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Y Xu

Publications and source records attributed to Y Xu.

At least 1,279 records · Page 71Linked to original sources
PubMed1988

Cytochemical demonstration of guanase in human liver using yellow tetrazolium.

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.

Aminohydrolases↗
PubMed1988

[Amplification and rearrangement of proto-oncogene c-abl in human leukemia cells].

DNA of peripheral blood or bone marrow leukocytes from 8 normal subjects, 7 cases of acute lymphocytic leukemia (ALL), 2 of acute myelogenous leukemia (AML) and 1 of chronic myelogenous leukemia (CML), having been digested by endonuclease Eco RI or Pst I separately, was hybridized with the probes of 3' fragment (Pst I/Hind III) or 5' fragment (Hinc II/Pst I) of Abelson murine leukemia virus (A-MuLV) oncogene v-abl. The proto-oncogene c-abl, which is homologous to v-abl, was found amplified in 4 ALL, 1 CML and 1 AML. In one of these 4 ALL, c-abl was amplified even over 100 times. A new c-abl BamH I fragment with 6.7 kilobase pairs (kb) in length was observed in 2 ALL and 1 CML out of these 6 cases with amplification, but none of this fragment was found in the normal subjects or other leukemia patients. These 3 patients with the presence of 6.7 kb fragment were high risk ones and 2 of them had died, suggesting that 6.7 kb fragment be the index of poor prognosis. The amplification and rearrangement of c-abl imply the activation of proto-oncogene in leukemogenesis.

Gene Amplification↗
PubMed1987

Stabilized ubisemiquinone in reconstituted succinate ubiquinone reductase.

QP-S, a ubiquinone (Q) protein, accepts electrons from succinate through succinate dehydrogenase (SDH). A new method has produced a preparation of QP-S which has a different amino acid composition and SDS gel electrophoretic pattern from that of the old preparation (Biochemistry 19, 3579-3585 (1980)). The new preparation contains less than 1 nmol heme/mg protein; the activity of the preparation was not proportional to its heme content. A thenoyltrifluoroacetone sensitive free radical signal was detected by EPR spectroscopy in succinate-Q reductase reconstituted from this QP-S and SDH; the characteristics of this species identify it as ubisemiquinone. At pH 7.4, the Em of the two electron step was about 70 mV with E1 = 5 mV and E2 = 125 mV. The properties of the radical differed slightly from those of "Qs" radical in more intact preparations (e.g. submitochondrial particles). The present is the simplest system in which such a succinate reducible ubisemiquinone free radical has been demonstrated.

Coenzymes↗
PubMed1987

Effects of Temperature on H Secretion and Uptake by Excised Flexor Cells during Dark-Induced Closure of Samanea Leaflets.

Previous studies reveal that dark-induced closure of Samanea leaflets is accompanied by H(+) secretion from flexor motor cells. We now report that flexor tissue excised in the light, incubated in a weakly buffered bathing solution, and then darkened at different temperatures (18 degrees C-30 degrees C) acidified the medium (indicating net H(+) efflux) at all temperatures tested, but most rapidly at the highest temperature. However, pH changes reversed direction after 20 to 70 minutes; the lower the temperature, the later pH reversal occurred, and the lower the pH at reversal and after 45 minutes. These data provide a basis for the previously reported promotive effect of low temperature on dark-induced leaflet closure, assuming net H(+) and K(+) fluxes are opposite in direction. Net H(+) efflux at all temperatures tested was greater when the impermeant molecule iminodiacetate replaced small permeant anions in the bathing solution, suggesting that H(+) uptake is coupled to anion uptake, probably via a H(+)/anion symport system. When permeant anions were deficient, the amount of malate in the tissue increased, presumably by new synthesis. Malate synthesis would substitute for H(+)/anion uptake in charge balance and in providing H(+) for cytoplasmic pH regulation.

Journal Article↗
PubMed1987

Injection of copper powder into epididymides via vas deferens on male fertility.

In adult SD rats, a single injection of silicon rubber containing 10mg metallic copper particles via vas deferens into each cauda epididymis could induce male infertility. Although the copper contact in the cauda epididymides of treated rats was significantly higher than that in the controls, the serum copper concentration did not rise significantly, while the histology of important organs and blood testosterone levels did not change. Treated animals gained weight as fast as the controls, suggesting a low systemic toxicity of this procedure. In 5 of the 8 treated rats, fertility was restored 16 weeks after treatment with normal testicular copper concentration and testicular histology. In 3, fertility was not restored within 16 weeks and the testicular copper concentration was significantly higher than in the controls. Only in these 3 rats were different degrees of damage noted in the seminiferous epithelium and it is anticipated that the fertility will be restored after a certain period of time since sperm production was unaffected. The delayed recovery of fertility in these rats is attributed to the diffusion of copper ions into the testis. It would appear that the injection of silicon rubber containing copper particles via the vas deferens to the cauda epididymides is a potential approach for male contraception.

Animals, Laboratory↗
PubMed1987

Establishment of a human/Chinese hamster hybrid clone panel.

Combined with the chromosome G-banding, followed by Giemsa-11 techniques and chromosomal marker isozyme analysis, 6 out of 200 subclones have been analyzed in detail. A primary hybrid clone panel has been established, which can be used to map genes on chromosomes 4, 5, 8, 12, 20 and 22. Since the panel contains deleted chromosomes 4, 5, 8 and 12, genes on these chromosomes can be mapped regionally.

Animals↗
PubMed1987

Regional assignment of human alcohol dehydrogenase (ADH) gene to 4pter----4q21.

The hybrid clone FD1 constructed by fusion of Chinese hamster cell line Wg3-h with human lymphocyte was irradiated with X-ray. Fourteen survival clones were isolated and 3 of them, F5B, F52B, F61A were analyzed in detail by cytogenetic and biochemical methods. The results of chromosome G-banding followed by Giemsa-11 differential staining show that there exists a deleted human chromosome 4 in all of the three hybrids. This deletion of human chromosome 4 in F61A is 4pter----4q21. The results of isozyme analysis of phosphoglucomutase-2 (PGM2) which is located on 4p14----4q21 confirm our cytogenetic conclusion. We used polyacrylamide gel electrophoresis to study the alcohol dehydrogenase (ADH) in human lymphocyte, Wg3-h and hybrid clones. Their electrophoretic pattern showed that human ADH isozyme did express, in the peripheral blood lymphocyte, hybrids F5B, F52B, F61A and FD1. According to these results, we suggest that one of the Class I ADH structural genes is located on the human chromosome 4pter----4q21. Recently, McKusick reported that Class I ADH gene cluster had been assigned to chromosome 4q21----4qter. Considering this fact, we suggest that Class I ADH gene might be assigned to chromosome 4q21 or on its vicinity.

Alcohol Dehydrogenase↗