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Biomedical subjects

M Pineda

Publications and source records attributed to M Pineda.

At least 73 records · Page 4Linked to original sources

Glutaric aciduria type I with high residual glutaryl-CoA dehydrogenase activity.

Two brothers with dystonia and slight MRI changes in the basal ganglia had normal urinary glutaric acid excretion, but slightly increased 3-hydroxyglutarate and conjugated glutarate excretions. Both siblings have high residual glutaryl-CoA dehydrogenase activity, and are compound heterozygotes for two mutations - R227P and V400M reported to be disease-causing in patients with glutaric aciduria type I.

Amino Acid Metabolism, Inborn Errors↗

Multiple endocrine involvement in two pediatric patients with Kearns-Sayre syndrome.

We present 2 cases of progressively severe Kearns-Sayre syndrome (KSS) with multisystemic affectation and atypical endocrine and cutaneous features, a 16-year-old patient (case 1) and a 5-year-old patient (case 2). Endocrine studies showed high glucose and glycohemoglobin concentrations with normal pancreatic reserve and low values of ACTH, cortisol, LH and FSH in case 1. Normal ACTH values with low concentrations of cortisol and PTH were observed in case 2. Southern blot analysis and PCR amplification revealed the presence of a deletion of approximately 6.7 kb in the mitochondrial DNA of both patients. Endocrinological studies suggest that adrenal insufficiency may be an additional feature of KSS that worsens the clinical evolution of the patients. In spite of a normal pancreatic reserve, insulin therapy should be considered in patients with diabetes mellitus of mitochondrial origin.

Adolescent↗

[Respiratory chain and pyruvate metabolism deficiencies in pediatric patients: evaluation of biochemical tests for selective screening].

INTRODUCTION: The correct selection of pediatric patients with clinical suspicion of mitochondrial diseases is the first step to achieve a definitive diagnosis. MATERIAL AND METHODS: The results of the initial biochemical tests obtained in 35 children diagnosed of respiratory chain or pyruvate metabolism defects were reviewed. The efficiency of basal determinations (lactate, pyruvate, ketone bodies, amino and organic acids and carnitine), cerebrospinal fluid (CSF) analysis, and dynamic tests (exercise, glucose loading and glucose oxidation by lymphocytes) was discussed. RESULTS: Plasma lactate and alanine, and CSF metabolites were the most informative measurements in basal status. Urine organic acids were very useful to confirm the initial suspicion. Glucose loading was the most informative and reliable challenge test for pediatric population, while exercise test was especially useful for older children with fatigability or peripheral nervous system involvement. CONCLUSIONS: Glucose oxidation by lymphocytes might be applied when the other dynamic tests can not be performed or are not informative.

Alanine↗

[Neurocutaneous melanosis].

INTRODUCTION: Neurocutaneous melanosis is an infrequent condition characterized by the presence of numerous gigantic cutaneous naevi and melanocytic infiltration of the central nervous system and/or the leptomeningeal layers. Different clinical features may be seen: endocranial hypertension due to hydrocephalus, cranial nerve paralysis, myelopathy, convulsive seizures, etc. The prognosis is considered to be malignant. Only positive CNS histological findings confirm the diagnosis. CLINICAL CASE: We present the case of a man with cutaneous lesions compatible with the diagnosis of neurocutaneous melanosis since birth, with benign self-limiting epilepsy in early childhood. Cerebral CT and MR scans were normal until the age of 17, when hipper-signal lesions appeared on MR, infiltrating the leptomeninges of the deep temporal pole and anterior aspect of the cerebral peduncles, which suggested the presence of melanocytes in the CNS. CONCLUSIONS: There are cases of neurocutaneous melanosis with a good medium-term prognosis and benign manifestations until infiltration of the CNS occurs. Then they start to show the classical behavior of cases with a malignant prognosis. MR should be included as part of the diagnostic criteria for neurocutaneous melanosis. MR should be done periodically in patients with cutaneous lesions suggestive of this condition.

Brain Diseases↗

Tocopherol in inborn errors of intermediary metabolism.

Red blood cell tocopherol was measured in a group of 92 children with inborn errors of intermediary metabolism to evaluate the peroxidative damage in different mitochondrial and cytosolic defects, and to consider the need for treatment or vitamin supplementation. Tocopherol was determined by HPLC with UV detection. Results were expressed in nanomoles red blood cell tocopherol per gram protein. Significant differences (Mann-Whitney; P < 0.001) were found between tocopherol levels in untreated patients: 19 with mitochondrial defects versus 23 with cytosolic enzyme or transport defects, and versus 58 age-matched reference values. In conclusion, mitochondrial enzyme deficiencies, either amino and organic acidurias or defects of energy metabolism, seem to produce an excess of free radicals with the consequent utilization of tocopherol as antioxidant. This is not apparent in the cytosolic enzyme defects studied, whose tocopherol levels are in the normal range. Treatment with tocopherol completely corrects the deficient antioxidant status.

Adolescent↗

High transdominant RevM10 protein levels are required to inhibit HIV-1 replication in cell lines and primary T cells: implication for gene therapy of AIDS.

Expression of antiviral genes in CD4+ T cells has been proposed as a strategy for gene therapy of AIDS. Over the past years, we and others have developed retroviral vectors encoding the RevM10 protein, a dominant-negative mutant of the HIV-1 Rev trans-activator protein. We could demonstrate gene transfer and inhibition of HIV-1 replication in cultured T cell lines and primary T cells. However, little is known about the levels of the antiviral protein required to achieve a therapeutic effect, particularly in primary cells. In this report, we compare different vector designs with regard to expression of the antiviral gene to develop an optimal vector for clinical applications. Our results demonstrate that intracellular steady-state RevM10 protein levels expressed from the Moloney murine leukemia virus (MoMLV), myeloproliferative sarcoma virus (MPSV) or mouse embryonic stem cell virus (MESV) promoters located in the long terminal repeat (LTR) were uniformly higher than from internal promoters (eg CMV, PGK). Analysis of selected vectors in acutely and chronically HIV-infected cell lines suggested that threshold levels of RevM10 expression are required to achieve inhibition of HIV replication. LTR-driven RevM10 expression also yielded high steady-state protein levels in activated primary T cells resulting in inhibition of HIV replication, and there was no apparent difference between the MoMLV, MPSV and MESV-LTR vectors. However, RevM10 expression was down-regulated in resting primary cells and consequently anti-HIV efficacy was significantly reduced. Taken together, the data suggest that relatively high steady-state levels of RevM10 protein are required to achieve inhibition of HIV replication and that the MPSV- and MESV-derived retroviral vectors show no advantage over the MoMLV-based vectors for expression of anti-HIV genes in human T cells.

CD4-Positive T-Lymphocytes↗

[Fragile X syndrome and mental retardation].

INTRODUCTION: Fragile-X syndrome is characterized by the presence of a fragile site (gap) on Xq 27.3 and the transcriptional inhibition of a mRNA protein-binding gene called FMR-1. Neuropsychological features include cognitive impairment, attention deficit disorder with and without hyperactivity, and impairment of visuospatial functions, language and frontal executive functions. In the present paper, other cytogenetic and phenotype characteristics, associate disorders, neurological and neuroimaging studies are revised. CLINICAL CASES: We describe two siblings that illustrate the pattern of neurocognitive and behavioural trends of the Fragile X syndrome, and sex differences. DISCUSSION AND CONCLUSIONS: These two cases emphasize the need for performing a cytogenetic diagnostic in patients with mental retardation, of unknown etiology, and with a familiar history of mental retardation.

Adult↗

Homozygosity mapping of Hallervorden-Spatz syndrome to chromosome 20p12.3-p13.

Hallervorden-Spatz syndrome (HSS) (OMIM #234200) is a rare, autosomal recessive neurode-generative disorder with brain iron accumulation as a prominent finding. Clinical features include extrapyramidal dysfunction, onset in childhood, and a relentlessly progressive course. Histologic study reveals massive iron deposits in the basal ganglia. Systemic and cerebrospinal fluid iron levels are normal, as are plasma levels of ferritin, transferrin and ceruloplasmin. Conversely, in disorders of systemic iron overload, such as haemochromatosis, brain iron is not increased, which suggests that fundamental differences exist between brain and systemic iron metabolism and transport. In normal brain, non-haem iron accumulates regionally and is highest in basal ganglia. Pathologic brain iron accumulation is seen in common disorders, including Parkinson's disease, Alzheimer's disease and Huntington disease. In order to gain insight into normal and abnormal brain iron transport, metabolism and function, our approach was to map the gene for HSS. A primary genome scan was performed using samples from a large, consanguineous family (HS1) (see Fig. 1). While this family was immensely powerful for mapping, the region demonstrating homozygosity in all affected members spans only 4 cM, requiring very close markers in order to detect linkage. The HSS gene maps to an interval flanked by D20S906 and D20S116 on chromosome 20p12.3-p13. Linkage was confirmed in nine additional families of diverse ethnic backgrounds.

Chromosome Mapping↗

Purification and characterization of tomatinase from Fusarium oxysporum f. sp. lycopersici.

The antifungal compound alpha-tomatine, present in tomato plants, has been reported to provide a preformed chemical barrier against phytopathogenic fungi. Fusarium oxysporum f. sp. lycopersici, a tomato pathogen, produces an extracellular enzyme inducible by alpha-tomatine. This enzyme, known as tomatinase, catalyzes the hydrolysis of alpha-tomatine into its nonfungitoxic forms, tomatidine and beta-lycotetraose. The maximal tomatinase activity in the fungal culture medium was observed after 48 h of incubation of germinated conidia at an alpha-tomatine concentration of 20 micrograms/ml. The enzymatic activity in the supernatant was concentrated against polyethylene glycol 35,000, and the enzyme was then purified to electrophoretic homogeneity by a procedure that includes preparative isoelectric focusing and preparative gel electrophoresis as main steps. The purification procedure had a yield of 18%, and the protein was purified about 40-fold. Tomatinase was found to be a monomer of 50 kDa by both native gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The analytical isoelectric focusing of the native tomatinase showed at least five isoforms with pIs ranging from 4.8 to 5.8. Treatment with N-glycosidase F gave a single protein band of 45 kDa, indicating that the 50-kDa protein was N glycosylated. Tomatinase activity was optimum at 45 to 50 degrees C and at pH 5.5 to 7. The enzyme was stable at acidic pH and temperatures below 50 degrees C. The enzyme had no apparent requirement for cofactors, although Co2+ and Mn2+ produced a slight stimulating effect on tomatinase activity. Kinetic experiments at 30 degrees C gave a K(m) of 1.1 mM for alpha-tomatine and a Vmax of 118 mumol/min/mg. An activation energy of 88 kJ/mol was calculated.

Enzymes↗

Nosocomial transmission of Mycobacterium tuberculosis: role of health care workers in outbreak propagation.

To investigate an outbreak of tuberculosis (TB) among health care workers (HCWs) at a county hospital, all patients with culture-confirmed TB on wards A and B and all HCWs working at least one shift on these wards from January 1991 through March 1992 were studied. Tuberculin skin test conversions occurred in 30% (ward A) and 48% (ward B) of HCWs; 8 developed active TB. Workers exposed for at least one shift to workers or patients with active TB were more likely to have skin test conversion than were workers who were not exposed (ward A exposure relative risk [RR] for workers = 2.8, P = .005, and for patients = 2.2, P > .5; ward B exposure RR for workers = 2.8, P < .001, and for patients = 5.3, P < .001). Underlying conditions and performing charting activities in the nurses' work room were associated with progression to active TB among infected workers. Transmission was facilitated by delays of < or = 2.5 months in treatment of workers with skin test conversion or TB symptoms.

Cross Infection↗

Increased VLDL levels and diminished renal excretion of uric acid in hyperuricaemic-hypertriglyceridaemic patients.

The objective was to study the lipoprotein levels in primary hyperuricaemic patients and to analyse their renal management or urates in order to check for some potential influence of altered lipid levels on the renal excretion of urates by this type of patient. Overall 115 male individuals were studied in five groups, namely: 30 primary hyperuricaemic (group I); 27 primary hyperuricaemic-hypercholesterolaemic (group II); nine primary hyperuricaemic-hypertriglyceridaemic (group III); 33 primary hyperuricaemic-mixed hyperlipidaemic (group IV); and 16 normouricaemic-normolipidaemic subjects (group C). All patients were subjected to blood analyses for uric acid, total triglycerides, total protein, creatinine, high density lipoprotein (HDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, low density lipoprotein (LDL) cholesterol, apoprotein (apo) AI, apoprotein B, apoprotein CII and apoproteins CIII1 and CIII2. For urine analysis creatinine, creatinine clearance, uric acid excretion, clearance and fractional excretion were measured in 24 h urine samples. Mixed and pure hyperuricaemic-hypertriglyceridaemic patients exhibited increased levels of VLDL components, decreased fractional excretion of uric acid and increased apo CIII/CII ratios. The increased levels of structural VLDL components were negatively (and statistically significantly) correlated with the fractional excretion of uric acid; this suggests a close biological relationship between the two parameters. Taking into account the role played by apo C in VLDL metabolism, the altered apo CIII/CII ratios found in hyperuricaemic-hypertriglyceridaemic patients (both pure and mixed) suggest that this apoprotein plays a central role in the physiopathology of the alterations observed.

Adult↗

Vitamin D dependent rickets type II and normal vitamin D receptor cDNA sequence. A cluster in a rural area of Cauca, Colombia, with more than 200 affected children.

Vitamin D dependent rickets type II is an autosomal recessive disease caused by the vitamin D defective receptor. More than 200 patients with different types of lower limb deformities were detected in a rural area of the Cauca department in the southwest part of Colombia. Patients were well nourished and in good physical condition in spite of their deformities. None of them presented alopecia, myopathy, seizures or aminoaciduria. Serum analysis showed significantly lower serum calcium as compared to normal relatives, though in the normal low range, normal phosphorus, high alkaline phosphatase, normal 25-hydroxyvitamin D3 and high 1,25-dihydroxyvitamin D3, indicating target organ resistance. The cDNA analysis showed normal nucleotide sequence. We suggest that our patients represent a distinct form of receptor-positive resistance to vitamin D. This report is the first extensive study on this class of patients.

Adult↗

A continuous spectrophotometric assay for ureidoglycolase activity with lactate dehydrogenase or glyoxylate reductase as coupling enzyme.

A spectrophotometric assay for ureidoglycolase activity (both ureidoglycolate lyase and hydrolase), based on the reduction of glyoxylate to glycolate catalyzed by glyoxylate reductase or lactate dehydrogenase with the stoichiometric and continuous NADH oxidation, is described. The assay has been optimized for the amount of coupling enzyme, reagent concentrations, buffers, and the nonenzymatic degradation of ureidoglycolate. Under optimal assay conditions, ureidoglycolase activity can be followed with either lactate dehydrogenase or glyoxylate reductase as coupling enzyme and reaction can be started by addition of substrate or enzyme extract. Once the reaction was started, NADH oxidation was linear with time after a lag phase of 1-2 min. This linear NADH oxidation was directly proportional to enzyme concentration in the assay mixture until changes in absorbance of 0.12 per minute. This method is easy and reliable for the accurate determination of ureidoglycolase activity in crude and purified extracts from Chlamydomonas reinhardtii cells and no notable interferences have been detected. Since lactate dehydrogenase is much cheaper and has a lower Km for its substrate than glyoxylate reductase and can be used as supplied, its use as the coupling enzyme of choice is recommended.

Alcohol Oxidoreductases↗