Biomedical subjects

Yu Cao

Publications and source records attributed to Yu Cao.

36 records · Page 2Linked to original sources

PubMed2005

[Landscape health assessment on Ejin natural oasis].

Landscape scale ecosystem health research could not only provide a basis for integrating natural ecological processes and social economic values, but also provide an appreciated temporal and spatial scale in dealing with the issues of resources and environment. The Ejin natural oasis landscape is at the lower reach of Heihe river basin in the arid inland regions of northwestern China. Owing to the lack of sufficient water resource from the upper reaches of Heihe River, a series of ecological and environmental problems are getting more serious in the oasis in recent years. Based on the past decade landscape change of the Ejin natural oasis, this paper developed a landscape health indicators system including landscape change indicators, bio-physical indicators, eco-environmental indicators and social-economic indicators, and established the criteria and weightiness for assessment indicators. The landscape health index (LHI) was finally figured out as 0. 3042 by using fuzzy comprehensive evaluation method, which showed that the health condition of Ejin natural oasis landscape was ranked to "severely ill level" in the landscape health assessment criteria system. The landscape health of Ejin natural oasis landscape today is much worse than in the past years, with a badly unsustainable developing trend.

China↗

PubMed2004

[The correlation between preoperative pulmonary function and postoperative pulmonary complications in the surgical treatment of scoliosis].

OBJECTIVES: To evaluate the incidence of immediate postoperative pulmonary complications and their correlation to preoperative pulmonary function tests (PFTs), preoperative pulmonary symptoms and surgical approaches. METHODS: The case records of 298 patients, who underwent anterior or posterior fusion, were reviewed. Preoperative PFTs were recorded and abnormal PFTs were defined as forced vital capacity (FVC) is less than 80% of FVC predicted. Preoperative pulmonary symptoms (breathless on exertion) were noted, and postoperative pulmonary complications were defined when the presence of atelectasis, infiltrates, pneumothorax, hemothorax, pneumonia or requirement of postoperative ventilatory support was noted. RESULTS: The mean age of this group was 16.4 years (range from 6-62 years). The average coronal Cobb angle was 73.26 degrees (range from 45 degrees-141 degrees ). Of all the patients, 115 patients had normal preoperative PFTs, the other 183 cases had abnormal PFTs. Nineteen cases of all the patients were found with postoperative pulmonary complications including postoperative ventilatory support in 6 cases, atelectasis in 4 cases, infiltration in 2 cases, pneumothorax in 3 cases, pneumonia in 3 cases and hypoxemia in 1 case. The incidence of postoperative pulmonary complication was 6.4% in all the patients, while 18.99% in the 79 patients with thoracotomy and 1.85% in the 216 patients without. The correlation between postoperative pulmonary complications and the surgical approach was statistically significant (P=0.0000). When the patients were classified into 3 groups: 60%< FVCR <80%, 40%< FVCR <60%, FVCR <40%, the incidence of postoperative pulmonary complications were 2.72% (3/110), 7.40% (4/54) and 31.6% (6/19) respectively, which showed an increasing complication incidence. In the 115 patients with normal PFTs, 3 patients had preoperative pulmonary symptoms (2.68%), while 14 of the 183 patients with abnormal PFTs had preoperative pulmonary symptoms (7.65%). The correlation between presence of preoperative respiratory symptoms and abnormal results on PFTs was statistically significant (P=0.01). No significant correlation was found between preoperative respiratory symptoms and postoperative pulmonary complications (P=0.52). CONCLUSIONS: The incidence of postoperative pulmonary complications increases with the deterioration of PFTs. The posterior procedure has a very low incidence of postoperative pulmonary possibility of complications, but a transthoracic procedure increases the complications significantly. Preoperative respiratory symptoms usually predict abnormal results of PFTs but have no correlation with postoperative pulmonary complication.

Adolescent↗

PubMed2004

Spontaneous formation of periodic nanostructured film by electrodeposition: Experimental observations and modeling.

In this paper we report the spontaneous formation of a nanostructured film by electrodeposition from an ultrathin electrolyte layer of CuSO4. The film consists of straight periodic ditches and ridges, which corresponds to the alternating deposition of nanocrystallites of copper and copper plus cuprous oxide, respectively. The periodicity on the film may vary from 100 nm to a few hundred nanometers depending on the experimental conditions. In the formation of the periodically nanostructured film, oscillating voltage/current has been observed across the electrodes, and the frequency depends on the pH of the electrolyte and the applied current/voltage. A model based on the coupling of [Cu2+] and [H+] in the electrodeposition is proposed to describe the oscillatory phenomena in our system. The calculated results are in agreement with the experimental observations.

Journal Article↗

PubMed2004

[Chemopreventive effect of resveratrol to cancer].

BACKGROUND & OBJECTIVE: Carcinogenesis is a complex process and at least 3 stages, including initiation, promotion, and progression, have been proposed in the process of carcinogenesis. Resveratrol has attracted considerable attention due to its low toxicity and unique chemical structure. This study was designed to test chemopreventive effect of resveratrol to cancer using various animal models. METHODS: Ames assay and micronucleus formation assay were used to test the antimutagenic activities of resveratrol. Croton oil-induced enhancement of ornithine decarboxylase (ODC) activities of dorsal epidermis cells in mouse and mouse ear edema model were used to investigate the anti-promotion effect of resveratrol. In addition,7,12-dimenthylbenz[a]anthracene (DMBA)/croton oil-induced mouse skin tumor model was used to evaluate chemopreventive effect of resveratrol to cancer in vivo. RESULTS: In Ames test,100 microg/plate of resveratrol exhibited 42.2% of inhibition on the reversion of Salmonella typhimurium TA100 induced by methylmethansulfonate, and 200 microg/plate of resveratrol exhibited 91.8% of inhibition on the reversion induced by benzopyrene. Pretreatment of resveratrol prevented cyclophosphamide (CTX)-induced micronucleus formation of polychromatic erythrocytes of mice bone marrow in dose-dependent manner. Mice treated with 30 mg/kg of resveratrol for 6 days before croton oil exposure have palliative ear edema. Treatment of 180 mg/kg resveratrol for 3 days caused 69.3% decrease of ODC activities in croton oil-induced dorsal epidermis. It was shown that resveratrol could inhibit DMBA/croton oil-induced mouse skin papilloma, which includes prolonging the latent period of tumor occurrence, decreasing the incidence of papilloma, and reducing tumor number per mouse in dose-dependent manner. CONCLUSION: Resveratrol has the ability of anti-mutation and anti-promotion of cancer and merit further studies as a potential cancer chemopreventive agent.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2003

Synaptojanin is recruited by endophilin to promote synaptic vesicle uncoating.

We describe the isolation and characterization of Drosophila synaptojanin (synj) mutants. synj encodes a phosphatidylinositol phosphatase involved in clathrin-mediated endocytosis. We show that Synj is specifically localized to presynaptic terminals and is associated with synaptic vesicles. The electrophysiological and ultrastructural defects observed in synj mutants are strikingly similar to those found in endophilin mutants, and Synj and Endo colocalize and interact biochemically. Moreover, synj; endo double mutant synaptic terminals exhibit properties that are very similar to terminals of each single mutant, and overexpression of Endophilin can partially rescue the functional defects in partial loss-of-function synj mutants. Interestingly, Synj is mislocalized and destabilized at synapses devoid of Endophilin, suggesting that Endophilin recruits and stabilizes Synj on newly formed vesicles to promote vesicle uncoating. Our data also provide further evidence that kiss-and-run is able to maintain neurotransmitter release when synapses are not extensively challenged.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Mapping Drosophila mutations with molecularly defined P element insertions.

The isolation of chemically induced mutations in forward genetic screens is one of the hallmarks of Drosophila genetics. However, mapping the corresponding loci and identifying the molecular lesions associated with these mutations are often difficult and labor-intensive. Two mapping methods are most often used in flies: meiotic recombination mapping with marked chromosomes and deficiency mapping. The availability of the fly genome sequence allows the establishment and usage of molecular markers. Single-nucleotide polymorphisms have therefore recently been used to map several genes. Here we show that thousands of molecularly mapped P element insertions in fly strains that are publicly available provide a powerful alternative method to single-nucleotide polymorphism mapping. We present a strategy that allows mapping of lethal mutations, as well as viable mutations with visible phenotypes, with minimal resources. The most important unknown in using recombination rates to map at high resolution is how accurately recombination data correlate with molecular maps in small intervals. We therefore surveyed distortions of recombination rates in intervals <500 kb. We document the extent of distortions between the recombination and molecular maps and describe the required steps to map with an accuracy of <50 kb. Finally, we describe a recently developed method to determine molecular lesions in 50-kb intervals by using a heteroduplex DNA mutation detection system. Our data show that this mapping approach is inexpensive, efficient, and precise, and that it significantly broadens the application of P elements in Drosophila.

Animals↗

PubMed2003

Anti-invasion and anti-angiogenesis effect of taxol and camptothecin on melanoma cells.

Two highly invasive melanoma cell lines B16BL6 and B16F10 were used to investigate the anti-invasion and antiangiogenesis action of taxol and camptothecin (CPT). The adhesion of melanoma cells was tested by optical absorbance at 545 nm. The invasive activity of these cells was tested in a transwell chamber assay. The cell migration within a 3D collagen matrix was recorded with a time-lapse video recorder and analyzed by computer-assisted cell tracking. Gelatin zymography was used to study the metalloproteinase activity. The chicken chorioallantoic membrane (CAM) model was used to study the anti-angiogenesis effect of the two drugs. The results demonstrated that both taxol and CPT could inhibit the migration of B16F10 cells, and inhibit the adhesion of B16F10 to fibronectin and laminin. They can reduce the metalloproteinase secretion of HT1080 and exhibit the antiangiogenesis effect in the CAM model. Taxol showed a highly anti-invasion effect on B16BL6 cells while CPT did not exhibit such an effect.

Animals↗

PubMed2003

Taxol inhibits melanoma metastases through apoptosis induction, angiogenesis inhibition, and restoration of E-cadherin and nm23 expression.

An in vivo melanoma spontaneous metastases model was adopted to study the molecular mechanisms of the anti-metastatic effect of Taxol. The morphology of melanoma cells in the melanoma tissue lesions was examined by hematoxylin/eosin (H&E) staining and electron microscopy. The in situ programmed cell death was tested by TUNEL analysis. Vascular endothelial growth factor (VEGF) and E-cadherin expression were detected by immunohistochemistry. The metastases suppressor gene nm23 mRNA expression level was analyzed by in situ hybridization. The results showed that i.p. injection of Taxol at 5 mg/kg per day for three weeks significantly inhibited metastases formation in the pulmonary of mice. Taxol induced melanogenesis and apoptosis in the melanoma cells, inhibited angiogenesis in melanoma tissue lesions, and reduced the expression of VEGF. Conversely, Taxol increased the expression of E-cadherin and nm23. In conclusion, administration of Taxol in the early stage of melanoma metastases can significantly inhibit melanoma metastases. This effect was possibly related to apoptosis induction, tumor angiogenesis inhibition, and restoration of the metastasis suppression ability.

Angiogenesis Inhibitors↗

PubMed2003

[Landscape changes of Minqin oasis in Gansu Province and its driving force].

Based on the technology of GIS, RS and using FRAGSTATS, studies on the landscape changes of Minqin oasis during 1987 to 2001 showed that the transitions of landscape patches were complex, and open up wasteland took place during 1994 to 1998 in the south of the oasis where the condition of water was better and desertization took place during 1998 to 2001 in the north of the oasis where the condition of water was worse. The decreasing of the Shannon's diversity index and the Shannon's evenness index and the increasing of Contagion index showed that human beings reconstructing the landscape of the oasis began stronger than before. Unreasonable land use was changed the landscape pattern, and the condition of water resource accelerated the landscape change.

Agriculture↗

PubMed2003

[Experimental studies on the apoptosis of HL-60 cells induced by Brucea javanica oil emulsion].

OBJECTIVE: To investigate the inducing effect of Brucea javanica on the apoptpsis of HL-60 cells. METHOD: HL-60 cells were treated with Brucea javanica 1:100, 1:40, 1:20 (v/v) respectively for 6 h and DNA agarose gel electrophoresis, flow cytometry, fluorescence microscope, electron microscope were used to observe the apoptosis inducing effect of Brucea javanica. RESULT: DNA ladder was seen in the 1:40 group. The apoptosis cell percentages of 1:40 and 1:20 group were 86.8% and 97% respectively. Cells of 1:40 group showed obvious apoptosis character under fluorescence microscope. Cells were induced apoptosis in 1:20 and 1:40 Brucea javanica under electron microscope. CONCLUSION: 1:20 and 1:40 Brucea Javanica showed obvious apoptosis inducing effect of HL-60.

Antineoplastic Agents, Phytogenic↗

PubMed2003

[Study of the expression membrane protein LASS2].

A human membrane protein LASS2 (Homo sapiens longevity assurance homologue 2 of yeast LAG1), which has important physiologic functions, was expressed in three different expression systems. Only the LASS2 protein carboxyl terminal hydrophilic fragment could be expressed in the prokaryote expression system and its polyclonal antibody was produced. The full length of LASS2 protein could be expressed successfully in both eukaryotic in vitro translation system and Bacuvirus expression system: Bac-to-Bac system. SDS-PAGE analysis revealed that the molecular weight of expressed product of LASS2 was about 28 kD. The product was also proved by Western blot. This recombinant LASS2 protein was purified by metal affinity resin and the purity is above 90%.

Animals↗

PubMed2002

The properties of enzyme-hydrolyzed cellulose in aqueous sodium hydroxide.

Pure natural cellulose (softwood pulp) modified with cellulase is allowed to react with sodium hydroxide in a muller, and changes in structure and properties are investigated by FTIR and DSC. The reactivity of cellulose for some dissolving and derivatization processes is shown to be improved by an enzymatic hydrolysis and admixture with sodium hydroxide. The modified cellulose dissolved at 9% (wt) sodium hydroxide at -10 degrees C at 6% pulp consistency, while the DP of cellulose is >350.

Ascomycota↗

PubMed2002

Effects of cellulase on the modification of cellulose.

Multicomponent cellulases, purified endoglucanases and cellobiohydrolases were assayed and shown to modify pure natural cellulose (softwood pulp). Changes in structure and properties of the cellulose caused by enzymatic treatment depend on the composition, the type of enzyme, and the treatment conditions. The reactivity of cellulose for some dissolving and derivatization processes may be improved by enzymatic hydrolysis. Endoglucanases decreased the average degrees of polymerization (DP) and improved the alkaline solubility of cellulose most efficiently. The variation in the supramolecular structure estimated from the infrared spectra of the cellulose samples was found to be correlated with the reactivity and might represent wide variations in conformation caused by the breakdown of the hydrogen bonds.

Carboxymethylcellulose Sodium↗

PubMed2002

Localization and functional investigation of the transcription factor CREB in taste receptor cells.

Taste receptor cells utilize the cAMP and other second messenger systems in transducing sweet and bitter stimuli into physiological responses. However, long-term consequences of taste stimulation, such as gene expression, are unknown. We investigated the presence of cAMP response element-binding protein (CREB), a stimulus-induced transcription factor, in taste receptor cells. Using immunocytochemistry, both CREB and its activated form, phosphorylated-CREB (pCREB), were localized to a subset of rat taste receptor cells. Basal level of pCREB was high in the absence of any known stimulation. Using western blot analysis and specific protein kinase inhibitors, CREB phosphorylation was demonstrated to be linked to protein kinase A but not to protein kinase C activation. Stimulation of taste receptor cells with sucrose, a sweet stimulus that elevates cAMP levels, was without effect on CREB phosphorylation. There was a tendency for quinine stimulation, a bitter stimulus that lowers cAMP, to reduce CREB phosphorylation. These results suggested that taste receptor cells express CREB and that its phosphorylation is influenced by the cAMP second messenger system.

Animals↗

PubMed2002

[Anti-mutagenicity activity of dehydroepiandrosterone].

OBJECTIVE: The chemopreventive activity and mechanism of dehydroepiandrosterone (DHEA) were studied. METHODS: Model of 7, 12-dimethylbenz (alpha) anthracene (DMBA) induced breast carcinoma in Sprague-Dawley rats, uitra-violet (UV)-induced DNA damage and Salmonella mutation assay were used. RESULTS: In DMBA-induced rat mammary tumor model, the rats were orally given daily DHEA for 2 weeks before DMBA and continued for 10 weeks after DMBA administration. The results showed significant inhibition of tumor development by DHEA. The incidence of mammary carcinoma also decreased significantly on daily dose of oral 25 mg/kg DHEA with the mean tumor volume per rat also remarkably reduced by 92%. Moreover, 25 mg/kg DHEA treatment could significantly increase the carcinoma latency for about 3.5 weeks as compared with the control. Using polymerase chain reaction (PCR) assay, in vitro 10(-9) mol/L DHEA showed significant inhibitory effect on UV-induced DNA damage by 90%. In Ames test, DHEA was found to decrease DMBA and benzo (alpha) pyrene-induced TA98 and TA100 His(+) revertants markedly and the number of Salmonella clones were significantly reduced by 53.2% and 73.0% on dose of 5 microgram DHEA/plate. It was also shown that in vitro 10(-7) mol/L DHEA could also effectively inhibit the G-6-PDH activity, which might play an important role in its chemoprophylaxis activities. CONCLUSION: The results strongly prove that DHEA is a potent cancer chemoprophylaxis agent, which exhibits inhibitory potential on mutation and chemical carcinogen in vivo and in vitro.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2002

[Improvement of recombinant xylanase XynF1 from Aspergillus oryzae expressed in Pichia pastoris by site-directed mutagenesis].

The recombinant xylanase XynF1 from Aspergillus oryzae expressed in the methylotrophic yeast Pichia pastoris was improved by site-directed mutagenesis. The mutant I156A secreted about 47.7 U/mL xylanase XynF1 in the BMMY medium. The mutant xylanase XynF1 was purified by ion exchange and gel filtration chromatographies. The molecular weight of purified XynF1 was 35 kD. XynF1 was stable between pH 4-9 and its optimum pH was 7.0. The optimum temperature of XynF1 was 45 degrees C and it was stable below 50 degrees C. The properties of mutant were same as the parent's except the stability of temperature.

Aspergillus oryzae↗

PubMed2002

[A review on the concept, characteristic and assessment of landscape health].

As a new concept emerging from landscape ecology and ecosystem health, landscape health is the subject dealing with ecosystem health for landscapes which, under the disturbance of intense activities from human beings, are seriously polluted and degraded, even facing with the risk of disappearing. The basic concept, characteristics and criteria of landscape health were introduced in this paper, and indicators, scales and hierarchical structures and methods for landscape health assessment were also discussed. It was emphasized that comparative, integrative, and developmental methods should be applied in landscape health assessment.

Ecosystem↗

PubMed2002

[Oasis corridor landscape in arid regions: a case study of Jinta Oasis].

In arid region oasis, the main corridor landscape types include river, ditch, shelterbelt and road. This paper introduced their basic ecological effects on transporting mass and energy and on obstructing desert landscape expansion and incursion. Using Geographic Information System (GIS), the corridor distribution and its spatial relationship with other landscape types in the Jinta Oasis were analyzed. Based on the dynamically monitoring on the landscape pattern change of the Jinta Oasis during the latter 10 years, the driving functions of the corridors on this change were analyzed in detail. The results showed that all kinds of corridors' characteristics could be quantified by the indexes such as length and width, ratio of parameter and area, density, and non-heterogeneity. The total corridor length of Jinta Oasis is 1838.5 kilometers and its density is 2.1 km.km-2. The corridor density of the irrigated land, forest and resident area is maximal, showing that the affection degree of the oasis corridors on them is the most. The improvement of the corridor quality is one of the important driving factors on the irrigated land.

Agriculture↗