The effect of melanin on the bystander effect in human keratinocytes

The influence of melanin on radiation-induced bystander effects has been studied. Melanin is known to be a natural substance with proved radioprotective properties in different organisms and cell lines. It is non-toxic and is effective against acute and chronic irradiation. The lower the radiation dose, the higher the relative impact of melanin protection. In this study influence of melanin on human keratinocytes (HPV-G cells) has been studied using the colony-forming assay. We have shown that bystander donor medium from 0.5 Gy irradiated cells when transferred to unirradiated cells, caused almost the same effect as direct irradiation. Melanin increased the colony-forming ability of bystander recipient cells when it was added into culture medium before irradiation. The effect of melanin added after irradiation was to produce less protection in both the directly irradiated and bystander medium treated groups. The absorption spectrum of the filtered medium is identical to one of the intact culture medium showing that melanin was not present in filtered medium. Thus, it cannot protect recipient cells but reduces the amount of the bystander effect. It is concluded that melanin added before irradiation effectively decreased the radiation dose. The reduction of the impact of the bystander signal on recipient cells when melanin was added to the donor medium after harvest but before filtration, may mean that the bystander signal has a physical component as melanin can absorb all types of physical energy.     

The effect of fulvic acid on the dose effect of selenite on the growth of wheat

The effect of fulvic acid on the dose effect of selenite has been studied by using the hydroponics culture of wheat in the presence of selenite and fulvic acid (FA). The bioavailability of Se was investigated by 5 morphological end points and 12 biological and biochemical end points at different phases of growth of wheat seedling and seed germination. The “platform” of the dose effect observed indicates that the presence of FA can have both the beneficial effects and antagonists on the toxicity of Se to a certain extent.     

Modulatory effect of diclofenac on antispasmodic effect of pitofenone in cholinergic spasm

Biliary, ureteric and intestinal colic are extremely common clinical conditions associated with smooth muscle spasm. In the present study, antispasmodic activity was carried out against acetylcholine (10-640 ng/ml)-induced contractions on guinea pig ileum. Acetylcholine (10-640 ng/ml) induced concentration-dependent contraction of smooth muscle. Diclofenac, in varying concentration (9.4 x 10(-5) mol/l and 14.1 x 10(-5) mol/l) shifted the concentration response curve of acetylcholine to the right without suppressing the maximal response. However, in higher concentration diclofenac (18.9 x 10(-5) mol/l) blocked the response in an unsurmountable fashion. Further, analgin (11.09 x 10(-5), 16.63 x 10(-5) and 22.18 x 10(-5) mol/l) in equimolar concentrations did not alter the concentration response curve of acetylcholine, but in higher concentration analgin (44.36 x 10(-5) mol/l) also blocked the response in an unsurmountable fashion. Pitofenone (2.5 x 10(-6) mol/l) also, shifted the concentration response curve of acetylcholine to right in a parallel fashion with no change in maximal response. The present study confirms the potent antispasmodic activity of diclofenac-pitofenone combination in comparison to analgin-pitofenone in molar equivalent concentration (in comparison to diclofenac) against acetylcholine-induced contractions of guinea pig ileum.     

Hybridity effect on mortality

Abstract

Several techniques for preselecting the sex of offspring are available now or will be in the near future. Although hundreds of studies indicate that sons are desired by the overwhelming proportion of persons asked, few studies ask whether preselecting of sex of offspring ought to be made available generally, as the technologies become perfected. In northern California, 2,138 respondents indicated widespread acceptance of ongoing biomedical research to perfect preselection methods and of making these procedures available to potential parents. Almost half agreed that they might want to use such techniques. Variation in levels of agreement were assessed by sex, race, marital status, child‐parity, religious affiliation and attendance, level of education, class, and general attitudes toward medical and scientific leaders. The implications of the general acceptability of sex selection go far beyond the freedom of parental choice—to such matters as socialization patterns of first son, second daughter ordering, sex role inflexibilities, sex ratio imbalances, and also include possibilities for curtailing rapid population growth.     

Fungicide effect of Triton-N on Phlyctidium

Summary Triton-N surfactants can combat algal parasites Phlyctidium scenedesmi (Fott) and Phlyctidium sp. Triton N-57 inhibits temporarily the growth of Scenedesmus acutus Meyen and Scenedesmus acuminatus (Lagerh./Shod.) and later stimulates it. This surfactant can be used in producing healthy inoculum as a starting material for mass algal cultures. A medium formulation was developed for maintenance of parasites in laboratory.     

Growth-inhibitory effect of hemin on staphylococci

The antibacterial activity of hemin onStaphylococcus aureus is described. Hemin binding to bacteria was a rapid process, and each cell accumulated 5×10⁵ to 1×10⁶ molecules within 5 min. Bacterial growth was stopped completely after 30 min from addition of low concentration of hemin (3–10 g/ml). Cell viability was reduced by 99.9% in 1 h of exposure, and the effect was consistent at any stage of the growth curve whenever hemin was added. Glucose utilization was arrested immediately after hemin addition, and no CO₂ was produced. The survivors of hemin treatment regrow in a time-related kinetics depending on the dose of hemin to which the cells were exposed. The recovered bacteria were again sensitive to hemin, similar to an untreated culture. We suggested that the recovery phenomenon is a result of an on-off mechanism regulating sensitivity to hemin, rather than a selection mechanism giving rise to hemin-resistant mutants.