The present paper describes a new enzyme from animal tissues which catalyzes the keto-enol tautomeriaation of the phenylpyruvic acids. Preliminary accounts of this tautomerase have been published (1, 2). The enzyme has not yet proved to be essential in any biological reaction, but a physiological role may be expected since specific tautomers of a-keto acids are substrates or products in some re...

The purpose of this study was to elucidate the mechanism by which acetylcholine (ACh) promotes prostacyclin (PGI2) production in cultured coronary endothelial cells (CEC) of the rabbit heart. ACh-induced production of PGI2, measured as immunoreactive 6-keto-PGF1alpha, was enhanced by increasing the extracellular calcium (Ca++) concentration and reduced by Ca++ depletion. The receptor-operated C...

An efficient catalytic synthesis of α-amino-β-keto esters has been newly developed. Cross-coupling of various aldehydes with α-imino ester, catalyzed by N-heterocyclic carbene, leads chemoselectively to α-amino-β-keto esters in moderate to good yields with high atom efficiency. The reaction mechanism is discussed, and it is proposed that the α-amino-β-keto esters are formed under thermodynamic ...

The behavior of hydroxypyruvic acid, CHzOH. CO. COOH, and some of its transformation products toward periodic acid, treated in detail in the preceding paper (I), suggested an orienting study of the action of this oxidant on glyoxylic acid, CHO. COOH, and other a-keto acids or on compounds giving rise to such keto acids, following oxidation by periodate. While cr-glycols, a-ketols, a-diketones, ...

The specific mechanisms by which skin blood flow increases in response to a rise in core body temperature via cutaneous active vasodilation are poorly understood. The primary purpose of this study was to determine whether the cyclooxygenase (COX) pathway contributes to active vasodilation during whole body heat stress (protocol 1; n = 9). A secondary goal was to verify that the COX pathway does...

Gestational choriocarcinoma metastasizes rapidly, in which process the vasoactive prostanoids may be significant. We therefore compared the urinary excretion of prostacyclin and thromboxane A2 (TxA2) metabolites in 19 women with gestational choriocarcinoma and 20 healthy age-matched women by assessing spot urine samples for 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and 2,3-dinor-6-keto-...

The peripheral plasma content of the pulmonary metabolite, 13,14-dihydro-15-keto-prostaglandin E2, reflects prostaglandin E2 (PGE2) biosynthesis and disposition in vivo more reliably than the peripheral plasma content of PGE2 itself. However, the chemical instability of 13,14-dihydro-15-keto-PGE2 and the multiple fates of its degradation products hinder the development of quantitative assays fo...

Concentrations of prostaglandins E, F, and 6-keto-prostaglandin F1 alpha were estimated in central venous blood and amniotic fluid in 21 women with eclampsia and 16 healthy pregnant controls. Central venous blood concentrations of 6-keto-prostaglandin F1 alpha and prostaglandin E were significantly lower in patients than controls before delivery and remained reduced for at least 48 hours after ...

In continuation of our study on Cotinus coggygria from Serbia, 10 known flavonoids (1-10) were isolated the methylene chloride/methanol extract heartwood. They tested for in vitro protective effect against chromosome aberrations peripheral human lymphocytes, using cytokinesis-block micronucleus assay. All compounds (in minimal doses 1 μg/mL) exerted a beneficial by decreasing DNA damage lymphoc...