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N Zimmermann

Publications and source records attributed to N Zimmermann.

83 records · Page 5Linked to original sources
PubMed1985

Light microscopical localization of enzymes by means of cerium-based methods. II. A new cerium-lead-technique for alkaline phosphatase.

The use of cerium ions as a primary capture reagent in phosphatase histochemistry on the light and the electron microscopic level is a progress in the field of enzyme localization. Many influences of other captures (as of lead ions), e.g. enzyme inhibition, diffusion and other artefacts, are restricted when cerium-based methods are used. But the broader use of cerium is difficult, because cerium ions are at alkaline pH converted to the insoluble cerium hydroxide, which intensively precipitates in the incubation medium. This is an important disadvantage for a successful histochemical detection of alkaline phosphatase. The aim of this paper is to describe a new cerium-based method for the light microscopical detection of alkaline phosphatase, which is free from all these above mentioned problems. It is proposed a collidine buffer-sucrose containing medium, which holds cerium ions at pH = 9.0 in solution. The histochemical results of this method are excellent. The method is compared with a strontium based technique, the coupling azo dye technique for alkaline phosphatase as well as with in vitro and histochemical experiments with several chelator agents. The cerium-based collidine-sucrose technique is superior to all other procedures tested here and is recommended for a broader use.

Alkaline Phosphatase↗
PubMed1985

Light microscopical localization of enzymes by means of cerium-based methods. I. Detection of acid phosphatase by a new cerium-lead-technique (Ce-Pb-method).

Cerium-III-ions are more and more used as capturing reagent and opaque marker for the electron microscopic localization of a number of H2O2-generating enzymes as well as phosphohydrolases. Contrary to its advantages over common lead methods in the histochemical detection of enzyme activities at the electron microscopic level, cerium-based methods proved to be a failure for light microscopic investigations. Therefore, our cerium-based method for the ultrahistochemical detection of acid phosphatase was developed for further observations at the light microscopic level. The principle of that new Ce-Pb-method is the conversion of light microscopic not visible cerium phosphate into lead phosphate by the secondary capture reagent alkaline lead citrate. Finally, the lead phosphate can be visualized as lead sulfide in the section. The Ce-Pb-method in its finally proposed manner was compared with a common lead method and showed a range of advantages. Because of that fact, the new Ce-Pb-method is recommended for a broader use in histochemistry, e.g. for the light microscopic enzyme investigation parallel to ultrahistochemical preparations.

Acid Phosphatase↗
PubMed1985

Light microscopical localization of enzymes by means of cerium-based methods. III. Visualization techniques for cerium phosphate.

Cerium-based methods are more and more used for the electron microscopic localization of phosphohydrolases. By means of the earlier described Ce-Pb-technique, it is possible to localize these enzymes on the light microscopical level. The final product of this reaction is lead sulfide. In addition to this technique, other visualization methods for the light microscopically not visible cerium phosphate are proposed. 3 successful techniques are described in the report: The cerium perhydroxide reaction. By means of H2O2 cerium phosphate is converted into cerium perhydroxide which has an orange-yellowish colour. The manganese dioxide reaction with the conversion of cerium phosphate into cerium oxalate, which is able to reduce permanganate into the hardly soluble brown coloured manganese dioxide. A silver technique (Ce-Pb-AgS-method), which is characterized by the conversion of cerium phosphate into lead phosphate and in a second step to lead sulfide. At the active sites of the lead sulfide, the reduction of silver ions takes place. The reduced silver is converted in a final step into silver sulfide. The enzyme activity is represented by a brown or black coloured staining.

Acid Phosphatase↗
PubMed1985

The rat liver foci bioassay: II. Investigations on the dose-dependent induction of ATPase-deficient foci by vinyl chloride at very low doses.

In order to study the dose-dependence of the genotoxic effect of vinyl chloride (VC) hepatocellular ATPase-deficient foci were evaluated after subchronic exposure of newborn rats. Wistar rats were exposed from day 1 after birth over 10 weeks to 10, 40, 70, 150, 500 and 2000 p.p.m. VC (8 h/day; 5 days/week). One week after cessation of exposure hepatic ATPase-deficient foci were quantitated. For a subsequent investigation lower dose range groups of female and male Wistar and Sprague-Dawley rats were exposed (8 h/day; 5 days/week) to 2.5, 5, 10, 20, 40 and 80 p.p.m. VC. Exposure started at day 3 of life and lasted for 3 weeks. After cessation of exposure the animals were maintained for 10 weeks without further treatment until ATPase-deficient foci were quantitated. Both sets of experiments revealed a straight linear relationship between the dose of VC and the % foci area induced. Within the dose range investigated, no obvious threshold for the induction of pre-neoplastic foci by VC was observed.

Adenosine Triphosphatases↗
PubMed1985

Evidence for erythrocyte-microvesiculation in vivo.

During physiologic aging, erythrocytes (RBC) mainly loose membrane as shown by biochemical investigations. The most likely reason for a such loss would be the pinch off of RBC-microvesicles. The detection of RBC-microvesicles generated in vivo is rendered more difficult because of the relatively small amount of vesiculation processes under physiologic conditions accompanied by the fast phagocytosis of RBC-microvesicles in the reticulo-histiocytic system. The latter has been shown after the intravenous injection of heat-induced RBC-microvesicles. Investigations of spleens resulted in the case of PHZ-treatment, up till now in a clear demonstration of RBC-microvesicles. The result of microvesiculation in the PHZ-model led to the conclusion, that also rigid, naturally aged RBC could pinch off microvesicles in physiologic narrows of the blood flow like in the spleen.

Animals↗
PubMed1981

A polyacrylamide gel method for the cytochemical demonstration of glucose-6-phosphate dehydrogenase activity in mouse sperm.

Solubility and low activity of glucose-6-phosphate dehydrogenase let both the aqueous and agarose gel cytochemical incubation techniques fail in mouse sperm. By means of a polyacrylamide gel medium G6PDH was constantly demonstrated in the midpieces of sperm cells prefixed with cold acetone. Although this technique prevented the dislocation of the enzyme, diffusion artifacts due to delayed formation of formazan may occur from sites of high dehydrogenase activity, e.g., epididymal epithelium encountered in sperm smears.

Acrylic Resins↗
PubMed1977

A new technique in avian semen evaluation.

Modification of a technique used in human fertility is presented and shown to be a simple, inexpensive and quantitative method for estimating the subsequent fertility of a semen sample.

Animals↗