Possible mechanisms of anti-ulcer action of silatranes

A stimulating effect of methylethyl(silatrane-I-ilmethyl)-sulphonium iodides, 1-(ethoxy)silatranes and 1-(chloromethyl)silatrane on the processes of rat test acetate ulcer healing is studied. Silatranes efficiency is not inferior to oxyferriscorbone and exceeds that of methacil. It is shown that all preparations inhibit the processes of lipids peroxidation in the blood, in liposomes and stomach tissue.     

The radiomodifying action of ATP and ADP on membrane-bound enzymes

A modifying action of ATP and ADP on the activity of some key membrane-bound enzymes of the brain and heart microsomes of rats exposed to 7 Gy radiation has been investigated. The difference in the reactions of energy-dependent enzymes is attributed to the compensatory systems involved at the molecular level.     

Possible mechanisms of analgesic effects of low-intensity microwave radiation

Based on a review of published data and results of our own experiments, we discuss possible mechanisms of analgesic effects of low-intensity microwaves. We hypothesize that the effects of microwave irradiation can be to a considerable extent mediated by the influence on the acupuncture points, which are tentatively considered receptor structures of the electromagnetic sensory system in humans and animals.     

Possible mechanisms of action of an anti-Pasteurella pestis factor

Anti-Pasteurella pestis factor (APF) inhibited bacterial growth, but there was no evidence that APF from either mouse or guinea pig or selected fatty acids physically disrupted the cell wall. The fatty acids selected were representative of those found in APF. APF inhibited oxidation of beta-d-glucose but not oxidation of glucose-6-phosphate, whereas fatty acids inhibited the oxidation of glucose-6-phosphate but not oxidation of beta-d-glucose. The oxidation of 6-phosphogluconic acid was inhibited by both APF and free fatty acids. Furthermore, APF and potassium laurate inhibited 6-phosphogluconic dehydrogenase in a cell-free extract of P. pestis strain E.V. 76. No evidence of beta-d-glucose or glucose-6-phosphate dehydrogenases was found in the cell-free extract. The results suggested that APF and fatty acids may kill P. pestis by inactivating 6-phosphogluconic acid dehydrogenase. The effects of these agents on other enzyme systems were not excluded.     

Effect of electromagnetic radiation of the decimetric wave range on myocardium cell membranes

The decrease in the rate of lipid peroxidation and the increase in te fluorescence of chlortetracycline, bound with calcium ions absorbed on membrane surface after exposure thereof to decimeter waves, were revealed in myocardium cell membranes. Opposite changes were observed after the effect of p- chlormercuribenzoate . The effect of decimeter waves compensated the p- chlormercuribenzoate -induced changes.     

Possible mechanisms of action of growth factors and cell aging]

Main effects of growth factors (GFs) on proliferation seem to be mediated by second messengers (SMs). A variety of feed-backs in the SM system allows to suggest that cell cycling is determined by self-oscillations of levels of the SMs and SM-dependent proteins. GFs perform roles of parameter switches of the system functioning regimes; self-oscillations occur only if the GF levels are within certain range. This approach makes it possible to explain the GF synergy, dual roles of GFs as activators and inhibitors of proliferation, and cell cycle duration variability. It predicts that GFs must accelerate some cell cycle phases and decelerate other phase. When the GF levels are sharply changed, cells may become terminally differentiated, which allows to explain a limited number of cell divisions in culture. We can also explain why some oncogenes decrease the dependence of cells on GFs but cells undergo a limited number of divisions, and other oncogenes enable cells to divide unlimitedly.     

Studies on the mechanisms of the skeletal anabolic action of endogenous and exogenous parathyroid hormone

Parathyroid hormone (PTH) has been viewed as catabolic for bone. Nevertheless, exogenous PTH is anabolic when administered intermittently, at a frequency that permits complete clearance between doses. In the fetus and neonate, endogenous PTH is required for normal trabecular bone formation. In older animals PTH produces net bone loss in fulfilling its calcium homeostatic role, whereas PTH-related peptide (PTHrP), acting in a paracrine/autocrine mode, is anabolic. The proliferative, differentiating, and anti-apoptotic effects of PTH on cells of the osteoblast lineage leading to anabolism can be direct, or indirect via release of local growth factors. The anabolic effect of PTH is also influenced by osteoclastic activity such that suppression of osteoclasts with anti-resorptive agents, concomitant to administering PTH, may enhance the anabolic effect by delaying a reactive osteoclastic response. In contrast, prolonged suppression of osteoclast activity prior to administering PTH appears to diminish molecular signals that increase the osteoblast pool and thereby reduces the anabolic efficacy of PTH. These observations may define the proper timing of the use of PTH as a therapeutic in diseases of bone loss. Finally, the capacity of exogenous PTH to modulate extra-osseous factors such as 1,25 dihydroxyvitamin D may also modulate its potency as an anabolic agent.     

Mutagenic action of monochromatic UV radiation in the solar range on human cells

Mutations to ouabain resistance (selecting for base modifications at the co-dominant Na+K+-dependent ATP-ase locus) and thioguanine resistance (selecting for a wide range of genetic changes at the recessive hypoxanthine-guanine phosphoribosyl transferase locus) were measured in a repair-proficient human lymphoblastoid line with defined monochromatic radiations in the UVC (254 nm), UVB (302 nm, 313 nm), UVA (334 nm, 365 nm) and visible (405 nm) ranges. No mutations were detected at wavelengths in the range 334-405 nm. At 254 nm and 313 nm, both mutations to thioguanine resistance and survival were consistent with those expected from the relative levels of cyclobutane-type pyrimidine dimers induced. However, at 313 nm, the ratio of ouabain-resistant to thioguanine-resistant mutants is 10 times higher than at 254 nm, indicating that a unique type of pre-mutagenic base damage is induced at the longer wavelength. Radiation in the UVA (334 nm) range reduced the induction of mutations by a UVC (254 nm) wavelength at both mutation markers. These results suggest, first, that distinct types of biologically expressed genetic damage may be induced in the UVB region of sunlight and, second, that strong interactions may occur between the different wavelength regions of sunlight that can modify the expression of this genetic damage in human cells.     

Effect of electromagnetic radiation in a decimeter wave-length range on the calcium current of molluscan neurons

Microwave effect on calcium current of the dialysed snail neurons was investigated. Isolated neurons were irradiated by unmodulated and modulated microwaves (900 MHz) with modulation frequency 0,5 divided by 1000 Hz and SAR = 0,1 divided by 20 W/kg. Calcium current increase was shown to be induced by microwave heating. The current increments were proportional to SAR. Microwave effects on the charge distribution of the cell membrane surface and other non-thermal special microwave effects were not detected.     

Roles of different neurochemical systems in mechanisms underlying the antinociceptive effect of extrahigh-frequency electromagnetic radiation

We studied the effect of low-intensity extrahigh-frequency (EHF) electromagnetic radiation (EMR) on the duration of a pain behavioral reaction in rats under conditions of experimental induction of tonic pain (formalin test). The antinociceptive effect of EHF irradiation was modulated by suppression of the activity of a few neurochemical systems resulting from the blockade of receptors of opioid peptides, α-and β-adrenoreceptors, receptors of dopamine and melatonin, as well as from inhibition of serotonin synthesis. We demonstrated that all the respective neurochemical systems are to a certain extent involved in the mechanisms underlying the analgesic action of EHF EMR. Within an early phase of pain stress, functioning of the opioidergic and noradrenergic systems and the effects of melatonin play leading roles, while the activity of the serotonergic system plays such a role within the second (tonic) phase. Neirofiziologiya/Neurophysiology, Vol. 39, No. 2, pp. 165–173, March–April, 2007.     

Subcellular mechanisms of the action of weak extra-low frequency electromagnetic fields on the cerebral cortex

Electron microscopic examinations of the cerebral cortex in rabbits and rats after exposure to weak extra-low electromagnetic fields has detected ultrastructural changes whose degree in different nerve tissue elements was dependent on the duration of irradiation. Single exposure to weak extra-low electromagnetic field resulted only in the glial response of the neocortex, while multiple exposure resulted alternately in the response of glial cells or neuronal bodies. Three days after a single exposure and within 15 days after multiple exposure to electromagnetic field a complete repair of the nervous tissue was observed. No destructive or pathological alterations have been found which suggests the functional character of the reactions induced. Neuro-morphological alterations are of a similar character when induced by weak extra-low electromagnetic fields or other biophysical effects which points to common subcellular mechanisms of nonspecific adaptive reactions.     

Possible implications in the use of exogenous phospholipids.

The development of new techniques has shed more light on the physical state of phospholipids within the living cell. This has helped in the development of new concepts of the structural inter-relationship of phospholipids with proteins and other natural constituents and also of their functional role (e.g. enzyme modulators). On the other hand, understanding of phospholipid behaviour within the biological environment has encouraged research into the possibility of assigning to these molecules the role of carriers for exogenous or endogenous biologically active agents. Possible applications of this carrier potential in biology and medicine are discussed.     

The role of p38 protein kinase in mouse responses to low-intensity electromagnetic radiation of the centimeter range

The role of p38 mitogen-activated protein kinase in regulating the cell responses to ultralow-intensity centimeter microwaves (8.15–18.0 GHz, 1 µW/cm², 1 h) was studied in male BalbC mice. Mice were tested for the level of protein phosphorylation in the NF-κB (p65 and IKK), JNK, and IRF3 signaling cascades expression of TLR4 and stress-inducible heat shock proteins Hsp72 and Hsp90 in splenic lymphocytes and pro- and anti-inflammatory cytokines and IL-10 in the blood serum. An inhibitor of the p38 signaling pathway (p38 inhibitor XI) was shown to reduce the sensitivity to ultralow-intensity ultrahigh-frequency electromagnetic radiation. This was evident from a decrease in radiation-induced activation of the NF-κB signaling pathway, expression of Hsp72 and Hsp90 in splenic cells, and an accumulation of proinflammatory cytokines (IL-6, IL-17, TNF-α, and IFN-γ) in the blood serum of irradiated mice pretreated with p38 inhibitor XI. However, p38 inhibitor XI did not attenuate the activation of the p38 and IRF3 signaling pathways and overexpression of TLR4 in splenic cells of irradiated mice. It was assumed that p38 mitogenactivated protein kinase is involved in regulating the nonspecific defense responses does not determine the murine sensitivity to ultralow-intensity electromagnetic waves of the centimeter range.     

Application of exogenous melatonin in vitro and in planta: a review of its effects and mechanisms of action

Biotechnology Letters - Melatonin is a natural indolamine that regulates many physiological functions in plants. The most prominent role of melatonin in plants has been its ability to work as an...     

Effects of electromagnetic radiation in the range 20–300 MHz on the vacuolar potential of characean cells

A giant cell (circa 10 mm long) of Chara braunii or Nitella flexilis was placed in a microstrip exposure apparatus, and the vacuolar potential at one end was monitored with a micropipette while the other end was exposed to pulses of VHF radiation at electric field strengths up to 6250 V/m. With suitable filtering and signal averaging, offsets of the vacuolar potential could be detected in real time and at levels as low as 1 μU V. The only effect that has been reproducibly observed in the carrier frequency range 20–300 MHz was the slow ramp-like hyperpolarization previously reported [Pickard and Barsoum, 1981] and tentatively attributed to electromagnetic heating of the system. The slopes of these ramps became more pronounced with increasing frequency and behaved in accordance with theoretical predictions.