Role of HIV-1 RNA and protein determinants for the selective packaging of spliced and unspliced viral RNA and host U6 and 7SL RNA in virus particles.

HIV-1 particles contain RNA species other than the unspliced viral RNA genome. For instance, viral spliced RNAs and host 7SL and U6 RNAs are natural components that are non-randomly incorporated. To understand the mechanism of packaging selectivity, we analyzed the content of a large panel of HIV-1 variants mutated either in the 5'UTR structures of the viral RNA or in the Gag-nucleocapsid protein (GagNC). In parallel, we determined whether the selection of host 7SL and U6 RNAs is dependent or not on viral RNA and/or GagNC. Our results reveal that the polyA hairpin in the 5'UTR is a major packaging determinant for both spliced and unspliced viral RNAs. In contrast, 5'UTR RNA structures have little influence on the U6 and 7SL RNAs, indicating that packaging of these host RNAs is independent of viral RNA packaging. Experiments with GagNC mutants indicated that the two zinc-fingers and N-terminal basic residues restrict the incorporation of the spliced RNAs, while favoring unspliced RNA packaging. GagNC through the zinc-finger motifs also restricts the packaging of 7SL and U6 RNAs. Thus, GagNC is a major contributor to the packaging selectivity. Altogether our results provide new molecular insight on how HIV selects distinct RNA species for incorporation into particles.

Quenching of singlet molecular oxygen by Commiphora myrrha extracts and menthofuran.

The quenching activity against singlet oxygen, an actor of lipid peroxidation and DNA degradation, of the essential oil and resinoid of Commiphora myrrha from Somalia has been studied and compared to DL-alpha-tocopherol using 1,3-diphenylisobenzofuran (DPBF) as a probe. To insure that the furan ring was the site of the reaction, experiments were conducted with menthofuran. The essential oil and menthofuran show a higher activity than DL-alpha-tocopherol, suggesting their potential usefulness to neutralise this deleterious form of molecular oxygen.

Academic-community collaboration. An ecology for early childhood violence prevention.

The growing supportive evidence for multi-faceted approaches to violence prevention certainly demand that multi-agency collaborations will continue to proliferate as communities engage in early childhood prevention strategies. These collaborations often include partnerships between members of academia and community agencies that often produce unique challenges and benefits related to diverse experiences, skills, agendas, and practical constraints. This article describes the Jacksonville First and Best Teacher Initiative, an example of one such collaborative model for violence prevention, to illustrate many of the principles of effective academic-community collaborations and lessons learned in addressing the specific challenges of such programs.

Influence of pH and light on the stability of some antioxidants.

Summary Many organic molecules can be oxidized in the presence of oxygen. Light and traces of heavy metal ions catalyse the process of oxidation. The addition of a very small quantity of antioxidant to alcoholic perfumes and cosmetic bases is often made to retard auto-oxidations. Among the parameters which could influence the efficiency of an antioxidant, its intrinsic stability should be considered in the medium to be protected. This stability might conceivably be influenced by the pH, the presence of light, heavy metal ions and microorganisms. In this study we have concentrated on the role played by the first two factors. To eliminate a possible interference by the last two, analytical grades reagents together with chelators and high proof (80% v/v) hydroalcoholic solutions have been used. The antioxidants tested were: BHT, BHA, ethyl gallate, 2, carboxy-6, hydroxy, 2, 5, 7, 8, tetramethyl chroman (Trolox C(R)) and D-L-alpha-tocopherol. Solutions of 0.5 mmol/kg of each antioxidant were prepared in 80% v/v hydroalcoholic solutions and the pH adjusted with citric acid and potassium hydroxyde or hydrochloric acid. The pH extended from 2.5 to 10 and thus largely covers the pH range of cosmetic products. Of each solution, 100ml were kept in hermetically closed 125ml white glass bottles stored at room temperature (22 +/- 2 degrees C) and kept in the dark or exposed to the diffuse daylight of the laboratory. The antioxidants concentrations were determined by linear sweep voltametry on gold or glassy carbon electrodes. Significant differences in behaviour were observed. BHA and BHT are stable regardless of light and pH except at high pH (

Antioxidant properties of wax from Yugoslavian oakmoss (Evernia prunastri).

Synopsis Wax from Yugoslavian oakmoss resulting from the industrial benzene extraction of the vegetable matter was extracted by solvents of different polarities. The wax and the extracts were tested for antioxidant activities using (+) limonene as peroxidizable test substrate and were found to have such activity. The extracts are more active than the wax itself. Although not directly usable because of still too low activity, the wax and the extracts contain a small amount of substance with antioxidant activity comparable to that of the usual synthetic antioxidants.

Rapid lactate determination with an electrochemical enzymatic sensor: clinical usability and comparative measurements.

Lactate measurements can be performed within 2-3 minutes after blood withdrawal from the patients by using an electrochemical enzymatic sensor for lactate. The values obtained reflect the actual state of the patient which is not the case with the slow classical method using lactate dehydrogenase and NAD. The sensor is reproducible and the influence of the main reducing substances found in the blood is small enough to be of no clinical significance. Drugs commonly used in intensive care stations have no influence on the sensor. In vitro lactate production of the blood cells has been studied under various conditions. 66 pairs of comparative measurements between the classical method and the lactate sensor resulted in a good correlation coefficient.

An instrument for the rapid determination of L-lactate in biological fluids.

An analyzer for lactate has been developed based upon an electrochemical-enzymatic method. It allows the determination of lactate within 2 to 3 minutes after sample collection. The instrument is capable of performing up to 20 measurements per hour. A minimum sample volume of 50 mul is needed. Except for the injection of the sample, all steps of the measurement are automated. The instrument is easy to operate and can also be used by nontechnical staff.