Biomedical subjects

Bin Chen

Publications and source records attributed to Bin Chen.

At least 199 records · Page 11Linked to original sources

PubMed2002

Tuberous sclerosis complex: renal imaging findings.

PURPOSE: To review the renal imaging findings and changes over time in a large series of young patients with tuberous sclerosis complex (TSC). MATERIALS AND METHODS: One hundred thirty-nine renal imaging studies (113 ultrasonographic scans, 15 computed tomographic scans, and 11 magnetic resonance images) were identified in 59 patients with TSC (mean age, 11.4 years; age range, 3 days to 36 years). There were 31 male and 28 female patients. Angiomyolipomas and cysts were identified and characterized according to the following features: number, unilateral versus bilateral, largest diameter, and change over time. In patients whose initial examination results were normal, the age at onset of lesions was noted. The chi(2) test was used to determine whether cysts and angiomyolipomas occurred in different subpopulations. RESULTS: Angiomyolipomas were identified in 47 (80%) patients and were too numerous to count in 36 (76%), focal in 38 (81%), and bilateral in 42 (89%). The mean largest diameter was 21 mm. Cysts were identified in 28 (47%) patients, 18 (64%) of whom had fewer than five cysts. Cysts were bilateral in 17 (61%) patients. The mean largest diameter was 20 mm. In patients with initially normal examination results, the mean age at presentation was 9.0 years for those with cysts and 9.2 years for those with angiomyolipomas. In 80 follow-up examinations, size and/or number increased in 32 (40%) angiomyolipomas and 21 (26%) cysts. Cysts and angiomyolipomas did not occur in significantly different subpopulations (P =.13). CONCLUSION: Both angiomyolipomas and cysts occur commonly in pediatric patients with TSC and tend to increase in size and number with increasing age. Angiomyolipomas are more common than cysts and tend to be numerous.

Adolescent↗

PubMed2002

Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers.

Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

Carbon↗

PubMed2002

Antivascular tumor eradication by hypericin-mediated photodynamic therapy.

Photodynamic therapy (PDT) with hypericin has been shown to inhibit tumor growth in different tumor models, and tumor vascular damage was suggested to be mainly responsible for the antitumoral effect. Here, we demonstrate tumor vascular damage and its consequence on local tumor control after hypericin-mediated PDT by using both short and long drug-light intervals. Radiation-induced fibrosarcoma-1 tumors were exposed to laser light at either 0.5 or 6 h after a 5 mg/kg dose of hypericin. Tumor perfusion was monitored by fluorescein dye-exclusion assay and by Hoechst 33342 staining of functional blood vessels. Significant reduction in tumor perfusion was found immediately after both PDT treatments. A complete arrest of vascular perfusion was detected by 15 h after the 0.5 h-interval PDT, whereas well-perfused areas could still be found at this time in tumors after the 6 h-interval PDT. A histological study confirmed that primary vascular damage was involved in both PDT treatments. Tumor cells appeared intact shortly after light treatment, degenerated at later hours and became extensively pycnotic at 24 h after the 0.5 h-interval PDT. PDT under this condition led to complete tumor cure. In contrast, significant numbers of viable tumor cells, especially at the tumor periphery, were found histologically at 24 h after the 6 h-interval PDT. No tumor cure was obtained when PDT was performed at this time. Our results strongly suggest that targeting the tumor vasculature by applying short drug-light interval PDT with hypericin might be a promising way to eradicate solid tumors.

Animals↗

PubMed2002

Correlation on cine MR imaging of size of adenoid and palatine tonsils with degree of upper airway motion in asymptomatic sedated children.

OBJECTIVE: The objective of this study was to use MR fluoroscopy to evaluate variations in size of the adenoid and palatine tonsils and the relationship between tonsil enlargement and airway motion dynamics in asymptomatic children during sleep. SUBJECTS AND METHODS: We performed sagittal midline cine MR imaging (fast gradient-echo series: TR/TE, 8.2/3.6 sec; flip angle, 80 degrees; slice thickness, 8 mm; 128 consecutive images; imaging time, 2 min; displayed in cine mode) in children referred for MR imaging of the brain who required sedation. The largest transverse diameter of the adenoids was recorded. A subjective impression was made as to whether the adenoids were enlarged or normal in size. Palatine tonsils were considered enlarged when a soft-tissue mass was identified on the midline cine images, and maximum diameter was recorded. Enlarged and nonenlarged adenoid and palatine tonsil groups were compared using motion parameters (chi-square or Fisher's exact test): mouth position (opened or closed); vertical motion (present, absent); nasopharyngeal, oropharyngeal, and hypopharyngeal motion (static patent, dynamic patent, intermittent collapsed, or static collapsed, and greatest change in size). RESULTS: We studied 148 subjects who had a mean age of 3.4 years. The adenoid tonsils were considered enlarged in 64 patients (43%), and the palatine tonsils were considered enlarged in 29 patients (20%). The mean size of the enlarged adenoid tonsils was 11.6 mm and of the nonenlarged adenoid tonsils was 6.2 mm. Enlarged adenoids correlated with the open mouth position (p = 0.0242) and increased dynamic motion of the oropharynx (p = 0.0413). A trend was also seen for increased dynamic motion of the nasopharynx (p = 0.0723). Enlarged palatine tonsils correlated with an increased frequency of dynamic motion of the oropharynx (p = 0.0006) and the nasopharynx (p = 0.0033) and a trend for increased frequency of the open mouth position (p = 0.0692). CONCLUSION: Large adenoid and palatine tonsil size affects breathing dynamics of the upper airway even in asymptomatic children.

Adenoids↗

PubMed2002

Cytoarchitecture of the retinal ganglion cells in the rat.

PURPOSE: To determine the number and cytoarchitecture of retinal ganglion cells (RGCs) in the female Wistar rat, by using a newly devised procedure for rapid RGC counting in the entire retina that avoids assumptions about RGC spatial arrangement. METHODS: RGCs of normal female Wistar rats were retrogradely labeled with a fluorescent tracer. Automated counting was accomplished by applying standard imaging software to analysis of all labeled cells in retinal flatmounts. The method was validated by comparison of automated and manual counts of 70,000 RGCs in frames covering the density range in the normal rat retina of 600 to 3600 RGC/mm(2). RGC numbers were determined for each retina and compared with the contralateral retina of the same animal. RGC density maps were constructed for each retina. RGC size distribution was determined. RESULTS: Automated RGC counting showed a good linear correlation with manual counting (R(2) = 0.9416). Mean total RGC count in 10 rat eyes was 97,609 +/- 3,930 (SEM) per eye. Contralateral eyes differed by an average of 4.1% (3983 plus minus 5098 RGCs). Size analysis calculated from cell areas confirmed that the majority of rat RGCs are between 7 and 21.5 microm in equivalent diameter. The RGC counts for all frames at the same eccentricity in all 10 of the retinas showed that variability increased with eccentricity and increased further as the fractional area of the retina sampled at each eccentricity was reduced. There was also significant variability in the spatial density of the RGCs at the same eccentricity location between different eyes. Comparison of total RGC counts between left and right eyes estimated from RGC counts in sectors of the retina (hemiretinas or quadrants) showed increased variability compared with counting all the RGCs in a retina. CONCLUSIONS: RGCs in the Wistar rat display significant variability in their cytoarchitecture. Such variability can make quantification by sampling problematic for diffuse, and particularly, for focal RGC losses resulting from experimental interventions, unless virtually the entire RGC population is counted.

Animals↗

PubMed2002

Early and late outcomes in patients with severe extracranial internal carotid stenosis undergoing carotid endarterectomy.

OBJECTIVE: To determine the perioperative and late outcomes for carotid endarterectomy (CEA) in treatment of patients with high-grade stenotic lesions of the extracranial internal carotid artery. METHODS: Twenty patients underwent 21 CEAs at the Zhongshan Hospital between May 1993 and June 2000. They were 19 men and 1 woman, with a mean age of 64 +/- 9 years. Seven patients were performed for stroke, 11 for transient ischaemic attacks (TIAs) and 2 for asymptomatic disease. Duplex scan was the primary tool of evaluation prior to surgery. Perioperative digital subtraction angiography and magnetic resonance angiography were done for 19 and 18 patients, respectively. The percentage of stenosis was calculated using NASCET criteria. Of the 21 lesions operated, 19 had a stenosis of 70% or greater, 2 had ulcerative lesions with a stenosis ranging from 60% to 69%. All CEAs were performed under cervical block anaesthesia with selective intraoperative shunting and patch angioplasty. The patients were followed up regularly with duplex scan surveillance. RESULTS: There was no mortality or stroke during 30 days postoperatively. A TIA occurred in one patient and cranial nerve injury in 2 patients perioperatively. All patients were followed up for a mean interval of 31 +/- 20 months (range: 1 - 63 months). The 2-year survival rate and risk of stroke were 92.3% and 0%, respectively, and the 5-year survival rate and risk of stroke were 79.1% and 12.5%, respectively. Two asymptomatic recurrent stenoses ranging from 50% to 60% were detected on follow-up duplex scan. CONCLUSIONS: For the patients in this study, CEA is associated with an acceptable perioperative outcome as well as a satisfactory long-term beneficial effect in stroke prevention.

Aged↗

PubMed2002

[Early complications of surgery for chronic suppurative otitis media].

OBJECTIVE: To explore early post-operative complications following surgery for chronic suppurative otitis media. METHOD: From Jan 1992 to July 2000, 291 cases of chronic suppurative otitis media have been treated in our department. 79 cases underwent myringoplasty, 82 cases tympanoplasty, 88 cases modified radical mastoidectomy and 42 cases radical mastoidectomy. RESULT: Facial nerve palsies occurred in 3 cases (1.03%), bone conduction threshold elevation occurred in 13 cases (4.47%), wound infection occurred in 11 cases (3.78%), 7 patients (2.41%) reported symptoms related with chorda tympani trauma, symptoms of jaw discomfort were reported by 7 patients (2.41%) and imbalance or vertigo by 13 patients(4.47%). CONCLUSION: The incidence of early complications of surgery for chronic suppurative otitis media in this report was similar to previous reports.

Adolescent↗

PubMed2002

Nitric oxide synthase gene expression in injured spinal cord tissue.

OBJECTIVE: To investigate gene expression of three nitric oxide synthase isozymes in injured spinal cord tissue. METHODS: Thirty-six adult SD rats were randomly divided into six groups: a normal group and five injury groups, with six per each group. Animals in the injury groups were sacrificed at 2, 6, 12, 24, 48 h after injury. A compression injury model on the spinal cord was made according to Nystrom B et al and gene expression of the three NOS isozymes were examined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Gene expression of nNOS and eNOS were detectable in the normal group and were up-regulated quickly after injury, reaching a maximum at 6 h: (0.633 +/- 0.012) and (1.236 +/- 0.207). Gene expression of iNOS was detectable only in the injury groups and it was gradually up-regulated after injury, reaching a maximum at 24 h: (1.043 +/- 0.049). CONCLUSION: Injury to the spinal cord leads to early up-regulation of cNOS and late up-regulation of iNOS. Different NOS isozymes may play different roles in secondary spinal cord injury.

Animals↗

PubMed2002

Effect of X-ray irradiation on limb allograft rejection in adult rats.

OBJECTIVE: To establish appropriate animal models for observing the effects of X-ray irradiation on limb allograft rejection. METHODS: Wistar rats were used as donators and SD rats as recipients, the latter divided into 2 groups, namely irradiation group and non-irradiation group according to pretransplant treatment with or without X-ray radiation (5 Gy) on the part of the donators. The donor limbs were transplanted into SD rats who had their own limbs cut off, and the sciatic nerve, femoral nerve, and femoral artery and femoral vein were anastomosed in operation. After the operation, all the recipients were given benzathine benzylpenicillin, and their vital signs, together with changes of the allografts, observed. RESULTS: A total of 16 rats received transplantation that was successful in 6 rats of non-radiation group and 7 of irradiation group. The graft survival averaged 12.0+/-2.4 d in non-irradiation group and 24.7+/-8.1 d in irradiation group, showing significant difference in the lengths of survival between the 2 groups (P<0.05). CONCLUSION: The graft survival time in rats can be significantly prolonged by pretransplant irradiation of the allograft, which also help control acute rejection of the allograft.

Animals↗

PubMed2002

[mRNA expression of recombinant human bone morphogenetic protein 7 in skeletal muscle satellite cells with retroviral vector-mediated rhBMP7 gene transfection].

OBJECTIVE: To detect the expression of recombinant human bone morphogenetic protein7 (rhBMP7) in skeletal muscle satellite cells (SMSCs) with rhBMP7 gene transfection mediated by retroviral vector. METHODS: rhBMP7 gene was reconstructed in retroviral vector and transferred into packaging cells PT67 via liposome reagent, with the positive cell clones selected with G418. In vitro cultured SMSCs were transfected with the virus granules secreted by PT67 cells and followed by G418 selection. Reverse transcriptase-polymerase chain reaction was utilized for analysis for rhBMP7 mRNA in the transfected cells. RESULTS: rhBMP7 retrovirus vector was successfully constructed and transferred into PT67 cells, and abundant mRNA expression of rhBMP7 was observed in the skeletal muscle satellite cells transfected with the virus and selected with G418. CONCLUSION: rhBMP7 gene can be transferred into the skeletal muscle satellite cells via retroviral vector to yield effective rhBMP7 mRNA expression.

Animals↗

PubMed2002

[Expression of human bone morphogenetic protein 7 mRNA after the gene transfection in rabbit bone marrow-derived mesenchymal stem cells].

OBJECTIVE: To detect the expression of human bone morphogenetic protein 7 (hBMP-7) mRNA in rabbit bone marrow-derived mesenchymal stem cells with hBMP-7 gene transfection mediated by retroviral vector. METHODS: Retroviral vector for hBMP-7 gene was constructed that was transferred into the packaging cell PT67 mediated by liposome. hBMP-7 gene-positive cell clones were selected with G418 (600 ng/ml) and amplified to obtain the retroviral supernatant containing the target genes that were subsequently used to transfect rabbit bone marrow-derived mesenchymal stem cells (MSCs). HBMP-7 mRNA expression in the MSCs was examined by way of in situ hybridization and reverse transcriptase-polymerase chain reaction. RESULTS: hBMP-7 retroviral vector was successfully constructed and transferred into PT67 cells with resistance to G418, and after transfection with the recombinant retrovirus, transcription and expression of hBMP-7 mRNA were detected in MSCs. CONCLUSION: Rabbit bone marrow stem cells transfected with hBMP gene via retroviral vector can secrete the correspondent protein, indicating the possibility of enhancing the osteogenic capacity of MSCs in the study of bone tissue engineering.

3T3 Cells↗

PubMed2002

[Repair of tibial defect with tissue-engineered bone graft and radionuclide bone imaging in goats].

OBJECTIVE: To observe the effect of tissue-engineered bone grafts in repairing large tibial defect in goats, and assess the value of radionuclide bone imaging in monitoring the therapeutic effect of this approach. METHODS: Tibial defects measuring 2 cm was artificially made in the left tibia of 27 normal goats that were subsequently divided into 3 groups (9 each) to undergo treatment with tissue-engineered bone grafts, artificial bone grafts or without any grafts (as control group) respectively. The tissue-engineered bone grafts contained bone marrow stroma cells (BMSCs) of the goats and coral hydroxyapatite (CHAP), while the artificial bone grafts were from CHAP only. After the operations, radionuclide bone imaging was used to monitor the therapeutic effects at 2, 4 and 8 postoperative weeks. RESULTS: The 99mTc-MDP uptake of the region of interest (ROI) and the target to non-target ratios (T/NT) of the control group did not indicate any process of revascularization or bone regeneration. An increasing tendency of the revascularization and bone regeneration, in contrast, was observed in goats receiving the artificial bone grafts, a tendency that was far more obvious in the goats with tissue-engineered bone grafts. CONCLUSION: Tissue-engineered bone graft is eligible in repairing large defect in the caprine tibia, and radionuclide bone imaging may accurately monitor the revascularization and bone regeneration after the bone graft implantation.

Animals↗

PubMed2002

[Biocompatibility of adult human osteoblasts with coral-derived hydroxyapatite in vitro].

OBJECTIVE: To study the biocompatibility of the osteoblasts from adult human bone marrow with coral-derived hydroxyapatite (CHA) in in vitro culture. METHODS: Bone marrow was obtained from healthy adult subjects and cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10 % fetal bovine serum. The subsequent cell passaging was conducted in conditioned medium containing dexamethasone, beta-sodium glycerophosphate and ascorbic acid, with the osteoblasts in culture then divided into CHA group (in which the cells were cultured with CHA) and osteoblasts group (without CHA). The proliferation and differentiation of all the cultured cells were observed at different time points under inverted phase contrast microscope, optical microscope with HE staining and scanning electron microscope respectively. Proliferation of the cultured cells were evaluated by MTT assay, and the activity of alkaline phosphatase and total micro-protein contents in these cultured osteoblasts were quantitatively detected. RESULTS: The osteoblasts from adult human bone marrow grow well in vitro, regardless of the presence of CHA, with biological and morphological characteristics similar to those of normal osteoblasts. CHA improved the adhesion, growth and proliferation of the cultured cells, showing no adverse effects on the cell functions. CONCLUSION: CHA is an optimal scaffold material for bone tissue engineering, which may potentially find clinical application for bone defect repair.

Adult↗

PubMed2002

[An experimental study of the inhibition of tamoxifen on rat model of benign prostatic hyperplasia].

OBJECTIVES: To study the inhibitory mechanism of tamoxifen on benign prostatic hyperplasia. METHODS: The Wistar male adult rats were injected into muscle with testosterone propionate 4-6 mg/kg, simultaneously were irrigated into stomach with tamoxifen citrate 0.21 mg/kg. The partly rats of each group were decapitated at 7, 15 and 30 days, then their index numbers of prostate were calculated, and the structural changes of the prostatic histocyte were observed in the light microscopy and scan electronic microscopy. RESULTS: At the 7th, 15th, and 30th day, the index numbers of prostate of those rats which had been injected only with testosterone propionate were higher than that of the control group and the irrigating group(P < 0.05). The hyperplasia of the prostatic epithelial cells and the ground substance of those rats, which had been irrigated with tamoxifen citrate, had not happened in light microscopy and the scan electronic microscopy. CONCLUSIONS: Tamoxifen could block the effect of the estrogen, which could suppress the prostatic hyperplasia. This study could provide the experimental evidences for using Tamoxifen to treat the human benign prostatic hyperplasia.

Animals↗

PubMed2002

[Studies on chemical constituents in fruit of Eucalyptus globulus].

OBJECTIVE: AIM To study the chemical constituents of the fruit of Eucalyptus globulus. METHOD: Various column chromatographies with silica gel were employed for the isolation and purification. The structures of the compounds were elucidated with of spectral analyses and chemical methods. RESULT: Five compounds were isolated and elucidated as follows: betulonic acid (I), betulinic acid (II), ursolic acid (III), corosolic acid (IV), daucosterol (V). CONCLUSION: Compound I, II, III and IV were isolated from this plant for the first time.

Eucalyptus↗

PubMed2002

[The rapid analysis of functional components of P. Lobata by near infrared spectrum].

The functional components of P. Lobata were analyzed rapidly by near infrared (NIR) spectral technology. The optimum conditions of mathematics model of three components (total isoflavones, puerarin, daidzin) were studied, including the sample set selection, chemical value analysis, the detection methods and conditions. The analytical results demonstrated that the correlation between the chemical value (true value) of the three components of sample set and the NIR predicated value is 0.975, 0.984, 0.996, respectively. The correlation between the chemical value of the testing sample set and the NIR predicated value is 0.982, 0.975 and 0.981, respectively. It proved that the mathematical model that we established can be used in practice.

Isoflavones↗

PubMed2002

[Charge transfer interaction of atropinum with sigma-electron acceptor and application research].

The charge transfer interaction of vitriol atropinum with iodine in the chloroform was studied. Iodine interacts with atropinum in the chloroform and forms the purple and brown charge transfer complexation. From the ultraviolet spectrum, it is confirmed that the maximum wavelength of the complexation is 280 nm and the apparent molar absorptivities of the complexation is 2.66 x 10(4) L.mol-1.cm-1. Using the equal mole consecutive change method, it is confirmed that the molar combining ratio is 1:1. The reaction mechanism is studied and it is confirmed that the complexation is a kind of supramolecule compound, which is in the syntonic mixed state of non-bonding structure and charge transfer. On the base of the complexation, the method that is used to determine vitriol atropinum injection by the charge transfer spectrophotometry is founded. And the optimal condition of the method was studied. The experiment showed that when the volume ratio of iodine and vitriol atropinum was 2:1, the value of the absorbency of the reaction system was almost stable and the reaction should last out for 20 minutes at room temperature. The method is simple and convenient, short-cut, exclusive. The linear range is 0-35 micrograms.mL-1, the reclaim rate is 99.6%, RSD is 0.83%.

Atropine↗

PubMed2002

[Determination of trace barium in mineral water with oxygen enriched air-acetylene flame in atomic absorption spectrometry].

In this paper, the determination of Ba using oxygen enriched air-acetylene flame in AAS has been studied and the effect of acetylene flow, oxygen flow and the ratio of O2/C2H2 on the absorbance have been compared. When the amount of oxygen is 52% in mixed gas and the ratio of O2/C2H2 is about 0.72, higher sensitivity for Ba can be obtained. In this flame acids and most of elements did not interfere. By adding 1,000 mg.L-1 K the interference can be minimized and the sensitivity for the determination of Ba can be increased. The sensitivity of the method is 0.16 mg.L-1/1%, the detection limit is 0.034 mg.L-1, and the relative standard deviation is 2.5%. The analytical results of the standard reference material (GBW08301 and GSD-6) by this method are consistent with the certified values, and it was proved that this method are reliable and is suitable for the determination of Ba in mineral water.

Acetylene↗