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M M NACHLAS

Publications and source records attributed to M M NACHLAS.

At least 37 records · Page 2Linked to original sources
PubMed1960

Improvement in the histochemical localization of leucine aminopeptidase with a new substrate, L-leucyl-4-methoxy-2-naphthylamide.

A new method for the histochemical demonstration of leucine aminopeptidase in fresh frozen sections was developed with the substrate L-leucyl-4-methoxy-2-naphthylamide. The superior enzyme localization is due to the more rapid rate of coupling of the hydrolysis product, 4-methoxy-2-naphthylamine as compared to 2-naphthylamine itself, and to the low lipid solubility and high substantivity for protein of the copper chelate of the dye formed on coupling with tetrazotized diorthoanisidine. A comparison of the old and the new method is illustrated, and a description is given of the localization of leucine aminopeptidase in the tissues of the rat and man.

2-Naphthylamine↗
PubMed1959

Further studies on the lyo and desmo components of several hydrolytic enzymes and their histochemical significance.

This report describes additional studies of the lyo and desmo components of esterase, alkaline phosphatase, acid phosphatase, leucine aminopeptidase, and beta-glucuronidase. The techniques used have already been reported (7). Enzyme diffusion occurs to different degrees in different fixatives, and varies somewhat with each enzyme. Loss of enzymatic activity during fixation occurs as a result of both inactivation due to the chemical reaction of the fixative with the enzymic protein, and diffusion of the lyo component into the fixative. The amount of diffusion into formalin can be reduced by the addition of salts, sucrose, or methocel. The pH of the aqueous medium significantly influences the removal of the lyo fraction from the tissue section. A striking similarity can be noted in the proportions of each fraction of enzyme present in the kidney of the rat, dog, and man. The procedure of fixation and paraffin embedding of tissue blocks does not wholly prevent the diffusion of the lyo component from the tissue sections when they are subsequently immersed in the aqueous incubation medium.

Acid Phosphatase↗
PubMed1958

The histochemical localization of triphosphopyridine nucleotide diaphorase.

A histochemical method is described for the localization of triphosphopyridine nucleotide diaphorase using a recently synthesized tetrazolium salt (Nitro-BT). By virtue of the favorable histochemical properties of this reagent, it has been possible to demonstrate that whereas DPN diaphorase is usually restricted to the mitochondria, the TPN diaphorase activity of corresponding cells was distributed throughout the cytoplasm in granules too fine to be considered mitochondria. Furthermore, although the diaphorase alone is responsible for the passage of electrons from TPNH to the tetrazole, it has been found that sites of activity of different TPN-linked dehydrogenases can be visualized in tissue sections, and characteristic loci for each enzyme may be observed. For example, whereas TPN diaphorase and isocitric dehydrogenase have an extensive distribution in the kidney cortex, 6-phosphogluconic dehydrogenase is limited to the cells of the macula densa.

Biological Phenomena↗
PubMed1958

A histochemical method for the demonstration of diphosphopyridine nucleotide diaphorase.

The present investigation concerning the histochemical demonstration of DPN diaphorase follows the development of a new reagent, Nitro-BT, which has already been used successfully for the cytochemical localization of the succinic dehydrogenase system. The most consistently favorable results were obtained with the lactate-lactic dehydrogenase system buffered at pH 7.4. Using sections of rat kidney and stomach, it was found that the intensity of stain was optimal after 15 minutes incubation at 37 degrees C., conducted aerobically. By appropriate variations in the substrate mixture it was possible to selectively demonstrate the histochemical distribution of certain DPN-linked dehydrogenases in addition to DPN diaphorase. This was made possible by the special distribution of some of these dehydrogenases which distinguished them from one another. Of the dehydrogenases studied the distribution pattern of beta-hydroxybutyric dehydrogenase was the most singular. In the gastric mucosa beta-hydroxybutyric dehydrogenase was restricted to the cells of the mucous lining epithelium and the gland necks; and in the kidney the enzyme was limited to the cells of the proximal convoluted tubule and thick limbs of Henle's loop. In contrast, lactic dehydrogenase like DPN diaphorase was demonstrable in almost all cytologic elements of both the stomach and the kidney.

Dihydrolipoamide Dehydrogenase↗
PubMed1956

Quantitative estimation of lyo- and desmoenzymes in tissue sections with and without fixation.

1. Tissue sections eight microns thick were exposed to various experimental conditions used in histochemistry, and the effect upon the activities of esterase, the phosphatases, leucine aminopeptidase, beta-glucuronidase, and arylsulfatase was determined colorimetrically. 2. Significant differences were found in the amounts of the lyo and desmo fractions of these enzymes. The desmo components were found to be for esterase, alkaline phosphatase, leucine aminopeptidase, acid phosphatase, beta-glucuronidase, and arylsulfatase, (1/3), 2/3, 2/3, (1/2), (1/8), and (1/8) of the total enzymatic activity respectively. 3. Variations in the time and in the temperature at which diffusion was studied and of the pH and salt concentration of the solution into which the sections were placed, resulted in differences in the amount of enzymatic activity which remained in the tissue section. Some enzyme loss by diffusion was noted even after fixation of the tissue section. 4. The significance of the findings with respect to some of the concepts of localization of enzymes in tissue sections was discussed.

Acid Phosphatase↗