Conformational transitions in polyelectrolyte adsorption

The mole fraction X of nucleic acid chromophores, adsorbed on cationic and anionic exchange chromatography paper disks, was calculated [O.L. H?rer and A. Grigorescu, Rev. Roum. Med. Virol., 43 (1992) 33] in terms of the standard Debye screening length D (in the 0.01 to 1.2 M ionic strength range), using data from MLSEA (multiple light scattering enhanced absorption) measurements. In contrast to the cases of mononucleotides or double-stranded and relatively rigid DNA structures, highly polymerized and single-stranded RNA shows sigmoidal-shaped X curves, suggesting that polymer adsorption may be regarded as a conformational transition from a three-dimensional statistical coil to a two-dimensional one.     

The variability of different larch clone provenances on the response to the attack by its main pests and fungal diseases

A wide range of pests and diseases attacks larch, and over 3 years in an orchard in north-western Romania, the most frequently occurring were larch needle disease (Hypodermella laricis), the case-bearer (Coleophora laricella) and woolly adelgid (Adelges laricis) insects. Their attack on seven larch clones obtained through selection from different geographic populations from Romania was studied. To evaluate the attack intensity, four branches per tree were analysed in the upper, middle and lower third of the crowns in all cardinal directions. According to the position in the crown, a high attack intensity by H. laricis was recorded on the branches in the north direction. A high intensity of C. laricella attack was registered on the upper third of the crown, especially in the east, west and south directions. A positive relationship was identified between the damaged sprouts caused by the C. laricella and A. laricis attack. The differences among the reaction of the clones and the heritability coefficients illustrated that the response to the attacks had a strong genetic determinism, with resistance being clearly influenced by genotype. In addition to the identification of gene sources that are useful for larch breeding, this study offers technical information about the potential to develop efficient treatments based on the attacks on the tree crowns.     

The effect of thermal treatment on antibacterial properties of nanostructured TiO<Subscript>2</Subscript>(N) films illuminated with visible light

This work focuses on the photocatalytic performances and antibacterial activity of nitrogen doped TiO₂ nanosystems with three and five layers obtained by a sol-gel route, followed by thermal treatment in oxygen or ammonia atmosphere at temperatures between 400 and 1000°C. Subsequently, the antibacterial activity of the obtained nanosystems on the Escherichia coli cells are determined and discussed. The obtained results show a significant dependence of the functional performances on the system’s composition. In particular, the antimicrobial activity of nitrogen-doped TiO₂ films is correlated with the temperature of thermal treatment and illumination time with visible artificial light.     

Pyranocoumarin, a novel anti-TB pharmacophore: synthesis and biological evaluation against Mycobacterium tuberculosis

Pyranocoumarin compounds were identified to embody a novel and unique pharmacophore for anti-TB activity. A systematic approach was taken to investigate the structural characteristics. Focused libraries of compounds were synthesized and evaluated for their anti-TB activity in primary screening assays. Compounds shown to be active were further determined for MIC and MBC values. Three of the four bactericidal compounds (16, 17c, and 18f) were amino derivatives, with MIC values of 16 microg/mL and respective MBC values of 32, 32, and 64 microg/mL.     

Synthesis and structural assignment of two major metabolites of the LTA4H inhibitor DG-051

The same two major CYP mediated metabolites of DG-051 were produced in the presence of rat, dog, monkey and human liver microsomes. Their respective structures were hypothesized based on mass spectrometry data correlated with the parent structure and confirmed by comparison with authentic synthetic samples. The number of regioisomers synthesized as candidates for metabolite M1 was narrowed down using a metabolic study of a selectively deuterated DG-051 analogue.     

Halophilic archaea isolated from man-made young (200 years) salt lakes in Slănic, Prahova, Romania

We isolated a number of extremely halophilic archaea from four salt lakes (Red Bath, Green Bath, Shepherd Bath and Bride Cave) located in Slanic Prahova, Romania. The characterization of 12 representative isolates by polyphasic approach revealed that 11 strains were members of the genus Haloferax and only one was a member of the genus Haloarcula. The 11 Haloferax isolates possessed sulfated diglycosylarchaeol-1 as the major membrane glycolipid, and G+C contents of total DNA were 63.4–65.8 mol%. The predominant isolation of Haloferax species from the lakes may suggest that the underground salt deposit possesses Haloferax species as the major biota of ancient origin. To the best of the authors’ knowledge, this is the first paper on the survey of halophilic archaea of man-made young salt lakes.     

Detection of Pathogenic Viruses in Sewage Provided Early Warnings of Hepatitis A Virus and Norovirus Outbreaks

Most persons infected with enterically transmitted viruses shed large amounts of virus in feces for days or weeks, both before and after onset of symptoms. Therefore, viruses causing gastroenteritis may be detected in wastewater, even if only a few persons are infected. In this study, the presence of eight pathogenic viruses (norovirus, astrovirus, rotavirus, adenovirus, Aichi virus, parechovirus, hepatitis A virus [HAV], and hepatitis E virus) was investigated in sewage to explore whether their identification could be used as an early warning of outbreaks. Samples of the untreated sewage were collected in proportion to flow at Ryaverket, Gothenburg, Sweden. Daily samples collected during every second week between January and May 2013 were pooled and analyzed for detection of viruses by concentration through adsorption to milk proteins and PCR. The largest amount of noroviruses was detected in sewage 2 to 3 weeks before most patients were diagnosed with this infection in Gothenburg. The other viruses were detected at lower levels. HAV was detected between weeks 5 and 13, and partial sequencing of the structural VP1protein identified three different strains. Two strains were involved in an ongoing outbreak in Scandinavia and were also identified in samples from patients with acute hepatitis A in Gothenburg during spring of 2013. The third strain was unique and was not detected in any patient sample. The method used may thus be a tool to detect incipient outbreaks of these viruses and provide early warning before the causative pathogens have been recognized in health care.