levels, in response to precipitation of monosodium urate monohydrate crystals in various tissues, followed by an inflammatory response. The essence of the prevention and treatment of gout is antihyperuricemic therapy, either by uricosuric drugs or by xanthine oxidase (XOD) inhibitors. Allopurinol, an XOD inhibitor which is structurally related to xanthine, binds tightly to the active site of XO...

The widespread occurrence of antibodies (IgG) specific to xanthine oxidase in both normal (nonimmune) human and animal sera, and in antisera raised against a diversity of unrelated antigens is described. A study of sera from 81 humans revealed that xanthine oxidase-specific IgG represents a high proportion (1-8%) of total IgG. No obvious correlation to pathological events or symptoms of disease...

A new group of compounds analogous to the purines was recently described (1) in which carbon atom 2 of the purine ring was replaced by nitrogen. One of these imidazo-1 ,2,3-triazines (I), conveniently called 2-azaadenine, was shown to be an antagonist of hypoxanthine and of adenine in its toxic action against bacteria and mice. The corresponding hydroxy compound, 2-azahypoxanthine, was relative...

The numerous attempts to influence the development and growth of neoplasms by means of vitamins and other nutritional elements have been comprehensively summarized by other investigators (8, 9, 20). The experiment described here was stimulated by the observation that the dialyzed grouffd livers of cancerresistant mice (JK), exhibit a higher level of xanthine dehydrogenase activity than do the d...

BACKGROUND Endothelial dysfunction is linked to exaggerated production of superoxide anions. This study was conducted to examine the effects of oxidative stress on endothelial modulation of contractions in chronic two-kidney, one-clip (2K1C) renal hypertensive rats. METHODS The 2K1C hypertension was induced by clipping the left renal artery; age-matched rats receiving sham treatment served as...

Arterial hypertension is associated with increased levels of reactive oxygen species, which may scavenge endothelium-derived NO and thereby diminish its vasorelaxant effects. However, the quantitatively relevant source of reactive oxygen species is unclear. Thus, this potential pathomechanism is not yet pharmacologically targetable. Several enzymatic sources of reactive oxygen species have been...

Myocardial phospholipase D (PLD) is primarily localized at the sarcolemmal level and selectively hydrolyzes phosphatidylcholine to form phosphatidic acid as part of the signal transduction mechanisms for regulating Ca2+ movements in the heart. Since the myocardial cell damage induced by oxidative stress is associated with abnormalities in Ca2+ homeostasis and thiol status, we examined the thiol...

A plasmid containing a transcriptional fusion of the Escherichia coli katG promoter to a truncated Vibrio fischeri lux operon (luxCDABE) was constructed. An E. coli strain bearing this plasmid (strain DPD2511) exhibited low basal levels of luminescence, which increased up to 1,000-fold in the presence of hydrogen peroxide, organic peroxides, redox-cycling agents (methyl viologen and menadione),...

In this paper xanthine (C5H4N4O2 , MW=152) drug (M1) as a parent molecule and three of its dimethyl substituted isomers , namely, 3,7-dimethylxanthine (M2) 1,3-dimethylxanthine (M3) and 1,7-dimethylxanthine (M4) of formula (C7H8N4O2, MW = 180), were investigated using electron ionization (EI) mass spectrometry (MS) at 70 eV. Semi-empirical MO-calculations , PM3 procedure, have been carried out ...

The reduction of cytochrome c by xanthine oxidase and the competitive inhibition of this process by carbonic anhydrase and by myoglobin have been studied by kinetic and by equilibrium binding methods. Carbonic anhydrases isolated from bovine and from human erythrocytes differed strikingly in their ability to inhibit competitively the reduction of cytochrome c. The KS for cytochrome c was a func...