Are prealbumin plasma levels linked to amino acid supply from peripheral tissues in liver cirrhosis?

Summary Prealbumin plasma level is considered a good index of liver function in liver cirrhosis. However, plasma protein levels depend not only on liver function, but also on amino acid supply which is consequent to nutritional status.In 12 cirrhotics we measured prealbumin plasma levels and the lower limb venous-artero difference of amino acid plasma levels in blood samples taken from femoral vein and femoral artery in post-absorptive conditions considered as a direct index of protein release from peripheral tissues and an indirect index of protein nutritional status.In arterial and in venous plasma amino acid sum was 1.86±0.40 (mean + sd) and 2.00 ± 0.04 mMol/l respectively.Prealbumin plasma levels were found directly correlated with the venousartero difference of amino acid plasma levels (r = 0.57p < 0.05) and of glutamate + glutamine levels (r = 0.73p < 0.007).In conclusions, these data suggest that prealbumin plasma levels are linked to amino acid supply from peripheral tissues in cirrhotics.     

Seasonal cycles of reserves in relation to reproduction inSebastes

Synopsis Seasonal cycles of reserve deposition and utilization in many fishes, amphibians and reptiles alleviate temporal mismatches of energy supply and demand. Utilization of reserves can be related to maintenance during periods of reduced food supply, to reproduction, particularly during periods of poor food availability, and to migration. Published data on the seasonal cycles of reserves and reproduction inSebastes suggest that reserves are important for maintenance during wintertime periods of low food availability. Unlike many other ectothermic vertebrates, some species ofSebastes deposit fat reserves at the same time as gametogenesis, a pattern consistent with the longevity and iteroparity evident in the genus. Other species ofSebastes have similar seasonal timing of fat cycles, but since reproduction takes place later in the year, the decline in reserves during winter coincides with the main period of reproductive activity. The significance of this is not clear. Interspecific differences in amounts of reserves may be related to geographical differences in the seasonality or abundance of food. Intraspecific variation in reserves, marked most strongly by allometry of reserves with regard to fish legth, bears further study, since it may link the proces of sexual maturation and the responses of repeat spawners to variability in food supply and other environmental factors.     

Functional and morphological characterization of cultures of Kupffer cells and liver endothelial cells prepared by means of density separation in Percoll,and selective substrate adherence

Summary This paper presents a study on the structure and function of Kupffer cells (KC) and liver endothelial cells (LEC) isolated by a simple and rapid technique involving 1) perfusion of the liver with collagenase; 2) cell separation by means of density centrifugation in Percoll; and 3) cell culture, taking advantage of the fact that KC and LEC differ in their preferences for growth substrate. The KC, which attach and spread under serum-free conditions on surfaces of glass or plastic during the first 15 min in culture exhibit a typical macrophage-like morphology including membrane ruffling and a heterogenous content of vacuoles. Moreover, these cells express (a) Fc receptors (FcR) for binding and phagocytosis of erythrocytes covered with immune globulin G (E-IgG), and (b) complement receptors (CR) for binding and serum dependent phagocytosis of erythrocytes covered with either human C3b or mouse inactivated C3b (iC3b). The cells also bind fluid phase fluoresceinated C3b. Approximately 30% of the KC express immune response-associated (Ia)-antigens.The LEC attach and spread on fibronectin coated surfaces, but not on glass or plastic surfaces, during the first two hours in culture with or without serum, and are morphologically distinct from KC. Cultured LEC are well spread out with no membrane ruffling and with numerous large vesicles surrounding the regularly shaped nucleus. These cells bind, but do not ingest E-IgG via the FcR, but no binding of fluid phase C3b or particle fixed C3b or iC3b can be observed. Incubation of LEC with fluorescein amine conjugates of ovalbumin or formaldehyde treated serum albumin, but not with fluoresceinated native serum albumin, results in accumulation of fluorescence specifically localized in the large perinuclear vesicles. Neither KC nor any other cell types tested have the ability to accumulate fluorescence upon incubation with these compounds. Iaantigens are not present on the LEC.Cytochemical demonstration of unspecific esterase, acid phosphatase, and peroxidase reveals different patterns and intensities of staining in KC as compared to LEC.Abbreviations Used KC Kupffer cells - LEC Liver endothelial cells - C Complement - C3b Major fragment of C3 activation - iC3b C3b that has been cleaved by factor I (C3b inactivator), present in serum - meC3b C3b produced by treating purified human C3 with methyl amine - trC3b C3b produced by treating purified human C3 with trypsin - CR Complement receptors for C3b and iC3b - IgG Immune globulin G - IgM Immune globulin M - E Erythrocytes - E-IgG E covered with anti-E IgG - E-IgM E covered with anti-E IgM - E-C3b(h) E-IgM reacted with purified human C1, C4, oxidized C2 and C3 (E-IgMC14^xyC2C3b) - E-iC3b(m) E-IgM incubated with C5 deficient serum from AKR mice - FcR Receptors for the Fc portion of IgG - FITC Fluorescein isothiocyanate - FITC-meC3b FITC conjugated to meC3b - FITC-trC3b FITC conjugated to trC3b - FA Fluorescein amine - FA-OA Ovalbumin conjugated with FA - FA-SA Serum albumin conjugated with FA - FA-FSA Formaldehyde-treated serum albumin conjugated with FA - Ia Immune response-associated AcE Acid unspecific esterase acting on alpha naphtyl acetate - NASDAE Unspecific esterase acting on naphthol AS-D acetate - NASDCAE Unspecific esterase acting on napthol AS-D chloroacetate     

小鼠肝脏免疫抑制蛋白质(LISP)的分离纯化和鉴定

用硫酸铵分段盐析及DEAE-Sephadex A-50、羟磷灰石和CM纤维素等多种柱层析方法,从正常小鼠肝浸液中分离纯化出一种免疫抑制蛋白质(LISP)。在体外用微量该蛋白质就能强烈抑制小鼠T、B淋巴细胞对促有丝分裂原和同种异型抗原的增生反应。纯化的蛋白质在聚丙烯酰胺凝胶电泳(PACE)和等电聚焦(IEF)鉴定时均显示为一条区带,其等电点(pI)值在7.5—7.8范围。沉降系数利S_(20),w为5.39。Sephadex G-100凝胶层析测得LISP的分子量为78,000道尔顿。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)提示LISP是由二个相同的亚基组成,亚基分子量为38,500道尔顿。LISP是一种既非糖蛋白又非脂蛋白的碱性蛋白质,对它的氨基酸组成也作了分析。     

In vitro metabolism of N-methyl-dibenzo [c,g]carbazole a potent sarcomatogen devoid of hepatotoxic and hepatocarcinogenic properties

The metabolism of N-methyl substituted 7H-dibenzo[c,g]carbazole (N-Me DBC) was investigated in vitro using liver microsomes from 3-methylcholanthrene (MC)-, benzo[c]carbazole (BC) and Arochlor-pretreated mice and rats. N-Me DBC is a potent sarcomatogen devoid of hepatotoxicity and liver carcinogenic activity. The ethyl acetate-extractable metabolites were separated by high performance liquid chromatography (HPLC) and most of them were identified by proton magnetic resonance (PMR), mass spectrometry (MS) and comparison with synthetically prepared specimens. Mouse and rat microsomes gave rise to the same metabolites. The major metabolites were 5-OH-N-Me DBC (50%), N-hydroxymethyl (HMe) DBC (25-30%) and 3-OH-N-Me DBC (10%). Addition of 1,1,1-trichloropropene-2,3-oxide (TCPO) to the standard incubation medium permitted the identification of two dihydrodiols among the minor metabolites. No metabolite of DBC was observed after incubation of N-Me DBC, or its major metabolite N-HMe DBC, with either mouse or rat microsomes, but the possibility of a slight demethylation cannot be totally excluded. The lack of biotransformation at the nitrogen atom site may explain the lack of hepatotoxicity and liver carcinogenic activity of N-Me DBC. The modulation of metabolism by epoxide hydrolase, cytosol and glutathione was also investigated. The results are discussed in the light of data previously obtained with hepatotoxic and hepatocarcinogenic DBC.     

Toxic effects of 2-methyl-4-dimethylaminoazobenzene in normal and partially hepatectomized rats

In order to obtain a more precise definition of the conditions under which 2-methyl-4-dimethylaminoazobenzene (2-Me-DAB) and liver cell proliferation play a role in the initiation of hepatocarcinogenesis, the toxicity of 2-Me-DAB for normal and partially hepatectomized rats was investigated. Continuous feeding of a basal low protein, low riboflavin diet supplemented with 2-Me-DAB was found to be highly toxic for male albino rats. All animals fed on such a diet died before 200 days. Sham operation and partial hepatectomy (PH) at 30 days of 2-Me-DAB feeding reduced the median survival time from 122 days to 107 and 94 days, respectively. Transfer to the basal diet after 30 days of 2-Me-DAB feeding and PH prolonged the median survival time to 216 days while 97% of the rats returned to the normal complete diet after the same treatments survived for more than 300 days. 2-Me-DAB was not necrogenic and there was no evidence of reparative proliferation or hepatic tumor formation in any group. Feeding rats with the 2-Me-DAB containing diet for 1 month delayed and strongly inhibited the mitotic response of the liver to the stimulus of partial hepatectomy. This is the result of a blockage of the cells in G1 as revealed by the fact that only 1% of the hepatocytes became labeled when 2-Me-DAB fed animals were injected with tritiated thymidine prior to sacrifice at 24 h post-hepatectomy, as compared to 40% in rats fed the normal or the control basal diet. This inhibitory effect of 2-Me-DAB is reversible however since rats returned to the normal diet for 1 or 2 months after 2-Me-DAB feeding showed percentages of mitoses and labeling indices comparable to those of control animals following PH. The number of abnormal mitoses was high (13%) in regenerating livers of rats fed 2-Me-DAB and the lesions responsible for this effect are apparently not repaired since 2-Me-DAB fed rats partially hepatectomized after being transferred to the normal diet for 1 or 2 months showed the same number of mitotic irregularities. The present results suggest that assays with 2-Me-DAB as 'pure initiator' or agent of selective toxicity should be pursued in attempts to improve existing experimental models of hepatocarcinogenesis.     

Characteristics of redox-linked proton ejection in cytochrome c oxidase reconstituted in phospholipid vesicles. New observations support mechanisms different from proton pumping

Experimental observations reveal a number of characteristics of the redox-linked proton ejection from cytochrome c oxidase vesicles, which apparently cannot be explained by a proton pumping activity of the oxidase. These observations seem, on the other hand, to provide useful elements for alternative explanation(s) of the proton ejection. It is proposed here that the process is scalar and not vectorial and can derive from redox-linked rupture of protonated salt-bridges in the oxidase-lipid complex.     

Schistosoma mansoni: schistosomulicidal activity of macrophages isolated from liver granulomas of infected mice

Mice infected with Schistosoma mansoni develop T cell-mediated granulomatous reactions around disseminated parasite eggs. In this study, granuloma-derived leucocytes have been examined for schistosomulicidal capacity by the use of in vitro cytotoxicity assays. Adherent macrophages, that were shown by electron microscopy to exhibit no gross morphological abnormalities, were unable to mediate significant mortality in the absence of serum factors. When cocultured with immune serum and complement, however, these cells killed +/- 26% of the larvae at a cell:target ratio of 5000:1. In contrast, granuloma-derived cell populations that were enriched for eosinophils (50-70% eosinophil content) showed only minimal cytotoxic potential. This may be related to observed structural changes in the eosinophil lysosomal granules, or perhaps to blocking of the cell-surface receptors by immune complexes. It is concluded that granuloma macrophages, activated by egg antigen-sensitised T lymphocytes, may serve as effector cells in immunity to schistosomules.     

Differences in chromatin from normal and leukemic human cells as shown by digestion with restriction nucleases

Sequence homology was found by computer analysis between potato spindle tuber viroid (PSTV) RNA and U3B snRNA of Novikoff hepatoma cells. This homology is colinear in arrangement, extends in length to 81% of the entire U3B snRNA molecule and is involved in the PSTV molecule unique sites which, if depicted in terms of the secondary structure of the circular PSTV molecule, reveal a conspicuous regularity in their location. A strong relation in primary structure between PSTV and U3B snRNA is demonstrated by statistical analysis.     

Peroxisome-desmosome complexes in mouse hepatic cells

Summary In addition to mitochondrion-desmosome complexes, peroxisome-desmosome complexes were present in mouse hepatocytes. The latter complexes consisted of a desmosome which was flanked on one or both sides by a peroxisome. Occasional desmosomes were confronted on one side by a peroxisome and on the other by a mitochondrion. It is suggested that the association between organelles and desmosomes is fortuitous, and that no functional significance can be inferred from this association.This work was supported in part by grants from the Heart Association of Northeastern Ohio, Inc., by grant 3C179 from the Cleveland Foundation, by American Cancer Society Institutional Grant In-57-H, and by grant 5 SO1 FR05335-09 from the National Institutes of Health. The expert technical assistance of Merry A. Hetrick and Jeanne Luschin is acknowledged.