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Biomedical subjects

Kun Wang

Publications and source records attributed to Kun Wang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Doxycycline-regulated co-expression of GDNF and TH in PC12 cells.

Current gene therapy models for Parkinson's disease (PD) have adapted two treatment strategies. One is to restore dopamine (DA) production by delivering the genes of DA-synthesizing enzymes such as tyrosine hydroxylase (TH) to the striatum to relieve motor symptoms of PD. Another is to block or slow down progressive degenerative changes by delivering neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF) to protect the remained neurons. To test the assumption that the combination of the two strategies may have a compound or synergistic effect, we had constructed tetracycline-inducible (tet-off) AAV vector carrying GDNF and TH. After co-transfection of PC12 cells with this vector and the inducer plasmid, the expression of GDNF and TH protected these cells from 1-methyl-4-phenyl-pyridinium-induced injury, and significantly increased the content of dopamine in GDNF/TH-expressing cells compared with the control. Furthermore, mRNA expression of GDNF and TH could be effectively and reversibly regulated by doxycycline (Dox) and the function of GDNF and TH could be repressed by Dox. These results suggest that the tet-off AAV vector carrying GDNF and TH may be a useful tool for gene therapy in the treatment of PD.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2006

Association of nonalcoholic fatty liver disease with abnormal aminotransferase and postprandial hyperglycemia.

GOALS: This study was conducted to explore the association between nonalcoholic fatty liver disease and glucose metabolism as well as insulin resistance using the homeostasis model assessment method (HOMA). STUDY: From July 2003 to June 2004, 23 patients with ultrasound-proved fatty liver and either normal (10 patients) or abnormal (13 patients) serum aminotransferase levels were enrolled. Blood tests included a routine biochemistry, a 75-g glucose oral glucose tolerance test (OGTT) with blood sampled at 30-minute intervals during a 120-minute period. Fasting and 120-minute serum leptin, insulin, and C-peptide concentrations were also measured. RESULTS: Using the Mann-Whitney U test, significant differences were found in gamma glutamyl transpeptidase (28.6+/-7.9 vs. 65.1+/-65.9 U/L, P=0.008), fasting insulin (FI) (13.11+/-7.53 vs. 31.76+/-42.95 muU/mL, P=0.02), fasting C-peptide (3.82+/-3.00 vs. 2.17+/-0.43 ng/mL, P=0.01), fasting leptin (10.34+/-4.05 vs. 24.27+/-24.97 ng/mL, P=0.01), HOMA-IR (3.34+/-1.06 vs. 8.81+/-13.18, P=0.02), and HOMA beta-cell function (120.32+/-52.50 vs. 242.20+/-247.29, P=0.02) between normal and abnormal ALT/AST function groups. From the 75-g OGTT, no significant difference of plasma glucose was noted at 0, 30, 60, and 90 minutes but significant change was noted in 120-minute plasma glucose (99.3+/-21.5 vs. 131.4+/-27.3 mg/dL, P=0.004) of 2 groups. CONCLUSIONS: In conclusion, patients with fatty liver proved by ultrasound sonography might be at high risk of developing type 2 diabetes, especially when they had elevated liver enzymes. OGTT is warranted for the early diagnosis of these high risk patients.

Adult↗
PubMed2006

Baculovirus-mediated gene expression in chicken primary cells.

A recombinant baculovirus was constructed containing an expression cassette with a reporter gene, green fluorescent protein, directed by a constitutive mammalian promoter: a human cytomegalovirus immediate early promoter/enhancer (CMV-IE). High titer virus was prepared with ultracentrifugation. Efficient gene delivery and expression were observed in the virus-treated chicken primary culture, myoblast cells, and whole embryonic fibroblast cells. It was noticed that an addition of sodium butyrate (a selective histone deacetylase inhibitor) to viral transduction medium extremely enhanced the reporter-gene expression. However, there is no effect of presence of trichostatin A observed. To maximize the reporter-gene expression, the baculoviral infection condition was optimized with both cell types. Our approaches demonstrated that recombinant baculovirus could efficiently deliver its genome DNA into chicken primary cells and that CMV-IE, a mammalian-cell-active promoter, was functional in chicken primary cells and could direct a high level of gene expression. Clearly, the recombinant baculovirus provides an alternative means for foreign gene delivery into avian cells.

Animals↗
PubMed2006

Computational approaches to model ligand selectivity in drug design.

To be effective, a designed drug must discriminate successfully the macromolecular target from alternative structures present in the organism. The last few years have witnessed the emergence of different computational tools aimed to the understanding and modeling of this process at molecular level. Although still rudimentary, these methods are shaping a coherent approach to help in the design of molecules with high affinity and specificity, both in lead discovery and in lead optimization. It is the purpose of this review to illustrate the array of computational tools available to consider selectivity in the design process, to summarize the most relevant applications, and to sketch the challenges ahead.

Amino Acid Sequence↗
PubMed2006

[Influence of bicortical anchorage on the natural frequencies of dental implant].

OBJECTIVE: To investigate the influences of bicortical anchorage on values of natural frequencies of dental implants utilizing the 3-dimensional finite element analysis. METHODS: Using the commercial code of Solidworks, 3-D models of a screw-shaped dental implant and a mandibular bone segment were generated. After the 3-D implant-bone complex was meshed by ABAQUS software, effects of bicortical anchorage on the buccolingual and axial first-order natural frequencies of the implant were computed. RESULTS: Bicortical anchorage increased both the buccolingual and axial natural frequencies remarkably. As the bicortical anchorage got deeper, the frequencies correspondingly got higher. CONCLUSION: Bicortical anchorage can increase the buccolingual and axial primary stability of dental implants.

Dental Implantation, Endosseous↗
PubMed2006

[Isolation, culture, identification and biological characteristics of chicken skeletal muscle satellite cells].

Chicken skeletal muscle satellite cells were obtained by a two-step method of collagenase-I and trypsin digestion, followed by in vitro culture. They were further identified by specific gene expression assays. In addition, cell biological characteristics and myogenic genes expression were analyzed. Results showed that satellite cells from chicken skeletal muscle tissue expressed pax7, desmin, and possessed ability to proliferate and differentiate. The technical platform was established to study the mechanism of myogenic proliferation, differentiation and muscle regeneration.

Animals↗
PubMed2006

[Development of a portable glucose meter based on PIC microcomputer].

A portable glucose meter based on PIC microcomputer with data storage, analysis and historical data curve display functions, is presented. The concentration of blood glucose is detected with a glucose oxidase electrode. Test records may be stored and historic data can be displayed on the LCD with a fitting curve.

Blood Glucose Self-Monitoring↗
PubMed2006

[Degradation of antigen-extracted meniscus in vitro].

OBJECTIVE: To study degradation of the antigen-extracted meniscus in PBS solution with no enzyme or with different enzymes. METHODS: Four types of enzymes (collagenase, hyaluronidase, trypsin, papain) were used to enzymolyze the antigen-extracted meniscus and the fresh meniscus for 3, 7, 15 and 30 days (37 degrees C). The antigen-extracted meniscus and the fresh meniscus were immersed in PBS solution (37 degrees C) for 30 days. Weight loss measurement, UV spectrophotometry, and scanning electron microscopy (SEM) were used to characterize the degraded materials. RESULTS: The two types of the materials were remarkably digested under the enzymes, especially under trypsin. The degradation curves showed that the antigen-extracted meniscus was enzymolyzed less than the fresh meniscus. The degradation products were grouped as amino, peptide, and polycose by the analysis. Both of the materials could hardly be hydrolyzed in PBS solution without the enzymes. The four different enzymes had different surface morphologies under the examination of SEM. CONCLUSION: The antigen-extracted meniscus is enzymolyzed more slowly than the fresh meniscus in vitro, and the result can be used as a guideline to the further research.

Animals↗
PubMed2006

[Dynamics of soluble sugar and endogenous hormone contents in several steppe grass species during their germination period in spring].

The study on the dynamics of soluble sugar and endogenous hormone contents in steppe grass species Elymus sibiricus, E. rectisetus, Leymus chinensis, L. racemosu and Stipa krylovii during their germination period in spring showed that high content GA and low content ABA played an important role for L. chinensis and L. racemosus germination, and the abundant soluble sugar storage in root made the rhizome grasses germinate earlier and grow stronger. The dynamics of ribosylzeatin was similar with that of soluble sugar in root, i.e., declined in early germination period, reached the lowest by the end of April, and ascended then, while the IAA and GA contents had a similar variation trend with the soluble sugar content in bud, i.e., all ascended gradually. There was a significant difference in the contents of GA, ABA and soluble sugar between rhizome grasses L. chinensis and L. racemosus and fibrous-root grasses E. sibiricus and E. rectisetus.

Adenosine↗
PubMed2006

[Clinicopathological features of solid pseudopapillary tumor of the pancreas].

OBJECTIVE: To elucidate the clinicopathological features of solid pseudopapillary tumor (SPT) of the pancreas. METHODS: Eight patients with SPT of the pancreas admitted from August 1996 to March 2005 were retrospectively analyzed. RESULTS: All the 8 patients were female with an average age of 25.3 (13-41) years. The primary clinical manifestations included abdominal mass (n = 3), vague abdominal pain (n = 3), and duodenal obstruction (n = 1). SPT was occasionally found in one patient during physical examination. Six tumors located at the head and the other two in the body and tail of the pancreas. Pancreaticoduodenectomies were performed in 4 patients, tumor enucleations in 2, distal pancreatectomies in 1, and palliative internal drainage with a cystoenterotomy in the other one with an unresectable huge cystic lesion. All patients were alive on an average follow-up of 37.8 (8-103) months. CONCLUSION: SPT occurs mainly in adolescent and young females, and satisfactory outcome may be achieved with active and appropriate surgeries.

Adolescent↗
PubMed2006

[Improvement of two-dimensional gel electrophoresis of total proteins from rice anthers].

This paper reported an improvement in 2-D gel electrophoresis of the proteome in Honglian cytoplasmic male sterile rice. An IPGphor unit with immobile pH gradient strips was used as the first dimension and SDS-PAGE as the second. The total anther proteins were extracted using TCA/acetone and then were washed 5-6 times with acetone till the proteins were white and clean, and then tributylphosphine and DTT were added into the rehydration buffer to improve the solubility of the proteins. The 2-D gel was stained by both methods of coomassie blue G-250 and silver. Extraction of proteins, pH of the strips and rehydration of the strips were optimized and compared. Higher repeatability and better separating protein pattern could be gained by this technique.

Electrophoresis, Gel, Two-Dimensional↗
PubMed2005

[Anxiety and depression related to the symptoms of gastroesophageal reflux disease].

OBJECTIVE: To compare the differences in the psychological scale scoring among different subgroups reflux esophagitis (RE) and non-erosive reflux disease (NERD) and to explore the influence of mental factors on the pathogenesis of RE and NERD. METHODS: Two hundred and six patients with typical heartburn and acid regurgitation underwent endoscopy and esophageal pH monitoring and then were divided into 4 groups: RE+ group (n = 35, 24.3%) with RE and positive pH monitoring results, RH- group (n = 15, 30.0%) with RE and negative pH monitoring results, NERD+ group (n = 77, 40%), with NERD and positive pH monitoring results, and NERD- group (n = 79, 50.6%) with NERD and negative pH monitoring results that was re-divided into 2 subgroups according to the symptom index (SI): NERD-SI+ group (n = 18, 22.8%) with positive symptom index and NERD-SI- group (n = 61, 77.2%) with negative SI. The demographic data and body mass index (BMI) were investigated. The psychological questionnaires: Symptom Checklist 90 (SCL-90), and Hospital Anxiety and Depression Scale (HAD) were used. RESULTS: (1) Male patients were dominant in the RE group and RE+ subgroup, while female patients were dominant in the NERD group and NERD+ subgroup. The values of BMI of the RE group and RE+ subgroup were significantly higher than those of the NERD group and NERD+ subgroup. (2) The abnormal pH monitoring rate of the RE group was 70.0%, significantly higher than that of the NERD group (49.4%). The average DeMeester's score of the RE group was 39.3 (96.5), significantly higher than that of the NERD group 13.8 (33.6). The average DeMeester's score of the RE+ group was 68.1 (95.2), significantly higher than that of the NERD+ group 40.1 (64.4). (3) 44.6% (29/65) of the patients presented depression and 36.9% (24/65) had anxiety, most of them were in mild or moderate degree. The scores of most items of each mental scale were significantly higher in the NERD- patients than in the NERD+ patients, especially in the NERD-SI- subgroup. CONCLUSION: The symptoms of RE+ and NERD+ patients are associated with esophageal acid exposure and the acid reflux in the RE patients is much severer than that in the NERD patients. Anxiety and depression are related to the symptoms of patients without objective evidence of esophageal mucosal injury and acid reflux (NERD-), especially in the symptom index negative subgroup. Visceral hypersensitivity and stress play an important role in the pathogenesis of gastroesophageal reflux.

Adolescent↗
PubMed2005

Activation-coupled inactivation in the bacterial potassium channel KcsA.

X-ray structures of the bacterial K+ channel KcsA have led to unparalleled progress in our understanding of ion channel structures. The KcsA channel has therefore been a prototypic model used to study the structural basis of ion channel function, including the gating mechanism. This channel was previously found to close at near-neutral intracellular pH (pH(i)) and to open at acidic pH(i). Here, we report the presence of a previously unknown channel inactivation process that occurs after the KcsA channel is activated. In our experiments, mammalian cells transfected with a codon-optimized synthetic gene encoding the KcsA protein expressed K+-selective channels that activated in response to a decrease in pH(i). Using patch-clamp and rapid solution exchange techniques, we observed that the KcsA channels inactivated within hundreds of milliseconds after channel activation. At all tested pHs, inactivation always accompanied activation, and it was profoundly accelerated in the same pH range at which activation increased steeply. Recovery from inactivation was observed, and its extent depended on the pH(i) and the amount of time that the channel was inactive. KcsA channel inactivation can be described by a kinetic model in which pH(i) controls inactivation through pH-dependent activation. This heretofore-undocumented inactivation process increases the complexity of KcsA channel function, but it also offers a potential model for studying the structural correspondence of ion channel inactivation.

Animals↗
PubMed2005

Synthesis, antiviral, and antitumor activity of 2-substituted purine methylenecyclopropane analogues of nucleosides.

The Z- and E-2-fluoro- and 2-chloropurine methylenecyclopropanes 9a,b and 10a,b as well as enantiomeric Z-isoguanine methylenecyclopropanes 11a,b and their phenyl phosphoralaninate pronucleotides 11c,d were synthesized and their antiviral activity against several viruses was evaluated. Fluoro analogues 9a and 10a were active against human cytomegalovirus but they were cytotoxic at approximately the same concentrations. Chloro derivatives 9b and 10b were non-cytotoxic and effective against Epstein-Barr virus in Daudi cells. Isoguanine analogues 11a-d lacked antiviral activity but pronucleotides 11c,d were substrates for porcine liver esterase. From the group of 9a,b and 10a,b, the fluoro analogues 9a and 10a exhibited antitumor activity but only the Z-isomer 9a had a selective effect.

Animals↗
PubMed2005

Development and potential of a biomimetic chitosan/type II collagen scaffold for cartilage tissue engineering.

BACKGROUND: Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the supposition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering. METHODS: Chitosan of 88% deacetylation was prepared via a modified base reaction procedure. A freeze-drying process was employed to fabricate a three-dimensional composite scaffold consisting of chitosan and type II collagen. The scaffold was treated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. Ultrastructure and tensile strength of the matrix were carried out to assess its physico-chemical properties. After subcutaneous implantation in rabbits, its in vivo biocompatibility and degradability of the scaffold were determined. Its capacity to sustain chondrocyte growth and biosynthesis was evaluated through cell-scaffold co-culture in vitro. RESULTS: The fabricated composite matrix was porous and sponge-like with interconnected pores measuring from 100-250 microm in diameter. After cross-linking, the scaffold displayed enhanced tensile strength. Subcutaneous implantation results indicated the composite matrix was biocompatible and biodegradable. In intro cell-scaffold culture showed the scaffold sustained chondrocyte proliferation and differentiation, and maintained the spheric chondrocytic phenotype. As indicated by immunohistochemical staining, the chondrocytes synthesized type II collagen. CONCLUSIONS: Chitosan and type II collagen can be well blended and developed into a porous 3-D biomimetic matrix. Results of physico-chemical and biological tests suggest the composite matrix satisfies the constraints specified for a tissue-engineered construct and may be used as a chondrocyte carrier for cartilage tissue engineering.

Animals↗
PubMed2005

A tetracycline-regulatable adeno-associated virus vector for double-gene transfer.

An increasing demand for polycistronic vectors that express multiple genes simultaneously has arisen in recent years to obtain an efficient gene therapy. Armed with the knowledge that the expression of transgene in mammalian cells often requires tight control, we constructed in this study a tetracycline-regulated double-gene adeno-associated virus (AAV) vector carrying green and red fluorescent protein genes and expressed it in PC12 cells. When detected by fluorescence microscope and fluorescence-activated cell sorting, gene expression was induced by 44-66-fold and could be reversibly controlled by doxycycline. This double-gene AAV vector may be useful for regulated expression of two genes or a marker to monitor transgene expression.

Adenoviridae↗
PubMed2005

Long-term outcome of bladder augmentation using living-related partial bladder transplantation in rats.

Long-term histopathologic changes after bladder augmentation (BA) in rats using living-related partial bladder transplantation (LPBTx) or conventional ileocystoplasty (ICP) were compared. In this study, BA (n = 37), LPBTx (n = 18), and ICP (n = 19) were performed in 16-wk-old Lewis rats. Five donors and seven nontransplanted normal Lewis rats (controls) were also studied. Rats that survived >10 mo after BA were killed after blood biochemistry and neobladder imaging. Harvested bladders were examined with hematoxylin and eosin and proliferating cell nuclear antigen (PCNA). When the rats were killed, there were 16 rats in the LPBTx group and 12 rats in the ICP group; ICP rats were significantly smaller than LPBTx rats (p < 0.05). Mean duration of follow-up for the LPBTX group was 17.3 mo, for the ICP group was 13.7 mo, for the donor group was 16.1 mo, and for the control group was 19.7 mo. Mean serum pH in the LPBTx group was 7.41 +/- 0.78 and in the ICP group was 7.25 +/- 0.38. Mean base excess in the ICP group was significantly lower than in the LPBTx group (p < 0.05). Incidence of bladder calculi in the LPBTx group (6.3%) was significantly lower than in the ICP group (33.3%; p < 0.05). There was no dysplasia/malignancy/increase in PCNA in the LPBTx group. PCNA increased in the ICP group, compared with controls (p < 0.05); two (16.7%) of 12 of ICP rats had dysplasia with mitosis. Bladder capacity increased in LPBTx and ICP compared with controls (both p < 0.05). We hope to show that BA using LPBTx may result in a neobladder with fewer complications than BA using ICP; LPBTx may also decrease the risk for malignancy.

Anastomosis, Surgical↗