Distribution,phosphorylation, and activities of Hsp25 in heat-stressed H9c2 myoblasts: a functional link to cytoprotection

The behavior of the endogenous heat shock protein 25 (Hsp25) in heat-stressed rat H9c2 myoblasts was studied. After mild or severe heating, this protein became less extractable with Triton X-100 and displayed characteristic immunofluorescence patterns, namely (1) granules in the nucleus, and (2) association with F-actin bundles in the cytoplasm. The intranuclear granulation of Hsp25 and its association with F-actin were sensitive to drugs affecting Hsp25 phosphorylation (cantharidin, sodium orthovanadate, SB203580, SB202190). Isoform analysis of Hsp25 translocated to the nucleus-free cytoskeletal fraction revealed only mono- and biphosphorylated Hsp25 and no unphosphorylated Hsp25. Transfected luciferase with initial localization in the nucleosol became colocalized with the Hsp25-containing granules after a heat shock treatment that denatured the enzyme in the cells. The association of Hsp25 with actin filaments after a mild heat stress conferred protection from subsequent F-actin-damaging treatments with cytochalasins (D and B) or severe heat stress. We hypothesize that (1) the binding of heat-denatured nucleosolic proteins to the Hsp25 contained in specific granular structures may serve for the subsequent chaperoning or degradation of the bound proteins, and (2) the actin cytoskeleton is stabilized by the direct targeting of phosphorylated Hsp25 to microfilament bundles.     

Changes in estuarine nematode communities following a decrease of organic pollution

The response of a nematode community to a decreasing organic matter loading was studied. Monthly observations were made at three stations at an intertidal brackish-water mudflat in the Ems estuary in 1980 (highly polluted), 1987 (moderately polluted) and 1993 (no significant pollution). Nematodes were identified and counted in the upper 1 cm of the sediment.The decrease of organic pollution was followed by an increase in species diversity, whereas numerical densities decreased. Diatom eating nematodes, being dominant under eutrophic conditions in 1980, decreased strongly, partly as a consequence of decreasing diatom standing stock. Eudiplogaster pararmatus, an indicator of organic enrichment, decreased strongly to disappear completely in 1993. Bonger's maturity index was used to describe the response of the nematode community. At 2 most polluted stations a strong response was observed from 1980 to 1987: a decrease of colonizer species. After 1987, although persister species increased, no further development towards a more natural succession type community occurred, probably due to the natural stress of the habitat (high mudflat, low salinities).     

The European General Practice Research Network Presents the Translations of Its Comprehensive Definition of Multimorbidity in Family Medicine in Ten European Languages

Background

Multimorbidity, according to the World Health Organization, exists when there are two or more chronic conditions in one patient. This definition seems inaccurate for the holistic approach to Family Medicine (FM) and long-term care. To avoid this pitfall the European General Practitioners Research Network (EGPRN) designed a comprehensive definition of multimorbidity using a systematic literature review.

Objective

To translate that English definition into European languages and to validate the semantic, conceptual and cultural homogeneity of the translations for further research.

Method

Forward translation of the EGPRN’s definition of multimorbidity followed by a Delphi consensus procedure assessment, a backward translation and a cultural check with all teams to ensure the homogeneity of the translations in their national context. Consensus was defined as 70% of the scores being higher than 6. Delphi rounds were repeated in each country until a consensus was reached

Results

229 European medical expert FPs participated in the study. Ten consensual translations of the EGPRN comprehensive definition of multimorbidity were achieved.

Conclusion

A comprehensive definition of multimorbidity is now available in English and ten European languages for further collaborative research in FM and long-term care.     

Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels

In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters (n = 11) and endurance athletes (n = 12) in not-specifically trained muscle (biceps brachii) during prolonged dynamic exercises at low forces. sEMG was acquired during 4 min’ exercises: unloaded, 5%, 10% and 20% of maximal voluntary contraction (MVC). The features extracted from the sEMG were: the mean muscle conduction velocity – estimated using the inter-peak latency and cross-correlation methods, the within-subject skewness (expressing the proportions of faster and slower propagating MUPs) and the within-subject standard deviation of MUP velocities (SD-mup). Sprinters showed a greater proportion of faster propagating MUPs than endurance athletes. During fatigue, the SD-mup of sprinters broadened progressively, whereas that of endurance athletes did not. The findings suggest that sprinters conveyed a greater proportion of faster motor units than endurance athletes and that motor unit behavior during fatigue differed between groups. Thus, the distribution of MUP velocities enables distinction between a muscle of sprinters and endurance athletes during prolonged dynamic exercises at low forces.     

Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during short static contractions at low force levels

In surface electromyography (sEMG), the distribution of motor unit potential (MUP) velocities has been shown to reflect the proportion of faster and slower propagating MUPs. This study investigated whether the distribution of MUP velocities could distinguish between sprinters and endurance athletes in not-specifically trained muscle (biceps brachii). sEMG results were acquired from 15 sprinters and 18 endurance athletes during short static contractions (3.8 s) at three force levels: unloaded, 10% and 20% of maximum voluntary contraction. The features extracted from the sEMG were: the mean muscle conduction velocity (CV) – estimated using the inter-peak latency and the cross-correlation methods, the within-subject skewness of MUP velocities (expressing the relative proportions of faster and slower propagating MUPs), and the within-subject standard deviation of MUP velocities. Sprinters had a higher CV than endurance athletes using both methods. Sprinters also demonstrated a greater proportion of fast propagating MUPs, as indicated by the skewness. Thus, the distribution of MUP velocities was able to demonstrate physiological differences between sprinters and endurance athletes during short contractions at low forces. The findings can be extrapolated to the motor unit level. Since the investigated muscle was not involved in specific training, the differences seem to reflect inherited properties.     

Adaptive responses in eye-head-hand coordination following exposures to a virtual environment as a possible space flight analog

Virtual reality environments (VRs) offer unique training opportunities, particularly for training astronauts and preadapting them to the novel sensory conditions of microgravity. The purpose of the current research was to compare disturbances in eye-head-hand (EHH) sensorimotor coordination produced by repeated exposures to VR systems. In general, we observed significant increases in position errors for both horizontal and vertical targets. The largest decrements were observed immediately following exposure to VR and showed general recovery within 6 hours across each test session, but not across days. Subjects generally showed faster reaction times across days. These findings provide some direction for developing training schedules for VR users that facilitate adaptation and support the idea that VRs may serve as an analog for sensorimotor effects of spaceflight.     

Global transcriptional responses of fission and budding yeast to changes in copper and iron levels: a comparative study

Background  

Recent studies in comparative genomics demonstrate that interspecies comparison represents a powerful tool for identifying both conserved and specialized biologic processes across large evolutionary distances. All cells must adjust to environmental fluctuations in metal levels, because levels that are too low or too high can be detrimental. Here we explore the conservation of metal homoeostasis in two distantly related yeasts.     

Crystal structure of quinone‐dependent alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes. A versatile dehydrogenase oxidizing alcohols and carbohydrates

The quinone‐dependent alcohol dehydrogenase (PQQ‐ADH, E.C. 1.1.5.2) from the Gram‐negative bacterium Pseudogluconobacter saccharoketogenes IFO 14464 oxidizes primary alcohols (e.g. ethanol, butanol), secondary alcohols (monosaccharides), as well as aldehydes, polysaccharides, and cyclodextrins. The recombinant protein, expressed in Pichia pastoris, was crystallized, and three‐dimensional (3D) structures of the native form, with PQQ and a Ca²⁺ ion, and of the enzyme in complex with a Zn²⁺ ion and a bound substrate mimic were determined at 1.72 Å and 1.84 Å resolution, respectively. PQQ‐ADH displays an eight‐bladed β‐propeller fold, characteristic of Type I quinone‐dependent methanol dehydrogenases. However, three of the four ligands of the Ca²⁺ ion differ from those of related dehydrogenases and they come from different parts of the polypeptide chain. These differences result in a more open, easily accessible active site, which explains why PQQ‐ADH can oxidize a broad range of substrates. The bound substrate mimic suggests Asp333 as the catalytic base. Remarkably, no vicinal disulfide bridge is present near the PQQ, which in other PQQ‐dependent alcohol dehydrogenases has been proposed to be necessary for electron transfer. Instead an associated cytochrome c can approach the PQQ for direct electron transfer.