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Biomedical subjects

Jun Pan

Publications and source records attributed to Jun Pan.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed2004

Norepinephrine transporter function and desipramine: residual drug effects versus short-term regulation.

Previous research has shown that exposure of norepinephrine transporter (NET)-expressing cells to desipramine (DMI) downregulates the norepinephrine transporter, although changes in the several transporter parameters do not demonstrate the same time course. Exposures to desipramine for <1 day reduces only radioligand binding and uptake capacity while transporter-immunoreactivity is unaffected. Recent demonstration of persistent drug retention in cells following desipramine exposures raises the possibility that previous reported changes in the norepinephrine transporter may be partly accountable by residual drug. In this study, potential effects of residual desipramine on norepinephrine transporter binding and uptake were re-evaluated following exposures of PC12 cells to desipramine using different methods to remove residual drug. Using a method that minimizes residual drug, exposure of intact PC12 cells to desipramine for 4h had no effect on uptake capacity or [(3)H]nisoxetine binding to the norepinephrine transporter, while exposures for > or =16 h reduced uptake capacity. Desipramine-induced reductions in binding to the transporter required >24 h or greater periods of desipramine exposure. This study confirms that uptake capacity of the norepinephrine transporter is reduced earlier than changes in radioligand binding, but with a different time course than originally shown. Special pre-incubation procedures are required to abolish effects of residual transporter inhibitor when studying inhibitor-induced transporter regulation.

Adaptation, Physiological↗
PubMed2004

The effect of step-wise increased stretching on rat calvarial osteoblast collagen production.

Mechanical forces regulate the function of bone cells. In this paper, the effects of cyclic stretching on osteoblasts derived from rat calvaria were studied at a magnitude occurring in physiological loaded bone tissue. A four-point bending apparatus was used to apply cyclic stretching on osteoblasts. Stretching at 500 microepsilon for 2-24 h resulted in an increase in matrix synthesis(P<0.01). In contrast, the cyclic stretching at 1000 and 1500 microepsilon for 2-24 h inhibited osteoblast collagen production (P<0.01). We also described our new loading method to increase strain magnitude step-by-step. The strain magnitude increased by 500 microepsilon increments from 500 to 1500 microepsilon every 2 or 12 h, respectively. Results showed that osteoblasts could absorb large amount of proline for collagen synthesis when stretched at 500 microepsilon. However, not all the absorbed proline was used to synthesize collagen. Some of it was stored in cells. When the suitable signal (500 microepsilon) was changed to an inhibiting signal (1000 microepsilon), cells responded to it accordingly and released proline to medium. These results demonstrate that the response of osteoblasts is dependent on the magnitude of the strain applied and cells can adjust their bio-chemical response to adapt to the changing environmental stimulation.

Animals↗
PubMed2003

Elevated concentrations of CRF in the locus coeruleus of depressed subjects.

Research evidence that corticotropin-releasing factor (CRF) plays a role in the pathophysiology of major depressive disorder (MDD) has accumulated over the past 20 years. The elevation of lumbar cerebrospinal fluid (CSF) concentrations of CRF decreased responsiveness of pituitary CRF receptors to challenge with synthetic CRF, and increased levels of serum cortisol in MDD subjects support the hypothesis that CRF is chronically hypersecreted in at least the endocrine circuits of the hypothalamic-pituitary-adrenal (HPA) axis and may also involve other CRF brain circuits mediating emotional responses and/or arousal. One such circuit includes the excitatory CRF input to the locus coeruleus (LC), the major source of norepinephrine in the brain. Furthermore, there are now reports of decreased levels of CRF in lumbar CSF from MDD patients after symptom relief from chronic treatment with antidepressant drugs or electroconvulsive therapy. Whether this normalization reflects therapeutic effects on both endocrine- and limbic-associated CRF circuits has not yet been effectively addressed. In this brief report, we describe increased concentrations of CRF-like immunoreactivity in micropunches of post-mortem LC from subjects with MDD symptoms as established by retrospective psychiatric diagnosis compared to nondepressed subjects matched for age and sex.

Adult↗
PubMed2003

Atomic force microscopy of actin.

Atomic force microscope (AFM) is a powerful and novel tool to investigate the surface and submembranous structures of living cells under physiological conditions at high resolution, and has force measure at nano-Newton level. AFM can image and manipulate samples (single macromolecule, cells, and so on) at very high, sometimes atomic resolution by scanning a fine tip over the surface of interest and detecting physical interactions between the tip and sample. Actin is one of the most important proteins, involved extensively in various cell physiological activities and functions in eukaryotes. The present paper clarified the crucial significance and the enormous applicable prospects of AFM in modern biological sciences by reviewing the usage of AFM in actin study, which can be taken as a good example for expounding almost all functions that AFM owns, and can be utilized in life sciences exploration.

Actins↗