Analysis of variance delimitation of factors influencing studies of acoustic evoked potentials]

The effect of the variables "stimulus intensity", "residual effect of previous stimulus intensity", "period effect" and "subject effect" on the amplitudes and on the peak latencies of the N1 and P1 components of the acoustical EEG evoked potentials was studied in human subjects with the use of an orthogonal experimental design. The stimulus intensity (30, 50 and 80 dB) accounts for the greatest part of the total variance of the amplitudes and of the peak latencies of N1.-The existence of a totalvariance component due to differences between the subjects is also statistically significant (P equals 5%), As far as the period effect (habituation effect) is concerned, only its effect on the amplitude of N1 - P2 is statistically significant. - The residual effect of the stimulus intensity used in the previous series was not significant.     

热效应在微生物诱变育种中的应用

本文综述了微生物诱变育种中的热效应机理及其应用研究进展。热在微生物诱变育种中具有热诱变效应和热筛选效应, 热诱变效应通过热引起DNA中G-C碱基对的置换实现, 热筛选效应可以从其他诱变剂诱变的菌体中获得更高的正向突变率。     

Anticoagulative effect of pepsin

Anticoagulative effect of pepsin is observed in vitro when its concentration is 36 microM and higher. This effect is due to inhibition of fibrin monomer polymerization. Protamine abolishes anticoagulative effect of pepsin. Pepsin does not influence platelet aggregation induced by ADP and collagen.     

The protective effect of simvastatin against low dose streptozotocin induced type 1 diabetes in mice is independent of inhibition of HMG-CoA reductase

Besides a cholesterol-lowering effect, simvastatin possesses anti-inflammatory properties attributed to inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and/or direct binding to, and inhibition of, the integrin lymphocyte function associated antigen-1 (LFA-1). We have shown that simvastatin protects against multiple low dose streptozotocin (MLDS) induced type 1 diabetes in mice. Presently, we examined if this effect could be abolished by co-administration of mevalonic acid, thus determining if the protective effect is dependent or independent of inhibition of HMG-CoA reductase. Mevalonic acid did not affect the protective effect of simvastatin against MLDS diabetes. Moreover, spleens from these mice did not show any signs of toxic side-effects, thus excluding the possibility that the protective effect is secondary to a general inflammatory response. We suggest that simvastatin’s protective effect mainly is independent of HMG-CoA reductase inhibition. This implies that inhibition of LFA-1 activation is important for the protective effect exerted by simvastatin.     

Mislocalization of visual stimuli: independent effects of static and dynamic attention

Shifts of visual attention cause systematic distortions of the perceived locations of visual objects around the focus of attention. In the attention repulsion effect, the perceived location of a visual target is shifted away from an attention-attracting cue when the cue is presented before the target. Recently it has been found that, if the visual cue is presented after the target, the perceived location of the target shifts toward the location of the following cue. One unanswered question is whether a single mechanism underlies both attentional repulsion and attraction effects. We presented participants with two disks at diagonal locations as visual cues and two vertical lines as targets. Participants were asked to perform a forced-choice task to judge targets' positions. The present study examined whether the magnitude of the repulsion effect and the attraction effect would differ (Experiment 1), whether the two effects would interact (Experiment 2), and whether the location or the dynamic shift of attentional focus would determine the distortions effects (Experiment 3). The results showed that the effect size of the attraction effect was slightly larger than the repulsion effect and the preceding and following cues have independent influences on the perceived positions. The repulsion effect was caused by the location of attnetion and the attraction effect was due to the dynamic shift of attentional focus, suggesting that the underlying mechanisms for the retrospective attraction effect might be different from those for the repulsion effect.     

Role of arginine in the stabilization of proteins against aggregation

The amino acid arginine is frequently used as a solution additive to stabilize proteins against aggregation, especially in the process of protein refolding. Despite arginine's prevalence, the mechanism by which it stabilizes proteins is not presently understood. We propose that arginine deters aggregation by slowing protein-protein association reactions, with only a small concomitant effect on protein folding. The associated rate effect was observed experimentally in association of globular proteins (insulin and a monoclonal anti-insulin) and in refolding of carbonic anhydrase. We suggest that this effect arises because arginine is preferentially excluded from protein-protein encounter complexes but not from dissociated protein molecules. Such an effect is predicted by our gap effect theory [Baynes and Trout (2004) Biophys. J. 87, 1631] for "neutral crowder" additives such as arginine which are significantly larger than water but have only a small effect on the free energies of isolated protein molecules. The effect of arginine on refolding of carbonic anhydrase was also shown to be consistent with this hypothesis.     

腰- 硬联合麻醉用于老年人手术的应用体会

目的:探讨和总结腰-硬联合麻醉在老年人手术中的应用。方法:对128例老年下腹部和下肢手术患者,在腰-硬联合麻醉和硬膜外麻醉下进行手术,对其低血压发生率、镇痛效果和肌松效果情况进行研究析。结果:CSEA组低血压发生率4.67%,镇痛效果优为89.1%,肌松效果优为90.6%;CEA组低血压发生率17.18%,镇痛效果组优为67.2%,肌松效果优为60.9%。结论:老年人下腹部和下肢手术应用CSEA效果满意,安全性好。     

Comparative study of the effect of ionic and non-ionic surface-active compounds on plasmic membrane of yeast protoplasts]

Lytic effect of some cationic surface-active compounds (SAC) on yeast protoplast plasmic membrane is studied. Comparative analysis of the lytic effect of anionic, cationic and non-ionic SAC is carried out, a correlation between key physico-chemical characteristics of the agents (critical concentration of micellization, hydrophyle-lipophyle balance) and their lytic activity is investigated. A proposition is made on the presence in all biphylic compounds of a hydrophyly gradient, which is due to the effect of hydrophylic group on lipophylic properties of hydrophobic part of the molecule, and possible role of this factor in thelytic effect of biphylic compounds on biological membranes is discussed.     

The influence of organic phosphates on the Bohr effect of human hemoglobin valency hybrids.

The Bohr effect of hemoglobin and that of the aquomet and cyanomet valency hybrids was measured in the presence and the absence of IHP (inositol hexaphosphate) and DPG (2,3-diphosphoglycerate). In the absence of these organic phosphates the four hybrids show similar, but suppressed Bohr effects as compared to hemoglobin. Addition of IHP and DPG results in all cases in an increase of the Bohr effect. The additional phosphate induced Bohr effect of the hybrids with the alpha chain in the oxidized form is almost identical to that of hemoglobin, while this effect of the hybrids with oxidized beta chains is slighly lower than that of hemoglobin. The results suggest (a) that the Bohr effect is correlated to the ligation state of the hemoglobin molecule rather than to its quaternary structure (b) that the additional phosphate induced Bohr effect is related to the change in quaternary structure of the tetramer, and (c) that with respect to the Bohr effect of the hybrids there is no difference between high and low spin species.     

Role of protein supplements in the culture of mouse embryos

The effect of various types of proteins used in single protein supplements for Bigger-Whitten-Whittingham (BWW) medium on the in vitro development of mouse preimplantation embryos was evaluated. Thioredoxin, superoxide dismutase (SOD), and apotransferrin showed prominent growth-promoting activity, whereas bovine serum albumin (BSA), fatty acid-free BSA, and catalase showed moderate promoting effects. beta-lipoprotein, ovalbumin and hemoglobin were ineffective, and holo-type transferrin and ceruloplasmin were actually toxic to the embryos. These results suggest that the growth-promotive effect of proteins on mouse pronuclear stage embryos is due to their antioxidative action, or to the removal of some free metal ion(s) such as Fe(3+). The mild growth promoting effect of both BSA and fatty acid free BSA suggest that the effect mediated by BSA is not dependent on bound fatty acids, but more likely is due to their antioxidative effect or chelating effect.     

Role of catecholaminergic mechanisms in regulating the autogenic periodic motor activity of rat pups

In 1-, 2- to 3-, 7- to 8-, and 10-day old intact and spinal rat puppies, studies have been made of the effect of l-DOPA (100 mg/kg, intraperitoneally) on autogenic periodic motor activity in the gastrocnemius muscle. In 1- to 3-day old pups, strong stimulating effect was observed up to a prolonged continuous activity for 5-10 or even more minutes. This effect decreases with age. Traces of the inhibitory effect are observed at early stages in the form of total decrease of the activity. The inhibitory effect increases with age. In all spinal animals, at the background of a decreased activity, stimulating effect of l-DOPA was predominantly observed. Age peculiarities of the effect of l-DOPA are discussed in relation to ontogenetic development of catecholaminergic innervation in rats. It is suggested that stimulating effect of l-DOPA is associated with its action on the descending noradrenergic system, whereas the inhibitory one is mediated by the brain structures.     

Comparison of the diuretic and natriuretic effects of dopamine in control and diabetes insipidus dogs. Effect of propranolol]

The diuretic effect of dopamine is unchanged in the dog with diabetes insipidus but the natriuretic effect of dopamine is shorter. With the normal dog propanolol delays the dopamine-induced diuresis and natriuresis but the magnitude of this double effect is unchanged. In the dog with diabetes insipidus, propanolol suppresses the dopaminergic diuresis and reduces the natriuresis.     

Effect of negative hydro-aero ions on the structure and functional properties of mitochondria

Studies were carried out of the physical mechanism of biological effect of natural stimulant of the living activity--light negative hydroaeroions. The latter are a hydroxyl separated from water ions and designated here as electrically noncompensated hydroxyl OH-. Unique effect of OH-, i.e. fast restoration and prevention of fine damage of native mitochondria (NM) at storage was revealed on mitochondria preparations by specific procedure, providing preservation of the ability of self-organization--formation of aggregated and denser packing--native mitochondria. This effect of OH- is conditioned by increased formation of native mitochondria aggregates and is concerned with better ADP phosphorylation and Ca2- release. The effect of the air current OH- is produced by water action presaturated with OH-. OH- induces in water cooperative structure formation preserved for many days, which is indicated by an increase of its heat capacity and decrease of surface tension. The principal factor in OH- effect both on mitochondria and water seems to be a decrease of local positive changes. It is of more advantage in NM water suspensions to order (structurate) NM with disordering water, which explains formation of NM stable aggregates. OH- effect supports the main function of the organism struggling with proton excess which destroys biological self-organization. Strengthened structural self-organization under the effect of OH- found in NM seems to be of universal importance for biological macromolecules and membranes and is a primary effect of OH- on the living objects.     

Effect of sterols of cholesterol series on secretion of hydrochloric acid in mucosa of animals

Secretion of hydrochloric acid of frog gastric mucosa in vitro was studied as affected by some sterols of the cholesterol series. This effect is found to depend on both the sterol molecule structure and the substance concentration. 7-dehydrocholesterol and its products of oxidation are supposed to have a specific effect on the process of hydrochloric acid secretion. Possible mechanism of this effect is under discussion.     

Induction of dominant lethals in progeny of male CBA mice after pheromonal action

The inhibiting effect of pheromone 2,5-dimethylpyrazine of house mouse females on the reproductive function of the CBA male mice was studied. The mutagenic effect of six-day pheromonal effect was assessed by dominant lethal test. Analysis for the frequency of dominant lethals showed that the pheromonal effect results in an increased death rate of the progeny of the treated males. This is probably explained by implantation failure and is expressed in a reduced average number of the implantation sites and low live embryos per female. The proportion of females with live embryos decreased significantly. The implication of the effect of female mouse pheromone 2,5-dimethylpyrazine on the genetic processes in germ cells of male mice is discussed.     

Influence of phosphate anions on the stability of immobilized enzymes. Effect of enzyme nature,immobilization protocol and inactivation conditions

A destabilizing effect at pH 7 of sodium phosphate on several lipases immobilized via interfacial activation is shown in this work. This paper investigates if this destabilizing effect is extended to other inactivation conditions, immobilization protocols or even other immobilized enzymes (ficin, trypsin, β-galactosidase, β-glucosidase, laccase, glucose oxidase and catalase). As lipases, those from Candida antarctica (A and B), Candida rugosa and Rhizomucor miehei have been used. Results confirm the very negative effect of 100 mM sodium phosphate at pH 7.0 for the stability of all studied lipases immobilized on octyl agarose, while using glutaraldehyde-support the effect is smaller (still very significant using CALA) and in some cases the effect disappeared (e.g., using CALB). The change of the pH to 5.0 or 9.0, or the addition of 1 M NaCl reduced the negative effect of the phosphate in some instances (e.g., at pH 5.0, this negative effect is only relevant for CALB). Regarding the other enzymes, only the monomeric β-galactosidase from Aspergillus oryzae is strongly destabilized by the phosphate buffer. This way, the immobilization protocol and the inactivation conditions strongly modulate the negative effect of sodium phosphate on the stability of immobilized lipases, and this effect is not extended to other enzymes.     

Adaptation of electropic and ionotropic vagal effects on the isolated rabbit atrium]

Long-time vagal stimulation induces a decrease of electrotropic and inotropic effects on the isolated rabbit atrium in spite of constant stimulation frequency. This decrease is defined as effect adaptation. To compensate this effect adaptation, the n. vagus was stimulated with increasing stimulation frequency. Compensation is possible for a certain period referred to as control time. The adaptation of the electrotropic effects is more delayed and weaker than the inotropic effect adaptation. The control times of the electrotropic effect are longer than those of the inotropic effect. Acetylcholine perfusion without vagal stimulation shows the same results. It was shown that the effect adaptaion does not result from depletion of acetylcholine stores or from co-stimulation of sympathetic nerve fibres. The effect adaptation is discussed as being the result of machano-electrical coupling.     

Inhibition of ADP-induced aggregation of human platelets by beta, gamma-methylene-ATP.

Like ATP the analogue beta, gamma-methylene-ATP (AMP-PCP) is shown to be an inhibitor of both ADP-induced shape change and aggregation of human platelets. The effect of AMP-PCP on aggregation is not dependent on its conversion to adenosine, though in the presence of plasma adenosine is produced and the inhibitory effect is enhanced. Since AMP-PCP cannot be enzymatically cleaved at the beta, gamma-position the inhibitory effect cannot be attributed to utilisation of the analogue by a surface-located ATPase as has been suggested for ATP. Alternative explanations for the effect are considered with respect to some current theories of ADP-induced platelet aggregation.     

城市水体对热岛的缓冲性能沿河岸距离的变化规律

城市水体包括城区内的自然水体和人工水体两大类。作为城市生态系统的重要组成部分,水体在缓解城市热岛效应(Urban Heat Island, UHI)上具有重要作用。研究城市热岛效应的现状,探讨水体对城市热岛的缓冲效应,为改善城市热岛效应和生态环境,并对城市进行合理的改造和规划提供理论依据。以长沙市中心城区为研究区域,以南北向贯穿长沙市的湘江河道作为主要研究对象,基于长沙市2016年7月Landsat 8 TIRS遥感影像采用大气校正法反演地表温度(Land Surface Temperature, LST),利用监督分类法获取其同步的城市化进程和土地利用类型,分析市区内地表温度及热岛效应的空间分布特征。同时,通过在湘江两侧建立多个尺度的缓冲区,并将其与地表温度分布及土地利用类型叠置,分析湘江为主的水体对长沙市热环境及各缓冲区的缓冲效应,结果表明:(1)长沙市城市建设格局与热岛效应空间分布基本相似,建筑用地热岛效应更高,极端地表温度达到53.8℃;水体、绿地和裸地的热岛效应相对较低,最低地表温度为16.0℃;(2)湘江对长沙市热岛效应具有缓冲作用,对长沙市热岛效应的平均缓冲距离为400 ...     

Effect of potential fluctuations on the activity of sinoatrial node cells

The effect of fluctuations of the transmembrane potential on the generation of the action potential is studied by simulating the rabbit sinoatrial node (SAN) pacemaker. It is shown that the effect of fluctuations is enhanced with an increase in the concentration of acetylcholine and becomes most pronounced at the border of spontaneous activity loss and after it. When applying and washing off acetylcholine, the hysteretic effect is observed.