Biomedical subjects

G Jiang

Publications and source records attributed to G Jiang.

At least 55 records · Page 3Linked to original sources

PubMed2001

Preparation and characterization of a composite PLGA and poly(acryloyl hydroxyethyl starch) microsphere system for protein delivery.

PURPOSE: To prepare and characterize a novel composite microsphere system based on poly(D,L-lactide-co-glycolide) (PLGA) and poly(acryloyl hydroxyethyl starch) (acHES) hydrogel for controlled protein delivery. METHODS: Model proteins, bovine serum albumin, and horseradish peroxidase were encapsulated in the acHES hydrogel, and then the protein-containing acHES hydrogel particles were fabricated in the PLGA matrix by a solvent extraction or evaporation method. The protein-loaded PLGA-acHES composite microspheres were characterized for protein loading efficiency, particle size, and in vitro protein release. Protein stability was examined by size-exclusion chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and monitoring the enzymatic activity. RESULTS: Scanning electron microscopy showed discrete PLGA microspheres containing many acHES particles. The composite microspheres were spherical and smooth in size range of 39-93 microm. The drug loading efficiency ranged from 51 to 101%. The composite microspheres showed more favorable in vitro release than conventional PLGA microspheres. The composite microspheres showed 20% less initial with a gradual sustained release compared to high burst (approximately 60%) followed by a very slow release with the conventional PLGA microspheres. The composite microspheres also stabilized encapsulated proteins from the loss of activity during the microsphere preparation and release. Proteins extracted from the composite microspheres showed good stability without protein degradation products and structural integrity changes in the size-exclusion chromatography and SDS-PAGE analyses. Horseradish peroxidase extracted from microspheres retained more than 81% enzymatic activity. CONCLUSION: The PLGA-acHES composite microsphere system could be useful for the controlled delivery of protein drugs.

Acrylic Resins↗

PubMed2001

Enhancement of bone growth by sustained delivery of recombinant human bone morphogenetic protein-2 in a polymeric matrix.

PURPOSE: The purpose of this study was to develop a polymeric sustained delivery system for recombinant human bone morphogenetic protein-2 (BMP-2) and to evaluate local bone growth induced by the sustained release of BMP-2 in an animal model. METHODS: BMP-2 was incorporated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres to obtain different release rates. Two sustained and an immediate release implants were produced by suspending the BMP-2 loaded PLGA microspheres in aqueous sodium carboxymethylcellulose (CMC), lyophilizing, and cutting the dried materials to the size of the animal bone defects. The local in vivo release at the implantation site in rat calvarial defects was determined by gamma scintigraphy using radiolabeled BMP-2. The local bone induction in the critical size of rabbit calvarial defects was evaluated six weeks post implantation. RESULTS: The immediate release implant showed about 65% initial drug release within 24 h and the remaining BMP-2 quickly exhausted from the implantation site within 7 days. The sustained release implants, showing 45-55% initial release followed by a prolonged release for 21 days, released a greater amount of BMP-2 at the implantation site and maintained higher serum BMP-2 for the longer period of time compared to the immediate release implant. Significant bone growth was observed in all BMP-2 treated defects while the defects without treatment or with BMP-2-free implant showed minimal bone healing. 75-79% of rabbit calvarial defect area was healed with newly induced bone matrix by the sustained release implants in 6 weeks as compared to 45% recovery from the immediate release implant. CONCLUSION: The sustained delivery of BMP-2 based on the biodegradable PLGA microsphere system resulted in faster and more complete bone healing in the animal model.

Animals↗

PubMed2001

Preconcentration of trace amounts of cadmium in aqueous samples on minicolumns packed with Chromosorb series gas chromatographic stationary phases and its determination by electrothermal atomic absorption spectrometry.

The adsorption characteristics of five commercially available Chromosorb GC stationary phases towards Cd2+ and their application to the preconcentration and ETAAS determination of Cd2+ in several water samples were studied. The experimental results indicated that although all of the five Chromosorb GC stationary phases studied can retain Cd2+ quantitatively from aqueous solutions at appropriate pH values without adding chelating reagent. Chromosorb 105 displayed the highest adsorption capacity. A highly sensitive, simple methodology for preconcentration and ETAAS determination of trace amounts of cadmium in natural water samples using a Chromosorb 105 packed minicolumn is proposed. Conditions for quantitative and reproducible preconcentration, elution and subsequent ETAAS determination were established. The high retention efficiency (> 95%) for Cd2+ provides a sensitivity enhancement of 100-fold for a 200 mL sample volume with a detection limit of 6.2 ng L(-1) (3 sigma).

Cadmium↗

PubMed2001

A functional myo-inositol dehydrogenase gene is required for efficient nitrogen fixation and competitiveness of Sinorhizobium fredii USDA191 to nodulate soybean (Glycine max [L.] Merr.).

Inositol derivative compounds provide a nutrient source for soil bacteria that possess the ability to degrade such compounds. Rhizobium strains that are capable of utilizing certain inositol derivatives are better colonizers of their host plants. We have cloned and determined the nucleotide sequence of the myo-inositol dehydrogenase gene (idhA) of Sinorhizobium fredii USDA191, the first enzyme responsible for inositol catabolism. The deduced IdhA protein has a molecular mass of 34,648 Da and shows significant sequence similarity with protein sequences of Sinorhizobium meliloti IdhA and MocA; Bacillus subtilis IolG, YrbE, and YucG; and Streptomyces griseus StrI. S. fredii USDA191 idhA mutants revealed no detectable myo-inositol dehydrogenase activity and failed to grow on myo-inositol as a sole carbon source. Northern blot analysis and idhA-lacZ fusion expression studies indicate that idhA is inducible by myo-inositol. S. fredii USDA191 idhA mutant was drastically affected in its ability to reduce nitrogen and revealed deteriorating bacteroids inside the nodules. The number of bacteria recovered from such nodules was about threefold lower than the number of bacteria isolated from nodules initiated by S. fredii USDA191. In addition, the idhA mutant was also severely affected in its ability to compete with the wild-type strain in nodulating soybean. Under competitive conditions, nodules induced on soybean roots were predominantly occupied by the parent strain, even when the idhA mutant was applied at a 10-fold numerical advantage. Thus, we conclude that a functional idhA gene is required for efficient nitrogen fixation and for competitive nodulation of soybeans by S. fredii USDA191.

Amino Acid Sequence↗

PubMed2001

Epidermal growth factor-induced tumor cell invasion and metastasis initiated by dephosphorylation and downregulation of focal adhesion kinase.

Upregulated epidermal growth factor (EGF) receptor (EGFR) expression and EGFR-induced signaling have been correlated with progression to invasion and metastasis in a wide variety of carcinomas, but the mechanism behind this is not well understood. We show here that, in various human carcinoma cells that overexpress EGFR, EGF treatment induced rapid tyrosine dephosphorylation of focal adhesion kinase (FAK) associated with downregulation of its kinase activity. The downregulation of FAK activity was both required and sufficient for EGF-induced refractile morphological changes, detachment of cells from the extracellular matrix, and increased tumor cell motility, invasion, and metastasis. Tumor cells with downregulated FAK activity became less adherent to the extracellular matrix. However, once cells started reattaching, FAK activity was restored by activated integrin signaling. Moreover, this process of readhesion and spreading could not be abrogated by further EGF stimulation. Interruption of transforming growth factor alpha-EGFR autocrine regulation with an EGFR tyrosine kinase inhibitor led to a substantial increase in FAK tyrosine phosphorylation and inhibition of tumor cell invasion in vitro. Consistent with this, FAK tyrosine phosphorylation was reduced in cells from tumors growing in transplanted, athymic, nude mice, which have an intact autocrine regulation of the EGFR. We suggest that the dynamic regulation of FAK activity, initiated by EGF-induced downregulation of FAK leading to cell detachment and increased motility and invasion, followed by integrin-dependent reactivation during readhesion, plays a role in EGF-associated tumor invasion and metastasis.

3T3 Cells↗

PubMed2001

Contractile regulation of the Na(+)-K(+)-2Cl(-) cotransporter in vascular smooth muscle.

Vasoconstrictors activate the Na(+)-K(+)-2Cl(-) cotransporter NKCC1 in rat aortic smooth muscle, but the mechanism is unknown. Efflux of (86)Rb(+) from rat aorta in response to phenylephrine (PE) was measured in the absence and presence of bumetanide, a specific inhibitor of NKCC1. Removal of extracellular Ca(2+) completely abolished the activation of NKCC1 by PE. This was not due to inhibition of Ca(2+)-dependent K(+) channels since blocking these channels with Ba(2+) in Ca(2+)-replete solution did not prevent activation of NKCC1 by PE. Stimulation of NKCC1 by PE was inhibited 70% by 75 microM ML-9, 97% by 2 microM wortmannin, and 70% by 2 mM 2,3-butanedione monoxime, each of which inhibited isometric force generation in aortic rings. Bumetanide-insensitive Rb(+) efflux, an indication of Ca(2+)-dependent K(+) channel activity, was reduced by ML-9 but not by the other inhibitors. Stretching of aortic rings on tubing to increase lumen diameter to 120% of normal almost completely blocked the stimulation of NKCC1 by PE without inhibiting the stimulation by hypertonic shrinkage. We conclude that activation of the Na(+)-K(+)-2Cl(-) cotransporter by PE is the direct result of smooth muscle contraction through Ca(2+)-dependent activation of myosin light chain kinase. This indicates that the Na(+)-K(+)-2Cl(-) cotransporter is regulated by the contractile state of vascular smooth muscle.

Androstadienes↗

PubMed2001

Growth factors stimulate the Na-K-2Cl cotransporter NKCC1 through a novel Cl(-)-dependent mechanism.

The Na-K-2Cl cotransporter NKCC1 is an important volume-regulatory transporter that is regulated by cell volume and intracellular Cl(-). This regulation appears to be mediated by phosphorylation of NKCC1, although there is evidence for additional, cytoskeletal regulation via myosin light chain (MLC) kinase. NKCC1 is also activated by growth factors and may contribute to cell hypertrophy, but the mechanism is unknown. In aortic endothelial cells, NKCC1 (measured as bumetanide-sensitive (86)Rb(+) influx) was rapidly stimulated by serum, lysophosphatidic acid, and fibroblast growth factor, with the greatest stimulation by serum. Serum increased bumetanide-sensitive influx significantly more than bumetanide-sensitive efflux (131% vs. 44%), indicating asymmetric stimulation of NKCC1, and produced a 17% increase in cell volume and a 25% increase in Cl(-) content over 15 min. Stimulation by serum and hypertonic shrinkage were additive, and serum did not increase phosphorylation of NKCC1 or MLC, and did not decrease cellular Cl(-) content. When cellular Cl(-) was replaced with methanesulfonate, influx via NKCC1 increased and was no longer stimulated by serum, whereas stimulation by hypertonic shrinkage still occurred. Based on these results, we propose a novel mechanism whereby serum activates NKCC1 by reducing its sensitivity to inhibition by intracellular Cl(-). This resetting of the Cl(-) set point of the transporter enables the cotransporter to produce a hypertrophic volume increase.

Animals↗

PubMed2001

Fibroblast growth factor receptor 2 (FGFR2): genomic sequence and variations.

Fibroblast growth factor receptors (FGFRs) play an important role in development and tumorigenesis. Mutations in FGFR2 cause more than five craniosynostosis syndromes. The FGFR2 genomic structure is the largest of the FGFR family. We have refined and extended the genomic organization of the FGFR2 gene by sequencing more than 119 kb of PACs, cosmids, and PCR products and assembling a region of approximately 175 kb. Although the gene structure has been reported to include only 20 exons, we have verified the presence of at least 22 exons, some of which are alternatively spliced. The sizes of six exons differed from those reported previously. Comparison of our sequence and those in the NCBI database detected more than 300 potential single nucleotide polymorphisms (SNPs). However, sequencing regions containing 52 of these potential SNPs verified only 14 in PCR products generated from 16 CEPH alleles. In contrast, direct sequencing of the CEPH DNAs revealed 21 other polymorphisms. Only one SNP was found in the 2,926 bp of coding sequence. Twenty-seven SNPs, two insertion polymorphisms and five microsatellite polymorphisms are contained in approximately 16.6 kb of non-coding sequence. These data yield an average of one polymorphism for approximately 488 bp of non-coding sequence examined. This collection of SNP, insertion, and repeat polymorphisms will aid future association studies between the FGFR2 gene and human disease and will enhance mutation detection.

Alleles↗

PubMed2001

Comprehensive-trace level determination of methyltin compounds in aqueous samples by cryogenic purge-and-trap gas chromatography with flame photometric detection.

A comprehensive method was developed for the sensitive and fast determination of trace levels of methyltin compounds in aqueous samples. Tin compounds in aqueous solution at pH 5 were converted to the corresponding volatile hydrides: CH3SnH3, (CH3)2SnH2, and (CH3)3SnH, by reaction with potassium borohydride. A CP-4010 purge and trap injector (PTI) was used to purge analyte species from water directly. The volatile derivatives were base-line separated on a capillary column in an Angilent-6890 gas chromatograph by a suitable temperature program and were detected by a flame photometric detector (FPD). The detection limits were 18 ng L-1 for monomethyltin, 12 ng L-1 for dimethyltin, and 3 ng L-1 for trimethyltin, respectively. This method was successfully applied to the determination of methyltin compounds in different aqueous samples.

Chemical Industry↗

PubMed2001

[Current status of organotin studied in China and abroad].

The toxicity of organotin compounds and the current pollution status in China and abroad is discussed. Regulations and limitations on the usage of organotin compounds in western countries are introduced briefly in this paper. The examination results showed that the most Chinese harbors, rivers as well as larger lakes were contaminated by organotin, especially by tribuyltin compounds. Regulations for limiting the use of butyltin compounds as antifouling paints in Chinese marine industries are imperatively needed. Actions toward for the investigation of organotin contamination levels in food chains and in household commodities are also highly desired.

Animals↗

PubMed2001

[Peri-operative management in patients with thoracic aortic aneurysm complicated with cardiac tamponade].

We retrospectively summarized the peri-operative hemodynamic status and respiratory function in patients with thoracic aneurysms complicated with cardiac tamponade (Tamponade Group; n = 6) in comparison with patients complicated with hemorrhagic pericardial effusion without symptom of cardiac tamponade (Effusion Group; n = 10). There were no difference with regard to preoperative heart rate, pericardial effusion quantity, frequency of emergent operation and operation time. Preoperative hemodynamic status was worse in Tamponade Group than in Effusion Group. The cardiac indices of 12 h, 24 h, 48 h after operation in Tamponade Group were 2.60 +/- 0.60, 2.29 +/- 0.42, 1.95 +/- 0.33 l/min/m2 respectively, those were not different in Effusion Group. The differences between O2 tension in alveolar and arterial blood O2 tension (A-aDO2) and oxygenation indices (OI) of 12 h and 24 h after operation were significantly worse in Tamponade Group than in Effusion Group, but those of 48 h were not different. The operative mortality was 50% in Tamponade Group, and none in Effusion Group. It is very important to maintain hemodynamic status before operation, to perform complete repair (graft replacement) as early as possible and to care intensively after operation for thoracic aortic aneurysm complicated with cardiac tamponade.

Adolescent↗

PubMed2001

Phosphatidylinositol 3-kinase signaling controls levels of hypoxia-inducible factor 1.

The phosphatidylinositol 3-kinase (PI3K) signaling pathway has inherent oncogenic potential. It is up-regulated in diverse human cancers by either a gain of function in PI3K itself or in its downstream target Akt or by a loss of function in the negative regulator PTEN. However, the complete consequences of this up-regulation are not known. Here we show that insulin and epidermal growth factor or an inactivating mutation in the tumor suppressor PTEN specifically increase the protein levels of hypoxia-inducible factor (HIF) 1alpha but not of HIF-1beta in human cancer cell lines. This specific elevation of HIF-1alpha protein expression requires PI3K signaling. In the prostate carcinoma-derived cell lines PC-3 and DU145, insulin- and epidermal growth factor-induced expression of HIF-1alpha was inhibited by the PI3K-specific inhibitors LY294002 and wortmannin in a dose-dependent manner. HIF-1beta expression was not affected by these inhibitors. Introduction of wild-type PTEN into the PTEN-negative PC-3 cell line specifically inhibited the expression of HIF-1alpha but not that of HIF-1beta. In contrast to the HIF-1alpha protein, the level of HIF-1alpha mRNA was not significantly affected by PI3K signaling. Vascular endothelial growth factor reporter gene activity was induced by insulin in PC-3 cells and was inhibited by the PI3K inhibitor LY294002 and by the coexpression of a HIF-1 dominant negative construct. Vascular endothelial growth factor reporter gene activity was also inhibited by expression of a dominant negative PI3K construct and by the tumor suppressor PTEN.

Androstadienes↗

PubMed2001

Retrospective study of mechanical ventilation in treating multiple trauma accompanied with craniocerebral injury.

OBJECTIVE: To explore the importance of mechanic al ventilation (MV) in treating multiple trauma mainly accompanied with cerebral injury and improve the treatment level. METHODS: All 116 patients who suffered from multiple trauma accompanied with mainly cerebral injury were analyzed. Rank correlation and Chi-square test were made between MV with GCS, ISS, and whether shock or not. RESULTS: The MV was correlated with GCS, ISS scores, and whether shock or not markedly. Furthermore, when GCS or=35, the ratio of MV was about 85%. CONCLUSIONS: During the treatment of multiple trauma accompanied with cerebral injury, the principle of "early MV, early withdraw" and "individualism" should be insisted on. For patients accompanied with shock, the optimum PEEP is very important. Proper and active MV is of great importance and can improve the treatment level markedly.

Adolescent↗

PubMed2001

Homology Modeling of Bacillus subtilis Tryptophanyl-tRNA Synthetase.

Tryptophanyl-tRNA synthetase (TrpRS) plays a pivotal role in protein synthesis. However, till now no stereostructural data of Bacillus subtilis TrpRS were reported. Here, by using the homology modeling using Bacillus stearothermophilus TrpRS as a template, it is demonstrated that the synthetase has 16alpha helices and 5beta sheets. The only tryptophan Trp(92) is located on the interface of subunits. Also the modeling presents the ligand binding site, active site and the putative binding of tRNA(Trp).

Journal Article↗

PubMed2001

[The analysis of rice total RNA by capillary electrophoresis].

When the RNase was eliminated through backing at 200 degrees C or treated by diethylpyrocarbonate (DEPC), the total RNA of rice could be separated within 15 min using 1.0%T, 0%C linear polyacrylamide as sieving matrix and 7 mol/L urea as denaturant. The tRNA of rice can be separated into two classes and about nine peaks when high concentrated polyacrylamide sieving matrix (5.0%T, 0%C) was used. This technique could provide one of the rapid and accurate methods for the determination of RNA in plants.

English Abstract↗

PubMed2001

[Synchronal ossicular chain reconstruct of chronic suppurative otitis media surgery (389 cases analyze)].

OBJECTIVE: To discuss the best material and operation style of synchronal ossicular chain reconstruct for chronic suppurative otitis media patients. METHOD: Review and analyze the effect of ossicular chain reconstruct in 389 cases with chronic suppurative otitis media after surgery. RESULT: The result of hearing improve of macro-tympanum III mould of ossicular chain reconstruct with artificial ossicle was better than other materials and operation types. The outcome of hearing improvement of incudostapedial joint reconstruct was better than the group of macrotympanum III mould of ossicular chain reconstruct with aritificial ossicle. CONCLUSION: The result of hearing improvement of macro-tympanum III mould of ossicular chain reconstruct with aritificial ossicle was better than other material and operation types. The effect of aritificial ossicle better than self-ossicle in ossicular chain reconstruct surgery.

Adult↗

PubMed2001

[Value of regional intra-arterial induction chemotherapy for locally advanced nasopharyngeal carcinoma].

OBJECTIVE: To define the value of regional intra-arterial induction chemotherapy for locally advanced nasopharyngeal carcinoma (NPC). METHODS: 121 locally advanced NPC(stage III-IV) patients confirmed by pathology were randomly divided into two groups before radiation, and the two groups were given two different methods of chemotherapy: regional intra-arterial chemotherapy (IACT) and systemic chemotherapy (SCT). After radiation the effect of two methods was compared. RESULTS: The complete response rates were 27.9% in the IACT and 11.7% in the SCT, and 5 years survival rates were 63.9% in the IACT and 45.0% in the SCT respectively. The differences of two groups were significant. CONCLUSION: IACT is more reasonable than SCT as induction chemotherapy for these locally advanced NPC.

Adolescent↗

PubMed2001

Flashlamp-pumped pulsed dye laser in treatment of port-wine stains.

OBJECTIVE: To assess the effectiveness of the flashlamp-pumped pulsed dye laser (Photogeneca V, Synosure Corp, Boston, United States) in the treatment of port-wine stains. METHODS: One hundred and ninety-four consecutive patients with port-wine stains were treated with a flashlamp-pumped pulsed dye laser in Peking Union Medical College Hospital from January 1998 to August 1999. RESULTS: Of 194 patients who completed treatment, 56.2% had more than 60% fading of the lesion and only 6.7% had less than 20% fading. An average of 3.6 treatments were needed to achieve more than 60% fading. The response was better in children than in adults, although the difference was not significant. Pigmentary change (usually transient) occurred in 3.1% of patients. CONCLUSIONS: This study confirms the efficacy of the flashlamp-pumped pulsed dye laser in the treatment of port-wine stains in children and adults.

Adolescent↗