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Biomedical subjects

H Reichmann

Publications and source records attributed to H Reichmann.

At least 181 records · Page 10Linked to original sources
PubMed1990

Normal mitochondrial genome in brain from patients with Parkinson's disease and complex I defect.

The mitochondrial genome codes for 13 proteins which are located in the respiratory chain. In postmortem brain of patients with Parkinson's disease, decreased activity of complex I of the respiratory chain could be demonstrated. Because seven subunits of complex I are coded by the mitochondrial genome, we analyzed the mitochondrial DNA of human postmortem substantia nigra, putamen, and frontal cortex by the Southern blot technique. No deletions of the mitochondrial genome could be demonstrated, thus indicating that either subunits which are encoded by the nuclear genome are decreased or enzyme activity is diminished by metabolites, toxins, or increase of Fe3+.

Aged↗
PubMed1990

On the stability of key enzymes of energy metabolism in muscle biopsies.

Enzymes of energy metabolism were tested for stability depending on different storage conditions (-20, -80 degrees C). To avoid problems due to the different fiber type composition of human muscle, we selected two muscles from rabbit. The m. psoas consists almost exclusively of type 2B fibers, and the m. soleus consists almost exclusively of type 1 fibers. Enzyme activities were measured from small aliquots of these muscles at various time points up to 1 year after sacrificing the animal. Enzymes from anaerobic metabolism were stable for more than 1 year, independent of whether the muscle was stored at -20 or -80 degrees C. Oxidative enzymes, such as succinate dehydrogenase, citrate synthetase, or cytochrome c oxidase (COX) decrease in activity at -20 degrees C and, to a lesser degree, at -80 degrees C. In addition, mitochondria were isolated from freshly taken muscle and stored at -80 degrees C. Oxidative enzymes were surprisingly stable for more than 1 year, with the exception of COX which decreased by 60% of its original activity in mitochondria from m. soleus.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

A spectrophotometric method for the determination of free and esterified carnitine.

We have developed a spectrophotometric assay to measure carnitine in any tissue. The test is based on the transformation of carnitine to acetyl-carnitine catalyzed by carnitine acetyltransferase. The second reaction product, reduced Coenzyme A, is converted to succinoyl-CoA by adding 2-oxoglutarate. The enzyme which catalyzes this reaction, 2-oxoglutarate dehydrogenase, reduces NAD which is followed spectrophotometrically. Via external standards the carnitine concentration can be determined. In a detailed study we proved the reproducibility, precision and specificity of the assay and its correspondence with the radiochemical test.

Acyl Coenzyme A↗
PubMed1988

Differential response of enzyme activities in rat diaphragm and intercostal muscles to exercise training.

To determine whether respiratory muscles undergo alterations in enzyme activities of energy metabolism as a result of increased mechanical activity, adult male Wistar rats were subjected to a prolonged endurance training program. Analysis off maximal enzyme activity patterns in the diaphragm following 15 weeks of extreme training (final running duration: 210 min per day, 27 m.min-1 at 15 degrees grade, indicated significant reductions in the marker enzymes of the citric acid cycle (citrate synthase), glycolysis (pyruvate kinase, PK; lactate dehydrogenase, LDH), ketone body utilization (3-keto acid: CoA transferase) and transamination (glutamate pyruvate transaminase, GPT). No changes were found for the enzymes of glycogenolysis (phosphorylase, PHOSPH), glycolysis (glyceraldehyde phosphate dehydrogenase, GAPDH), glucose phosphorylation (hexokinase, HK) and beta-oxidation (3-hydroxyacyl: CoA dehydrogenase, HAD) following training. In contrast, in the external intercostal muscle, increases in the range of 57-77% were noted for the enzymes CS and HAD, whereas in the internal intercostal muscles no training induced alteration was evident for these enzymes. For both the intercostal muscles, a consistent trend was noted towards a reduction in all of the glycolytic enzymes investigated, however, significantly lower values were recorded for only PK and LDH in the internal intercostals. GPT was increased in the internal intercostal muscles. These findings indicate that the response pattern observed in the enzyme activities studied following training are to some degree specific to the respiratory muscle investigated.

Animals↗
PubMed1988

Enzymes of fatty acid beta-oxidation in developing brain.

Developmental profiles were determined for the activities of eight enzymes involved in fatty acid beta-oxidation in rat brain. The enzymes studied were the palmitoyl-CoA, octanoyl-CoA, butyryl-CoA, glutaryl-CoA, and 3-hydroxyacyl-CoA dehydrogenases, the enoyl-CoA hydratase (crotonase), and the C4- and C10-thiolases. With the exception of the thiolases, all of the activities (expressed on the basis of brain weight) increased during the postnatal period of brain maturation. The activity of octanoyl-CoA dehydrogenase was elevated markedly compared to that of palmitoyl-CoA dehydrogenase at all developmental stages and in all brain regions in the rat. A similar relationship between these enzymes was observed in various regions of adult human brain. Comparisons of the activities of the beta-oxidation enzymes in human brain versus human skeletal muscle and in cultured neural cell lines (neuroblastoma and glioma) versus cultured skin fibroblasts revealed that the elevated activity of octanoyl-CoA dehydrogenase relative to palmitoyl-CoA dehydrogenase was specific to the neural tissues. This relationship was particularly evident when the enzyme activities were normalized to the activity of crotonase. The data support previous findings with radiochemical tracers, indicating that the brain is capable of utilizing fatty acids as substrates for oxidative energy metabolism. The relatively high activity of the medium-chain fatty acyl-CoA dehydrogenase in neural tissue may represent an adaptive mechanism to protect the brain from the known encephalopathic effects of octanoate and other medium-chain fatty acids that readily cross the blood-brain barrier.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1988

Enzyme activity measured in single muscle fibers in partial cytochrome c oxidase deficiency.

Single-fiber analyses using a kinetic microphotometric method were performed on three patients with chronic progressive external ophthalmoplegia and proximal myopathy accompanied by a partial deficiency of cytochrome c oxidase. Two patients had subsarcolemmal accumulation of mitochondria (ragged-red fibers). Qualitative histochemical demonstration of cytochrome c oxidase showed a mosaic of fibers without detectable cytochrome c oxidase activity. Quantitative single fiber measurements in the patients' biopsies showed that the majority of the muscle fibers had decreased cytochrome c oxidase activity without selective involvement of a specific fiber type. Succinate dehydrogenase was measured and the ratio of the activities (succinate dehydrogenase/cytochrome c oxidase) was calculated. Normal muscle showed a ratio of about 2, whereas diseased muscle showed values between 10 and 20, due to a decrease in cytochrome c oxidase activity. Ragged-red fibers showed very low or undetectable cytochrome c oxidase activity.

Adolescent↗
PubMed1987

Biochemical studies in mitochondrial encephalomyopathy.

The alpha-keto acid dehydrogenase complex and its component enzymes, lactate dehydrogenase, pyruvate carboxylase, cytochrome c oxidase, succinate-cytochrome c reductase, NADH-cytochrome c reductase, and the concentration of cytochromes and enzymes of beta-oxidation in muscle from a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes were studied and no specific defect was found. These results raise the possibility that the mitochondrial changes in the patient may be secondary.

Acidosis, Lactic↗
PubMed1985

Decreased parvalbumin contents in skeletal muscles of C57BL/6J(dy2J/dy2J) dystrophic mice.

Parvalbumin content is decreased by 40% in hindlimb muscles of adult (3.5 months) dystrophic mice when compared to normal mice of the same age. The concentration of parvalbumin in the dystrophic muscles resembles that of immature muscles of 4-week-old normal mice. The reduction may contribute to an elevation of sarcoplasmic free CA2+, which could stimulate various Ca2+-dependent processes related to the disease.

Animals↗