Nonhepatic cell

Several sources have reported using stem cells including embryonic stem cells, adult liver progenitors, and transdifferentiated nonhepatic cells in cell-based thera-pies. Hepatocyte lineage in vitro has been reported in murine embryonic stem cells." It is apparent that hematopoietic stem cells can generate hepatocytes directly. This has been shown in rodent models and confirmed in humans by a study of recipients of bone marrow and liver transplants. ... 

Apolipoprotein B-lOO on the surface of an LDL particle binds to a specific receptor protein on the plasma membrane of nonhepatic cells. The receptors for LDL are localized in specialized regions called coated pits, which contain a specialized protein called clathrin. 

Holmes JL, Pollenz RS. 1997. Determination of aryl hydrocarbon receptor nuclear translocator protein concentration and subcellular localization in hepatic and nonhepatic cell culture lines development of quantitative Western blotting protocols for calculation of aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator protein in total cell lysates. Molec. Pharmacol. 52 202-11... 

Baumann H, Wang Y, MoreUa KK, et al. Complex of the soluble IL-11 receptor and lL-11 acts as IL-6-type cytokine in hepatic and nonhepatic cells. J Immunol 1996 157 284-90. 

Tumors were not clearly or consistently observed in nonhepatic tissues of animals exposed to FireMaster FF-1. Induction of thyroid follicular cell adenoma was inconclusive in mice in both National Toxicology Program bioassays. Equivocal increases in incidences of mononuclear cell leukemia were observed in adult-only exposed rats in the NTP chronic study, and combined perinatal and adult exposure showed no significant increase. Combined analysis of the incidences of this leukemia in the adult-only, perinatal only. 

Patients with malignant disease show increased LD activity in serum up to 70% of patients with fiver metastases and 20% to 60% of patients with other nonhepatic metastases have elevated total LD activity. Notably elevated LD-1 is observed in germ cell tumors (61% of cases), such as teratoma, seminoma of the testis, and dysgerminoma of the ovary. Patients with seminoma have a raised LD-1 m 63% of cases compared with 60% in nonseminoma cases. The percent of patients with increased LD-1 depended on the stage of the disease. LD-1 appeared to be a useful predictor of outcome in patients with testicular germ cell tumors. 

De novo synthesis is particularly active in the liver and placenta. Nonhepatic tissues (e.g., bone marrow) depend on preformed purines that are synthesized in the liver and transported by red blood cells. They are very effective in salvaging the purines and exhibit little or no activity of xanthine oxidase, which oxidizes free purines. 

From 1978 to 1985 renewed interest in tryptophan metabolism via the kynurenine-niacin pathway was generated by the findings of Hayaishi et al. and others of a second enzyme, namely, indoleamine-2,3-dioxygenase (IDO).2 3 This enzyme was found to be present in several nonhepatic tissues (lung, intestine, brain, and epididymis) and cells (blood monocytes, macrophages, and eosinophils). The enzyme normally has very low activity but is induced to very high activity by stimulation of immune systems with interferon-y1-8 or interleukin-2 (cytokines).9 Thus, inflammatory processes, infections, and immune stimulation that induce interferon-y could lead to... 

The more recent discovery that the enzyme indolamine dioxygenase (IDO) also is involved in the kynurenine-niacin pathway in nonhepatic tissues, such as lung, intestine, and epididymis, or in cells, such as monocytes, macrophages, and eosinophils, has been a major breakthrough. It has expanded the information about the utilization and involvement of tryptophan in cells considered to be active in immunologic reactivity and responses. 

Cholesterol is packaged in chylomicrons in the intestine and in very-low-den-sity lipoprotein (VLDL) in the liver. It is transported in the blood in these lipoprotein particles, which also transport triacylglycerols. the triacylglycerols of the blood lipoproteins are digested by lipoprotein lipase, chylomicrons are converted to chylomicron remnants, and VTDT is converted to intermediate-density lipoprotein (IDL) and subsequently to low-density lipoprotein (LDL). These products return to the liver, where they bind to receptors in cell membranes and are taken up by endocytosis and digested by lysosomal enzymes. LDL is also endocy-tosed by nonhepatic (peripheral) tissues. Cholesterol and other products of lysosomal digestion are released into the cellular pools. The liver uses this recycled cholesterol, and the cholesterol that is synthesized from acetyl CoA, to produce VLDL and to synthesize bile salts. 

Darlington (1977) obtained hybrids of somatic cells which were isolated from hepatic and other cell cultures of mice (i.e., of hepatic and nonhepatic origin). The hepatic cells HePa la and HH synthesize albumin, transferrin and a-fetoprotein. Most somatic Hybrids between these cells and L-cells did not demonstrate albumin and a-fetoprotein synthesis, but continued to synthesize transferrin. This type of expression was similar for hybrids with one and two doses of the hepatic genes. In hybrid cells between hepatic cells and embryonic hepatic cells, 3 of 17 cells synthesized embryonic a-fetoprotein. The investigators suggested that albumin and a-fetoprotein production in the hybrid cells depends upon the epigenetic status of the nonhepatic parent. 

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