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H U Lee

Publications and source records attributed to H U Lee.

5 recordsLinked to original sources
PubMed2001

Effects of heme oxygenase system on the cyclooxygenase in the primary cultured hypothalamic cells.

Endogenous carbon monoxide (CO) shares with nitric oxide (NO) a role as a putative neural messenger in the brain. Both gases are believed to modulate CNS function via an increase in cytoplasmic cGMP concentrations secondary to the activation of soluble guanylate cyclase (sGC). Recently CO and NO were proposed as a possible mediator of febrile response in hypothalamus. NO has been reported to activate both the constitutive and inducible isoform of the cyclooxygenase (COX). Thus, we investigated whether CO arising from heme catabolism by heme oxygenase (HO) is involved in the febrile response via the activation of COX in the hypothalamus. PGE2 which is a final mediator of febrile response released from primary cultured hypothalamic cells was taken as a marker of COX activity. PGE2 concentration was measured with EIA kits. Exogenous CO (CO-saturated medium) and hemin (a substrate and potent inducer of HO) evoked an increase in PGE2 release from hypothalamic cells, and these effects were blocked by methylene blue (an inhibitor of sGC). And membrane permeable cGMP analogue, dibutyryl-cGMP elicited significant increases in PGE2 release. These results suggest that there may be a functional link between HO and COX enzymatic activities. The gaseous product of hemin through the HO pathway, CO, might play a role through the modulation of the COX activity in the hypothalamus.

Animals↗
PubMed1987

Developmental expression of the angiotensinogen gene in rat embryos.

Angiotensin II is a potent octapeptide vasoconstrictor and regulator of cardiovascular and electrolyte homeostasis. Angiotensinogen, the protein precursor of angiotensin II, is synthesized by the liver and many other organs of the adult rat. To determine whether angiotensin may be present in early fetal development we analyzed rat embryonic tissues (chorionic membranes, head, and body) for the expression of the angiotensinogen gene during days 11-21 of embryogenesis. Angiotensinogen mRNA was detected at low levels in embryo bodies and yolk sac placenta from day 11 of gestation. An initial rise in the level was noted on day 13, reaching a plateau from day 17 of gestation to birth. Angiotensinogen mRNA levels of the embryonic head were about 10-fold less than those of the body on days 17-19 and increased to levels similar to those of the body on days 20-21. Angiotensinogen mRNA levels of the yolk sac placenta were about 20-fold higher than those in the embryonic body, but no angiotensinogen mRNA was detected in the chorioallantoic placenta. Angiotensinogen mRNA from both embryos and yolk sac placenta was larger by about 200 bases than the mRNA obtained from adult rat liver; this was shown to be a consequence of both the utilization of more distal polyadenylation sites and a longer poly(A) tract. These observations suggest the possibility of a biological function for angiotensinogen in the early development of the rat, and that polyadenylation site selection may alter the functional expression of the angiotensinogen gene in a developmentally specific manner.

Angiotensinogen↗
PubMed1984

Expression of myoblast and myocyte antigens in relation to differentiation and the cell cycle.

Cell cycle parameters and expression of myoblast and myocyte antigens were investigated during exponential growth and during the differentiation phase of rat L8( E63 ) myoblasts by an integrated approach involving microspectrophotometry with DNA fluorochromes, [3H]thymidine autoradiography, and immunofluorescent staining with monoclonal antibodies. In addition to the majority of cells which are recruited into myotubes, two distinct populations of mononucleate cells were resolved in cultures of rat myoblasts undergoing differentiation. These mononucleate cells consist of (1) a population of proliferating cells with a prolonged G1 transit time; (2) a population of non-proliferating cells which remain arrested in G1 for more than 72 h. The latter group was examined with respect to the expression of two marker antigens recognized by two monoclonal antibodies: antibody B58 reacts with a macromolecular component present in undifferentiated myoblasts but not in mature myotubes, and antibody XMlb reacts with a muscle-specific isoform of myosin. All four possible combinations of expression of these antigens by single cells were found: B58 +XM1b -, B58 +XM1b +, B58 - XM1b -, and B58 - XMlb +. The implication of these findings with respect to the transition from the proliferative to the differentiative phase of myogenesis is discussed.

Animals↗