Synthesis and study of C-substituted methylthio derivatives of cobalt bis(dicarbollide)

The C-methylthio derivatives of cobalt bis(dicarbollide) were synthesized by reaction of anhydrous CoCl₂ with nido-carborane [7-MeS-7,8-C₂B₉H₁₁]⁻ and isolated as a mixture of rac-[1,1′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ and meso-[1,2′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ isomers. The structures of both isomers were studied using DFT quantum chemical calculations. The most preferable geometry of rotamers and the stabilization energy of C-methylthio derivatives of cobalt bis(dicarbolide) were calculated. The (BEDT-TTF)[1,1′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂] salt was prepared and its structure was determined by single crystal X-ray diffraction. The cisoid conformation of the rac-[1,1′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ anion is stabilized by short intramolecular CH⋯S hydrogen and BH⋯S chalcogen bonds between the dicarbollide ligands, that is in good agreement with the data of quantum chemical calculations.

The C-methylthio derivatives of cobalt bis(dicarbollide) rac-[1,1′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ and meso-[1,2′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ were synthesized and studied by DFT calculations and X-ray diffraction.     

Restriction of cell lysis by homologous complement: II. Protection of erythrocytes against lysis by newly activated complement

Our previous work revealed that homologous complement (C) was ineffective in lysing antibody-sensitized erythrocytes (EA) even at high concentrations. It was also shown that activation of complement on homologous EA resulted in the binding of C9 and the formation of EA bearing complement proteins C1 through C9 (EAC1-9), yet few hemolytic sites were formed. Instead, as shown here, the formation of homologous EAC1-9 caused the cells to become resistant to lysis even by heterologous complement during a second incubation. In contrast, when homologous EAC1-8 were produced by incubating EA with C9-depleted serum, such intermediates were not protected against lysis by heterologous complement during a second incubation. Furthermore, homologous C9 on EAC1-9 was able to reduce the hemolytic efficiency of heterologous complement without blocking C activation and the formation of new C5b-9 complexes. Protection was not modified when homologous EAC1-9 were produced in one step, by incubation of EA with serum, or sequentially by adding C9 to EAC1-8. The minimum number of 9-sites required to confer a protective effect on EAC1-9 was less than 200 per cell. Thus, in addition to its known effect in heterologous cell killing, homologous C9 is capable of protecting homologous cells against inadvertent complement lysis.     

Growth characteristics of circulating hematopoietic progenitor cells from patients with essential thrombocythemia

Peripheral blood mononuclear cells from five patients with essential thrombocythemia (ET) were cultured in vitro to evaluate restricted megakaryocytic (CFU-Meg), myeloid (CFU-GM), and erythroid (BFU-E) progenitor cell development. Varying concentrations of aplastic canine serum served as the source of megakaryocyte colony-stimulating activity, and cultured megakaryocyte ploidy distributions were determined by Feulgen staining and microfluorometry. Megakaryocyte colony growth was strikingly abnormal in all five patients evaluated. Four of the 5 had a marked expansion in the concentration of circulating CFU-Meg and 3 of 4 manifested abnormalities in cultured megakaryocyte colony size (2 unusually large and 1 small). Unstimulated megakaryocyte colony growth was substantially increased in three patients. However, the fraction of megakaryocyte progenitors in cell cycle was near or below normal in all instances. Endomitotic megakaryocyte development was disordered in each of the four ET patients in whom it was evaluable. In normal subjects, mean megakaryocyte ploidy values vary biphasically with aplastic canine serum concentration and peak at 13.2 N following 12 to 15 days of culture. In contrast, day 12 mean ploidy values in cultures from the ET patients remained low at all aplastic canine serum concentrations and reached a maximum averaging only 8.4 N. Three patients were evaluated serially at extended culture durations of up to 21 days. The cultured megakaryocyte ploidy was unchanged during this interval for two of the patients. For the third patient, ploidy increased steadily, reaching abnormally high ploidy values by day 21. Progenitor cell expansion was limited to the megakaryocyte line in three patients. However, two patients had substantial increases in CFU-GM, one of whom also had a marked increase in BFU-E. There was no significant unstimulated colony growth by either CFU-GM or BFU-E. These data indicate that ET is usually characterized by an expansion in the concentration of circulating CFU-Meg in vivo which manifest both disordered replication and endoreduplication in vitro.     

Molecular genetic analysis of the biological properties of highly pathogenic influenza A/H5N1 virus strains isolated from wild birds and poultry during epizooty in Western Siberia (July 2005)

The full-size genomes of 2 highly pathogenetic avian influenza (HPAI) virus strains isolated from a wild great-crested grebe (A/Grebe/Novosibirsk/29/05) and a domestic duck (A/Duck/Novosibirsk/56/05) in the tract of the Chany hollow, Barabino forest-steppe (Novosibirsk Region) during the epizootic outbreak in the summer of 2005. The reproductive properties of these strains successively increase in the series of cell lines BHK-2 --> LEH --> Vero-E6 --> MDCK --> PS. A/Grebe/Novosibirsk/29/05 and A/Duck/Novosibirsk/56/05 were shown to be genetically close in all genomic segments to both each other and a group of HPAI/H5N1 A/Qinghai 05 strains isolated from wild birds on the Kukunor Lake in the northwestern province of Tsinkhai, China, in May 2005. All the above strains have the HPAI/H5-specific amino acid sequence of a proteolytic cleavage site (PQGERRRKKRGLF) with Lys-627 in the protein PB2 (which is associated with increased virulence to mammalian cells), Glu-92 in the protein NS1 (that suppresses an antiviral response in the host), Ser-31 in M2 (that is a marker of rimantadine/amantadine sensitivity), 20-member amino acid deletion in the protein NA (positions 49-68) that is a marker of affiliation to the so-called genotype Z and of increased tropism to poultry.     

Optimization of the gene composition of influenza H5 virus hemagglutinin-containing reassortants and their efficacy in immune cross-protection experiments

The reassortant described in the authors' previous paper contained 6 genes originating from the high-yield virus A/Puerto Rico/8/34 (H1N1) and the genes of hemagglutinin (HA) and neuraminidase (NA) of the low-pathogenic avian influenza A/Duck/Primorie/2621/2001 (H5N2) (6:2 reassortant). The reassortant was used for the backcrossing with the parent avian virus in order to optimize the gene composition. Genotyping of the highest-yield second-generation reassortment indicated that it had obtained the PB1, HA, and NA genes from the virus A/Duck/Primorie/ 2621/2001 and the other genes received the genes from the virus A/Puerto Rico/8/34 (5:3 reassortant). The yield produced in the embryonated chicken eggs by the 5:3 reassortant was higher than that produced by the 6:2 reassortant although it did not achieve the reproduction of the parent virus A/Puerto Rico/8/34. Murine immunization with the inactivated reassortant containing the HA and NA genes of the virus A/Duck/Primorie/2621/2001 (H5N2) provided an efficient protection against the virus containing HA and NA of a recent H5N1 strain.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Deviation from the random distribution pattern of influenza A virus gene segments in reassortants produced under non-selective conditions

High-frequency reassortment of gene segments is characteristic for influenza viruses, and it is considered to be of significance for the origin of pandemic influenza. In order to analyze whether the segregation of genes in the reassortants is random, or it deviates from the random pattern, we inoculated embryonated chicken eggs simultaneously with two influenza viruses, A/WSN/33 (H1N1) and A/Duck/ Czechoslovakia/56 (H4N6), at a high multiplicity of infection. The virus yield was used for plaque cloning, and the genetic content of plaque isolates was determined by analysis of the mobility of virus-induced proteins in polyacrylamide gel (for NP and NS genes), partial sequencing (for M gene) and polymerase chain reaction analysis with strain-specific primers for the other genes. Out of 37 isolates, 27 were reassortants. The majority of the reassortants contained the HA gene of A/WSN/33 (H1N1) virus and the NP gene of A/Duck/Czechoslovakia/56 (H4N6) virus. The data demonstrate the previously unrecognized phenomenon of segment-specific deviation from the random distribution of parent genes in the reassortants. The results are discussed in connection with the problem of differential competition between influenza A virus gene segments in mixed infection and random versus non-random reassortment of gene segments under non-selective conditions.     

Development of increased convulsibility in mice after a single norbornan injection

A single intraperitoneal injection of norbornan markedly increases convulsant activities of picrotoxin and 3-mercaptopropionic acid in mice. Norbornan may be useful in the investigation of the mechanisms of convulsions. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 123, No. 1, pp. 60–62, January, 1997     

The use of perfluorinated emulsion for prolongation of the endurance period in lethal hypoxia

The apnea model with venovenous perfusion and blood oxygenation in a membrane oxygenator was used to study the gas transport characteristics of perfluorinated emulsion with the aim to prolong the endurance period in lethal hypoxia. The use of PFOS emulsion (40 ml/kg) as a hemodilution agent at relatively low rate of assisted perfusion (35 ml/kg×min) produced no improvement of oxygen supply during the critical period in comparison with conventional plasma substitutes. However, perfusion with oxygenated perfluorinated emulsion prolonged survival as compared with polyglucin perfusion, mainly due to the maintenance of the vitally important organs (heart and brain) and due to the improvement of microcirculation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 10, pp. 477–480, October, 1997