The effect of ethnicity on appendicular bone mass in white, coloured and Indian schoolchildren

Ethnic differences in the incidence and prevalence of osteoporosis have been shown throughout the world. In South Africa the prevalence of osteoporosis is much higher in whites than in blacks. This is surprising, since factors that might predispose to reduce bone mass are more preponderant in black communities. The present research was undertaken to detertnine whether differences in bone mass during the period of bone accretion could explain the difference in the incidence of osteoporosis. In this paper we report on differences in appendicular bone Inass between white, coloured and Indian children and teenagers (6 - 18 years) from Johannesburg. The effects of weight, height, puberty and skinfold thickness on bone mass were also assessed. The bone width (BW) of white boys was greater than that of Indian boys, while the bone mineral content (BMC) and BMC/BW were greater in white boys than in both Indian and coloured boys. After adjustment for differences in weight and height, the BW of coloured boys was significantly greater than that of white boys, while all differences in BMC and BMC/BW becaIne non-significant. For girls there were no significant differences in bone mass measurements, but after adjustment for height and weight coloured girls had significantly greater BMC and BMC/BW than either white or Indian girls. This greater weight- and height-adjusted bone mass in coloured girls is consistent with the impression of a lower incidence of osteoporosis in coloured women than in white women

Rheumatic fever prophylaxis in South Africa - is bicillin 1,2 million units every 4 weeks appropriate?

Rheumatic fever is a major health problem in South Africa. Although intramuscular benzathine penicillin (bicillin) 1,2 million units (MU) every 4 weeks is widely used for secondary prophylaxis, studies in other countries have shown a recurrence rate of 3 - 8% over 5 - 6 years in patients on this regimen. It has been recommended that serum penicillin concentrations should be maintained above 0,02 mg/ml to prevent such recurrences. The World Health Organisation (WHO) and the American Heart Association have recommended since 1988 that patients in high-risk areas for the development of rheumatic fever should receive benzathine penicillin 1,2 MU every 3 weeks rather than every 4.The aims of this study were, firstly, to determine the prevalence of serum penicillin concentrations below 0,02 μg/ml in rheumatic fever patients on benzathine penicillin 1,2 MU 4-weekly and, secondly, to study the effect of increasing the dose to 1,8 MU 4-weekly in patients with subtherapeutic concentrations.Forty-five of 51 rheumatic fever patients (88%) in this study on benzathine penicillin 1,2 MU 4-weekly had low serum penicillin concentrations (< 0,02 μg/ml) at the end of the 4th week after the injection. Penicillin was detected in the urine of 30 of the 45 patients (67%) with low concentrations, suggesting that such patients have tissue   bound penicillin which might be important in preventing rheumatic fever. The 15 patients (33%) with subtherapeutic serum penicillin concentrations and no detectable penicillin in the urine could be at very high risk for recurrent attacks of rheumatic fever.Fourteen of 29 patients (48%) given the higher dose of benzathine penicillin (1,8 MU 4-weekly) had subtherapeutic serum penicillin concentrations at the end of the 4th week after the injection, but in all 29 penicillin was detected in the urine.Review of our present policy of secondary prophylaxis for rheumatic fever is necessary. Concentrated preparations of benzathine penicillin (600 000 U/ml) are not available in South Africa; administration of a higher dose (1,8 MU) 4-weekly would therefore require a double injection, which could affect compliance adversely. We recommend that rheumatic fever patients in our area should receive benzathine penicillin 1,2 MU 3-weekly as recommended by the WHO until strategies for secondary prophylaxis have been evaluated further

How can we learn about community socio-economic status and poverty in a developing country urban environment? An example from Johannesburg-Soweto, South Africa.

Few tested tools exist to assess poverty and socio-economic status at the community level, particularly in urban developing country environments. Furthermore, there is no real sense of what the community concept actually means. Consequently, this paper aims to describe how formative qualitative research was used to develop a quantitative tool to assess community SES in Johannesburg-Soweto in terms of the terminology used, topics covered, and how it was administered, comparing it to the South African Living Standards and Measurement Study. It also discusses the level of aggregation respondents identified as defining a local community using a drawing/mapping exercise. Focus groups (n=11) were conducted with 15-year-old adolescents and their caregivers from the 1990 Birth-to-Twenty (Bt20) cohort and key informant in-depth interviews (n=17) with prominent members working in the Bt20 communities. This research recognises the importance of involving local people in the design of data collection tools measuring poverty and human well-being

Chemical Bonding in Solids

This chapter discusses the various classes of hydride compounds, with a special focus on saline and metallic hydrides as well as oxyhydrides. It includes the following topics: thermodynamic stability, crystal chemistry, synthesis, and physical properties. The chapter also highlights recent progress in understanding hydride ion mobility in alkaline earth hydrides. It further deals with hydride compounds and in particular those containing alkali, alkaline earth, and transition and rare earth metals. The saline hydrides, that is, AH and AeH2 (with A=Li, Na, K, Rb, and Cs; Ae=Mg, Ca, Sr, and Ba) are proper ionic materials, in which hydrogen is present as hydride anions, H−. Saline hydrides show many similarities with their halide analogues, especially concerning crystal and electronic structures and, perhaps to a lesser extent, physical attributes such as brittleness, hardness, and optical properties

Natural control of HIV infection in young women in South Africa: HPTN 068

Background: Some individuals control HIV replication without antiretroviral (ARV) therapy. Objective: To analyze viral suppression in young women in rural South Africa enrolled in a trial evaluating a behavioral intervention for HIV prevention. Methods: Plasma samples were obtained from women ages 13–24 (81 infected at enrollment, 164 seroconverters). ARV testing was performed using an assay that detects 20 ARV drugs. Women were classified as viremic controllers if they were virally suppressed for ≥12 months with no ARV drug use. Results: Samples from 216/245 (88.2%) women had no ARV drugs detected at their first HIV-positive visit. Thirty-four (15.7%) of the 216 women had a viral load <2,000 copies/mL. Fifteen of the 34 women were followed for ≥12 months; 12 were virally suppressed with no ARV drugs detected during follow-up. These women were classified as viremic controllers (overall: 12/216=5.6%). The median CD4 cell count at the first HIV-positive visit was higher among the 12 controllers than among the 204 women who were not using ARV drugs (759 vs. 549 cells/mm 3 , p=0.02). Some women had a viral load <40 copies/mL at a single study visit, but none were classified as elite controllers (viral load <40 copies/mL for ≥12 months with no ARV drug use). Conclusions: In this cohort, 5.6% of women who were not using ARV drugs had sustained viral suppression. This represents a minimum estimate of the frequency of viremic controllers in this cohort, since some women were not followed long enough to meet the criteria for classification