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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 865 records · Page 48Linked to original sources
PubMed1997

[Mechanism of taxol-induced apoptosis in human breast cancer cells].

OBJECTIVE: To investigate the mechanism by which taxol induces apoptosis in human breast cancer cells. METHODS: Cell morphology, agarose gel electrophoresis, flow cytometry, video time-lapse monitor and Western blot were performed for taxol-induced apoptosis in human breast cancer cells (Bcap 37). RESULTS: BCap 37 cells treated with taxol (100 nm) underwent the arrests of cell mitosis at metaphase of mitosis and induction of apoptosis. Apoptotic cells demonstrated cell shringkage, condensation and fragmentation of chromosomes. Nuclear DNA of apoptotic cells displayed ladder bands characteristic of internucleosomal DNA fragmentation. The expression of bcl-2, inhibitor of apoptosis, was decreased with modification, while that of bax, inducer of apoptosis, increased only at early stage of the apoptotic pathway and decreased later. CONCLUSION: In human breast cancer cells the induction of apoptosis by taxol was closely associated with mitotic arrest of cell cycle, and altered expression of bcl-2 and bax gene, possibly playing an important role in regulating taxol-induced apoptosis.

Antineoplastic Agents, Phytogenic↗
PubMed1997

[Determination of mangiferin in qingqiliangying injection by reversed-phase HPLC].

A reversed-phase HPLC method has been established for the determination of mangiferin in Qingqiliangying Injection. The mangiferin was separated on a Nova-pak C18 column (150 mm x 3.9 mm) and detected at 258 nm, using methanol-tetrahydrofuran-0.85% H3PO4 aqueous solution (500:80:15) as the mobile phase. The average recovery of mangiferin was 100.9%. The method is simple, rapid, and well reproducible, and thus very reliable for the quality control of Qingqiliangying Injection.

Chromatography, High Pressure Liquid↗
PubMed1997

The preliminary report of epikeratophakia in the treatment of pediatric aphakia after traumatic cataract extraction.

PURPOSE: To study the role of epikeratophakia in treating pediatric unilateral aphakia after traumatic cataract extraction. METHODS: We performed epikeratophakia in 43 children to treat aphakia after traumatic cataract extraction, using the corneal lenses made by ourselves. The rehabilitation of the the postoperative vision and the prevention of amblyopia were observed with a mean follow-up period of 20 months. RESULTS: All the lenses remained transparent. Postoperatively, 31 cases (72.1%) achieved uncorrected visual acuities (V.A) over 0.2, 32 cases (74.4%) achieved corrected V.A over 0.4. Most of the cases achieved the best preoperative corrected V.A with spectacles of less than 3 diopters. No severe complication occurred. CONCLUSION: Epikeratophakia is predictable with quality lens and correct surgical technique. The result suggests that the epikeratophakia is one of the best treatment for the pediatric aphakia especially for those who are not optimal for IOL implantation.

Adolescent↗
PubMed1997

[A preliminary report of epikeratophakia for the treatment of Terrien's degeneration].

PURPOSE: To evaluate the efficacy of epikeratophakia for the treatment of severe Terrien's degeneration. METHODS: Four eyes with severe Terrien's corneal degeneration are studied. The lesions were located at the peripheral cornea and the corneal thickness was less then 1/3 of normal. Plano keratoplasty was performed. A lamellar lenticule with a 2 mm scleral rim was grafted on the cornea of which the epithelium had been removed. Keratometry and cycloplegic refraction were performed pre- and post-operatively. RESULTS: Follow-up was between 3 and 13 months (mean, 10 months). All grafts remain clear. The properative mean cylinder was 11.5 diopters and the postoperative mean cylinder was 3.9 diopters. Best corrected visual acuity was improved in 3 eyes. Interface opacification is the main complication, like other forms of epikeratoplasty. Epithelial ingrowth occurred in one eye and the lenticule was replaced. CONCLUSIONS: Epikeratophakia is a simple and effective way for the treatment of severe Terrien's degeneration. This procedure not only increases the corneal thickness, but also hepls the cornea to preserve its transparency, since the Bowman's layer remains intact.

Adult↗
PubMed1997

[The combined procedure of limbal transplantation (LT) and penetrating keratoplasty (PK) for severe ocular obsolete chemical or thermal burns].

PURPOSE: To improve the prognosis of grafts for obsolete ocular chemical or thermal burns. METHODS: LT + PK or PK were performed in 28 eyes with severe chemical or thermal burns. The effects of the two groups were compared. RESULTS: In LT + PK group(12 eyes), during 5 to 28 months of follow-up, the results showed improved visual acuity in 9 eyes (75%), maintained stable epithelial adhesion without recurrent erosion or persistent epithelial defect in 11 eyes (91.67%), graft transparent in 9 eyes (75%). Nine eyes (75%) showed prevented neovascularization and conjunctival tissue from growing into graft. Allograft rejection were identified in 4 eyes (33.33%). In routine PK group (16 eyes), during 3 to 22 months of follow-up, the results showed improved visual acuity in 4 eyes (25%), maintained stable epithelial adhesion without recurrent erosion or PCED in 8 eyes (50%), graft transparent in 4 eyes (25%). Four eyes (25%) showed prevented neovascularization and conjunctival tissue from growing into cornea. CONCLUSIONS: Combined procedure of LT and PK is an effective treatment for severe ocular chemical or thermal burns. It can reduce persistent corneal epithelial defect and prevent neovascularization and conjunctival epithelial from growing into cornea thus maintaining graft transparent and improving visual acuity.

Adolescent↗
PubMed1997

[The study on analgesic effect of local-release delivery system--Huangjiabang].

Laboratory investigation was made on analgesic effect of local release delivery system, Huangjiabang, which mainly includes Chinese medical herbs. Through the application of twisting-body and thermal-plate experiments on white rats. The result showed that the pain threshold was markedly elevated (P < 0.05, P < 0.001) after the rats were fed with Huangjiabang 125 mg/kg or 250 mg/kg body weight, and the number of twisting body's animals significantly decreased (P < 0.001). The analgestic mechanism of Huangjiabang delivery system relates to its effect of invigorating the circulation of blood and accelerating the stasis assimilation, remitting the inflammation.

Analgesics, Non-Narcotic↗
PubMed1997

[Clinical and pathological study on liver fibrosis in viral hepatitis].

49 patients with viral hepatitis were studied on the correlationship between liver fibrosis and the level of serum precollagen type III (PC III), pre-collagen III pre-peptide (P III P), Laminin (LN), hyaluronic acid (HA) and collagen type IV (IV-C), as well as relationship between them and the expression of LN, IV-C, a-smooth muscle actin (a-SMA) and cytokeration (CK) in the liver tissues examined by immunohistochemistry. Results showed that the level of PC III, P III P, LN, HA and IV-C in the groups of liver cirrhosis and chronic severe hepatitis were higher than that in the groups of acute and chronic hepatitis. High correlation was found between the level of these markers (especially the level of the IV-C) and the degree of fibrosis in the group of chronic hepatitis. So were the expression of LN, IV-C, a-SMA and CK in the liver tissue. The results also showed that the liver fibrosis correlated with inflammatory reaction in the liver. So the authors suggested that more attention should be paid to the inflammatory reaction of the liver for prevention and treatment of liver fibrosis.

Adolescent↗
PubMed1997

[In situ detection of DNA strand breaks associated with apoptosis in viral hepatitis].

The significance of apoptosis in liver injury or liver fibrosis in viral hepatitis is yet unknown. The authors investigated the hepatocyte apoptosis and the correlation between the apoptosis and the liver injury in 22 liver biopsy specimens from the patients with hepatitis. Specimens were put onto slides to detect DNA strand breaks in situ with nick end labeling method using terminal deoxynucleotide transferase and bio-11-dUTP (TUNEL). The results showed that most of TUNEL-positive hepatocytes which have the features of apoptosis were apoptotic hepatocytes. There was TUNEL-positive reaction in few of the hepatocytes with ballooning degeneration. The degree of apoptotic hepatocytes in the chronic hepatitis was stronger than that in the acute hepatitis. This suggested that the degree of apoptotic hepatocytes correlated with the chronicity of hepatitis.

Apoptosis↗
PubMed1997

[Study on enterovirus aetiology of CNS infection in Shantou].

Enterovirus isolation and serological assay were done in 236 cases of CNS infection in Shantou. 62 strains of virus (from 55 cases) were isolated from 257 samples of 236 cases (24.1%). 48 cases were positive among 57 cases (84.2%) by serological assay. 78 cases were positive for virus isolation and/or serological assay (33.1%). Virus infection included 33 cases of poliovirus (including 6 polio-I, 18 polio-II, 4 polio-III, 5 mixed infections), 21 cases of Coxsackie virus (including 6 CoxA24,7 CoxB1,2 CoxB4 and 6 CoxB5), 11 cases of ECHO virus (including 5 ECHO-7,2 ECHO-24 and each one of ECHO-11, 12, 15, 27), 10 cases of Enterovirus (including 3 EV-70, 7 EV-71), and 3 cases of mixed viral infection.

Adolescent↗
PubMed1997

[Production of anti-enteric adenovirus monoclonal antibody by electrofusion and semi-solid medium culture].

Ten million splenocytes from the enteric adenovirus (Ad40/41) immunized mice were fused with 3 x 10(6) myeloma cells by electrofusion. Then, the cells were selectively cultured in methyl cellulose semi-solid medium. Eighteen clones of hybridoma were directely picked out from the culture plates and 7 of them could secret high level specific antibodies to enteric adenovirus. So far, the anti-Ad40/41 virus monoclonal antibodies were successfully generated by the protocal of electrofusion accompanied with selective culture in methyl cellulose semi-solid medium.

Adenoviridae↗
PubMed1997

[Detection of bcr gene rearrangement in chronic myeloid leukemia by fluorescence in situ hybridization].

OBJECTIVE: To detect bcr gene rearrangement in chronic myeloid leukemia (CML). METHODS: Bcr rearrangement was detected by fluorescence in situ hybridization (FISH), using 765E3, a yeast artificial chromosome (YAC)-derived probe flanking the breakpoint within bcr gene. RESULTS: Nine patients with CML were examined, bcr gene rearrangement was revealed in 5 cases in chronic phase, 2 in blastic phase, and one after interferon-alpha therapy. The karyotype of 1 case after autologous bone marrow transplantation (ABMT) was chimera with normal and bcr gene rearrangement chromosomes. CONCLUSION: YAC765E3 is a useful probe for detecting bcr gene rearrangement. FISH technique is likely an important tool for monitoring of treatment and revealing minimal residual disease in CML.

Chromosomes, Artificial, Yeast↗
PubMed1997

[Study of dominant negative effect of the PLZF-RARalpha against the wild-type RARalpha in acute promyelocytic leukemia].

OBJECTIVE: To explore the role of promyelocytic leukemia zinc finger (PLZF) gene on 11q23 and RARalpha gene on 17q21. METHODS: Eight PLZF/RARalpha expression plasmids with deletions of different PLZF motifs were constructed by using PCR based-method. RESULTS AND CONCLUSION: By transient co-transfection, it was confirmed that PLZF/RARalpha had a dominant negative effect against the wild-type RARalpha, the POZ domain of PLZF/RARalpha was responsible for the dominant negative effect and the PLZF/RARalpha may play certain role through a spatial interaction with POZ.

Animals↗
PubMed1997

[Preliminary study on the arsenic trioxide-induced NB4 cell apoptosis and its molecular mechanisms].

OBJECTIVE: To illustrate the possible cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: APL cell line NB4 was used for in vitro studies. The effect of As2O3 on APL was studied by using flow cytometry, DNA electrophoresis, Narthern blotting and Western blotting. RESULTS: As2O3 induced NB4 cell apoptosis, while not inhibiting the growth and survival of two other leukemic cell lines (HL-60 and U937). Furthermore, As2O3 effectively down-regulated the expression of bcl-2 gene without changing the mRNA levels of other apoptosis-associated genes (including p53, c-myc, bax and bcl-XL). CONCLUSION: These might be one of the molecular mechanisms of As2O3 induced NB4 cell apoptosis.

Animals↗
PubMed1997

[Effects of arsenic trioxide on the subcellular localization of PML/PML-RARalpha protein in leukemic cells].

OBJECTIVE: In order to illustrate the possible roles of PML-RARalpha protein in arsenic trioxide (AsO3)-induced NB4 cell apoptosis. METHODS: Effects of As2O3 on the subcellular localization of PML-RARalpha in NB4 cells were studied. RESULTS: (1) Anti-PML serum staining was reduced and PML granules emerged in the perinuclear cytoplasm in a diffuse pattern in HL-60 cells under As2O3 treatment; (2) abnormal PML/PML-RARalpha granules were decreased; (3) NB4 cells accumulated anti-PML serum staining granules in the cytoplasms were increased and similar accumulation also found in apoptotic cells; and (4) pretreatment with all-trans retinoic acid (ATRA) for 24 or 48 hours did not alter the As2O3 effects. CONCLUSION: As2O3-induced apoptosis was independent of the retinoic acid signal pathway, and it might be regulated by PML/PML-RARalpha and/or other related genes.

Antineoplastic Agents↗
PubMed1997

[Pharmacokinetics of intravenous arsenic trioxide in the treatment of acute promyelocytic leukemia].

OBJECTIVE: In order to study the pharmacokinetics and metabolism of arsenic trioxide (As22O3), and its major side effects. METHODS: The clinical pharmacokinetics of intravenous As2O3 in 8 relapsed acute promyelocytic leukemia (APL) patients were studied by Gas-phase chromotography. RESULTS: (1) After 2 hour intravenous drips of 10mg As2O3, drug plasma maximal concentration (Cpmax) was 0.94 +/- 0.37mg/L(x +/- s), time to peak concentration (Tp) was 4hrs, T1/2 alpha and T1/2beta were 0.89 +/- 0.29hrs and 12.13 +/- 3.31hrs, respectively, apparent volume of distribution (Vc) was 3.83 +/- 0.45L, system clearance (CLs) was 1.43 +/- 0.17L/h and area under curve (AUC) was 7.25 +/- 0.97mg x h/L. Importantly, the continuous administration of As2O3 did not alter the pharmacokinetic behaviors. (2) During As2O3 therapy, 24-hour arsenic content in urine accounted for 1%-8% of the total dose (10mg) per day. And it decreased gradually after drug withdrawal. (3) Arsenic contents in nail and hair were increased continuously during As2O3 therapy. The peak concentrations could be five to seven-fold higher than that pre-treatment. It also decreased gradually after drug with drawal. CONCLUSION: As2O3 is a relatively safe and effective drug in the treatment of APL patients, in spite of certain accumulation in some tissues.

Adolescent↗
PubMed1997

[Comparative study of two fusion retinoic acid receptor alpha in acute promyelocytic leukemia].

OBJECTIVE: To make a comparison of biological properties between PML-RARalpha and PLZF-RARalpha fusion proteins. METHODS: Receptor radioligand binding assay, receptor DNA binding assay and immunofluorescence methods were used. RESULTS AND CONCLUSION: PML-RARalpha and PLZF-RARalpha had similar ligand-binding affinities. Both could bind in vitro to retinoic acid response elements (RAREs) forming homodimers and to retinoic acid X receptor. However ,they differed in the relative binding affinities to different RAREs,the behavior of forming complex with RXR and the subcellular localization. More importantly, PML-RARalpha and PLZF-RARalpha could block different regulatory pathways mediated by PML or PLZF, through heterocomplex formation with wild-type PML or PLZF. The differences between PML-RARalpha and PLZF-RARalpha may in part explain the apparent resistance of APL with t(11;17) to differentiating effect of all-trans retinoic acid (ATRA).

DNA↗
PubMed1997

[In vitro study on arsenic trioxide-inducing apoptosis in primary acute promyelocytic leukemie cells].

OBJECTIVE: To illustrate mechanisms of arsenic trioxide(As2O3) in the treatment of acute promyelocytic leukemia (APL). METHODS: Cell-DNA content distribution, CD11b and CD33 antigens and nitroblue tetrazolium (NBT) reduction were evaluated in fresh APL cells from six APL patients treated in vitro with As2O3. RESULTS: As2O3 had double effects on the cells inducing apoptosis and inducing partial differentiation at higher and at lower drug concentrations, respectively. As2O3 (0.1 approximately 2.0 micromol/L) could rapidly modulate and degrade APL-specific marker molecule PML-RARalpha protein, which could play an important role in the effects of As2O3 on APL cells. CONCLUSION: As2O3 had double effects (induction of apoptosis and partial differentiation) on APL cells through the modulation and degradation of PML-RARalpha proteins.

Apoptosis↗