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Biomedical subjects

L Z Xu

Publications and source records attributed to L Z Xu.

At least 55 records · Page 3Linked to original sources
PubMed1990

Expression of mammalian liver glycolytic/gluconeogenic enzymes in Escherichia coli: recovery of active enzyme is strain and temperature dependent.

A number of mammalian enzymes have been expressed in Escherichia coli using the T7 RNA polymerase system, but the production of large amounts of these proteins has been limited by the low percentage of active enzyme that is found in the soluble fraction. In this report the effect of induction temperature was tested on the recovery of four rat liver enzymes, 6-phosphofructo-2-kinase/fructose-2,6- bisphosphatase, fructose-2,6-bisphosphatase, glucokinase, and fructose-1,6-bisphosphatase. We also tested the effect using a host cell strain that contains a plasmid encoding T7 lysozyme, an inhibitor of T7 RNA polymerase. Large amounts of the first three enzymes accumulated in the cells after 4 h of induction at 37 degrees C, but only about 1-2% of the total expressed proteins were recovered in a soluble, active form. When the induction was carried out at 22 degrees C for 48 h with the pLysS strain, 20- to 30-fold higher amounts of the active expressed enzymes were recovered in the soluble fraction, even though the total accumulation and the rate of synthesis of these proteins were reduced. The optimal concentration of isopropyl-1-thio-beta-D-galactopyranoside required for induction was the same at both temperatures. On the other hand, the recovery of active fructose-1,6-bisphosphatase, a heat-stable enzyme, was 66% at 37 degrees C and was essentially unchanged at an induction temperature of 22 degrees C. Lowered induction temperature would appear to be of utility for enhanced recovery of active mammalian enzymes which are insoluble in E. coli cytosol at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[The anchoring of newly synthesized adenovirus DNA to the nuclear matrix].

After adenovirus infected HeLa cells were pulse labeled and pulse-chase labeled with 3H-thymidine, the nuclear matrix and DNA remaining tightly bound to the matrix were obtained by sequential cell fractionation. Measuring the radioactivity of labeled DNA indicated that newly synthesized viral DNA specifically attach to the nuclear matrix and the amount of binding DNA is in direct proportion to the viral DNA replication activity: then the DNA gradually detach from the matrix and are involved in viral assembly. Electron microscopic autoradiography of the extracted cells showed the virion and viral DNA associated with the nuclear matrix, and thus further confirmed the anchoring of newly synthesized viral DNA to the nuclear matrix.

Adenoviruses, Human↗
PubMed1989

Gastric xanthelasma.

Gastric xanthelasmas are macroscopically well demarcated yellow or yellow-white plaques, and microscopically composed of typical foamy macrophages. Of 3870 patients who underwent upper gastrointestinal panendoscopic examinations, 30 (0.8%) were found to have gastric xanthelasma. A moderate predominance of males over females (M:F = 3.3:1) was noted. The age ranged between 21 and 69 years (mean 46.7). Frequency peaked in those from 40 to 60 years of age (53.3%). Single lesions were found in 26 patients and multiple in 4, with diameters of 1-6 mm, nearly 66.7% of which were 2-3 mm. Gastric xanthelasmas are most frequently found in the antrum (67.8%), especially along the lesser curvature. Associated chronic gastritis in the xanthelasma surrounding mucosa was found in the 30 patients and intestinal metaplasia in 4 (13.3%). The cause of gastric xanthelasma is unknown, but chronic gastritis may be the most plausible etiologic factor.

Adult↗
PubMed1989

Establishment of a group of murine leukemic cell lines and investigation of their biological characteristics.

An in vitro-vivo technique for establishment of cell lines on murine leukemia has been developed. Using this method, suppressive T lymphoblastic leukemia L7811-85, L7212-85, non-T, non-B lymphocytic leukemia L1210-86, B lymphocytic leukemia P 388-86 and Friend erythroleukemia FLCL cell lines have been established. Incidence of leukemia with these cell lines was 100%. Along with the increase of generations of cell lines, cell growth accelerated, generation time shortened and cloning efficiencies rose. A following up electron microscopic observation on L7811-85 and L7212-85 showed that the virus particles were "A" particles in original cells. When they became cell lines in vitro, virus particles increased and transformed into typical "C" particles with budding. An inhibitory activity relevant to leukemic cells on proliferation of leukemic cells has been observed in the supernatant of L7811-85 medium and was regarded as an "autocrine".

Animals↗
PubMed1987

[Pattern recognition on the trace element spectrum in gastric cancer and peptic ulcer].

The trace element spectrum of gastric tissue and whole blood specimens from gastric cancer and peptic ulcer patients was recognized with pattern recognition technique in order to obtain the chemical information of gastric cancer. Thirty specimens were obtained from cancer patients in each of the 58 gastric tissues and 54 whole blood specimens. Five pathological types were divided into two groups: peptic ulcer and dysplasia as the ulcer group; well-differentiated, undifferentiated and mucinous carcinoma as the cancer group. The accuracy of recognizing the several spectra was 90%: nine trace element spectra (Cu, Zn, Ni, Co, Cr, Cd, Mn, Fe and Mg) for the tissue specimens from the cancer and ulcer groups; six (Cu, Zn, Mn, Co, Cr and Cd) for dysplasia and well-differentiated adenocarcinoma tissues; five (Cu, Ni, Cr, Cd and Fe) for the whole blood specimens from these two groups and six (Cu, Zn, Cr, Cd, Fe and Ni) for the whole blood specimens from dysplasia and peptic ulcer (including 10 normal individuals). The data were treated by non-linear mapping method and calculated by TRS-80 III type microcomputer.

Adenocarcinoma↗
PubMed1987

[Transplantation model of human lung oat cell carcinoma in nude mice].

A human lung oat cell carcinoma from a surgical specimen was successfully transplanted into nude mice and has been maintained for over four years through 14 passages. This transplanted tumor had a long latent period of more than one month, slowly growing in the initial inoculation and the following passages. The interval between two passages was about four months. 5 months after the inoculation, the transplanted tumor in nude mice grew to 2 cm in diameter. It was demonstrated that the transplanted tumor possessed the human isoenzyme pattern and human chromosome karyotype. The original human tumor and its transplanted counterparts in the nude mice were strikingly similar by histopathology. Besides, specific neuro-secretory granules in cytoplasm of the transplanted tumor were observed under transmission electron microscope.

Aged↗
PubMed1986

Endoscopic diagnosis and management of Ascaris-induced acute pancreatitis.

We report on 14 cases of endoscopically diagnosed and managed Ascaris-induced acute pancreatitis. Fifteen live adult ascarides were found in fourteen patients. Under direct endoscopic observation, all roundworms impacted in the papilla of Vater were grasped by the biopsy forceps and removed. After the endoscopic procedure, all the symptoms subsided, and laboratory data gradually returned to normal levels. We believe that this method is a safe procedure without complications or risk.

Acute Disease↗
PubMed1984

Phenotypic expression of non-Hodgkin's lymphomas in China.

Monoclonal antibodies were used to label malignant lymphomas obtained from 57 patients. On the basis of morphologic criteria, 18 lymphomas were the B-cell type, 10 were the T-cell type, and 6 were histiocytic; for 23 the type could not be determined. After monoclonal antibody labeling, 18 lymphomas of B-cell lineage were confirmed, 16 of the T-cell type were demonstrated, 6 were true histiocytic, and 17 were the null cell (non-T, non-B) type. Of the 16 lymphomas of T-cell lineage, 6 were lymphoblastic and 10 were the peripheral type. The percentages of cell types in the non-Hodgkin's lymphomas were as follows: B-cell, 31.5%; T-cell, 28%; null cell, 29%; and histiocytic, 10%. Of the 16 lymphomas of T-cell origin, 15 belonged to helper T-cell subsets (Leu1+, Leu4+, and Leu3a+), and the la marker was positive in all 16. Of the 18 B-cell lymphomas, 14 were kappa-positive and 4 were lambda-positive. Eleven were both B1- and kappa-positive, and 1 was kappa-positive but B1-negative. In the 4 cases that were lambda-positive, 2 were both lambda- and B1-positive. The results indicate that Leu4, Leu2a, Leu3a, and B1 are the most important markers to differentiate T-cell and B-cell lymphomas for pathologic classification. The findings also show a higher percentage of T-cell neoplasm in China as compared to that in Western countries.

Adult↗