We studied the influences of chronic tobacco exposure on aging and oxidant-antioxidant balance in two different strains of mice, hitherto called SAM (senescence-accelerated mice). One is a senescence-prone strain, "SAM-P/2," and another is a senescence-resistant strain, "SAM-R/1." We used 100 male mice--20 young (12 weeks of age) mice and 30 mature (24 weeks of age) mice from each strain. Half of each series were housed in a Hamburg II machine and exposed to tobacco smoke inhalation for five weeks. The result was that fewer of the mature SAM-P/2 survived compared with the mature SAM-R/1 after chronic tobacco inhalation. The grading of senility in the mature SAM-P/2 was also significantly higher than that in the mature SAM-R/1. The reduction of glutathione contents of blood and liver after tobacco exposure in the mature SAM-P/2 was greater than that in the young SAM-P/2 and the mature SAM-R/1. Moreover, oxygen radical generation of total blood cells stimulated by phorbol-myristate-acetate or opsonized zymosan showed a greater increase in the mature SAM-P/2 compared to the young SAM-P/2 and the mature SAM-R/1. These results indicate that the senescence-prone strain (SAM-P/2) was more susceptible to tobacco smoke exposure than the resistant strain (SAM-R/1). The impaired oxidant-antioxidant balance in the SAM-P/2 may therefore contribute to the process of senescence acceleration.

Aging↗

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Beneficial effect of tetrahydrobiopterin on the survival of rats exposed to hepatic ischemia-reperfusion injury.

INTRODUCTION: The protective role of nitric oxide (NO) against hepatic ischemia-reperfusion (I/R) injury remains controversial. In this study we investigated the effect of tetrahydrobiopterin (BH4) on the survival of rats exposed to an hepatic I/R injury. METHODS: The rats were subjected to 100 minutes of 70% hepatic ischemia 30 minutes after administration of BH4 or saline. A specific inducible NO synthase (iNOS) blocker, 1400W, was used to evaluate endogenous iNOS. NOS protein measured the histological appearance of the liver by Western blotting, and survival was evaluated after reperfusion. RESULTS: The 1-week survival rate was 60% among the BH4 group and 10% for the saline group. The serum ALT and bilirubin values in the BH4 group were significantly lower than the saline group. Histological examination of the liver revealed only a small necrotic area in the BH4 group as opposed to massive necrosis and cell infiltration in the saline group. Injection of 1400W significantly decreased the prolongation of survival produced by BH4. CONCLUSIONS: BH4 significantly improved the survival rate, the histological findings, and the liver function, thereby reducing liver failure. Western blotting showed a higher level of iNOS protein in the BH4 group than the saline group, 1400W suppressed this effect of BH4. Taken together, these observations suggest that NO derived from reactions driven by BH4-induced iNOS exerts a protective effect against reperfusion injury.

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Teratoma formation and hepatocyte differentiation in mouse liver transplanted with mouse embryonic stem cell-derived embryoid bodies.

We previously reported that mouse embryonic stem (ES) cells are capable of differentiating into hepatocytes in cultured embryoid bodies (EBs) and that hepatocytes generate in the recipient liver injected with cultured day-9 EB cells via spleen without the formation of a teratoma. Because ES cells frequently form teratomas in recipient mice, we investigated incidence of teratoma formation when day-9 EBs derived from ES cells were transplanted directly into the subcapsule of mouse liver. In contrast to injection of day-9 EB cells through the portal vein via the spleen, direct subcapsular injection of cultured day-9 EB cells into liver, and even of cultured day-15 EBs, resulted in an high incidence of teratoma in the liver. In teratomas of livers injected directly with day-15 EBs, hepatocytes were detected singly and in clusters. These results imply that undifferentiated cells capable of developing into teratomas exist in cultured EBs, and even in cultured day-15 EBs containing differentiated hepatocytes.

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Studies on the most efficient vector systems for gene transduction into dendritic cells.

Specialized antigen-presenting cells (APC), known as dendritic cells (DC), play a pivotal role in initiating primary immune responses. Several vector systems, including adenoviral vectors, retroviral vectors, hemagglutinating virus of Japan-related vectors, and the electroporation, have been shown to transduce genes into mouse and human but not rat DC. However, there is no direct evidence to support the view that the currently used vector systems are able to transduce genes into mature DC. Inasmuch as most, if not all, gene transfer studies investigating DC or DC-related cell populations are performed employing heterogeneous-groups of cells, it is therefore important to determine the extent to which gene transduction occurs in bona fide DC. In this study, we provide evidence that none of these vector systems are able to transfer genes into mature rat DC, which are derived from bone marrow cells (BMC), driven by Flt3/Flk2 ligand and IL-6, and purified with CD161a. Nevertheless, the most efficient gene transduction was observed with developing DC progenitor cells during long-term culture of rat BMC. Successful gene transfer was achieved after 2-week culture with an HIV-based lentiviral vector system.

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Isolation of hepatocyte-like cells from mouse embryoid body cells.

We previously reported that embryoid body (EB) cells derived from embryonic stem (ES) cells are capable of differentiating into functional hepatocyte-like cells both in vitro and in vivo. Because transplantation of EB-derived cells into the liver via the spleen resulted in a low incidence of teratoma formation, purification of hepatocyte-like cells is required to prevent teratoma formation. The aim of this study was to purify hepatocyte-like cells from cultured EBs. For the isolation of hepatocyte-like cells, EBs cultured for 15 days were treated with trypsin-EDTA. The disaggregated cells were plated on a gelatin-coated dish as a monolayer. These cells were separated by Percoll gradient centrifugation, enriched by magnetic cell sorting, and purified by FACS. The purified hepatocyte-like cells in monolayer cultures were positive for immunostaining for albumin and expressed albumin mRNA, but not Oct3/4 mRNA. Transplantation of the purified hepatocyte-like cells derived from mouse ES cells might be an effective treatment for liver failure.

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Phenotype and functional identity of GM-CSF-independent dendritic cells generated by long-term propagation of DC progenitor cells in bone marrow cells and skin Langerhans cells.

Evidence is provided that dendritic cells (DC) generated by either long-term bone marrow cell (BMC) culture with Flt3L and interleukin-6 (IL-6), or after short-term BMC culture with granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), contain heterogeneous cell populations of admixed DC and Mphi, regardless of the cytokine source. By employing GM-CSF-independent culture systems with the aid of Flt3/Flk-2 ligand and IL-6 and phenotypic characterization of BMC-derived DC and skin Langerhans cells (LC), revealed similar phenotypes. Furthermore, CD103 (OX62), which is widely used for rat DC separation, was found to be insufficient to enrich DC, due to downregulation of the marker. In this regard, the most efficient selection of rat DC, was obtained by CD161a (NKR-P1A), a member of the C-type lectin family. Despite the phenotypic similarity with BMC-derived DC, the nucleus of LC showed a distinct morphology. A large population of DC generated by Flt3L/IL-6 from GM-CSF receptor-deficient mice by do not express NK1.1 (NKR-P1B and NKR-P1C). The profiles for BMC-derived DC were the same as for skin Langerhans cells.

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PubMedDate not supplied

A new serum protein (KX-5) induced by liver transplantation suppresses heart allograft rejection in nonspecific manner.

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Animals↗

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In vivo and in vitro analysis of the effectiveness of doxorubicin combined with temporary arterial occlusion in liver tumors.

PURPOSE: The authors evaluated the effects of daunomycin (daunorubicin)--an analogue of doxorubicin--ethiodized oil, and arterial occlusion on an in vitro hepatoma analogue and on in vivo rat liver tumors. MATERIALS AND METHODS: A human Sk hepatoma cell monolayer sandwich system was used to determine uptake of 3H-daunomycin under normoxic/hypoxic conditions with use of autoradiography. Fluorescence microscopy was used to evaluate the biodistribution of doxorubicin in cell cultures (human Sk hepatoma and colon carcinoma). Microvascular flow adjacent to and within liver tumors and the intrahepatic effects of doxorubicin and ethiodized oil were studied with in vivo video microscopy on exteriorized rat livers containing peripheral hepatomas. RESULTS: Increased uptake of 3H-daunomycin by hepatoma cells occurred under hypoxic conditions. Intrahepatic arterial administration of ethiodized oil caused temporary occlusion of peripheral sinusoids following passage through arterioportal anastomoses. Tumors received portal venous and neovascular blood supply and ethiodized oil occluded but did not enter the narrow neovasculature perfusing the tumors. CONCLUSION: Hypoxia increases uptake of 3H-daunomycin by human Sk hepatoma and colon carcinoma cell cultures. Selective hepatic arterial occlusion (and perhaps the resultant hypoxia) may facilitate increased uptake of doxorubicin analogues into liver tumors. Hepatomas receive both arterial and portal venous blood supply, and ethiodized oil reaches the tumor via arterioportal anastomoses that perfuse the tumor periphery.

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