Biomedical subjects

Qiang Zhang

Publications and source records attributed to Qiang Zhang.

At least 109 records · Page 6Linked to original sources

PubMed2005

Enhanced magnetooptical response in dumbbell-like Ag-CoFe2O4 nanoparticle pairs.

We study magnetooptical Faraday rotation in a colloidal solution of "dumbbell-like", physically conjoined nanoparticle pairs composed of a ferromagnetic (CoFe2O4) and a noble metal (Ag). We show that outside the CoFe2O4 interband dominated spectral regime, the coupled dumbbells show significantly enhanced magnetooptic response relative to single CoFe2O4 nanoparticles, derived from plasmonic contribution by the Ag nanoparticles.

Journal Article↗

PubMed2005

Characterization of carbonaceous species of ambient PM2.5 in Beijing, China.

One-week integrated fine particulate matter (i.e., particles <2.5 microm in diameter; PM2.5) samples were collected continuously with a low-flow rate sampler at a downtown site (Chegongzhuang) and a residential site (Tsinghua University) in Beijing between July 1999 and June 2000. The annual average concentrations of organic carbon (OC) and elemental carbon (EC) at the urban site were 23.9 and 8.8 microg m(-3), much higher than those in some cities with serious air pollution. Similar weekly variations of OC and EC concentrations were found for the two sampling sites with higher concentrations in the winter and autumn. The highest weekly variations of OC and EC occurred in the winter, suggesting that combustion sources for space heating were important contributors to carbonaceous particles, along with a significant impact from variable meteorological conditions. High emissions coupled with unfavorable meteorological conditions led to the max weekly carbonaceous concentration the week of November 18-25, 1999. The weekly mass ratios of OC:EC ranged between 2 and 4 for most samples and averaged 2.9, probably suggesting that secondary OC (SOC) is present most weeks. The range of contemporary carbon fraction, based on the C14 analyses of eight samples collected in 2001, is 0.330-0.479. Estimated SOC accounted for approximately 38% of the total OC at the two sites. Average OC and EC concentrations at Tsinghua University were 25% and 18%, respectively, higher than those at Chegongzhuang, which could be attributed to different local emissions of primary carbonaceous particles and gaseous precursors of SOC, as well as different summer photochemical intensities between the two locations.

Air Pollutants↗

PubMed2005

Permeation-enhancing effects of chitosan formulations on recombinant hirudin-2 by nasal delivery in vitro and in vivo.

AIM: To investigate the enhancing effects of chitosan with or without enhancers on nasal recombinant hirudin-2 (rHV2) delivery in vitro and in vivo, and to evaluate the ciliotoxicity of these formulations. METHODS: The permeation-enhancing effect of various chitosan formulations was estimated by using the permeation coefficient of fluorescein isothiocyanate recombinant hirudin-2 (FITC-rHV2) across the excited rabbit nasal epithelium in vitro. The effect was further evaluated by measuring the blood concentration level after nasal absorption of FITC-rHV2 in rats. The mucosal ciliotoxicity of different formulations was evaluated with an in situ toad palate model. RESULTS: Chitosan at a concentration of 0.5% with or without various enhancers significantly increased the permeability coefficient (P) and relative bioavailability (Fr) of FITC-rHV2 compared with the blank control. The addition of 1% sodium dodecylsulfate, 5% Brij35, 5% Tween 80, 1.5% menthol, 1% glycyrrhizic acid monoammonium salt (GAM) or 4% Azone into the 0.5% chitosan solution resulted in a further increase in absorption (P<0.05) compared with 0.5% chitosan alone. But co-administration of chitosan with 5% hydroxyl-propyl-beta-cyclodextrin (HP-beta-CD), 5% lecithin or 0.1% ethylenediamine tetraacetic acid (EDTA) was not more effective than using the 0.5% chitosan solution alone. Chitosan alone and with 5% HP-beta-CD, 0.1% EDTA, 1% GAM or 5% Tween 80 was relatively less ciliotoxic. CONCLUSION: Chitosan with or without some enhancers was able to effectively promote the nasal absorption of recombinant hirudin, while not resulting in severe mucosal ciliotoxicity. A chitosan formulation system would be a useful approach for the nasal delivery of recombinant hirudin.

Absorption↗

PubMed2005

Novel expression and characterization of lymphatic vessel endothelial hyaluronate receptor 1 (LYVE-1) by conjunctival cells.

PURPOSE: Lymphatic vessel endothelial hyaluronic acid receptor (LYVE-1) is a newly discovered lymphatic-specific marker. To date, there is no report of its expression on conjunctival cells. The purpose of this study was to investigate the expression of LYVE-1 in normal conjunctiva, to phenotype LYVE-1+ cells, and to study changes in their expression levels during corneal inflammation. METHODS: Flat-mounted conjunctivae or cross sections of eyeballs were harvested from BALB/c mice (6-8 weeks of age) for immunofluorescent confocal microscopic studies. RESULTS: The data demonstrate, for the first time, that in addition to its expression on lymphatic vessels, LYVE-1 was expressed on CD45+, CD11b+, and CD31- conjunctival cells, indicating a bone-marrow-derived monocytic lineage. Surprisingly, the number of cells that expressed LYVE-1 decreased during corneal inflammation, in conjunction with ingrowth of lymphatics into the cornea. CONCLUSIONS: A new population of monocytic cells has been found to express LYVE-1 in normal conjunctiva. These cells that normally express LYVE-1 may act as a reservoir for lymphangiogenesis and cell recruitment when the immune system is challenged.

Animals↗

PubMed2005

Nasal recombinant hirudin-2 delivery: absorption and its mechanism in vivo and in vitro studies.

The objective of this study was to investigate the feasibility of systemic absorption of recombinant hirudin-2 (rHV2) by nasal delivery, and its possible absorption mechanism. The degradation of rHV2 in the nasal tissue homogenate and extracts of mucosae of rabbit, as well as the degradation inhibition of enzyme inhibitor (bacitracin) was evaluated. The bioavailability of rHV2 and the improvement with enhancers, after nasal administration in rats was investigated. For further understanding of the transport and uptake characteristics of rHV2, in vitro transport experiment under various conditions using diffusion chamber technique in excised rabbit nasal epithelium was performed. It was found that rHV2 underwent rapid degradation in rabbit nasal homogenate, but it was more stable in the extracts of nasal mucosae surface. Bacitracin was able to inhibit the degradation of rHV2 to certain extent. rHV2 was detected in the rat plasma by chromogenic substrate assay after nasal administration and some enhancers also significantly increased the nasal absorption of rHV2. The transport and uptake of rHV2 across nasal epithelium was concentration-dependent and unsaturated, and was significantly inhibited by low temperature, NaN(3), DNP and colchicines, while was less affected by alteration of transport direction. These results demonstrate that the possible absorption mechanism of rHV2 by nasal mucosa appears to be associated with the endocytosis as well as passive diffusion process.

Absorption↗

PubMed2005

Sublingual delivery of insulin: effects of enhancers on the mucosal lipid fluidity and protein conformation, transport, and in vivo hypoglycemic activity.

The purposes of this study were to evaluate effects of enhancers for sublingual delivering insulin on the mucosal lipid fluidity and protein conformation, transport, and in vivo hypoglycemic activity in normal rats. The effects on sublingual mucosa, and aggregation states of insulin were estimated using fluorescence polarization, and circular dichroism method, respectively. The human immortalized oral epithelial cell monolayer was used for evaluating transport of insulin. Hydroxylpropyl-beta-cyclodextrin (HP-beta-CD), chitosan, polyethylene-polypropylene glycol, polyoxyethylene lauryl ether, polysorbate 80, egg lecithin, or oleic acid, was used as a penetration enhancer, respectively. The fluidity of sublingual mucosal lipid was markedly reduced by these enhancers excluding polysorbate 80, and the secondary structure of the mucosal proteins was also influenced by these enhancers. The hexamers of insulin were dissociated to monomers only by chitosan, polyoxyethylene lauryl ether, and egg lecithin. Nonetheless, plasma glucose levels in normal rats were significantly lowered after sublingual administration of insulin with an enhancer compared with those without an enhancer at the same time-point. The enhancing effects may be due to one or multiple factors: increasing the mucosal lipid fluidity, directly loosing the tight junction of epithelia, and dissociating the hexamers of insulin to monomers. Among these, the opened tight junction may correlate most with the enhancing effect in the mucosal permeability. Because the aggregates of insulin exist, the dissociation of the aggregates by an enhancer would benefit the permeability.

Administration, Sublingual↗

PubMed2005

In vitro and in vivo characterization of a newly developed clonidine transdermal patch for treatment of attention deficit hyperactivity disorder in children.

The aim of this study was to characterize a newly developed clonidine transdermal patch, KBD-transdermal therapeutic system (TTS), for the treatment of attention deficit hyperactivity disorder in children. In vitro release, penetration, and in vivo pharmacokinetics in rabbits were investigated. The smaller size of KBD-TTS (2.5 mg/2.5 cm2) showed a similar in vitro penetration to those of Catapres-TTS (2.5 mg/3.5 cm2, a clonidine transdermal patch used for the treatment of hypertension, Alza Corporation, U.S.A.). The transdermal penetration rate of clonidine was mainly controlled by the ethylene vinylacetate membrane used in the patch. The skin layer may be only a minor rate-limiting barrier after the topical skin layer at the dosing site is saturated with penetrating clonidine in the initial phase (0 to 12 h). A sensitive liquid chromatography-mass spectrometry method for the quantification of clonidine in rabbit plasma was developed using solid-phase extraction and gradient elution on LC combined with the selected-ion monitoring (SIM) mode. A single dose of clonidine transdermal patch (KBD-TTS) or Catapres-TTS was transdermally administered to rabbits (n=6 each) and removed after 168 h. The average half-life, Tmax, Cmax and Css values of clonidine in rabbits following administration of KBD-TTS were 19.27+/-4.68 h, 52.56+/-25.77 h, 27.39+/-9.03 ng/ml, and 25.82+/-9.34 ng/ml, similar to those of Catapres-TTS, respectively. The clonidine plasma concentration of KBD-TTS reached a steady state at 24 h through 168 h. The in vitro release rate of the clonidine from KBD-TTS significantly correlated with the in vivo absorption rate (p<0.001).

Administration, Cutaneous↗

PubMed2005

In vitro cytotoxicity of Stealth liposomes co-encapsulating doxorubicin and verapamil on doxorubicin-resistant tumor cells.

Multidrug resistance (MDR) is a major obstacle to successful clinical cancer chemotherapy. A novel doxorubicin anti-resistant Stealth liposomes (DARSLs), prepared by co-encapsulating doxorubicin (DOX) and verapamil (VER) into stealth liposomes, has been developed. The average particle size of DARSLs was 118.1+/-22.3 nm. Encapsulation efficiencies of DOX and VER in DARSLs were greater than 95% and 70%, respectively. The IC(50) of DARSLs as measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay in multidrug resistant rat prostate cancer Mat-LyLu-B2 (MLLB2) cells was 0.079+/-0.017 microM, 13 fold less than that for liposomal DOX with free VER (LDFV 0.96+/-0.46 microM) but only about 2 times less than FDFV. The IC(50) cytotoxicity on MLLB2 cells of the various formulations was as follows: DARSLs approximately LDLV<FDFV<FDLV<LDFV<LD<FD, (LD: liposomal DOX; LV: liposomal VER; FD: free DOX; FV: free VER). Similar cytotoxicities were shown between DARSLs and FDFV in DOX-resistant human uterus sarcoma MES-SA/DX5 cells, reversing DOX-resistance to that shown by FD on DOX-sensitive MES-SA cells. For MLLB2 cells, DARSLs was the most cytotoxic, but its intracellular concentration of DOX, measured as mean cellular fluorescence with flow cytometry was lower (p<0.01) than that observed with the FDFV formulation. In conclusion, DARSLs was an effective DOX formulation which could overcome drug resistance in DOX-resistant tumor cells, but its mechanisms of action may be complex.

Cell Line, Tumor↗

PubMed2005

[Preparation, identification and inclusion actions of irisquinone hydroxypropyl-beta-cyclodextrin inclusion complex].

AIM: To perpare and identify irisquinone hydroxypropyl-beta-cyclodextrin inclusion complex (irisquinone-HP-beta-CD), as well as to study the inclusion mechanism and molecule stoichiometry between irisquinone and hydroxypropyl-beta-cyclodextrin. METHODS: Irisquinone-HP-beta-CD was prepared by freeze-drying technique. The ratio of host and guest was also studied in inclusion process by mol gradient and continuing variational methods. At the same time, the inclusion complex was identified by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). RESULTS: It was demonstrated that the solubility of irisquinone was enhanced markedly by inclusion with HP-beta-CD when stoichiometry was 2:1 of host and guest at 25 degrees C, 35 degrees C and 45 degrees C. CONCLUSION: The solubility and stability of irisquinone could be increased by preparing the inclusion complex with hydroxypropyl-beta-cyclodextrin.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed2005

[Preparation of 8-chloro-adenosine long circulation liposomes and its pharmacokinetics in rats].

AIM: To prepare 8-chloro-adenosine (8-Cl-A) long circulation liposomes with high entrapped efficiency and prolonged action-time of 8-Cl-A in vivo. METHODS: To prepare 8-Cl-A long circulation liposomes of nanometer size by improved multiple emulsion. The entrapped efficiency, size and size distribution of 8-Cl-A long circulation liposomes were determined, and its pharmacokinetics in rats was evaluated. RESULTS: The entrapped efficiency of 8-Cl-A long circulation liposomes was 62.70% and mean diameter of the liposomes was 79.9 nm. The pharmacokinetics studies indicated that 8-Cl-A long circulation liposomes showed higher drug concentration and larger AUC values than that of 8-Cl-A after iv to rats. CONCLUSION: 8-Cl-A long circulation liposomes could prolong the action-time of 8-Cl-A in vivo.

2-Chloroadenosine↗

PubMed2005

[Studies on the nasal epithelium toxicity of adjuvants and recombination hirudin (rHV2) nasal spary].

OBJECTIVE: To investigate the nasal epithelium toxicity of adjuvants and rHV2 nasal spary(HVS). METHOD: Ciliary movement were evaluated with in situ toad palate model; The histology assessment of nasal epithelium were carried out after long-lasting and repeated use of HVS. RESULT AND CONCLUSION: Adjuvants included SDS, Brij 35, azone, lecithin, EDTA, menthol, nipagin and thiomersal were able to significantly inhibited the ciliary movement, while tween80, glycyrrhizic acid monoammonium salt, benzalkonium bromide, sodium benzoate and adhensive materials investigated had less influence on it. HVS was able to damaged the nasal epithelium, but this effect recovered soon after stopping administration. It was demonstrated that SDS, Brij 35, azone,lecithin, EDTA, menthol, nipagin and thiomersal. It had significant cilitoxity, while tween80, glycyrrhizic acid monoammonium salt, benzalkonium bromide, sodium benzoate and adhensive materials investigated had no significance; Chitosan co-administration with some adjuvants may make the cillitoxity severer; It is available that rHV2 be administered by nasal spary.

Adjuvants, Pharmaceutic↗

PubMed2005

[Effects of applying L-methionine, L-phenylalanine and L-tryptophan on Zea mays growth and its nutrient uptake].

A pot experiment was conducted to evaluate the effects of applying L-methionine (L-MET), L-phenylalanine (LPHE) and L-tryptophan (L-TRP) on the growth of Zea mays and its nutrient uptake, and to determine the optimal application rate of them. The results showed that L-MET, L-PHE and L-TRP could improve the shoot height, shoot and root dry weights, root activity, nitrate reductase and hydrogen peroxidase activities, and N, P, K and Zn uptake of corn. The optimal application rate of L-MET, L- PHE and L-TRP was 0.0185 - 0.185 mg x kg)(-1) soil, 0.2 mg x kg(-1) soil, and 0.03 - 0.3 mg x kg(-1) soil, respectively, and L-PHE and L-TRP were superior to L-MET.

Fertilizers↗

PubMed2005

[The in vitro cytotoxicity and in vivo toxicity of doxorubicin antiresistant stealth liposomes].

AIM: Multidrug resistance ( MDR) as a major obstacle to successful clinical cancer chemotherapy, searching a novel effective antiresistant drug would be necessary. METHODS: A novel doxorubicin anti-resistant stealth liposomes (DARSLs) was prepared by co-encapsulating doxorubicin (DOX) and verapamil (VER) into stealth liposomes with ammonium sulfate gradient remote loading approach. In vitro cytotoxity of various DOX formulations and in vivo toxicity of DARSLs were evaluated using DOX-resistant rat prostate cancer cell line (MLLB2), human uterus sarcoma cell line (MES-SA/DX5) and normal SD rats, separately. RESULTS: The DARSLs liposome suspensions mainly consisted of homogeneous large unilamellar vesicles (LUV) with average particle size of (118.1 +/- 22.3) nm. Encapsulation efficiencies of DOX and VER in DARSLs were more than 90% and about 70%, respectively, when the ratio of DOX/VER/Lipid was 1: 0.11 :10 (w/w/w). In vitro cytotoxicity tests of the DARSLs using rat prostate cancer cell line (MLLB2) and human uterus sarcoma cell line (MES-SA/DX5) showed that 5 micromol x L(-1) VER significantly reversed DOX-resistance of these 2 cell lines and DARSLs was the most effective on inhibition of DOX-resistant cell growth. Besides, compared to FDFV, much slower DOX distribution (confocal microscopy) to nuclei and cytoplasm in MLLB2 cells for DARSLs suggested that it might possess distinct mechanism of cytotoxicity. Systemic and cardiac toxicity evaluations in normal SD rats suggested that liposomal encapsulation could significantly improve the severe cardiotoxicity arising from simultanous administration of DOX and VER. CONCLUSION: DARSLs is a novel anticancer liposome formulation with lower cardiotoxicity, effective drug-resistance reversal and intravenous injection.

Animals↗

PubMed2005

[In vitro transdermal permeation of lidocaine-dodecanol binary eutectic system].

AIM: To study the effect of lidocaine-dodecanol binary eutectic system on the transdermal permeation of lidocaine. METHODS: Binary eutectic mixture of different proportions of lidocaine and dodecanol were prepared and the patch containing the binary eutectic mixture was developed. The solubilities of pure lidocaine and lidocaine from the binary eutectic system were determined in pH 7.9 phosphate buffer. The transdermal flux of lidocaine from the patches containing the binary eutectic system and pure lidocaine were measured using Franz-type single diffusion cell. RESULTS: The melting point of the lidocaine-dodecanol binary eutectic system was markedly lower than that of pure lidocaine. The steady state transdermal flux of lidocaine from the patch of the binary eutectic system was six times as much as that of pure lidocaine patch. CONCLUSION: The lidocaine-dodecanol binary eutectic system could produce high thermodynamic activity of the drug and the high driving force for transdermal permeation of lidocaine.

Administration, Cutaneous↗

PubMed2005

[Platysma myocutaneous flaps in reconstruction of oral defect caused by tumor resection].

OBJECTIVE: To study the method and feasibility of platysma myocutaneous flap in reconstruction of oral defects. METHODS: From March 2003 to June 2004, 15 patients with defects of tongue, floor of mouth, bucca, lateral pharynx and soft palate were treated with platysma myocutaneous flaps. There were 12 males and 3 females with an age range of 41-77 years. Defect was caused by resection of bucca (11 cases), tongue (1 case), floor of mouth (2 cases)and lateral pharyngeal and soft palate (1 case) squamous cell carcinoma. All patients were given primary cancer dissection and radical neck dissection. The defect sizes were from 3.0 cmX 3.5 cm to 7.0 cm X 4.0 cm. The sizes of the platysma myocutaneous flap were from 7.0 cm x 3.5 cm to 12.0 cm x 4.0 cm. RESULTS: All the patients were followed up for 6-12 months. In 15 patients, the flap survived, and the color and appearance of the flaps were normal. Mouth-opening was not limited. Eight patients had cutaneous fistula after 10-15 days of operation and were cured by secondary operation. No complication of ankyloglossia and tumor relapse occurred. The operation results were satisfactory. CONCLUSION: Platysma myocutaneous flap has generous blood supply, it is useful in reconstruction of oral tissue defects.

Adult↗

PubMed2005

[The influence of absorption enhancer and preparation of paclitaxel on its intestinal mucous membrane permeation detected by enhancement by using electron spin resonance technique].

AIM: To investigate the permeation mechanism of paclitaxel by enhancers and preparation factors. METHODS: The fluidity of mucous membrane and membrane protein conformation changes were determined by using electron spin resonance (ESR) when mucous membrane was treated by several enhancers. At the same time, the factors of penetration of lower dissolution drug across the intestinal mucous membrane were studied in three formulas inclusion complex, microemulsion and injection. RESULTS: Polyethylene glycol (PEG) 1500, hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and phospholipid as enhancers could reinforce the permeation of paclitaxle because of loosening of protein conformation in intestinal mucous membrane. Paclitaxel-HP-beta-CD inclusion complex and paclitaxel microemulsion as vehicle could significantly increased permeation kinetic rate of paclitaxel with fluid diffuse method. CONCLUSION: Characteristics of enhancing intestinal absorption of poor dissolution drug had been provided with enhancer the change of membrane fluid.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed2005

[Arbovirus survey in some regions in Heilongjiang province].

BACKGROUND: Mosquitoes were collected in Heilongjiang province in 2002, four virus strains were isolated by inoculation of homogenates onto BHK cell lines. The viruses were identified. Multiple alignment and phylogenetic analysis were carried out by Clustal X (1.8) program.Amino acid (AA) analysis was carried out by GENEDOS (3.2). RESULTS: Biological characters of four newly isolated strains were examined and it was found that all of them could produce cytopathogenic effect (CPE) in BHK cells, killing sucking mice. Serological tests showed that all of these stains reacted positively to JEV antibodies. PrM and E gene regions were amplified and sequenced. Phylogenic analysis showed that all the newly isolated JEV strains belong to genotype III. Using the vaccine strains (SA14-14-2) as control, analysis of the E gene of the new strains and two JEV strains (47, Ha-3) isolated previously from Heilongjiang province showed that these new strains' nucleotide sequence had a homology of up to 99.9% and the amino acid sequence homology up to 99.8%, respectively. Compared with the standard JE vaccine strain SA-14-14-2 and the four new strains, the nucleotide sequence homology was 97.3% and amino acid sequence homology was between 96.8% and 97.0%, respectively. Compared with vaccine strain, there were seven common variations in all the four newly isolated strains. CONCLUSION: Four JE virus strains were isolated in Heilongjiang province. As compared to the vaccine strain, six variations were found in the newly isolated strains at the eight sites relevant to the virulence of the virus.

Animals↗

PubMed2005

[Preparation of doxorubicin-loaded stealth liposomes modified with RGD mimetic and cellular association in vitro].

AIM: To investigate the possibility of using stealth liposomes modified with arginine-glycine-aspartic acid (RGD) mimetic as the targeted carriers to achieve increased accumulation in tumor and enhanced intracellular delivery for the encapsulated anticancer drugs. METHODS: RGD mimetic (RGDm) as a ligand for integrins was synthesized and covalently conjugated to the active PEGylated phospholipids (DSPE-PEG-BTC) to form RGDm conjugate (DSPE-PEG-RGDm). Then RGDm-modified SL (RGDm-SL) containing DOX (RGDm-SL-DOX) and SL containing DOX (SL-DOX) were prepared by film dispersion followed by ammonium sulfate gradient method. The pH-sensitive probe, BCECF-AM, was used to study the binding of melanoma cells to DSPE-PEG-RGDm. Flow cytometry and confocal microscopy were performed to evaluate the cellular association or DOX uptake for RGDm-SL-DOX or SL-DOX in vitro. RESULTS: The melanoma cells A375 and B16 showed enhanced binding to the immobilized DSPE-PEG-RGDm. The cells treated with RGDm-SL-DOX showed remarkable increase in cellular association or DOX uptake compared with SL-DOX. CONCLUSION: The RGDm-modified SL could be as the targeted carriers to facilitate the delivery of the encapsulated anti-cancer drugs into tumor cells by receptor-mediated way.

Animals↗