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Biomedical subjects

Hong Yuan

Publications and source records attributed to Hong Yuan.

36 records · Page 2Linked to original sources
PubMed2005

[Preparation and quality control of low molecular weight chitosan].

OBJECTIVE: To prepare the low molecular weight chitosan (LMWC) and establish the method for quality control. METHOD: Use enzymatic degradation to prepare LMWC with chitosan, and separate by ultrafiltration; the molecular weight and purity were determined by gel permeation chromatography (GPC) and colorimetry respectively. RESULT: LMWC was prepared by control the hours of enzymatic degradation and ultrafiltered through filter with cutoff molecular of 10K Dalton and 50 K dalton; the average molecular weight was 20 K dalton and the purity was (96.60 +/- 1.56)%. CONCLUSION: The condition of enzymatic degradation is geniality and easy to control, LMWCs with different molecular weight can separate by ultrafiltration efficiently; the quality of LMWC can control with gel permeation chromatography (GPC) and colorimetry.

Cellulase↗
PubMed2004

Histological, behavioural and neurochemical evaluation of medial forebrain bundle and striatal 6-OHDA lesions as rat models of Parkinson's disease.

We compared the effect of an injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle (MFB) and into the striatum on different parameters for evaluation of motor dysfunction and dopamine denervation in rats, as a function of time. A combination of behavioural, neurochemical and histological techniques was employed. Amphetamine-induced rotation is shown to provide a first rough estimation of motor impairment. Indeed, the number of rotations observed after amphetamine administration can distinguish between a partial and a near complete (>90%) denervation in the substantia nigra. However, lesion sizes of 50-80% resulted in similar rotational behaviour. Similarly, the elevated body swing test (EBST) can determine severe lesions, but is not sensitive enough in the partial model. In both models, determination of the dopamine tissue content with HPLC is a more precise measure of striatal dopamine innervation than striatal TH-immunostaining. The number of cells estimated by TH- and Nissl-staining correlated well in the striatal model, but there was a discrepancy between both measures in the MFB-lesioned animals. Therefore, additional Nissl-staining is necessary for better estimation of the size of the lesion at the level of the substantia nigra or ventral tegmental area in the severely lesioned animals. The MFB lesion model mimics end-stage Parkinson's disease. The striatal injection of 6-OHDA described here cannot be considered a progressive model, since there was no change in the number of TH-immunoreactive cells in the substantia nigra up to 8 weeks post-lesioning. However, the partial denervation renders its quite suitable for mimicking early stage Parkinson's disease, and is thus suitable for testing possible neuroprotective and neurotrophic drugs.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

Neuroprotective and neurotrophic effect of apomorphine in the striatal 6-OHDA-lesion rat model of Parkinson's disease.

We investigated the possible neuroprotective effect of the dopamine (DA) receptor agonist R-apomorphine (R-APO) within the striatal 6-hydroxydopamine (6-OHDA) rat model of Parkinson's disease. In one group of rats, R-APO administration (10 mg/kg/day, s.c.) started 15 min before 6-OHDA-injection. In a second group, R-APO administration started 24 h after lesion induction. Both groups received R-APO chronically for 11 days. Testing was carried out 2 weeks post-lesioning. R-APO treatment, whether started before or after the lesion induction, significantly reduced both the amphetamine-induced ipsiversive rotation and the size of the lesion at the level of the substantia nigra. Moreover, the dopamine cell shape and size resembled that observed in intact animals. R-APO treatment had no effect on the number of cells in the substantia nigra of intact rats, but significantly increased the number of cells in the ventral tegmental area (VTA), suggesting selective neurotrophic properties of R-APO in this region. R-APO treatment significantly attenuated the 6-OHDA-induced striatal DA depletion and DOPAC/DA ratios were normalized. Finally, an acute injection of 10 mg/kg R-APO was unable to scavenge 6-OHDA or MPP(+)-induced hydroxyl radicals as determined with the in vivo salicylate trapping technique. These data provide further evidence of the neurorescuing properties of R-APO. At least at the dose used in this study, this effect possibly occurs via mechanisms other than scavenging of hydroxyl radicals. In intact rats, we also show neurotrophic effects of the R-APO treatment. These seem to be limited to the VTA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

An intravital microscopy study of radiation-induced changes in permeability and leukocyte-endothelial cell interactions in the microvessels of the rat pia mater and cremaster muscle.

Using intravital microscopy and a closed window method, we measured irradiation-induced changes in the vascular permeability and cell interactions in microcirculation networks of the rat pia mater; the same effects were monitored in the cremaster muscle as a control. The closed cranial window has many advantages, including long-term direct visualization of microcirculation. The method allows for repeated testing of the same vessel or network, thereby reducing variability. The method also allows for measurement of permeability changes and the accompanying leukocyte-endothelial cell interactions in the same network or vessel, which permits correlative studies of these phenomena. However, this method is not without challenges. The optical conditions are difficult, because the brain is three-dimensional and its parenchyma is more complex than the thinner, flatter peripheral tissues. To overcome this limitation, we performed a dynamic background subtraction. The background is dynamically related to vessel intensity, and changes in intensity were determined by eliminating the effects of neighboring and underlying vessels. We applied this method to studying the effects of ionizing radiation on the blood-brain barrier (BBB) permeability and cell interactions and the modulation of these effects by anti-ICAM-1 antibodies. Our results demonstrate that this method is sensitive to changes in these properties of the BBB.

Animals↗
PubMed2004

Resonance light scattering spectroscopy study of interaction between gold colloid and thiamazole and its analytical application.

In this paper, we used resonance light scattering (RLS) spectroscopy to study the interaction between thiol-containing pharmaceutical-thiamazole and gold colloid. At pH 5.2, the resonance light scattering spectrum of gold nanoparticles has a maximum peak at 555 nm and the RLS intensity is enhanced by trace amount of thiamazole due to the interaction between thiamazole and gold colloid. The binding of colloidal gold to thiamazole results in ligand-induced aggregation of colloidal gold, which was characterized by RLS spectrum, ultraviolet-visible (UV-Vis) spectrum, and transmission electron microscopy (TEM). Based upon the study, we proposed a highly sensitive, gold colloid-based assay using RLS spectrum to detect pharmaceuticals for the first time. The mechanism of binding interaction between Au colloid and thiamazole was also discussed.

Absorption↗
PubMed2004

In vivo characterization of somatodendritic dopamine release in the substantia nigra of 6-hydroxydopamine-lesioned rats.

We investigated the effect of an injection of 6-hydroxydopamine (6-OHDA) into the rat medial forebrain bundle (MFB) on the degeneration and the function of the dopaminergic cell bodies in the substantia nigra (SN) 3 and 5 weeks after lesioning. After injection of 6-OHDA into the MFB a complete loss of dopamine content was apparent in the striatum 3 weeks after lesioning. In the SN the amount of tyrosine hydroxylase-immunoreactive dopamine cells decreased gradually, with a near-complete lesion (> 90%) obtained only after 5 weeks, indicating that neurodegeneration of the nigral cells was still ongoing when total dopamine denervation of the striatum had already been achieved. Baseline dialysate and extracellular dopamine levels in the SN, as determined by in vivo microdialysis, were not altered by the lesion. A combination of compensatory changes of the remaining neurones and dopamine originating from the ventral tegmental area may maintain extracellular dopamine at near-normal levels. In both intact and lesioned rats, the somatodendritic release was about 60% tetrodotoxin (TTX) dependent. Possibly two pools contribute to the basal dopamine levels in the SN: a fast sodium channel-dependent portion and a TTX-insensitive one originating from diffusion of dopamine. Amphetamine-evoked dopamine release and release after injection of the selective dopamine reuptake blocker GBR 12909 were attenuated after a near-complete denervation of the SN (5 weeks after lesioning). So, despite a 90% dopamine cell loss in the SN 5 weeks after an MFB lesion, extracellular dopamine levels in the SN are kept at near-normal levels. However, the response to a pharmacological challenge is severely disrupted.

Amphetamine↗
PubMed2004

[Study of the uptake of chitosan oligosaccharide nanoparticles by A549 cells].

AIM: To study the cellular uptake of chitosan oligosaccharide nanoparticles by A549 cells and evaluate the possibility of chitosan oligosaccharide nanoparticles used as a potential drug carrier. METHODS: Chitosan oligosaccharide (CSO) was obtained by ultrafiltration separation after regulation of the condition of chitosanase degradation. The molecular weight of CSO was determined by gel permeation chromatography (GPC). Chitosan oligosaccharide nanoparticles (CSO-NPs) were prepared by a novel solvent diffusion method in an oil system after the carrier material grafted fluorescein isothiocyanate (FITC) and the particle size distribution and zeta potential were determined by light scattering and electrophoretic mobility. The cytotoxicity and uptake of FITC-labeled CSO-NPs in A549 cells following various incubation periods were studied by the MTT method and fluorescence microscopy, flow cytometric analysis, respectively. RESULTS: The molecular weight (MW) of CSO was 18,678 u and the particles sizes of CSO-NPs were 133.3 nm (number average) and 368.2 nm (volume average), respectively. The IC50 of CSO and CSO-NPs were 944.36 and 643.16 mg x L(-1), respectively, and the result showed low cytotoxicity. Cellular uptake of CSO and CSO-NPs were relative to the concentration and the incubation time. Internalization of CSO-NPs increased 0.49 - 13.9 times more than that of the CSO with the same incubation time. CONCLUSION: CSO and CSO-NPs have low cytotoxicity. CSO-NPs can significantly improved the uptake of CSO-NPs by A549 cells compared to the same molecular weight of CSO.

Adenocarcinoma↗
PubMed2004

[Preparation and characterization of stearic acid-grafted chitosan oligosaccharide polymeric micelles].

AIM: To prepare the micelles of stearic acid-grafted chitosan oligosaccharide and investigate the drug release from micelles. METHODS: Mediated by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), stearic acid (SA) was covalently attached to chitosan oligosaccharide (CSO), and the graft polymer (CSO-SA) was obtained. The critical aggregation concentration (CAC) of the CSO-SA was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The effect of various pH dispersed media and concentration of tripolyphosphate sodium (TPP) on the micellar size distribution and zeta-potential measured by light scattering and electrophoretic mobility, was investigated. In buffers of different pH, the release profiles of methotrexate (MTX) from micelles were evaluated. RESULTS: The CAC value of CSO-SA in deionized water was 0.05 g x L(-1). The mean diameter of CSO-SA micelles was 26.7 nm and the zeta potential was (55.9 +/- 0.1) mV. With the increase of TPP concentration, the size and MTX encapsulation of CSO-SA micelles increased, while the zeta-potential decreased. With the decrease of pH value of dispersed media, the size and zeta-potential of CSO-SA micelles increased, and the MTX encapsulation in CSO-SA micelles decreased. While the enhancement of drug release from the micelles was observed. CONCLUSION: The graft polymer of CSO-SA provides polymeric micelles, which possessed a low CAC value in aqueous media. The drug release in vitro from CSO-SA micelles was affected by the pH of delivery media.

Chitosan↗
PubMed2004

[Preparation of rAAV2/hFIX and experimentally application to gene therapy for hemophilia B].

OBJECTIVE: To prepare the rAAV2/hFIX and evaluate the efficiency of the preparation on gene therapy of hemophilia B model mice. METHODS: The rAAV-2/hFIX was prepared by "one helper virus-one vector cell line" strategy and transfected both BHK-21 and C2C12 cells in vitro. The hFIX antigen level in cell culture supernatant was assayed. The rAAV-2/hFIX was injected into muscles of hemophilia B model mice and assayed the serum hFIX levels, hFIX clotting activity, bleeding time, 5 min bleeding volume. RESULTS: The hFIX antigen could be detected from 24 h till 120 h after BHK-21 and C2C12 cells were transfected with highest levels at 24 h reaching (51.0 +/- 6.5) ng/10(5) cells and (68.0 +/- 7.2) ng/10(5) cells, respectively. The rAAV2/hFIX injected mice could efficiently express hFIX and peaked at three weeks after injection, then slowly decreased but low level hFIX antigen was still detectable till 10 weeks after injection. There were significant differences between the high, middle and low dose groups of rAAV2/hFIX and the control group (P < 0.01), the plasma FIX clotting activities in the model mice were improved remarkably, bleeding time was greatly shortened and bleeding in 5 min was decreased. The hFIX expression level and FIX clotting activity of the high dose of rAAV2/hFIX group (1.6 x 10(13) v.g./kg) reached about (387.0 +/- 12.5) ng/ml plasma in contrast with the normal levels of (30.0 +/- 5.5)% at the third week after injection. No rAAV2 vector DNA was detected in the organs except for injected muscle tissue. CONCLUSION: The rAAV2/hFIX transfected BHK-21 and C2C12 cells could efficiently express hFIX antigen and was of therapeutic effects for the hemophilia B model mice by intramuscularly injection.The results provide the basis for clinical trial of rAAV2 gene therapy for hemophilia B.

Animals↗
PubMed2004

[Uptake of monostearin solid lipid nanoparticles by A549 cells].

AIM: To investigate the cellular uptake of monostearin solid lipid nanoparticles (MSLN) and the influence on the cellular uptake by MSLN modified with PEG2000 in human-type II cell alveolar epithelial cell line (A549) and murine macrophages cell line (J774A1). METHODS: MSLN were prepared by a novel solvent diffusion method. The particle size distribution and zeta potential of MSLN, measured by light scattering and electrophoretic mobility, were investigated. The cytotoxicity of MSLN and MTX-loaded MSLN in A549 cells were performed by the MTT method. Rhodamine B was incorporated into solid lipid nanoparticles as fluorescent marker, after PEG2000 integrating monostearin during preparation, the cellular uptake of MSLN by A549 and J774A1 cell lines were determined spectrofluorimetrically. RESULTS: The IC50 of MSLN and MTX-loaded MSLN on A549 cells were 227.56 microg x mL(-1) and 71.37 microg x mL(-1), respectively. The percentage of cellular uptake showed a negative correlation to the concentration of MSLN in incubation medium and the internalization behaved rapidly. Contrary to situation in J774A1 cell line, internalization of solid lipid nanoparticles was promoted with increasing the content of PEG2000 incorporated into MSLN in A549 cell line. CONCLUSION: After modifying MSLN with PEG2000, it represents relative lower phagocytosis by J774A1 cell line and higher uptake in A549 cell line.

Adenocarcinoma↗
PubMed2003

Radiation-induced permeability and leukocyte adhesion in the rat blood-brain barrier: modulation with anti-ICAM-1 antibodies.

We assessed the acute effects of radiation on the rat blood-brain barrier. A cranial window model and intravital microscopy were used to measure changes in permeability and leukocyte adhesion in pial vessels after a localized, single dose of 20 Gy. Permeability was assessed using five sizes of fluorescein isothiocyanate (FITC)-dextran molecules (4.4-, 10-, 38.2-, 70-, and 150-kDa) with measurements performed before and 2, 24, 48, 72 and 96 h after irradiation for the 4.4 and 38.2-kDa molecules and before and 24 h after irradiation for the other three molecules. To demonstrate the nature of blood-brain barrier permeability, we concurrently studied the permeability of microvessels in the cremaster muscle. In both tissues, permeability to FITC-dextran was significantly greater 24 h after irradiation than before (P<0.05). The exception was that radiation did not affect the permeability of pial vessels to the 150-kDa molecule. The particle-size dependence of the permeability changes in the brain were indicative of altered integrity of endothelial tight junctions and occurred concomitantly with an increase in cell adhesion which was determined by fluorescent labeling of leukocytes with rhodamine 6G. An early inflammatory response to irradiation was apparent in the brain 2 h after irradiation. The numbers of rolling and adherent leukocytes increased significantly and peaked at 24 h. Injection with the anti-ICAM-1 mAb significantly reduced leukocyte adhesion and permeability thereby linking the two processes. These findings provide a target to reduce radiation-related permeability and cell adhesion and potentially the side effects of radiation in the CNS.

Animals↗
PubMed2003

[Preparation of solid lipid nanoparticles by solvent diffusion method].

AIM: To establish an efficient method for preparation of solid lipid nanoparticles with high recovery. METHODS: Monostearin solid lipid nanoparticles was prepared by solvent diffusion method in aqueous system. The recovery of the method was greatly improved by adjusting the Zeta potential. RESULTS: The drug-loaded solid lipid nanoparticles suspension was quickly produced and easily separated with centrifugation at 4,000 r.min-1 under acidic condition. Compared with the nanoparticles made without adjusting the Zeta potential, the recovery of nanoparticles prepared in this way was significantly increased. The release behavior in vitro showed an initial burst effect in the first 3 hours followed by a slower rate stage of 4 days with nearly 6% drug released in each day. CONCLUSION: The solvent diffusion method in aqueous system might be used as a new method to prepare solid lipid nanoparticles in the future. The loaded drug can be released in a controlled manner.

Clobetasol↗
PubMed2003

The PLC-PKC cascade is required for IL-1beta-dependent Erk and Akt activation: their role in proliferation.

We investigated the signaling mechanisms that lead to IL-1beta-induced cell proliferation. Treatment of Balb 3T3 cells with IL-1beta activated two signaling pathways, Erk and Akt. IL-1beta also increased tyrosine phosphorylation of PLC-gamma in Src kinase-dependent manner. Pharmacological inhibition of the PLC-PKC cascade by using specific inhibitor for PLC-gamma (U73122) and PKC (GFX) strongly inhibited IL-1beta-induced Erk and Akt activation. Inhibition of MEK1 by its specific inhibitor, PD98059 substantially inhibited Erk activation. Similarly, inhibition of PI3K activation by its specific inhibitor LY294002 suppressed Akt phosphorylation. Moreover, IL-1beta-induced association of PLC-gamma with SHPS-1. SHPS-1 mutants lacking the tyrosine phosphorylation sites failed to associate with PLC-gamma. Finally, IL-1beta-induced proliferation of Balb 3T3 cells and inhibition of Erk and Akt signalings or their upstream signaling molecules, Src kinase and PKC by their inhibitors strongly inhibited IL-1beta-dependent cell proliferation. Taken together, our results suggest that a SHPS-1-PLC-gamma complex activate the PLC-PKC cascade, which is required for the activation of IL-1beta-dependent Erk and Akt signalings and cell proliferation.

Animals↗
PubMed2002

Targeting microparticles to select tissue via radiation-induced upregulation of endothelial cell adhesion molecules.

PURPOSE: Certain endothelial cell adhesion molecules are up regulated in tissue that has been irradiated for therapeutic purposes. This up-regulation of adhesion molecules provides a potential avenue for targeting drugs to select tissues. METHODS: Microspheres were coated with a mAb to ICAM-1 and the level of adhesion of the anti-ICAM-1 microspheres to irradiated tissue in vitro and in vivo was quantified. RESULTS: Under in vitro flow conditions, the number of adherent microspheres on irradiated HUVEC was 4.8 +/- 0.9 times that of control; the adhesion of anti-ICAM-1 microspheres on irradiated HUVEC could be enhanced by more than 170% in the presence of RBC (20% hematocrit) in the medium. In vivo in a rat cranial window model, the number of adherent anti-ICAM-1 microspheres in locally irradiated cerebral tissue was 8 and 13 times that of IgG microspheres at 24 h and 48 h post-irradiation, respectively and returned to baseline 7 days post-irradiation. In locally irradiated animals, the number of adhering microspheres in unirradiated tissue remained at the basal level. CONCLUSIONS: Radiation-induced up-regulation of endothelial cell adhesion molecules may be exploited to target drugs and/or genes to select segments of the endothelium.

Animals↗
PubMed2002

[Analysis of serologic typing error for HLA-A and HLA-B in Chinese].

Serological mistypings of HLA-A and HLA-B in 27 cases were analyzed. The results showed that for HLA-A and HLA-B typing, the rates of incorrect antigen assignments were significantly higher than rates of antigen misses (P < 0.05), but there was no significant difference between HLA-A and HLA-B typings. The frequencies of miss-assigned HLA-A and HLA-B specificities were A1 (66.7%), A3 (50.0%), A11 (13.5%), A9 (11.8%), A19 (7.1%), and B16 (50.0%), B48 (43.9%), B15 (16.7%), B40 (11.1%), B13 (10.0%) and B17 (9.1%). In conclusion, the serologic and DNA-based typing techniques should be reciprocally complementary in HLA-A and HLA-B typing.

Asian People↗
PubMed2002

[Glossopharyngeal neuroutomy by improved retrosigmoid approach].

OBJECTIVE: To explore a surgical approach to improve the operation effect of glossopharyngeal neuralgia (GPN). METHOD: In 8 cases with GPN, the improved retrosigmoid approach was adopted to access the cerebellopontine angle for exposing the jugular foramen and its adjacent tissues so as to cut off the glossopharyngeal under microscope. The sensoryrizotomy of trigemlind nerve was also performed if there was a trigeminal neuralgia. RESULT: All the symptom of pain in 8 cases with GPN disappeared after operation with no complication occurred. There was no recurrence following-up for 2 approximately 7 years. CONCLUSION: By improved retrosigmoid approach, it is easy to explore the jugular foramen and cut off the glossopharyngea for treating GDN.

Adult↗