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Biomedical subjects

G Du

Publications and source records attributed to G Du.

At least 37 records · Page 2Linked to original sources
PubMed2000

Diagnosis and surgical treatment of posterior fossa solid hemangioblastomas.

OBJECTIVE: To elucidate the diagnosis and surgical treatment of the posterior fossa solid hemangioblastomas (PFSHs). METHODS: The data from 22 patients with PFSHs verified by surgery and pathology were analyzed retrospectively and a review of relevant literature was conducted. RESULTS: The preoperative definitive diagnosis rate was 13/22. Total tumor removal was achieved in 20 patients. Two of the 22 patients died after surgery, one of brain-stem injury and the other from an intracranial hemorrhage. Twenty patients were followed up for 2 months to 8 years (average, 2 years). Kamofsky scale was > or = 80 in 15 patients, 60-70 in 1 patient and not measured in 4 patients who died during follow-up. The causes of death were pneumonia (2 patients) and purulent meningitis (2). CONCLUSION: MRI and DSA (digital subtraction angiography) are major preoperative diagnostic modalities for PFSH, but PFSH remains a challenging benign neoplasm. Special microsurgical techniques and improved operative manipulation can improve surgical efficacy.

Adult↗
PubMed2000

[Survey on children's dental fluorosis and fluoride content in urine after defluridation to improve drinking water].

The authors surveyed the dental fluorosis and fluoride content in urine of 8-12 years old children's in 1993 to 1999 for the evaluation of the efficiency to prevent endemic fluorosis after defluoridation to change drinking water source in Guangdong Province. Three villages: slight fluorosis area in Dazhai village, middle fluorosis area in Hupi village and severe fluorosis area in Anquan village in Fengshun County were surveyed. The results showed that the fluoride contents in drinking water were 1 mg/L (or less) in Anquan village, at the same time the prevalence of dental fluorosis and indexes of dental fluorosis were decreasing as changing water time. Fluoride contents in urine were normal. But in other two villages, the fluoride contents in drinking water exceeded 1 mg/L, therefore the children's prevalence rates and indexes of dental fluorosis were higher than the national standards. It is important to keep fluoride contents in drinking water under 1 mg/L for preventing endemic fluorosis by defluoridation to improve drinking water.

Child↗
PubMed2000

[Effects of nitrogen feeding on the accumulation of poly-beta-hydroxybutyrate with Alcaligenes eutrophus].

On the basis of analysis of PHB fermentation processes, the effects of ammonium sulfate feeding rate at PHB formation period on the PHB accumulation by Alcaligenes eutrophus were investigated. It was shown that the complete absence of nitrogen source at PHB formation phase would lead to the decline of PHB synthetic activity, and the obvious influences of different nitrogen feeding rate on PHB synthesis were observed. Higher PHB content, but relative lower cell dry weight, PHB concentration and PHB productivity could be obtained at slower nitrogen feeding rate. The excessive nitrogen feeding rate resulted in the drop of PHB content, which led to the decrease of PHB concentration and PHB productivity. The better results could be achieved when the ammonium sulfate feeding rate was set at around 0.5 g/h.

Ammonium Sulfate↗
PubMed1999

EGb 761 protects liver mitochondria against injury induced by in vitro anoxia/reoxygenation.

The present study investigated the protective effects of Ginkgo biloba extract (EGb 761) on rat liver mitochondrial damage induced by in vitro anoxia/reoxygenation. Anoxia/reoxygenation was known to impair respiratory activities and mitochondrial oxidative phosphorylation efficiency. ADP/O (2.57 +/- 0.11) decreased after anoxia/reoxygenation (1.75 +/- 0.09, p < .01), as well as state 3 and uncoupled respiration (-20%, p < .01), but state 4 respiration increased (p < .01). EGb 761 (50-200 microg/ml) had no effect on mitochondrial functions before anoxia, but had a specific dose-dependent protective effect after anoxia/reoxygenation. When mitochondria were incubated with 200 microg/ml EGb 761, they showed an increase in ADP/O (2.09 +/- 0.14, p < .05) and a decrease in state 4 respiration (-22%) after anoxia/reoxygenation. In EPR spin-trapping measurement, EGb 761 decreased the EPR signal of superoxide anion produced during reoxygenation. In conclusion, EGb 761 specially protects mitochondrial ATP synthesis against anoxia/reoxygenation injury by scavenging the superoxide anion generated by mitochondria.

Adenosine Triphosphate↗
PubMed1999

[Selection of human phage antibodies against HAV and DNA sequence analysis].

OBJECTIVE: To obtain the anti-HAV antibodies. METHODS: The antibody-capturing antigen strategy was used in panning antibody library with impure antigen. The HAV-binding activity and specificity of phage antibodies were assayed by sandwich ELISA and competitive inhibition ELISA. RESULTS: Phage antibodies(Fab) against HAV were screened from a human immunoglobulin combinatorial library. Fd and light chain genes were sequenced. Comparison of the Fd gene and light chain gene with KABAT database showed that the heavy chain belonged to IgG1 subclass, and its variable region was derived from rearranged germ-line gene of DP88, D3-3 and JH5; while the light chain was a member of V kappa III family, the germ-line gene was DP kappa 22 and J kappa 4. CONCLUSION: Phage antibodies against HAV were selected from the antibody library by using the antibody-capturing antigen strategy. The result also suggested that the antibody library was constructed successfully.

Amino Acid Sequence↗
PubMed1999

Neuronavigation for the resection of cavernous angiomas.

OBJECTIVE: To introduce the use of the StealthStation neuronavigator combined with preoperative computerized tomography (CT) in resection of intracranial cavernous angiomas (CAs). METHODS: The StealthStation neuronavigator was used to provide a realtime correlation of the operating field and the computerized images in 6 patients with CAs. All patients suffered from epileptic seizures. Four patients underwent keyhole surgery and 2 underwent small skin-flap craniotomy. The mean follow-up was 4.5 months. RESULTS: With the guidance of neuronavigator, lesionectomy associated with removal of hemosiderin deposition, gliosis and calcification was performed precisely. The mean fiducial error was from 1.65 mm to 4.53 mm, the predicted accuracy at 10 cm was between 1.82 mm and 3.28 mm, and the sustained accuracy ranged from 0.50 mm to 3.45 mm. CONCLUSION: The StealthStation neuronavigator is reliable and accurate in the resection of CAs.

Adolescent↗
PubMed1999

[Neuronavigation for the resection of intracranial cavernous angiomas].

OBJECTIVE: To evaluate the use of the Stealth Station neuronavigator in conjunction with preoperative computerized tomography (CT) in the resection of intracranial cavernous angiomas (CAs). METHODS: The Stealth Station neuronavigator was used to provide real-time correlation of the operating field and computerized images in 6 patients with CAs. All of them suffered from epileptic seizures. RESULTS: Neuronavigation-guided lesionectomy with removal of hemosiderin deposition, gliosis and calcification in all cases was performed precisely. Mean fiducial error, predicted accuracy at 10 cm, and sustained accuracy ranged from 1.65 to 4.53 mm, 1.82 to 3.28 mm, and 0.50 to 3.45 mm, respectively. CONCLUSIONS: The Stealth Station neuronavigator is reliable and accurate in the resection of CAs.

Adolescent↗
PubMed1999

[Effect of tian ma cu zhi chongji medicinal granules (TMCZCJ) on blood rheology in hypostasis rats due to stagnation of liver-qi and learning-memory disorder in cerebral ischemia-reperfusion mice].

OBJECTIVE: To investigate the effect of TMCZCJ on the blood rheology in hypostasis rats due to stagnation of the liver-qi and on the learning-memory disorder in cerebral ischemia-reperfusion mice. METHOD: The models of hypostasis due to stagnation of the liver-qi were made by combining irritation with hypodemic injected adrenalin and ice-bath in rats, and the models of learning-memory disorder were made by repeatedly ligating-reperfusing the bilateral carotid in mice. The hypostasis rats and learning-memory disorder mice were perorally administrated TMCZCJ(7.7, 15.4 g.kg-1) once a day, for fourteen consecutive days. RESULT: TMCZCJ can significantly reduce plasma viscosity, blood viscosity and reduced viscosity in hypostasis rats. It can also improve the latent learning-memory capability and memory gain-repetition ability in water-maze for cerebral ischemia-reperfusion mice. CONCLUSION: TMCZCJ can improve remarkably blood rheology in hypostasis rats and learning-memory disorder in cerebral ischemia-reperfusion mice.

Animals↗
PubMed1999

[Optimization of fermentation conditions for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Alcaligenes eutrophus].

A close relationship, between the initial addition time and concentration of propionate and HV fraction, was observed in shaking culture of Alcaligenes eutrophus for the production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The optimal initial addition time of propionate was determined at the onset of PHBV formation period. Although relatively high HV unit could be obtained under high propionate concentration, the growth and product synthetic activities were inhibited obviously. Different ratios of glucose to propionate were fed to stimulate the formation of HV unit and the results were compared. The optimizing feeding strategy of propionate was proposed based on the consideration of several fermentation index. The final cell dry weight, PHB concentration, PHB content and HV fraction in PHBV reached 52.1 g/L, 40.8 g/L, 78.3% and 16.2 mol%, respectively, Yield coefficient of HV unit to propionate and PHBV productivity were obtained to be 0.5 g/g and 0.74 g/(L/h), respectively.

Cupriavidus necator↗
PubMed1998

Mechanism of mammalian soluble epoxide hydrolase inhibition by chalcone oxide derivatives.

A series of substituted chalcone oxides (1,3-diphenyl-2-oxiranyl propanones) and structural analogs was synthesized to investigate the mechanism by which they inhibit soluble epoxide hydrolases (sEH). The inhibitor potency and inhibition kinetics were evaluated using both murine and human recombinant sEH. Inhibition kinetics were well described by the kinetic models of A. R. Main (1982, in Introduction to Biochemical Toxicology, pp. 193-223, Elsevier, New York) supporting the formation of a covalent enzyme-inhibitor intermediate with a half-life inversely proportional to inhibitor potency. Structure-activity relationships describe active-site steric constraints and support a mechanism of inhibition consistent with the electronic stabilization of the covalent enzyme-inhibitor intermediate. The electronic effects induced by altering the ketone functionality and the para-substitution of the phenyl attached to the epoxy C1 (i.e., the alpha-carbon) had the greatest influence on inhibitor potency. The direction of the observed influence was reversed for the inhibitory potency of glycidol (1-phenyl-2-oxiranylpropanol) derivatives. Recent insights into the mechanism of epoxide hydrolase activity are combined with these experimental results to support a proposed mechanism of sEH inhibition by chalcone oxides.

Animals↗
PubMed1998

Generation of superoxide anion by mitochondria and impairment of their functions during anoxia and reoxygenation in vitro.

A small portion of the oxygen consumed by aerobic cells is converted to superoxide anion at the level of the mitochondrial respiratory chain. If produced in excess, this harmful radical is considered to impair cellular structures and functions. Damage at the level of mitochondria have been reported after ischemia and reperfusion of organs. However, the complexity of the in vivo system prevents from understanding and describing precise mechanisms and locations of mitochondrial impairment. An in vitro model of isolated-mitochondria anoxia-reoxygenation is used to investigate superoxide anion generation together with specific damage at the level of mitochondrial oxidative phosphorylation. Superoxide anion is detected by electron paramagnetic resonance spin trapping with POBN-ethanol. Mitochondrial respiratory parameters are calculated from oxygen consumption traces recorded with a Clark electrode. Respiring mitochondria produce superoxide anion in unstressed conditions, however, the production is raised during postanoxic reoxygenation. Several respiratory parameters are impaired after reoxygenation, as shown by decreases of phosphorylating and uncoupled respiration rates and of ADP/O ratio and by increase of resting respiration. Partial protection of mitochondrial function by POBN suggests that functional damage is related and secondary to superoxide anion production by the mitochondria in vitro.

Adenosine Diphosphate↗
PubMed1998

[Expression of standard and variant CD44 in human lung cancer].

OBJECTIVE: CD44 transmembrane glycoprotein, a cell adhesion molecule, is expressed in most adult tissues and in the majority of neoplasms. Due to alternative splicing, this cell adhesion molecule exists in multiple isoforms, some of which have been associated with specific types of tumors as well as with tumor invasion and metastasis. In this study, we observed the expression of CD44 standard (CD44s) and variant forms (CD44v6) in 96 primary lung carcinomas and 12 cases of metastatic lymph nodes by immunohistochemistry and associated the results with clinical outcome. To understand the correlation of CD44's expression with the histological types, differentiation, progression and metastasis of primary lung carcinomas. METHOD: Formalin-fixed paraffin-embedded archival tissues from 56 squamous cell carcinomas (SCC), 34 adenocarcinomas (ADC), 6 small cell lung carcinomas (SCLC) and 12 metastatic lymph nodes were immunostained after microwave antigen repair with monoclonal antibodies against CD44s and CD44v6, and the results were associated with histological tumor type, tumor stage and metastasis. RESULT: (1) SCC showed much higher membranous expression of CD44s and CD44v6 than ADC (P < 0.01), and there is no expression in all 6 SCLC cases. (2) In 12 metastatic lymph nodes, 10 metastatic lung carcinomas were found strong immunoreactivity for CD44v6 (83%), and in comparison with lung carcinomas without lymph node metastasis (51%), primary lung carcinomas with lymph node metastasis showed strong expression of CD44v6 (91%, chi 2 = 14.92, P < 0.01). (3) The expression of CD44s and CD44v6 is independent from tumor histopathological grading (well, moderate, poor differentiated). Among different tumor stages, however, there is a distinct statistic difference between stage I + II and stage III + IV (chi 2 = 6.05, P < 0.05) with the tendency of higher stage with higher expression of CD44v6. CONCLUSION: CD44 expresses mostly in NSCLC. Moreover, there is an stronger expression of CD44s and v6 in SCC over ADC; Immunopositivity of CD44v6 may suggest a potential of high risk for lymph node metastasis in NSCLC; CD44v6 reactivity may be useful to decide TNM stage of NSCLC, especially to discriminate stage I, II with higher stage.

Adenocarcinoma↗
PubMed1998

[Clinical effect of tianma-cuzhi granules on senile vascular dementia].

OBJECTIVE: To assess the clinical efficacy of Tianma-cuzhi Granules (TMC) in treating senile vascular dementia(VaD) of the "sthenia of liver-yang" type. METHOD: TMC were given to thirty VaD patients three times a day of 0.5 g/bageach. The treatment course was one month and the patients finished two consecutive courses. RESULTS: TMC could markedly increase the mini-mental state examination (MMSE) and Hamilton depression scale(HDS) marks of VaD patients, and also contribute to improving certain indexes especially in abnormal cases. CONCLUSION: TMC have certain effects on senile VaD.

Aged↗
PubMed1998

[Determination of content of radix Paeoniae Rubar(Chishao)801 in rabbit's plasma by HPLC].

A HPLC method was used to determine the content of Radix Paeoniae Rubar (Chishao)801 in rabbit's plasma, using Nucleosil C18 column, methanol, water and glacial acetic acid (48:50:2) as mobile phase ethye 4-hydroxybenzoate as internal standard, and UV-detector(lambda max: 275 nm, AUFS: 0.02). The average recovery was 96.70%(C: 2.5 micrograms/ml) and 98.86%(C: 5 micrograms/ml) respectively. The lowest determination limit was 0.1 microgram/ml. The method is simple, accurate, sensitive and reliable.

Animals↗
PubMed1998

[Protective effect of Astragalus membranaceus (Fisch.) Bge. and Hedysarum polybotrys Hand.-Mazz. on experimental model of cerebral ischemia in rats].

The experimental model of middle cerebral artery embolism in rats was made by inserting nylon thread. It was discovered that Astragalus membranaceus decoction(both 4.26 g.kg-1 and 7.1 g.kg-1) could reduce the capillary hyperpermeability and alleviate the dyskinesia caused by cerebral ischemia in rats. Purified Hedysarum polybotrys decoction (waste substances removed with alcohol after decocting with water) (12.5 g.kg-1) could reduce the water content in brain caused by occlusion of bilateral carotids in rats. Purified Hedysarum polybotrys decoction showed a tendency to reduce the water content in brain, but without statistical significance.

Animals↗
PubMed1997

Protective effects of salvianolic acid A against impairment of memory induced by cerebral ischemia-reperfusion in mice.

OBJECTIVE: To investigate the protective effects of Salvianolic acid A against impairment of memory induced by cerebral ischemia-reperfusion in mice and the relationship between antioxidant activity of salvianolic acid A and its protective effects on brain injury caused by reperfusion. METHODS: Step down and step through tests were used to examine the function of memory in the model of impairment of memory induced by cerebral ischemia-reperfusion in mice. RESULTS: Salvianolic acid A (Sal A) at the dosage of 3 and 10 mg.kg-1 i.v. could improve the impaired memory function induced by cerebral ischemia-reperfusion as shown in step down and step through tests. In step down tests, the mean number of errors of Sal A 3 and 10 mg.kg-1 treated group were 1.29, 1.15 and that of control group was 3.8 (P < 0.01). The latencies of these tests were longer than those of the control group. Meanwhile, 3 and 10 mg.kg of Sal A i.v. were found to reduce the malondialdehyde contents in the cortex, hippocampus and corpus striatum of cerebral ischemia-reperfusion rat in vivo. Sal A 10-100 nmol.L-1 was also shown to inhibit lipid-peroxidation of the brain and scavenge the free hydroxyl radicals in vitro. CONCLUSION: These indicate that the ameliorating effect of Sal A on learning and memory impairment caused by cerebral ischemia reperfusion may be related to its anti-oxidant activity.

Animals↗
PubMed1995

Protein structure encodes the ligand binding specificity in pheromone binding proteins.

The ligand specificities and binding affinities of three recombinant pheromone binding proteins (PBPs) of two saturniid moths (genus Antheraea) were determined by using a novel binding assay in conjunction with two tritium-labeled constituents of the pheromone blend, [3H]-6E,11Z-hexadecadienyl acetate and [3H]-4E,9Z-tetradecadienyl acetate. The new binding assay, in which nonspecific adsorption to a plastic vessel is suppressed by presaturation of the surface with a 1-alkanol, allows measurement of dissociation constants (KD) for lipophilic ligands for their carrier proteins. The three PBPs showed KD values for [3H]-6E,11Z-16:Ac and [3H]-4E,9Z-14:Ac between 0.6 and 30 microM, as determined by Scatchard analysis. Importantly, two PBPs (Aper-1 and Aper-2) from one species showed opposite binding specificities for these two ligands. Aper-1, like Apol-3, showed 15-fold higher affinity for 6E,11Z-16:Ac than for 4E,9Z-14:Ac, while Aper-2 showed a 3.5-fold preference for binding the shorter chain compound. In addition, for the Apol-3 PBP, displacement of [3H]-6E,11Z-16:Ac binding by other pheromone components or analogs showed a clear trend in relative binding affinity: 6E,11Z-16:Ac > 4E,9Z-14:Ac > 6E,11Z-16:Al approximately 16:Ac > 6E,11Z-16:OH > 4E,9Z-14:OH. These data clearly demonstrate a > 1000-fold range of binding affinities among these very similar structures and unambiguously demonstrate the specificity of the PBP-pheromone interaction. Moreover, this assay offers the potential for determining ligand specificities for odorant binding proteins and other proteins in the vertebrate lipocalin superfamily.

Amino Acid Sequence↗