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1994-08-27
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Document 0718
DOCN M9480718
TI Effect of L-carnitine on the zidovudine-induced destruction of human
myotubes. Part I: L-carnitine prevents the myotoxicity of AZT in vitro.
DT 9410
AU Semino-Mora MC; Leon-Monzon ME; Dalakas MC; Neuromuscular Diseases
Section, National Institutes of; Neurological Diseases and Stroke,
National Institutes of Health,; Bethesda, Maryland.
SO Lab Invest. 1994 Jul;71(1):102-12. Unique Identifier : AIDSLINE
MED/94315860
AB BACKGROUND: Zidovudine (AZT) as used in the treatment of AIDS, causes a
mitochondrial myopathy characterized by depletion of mitochondrial DNA,
enzymatic defects in the respiratory chain system, and accumulation of
lipid droplets. Most of these changes are also seen in normal human
myotubes treated with AZT. Because L-carnitine plays a major role in the
transport of long chain fatty acids across the inner mitochondrial
membrane and facilitates the beta-oxidation of fatty acids, we examined
the effect of L-carnitine in preventing the destructive effect of AZT on
the mitochondria and the myotubes of human muscle in tissue culture.
EXPERIMENTAL DESIGN: Myotubes, prepared from human muscle biopsies, were
exposed to various concentrations of AZT for up to 3 weeks. One-third of
the flasks were treated with AZT alone, another third with AZT plus
L-carnitine and another third were untreated. The cultures were
evaluated with: (a) immunocytochemistry counting the number of myotubes
stained with antibodies to Leu-19; (b) enzyme histochemistry for NADH
reaction and oil-red-O stain to assess mitochondrial enzymatic activity
and lipid droplet accumulation; and (c) electron microscopy counting all
the organelles within representative sections of the myotubes, at
x24,000, and calculating the volumetric density of each organelle/unit
volume of tissue. RESULTS: AZT, at concentrations 250 microM and above,
caused depopulation of the Leu-19-positive myotubes, destructive changes
in the mitochondria consisting of swelling, lamellar inclusions and
multiple concentric cristae, accumulation of lipid droplets, and
increase lysosomes. L-Carnitine increased the number of Leu-19-positive
myotubes from 3.4 +/- 0.6 to 9.4 +/- 1.2, preserved the morphology of
the mitochondria, increased their volumetric density from 2.5 +/- 0.4 to
6.0 +/- 0.7, and reduced the volumetric density of the lipid droplets
from 12.2 +/- 4.9 to 1.4 +/- 0.7 and of the lysosomes from 15.6 +/- 3.6
to 3.9 +/- 1.4 (p < 0.001). CONCLUSIONS: L-Carnitine, used concurrently
with AZT, prevents the human myotubes from the AZT-associated
destruction, preserves the structure and volume of mitochondria and
prevents the accumulation of lipids. The findings may have potential
clinical implications in preventing the myotoxicity of AZT in patients
with AIDS.
DE Carnitine/*PHARMACOLOGY Dose-Response Relationship, Drug
Histocytochemistry Human Immunohistochemistry Mitochondria,
Muscle/*DRUG EFFECTS/ULTRASTRUCTURE Mitochondrial Myopathies/CHEMICALLY
INDUCED Muscles/*DRUG EFFECTS/ULTRASTRUCTURE Reproducibility of
Results Stains and Staining Tissue Culture Zidovudine/*ADVERSE
EFFECTS JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).