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J Arenas

Publications and source records attributed to J Arenas.

At least 109 records · Page 6Linked to original sources
PubMed1998

Cerebrospinal fluid levels of alpha-tocopherol in amyotrophic lateral sclerosis.

We compared CSF and serum levels, and the CSF/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 30 patients with sporadic amyotrophic lateral sclerosis (SALS) and 78 matched controls. The mean CSF and serum vitamin E levels did not differ significantly between the 2 study groups. These values were not influenced by the clinical form (spinal versus bulbar) of SALS. CSF alpha-tocopherol levels did not correlate with age, age at onset, and duration of the disease. These results suggest that CSF and serum alpha-tocopherol concentrations are unrelated with the risk for ALS.

Aged↗
PubMed1998

Biological roles of L-carnitine in perinatal metabolism.

Carnitine performs a crucial role in the energy supply of tissues during fetal life and in the neonatal period by controlling the influx of fatty acids into mitochondria. Carnitine also facilitates the oxidation of pyruvate and branched chain amino acids, and contributes to the protection of cells from the deleterious actions of acyl CoAs. Carnitine further acts as a secondary antioxidant, favouring fatty acid replacement within previously oxidatively damaged membrane phospholipids. Availability of L-carnitine is essential in the developing fetus for processes underlying fetal maturation. L-carnitine is also essential for development of hepatic ketone synthesis, a central pathway for neonatal energy metabolism. Ketone bodies inhibit the oxidation of both glucose and lactate, sparing these metabolic substrates for biosynthetic functions.

Carnitine↗
PubMed1998

Clinical heterogeneity associated with mitochondrial DNA depletion in muscle.

We studied 10 patients with a variable degree of mtDNA depletion in muscle. Seven patients showed a clear-cut myopathic pattern, while the three remaining had brain involvement. There was no relationship between age at onset and relative mtDNA copy number in muscle, but we found an apparent correlation between clinical severity and degree of muscle mtDNA depletion. Muscle morphology showed that mtDNA depletion was associated with mitochondrial proliferation and cytochrome c oxidase negative fibers. Biochemical studies revealed single or combined defects of mtDNA-dependent respiratory chain complexes. Our data indicate that patients with mtDNA depletion may have a more variable age at onset and clinical evolution and wider phenotype than previously thought. The diagnosis of this condition, so far regarded as rare, may have been overlooked to some extent.

Age Factors↗
PubMed1998

Effects of L-carnitine on erythrocyte acyl-CoA, free CoA, and glycerophospholipid acyltransferase in uremia.

We studied the effects of L-carnitine treatment in the acyl flux of erythrocyte membranes from uremic patients. We found a significantly lower relative proportion of long-chain acyl-CoA (LCCoA) to free CoA (FCoA) in patients than in control subjects. In addition, patients had reduced activities of both carnitine palmitoyltransferase (CPT) and glycerophospholipid acyltransferase (LAT; CoA dependent), and increased ratios of long-chain acylcarnitine (LCAC) to free carnitine in their erythrocytes. These data support the hypothesis that acyl-trafficking is altered in erythrocytes in uremia. After treatment with L-carnitine, we observed a significant increase in CPT and LAT activities as well as in the LCCoA-FCoA ratio, and a significant decrease in the ratio of LCAC to free carnitine. These results support the conclusion that L-carnitine supplementation improves erythrocyte flux in uremic patients.

Acyl Coenzyme A↗
PubMed1998

Prospective study of serum and urinary nitrate levels in patients with systemic lupus erythematosus.

OBJECTIVE: To study prospectively whether serum and urinary nitrate levels are related to lupus activity. METHODS: Fifty patients with systemic lupus erythematosus (SLE) were studied prospectively for 2 yr. Every 4 months, the SLE Disease Activity Index (SLEDAI) was administered to the patients, and blood and 24 h urine samples were obtained; 88 healthy controls were also studied. Nitrate levels were measured by the Greiss method. Statistical analyses were performed using standard parametric and non-parametric tests, and analysis of serial measurements. RESULTS: Twelve patients suffered infections, 12 active nephritis and 17 episodes of non-renal activity. By analysis of serial measurements, serum and urinary nitrate levels did not correlate with SLEDAI. C-Reactive protein (CRP) levels, presence of infection and creatinine clearance weakly influenced nitrate levels. CONCLUSIONS: In SLE, serum and urinary nitrate levels do not parallel lupus activity. Other variables, related or not to SLE, seem to affect these levels.

Adolescent↗
PubMed1998

[Mitochondrial respiratory chain deficiency may present as multiple sclerosis].

Defects of the mitochondrial respiratory chain are associated with a great variety of clinical disorders. In addition to the well recognized syndromes, a significant number of patients present non-specific encephalopathic disorders. In consequence these types of mitochondrial disorder are very difficult to diagnose on clinical features alone. In this paper, we describe the clinical and the magnetic resonance findings of 2 patients with a neurological syndrome indistinguishable from multiple sclerosis (Poser). Muscle biochemistry revealed defect of complex IV of the respiratory chain. We think that these patients have a mitochondrial encephalomyopathy. We suggest that in patients presenting as atypical multiple sclerosis it could be necessary investigating mitocondrial encephalopathy.

Adult↗
PubMed1998

Correlation of sperm motility with mitochondrial enzymatic activities.

Until now, little attention has been paid to the contribution of mitochondrial dysfunction to germinal tissue disorders. The target of this study was to investigate the relationship between sperm motility and mitochondrial respiratory chain enzyme activities. The results obtained showed that semen samples of control individuals (n = 33) have substantially higher activities of complexes I, II, and IV compared with those of asthenozoospermic subjects (n = 86). Moreover, a direct and positive correlation was found in the whole population studied between spermatozoa motility and all the mitochondrial respiratory complex activities assayed (I, II, I+III, II+III, and IV). The ratio of these enzymes to citrate synthase (a reliable enzymatic marker of mitochondrial volume) activities did not correlate with sperm motility. This suggests that motility depends largely on the mitochondrial volume within the sperm midpiece. These observations could be of physiopathological relevance because they suggest that factors affecting the mitochondrial energy production could be then responsible for particular cases of idiopathic asthenozoospermia.

Citrate (si)-Synthase↗
PubMed1998

Histochemical study of the vastus lateralis muscle fibre types of athletes.

In 16 women and 66 men, aged 14 to 36 years, 10 sedentary and 72 athletes, the histochemical characteristics of the vastus muscle fibres have been studied. Muscle biopsies were processed histochemically using the myofibrillar ATPase method, and were classified according to gender, sport activity and type of exercise. The average diameter of muscle fibres was larger in men than in women and in trained individuals than in sedentary ones. The largest percentage of Type I fibres was found in long distance runners; the smallest in those performing karate and triple jump. The largest percentage of Type IIA fibres was found in swimmers and the smallest in footballers. The largest percentages of Type IIB and IIC fibres were found in footballers. The largest average diameters of Type I and Type II fibres were found in swimmers and in long distance athletes respectively. Type I and Type II fibres were dominant in the aerobic group and the anaerobic one, respectively; the percentage of Type IIC fibres was smaller in the anaerobic group.

Adenosine Triphosphatases↗
PubMed1998

[Enzyme complex defects of the mitochondrial respiratory chain].

The mitochondrial respiratory chain is the final step in oxidative metabolism and plays an essential part in the mechanisms of energy production. It is composed of five enzymatic complexes under the dual control of nuclear and mitochondrial genomes. The disorders caused by respiratory chain defects are heterogeneous, mainly affecting organs and tissues which are functionally dependent on oxidative metabolism, such as brain, muscle, myocardium, kidney and liver. The activity of the enzymatic complexes may be measured in any tissue or organ, but skeletal muscle is usually used since it is post-mitotic and permits correlation with morphological studies. Defects in the electron transport chain may affect one or more complexes. Monoenzymopathies are characteristic of nuclear alterations, particularly if there is phenotype histo-specificity. However, mutations of the structural genes of the mitochondrial DNA (mtDNA) may also produce specific defects. Combined defects are characteristic of mtDNA alterations due to reduced synthesis of mitochondrial proteins.

DNA, Mitochondrial↗
PubMed1998

[Molecular genetics of alterations in the mitochondrial respiratory chain].

Mitochondrial biogenesis is the result of the coordinated action of two genomes, nuclear (nDNA) and mitochondrial (mtDNA). Therefore respiratory chain defects are divided into alterations of mtDNA and of nDNA. The former may be due to sporadic isolated deletions and specific duplications and mutations, which are both transmitted maternally. The nDNA disorders are inherited following a mendelian pattern and may affect genes which codify enzymes, genes which take part in the process of importing proteins, or genes involved in intergenomic communication. In the latter case, the alterations are seen in the mtDNA as multiple deletions or depletion. The characteristics of mitochondrial genetics are maternal inheritance, polyplasmia, heteroplasmia, mitotic segregation and threshold effect and largely explain the characteristic phenotype behaviour specific to these changes.

DNA, Mitochondrial↗
PubMed1997

Cloning of mDEAH9, a putative RNA helicase and mammalian homologue of Saccharomyces cerevisiae splicing factor Prp43.

Yeast splicing factor Prp43, a DEAH box protein of the putative RNA helicase/RNA-dependent NTPase family, is a splicing factor that functions late in the pre-mRNA splicing pathway to facilitate spliceosome disassembly. In this paper we report cDNA cloning and characterization of mDEAH9, an apparent mammalian homologue of Prp43. Amino acid sequence comparison revealed that the two proteins are approximately 65% identical over a 500-aa region spanning the central helicase domain and the C-terminal region. Expression of mDEAH9 in S. cerevisiae bearing a temperature-sensitive mutation in prp43 was sufficient to restore growth at the nonpermissive temperature. This functional complementation was specific, as mouse mDEAH9 failed to complement mutations in related splicing factor genes prp16 or prp22. Finally, double label immunofluorescence experiments performed with mammalian cells revealed colocalization of mDEAH9 and splicing factor SC35 in punctate nuclear speckles. Thus, the hypothesis that mDEAH9 represents the mammalian homologue of yeast Prp43 is supported by its high sequence homology, functional complementation, and colocalization with a known splicing factor in the nucleus. Our results provide additional support for the hypothesis that the spliceosomal machinery that mediates regulated, dynamic changes in conformation of pre-mRNA and snRNP RNAs has been highly conserved through evolution.

Amino Acid Sequence↗
PubMed1997

Bilateral striatal necrosis and MELAS associated with a new T3308C mutation in the mitochondrial ND1 gene.

We found a novel maternally inherited T3308C mutation in the mtDNA ND1 gene in a patient with bilateral striatal necrosis and stroke-like episodes. Muscle biopsy from the proband showed mitochondrial proliferation in blood vessels and normal respiratory chain activities. The mutation, which was not present in 100 normal controls or in 30 patients with mitochondrial disease, was heteroplasmic in both muscle and blood of the proband and in blood from her asymptomatic mother. This mutation results in a Met --> Thr change at the highly conserved amino acid position 1. The T3308C mutation may alter the hydrophobicity and antigenicity of the N-terminal peptide of ND1.

Adult↗
PubMed1997

Decreased cerebrospinal fluid levels of neutral and basic amino acids in patients with Parkinson's disease.

We measured the CSF levels of 21, and the plasma levels of 26, amino acids in 31 patients with Parkinson's disease (PD) and in 45 matched controls. We used an ion-exchange chromatography method. When compared to controls, PD patients had lower CSF levels of taurine, alanine, valine, leucine, isoleucine, ethanolamine, citrulline, ornithine, lysine, histidine, arginine, and alpha-aminobutyric acid. PD patients not treated with levodopa or with dopamine agonists had higher CSF tyrosine and phenylalanine levels than those not treated with these drugs and also than controls. PD patients had higher plasma levels of phosphoserine, threonine, methionine, tyrosine, sarcosine and alpha-aminoadipic acid, and lower plasma levels of valine, leucine, and tryptophan, than controls. The CSF/plasma ratio of many of these amino acids was significantly lower in PD patients than those of controls, suggesting that PD patients might have a dysfunction in the transport of neutral and basic amino acids across the blood-brain barrier.

Adult↗
PubMed1997

Cerebrospinal fluid carnitine levels in patients with Parkinson's disease.

We assessed free carnitine (FC) and acyl-carnitine esters (AC) in both CSF and plasma from 29 patients with diagnostic criteria for PD, and from 29 healthy matched-controls. FC and AC levels in both CSF and plasma did not differ significantly between PD patients and controls, they were not influenced significantly by anti-parkinsonian drugs, and did not correlate with age at onset, duration and severity of PD. These results suggest that CSF carnitine levels are apparently unrelated with the risk for PD.

Acylation↗
PubMed1997

Cerebrospinal fluid levels of alpha-tocopherol (vitamin E) in Alzheimer's disease.

We compared CSF and serum levels, and the CST/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 44 apparently well-nourished patients with Alzheimer's disease (AD) and 37 matched controls. CSF and serum vitamin E levels were correlated, both in AD patients and in controls. The mean CSF and serum vitamin E levels were significantly lower in AD patients, and the CSF/serum ratio of AD patients did not differ significantly between the 2 study groups. CSF vitamin E levels did not correlate with age, age at onset, duration of the disease and score of the Minimental State Examination in the AD group. Weight and body mass index were significantly lower in AD patients than in controls. These results suggest that low CSF and serum vitamin E concentrations in AD patients could be related with a deficiency of dietary intake of vitamin E.

Aged↗
PubMed1997

Cerebrospinal fluid levels of alpha-tocopherol (vitamin E) in Parkinson's disease.

We compared CSF and serum levels, and the CSF/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 34 patients with Parkinson's disease (PD) and 47 controls. CSF and serum vitamin E levels were correlate. The mean CSF and serum vitamin E levels, and the CSF/serum ratio of PD patients did not differ significantly between the groups. There was no influence of antiparkinsonian therapy on CSF vitamin E levels. CSF vitamin E levels did not correlate with age, age at onset, duration of the disease, scores of the Unified Parkinson Disease Rating Scale of the Hoehn and Yahr staging in the PD group. These results suggest that CSF vitamin E concentrations are unrelated with the risk for PD.

Aged↗
PubMed1997

The association of acetyl-L-carnitine with glucose and lipid metabolism in human muscle in vivo: the effect of hyperinsulinemia.

We examined whether hyperinsulinemia is associated with changes in the amount of L-carnitine and acetyl-L-carnitine in the muscle and whether the source of acetyl-coenzyme A (CoA) (glucose or free fatty acids [FFAs]) influences its further metabolism to acetyl-L-carnitine or through tricarboxylic acid in the skeletal muscle of man in vivo. Twelve healthy men (aged 45 +/- 2 years; body mass index, 25.2 +/- 1.0 kg/m2) were studied using a 4-hour euglycemic-hyperinsulinemic clamp (1.5 mU/kg/min) and indirect calorimetry. Although the mean muscle free L-carnitine and acetyl-L-carnitine concentrations remained unchanged during hyperinsulinemia in the group as a whole, the individual changes in muscle free L-carnitine and acetyl-L-carnitine concentrations were inversely related (r = -.72, P < .02). The basal level of acetyl-L-carnitine was inversely related to the rate of lipid oxidation (r = -.70, P < .02). In a stepwise linear regression analysis, 77% of the variation in the change of acetyl-L-carnitine concentrations was explained by the basal muscle glycogen level (inversely) and nonoxidative glucose disposal rate (directly) during hyperinsulinemia (P < .001); by adding the final FFA concentration (inverse correlation) to the model, 88% of the variation was explained (P < .001). In conclusion, (1) hyperinsulinemia does not enhance skeletal muscle free L-carnitine or acetyl-L-carnitine concentrations in-man, and (2) the acetyl group of acetyl-L-carnitine in human skeletal muscle in vivo is probably mostly derived from glucose and not through beta-oxidation from fatty acids.

Acetyl Coenzyme A↗