Biomedical subjects

A L Andreu

Publications and source records attributed to A L Andreu.

70 records · Page 4Linked to original sources

PubMed1998

Familial multiple symmetric lipomatosis associated with the A8344G mutation of mitochondrial DNA.

We describe familial multiple symmetric lipomatosis in a pedigree harboring the 8344 mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA). The proband showed neuromuscular involvement but lacked the typical manifestations of myoclonic epilepsy and ragged-red fibers disease. The distribution of the mutation was unusual because the proportion of mutated genomes was higher in blood and lipomas than in muscle tissue.

Adult↗

PubMed1998

Molecular genetic analysis of McArdle's disease in Spanish patients.

We analyzed leukocyte DNA of 19 patients from 12 Spanish families with McArdle's disease (myophosphorylase deficiency). In 15 patients, the enzyme defect was documented histochemically in muscle, and in four the diagnosis was based on clinical and laboratory data. Three patients were homozygous and six were heterozygous for the nonsense mutation at codon 49 (R49X). Our findings indicate that the R49X mutation, which is common in English and American patients, is also present in Spanish patients with McArdle's disease, but at a lower frequency.

Adult↗

PubMed1998

Missense mutation in the mtDNA cytochrome b gene in a patient with myopathy.

A patient with progressive exercise intolerance, proximal weakness, and complex III deficiency in skeletal muscle had a missense mutation in the cytochrome b gene of mitochondrial DNA (G15762A). The mutation, which leads to the substitution of a highly conserved amino acid (G339E), was heteroplasmic (85%) in the patient's muscle and was not present in 100 individuals of different ethnic backgrounds. These data strongly suggest that this molecular defect is the primary cause of the myopathy.

Adult↗

PubMed1998

Effect of starvation on organ blood flow in the senescent rat.

To investigate the amino acid requirements of the senescent rat, as part of a study directed toward nutritional support in the aged, it was necessary to determine amino acid levels in plasma and tissue, but also regional blood flow of the animals subjected to fast. Only this latter allows the determination of the amounts of each amino acid present in the tissue before starvation by extrapolation of values measured during starvation. As plasma and tissue amino acid had been previously determined, the aim of this study had been to measure regional blood flow in the liver, kidney, testis, spleen, stomach, small intestine and large intestine in senescent rats submitted to 1, 5, 9 and 15 days of starvation. Twenty-four-month-old male Wistar rats (n = 16) were divided into four groups (n = 4), and submitted to starvation for 1, 5, 9 and 15 days. Blood flow in the liver, kidney, testis, spleen, stomach, and small and large intestine was measured by injecting 0.5 ml of a microsphere solution (15 microns diameter) labelled with 57Co, 0.25 microCi/ml. Over the 15-day period studied, the response to starvation showed two distinct phases: an early effect (from day 1 to day 9) in which there were decreases in the weight of the organs and in organ blood flow, and a second phase (from day 9 to day 15) in which blood flow and organ weight were maintained. However, organ blood flow related to mass was not substantially affected by starvation. This implies that measurement of substrate plasma concentration alone can reliably reflect organ substrate flow.

Aging↗

PubMed1997

Modification of organ protein synthesis after surgical stress by low energy diets with different supplements.

We have studied the effects of hypocaloric diets with different supplements on liver and jejunal mucosa protein synthesis. The supplements assayed were medium chain triglycerides (diet MCT, with 50% carbohydrates: 25% long chain triglycerides (LCT): 25% medium chain triglycerides (MCT), standard amino acids), branched-chain amino acids (diet BCA, identical to control diet L50, with 15.3% of nitrogen replaced by branched-chain amino acids) and glutamine (diet GLN, identical to diet L50, with 15.3% of nitrogen replaced by glutamine). The control diet (L50) had 50% carbohydrates: 50% LCT and standard amino acids. The diets were assayed on 86 rats with femoral fracture immobilized by Kirschner pin insertion. Nutrition was administered for 4 days. On the fifth day, liver and jejunal mucosa protein synthesis was determined. A branched-chain amino acid supply in a proportion higher than 21.2% of amino acid nitrogen significantly decreased liver and jejunal mucosa protein synthesis, while the same amount of glutamine did not modify it. MCT had no effect on jejunal mucosa protein synthesis, while it was decreased significantly in the liver.

Amino Acids, Branched-Chain↗

PubMed1997

Modification of organ protein synthesis after surgical stress by low energy diets with different lipid/glucose ratios.

The aim of this work was to study the effects of low energy parenteral diets with different lipid/glucose ratios on rat liver and jejunal mucosa protein synthesis. The studied diets were: L0 (100% glucose, control diet), L25 (25% lipids: 75% glucose), L50 (50% lipids: 50% glucose) and L75 (75% lipids: 25 % glucose). All diets were isoenergetic and isonitrogenated, with a standard amino acid content. The diets were assayed in 93 rats with open femoral fracture immobilized by Kirschner pin insertion. The diets were administered for 4 days. On the fifth day, liver and jejunal mucosa protein synthesis were determined. Highest liver protein synthesis rates were obtained with the diet compositions: lipid/carbohydrate ratio: 25% lipids and 75% carbohydrates (expressed as energy ratio). A higher proportion of lipids significantly decreases liver protein synthesis (p <0.05). Jejunal mucosa protein synthesis followed the same pattern, with the same statistical differences.

Animals↗

PubMed1995

Addition of glutamine does not improve protein synthesis and jejunal mucosa morphology in non-hypercatabolic stress.

To investigate the effect of glutamine-enriched total parenteral nutrition (TPN) on the protein synthesis and morphology of jejunal mucosa in non-hypercatabolic stress, sixty-two male Sprague-Dawley rats were subjected to surgical stress by femoral fracture. The rats were divided into 3 groups and received TPN for 8 days. One group received a standard amino acid solution without glutamine, the second group a standard solution enriched with glycine and glutamic acid, and the third group a standard solution enriched with glycyl-glutamine. All regimens were isocaloric and isonitrogenous-nitrogen (2.2 g/kg.day), glucose (150 Kcal/kg.day), and lipids (150 Kcal/kg.day). There were no statistically significant differences in jejunal mucosal thickness, DNA content, protein content, fractional synthesis rate or absolute protein synthesis among the groups after eight days of parenteral nutrition. In conclusion, the addition of glutamine to TPN did not influence either protein metabolism or morphology of the jejunal mucosa in non-hypercatabolic surgical stress.

Animals↗

PubMed1994

Effect of medium chain triglycerides (MCT) on jejunal mucosa mass and protein synthesis.

The effects of medium chain triglycerides (MCT) on jejunal mucosa mass and protein synthesis were compared with results from previous experiments with rats fed by parenteral nutrition or enteral nutrition. Other published studies have also been analysed. Three experimental models were studied. In the traumatic model, production of a femoral fracture was followed by Kirschner pin insertion into the medullary canal of both fragments at reduction. (Forty ras were fed enteral nutrition and 93 were given parenteral nutrition.) A second model entailed resection under ether anaesthesia using the technique described by Higgins. (Fifty five rats were fed enteral nutrition and 28 with parenteral nutrition.) A third model entailed a terminolateral portocaval shunt under anaesthesia with pentobarbital. (Sixty nine rats were treated this way and then given enteral nutrition.) Proportions of medium chain/long chain triglycerides (LCT) were as follows: 0/100, 20/80, 40/60, 50/50, and 92/8 for enteral nutrition and 0/100, 30/70, 50/50, and 70/30 for parenteral nutrition. Faecal losses of alpha amino nitrogen, protein, total fats, and free fatty acids were analysed together with the quantitative intake, weight gain of the rats, jejunal mucosal mass, and protein synthesis in relation to the MCT proportion ingested or given by enteral nutrition or parenteral nutrition. From analysis of our results and those of others, several conclusions could be drawn. Firstly, the route of administration of MCT is extremely important and enterocytes might be considered one of the main target sites. Secondly, a high proportion of MCT (more than 80%) offers no advantage for jejunal mucosa and produces undesirable side effects. Thirdly, the effect of MCT on jejunal mucosal protein synthesis depends on the metabolic state. Finally, an increase in jejunal mucosal mass directly correlated with MCT concentrations, but no correlation was found between mass and protein synthesis. A positive correlation, however, between MCT proportion and enzyme activity (alkaline phosphatase and sucrase) in the brush border membrane was seen as well as a positive correlation with the concentration of phospholipids in the microvilli.

Animals↗

PubMed1993

[Anthropometric reference parameters for the aged population].

BACKGROUND: Anthropometry is an effective method used in the evaluation of the state of nutrition. Anthropometric reference values obtained from the general population have frequently been used. The aim of this study was to determine the anthropometric parameters of the elderly in Manresa and demonstrate the different evolution of these values in both sexes between the ages of 65 and 85 or more. METHODS: Following randomization a representative sample of 1,034 healthy elderly subjects living in Manresa was obtained with the following being determined: weight, height, tricipital, subscapular and abdominal fat folds, arm circumference, arm muscle perimeter, weight/height indexes, muscle and fat areas of the arm and percentage of fat. All the measurements were obtained by the same person with the use of a tallimeter scale with a flexible metric tape and a Holtain lipocalibrater. RESULTS: The values are presented in percentiles by subgroups of age and sex. The weight, height and indexes of lean mass were greater in males while those determining fatty mass were greater in females. In females all the values decreased between 65 and 85 or more years of age (p < 0.001), while in males all decreased (p < 0.001) except; tricipital and abdominal skin folds. Upon comparison of these parameters with those obtained in other geographic areas, differences were observed between both. CONCLUSIONS: By the characteristics of the population studied it was considered that the anthropometric parameters obtained are extensible to all the elderly population of Catalonia and may be used as reference values of the same.

Aged↗

PubMed1993

Ketoisocaproate contamination errors in protein synthesis determinations using L[1-14C]leucine.

Protein synthesis rate determinations in vivo using L-[1-14C]-leucine may be underestimated because of contamination by radioactive ketoisocaproate (KIC) resulting from leucine metabolism. The aim of this work was to set up a reliable method to determine the KIC/leucine radioactivity ratio in protein-free homogenates, and to apply it to study the extent of the protein synthesis ratio error due to KIC contamination. Cation-exchange chromatography using Dowex AG 50W-X8 resin was used to separate KIC from leucine, eluting KIC with water and leucine with 4 M ammonia. The errors found in the protein synthesis ratio were 6.20% in liver and 2.34% in jejunum.

Animals↗

PubMed1993

Inhibition of visceral protein synthesis by certain amino acid supplements.

This study was focused on the effects produced by diets with different amino acid proportions on visceral protein synthesis (liver and jejunal mucosa). Eight groups of rats received an enteral modular diet supplemented with different amino acids (Group 1: Ile, Leu, Val; Group 2: Phe, Met, Gly; Group 3: Glu, Arg, Gly; Group 4: Gly, Group 5: Orn-Asp, Cys, Pro; Group 6: Lys, Ser, Thr; Group 7: Tyr, His, Ala). Group 8 was the control group. Rats were fed for four days. At the end of this period a flooding dose of 14C-Leu was injected and animals were killed. Liver and jejunal mucosa were removed and protein synthesis rate was determined. Results show a decreased liver protein synthesis in group fed with aromatic amino acids (53.8 +/- 8.4 vs. 88.6 +/- 12.1) and Glu-Arg (68.6 +/- 10.9). In jejunal mucosa there was a decrease of protein synthesis in groups fed with aromatic amino acids (98.7 +/- 16 vs 160.5 +/- 49). These changes seem to be related to the intracellular amino acid pool size and its influence on protein metabolism.

Amino Acids↗

PubMedDate not supplied

[Mitochondrial encephalopathies: where are we going?].

In few areas of medicine has progress been more spectacular than in the field of mitochondrial diseases, especially those related to mtDNA mutations. Much remains to be done, however, and this brief review discusses the following areas of research where progress has been more limited or data are still controversial: 1. The pathophysiology of mtDNA related disorders; 2. The molecular base of nDNA mutations; 3. The coenzyme Q10 deficiency; 4. Defects of translocases; 5. Defects of mitochondrial protein importation, and 6. Defects of intergemonic signalling.

DNA, Mitochondrial↗

PubMedDate not supplied

[Leigh syndrome resulting from a de novo mitochondrial DNA mutation (T8993G)].

INTRODUCTION: Several degenerative neurological diseases are caused by mutations in the mitochondrial gene coding for subunit 6 of the ATPase. Thus, NARP (neurogenic weakness, ataxia, and retinitis pigmentosa) and Leigh syndromes are associated to a T8993G mutation when the percentage of mutant mitochondrial DNA is low (60 90%) or high (>90%), respectively. Leigh syndrome is also caused by a second mutation in the same position T8993C. CASE REPORT: The patient, a boy that died at 6 months, had generalized hypotonia, psychomotor delay, hepatomegaly, choreic movements and hyporreflexia. MRI showed hypodensities in the basal ganglia and brain stem as well as hyperlactacidemia. Molecular genetic analysis of the mitochondrial DNA showed that the patient had the T8993G mutation in a percentage higher than 95%. No mutated DNA was detected in blood of the proband s mother, maternal aunt and grandmother. CONCLUSIONS: The point mutation T8993G may occur de novo, at high levels, causing neurodegenerative diseases.

DNA, Mitochondrial↗

PubMedDate not supplied

[Mitochondrial disorders: a classification for the 21st century].

Mitochondrial encephalomyopathies were described in the 60's when accumulation of mitochondria were observed in patients with exercise intolerance. The electronic transport chain is located in the mitochondria and forms the oxidative phosphorylation (OXPHOS) system that produces ATP in the cell. The electronic transport chain is coded by two different genomes, nuclear and mitochondrial, with different genetic characteristics. The main differences between nuclear and mitochondrial genetics are heteroplasmy and threshold effect, mitotic segregation and maternal inheritance. Mitochondrial diseases are due to defects in the genes encoding proteins involved in some mitochondrial pathways. Those genes may be ARNts, structural proteins of the electronic transport chain or associated proteins of the mitochondria (transporters or assembly proteins). Alterations in those genes may be point mutations, deletions or duplications in the mitochondrial DNA and alterations of the genomic signaling between nucleus and mitochondria.

Cell Nucleus↗

PubMedDate not supplied

Thiolprotease activity in skeletal and myocardial muscle and liver of fasted rats.

The activity of the thiolproteases, cathepsins B, H, and B + L, one of the most important groups of endoproteases, was measured in skeletal and myocardial muscle and liver of Sprague-Dawley rats submitted to fasts of different duration (control and 24, 48, and 72 h). After the fasting period, the animals were killed, and fresh tissue samples were collected. Enzyme activity was determined in vitro with the specific substrates Z-Arg-Arg-MCA for cathepsin B, Z-Phe-Arg-MCA for cathepsin B + L, and Arg-MCA for cathepsin H. Results show different patterns in the organs studied: activity increased linearly in liver, decreased in myocardial muscle, and had no change in skeletal muscle. These results suggest that the expected alteration observed in proteolytic activity in fasted tissues is produced to a certain degree by changes in thiolprotease activity.

Animals↗

PubMedDate not supplied

Nutrition, lysosomal proteases, and protein breakdown.

We review the role played by the lysosomal proteases on cellular protein breakdown and their relation to nutrition research. Several recent works have shown that an important group of lysosomal proteases (cathepsins) are directly responsible for the maintenance of protein breakdown. The determination of their enzyme activity or measurement of mRNAs as an index of gene expression have provided new views about the mechanisms of protein-breakdown regulation. The introduction of molecular biology could provide new ways with which to manipulate the catabolic response of injured patients.

Animal Nutritional Physiological Phenomena↗