Biomedical subjects

Gang Sun

Publications and source records attributed to Gang Sun.

7 recordsLinked to original sources

PubMed2003

Inactivation of bovine plasma amine oxidase by 4-aryloxy-2-butynamines and related analogs.

Propargylamine and 2-butynamine were reported to serve as mechanism-based inactivators of the copper-containing bovine plasma amine oxidase (BPAO). Here, Ar- or Ar-X-extended analogs (X=NH, O, S) of these small molecules were synthesized and evaluated as BPAO inhibitors. 4-Phenoxy-2-butynamine and its aryl ring substituted analogs were found to be both good substrates and time- and concentration-dependent irreversible inactivators. At lower concentrations, loss of activity ceased within minutes, and the plateau data were translated into partition ratio values. For 4-phenoxy-2-butynamine, the turnover product was shown to be the expected corresponding aldehyde, 4-phenoxy-2-butynal, which could inactivate BPAO, but only slowly. The most potent analogs, 4-(4-methylphenoxy-, 4-(4-nitrophenoxy-, 4-(4-methoxyphenoxy-, and 4-(2-naphthyloxy)-2-butynamine, all exhibited 20 min IC(50) values of 20-25 microM at 30 degrees C, and partition ratios of 14-17. Overall, structure-inhibitory data revealed that rigidity and lateral branching reduced inhibitory potency. Although denatured samples of inactivated enzyme retained redox cycling competency of the quinone cofactor, loss of phenylhydrazine reactivity implies covalent blockage of the active site.

Amine Oxidase (Copper-Containing)↗

PubMed2003

Full waveform inversion with optimal basis functions.

Based on the approach suggested by Tarantola, and Gauthier et al., we show that the alternate use of the step (linear) function basis and the block function (quasi-delta function) basis can give accurate full waveform inversion results for the layered acoustic systems, starting from a uniform background. Our method is robust against additive white noise (up to 20% of the signal) and can resolve layers that are comparable to or smaller than a wavelength in thickness. The physical reason for the success of our approach is illustrated through a simple example.

Journal Article↗

PubMed2003

Mass spectrometric characterization of mitochondrial electron transport complexes: subunits of the rat heart ubiquinol-cytochrome c reductase.

Complex III of the mitochondrial electron transport chain, ubiquinol-cytochrome c reductase, was isolated by blue native polyacrylamide gel electrophoresis. Ten of the 11 polypeptides present in this complex were detected directly by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) following electroelution of the active complex. Tryptic and chymotryptic digestion of the complex permit the identification of specific peptides from all of the protein subunits with 70% coverage of the 250 kDa complex. The mass of all 11 proteins was confirmed by second dimension Tricine sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and elution of the separated polypeptides. Additionally, the identity of the core I, core II, cytochrome c and the Rieske iron-sulfur protein were confirmed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) characterization of the peptides generated by in-gel trypsin digestion of the SDS-PAGE separated proteins. The methodology demonstrated for analyzing this membrane-bound electron transport complex should be applicable to other membrane complexes, particularly the other mitochondrial electron transport complexes. The MS analysis of the peptides obtained by in-gel digestion of the intact complex permits the simultaneous characterization of the native proteins and modifications that contribute to mitochondrial deficits that have been implicated as contributing to pathological conditions.

Amino Acid Sequence↗

PubMed2003

Primary jejunoileal neoplasmas: a review of 60 cases.

AIM: Primary neoplasmas of the jejunum and ileum are infrequent and lack specific manifestations and inaccessibility of conventional endoscopy, so the diagnosis of these tumors are usually delayed. So far the data of primary jejunoileal neoplasmas is still scarce, especially in Chinese medical literature in English. There may be some differences among the Chinese and the westerners in jejunoileal neoplasmas. METHODS: A retrospective analysis was made on clinical findings and pathological types. RESULTS: Of the 60 patients with jejunal or ileal neoplasmas, the most frequent symptom was abdominal pain (57 %), followed by tarry stool (43 %) and hematochezia (10 %). Abdominal mass (40 %) was the most common finding on physical examination, followed by anemia and weight loss (35 %). 67 % of the jejunoileal neoplasms were located in the jejunum. Among the malignant neoplasmas (68 %), malignant stroma (47 %) was most common, while the benign stromoma (20 %) was the most common benign neoplasmas. Preoperatively, 40 patients (67 %) were diagnosed as small bowel neoplasmas, of which 34 were found by enteroclysis. Abdominal mass was shown by CT in 18 cases and by ultrasonography in 13. The mean duration of symptoms before diagnosis was 7 months. In 41 patients with malignant tumors, the duration of symptoms before diagnosis exceeded 12 months in 21 cases, lymphatic or distant metastases were found in 26 (63 %)cases during operation. An emergency laparotomy was performed in 4 patients (7 %) owing to intestinal obstruction or perforation. CONCLUSION: Primary jejunoileal neoplasmas in Chinese present some difference from Westerners on clinical features and histopathologic types. Enteroclysis remains the major relevant diagnostic procedure in this study, the misdiagnotic rate is high preoperatively due to failure of detection by conventional imaging procedures such as CT and inaccessibility of routine endoscopy. For the suspected patients, combined application of aforementioned procedures may facilitate early diagnosis. The wireless capsule endoscopy may improve the diagnostic rate of jejunoileal neoplasmas in the future.

Adolescent↗

PubMed2003

Percutaneous vertebroplasty using instruments and drugs made in China for vertebral metastases.

OBJECTIVES: To evaluate the effect of percutaneous vertebroplasty on vertebral tumor metastasis using instruments and drugs made in China and to explore the technique of percutaneous vertebroplasty. METHODS: Thirty-two patients with vertebral metastasis were treated with percutaneous vertebroplasty with instruments and drugs made in China. Anterolateral approach for cervical vertebrae and transpedicular approach for thoracic and lumbar vertebrae were used. The volume of disease focus and the amount of polymethy methacrylate (PMMA) injected were calculated with formula V = 4/3pi (D/2)(3) preoperatively. PMMA with contrast was mixed according to the ratio of powder/liquid/contrast of 3:2:1. The procedures were monitored under fluoroscopy. PMMA was injected in the polymerization time. CT scanning was performed before and after the operation. RESULTS: The percentage of lesion PMMA fill was more than 50% as demonstrated by CT. Clinical data were obtained from the cases followed up for 7 - 12 months, and the rate of pain relief was 90.6% (29/32) at one week, 71.8% (23/32) at six months, and 58.6% (17/29) at 12 months after operation. There were no cases of PMMA leakage that affected clinical performance. CONCLUSIONS: Percutaneous vertebroplasty for vertebral tumor metastasis using instruments and drugs made in China was effective. It is important to prevent paravertebral leaks of PMMA and to ensure that PMMA is injected within the polymerization time.

Aged↗

PubMed2002

[Colocalization of 11beta-hydroxysteroid dehydrogenase type I and glucocorticoid receptor and its significance in rat hippocampus].

This paper was designed to observe the colocalization of 11beta-HSD1 and GR, and its significance in the rat hippocampus. Immunocytochemical dual-staining showed that not only 11beta-HSD1 but also GR immunoreactive substances were present in the cultured rat hippocampal neurons. Moreover, they were colocalized in the same hippocampal neuron. Synthetic glucocorticoid dexamethasone (DEX) up-regulated the protein expression and activity of 11beta-HSD1 in the cultured hippocampal neurons, as determined by Western blot and thin layer chromatography (TLC) respectively. The transfection of PC12 cells with the plasmid containing promoter sequence of 11beta-HSD1 gene and the reporter gene of CAT enzyme was conducted. DEX up-regulated the reporter gene expression in the system described above. The up-regulation of 11beta-HSD1 and reporter gene expression induced by DEX were both blocked by GR antagonist RU38486. Our study suggests that the colocalization of 11beta-HSD1 and GR in the hippocampus may be implicated in the up-regulation of 11beta-HSD1 expression by glucocorticoids combining to its promoter region, which in turn produces more biologically active glucocorticoids necessary for the binding of low affinity of GR.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed2002

[Preliminary study on anti-baculovirus mechanism of feeding housefly larvae (Musca domestia) and population infection model of outbreaking epidemic disease of shrimp (Panaeus chinensis)].

Based on indoors individual infection and outdoor population infection of shrimp, population infection model was established and anti-baculovirus mechanism of housefly larvae was analyzed. The results showed that 50% death time of the shrimps feeding with housefly larval reasonably was prolonged 3-5 times compared with the control group. Prophenoloxidase system of prawns was activated while feeding shrimps with housefly larval 7-10 days before infection by baculovirus, and prophenoloxidase activity was 3 times higher than the control group. The establishment of population infection model illustrated clearly important role of housefly larvae in improving the immunity of shrimps from baculovirus.

Animals↗