Ultraweak luminescence of blood plasma in experimental embolism of the main arteries of the limbs

The changes in the level of blood plasma chemiluminescence initiated by hydrogen peroxide and divalent iron were studied in experiments on 15 dogs with aorta bifurcation embolism. After occlusion of the arteries the level of iron-initiated chemiluminescence decreases. The level of hydrogen peroxide-initiated luminiscence increases simultaneously, reaches the maximum after 6-hour occlusion and subsequently tends to decrease. Hydrogen peroxide-initiated statistically significant increase in luminescence allows one to form a judgement about duration of the disease. After blood flow recovery in the limbs there take place a rise in the level of hydrogen-peroxide initiated hemiluminescence and subsequent iron-initiated hemiluminescence level drop.     

The extension reached by the minimization of the polarity distances during the evolution of the genetic code

Summary The level reached by the optimization of the polarity distances during the evolution of the genetic code was investigated. The results, although not conclusive, indicate that this optimization level is higher than the data reported in the literature. The results seem compatible with the reaching of an evolutionary minimum, with respect to the optimization of the polarity distances, by the genetic code during its formation.     

Compressive Nonlinearity in the Auditory System: Manifestation in the Action of Complex Sound Signals

In psychophysical experiments on humans, a cochlear compression was revealed by comparing onfrequency and low-frequency masking in the conditions of discrimination of complex spectra of sound signals. It has been established that, with an increase in the level of the masker, the limit of the discriminable density of the spectrum ripples decreases. It was noted that when the signal level increased, the on-frequency masker level at threshold grew proportionally to the level of the signal, whereas the low-frequency masker level grew much more slowly, indicating the compression of the signal, which was not affected by lateral suppression and off-frequency listening.     

溶氧水平对红豆杉细胞悬浮培养的影响研究

紫杉醇 (Ｔａｘｏｌ)是源自红豆杉提取物的一种高度衍生化的二萜类化合物 ,临床实验结果表明紫杉醇对于卵巢癌、乳腺癌、胃肠道癌等具有明显的抗肿瘤活性[1] ,因而受到世界各国的广泛关注 ,并已被美国食品与药品管理局 (ＦＤＡ)批准用于卵巢癌与乳腺癌的治疗[2 ] 。到目前为止紫杉醇仍然主要从树皮中提取 ,但由于红豆杉生长缓慢 ,天然资源非常有限 ,加快其替代来源的研究势在必行。利用植物细胞悬浮培养生产紫杉醇作为一种可行的选择 ,近年来取得了较大的进展[3 ,4 ] 。本文研究了摇瓶及 2 0 Ｌ反应器培养过程的溶氧水平对细胞生长及紫杉醇…     

Changes in activity of the renin-angiotensin system of the rat by induction of acute inflammation

Angiotensinogen is the precursor of biologically active peptide angiotensin II and its hepatic synthesis is increased by the induction of acute inflammation. Studies were carried out to know whether the rise in plasma angiotensinogen is actually involved in the activity of the renin-angiotensin system during acute inflammation. The plasma level of angiotensinogen in rats was increased to 2.5 times the normal level 16 h after the induction of acute inflammation by administration of lipopolysaccharide (LPS). The plasma renin concentration (PRC) was decreased to about 40% of the normal level concomitantly with a reduction of plasma renin activity (PRA) at 4 h after LPS administration. In contrast, 16 h after LPS injection, when plasma angiotensinogen showed a high level and PRC had recovered to the normal range, PRA was increased to 1.7 times the normal level. These results indicate that acute inflammation induced by LPS causes a biphasic change in the generation of angiotensin I, i.e., an early decrease depending upon the reduction of PRC and later increase depending upon elevation of the angiotensinogen concentration.     

Comparison of in vitro effects of cadmium and nickel on the components of the liver microsomal drug metabolizing enzyme system of the guinea-pig

In vitro addition of cadmium chloride (CdCl2) to a reaction mixture decreased the liver microsomal cytochrome P-450 level of the male guinea-pig. In contrast nickel chloride (NiCl2) did not cause any alteration in the cytochrome P-450 level. Neither CdCl2 nor NiCl2 produced any activity changes in the liver microsomal NADPH-cytochrome c reductase. When the liver microsomes were preincubated in the presence of CdCl2, metal-induced reduction increased as the time of preincubation progressed and attained its maximum reduction level at about 15 min. In the case of NiCl2, the maximal reduction level was attained at about 5 min. However, no changes were observed by metals in liver microsomal NADPH-cytochrome c reductase activity as the time of preincubation progressed. After preincubation, the reduction of cytochrome P-450 achieved by CdCl2 was stronger than that obtained by NiCl2 as well as than that obtained by CdCl2 without preincubation.     

Variable methylation of the ribosomal RNA genes of the rat.

Both the pattern and level of rRNA gene methylation vary in the rat. This variation reflects stages in the maturation process and perhaps the level of gene expression in different tissues. We studied methylation at a common site, the inner cytosine of the sequence CCGG, by hybridizing 32P-rRNA to DNA digests obtained with endonuclease Msp I (which cleaves CCGG and CMCGG) and its isochizomer, HpaII (which cleaves only CCGG). In the liver, the changing pattern of rRNA gene methylation reflected the late stages of development: the rRNA genes were mostly unmethylated at 14 days gestation; by 18 days gestation, about 30% of them were methylated, and this level persisted into adulthood. In 18-day DNA, the methylation was uniform, but in adult DNA, the methylation pattern was discontinuous, because otherwise methylated genes contained a demethylated region. Similar developmental changes were observed in brain DNA. In a tissue culture cell line, the change from the continuous to the discontinuous pattern of the methylation could be induced by transformation with Kirsten sarcoma virus. And, in adult tissues, the lowest level of rRNA gene methylation was found in rapidly growing jejunal epithelium, and the highest level, in non-growing spermatozoa.     

低功率激光外照射治疗炎症性疾病

低功率激光外照射治疗炎症性疾病,在临床已广泛应用,并取得较好的效果,本文主要其激光对炎症的作用机制从四个方面作一总结概述。     

Glutathione content in the semen of bulls of the lowland black-white breed

Glutathione concentration in the semen was determined in 113 ejaculates obtained from 30 bulls of the lowland black-white breed. The quantitative and morphological characteristics of the studied sperm samples indicated considerable individual differences but always within normal range. Glutathione content was determined in the plasma and in isolated spermatozoa by the method of Saville (Analyst, 1958, 83, 670). A high glutathione level in the spermatozoa (31 nmols in 10(9) cells) and in plasma (28.8 microM) was found. A positive correlation was demonstrated (p less than 0.05) between the level of the peptide in plasma and its level in spermatozoa. It was found that the glutathione level in spermatozoa was higher in the ejaculates with the cell count below the average level.     

Time course of the changes in the level of endogenous growth regulators during the stratification of the seeds of the ‘Panenské české’ apple

The time course of the changes in the level of endogenous growth regulators was followed during the stratification at 5 °C of the seeds of ‘Panenské ?eské’ apples. An increase in the endogenous gibberellin activity was found already during the first and the second week of stratification which is according to it decisive for the release of dormancy in the seeds, as it precedes with the anticipation of approximately two weeks the curve of the release of dormancy in the seeds. The rise in the level of endogenous cytokinins in the seeds is belated one to two weeks behind the rise in gibberellin activity in them and thus approximately coincides with the release of dormancy. The rise in auxin level occurs approximately 4 weeks after the increase in cytokinin level. The increase in auxin level, which is accompanied by an increase in inhibitions, is apparently not connected with the release of dormancy in the seeds during the stratification.     

The level of lymphocytes in the peripheral blood as a criterion of the degree of severity of acute radiation sickness (based on materials from the accident at the Chernobyl Nuclear Power Station)

A study was made of the peripheral blood lymphocyte level as a function of gamma-radiation dose after single gamma-radiation attack resulted from Chernobyl disaster. After the initial drop an average level of lymphocytes was stabilized by day 2 after exposure and no further systematic decrease in the number of lymphocytes occurred. The accuracy of prognostication of the severity of acute radiation sickness, determined by the average lymphocyte level on days 3-6 amounted to as low as 50%. However, when the neighbouring, by the severity, groups of patients were taken into account, the accuracy was 88%.     

The impact of cerebral palsy on the intelligibility of pitch-based linguistic contrasts

This study investigated the perception of three Cantonese level tones produced by speakers with dysarthria associated with cerebral palsy. Four speakers with dysarthria were selected on the basis of their distinctive patterns of fundamental frequency (F0) values observed in the level tones they produced, which showed errors in either F0 level or, F0 contour, or both. Monosyllabic words which contrasted in tone level were used as stimuli in an identification task. Five expert listeners identified the tones among the six Cantonese contrastive tones. Results showed that the tones produced by the dysarthric speakers were predominantly perceived as level tones; although a majority was perceived as the wrong level tone. The most important finding is that only the level tones produced by dysarthric speakers could be identified as rising or falling contour tones. The frequent perceptual confusion among the level tones, and the perception of contour tones, shows that a disorder in the production of pitch-based linguistic contrasts can have a substantial impact on the communication abilities of individuals with cerebral palsy.     

考洲洋饵料生物水平综合评价

在GIS(Geographical Information System)的支持下,利用等级模型对1999年2月(枯水期)和8月(丰水期)考洲洋饵料生物水平进行了综合的分析和评价。枯水期考洲洋整个水域饵料生物的分布较均匀,其密集分布区位于湾西北部、湾口和吉隆河口附近水域,达4级水平,饵料生物较为丰富。丰水期饵料生物水平的变化幅度较大,其密集分布区位于湾中部和望京洲沿岸水域,达4-5级,饵料生物最为丰富,其次为湾口,达4级水平。两个调查航次相比,丰水期的饵料生物水平高于枯水期。主要优势种的变化具有明显的季节交叉和演替现象,浮游植物和浮游动物的主要优势种在不同季节差异较大,而底栖生物的优势种组成在整个调查期间变化不大。调查期间各饵料生物的多样性指数和均匀度均呈现出较大的变化,其最大变化范围分别为0.01-4.49和0.01-0.96,表明湾内饵料生物受外界环境条件影响较大,生物群落组成结构和生物多样性水平不太稳定。调查期间整个水域的生物多样性阈值均呈现出湾西部及西北部水域较高,其余水域较低的分布特点,但不同季节其变化趋势及分布范围略有差异。枯水期多样性阈值的密集分布区出现于湾西侧的部分水域,其等级水平为3级,饵料生物多样性较好,其余水域均为2级或低于2级水平,多样性一般或较差。丰水期的分布趋势与枯水期相似,其密集区出现于湾西部和西北部的整片水域中,分布范围比枯水期大,但等级水平明显低于枯水期,为2级,多样性一般,其余大部分水域均为1级水平,多样性较差。       

Influence of the spacer of cationic gemini amphiphiles on the hydration of lipoplexes

The impact of the length of gemini surfactant spacer on complexation and condensation of calf thymus DNA by cationic mixed phospholipid/gemini liposomes was investigated by monitoring the conformational changes of DNA by circular dichroism and the lipid hydration level by the emission characteristics of the fluorescent probe laurdan included in the lipid bilayer. The length of the spacer was shown to influence, on one hand, the hydration level and the organization of the corresponding liposomes and, on the other, the variation of lipid hydration level and the DNA conformation upon complexation. In fact, in correspondence with the longest spacer we observed more hydrated liposomes, probably organized in domains, a higher extent of dehydration promoted by the addition of DNA, and a minor extent of DNA conformational change. The physicochemical features of lipoplexes were shown to depend on the [cationic headgroup]/[DNA single base] ratio.     

The role of the antilysozyme activity of Shigella flexneri as a factor controlling the degree of its resistance to the lytic action of bacteriophages

The level of the antilysozyme activity of S. flexneri in ensuring the high level of their phage resistance has been studied. The realization of the phage protective effect of antilysozyme activity has been noted to occur due to disturbances in the lysis of infected bacteria by phage-synthetized lysozyme-like enzyme. The direct relationship between the level of the lysozyme production of bacteriophages and their capacity for overcoming the antilysozyme protection of the host bacterium has been shown.     

Analysis of the trends in typhoid-paratyphoid morbidity in the USSR]

Mathematico-statistical analysis of typhoid-paratyphoid infection morbidity in the USSR during 1900--1940 revealed a regular many-year cyclic recurrence of the changes in the morbidity level. The intensity of the morbidity level reduction at the periods of decline--in 1900--1917, 1920--1928, and in 1932--1939--was similar. A successive reduction of morbidity of this group of infections, by 6.45% on the average, annually, occurred in 1930--1976. The character of reduction of typhoid-paratyphoid infections morbidity level in the USSR during that period is well described by the exponential function.     

Changes in the cAMP level in macrophages during the phagocytosis of Salmonella typhimurium. II. Effect of the virulence of microorganisms and the immune status of the macrophages on the dynamics of changes in cAMP levels

The dynamics of changes in the level of intracellular cyclic AMP in nonimmune and immune macrophages in the process of the phagocytosis of S. typhimurium virulent strain, its heated variant and its mutant with low virulence was studied. A transient increase in the level of cyclic AMP was shown to occur during the first 30 minutes of phagocytosis; this increase did not depend on the kind of the phagocytized object and on the activity of macrophages and neither had it any influence on the outcome of phagocytosis. The virulent strain also induced the three-fold increase of the level of cyclic AMP in nonimmune macrophages prior to their disintegration caused by the cytopathogenic action of the microorganism. In immune macrophages the virulent strain did not induce the secondary increase of the level of cyclic AMP.     

Analysis of the Control of Development in Oryzopsis miliacea by the Light Environment

The developmental responses of Oryzopsis miliacea plants tothe light environment were separated into those resulting fromthe level of incident solar radiation and those resulting fromthe photoperiod (comparing 16 h, which are inductive for flowering,with 8 h, which are not). The rate of leaf appearance and thetransition from the vegetative to the reporductive state, weredetermined by photoperiod and not by radiation level. In inductivephotoperiods, the ontogenetic timing of internode elongationwas unaffected by radiation level. Lowering the radiation levelprogressively delayed and reduced the activation of axillarybuds and crown roots, whereas photoperiod was without significanteffect. Accumulation of dry matter was progressively reducedas the radiation level was lowered, without affecting its distributionbetween the root and shoot systems. The mean dry-matter contentof a single shoot, as well as that of a single crown root, werealso unaffected by radiation level. The shorter photoperiodresulted in the diversion of a greater proportion of the drymatter to the root system, with the result that individual shootsaccumulated less, and individual roots accumulated more drymatter than in the longer photoperiod. Leaf blades in comparablenodal positions were consistently smaller and contained lessvasucular bundles in the longer photoperiod. These effects wereapparently due to inhibition of the trend for increasing cellproliferation in the surface plane by the long photoperiod,and its very small effect on the trend for diminution in celldimensions in blades on progressively higher nodes. The levelof solar radiation also affected blade surface dimensions, lowerlevels resulting in progressively larger surfaces, but the effectsof photoperiod and those of nodal position were equally modified.The longer photoperiod reduced the cross-sectional area of theinterbundle chlorenchyma strands, without affecting its shape,while reduction in radiation level caused an increase in itswidth and a compensating decrease in its thickness, thus changingthe shape of the cross-section without affecting its area.     

Role of the pulmonary mechanoreceptor apparatus in molding the natural respiration of the frog Rana temporaria

In acute experiments on the frog Rana temporaria, studies have been made of the effect of afferent impulsation in pulmonary mechanoreceptors on respiration pattern. Simultaneous recordings were made of total afferent activity in the pulmonary branch of the vagal nerve and of the activity of motor respiratory nerves as an index of respiration pattern. It was shown that to the end of ventilation period, the level of afferentation decreases up to a threshold value which favours the onset of inspiration. Artificial decrease of afferentation level by the increase in CO2 content in the lung or by novocain application to the latter always resulted in extra-inspiration. On vagotomized frogs, it was found that maximum level of afferent influences is necessary for the onset of expiration.     

Evidence for the contribution of the S-state transitions of oxygen evolution to the initial phase of fluorescence induction

Fluorescence induction of isolated spinach chloroplasts was measured by using weak continuous light. It is found that the kinetics of the initial phase of fluorescence induction as well as the initial fluorescence level F_j are influenced by the number of preilluminating flashes, and shows damped period 4 oscillation. Evidence is given to show that it is correlated with the S-state transitions of oxygen evolution. Based on the previous observations that the S states can modulate the fluorescence yield of Photosystem II, a simulating calculation suggests that, in addition to the Photosystem II centers inactive in the plastoquinone reduction, the S-state transitions can also make a contribution to the intial phase of fluorescence induction.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethyl urea - F₀ non-variable fluorescence level emitted when all PS II centers are open - F_i initial fluorescence level immediately after shutter open - F_pt intermediate plateau fluorescence level - F_m maximum fluorescence level emitted when all PS II centers are closed - PS II Photosystem II - Q_A primary quinone acceptor of PS II - Q_B secondary quinone acceptor of PS II