Biology Reference
In-Depth Information
In this regard, one of the most studied compounds was d4T, but few and
contrasting data exist on its capacity to a¨ect mitochondrial function and
DNA. In hepatoma cells, Pan-Zhou et al. found no e¨ects on the synthesis of
11 polypeptides encoded by mtDNA ( Pan Zhou et al., 2000); in PC-12 cells
(of neuronal origin), Cui et al. described a dose-dependent inhibition of neurite
regeneration but no e¨ects on mtDNA synthesis (Cui et al., 1997). According
to Faraj et al., who studied di¨erent antiretroviral compounds, d4T is the least
potent NRTI capable of inhibiting proliferation of cells belonging either to the
granulocyte-monocyte or erythroid lineages ( Faraj et al., 1994). In CEM cells
(of lymphocytic origin), cell viability and mtDNA content in cultures treated
with d4T were signi®cantly reduced in a concentration-dependent fashion
compared with cell viability and mtDNA content in untreated cultures (Medina
et al., 1994); such cells also showed signi®cant changes in their mitochondrial
morphologies, including distortion and reduction of the cristae and numerous
vesicles.
However, even if direct responsibility for drug-induced mitochondrial
damages in the pathogenesis of lipodystrophy has been hypothesized, there is
still a substantial lack of direct analysis of the functionality of these organelles,
for example, in cells taken from lipodystrophic patients or in other models.
Two recent reports described the features of mitochondria in these patients.
In the ®rst, Shikuma et al. have performed a cross-sectional evaluation of
tissue-speci®c mtDNA in HIV-infected individuals with lipodystrophy, taking
HAART for at least 6 months, in comparison with other cohorts of HIV
patients (Shikuma et al., 2001). They performed semiquantitative analysis
of mtDNA content in subcutaneous fat biopsies taken from the neck, abdo-
men, and thigh. They found that decreased mtDNA levels were present in
subcutaneous adipose tissue from lipodystrophic patients on NRTI-containing
HAART; however, no large mtDNA deletions or insertions were found in any
specimen. Vigan Á et al. showed that, as far as changes in Dc or tendency to
undergo apoptosis were concerned, peripheral lymphocytes from lipodystrophic
children did not display signi®cant di¨erences from those of healthy control or
HIV-infected children without lipodystrophy (Vigan Á et al., 2001). The latter
study is based upon some cytometric technologies described below, which thus
could be useful, at least in part, for clarifying the role of mitochondrial dam-
ages during HIV infection and its therapy.
MITOCHONDRIAL FUNCTIONAL PARAMETERS THAT CAN BE
DIRECTLY ANALYZED IN LIVING CELLS BY CYTOMETRIC
METHODS
Mechanisms that regulate changes in membrane potential of organelles with a
negative interior, as depicted in Figure 13.1, have been analyzed with sev-
eral membrane-permeable, lipophilic cations, because of their property to
accumulate in such organelles and/or liposomes. Such probes include those
