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Biomedical subjects

J Lehmann

Publications and source records attributed to J Lehmann.

At least 199 records · Page 11Linked to original sources
PubMed1990

[Lactones. 22. Synthesis and reduction of alpha-aminomethylene-delta,delta-diphenyl-delta-valerolactones].

Treatment with tris-(dimethylamino)-methane resp. formylation and reaction with piperidine transfer 1 to 5a,b, which can not be reduced to the corresponding alpha-aminomethyllactones 4a,b, in contrast to the homologue 6 and other alpha-aminomethylene-gamma- and delta-lactones. Isolation of products and gc/ms-investigations verify the reaction course: The aminomethyl moiety in alpha-position of delta,delta-diarylated delta-lactones is instable and eliminates amine to give 7 (NaCNBH3) or 9 (H2/Pt). Only cleavage of the lactone ring enables the formation of stable aminomethyl compounds (10,11). 5a shows weak parasympatholytic and no H1-antihistaminic activity at the isolated guinea-pig ileum.

Animals↗
PubMed1990

Selective activation of dopaminergic pathways in the mesocortex by compounds that act at the phencyclidine (PCP) binding site: tentative evidence for PCP recognition sites not coupled to N-methyl-D-aspartate (NMDA) receptors.

Several lines of evidence suggest a tight functional coupling between N-methyl-D-aspartate (NMDA) and phencyclidine (PCP) receptors. The effects of PCP receptor agonists (PCP, dexoxadrol, ketamine and MK-801) and NMDA receptor antagonists, cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS-19755) and 3-(2-carboxypiperizin-4-yl)-propyl-1-phosphonic acid (CPP), have been examined on the metabolism of dopamine in the mesocortex, with a view of studying the coupling between these two receptor systems. Phencyclidine receptor agonists selectively increased the metabolism of dopamine in the mesocortex without affecting the metabolism of dopamine in the striatum. N-Methyl-D-aspartate and the competitive antagonists of NMDA receptors did not effect the metabolism of dopamine, neither did the sigma receptor ligands, 1,3-di-(2-tolyl)guanidine (DTG) and rimcazole. Rimcazole also did not affect the increases in the metabolism of dopamine in the mesocortex, seen after MK-801. These data indicate that dopaminergic neurons in the mesocortex are positively modulated by PCP receptors but tentatively suggest that those recognition sites for PCP are not coupled to NMDA receptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Interactions of phencyclidine receptor agonist MK-801 with dopaminergic system: regional studies in the rat.

Interactions of the potent phencyclidine receptor agonist MK-801 with the dopaminergic system were examined in various brain regions in the rat. MK-801 increased dopamine (DA) metabolism in the pyriform cortex, entorhinal cortex, prefrontal cortex, striatum, olfactory tubercle, amygdala, and septum without affecting DA metabolism in the cingulate cortex and nucleus accumbens. In pyriform cortex and amygdala, MK-801 was more potent than phencyclidine at increasing DA metabolism. Local injections of MK-801 into ventral tegmental area and into the amygdala/pyriform cortex interface indicated that MK-801 may act at the cell body as well as the nerve terminal level to increase DA metabolism and that ongoing dopaminergic neuronal activity is a prerequisite for full drug action.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

[Growth rate of glioblastoma multiforme].

The velocity of events in cases of glioblastomas is well known. In spite of modern methods of examination the perceivability can miss. By one's own experiences the value of the unchanged role of clinical and neurological examination is point out.

Brain Neoplasms↗
PubMed1990

CGS 19755: a novel competitive N-methyl-D-aspartate (NMDA) receptor antagonist with anticonvulsant, anxiolytic and anti-ischemic properties.

CGS 19755 is a potent and selective competitive antagonist at NMDA receptors in the brain. In preclinical animal tests, the compound produces anticonvulsant, anxiolytic and anti-ischemic effects. CGS 19755 is not very active when administered orally, and intravenous administration is the most practical for clinical application. The anti-ischemic potential of CGS 19755 provides the most attractive application for clinical investigation.

Animals↗
PubMed1990

[Changes in the general activation level in psychophysiologic studies--II. Values of auditory evoked potentials in relation to impression and perception and heart rate].

In psychophysiology all procedures used are accompanied with changes of general activation level (GAL) of the subjects. In our study these changes are characterized by self-assessment of the internal state and by the mean heart rate (HR) of each period. On the basis of these data group mean auditory evoked potentials (AEPs) were computed. The influence of the GAL on the N 110- and P 190-amplitudes of the AEPs was analysed. There was no effect on the P 190-amplitude whereas the N 110-amplitude shows distinct responses on changes in GAL. These amplitudes diminished when the subjects reported a change of internal state. The diminishing of N 110-amplitudes took place as well at an increase as at a decrease of the internal state factors. Comparing the HR and the N 110 of the AEPs we found an inverse U-shaped dependence. These results are discussed in comparison to the literature. Furthermore a model which could elucidate the observed findings is presented for a critical discussion.

Adult↗
PubMed1990

Culture and stimulation of human T- and B-lymphocytes.

The cultivation and stimulation of human peripheral blood cells by different mitogens were studied using a serum-free culture technique. It shows the possibility to culture human PBL in a commercially available serum-free medium over a period of at least 7 days. In a serum-free medium with high protein content the viability of the cells was higher than in one with low protein content or in a serum containing medium. It is possible to stimulate human T cells by phytohaemagglutinin in a serum-free medium. After measurement of [3H]thymidine incorporation, a significant difference between control and test cultures was found. There is also a difference between serum-free medium with high and low protein content. Human peripheral B lymphocytes stimulated by pokeweed mitogen did not show any measurable IgG-secretion if they were cultured in serum-free medium.

B-Lymphocytes↗
PubMed1990

[Experiences in the diagnosis and treatment of polyneuropathies in patients with malignant monoclonal gammopathy].

4 patients are reported having monoclonal gammopathies, who clinically exhibited a sensomotoric polyneuropathy being progressive during some years. The EMG showed axional failure and secondary demyelisation. In two of the patients an IgG-type multiple myeloma has been revealed, while in the other two ohnes an increase of abnormal IgM-mIg could be demonstrated. In all patients the liquor protein was found increased and the appropriate mIg has been found in the liquor. Immunohistochemically the appropriate immunoglobulins could be demonstrated on the peripheral nerve by means of immunofluorescence method. Electron microscopical studies of nerval biopsies supported the diagnosis of mIg-associated polyneuropathy. References to diagnostics and treatment of mIg-associated polyneuropathy are done.

Aged↗
PubMed1989

Alpha- and gamma-tocopherol levels in lipoproteins fractionated by affinity chromatography.

Alpha- and gamma-tocopherol levels of nine women were measured in whole serum and in serum lipoproteins separated by heparin affinity chromatography. Alpha-tocopherol levels (mean +/- SD) in whole serum, low density plus very low density lipoproteins and high density lipoproteins were 10.8 +/- 2.7, 6.4 +/- 1.6 and 4.6 +/- 1.4 (micrograms/ml), respectively. Corresponding values (micrograms/ml) for gamma-tocopherol were 1.2 +/- 0.5, 0.7 +/- 0.3 and 0.6 +/- 0.2. Recoveries of serum alpha- and gamma-tocopherol from the heparin columns were 102 +/- 5% and 105 +/- 7%, respectively. Serum alpha-tocopherol was linearly correlated with components of high density lipoprotein (apolipoproteins, high density lipoprotein cholesterol), but not with serum total lipids or indices of low density lipoprotein, even though high density lipoprotein carried less than half of the serum alpha-tocopherol. However, serum gamma-tocopherol was highly correlated with indices of serum lipids, such as serum cholesterol (r = 0.92, p = 0.005). The coefficient for the correlation of low density lipoprotein (+ very low density lipoprotein) tocopherol with high density lipoprotein tocopherol was r = 0.66 (p = 0.06) for alpha-tocopherol and r = 0.84 (p = 0.004) for gamma-tocopherol. These differences in the relationships of the two tocopherols to lipids and lipoproteins support the view that when the two tocopherols are present at normal dietary levels, gamma-tocopherol partitions between lipoproteins based on their relative lipid content, but a portion of the alpha-tocopherol in high density lipoprotein is specifically bound.

Adult↗
PubMed1989

Differential effects of phencyclidine (PCP) and ketamine on mesocortical and mesostriatal dopamine release in vivo.

The interactions of phencyclidine (PCP) with the mesocortical dopaminergic system were of interest because of the putative role of this pathway in the etiology of schizophrenia. In the present investigation we examined the effects of PCP, and PCP-receptor agonist, ketamine, on dopamine (DA) release by measuring the levels of 3-methoxytyramine (3-MT), the only DA metabolite which is a reliable indicator of DA release in vivo. PCP increased DA release in the amygdala, pyriform and prefrontal cortices, while ketamine was less potent than PCP in this respect. In contrast to the changes in DA release in the cortical regions, ketamine decreased DA release in striatum, while PCP did not change DA release.

Amygdala↗
PubMed1989

The imidazoline-preferring receptor.

Evidence gathered over the past ten years supports the existence of subtypes of alpha 2-adrenoceptors. A receptor which resembles the alpha 2-adrenoceptor, called the imidazoline-preferring receptor (IPR), is virtually insensitive to catecholamines but binds selectively imidazolines and oxazolines such as idazoxan and rilmenidine. In contrast, the catecholamine-preferring alpha 2-adrenoceptor is preferentially activated by catecholamines including alpha-methylnorepinephrine and epinephrine and is antagonized selectively by rauwolscine. In addition to different pharmacological profiles to agonists and antagonists, the IPR and alpha 2-adrenoceptors show differences in anatomical distribution and molecular properties. The evidence has been drawn primarily from in vitro physiological and radioligand binding studies, but is gradually extending into in vivo and even clinical studies.

Adrenergic alpha-Agonists↗
PubMed1989

[Activity status in psychophysiologic studies. "Changes in the general activity level in psychophysiologic studies--an analysis of objective and subjective parameters"].

The general activation level (GAL) is one of the sources of influence in psychophysiological experiments. That means most of the results are dependent on the GAL. Taken this into account one can furthermore elucidate a part of the high variability of the interesting physiological data. We analysed heart rate (HR), auditory evoked potentials (AEP) elicited by background stimuli and the subjective assessment of the internal state of the subjects to describe changes of the GAL. Summarizing the results we can show different influences of the GAL on the physiological data. Changes of HR and AEP-parameters are caused by specific experimental conditions. The distinct influence of the subjective state of the subjects on the AEP-shapes allows the conclusion that subjective data should be more taken into consideration. The comprehensive characterization of the GAL requires data of different integrative levels.

Adult↗
PubMed1989

[Secondary muscular carnitine deficiency following immunosuppressive treatment].

Carnitine deficiency syndromes can be classified into two groups: primary carnitine deficiency and secondary carnitine deficiency syndromes. A lipid storage myopathy with carnitine deficiency following an immunosuppressive therapy is described in a young man suffering from a possible polymyositis. After treatment with L-carnitine both biochemical and morphological features recovered. A secondary carnitine deficiency syndrome due to an immunosuppressive therapy is supposed.

Adult↗
PubMed1989

[Proliferative kidney disease (PKD) of salmonids].

Proliferative Kidney Disease (PKD) of salmonids, pathology, occurrence and the causative agent are described according to recent literature. For diagnosis histology and/or impression smears of infected kidneys are recommended. Original coloured photos are added to serve this purpose.

Animals↗
PubMed1988

Malto-oligosaccharide homologues of 3,7-anhydro-2-azi-1,2-dideoxy-D-glycero-D-gulo-octitol+ ++: improved photoaffinity reagents for labelling the malto-oligosaccharide-binding protein of Escherichia coli.

3,7-Anhydro-2-azi-1,2-dideoxy-D-glycero-D-gulo-octitol (2) was synthesized as a beta-D-glucopyranosyl analogue, which could be converted into a series of malto-oligosaccharide derivatives (3-7) by cyclodextrinase-catalyzed glucosyl transfer from alpha-cyclodextrin (cyclomaltohexaose). The pure analogues 3-7 containing 1-5 (1----4)-linked alpha-D-glucose residues inhibited the uptake of maltose via the maltose-binding protein-dependent transport system in Escherichia coli. The concentration of half-maximal inhibition of maltose transport at 60nM decreases with increasing chain-length of the analogue, reaching a minimum at 0.02 mM for 6 (4 glucose residues). 3H-Labelled alpha-cyclodextrin was prepared by partial oxidation and reduction of the aldehyde groups with NaB3H4. Radiolabelled 5a was used to photolabel the binding site of the maltose-binding protein.

ATP-Binding Cassette Transporters↗