Spectral characteristics of the bioelectrical activity of the cerebral cortex upon electric stimulation of subcortical structures

A spectral-correlation analysis of electrical activity of the rabbit cerebral cortex was made with the use of Dnieper computer, after electrical stimulation (100-250 c/s) of the midbrain reticular formation, the thalamic nonspecific formations (midline nuclei) and different nuclei of the posterior part of the hypothalamic area (ventromedial and posterior hypothalamic nuclei and the lateral field). The background spectrograms were characterized by a high variability; their frequencies ranged from 0,5 to 12 c/s. Under the influence of the electrical stimulation of the indicated formations, a well-pronounced, dominating peak appeared in the spectrograms of the cortical EEG, in the band from 4 to 7 c/s, and the similarity of biopotentials in this rhythm increased. The experimental data show that enhancement of spatial synchronization of the cortical biopotentials under conditions of electrical stimulation of the indicated subcortical formations is based on increased rhythmic oscillations within the theta-band and on a greater coherence in this range.     

有机酚醛聚合物凝胶深部调驱体系孔渗适应性研究

聚合物凝胶体系在地层中的渗流及封堵特性对深部调驱效果具有重要的影响。利用长填砂管驱替物模试验,研究了有机酚醛聚合物凝胶体系在不同渗透率填砂管中的注入特性、渗流行为和封堵性能,结果表明有机酚醛聚合物体系是一种注入性和流动性均较好的凝胶体系。通过对有机酚醛聚合物凝胶体系在长填砂管中的封堵特性和渗流参数结果分析,确定了有机酚醛聚合物凝胶体系组分质量浓度与3种地层渗透率的匹配关系。最后通过室内驱油物模试验,对凝胶体系与渗透率的匹配关系进行了验证。     

一种基于时钟差的双端数据同步方法

文章对已有的双端数据采样同步方法进行了对比分析并指出了其优缺点.随着自愈环网和可变路由的光纤通道在高压电网中的普遍应用,采样数字同步网络复用通道作为传输信道时有可能出现通信路由不一致的情况,为了解决收、发通道延时不一致时的数据同步问题,文章引入装置“时钟差”的概念,以传统的“乒乓对时”为主,辅助以电气量对时,可以解决由...     

Staurosporine inhibits interferon alpha-induced gene expression in Friend erythroleukemia cells through a PKC independent pathway

Diabetes mellitus is associated with typical patterns of long term vascular complications which vary with the organ involved. The microvascular kidney disease (Olgemoller and Schleicher, 1993) is characterized by thickening of the capillary basement membranes and increased deposition of extracellular matrix components (ECM), while loss of microvessels with subsequent neovascularisation is predominant in the eye and peripheral nerves. On the other hand macrovascular disease is characterized by accelerated atherosclerosis. These complications are dependent on long term hyperglycemia. Specific biochemical pathways linking hyperglycaemia to microvascular changes were proposed: the polyol pathway (Greene et al., 1987), non-enzymatic glycation of proteins (Brownlee et al., 1988), glucose autooxidation and oxidative stress (Hunt et al., 1990), hyperglycemic pseudohypoxia (Williamson et al., 1993) enhanced activation of protein kinase C by de novo-synthesis of diacyl glycerol (Lee et al., 1989; DeRubertis and Craven 1994) and others. These pathways are not mutually exclusive (Larkins and Dunlop, 1992; Pfeiffer and Schatz, 1992). They may be linked to alterations in the synthesis of growth factors particularly since atherosclerosis and angioneogenesis are associated with increased proliferation of endothelial and smooth muscle cells. Increased synthesis of ECM components is stimulated by growth factors like transforming growth factor beta (TGF beta) (Derynck et al., 1984) and insulin-like growth factor I (IGF-I) (Moran et al., 1991). This review will summarize some of the recent evidence for an involvement of growth factors in diabetic vascular complications and will attempt to assign their emergence in the sequence of events leading to vascular complications.     

Synthesis of modified oligodeoxyribonucleotides containing 9-(2'-amino-2'-deoxy-beta-D-arabinofuranosyl)adenine

A method for preparing a modified derivative of 2'-amino-2'-deoxy-arabino-adenosine ready for directed insertion into an oligonucleotide chain during solid-phase synthesis was elaborated. A series of the title oligonucleotides (6-25-mers) containing a 2'-amino-2'-deoxy-arabino-adenosine fragment were prepared. A high reactivity of the 2'-amino group during the acylation with carboxylic acid anhydrides was demonstrated. It was shown that the insertion of the modified fragments into oligonucleotides did not inhibit the formation of the DNA duplex.     

Gangliocytoma--magnetic resonance imaging characteristics

An atypical presentation of a temporal lobe gangliocytoma in an adult female with headaches is reported. Computed tomography showed a hypodense enhancing mass in the right temporal lobe with vasogenic oedema and mass effect. MRI demonstrated a well demarcated mass of low signal on T1W, intermediate signal on PDW, high signal on T2W and homogeneous enhancement on post-gadolinium scan. This case is an addition to the current literature for the characteristic MR features of a ganglion cell tumour.     

A new method of nonradioactive labelling of oligonucleotides and their use as allele-specific probes for detecting mutations causing beta-thalassemia

We have developed simple and efficient methods for synthesis of biotin and horseradish peroxidase (HRP)-labeled oligonucleotides. Biotinylated oligonucleotides were obtained in quantitative yields, and oligonucleotide conjugates with HRP in 60-80% yields. Allele-specific oligonucleotide probes for the diagnostics of IVS 1-110 mutation in the beta-globin gene causing beta-thalassemia were thus obtained. Temperature conditions for the non-radioactive ASO hybridization with the amplified segment of the human beta-globin gene and wash conditions were selected. HRP-labelled probes were used in hybridization without preliminary separation after synthesis. To decrease nonspecific enzyme binding we have elaborated special conditions for membrane blocking. Detection of the biotinylated probe was carried out with the help of a streptavidin--HRP conjugate. O-Dianisidine was used as a chromogenic substrate. We have demonstrated the usefulness of this method in the analysis of amplified samples of DNA obtained from blood of patients homozygous in the mutant gene, and heterozygous carriers.     

Reversal of advanced liver fibrosis in rabbits with Schistosomiasis japonica

Advanced liver fibrosis is generally considered to be irreversible. We studied the reversibility of marked liver fibrosis in rabbits infected with Schistosoma japonicum. We determined liver collagen content, collagen biosynthesis, and collagenase activity using serial biopsy specimens obtained 20, 40, and 60 weeks after infection. Reversibility of this process was investigated in rabbits cured of infection at 21 weeks; control rabbits not cured of infection were also studied. At 20 weeks, liver collagen content was 16-fold greater than normal, with accumulation of collagen types I, III, and V. Synthesis of collagen within fibrotic liver slices was 10-fold greater than normal. Liver collagenolytic activity for a type I substrate was 19-fold greater than normal. After parasitologic cure, a striking morphologic reversal of fibrosis occurred during the subsequent 40 weeks, with the return of liver collagen content to three-fold greater than normal and a 75% decrease in synthetic rates compared with those at 20 weeks (P < 0.01). Collagenolytic activity remained elevated to the same degree noted at 20 weeks. A similar but lesser resolution of fibrosis also occurred in untreated control rabbits, coincident with a spontaneous decrease in new egg deposition known to occur in this model system. We conclude that advanced liver fibrosis in S. japonicum-infected rabbits is slowly reversible after cure or senescence of the infection. A possible mechanism for this reversal is persistently increased collagenolysis as collagen synthesis diminishes.