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Biomedical subjects

V Neuhoff

Publications and source records attributed to V Neuhoff.

At least 109 records · Page 6Linked to original sources
PubMed1977

[Direct immunological identification of proteins following electrophoretic separation in polyacrylamide micro-gradient gels and the effect of detergents on immunoprecipitation (author's transl)].

Methods for direct immunological identification of single protein components after fractionation of a protein mixture in microgels are described. Protein mixtures were separated with high resolution in polyacrylamide microgradient gels and transferred after electrophoresis into agarose layers containing suitable antisera. Monospecific as well as polyvalent antisera were used. The formation of immunoprecipitates could be observed within approx. 1 h. Immunoprecipitates are also formed in the presence of sodium dodecylsulfate or other detergents, thus allowing immunoreactions to be performed with water-insoluble proteins. Staining of the proteins in the gels did not completely inhibit the immunoreaction, while dansylation of proteins had no effect. The influence of different detergents e.g. sodium dodecylsulfate, Triton X-100, Brij 99, np-40 and urea, as well as different reducing agents e.g. mercaptoethanol, dithiothreitol, thioglycolic acid, on two-dimensional microdiffusion was also studied. When suitable concentrations of these compounds were used, the formation of immunocomplexes was observed within approx. 1 h. This technique can also be applied to immunoreactions with water-insoluble proteins dissolved in detergents.

Blood Proteins↗
PubMed1976

Tryptophan metabolism and the occurrence of amino acids and serotonin in the leech (Hirudo medicinalis) nervous system.

The occurrence and distribution of serotonin (5-HT) and amino acids along the central nerve chain of the leech, Hirudo medicinalis, was analyzed using dansyl-chloride in order to obtain information on the functional roles of amines and amino acids. There was no statistical variation in the occurrence of most of the amino acids or serotonin in the different parts of the dorsal nerve chain of the leech. A variation in the serotonin content was found during the year with the highest level occurring in winter. Leech ganglia also accumulated 3H-tryptophan and metabolized part of it to form 5-HTP, 5-HT, and 5-HIAA. The results are discussed from the point of view of 5-HT being a transmitter substance.

5-Hydroxytryptophan↗
PubMed1976

Activation of snail (Helix pomatia) nervous tissue tyrosine monooxygenase by calcium in vitro.

Addition of calcium chloride to soluble preparations of tyrosine monooxygenase from snail brain appears to produce an activation of the enzyme when assayed with subsaturating concentrations of the pteridine cofactor 6 MPH4 (2-amino-4-hydroxy-6-methyltetrahydropteridine). While some increase in the activity occurs with calcium chloride at a concentration of 0.01 mM, activation is increased by about 100% at 1mM and reaches a maximum at 5mM (144%) where it remains more or less constant up to 10mM. Barium chloride also produces an activating effect although it is much less pronounced while magnesium chloride is without effect. EGTA has no direct effect on the enzyme but antagonises the activation produced by calcium chloride. The activation of tyrosine monooxygenase by calcium is reflected in changes in the kinetic properties of the enzyme, decreasing the Km from 43 muM to 19 muM for tyrosine and from 670muM to 230muM for the pteridine cofactor. No change was observed with V values for either tyrosine or pteridine cofactor. It is suggested that calcium, which enters the nerve terminal during nerve stimulation, regulates the transmitter dopamine by activating the rate-limiting enzyme tyrosine monooxygenase.

Animals↗
PubMed1976

[Isoelectric focusing of complex protein mixtures in the nanogram range in microgels (author's transl)].

A method is described for isolectric focusing of complex protein mixtures in 2, 5 or 10 mul capillaries. For one separation only 15- 50 ng of a protein mixture is needed. Isoelectric focusing is finished after 10 min, staining takes 20 min and destaining approximately 30 min. Using defined mixtures of Servalyt from different pH ranges, isoelectric focusing can be adapted to the protein sample to be fractionated. Protein peaks separated by isoelectric focusing can be electrophoretically eluted and for further analysis refractionated directly in a microgradient gel. The resolution power of microisoelectric focusing is as good as that of the wellknown macroprocedure, as is demonstrated by isoelectric focusing of the water soluble proteins from cerebellum and heart, of rat and human serum and of a human oncocytoma of the thyroid gland.

Animals↗
PubMed1976

Oxidative side reactions during dansylation of SH-compounds.

Dansyl chloride can act as an oxidizing agent on compounds which are easily oxidized. During the reaction of mercaptanes, e.g. cysteine, homocysteine, cysteamine, with dansyl chloride, the corresponding disulfides are formed and dansyl chloride is reduced to 5-dimethylaminonaphthalene 1-sulfinic acid. This reaction is so rapid that the normal dansylation can take place only after complete oxidation of all SH-compounds. Therefore only the dansyl derivatives of the corresponding disulfides are formed during normal dansylation of SH-compounds. If different SH-compounds are present in the reaction mixture mixed disulfides are formed as well. These can be separated by microchromatography on 3 X 3 cm micropolyamide sheets. Dependent on the concentration of dansyl chloride, 6 or even 15 different dansylated disulfides are formed from three different SH-compounds so that interpretation of these chromatograms is difficult. The actual dansylmercaptanes (e.g., dansylcysteine, dansylhomocysteine, dansylcysteamine) can be prepared by reduction of the dansylated disulfides with suitable reducing agents.

Amino Acids↗
PubMed1976

Failure of benzoctamine to influence the activity of rat striatum tyrosine-hydroxylase.

The influence of benzoctamine (Tacitin) on rat striatum tyrosine-hydroxylase was analized. Injection of 100 mg benzoctamine/kg body weight caused no alteration in the tyrosine-hydroxylase activity whilst a decrease of about 60% in the activity was recorded after treatment with a-methyl-p-tyrosine a known inhibitor of tyrosine-hydroxylase. The present results differ from those of Maitre et al. which indicated that benzoctamine inhibited tyrosine-hydroxylase activity.

Animals↗
PubMed1976

[Quantitative determination of taurine and glycine in the picomole range using [14C]dansyl chloride (author's transl)].

Taurine, a possible neurotransmitter, and the transmitter substance glycine can be determined quantitatively in the picomole range using [14C]dansyl chloride even in the presence of a several thousand fold excess of other amino acids. However, it is necessary to eliminate the excess of dansyl chloride after complete reaction by adding diethylamine. In corresponding microchromatograms on 3 X 3 cm polyamide sheets the dansyltaurine is clearly separated as a circumscript spot without fluorescing contaminations. But commercial [14C]dansyl chloride preparations regularly contain radioactive impurities which do not fluoresce and therefore can only be detected by autoradiography. Since one of these labelled impurities migrates with the usual solvents together with [14C]dansyltaurine during chromatography a method is described for a chromatographic separation of [14C]dansyltaurine from these impurities. As internal standards for preparing calibration curves, alpha-phenylglycine and sarcosine are used. gamma-Aminobutyric acid as well as glutamic acid can react with dansyl chloride to form the corresponding lactams. These lactam rings can be converted with ammonia into the corresponding amides (dansylglutamine and dansyl-gamma-aminobutyramide).

Autoradiography↗
PubMed1975

Monoamine oxidase activity in Helix pomatia.

The distribution and characterization of MAO in various tissues of the snail were analyzed. Only low amounts of the enzyme exist in the different tissues and data suggest that there is more than one type of MAO.

Animals↗
PubMed1975

Dopamine metabolism in characterised neurones of Planorbis corneus.

A sensitive chromatographic procedure was used to study the metabolism of [14C]tyrosine, [3H]DOPA and [3H]dopamine in 3 defined cell-types situated in the nervous system of Planorbis corneus. One of the cell-types contains dopamine (GDC), the other serotonin (GSC) and the other neither amine (GC). The GDCs metabolise [14C]tyrosine to form DOPA and dopamine while the other two cells lack this ability. In contrast, the GDCs and the GSC, but not the GCs, metabolise [3H]DOPA to form dopamine. In addition the GDCs incorporate radioactivity from [3H]DOPA into DOPAC, homovanillic acid and methoxytyramine. After incubation of cells in [3H]dopamine, only the GDCs metabolise it to form DOPAC, homovanillic acid and methoxytyramine. In no instance did the GDCs form significant amounts of noradrenaline from the incorporated radioactive substances. These results, together with data on the amine histochemistry of the individual cell-types following pretretment of animals with drugs known to affect specific enzymes in the synthesis of amine transmitter substances, clearly demonstrate that the GDCs alone have the enzymes requisite for the biosynthesis and catabolism of dopamine, but not noradrenaline.

Animals↗