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Biomedical subjects

Yi Zhang

Publications and source records attributed to Yi Zhang.

At least 289 records · Page 16Linked to original sources
PubMed2005

[Surgical management of naso-orbital-ethmoid fractures].

OBJECTIVE: To explore the clinical characteristics of naso-orbital-ethmoid (NOE) fracture, principles and surgical methods. METHODS: Twenty-nine patients with NOE fractures were investigated. Operations for the treatment of NOE and subsequent deformities included reduction of central fragment, reconstruction of orbit walls, reattachment of medial canthal ligament and so on. The outcome of the treatment was evaluated. RESULTS: Three cases were infected postoperatively. Of the 14 cases performed on reconstruction of orbit wall, 9 cases got complete correction for their dystopia/enophthalmos, 5 cases improved. Thirteen cases experiencing canthopexy obtained accepted outcome. CONCLUSIONS: The satisfactory correction of NOE fracture and subsequent enophthalmos/dystopia and telecanthus can be achieved with elective surgery in most cases.

Adolescent↗
PubMed2005

[Tissue expansion under the cicatrix].

OBJECTIVE: To investigate a more simple and effective method to repair cicatrix by tissue expansion. METHODS: The dilator with the capacity of 80 - 500 ml was implanted into the subcutaneous pocket under the cicatrix. After dilating for one to two months, the dilator was taken out and the wound surface of the cicatrix was removed. The expanded skin flap was advanced or rotated to cover the defects. The procedure was used on 203 cases. RESULTS: The dilatation was achieved successfully in all the cases, followed by cicatrix removing and repair. The incision scar was not noticeable. CONCLUSIONS: Tissue expansion under the cicatrix has the advantages of safety, less trauma and less extra incisions. It is a reasonable choice to obtain more flexible surgical designs and more economical skin flap applications. It is suitable for most of the treatment for cicatrix.

Adolescent↗
PubMed2005

[Predictive value of P53 expression in selecting first-line chemotherapy regimen for advanced epithelial ovarian carcinoma].

BACKGROUND & OBJECTIVE: The first-line adjuvant chemotherapy regimens of ovarian cancer mainly include TC (paclitaxel combined with carboplatin) and PC (cisplatin combined with cyclophosphamide) protocols. This study was to investigate the correlation of P53 expression to treatment outcome of ovarian cancer patients received the above 2 protocols, and explore the predictive value of P53 expression in selecting chemotherapy regimen. METHODS: Records of 53 patients with advanced epithelial ovarian cancer (stage IIIc), treated with TC or PC regimen, were analyzed retrospectively. The expression of P53 was detected by immunohistochemistry. The complete response (CR) rate and progression-free survival (PFS) were compared between TC and PC groups according to P53 status. RESULTS: Of the 53 patients, 22 were P53 positive, of which 13 received TC regimen and 9 received PC regimen; the CR rate was slightly higher in TC group than in PC group (76.9% vs. 33.3%, P=0.054), and PFS was significantly longer in TC group than in PC group (102 weeks vs. 43 weeks, P=0.040). In the subgroup of P53-negative patients, TC group had similar CR rate and PFS to PC group. Multivariate analysis showed that the size of residue was an independent prognostic factor. CONCLUSIONS: P53 detection may play a role in selecting first-line chemotherapy for advanced epithelial ovarian cancer patients: TC regimen is preference for P53-positive patients, PC regimen may be a choice for P53-negative patients. These recommendations should be tested in further trails with large samples.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

[Cytotoxicity of IFN-gamma-activated dendritic cells to freshly isolated acute myeloid leukemia cells].

To investigate the tumoricidal activity of dendritic cell (DC) stimulated by interferon-gamma (IFN-gamma) against freshly isolated myeloid leukemia cells and its mechanism, the peripheral blood monocytes collected from healthy donors were cocultured with interleukin-4 and granulocyte-macrophage colony-stimulating factor in medium to induce DC for 7 days. After 12 hour culture in the absence or presence of IFN-gamma, the changes of costimulatory molecules were analyzed with flow cytometry. To assay the cytotoxicity of DC against freshly isolated acute myeloid cells, they were cocultured at various effector-to-target ratio for 18 hours, then the percentage of tumoricidal activity was measured with (51)Cr release assay. To explore the mechanism of DC-mediated cytotoxicity, the change of DC surface or intracellular protein expression of Fas ligand (Fas L), TNF-alpha and TNF related apoptosis-inducing ligand (TRAIL) were analyzed with flow cytometry. The results showed that IFN-gamma enhanced cytotoxicity of DC against AML cells was (33.8 +/- 1.6)% at E:T as 20:1, compared with unstimulated DC (P < 0.05); IFN-gamma up-regulated expression of costimulatory molecules of DC surface such as CD86 and CD83; after stimulation with IFN-gamma, expression of intracellular TRAIL of DC was significantly enhanced, but expression of TRAIL on cell surface of DC was low; while the significant changes of Fas L and TNF-alpha expression neither on cell surface or in cells were not observed before or after stimulation with IFN-gamma. It is concluded that DC stimulated by IFN-gamma exhibit tumoricidal activity against AML cells. The cytotoxicity is partially related to maturation of DC and TRAIL inducing apoptosis, but not associated with death domain-independent mechanism of Fas L and TNF-alpha.

Acute Disease↗
PubMed2005

[Differentiation of bone marrow mesenchymal stem cells into hepatocytes in hepatectomized mouse].

CD44+ CD29+ and CD44- CD29+ bone marrow mesenchymal stem cells (BMSCs) were isolated from bone marrow of BALB/C male donor mouse by adherence selecting in DMEM media with low glucose and 20% fetal bovine serum. Then P5 cells were injected into the liver remnants of hepatectomined female mouse. Simultaneous assays were performed on the injected liver lobe and other liver lobe for detecting the Y-chromosome by fluorescence in situ hybridization and for defecting the albumin or cytokeratin 18 (CK18) by fluorescence immunoassays. Both Y chromosome and albumin (or CK18) positive cell could be detected at 5 days and 14 days after transplantation. At 14 days after transplantation, the liver weight in transplanted mouse was higher than that in model mouse. These results suggest that BMSCs could be induced to differentiate into hepatocytes and participate in the regeneration of liver.

Animals↗
PubMed2005

[Study on effects of salidroside on lipid peroxidation on oxidative stress in rat hepatic stellate cells].

OBJECTIVE: To investigate the effect of antioxidant Salidroside on the lipid peroxidation of oxidative stress in rat hepatic stellate cells in vitro. METHODS: HSC-T6 were incubated with 0.1 mM ferric nitrilotriacetate complex (FeNTA). MTT colorimetry was used for assaying proliferation of HSC. Cytotoxicity was measured by LDH colorimetry. Collagen type I accummulation in the culture media was measured by ELISA. Intracellular MDA, SOD, GSH and GSH-PX levels in the culture media were measured by their reagent boxes. RESULTS: HSC incubation with FeNTA resulted in a significant production of intracellular MDA and GSH, associated with decreasing SOD and GSH-PX activity. Exposure of HSC to FeNTA significantly enhanced the number of proliferating HSC and collagen type I levels in the culture medium. All these effects were reversed by the antioxidant Salidroside. CONCLUSION: The mechanism of Salidroside on fibrosis may be related to inhibit lipid peroxidation.

Animals↗
PubMed2005

[Studies on the process of Herba Clinopodii saponins purified with macroporous adsorption resin].

OBJECTIVE: To study the technological parameters of the purification process of saponins with macroporous adsorption resin. METHODS: The adsorptive characteristics and elutive parameters of the process were studied by taking the elutive and purified ratio of saponins as markers. RESULTS: 11.4 ml of the extraction of Herba Clinopodii (crude drugs 0.2 g/ml) was purified with a column of macroporous adsorption resin (phi15 mm x H90 mm, dry weight 2.5 g) and washed with 3BV of distilled water, then eluted with 3BV of 30% ethanol and 3BV of 70% ethanol. Most of saponins were collected in the 70% ethanol. CONCLUSION: With macroporous adsorption resin adsorbing and purifying,the elutive ratio of saponins is 86.8% and the purity reaches 153.2%. So this process of applying macroporous adsorption resin to adsorb and purify Saponins is feasible.

Adsorption↗
PubMed2005

[Research progresses in endovascular stent biomaterials].

This essay is to make brief comments on the physical characteristics, biocompatibility, corrosion resistance, clinical information, existent problems of endovascular stent biomaterials and the developing tendency in future.

Angioplasty↗
PubMed2005

[Clinical observation of young, middle-aged and elderly women with endometrial carcinoma].

OBJECTIVE: To explore the clinical features, diagnosis, treatment and prognosis of endometrial carcinoma in young, middle-aged and elderly women. METHODS: We retrospectively analyzed the clinical data of 82 cases of endometrial carcinoma in young, middle-aged women and 33 cases of endometrial cacinoma in elderly women. RESULTS: The rates of adenocarcinoma in young, middle-aged and elderly groups were 74.4% and 75.5%, respectively. The young,middle-aged and elderly patients with Stage I endometrial cancer were 64.6% and 69.7%, and those with Stage III and IV were 15.9% and 15.2%, respectively. The histological Grade 1 carcinoma of endometrium in young,middle-aged and elderly women were 70.7% and 60.6%, respectively. The young, middle-aged women without myometrial invasion were more than the elderly women (42.8% vs 15.6%, P < 0.01). The young, middle-aged women with myometrial invasion more than half of myometrial wall were less than the elderly women (10.4% vs 40.6%, P < 0.01). The rate of chemical treatment after the surgery in the elderly women was more than that of the young, middle-aged women (P < 0.05). The 5-year survival rate of the young, middle-aged women was obviously higher than that of the elderly women (92.79% vs 72.21%, P < 0.05). CONCLUSION: Adenocarcinoma and well-differentiated cells are the main pathological characteristics of endometrial carcinoma both in the young, middle-aged and the elderly women. Most young, middle-aged and el-derly patients can be diagnosed and treated in the early stage. Early diagnosis and reasonable treatment can improve the prognosis. The prognosis of the young, middle-aged patients is obviously better than that of the elderly patients, and the myometrial invasion depth may be the main difference.

Adenocarcinoma↗
PubMed2005

[Western Blot analysis of type I, III, V, VI collagen after laser epithelial keratomileusis and photorefractive keratectomy in cornea of rabbits].

PURPOSE: Use immunohistochemical staining and Western Blot analysis to observe and compare the accurate dynamic changes of type I, III, V, VI collagen in the wound healing processes of the rabbit cornea which underwent LASEK or PRK to investigate the possible mechanism of corneal haze and myopic regression. METHODS: New Zealand White rabbits were divided into 8 groups: normal control group (n=6), 1 day, 7 days, 1, 3, 4, 5 and 6 month groups (n=14). Every rabbit underwent LASEK in one eye while the other one with PRK. We use immunohistochemical staining and Western Blot analysis to compare the wound healing process of dynamic change of the type I, III, V and VI collagen in rabbit cornea of every time point. The results were analysised with data analysis software. RESULT: Immunohistochemical staining and Western Blot analysis showed that after LASEK, the cornea wound healing with type I and III collagen were much faster than PRK, and the wound response was also much weaker. Whereas for type V and VI collagen, their dynamic changes were resemble between LASEK and PRK, they both reached the peak value after 3 months since the surgery, but LASEK group returned to normal earlier than PRK. The value of these two types of collagen after PRK were higher than LASEK. The changes of these four types of collagen may offer us at least partial explaination to the difference between formation between corneal haze and refractive regression. CONCLUSIONS: There were significant differences between LASEK and PRK on type I, III, V and VI collagens or the time of reacting, reaching apex and returning to normal . LASEK had slighter intensity of reaction. The results indicate that there is excessive aggradation of collagens after PRK, it may be the histological foundation of obvious haze and myopia regression.

Animals↗
PubMed2004

Fast formation of the P3-P7 pseudoknot: a strategy for efficient folding of the catalytically active ribozyme.

Formation of the P3-P7 pseudoknot structure, the core of group I ribozymes, requires long-range base pairing. Study of the Tetrahymena ribozyme appreciates the hierarchical folding of the large, multidomain RNA, in which the P3-P7 core folds significantly slower than do the other domains. Here we explored the formation of the P3-P7 pseudoknot of the Candida ribozyme that has been reported to concertedly fold to the catalytically active structure with a rate constant of 2 min(-1). We demonstrate that pseudoknot formation occurs during the rapid ribozyme compaction, coincident with formation of many tertiary interactions of the ribozyme. A low physiological concentration of magnesium (1.5 mM) is sufficient to fully support the pseudoknot formation. The presence of nonnative intermediates containing an unfolded P3-P7 region is evident. However, catalysis-based analysis shows these nonnative intermediates are stable and fail to convert to the catalytically active structure, suggesting that rapid pseudoknot formation is essential for folding of the active ribozyme. Interestingly, RNAstructure predicts no stable Alt P3 structure for the Candida ribozyme, but two stable Alt P3s for the Tetrahymena ribozyme, explaining the dramatic difference in folding of the P3-P7 core of these two ribozymes. We propose that rapid formation of the P3-P7 pseudoknot represents a folding strategy ensuring efficient production of the catalytically active structure of group I ribozymes, which sheds new light on the mechanism of effective ribozyme folding in vivo.

Animals↗
PubMed2004

Superhard cubic BC2N compared to diamond.

Recent experiments claimed successful synthesis of cubic boron-carbonitride compounds BC2N with an extreme hardness second only to diamond. In the present Letter, we examine the ideal strength of cubic BC2N using first-principles calculations. Our results reveal that, despite the large elastic parameters, compositional anisotropy and strain dependent bonding character impose limitation on their strength. Consequently, the hardness of the optimal BC2N structure is predicted to be lower than that of cubic BN, the second hardest material known. The measured extreme hardness of BC2N nanocomposites is most likely due to the nanocrystalline size effect and the bonding to the surrounding amorphous carbon matrix. This may prove to be a general rule useful in the quest for new superhard covalent materials.

Journal Article↗
PubMed2004

Effects of novel anxiolytic 4-butyl-alpha-agarofuran on levels of monoamine neurotransmitters in rats.

4-butyl-alpha-agarofuran (AF-5) is a new compound derived from alpha-agarofuran, a constituent extracted from Aquillaria agallocha Roxb. Our previous research has shown that AF-5 has significant antianxiety activity in several animal models. In this study, an antianxiety effect was observed in a social interaction test after acute treatment with AF-5 (0.5-4.0 mg/kg, i.p.) in rats. Using high-performance liquid chromatography (HPLC)-electrochemical detection (ECD), we further investigated the effects of AF-5 on monoamine neurotransmitters both in rat brain tissues and in striatum dialysates. After acute administration of AF-5 (5.0 mg/kg, i.p.), serotonin (5-hydroxytryptamine, 5-HT) tissue levels significantly decreased by 26.3%, 30.4%, and 17.4% of the vehicle-control levels, in the striatum, cortex, and midbrain, respectively. The dopamine level decreased by 34.7% in the striatum and 19.0% in the midbrain, while in the hypothalamus, it increased to 156.6%. The epinephrine level decreased by 34.6% in the cortex. In cerebral microdialysis perfusates from rat striatum, the extracellular dopamine level declined stepwise after treatment with AF-5 (10.0 mg/kg, i.p.). By 200 min postinjection, the dopamine level reached a minimum, about 40% of the baseline value. At the same time, the extracellular levels of 5-hydroxyindolacetic acid, 3-4-dihydroxyphenylacetic acid, and homovanillic acid increased significantly, the maximum values were 150%, 145%, and 175% above baseline, respectively. This study suggests that AF-5 is a potent anxiolytic agent, and that its beneficial action may be related to its effects on central monoamine neurotransmitters.

Animals↗
PubMed2004

Imprinting along the Kcnq1 domain on mouse chromosome 7 involves repressive histone methylation and recruitment of Polycomb group complexes.

Imprinted genes are clustered in domains, and their allelic repression is mediated by imprinting control regions. These imprinting control regions are marked by DNA methylation, which is essential to maintain imprinting in the embryo. To explore how imprinting is regulated in placenta, we studied the Kcnq1 domain on mouse distal chromosome 7. This large domain is controlled by an intronic imprinting control region and comprises multiple genes that are imprinted in placenta, without the involvement of promoter DNA methylation. We found that the paternal repression along the domain involves acquisition of trimethylation at Lys27 and dimethylation at Lys9 of histone H3. Eed-Ezh2 Polycomb complexes are recruited to the paternal chromosome and potentially regulate its repressive histone methylation. Studies on embryonic stem cells and early embryos support our proposal that chromatin repression is established early in development and is maintained in the placenta. In the embryo, however, imprinting is stably maintained only at genes that have promoter DNA methylation. These data underscore the importance of histone methylation in placental imprinting and identify mechanistic similarities with X-chromosome inactivation in extraembryonic tissues, suggesting that the two epigenetic mechanisms are evolutionarily linked.

Animals↗
PubMed2004

Ring1b-mediated H2A ubiquitination associates with inactive X chromosomes and is involved in initiation of X inactivation.

Histone modifications are thought to serve as epigenetic markers that mediate dynamic changes in chromatin structure and regulation of gene expression. As a model system for understanding epigenetic silencing, X chromosome inactivation has been previously linked to a number of histone modifications including methylation and hypoacetylation. In this study, we provide evidence that supports H2A ubiquitination as a novel epigenetic marker for the inactive X chromosome (Xi) and links H2A ubiquitination to initiation of X inactivation. We found that the H2A-K119 ubiquitin E3 ligase Ring1b, a Polycomb group protein, is enriched on Xi in female trophoblast stem (TS) cells as well as differentiating embryonic stem (ES) cells. Consistent with Ring1b mediating H2A ubiquitination, ubiquitinated H2A (ubH2A) is also enriched on the Xi of both TS and ES cells. We demonstrate that the enrichment of Ring1b and ubH2A on Xi is transient during TS and ES cell differentiation, suggesting that the Ring1b and ubH2A are involved in the initiation of both imprinted and random X inactivation. Furthermore, we showed that the association of Ring1b and ubH2A with Xi is mitotically stable in non-differentiated TS cells.

Animals↗