Search PubMed⌕ Search

Biomedical subjects

Z Zeng

Publications and source records attributed to Z Zeng.

At least 37 records · Page 2Linked to original sources
PubMed2001

Supercooling capacity of Urophora affinis and U. quadrifasciata (Diptera: Tephritidae) on spotted knapweed: comparisons among plants, sites, time of season, and gall densities.

Larval supercooling points of Urophora affinis Frauenfeld and U. quadrifasciata (Meigen) were compared among plants, six research sites in western Montana, four fall/winter time periods, and among gall densities. These two tephritid fly species are introduced biological control agents of spotted knapweed, Centaurea maculosa Lamarck, and diffuse knapweed, Centaurea diffusa Lamarck. Few differences in larval supercooling points for U. affinis and U. quadrifasciata were found among plants, and where differences were found, they were not consistent across fall/winter time periods. Significant differences in larval supercooling points were found among sites and across fall/winter time periods. No relationship was found between larval supercooling points and site elevation. Larval supercooling points of both U. affinis and U. quadrifasciata showed no relationship with the density of Urophora galls within spotted knapweed capitula. Mean larval supercooling points of U. affinis were consistently lower than those of U. quadrifasciata across sites and fall/winter time periods. In conclusion, temporal differences in temperature over the fall/winter time periods and microclimatic differences among sites appear to be the most important abiotic factors influencing the supercooling points in U. affinis and U. quadrifasciata.

Journal Article↗
PubMed2001

Role of promoter methylation in increased methionine adenosyltransferase 2A expression in human liver cancer.

Methionine adenosyltransferase (MAT), an essential enzyme that catalyzes the formation of S-adenosylmethionine (SAM), is encoded by two genes, MAT1A (liver-specific) and MAT2A (non-liver-specific). We showed a switch from MAT1A to MAT2A expression in human liver cancer, which facilitates cancer cell growth. The present work examined the role of methylation in MAT2A transcriptional regulation. We found that the human MAT2A promoter is hypomethylated in hepatocellular carcinoma, in which the gene is upregulated transcriptionally, but hypermethylated in normal liver, in which the gene is minimally expressed. Luciferase activities driven by in vitro methylated MAT2A promoter constructs were 75-95% lower than activities driven by unmethylated constructs. SAM treatment of Hep G2 cells reduced MAT2A endogenous expression by 75%, hypermethylated the MAT2A promoter, and reduced luciferase activities driven by MAT2A promoter constructs by 65-75% while not affecting MAT1A's promoter activity. Treatment of adult rat and human hepatocytes with trichostatin A, an inhibitor of histone deacetylase, upregulated MAT2A expression by more than fourfold. Collectively, these results suggest that MAT2A expression is regulated by promoter methylation and histone acetylation.

Animals↗
PubMed2001

Expression of the cysteinyl leukotriene 1 receptor in normal human lung and peripheral blood leukocytes.

The cysteinyl leukotrienes (CysLTs) are important mediators of human asthma. Pharmacologic and clinical studies show that the CysLTs exert most of their bronchoconstrictive and proinflammatory effects through activation of a putative, 7-transmembrane domain, G-protein-coupled receptor, the CysLT1 receptor. The initial molecular characterization of the CysLT1 receptor showed by in situ hybridization, the presence of CysLT1 receptor messenger RNA (mRNA) in human lung smooth-muscle cells and lung macrophages. We confirmed the results of these in situ hybridization analyses for the CysLT1 receptor, and produced the first immunohistochemical characterization of the CysLT1 receptor protein in human lung. The identification of the CysLT1 receptor in the lung is consistent with the antibronchoconstrictive and antiinflammatory actions of CysLT1 receptor antagonists. We also report the expression of CysLT1 receptor mRNA and protein in most peripheral blood eosinophils and pregranulocytic CD34+ cells, and in subsets of monocytes and B lymphocytes.

Blood↗
PubMed2001

[Effects of the alterations of membrane shear elastic modulus and viscosity on the deformation and orientation of RBCs].

Neuraminidase can partly remove the surface charge of RBCs through a biochemical interaction; thus it can give rise to alterations in the microstructure of membrane, the shear elastic modulus (E) and the viscosity(micron) of membrane. Changing the time of treatment and the dose of neuraminidase and using a new ektacytometry that can separate deformation index DI into orientation index (DI)or and small deformation index (DI)d for RBCs in shear flow field of low viscosity, we measured (DI)d and the half time t0.5 when the DI recovered to half of the maximum in the process of relaxation for every treated sample. (DI)d and t0.5 were put respectively into the RBC membrane shear elastic modulus formula and the membrane viscosity formula which were put forward by Wen Zong-yao and Yan Zong-yi et al[1]. The rules of the alterations of E and micron were obtained. We also measured DI and (DI)or. It was found that E and micron increased greatly but DI and (DI)or decreased when the dose of neuraminidase and the time of treatment were increased. There was a contrary correlation between them. These data demonstrated that the increase of E and micron weakened the deformability and the ability of orientation of RBCs.

Animals↗
PubMed2001

[Chromosomal aberration analyzed by comparative genomic hybridization in nasopharyngeal carcinoma].

OBJECTIVE: To identify genetic alteration in primary sporadic nasopharyngeal carcinoma(NPC) in Hunan. METHODS: Comparative genomic hybridization was applied to investigate the genomic imbalance in a series of 20 cases of primary nasopharyngeal carcinomas. RESULTS: The common chromosomal alterations included gains of chromosomes 1q, 2, 3q, 7q,8q,12 as well as losses of chromosomes 3p, 9p, 11q, 16q. CONCLUSION: There are multiple regions of chromosomes with copy number changes in NPC. The tumor suppressor genes and oncogenes on these regions may be involved in the development and progress of nasopharyngeal carcinoma.

Chromosome Aberrations↗
PubMed2001

[A pathologic study on the bronchioles and lung tissues in guinea pig asthma models].

OBJECTIVE: To probe further the pathologic changes in peripheral airways and lung tissues and to observe the changes of surfactant in asthma. METHODS: (1) The guinea pig asthma models were established with ovalbumin challenge method. (2) 6 groups were studied: control group, asthma group of day 1, asthma group of day 4, asthma group of day 14, intraperitoneal dexamethasone group, and budesonide inhalation group. (3) The pathologic changes were observed under optical and electron microscope. (4) The total and differential white blood cells counts of bronchoalveolar lavage fluid(BALF) were carried out. (5) The total amounts of phospholipids which represent the levels of pulmonary surfactant were measured with phosphorus detection method. RESULTS: (1) Significant hyperplasia of mucous membrane, basement membrane, and smooth muscle layer of central and peripheral airways in the asthma groups were seen. The alveolar walls were significantly thickened and alveolar spaces diminished (P < 0.001, compared with the control group). Significant infiltration of eosinophils and lymphocytes were observed in airways and lung tissues. (2) The total cell number and the number eosinophils and lymphocytes in BALF were significantly increased in the asthma groups than those in the control group(P < 0.01). Neutrophils were dominant at early stage, but eosinophils and lymphocytes at late stage. (3) The ultrastructural changes of type II alveolar cells in asthma group included cell swelling, evacuation of lamellar bodies and partial cell desquamation. (4) The total amount of phospholipids in BALF was significantly decreased in the asthma groups as compared with that in the control group (P < 0.01). The above changes were significantly improved in both corticosteroid treated groups. CONCLUSION: Widespread and significant inflammation with eosinophilic infiltration exists in the bronchioles and alveolar walls in guinea pig asthma models. Not only there is structural change, but also the function of alveolar cells is influenced. Asthma is a disease involving the whole airway and lung system.

Animals↗
PubMed2001

[Hypermethylation of the calcitonin gene as molecular genetic marker in detecting minimal residual disease of leukemia].

OBJECTIVE: To explore whether detecting minimal residual disease (MRD) of leukemia with hypermethylation of the calcitonin gene as molecular genetic marker of leukemic clone may predict the prognosis. METHODS: Polymerase chain reaction (PCR) in combination with digestion of DNA with HpaII was used to examine the methylation patterns of the calcitonin gene in 29 cases with acute leukemia and 8 cases with transformation of chronic myeloid leukemia. By using PCR, MRD was longitudinally detected in patients who were positive for hypermethylation of the calcitonin gene as molecular genetic marker. RESULTS: Twenty patients with acute leukemia and transformation of chronic myeloid leukemia had MRD after complete remission. Bone marrow relapse occurred soon when MRD persisted or reappeared. It may predict bone marrow relapse two to eleven months earlier. The patients who were negative for MRD early and remained persistently negative may acquire prolonged survival. CONCLUSION: MRD of leukemia may be monitored by using PCR with hypermethylation of the calcitonin gene as molecular genetic marker for leukemic clone. It may prove useful in predicting the prognosis of leukemia.

Adult↗
PubMed2001

[Study of triglyceride distribution aged 35 - 64, and their association with other cardiovascular disease risk factors in 11 provinces].

OBJECTIVE: Study of triglyceride distribution and their association with other major cardiovascular disease risk factors in 11 provinces. METHODS: Twenty-seven thousand and sixteen persons in 11 provinces, aged 35 - 64, were screened for cardiovascular disease risk factors. RESULTS: (1) Results of plasma triglyceride level distribution showed that there was significant difference among 11 province, the highest/lowest ratio was 2.3. (2) Plasma triglyceride level was higher in men than in women (P < 0.001). (3) The prevelance of hypertriglyceridemia was the most frequent type of the dislipidemia. (4) Multiple stepwise regression analysis showed that total cholesterol, high-density lipoprotein cholesterol, body mass index, blood pressure, blood glucose and physical activity, significantly and independently correlated with hypertriglyceridemia prevelance. (5) There existed aggregation of risk factors in hypertriglyceridemia. Seventy-one point zero percent of hypertriglyceridemia had at least one other risk factors in men and 74.4% in women, while it was 53.8% men and 52.2% women of those with non hypertriglyceridemia (P < 0.01). CONCLUSION: Our date indicated that fasting triglycerides were associated with more arteriosclerosis factors and could serve as a marker for several cardiovascular disease risk factors. More patients with hypertriglyceridemia combined with other situation of metabolic syndromes thus might have higher risks.

Adult↗
PubMed2001

[Examination and evaluation of lipopolysaccharide binding protein in serum of patients with chronic hepatitis, severe hepatitis].

OBJECTIVE: To observe the variability of lipopolysaccharide binding protein (LBP) in patients with chronic hepatitis and severe hepatitis. METHODS: Using ELISA the authors detected the serum LBP of 71 patients including 16 with chronic hepatitis, 15 with post hepatitis cirrhosis, 12 with severe hepatitis and 17 healthy controls. RESULTS: The serum LBP of chronic liver disease group was 35 166.25 micrograms/L, which was higher than that of healthy control group (18 590.00 micrograms/L). The serum LBP of chronic hepatitis and cirrhosis patients was higher than that of severe hepatitis cases. These differences were significant. The serum LBP had positive correlation with prothrombin activity (PTA) (r =0.395 8,P <0.01), while it had no significant correlation with serum ALT and total bilirubin levels (r =0.164 5,0.189 4, respectively, P <0.05). CONCLUSIONS: Serum LBP could be used as an index for predicting liver function compensation.

Acute-Phase Proteins↗
PubMed2001

[Surgery of substernal goiter].

OBJECTIVE: To study the surgical approaches and operative techniques for substernal goiter. METHOD: A retrospective study of 27 cases with substernal thyroid nodules was made in our hospital. RESULT: The operations on 27 patients with substernal nodules have been successfully carried out. Among them, 10 were goiters, 9 adenomas, 4 malignancy and 4 were thyroid cancer metastasizing to paratracheal or substernal nodes. Resection via cervical collar incision was adequate in 23 cases. Three thyroid cancers with paratracheal node metastasis were completely resected by sternotomy and only one thyroid cancer with paratracheal and substernal nodes metastasis was resected by combined thoracotomy and cervical collar incision. CONCLUSION: Resection via cervical collar incision for all retrosternal thyroid nodules were advised. The preliminary experience with this procedure suggests that it has some advantages in the management of substernal goiter, including: 1. ease of operation compared to both sternotomy and thoracotomy; 2. relatively low morbidity; 3. safe and reliable.

Adult↗
PubMed2001

[Value of surgical margin in directing the treatment of early laryngeal carcinoma after partial laryngectomy].

OBJECTIVE: To investigate the value of surgical margin in directing the treatment of early laryngeal carcinoma after partial laryngectomy. METHODS: We studied 87 cases of T1N0M0 and T2N0M0 laryngeal carcinoma in which the surgical margins were reserved during partial laryngectomy. The recurrence and survival rates between the positive and negative margin groups were compared; the survival between the positive margin groups with postoperative radiotherapy and negative groups; the survival between groups with and without postoperative radiotherapy in negative margins. RESULTS: Recurrent rate of the negative group was lower than that of the positive group (5.8% vs 33.3%, chi 2 = 10.64 P = 0.001). The estimated survival was higher in the negative group than in the positive group(P = 0.011), and also in tumor-free time(P = 0.007). The survival of those with positive surgical margin and received postoperative RT was lower than that with negative margins(P = 0.01). In the negative group, the difference in the survival between those with or without postoperative RT was not significant (P = 0.405). CONCLUSION: The prognosis of the positive margin group of the early laryngeal carcinoma was worse than that of the negative group, but postoperative RT can improve it; it is not necessary for the negative group to be treated by postoperative RT.

Adult↗
PubMed2001

[Study on the detaining effect of hypocrelin a in the cancer cell using microspectrum].

Microspectra of mouse lymph cancer cells which one is cultured with HA and the other is cultured without HA have obtained in the range of 20,000-12,000 cm-1. The result shows tha two microspectra are quite different. This point out the cancer cell has changed because of HA. In the microspectrum of cancer cell cultured with HA, we have got the fluorescent peak of HA. This prompts HA has detained in the cancer cell. A new method which studies cells after being affected by drugs using microspectrum has also being developed.

Animals↗
PubMed2001

[Direct determination of Pb, Zn and Cd in environmental and biological samples by FAAS].

This paper describes interference and background correction problem of direct determination of Pb, Zn and Cd in soil, sediment, plants, halobios and sea water by FAAS. With the improvement of limit of detection(L.O.D) of instrument, Pb, Zn and Cd in same environmental and biological samples can be analyzed directly by FAAS, but it is worth taking attention that there are quantities of elements which lead to background interference in air-ethyne flame, such as Al, Na, K Ca, Mg and Fe. Compare with no background correction, limit of detection using D2 lamp background correction is improved by 1.05-4.5 times, the recoveries and the relative standard deviation(R.S.D) are better, standard samples were also analyzed with satisfactory results.

Animals↗
PubMed2001

[A clinical trial of oxymatrine in treating chronic viral hepatitis type B].

OBJECTIVE: To investigate the therapeutic effect of oxymatrine on chronic viral hepatitis type B. METHODS: 303 patients were randomly allocated either to a treatment group or a control group. The treatment group consisted of 253 patients treated with intravenous or intra-muscular injection of oxymatrine and oral oxymatrine capsule. Oral tiopronin was used in the control group. RESULTS: At the end of treatment, the rate of normal ALT was similar among the different groups. The rate of normal ALT was 53.3% - 58.3% in the three oxymatrine groups six months after the end of treatment. It was higher than that of the tiopronin group (P < 0.05). After a follow up of six months, the rate of negative HBeAg was 30.0% - 40.9% in the three oxymatrine groups. It was higher than that of the tiopronin group (16.7%). The rate of negative HBV DNA was 39.2% - 49.5% in the three oxymatrine groups. It was also higher than that of the tiopronin group. CONCLUSION: Oxymatrine can improve the liver function and increase the negative rate of HBeAg and HBV DNA in the patients with chronic hepatitis B. The therapeutic effect of oxymatrine will persist after the cessation of administration.

Adolescent↗
PubMed2000

Mechanism and significance of increased glutathione level in human hepatocellular carcinoma and liver regeneration.

Increased glutathione (GSH) level occurs early during liver regeneration and in many drug and/or radiation-resistant tumors. Whether GSH level is elevated in liver cancer is unknown. GSH levels and expression of GSH synthetic enzymes were measured in hepatocellular carcinoma (HCC) and normal liver. GSH levels doubled in HCC. The mRNA levels of g-glutamylcysteine synthetase heavy subunit (GCS-HS) and GSH synthetase (GS) doubled, whereas the expression of GCS light subunit was unchanged. Nuclear run-on assay showed that the rate of gene transcription doubled for both GCS-HS and GS. In HCC, there is increased binding to anti-oxidant response, AP-1 and NF-kB, three cis-acting elements in the 5'-flanking region of the human GCS-HS important for its transcriptional regulation. The role of GSH in cell growth was examined by using HepG2 cells. Cell GSH level was varied by treating cells with cystine (0 to 0.2 mM) with or without GSH ester or buthionine sulfoximine. Cell GSH level correlated directly with growth rate. Finally, preventing the increase in GSH after two-thirds partial hepatectomy blunted liver regeneration. Thus, GSH level is increased during liver growth as a result of up-regulation of GCS-HS and GS. This increase, in turn, facilitates growth.

Antioxidants↗
PubMed2000

Sulfonation of poly(N-vinylcarbazole) studied by combined time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy

A series of sulfonated poly(N-vinylcarbazole) (PVK) samples have been systematically studied by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS). Negative TOF-SIMS results provided unambiguous evidence that sulfonate groups are chemically attached to the carbazole moiety of PVK. The positive SIMS spectrum of PVK was, however, little affected by the sulfonation reaction. The degree of sulfonation was quantitatively determined by XPS. Therefore, the combination of TOF-SIMS and XPS is useful to follow the sulfonation reaction, both qualitatively and quantitatively. The SIMS intensities of some characteristic fragments are linearly related to the degree of sulfonation, suggesting that quantitative analysis is possible from TOF-SIMS data.

Journal Article↗