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Biomedical subjects

W Endres

Publications and source records attributed to W Endres.

At least 37 records · Page 2Linked to original sources
PubMed1991

Fatal infantile mitochondrial cardiomyopathy and myopathy with heterogeneous tissue expression of combined respiratory chain deficiencies.

A 5-month-old boy died of progressive heart failure that started at the age of 3 months. Autopsy revealed a mitochondrial cardiomyopathy and a mitochondrial myopathy of the limb muscle and diaphragm. Cytochemically random defects of cytochrome c oxidase were visualized by light and electron microscopy in the diaphragm and especially the heart muscle, the limb muscle showing a diffuse attenuation whereas the liver and kidneys reacted normally. The activities of NADH-dehydrogenase (complex I) and cytochrome c oxidase (complex IV) were severely diminished (20% residual activity of controls) in the skeletal and heart muscle. In the heart, succinate cytochrome c reductase (complex II/III) was additionally decreased to the same degree. Loss of cytochrome c oxidase activity was based on a reduction of both mitochondrial and nuclear derived subunits in the heart and diaphragm as revealed by immunohistochemical analysis, whereas the limb muscle showed a normal immunoreactive protein content. The results illustrate heterogeneous tissue expression of respiratory chain enzyme defects and demonstrate that a cardiomyopathy may be the leading presentation of a mitochondrial disorder in early infancy.

Cardiomyopathies↗
PubMed1991

Inadequate iron availability as a possible cause of low serum carnitine concentrations in patients with phenylketonuria.

A previous observation of decreased serum carnitine concentrations in phenylketonuria (PKU) was investigated in 169 patients either on a strict diet (n = 107; median: 8.1 years) or off diet (n = 62; median: 15.0 years). Fifty-seven metabolically healthy children (median: 8.5 years) served as controls. PKU patients on a strict diet and older than 2 years had significantly lower serum carnitine concentrations (19.4 +/- 5.4 mumol/l) than those off diet (29.6 +/- 6.7 mumol/l). PKU patients on diet also had significantly lower concentrations of haemoglobin and serum ferritin than those off diet. A linear correlation existed between total serum carnitine and ferritin concentrations up to 40 micrograms/l (r = 0.52; P less than 0.01). As iron is an essential cofactor of carnitine synthesis we conclude that reduced endogenous carnitine synthesis due to an inadequate availability of iron may be a major cause of low serum carnitine concentrations. The low carnitine content of the strict and highly protein-reduced diet additionally contributes to a decrease in the serum carnitine concentration. Our results show that a further optimization of the PKU diet increasing either iron availability or carnitine intake should be considered.

Adolescent↗
PubMed1990

Cataract and metabolic disease.

In addition to the already recognized metabolic diseases which have been associated with cataract formation, e.g. galactosaemia, galactokinase deficiency, Lowe's syndrome and diabetes, several other disorders can also lead to the development of cataracts. They are sorbitol dehydrogenase deficiency, uridine diphosphate galactose-4-epimerase deficiency, marginal maternal transferase and galactokinase deficiency, galactitol and sorbitol accumulation of unknown origin, heterozygosity for galactosaemia and galactokinase deficiency as well as the carrier state for Lowe's syndrome. In this review these metabolic disorders have been divided into five groups according to the age at the first appearance of lens clouding and the possible means of treatment have been discussed.

Adult↗
PubMed1990

Plasma polyol levels in patients with cataract.

Galactitol and sorbitol concentrations in plasma were determined in patients (with or without cataract) in whom homo- or heterozygosity for galactokinase, galactose-1-phosphate uridyltransferase, systemic or peripheral UDP-galactose epimerase and sorbitol dehydrogenase deficiency was confirmed. For the above disorders it can be concluded that elevation of plasma polyols is not always related to the presence or absence of cataract. In all cases with cataract, however, the plasma galactitol or sorbitol levels were elevated. In another group of patients with unexplained congenital or infantile cataracts, but without apparent enzyme defects, mild to moderately elevated concentrations of plasma galactitol or sorbitol were found in about 45%. In 8% of this group the cataract and the elevated plasma galactitol concentration could possibly have been related to partial maternal enzyme deficiency. In all the other cases the elevated plasma polyol concentration remains unexplained but could indicate a further cause of cataract formation due to a hitherto unknown galactose or glucose metabolic aberration.

Carbohydrate Epimerases↗
PubMed1989

Acetylcholinesterase reactivators antagonize epileptiform bursting induced by paraoxon in guinea pig hippocampal slices.

The electrophysiological actions of paraoxon, an irreversible blocker of acetylcholinesterase, and their antagonism by a series of organophosphate cholinesterase reactivators, were studied in area CA1 of the guinea pig hippocampus in vitro. To avoid indirect effects elicited by excitation of CA3 neurons, the CA2/3 regions were removed routinely before the recording of extracellular field potentials in CA1. Under these conditions, paraoxon (1 microM) induced regular burst activity (rate, 2-10/min; amplitude, 0.2-1 mV; duration, 100-500 msec). The antagonism of this burst activity by atropine (0.3-1.0 microM) and pirenzepine (1.0 microM) suggested the involvement of muscarinic cholinoceptors in the mediation of this response. The reduction in frequency of paraoxon-induced bursting by the cholinesterase reactivators was taken as an index of their efficacies. The four oxime compounds tested were all active in the low micromolar range (rank order of potencies: obidoxime greater than HGG 12 = HLö 7 greater than Hl 6). In experiments without paraoxon, these oximes did not depress either evoked population spikes in normal artificial cerebrospinal fluid or bursts induced by superfusion with Mg++-free artificial cerebrospinal fluid. Thus, an unspecific inhibitory effect of oximes can be excluded. It is concluded that the in vitro hippocampus provides a suitable system for the quantitative electrophysiological evaluation of cholinesterase reactivators in the central nervous system.

Acetylcholine↗
PubMed1988

Report on a new patient with combined deficiencies of sulphite oxidase and xanthine dehydrogenase due to molybdenum cofactor deficiency.

A newborn infant exhibiting seizures and spastic tetraparesis at the age of 1 week was shown to excrete excessive quantities of sulphite, taurine, S-sulphocysteine and thiosulphate, characteristic of sulphite oxidase deficiency. In addition, increased renal excretion of xanthine and hypoxanthine combined with a low serum and urinary uric acid was consistent with xanthine dehydrogenase deficiency. Both deficiencies could be established at the enzyme level. The primary defect giving rise to the combined abnormalities is the absence of a molybdenum cofactor, a molybdenum-containing pterin being an essential component of both enzymes. The patient developed a severe neurological syndrome, brain atrophy and lens dislocation and died at the age of 22 months. Attempts at treatment, such as oral administration of ammonium molybdate, sodium sulphate, D-penicillamine, 2-mercaptoethane sulphonic acid, pyridoxine and thiamine did not influence the clinical course.

Abnormalities, Multiple↗
PubMed1988

Continuous electrophysiological measurements of changes in cell volume of motoneurons in the isolated frog spinal cord.

One type of ion-sensitive micro-electrode (K+ ligand Corning 477317) is sensitive to large quaternary ammonium ions such as choline or tetramethylammonium (TMA+). We have now used such electrodes for continuous electrophysiological measurements of changes in cell volume of motoneurons in the isolated frog spinal cord. The electrodes were double-barrelled with tip diameters of 1 micron. The reference barrel was filled with 100 mM choline or 100 mM TMA+ in 1 M Mg2+-acetate, the sensitive barrel contained the Corning K+ ligand. After the impalement of a motoneuron, choline or TMA+ diffused into the cell and about 1 h later, a steady-state concentration of these ions in the range of 10-20 mM was reached. Following this period, the motoneurons were activated by repetitive electrical stimulation or by application of amino acids via the bathing solution. All these stimuli led to a transient rise of the intracellular concentrations of choline or TMA+ (indicating a cell shrinkage of 3-10% difference to control volume).

Amino Acids↗
PubMed1988

Glucose depletion hyperpolarizes guinea pig hippocampal neurons by an increase in potassium conductance.

Superfusion of guinea pig hippocampal brain slices with a glucose-free solution induced a membrane hyperpolarization and an increase in input conductance of neurons in the CA3 region. Under voltage clamp, glucose depletion induced an outward current with a reversal potential near the K+ equilibrium potential. The action of glucose depletion was different from the effect of ouabain, indicating that low-glucose-induced changes in the membrane conductance are primarily due to alterations in cell metabolism rather than due only to an inhibition of the Na+/K+ pump.

Animals↗