Peripheral and visceral fat changes following a treatment switch to a non-thymidine analogue or a nucleoside-sparing regimen in HIV-infected subjects with peripheral lipoatrophy: results of ACTG A5110.

BACKGROUND: Switching a thymidine analogue to a non-thymidine analogue or changing to a nucleoside-sparing regimen has been shown to partially reverse peripheral lipoatrophy. The current study evaluated both approaches. METHODS: Subjects at 15 AIDS Clinical Trial Group sites receiving thymidine analogue stavudine- or zidovudine-containing regimens with plasma HIV RNA < or =500 copies/mL and lipoatrophy were prospectively randomized to: (i) switch the thymidine analogue to abacavir; (ii) discontinue all antiretrovirals and switch to lopinavir/ritonavir plus nevirapine (LPV/r+NVP); or (iii) delay switching for 24 weeks (ClinicalTrials.gov identifier: NCT00028314). Single-slice computer tomography of mid-thigh and abdominal fat and metabolic and virological/immunological parameters were measured at baseline and weeks 24 and 48. RESULTS: Among the 101 patients enrolled, there were significant subcutaneous thigh fat and subcutaneous abdominal tissue (SAT) increases over time and decreases in visceral adipose tissue to total adipose tissue (VAT:TAT) ratios for both interventions, and a decrease in VAT for abacavir. CD4 increased in the LPV/r+NVP arm. LPV/r+NVP had a significantly shorter time to grade 3 or higher toxicity (P = 0.007), but discontinuation rates were similar. Glucose levels did not change, but insulin decreased in the LPV/r+NVP arm. Lipids tended to increase in the LPV/r+NVP arm. CONCLUSIONS: Switching stavudine or zidovudine to a non-thymidine analogue or changing to a nucleoside reverse transcriptase inhibitor-sparing regimen is associated with qualitatively similar improvements in thigh fat, SAT and VAT:TAT ratio at 48 weeks. Abacavir also resulted in VAT reductions and LPV/r+NVP resulted in CD4 count increases.

Some theoretical aspects of the turbulent point-spread function.

In a previous work [J. Opt. Soc. Am. A24, 753 (2007)], we developed a theory describing the space-time statistics of the scintillation and displacement fields of the turbulent point-spread function (PSF), which we validated using imaging data. We now expand on that work by deriving the theoretical expression for the spread fields of the PSF. We also show how the displacement and spread fields are derivable from a set of potentials, and we discuss some of the properties of those potentials.

Some space-time statistics of the turbulent point-spread function.

We consider the point-spread function (PSF) of an imaging system looking through weak optical turbulence along a horizontal path through the atmospheric surface layer. From this PSF we derive a scalar total irradiance field and a center-of-mass vector field. Theoretical values are found for the space-time autocorrelation and cross-correlation functions for these fields, which are then compared with the observed correlation functions obtained from data taken at the Validation Measurements on Propagation in the Infrared and Radar (VAMPIRA) measurement trial. We discuss the meaning of these results and possible directions for future work.