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Biomedical subjects

P Wiechert

Publications and source records attributed to P Wiechert.

At least 19 recordsLinked to original sources
PubMed1998

Behavioral effects of vigabatrin correlated with whole brain gamma-aminobutyric acid metabolism in audiogenic sensitive rats.

The present study evaluates dose-dependent behavioral effects of acutely or subacutely administered single doses of vigabatrin (gamma-vinyl gamma-aminobutyric acid, gamma-vinyl GABA, CAS 60643-86-9) in audiogenic sensitive rats, in correlation with whole brain GABA metabolism. There was a discrepancy in timing between behaviorally observed maximal antiepileptic protection (4 h after i.p. administration of gamma-vinyl GABA) and on the other hand maximal inhibition of GABA-transaminase activity and maximal increase of whole brain GABA content (24 h after i.p. administration of gamma-vinyl GABA). This suggests that the antiepileptic properties of gamma-vinyl GABA not only depend on GABA-ergic neurotransmission. A possible explanation is a gamma-vinyl GABA-induced decrease of excitatory amino acids or increased glycine concentrations in the brain.

4-Aminobutyrate Transaminase↗
PubMed1992

Guanidino compounds in serum, urine, liver, kidney, and brain of man and some ureotelic animals.

Guanidino compound levels were quantitatively determined in serum, urine, liver, kidney, and brain of man and of some ureotelic animals. The guanidino compounds were separated over a cation exchange resin, using sodium citrate buffers, and detected with the fluorescence ninhydrin method. Species-specific differences in the levels of some guanidino compounds in the studied ureotelic animals are shown. alpha-Keto-delta-guanidinovaleric acid is a naturally occurring guanidino compound in ureotelic animals, and is not restricted to the pathobiochemistry of hyperargininemic patients. The fasting serum levels observed in beagles are the same as those found in hyperargininemic patients. In serum, liver, and kidney, the homoarginine, beta-guanidinopropionic acid, and gamma-guanidinobutyric acid levels are the highest in rats. The last two compounds have the highest levels of the studied guanidino compounds, with the exception of creatinine, in kidney. Specific high levels of gamma-guanidinobutyric acid and argininic acid are found in brain of rabbits.

Animals↗
PubMed1990

[Adrenaline and noradrenaline levels in 10-12-year-old boys during a mathematics test].

Blood plasma adrenaline and noradrenaline levels were measured using radio-enzyme techniques in 53 normally intelligent boys aged 10 to 12 years with and without Attention Deficit Disorders. The measurements were performed while the subjects were at rest and during a calculation load test. An anticipatory effect in the release of catecholamine and phasic phenomena were observed. Intelligence and mental lability are implicated in catecholamine release during load situations als well as genetic factors.

Child↗
PubMed1989

Hyperargininemia, epilepsy and the metabolism of guanidino compounds.

Patients with hyperargininemia have an arginase deficiency which leads to blockade of the urea cycle in the last step with several clinical symptoms. Owing to the arginase deficiency this patients accumulate arginine which leads to eventual alternative yet unknown pathways of arginine metabolism. These clinical and biochemical findings intensified the research on guanidino compounds. It has been shown that most of the guanidino compounds are epileptogenic. Therefore we investigated the levels of 12 guanidino compounds in serum and brain of audiogenic sensitive rats. The changes of some guanidino compounds in serum and brain will be discussed.

Amino Acid Metabolism, Inborn Errors↗
PubMed1986

Comparative study of guanidino compounds in serum and brain of mouse, rat, rabbit, and man.

The levels of 12 guanidino compounds were determined in the serum and brain of mouse, rat, rabbit, and man using cation-exchange column chromatography with the fluorescence ninhydrin detection method. A comparative study of these compounds was made in the four groups studied, for serum and brain. In rabbit and man the different guanidino compounds were also determined in various brain regions. This study provides basic analytical data that could facilitate the interpretation of further biochemical and neurochemical studies dealing with guanidino compounds that are identified as being toxins in hyperargininemia and uremia.

Animals↗
PubMed1986

Guanidino compounds in serum and brain of audiogenically sensitive rats.

The levels of 12 guanidino compounds were determined in serum and brain of audiogenically sensitive rats with and without seizures. During audiogenic seizures the serum levels of creatine are significantly decreased, while those of guanidinoacetic acid, N-alpha-acetylarginine, creatinine, gamma-guanidinobutyric acid, arginine, guanidine and methylguanidine are significantly increased. In brain only creatinine and N-alpha-acetylarginine are markedly increased during seizure. These data demonstrate noticeable modifications of the levels of guanidino compounds in the blood during audiogenic seizure and also, in parallel, a creatinine increase in serum and brain.

Animals↗
PubMed1983

[Quantitative amino acid determination in the serum and cerebrospinal fluid in endogenous depressions].

The levels of 20 amino acids were measured in the plasma and cerbrospinal fluid of 41 patients with endogenic depressions. The plasma levels of 12 amino acids were found to be significantly lower in the patients than in the control group, but cerebrospinal fluid levels were significantly lower only in the case of taurine, glutamine, phenylalanine and aginine. Comparison of the same amino acid levels in treated and non-treated patients showed that serine and alpha-aminobutyric acid serum concentrations were higher in the nontreated patients. The tyrosine and phenylalanine levels in the cerebrospinal fluid of the patients who had received medicamentous treatment were higher than in the other group.

Adolescent↗
PubMed1979

[Concentration of amino acids in synaptosomes of the rat brain in the preconvulsive phase of experimentally-induced seizures].

In the synaptic vesicae of rat brains the free amino acids were determined for control animals and experimental animals during the preconvulsive phase of induced cerebral spasms. Especially high concentrations were established for taurine, glutamic acid, asparaginic acid, gamma-aminobutyric acid and valine. Prior to a cerebral spasm the glutamic acid concentration is lowered in the synaptosomes.

Amino Acids↗
PubMed1976

Excretion of guanidino-derivates in urine of hyperargininemic patients.

Quantitative determinations were made for seven guanidino-derivates in urine of patients affected with hyperargininemia, lysine cystinuria, healthy children and adults, goats and monkey. The amount of all seven guanidino-derivates excreted in the urine with the exception of guanidino-succinic acid was large in the case of hyperargininemic patients. Guanidino-succinic acid is found in traces in the urine of these patients, even after arginine loading tests. There is apparently no similarity concerning the guanidino-derivates between the patients with hyperargininemia, a pathological status, and the arginase deficiency in goats and monkeys, a physiological phenomenon.

Adult↗