Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of MHC class II antigens on potential APC is a crucial step in T-lymphocyte activation and the initiation of an immune response. The studies which are presented here were initiated to characterize the critical APC present in physiologically normal, untreated rats. Such a cell should constitutively express these antigens at high density and therefore provide the apparatus necessary to provoke both primary and secondary immune responses at any time. DAC were found to fulfill these criteria. In the absence of specific surface markers of rat DAC, the results are based on the strict combination of morphological appearance and functional activity. However, the high expression of MHC class II antigens may be regarded as semispecific markers for DAC which are distributed at strategic positions in many lymphoid and nonlymphoid tissues (Hart & Fabre 1981, Steiniger et al. 1984). The relatively low number of these cells observed in tissue sections and in in vitro isolates (0.1% of all cells) may explain their high activity as APC. This would facilitate the presentation of antigen in vivo to a sufficient number of competent T lymphocytes. DAC differentiate from a bone marrow progenitor cell pool preferentially under the influence of spleen cell-derived activities. Although the exact lineage has not yet been determined it may be fair to speculate that DAC form a new cell lineage probably related to interdigitating cells but not to macrophages which differentiate from bone marrow-derived precursors under the influence of colony-stimulating activities. However, the cooperation between DAC plus macrophages may provide the stage for T-lymphocyte activation and T-T collaboration (Mitchison 1990). There are still many open questions concerning the general role of DAC in vivo and in vitro. To further characterize rat DAC, their tissue distribution, role in the immune response and possible influence on intrathymic lymphopoiesis, with respect to T-lymphocyte subpopulations and the selection of the T-lymphocyte antigen-receptor repertoire, a panel of DAC-specific monoclonal antibodies must be generated in the future. Such antibodies will also be useful to study the mechanism by which DAC activate T lymphocytes.
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PMID:Lymphoid dendritic accessory cells of the rat. 225 88

The object of this study was to investigate the renal component of hypertension in aortic constriction. In 40-day-old Sprague-Dawley rats the aorta were constricted either proximal (PAC) or distal (DAC) to the renal arteries. The rats were examined 3 weeks later together with control rats. The arterial pressure proximal to the constriction was elevated in the PAC group but not in the DAC group. In PAC rats the arterial pressure was also elevated distal to the constriction. There was a significant pressure gradient across the constriction in both PAC and DAC rats. The PAC rats had a significant decrease of renal blood flow, a significant increase in renal vascular resistance and a numerical but not significant decrease of glomerular filtration rate. Serum levels of angiotensin II were not significantly different in PAC and control rats. The pressor effect of a bolus dose of angiotensin II was significantly increased in PAC rats. Captopril, a converting enzyme inhibitor, decreased the arterial pressures and renal vascular resistance in PAC rats. The pressure elevating effects of angiotensin II and pressure lowering effect of captopril were more pronounced distal than proximal to the constriction. We conclude that the kidneys play a major role in the development of hypertension in PAC, and that the local effect of angiotensin II on the renal vascular bed is an important contributor to the renal component of the hypertension.
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PMID:Studies of the renal component of the hypertension in rats with aortic constriction. Role of angiotensin II. 352 26

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.
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PMID:The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay. 1573 61