Leishmania infantum species-specific kDNA probes: isolation and evaluation

The study refers to the isolation of specific DNA probes to the parasite species Leishmania (L) infantum according to different strategies using recombinant minicircles isolated from L. infantum kinetoplast DNAs. A first probe was identified following a classical procedure. One mini-circle selected for strong reactivity to L. infantum total DNA was used to identify specific subfragments to this species among which the 95bp fragment, 3B8HaeIII-2 was selected. For the obtention of the second probe, a strategy based on sequential screenings for specificity and sensitivity was applied. This allowed identification of a set of minicircles showing an increased specificity to L. infantum as compared to other species, and an increased sensitivity of reaction as compared to the other minicircles. Subclonings and screenings allowed a final selection of a 137bp-minicircle fragment: 3E9HaeIII-12. Reactivities of the 2 probes were assessed on a panel of total DNAs and promastigotes from 74 isolates pertaining to 9 species encountered in the Old World. Parasites isolated in Tunisia from different foci, different hosts after different transmission seasons were included. Hybridizations have shown the exquisite specificity of these probes to L. infantum in this country. Probe 3E9HaeIII-12 was found to be the more sensitive where down to 10 ng of total DNA and 10(3) promastigotes could be detected. From this study and as compared to data provided in the literature, the second procedure allowed at least 10-fold increase in sensitivity.     

First report of the investigation into the importance of pK(a) in the inhibition of estrone sulfatase by sulfamate containing compounds

In an effort to rationalise the inhibitory activity of a range of aminosulfamate compounds and to further investigate the recently reported definitive pharmacophore estrone sulfatase (ES), we undertook extensive synthesis, biochemical evaluation and physicochemical property determination of a range of similar compounds. Here, we report the initial results of our study into a series of simple (aminosulfonate based) substituted phenol derivatives. Using these compounds, we investigated the role of pK(a) in the inhibition of ES. The results of the study suggest that there is a strong correlation between the inhibitory activity and the stability of the resulting O(-) anion (i.e., the pK(a) of the starting phenol).     

Do extraction procedures affect olive oil quality and stability?

Quality and stability of olive oil extracted using discontinuous (pressing) or continuous (centrifuging) procedures were studied. Virgin olive oils extracted from two olive varieties were stored for 17 months. Analytical parameters of oil quality (acidity, peroxide value, polyphenol content, chlorophyll amount, fatty acid composition and triacylglycerol molecular species) were followed at different time intervals. Our results showed that no differences exist between the two types of tested mill, since the studied parameters were unchanged or varied slightly in the same range during the time of oil conservation. Changes depend on olive varieties rather than extraction systems used. Moreover, oils produced by the continuous system contain comparatively higher levels of polyphenols, which may confer to them greater resistance against oxidation for long-term storage.     

Contemporary patterns of adolescent sexuality in urban Botswana

In Botswana, as in other areas in southern Africa, there is a growing concern about the risks associated with adolescent sexuality. To facilitate the design of policies that can address these problems, it is necessary to gain a thorough understanding of contemporary patterns of adolescent sexual behaviour, and the factors that affect them. This paper examines these issues using data from the 1995 Botswana Adolescent Reproductive Health Survey in conjunction with data from focus group discussions. The results suggest that adolescents become sexually active at an early age, and that many of them, males and females alike, have multiple sex partners. This early sexual initiation implies that adolescent reproductive health programmes should target youths aged 13 or younger. For school-based programmes this implies starting no later than Grade 6 or Standard 1, and preferably earlier. Young males appear to be a particularly vulnerable group that needs further attention. Adolescents perceive that teachers, peers and parents have the largest influence on their reproductive health attitudes. Schools appear to have the most potential for providing reproductive health information, because they reach youths both directly and indirectly by educating their peers. The results also show that male and female sexual behaviour is affected by different factors. Among males, having secondary education strongly increases the odds of being sexually active, presumably because such males make attractive partners. Among females, on the other hand, being in school significantly reduces the odds of being sexually active. This finding is consistent with the policy imposing a one-year school expulsion for pregnant schoolgirls, which was implemented as a deterrent to schoolgirl pregnancy.     

The APS adapter protein couples the insulin receptor to the phosphorylation of c-Cbl and facilitates ligand-stimulated ubiquitination of the insulin receptor

The APS adapter protein is rapidly tyrosine-phosphorylated following insulin stimulation. In insulin-stimulated 3T3-L1 adipocytes, APS co-precipitated with phosphorylated c-Cbl. In CHO.T-APS cells overexpressing the insulin receptor and APS, APS co-precipitated with c-Cbl but not in CHO.T cells which do not express APS. APS-mediated recruitment of c-Cbl to the insulin receptor led to rapid ubiquitination of the insulin receptor beta-subunit in CHO. T-APS but not in parental CHO.T cells. These results suggest that the function of APS is to facilitate coupling of the insulin receptor to c-Cbl in order to catalyse the ubiquitination of the receptor and initiation of internalisation or degradation.     

Phenolic constituents from Grevillea robusta

Seven phenolic compounds were isolated from a MeOH extract of the leaves of Grevillea robusta. Their structures were determined by various spectral methods including 2D NMR spectroscopy.     

Stretch-induced injury alters mitochondrial membrane potential and cellular ATP in cultured astrocytes and neurons

Energy deficit after traumatic brain injury (TBI) may alter ionic homeostasis, neurotransmission, biosynthesis, and cellular transport. Using an in vitro model for TBI, we tested the hypothesis that stretch-induced injury alters mitochondrial membrane potential (delta(psi)m) and ATP in astrocytes and neurons. Astrocytes, pure neuronal cultures, and mixed neuronal plus glial cultures grown on Silastic membranes were subjected to mild, moderate, and severe stretch. After injury, delta(psi)m was measured using rhodamine-123, and ATP was quantified with a luciferin-luciferase assay. In astrocytes, delta(psi)m dropped significantly, and ATP content declined 43-52% 15 min after mild or moderate stretch but recovered by 24 h. In pure neurons, delta(psi)m declined at 15 min only in the severely stretched group. At 48 h postinjury, delta(psi)m remained decreased in severely stretched neurons and dropped in moderately stretched neurons. Intracellular ATP content did not change in any group of injured pure neurons. We also found that astrocytes and neurons release ATP extracellularly following injury. In contrast to pure neurons, delta(psi)m in neurons of mixed neuronal plus glial cultures declined 15 min after mild, moderate, or severe stretch and recovered by 24-48 h. ATP content in mixed cultures declined 22-28% after mild to severe stretch with recovery by 24 h. Our findings demonstrate that injury causes mitochondrial dysfunction in astrocytes and suggest that astrocyte injury alters mitochondrial function in local neurons.