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Biomedical subjects

W D Rausch

Publications and source records attributed to W D Rausch.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effect of lipoic acid on redox state of coenzyme Q in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and diethyldithiocarbamate.

We investigated the effects of a combined treatment of male C57Bl/6 mice with diethyldithiocarbamate and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the absence or presence of different forms of lipoic acid (Thioctacid TR; commonly used for treatment of diabetic polyneuropathies) on levels and redox states of alpha-tocopherol and coenzyme Q in vivo and on activities of various enzymes of energy metabolism ex vivo. Treatment of mice with diethyldithiocarbamate plus MPTP resulted in a decrease in dopamine (67%) and its major metabolites dihydroxyphenylacetic acid (38%) and homovanillic acid (37%) in striatum. alpha-Tocopherol levels were unaltered in striatum; however, the reduced forms of coenzyme Q were decreased in frontal cortex and hippocampus following diethyldithiocarbamate plus MPTP. In frontal cortex activity of NADH dehydrogenase was significantly inhibited by diethyldithiocarbamate plus MPTP ex vivo, suggesting that the neurotoxic metabolite of MPTP, 1-methyl-4-phenylpyridinium ion, is acting in brain regions other than striatum as well. Lipoic acid, administered 6 times, each at 90 min prior to MPTP, could not restore dopamine in striatum but in contrast maintained a normal ratio of the reduced form to the oxidized form of coenzyme Q, suggesting an interaction of lipoic acid with energy metabolism which seems, however, not only to be due to an activation of pyruvate dehydrogenase.

Animals↗
PubMed1994

Influence of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, lipoic acid and L-deprenyl on the interplay between cellular redox systems.

For several years there is controversy concerning the toxic potency of reaction products catalyzed by monoamine oxidase in neurodegenerative processes. There is uncertainty whether products of catecholamine oxidation are pathogenetically relevant factors for neuronal cell death in Parkinson's disease. To date products responsible for impairment of biochemical functions essential for cell viability are not yet identified, and the primary site of damage within the cell is unknown. Ammonia, aldehydes and hydrogen peroxide are formed via monoamine oxidase catalyzed oxidations of primary amines. But which of them, if any, is damaging to the cell? We discuss some aspects of the oxidative stress theory of cell degeneration in relation to toxicity of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and to monoamine oxidation. Furthermore, we consider possible functional relationships of mitochondrial electron transfer reactions, toxicity of MPTP and MAO activity.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

Neuroprotection by dopamine agonists.

Research on Parkinson's disease has led to new hypotheses concerning the mechanisms of neurodegeneration and to the development of neuroprotective agents. Recent findings of impaired mitochondrial function, altered iron metabolism and increased lipid peroxidation in the substantia nigra of parkinsonian patients emphasize the significance of oxidative stress and free radical formation in the pathogenesis of Parkinson's disease. Present research is therefore focussing on improvements in neuroprotective therapy to prevent or slow the rate of progression of the disease. Possible neuroprotective strategies include free radical scavengers, monoamine oxidase-B inhibitors, iron chelators and glutamate antagonists. Recent studies point to the possibility of achieving neuroprotection in ageing and parkinsonism by the administration of dopamine agonists. In the rat, the dopamine agonist pergolide appears to preserve the integrity of nigrostriatal neurones with ageing. The prevention of age-related degeneration may be achieved as a result of a decreased dopamine turnover and reduced conversion of dopamine to toxic compounds. In our own study, bromocriptine treatment prevented the striatal dopamine reduction following MPTP administration in the mouse. These results suggest that the neurotoxic effects of MPTP can be prevented by bromocriptine. Monotherapy with the dopamine agonist lisuride in the early stages of Parkinson's disease delays the need for the initiation of levodopa treatment to a similar extent as has been reported for L-deprenyl. It remains to be shown whether this is due to neuroprotective efficacy of the dopamine agonist or to a direct symptomatic effect.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1993

Functional changes in cocultures of mesencephalon and striatal neurons from embryonic C57/BL6 mice due to low concentrations of 1-methyl-4-phenylpyridinium (MPP+).

1-Methyl-4-phenylpyridinium (MPP+), the active metabolite of 1-Methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP) is taken up into dopaminergic terminals and selectively destroys dopaminergic neurons, serving as a valuable tool in animal model of Parkinson's disease. Cocultures from ventral mesencephalon and neostriatum of embryonic C57/BL6 mouse brains were used to study the sensitivity of dopaminergic neurons to the toxic agent MPP+. Cultures were grown for 9 days in vitro and exposed to different concentrations of MPP+ for various times. Treatment with (0.1-1.0 microM) MPP+ for 24 hours decreased 3H-dopamine (3H-DA) uptake with an IC50 at 0.2 microM. Exposure of cells to 1 microM MPP+ over time decreased the 3H-DA uptake to 38% of controls within the first two hours of incubation and to 8% after 48 hours. Loss of tyrosine hydroxylase (TH) positive cells became evident at 0.1 microM MPP+ (80% of control) leading to maximal toxicity at 10 microM (20% of control). MPP+ reduced the dopamine content in the cultures in a dose dependent manner (IC50 at 0.1 microM) and failed to show reversibility in recovery studies. These findings provide evidence that exposure of MPP+ even at low concentrations and for short time in our coculture model results in irreversible toxicity for dopaminergic neurons.

Animals↗
PubMed1993

Influence of labor and neonatal hypoxia on sympathoadrenal activation and methionine enkephalin release in calves.

Labor and delivery stimulate increased release of catecholamines and endogenous opioid peptides in neonates. Catecholamines promote adaptation to the extrauterine environment after birth. Enkephalins are stored together with catecholamines in the adrenal medulla and have an inhibitory effect on catecholamine release. We investigated the influence of labor and neonatal hypoxia on epinephrine, norepinephrine, and met-enkephalin release in calves. Blood samples were taken from the umbilical artery before rupture of the umbilical cord and from the jugular vein repeatedly after birth. Highest plasma norepinephrine concentration was found in calves delivered at the end of gestation (term calves) before umbilical cord rupture. In calves delivered before the physiologic end of gestation (preterm calves), norepinephrine values increased after cord rupture, but remained lower than values in term calves. Epinephrine release followed a similar pattern, but norepinephrine was clearly predominant. In term calves, met-enkephalin values were significantly higher than values in preterm calves. In calves of both groups, met-enkephalin release increased after cord rupture. During birth, the increase in catecholamine release seems to take place earlier than that of enkephalins. Norepinephrine-dominated stimulation during expulsion of the calf might be followed by increasing enkephalinergic inhibition after cord rupture and onset of respiration. Reduced release of catecholamines and enkephalins in preterm calves may be connected with delayed adaptation to the extrauterine environment.

Acidosis↗
PubMed1990

Effects of L-deprenyl and amantadine in an MPTP-model of parkinsonism.

Mongolian gerbils of both sexes received a single daily dose of 40 mg/kg of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) over 4 consecutive days. On the fifth day the animals were treated with 15 mg/kg i.p. of L-deprenyl or amantadine or the combination of both drugs. At different time intervals (1, 2, 5 hours) the animals were sacrificed. In the caudate nuclei dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were measured by an HPLC technique. MPTP affected the dopaminergic (HVA -25%) as well as the serotoninergic system (5-HT -54%, 5-HIAA -31%). L-deprenyl and amantadine accumulated DA and 5-HT in the MPTP affected caudates. Synergistic effects of the drug combination could be proven.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1989

Transition metals, ferritin, glutathione, and ascorbic acid in parkinsonian brains.

The regional distributions of iron, copper, zinc, magnesium, and calcium in parkinsonian brains were compared with those of matched controls. In mild Parkinson's disease (PD), there were no significant differences in the content of total iron between the two groups, whereas there was a significant increase in total iron and iron (III) in substantia nigra of severely affected patients. Although marked regional distributions of iron, magnesium, and calcium were present, there were no changes in magnesium, calcium, and copper in various brain areas of PD. The most notable finding was a shift in the iron (II)/iron (III) ratio in favor of iron (III) in substantia nigra and a significant increase in the iron (III)-binding, protein, ferritin. A significantly lower glutathione content was present in pooled samples of putamen, globus pallidus, substantia nigra, nucleus basalis of Meynert, amygdaloid nucleus, and frontal cortex of PD brains with severe damage to substantia nigra, whereas no significant changes were observed in clinicopathologically mild forms of PD. In all these regions, except the amygdaloid nucleus, ascorbic acid was not decreased. Reduced glutathione and the shift of the iron (II)/iron (III) ratio in favor of iron (III) suggest that these changes might contribute to pathophysiological processes underlying PD.

Aged↗
PubMed1989

[Catecholamine and cortisol concentrations in plasma from cattle at parturition].

Cows with spontaneous parturition (n = 8) and cows with flumethasone (n = 3) or prostaglandin (n = 3) induced parturition were used in this study. Catecholamine concentrations from cows in the periparturient period were measured in order to evaluate the stress of birth on the dam and the calf. The plasma content of both norepinephrine and epinephrine in late pregnancy was not different from control values in the 3rd to 6th month of pregnancy (norepinephrine 3.27 +/- 0.99 nmol/l plasma and epinephrine 0.98 +/- 0.45 nmol/l plasma), though both parameters appear elevated in the pregnant group. Norepinephrine concentrations rose to a value of 4.50 nmol/l immediately after birth, whereas epinephrine levels did not show an increase post partum. In two neonates norepinephrine and epinephrine values were 2-3 times higher than in the dams and decreased to the values of the dams within 48 hours. Synthetic glucocorticoids can mimic the increase of cortisol, which leads to birth. Cortisol concentrations in the cows remained unaffected by induction of parturition by prostaglandins. Newborn calves showed values of about 330 nmol/l, which also declined within 48 hours to values similar to those measured in the dam (9-28 nmol/l). As stress and exogenous glucocorticoids may affect antibody production, the IgG-content of the colostrum was examined. Prostaglandin induction of birth did not alter the IgG-content of colostrum, but flumethasone produced a decrease of about 14.5%. It is therefore concluded that pre-term birth induction does not produce negative effects on the supply of IgG.

Animals↗
PubMed1988

Tyrosine hydroxylase activity in caudate nucleus from Parkinson's disease: effects of iron and phosphorylating agents.

Tyrosine hydroxylase (TH) activity of human postmortem brain tissues from controls and patients with Parkinson's disease (PD) was examined in the presence of Fe2+ and phosphorylation agents, such as cyclic AMP, exogenous protein kinase, calcium plus calmodulin (Ca2+-CaM), and ATP. TH activity from parkinsonian tissue was increased by 48% with statistical significance in the presence of exogenous protein kinase. Cyclic AMP alone had no effect, whereas Ca2+-CaM increased the activity by only 10%. The presence of acetylcholine resulted in a slight decrease in enzyme activity. Human TH was stimulated 13.17-fold in the presence of 1 mM Fe2+. For iron dependence, no significant differences could be shown for the Km values of TH in striata of PD, while the activity of TH was half of that of controls. Here stimulation with 1 mM Fe2+ raised the activity of TH 11-fold. Stimulation of rat, gerbil, pig, and human caudate nucleus TH with Fe2+ shows remarkable species differences. In particular, the sensitivity of human TH to stimulating processes is noteworthy. H2O2 decreases TH activity only at high concentrations. Species differences are noted for the combined incubation of Fe2+ and H2O2. In the gerbil caudate nucleus, H2O2 does not prevent the stimulating properties of Fe2+, while the pig shows a dose-dependent decline of TH activity. In conclusion, there are no significant changes in the stimulating properties of human caudate nucleus TH activity with Fe2+ in PD, while such differences are noted by using exogenous protein kinase. Furthermore, experimental evidence shows that TH activity declines at high concentrations of H2O2 only. Potentiation of this effect by Fe2+ seems to be species-dependent.

Aged↗
PubMed1987

[Metabolic changes in ischemic brain infarct].

Serum and cerebrospinal fluid (CSF) from 17 patients less than 3 days after brain infarction (measurement 1) and during recovery 7 +/- 2 days after infarction (measurement 2) were analysed for organic acids (energy metabolites, keto acids and amino acids). Clinical parameters improved by 32% over the period of assessment. Only serum pyruvate levels were elevated at both measurement times. Acute infarction was characterized by significant correspondence of serum and CSF concentrations for pyruvate and alpha-oxo-beta-methyl valeric acid which was lost during the recovery period. Amino acids of the L-system were roughly doubled (phenylalanine 7-fold in the CSF); increased concentrations were recorded for amino acids of the basic transport system, while amino acids of the A-system stayed unchanged (with the exception of alpha-amino butyric acid--20-fold in CSF). Except in the case of taurine, serum and CSF amino acid concentrations remained unchanged between the two measurement times. Mutual dependence of CSF and serum amino acid concentrations, existing initially for glycine, valine, leucine, tyrosine, as well as ornithine, lysine and histidine was lost in the recovery phase. This is interpreted as indication of a normalization of the blood-brain barrier.

Acids↗
PubMed1987

[Changes in organic acids in plasma and cerebrospinal fluid in cerebral infarct].

Seventeen patients with recent cerebral infarction were included in the study. The general condition of the patients was evaluated within 3 days after the incidence (rating 1) and 7-9 days after the incidence (rating 2) using a clinical rating scale for internal, psychiatric and neurological findings. The statistical evaluation showed a clinical improvement of the score of 32%. The extent of the brain lesions was determined by cranial computed tomography. Routine analysis of the cerebrospinal fluid included determination of protein, cell count, cell type, glucose, lactic acid, and hemoglobin. In addition, spinal fluid and serum concentration of pyruvic acid, citric acid, fumaric acid, alpha-ketoglutaric acid and alpha-keto-beta-methylvaleric acid (3-MKV) were determined at the two rating times. CSF and serum values of fumaric acid, 3-MKV and pyruvic acid correlated at rating 1, while at rating 2 a correlation existed only for fumaric acid. A trend analysis infarction - postinfarction period showed the concentration of all metabolites to decrease significantly. This is interpreted as a reconstitution of the initially disturbed blood brain barrier function.

Aged↗
PubMed1983

Studies on the neurotransmitter binding to pig brain microvessels.

Microvessels from pig brain areas were prepared by differential centrifugation techniques. These fractions were assayed for purity and structural unity by marker enzyme determination, light and electron microscopy. Binding properties of 3H-flunitrazepam were studied in different brain regions. Kinetic studies of 3H-flunitrazepam showed BMax-values of 0,42 +/- 0,3 pmol/mg protein and KD-values of 1,26 +/- 0,6 nM and were compared to a synaptosomal membrane fraction (P2-fraction) with BMax = 2,68 +/- 0,5 pmol/mg protein and a KD of 1,95 +/- 0,3 nM. GABA kinetic studies gave IC50-values of 250 nM in the microvessel fraction and 40 nM in the P2-fraction.

Animals↗
PubMed1980

Dopamine metabolism in human brain: effect of monoamine oxidase inhibition in vitro by (-)deprenyl and (+) and (-) tranylcypromine.

The effects of the monoamine oxidase inhibitors (-)deprenyl and (+)-and (-)tranylcypromine on dopamine oxidation in human caudate have been investigated. Oxidation of dopamine has been found to exhibit both (-)deprenyl-sensitive and -insensitive components. The tranylcypromine isomers are both more sensitive towards dopamine than 5-hydroxytryptamine oxidation, (+) isomer being the more effective of the two. These results are discussed in terms of the in vivo action of the drugs and their therapeutic value.

Aged↗