The production of chromosome structural changes by radiation

Summary This paper attempts an update and comment upon some of the topics of chromosome aberration formation which Lea raised in Chapter VI of his classic work Actions of Radiations on Living Cells²⁴. Only the first nine sections of this chapter are covered, which deal primarily with the qualitative aspects of aberrations, their formation, classification and interrelationships. In commenting upon these topics, pertinent references are made to work with mammalian and human cells.Increased knowledge of the importance of DNA as a fundamental target and the integral part it plays in the complex structure of the chromosome, coupled with cellular techniques not available to these earlier workers necessitate some revision and modification of early ideas. However, inspite of the enormous accumulation of data and ideas since the original work was published in 1946, the foundation that these early workers laid is still very solid. Surprisingly, we are still puzzled by many of the problems that perplexed them.     

光致发光稀土有机配合物在生物分析上的应用

稀土有机配合物因镧系元素独特的电子结构而成为一类具有重要理论和应用价值的发光材料.本文综述了稀土有机配合物的类型及其光致发光的基本原理,阐述了稀土有机配合物光致发光在生物分析方面的应用,并在荧光免疫分析及活细胞成像方面提出了良好的展望.     

Photoreactivation of UV damage in culturedDrosophila cells

Summary Cell survival and photoreactivation of 254 nm ultraviolet (UV) light damage in a wild typeDrosophila cell line was assayed by colony formation in liquid medium. F_o, F_q, and extrapolation number for the exponential portion of survival curves are 21 J/m², 3.6 J/m², and 1.5 for non-photoreactivated cells and 110 J/m², 11.2 J/m², and 1.3 for those exposed to photoreactivating light. Maximal photoreactivation occurs at the 100 J/m² region of the curve. At 10 and 50% survival, 75–80% of the UV damage was photoreactivable.     

Increase in the survival time of mice exposed to ionizing radiation by a new class of free radical scavengers

Summary N-acyl dehydroalanines react with and scavenge mainly superoxide radical and hydroxyl radical (HO^.). The ortho-methoxyphenylacetyl dehydroalanine derivative, indexed as AD-20, protects mice against damage resulting from total body X-irradiation, as measured by the increase in their survival time. AD-20 increases the LD₅₀ at 30 days from 6.1 to 7.3 Gy in animals exposed to a wide range of X-rays (6 to 10 Gy). The dose reduction factor (D R F) of AD-20 is 1.20. We postulate that such radioprotective effect may result from its free radical scavenging activity.     

Components of biological,including seasonal,variation in hematological measurements and plasma fibrinogen concentrations in normal humans

This study has been carried out in order to examine the components of biologicalaand, in particular, seasonal variation in hematologic measurements in normal humans. Toward this end, 26 normal volunteers had monthly blood samplings during one calendar year for determination of number of red blood cells (RBC) and platelets, hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), MC Hb (MCH), MC Hb concentration (MCHC), RBC distribution width (RDW), mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (PCT), and plasma fibrinogen concentrations. The data were analyzed by means of spectral analyses of a group of time series or a single time series, and by means of repeated measures analyses of variance. Most of the hematologic variables show seasonal rhythms, such as annual rhythms or harmonics, which are expressed as a group phenomenon. An important part of the variance (>15%) in Ht, MCV, MCH, MCHC, RDW, number of platelets, MPV and plasma fibrinogen was explained by a yearly variation. The peak-trough differences (expressed as a percentage of the mean) in the yearly variations in number of RBC, Ht, MCV, MCH, MCHC and RDW were very low (all<8.5%). Number of platelets (14.4%) and plasma fibrinogen values (28%) showed a high-amplitude yearly variation. All hematological variables, except MCHC, show a high interindividual variability which exceeds by far the intraindividual variability.     

Possible biological effects of electric and magnetic parameters in the environment

The features and intensities of electric and magnetic fields in the environment are described. Natural as well as technical constant and variable fields are considered in the light of their possible biological effects. The upper limits of the various fields are discussed. Results of laboratory measurements and also of epidemiological investigations are presented. The question is raised whether atmospheric small ions can cause a biological effect.