Linked Life Data

9742236

Source:http://linkedlifedata.com/resource/pubmed/id/9742236

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
1998-11-17
pubmed:abstractText
Progressive age-related oxidative phosphorylation (OxPhos) decline is well known in human tissues. Depletion of mitochondrial DNA (mtDNA) causes OxPhos defects in patients with myopathic syndromes and deficient mtDNA replication has been observed in cells cultured from patients with mitochondrial disease. Patients undergoing treatment for AIDS develop OxPhos defects via mtDNA depletion resulting from inhibition of mtDNA polymerase gamma (Polgamma) by 2'-deoxy 3'-azido thymidine. These findings by others give rise to a possible link between mtDNA replication and bioenergetic decline in disease and during ageing. We have designed an in vitro assay for Polgamma function in small tissue samples to explore this possible link. Platelet homogenate Polgamma showed an activity with a K m of 150 microM (dTTP), a V max of 11.8 pmol/min/mg, inhibited (41% inhibition; 50 microM) by ethidium bromide. Determination of several storage characteristics showed that platelets were a convenient source of Polgamma for assay. Polgamma activity in 45 subjects did not coincide with significant age-related decline (P<0.002; P) observed in cytochrome oxidase (CytOx) activity or with citrate synthase activity. Of the activities studied, the only significant age-wise variation was a 24% CytOx deficiency in elderly (>50; n = 19) compared to young (<51; n = 24) individuals (P<0.01; t). These results suggest a maintenance of total cellular mtDNA Polgamma processive levels during ageing, largely independent of total cellular bioenergetic status or mitochondrial number/density. The processive component of Polgamma is therefore unlikely to make a major contribution to age-related bioenergetic activity decline. This does not, however, preclude the possibility that transient periods of inhibition at crucial points of the cell cycle or development may augment existing intracellular deficiencies. The assay described here greatly facilitates study of Polgamma activity in patients with conditions involving mtDNA depletion or rearrangement.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0305-1048
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4365-73
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
mtDNA replicative potential remains constant during ageing: polymerase gamma activity does not correlate with age related cytochrome oxidase activity decline in platelets.
pubmed:affiliation
Melbourne Neuromuscular Research Centre and Department of Clinical CSIRO Division of Molecular Science, Parkville Laboratory, Parkville, Victoria 3052, Australia. rkapsa@ariel.unimelb.edu.au
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't