[The genetic polymorphism of the dioeciousness trait in the fodder beet]. / Geneticheskii polimorfizm priznaka razdel'notsvetkovosti u kormovoi svekly.

The data on the study of genetics of the monofloret-cluster trait in fodder beet were presented. Three alleles of monofloret mc4, mc5 and mc6 were selected and described. Available monofloret sources of fertile fodder beet was tested on allelism.

The role of retinal pigment epithelium melanin in photoinduced oxidation of ascorbate.

To determine the role of major chromophores of the human retinal pigment epithelium (RPE) in photooxidation of ascorbate, we monitored spectrophotometrically rates of ascorbate depletion, induced by blue light, in suspensions of human RPE melanin, melanolipofuscin and lipofuscin and in preparation of pigmented and nonpigmented bovine RPE cells. The results clearly show that melanin is the key retinal pigment responsible for the photosensitized oxidation of exogenous ascorbate. To elucidate the mechanism of the photooxidation process, we used purified RPE melanin granules and synthetic dopa (dihydroxyphenylalanine) melanin and employed electron spin resonance (ESR) spectroscopy, ESR oximetry and oxidase electrode. Our data indicate that photoinduced melanin radicals oxidize ascorbate via one-electron transfer reaction. The reduced melanin is reoxidized by molecular oxygen with the formation of superoxide anion and hydrogen peroxide, while the ascorbate radicals decay by disproportionation. Because in the absence of oxygen, no measurable oxidation of ascorbate is observed, it can be concluded that melanin acts as an electron transfer agent. Biological implications of this study remain unclear; however, the formation of oxygen-reactive species that accompany melanin-mediated photooxidation of ascorbate may represent a potential risk to the RPE that should be minimized by yet unknown cellular mechanisms.

The effect of a synthetic neuromelanin on yield of free hydroxyl radicals generated in model systems.

Neuromelanin is an amorphous pigment of the catecholamine origin that accumulates in certain dopaminergic neurons of the substantia nigra of human brain. In Parkinson's disease, there appears to be selective degeneration of the most heavily pigmented neurons of the substantia nigra, and this process has been linked to the presence of neuromelanin. It has been postulated that neuromelanin could increase the risk of oxidative stress reactions. On the other hand, melanin is usually considered to be an efficient antioxidant. Here we analyze experimental conditions that stimulate, or inhibit, antioxidant properties of neuromelanin. Using electron spin resonance (ESR)--spin trapping technique and salicylate hydroxylation assay, we monitored the formation of free hydroxyl radicals generated by a Fenton system in the presence of varying concentration of dopamine-melanin, a synthetic model for neuromelanin. Our data clearly indicate that the antioxidant action of neuromelanin is predominantly due to its ability to sequester redox-active metal ions such as iron. Using direct ESR spectroscopy, we have shown that ferric complexes with neuromelanin are resistant to reduction by mild biological reductants such as ascorbate. We have demonstrated that dopamine-melanin saturated with ferric ions, could enhance the formation of free hydroxyl radicals by redox activation of the ions. Thus, under the conditions that stimulate the release of accumulated metal ions, neuromelanin may actually become an efficient prooxidant. It is conceivable that neuromelanin, which normally is able to protect pigmented dopaminergic neurons against metal-ion related toxicity, could under extreme conditions have a cytotoxic role.

[Some causes of ectopic pregnancy in the aspect of clinical and anatomo-pathological studies]. / Niektóre przyczyny ciazy pozamacicznej na podstawie badan klinicznych i anatomopatologicznych

PIP: 9.98% of all gynecological surgical interventions made at the Clinic in Zabrez from 1965 to 1971 were for ectopic pregnancy. 157 cases of ectopic pregnancy were chosen at random for clinical analysis. Microscopic examinations of the excised oviduct were made in order to establish the cause of tubular implantation. The cause was determined in 45.6% of all the cases. Causal factors were chronic salpingitis (33%), endometriosis (11.4%), and tuberculosis (1.2%). In the formation of acute salpingitis (54.4% of these cases) a major incidence of passed spontaneous and artificial abortion was revealed. It is felt that postoperative examination of material should cover not only the presence of the fetal ovum but also the microscopic appearance of the oviducts' walls. In this manner it is thought that the cause may become more evident, making prophylaxis of ectopic pregnancy more possible.^ieng