Mechanisms of disruption of DNA in human cells. Mutagenesis of a virus in xeroderma pigmentosum cells as an indicator of a defect in DNA repair

Lymphocytes of two patients with Xeroderma pigmentosum, their mothers and cell lines isolated from the third patient were examined. The reaction of vaccinia virus treated with mutagens, the index of virus-induced mutagenesis and DNA repair synthesis were the criteria of estimation of cell repair activity. Significant inhibition of DNA repair synthesis was detected in cells of all the patients observed (primary and established lines) in the experiments with UV-irradiation and 4-nitroquinoline-4-oxide. These indexes correlated with decreased virus reactivation and increased level of virus-induced mutagenesis. Inhibition of DNA repair synthesis was also revealed in lymphocytes of both mothers. These data claim a possibility of discovering heterozygotes, the carriers of mutant genes. The data on virus-induced mutagenesis serve as a simple test for detection of DNA repair disorders.     

中国仰蝽科一新种及一新纪录（半翅目）

本文记述了中国半翅目仰蝽科一新种:突顶小仰蝽Anisops protracta sp. nov. 及一新记录:南小仰蝽A. exigera Horvath。对于新种进行了描述,并附特征插图8幅。     

安徽省达氏属一新种记述：吸虫纲：棘口科

本文记述了寄生于淡水鱼类的棘口科吸虫的一个新种——淮河达氏吸虫Ditetziella huaiheeniss sp.nov.模式标本采自安徽省淮河的女山湖地区黄颡鱼的肠道。     

Changes in the hydrodynamic resistance of collaterals after ligation of the femoral artery

After ligation of the femoral artery in 12 dogs anatomical changes of the collaterals 1 month after the operation are accompanied with 18-fold decrease of hydrodynamic resistance in them as compared to the initial one. The shifts observed in 96% are the results of dilatation occurring in the intramuscular interarterial anastomoses. Dilatation of the intramuscular arteries, situating more distally to the anastomosis zone and experiencing a decreased arterial pressure, is also observed, as it is in proximal vessels, situating in the zone of an increased blood pressure. Despite the essential shifts, the blood flow capacity of the collaterals even 1 month after the operation is still 500 times as small as that of the intact femoral artery.     

Mammalian growth and development parameters, cell proliferation in culture and the maximal life span]

The maximum life span of mammals is known to be proportional to the pregnancy duration and to the age at puberty. We found that the maximum life span of mammals was also proportional to the number of cell doublings, and inversely proportional to the rate of duplication of these cells, during embryogenesis or for the time from zygote formation to growth termination. We found also that the life span of "stationary phase aging" transformed Chinese hamster cells (time from subcultivation until culture "death", i.e., until the moment when the number of live cells is less than 10% of their number at saturation density) was proportional to the duration of their growth and number of cell doublings during the period from subcultivation to saturation density, and inversely proportional to the rate of cell culture duplication during the same period. The dependencies for cell cultures and mammals proved to be analogous to each other. An approximately twofold decrease in the cell duplication rate, as a result of a decrease of the growth medium temperature from 37 to 27 degrees C or the introduction of ethanol to a final concentration 2%, increased the life span of "stationary phase aging" cultures more than twofold. The data obtained suggest that influences resulting in optimized delay of the rate of cell duplication, and correspondingly the mean rate of proliferation during the period of growth in mammals, may increase their maximum life span.     

Evaluation of the usefulness of three collections of bacteriophages for typing methicillin-resistant Staphylococcus aureus,isolated in Moscow hospitals

The typing of S. aureus methicillin-resistant strains, isolated in different hospitals of Moscow; was carried out with the use of three collections of phages: the International Set of Phages; the set of phages of the International Center of S. aureus phage typing in London (L); and the experimental collection of phages of the Gamaleya Institute of Epidemiology and Microbiology in Moscow (M). In this study made with the use of both the phages of the International Diagnostic Set and phages L in the standard typing dose of 1 TP about 6% of the cultures under study proved to be sensitive. When the typing dose was increased to 100 TP the phages of the international diagnostic set lyzed 75.5% of the cultures. The typed strains were found to belong to phage types 77 (71.7%), 77/84/85 (19.6%) and 94/96 (6.5%). At a concentration of 100 TP phages L lyzed 83.7% of the cultures, but the dominating phage types could not be determined due to a great variety of phage markers. In contrast to the two preceding collections, the third phage collection M was composed in such a way that in the study of the investigated culture the specificity of its restriction modification was primarily evaluated and only then the presence of antiphage immunity was determined. This latter collection was used in the evaluation of 93.1% of the cultures. By the specificity of their restriction specification system the majority of them were classified with two new groups, heretofore not described. Only this collection M made it possible to differentiate epidemic and sporadic strains and to evaluate the epidemic situation in all 6 hospitals.     

Internal synchronization of the main 0.1-Hz rhythms in the autonomic control of the cardiovascular system

Synchronization parameters of 0.1-Hz rhythms isolated from the heart rate and the oscillations of the blood volume in microcirculatory vessels were studied in 12 healthy subjects and 32 patients with acute myocardial infarction. Recordings of the electrocardiogram and the pulsogram from the distal phalanx of the index finger, as well as mechanical recording of respiration with the body in a horizontal position, were performed. In patients with myocardial infarction, the recordings were performed during the first three to five days and the third week after the infarction. Synchronization was tested by plotting phase differences and calculating the total percentage of phase synchronization. Synchronization parameters of 0.1-Hz rhythms were high in healthy subjects. In patients with acute myocardial infarction, synchronization of 0.1-Hz rhythms was considerably poorer. The data obtained suggest that the studied 0.1-Hz rhythms are two independent oscillatory processes that are synchronized in healthy subjects. However, this interaction may be disturbed in cardiovascular pathologies, e.g., myocardial infarction.     

A study of interactions of carbonic anhydrase B with water and urea. I. Spin-diffusion parameters that determine individual and cooperative properties of molecules

The rigidity parameter (G), which is characteristic of protein compactness, was studied in native globular carbonic anhydrase B. The dependence of parameter G on power and excitation time of spin-diffusion was expressed analytically. We found out that native carbonic anhydrase B is able to form water-protein units that are probabilistically distributed with respect to their sizes. Large water-protein units can be detected by analyzing the spin-diffusion spectra. The excitation frequencies of spin-diffusion spectra were shifted far away from typical 1H NMR spectra of carbonic anhydrase B.     

Studies of interactions of carbonic anhydrase B with water and urea: II. Spin diffusion of associates of protein intermediate state at 4.2 M of urea

The formation of carbonic anhydrase B associates (pH 5.7, urea concentration 4.2 M, 297 K) was studied as a function of protein concentration and time by nuclear magnetic resonance spectroscopy (spin diffusion method). It was found that the association process proceeds in two steps. The first step is relatively fast and cannot be controlled by our methods. During this step, persistent units are built. These consist of protein molecules that are able to interact with solvent molecules and with each other when protein solution contains 4.2 M of urea. Persistent units are relatively small (two, three protein molecules), and their mobility matches one of a single protein. The second step is slower, and throughout this step large structures are formed from persistent units. The parameters G* and S*, which characterize spin diffusion in a protein and a solvent, respectively (when spin diffusion excitation happens away from NMR spectral signals) are related to the probable size distribution of protein-solvent associates and are determined by their collective properties.