The Body Covers: The XIII International AIDS Conference
July 11, 2000
Mitochondrial function and exercise capacity in HIV-infected patients with lipodystrophy (TuPpB1232)There has been an increased amount of attention to the possibility that nucleoside antivirals have a side effect that alters the function of mitochondria. Mitochondria are in virtually all of the body's cells and are responsible for the fuel and energy of cell function. If the mitochondria are impaired by nucleoside antivirals, then we might expect to see reduced exercise capacity in someone, as the muscle cells might have less energy to do the exercise. With this as a rationale, the researchers did a small study with eight people who were on combination antivirals. The patients were required to exercise regularly and were compared with six others who were HIV-negative and similar in age, gender, and height. They focused on measuring blood lactate, which is produced when mitochondria are not functioning optimally in cells. They reported seeing some differences in those who were HIV-positive, as there was more lactic acid production while exercising. However, at "peak" exercise levels, these differences were no longer seen.
It is unclear what these results mean at this point. Since the differences were not true at all levels of exercise it may reflect some vulnerability in those who are positive on medications, but this difference was subtle. In addition, as they did not have any participants who were HIV-positive and not on medication, we cannot say from this study how much the outcome was due to being on medications vs. just having HIV infection. Nonetheless, there will be more exploration of the impact of nucleoside antivirals on mitochondrial function.
Screening for nucleoside-associated lactic acidosis (TuPpB1233) and
Screening for lactic acidosis for those on nucleoside RT antivirals has become more discussed in recent months with the hope that this lab finding may explain some of the side effects seen in those on antivirals. These two studies explored the possible role of using lactic acid measurements as a way to identify those who might be at risk for medical problems, allowing us to intervene before symptoms might occur.
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