Effectiveness of cefotaxime in experimental plague infection]

Cefotaxime was shown highly efficient in prophylaxis and treatment of experimental plague infection in albino mice. The in vitro activity of cefotaxime against natural strains of the plague microbe was 32 to 64 times higher than that of cefazolin, cephalothin and cefmetazole. The combined use of cefotaxime with amikacin significantly increased the percentage of the survived albino mice with plague infection as compared to the use of the antibiotics alone.     

A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.      

Direct selection of Aspergillus terricola variants having different toxicity on a culture of fibroblasts

A direct method is proposed to select less toxic mutants of Aspergillus terricola on a culture of fibroblasts. The conidia are first irradiated with UV, and then are used to grow colonies on the glass surface of tubes or flasks containing medium 199. The cells of fibroblasts are added thereupon and the two cultures are being grown together for 24--48 hours. The colonies which inhibit the growth of fibroblasts to a less extent are selected using microscopy. The method can be used for primarily selection of experimentally produced mutants of Aspergillus which form fibrinolytic enzymes possessing low toxicity.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Paleoclimatic potential of the northernmost juniper trees in Europe

In late summer 2004 stem discs were collected from about 40 juniper trees (Juniperus Siberica Burgsd) growing at the remote central part of Kola Peninsula behind the polar circle at the northern timberline. Up to now these juniper trees are oldest ones found at Kola Peninsula. Data processing was difficult due to extremely small tree rings as well as the occurrence of missing and false rings. However, finally it was possible to build up a 676-year long chronology and retrieve information on the past climatic variations at Kola Peninsula that could partly be linked to extraterrestrial factors such as changes in solar activity and galactic cosmic ray activity. It was obtained that:

(1) There is a rather good agreement between long-term climatic variation in Europe and at Kola Peninsula.

(2) The minima of solar activity Sporer (1416–1534 AD), Maunder (1645–1715 AD) and Dalton (1801–1816 AD) were accompanied by temperature decreases. Cooling during the end of the Wolf minimum (until 1350) is reflected in the juniper tree-ring series from Kola Peninsula whereas it is not reflected in the European temperature reconstructions.

(3) Some recent decreases in solar activity around 1900 and 1960 are linked to phases of reduced growth in juniper.

(4) The juniper chronologies from Kola Peninsula do not indicate a temperature rise at the end of the XX century.

(5) MTM spectral and wavelet analysis of juniper tree-ring records showed:

(a) more pronounced 22- and 80–100-year periodicities;

(b) the main cycle of solar activity, the 11-year Schwabe cycle, was not present;

(c) 20–22-year periodicity was not significant throughout the entire ca.700-year period, but during certain time intervals: 1328–1550, 1710–1800, 1985 to present.

1-Oxo-3,4-dihydroisoquinoline-4-carboxamides as novel druglike inhibitors of poly(ADP-ribose) polymerase (PARP) with favourable ADME characteristics

A novel 3,4-dihydroisoquinol-1-one-4-carboxamide scaffold was designed as the basis for the development of novel inhibitors of poly(ADP-ribose) polymerase (PARP). Synthesis of 3,4-dihydroisoquinol-1-one-4-carboxylic acids was achieved using the previously developed protocol based on the modified Castagnoli-Cushman reaction of homophthalic anhydrides and 1,3,5-triazinanes as formaldimine synthetic equivalents. Employment of 2,4-dimethoxy groups on the nitrogen atom of the latter allowed preparation of 2,3-unsubatituted 3,4-dihydroquinolone core building blocks. Iterative synthesis and in vitro biological testing of the amides resulting from the amidation of these carboxylic acids allowed not only drawing important structure-activity generalisations (corroborated by in silico docking simulation) but also the identification of the lead compound, 4-([1,4''-bipiperidine]-1''-carbonyl)-7-fluoro-3,4-dihydroisoquinolin-1(2H)-one, as the candidate for further preclinical development. The lead compound as well as its des-fluoro analog were compared to the approved PARP1 inhibitor, anticancer drug Olaparib, in terms of their molecular characteristics defining druglikeness as well as experimentally determined ADME parameters. The newly developed series demonstrated clear advantages over Olaparib in terms of molecular weight, hydrophilicity, human liver microsomal and plasma stability as well as plasma protein binding. Further preclinical investigation of the lead compound is highly warranted.     

The proton gradient of secretory granules and glutamate transport in blood platelets during cholesterol depletion of the plasma membrane by methyl-β-cyclodextrin

Glutamate transport in blood platelets resembles that in brain nerve terminals because platelets contain neuronal Na⁺-dependent glutamate transporters, glutamate receptors in the plasma membrane, vesicular glutamate transporters in secretory granules, which use the proton gradient as a driving force, and can release glutamate during aggregation/activation. The acidification of secretory granules and glutamate transport were assessed during acute treatment of isolated platelets with cholesterol-depleting agent methyl-β-cyclodextrin (MβCD). Confocal imaging with the cholesterol-sensitive fluorescent dye filipin showed a quick reduction of cholesterol level in platelets. Using pH-sensitive fluorescent dye acridine orange, we demonstrated that the acidification of secretory granules of human and rabbit platelets was decreased by ∼15% and 51% after the addition of 5 and 15 mM MβCD, respectively. The enrichment of platelet plasma membrane with cholesterol by the application of complex MβCD-cholesterol (1:0.2) led to the additional accumulation of acridine orange in secretory granules indicating an increase in the proton pumping activity of vesicular H⁺-ATPase. MβCD did not evoke release of glutamate from platelets that was measured with glutamate dehydrogenase assay. Flow cytometric analysis did not reveal alterations in platelet size and granularity in the presence of MβCD. These data showed that the dissipation of the proton gradient of secretory granules rather than their exocytosis caused MβCD-evoked decrease in platelet acidification. Thus, the depletion of plasma membrane cholesterol in the presence of MβCD changed the functional state of platelets affecting storage capacity of secretory granules but did not evoke glutamate release from platelets.