Showing papers by "Hospital Universitario La Paz published in 1994"

Calculated versus measured oxygen consumption during aortic surgery: reliability of the Fick method.

Abstract: Oxygen consumption (VO2) can be obtained by the Fick method as the product of cardiac index (CI) by the arteriovenous oxygen content difference (D[a-v]O2) or by indirect calorimetry (IC) based on gas exchange measurements. IC is considered the "gold standard" but is not widely available in clinical practice. Our objective was to test the reliability of the reversed Fick method compared with IC under conditions of hemodynamic changes. For this purpose we chose aortic clamping and unclamping as a model. Twelve patients undergoing abdominal aortic surgery were monitored with a fiberoptic pulmonary artery catheter (Opticath). Calculated oxygen consumption (cVO2) was obtained from hemodynamic and analytic data according to the Fick method at six stages: postinduction, before cross-clamping (Pre-C), postclamping (Post-C), before unclamping (Pre-U), after unclamping (Post-U), and the end of surgery. cVO2 was compared with measured oxygen consumption (mVO2) obtained by IC. CI and mixed venous oxygen saturation (SVO2) varied significantly (P < 0.0001) during the interventions. Although mVO2 did not vary, cVO2 varied significantly (P = 0.0001), reaching a maximum at Post-U coinciding with a sudden decrease in SVO2. There was good concordance between mVO2 and cVO2 except at Post-U (P = 0.005). We conclude that cVO2 is a reliable indicator of VO2 in this hemodynamic model except at Post-U. This lack of correlation seems to be due to a mathematical artifact, because the low value of SVO2 registered at this stage and introduced into the Fick formula reflects a sudden venous return of desaturated blood and not an increase in VO2.

Determination of the Activity of Recombinant Human Phosphoribosylpyrophosphate Synthetase Isoform 1 by a Non-Isotopic, One-Step Method

Abstract: Phosphoribosylpyrophosphate synthetase (Ribophosphate pyrophosphokinase, EC 2.7.6.1., PRS) catalyses the synthesis of phosphoribosylpyrophosphate (PRPP) from ribose 5-phosphate and MgATP in the reaction: Open image in new window

Complex I and IV deficits in the mitochondrial respiratory chain in two siblings with type I glutaric aciduria

Abstract: We report two brothers with a glutaric aciduria type I (GA-I) identified by Glutaryl-coenzyme A dehydrogenase deficiency in skin fibroblasts. The onset of neurologic abnormalities was at 6 and 9 months of age as an acute Reye-like presentation in one. Because of the hyperlactacidemia, hyperlactatorrachia, mitochondrial abnormalities in muscular cells and a deficiency in complex I and IV of the respiratory chain in isolated mitochondria from muscle, a presumptive diagnosis of Leigh syndrome was made. We analyze the difference between both disorders. GA-I should be suspected in patients with acute dystonia and psychomotor regression, lactic acidosis and hypodensity of the basal ganglia.

Abordajes clinico y paraclinico de las enfermedades mitocondriales. estudio de 15 casos

Abstract: 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 myocardic and hepatic tissues of another. Site of biochemical defect was located in 12 patients. Complex 1 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 clinical 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.