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Biomedical subjects

Jian Sun

Publications and source records attributed to Jian Sun.

118 records · Page 7Linked to original sources
PubMed2003

A hybrid condensed finite element model for interactive 3D soft tissue cutting.

As requested from practical operations, it is necessary in the design to provide the ability to real-time cut and suture the tissue in a surgery simulation apart from the deformation simulation. In this paper, we present a deformation model, referred as the hybrid condensed FE model, based on the volumetric finite element method. The most important advantage of this model is its ability to handle the topology change freely with interactive rate in the surgical simulation on current PC platform.

Computer Simulation↗
PubMed2002

Synthesis, crystal structure, and ESR study of a novel phosphorylated lipophilic spin trap.

In this article, the synthesis of a novel alpha-phosphorus-containing spin trap DEPPEPO [2-(diethoxyphosphoryl)-2-phenethyl-3,4-dihydro-2H-pyrrole-1-oxide] and the evaluation of its ability to spin-trap radicals, especially superoxide and hydroxyl radicals, are described. Single crystal X-ray structure analysis reveals that there exist a lot of intramolecular nonbonded attractive interactions in the molecule. The phenethyl group is located away from the diethoxyphosphoryl group and the nitronyl plane, and only one face of the nitronyl plane is sterically hindered by the oxygen attached to the phosphorus with a double bond. The latter feature is responsible for the stereoselection of the free radical additions on the nitronyl moiety. The ability of DEPPEPO to trap the active superoxide anion radical generated in the HX/XO system and the stability of their spin adduct were investigated with that for DEPMPO. The half-life of DEPPEPO is about 13.4 min, and as a result, the DEPPEPO seems to be a promising lipophilic spin trap, perhaps in both in vitro and in vivo ESR investigation. Because DEPPEPO is a solid compound, it is quite easy to purify by recrystallization and to store the compound even at room temperature. In addition, an obvious increase in lipophilicity for DEPPEPO was found as a contribution of 2-substituted phenethyl.

Journal Article↗
PubMed2002

[Serum levels of soluble Fas soluble Fas ligand and soluble IL-2 receptor in patients with coronary heart disease]

OBJECTIVE: To evaluate the relationship between serum levels of soluble Fas(sFas), soluble Fas li gand(sFasL), soluble IL-2 receptor(sIL-2R) and coronary heart disease (CHD). METHODS: With enzyme-linked immunosorbent assay (ELISA) tests, sFas, sFasL and sIL-2R were measured in the sera from 30 patients with CHD and 26 subjects without CHD as controls. RESTULTS: Mean level of sFas was significantly higher in patients with CHD than in controls [(1 583.41+/-174.46)ng/L compared with (1 374.55+/-142.42)ng/L, P<0.01]. Compared with the controls, the mean level of sIL-2R was significantly higher in patients with CHD [(944.50+/-395.59)ng/L compared with (652.45+/-163.36)ng/L P<0.01]. Moreover, in patients with CHD sFas and sIL-2R were positively correlated (r=0.418 P<0.05). Whereas no such difference was found between both groups in sFasL (P<0.05). CONCLUSION: High levels of serum sFas and sIL-2R were associated with CHD, and elevation of sFas may inhibit apoptosis in activated T cells, leading to coronary events.

Journal Article↗
PubMed2002

[Effects of carvedilol on circulating levels of endothelin and von Willebrand factor in patients with unstable angina pectoris]

OBJECTIVE: To observe the effect of carvedilol on circulating levels of endothelin (ET) and von Willebrand factor (vWF) in patients with unstable angina pectoris (UAP). METHODS Forty patients with UAP were randomly divided into two groups. On the basis of anti coagulated and vasodilator remedy patients in control group(n=21) were given benazeptil(10 mg/d) for three days while patients in therapeutic group(n=19) were administered carvedilol(40 mg/d) for three days. Before and at the end of treatment,ET was measured by RIA and vWF by ELISA in patients with UAP and healthy individuals(n=20), heart rate and blood pressure were also recorded. RESTULTS The levels of circulating ET 101.8+/-28.9 versus 110.6+/-43.5 ng/L and vWF 162.6+/-55.6 versus 172.9+/-37.8 % between control group and carvedilol group were not significantly different before treatment, but both were higher than those in healthy individual ET 81.2+/-34.0 ng/L, vWF 142.0+/-49.4 % (P<0.05). After the treatment, the levels of ET 106.3+/-38.2 ng/L and vWF 155.4+/-54.2 % in control group did not decrease significantly (P>0.05), while those in carvedilol group ET 89.2+/-45.5 ng/L, vWF 129.2+/-48.8 % decreased markedly with the reduction of heart rate and blood pressure(P<0.05). CONCLUSION Carvedilol can decrease circulating levels of endothelin and von willebrand factor in patients with UAP markedly.

Journal Article↗
PubMed2002

Application of obturator to treat velopharyngeal incompetence.

OBJECTIVE: To evaluate the effect of a system of velopharyngeal incompetence (VPI) management after the application of obturator. METHODS: Using nasopharyngofiberoscope (NPF) and a computer analysis system, we quantitatively analyzed the improved state of velopharyngeal incompetence in 100 patients with unilateral and/or bilateral cleft palate. RESULTS: The velopharyngeal closure (VPC) can be greatly improved by using a temporary oral prosthesis (obturator) and speech training. An objective quantitative standard was established to evaluate the change of velopharyngeal closure of cleft palate patients after surgery and conservative treatment. CONCLUSIONS: The method used is more succinct, accurate and practical than previous methods. In order to reflect the state of velopharyngeal incompetence, the concept of improvement rate of velopharyngeal incompetence (IRVPI) is put forward.

Adolescent↗
PubMed2002

[Circadian rhythms of DNA synthesis and apoptosis correlated gene expression in bone marrow cells of nude mice bearing human nasopharyngeal carcinoma].

BACKGROUND & OBJECTIVE: No report was found on research of circadian rhythms of nasopharyngeal carcinoma(NPC). This study was designed to investigate the circadian rhythms of DNA synthesis and apoptosis correlated gene expression in bone marrow cells of nude mice bearing NPC and to collect necessary data for making clinical chronochemotherapy schedule of NPC. METHODS: Sixty-nine BALB/C nude mice were synchronized with an alternative lighting regimen with 12 hours in light and 12 hours in dark (LD 12:12) for at least 3 weeks. Human nasopharyngeal poorly differentiated squamous cell carcinoma (CNE-2) cells were implanted into each mouse. Ten days after transplantation, the mice were sacrificed, bone marrow cells were collected in the 3, 7, 11, 15, 19, and 23 hours after light onset (HALO). Single cell suspension was obtained and stained with propidium iodide. The cellular DNA content was measured by flow cytometry. Data were analyzed with analysis of variance(ANOVA) and Cosinor analysis. Proteins were extracted from bone marrow cells and determined; Bcl-2, p53, and p21 expression were tested using Western blot analysis. RESULTS: The proportion of bone marrow cells in phase G1, S, and G2/M varied according to circadian sampling time with statistical significance (ANOVA). Moreover, such variation in G1 and G2/M was statistically valid by Cosinor analysis with an acrophase located at 10.8 HALO and 1.8 HALO, respectively. The distribution curves of phase G1 and G2/M fit to Cosinor changes but not for S phase cells. The expression of p53 and Bcl-2 protein level in bone marrow cells varied in 24 h time scale. No p21 protein expression was found in this experiment. CONCLUSION: DNA synthesis of bone marrow cells in nude mice bearing human nasopharyngeal poorly differentiated squamous cell carcinoma (CNE-2) cells varies according to circadian rhythm. The expression of p53 and Bcl-2 protein level in bone marrow cells varies in 24 h time scale.

Animals↗
PubMed2002

[Application of carotid artery reconstruction in head neck malignancy].

OBJECTIVE: The purpose of this study was to establish an ideal operation method to deal with head and neck carcinomas of late stage and involving the carotid. METHODS: A total of four metastasized head neck carcinomas involving the carotid arteries were included in this clinical trial. The primary tumors of the four cases tumors were carcinomas of tongue, esophagus, laryngeal and parotid glands. All four cases were examined by means of TCD, DSA, SPECT to confirm good compatibility of brain blood circulation before operations. The bony petrous sections of carotid arteries were drawn off after the exposure of the bone tissue for exterior skull. A by-pass was set up by inserting a shunt tube between the common carotid and the infernal carotid artery. The extended tumor resection was carried out involving the resection of the carotid artery. The artery was reconstructed with saphena magna vein transplantation in one case, and replaced by artificial vessels in two cases. Tissue defects were repaired by pedicle PMMF. RESULTS: The B-typed ultrasound and TCD examination two weeks to six months post-operatively showed the four cases revealed good condition of transplanted carotid arteries, except one case occurred Honer's syndrome, but there was no central nerve's symptom or complication in the other three cases. CONCLUSION: This operation method could provide a good chance of survival by curettage of later staged head neck tumors. The authors recommend reconstruction of carotid artery in the operation treatment of malignant head neck carcinomas during late stages.

Adult↗
PubMed2001

Detection of the YMDD motif mutation of P gene of hepatitis B virus using polymerase chain reaction-restriction fragment length polymorphism.

OBJECTIVE: To establish a convenient approach to implement polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for detecting of gene mutation. METHODS: Serum samples were collected from l0 patients with chronic hepatitis B who had received oral lamivudine for at least l year, and 3 methods including mismatched PCR-RFLP, direct sequence analysis of the PCR product and cloning prior to secondary sequence analysis were employed respectively to examine the YMDD motif mutation of P gene of hepatitis B virus (HBV). RESULTS: PCR-RFLP revealed wild-type HBV infection in 7 cases mixed infection in 1 case and HBV mutant infection in 2 cases. With direct sequence analysis of the PCR product, 9 cases were found with Wild-type HBV infection and 1 with HBV mutant infection. However, 2 non-wild-type HBVV-infected cases as approved by PCR-RFLP, opposite to the results by direct sequence analysis, were both shown by sequence analysis after cloning to suffer mixed infection. CONCLUSION: Sequence analysis following cloning is the best way to detect YMDD motif mutation in HBV, but in terms of economy and practicability, mismatched PCR-RFLP is of greater significance in mass screening of YMDD motif mutant HBV than the other 2 approaches.

Journal Article↗
PubMed2001

Hot-spot mutations in HBV pre-C region in HBeAg-negative patients with severe hepatitis B.

OBJECTIVE: To investigate the association of hot-spot mutations in hepatitis B virus (HBV) pre-C region with the occurrence and outcome of severe hepatitis B. METHODS: A total of 68 patients with severe hepatitis B negative for hepatits B e antigen (HBeAg) were enrolled in this study, including 6 cases of acute, 38 cases of subacute and 24 chronic severe hepatitis B, with another 44 HBeAg-positive patients with chronic hepatitis B serving as control. Mismatch PCR and restriction fragment length polymorphism analysis were employed to examine the mutations of T1862 and A1896 in this 2 groups of patients. RESULTS: The mutation rates at A1896 and T1862 were 66.7% (4/6) and 0 (0/6) respectively in acute severe hepatitis B cases, 42.1% (16/38) and 15.8% (6/38) in subacute severe hepatitis, 25.0% (6/24) and 16.7% (4/24) in chronic severe hepatitis, and 45.5% (20/24) and 2.3% (1/44) in chronic hepatitis cases. There were significant differences in terms of T1862 mutation between patients with severe hepatitis and chronic hepatitis (P<0.01). CONCLUSION: T1862 mutation is closely related to the exacerbation of chronic hepatitis, while the role of A1896 mutation in this process requires further investigation.

Journal Article↗