Studies on the regulation of cholesterol 7 alpha-hydroxylase and HMG-CoA reductase in rat liver: effects of lymphatic drainage and ligation of the lymph duct.
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Lymphatic drainage leads to a significant stimulation of both the cholesterol 7 alpha-hydroxylase and HMG-CoA reductase activity in rats (Bjorkhem et al. 1978. Biochem. Biophys. Res. Commun. 85: (532-540). This finding was confirmed here and it was also shown that ligation of the lymph duct leads to a similar but less pronounced effect. Ligation of the lymph duct or lymph fistulation of bile duct-ligated or cholestyramine-treated rats did not further increase 7 alpha-hydroxylase or the HMG-CoA reductase activity. However, treatment of lymph fistula rats with cholestyramine led to a significant further stimulation of both 7 alpha-hydroxylase and HMG-CoA reductase activity. Intravenous infusion of lymph into bile fistula rats led to a significant inhibition of both cholesterol 7 alpha-hydroxylase activity and HMG-CoA reductase activity. A corresponding infusion of cholesterol-enriched Intralipid led to inhibition of HMG-CoA reductase without effect on cholesterol 7 alpha-hydroxylase activity. The results show that cholesterol 7 alpha-hydroxylase is feedback-regulated by bile acids in a situation where the flux of cholesterol to the liver is interrupted also. The possibility is discussed that there is a factor in the lymph that down-regulates cholesterol 7 alpha-hydroxylase. If such a factor exists, it requires an intact enterohepatic circulation for its effect. The stimulatory effect of cholestyramine on HMG-CoA reductase also in lymph fistula rats shows that the previously demonstrated suppressive effect of bile acids on HMG-CoA reductase is not only due to the effect of bile acids on intestinal absorption of cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS) (+info)
Lymphatic pump treatment augments lymphatic flux of lymphocytes in rats.
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Allograft rejection in athymic nude rats by transferred T-cell subsets. I. The response of naive CD4+ and CD8+ thoracic duct lymphocytes to complete allogeneic incompatibilities.
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PVG.rnu/rnu nude rats were pre-grafted with two allogeneic skin grafts, AO(RTlu) and BN(RTln), 6-14 days in advance of cell transfer. Cellular requirements for rejection were established by transferring graded numbers of B cell-depleted (Ig-) thoracic duct lymphocytes (TDL) or purified W3/25+ (CD4+) or OX8+ (CD8+) TDL subsets. Allografts were rejected by 10(5) to 5 x 10(6) Ig- TDL in a dose-dependent fashion. A similar dose-response relationship was found by transferring 5 x 10(5) to 5 x 10(6) Ig- OX8- TDL (purified by depletion of B cells and OX8+ cells). Larger numbers of Ig- OX8- TDL (10-30 x 10(6)) did not significantly accelerate rejection. W3/25+ TDL alone (10(5)), highly purified by fluorescence-activated cell sorting (FACS), were sufficient to induce allograft rejection in this athymic nude rat model. In contrast, 10 times more FACS purified OX8+ TDL (10(6)) were unable to initiate skin graft rejection despite the complete class I and class II MHC incompatibilities. Furthermore, the addition of 10(6) OX8+ cells did not accelerate or retard the rejection induced by 10(5) W3/25+ cells alone. Pre-grafted nude recipients, irradiated (500 R) 2 hr before W3/25+ TDL injection, in order to eliminate putative nude T cells, rejected allografts on the same day as unirradiated controls. We conclude that when confronted with complete MHC disparities, CD4+ T cells are necessary and sufficient to induce skin allograft rejection whereas CD8+ T cells do not appear to contribute. (+info)
T-helper subset function in the gut of rats: differential stimulation of eosinophils, mucosal mast cells and antibody-forming cells by OX8- OX22- and OX8- OX22+ cells.
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Thoracic duct lymphocytes (TDL) collected 3 days after infection of rats with Trichinella spiralis (TS) and adoptively transferred into normal, uninfected recipients, increased the numbers of both mucosal mast cells (MMC) and eosinophils (EOS) in the intestine. The CD4+ T-helper cell population was separated into two subsets (OX22+ and OX22-) using OX22 monoclonal antibody (mAb) and panning techniques. After adoptive transfer of these T-helper subsets i.v., rats were challenged with TS 24 hr later. The intestine of recipient rats was examined histologically at intervals from Day 3 to Day 21. On Day 9 after transfer, OX22+ T helpers induced a substantial mastocytosis [94 +/- 3, mean +/- SE/villus crypt unit (VCU)], whereas the OX22- T-helper subset increased resident EOS numbers (60 +/- 2/VCU) compared to the challenge control (18 +/- 1 MMC, 27 +/- 1 EOS/VCU). The time of peak eosinophilia was advanced by 3-6 days for recipients of OX22- cells and that of mast cells by 9-12 days for recipients of OX22+ cells. The recipients of OX22-, but not OX22+, cells also showed a large increase in the numbers of B cells in the spleen and mesenteric lymph node (MLN) secreting antibody against adult TS. Recipients of OX22- cells displayed an even increase in EOS throughout the villi, lamina propria (LP) and muscularis, whereas in OX22+ cell recipients mast cells were only present in the lower villus and the epithelium just above the crypt as well as the muscularis layer. Only the CD4+ OX22- cell subset conferred protection against TS in the intestine. We conclude that the OX22+ and OX22- T-helper cells exert distinctive effects in the intestine on MMC and EOS. Because protection was established in the presence of an OX22- T-helper-induced eosinophilia but without a concurrent mastocytosis, the results suggest that MMC are probably not involved in expulsion of TS to terminate the primary infection. (+info)
Near-infrared fluorescence imaging of thoracic duct anatomy and function in open surgery and video-assisted thoracic surgery.
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Anatomical variations in bovine thoracic ducts.
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Gross anatomical observations of bovine thoracic duct pathways and the lymph-venous junctions revealed that 37% of these ducts connected to the left venous angle at one location, whereas the other terminal connected to other areas, such as the left internal jugular vein, the left subclavian vein and the right venous angle, at more than one location. The thoracic duct pathways were classified according to Adachi's classification as types III, VI and IX. The frequencies of types VI, IX and III were 76%, 15%, and 9%, respectively and 48% of cattle had more than one ring formation in the thoracic duct pathway. These findings demonstrate many anatomical variations in bovine thoracic duct pathways and lymph-venous junctions. (+info)