Biomedical subjects

Jun Pan

Publications and source records attributed to Jun Pan.

At least 19 recordsLinked to original sources

PubMed2006

Separation of polyethylene glycols and their fluorescein-labeled compounds depending on the hydrophobic interaction by high-performance liquid chromatography.

The separation and characterization of fluorescein-labeled polyethylene glycols (PEG) is described. Firstly, the polyethylene glycols labeled with fluorescein isothiocyanate (FITC) were synthesized and separated using Sephadextrade mark LH-20 medium by a step gradient. Secondly, a TSK GEL G4000 PW XL column was developed for determining the FITC derivatives of PEG. The retention mechanism is based on the hydrophobic interaction between the FITC derivatives of PEG and the packing material of the TSK GEL G4000PW XL column. The retention time of the PEG compounds increased by adding of salts in the mobile phase and decreased by adding of organic modifier. In addition, various salts in the eluent can also change the chromatographic behavior of these compounds. Finally, the pH of the mobile phase can have an impact on the retention time of the PEG compounds.

Chromatography, High Pressure Liquid↗

PubMed2006

The prognostic value of the mitral diastolic filling velocity ratio for all-cause mortality and cardiovascular morbidity in African Americans: the Atherosclerotic Risks in Communities (ARIC) study.

BACKGROUND: Although recent data suggest that the mitral diastolic early-to-late (E/A) ratio may be prognostic in selected population-based cohorts, its predictive value for morbidity and mortality in African Americans has not yet been well studied. METHODS: The study population consisted of African American participants from the Jackson cohort of the Atherosclerotic Risks in Community Study. Three subgroups of E/A ratios were defined: E/A <0.7, E/A 0.7-1.5, and E/A >1.5, using the middle group as reference. Cox proportional hazard models were used to assess the association between the E/A ratio and both all-cause mortality and incident cardiovascular disease (CVD). The mean follow-up period was 6.8 +/- 1.3 years. RESULTS: Of the 2211 participants in the study population (mean age 62 years, 65.1% women), 8.2% had an E/A ratio <0.7, 84.7% had an E/A 0.7-1.5, and 7.1% had an E/A >1.5. An E/A >1.5 was independently associated with all-cause mortality (hazard ratio [HR] 2.18, 95% confidence interval [CI] 1.20-4.03) in the multivariable model. An E/A <0.7 was associated with higher all-cause mortality (HR 1.79, 95% CI 1.17-2.73) and incident CVD (HR 1.91, 95% CI 1.29-2.83) compared with a normal E/A in the age and sex adjusted model but was not independently predictive in the multivariable model (P > .05). CONCLUSIONS: In a population-based cohort of middle-aged African Americans, an E/A >1.5 independently predicts all-cause mortality. An E/A >1.5 and an E/A <0.7 were both associated with incident CVD when adjusted for age and sex alone but were not independently predictive in the multivariable analysis.

Black or African American↗

PubMed2006

[An epidemic outbreak of respiratory infection caused by Chlamydia pneumoniae in medical workers].

OBJECTIVE: To investigate the clinical manifestations and the chest imaging characteristics of an epidemic outbreak of respiratory infection caused by Chlamydia pneumoniae (CP). METHODS: A prospective study for CP infection in 15 patients from September 2003 was carried out. Sputum and throat swab specimen were obtained and CP DNA was detected by polymerase chain reaction (PCR). Serum samples were obtained and immunoglobulin G and M (IgG and IgM) of antibodies to CP. pneumoniae were studied by microimmunofluorescence test. Chest X-ray and computed tomography were retrospectively analyzed. RESULTS: All patients presented fever, headache, sore throat, hoarseness, muscular ache, and dry cough. Acute cough was often associated with chest pain. The sputum blood was present in 3 patients (20%). Moist rales were heard in 4 patients. Chest imaging abnormalities were present in 67% (10 patients). The organism was demonstrated in 87% (13 patients) by PCR. The most common imaging abnormalities were unilateral and (or) bilateral multi-focal or solitary alveolar nodular opacities (9 patients). The patchy shadows were found in 2 patients, and pulmonary consolidation associated with the local pulmonary edema in 1 patient. Hilar or mediastinal lymphadenopathy and pleural effusion was not found. CONCLUSIONS: The colony occurrences and similar clinical and chest imaging manifestations are characteristics of an outbreak of respiratory infection caused by CP in medical workers. An outbreak of respiratory infection caused by CP should be differentiated from severe acute respiratory syndrome (SARS).

Adult↗

PubMed2006

[HPLC-MSn analysis of trigonelline and its metabolites in rat urine].

AIM: To establish a rapid and sensitive LC-MSn method for the identification of trigonelline and its main metabolites in rat urine. METHODS: After optimizing the detection conditions of LC-MSn chromatography and mass spectrometry using trigonelline, its ionization and cleavage in ESI-MS and ESI-MSn modes were summarized, then serving as the basis for the metabolite analysis of trigonelline in rat urine. The 0-48 h urine samples of rats were collected after iv 8 mg x kg(-1) trigonelline, then, the samples were purified through C18 solid-phase extraction cartridge. The purified samples were analyzed by LC-MSn. RESULTS: The structures of trigonelline metabolites were elucidated according to the changes of the molecular weights of the metabolites (deltaM) and their cleavage pattern in ESI-ITMSn. As a result, two phase I metabolites and the parent drug were identified existing in rat urine, and two phase II metabolites were identified. CONCLUSION: The LC-MSn method is rapid and high sensitive and specific, it is suitable for the identification of trigonelline and its metabolites in rat urine.

Alkaloids↗

PubMed2006

Preparation and in vitro targeting of sterically stabilized liposomes modified with chimeric TNT-3 monoclonal antibody.

AIM: To prepare sterically stabilized liposomes modified with chimeric TNT-3 monoclonal antibody (chTNT-3) and investigate their immunoreactivity and in vitro targeting. METHODS: An end-group functionalized polyethylene glycol-lipid derivative (pyridylthiopropionoylamino-polyethylene glycol-hydrogenated soy phosphatidylethanolamine, PDP-PEG-HSPE) was synthesized and incorporated to sterically stabilized liposomes. After mild thiolysis of the PDP groups by dithiothreitol, liposomes were covalently linked with maleimide-derivatized chTNT-3 and formed sterically stabilized immunoliposomes. Coupling efficiency, antibody density, size distribution, immunoreactivity of chTNT-3-modified sterically stabilized liposomes (chTNT-3-SLs) and specific binding properties of the chTNT-3-SLs to fixed Raji cells were determined, separately. RESULTS: Higher initial Ab/PDP-PEG-HSPE molar ratios resulted in higher antibody density on the surface of liposomes but lower coupling efficiency. The optimal coupling efficiency of 71% was obtained while antibody density in liposome was 106 microg antibody/micromol phospholipids (as initial antibody/PDP-PEG-HSPE = 1 : 10). The chTNT-3-SLs had a narrow size distribution after extrusion and the mean size of this immunoliposomes was (115 +/- 33) nm. The immunoreactivity of chTNT-3 can be preserved after efficient attachment of maleimide-derivatized chTNT-3 to the surface of liposomes. But calculated per antibody concentration, the immunoreactivity of chTNT-3-SLs would obviously decrease compared to that of chTNT-3 or chTNT-3 derivatives. Significantly higher binding of chTNT-3-SLs to fixed Raji cells directed by chTNT-3 was obtained compared to other preparations in serial dilutions (P < 0.01). CONCLUSION: chTNT-3-SLs prepared by PDP-PEG-HSPE method remained most immunoreactivity of chTNT-3 and was able to bind nuclear antigens in vitro.

Antibodies, Monoclonal↗

PubMed2006

[Anatomical study of venous spaces in transsphenoidal approach for cavernous sinus surgery].

OBJECTIVE: To study the anatomical and morphological characteristics of the venous spaces involved in surgery via transsphenoidal approach to the cavernous sinus (CS). METHODS: Ten fixed cadaver heads (six male, four female) with red and blue latex injected in the arteries and veins, respectively, were used to perform the transsphenoidal approach. The anterior wall of the sphenoidal sinus and the floor of sellar turcica were opened as much as possible to expose the dura mater at the sellar floor and the inferior wall of CS, and the location of the anterior and inferior intercavernous sinuses were observed carefully. All the spaces of CS were observed and measured. According to the observations, the venous spaces available for operation were identified and analyzed. RESULTS: In all the cadaver heads, 4 anterior and 5 inferior intercavernous sinuses were found, with the former locating below the optic protuberance, while the latter situated at the turn of the sellar protuberance at the clival indentation. CS was subdivided into medial space, inferolateral space, and dorsolateral space. CONCLUSIONS: In transsphenoidal approach, opening of anterior and inferior intercavernous sinus is liable to result in intra- and postoperative venous bleeding, and understanding of the location of the intercavernous sinus and appropriate utilization of these CS may help reduce intraoperative vascular and nerve injury.

Cadaver↗

PubMed2005

[Amniotic fluid: a novel source for tissue engineering].

OBJECTIVE: To investigate the possibility of using amniotic fluid cells as seed cells for tissue engineering. METHODS: Amniotic fluid was obtained by ultrasound-guided amniocentesis performed on pregnant women with a gestational age ranging from 16(th) approximately 23(rd) weeks. The cells isolated from the amniotic fluid were cultured in F10 culture fluid with 10% FBS. Immunocytochemistry was used to examine the standard intermediate filaments. After 3 passages of subculture, the cells were harvested and seeded onto PGA polymer scaffold. The cellular morphology, structure and adhesion with scaffold were evaluated by contrast microscope and scanning electronic microscope. RESULTS: The amniocytes expanded rapidly in culture media. Immunocytochemistry revealed positive signals for vimentin, smooth muscle action (SMA), and pan cytokeratin, and negative signals for desmin. Amniocytes-polymer complex analysis showed confluent cells firmly attached to the scaffold, with no evidence of cell death. CONCLUSION: The expansion potential of amniotic fluid cells is active. They express the characteristics of mesenchymal cells. The cells on PGA polymer scaffold can grow rapidly and maintain its morphological property. So the amniotic fluid may be a practical cell source for tissue engineering.

Actins↗

PubMed2005

In vitro and in vivo studies on mucoadhesive microspheres of amoxicillin.

Amoxicillin mucoadhesive microspheres (Amo-ad-ms) were prepared using ethylcellulose (Ec) as matrix and carbopol 934P as mucoadhesive polymer for the potential use of treating gastric and duodenal ulcers, which were associated with Helicobacter pylori. The morphological characteristics of the mucoadhesive microspheres were studied under scanning electron microscope. In vitro release test showed that amoxicillin released faster in pH 1.0 hydrochloric acid (HCl) than in pH 7.8 phosphate buffer. Yet, it would be degraded to some extent in a pH 1.0 HCl medium at 37 degrees C, which indicated that amoxicillin was not stable in an acidic surrounding. It was also found that amoxicillin entrapped within the microspheres could keep stable. In vitro and in vivo mucoadhesive tests showed that Amo-ad-ms adhered more strongly to gastric mucous layer than nonadhesive amoxicillin microspheres (Amo-Ec-ms) did and could retain in gastrointestinal tract for an extended period of time. Amo-ad-ms and amoxicillin powder were orally administered to rats. The amoxicillin concentration in gastric tissue was higher in the Amo-ad-ms group. In vivo H. pylori clearance tests were also carried out by administering, respectively, Amo-ad-ms or amoxicillin powder, to H. pylori infectious BALB/c mice under fed conditions at single or multiple dose(s) in oral administration. The results showed that Amo-ad-ms had a better clearance effect than amoxicillin powder did. In conclusion, the prolonged gastrointestinal residence time and enhanced amoxicillin stability resulting from the mucoadhesive microspheres of amoxicillin might make contribution to H. pylori clearance.

Adhesives↗

PubMed2005

Grafting reaction of poly(D,L)lactic acid with maleic anhydride and hexanediamine to introduce more reactive groups in its bulk.

Bioactivity of biomaterials was a new requirement, especially in tissue engineering and drug delivery. As a traditional used biomaterial, polylactide (PLA) had no bioactivity, of course, and it still had few reactive groups to introduce some bioactive molecules in its bulk. Here, we want to introduce carboxyl groups and amino groups in the side chain of PLA to get more reactive groups for incorporating bioactive molecular later and to maintain the structure of main chain to keep its biodegradability, and to settle the acidity of PLA during hydrolysis at the same time. It was performed as follows: first, maleic anhydride was covalently grafted onto the side chain of PLA by a free radical reaction at 100 degrees C for 20 h with BPO as the initiator. Then, by amidation with a maleic anhydride group on PLA at room temperature, hexanediamine was incorporated. The resulting polymers have been characterized via GPC, (13)C NMR, DSC, and TGA. The graft ratio was tested by titration. The pH changes during hydrolysis in 0.1 M PBS with pH 7.4 of PLA, MPLA, and HPLA were investigated. All the results showed that this research has grafted maleic anhydride and then hexanediamine in the bulk of PLA. The molecular weight degradation during reaction was less than 20%. The graft ratios of were 2.68, 2.36, and 1.86%, respectively in 5, 10, and 20% raw MA in MPLA; and the anhydride groups grafted in MPLA can completely react with hexanediamine at room temperature. The pH value of HPLA remained neutral within 12 weeks' hydrolysis compared with the resulted acidity of PLA and MPLA.

Biocompatible Materials↗

PubMed2005

Tissue-dependent distribution and accumulation of chlorobenzenes by vegetables in urban area.

Five seasonal vegetables from three growing sites in Hangzhou city, Zhejiang Province, were studied for the levels of four chlorobenzenes(CBs): o-dichlorobenzene (o-DCB), p-dichlorobenzene (p-DCB), m-dichlorobenzene (m-DCB), and 1,2,4-trichlorobenzene (1,2,4-TCB). Samples of each vegetable from each site were subdivided into leaves, stems, and roots, and these subsamples were analyzed separately for the levels of accumulated CBs. Relations between the levels of CBs in vegetables with the total organic carbon (TOC) of the soil, the lipid content of the vegetable, and the physicochemical properties of CBs were established. Results showed that o-DCB, p-DCB, m-DCB, 1,2,4-TCB were present in all vegetables analyzed. For spinaches (Spinacia oleracea), Chinese cabbages (Brassica rapa var. pekinensis), and celery (Apium graveolens var. dulce), the highest level of CBs was with roots, followed by leaves. While for radishes (Raphanus sativus), and carrots (Daucus carota subsp. sativus), the highest level was with leaves, followed by stems. The accumulation of CBs was found to have a good correlation with the plant-tissue lipid content, the contaminant air-water Henry's coefficient (H), the contaminant octanol-water partition coefficient (K(ow)), and the physiological characteristics of the vegetables.

1-Octanol↗

PubMed2005

Stabilization of cold-adapted protease MCP-01 promoted by trehalose: prevention of the autolysis.

Protease MCP-01 is similar to other cold-adapted enzymes in that it is a cold-adapted serine protease having high specific activity and low thermostability at low and moderate temperature. Its thermolability and self-autolysis has resulted in difficulties in its purification, preservation and research on its structure and function. The disaccharide trehalose is known to effectively stabilize proteins. Its prevention effect on the autolysis of cold-adapted protease MCP-01 was monitored by capillary electrophoresis. In the absence of trehalose, protease MCP-01 autolyzed rapidly at 35 degrees C. However, when trehalose was added, autolysis was remarkably prevented and the loss of activity reduced. MCP-01 may be a useful model for basic research on the interaction of protein and trehalose.

Electrophoresis, Capillary↗

PubMed2005

[Prenatal diagnosis of glycogen storage disease Ia by screening for hot spot mutations in combination with the 1176 nucleotide polymorphism linkage analysis].

OBJECTIVE: To develop and evaluate a simple, fast and accurate prenatal diagnosis method for glycogen storage disease Ia (GSD Ia) in Chinese. METHODS: This study involved 3 unrelated families. Genomic DNA samples were extracted from the blood of three GSD Ia patients and their parents, from the amniocytes of 3 fetuses and the blood of 2 newborns. By the way of restriction enzyme analysis, the screening for 727G-->T and R83H mutations of glucose-6-phosphatase gene was carried out in conjunction with 1176 nucleotide polymorphism linkage analysis so as to make the gene and prenatal diagnosis of 3 GSD Ia families. Direct DNA sequencing of the corresponding PCR products was used to confirm the unveiled mutations and 1176 nucleotide polymorphism. RESULTS: Three probands were homozygotes for the 727G-->T mutation and their parents were heterozygotes for this mutation. The fetuses of family 1 and 3 were heterozygotes for the 727G-->T mutation, whereas the fetus of family 2 did not carry this mutation. The 1176 nucleotide polymorphisms of 3 fetuses were different from those of the corresponding probands. The prenatal diagnoses of family 1 and 2 were confirmed by the postnatal biochemical and molecular studies. CONCLUSION: These findings suggest that the screening for 727G-->T and R83H mutations in conjunction with the 1176 polymorphism linkage analysis be a simple, fast and accurate method for gene and prenatal diagnosis of GSD Ia in Chinese.

Adult↗

PubMed2005

[Advances in apoptosis induced by biomaterials].

Biomedical materials are the biomaterials that, used in physiological system for diagnosis, treatment, plerosis or replacement of tissues and organs. Apoptosis, also known as PCD or ACD, is a normal physiological mechanism of cell in organism and a process of automatic cell death in which multicell organism modulates the development of organism and maintains the stability of internal environment. The human beings are able to understand the interaction between the material and organism at the molecular level due to the widely-used biomedical material and the development of material science, life science and biological technology. The research of that interaction is mainly focused on biocompatibility, while much attention has been drawn to the apoptosis induced by biomaterial concerning that apoptosis could be caused by inducing factor, and many therapies of diseases are closely related to inducing apoptosis. Based on the recent research advances of apoptosis in life science and the development of biomaterials, the pathways of apoptosis induced by biomaterials were reviewed; from the different views, the pathways of signal transduction of apoptosis include traditional pathway of signal transduction, the pathway of death receptor, and the pathway through mitochondrion. By the other way, the pathways of apoptosis caused by reactive oxygen species induced by biomaterials and apoptosis by affecting cell adhesion to biomaterials and so forth were discussed also. It indicates that the pathways to apoptosis due to biomaterials possess the characteristics of variety, intercrossing and multiplicity. It is essential for a research to inquire into the mechanism of apoptosis that is induced by biomaterials, and further into the manufacturing of biomaterials. This review is devoted to shedding light on the wide application of biomaterials in the therapy of human diseases, especially in the therapy of cancer that is closely related to apoptosis.

Apoptosis↗

PubMed2005

[Research on endothelialization of artificial vascular grafts].

Endothelialization of artificial vascular graft is considered as one of the most promising methods to improve its antithrombotic ability and long-term patency. Endothelialization of artificial vascular graft includes harvesting endothelial cells, choosing some materials with better compliance and seeding endothelial cells. The methods such as immobilization of extracellular matrix protein and growth factor to substrates, stimulation of chronic in vitro shear stress for endothelial cell retention on artificial vascular graft in bioactor, genetic modificatioin of ECs, and changes of electric charge of ECs are used to increase the adherence ability of endothelial cells. This paper reviews the process of endothelialization of artificial vascular graft and makes brief comments on the methods of endothelialization of artificial vascular graft.

Blood Vessel Prosthesis↗

PubMed2005

[Preparation and characterization of bovine bone collagen matrix].

A process of preparing bovine cortical bone in order to form materials suitable for biomedical xenograft implants was described. Fresh bone samples cut from the middiaphyseal region of bovine femora were obtained from a local slaughterhouse. The bovine bone collagen matrix (BBCM) of various shapes fabricated from bovine bone by defatting and deproteination procedure may be implanted surgically for various purposes. The bone cubes were first defatted in a mixture of defatting agent; subsequently, the samples were extracted to release noncollagenous proteins, followed by digestion using a proteolytic enzyme to remove the telopeptide portions of collagen and residual noncollagenous proteins. Finally,the samples were dried in vacuum, packed and sterilized by gamma irradiation. The bone specimens were characterized by a suite of analytical techniques involving FTIR spectroscopy, X-ray diffraction spectroscopy, differential scanning calorimetry (DSC), uniaxial tension mechanical tests and scanning electron microscopy (SEM). The result showed that BBCM occurred as a white structure with suitable porosity. It contains reasonable proprotion of mineral and organic components in the original osseous architecture of the bovine bone, which is beneficial to keeping the mechanic property and weaker immunogenicity; therefore, it can serve as a potential bone implantable material and extracellular matrix material in bone tissue engineering.

Animals↗

PubMed2005

[Advance in research of osteoblast adhesion to bioactive materials].

In the research field of bone tissue engineering, the interaction of osteoblast and substrate is pivotal and the adhesion of osteoblast to biomaterials is the basic condition. Firstly, osteoblast must adhere to biomaterials, then it can migrate, proliferate and differentiate. This paper introduces the proteins relating to the adhesion of osteoblast and the influences of relating surface character and modification of biomaterials on the adhesion ability of osteoblast. These could serve as basic data and useful reference for the development of bone tissue engineering and tissue engineering scaffold materials.

Biocompatible Materials↗

PubMed2005

[Histological evaluation of poly (dextrogyr-levogyr) lactide acid-triiodothyronine in sciatic nerve defect of rat].

OBJECTIVE: To make a histological evaluation of poly (dextrogyr-levogyr)lactide acid-triiodothyronine (PDLLA-T3) in sciatic nerve defect of rat. METHODS: Ninety SD rats were evenly divided into 3 groups (autograft group A, PDLLA-T3 group B and PDLLA group C). Group D was control group. The left sciatic nerves were cut off by operation and 1 cm-nerve-defect was set up. The specimens were collected 2 weeks, 1 month and 2 months after the operation respectively, simultaneously the right sciatic nerves were collected as normal control group D. HE staining, electron microscope, S-100 immunohistochemistry, and Bielschowsky staining were done in all the specimens, the quantity and quality of the regenerated nerves were observed, and all the results were processed by image analyzer. RESULTS: Two weeks after the operation,histological observation indicated that the materials in groups B and C were not completely degraded. Transmission electron microscopic observation showed that the myelin sheath was not thick and it was about 0.5 microm in thickness. There was no significant difference among the 3 groups. One month after the operation, histological observation indicated that in group A the regenerated nerves passed through the scaffold and in the new nerves there were regenerated blood vessels. The materials in groups B and C were not completely degraded. S-100 immunohistochemical observation and Bielschowsky staining showed that in group B PDLLA-T3 repaired the defect successfully and the regenerated nerve myelin sheath was 1.81+/-0.19 microm in thickness. The effect in group B was better than that of groups A and C (P> 0.05). Two months after the operation, the materials in groups B and C were completely degraded. The quantity of the regenerated nerves in group B confirmed by S-100 immunohistochemical observation and Bielschowslcy staining was more than that in group C(P<0.05) and close to that in group A. The regenerated nerve myelin sheath in group B was 2.15+/-0.27 microm in the thickness and was thicker than that in group C (P<0.05), but thinner than that in groups A and D (P<0.05). CONCLUSION: PDLLA-T3 can repair the defect of rat sciatic nerve with satisfactory quantity and quality of regenerated nerves.

Animals↗

PubMed2005

[Molecular mechanism of bone absorption in osteoclast].

The physiological reconstruction of bone is strictly dependent on bone resorption. Bone resorption is believed to be a complicated molecular reaction process that occurs in the microcircumstance of bone tissue. A lot of enzymes and factors take part in this process, yet there are not enough data with reference to the activation of osteoclast, resorption of bone matrix, regulation of bone resorption. In this paper we review the importance of matrix metalloproteinases (MMPs) in transfer of osteoclast and degradation of bone matrix, and the function of receptor activator of NF-kappaB-ligand (RANKL) and osteoprotegerin (OPG) in regulation of bone resorption.

Bone Resorption↗