The HIV-1 Integrase Mutations Y143C/R Are an Alternative Pathway for Resistance to Raltegravir and Impact the Enzyme Functions

Resistance to HIV-1 integrase (IN) inhibitor raltegravir (RAL), is encoded by mutations in the IN region of the pol gene. The emergence of the N155H mutation was replaced by a pattern including the Y143R/C/H mutations in three patients with anti-HIV treatment failure. Cloning analysis of the IN gene showed an independent selection of the mutations at loci 155 and 143. Characterization of the phenotypic evolution showed that the switch from N155H to Y143C/R was linked to an increase in resistance to RAL. Wild-type (WT) IN and IN with mutations Y143C or Y143R were assayed in vitro in 3′end-processing, strand transfer and concerted integration assays. Activities of mutants were moderately impaired for 3′end-processing and severely affected for strand transfer. Concerted integration assay demonstrated a decrease in mutant activities using an uncleaved substrate. With 3′end-processing assay, IC₅₀ were 0.4 µM, 0.9 µM (FC = 2.25) and 1.2 µM (FC = 3) for WT, IN Y143C and IN Y143R, respectively. An FC of 2 was observed only for IN Y143R in the strand transfer assay. In concerted integration, integrases were less sensitive to RAL than in ST or 3′P but mutants were more resistant to RAL than WT.     

Genetic heterogeneity in tuberous sclerosis

Tuberous sclerosis (TSC) is an autosomal dominant disorder characterized by widespread hamartosis. Preliminary evidence of linkage between the TSC locus and markers on chromosome 9q34 was established, but subsequently disputed. More recently, a putative TSC locus on chromosome 11 has been suggested and genetic heterogeneity seems likely. Here we describe an approach combining multipoint linkage analysis and heterogeneity tests that has enabled us to obtain significant evidence for locus heterogeneity after studying a relatively small number of families. Our results support a model with two different loci independently causing the disease. One locus (TSC1) maps in the vicinity of the Abelson oncogene at 9q34 and a second locus (TSC2) maps in the region of the anonymous DNA marker Lam L7 and the dopamine D2 receptor gene at 11q23.     

SIMS microscopy in the biomedical field.

We attempted to indicate the requirements for biomedical applications of SIMS microscopy. Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue. Furthermore, it is often necessary to correlate ionic and light microscope images. This implies a common methodological approach to sample preparation for both microscopes. The use of low or high mass resolution depends on the elements studied and their concentrations. To improve the acquisition and processing of images, digital imaging systems have to be designed and require both ionic and optical image superimposition. However, the images do not accurately reflect element concentration; a relative quantitative approach is possible by measuring secondary ion beam intensity. Using an internal reference element (carbon) and standard curves the results are expressed in micrograms/mg of tissue. Despite their limited lateral resolution (0.5 microns) the actual SIMS microscopes are very suitable for the resolution of biomedical problems posed by action modes and drug localization in human pathology. SIMS microscopy should provide a new tool for metabolic radiotherapy by facilitating dose evaluation. The advent of high lateral resolution SIMS imaging (less than 0.1 microns) should open up new fields in biomedical investigation.     

Peptide-N 4-(N-acetylglucosaminyl)asparagine amidase (PNGase) activity could explain the occurrence of extracellular xylomannosides in a plant cell suspension

We have previously isolated mannoside and xylomannoside oligosaccharides with one or two terminal reducingN-acetylglucosamine residues from the extracellular medium of white campion (Silene alba) suspension culture. We have now demonstrated the presence of peptide-N ⁴-(N-acetylglucosaminyl)asparagine amidase (PNGase) activity in cell extracts as well in the culture medium that could explain the production of those compounds. An additional xylomannoside, (GlcNAc)Man₃(Xyl)GlcNAc(Fuc)GlcNAc, was characterized, and¹H- and¹³C-NMR assignments for the oligosaccharide Man₃(Xyl)GlcNAc(Fuc)GlcNAc were obtained using homonuclear and heteronuclear spectroscopy (COSY).Abbreviations Endo endo--N-acetylglucosaminidase - Fuc fucose - GlcNAc N-acetylglucosamine - Man mannose - NMR nuclear magnetic resonance - PNGase peptide-N ⁴-(N-acetylglucosaminyl)asparagine amidase - Xyl xylose     

Influence of maize root mucilage on soil aggregate stability

This study was undertaken to determine the effects of root exudates on soil aggregate stability. Root mucilage was collected from two-month old maize plants (Zea mays L.) Mucilage and glucose solutions were added at a rate of 2.45 g C kg⁻¹ dry soil to silty clay and silt loam soils. Amended soils, placed in serum flasks, were incubated for 42 d with a drying-wetting cycle after 21 d. Evolved CO₂ was measured periodically as well as the water-stable aggregates and soluble sugar and polysaccharide content of the soil. In mucilage-amended soils CO₂ evolution started with a lag phase of 2–3 days, which was not observed in glucose-amended soils. There was then a sharp increase in evolved CO₂ up to day 7. During the second incubation period there were only small differences in evolved C between treatments. Incorporation of mucilage in both soils resulted in a spectacular and immediate increase in soil aggregate stability. Thereafter, the percent of water-stable aggregates quickly decreased parallel to microbial degradation. On completion of the incubation, aggregate stability in the silty clay soil was still significantly higher in the presence of mucilage than in the control. This work supports the assumption that freshly released mucilage is able to stick very rapidly to soil particles and may protect the newly formed aggregates against water destruction. On the silty clay, microbial activity contributes to a stabilization of these established organo-mineral bounds.     

Cell population obtained by bronchoalveolar lavage in Pneumocystis carinii pneumonitis

In the course of bronchoalveolar lavages performed in 115 immunocompromised patients in order to investigate the occurrences of pneumonitis, Pneumocystis carinii pneumonia was diagnosed by demonstration of cysts in bronchoalveolar lavage specimens from 11 patients. The cellular phenomena associated with P. carinii infection at the level of the alveolar space were evaluated. Differential cell counts on bronchoalveolar lavage preparations stained by the May-Grünwald-Giemsa method were performed in immunocompromised patients and in ten nonimmunocompromised patients without any respiratory disease. A decrease in the alveolar macrophage count associated with an increase in the polymorphonuclear neutrophil count and the presence of plasma cells and/or immunoblasts was highly suggestive of P. carinii pneumonia. These cellular changes in bronchoalveolar lavage specimens are discussed in relation to the pathologic features usually described in P. carinii pneumonia.     

Contribution a la connaissancce des rhapydionininae (foraminifères, alveolinidae) crétacés

The formerly unknown microspheric form of Raadshoovenia salentina (Papetti and Tedeschi) and the new genus Cyclopseudedomia (type-species Cyclopseudedomia smouti n.g., n.sp.) are described from limestones of Campanian-Maastrichtian age from Gavrovo-Tripolitza zone in Greece. The new genus is distinguished from others of the sub-family RhapydionininaeKeijzer emend. Hamaoui and Fourcade by its almost entirely evolute test made of chambers tending to a cyclical stage (rapidly reached in the microspheric form).     

Integrated cultivation of salmonids and seaweeds in open systems

Bacterial abundance and production in a vertical profile in Lake Kariba (17dgS), Zimbabwe, were affected by solar irradiance. At the surface, 1.87 × 10⁹ bacteria 1^–1 were found and abundance peaked at 10 m (2.5 × 10⁹ bacteria l^-1), then decreasing with depth. Bacterial reproduction at the surface(0.145 µg C1^–1 h^–1) was nearly four times less than the production at 10 m although bacterial numbers were only 26% less. Thus, bacterial production per cell was lower at the surface than deeper down, suggesting that bacterial production is inhibited at the surface.Bacterial production in GF/F filtered lake water in Whirl Pack bags showed an exponential decrease down to 3 m depth. The inhibition was well in accordance with light extinction in the UV region. Phosphatase activity was low in light exposed bags compared to dark, indicating photolysis of extracellular enzymes, or phototransformation of recalcitrant DOM, which substitutes enzyme activity. Hypolimnetic enzyme activity was less affected by solar light than epilimnetic.     

Cold acclimation and photoinhibition of photosynthesis in Scots pine

Cold acclimation of Scots pine did not affect the susceptibility of photosynthesis to photoinhibition. Cold acclimation did however cause a suppression of the rate of CO₂ uptake, and at given light and temperature conditions a larger fraction of the photosystem II reaction centres were closed in cold-acclimated than in nonacclimated pine. Therefore, when assayed at the level of photosystem II reaction centres, i.e. in relation to the degree of photosystem closure, cold acclimation caused a significant increase in resistance to photoinhibition; at given levels of photosystem II closure the resistance to photoinhibition was higher after cold acclimation. This was particularly evident in measurements at 20° C. The amounts and activities of the majority of analyzed active oxygen scavengers were higher after cold acclimation. We suggest that this increase in protective enzymes and compounds, particularly Superoxide dismutase, ascorbate peroxidase, glutathione reductase and ascorbate of the chloroplasts, enables Scots pine to avoid excessive photoinhibition of photosynthesis despite partial suppression of photosynthesis upon cold acclimation. An increased capacity for light-induced de-epoxidation of violaxanthin to zeaxanthin upon cold acclimation may also be of significance.Abbreviations APX ascorbate peroxidase - DHA dehydroascorbate - DHAR dehydroascorbate reductase - Fm maximal fluorescence when all reaction centres are closed - Fv/Fm maximum photochemical yield of PSII - GR glutathione reductase - GSH reduced glutathione - Je rate of photosynthetic electron transport - MDAR monodehydroascorbate reductase - q_N nonphotochemical quenching of fluorescence - q_P photochemical quenching of fluorescence - SOD superoxide dismutase This work was supported by the Swedish Natural Science Research Council and the National Natural Science Foundation of China.