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Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

At least 181 records · Page 10Linked to original sources
PubMed2005

Expression and immunoactivity of chimeric particulate antigens of receptor binding site-core antigen of hepatitis B virus.

AIM: To improve the immunogenicity of receptor binding site of hepatitis B virus (HBV) on preS1 antigen using HBV core antigen as an immuno-carrier. METHODS: One to 6 tandem copies of HBV preS1 (21-47) fragment were inserted into HBcAg at the sites of aa 78 and 82, and expressed in E.coli. ELISA, Western blot and animal immunization were used to analyze the antigenicity and immmunogenicity of purified particulate antigens. The ability to capture HBV by antibodies elicited by chimeric particles was detected with immuno-capture PCR. RESULTS: Recombinant antigens CI, CII, CIII carrying 1-3 copies of HBV preS1 (21-47) individually could form virus-like particles (VLPs), similar to HBcAg in morphology. But recombinant antigens carrying 4-6 copies of HBV preS1 (21-47) were poorly expressed in E.coli. Chimeric antigens were lacking of immunoreactivity with anti-HBc monoclonal antibodies (McAbs), but still reserved good immunoreactivity with anti-HBe McAbs. CI, CII, CIII could strongly react with anti-preS1 McAb, suggesting that preS1 (21-47) fragment was well exposed on the surface of chimeric VLPs. Three chimeric VLP antigens (CI, CII and CIII) could stimulate mice to produce high-level antibody responses, and their immunogenicity was stronger than non-particulate antigen 21-47*6, containing 6 copies of preS1 (21-47). Mouse antibodies to CI, CII and CIII were able to capture HBV virions in immuno-capture PCR assay in vitro. CONCLUSION: Chimeric particulate antigens of receptor binding site-core antigen of HBV can elicit strong antibody responses to preS1. They have a potential to be developed into prophylactic or therapeutic vaccines against HBV infection.

Animals↗
PubMed2005

Isolation and characterization of neural stem cells from human fetal striatum.

This paper described that neural stem cells (hsNSCs) were isolated and expanded rapidly from human fetal striatum in adherent culture. The population was serum- and growth factor-dependent and expressed neural stem cell markers. They were capable of multi-differentiation into neurons, astrocytes, and oligodendrocytes. When plated in the dopaminergic neuron inducing medium, human striatum neural stem cells could differentiate into tyrosine hydroxylase positive neurons. hsNSCs were morphologically homogeneous and possessed high proliferation ability. The population doubled every 44.28h and until now it has divided for more than 82 generations in vitro. Normal human diploid karyotype was unchanged throughout the in vitro culture period. Together, this study has exploited a method for continuous and rapid expansion of human neural stem cells as pure population, which maintained the capacity to generate almost fifty percent neurons. The availability of such cells may hold great interest for basic and applied neuroscience.

Astrocytes↗
PubMed2005

Fabrication and optical property of silicon oxide layer coated semiconductor gallium nitride nanowires.

Quasi one-dimensional GaN-SiO(2) nanostructures, with a silicon oxide layer coated on semiconductor GaN nanowires, were successfully synthesized through as-synthesized SiO(2) nanoparticles-assisted reaction. The experimental results indicate that the nanostructure consists of single-crystalline wurtzite GaN nanowire core, an amorphous SiO(2) outer shell separated in the radial direction. These quasi one-dimensional nanowires have the diameters of a few tens of nanometers and lengths up to several hundreds of micrometers. The photoluminescence spectrum of the GaN-SiO(2) nanostructures consists of one broad blue-light emission peak at 480 nm and another weak UV emission peak at 345 nm. The novel method, which may results in high yield and high reproducibility, is demonstrated to be a unique technique for producing nanostructures with controlled morphology.

Gallium↗
PubMed2005

Fast separation of single-stranded oligonucleotides by capillary electrophoresis using OliGreen as fluorescence inducing agent.

The fast separation of oligonucleotide (oligos) sizing marker by CE using OliGreen and including effects due to the concentration of separation medium and urea denaturant is presented. OliGreen dye is found to be more sensitive than ethidium bromide (by a factor of about 6 based on S/N considerations) for the oligos' separations. Higher concentration of F127 in 1xTris-boricacid-EDTA (TBE) up to 30% w/v leads to better resolution of oligos separations. The addition of urea into the separation medium decreases the sensitivity. With an optimized running condition, the oligos sizing marker could be successfully separated with 1-base resolution within 1.3 min by using 30% w/v F127/1xTBE solution as the separation medium at an applied electric field of 800 V/cm in a 3 cm long capillary, the fastest capillary gel electrophoresis separation with high resolution reported to date for oligos in the similar size range.

Buffers↗
PubMed2005

Simulation study of breast tissue hemodynamics during pressure perturbation.

We simulated the effects of compression of the breast on blood volume and tissue oxygenation. We sought to answer the question: how does the compression during breast examination impact on the circulatory systems of the breast tissue, namely blood flow, blood pooling, and oxygen concentration? We assumed that the blood was distributed in two compartments, arterial and venous. All the parameters were expressed with oxy- and deoxyhemoglobin quantities and were measured with a non-invasive method, Near Infrared Spectroscopy (NIRS). The simulated data showed that the blood volume pool in the breast decreased due to lower arterial flow and higher venous outflow, as the breast was squeezed under 100 cm H2O with a 10 cm diameter probe (or 78 cm2). The blood volume was reversed when the pressure was released. The breast venous oxygen saturation dropped, but overall tissue saturation (presenting NIRS signal, volume weighted average saturation) was increased. The results showed that simulation can be used to obtain venous and average oxygen saturation as well as blood flow in compressed breast tissues.

Blood Volume↗
PubMed2005

Dietary stearic acid and risk of cardiovascular disease: intake, sources, digestion, and absorption.

Individual FA have diverse biological effects, some of which affect the risk of cardiovascular disease (CVD). In the context of food-based dietary guidance designed to reduce CVD risk, fat and FA recommendations focus on reducing saturated FA (SFA) and trans FA (TFA), and ensuring an adequate intake of unsaturated FA. Because stearic acid shares many physical properties with the other long-chain SFA but has different physiological effects, it is being evaluated as a substitute for TFA in food manufacturing. For stearic acid to become the primary replacement for TFA, it is essential that its physical properties and biological effects be well understood.

Cardiovascular Diseases↗
PubMed2005

Breast cancer detection based on incremental biochemical and physiological properties of breast cancers: a six-year, two-site study.

RATIONALE AND OBJECTIVES: To demonstrate that near-infrared spectroscopy would achieve sufficient sensitivity and specificity in human breast cancer to reach ROC/AUC values in the 90s and yet to warn of the potential liabilities of introduction of a novel technology in this field. MATERIALS AND METHODS: 116 subjects from two nations (44 were cancer-verified by biopsy and histopathology) were reviewed. NIR spectroscopy of total hemoglobin and its relative oxygenation were monitored in breast cancers and compared to their contralateral breast in a 2D nomogram for diagnostic evaluation. A novel handheld NIR breast cancer detector pad with a 3-wavelength LED and 8 detectors with 4 cm separation between source and detectors was placed on the subject's breast. The method is convenient, rapid, and safe and has achieved high patient compliance with minimal patient apprehension of compression, confinement, or radioactivity. RESULTS: The absorbance increments of the cancerous region are referred to the mirror image location on the contralateral breast. The two metrics are increased hemoglobin concentration due to angiogenesis and decreased hemoglobin saturation due to hypermetabolism of the cancer. The 2D nomogram display of these two metrics shows Zone 1 contains verified cancers and Zone 2 contains noncancers. ROC evaluation of the nomogram gives 95% AUC for the two sites, Philadelphia and Leipzig. CONCLUSION: A simple, economical breast cancer detector has achieved high patient compliance and a high ROC/AUC score for a population which involved a range of tumors down to and including those of 0.8-1 cm in diameter.

Area Under Curve↗
PubMed2005

Maternal pre-pregnancy overweight and obesity and the risk of cesarean delivery in nulliparous women.

PURPOSE: To examine the effect of maternal pre-pregnancy overweight and obesity on the risk of term cesarean delivery in nulliparous women. METHODS: The authors examined data from 641 nulliparous women with a term pregnancy that participated in the Pregnancy, Infection, and Nutrition Study from 1995 to 2002. Unadjusted and adjusted risk ratios and 95% confidence intervals (CI) were computed for normal weight (BMI 19.8-26.0 kg/m(2)), overweight (BMI 26.1-29.0 kg/m(2)), and obese (BMI>29.0 kg/m(2)) women. Normal weight women served as the referent population. RESULTS: The unadjusted risk ratio for cesarean delivery for overweight women compared with normal weight women was 1.4 (95% CI, 0.97, 2.1) and for obese women compared with normal weight women was 1.4 (95% CI, 1.03, 2.0). After controlling for maternal height, education, weight gain during pregnancy, and labor induction, the adjusted risk ratio for cesarean delivery among overweight women was 1.2 (95% CI, 0.8, 1.8). The adjusted risk ratio for obese women was 1.5 (95% CI, 1.05, 2.0). CONCLUSION: Our analysis confirms that there is a moderate association between maternal pre-pregnancy obesity and an unplanned term cesarean delivery. However, the risk is not as large as previously reported.

Adolescent↗
PubMed2005

Natural polyelectrolyte films based on layer-by layer deposition of collagen and hyaluronic acid.

The aim of the present work was to assemble extracellular matrix components into polyelectrolyte multilayers using the layer-by-layer deposition method. The films are constructed with type-I collagen and hyaluronic acid. The construction exhibits the general features observed during polyelectrolyte multilayer buildup: alternate positive and negative values of the zeta potential of the film during its construction and regular increase of the film thickness with the number, n, of deposition step. This increase is shown to be linear with n. As expected for a linearly growing film, the confocal microscopy shows that when the film is brought in contact with a collagen solution, collagen does not diffuse into the film but interacts only with its outer layer. However, the films are not constituted of homogeneously distributed polyanion/polycation complexes as it is usually observed, but they are formed of fibers as imaged by AFM. The typical width of these fibers increases with the number of deposition steps. Finally, it is found that chondrosarcoma cells spread well and synthesize extracellular matrix components only on the collagen ending films, whereas no cellular matrix was found for HA ending ones. Such architectures may be further functionalized by inclusion of active drugs, peptides, proteins..., and could be used as tunable biomaterial interfaces.

Biocompatible Materials↗
PubMed2005

Concentration of depot medroxyprogesterone acetate and pain scores in adolescents: a randomized clinical trial.

A prospective, single-blinded, randomized trial was initiated to determine whether injection site pain differed in adolescents receiving two concentrations of 150 mg of depot medroxyprogesterone acetate (DMPA). Ninety-five adolescents seeking injectable contraception were randomized to receive 150 mg of DMPA as follows: a deltoid injection of 1.0 mL from a single-unit-dose vial containing 150 mg/mL or 0.38 mL from a multidose vial containing 400 mg/mL of DMPA. A visual analogue scale was measured at each visit and cumulatively compared between the groups. Continuation rates were tabulated. The report of pain for the multidose vial group was significantly higher than for the unit-dose vial group (p<.003). The dropout rates for both groups were high at 1 year and were not statistically different (multidose group=64% and unit-dose group=77%). Twenty percent of the subjects in the multidose group vs. 22% in the unit-dose group discontinued due to bleeding irregularities. The concentrated form of DMPA led to greater pain at the injection site than did the less concentrated form, but this did not lead to higher discontinuation rates among adolescents.

Adolescent↗
PubMed2005

DDT serum concentration and menstruation among young Chinese women.

High DDE and DDT concentrations were found to be associated with shortened menstrual cycle length in Laotian immigrants to the United States. We examined this issue in a sample of young Chinese women. A total of 60 women aged 20-24 years were enrolled in three maternal and child health clinics (20 from urban, 20 from suburban, 20 from rural) in Shanghai, China, and vicinity, in 1998. Of these women, 47 who did not use hormonal contraceptives and had valid menstrual cycle characteristics were included in the analysis for associations among serum DDE and DDT concentration and menstrual cycle length, duration of menses, and heaviness of menstrual flow. In univariate analysis, higher p,p'-DDE concentration was associated with longer menstrual cycle length (0.66 day per 10 microg/L, 95% confidence interval [CI]: 0.21, 1.11 day). With adjustment for age, body mass index, education, occupation, and resident location, the estimate was 0.42 day (95% CI: -0.35, 1.19 day). p,p'-DDE was not associated with duration of menses or heaviness of menstrual flow. Neither p,p'-DDT nor o,p'-DDT were associated with menstrual cycle length, duration of menses or heaviness of menstrual flow. The study largely suggests no association between DDE and DDT concentrations and menstrual cycle characteristics in young Chinese women, though the weak-to-no correlation of DDE with menstrual cycle length merits further study.

Adult↗
PubMed2005

Synthesis and in vivo evaluation of [11C]PJ34, a potential radiotracer for imaging the role of PARP-1 in necrosis.

Poly(ADP-ribose) polymerase-1 (PARP-1) is an abundant nuclear enzyme of eukaryotic cells that has been implicated in response to DNA injury. PARP-1 detects single-strand DNA breaks induced by a variety of genotoxic insults. A hyperactivation of PARP-1 is believed to play a critical role in tissues undergoing cellular death by necrosis. Therefore, a radiotracer that could image PARP-1 levels with PET could provide a useful tool in measuring necrosis in a variety of pathological conditions. The phenanthridinone derivative, 2-(dimethylamino)-N-(5,6-dihydro-6-oxophenanthridin-2-yl)acetamide (PJ34), has a high affinity for PARP-1 (IC(50) = 20 nM) and is a suitable lead compound for PET radiotracer development. The synthesis of [(11)C]PJ34 was accomplished by base-catalyzed reaction of the corresponding des-methyl precursor, N-(5,6-dihydro-6-oxophenanthridin-2-yl)-2-(methylamino)acetamide with [(11)C]methyl iodide in DMF. The radiolabeling yield was 60% and the specific activity was approximately 2000 mCi/micromol (decay corrected to E.O.B.). The total radiosynthesis time was approximately 50 min. Preliminary in vivo biodistribution studies in a rodent model of diabetes indicate that [(11)C]PJ34 displays a high uptake in tissues where PARP-1 is hyperactivated. These data indicate that [(11)C]PJ34 may be a useful radiotracer for imaging tissues undergoing cellular death via necrosis.

Animals↗
PubMed2005

Retroperitoneal laparoscopic dismembered pyeloplasty: experience with 50 cases.

OBJECTIVES: To report our techniques and experience with retroperitoneal laparoscopic dismembered pyeloplasty for ureteropelvic junction (UPJ) obstruction. METHODS: From May 2000 to September 2004, 50 patients with UPJ obstruction underwent laparoscopic dismembered pyeloplasty. A three-port, balloon-dissecting, retroperitoneal approach was used. All anastomoses were completed with free-hand intracorporeal suture techniques. Follow-up studies were performed with intravenous urography and renal ultrasonography. RESULTS: All operations were completed laparoscopically, and no open conversions were required. The mean operating time was 81.6 minutes (range 55 to 180). The mean blood loss was 12 mL (range 5 to 50), and the mean postoperative hospitalization stay was 7.6 days (range 6 to 12). No intraoperative complications occurred. Aberrant artery vessel and primary stricture as the cause of UPJ obstruction was noted in 6 and 44 patients, respectively. Anastomotic leakage occurred in 2 patients, 1 of whom later underwent open surgery for recurrent UPJ obstruction. Radiographic assessment by intravenous urography showed good results in 49 patients at a mean follow-up of 22 months. CONCLUSIONS: Our experience with retroperitoneal laparoscopic dismembered pyeloplasty has demonstrated that this technique is an effective treatment for UPJ obstruction and can be accomplished reasonably quickly.

Adolescent↗
PubMed2005

Successful treatment of experimental autoimmune myocarditis by adenovirus-mediated gene transfer of antisense CIITA.

Experimental autoimmune myocarditis (EAM) has been used as a model for human myocarditis in relation to the autoimmune mechanism and proved as a T cell-mediated autoimmune disease. Interaction of T cell receptors (TCR) with its ligand peptide-MHC complex on APCs is critical for antigen-specific T cell activation under physiological and pathological conditions. CIITA is a transcriptional coactivator that functions as a key regulatory factor for MHC-II expression. To achieve effective inhibition of interaction of TCR and peptide-MHC-II complex, adenovirus vectors containing antisense CIITA were constructed and their effects in preventing EAM were examined. Ad-CIITA was injected intravenously into mice on days 0-2 or 14-16 after myosin immunization to study the preventive effects on EAM in the T cell activation phase or inflammatory phase. Disease severity was determined by the microscopic grade of heart check, concentration of plasma cTnI, and cellular and humoral immune responses on day 21. Results show that onset of EAM after Ad-CIITA treatment on days 0-2 was almost completely inhibited and antigen-specific lymphocyte proliferation was significantly reduced in adenovirus treatment group, which demonstrate that this adenovirus vector inhibit auto-responsive T cells activation and proliferation. Moreover, compared with EAM mice, even administered on days 14-16, the Ad-CIITA treated mice achieved significant reduction in disease severity. It indicates the therapeutic potential of blocking T cells activation by gene-transfer in myocarditis.

Adenoviridae↗
PubMed2005

Three-dimensional model on thermal response of skin subject to laser heating.

A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank-Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.

Animals↗
PubMed2005

Terpene alkaloids from Tripterygium wilfordii.

Two new sesquiterpene alkaloids, 1beta-hydroxy-2beta,5alpha,11-triacetoxy-7beta-nicotinoyl-8beta-benzoyl-dihydroagarofuran, and 1beta,5alpha,11-triacetoxy-7beta-nicotinoyl-8beta-benzoyl-dihydroagarofuran were isolated from the xylem of Tripterygium wilfordii, together with six known compounds. Their structures were elucidated on the basis of spectroscopic studies.

Molecular Structure↗
PubMed2005

Cocaine increases human immunodeficiency virus type 1 neuroinvasion through remodeling brain microvascular endothelial cells.

Cocaine is a suspected cofactor in human immunodeficiency virus (HIV)-associated dementia but cocaine's effects are not clear. Herein the authors describe investigations of the mechanisms by which cocaine increases HIV-1 invasion through brain microvascular endothelial cells (BMVECs). Cocaine binds to a site on BMVECs, which is not a biogenic amine transporter, a binding site for estrogen, or a muscarinic receptor and for which benztropine and tamoxifen have the highest affinity. Cocaine treatment of BMVECs disrupts intercellular junctions and induces cell ruffling, which could account for their increased permeability and decreased electrical resistance. HIV-1 enters BMVECs by macropinocytosis and is transported to lysosomes and inactivated. In cocaine-treated BMVECs, the virus enters and persists in large cytoplasmic "lakes." Cocaine exposure of BMVECs up-regulates transcription of genes important in cytoskeleton organization, signal transduction, cell swelling, vesicular trafficking, and cell adhesion. The toxicity of cocaine for the blood-brain barrier may lead to increased virus neuroinvasion and neurovascular complications of cocaine abuse.

Blood-Brain Barrier↗