The role of cytoplasmic [Ca2+] in glucose-induced inhibition of respiration and oxidative phosphorylation in Ehrlich ascites tumour cells: a novel mechanism of the Crabtree effect

The effect of Ca2+ on energy-coupling parameters of Ehrlich ascites carcinoma was studied in digitonin-permeabilized cells. In nominally Ca-free medium the permeabilized cells respond to the addition of ADP by increased oxygen uptake with externally added respiratory substrates (succinate or pyruvate), decrease of the mitochondrial membrane potential (delta psi) and alkalinization of the medium. This typical behaviour is drastically changed if Ca2+ is added. The subsequent addition of ADP induces neither State 3 respiration, nor decrease of delta psi, nor alkalinization of the medium, indicating a complete block of ATP synthesis. These effects are produced by both a single pulse of 100 microM Ca2+ and a preincubation for 2 min with 0.4-1.0 microM Ca2+. Preincubation of the cells with glucose or deoxyglucose prior to permeabilization makes them sensitive to Ca2+ concentrations as low as 0.3 microM. In view of the previous finding that glucose and deoxyglucose produce an increase of cytoplasmic [Ca2+] in Ehrlich ascites cells [Teplova VV. Bogucka K. Czyz A. Evtodienko YuV. Duszyński J. Wojtczak L. (1993) Biochem. Biophys. Res. Commun., 196, 1148-1154; Czyz A. Teplova VV. Sabala P. Czarny M. Evtodienko YuV. Wojtczak L. (1993) Acta Biochim. Polon., 40, 539-544], the present results suggest that cytoplasmic Ca2+ plays a crucial role in the Crabtree effect.     

Effects of cumene hydroperoxide on the Ca(2+)-induced Ca2+ efflux from mitochondria and on the viability of hepatoma cells

We studied the expression of hyaluronan binding proteins (HABPs) during the development of embryonic chick joints, using immunocytochemistry and biotinylated HA. The expression of actin capping proteins and of actin itself was also studied because the cytoskeleton is important in controlling HA-HABP interactions. Three cell surface HABPs were localized in the epiphyseal cartilage, articular fibrocartilage, and interzone that comprise the developing joint. Of these three HABPs, CD44 was associated with the articular fibrocartilages and interzone, whereas RHAMM and the IVd4 epitope were associated with all three tissues. Biotinylated HA was localized to interzone and articular fibrocartilages before cavity formation and within epiphyseal chondrocytes post cavitation. Actin filament bundles were observed at the developing joint line, as was the expression of the actin capping protein moesin. Manipulation of joint cavity development, using oligosaccharides of HA, disrupted joint formation and was associated with decreases in CD44 and actin filament expression as well as decreased hyaluronan synthetic capability. These results suggest that HA is actively bound by CD44 at the developing joint line and that HA-HABP interactions play a major role in the initial separation events occurring during joint formation.     

Design of a Multistep Phase Mask for High-Energy Terahertz Pulse Generation by Optical Rectification

A new scheme for generating high-energy terahertz (THz) pulses based on using a multistep phase mask (MSPM) is suggested and analyzed. The mask is placed on the entrance surface of the nonlinear optical (NLO) crystal eliminating the necessity of the imaging optics. In contrast to the contact grating method, introduction of large amounts of angular dispersion is avoided. The operation principle of the suggested scheme is based on the fact that the MSPM splits a single input beam into many smaller time-delayed “beamlets,” which together form a discretely tilted-front laser pulse in NLO crystal. The analysis of THz-pulse generation in ZnTe and lithium niobate (LN) crystals shows that application of ZnTe crystal is more preferable, especially when long-wavelength pump sources are used. The dimensions of the mask’s steps required for high-energy THz-pulse generation in ZnTe and LN crystals are calculated. The optimal number of steps is estimated, taking into account individual beamlet’s spatial broadening and problems related to the mask fabrication. The proposed method is a promising way to develop high-energy, monolithic, and alignment-free THz-pulse sources.     

Open fire ovens and effects of in-home lavash bread baking on carbon monoxide exposure and carboxyhemoglobin levels among women in rural Armenia

Lavash is a traditional flatbread commonly baked at home by women in Armenia and other Middle Eastern and Caucasus countries. The baking process follows centuries' old recipes and is done primarily in open fire ovens. Data are limited regarding the impact of baking on indoor air quality and health outcomes. This study aimed at assessing the effects of lavash baking on household air pollution and cardiovascular outcomes among women who bake lavash in rural Armenia. A convenience sample of 98 bakers, all women, never-smokers, representing 36 households were enrolled. Carbon monoxide (CO) concentrations and carboxyhemoglobin (COHb) levels were monitored before, during, and/or after baking. As expected, exposure to concentrations of CO peaking at/or above 35-ppm during baking was more likely to occur in homes with fully enclosed and poorly ventilated baking rooms, compared to those with three or fewer walls and/or one or more windows. Bakers in homes where CO concentrations peaked at/or above 35-ppm were more likely to have an increase in post-baking COHb levels compared to those in homes with lower CO concentrations.     

Coherence analysis of the electrical activity of the rabbit brain in the presence of a hunger dominant

Abnormal uptake of atherogenic substances and lipid infiltration have been believed to contribute to the localized genesis and development of atherosclerosis, as well as to late failures of synthetic arterial prostheses. To verify the theoretical prediction that accumulation of lipoproteins on the luminal surface of arterial walls occurs in the regions of disturbed flow, we have carried out an in vitro mass transfer experiment to test the effect of a pseudo steady recirculation flow on the uptake of 3H-7-cholesterol by the arterial wall at a surgically created stenosis. It was found that, as predicted by the theory, in the flow field of the stenosis the uptake of labeled cholesterol reached a maximum around the reattachment point of the vortex distal to the stenosis, where the wall shear stress was lowest (zero). This value of the highest uptake rate was almost twice the average, whereas the uptake level was at a minimum at the stenosis itself where the wall shear stress was highest. The lowest uptake was only 60% of the average. These results provide strong support to our hypothesis, based upon the theory that, in addition to the flow induced changes to the biologic function of endothelial cells, the disturbed flow with slow recirculation itself favors the accumulation of atherogenic lipoproteins at the blood-endothelium boundary, therefore playing an important role in the localized pathogenesis and development of atherosclerosis.     

The evolution of pellet size and shape during spheronisation of an extruded microcrystalline cellulose paste

The process by which cylindrical rods of soft solid paste extrudate are converted into round pellets on a spheroniser (Marumeriser™) plate was studied by interrupting spheronisation tests and measuring the size and shape of the pellets. Batches of 20 identical rods (20 mm long, 3 mm diameter) generated by ram extrusion of 47 wt% microcrystalline cellulose/water paste were spheronised at rotational speeds, ω, between 1200 rpm and 1800 rpm on a laboratory spheroniser. The time to complete spheronisation was found to scale with ω^−3.6, which was close to the ω⁻³dependency predicted by a simple collision model. Breakage occupied the first 10% of the process duration: rounding off was the rate-determining step. The evolution of pellet shape was classified into five stages, the duration of which was found to scale with spheronisation time. Pellet shape, quantified by aspect ratio, circularity, shape and angularity factors presented by Sukumaran and Ashmawy (2001), showed similar behaviour for all ω studied. A phenomenological model is proposed which identifies different routes for small and large rod breakage products.     

Linear energy transfer spectra of cosmic radiation aboard the Cosmos-1129 satellite

The most important characteristic of the hazard due to cosmic radiation is the spectrum of linear energy transfer (LET), which enables one to estimate the dose equivalent. This has prompted us to study LET spectra of cosmic radiation aboard Cosmos-1129 using nuclear emulsions as a threshold detector.     

Initiation of the phosphoinositide cycle by parathyroid hormone in synaptosomes

We studied the effects of parathyroid hormone 10(-9) M) on the contents of mono-, di-, and triglycerides, total phospholipids, and free arachidonic acid in rat brain cortex synaptosomes using [1-(14)C]arachidonic acid at 2, 5, and 10 sec after addition of the hormone. Our data demonstrated the changes in lipid metabolism in synaptosomal membranes which were especially pronounced at 5 sec after addition of parathyroid hormone. Incorporation of 70% of [1-(14)C]arachidonic acid into the phosphoinositide fraction and the progress of changes in lipid metabolite composition suggest that the phosphoinositide cycle is initiated by parathyroid hormone, and the hormonal signal may be subsequently mediated in nerve cells by 1,2-diacylglycerol, a product of the phosphoinositide cycle.