Biomedical subjects

Peng Wang

Publications and source records attributed to Peng Wang.

187 records · Page 11Linked to original sources

PubMed2002

[Effect of different environmental factors on the activities of digestive enzymes and alkaline phosphatase of Macrobrochium nipponense].

The activities of digestive enzymes and alkaline phosphatase from the hepatopancreas of Macrobrochium nipponense were determined under different environmental factors (calcium concentrations 20 mg.L-1, 35 mg.L-1, 60 mg.L-1, 80 mg.L-1, 150 mg.L-1; salinity 7@1000, 14@1000, pH 7.6, 8.8, 9.8). The results showed that higher Ca2+ concentration could enhance the pepsin activity, but inhibit the trysin-like activity in hepatopancreas of M. nipponense. The activities of pepsin, trysin-like, alkaline phosphatase in hepatopancreas of M. nipponense were higher under salinity of 14@1000 than under salinity of 7@1000 and 20@1000. It showed that the activities of digestive enzymes and alkaline phosphatase of shrimp increased gradually with increasing pH value from 7.6 to 9.8.

Acid Phosphatase↗

PubMed2002

[The influence of heat-induced epitope retrieval on endogenous avidin-binding activity (EABA) and blocking of EABA in immunohistochemistry].

OBJECTIVE: To study the influence of heat-induced epitope retrieval (HIER) on endogenous avidin-binding activity (EABA) and to establish an effective way to block EABA in immunohistochemistry. METHODS: Systematically screening EABA in 164 (679 samples) formalin-fixed and paraffin-embedded human tissues including 76 (102 samples) normal tissues and 88 (577 samples) tumor tissues as well as 4 (80 samples) formalin-fixed and paraffin-embedded rat normal tissues using tissue array (tissue chip), HIER, immunohistochemistry and egg white solution blocking. In addition, EABA was also examined in 9 (15 samples) human frozen tissues. RESULTS: (1) EABA was detected in frozen tissues. (2) No staining for EABA was seen in formalin-fixed and paraffin-embedded tissues. (3) EABA was revealed after the tissues treated with microwave HIER. (4) The density of signal for EABA was variable from tissue to tissue and cell to cell. (5) The signals of EABA expressed in scatter or diffuse in tissues and in granular form in cytoplasm. (6) EABA was found in a wide range of epithelial tissues, especially in gland epithelia of normal and tumor tissues. These included kidney, adrenal cortex, liver, C cells of thyroid gland, oxyphil cells of parathyroid, fundal gland of stomach, sebaceous gland of skin, duct of salivary; oncocytoma and papillary adenocarcinoma of kidney and thyroid gland, adenolymphoma of parotid, carcinoma of liver cell, adenocarcinoma of stomach, colon, prostate, gall bladder and endometrium, and so on. (7) EABA was easier revealed by higher pH value buffer (EGTA pH 9.0) than that with lower pH value (EDTA pH 8.0 and citrate pH 6.0). (8) The revealed EABA could be effectively blocked using 20% egg white solution. CONCLUSIONS: HIER could unmask EABA in formalin-fixed and paraffin-embedded tissues. The unmasked EABA present in a wide range of human normal and tumor tissues as well as in rat normal tissues. The EABA could influence routine immunohistochemistry staining when using (strept)avidin-horseradish peroxidase detective system. The egg white solution could effectively block EABA and eliminate the influence of EABA on immunohistochemistry.

Animals↗

PubMed2002

[Study on making pneumoconiosis model and method of lung lavage in rabbit].

OBJECTIVE: To provide an intact rabbit pneumoconiosis model and a method of lung lavage for studying the pathogenesis and treatment of pneumoconiosis. METHODS: The dust particles(< or = 5 microns diameter) were poured into the trachea of rabbit by trachea spile. The lung lavage of rabbit was carried out by the improved trachea catheter method. RESULTS: The rabbit lungs exposed to coal dust showed many black dust spots and there were proliferation of fibroblasts. The rabbit lungs exposed to silica dust showed nodules and several fusing nodules. The X-ray film showed that there were small irregular shadows, or fusing together into flake-like or round shadows in both lungs. The recovery rate of the lung lavage was 89%-94%. CONCLUSION: The model made by trachea spile and the method of lung lavage by the improved trachea catheter were simple, safe and without being injured.

Animals↗

PubMed2002

[Expression and characterization of carboxylesterase A2 in E. coli].

The most commonly observed change that has been linked to resistance development is the increase in activity of carboxylesterases. The putative mechanism involves an overproduction of this enzyme for the sequestration and the hydroxylation of various organophosphate and carbamate insecticides. Carboxylesterases A2 cDNA was amplified from Culex quinquefasciatus by RT-PCR and sequenced consequently. Target gene was inserted into pET-28a to create prokaryotic expression plasmid pET-EstA2. When pET-EstA2 was transformed into E. coli BL21, the recombinant was induced by IPTG. A pure recombinant protein was obtained by affinity purification. Compared with carboxylesterase A2 purified from Culex quinquefasciatus, carboxylesterase A2, purified from the product of the transgenic of E. coli, has the same Km, but the Vm was higher than that of it, which shows that carboxylesterase A2, purified from the product of E. coli by affinity, is purer than that from Culex quinquefasciatus. The study on the expression and characterization of carboxylesterase A2 in E. coli is more useful for its future application.

Animals↗

PubMed2001

Evaluation of myocardial viability with myocardial contrast echocardiography: a preliminary clinical study.

OBJECTIVE: To evaluate the efficacy of myocardial contrast echocardiography (MCE) in the assessment of myocardial viability, with positron emission tomography (PET) as the golden standard. METHODS: Eleven patients with anterior wall Q wave myocardial infarction were enrolled in this study, who received successful percutaneous transluminal coronary angioplasty (PTCA) 3 to 19 months prior to the examinations by PET and MCE that were completed within 2 d. RESULTS: MCE score for the segments of necrotic myocardium, viable myocardium and normal myocardium was mostly 0, 0.5 and 1 respectively, and there was a significant difference between the grades of MCE score in identifying myocardial viability. In terms of diagnosing myocardium survival, MCE result was closely correlated with that of PET (with the correlation index rp of 0.78). CONCLUSION: Myocardial perfusion evaluation can be effectively accomplished by MCE, which might serve as a new approach to assess myocardial viability in clinical practice.

Journal Article↗

PubMedDate not supplied

Studying the explanatory capacity of artificial neural networks for understanding environmental chemical quantitative structure-activity relationship models.

Although artificial neural networks (ANNs) have been shown to exhibit superior predictive power in the study of quantitative structure-activity relationships (QSARs), they have also been labeled a "black box" because they provide little explanatory insight into the relative influence of the independent variables in the predictive process so that little information on how and why compounds work can be obtained. Here, we have turned our interests to their explanatory capacities; therefore, a method was proposed for assessing the relative importance of variables indicating molecular structure, on the basis of axon connection weights and partial derivatives of the ANN output with respect to its input, which can identify variables that significantly contribute to network predictions, and providing a variable selection method for ANNs. We show that, by extending this approach to ANNs, the "black box" mechanics of ANNs can be greatly illuminated, thereby making it very useful in understanding environmental chemical QSAR models.

Algorithms↗

PubMedDate not supplied

Mechanism of radical cation formation from the excited states of zeaxanthin and astaxanthin in chloroform.

The C-40 xanthophylls zeaxanthin and astaxanthin were confirmed to form radical cations, Car.+, in the electron-accepting solvent chloroform by direct excitation using subpicosecond time-resolved absorption spectroscopy in combination with spectroelectrochemical determination of the near-infrared absorption of Car.+. For the singlets, the S2(1B(u+) state and most likely the S(x)(3A(g)-) state directly eject electrons to chloroform leading to the rapid formation of Car.+ on a timescale of approximately 100 fs; the lowest-lying S1(2A(g)-) state, however, remains inactive. Standard reduction potential for Car.+ was determined by cyclic voltametry to have the value 0.63 V for zeaxanthin and 0.75 V for astaxanthin from which excited state potentials were calculated, which confirmed the reactivity toward radical cation formation. On the other hand, Car.+ formation from the lowest triplet excited state T1 populated through anthracene sensitization is mediated by a precursor suggested to be a solute-solvent complex detected with broad near-infrared absorption to the shorter wavelength side of the characteristic Car.+ absorption. However, ground state carotenoids are able to react with a secondary solvent radical to yield Car.+, a process occurring within 16 micros for zeaxanthin and within 21 mus for astaxanthin. Among the two xanthophylls together with lycopene and beta-carotene, all having 11 conjugated double bonds, zeaxanthin ranks with the highest reactivity in forming Car.+ from either the S2(1B(u+)) or the ground state. The effects of substituent groups on the reactivity are discussed.

Journal Article↗