Effects of ACTH and diabetes on phospholipid metabolism in adrenal mitochondria.

Incorporation of 32P into adrenal mitochondrial phospholipids (PL) incrased in ACTH-treated rats, but it decreased in diabetics, inspite of the fact that these animals showed adrenal overacity. Since diabetics did not show increased 11 beta-hydroxylation. as opposed to ACTH-treated rats, it is suggested that the stimulation of this enzyme activity by exogenous ACTH is related to an increased turnover of PL at the mitochondrial membrane. The process is impaired in diabetics and prevents the stimulation of 11 beta-hydroxylation.     

A facile one-step synthesis of cysteinyldopas using mushroom tyrosinase

Summary A convenient one-step procedure, based upon the tyrosinase co-oxidation of dopa and cysteine, is reported for the synthesis of 5-S-cysteinyldopa (I) in 74% yield. Secondary products of the reaction turned out to be 2-S-cysteinyldopa (II, 14%), 2,5-S, S-dicysteinyldopa (IV, 5%), and the hitherto unknown 6-S-cysteinyldopa (III, 1%).The generic term cysteinyldopa is proposed to designate the various cotechol amino-acids arising from addition of cysteine to dopaquinone.This work was supported in part by a grant from Consiglio Nazionale delle Ricerche, Roma.     

N-(5′-Phosphopyridoxyl)-4-aminobutyric acid: a stable bisubstrate adduct inhibitor of rat brain 4-aminobutyric acid aminotransferase

Summary N-(5-Phosphopyridoxyl)-4-aminobutyric acid, a stable adduct of pyridoxal phosphate and 4-aminobutyric acid, has been shown to be a potent inhibitor of rat brain 4-aminobutyric acid aminotransferase (GABA-T) with a K_i of 1.4 M.Acknowledgments. This work was supported in part by the United Parkinson Foundation, l'Association Canadienne l'Ataxie de Friedreich, and the Medical Research Council of Canada.     

Hydrogen peroxide generation inTrypanosoma cruzi

Summary Homogenates from T. cruzi epimastigotes produced 3.4 pmoles H₂O₂/min 10⁶ cells, as detected by the cytochrome c peroxidase assay. Addition of NADH or NADPH increased H₂O₂ production by a factor of 3 and 5, respectively. When supplemented with NADH and NADPH, the mitochondrial, microsomal, and supernatant fractions produced H₂O₂, the soluble fraction and the mitochondrial membranes being apparently the main generators of H₂O₂. The epimastigote homogenates showed cyanide-sensitive superoxide dismutase activity, equivalent to 0.28 g bovine superoxide dismutase per mg homogenate protein.This investigation was supported by grants from Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET) Argentina and the Scientific Office, American States Organization.Career Investigator of CONICET.     

A tissue-selective prostaglandin E2 analog with potent antifertility effects

Summary N-methanesulfonyl 16-phenoxy--tetranor PGE₂ is a prostaglandin analog which is markedly more tissue selective than PGE₂. This compound is 10–30 times more potent than PGE₂ in animal models which are considered relevant to antifertility effects in humans. In pharmacological tests which are believed to be predictive for side effects in humans, the compound has potency either equal to or less than that of PGE₂.     

Effects of cerebral lateral,ventricular infusions of phloridzin on feeding and body weight in Gallus domesticus (L.)

Summary Contrary to earlier findings in rats, cerebral lateral ventricular infusions of 1×10^–3 M or 2×10^–3 M solutions of phloridzin at a rate of 2.5 l/min for 90 min had no significant stimulating effects on food intake and weight gain in hens and cocks. These different responses to intraventricular phloridzin might reflect a difference of sensitivity to the inhibitory action of phloridzin on glucose transport in cerebral cells or certain peculiarities of mechanisms controlling food intake in chickens.     

Pulsating aurora induced by upper atmospheric barium releases

An effect which appeared to be pulsating aurora was observed to be associated with explosive releases of barium vapour near 250 km altitude, but only when the explosions were in the path of precipitating electrons associated with the visible aurora.     

Seed germination in response to diurnal fluctuations of temperature

Diurnal fluctuations in temperature may initiate or accelerate germination in certain flowering plants, and the effectiveness of the stimulus varies according to the amplitude of fluctuation and the presence or absence of light. Attempts to assess the adaptive significance of the phenomenon, however, have been limited by the scarcity of data for species of contrasted ecology. We report here an investigation of germination responses to fluctuating temperatures, conducted on seeds of herbaceous species collected from native populations near Sheffield. The results suggest that requirements for diurnal fluctuations in temperature are characteristic of the germination of species from particular types of habitat and provide mechanisms which cause seeds to germinate at times and in places favourable for seedling establishment.