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Biomedical subjects

J Chen

Publications and source records attributed to J Chen.

At least 703 records · Page 39Linked to original sources
PubMed2001

A study on the preservation of fresh amniotic membrane.

OBJECTIVE: To establish the standard preservation methods of fresh amniotic membrane for clinical use. METHODS: Human placentas were collected aseptically from selective caesarean sections in normal women in time. Amniotic or placental membrane were peeled and preserved in N. S, P. B. S or DMEM at 4 degrees C or cultured in DMEM at 37 degrees C, 5% CO2. Trypan-blue staining, light and electronic microscopy were observed every six hours after preservation. RESULTS: Seventy percent of amniotic epithelial cells survived after preservation in N.S for 6 hours, PBS 12 hours, DMEM 24 hours and 1 week in tissue culture. The amount of living epithelial cells maintained in placental membrane preservation was less than that in amniotic membrane preservation at the same time (t-test, P < 0.01). No collagen degeneration was found during preservation. CONCLUSION: Preservative solution and time will affect the maintenance time of fresh amniotic membrane greatly. Fresh amniotic membrane should be preserved within 6 hours in N. S, 12 hours in P. B. S, 24 hours in DMEM at 4 degrees C and 1 week in tissue culture for clinical use.

Adult↗
PubMed2001

[Comparing cryopreserved with fresh corneas on clinical application in penetrating keratoplasty].

PURPOSE: To evaluate the role of cryopreserved corneas on penetrating keratoplasty (PKP) by comparing them with fresh corneas on clinical application. METHODS: Third-six excellent condition patients were chosen and randomly divided into two groups. They were performed PKP by using fresh and cryopreserved corneas respectively. The graft transparency, epithelial healing speed of graft, tear membrane, graft thickness, endothelium density and visual acurity were emphasized respectively. RESULTS: When fresh and cryopreserved corneas were used on PKP as the donor respectively, postoperative time to recover normal break-up time (BUT) was two to six months average (4.7 +/- 0.3) months and two to eight months, average (5.6 +/- 0.4) months and time to recover normal Schirmer's test was one to four months average (2.1 +/- 0.3) months and 1-3.5 months, average (1.7 +/- 0.5) months. The graft's thickness, stabilized visual acurity and graft's rejective rate were 0.56-0.68 mm (average 0.62 mm) vs 0.54-0.62 mm (average 0.59 mm), (0.46 +/- 0.03) vs (0.44 +/- 0.05) and 20% vs 19% respectively when fresh vs cryoperserved corneas. No statistical significance between fresh and cryopreserved corneas (P > 0.05). But the grafts behaved intact epithelium and continuing transparency when fresh corneas as donors, while the graft's epithelial defects healed after three to five days of the operation and edematous grafts were reclear after two to three weeks of the operation when cryopreserved corneas as donors. Graft's endothelium density in fresh corneas group 2,043-2,210 cells/mm2 (average 2,135 cells/mm2) was high than in cryopreserved corneas 1,240-1,860 cells/mm2 (average 1,672 cells/mm2) (P < 0.01). CONCLUSION: There were no statistical significance on the transparent rate of grafts, grafts thickness, visual acurity and graft's rejective rate between fresh and cryopreserved corneas. But graft's epithelium healing was delayed and endothelium density was lower when cryopreserved corneas as donors.

Adolescent↗
PubMed2001

[The study on effects of rhEGF on proliferation of human conjunctival epithelial cells].

PURPOSE: To investigate the effects of Recombinant Human Epidermal Growth Factor (rhEGF) on proliferation of human conjunctival epithelial cells and optimal dose in vitro. METHODS: Cultured human conjunctival epithelial cells were plated in 96-well plates at a density of 2,000 cells per chamber, treated with different concentrations of rhEGF (100 micrograms/ml, 50 micrograms/ml, 20 micrograms/ml, 10 micrograms/ml, 5 micrograms/ml and 1 microgram/ml). After 24, 48, 72 and 96 hours of treatment, cell viability was assessed with MTT assay. RESULTS: There was no significant difference in all experimental groups and the control group in the first 24 horus. Experimental groups at a concentration of 50 micrograms/ml, 20 micrograms/ml and 10 micrograms/ml had significantly higher cell viability than which of the control group 48 hours later. All groups of rhEGF had significantly higher cell viability than which of the control group after 72 hours treatment, except for 100 micrograms/ml of rhEGF. Each group of rhEGF after 96 hours treatment had higher cell viability than which of the control group, and 100 micrograms/ml of rhEGF had lower cell viability than which of the other experimental groups, with significant difference. CONCLUSION: rhEGF enhance proliferation of human conjunctival epithelial cells effectively in vitro. The optimal concentration ranged from 10 micrograms/ml to 50 micrograms/ml.

Cell Division↗
PubMed2001

[Effect of ginsenoside Rg1 on learning and memory impairment induced by beta-amyloid peptide(25-35) and its mechanism of action].

AIM: To study the effect of ginsenoside Rg1 on the learning and memory impairment in mice induced by aggregated beta-AP(25-35). METHODS: Mice were administered Rg1(5, 10 mg.kg-1, i.p.) for 10 d and control mice received daily i.p. injections of saline after the intracerebroventricular injection of aggregated beta-AP(25-35). After the final treatment, passive avoidance and performance in the Morris water maze (MWM) were assessed. and the activity of cortical and hippocampal ChAT and AchE were detected after the final behavior test. RESULTS: Ginsenoside Rg1 (5, 10 mg.kg-1, i.p.) significantly ameliorated the learning and memory impairment induced by beta-AP(25-35). Rg1 (5, 10 mg.kg-1) decreased the latencies and swim distances of mice to reach a hidden platform and improved the corresponding changes in search strategies occurred in the Morris water maze, and Rg1 (10 mg.kg-1, i.p.), increased step-through latencies also. Biochemical analysis showed that Rg1 (5, 10 mg.kg-1, i.p.), prevented the cortical and hippocampal ChAT activity decline induced by beta-AP(25-35), and showed inhibition of the activity of AchE, although beta-AP(25-35) showed no effect on the cortical and hippocampal AchE activity. CONCLUSION: These data showed that ginsenoside Rg1 significantly improved the learning and memory impairment induced by beta-AP(25-35), and this effect could be attributed to its inhibition of AchE and increase of ChAT activity.

Acetylcholinesterase↗
PubMed2001

[Study on the structural property of polysacchrides 139A--a kind of IL-1R antagonists from microorganism].

AIM: To study the structural property of the bioactive component from the fermentation broth of Streptomyces 139 which can inhibit IL-1R. METHODS: Polysaccharide 139A is extracted and purified by means of macroreticular resin Diaion HP-20, cation exchange and DEAE Sephadex A-25 chromatography. The sugar compositions were analyzed with GC, the linkage positions of 139A were determined by methylation and GC-MS. RESULTS: The bioactive component which can inhibit IL-1R is a kind of polysaccharides. CONCLUSION: The components of 139A repeat units are conjectured.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

[Effect on proliferation and apoptosis of human lingual carcinoma cells cotransfected by bax and p53 genes].

OBJECTIVE: To investigate the effects on proliferation and apoptosis of human cancerous cells cotransfected by bax apoptosis-inducing gene and p53 tumor suppressor gene. METHODS: The chimeric gene pSV-CIP-bax-CAT was constructed in which bax gene was flanked upstream by a 217 bp fragment(+822(-)+1093) of the first intron and a 317 bp promoter fragment of human a 1(I) collagen gene. Human lingual carcinoma cell line Tca 8113 (LCC) in culture was respectively transfected with pSV-CIP-bax-CAT, and cotransfected with pSV-p53-CAT and pSV-CIP-bax-CAT by using the transfection reagent DOSPER. RESULTS: Immuno-slot blot and ELISA demonstrated that the expression of bax and p53 genes increased remarkably in the transfected and cotransfected LCC, compared with the controls (LCC transfected with pSV-CIP-CAT and LCC). MTT colorimetric assay, TUNEL fluorenscence microscopy and flow cytometry showed that foreign bax or p53 gene inhibited the LCC growth and induced apoptosis (23.9% and 26.1% of inhibitory rate by bax gene and p53 plus bax genes respectively). CONCLUSION: The ectopic expression of the bax gene in the LCC promoted by the cis-acting elements of human a1 (I)collagen gene has obviously synergistic effect on the proliferation and apoptosis of the LCC contransfected with p53 gene plus bax gene for 48 hours.

Apoptosis↗
PubMed2001

[Study on the chemosensitivity test of human gastric cancer using the MTT assay].

OBJECTIVE: This study was conducted to investigate the chemosensitivity of gastric carcinoma. METHODS: 112 cases of fresh human gastric cancer samples were obtained for drug sensitivity testing using MTT. RESULTS: The sensitivity sequence of antitumor agents was 5-Fu, DDP, MMC, etc. On the other hand, the sensitivity was relative to pathology and individual differences. CONCLUSION: The MTT assay is an accurate system for determination of the chemosensitivity of tumor cells.

Adenocarcinoma↗
PubMed2001

[Expression of alpha and beta subunit isoforms of Na, K-ATPase in the guinea pig endolymphatic sac].

OBJECTIVE: To investigate the expression and significance of alpha and beta subunit isoforms of Na, K-ATPase in the guinea pig endolymphatic sac. METHODS: The distribution of alpha and beta subunit isoforms of Na, K-ATPase in endolymphatic sac of guinea pig was identified by immunocytochemistry and in situ hybridization. RESULTS: The expression of Na, K-ATPase alpha and beta subunit isoforms varied among different cell regions of the endolymphatic sac. Epithelial cells of the endolymphatic sac were observed to contain the alpha 1, beta 1 and beta 2 subunit isoforms, and the expression of beta 2 was stronger than that of beta 1. Subepithelial cells contained alpha 1 and alpha 2 subunit isoforms and the expression of alpha 1 was stronger than that of alpha 2. No expression of alpha 3 subunit isoform was observed in endolymphatic sac. CONCLUSION: Na, K-ATPase of endolymphatic sac consists of different alpha and beta subunit isoforms which, working in concert, serve to maintain homeostasis in inner ear.

Animals↗
PubMed2001

The management of epithelial ingrowth after laser in situ keratomileusis.

OBJECTIVE: . To investigate the treatment of corneal epithelial ingrowth with flap melt after LASIK. PATIENTS AND METHOD: Thirteen eyes of 13 patients with corneal epithelial ingrowth and flap melt after LASIK were treated based on the thickness and the extent of melting of the flap. Nine eyes were treated by lifting the flap and scraping the epithelium in the interface. Three eyes underwent allogenic keratomileusis. The flap was removed in one eye. RESULTS: Recurrence occurred in 2 eyes treated by lifting the flap. The flaps, however, healed normally after retreatment. The grafts healed normally in the allogenic keratomileusis group, except for one eye in which the flap was lost. The corneal epithelium healed over the stromal bed after the flap was removed. Corneal haze of grade 2 was present at 6 months. The uncorrected visual acuity was between 0.3 and 1.0, and the best-corrected visual acuity lost 1 to 3 lines. CONCLUSIONS: Corneal epithelial ingrowth with flap melt is a severe complication after LASIK. However, with proper treatment, vision can be salvaged in most cases.

Corneal Diseases↗
PubMed2001

[Analysis of 128 Wilson's disease].

OBJECTIVE: To investigate the clinical feature and misdiagnosis of 128 patients with Wilson's disease and propose the points of diagnosis for this disease. METHOD: 128 patients with Wilson's disease from Jan. 1983-Apr. 2000 admitted to our hospital were reviewed. Their clinical feature and diagnosis condition, such as the early onset symptoms, misdiagnosis and hypersplenism were studied. RESULTS: 1. The first onset symptoms: 64 were liver dysfunction and 52 were manifestations of CNS (P > 0.05). 2. The average age of patients with liver dysfunction was significantly younger (13 +/- 3.5 years) than that of CNS manifestations (23 +/- 8.3 years, P < 0.05). 3. The positive rate of cornea Kayser-Fleischer ring was 96.8%; the value of copper oxidase absorbency was 0.051 +/- 0.024 (0.01-0.16) and its positive rate was 93%. 4. The overall misdiagnosis rate was 42.9% (55/128) and the predominant mis-diagnostic diseases were hepatitis A and chronic hepatitis. CONCLUSION: The clinical manifestations are diverse, which make the misdiagnosis rate very high. The age of liver dysfunction patients is significantly younger than that of the CNS manifestations patients. Cornea Kayser-Fleischer ring and copper oxidase absorbency are of high positive rate, as it can be carried out conveniently in clinics we recommends to use this diagnostic measure for Wilson's disease.

Adolescent↗
PubMed2001

[Gene clone of autoantigen hnRNP A2/B1 and research on expression in synovium].

OBJECTIVE: To investigate hnRNPA2/B1's role in rheumatoid synovitis by obtaining its cDNA sequence and analyzing its expression in synovium. METHODS: Total RNA was isolated from peripheral blood mononuclear cells (PBMC) and the RT-PCR was performed. The fragment was cloned into PUC-T1 plasmids and further sequenced. We detected it's expression in synovium with monoclonal antibodies and specific cDNA probes by immunohistochemistry and in situ hybridization. RESULTS: The fragment was identified by DNA sequencing. The expression in rheumatoid synovium was higher than that from osteoarthritis and the normal controls (P < 0.05). CONCLUSION: hnRNP A2/B1 cDNA has been cloned successfully and hnRNP A2/B1 might play an important role in rheumatoid synovitis.

Adult↗
PubMed2001

[Survivin--a new tumor-specific anti-apoptosis factor].

Survivin (SVV) is a new member of IAP-family (inhibitor of apoptosis, IAP) proteins. It can inhibit apoptosis induced by a variety of factors, and plays important roles during mitosis and cytokinesis of cells. Studies indicated that it is a tumor-specific anti-apoptosis factor. Survivin is expressed during embryonal development but lacks expression in terminally differentiated adult tissues. Interestingly, it becomes reexpressed in transformed cell lines and in a variety of human tumors. Its overexpression is prognostic of tumors and is implicated in the resistance to chemotherapy of tumor cells. SVV may be a new and widely applicable target for gene- and protein-based therapy of tumors.

Apoptosis↗
PubMed2001

[ARHI mRNA and protein expression in pancreatic cancers].

OBJECTIVE: To investigate ARHI mRNA and protein expression in pancreatic cancers. METHODS: Fifty-seven paraffin-embedded resected cancer samples and patient-corresponding normal pancreatic tissues were determined by using immunohistochemistry staining and in situ hybridization method. RESULTS: The positive rate of ARHI mRNA and protein expression in normal control pancreatic tissue was 84.2% and 82.5% respectively, and in cancer group was 52.6% both. The positive rate of mRNA and protein expression in cancer group was markedly decreased (P < 0.01). Yet the protein expression correlated with mRNA. Furthermore, positive staining of ARHI protein and mRNA can be observed in duodenal mucus epithelium, fibroblasts, smooth muscle myocytes, and wall of blood vessels. There was no correlation between positive rate and cancer differentiation, or clinical stages. CONCLUSIONS: ARHI protein expression is down-regulated in pancreatic cancer, possibly plays a role as tumor suppress gene, ARHI protein expressed in multiple types of tissues including duodenal mucus epithelium, fibroblasts and so on.

Adult↗
PubMed2001

[Raman spectra for YVO4 and Nd:YVO4 crystals].

In this paper, the measured Raman spectra of YVO4 and Nd: YVO4 crystals were reported. These results give a clear information on the phonon energy spectra, these are several discrete phonons in low energy region, then nothing shows up in a large space from 500-800 cm-1 and main portion of phonon spectra is distributed in the region of 800-900 cm-1. Based on the group theory, the symmetries for Raman lines can be deduced, and they are almost due to the vibration of VO(4)3- ion. The effect of uneven distribution for phonon spectra on the optical transition and laser performance are discussed. The restraint action of doped ion on the high energy phonon is found.

Crystallization↗
PubMed2001

[Analysis of the lineshape of laser frequency modulation].

In this paper, we analyze the dependence of the output signal spectral lineshape and intensity on the modulation, waveform and modulation index in first- and second-harmonic detection of triangle modulation, square demodulation and saw modulation square demodulation. The signal lineshape in the case of saw modulation, square demodulation is quite different from, whereas the signal lineshape in the case of triangle modulation, square demodulation is similar to that in traditional sine modulation, sine demodulation. Experiments of tunable IR laser frequency modulation absorption spectrum of methane are also done to verify the theoretical analysis. Then we reach a conclusion; the lineshape and intensity of frequency modulation spectrum can be influenced by modulation waveform, demodulation waveform and modulation index. Calculation results can be used to choose better experimental parameters and optimize experimental designs.

Algorithms↗
PubMed2001

[Calculation of spectroscopic parameters of Ho3+ in Ho:YVO4 crystal].

The intensity parameters omega lambda of Ho3+ in Ho:YVO4 crystal were calculated with J-O theory according to the absorption spectrum. Based on these omega lambda values, the oscillator strength of excited energy state, spontaneous radiation rate, branching ratio and integrated emission cross section were estimated. A discussion on potentiality of application in the infrared laser material is given.

Chemical Phenomena↗
PubMed2001

[Study of "living" radical polymerization by FTIR in situ].

Three types of living radical polymerization processes were monitored by means of FTIR spectrometer with handful diamond detector called as Dicomp in situ. It was found that both styrene and styrene/hydroxylpropyl methyacrylate (HPMA) could polymerize according to stable free radical polymerization (SFRP) mechanism in presence of 4-hydroxyl tetramethypiperidiyl-1-oxy(HTEMPO). For styrene/HPMA system, the styrene and HPMA conversion monitored by FTIR were linear with increase of molecular weight, but it gave longer induction period compared with that for St bulk polymerization. It was related to the hydrogen-transfer reaction between the propagating radicals with the end HPMA unit and HTEMPO. Furthermore, This following method in situ could be introduced into monitoring heterogeneous polymerization of styrene during atom transfer radical polymerization (ATRP). The apparent kinetics was found to be about zero order and not 1.0 order, due to propagating on the complex including radicals, CuX and bpy in heterogeneous interface. The polymerization rate will be not related to the St in bulk St phase.

Acrylamides↗