Neuromuscular adaptation after repeated exposure to whole-body cryotherapy (−110 °C)

The aim of the study was to evaluate the effects of single and repeated whole-body cryotherapy (WBC, air −110 °C) on the neuromuscular performance in healthy subjects (n=14). The flight times in a drop-jump exercise decreased after a single WBC exposure, but these changes almost vanished after repeated WBC for 3 months. This adaptation was accompanied by a decreased co-contraction of lower leg muscles during the drop-jump. In conclusion, in dynamic exercise, neuromuscular functioning may be able to adapt to repeated WBC, which might enhance the effects of therapeutic exercises in patients after the WBC.     

Climate change-driven elevational changes among boreal nocturnal moths

Oecologia - Climate change has shifted geographical ranges of species northwards or to higher altitudes on elevational gradients. These changes have been associated with increases in ambient...     

2-Chloro-2′-deoxyadenosine: Synthesis and Antileukemic Activity of 8-Substituted Derivatives

Abstract

A series of 8-substituted 2-chloro-2′-deoxyadenosine (2-CdA, 1) derivatives were prepared as potential anticancer agents. They were synthesized stereoselectively by the anion glycosylation of 2,6,8-trichloropurine or obtained by nucleophilic displacement reactions on 8-bromo-2-chloro-2′-deoxyadenosine (3). Within the 8-substituted CdA derivatives the 8-thioxo compound 11 was cytotoxic to several leukemia cell lines.     

Transfer RNA changes in rat granulation tissue possibly related to collagen synthesis

Transfer RNAs for glycine, proline, lysine, serine and leucine were compared in developing rat granulation tissue 6 and 15 days after sterile subcutaneous implantation of pieces of cellulose sponge. The acceptance of glycine, proline and lysine by unfractionated tRNAs were ca. 30 per cent greater in tRNA derived from 15-day granulation tissue, whereas those of serine and leucine were unaltered. Cochromatography on benzoylated DEAE-cellulose of the ³H- and ¹⁴C-labeled aminoacyl-tRNAs from the two sources revealed a significant increase in the relative amount of one of the three glycyl-tRNA fractions in the 15-day granulation tissue, whereas the elution profiles for prolyl-, lysyl-, seryl-, and leucyl-tRNAs were unaltered. The changes observed suggest a causal relation to the enhanced synthesis of collagen in the late-stage granulation tissue.     

Regulation of putrescine metabolism in Ehrlich ascites carcinoma cells exposed to hypotonic medium

When exposed to hypotonic growth medium, Ehrlich ascites carcinoma cells showed a rapid stimulation of ornithine decarboxylase (EC 4.1.1.17) activity in 4 h, followed by a rise in their putrescine content. This effect was totally abolished by addition of a slightly hypertonic concentration of sodium chloride or sucrose to the medium. The general protein synthesis was unaffected by the hypotonic treatment. The uptake of putrescine and, to a lesser extent, spermidine was enhanced, and the conversion of the radioactive putrescine into spermidine appeared partially inhibited during later stages of the hypotonic treatment. As a result, the half-life of putrescine increased from 2.8 h under isoosmotic conditions to 7.3 h in hypoosmotic medium. Both exogenous ([¹⁴C]-putrescine-derived) and endogenous ([¹⁴C]ornithine-derived) putrescine degraded at similar rates in control and hypotonic cells, yet the putrescine taken from the medium degraded preferably to nonpolyamine products, while the putrescine synthesized in the cell was converted evenly to spermidine and to other metabolites. Adenosylmethionine decarboxylase activity (EC 4.1.1.50), which provides the second precursor for spermidine and spermine synthesis, was distinctly inhibited in the hypotonic medium. Inhibition was likewise observed in spermidine synthase activity, while spermine synthase was marginally stimulated. It appears that the hypotonic treatment serves a special condition under which not only the formation of putrescine is enhanced dramatically but the cells also attempt to conserve the diamine by preventing its further metabolism to higher polyamines.     

Island biogeography of North European parthenogenetic Lumbricidae: I. Clone pool affinities and morphometric differentiation of Åland populations

Genetic and morphometnc differences between island (Åland) and mainland (Sweden, Finland and Estonia) populations of five parthenogenetic and ecologically different Lumbricidae species were studied by means of enzyme electrophoresis and morphometric analysis Affinities of clones to the mainland populations show that the postglacial rates of clone flow to Åland differ widely among species In Octolasion cyaneum, the only clone found on Åland is not related to any of the studied clones from the nearby mainlands The Åland population evidently originates from one long dispersal jump through human agency The Åland clone pool of the anthropochorous Aporrectodea rosea is rich As many as 98% of the worms and 82% of the clones belong to genotypes found in the mainland populations Åland is an intergradation zone of A rosea clones that have arrived from the west (Sweden) and from the east (Finland and Estonia) The more intense cultural connections to Sweden explain the higher clonal affinities that A rosea in Åland shows to the west than to the east There are not many Octolasion tyrtaeum clones on Åland The few that are present are mainly clones also found on the mainlands On Åland Eisemella tetraedra has extensive diversity but low clonal affinities to the mainland populations This also holds true for Dendrobaena octaedra but clonal affinities are on an average higher than in E tetraedra The Aland clone pool of D octaedra shows more affinities to Finland than to the other mainlands Probably the main factor that has facilitated D octaedra clone flow from Finland is a continuous archipelago In most species there are at least some clones that are more abundant on Åland than on the mainlands They may have a wider niche in the island environment The Åland populations of A rosea, O tyrtaeum and D octaedra differed particularly in somatic traits from the mainland populations The secondary reproductive traits of the parthenogens on Åland did not differ from the mainland populations We conclude that except for O cyaneumÅland has a role as a stepping stone island in the postglacial dispersal of parthenogenetic earthworms across the Baltic Sea Different rates of flow by immigrant clones from the surrounding mainland populations have resulted in very dissimilar clone pool structures even on the same island The Åland populations also show some morphometric differences to the mainland populations