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Biomedical subjects

J Maris

Publications and source records attributed to J Maris.

24 records · Page 2Linked to original sources
PubMed1985

Diagnosis and therapeutic evaluation of a pediatric case of cardiomyopathy using phosphorus-31 nuclear magnetic resonance spectroscopy.

An 8 month old girl presented with undiagnosed non-anatomic congenital cardiomyopathy with massive cardiomegaly on chest X-ray film. Her older sibling had died suddenly at 6 months of age from what appeared to be a similar abnormality. Utilizing phosphorus-31 nuclear magnetic resonance (P-31 NMR) surface coil spectroscopy, a metabolic disorder was demonstrated in both her myocardium and skeletal muscle, revealing a phosphocreatine (PCr) to inorganic phosphate (Pi) ratio of half of that for a normal control infant. Manipulation of serum substrate availability indicated that medium chain triglycerides alone did not improve myocardial metabolism, but that intravenous glucose or oral carbohydrate loading raised the myocardial PCr/Pi ratio from 1.0 +/- 0.05 to 1.8 +/- 0.1 (p less than 0.01) without significantly affecting the PCr/Pi value of her resting skeletal muscle. This study demonstrates the feasibility of using P-31 nuclear magnetic resonance to evaluate the biochemistry of the human myocardium in vivo and to diagnose a metabolic abnormality. Phosphorus-31 nuclear magnetic resonance can thus be used to optimize therapy for human disease.

Cardiomegaly↗
PubMed1985

Control of oxidative metabolism and oxygen delivery in human skeletal muscle: a steady-state analysis of the work/energy cost transfer function.

The concept of transfer function for organ performance (work output vs. biochemical input) is developed for skeletal and cardiac muscle under steady-state exercise conditions. For metabolic control by the ADP concentration, the transfer function approximates a Michaelis-Menten hyperbola. Variation of the work identifies metabolic operating points on the transfer function corresponding to ADP concentrations or to a ratio of inorganic phosphate to phosphocreatine that can be determined by phosphorus nuclear magnetic resonance. This operating point is characterized by the fraction (V/Vmax) of maximal activity of oxidative metabolism in the steady state. This quantity appears to be useful in predicting the degree to which metabolic homeostasis is effective; poorly controlled metabolic states can readily be identified and are used in the diagnosis and therapy of metabolic disease in the organs of neonates and adults.

Adenosine Diphosphate↗
PubMed1985

Evaluation of energy metabolism in skeletal muscle of patients with heart failure with gated phosphorus-31 nuclear magnetic resonance.

Exertional fatigue is a major limiting symptom in patients with heart failure. To investigate the metabolic basis of this fatigue, we used gated nuclear magnetic resonance spectroscopy to compare inorganic phosphate (Pi), phosphocreatine (PCr) and pH levels, and fatigue (1 to 4+) during mild forearm exercise in eight normal men and nine men with heart failure. Wrist flexion every 5 sec for 7 min was performed at 1, 2, and 3 J (average power output = 0.2, 0.4, and 0.6 W). In both groups linear relationships were noted between power output and Pi/PCr; the slope of this relationship was used to compare PCr depletion patterns. At rest both groups had similar Pi/PCr ratios (normal subjects 0.12 +/- 0.06, those with heart failure 0.15 +/- 0.03) and pH (normal subjects 7.04 +/- 0.13, those with heart failure 7.10 +/- 0.11). In normal subjects exercise resulted in a progressive increase in Pi/PCr (slope = 1.17 +/- 0.20 Pi/PCr units/W), a reduction in pH only at 0.6 W (0.2 W: 7.03 +/- 0.10, 0.4 W: 7.01 +/- 0.10, 0.6 W: 6.88 +/- 16) and moderate fatigue (0.2 W: 0 +/- 0, 0.4 W: 1.3 +/- 0.5, 0.6 W: 1.9 +/- 0.6). In patients with heart failure exercise resulted in significantly greater fatigue at all workloads (0.2 W: 1.0 +/- 0.5, 0.4 W: 1.9 +/- 0.6, 0.6 W: 2.9 +/- 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗