38 research outputs found
Thai me up, Thai me down — The XV IAS Conference in Bangkok
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Southern African Journal of HIV Medicine Vol. 5(3) 2004: 28-3
A Wigner-based ray-tracing method for imaging simulations
No full textThe Wigner Distribution Function (WDF) forms an alternative representation of the optical field. It can be a valuable tool for understanding and classifying optical systems. Furthermore, it possesses properties that make it suitable for optical simulations: both the intensity and the angular spectrum can be easily obtained from the WDF and the WDF remains constant along the paths of paraxial geometrical rays. In this study we use these properties by implementing a numerical Wigner-Based Ray-Tracing method (WBRT) to simulate diffraction effects at apertures in free-space and in imaging systems. Both paraxial and non-paraxial systems are considered and the results are compared with numerical implementations of the Rayleigh-Sommerfeld and Fresnel diffraction integrals to investigate the limits of the applicability of this approach. The results of the different methods are in good agreement when simulating free-space diffraction or calculating point spread functions (PSFs) for aberration-free imaging systems, even at numerical apertures exceeding the paraxial regime. For imaging systems with aberrations, the PSFs of WBRT diverge from the results using diffraction integrals. For larger aberrations WBRT predicts negative intensities, suggesting that this model is unable to deal with aberrations.ImPhys/Imaging PhysicsApplied Science
Comment on: A randomized clinical trial of exercise during pregnancy to prevent gestational diabetes mellitus and improve pregnancy outcome in overweight and obese pregnant women REPLY
No full textCapital Characteristic Clinical Application Research Fund [Z151100004015088]; World Diabetes Foundation [WDF 14-908]SCI(E)LETTER3380-38121
New antiretrovirals: What\'s in it for southern Africa
No full textThe rise of novel antiretrovirals (ARVs) has introduced a new evolutionary phase in HIV care. In developed countries, the 1980s and early 1990s were characterised by palliative care and opportunistic infection prophylaxis; the late 1990s by an attempt to use a limited and toxic antiretroviral arsenal effectively while cycling through high levels of resistance; and finally, the first half of this decade by working out the easiest-to-take regimens, using the steadily rising number of safer drugs. At present, there are 8 nucleoside analogues (NRTIs), 3 non-nucleoside analogues (NNRTIs), 10 protease inhibitors (PIs), and one each of the fusion, entry and integrase inhibitors to choose from, along with a new drug pipeline that targets both existing and new targets in the viral replicative cycle. The choice may seem quite vast, but the reality is that many of these drugs cannot be used simultaneously or in patients with extensive drug resistance. In addition, some drugs have unacceptable toxicities and are not favoured in current treatment regimens. Southern African Journal of HIV Medicine Vol. 9 (4) 2008: pp. 44-4
Antiretroviral drug resistance: A guide for the southern African clinician
No full textBoth private and public sector see a bewildering clinical array of patients taking failing antiretroviral (ARV) regimens. We intend this article to provide a practical guide to help clinicians understand and manage ARV drug resistance in an African context. ARV resistance is a rapidly evolving field, requiring expertise in dealing with a wide range of situations. Much of the information we have on ARV resistance is from populations in the developed world where clade B is the biggest problem, while in most of Africa clade C is the commonest infection. Southern Africa is faced with the daunting prospect of putting several hundred thousand people on ARV therapy (ART) in the next few years.1 ART is the only effective option available to people with advanced HIV disease, and is remarkably effective in improving quality of life, increasing lifespan, dramatically decreasing the burden of opportunistic disease, and returning people to productive life.2
The levels of adherence demanded by ARV regimens are extremely high relative to any other chronic disease. The South African government\'s Comprehensive Care for HIV/AIDS in the Public Health Sector3,4 programme has a \'second-line\' ARV regimen (Fig. 1), specifically as a safety net for people failing the first-line regimen. Other countries do not have this luxury. The SA second-line regimen is more difficult to take, has greater toxicity, and is more expensive than the first-line treatment. ARV resistance often compromises future treatment options. The choice of regimens in the SA programme maximises the use of available drugs in this country. Our experience of private practitioners in South Africa is that they use a range of drug regimens other than those recommended in the government guidelines. There is no effective mechanism to enforce use of the government\'s recommended drug regimens, but we feel that they are the most rational use of drugs currently available in SA and that deviation from guidelines in routine use should be discouraged, unless alternative options exist. AZT/3TC is still a popular combination, and there are excellent data to support its use as the nucleoside reverse transcriptase inhibitor (NRTI) backbone in first-line therapy, but the alternatives available when resistance to this option develops (i.e. d4T with ddI) are very toxic. In other countries, alternative regimens may be more appropriate.
While we have focused on adult ARV choices in this article, the same principles generally hold for children, although choice of drugs is currently different. Again, we recommend the use of the SA guidelines, published in the November 2005 Journal. Southern African Journal of HIV Medicine Vol. 7 (1) 2006: pp. 30-3
HIV-positive kidney transplants for HIV-positive individuals: Attitudes and concerns of South African patients and health care workers
No full textIn South Africa, an estimated 30% of the cadaveric donor pool is HIV-infected; in consequence, these organs are discarded. An undersupply of donor organs combined with limited resources tends to exclude HIV-positive patients from renal replacement programmes. We evaluated the acceptance of using HIV-positive donor kidneys for transplantation into HIV-infected recipients, and found that the vast majority (90% of health care workers and 80% of patients,N=20 and 80, respectively) found this approach acceptable for expanding the organ donor pool, which indicates broad patient and health care worker support for using HIV-infected donor kidneys
Pre-exposure prophylaxis for HIV prevention: ready for prime time in South Africa?
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