Several cellular and molecular alterations have been described in skeletal and respiratory muscles of patients with chronic obstructive pulmonary disease (COPD), but information on potential abnormalities of mitochondrial function is scarce. The aim of the present study was to investigate mitochondrial function in the vastus lateralis (VL) and external intercostalis (EI) of COPD patients. Biopsies from VL and EI were obtained during surgery for lung cancer in 13 patients with mild to moderate COPD (age 68+/-6 yrs, forced expiratory volume in one second (FEV(1)) 66+/-15% predicted) and 19 control subjects (age 67+/-9 yrs, FEV(1) 95+/-18% pred). State 3 and 4 mitochondrial oxygen consumption (V'(O(2),m)), ATP synthesis, citrate synthase, cytochrome oxidase (COX) and complex I-III activities, as well as reactive oxygen species (ROS) production, were determined. In COPD patients, in both muscles, COX activity (VL: COPD 3.0+/-0.8 versus control 2.0+/-0.8; EI: 3.7+/-1.6 versus 2.4+/-0.9 micromol min(-1) mg(-1)) and ROS production (VL: 1,643+/-290 versus 1,285+/-468; EI: 1,033+/-210 versus 848+/-288 arbitrary units) were increased, whereas state 3 V'(O(2),m) was reduced (VL: 2.9+/-0.3 versus 3.6+/-0.4; EI: 3.6+/-0.3 versus 4.1+/-0.4 mmol min(-1) kg(-1)). Skeletal muscle mitochondria of patients with chronic obstructive pulmonary disease show electron transport chain blockade and excessive production of reactive oxygen species. The concurrent involvement of both vastus lateralis and external intercostalis suggests a systemic (rather than a local) mechanism(s) already occurring in relatively early stages (Global Initiative for Chronic Obstructive Lung Disease stage II) of the disease.

Cisplatin is an anticancer agent marred by nephrotoxicity; however, limiting this adverse effect may allow the use of higher doses to improve its efficacy. Cilastatin, a small molecule inhibitor of renal dehydropeptidase I, prevents proximal tubular cells from undergoing cisplatin-induced apoptosis in vitro. Here, we explored the in vivo relevance of these findings and the specificity of protection for kidney cells in cisplatin-treated rats. Cisplatin increased serum blood urea nitrogen and creatinine levels, and the fractional excretion of sodium. Cisplatin decreased the glomerular filtration rate, promoted histological renal injury and the expression of many pro-apoptotic proteins in the renal cortex, increased the Bax/Bcl2 ratio, and oxidative stress in kidney tissue and urine. All these features were decreased by cilastatin, which preserved renal function but did not modify the pharmacokinetics of cisplatin area under the curve. The cisplatin-induced death of cervical, colon, breast, and bladder-derived cancer cell lines was not prevented by cilastatin. Thus, cilastatin has the potential to prevent cisplatin nephrotoxicity without compromising its anticancer efficacy.

A major area in cancer therapy is the search for protective strategies against cisplatin-induced nephrotoxicity. We investigated the protective effect of cilastatin on cisplatininduced injury to renal proximal tubular cells. Cilastatin is a specific inhibitor of renal dehydrodipeptidase I (DHP-I), which prevents hydrolysis of imipenem and its accumulation in the proximal tubule. Primary cultures of proximal cells were treated with cisplatin (1-30 M) in the presence or absence of cilastatin (200 g/ml). Apoptosis and mitochondrial injury were assessed by different techniques. Cisplatin uptake and DNA binding were measured by inductively coupled plasma spectrometry. HeLa cells were used to control the effect of cilastatin on the tumoricidal activity of cisplatin. Cisplatin increased cell death, apoptotic-like morphology, caspase activation, and mitochondrial injury in proximal tubular cells in a dose-and time-dependent way. Concomitant treatment with cilastatin reduced cisplatin-induced changes. Cilastatin also reduced the DNA-bound platinum but did not modify cisplatin-dependent up-regulation of death receptors (Fas) or ligands (tumor necrosis factor ␣, Fas ligand). In contrast, cilastatin did not show any effects on cisplatintreated HeLa cells. Renal DHP-I was virtually absent in HeLa cells. Cilastatin attenuates cisplatin-induced cell death in proximal tubular cells without reducing the cytotoxic activity of cisplatin in tumor cells. Our findings suggest that the affinity of cilastatin for renal dipeptidase makes this effect specific for proximal tubular cells and may be related to a reduction in intracellular drug accumulation. Therefore, cilastatin administration might represent a novel strategy in the prevention of cisplatin-induced acute renal injury.

Background Exhausting exercise reduces the mitochondrial DNA (mtDNA) content in the skeletal muscle of healthy subjects due to oxidative damage. Since patients with chronic obstructive pulmonary disease (COPD) suffer enhanced oxidative stress during exercise, it was hypothesised that the mtDNA content will be further reduced. Objective To investigate the effects of exercise above and below the lactate threshold (LT) on the mtDNA content of skeletal muscle of patients with COPD. Methods Eleven patients with COPD (6768 years; forced expiratory volume in 1 s (FEV 1 ) 4568%ref) and 10 healthy controls (6664 years; FEV 1 9067% ref) cycled 45 min above LT (65% peak oxygen uptake (V 9 O 2 peak) and another 7 patients (6566 years; FEV 1 5064%ref) and 7 controls (5669 years; FEV 1 9266%ref) cycled 45 min below their LT (50% V 9 O 2 peak). Biopsies from the vastus lateralis muscle were obtained before exercise, immediately after and 1 h, 1 day and 1 week later to determine by PCR the mtDNA/nuclear DNA (nDNA) ratio (a marker of mtDNA content) and the expression of the peroxisome proliferator-activated receptor-gcoactivator-1a (PGC-1a) mRNA and the amount of reactive oxygen species produced during exercise was estimated from total V 9 O 2 . Results Skeletal muscle mtDNA/nDNA fell significantly after exercise above the LT both in controls and in patients with COPD, but the changes were greater in those with COPD. These changes correlated with production of reactive oxygen species, increases in manganese superoxide dismutase and PGC-1a mRNA and returned to baseline values 1 week later. This pattern of response was also observed, albeit minimised, in patients exercising below the LT. Conclusions In patients with COPD, exercise enhances the decrease in mtDNA content of skeletal muscle and the expression of PGC-1a mRNA seen in healthy subjects, probably due to oxidative stress.