Melatonin-induced suppression of the pinealectomy-stimulated rat adrenal cortex mitotic activity

Pineal involvement in the regulation of adrenocortical mitotic activity has recently been suggested. It has been shown that melatonin (Mel) decreased the mean mitotic activity rate (MMAR) of the adrenal cortex both in vivo and in organ culture. The goal of the present study was to test the influence of pinealectomy (PX) and/or Mel-treatment on the MMAR of adrenocortical cells, as well as on the adrenal weight in rats. The stathmokinetic method was used in the study. It was found that PX significantly increased the MMAR of the adrenocortical cells. Moreover, Mel suppressed the proliferogenic effect of PX on the rat adrenocortical cells. Melatonin alone did not significantly affect the mitotic activity of the adrenal cortex. None of the three experimental procedures, i.e. Mel, PX and Mel-treatment of pinealectomized animals significantly affected the adrenal weight. The present data suggest that Mel may be involved in the inhibitory control of adrenocortical cell proliferation.     

The fate of young individuals with a history of myocardial infarction]

The fate of young individuals (to 45 years) with a history of myocardial infarction during 12 years was analysed with the aid of a questionnaire containing questions of both social and medical character. Sudden cardiac death or the second infarction were the most frequent causes of death during the first two years following myocardial infarction. Change in the physical activity mainly involved the return to work. Only 47% of young men and 29.8% of women started full-time jobs. They mainly belonged to so-called white collars. The lack of patients' physicians permission was a main cause of the abstinence of young men from the occupation. A position within the family and social activity usually remained unchanged in the majority of patients, but every third patient greatly reduced sexual activity. Every third patients continued smoking, and did not observe recommended diet despite the systematical medical check-ups. The course of the disease is unclear in the majority of young patients. It is often deformed and requires further, detailed information on young patients' style of life.     

The possibility of replacing blood serum with sputum for monitoring of therapy with lithium carbonate]

Lithium concentration was determined in both sputum and blood serum of 31 patients treated with lithium carbonate. It was found that lithium concentration rate in the sputum/blood serum is 2.17 +/- 0.16, and is constant in all patients, except one, for a long time. A high correlation index between lithium concentration in the sputum and blood serum (r = 0.9025, and without two assays in the above mentioned patient r = 0.9858) as well as stability of sputum/serum lithium levels enable -- in the opinion of the authors -- to control lithium concentration in the body, using sputum for the assays. These assays are easy to perform with the aid of the kit called "Salivette" (Sarstedt, Germany). Its principle was discussed, too.     

The effect of Lead on early stages ofPhaseolus vulgaris L. growthin vitro conditions

Lead chloride (10^-5 M) inhibited the growth of the main root, the duration of development, the number and growth of lateral roots, primary and trifoliate leaves, and also the mitotic index in root apical meristems. Lead strongly inhibited root growth rate, mainly by reducing the number of dividing cells. Other mechanisms of this inhibition are discussed.     

Neutrophils-induced increase of adenosine triphosphate depletion in rat neonatal cardiac myocytes with impaired energy metabolism.

Isolated, cultured rat neonatal cardiac myocytes were placed in medium supplemented with mitochondrial respiratory inhibitor potassium cyanide which caused a rapid adenosine triphosphate (ATP) depletion. These myocytes with the impaired energy metabolism ("hypoxia-like state") were exposed to unstimulated human neutrophils. Effect of human neutrophils on the myocytes in the "hypoxia-like state" was quantified as a total change in the amount of ATP in cardiac cells. After 5 hours of incubation of neutrophils with the myocytes in the "hypoxia-like state" an additional decrease (of 50 per cent) in ATP content was observed. Since catalase (which destroys hydrogen peroxide) prevented the further decline in ATP level in the myocytes with impaired energy metabolism, it seem that hydrogen peroxide and possibly their products are responsible for this effect. These results suggest that unstimulated human neutrophils after activation by the contact with injured cardiac cells caused further decrease of ATP level in target cells.     

Whole blood superoxide anion generation and efficiency of some erythrocyte antioxidant systems during recombinant human erythropoietin therapy of uremic anemia

Six chronic uremic patients on regular hemodialysis treatment were given recombinant human erythropoietin (r-huEPO) in a dose of 50 U/kg of body weight intravenously thrice weekly for 14 weeks. Following r-huEPO therapy, unstimulated whole blood superoxide anion ( ₂) generation did not change significantly, while opsonized zymosan-stimulated whole blood ₂ generation increased. At the same time, erythrocyte superoxide dismutase and, in particular, glutathione peroxidase activities were found to be reducing with concomitant lowering of erythrocyte malonydialdehyde (MDA) concentrations and increase in plasma MDA concentrations.     

Preliminary studies on the mechanisms of action of phosphonic analogues of morphactins on plants and bacteria

Two classes of phosphonopeptides, those containing P-terminal 9-aminofluoren-9-ylphos-phonic acid and those of dialkyl 9-aminofluoren-9-ylphosphine oxides, influence plant growth according to different mechanisms. The effect of these compounds on the growth of several bacterial species, including the photosynthetic bacteriumRhodospirillum rubrum, as well as on the activity of photosystems 1 and 2 in isolatedPisum sativum andSpirodela oligorrhiza chloroplasts was studied. The peptides of free, unblocked 9-aminofluoren-9-ylphosphonic acid acted in a morphactin-like manner, whereas those of dialkyl 9-aminofluoren-9-ylphosphine oxides influenced photosynthesis indirectly.     

Involvement of a single thiol group in the conversion of the NAD+-dependent activity of rat liver xanthine oxidoreductase to the O2-dependent activity.

The effects of 2-iodosobenzoic acid, 4-chloromercuribenzoate, 5,5'-dithiobis-(2-nitrobenzoic acid) and tetraethylthioperoxydicarbonic diamide (disulphiram) on the NAD+-dependent activity of xanthine oxidoreductase from rat liver were investigated. Only disulphiram converted the NAD+-dependent activity into the O2-dependent activity quantitatively, without changing the xanthine hydroxylation rate. The modification process was a first-order reaction with respect to time (min) and disulphiram concentration (microM). The kinetic data showed that modification of single thiol group is sufficient for loss of the enzymic activity towards NAD+ as electron acceptor. The complete protection afforded by NAD+ against the action of disulphiram suggests that the essential thiol group may be involved in binding of NAD+ to the xanthine oxidoreductase molecule.     

Studies of the orientation of the mitochondrial redox carriers. III. Orientation of the gx and gy axes of the hemes of cytochrome oxidase with respect to the plane of the membrane in oriented membrane multilayers.

The EPR absorption properties of the hemes of cytochrome oxidase and their liganded derivatives were examined in oriented multilayers from isolated oxidase, mitochondrial membranes and membrane fragments of a bacterium, Paracoccus denitrificans. The hemes of the oxidase in all the systems investigated were oriented normal to the plane of the multilayers. The directions of the g signals corresponding to the gx and gy axes of the g tensor were found to be different in low-spin ferric heme in fully oxidized oxidase and in half-reduced liganded oxidase. It is suggested that this different orientation of gx and gy in fully oxidized oxidase and half-reduced liganded oxidase arises because the respective EPR signals belong to two different hemes, those of cytochrome a and a3.