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J Arenas

Publications and source records attributed to J Arenas.

At least 145 records · Page 8Linked to original sources
PubMed1996

Cyclosporine nephrotoxicity and rejection crisis: diagnosis by urinary enzyme excretion.

The urinary enzymes alanine aminopeptidase (AAP; EC 3.4.11.2) and N-acetyl-B-D-glucosaminidase (NAG; EC 3.2.1.30) were measured daily in 35 renal transplant recipients during the early postoperative period. Each peak value of fractional excretion was corrected for its baseline value (CFE). CFE values above normal for both NAG and AAP were more frequently found in episodes of acute rejection than in cyclosporine acute nephrotoxicity episodes (76 vs. 0%; p < 0.001). Consequently, a rise in CFE levels for both NAG and AAP is strongly suggestive of acute rejection crisis.

Acetylglucosaminidase↗
PubMed1996

Leber's congenital amaurosis associated with mitochondrial dysfunction.

We report the case histories of two 6-month-old girls, both with young, nonconsanguineous parents, referred to us for suspected blindness. In both cases, Leber's congenital amaurosis was diagnosed. Due to persistently high lactic acid levels in blood, muscle biopsies were taken. Analysis of biopsies revealed that both patients had low levels of complex IV of the mitochondrial respiratory chain; one patient additionally had low levels of complex III. Microscopic and ultrastructural alterations of muscle, typically observed in mitochondrial disorders, were observed only in the second patient. These observations raise the possibility that at least some cases of Leber's congenital amaurosis may be due to alterations in the mitochondrial respiratory chain.

Age of Onset↗
PubMed1996

Respiratory-chain enzyme activities in isolated mitochondria of lymphocytes from untreated Parkinson's disease patients. Grupo-Centro de Trastornos del Movimiento.

We studied respiratory-chain enzyme activities in lymphocyte mitochondria from 36 untreated Parkinson's disease (PD) patients and in 30 age- and sex-matched healthy controls. The respiratory-chain enzyme activities did not differ significantly between patients and controls. Moreover, no patient showed respiratory-chain enzyme levels below normal range. Values for activities of complexes in the PD group did not correlate with age at onset, duration, scores of the Unified Parkinson's Disease Rating scales, or Hoehn and Yahr staging. These results suggest that the presence of defects of respiratory-chain complexes could depend on methodologic aspects, and that determinations of respiratory-chain enzymes in cell homogenates are not generally appropriate for evaluating abnormal mitochondrial dysfunction, especially when the amount of the specific enzyme is relatively low, as is the case of blood cells. In addition, the method of measuring complex I activity is critical for evaluating the results. In conclusion, our finding of normal mitochondrial function in lymphocyte mitochondria suggests that this tissue cannot be used to develop a diagnostic test for PD.

Citrate (si)-Synthase↗
PubMed1996

Single large-scale mitochondrial DNA deletion in a patient with mitochondrial myopathy associated with multiple symmetric lipomatosis.

In a nonalcoholic woman with multiple symmetric lipomatosis (MSL), muscle histochemistry showed ragged-red fibers and cytochrome c oxidase negative fibers. Southern blot analysis revealed a single deletion of mitochondrial DNA (mtDNA). We suggest that MSL is an uncommon manifestation of the wide clinical spectrum of mitochondrial disorders, in particular of those associated with single mtDNA deletions.

Blotting, Southern↗
PubMed1995

Mitochondrial DNA deletion in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes (MELAS) and Fanconi's syndrome.

Large-scale mitochondrial DNA deletion was found in a 5-year-old girl with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and Fanconi's syndrome. Muscle biopsy disclosed ragged-red fibers and cytochrome c oxidase negative fibers. Respiratory chain studies were normal. Southern blot analysis demonstrated a 10.5-Kb heteroplasmic deletion in both muscle and blood. Deleted genomes represented 40% of total mitochondrial DNA in muscle and 63% in blood. There was no evidence of point mutations characteristic of MELAS. We suggest that not only patients with progressive external ophthalmoplegia syndromes, but also those with defined syndromes [e.g., MELAS or myoclonic epilepsy and ragged-red fibers (MERRF)] without characteristic point mutations, be screened for mitochondrial DNA deletions.

Biopsy↗
PubMed1995

Clinical heterogeneity in two pedigrees with the 3243 bp tRNA(Leu(UUR)) mutation of mitochondrial DNA.

We studied two pedigrees with a mutation at the nucleotide 3243 of mitochondrial DNA (mtDNA). The proband from the first pedigree had clinically defined MELAS plus maternally transmitted insulin-dependent diabetes mellitus (IDDM). The propositus of the other pedigree had exercise intolerance, lactic acidosis and ragged-red fibers (RRF). In the first pedigree, both the mother and the sister's proband harbored the point mutation in their muscle. The mother had 40% of mutant mitochondrial genomes and the sister 70%. In the second pedigree, the mutation was present in both muscle and blood from the proband as well as in blood from all other members studied. Proportion of mutant mtDNA was 90% in muscle and ranged from 40% to 90% in blood.

Adult↗
PubMed1995

Respiratory chain enzyme defects in patients with idiopathic inflammatory myopathy.

OBJECTIVE: To analyse muscle respiratory chain enzymes in idiopathic inflammatory myopathy. METHODS: Four consecutive female patients seen at our hospital with idiopathic inflammatory myopathy were studied. Muscle histochemical staining included NADH tetrazolium reductase and succinate dehydrogenase tests. Activity of rotenone sensitive NADH cytochrome c reductase (complex I and III) succinate dehydrogenase (complex II), succinate cytochrome c reductase (complex II and III), cytochrome c oxidase (complex IV), and citrate synthase (a mitochondrial matrix enzyme), was measured spectrophotometrically in muscle homogenates. Free carnitine, and short and long chain acylcarnitine esters were determined in muscle homogenates by a radiochemical procedure. RESULTS: Three patients had mitochondrial proliferation in nonregenerating muscle fibres; these patients had defects of respiratory chain enzyme complexes. Carnitine concentrations, measured in two of the four patients, revealed carnitine deficiency in one. CONCLUSION: Our results suggest that mitochondrial dysfunction may be present in patients with inflammatory myositis.

Adolescent↗
PubMed1995

[Adult onset mitochondrial myopathy without ophthalmoplegia. Four cases attributable to complex III and IV deficits in the respiratory chain].

Four adults with proximal myopathy of mitochondrial origin but no ocular involvement are presented. Biochemical analysis showed combined complex III and IV deficits in the respiratory chain in all cases, suggesting an apparent correlation between clinical phenotype and biochemical findings. Mitochondrial DNA analysis of muscle from 1 patient failed to detect either large-scale deletion or point mutations at position 3243 of tRNA(Leu(UUR)) or at 8344 of tRNA(Lys). The tissue specificity of the disease and the absence of family history suggest that a mutation in a nuclear DNA gene encoding a specific subunit of muscle could underlie this disease.

Adult↗
PubMed1995

[Molecular genetics of mitochondrial cytopathologies].

In recent years new descriptions of basic structural and functional aspects of mitochondrial DNA have furthered our understanding of the role mitochondrial genome mutations play in human diseases. These mutations can be classified in two large groups: deletions and duplications, and point mutations. Deletions are typically sporadic and patients that carry them have varying types of symptoms. Point mutations, which affect genes that code tRNAs or genes that code mitochondrial respiratory chain proteins, are inherited through the maternal line and are also associated to a wide range of clinical signs. Some alterations are inherited according to a Mendelian pattern, involving multiple deletions and duplications of mitochondrial DNA caused by a defect in a factor coded by the nuclear genome and implicated in the regularization and replication or transcription of the mitochondrial genome. These changes are also related, directly or indirectly, to aging and to such common diseases as maternally transmitted diabetes.

DNA Replication↗
PubMed1994

Plasma levels of nitrates in patients with Parkinson's disease.

It has been suggested that nitric oxide (NO) could be implicated in the neuronal degeneration of substantia nigra compacta in patients with Parkinson's disease (PD). To ascertain the possible role of NO as risk factor for PD, we studied the plasma levels of nitrate (oxidation product that provides an indirect estimation of NO), in 68 PD patients and 68 matched-controls. The plasma levels of nitrate did not differ significantly between PD patient and control groups (44.5 +/- 2.46 and 44.8 +/- 2.67 mumol/l, respectively). They were not influenced by antiparkinsonian drug and they did not correlate with age at onset, duration, scores of the Unified Parkinson's Disease Rating scales and Hoehn and Yahr staging in the PD group. These data suggest that plasma levels of nitrate are apparently unrelated to the risk for PD.

Aged↗
PubMed1994

Effects of L-carnitine on the pyruvate dehydrogenase complex and carnitine palmitoyl transferase activities in muscle of endurance athletes.

The effects of L-carnitine on the pyruvate dehydrogenase (PDH) complex and carnitine palmitoyl transferase (CPT) were studied in muscle of 16 long-distance runners (LDR). These subjects received placebo or L-carnitine (2 g orally) during a 4-week period of training. Athletes receiving L-carnitine showed a dramatic increase (P < 0.001) in the PDH complex activities. By contrast, the levels of CPT, both 1 and 2, were unchanged. No significant changes were observed after placebo administration. We previously reported [Huertas R. et al., Biochem. Biophys. Res. Commun. 188 (1992) 102-107] that L-carnitine induces an increase in the activities of complexes I, III and IV of the respiratory chain in muscle of LDR. Taken together, our data suggest that the improvement in (maximal oxygen consumption) VO2max observed in LDR after L-carnitine administration is based on these biochemical findings.

Adult↗
PubMed1994

Benign mitochondrial myopathy with decreased succinate cytochrome C reductase activity.

In most of the cases previously described, the defect on complex II was suggested by low activity of succinate cytochrome C reductase (SCCR). The clinical pattern of the previous 10 cases is heterogeneous and may be limited to one particular tissue or be of a more general nature. We report a 22-year-old-woman, daughter of consanguineous parents, with generalized muscle weakness, easy fatigability and benign course, who showed a decrease of SCCR activity in mitochondria of muscle fibers. Free carnitine (FC) concentration was decreased in muscle as well. The muscle biopsy showed a mild variation in fiber size, with fiber type I predominance, subsarcolemmal oxidative DPNH accumulations, excess of neutral lipids and abnormally large mitochondria with paracrystalline inclusions. A possible inheritance pattern is discussed. Coenzyme Q10 therapy in this patient induced a significant increase of global MRC index score and a decrease of the turns-mean amplitude ratio in the automatic analysis of the EMG.

Adult↗
PubMed1994

[Clinical and investigative approaches in mitochondrial diseases. A review of 15 cases].

The results of laboratory investigations in concerning 15 patients suspected of mitochondrial disease (MD) are presented. Our purpose is to provide an outline of the investigative modalities that support the clinical suspicion and have been found to be useful in the diagnosis. Five clinical groups were studied including 5 exercise intolerances (2 with inflammatory myopathy), 3 with myopathies (1 with dilated cardiomyopathy), 2 with progressive external oftalmoplegia (1 associated with cerebellar ataxia+epilepsy+hypertrophic cardiomyopathy+pes cavus), 4 with encephalopathies (3 with myoclonic encephalopathies with ataxia and dementia and 1 with epilepsy and tremor), and 1 with metabolic acidosis and cardiomyopathy. We used the following categories of investigative procedures: clinical phenotype analysis including pedigree study, neurophysiological tests, bicycle ergometric evaluation, neuroimaging, microscopic study of skeletal muscle biopsy, post-mortem examination, biochemical assays and molecular genetic studies. EMG showed myopathic changes in 5 cases, features of neuropathy in 2, mixed myopathic and neuropathic pattern in 1 and nonspecific changes in 3. EMG was normal in 3 patients. The most common skeletal muscle abnormalities were variation in fiber size (60%), lipid inclusions (33.3%), oxidative subsarcolemmal aggregates (26.7%) and ragged-red fibers (26.7%). Electron microscopy revealed mitochondrial abnormalities in 8 out of 14 patients' muscle biopsies, and in myocardiac and hepatic tissues of another. Site of biochemical defect was located in 12 patients. Complex I defect in 6, complexes I+IV deficiencies in 3, complex II defect in 1, complex IV deficiency in 1, complexes II+IV deficiencies in 1, and complex III defect in 1. In 2 patients the biochemical defect was not located. Mitochondrial DNA alterations were not found in 7 investigated patients. The clinical spectrum of MD has become increasingly wider. After the clinica suspicion, the diagnosis depends up on the appropriate use of skeletal muscle biopsy, biochemical investigations and molecular genetic techniques. Conventional EMG and automatic measurement of the electromyogram are particularly helpful in confirming the clinical suspicion in patients with predominantly central nervous system disease or in cases in which clinical signs are few.

Adolescent↗