Rate of excitation propagation in a reduced Hodgkins-Huxley model. I. Rapid relaxation of the sodium current]

The question of calculating excitation propagation velocity is analyzed on the basis of the Hodgkin-Huxley model. The activation of the sodium current is assumed to be rapid as compared to the rate of potential variation. Because of slow variation of potassium activation and sodium inactivation the dynamics of these processes is assumed to be of negligible effect in the region of impulse velocity formation. By means of pieace-wise linear approximation of thus obtained voltage-current characteristics the characteristics the analytical solution of the problem was found. In two limiting cases this solution coincides with the solutions of Kolmogorov and Scott. The dependence of impulse velocity on parameters is analyzed and illustrated graphically.     

Transacetylation of carbohydrates in organic solvent catalysed by O-acetylpeptidoglycan esterase from Neisseria gonorrhoeae

The potential of the Neisseria gonorrhoeae O-acetylpeptidoglycan esterase (Ape1a) for catalysing transacetylations in organic solvents with a number of carbohydrate acceptors was investigated. The performance of the enzyme was observed to improve as the polarity index of the solvent increased. The best transacetylation conditions were determined to be a 1:6 phosphate buffer/ethyl acetate system, where Ape1a catalysed approximately 28% acetylation of 4-methylumbelliferyl-N-acetylglucosamine using p-nitrophenyl acetate as donor. Further analysis of the acetylated products by reverse phase HPLC and ESI-mass spectrometry confirmed the presence of monoacetylated 4-methylumbelliferyl-N-acetylglucosamine. Under identical reaction conditions, the enzyme also performed transacetylations using ethyl acetate or vinyl acetate as donor. These results demonstrated the feasibility of using the bacterial cell wall enzyme Ape1a to generate hitherto unattainable compounds which may be used as antagonists of peptidoglycan-metabolizing enzymes.     

Phosphorylation of lactate dehydrogenase by ATP

Evidence is presented indicating that phosphorylation of porcine muscle lactate dehydrogenase by [gamma-32P] ATP occurs at carboxyl residues of the protein. The phosphoenzyme complex was moderately stable at pH 6.8 and 25 degrees C, with a half-life of 3.5 h. In the presence of NADH rapid dephosphorylation occurred. Formation of an abortive complex with NAD-pyruvate also caused hydrolysis of the phosphoenzyme. The phosphorylated lactate dehydrogenase was shown to serve as a phosphate donor for phosphorylation of ADP.     

实验恒河猴糖尿病动物模型建立及视网膜并发症的研究

[目的]糖尿病是由于多种因素和遗传因素导致体内胰岛素相对或绝对分泌不足,而引起的代谢性内分泌疾病,它以血糖、尿糖升高为特点,起病隐蔽,通过并发症使人致残致死,是继心血管、癌症之后的第三大致死性疾病,很可能成为21世纪人类的“第一杀手”(1,2)。本文采用人工诱导的方法,建立恒河猴糖尿病动物模型,研究糖尿病疾病的发展和及其并发症的发生、发展规律和防治措施,同时对于治疗糖尿病新药的安全性评价和药物疗效的观察具有广阔的运用前景。[方法]选用成熟的、健康的、雄性恒河猴9只,随机分成三个组,其中高剂量组(60mg/kg)1只,中剂量组(45m…     

EMG and MMG of agonist and antagonist muscles as a function of age and joint angle.

The aim of this study was to determine the effect of elbow joint position on electromyographic (EMG) and mechanomyographic (MMG) activities of agonist and antagonist muscles in young and old women. Surface EMG and MMG were recorded from the triceps and biceps brachii, and brachioradialis muscles during isometric elbow extensions in young and old women. The measurements were carried out at an optimal joint angle (A(o)), as well as at smaller (A(s) = A(o) - 30 degrees ) and larger (A(l) = A(o) + 30 degrees ) angles. The normalized to force EMG amplitude (RMS-EMG/F) was smaller in old women compared to young in all muscles. The RMS-EMG/F of the triceps brachii muscle was not affected by muscle length while that of the biceps brachii and brachioradialis muscles increased at shortest muscle length in both groups. The normalized to force MMG amplitude (RMS-MMG/F) was smaller in old than in young in the triceps brachii muscle only. There was an increase in RMS-MMG/F with triceps brachii and biceps brachii muscle shortening in both groups, and in the brachioradialis muscle -- in young only. Compared to young, older women exhibited a bigger force fluctuation during maximum voluntary contraction, but these did not contribute significantly to the RMS-MMG. Skinfold thickness accounted for the RMS-EMG/F and RMS-MMG/F differences seen between old and young women in the biceps brachii muscle only. It is concluded that, the EMG and MMG response to muscles length change in agonist and antagonist muscles is generally similar in old and young women but the optimal angle shifts toward a bigger value in older women.     

Effect of opportunistic fungi on the life cycle of the root-knot nematode ( Meloidogyne javanica) on brinjal

The effect of four opportunistic fungi viz., Paecilomyces lilacinus, Cladosporium oxysporum, Gliocladium virens and Talaromyces flavus on the life cycle of the root-knot nematode, Meloidogyne javanica, on brinjal was evaluated under glasshouse conditions. The results revealed that these fungi affected the penetration and development of M. javanica. The life cycle of M. javanica was delayed by 10, 7, 4 and 2 days in the presence of P. lilacinus, C. oxysporum, G. virens and T. flavus respectively. Fecundity, number of eggs per eggmass and number of larvae was also reduced in the presence of these opportunistic fungi. However, the number of males increased in the presence of opportunistic fungi.     

Denmark between liberalism and nationalism

Abstract

What explains the restrictive turn towards immigrants in European countries like Denmark? Are countries returning to nationalism, or are they following a general European trend towards a perfectionist, even ‘repressive’ liberalism that seeks to create ‘liberal people’ out of immigrants? Recent developments in Danish policies of integration and citizenship, education and anti-discrimination suggest a combination of these two diagnoses. The current Danish ‘integration philosophy’ leaves behind a previous concern with private choice and equal rights and opportunities to emphasize other historical elements, especially the duty to participate in upholding democracy and the egalitarian welfare community, and to promote autonomous and secular ways of life. However, the virtues of this ‘egalitarian republicanism’ are seen by right-of-centre intellectuals and politicians as rooted in a wider Christian national culture that immigrants must acquire in order to become full citizens.