Novel biotin phosphoramidites with super-long tethering arms.

A number of novel biotin phosphoramidites, possessing exceptionally long and uncharged tethering arms, were synthesized from methoxyoxalamido (MOX) and succinimido (SUC) precursors. Included among these monomers is a uridine derivative with the biotin moiety attached through the 2'-position. Some of these phosphoramidites were used to make 5'-biotinylated primers, which were applied in direct sequencing of genomic DNA and capture of Sanger fragment pools.

[Monomers of a satellite sequence of chaffinch (Fringilla coelebs L., Aves: Passeriformes) genome contains short clusters of the TTTAGGG repeat]. / Satellitnaia posledovatel'nost' iz genoma ziablika (Fringilla coelebs L., Aves: Passeriformes), monomery kotoroi soderzhat korotkie klastery povtora TTAGGG.

A novel repeated sequence of chaffinch (Fringilla coelebs) designated as GS was isolated from genomic DNA after in vitro amplification of satellite DNA sequences using GSP-PCR technique. The proportion of this repeat in the chaffinch genome constitutes about 2%. Monomers are 176 to 199 bp in size and contain a short cluster of the TTAGGG telomeric tandem repeat. The oligomer of the telomeric hexanucleotide is flanked by the sequences that are significantly different in different monomers. The GS sequences are organized as tandemly repeated units and located in a number of chromomycin-positive blocks on the long arms of macrochromosomes 1, 2, 3, 5, and 6, as well as on several microchromosomes. The sequences homologous to the GS satellite of chaffinch were not found in the genomes of redwing (Turdus iliacus) and house sparrow (Passer domesticus).

[Analysis of the structure-functional features of a highly-repeating centromere sequence from the Fringilla coelebs L. (Aves: Passeriformes) genome]. / Analiz strukturno-funktsional'nykh osobennoste vysokopovtoriaiushcheisia tsentromernoi posledovatel;nosti iz genoma Fringilla coelebs L. (Aves: Passeriformes).

A highly repetitive centromeric Fringilla coelebs PstI (FCP) element was cloned and sequenced. The FCP tandem repeats with unit 505 or 506 nt accounted for about 0.9% of the entire genome and had 57% GC. Direct genomic sequencing with FCP-specific primers and ThermoFidelase 2A revealed the consensus sequence and the five most common single-nucleotide polymorphisms (SNPs) for the FCP unit. FCP may be transcribed and may play a role in spatial arrangement of the genome.

Centromeric tandem repeat from the chaffinch genome: isolation and molecular characterization.

A new family of avian centromeric satellites is described. The highly repeated sequence, designated FCP (Fringilla coelebs PstI element), was cloned from the 500-bp PstI digest fraction of the chaffinch (Fringilla coelebs L.) genomic DNA, sequenced, and characterized. The FCP repeat was found to have 505-506 bp length of monomer, 57% content of GC, to compose about 0.9% of the chaffinch genome, and to be highly methylated. Results of Southern-blot hybridization of cloned FCP element onto genomic DNA digested with different restriction enzymes, and sequencing directly from total genomic DNA using FCP-specific primers and ThermoFidelase enzyme (Fidelity Systems Inc.) were in agreement with a tandem arrangement of this repeat in the chaffinch genome. Five positions of single-nucleotide polymorphism (SNP) were found in the FCP monomers using direct genomic sequencing. Fluorescence in situ hybridization (FISH) with FCP probe and primed in situ labelling (PRINS) with FCP specific primers showed that the FCP elements occupy pericentric regions of all chaffinch chromosomes. On chromosome spreads, the fluorescent signals were also observed in the intercentromeric connectives between nonhomologous chromosomes. The results suggest that the centromeric FCP repeat is responsible for chromosome ordering during mitosis in chaffinch.

Combination of a drug targeting the cell with a drug targeting the virus controls human immunodeficiency virus type 1 resistance.

Combinations of drugs targeting viral proteins have been used to limit or control drug resistance, which is the most important cause of treatment failure in HIV-1-infected individuals. We suggest an alternative approach, namely to target cellular proteins, which are less prone to mutations than viral proteins. Here we show that simultaneous inhibition of a cellular protein (by hydroxyurea) and a viral protein (by ddI) produces a consistent and sustained suppression of HIV-1 for as long as 40 weeks in the absence of virus rebound. We identified the mechanism to explain this lack of rebound: although the combination of the two drugs did not prevent the emergence of mutant viral strains resistant to didanosine (ddI) in these patients, the mutants were still sensitive to standard doses of ddI in the presence of hydroxyurea. These in vivo results were consistent with our in vitro observations: HIV-1 molecular clones resistant to ddI were rendered sensitive to this drug (at concentrations routinely achievable in vivo) after addition of hydroxyurea. This phenomenon can be explained by the observation that hydroxyurea decreases the level of dATP, the cellular competitor of ddI. A low level of dATP favors the incorporation of ddI, even if the viral reverse transcriptase is resistant to this nucleoside analog. This is a novel mechanism of control of resistance and it explains the efficacy of a treatment that is well tolerated, simple, and inexpensive.

Epidemiology of HIV infection in St. Petersburg, Russia.

Overall HIV-1 prevalence in St. Petersburg (Leningrad) is extremely low (0.002%). HIV-2 infection has not been detected. The possible mode of virus entry was through sexual contacts with infected foreigners, the earliest documented date being prior to 1982. Among 25 seropositive males, 18 are homosexual and five are bisexual, suggesting that the virus is circulating within resident population of homo/bisexual males. The total incidence of new infections has not shown the type of dramatic increase noted in US gay/bisexual men in early 1980s. Information on lifestyle characterization of this indigenous population require further study to determine the future potential for spread. Among the non-Soviet population the rate is 0.01%. Highest rates occur among persons from HIV endemic areas of Africa, with rates as high as 5% and 3% among persons from Uganda and Rwanda, respectively. Rates among new entrants from Africa are lower, possibly reflecting the impact of prescreening of applicants prior to arrival in Russia. Further monitoring of high-risk populations and studies to define behavior risk pattern are planned.

[The detection of the human immunodeficiency virus antigen in the lymphoid cells of seropositive subjects]. / Vyiavlenie antigena virusa immunodefitsita cheloveka v limfoidnykh kletkakh seropozitivnykh lits.

Cells from anti-HIV-positive persons were used in experiments for virus isolation. The RT-activity, viral antigen, nucleic acids, electron microscopic morphology, and infectivity were studied. The data presented allow a conclusion that the virus was isolated. These data confirmed the previous diagnosis of HIV infection.