代谢通路中的功能分析

目的　利用转基因大鼠模型 ,研究人Wilson病致病基因ATP7B在铜代谢通路中的功能。方法　将构建的 7 1kb含有鸡 β肌动蛋白启动子的人正常ATP7BcDNA ,经显微注射法导入Wilson病动物模型LEC(long_evanscinnamon)大鼠受精卵的雄性原核。以RT_PCR和Westernblot分析其在转基因大鼠各组织内的表达谱 ;用抗大鼠铜蓝蛋白抗体检测肝细胞全铜蓝蛋白 (holoceruloplasmin)的合成 ;同时对 6～ 30周龄的转基因大鼠血清铜蓝蛋白亚铁氧化酶活性、血清铜浓度、胆汁的铜分泌量、以及肝、肾和脑组织中的铜含量进行分年龄段连续测定和统计学分析。结果　在转基因大鼠体内 ,ATP7B在各种组织中获得广泛表达 ,其中肝和肌肉中的表达水平较高 ,肝细胞恢复了全铜蓝蛋白的合成 ,血清中的铜含量及胆汁的铜排泄量增加 ,肝、肾组织中的铜蓄积减少。结论　完整表达人ATP7B基因产物的转基因大鼠的肝细胞 ,通过CPN介导的铜向血清的分泌和调节铜向胆汁的排泄 ,恢复了ATP7B参与铜转运功能 ,Wilson病的铜蓄积与ATP7B基因的突变直接相关。     

人ATP7B转基因大鼠模型的建立及其在转基因大鼠体内的表达分析

目的利用受精卵的雄性原核显微注射法,建立人ATP7B转基因大鼠模型。方法将构建7.1kb含有鸡β肌动蛋白启动子的人正常ATP7BcDNA,经显微注射法导入Wilson’s病动物模型LEC(Long-Evans Cinnamon)大鼠的受精卵,利用PCR法筛选、鉴定阳性转基因大鼠,以RT-PCR和Western bolt检测人ATP7B在转基因大鼠体内的表达,并从血液生化指标和临床症状上对16周龄内的阳性转基因大鼠进行分析。结果建立了3株独立的转基因大鼠株系,其中2株转基因大鼠的肝组织中可检测到完整的人ATP7B基因表达产物,血液生化和临床指征显示2株转基因大鼠具有明显的ATP7B相关功能恢复表型。结论人ATP7B在转基因大鼠的肝组织中获得完整和正确的表达,其弥补了转基因大鼠内源性Atp7b基因功能的缺陷。     

CD4T细胞缺乏对胸腺细胞凋亡影响的研究

通过对ＬＥＣ大鼠和正常对照鼠胸遥细胞的凋亡的研究，探讨了ＣＤ４Ｔ细胞缺乏对胸腺细胞凋亡的影响。电子显微镜，抗ｓｓ－ＤＮＡ抗体免疫细胞化学染色及ＤＮＡ片段梯形电泳带结果提示：ＣＤ４Ｔ细胞缺乏可诱导不成熟Ｔ细胞凋亡，对成熟Ｔ细胞无明显影响。