cal studies of the respiratory chain complexes in these and Defects of the respiratory chain are a typical feature of mitochondrial diseases and occur also during normal aging other tissues [11][12][13][14][15][16][17] have revealed that aging is an inhomogeneous process at the cellular level leading to randomly diswhere they have been described in postmitotic tissues. The present study addresses the question of defect expression in tributed defects of cytochrome-c-oxidase (complex IV of the respiratory chain) and to intercellular and interorgan differthe normal and cirrhotic liver. Randomly distributed defects of complex III (ubiquinone-cytochrome-c-oxidoreductase) and ences of the defect manifestation.Recently a decline of respiratory rates with age was also of complex IV (cytochrome-c-oxidase) of the respiratory chain have been detected with age-related increasing frequency both reported for the human liver 18 both for unstimulated (state 4) and adenosine diphosphate-stimulated respiration (state in normal and cirrhotic livers. No defects were present for complex II (succinate-dehydrogenase) and complex V (adeno-3). In the last few years molecular genetic studies have revealed that mutations of mitochondrial DNA (mtDNA) such sine triphosphate-synthase) and in liver cell carcinomas. Sixty-one of 107 normal livers (57%) showed defects of the as deletions, duplications, point mutations in transfer RNAs (tRNAs), and structural genes are involved in the pathogenerespiratory chain. The defects occurred in advanced age (over 50 years) in 87%. In contrast 50 of 64 cirrhotic livers (78%) sis of mitochondrial diseases. [19][20][21][22] Similar mutations also accumulate with age although at a lesser degree both in huhad defects and approximately 60% occurred after age 50. The defects were caused by a loss of enzyme protein involving mans 23-38 and in animals. [39][40][41][42][43][44][45][46][47] The present study reports on a random defect pattern of the respiratory chain in normal and both nuclearly and mitochondrially coded subunits. Ninetyfour percent of the defects (n Å 275) involved complex IV cirrhotic livers during aging underlining that aging occurs primarily at the individual cellular level and that similar selectively. In 4% selective defects of complex III were found and combined defects of both complexes occurred in only pathogenetic mechanisms are involved in postmitotic fixed muscular tissue and in liver. Although the random defect 2%. In situ hybridization and polymerase chain reaction (PCR) studies for the detection of the common deletion (4.977 bp) pattern favors a stochastic process, molecular genetic analyses failed to reveal a pathogenetic role of various mutations and of various point mutations of mitochondrial DNA (mtDNA) revealed no consistent molecular genetic abnormali-of mtDNA. Loss of respiratory chain function is a typical feature of normal livers and to the 8th decade in patients with cirrhosis. The mitochondrial diseases. 1-3 To a lesser degree respiratory chain tissue probes were stored fr...

No abstract

No abstract

The percentage of common deletion of mitochondrial DNA (mtDNA) was determined quantitatively by a PCR-based, non-radioactive method in DNA extracted from formalin-fixed, paraffin-embedded skeletal muscle tissues from two patients with Kearns Sayre syndrome (KSS) and one with chronic progressive external ophthalmoplegia (CPEO). The method involved PCR cycle titration of wild-type and deleted mtDNA in parallel, staining of gel bands with the sensitive fluorescence dye SYBR Green I, and quantitation of intensity on a computer screen by the NIH image program. We determined 75% and 71% common deletion of mtDNA in the KSS patients and 35% in the CPEO patient.

No abstract