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Biomedical subjects

N M van Gelder

Publications and source records attributed to N M van Gelder.

At least 37 records · Page 2Linked to original sources
PubMed1984

Familial periodic ataxia responsive to acetazolamide.

Two cases, a father and son, of recurrent cerebellar ataxia in the same family are reported, suggesting a familial trait for the dysfunction. In the older male the onset of each episode (30-90 min.) was signalled by dysarthria which then progressed towards gait ataxia; the son presented closely similar clinical symptoms. Physical examination and blood chemistry revealed no obvious neurological deficit or biochemical abnormalities, with the exception of I-III and III-IV evoked auditory wave interpeak latencies, which were found markedly abnormal on the left side in the father but not in the son; the EEG of both individuals showed some diffuse, slow wave abnormalities. A low dose of acetazolamide, 250 mg daily, has successfully repressed recurrence of the attacks over the past six months. Temporary withdrawal for 14 days of the carbonic anhydrase inhibitor in the father coincided with two observed ataxic episodes.

Acetazolamide↗
PubMed1984

Platelet taurine content in Friedreich's disease.

We have studied the concentrations of taurine and of 6 other amino acids in platelets from 12 patients with Friedreich's disease and 12 age sex-matched normal control subjects. No significant differences could be demonstrated between the two groups. The glycine/serine ratio was lower in all the patients but this change did not reach statistical significance. From these and other data, we conclude that the taurine retention deficit observed previously in Friedreich's disease cannot be the primary causal defect.

Adult↗
PubMed1983

A central mechanism of action for taurine: osmoregulation, bivalent cations, and excitation threshold.

A postulated zinc-taurine complex, with a zinc affinity intermediate between that for glutamic acid dehydrogenase and the calcium binding protein(s), provides an explanation for a series of seemingly unrelated biochemical and physiological effects of taurine. The proposed complex suggests a central mechanism for the action of taurine, such as a bicarbonate and pH dependent influence on calcium and zinc movements (and vice versa), the osmoregulatory role of taurine, and its effect on the excitation threshold.

Animals↗
PubMed1983

Feline generalized penicillin epilepsy: changes of glutamic acid and taurine parallel the progressive increase in excitability of the cortex.

A coinciding temporal sequence of electrophysiological and biochemical correlates of developing generalized penicillin epilepsy in cats may indicate a "cause and effect" relationship between the two phenomena. After intramuscular injection of penicillin, in the pre-epileptic state prior to the onset of spike-and-wave discharge, the cortical content of glutamic acid decreases. This change occurs when an increased amplitude of visual evoked potentials in association cortex heralds the approach of spike-and-wave activity. The decrease of glutamic acid and that of aspartic acid occur in parallel with an almost stoichiometric increase of glutamine, gamma-aminobutyric acid (GABA), or both, while taurine levels in the pre-epileptic state remain near normal. As the pre-epileptic progresses to the epileptic state, characterized by generalized 4-5 cycles/s spike-and-wave discharges, a failure of the glial capture mechanisms for taurine and glutamate appears to occur, since both amino acids are lost from the tissue and glutamine levels fall while GABA levels are maintained or become elevated but increasingly at the expense of aspartic acid. A presumed increase in interstitial glutamic acid concentration possibly in combination with subsequent failure of GABA inhibition appears the most plausible explanation for the increasing hyperexcitability during the development of feline generalized penicillin epilepsy.

Animals↗
PubMed1982

Protein and taurine of maternal diets during the mouse neonatal period: permanent effects on cerebellar--brainstem amino acid levels in mature offspring.

Neonatal malnutrition and/or undernutrition of limited duration appears to permanently influence steady state amino acid content of the adult mouse cerebellum and/or brainstem. Some of the changes seem related to the protein content of the milk (glutamine), whereas others reflect the taurine concentration in the milk during the neonatal period (glutamic acid and GABA). Adult levels of taurine, serine, and glycine in the cerebellum-brainstem may in part be influenced by the degree of growth retardation which occurred during the first 16 days of neonatal life. Provided the combined adult weight of the cerebellum and brainstem can be used as one criterion to determine growth retardation during the neonatal period, it appears justified to state that mice do not recover from malnutrition/undernutrition when subjected to such conditions during early infancy.

Aging↗
PubMed1981

Effect of protein and taurine content of maternal diet on the physical development of neonates.

The effect of taurine and/or protein composition of maternal diets was examined for effects on survival rates and growth of neonates. Most of the effects observed are attributable to the influence of such diets on both the quantity and quality of the milk supplied to the neonates. The taurine and protein content of the diets exhibit an interdependent relationship with respect to regulating the protein and taurine concentration of the milk. The overall effect of dietary taurine was to increase neonatal survival during the period that the mothers received a protein-deficient diet.

Animals↗
PubMed1981

Glutamic acid in nervous tissue and changes of the taurine content: its implication in the treatment of epilepsy.

In order to account for interdependent changes in the steady state cerebral levels of glutamic acid, taurine and glutamine, two compartments are considered which are connected by an adjustable flow valve. The first compartment may be equated with neuronal structures and confines most of the steady state content of glutamic acid. The second compartment represents glia and contains most cerebral glutamine; taurine is sequestered by both anatomic compartments. The adjustable valve symbolises a combination of rate limited release, transport, and enzymic mechanisms responsible for connecting the glutamate containing structures with those sequestering glutamine. These compartments only represent a portion of the total intracerebral metabolism of glutamic acid (see 19).

Animals↗
PubMed1980

Alterations in the compartmentalized metabolism of glutamic acid with changed cerebral conditions.

Data obtained from combined determinations of the nervous tissue content of glutamic acid, taurine and glutamine were examined in terms of the well established concept of a compartmentalized metabolism for glutamic acid. Three different situations associated with altered cortical conditions were studied: cortical hyperexcitability induced by cobalt epilepsy (mouse); chronic stimulation of the optic tectum by light adaptation (fish); and anatomic alteration of the optic tectum following unilateral enucleation (fish). All 3 situations appear to cause a reduction in the ability of glial elements to capture free glutamic acid released from neuronal structures. However, the underlying causes for such an insufficiency seem to differ in each instance. In epilepsy the release of glutamic acid and taurine exceeds the glial capture rate; during chronic stimulation of a normal cortex a diminished glial uptake rate for both amino acids seems apparent; anatomical degenerative changes seem to diminish especially the glutamine retention capacity of the cortex, possibly in combination with a reduced glial taurine uptake.

Animals↗
PubMed1980

Plasma amino acids in 3/sec spike-wave epilepsy.

Plasma levels of 14 amino acids were determined in 44 probands with 3/sec spike-wave epilepsy, 27 of their first-degree relatives, and 22 controls. Six ratios of metabolically related amino acids were also calculated. Statistically significant differences were found for 7/20 variables when the experimental and control probands were compared, and for 6/20 variables when the relatives were compared with controls. Tau, Asp, and Tau/Glu were decreased and Glu was was increased in both the experimental probands and their first degree relatives. When discriminant analysis was used, age- and sex-matched epileptic probands could be distinguished from the age- and sex-matched control probands with 100% accuracy employing only 3 amino acids (Asp, Glu, Val) and one ratio (Thr/Ser).

Adolescent↗
PubMed1980

Amino acid changes in a genetic strain of epileptic beagle dogs.

A neurochemical evaluation of beagle dogs with naturally occurring spontaneous generalized convulsive seizures was performed. Amino acid profiles of serum, cerebrospinal fluid (CSF), and biopsied cerebral cortex from epileptic dogs were compared with those from seizure-free siblings. No differences in absolute levels were noted. However, when levels were normalized as a percent of total free amino acids, seizures was performed. Amino acid profiles of serum, cerebrospinal fluid (CEF), and biopsied cerebral cortex from epileptic dogs were compared with those seizure-free siblings. No differences also the two groups differed in certain respects. Ten significant correlations between amino acid pairs appeared in epileptic dogs, but only one was seen in seizure-free animals. Seven of these ten correlations involved glutamate or taurine. It was noted that the highly correlated amino acids (taurine, glutamate, glycine, glutamine, alanine) all utilize sodium-dependent membrane transport processes. The sum of glutamate, aspartate, and glycine levels (competing sodium-dependent high-affinity systems) was significantly lower in epileptic beagles. Since this difference was noted in serum but not CSF or brain, it may indicate a diminished capacity of sodium-dependent high-affinity renal transport for acidic and certain small neutral amino acids.

Amino Acids↗
PubMed1978

Interrelated changes of amino acids in the retina and optic tectum of a marine fish with alterations of illuminating conditions.

Examination of interrelated changes in the concentrations of 'clusters' of amino acids provides evidence that individual amino acid levels in the tissues cannot be considered to vary independently. Such variations are observed when the CNS at 'rest' is stimulated. Alterations in taurine cause changes in glutamic acid and also modify its anatomically related compartmentalized metabolism. Similar interdependent modifications may be indicated for the concentrations of 3 biochemically related neutral amino acids: threonine, serine and glycine. With specific reference to the fish optic tectum and retina, certain differences and coincidences in the regulation of GABA and glycine have also been uncovered. Finally, many of the findings presented here are closely analogous to results obtained when comparing normal and epileptic mammalian tissues. Possibly, this analogy can be attributed to the fact that the physiological states so far investigated, from the most simplistic point of view, represent extreme variations of nervous tissue excitation.

Amino Acids↗
PubMed1978

Influence of taurine dosage on cobalt epilepsy in mice.

The present work addresses itself to answering several questions in relations to the antiepileptic action of taurine (see "Introduction"). For this purpose, cobalt epileptic mice, treated with isoosmolar saline or not treated, was compared with groups of mice that had received doses of taurine varying between 1.0 and 10.0 mg/kg. Whereas all the taurine doses employed effectively reduced seizure incidence, with 10.0 mg/kg giving the best results, none of these doses had ameliorated the amino acid abnormalities in the cortex after two days of treatment in comparison with the group that had received isoosmolar saline. On the contrary, the largest amino acid abnormalities occurred in the group of mice (10.0 mg/kg) that had improved the most clinically. We conclude that the acute antiseizure action of taurine, and its effect on restoring normal amino acid patterns in the cortex, represent two separate properties of taurine.

Amino Acids↗
PubMed1977

Taurine treatment of spontaneous chronic epilepsy in a cat.

Administration of taurine to a cat suffering from naturally occurring chronic (about 3 years) epilepsy caused disappearance of the clinical manifestation of the seizures as well as a marked improvement in the previously grossly abnormal EEG. The treatment consisted of injections of taurine initially, followed by a more prolonged administration of the amino acid by mouth. The combined methods of administration seemed essential for the success of the trial. To date (5 months post-taurine) the animal has suffered only one "grand mal" type seizure which occurred 3 months after the last dose of taurine was administered. Disappearance of the seizures preceded by several weeks the improvement in the EEG. In accordance with previous findings by a number of investigators, the results of this study suggest an immediate depressant action of taurine on hyperexcitable cortical neurons, followed by a more long-lasting, ameliorative influence on cerebral metabolism contributing to an increased resistance to epileptic discharge.

Administration, Oral↗