Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (statins) have been proven to reduce effectively cholesterol level and morbidity and mortality in patients with coronary heart disease and/or dyslipoproteinemia. Statins inhibit synthesis of mevalonate, a precursor of both cholesterol and coenzyme Q (CoQ). Inhibited biosynthesis of CoQ may be involved in some undesirable actions of statins. We investigated the effect of simvastatin on tissue CoQ concentrations in the rat model of NO-deficient hypertension induced by chronic L-NAME administration. Male Wistar rats were treated daily for 6 weeks with L-NAME (40 mg/kg) or with simvastatin (10 mg/kg), another group received simultaneously L-NAME and simvastatin in the same doses. Coenzyme Q9 and Q10 concentrations were analyzed by high performance liquid chromatography. L-NAME and simvastatin alone had no effect on CoQ concentrations. However, simultaneous application of L-NAME and simvastatin significantly decreased concentrations of both CoQ homologues in the left ventricle and slightly decreased CoQ9 concentration in the skeletal muscle. No effect was observed on CoQ level in the liver and brain. We conclude that the administration of simvastatin under the condition of NO-deficiency reduced the level of CoQ in the heart and skeletal muscle what may participate in adverse effect of statins under certain clinical conditions., J. Kucharská, A. Gvozdjáková, F. Šimko., and Obsahuje bibliografii
How the photosynthetic characteristics of insect-resistant transgenic cotton (Gossypium hirsutum L.) respond to light or whether this genetic transformation could result in unintended effects on their photosynthetic and physiological processes is not well known. Two experiments were conducted to investigate the shapes of net photosynthetic rate (P N), stomatal conductance (g s), apparent light use efficiency (LUEapp) and water use efficiency (WUE) light-response curves for single leaves of Bt (Bacillus thuringiensis) and Bt+CpTI (cowpea trypsin inhibitor) transgenic cotton plants and their non-transgenic counterparts, respectively. Results showed that the significant difference in response of P N and WUE to light between transgenic cotton and non-transgenic cotton occured but not always throughout the growing season or in different experiments or for all transgenic cotton lines. It was highly dependent on growth stage, culture condition and variety, but no obvious difference between any transgenic cotton and non-transgenic cotton in the shapes of g s and LUEapp light-response curves was observed in two experiments at different growth stages. In the field experiments, transgenic Bt+CpTI cotton was less sensitive to response of P N to high irradiance at the boll-opening stage. In pot experiments, WUE light-response curves of both Bt transgenic cotton and Bt+CpTI transgenic cotton progressively decreased whereas non-transgenic cotton slowly reached a maximum at high irradiance at boll-opening stage. We supposed that culture environment could affect the photosynthesis of transgenic cotton both directly and indirectly through influencing either foreign genes expression or growth and physiological processes. and C. X. Sun ... [et al.].
Single potassium channels in the membrane of human malignant glioma cells U-118MG were studied using the technique of patch clamp in cell-attached and inside-out configurations. Three types of potassium channels were found which differed from each other under conditions close to physiological in their conductance and gating characteristics. The lowest-conductance channel (20 pS near the reversal potential) showed a mild outward rectification up to 45 pS at positive voltages and spontaneous modes of high and low activity. At extreme values of potentials its activity was generally low. The intermediate conductance channel had an S-shaped I-V curve, giving a conductance of 63 pS at reversal, and a low and voltage independent opening probability. The high-conductance (215 pS) channel was found to be activated by both membrane potential and Ca2+ ions and blocked by internal sodium at high voltages. The current-voltage curves of all three channel types displayed saturation.
This paper compares the level of neighbourhood cohesion of two single-access neighbourhoods in Calgary, Alberta. The two neighbourhoods had a high sense of neighbourhood cohesion. It is argued that the single access to the neighbourhood has contributed to a high sense of neighbourhood cohesion. One neighbourhood outperformed the other on all three subscales of cohesion due to a stronger sense of seclusion of the neighbourhood. Establishing a sense of identity, a focus, and a clear boundary for a neighbourhood is paramount. At the same time, visionary planning for the future of neighbourhood design with a view to an easy and flexible redevelopment of the open-grid model seems to dominate the mindset of municipal planners operating under the banner of sustainability.
A problem of measuring tilt around a single axis is discussed in detail with regard to the resultant accuracy. Ways of improving the accuracy, based on application of various mathematical equations, are proposed. Presented results of related experimental studies, performed on a tilt sensor made of a standard MEMS accelerometer, have proven that it is possible to obtain accuracy of such measurements of ca. 0.2 degrees arc. Additionally, a problem of measuring tilt of an object, which rotates within a non-vertical plane, is addressed. and Obsahuje seznam literatury
The earlier developed double-modulation chlorphyll (Chl) fluorometer was modified for measurements with intact leaves of higher plants. The Chl fluorometer is based on a non-periodic modulation of both actinic and measuring flashes. In addition, continuous orange actinic and far-red radiation were produced by separate arrays of light-emitting diodes (LEDs). Programmable timing of the flashes allows to cover a wide dynamic range from microseconds to minutes. We have demonstrated that the LEDs can produce single-turnover flashes that saturate QA reduction of intact leaves of Glyceria maxima and shoots of Picea abies. and O. Urban ... [et al.].