Potassium polytitanate gas-sensor study by impedance spectroscopy.

Nanocrystalline potassium polytitanates K2O·nTiO2·mH2O represent a new type of semiconducting compounds which are characterized by a high specific surface that makes them promising for use in gas sensors. In this work, we have studied potassium polytitanate mesoporous nanoparticle agglomerates placed over a SiO2/Si substrate equipped with multiple coplanar electrodes to measure the electrical response to various organic vapors, 1000 ppm of concentration, mixed with air by impedance spectrometry in range of the 10(-2)-10(6) Hz. The recorded impedance data for each sensor segment are associated with RC components of an equivalent circuit which are applied to selectively recognize the test vapors exploiting a "multisensor array" approach.

[The effect of temperature on the growth of the promastigotes of different species of Leishmania]. / Vliianie temperatury na rost promastigot leishmanii raznykh vidov.

The specific growth rate (r), the time of reduplication (T), reproduction rates (k) and the duration of the exponential phase (E) of L.major (L.m.), L.turanica (L.t.), and L.gerbilli (L.g.) are different from one another. It is shown that they differently depend on the temperature. Temperature has the greatest influence on L.g and the least on L.m. and its intermediate influence on L.t. The growth of long-term cultivation strains depends on the temperature than that short-term ones. It is associated with the adaptation rate of leishmania promastigotes to the growth in the nutrient medium. The optimum temperatures are defined for reproduction of the three species.

[A comparison of the growth of Leishmania major, L. turanica and L. gerbilli on NNN medium]. / Sravnenie rosta Leishmania major, L. turanica i L. gerbilli na srede NNN.

Leishmania promastigotes grew in the NNN medium with medium-199 as a liquid phase. The NNN medium was prepared with agar bases of the following firms: Sigma, Oxoid, Difco, Medbioprom (Russia). Growth characteristics were examined with the following indices: specific growth rate (r), reduplication time (T), reproductive rate (k). The investigations have shown that the kind of agar base has the most influence on the r and T of L.turanica and L.gerbelli and on the k of L.major. The greatest differences of the r and T of 3 species were found when the Sigma agar base was used. The kinds of agar bases were selected for long-term cultivation and biomass growing. The ways of Leishmania adaptation to growth in different media were discussed.

[The isoenzyme identification of Leishmania isolates taken from greater gerbils, sandflies and human patients in foci of zoonotic cutaneous leishmaniasis in Turkmenistan]. / Izoénzimnaia identifikatsiia izoliatov leishmanii, vydelennykh ot bol'shikh peschanok, moskitov i bol'nykh liudei v ochagakh zoonoznogo kozhnogo leishmanioza v Turkmenistane.

In 1991-1992, 230 isolates were obtained in the Tedzhen oasis and its adjacent desert areas: 172 isolates from great gerbils, 39 from P. papatasi, and 19 from human cutaneous leishmaniasis patients. All the isolates were identified by the isoenzyme polyacrylamide gel electrophoresis by 8 enzymes. The characteristics of Leishmania circulation in the hyperendemic foci of Turkmenistan were similar to those previously studied in the mesoendemic areas of Uzbekistan and Kazakhstan. L. turanica which is non-pathogenic for man prevailed among infected great gerbils in winter, spring, and early summer, making the natural foci epidemiologically safe in that period of time. It was only in August-September that the great gerbil infection rate by L. major appeared to increase, occasionally reaching 100%. Epizootics due to L. major are developing in the presence of L. turanica, therefore most isolates are clone mixtures of L. major and L. turanica. P. papatasi is the only vector in the Tedzhen oasis; there has been strong evidence for its transmission of both L. major and L. turanica, which makes the concept inconsistent that P. papatasi is associated only with L. major. The overall analysis of recent findings of the distribution of L. major in the populations of great gerbils makes it possible to limit the former endemic zoonotic cutaneous leishmaniasis areas to 40 degrees N latitude and the southern borders of Turkmenistan and Uzbekistan. Within this area, the distribution of L. major is uneven and associated basically with rivers, valleys, oases, and foothill desert plains.

[The identification of marker strains of Leishmania major, L. turanica and L. gerbilli by the polymer chain reaction with a universal primer]. / Identifikatsiia markernykh shtammov Leishmania major, L. turanica, L. gerbilli metodom polimeraznoi tsepnoi reaktsii s universal'nym praimerom.

The Leningrad Nuclear Physics Institute, Academy of Science of the USSR, and Martsinovskii Institute of Medical Parasitology and Tropical Medicine, USSR Ministry of Health, developed polymerase chain reaction (PCR) technique with universal primer 3-2 for Leishmania identification. The primers were patented in the USSR (Patent No 4757254, 1989). Reference strains of three Leishmania species were identified: L. major--MRHO/SU/59/Neal P; L. gerbilli--MRHO/CN/60/gerbilli; L. turanica--MRHO/SU/80/Cl 3720 and MRHO/SU/83/KD 051. Each Leishmania species is specific and different in its PCR pattern whereas the two L. turanica strains have identical PCR patterns of the given primer.

[Occurrence of atypical histamine H2 receptors in the wall of the frog subclavian vein]. / O sushchestvovanii atipichnykh H2-gistaminovykh retseptorov v stenke podkliuchichnoi veny liagushki.

Selective H2-histamine agonist dimaprit was shown to produce relaxation of the isolated frog subclavian vein, with it persisting under the effect of selective H2-histamine antagonist cimetidine. Possible nonspecific mechanisms of relaxation produced by histamine are discussed. The data presented do not exclude that there are atypical H2-histamine receptors in subclavian vein of frogs, the activation of which initiates the attenuation of the active tension.

[Effect of activation of alpha- and beta-adrenergic receptors, M-cholinergic receptors and H1-histamine receptors on mechanical tension in the frog subclavian vein]. / Vliianie aktivatsii alpha- i beta-adreno-, M-kholino- i H1-gistaminovykh retseptorov na mekhanicheskoe napriazhenie podkliuchichnoi veny liagushki.

The effects of adrenaline, noradrenaline, isoproterenol, dopamine, histamine, acetylcholine, and serotonin on the wall tension in the isolated frog subclavian vein and modification of these effects by appropriate antagonists were examined. The existence of alpha- and beta-adreno-, M-choline- and H1-histamine receptors was demonstrated. Stimulation of alpha-adreno- and H1-histamine receptors augments and that of beta-adreno- and M-cholinoreceptors diminishes active wall tension in the vein.