Influence of phosphate ion on the fluorescence of 3-fluorotyrosine

Summary 3-Fluorotyrosine fluorescence is quenched effectively by phosphate ions not only by a dynamic but also by a static mechanism owing to H-bond complex formation in ground state. 3-Fluorotyrosine pK_a values both in the ground and first excited state (8.3 and 4, respectively) are appreciably lower than those of tyrosine, thus promoting 3-fluorotyrosinate ion formation in the excited state. Additional emission owing to 3-fluorotyrosinate ion (near 350 nm) may be taken erroneously for tryptophan fluorescence.     

Ultrastructure of blood cells in children exposed to radiation in utero and resided in radionuclide contaminated zones

The electron-microscopic examinations of lymphocytes and neutrophiles in circulating blood of children irradiated during intrauterine development and on posterior stages of ontogenesis were performed in dynamics after accidental period. Some changes in lymphocyte ultrastructure were revealed; namely the increased undulation of nuclear contours with dilated perinuclear space and some reconstructions of their cellular organoids (the increased density of mitochondrial matrix, crist disorganization, dilation of clear space in cisterns of cytoplasmic net, disorders in the structure of electron-dense granules). The peculiarities of neutrophile ultrastructure that are characterized by centre dilated perinuclear space, decrease in glycosomes, disorders in granular structure, vacuole presence, degradation of cytoplasm and nuclear hypersegmentation were determined.     

Functional profiles typical of the male and female residents in different climatic-geographical areas of Magadan region

Residents of the Extreme North, in total 255 males and 72 females were examined to study morpho-fuctional changes occurring in dependence on the area of residence. It was found that the subjects who recide in the towns of Magadan and Susuman demonstrated adaptive changes in somatometric parameters as well as in functioning of the body cardio-respiratory and gas-transporting systems that can be considered as a compensatory response providing the body energy balance and homeostasis maintenance at the level the unfavourable environmental factors.     

Effect of beta-adrenoreceptor blockade on cell division processes in the corneal and tongue epithelium of white rats with chronic oxygen starvation

A study was made of the changes in the mitotic activity, DNA synthesis, and the number of pathological mitoses after administration of the beta-adrenoblocker propranolol in the corneal and tongue epithelium of white rats kept in pressure chamber for 7 days (4 h daily) at a "height" of 9000 meters. The mitotic and the label indices (inclusion of 3H-thymidine by the epithelium nuclei) were analysed for mitotic activity and DNA synthesis, respectively. The experiments showed that the mitotic activity, DNA synthesis, the number of pathological mitoses were stabilized due to the propranolol administration.     

Some electrophysiological and hemodynamic characteristics of auditory selective attention in norm and schizophrenia

Six patients in the state of remission after the first episode ofjuvenile schizophrenia and seven sex- and age-matched mentally healthy subjects were examined by fMRI and ERP methods. The auditory oddball paradigm was applied. Differences in P300 parameters didn't reach the level of significance, however, a significantly higher hemodynamic response to target stimuli was found in patients bilaterally in the supramarginal gyrus and in the right medial frontal gyrus, which points to pathology of these brain areas in supporting of auditory selective attention.     

Enhanced chemiluminescence: A sensitive analytical system for detection of sweet potato peroxidase

3-(10'-Phenothiazinyl)propane-1-sulfonate (SPTZ) was shown to be a potent enhancer of anionic sweet potato peroxidase (aSPP)-induced chemiluminescence. The optimal conditions for aSPP-catalyzed oxidation of luminol were investigated by varying the concentrations of luminol, hydrogen peroxide, Tris, and SPTZ as well as the pH values of the reaction mixture. Addition of 4-morpholinopyridine (MORP) to the reaction mixture markedly increased the light intensity. Using SPTZ and MORP together enhanced the effect 265 times. The lower detection limit (LDL) of SPP was 0.09 pM, approximately in 10 times lower than that for the cationic isozyme c of horseradish peroxidase/4-iodophenol system. It was shown that aSPP in the presence of SPTZ produced a longer lasting chemiluminescent signal.     

3-(10′-Phenothiazinyl)propane-1-sulfonate is a potent enhancer of soybean peroxidase-induced chemiluminescence

3-(10′-Phenothiazinyl)propane-1-sulfonate (SPTZ) was shown to be a potent enhancer of soybean peroxidase (SbP)-induced chemiluminescence. To the best of our knowledge, SPTZ is the first enhancer of SbP to be discovered. Optimal conditions for SbP-catalyzed oxidation of luminol in the presence of SPTZ were determined. The SbP-SPTZ system showed better sensitivity and a lower detection limit (LDL) with respect to the horseradish peroxidase-4-iodophenol system traditionally used in chemiluminescent enzyme-linked immunosorbent assay (ELISA). The addition of 4-morpholinopyridine (MORP) to the SbP-SPTZ system improved its analytical parameters by decreasing the LDL of SbP to 0.03 pM. These results open up very promising perspectives for using the SbP-SPTZ-MORP system in ultrasensitive immunoassay.     

Long-term cytogenetic effects in children prenatally-exposed to radiation as a result of the accident at the Chernobyl Atomic Energy Station

Forty-two children exposed to ionizing radiation in prenatal period and 15 children of control group were examined in the remote terms after the accident using the method of differential G-staining of chromosomes in lymphocytes of peripheral blood. It was found that the average group rate of aberrant cells and chromosome aberrations was reliably higher in the children exposed in utero compared to control. Long-term cytogenetic consequences of the pre-natal exposure were characterized by prevalence of aberrations of a chromosome type, mainly stable chromosome lesions. At chronic exposure to low doses of ionizing radiation the increase in the rate both stable and unstable chromosome aberrations.     

Phenothiazine derivatives as enhancers of peroxidase-dependent chemiluminescence

Some N-alkyl phenothiazines with different ionic groups were studied as enhancers of chemiluminescence catalyzed by soybean peroxidase. It was shown that under experimental conditions, the compounds with positively charged groups do not exhibit enhancing ability, while the addition of phenothiazines with negatively charged groups to a substrate mixture significantly increased the chemiluminescence intensity. The relationship between the enhancing activity of phenothiazines and their capacity for enzymatic oxidation by hydrogen peroxide was found. The enhancers discovered new opportunities for increasing the sensitivity of determination of analytes by chemiluminescent enzyme immunoassay.