The Stability of a Thermocapillary-Buoyant Flow in a Liquid Bridge with Heat Transfer Through the Interface

An experimental investigation has been performed to study a supercritical flow driven by the combined effects of buoyancy and thermocapillary forces, in a non-isothermal liquid cylindrical column heated from above (liquid bridge). The liquid zone was of 3mm in radius and 2.58mm in height made of n-decane. Changing temperature of air in the experimental chamber via controlling the temperature at its external wall, the conditions at the onset of instability of the flow, as characterized by the critical value of the imposed temperature difference, were determined for several values of the liquid volume. Performing ”chaos analysis” of the obtained data, different regimes of the supercritical flow were identified. The experimental observations are supported by a computer modeling of the thermoconvective flow made for the experimental conditions neglecting deformations of the liquid-gas interface. It is shown that the spatial structure of the flow may change with external conditions in the ambient gas.     

Conjugates of Methylene Blue with Cycloalkaneindoles as New Multifunctional Agents for Potential Treatment of Neurodegenerative Disease

The development of multi-target-directed ligands (MTDLs) would provide effective therapy of neurodegenerative diseases (ND) with complex and nonclear pathogenesis. A promising method to create such potential drugs is combining neuroactive pharmacophoric groups acting on different biotargets involved in the pathogenesis of ND. We developed a synthetic algorithm for the conjugation of indole derivatives and methylene blue (MB), which are pharmacophoric ligands that act on the key stages of pathogenesis. We synthesized hybrid structures and performed a comprehensive screening for a specific set of biotargets participating in the pathogenesis of ND (i.e., cholinesterases, NMDA receptor, mitochondria, and microtubules assembly). The results of the screening study enabled us to find two lead compounds (4h and 4i) which effectively inhibited cholinesterases and bound to the AChE PAS, possessed antioxidant activity, and stimulated the assembly of microtubules. One of them (4i) exhibited activity as a ligand for the ifenprodil-specific site of the NMDA receptor. In addition, this lead compound was able to bypass the inhibition of complex I and prevent calcium-induced mitochondrial depolarization, suggesting a neuroprotective property that was confirmed using a cellular calcium overload model of neurodegeneration. Thus, these new MB-cycloalkaneindole conjugates constitute a promising class of compounds for the development of multitarget neuroprotective drugs which simultaneously act on several targets, thereby providing cognitive stimulating, neuroprotective, and disease-modifying effects.     

Photoaffinity labeling of DNA polymerase from Thermus thermophilus and DNA template by photoreactive analogs of dCTP

The aim of this study was to evaluate the influence of nicotine on the daily rhythms of heart rate, body temperature and locomotor activity in unrestrained rats by use of implanted radiotelemetry transmitters. The study was divided into three seven-day periods: a control period, a treatment period and a recovery period. The control period was used for baseline measurement of heart rate, body temperature and locomotor activity. During the treatment period three rats received nicotine (1 mg kg(-1), s.c.) at 0900 h. Three rats received saline under the same experimental conditions. Heart rate, body temperature and locomotor activity were continuously monitored and plotted every 10 min. During the three periods a power spectrum analysis was used to determine the dominant period of rhythmicity. If daily rhythms of heart rate, body temperature and locomotor activity were detected, the characteristics of these rhythms, i.e. the mesors, amplitudes and acrophases, were determined by cosinor analysis, expressed as means +/- s.e.m. and compared by analysis of variance. Nicotine did not suppress daily rhythmicity but induced decreases of amplitudes and phase-advances of acrophases for heart rate, body temperature and locomotor activity. These perturbations might result from the effects of nicotine on the suprachiasmatic nucleus, the hypothalamic clock that co-ordinates biological rhythms.     

Detection of lead in environmental objects and biologic materials during monitoring]

The authors specified methods to detect lead in biologic materials. The quality control covered use of Russian and foreign standard samples, the results proved to agree. Lead was detected by AAS technique (direct and flow-type variants with preliminary concentration of lead) and ELRA method. The authors determined measurement limits sufficient for analysis of complex biologic materials. The measurement range for lead varied from 0.002 mg/kg (plants) to 3,000 mg/kg (soil); the range of serum lead levels was < 0.5-39 mg/dl.     

Application of free-flow electrophoresis for isolation and purification of proteins and peptides

Free-flow electrophoresis (FFE) has been applied to the separation and purification of a variety of proteins and polypeptides: bee venom, tumor necrosis factor, interleukin-1beta, interferon-gamma and superoxide dismutase. FFE at constant pH and conductivity of the carrying buffer is shown to be efficient at various separation schemes. In some cases, the method allows us to obtain proteins with a purity of more than 90% at a productivity of 20-30 mg/h. An electrophoretic apparatus with a new, multi-sectional construction of the electrophoretic chamber and a system for cross-displacement of carrying buffer in the chamber is described.     

Changes in the chemotherapy sensitivity of leukemia L1210 cells during the development of diazan resistance

L 1210 leukemia strain resistant to diazan (L 1210/D1) was studied for its drug sensitivity in comparison with the parent strain. The resistant strain exhibited significantly higher sensitivity to nine drugs: dopan, sarcolysine, apirazidin, cyclophosphane, 6-mercaptopurine, thiophosphamide, rubomycin, vinblastine and vincristine. L 1210/D1 gained cross resistance to four drugs: 1-(2-chloroethyl)-3-(2, 6-dioxy-3-piperidyl)-1-nitrosourea, methotrexate, 5-fluorouracil and ftorafur. The resistant strain sensitivity remained unchanged (in comparison with the parent strain) to seven drugs: degranol, prospidin, nitrosomethylurea, chlorozotocin, deazauridine, bleomycin and L-asparaginase (crasnitine).     

The epidemiological indices of multiple myeloma and concomitant nephropathies

The authors have conducted an epidemiological study for multiple myeloma morbidity and mortality among 80,000 patients of the Medical Center examined in 1988-1995. Myeloma was diagnosed in 65 cases. Standard incidence rate was 4.09, 3.18 and 3.5 per 100,000 for myeloma in males, females and both sexes, respectively. Standard mortality was 2.76 and 1.73 per 100,000 for males and females, respectively. The above rates do not differ much from those of other countries. In terminal myeloma renal insufficiency occurred in 39 of 41 cases. In 8 cases chronic pyelonephritis was an independent course of renal failure thus indicating the importance of its persistent treatment.     

Accessibility of epitopes on UvrB protein in intermediates generated during incision of UV-irradiated DNA by the Escherichia coli Uvr(A)BC endonuclease

Structural intermediates generated during incision of damaged DNA by the Uvr(A)BC endonuclease were probed with monoclonal antibodies (mAbs) raised against the Escherichia coli UvrB protein. It was found that the epitope of B2C5 mAb, mapped at amino acids (aa) 171-278 of UvrB, is not accessible in any of the preformed Uvr intermediates. Preformed B2C5-UvrB immunocomplexes, however, inhibited formation of those intermediates. B2C5 mAb seems to interfere with the formation of the UvrA-UvrB complex due to overlapping of its epitope and the UvrA binding region of UvrB. Conversely, the epitope of B3C1 mAb (aa 1-7 and/or 62-170) was accessible in all Uvr intermediates. The epitope of B*2E3 mAb (aa 171-278) was not accessible in any of the nucleoprotein intermediates preceding UvrB-DNA preincision complex. However, B*2E3 was able to immunoprecipitate this complex and to inhibit overall incision. B2A1 mAb (aa 8-61) inhibited formation of those Uvr intermediates requiring ATP binding and/or hydrolysis by UvrB. B*2B9 mAb (aa 473-630) inhibited Uvr nucleoprotein complexes involving UvrB. B*2B9 seems to prevent the binding of the UvrA-UvrB complex to DNA. The epitope of the B*3E11 mAb (aa 379-472) was not accessible in Uvr complexes formed at damaged sites. These results are discussed in terms of structure-functional mapping of UvrB protein.