PubMed Health⌕ Search

Biomedical subjects

O Miró

Publications and source records attributed to O Miró.

At least 55 records · Page 3Linked to original sources
PubMed1999

Effects of general anaesthetic procedures on mitochondrial function of human skeletal muscle.

BACKGROUND: General anaesthetics inhibit mitochondrial function in animal models. However, very few studies have been performed in humans, and the results have not been conclusive. METHODS: We prospectively studied the oxygen consumption and the individual enzyme activity of each complex of the mitochondrial respiratory chain of skeletal muscle mitochondria in 54 healthy individuals who underwent general anaesthesia for orthopaedic surgery. The control group (n = 54) was made up of individuals submitted to the same orthopaedic procedure under regional anaesthesia (n = 31), and patients who underwent muscle biopsies for diagnostic purposes by local anaesthesia (n = 23). RESULTS: We found a significant decrease in the oxidation of glutamate (-36%), succinate (-25%) and ascorbate (-29%) in the general anaesthetic group compared with the controls (P < 0.001 for all substrates). The level of such inhibition was similar for volatile anaesthetics with strong (halothane) or weak (isoflurane) negative inotropic effect. By contrast, the enzymatic activity of all individual complexes and the coupling of oxidative phosphorylation did not differ between the two groups. CONCLUSION: We conclude that during general anaesthetic procedures there is an extensive inhibition of substrate oxidation in human muscle mitochondria, and that it is not caused by a direct effect on complexes of the mitochondrial respiratory chain or through uncoupling oxidative phosphorylation.

Anesthesia, Conduction↗
PubMed1999

Absence of mitochondrial dysfunction in polymyalgia rheumatica. Evidence based on a simultaneous molecular and biochemical approach.

OBJECTIVE: To investigate the molecular and biochemical profile of skeletal muscle mitochondria of patients with isolated polymyalgia rheumatica (PMR). PATIENTS AND METHODS: We included patients with a recent diagnosis of PMR and as control healthy individuals submitted to orthopedic surgery. Skeletal muscle was obtained from quadriceps, thus was mitochondria immediately isolated. Long polymerase chain reaction and Southern blot transference were performed to detect deleted mtDNA molecules. Mitochondrial oxidative activity using different substrates and individual enzyme activity of respiratory chain complexes were assessed to search for any biochemical dysfunction. RESULTS: Fifty-one individuals (PMR=25, controls=26) were included. Mean age was 72 (11) years; 45% were females. We found no significant increase of deleted mtDNA molecules in PMR patients compared to controls. Both groups differed neither on oxygen consumption (p=NS for all substrates) nor enzymatic activity (p=NS for all complexes). CONCLUSIONS: Skeletal muscle mitochondria are molecularly and biochemically unaffected in PMR.

Adenosine Triphosphatases↗
PubMed1999

Smoking disturbs mitochondrial respiratory chain function and enhances lipid peroxidation on human circulating lymphocytes.

Mitochondria constitute a source of reactive oxygen species. We tested whether mitochondrial function from human circulating lymphocytes is affected by smoking habit and if this could be associated with an increase in oxidative damage of biological membranes. We prospectively studied 35 smokers and 35 non-smoking healthy individuals matched by age and sex, with a similar physical activity. Individual enzyme activity of complexes II, III and IV of the mitochondrial respiratory chain (MRC) and of glycerol-3-phosphate dehydrogenase activity were measured spectrophotometrically. Intact cell respiration and oxidative rates after addition of pyruvate, succinate and glycerol-3-phosphate were assessed polarographically. Lipid peroxidation of biological membranes was assessed measuring the loss of cis-parinaric acid fluorescence. Results are expressed as means (+/-SD). Smokers showed a significant decrease in complex IV activity compared with non-smokers (112.8 +/- 40.9 versus 146.4 +/- 62.5 nmol/min/mg protein, respectively; 23% of inhibition; P = 0.01), while the rest of the complexes of MRC were unaffected. Conversely, oxidative rate with succinate, but not with the other substrates, was enhanced in smokers compared with non-smokers (16.7 +/- 10.4 versus 11.4 +/- 4.7 nmol oxygen/min/mg protein, respectively; 46% of activation; P = 0. 01). Lipid peroxidation of lymphocyte membranes was increased in smokers with respect to non-smokers (3.49 +/- 1.27 versus 4.39 +/- 1. 76 units of fluorescence/mg protein, respectively; 21% of increase; P = 0.03) and this increase correlated positively with succinate oxidation activation (R = 0.34, P = 0.02) and, to a lesser extent, with complex IV inhibition, although it did not reach statistical significance (R = 0.19, P = 0.18). In smokers, the MRC function of lymphocytes is disturbed and correlates with the degree of oxidative damage of membranes. This mitochondrial dysfunction could contribute to increased endogenous production of reactive oxygen species and could play a role in tobacco carcinogenicity.

Adult↗
PubMed1999

Skeletal muscle mitochondrial function in polymyalgia rheumatica and in giant cell arteritis.

OBJECTIVE: To ascertain whether mitochondrial function is impaired in polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). PATIENTS AND METHODS: Thirteen patients suffering from isolated PMR, 19 from GCA (eight with and 11 without PMR) and 25 healthy people submitted to orthopaedic surgery were included. Skeletal muscle was obtained from the quadriceps by open biopsy. Mitochondrial histological abnormalities were assessed on Gomori's trichrome staining and on cytochrome c oxidase and succinic dehydrogenase reactions. Biochemical studies consisted of polarographic measurement of oxidative activity using complex I, II, III and IV substrates, and spectrophotometric determination of individual enzymatic activity of such complexes. RESULTS: We did not find differences among groups either with respect to the percentage of histological or histochemical abnormalities [P = not significant (NS) for all stainings and reactions], oxidative capacity (P = NS for all substrates) or individual enzymatic activities (P = NS for all complexes). CONCLUSION: Skeletal muscle mitochondria remain histologically and functionally unaffected in PMR and in GCA.

Aged↗
PubMed1999

Decreased health care quality associated with emergency department overcrowding.

The objective of this study was to assess the influence of overcrowding on health care quality provided by emergency departments (ED). The study was carried out in an urban, university tertiary care hospital. All patients seen at the internal medicine unit (IMU) of the ED who returned during the following 72 hours, and those who died in the ED rooms were included in the study. During a consecutive period of 2 years (104 weeks), we prospectively quantified the number of weekly visits, revisits and deaths. We calculated revisit and mortality rates (in respect of percentage of all visited patients) for each week. Correlation between the number of weekly visits, and revisit and mortality rates was assessed using a simple linear regression model. We consigned 81,301 visits, 1137 revisits and 648 deaths; mean (+/- SD) number of weekly visits, revisits and deaths were 782 (68), 10.93 (3.97) and 6.23 (3.04) respectively; weekly revisit rate was 1.40% (0.48%) and weekly mortality rate was 0.79% (0.36%). We observed a significant, positive correlation between mortality rates and weekly number of visits (p = 0.01). Although a similar trend was also found for revisit rates, such an increase did not reach statistical significance (p = 0.06). It is concluded that since revisit and mortality rates constitute good health care quality markers, present data demonstrate that ED overcrowding implies a decrease in the health care quality provided by it.

Crowding↗
PubMed1999

Highly effective compensatory mechanisms in a 76-year-old man with a coarctation of the aorta.

We present a man who was diagnosed with coarctation of the aorta (CA) at the age of 76. He had developed an extensive collateral circulation for maintaining the circulation below the CA. This compensatory mechanism was highly effective, since the patient had remained asymptomatic and in good health during most of his life. He died from intrahospitalary pneumonia, unrelated to CA. Long-term survival in patients with untreated CA is exceptional, with only 11 patients living into their 70s being previously reported. A review of these cases is included.

Adaptation, Physiological↗
PubMed1998

Biochemical and molecular effects of chronic haloperidol administration on brain and muscle mitochondria of rats.

The objectives of the current study were to evaluate (1) the respiratory rates and enzyme activities of brain and muscle mitochondria from rats chronically treated with haloperidol, (2) the protective role of dopamine (DA) D-1 (SKF38393) and D-2 (quinpirole) receptor agonists, and (3) the effect of haloperidol on the mitochondrial DNA (mtDNA) and protein synthesis. Thirty male Sprague-Dawley rats were subdivided into the following five groups: controls, haloperidol, haloperidol plus SKF38393, haloperidol plus quinpirole, and haloperidol plus SKF38393 and quinpirole. We compared the respiratory rates and enzymatic activities of brain and muscle mitochondria from controls with other groups. We finally analyzed the mitochondrial protein synthesis and mtDNA alterations (deletions, point mutations, and depletion) in two rats from each group. In brain but not in muscle from haloperidol-treated rats, we found a decrease of oxygen consumption rates using glutamate plus malate (-68 +/- 35%, P < 0.05) and succinate (-78 +/- 20%, P < 0.05) as substrates as well as low complex I, II, and V activities (-35 +/- 15%, P < 0.05; -54 +/- 13%, P < 0.05; and -60 +/- 33%, P < 0.01; respectively). The administration of SKF38393 alone or together with quinpirole prevented most of haloperidol-induced effects, whereas the protective effects of quinpirole alone were lower. Brain mitochondrial protein synthesis was decreased in haloperidol-treated rats and was not prevented by SKF38393, quinpirole, or both. We did not find mtDNA abnormalities in brain or muscle mitochondria from haloperidol-treated rats. Chronic administration of haloperidol in rats is associated with a nonspecific deleterious effect in the activity of electron transport chain of brain, and this effect is only partially prevented by DA D-1 agonists. These results suggest that other mechanisms different from DA receptors pathway can contribute to the expression of behavioral supersensitivity.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1998

Clinical, histological and molecular reversibility of zidovudine myopathy.

The use of zidovudine in the treatment of human immunodeficiency virus infection has been associated with toxic mitochondrial myopathy. There are some reported cases of improvement after stopping the drug, but in only one were molecular studies performed. We therefore studied three patients with toxic AZT myopathy during AZT treatment and after drug withdrawal. Clinical complaints disappeared within the next three months after drug cessation. In all cases, histological data of mitochondrial abnormalities also disappeared. Molecular studies showed an initial depletion of the total amount of mitochondrial DNA with respect to healthy controls which was reversible after AZT withdrawal. This work demonstrates that AZT myopathy is reversible not only at a clinical and histological, but also at a molecular level.

Adult↗
PubMed1998

Cytochrome c oxidase assay in minute amounts of human skeletal muscle using single wavelength spectrophotometers.

Determination of cytochrome c oxidase (COX; EC 1.9.3.1) activity in human mitochondria presents several technical difficulties which result in a large intra- and interlaboratory variability, especially when a single wavelength spectrophotometer (SWS) is used, as is generally done in most laboratories in the context of screening procedures for the detection of respiratory chain deficiencies. We studied the experimental conditions of COX assay in human skeletal muscle mitochondria using a SWS in order to define the optimal conditions for the assay and compared these results with those obtained using a double wavelength spectrophotometer (DWS). We demonstrate that a low intra-individual variability of COX assay can be obtained with SWS by: (1) using manual stirrers to avoid the formation of bubbles in the mixture; (2) preincubating mitochondria and laurylmaltoside before the addition of cytochrome c, which prevents light scattering secondary to mitochondrial swelling; and (3) using low amounts (1-2 microg) of mitochondrial protein to extend and linearize the reaction rate. Under these experimental conditions, the concordance between SWS and DWS was very good (R=0.975).

Electron Transport↗
PubMed1998

Mitochondrial cytochrome c oxidase inhibition during acute carbon monoxide poisoning.

Clinical symptoms of acute carbon monoxide (CO) poisoning are mainly related to the capability of haemoglobin to bind CO. However, the persistence of some clinical alterations after carboxyhaemoglobin normalization suggests that other heme containing proteins, like cytochrome c oxidase, could play a role in its pathogenesis. We studied mitochondrial enzyme activities of lymphocytes from three patients suffering from acute CO poisoning. HbCO levels were 11.6%. 19.6% and 22.3% in the acute phase, 2.3%, 2.4% and 1.5% on day 3 after admission, and 1.2%, 3.3% and 1.1% on day 12. Complex II, III and glycerol-3-phosphate dehydrogenase activities remained normal along the study, while cytochrome c oxidase (complex IV) activity showed a 76% inhibition compared to controls during acute poisoning (P < 0.01) and 48% at day 3 (P < 0.05). The activity was normal already on day 12 after the complete disappearance of symptomatology. Our results suggest that mitochondrial cytochrome c oxidase is also a target site in human acute CO poisoning, and its extended and generalized inhibition could explain the persistence of different symptoms after the normalization of HbCO levels.

Acute-Phase Proteins↗
PubMed1998

Pacemaker-related endocarditis. Report of 7 cases and review of the literature.

We report on 7 patients with pacemaker endocarditis diagnosed during the workup of long-standing fever. Persistent positive blood cultures and echocardiography led to the diagnosis in 6 patients whereas autopsy was diagnostic in another. Causative microorganisms were Staphylococcus epidermidis (3), Staphylococcus lugdunensis (1), Pseudomonas aeruginosa (1), Streptococcus bovis (1), and Streptococcus mitis-Streptococcus sanguis (1). Pulmonary embolism was present in nearly 50% of the cases, a figure clearly higher than previously reported. In all but 1 case the initial medical approach was not successful, and thus the pacing system was finally removed. None of the cases relapsed after the removal. We have reviewed the literature regarding pacemaker endocarditis, particularly with respect to treatment.

Aged↗
PubMed1998

Histological and biochemical assessment of mitochondrial function in dermatomyositis.

OBJECTIVE: Mitochondrial dysfunction in idiopathic inflammatory myopathies (IIM) remains a controversial issue. The aim of the present study was to investigate the correlation between histological abnormalities and the biochemical function of the skeletal muscle mitochondria from patients with dermatomyositis (DM). METHOD: We evaluated 10 patients with a new diagnosis of DM and 15 healthy individuals, matched by age and gender. Muscle biopsy was routinely processed for histochemical studies and biochemical analysis of pure mitochondria. The percentages of ragged-red fibres (RRF), cytochrome c oxidase (COX)-negative fibres and succinic dehydrogenase (SDH) hyper-reactive fibres were calculated, oxygen utilization using different substrates was assessed polarographically, and enzymatic activity of individual complexes of the electron transport chain (ETC) and ATPase was measured spectrophotometrically. RESULTS: We found an increased percentage of COX-negative and SDH hyper-reactive fibres in DM patients (0.82 and 1.82%, respectively) compared to controls (0.26 and 0.22%; P < 0.05 and P = 0.001, respectively); however, oxidation rates of different substrates and enzymatic activities of ETC and ATPase did not differ significantly between both groups. CONCLUSION: The overall function of ETC from skeletal muscle mitochondria is not affected in DM.

Adenosine Triphosphatases↗
PubMed1997

Skeletal muscle studies in patients with HIV-related wasting syndrome.

Previous reports have suggested that HIV-related wasting syndrome may be considered as a form of myopathy. The aim of the present study was to investigate histopathological muscle changes in HIV-related wasting syndrome in order to know if there is a common substrate and whether muscle plays a primary or secondary role in its development. Patients with wasting syndrome diagnosed by Centers for Disease Control (CDC) criteria were prospectively evaluated. Clinical, analytical, nutritional, anthropometrical and muscular data were recorded. The patients were subdivided into two groups: group A was constituted by patients in whom wasting syndrome was the AIDS-defining illness, and group B by patients in whom AIDS diagnosis was previously made. In all cases muscle biopsy was performed and processed for conventional stainings and histochemical reactions. Thirty patients were included (group A, 12; group B, 18). Clinical, analytical, nutritional and anthropometrical data did not essentially differ between the two groups. All patients were malnourished with respect to controls. Histopathological findings in muscle biopsy were heterogeneous and similar in both groups, except for HIV-related myopathies, which were more frequently seen in the patients from group A (P=0.05). In five cases (17%) an unsuspected and potentially treatable myopathy was diagnosed. Patients with polyarteritis nodosa (two) or polymyositis (one) were treated with prednisone, which improved their wasting syndrome. By contrast, patients with AZT-myopathy (two) did not improve when the drug was discontinued. We conclude that in most cases the wasting syndrome cannot be considered as a true myopathy, and probably metabolic and/or nutritional factors may account for wasting development. However, in a subset of patients muscle biopsy allows the diagnosis of a treatable myopathy leading to the improvement of wasting syndrome.

Adult↗
PubMed1997

["Multicore" myopathy: report of 5 cases].

Five cases (three of them from a same family) of multicore myopathy are presented. The age at diagnosis ranged from 4 to 38 years. In 2 cases muscle complaints developed early in childhood while in the remaining 3 cases raised CK serum levels lead to perform a muscle biopsy. Malignant hyperthermia occurred in a young boy among the three affected relatives. Other family members are probably affected, suggesting an autosomal dominant inheritance. In none of the patients progressive disabling myopathy has occurred after a long term follow-up. A review of the bibliography is included, and clinical and evolutive characteristics of this myopathy are commented.

Adolescent↗