Impact of organic hydroperoxides on rat testicular tissue and epididymal sperm

Organic hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide have been implicated to cause oxidative stress leading to damage in membrane lipids, proteins, carbohydrates and DNA. This study was aimed to develop an in vivo animal model. The effects of  hydroperoxides on testicular tissue and epididymal sperm were investigated. Male Wistar rats aged 10 - 12 weeks were randomly placed in groups and received standard rat chow and water ad libitum. Animals were injected intraperitoneally with saline (0.5 ml), t-butyl hydroperoxide (5, 10, 20 and 40 ìM; 0.5 ml) or cumene hydroperoxide cHP (2.5, 5, 10 and 20 ìM; 0.5 ml) over a 60 day period. It was found that cumenehydroperoxide cHP (10 and 20 ìM) and t-butyl hydroperoxide tbHP (20 and 40 ìM) led to significantly lower epididymal sperm concentrations and motility. Superoxide dismutase and glutathione activities were also higher with an accompanying increase in lipid peroxidation in both testicular tissue and epididymal sperm. It can be concluded that in vivo intraperitoneal administration of organic hydroperoxides negatively affect the male reproductive system. We have therefore successfully createdan animal model to test the adverse effects of oxidative stress on male reproductive parameters, thereby, enabling us to study possible in vivo treatments

Subunit a of cytochrome o oxidase requires both YidC and SecYEG for membrane insertion

The Escherichia coli YidC protein belongs to the Oxa1 family of membrane proteins that facilitate the insertion of membrane proteins. Depletion of YidC in E. coli leads to a specific defect in the functional assembly of major energy transducing complexes such as the F1F0 ATPase and cytochrome bo(3) oxidase. Here we report on the in vitro reconstitution of the membrane insertion of the CyoA subunit of cytochrome bo(3) oxidase. Efficient insertion of in vitro synthesized pre-CyoA into proteoliposomes requires YidC, SecYEG, and SecA and occurs independently of the proton motive force. These data demonstrate that pre-CyoA is a substrate of a novel pathway that involves both SecYEG and YidC.</p

Development of guidance for sustainable irrigation use of greywater in gardens and small-scale agriculture in South Africa

Greywater is untreated household effluent from baths, showers, kitchen and hand-wash basins and laundry (i.e. all non-toilet uses). More than half of indoor household water is normally used for these purposes and can potentially be intercepted by the householder for additional beneficial uses. Greywater use is practised on an informal basis to supplement irrigation water, either in urban gardens in middle- to upper-income suburbs or in food gardens in lower-income informal, periurban and rural areas. It holds the potential to contribute significantly to food security in poor settlements by providing a source of both irrigation water and nutrients for crop plants. However, there are presently no formal guidelines for the use of greywater in South Africa. This paper presents the rationale and framework of a guidance document for the sustainable use of greywater to irrigate gardens and small-scale agriculture in South Africa, developed under the auspices of the Water Research Commission. The 3 driving principles in developing this guidance were: protection of human health; protection of plants irrigated; and protection of soil and the environment. Risk-management scenarios were developed on the basis of the extent of greywater characterisation. Water-quality constituents for inclusion were selected from among those indicated as presenting a problem in previous studies. Guidance was provided for managing greywater quality, either by mitigation of greywater quality (by practices such as irrigation method, amelioration of soil, leaching of soil and planting of tolerant plant types) or by small-scale biological treatment of greywater. Guidance was also given regarding the volumes of greywaterwhich can be applied, together with factors to adjust these volumes for site-specific conditions.Keywords: greywater, irrigation, food security, sustainable agriculture, health, soil, plant growt

Challenges and opportunities for women entrepreneurs in Botswana: Revisiting the role of entrepreneurship education

Purpose – The purpose of this paper is to investigate challenges faced by and opportunities open to women entrepreneurs in Botswana and how entrepreneurship education can boost their knowledge and skills of doing business profitably and contribute to women empowerment. Design/methodology/approach – In total, 400 women entrepreneurs of different ages, educational levels and from trades and different geographical locations were selected using a stratified random sampling procedure to participate in the study from ten towns and cities in the country. A structured questionnaire that used a five-point Likert scale was used for data collection. One-way ANOVA, regression analysis and descriptive statistics were used as tools for data analysis. Findings – Findings showed that women entrepreneurs faced a complex web of challenges among which were access to finance, lack of training leading to lack of technical skills, lack of knowledge of sources of financing and technical support, high competition in the market, marginalisation of women and lack of knowledge of marketing strategies. The key findings were that while women entrepreneurs faced a number of challenges, the legal and regulatory environment in Botswana was highly conducive and supportive of women entrepreneurship and also that customised entrepreneurship education and training offered opportunities for women entrepreneurs to enhance their knowledge and technical skills. Research limitations/implications – The study only used a quantitative approach to collect data. It could have perhaps been more enriching if a mixed-methods approach were used to help probe the participants more. The study also only used women entrepreneurs in cities and towns. Perhaps, it could have also got some women entrepreneurs from rural areas to hear what they say. These limitations will be addressed in future studies. Practical implications – Practical implications of the study are that women entrepreneurs need more training in business entrepreneurship for them to gain more knowledge and skills; finance houses become more accommodating to women entrepreneurship they could help in the empowerment of these people as theyshow potential in their businesses; and if more pro-women entrepreneurship policies are developed, they could enhance the activities of women entrepreneurs. Social implications – Women can perform as much as men in business if given the necessary support. Originality/value – This study contributes to the body of knowledge on women entrepreneurship as it helped expose challenges women entrepreneurs face as well as opportunities for them to take advantage of and improve their business operations.Curriculum and Instructional Studie

States of emergency

Noodtoestand. Nood toestand word deesdae as so alle daags en gemeenplasig beskou dat daar nie werklik sprake van diepgaande gesprekvoering en besinning oor die bestaan, inhoud en voortsetting daarvan is nie. Hierdie artik el beoog om 'n oorsig oor die afgelope vier jaar van noodtoestand in Suid -Afrik a te gee. Aanvanklik in 1985 is daar slegs 'n gedeeltelike noodtoestand afgekondig wat later opgehef is. ’ n Algemene noodtoestand is in Junie 1986 afgekondig sedertdien is dit jaarliks in in 1987 en 1988 herafgeko ndig. Die beperkings op individuelevryheid , pers vryheid en die normale regsgang is met elke verdere noodtoestand uitgebrei. Die gevolg hiervan is dat daar slegs by hoë uitsondering 'n beroep op die howe gedoen kan word om ondersoek na die geldigheid van nood toestand maatreëls en verbandhoudende owerheidsoptredes in te stel

Monitoring of Laser Powder Bed Fusion by Acoustic Emission: Investigation of Single Tracks and Layers

Quality concerns in laser powder bed fusion (L-PBF) include porosity, residual stresses and deformations during processing. Single tracks are the fundamental building blocks in L-PBF and their shape and geometry influence subsequent porosity in 3D L-PBF parts. The morphology of single tracks depends primarily on process parameters. The purpose of this paper is to demonstrate an approach to acoustic emission (AE) online monitoring of the L-PBF process for indirect defect analysis. This is demonstrated through the monitoring of single tracks without powder, with powder and in layers. Gas-borne AE signals in the frequency range of 2–20 kHz were sampled using a microphone placed inside the build chamber of a L-PBF machine. The single track geometry and shape at different powder thickness values and laser powers were studied together with the corresponding acoustic signals. Analysis of the acoustic signals allowed for the identification of characteristic amplitudes and frequencies, with promising results that support its use as a complementary method for in-situ monitoring and real-time defect detection in L-PBF. This work proves the capability to directly detect the balling effect that strongly affects the formation of porosity in L-PBF parts by AE monitoring

An investigation into the use of the method of spherical currents for the determination of scattered wave fields

In this thesis an approximation method, the method of spherical currents, is advanced for the determination of scattered fields (acoustic and electromagnetic) from convex bodies for plane harmonic incident waves. The method is worked out for the scalar (acoustic) case and applied to sound soft and sound hard obstacles of a given shape. The surface fields and backscattering cross sections of these obstacles are calculated according to the method and the results are compared with those of other methods. For the vector (electromagnetic) case only the basic theory is worked out for a perfectly conducting convex body

Baseline chest radiographic features of HIV-infected children eligible for antiretroviral therapy

Background. South Africa&rsquo;s HIV mortality is primarily due to pulmonary disease. No evidence exists regarding a correlation between specific chest radiographic patterns and CD4 levels of immunity in HIV-infected children.Objectives. We aimed to determine the prevalence of specific radiographic features in HIV-infected children initiating antiretroviral therapy (ART) to develop a guideline of expected baseline radiographic appearances, and the radiographic features that predominate at specific levels of immune suppression (defined by CD4 percentage ranges), which would narrow the radiological differential diagnosis.Method. Retrospective review of the baseline chest radiographs of 92 consecutive paediatric outpatients initiating ART.Results. Normal radiographs were reported in 54% of patients. Those with radiographic abnormalities had parenchymal disease (34%), mediastinal disease (22%) and pleural disease (1%). Parenchymal disease was predominantly air space (28%), and mediastinal disease was predominantly cardiomegaly (21%); lymphadenopathy was rare (1%). Radiological appearances of TB were seen in 9% of patients. A statistically significant association was shown between immune suppression and air space disease (p=0.049) with a relative risk of 0.46 (95% CI 0.24 - 0.88) for air space disease in immune-suppressed children. This association was independent of age.Conclusion. Baseline chest radiographs in paediatric outpatients presenting for initiation of ART are predominantly normal, but also demonstrate a significant number of pathological radiological features &ndash; primarily air space disease and cardiomegaly. The only statistically significant association between radiographic features and immune suppression was air space disease, which correlated with a higher level of immunity.S Afr Med J 2011;101:829-834