Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02003 (NBT)
 1,323 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Histochemical studies of human guanase (guanine deaminase) have seldom been undertaken, in part because of technical difficulties which result in heavy background staining. We reported a modified procedure for histochemical demonstration of guanase in human tissues involving hydrolytic deamination of the substrate guanine to xanthine via guanase, and then oxidation of xanthine to uric acid, with concomitant reduction of nitrotetrazolium blue (NBT). In this report, we describe a modification of this method for cytochemical demonstration of guanase at the fine structural level using yellow tetrazolium in place of NBT for determination of the intracellular distribution of guanase in human hepatocytes. In the hepatocytes, the reaction products were seen to be concentrated in the nucleus, in mitochondria, cisternae of the smooth and/or rough-surfaced endoplasmic reticulum, and lysosomes. The precise locations of the reaction product in the cisternae of the nuclear envelope, chromosomes, and nucleus could not be determined. However, the reaction products in the mitochondria were clearly seen to be located in the spaces of cristae. This information of the intracellular distribution of guanase in normal hepatocytes will be useful in determining the physiological role of this enzyme and in further studies on diseased hepatocytes including those in non-A non-B hepatitis.
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PMID:Cytochemical demonstration of guanase in human liver using yellow tetrazolium. 313 23

The origin of human Factor XIII subunit A (FXIII A) has been a subject of intense speculation and investigation during the last decade. The major question under dispute is whether hepatocytes can produce this clotting factor. Experimental evidence obtained by FXIII A phenotype analysis in bone marrow transplant patients clearly identified hemopoietic cells (monocytes/macrophages and/or megakaryocytes/ platelets) as a source of FXIII A, and also showed that additional extra-hemopoietic site(s) of synthesis also exist. The liver has been suggested as a possible extra-hemopoietic source of plasma FXIII A, but the cells responsible for synthesizing FXIII A were not identified yet. Our present study was designed to determine the cellular distribution of both FXIII A and its encoding mRNA in human liver samples by using light- and electron-microscopic immuno-morphological and in situ hybridization techniques. In paraformaldehyde/glutaraldehyde (PA/GA) fixed, araldite-embedded semithin sections that were immunostained by an ABC/DAB based postembedding immunocytochemical method, FXIII A could be detected in Kupffer cells, connective tissue histiocytes and hepatocytes. Immunoreactive hepatocytes were observed almost exclusively around the venae centrales. By using postembedding immunogold labeling, FXIII A could be electron-microscopically visualized in these hepatocytes in the immediate vicinity of the lamellae of the endoplasmic reticulum. By in situ hybridization using a mixture of five 32-40mer biotinylated oligonucleotides (ONs) to mRNA regions encoded by exons VI, XI and XV and a labeling system containing streptavidin conjugated with alkaline phosphatase/BCIP/NBT, the message for FXIII A could be detected in the same cell types. These results show that in human liver three different types of cells can synthesize FXIII A, but the extent of their contribution to the plasma FXIII A level will require further studies.
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PMID:Three different cell types can synthesize factor XIII subunit A in the human liver. 881 55