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H Wenzel

Publications and source records attributed to H Wenzel.

49 records · Page 3Linked to original sources
PubMed1983

[Histoprognostic factors of non-infiltrating urothelial tumors of the bladder].

The authors reported a pathology and clinical study about 215 cases of non infiltrating transitional cell carcinoma of the bladder. During the successive treatments of these lesions 475 specimens were collected. 5 tumours characteristics were analyzed: size of the tumour, multiplicity, microscopic structure, grade, mitotic index. The average time of supervision was 39,6 months. 75% of the patients presented a tumour recurrence over the 5 years period and in 3% of the cases deaths were directly attributable to the tumour. Multiplicity and especially mitotic index are the only tumour characteristics which correlated well with the likelihood of new tumour occurrence. The grade and the mitotic index are the best criteria to assess the risk of recurrence as an infiltrating carcinoma. The distribution of tumour characteristics shows that this type of lesion roughly keeps the same pathological pattern during recurrences. Nevertheless there exists a cellular dedifferentiation trend as well as an increase of mitotic index.

Adult↗
PubMed1978

Proton NMR relaxation study of the binding of pyridine and 1-methylimidazole to some ferriporphyrins and to metmyoglobin.

Proton spin-lattice relaxation times of pyridine and 1-methylimidazole complexed on Fe(III)protoporphyrin IX dimethyl ester, Fe(III)tetraphenylporphyrin in chloroform and on metmyoglobin in 2H2O have been measured. Caused by chemical exchange of the ligand molecules into the bulk solvent phase, the decay of their MZ-magnetization is given by a superposition of two exponentials from which the mean lifetime of the complexed species can be determined. This method offers the possibility to study exchange kinetics of ligand molecules from a well defined molecular configuration. The present data are compared with the results from linewidth measurements of the bulk phase molecules. From both sets of parameters a detailed picture of the ligand exchange can be gained, particularly if spin transition of the paramagnetic organic metal complex occurs, as is the case for some ferriporphyrins. For metmyoglobin, the NMR result is compared with relaxation times extracted from temperature jump experiments under similar conditions.

Calorimetry↗
PubMed1977

Binding studies of a spin-labelled oxidized coenzyme to bovine-liver glutamate dehydrogenase.

NAD+ with a nitroxide piperidine ring linked to the NH2 group of the adenine possesses full coenzymatic activity with glutamate dehydrogenase. Electron spin resonance spectra in the presence of glutamate dehydrogenase show mixtures of free and strongly immobilized spin-label. Binding studies in phosphate buffer demonstrate: (a) weak binary binding to the enzyme with a dissociation constant in the order of 2mM;(b) an indication for negative cooperativity or different sites for binding to enzyme-2-oxoglutarate, with dissociation constants in the order of 20--250muM; (c) similar but much weaker binding to enzyme-2-oxoglutarate-ADP; (d) a strong positive cooperative binding to enzyme-2-oxoglutarate-GTP, dependent on the enzyme concentration. Binding of phosphate to the enzyme with a Kd of about 20 mM or binding of pyrophosphate or tripolyphosphate with a Dd of about 2.5 mM enhances the binding of spin-labelled NAD+ in the presence of 2-oxoglutarate. There is evidence that the binding sites for these phosphates coincide with phosphate binding subsites of GTP.

Animals↗
PubMed1977

[Gas-chromatographic determination of insecticidal chlorinated hydrocarbons using the GCHF 18.3-6 gas chromatograph with an attached electron detector].

The authors describe the gas chromatographic determination of residues of insecticidal chlorinated hydrocarbons in foods by means of the GCHF 18.3-6 gas chromatograph with electron attachment detector of the VEB Chromatron Berlin which is most frequently available in the GDR for routine work. Furthermore, the authors deal with possibilities of identifying and confirming residues of chlorinated hydrocarbons with the aid of chemical reactions.

Aldrin↗
PubMed1976

Spin-labelled AMP - an activator of phosphorylase.

1. A spin-labelled AMP derivative and its diamagnetic analogue activate phosphorylase b in the same way, but do not activate phosphorylase a. 2. The electron-spin-resonance spectra of the spin-labelled AMP derivative bound to phosphorylase b and a have "powderlike" characteristics indicating that the spin label is immobilised on the protein. From changes in the electron-spin-resonance spectrum of spin-labelled AMP as phosphorylase b or a is added, the dissociation constants were calculated. 3. The interactions of spin-labelled AMP and the diamagnetic analogue with phosphorylase b and a have been monitored by observing changes in the spectral properties of fluorescent and spin-label probes covalently attached to the enzyme. 4. The dissociation constants of spin-labelled AMP and phosphorylase b or a are 175 +/- 25 muM and 15 +/- 5 muM respectively. Similar dissociation constants are obtained for the diamagnetic analogue. The effect of these AMP derivatives on the covalently attached probe groups and on phosphorylase activity is compared to the effect of AMP and IMP.

Adenosine Monophosphate↗
PubMed1976

The influence of various drugs on artificial oedema of the rat's bladder.

An experimental oedema of the bladder wall was produced by electric coagulation current in 130 rats. The amount of oedema was calculated by determination of the difference between the weight of the freshly excised wet bladder and that after drying to constant weight. Thus, oedema of a fairly constant and reproducible amount could be produced. The effect of three different drugs on such oedema was tested (Na-Aescinat, 6-methylprednisolone, alpha-Chymotrase). After the application of Na-Aescinat and 6-methylprednisolone no significant oedema could be measured after 48 h. Using alpha-Chymotrase, there was no measurable influence on the oedema.

Animals↗