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Chain Reaction Study (chain + reaction_study)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Functional and molecular evidence of adenosine A2A receptor in coronary arteriolar dilation to adenosine

DRUG DEVELOPMENT RESEARCH, Issue 1-2 2001
Lih Kuo
Abstract Adenosine is a potent vasodilator implicated in the regulation of coronary microvascular diameter during metabolic stress. However, the specific adenosine receptors and underlying mechanism responsible for the dilation of coronary microvessels to adenosine remains to be elucidated. Thus, pig subepicardial coronary arterioles (<100 ,m) were isolated, cannulated, and pressurized without flow for in vitro study. All vessels developed basal tone and dilated concentration-dependently to adenosine. Disruption of endothelium and inhibition of nitric oxide (NO) synthase by L-NAME produced identical attenuation of adenosine-induced dilation. KATP channel inhibitor glibenclamide further reduced the dilation of denuded vessels. cAMP antagonist Rp-8-Br-cAMP blocked vasodilation to forskolin, but failed to inhibit vasodilation to adenosine. Coronary dilation to adenosine was blocked by a selective adenosine A2A receptor antagonist ZM241385, but was not altered by an A1 receptor antagonist, DPCPX. Reverse transcription-polymerase chain reaction study revealed that A2A receptor mRNA was expressed in microvessels but not in cardiac myocytes; A1 receptor expression was observed only in cardiac myocytes. These results suggest that adenosine-induced dilation of coronary arterioles is mediated predominantly by A2A receptors. Activation of these receptors elicits vasodilation by endothelial release of NO and by smooth muscle opening of KATP channels in a cAMP-independent manner. Drug Dev. Res. 52:350,356, 2001. © 2001 Wiley-Liss, Inc. [source]

Phosphorylation of retinoblastoma protein in rat brain after transient middle cerebral artery occlusion

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2000
T. Hayashi
Although mature neurones do not replicate genomic DNA, some cell cycle-related kinases are aberrantly activated in neurones after ischaemia. As hyper-phosphorylation of retinoblastoma (Rb) protein is the common pathway in mitotic signal cascade, this study investigated the phosphorylation state of the Rb protein as well as its mRNA level in rat brain after transient middle cerebral artery (MCA) occlusion. Immunohisto-chemical analysis revealed that neurones in the sham-operated brain expressed Rb protein without the hyperphosphorylated form. Immunoreactivity for the hyperphosphorylated form of Rb protein progressively increased from 1 h to 3 days after ischaemia in neurones in the MCA territory. Western blot analysis demonstrated a similar change. However, reverse transcription-polymerase chain reaction study revealed that Rb showed no definite change at the mRNA level. These results suggest that Rb protein is progressively hyper-phosphorylated in the brain after ischaemia, which may activate apoptotic mechanisms in neuronal cells of the brain after ischaemia. [source]

Ziehl-Neelsen staining and polymerase chain reaction study of tissue from tuberculous granulomas

RESPIROLOGY, Issue 4 2003
Ali MERT
No abstract is available for this article. [source]

Human sebocytes express prostaglandin E2 receptors EP2 and EP4 but treatment with prostaglandin E2 does not affect testosterone production

BRITISH JOURNAL OF DERMATOLOGY, Issue 3 2009
W. Chen
Summary Background, Prostaglandins (PG) play an important role in cutaneous homeostasis. Among other skin cells, human sebocytes express cyclooxygenases and can produce PGE2. Various prostanoid receptors have been demonstrated in epidermis and hair follicles, while limited data are available regarding their expression in sebaceous glands. In addition, the interaction between PGE2 and androgenesis remains largely unclear. Objectives, To examine the expression of PGE2 receptor (EP) and PGF2, receptor (FP) in human sebocytes and the influence of PGE2 or PGF2, on testosterone production. Methods, A reverse transcription-polymerase chain reaction study was used to detect the expression of EP subtypes and FP. A testosterone radioimmunoassay was used to measure the amount of testosterone in the supernatant of cultured SZ95 sebocytes treated with PGE2 or PGF2, alone or in the presence of various androgen precursor substrates. Results, SZ95 sebocytes expressed mainly EP2 and EP4 but not EP3 or FP. Testosterone production was not induced by PGE2 or PGF2,, alone or in the presence of cholesterol. PGE2 did not affect androgenesis in cultured sebocytes. Conclusions, The expression patterns of prostanoid receptors differ between sebocytes, hair follicles and epidermis. The effects of PGE2 and PGF2, on the proliferation, lipogenesis and inflammation of sebocytes appear not to be associated with androgenesis. [source]