Influence of Custodiol on Preservation of the Isolated Rat Heart during Hypothermic Storage in a High-Pressure Gas Mixture of Carbon Monoxide and Oxygen

Biophysics - The preservation solution Custodiol was tested for effects on heart rate and contractility of the isolated rat heart following prolonged hypothermic (4°C) preservation in a...     

Effect of weak combined static and extremely low‐frequency alternating magnetic fields on tumor growth in mice inoculated with the Ehrlich ascites carcinoma

It has been shown that the ultralow‐frequency extremely weak alternating component of combined magnetic fields (MFs) exhibits a marked antitumor activity. The parameters of this component have been found (frequency 1, 4.4, 16.5 Hz or the sum of these frequencies; intensity 300, 100, 150–300 nT, respectively) at which this MF in combination with a collinear static MF of 42 µT inhibits or suppresses the growth of Ehrlich ascites carcinoma (EAC) in mice. It was shown that the exposure of mice with EAC to combined MFs causes structural changes in some organs (liver, adrenal glands), which are probably due to the total degradation of the tumor tissue. In mice with transplanted EAC, the tumor tissue after exposure to weak MFs was practically absent, as distinct from control animals in which the invasion of the tumor into the adipose tissue surrounding the kidneys, mesenteric lymph nodes, and spermatic appendages was observed. In animals without tumors, no pathological deviations from the norm in the structure of organs and tissues occurred after exposure to weak MF, indicating that this factor per se is not toxic to the organism. Bioelectromagnetics 30:343–351, 2009. © 2009 Wiley‐Liss, Inc.     

Effect of weak combined static and low-frequency alternating magnetic fields on the Ehrlich ascites carcinoma in mice

The parameters of the low-frequency (1, 4.4, 16.5 Hz or the sum of these frequencies) extremely weak (300, 100, 150–300 nT, according to frequencies) alternating component of combined magnetic fields have been found, which in combination with a weak collinear static field of 42 μT (the induction corresponds to the range of the geomagnetic field) has a marked antitumor activity. The exposure to these magnetic fields inhibits the tumor growth in mice with an intraperitoneally transplanted Ehrlich ascites carcinoma. The effect manifests itself as an increase in the life of tumor-bearing animals and in the content of damaged tumor cells. It was found that the death of tumor cells by the action of weak fields occurs predominantly by the mechanism of necrosis.     

Stressful effects of chemical toxins at low concentrations

Effects of three chemical compounds: ammonia, diethyl ether, and acetic acid, known as common environmental contaminants in technogenic accidents, were investigated in vivo and in vitro in low concentrations. When added in cultivation media, each of the chemicals has affected peritoneal macrophages and spleen lymphocytes isolated from male NMRI mice and led to a rise in the production of several cytokines, particularly the tumor necrosis factor-α and interferon-γ, as well as the expression of the inducible form of heat shock proteins (HSP72 and HSP90-α) and in the activation of signal cascades NF-κB and SAPK/JNK. The increase of the nitric oxide (NO) production in macrophages has been observed only when ammonia was added in cultivation media. Also, low concentrations of all compounds investigated led to the activation of the expression of receptor protein TLR4. When mice were exposed to airborne toxic contaminants in a hermetically sealed experimental chamber, an increase in the concentrations of cytokines, heat shock proteins, and signal proteins in immune cells was also observed in response to low concentrations of all chemicals investigated. Similarly to in vitro experiments, the NO production was augmented only in the presence of the airborne ammonia. The results indicate the environmental hazard of chemical contaminants even in rather low concentrations, which nevertheless lead to the stress response.     

An overview of models of stomatal conductance at the leaf level

Stomata play a key role in plant adaptation to changing environmental conditions as they control both water losses and CO₂ uptake. Particularly, in the context of global change, simulations of the consequences of drought on crop plants are needed to design more efficient and water‐saving cropping systems. However, most of the models of stomatal conductance (g_s) developed at the leaf level link g_s to environmental factors or net photosynthesis (A_net), but do not include satisfactorily the effects of drought, impairing our capacity to simulate plant functioning in conditions of limited water supply. The objective of this review was to draw an up‐to‐date picture of the g_s models, from the empirical to the process‐based ones, along with their mechanistic or deterministic bases. It focuses on models capable to account for multiple environmental influences with emphasis on drought conditions. We examine how models that have been proposed for well‐watered conditions can be combined with those specifically designed to deal with drought conditions. Ideas for future improvements of g_s models are discussed: the issue of co‐regulation of g_s and A_net; the roles of CO₂, absissic acid and H₂O₂; and finally, how to better address the new challenges arising from the issue of global change.     

Evolution of xyloglucan-related genes in green plants

Background  

The cell shape and morphology of plant tissues are intimately related to structural modifications in the primary cell wall that are associated with key processes in the regulation of cell growth and differentiation. The primary cell wall is composed mainly of cellulose immersed in a matrix of hemicellulose, pectin, lignin and some structural proteins. Xyloglucan is a hemicellulose polysaccharide present in the cell walls of all land plants (Embryophyta) and is the main hemicellulose in non-graminaceous angiosperms.     

The effect of ATP, GTP and cAMP on the cGMP-dependent conductance of the fragments from frog rod plasma membrane

Using a 'patch-clamp' method in the 'inside-out' configuration, ATP, ADP, AMP-PCP and AMP-PNP have been shown to increase the cGMP-dependent component of the rod plasma membrane conductance 2-4-fold and GTP, GDP but not GMP or nonhydrolyzable GTP analogs GMP-PNP and GTP-gamma-S to abolish the ATP action. The ATP and GTP effects were observed at [EDTA] = 1 mM when magnesium and calcium ions were absent. In about half of the experiments the cGMP-dependent conductance was shown to be increased by cAMP in the micromolar concentration range by 10-50%, the cAMP action did not depend on the presence of nucleoside triphosphates. In vivo ATP, GTP and cAMP are assumed to modulate the sensitivity of the photoreceptor plasma membrane to cGMP.