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Biomedical subjects

P Zhang

Publications and source records attributed to P Zhang.

At least 145 records · Page 8Linked to original sources
PubMed2001

[The effect of rIFN alpha-2b on mice NK cell activity].

OBJECTIVE: This animal experiment was made to study the effect of the recombined interferon alpha-2b(rIFN alpha-2b) on natural killer cells activity of mice spleen in vivo, and by way of this, to test the activity of rIFN alpha-2b. METHODS: BALB/c mice were given rIFN alpha-2b subcutaneously. The inhibiting 3H-TdR intaking method was used to test the NK activity of spleen cells of BALB/c mice. RESULTS: The NK cell activity levels of the high-dose group, the mid-dose group and the low-dose group were 65.19 +/- 17.56, 44.19 +/- 14.30 and 35.46 +/- 17.49, respectively. CONCLUSION: rIFN a-2b can enhance NK cells activity observably and its effect is dose dependent.

Animals↗
PubMed2001

[A study of analyzing short-chain fat acid by gradient reversed-phase high-performance liquid chromatography].

OBJECTIVE: The objective of this study is to obtain the optimized separating conditions of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, succinic acid from bacteria using reversed-phase high performance liquid chromatograph (RP-HPLC), and to set up a reliable progress in identifying the end-products of oral bacteria. METHODS: The conditions of separating seven short-chain fat acids were optimized using the method of gradient RP-HPLC. RESULTS: The study showed that the optimal chromatographic parameters were: 1.0 ml/min and 2.0 ml/min of flow rates, and the wavelength of ultraviolet detection was 217 nm. The composition of eluent: the ratio of phosphate buffer (pH 2.8) to methanol is 95:5 (v/v), gradient 5%-50%. The liner gradient wash will be performed in 10 minutes at room temperature. The average recovery rate was 92%, and RSD was 1.8%. CONCLUSION: The results of this paper will be helpful to determine acid composition of end products of oral bacteria.

Chromatography, High Pressure Liquid↗
PubMed2001

[An experimental study on demineralization of several beverages on bovine enamel].

OBJECTIVE: The aim of this study is to investigate the demineralization effects of several beverages on bovine enamel. METHODS: The concentration of calcium and phosphate in these beverages were measured by using EL 312e Micro-Plate after the bovine enamel was exposed to beverages for a period of 7 days. RESULTS: The data indicated that almost all of these beverages could cause demineralization of bovine enamel, except mineral water, and the concentration of calcium and phosphate in these beverages changed after the bovine enamel was exposed to beverages. There were great significant differences in demineralization abilities among different beverages (P < 0.01). The concentration of calcium and phosphate in beverages also changed with time (P < 0.01). CONCLUSION: All these beverages, except mineral water have erosive effects on bovine enamel. Demineralization degree varied with kinds of beverages. The fruit juice has the highest erosive effect on the enamel, and the calcium milk has the lowest erosive effect on the bovine enamel, when comparing with other beverages.

Animals↗
PubMed2001

[Identification and location of the toxin protein genes in 56 Bacillus thuringiensis isolates].

Polymerase chain reaction was performed to screen Bacillus thuringiensis isolates for cryI, cryIII, and cryV genes with cryI-, cryIII-, and cryV-specific primers respectively. The results indicated that, in the 56 Bt isolates examined, 7 isolates contain cryI gene, 2 isolates contain cryIII gene, and 21 isolates contain both cryI and cryV genes. The cryV gene was located by Southern hybridization in the large plasmid of about 150 MD molecular mass.

Bacillus thuringiensis↗
PubMed2001

[Amplifying variable region gene of light chain of monoclonal antibody against human retinoblastoma by PCR].

OBJECTIVE: To acquire the variable region gene of light chain of monoclonal antibody against human retinoblastoma. METHODS: Total RNA were extracted from hybridoma cells secreting specific monoclonal antibody(McAb) against human retinoblastoma(RB), then transcripted reversely into cDNA with random primers. The variable region of the light chain(VL) gene fragments were ampliflied using polymerase chain reaction(PCR) method. Agrose gel electrophoresis was confirmed. RESULTS: 1.5% agrose gel electrophoresis indicated that VL gene was about 340 base pairs. CONCLUSION: The light chain variable region gene of the McAb against human RB was amplified successfully, which lays a good basis for construction of a recombinant antibody.

Antibodies, Monoclonal↗
PubMed2001

Histopathological study of trabeculum after excimer laser trabeculectomy ab interno.

PURPOSE: To study the clinical manifestations and histopathologic changes of trabeculum after excimer laser trabeculectomy ab interno (ELT), and to investigate the mechanisms of ELT in reducing intraocular pressure. METHODS: ELT was performed on ten rabbit eyes and postoperative responses were documented. Corneoscleral tissue samples were harvested consecutively each week until the 5th postoperative week and these samples were examined under light and electrical microscopy. RESULTS: Mild stimulation signs were present postoperatively in nine of ten eyes, but no serious complications were experienced. Obvious inflammation was observed in one rabbit eye as a result of iris damage during the surgical manipulations. Local fractures on the trabecular meshwork and openings into Schlemm's canal were detected in all tissue samples under light microscope. Mitochondria were found to be turgescent and dilated like vacuoles and endoplasmic reticula were found to be dilated under electrical microscope in the early postoperative period. Later, all trabecular cells returned normal and no fibroblast cells were ever detected. CONCLUSIONS: Permanent openings through trabecular meshwork into the inner wall of Schlemm's canal can be created with ELT. The outflow resistance of aqueous humor can be reduced with these openings and intraocular pressure can be controlled thereafter.

Animals↗
PubMed2001

Pathological, ultrastructural and immunohistochemical observations of adenoma of retinal pigment epithelium.

PURPOSE: To Study the clinical, pathological, ultrastructural and immunohistchemical characters of adenoma of the retinal pigment epithelium in order to offer evidence to diagnose this tumor. METHODS: Routine paraffin slices HE stain, histochemistry PAS and VG stain, transmission electron microscopy, and immunohistochemistry for S-100 and vimentin with LSAB method were used. RESULTS: The tumor cells were oval and cuboidal in shape. Part of the tumor had a tubular arrangement. Around the sheets of tumors cells there was a large amount of uniform red stick-like substances. The above matter represented positive in PAS stain. Most of the above matter was yellow, while less of the matter showed red in VG stain. Transmission electron microscopy showed that there were tight junctions between tumor cells. Immunohistochemistry showed positive for S-100, negative for vimentin. CONCLUSIONS: The ultrastructural and immunohistochemical characters of the adenoma of retinal pigment epithelium are consistent with the retinal pigment epithelium.

Adenoma↗
PubMed2001

[Cytotoxic effect of Acanthamoeba trophozoite on HeLa cells].

OBJECTIVE: To investigate the cytotoxic effect(CTE) on human cervix cancer HeLa cells induced by five strains of pathogenic free-living Acanthamoeba. METHODS: The cytotoxic effect of five isolates of Acanthamoeba on HeLa cells was investigated by light microscopy and MTT method. RESULTS: The photomicrographs of HeLa cells showed a sequence of cardinal morphological features of apoptosis when HeLa cells were exposed to Acanthamoeba in a time-dependent manner at a ratio of 1:1 for 12 h. MTT method showed more than 50% of tumor cells underwent cytolysis following exposure to A. lugdunensis trophozoites, and only 18% of cells treated with A. polyphaga underwent CTE. The CTE produced by A. lugdunensis and A. quina trophozoites was more rapid than the others, beginning as early as 6 h after coincubation and resulting in cytolysis by 72 h. CONCLUSION: These five strains of Acanthamoeba exhibit cytotoxic effects of varying degrees on HeLa cells, inducing apoptosis.

Acanthamoeba↗
PubMed2001

[The contents and their change of nucleosides from natural Cordyceps sinensis and cultured cordyceps mycelia].

AIM: To compare the content of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia, and the effect of humidity and heat on the contents of nucleosides. METHODS: The contents of nucleosides were determined using high performance capillary electrophoresis (HPCE). Beckman P/ACE System 5010 apparatus equipped with a UV detector and a Beckman untreated fused-silica capillary (57 cm x 75 microns, 50 cm effective length) were used. Before sample injection, the capillary was rinsed with 1 mol.L-1 sodium hydroxide and running buffer for 5 minutes, respectively. 20 kV was applied during separation. Pressure injection was 586 kPa for 6 seconds, and the wavelength of detector was 254 nm. The running time was 20 minutes at 20 degrees C. The effect of humidity and heat on the content of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia was observed for 1, 3, 5 and 10 days at temperature 40 degrees C, and relative humidity 75%. RESULTS: The contents of nucleosides from cultured Cordyceps mycelia were higher than that of those from natural Cordyceps sinensis. The contents of nucleosides from freshly collected natural Cordyceps sinensis, were under the detection limit. The contents of nucleosides from natural Cordyceps sinensis were significantly increased by effect of humidity and heat, the phenomenon was not observed in cultured Cordyceps mycelia. CONCLUSION: There are difference in nucleosides content between natural Cordyceps sinensis and cultured Cordyceps mycelia. The nucleosides in natural Cordyceps sinensis may be derived from the degradation of macro-molecular nucleic acids. That means it is probably controversial that adenosine was used for quality control of natural Cordyceps sinensis.

Adenosine↗
PubMed2001

[The effect of AG490 on NK activity and lymphocyte transformation of PBMC].

OBJECTIVE: To examine the effect of AG490 on NK activity and lymphocyte transformation. METHODS: Using MTT colorimetry to detect cell survival, NK activity and cell proliferation. RESULTS: AG490 inhibited IL-2 and PHA induced peripheral blood mononuclear cell proliferation, and it inhibited NK activation. CONCLUSION: As an inhibitor of JAK, AG490 can influence the function of normal cells.

Cell Division↗
PubMed2001

[Comparative effects of carvedilol and metoprolol in preventing from left ventricular remodeling after acute myocardial infarction in rats].

OBJECTIVE: To compare the effects of carvedilol and metoprolol in preventing from left ventricular remodeling (LVRM) after acute myocardial infarction (AMI) in rats. METHODS: Twenty-four hours after ligating left coronary artery, 105 surviving female SD rats were randomly assigned to AMI control, carvedilol 1 mg/(kg.d) and metoprolol 2 mg/(kg.d) groups. Sham-operated rats (n = 16) were selected randomly as non-infarction control. After four weeks of drugs therapy, hemodynamic studies and pathologic analysis were performed. Exclusive of MI size < 35% or > 55%, complete experimental variables were obtained in 46 rats, which were comprised of AMI (n = 11), carvedilol (n = 12), metoprolol (n = 11), and Sham-operated (n = 12) groups. RESULTS: Compared with sham-operated group, left ventricular (LV) end diastolic pressure (LVEDP), volume (LVV) and weight (LVW), were all significantly increased (P < 0.05-0.001), while maximal rate of rise and fall (+/- dp/dt) of LV pressure as well as their corrected values (+/- dp/dt/LVSP) were all significantly decreased (P < 0.01-0.001) in AMI group. In comparison with AMI group, the LVEDP and LVV were all significantly decreased (all P < 0.001), while +/- dp/dt and +/- dp/dt/LVSP were significantly increased (P < 0.05-0.001) in both carvedilol and metoprolol group, with LVW and RVW only decreased in carvedilol group (P < 0.05-0.01). CONCLUSIONS: 1. Carvedilol can effectively attenuate LVRM, and improve hemodynamics and LV function after AMI in rats, 2. Metoprolol has equivalent beneficial effects as carvedilol on hemodynamics, LV dilatation and function, but not LV hypertrophy.

Adrenergic beta-Antagonists↗
PubMed2001

[Defect analysis in mercury cadmium telluride by Raman scattering].

Telluride precipitates in HgCdTe(MCT) and Raman scattering peaks of Hg vacancies are reported. We also analyze the relationship between the crystal surface perfection of MCT and its second-order scattering peaks. Intense bands at 125 and 145 cm-1 confirm them to be precipitates, and there is 2 cm-1 shift to high frequency in comparison with intense bands of normal trigonal Te. This shows the compressive stress exists around Te precipitates. The weak Raman peak at 108 cm-1 arise from Hg vacancies. This peak is only found in p-type MCT and MCT including p-n junction, and is not found in n-type MCT. The intensity of the second-order scattering peaks in MCT is very sensitive to its crystal surface perfect. To good surface perfect, these peaks are very distinct, and to poor surface perfect, they are not distinct. The intensity measurement of 2LO(T) mode in the second-order scattering peaks can provide useful information for surface analysis in crystal preparation process.

Cadmium↗
PubMed2001

[Study of Raman-PL spectra for GaAs layer on Si substrate in hot wall epitaxy].

The quality of GaAs layer on the Si substrate under different growth conditions with HWE technology was studied by Raman and PL spectra. The results show that the ratio of peak value to area for the TO peak at 265 cm-1 increased gradually with the improvement of the GaAs crystallinity quality for the GaAs layer at 300 K. The FWHM of Raman spectra of TO peak at 265 cm-1 is narrow, and the Raman shift is 2 cm-1. In the PL spectra, the FWHM at 900 nm is narrow. Then the results show GaAs layer is highly structural quality. But if we can not measure the PL peak at 900 nm, or the FWHM of Raman spectra of TO peak at 265 cm-1 is not narrow, the GaAs layer is not crystallinity. Therefore, we can estimate the layer quality by Raman and PL spectra.

Arsenicals↗
PubMed2001

[A comparison of SERS of positive and negative nano-silver adsorbing cation and anion molecule].

A study on the negative charge colloid of nano-silver particles with anion and cation molecules has been done. The results of the experiment show that the negative charge colloid of nano-silver particle has no SERS effect when anion molecule adsorbed on its surface. While the cation molecule in adsorbed on its surface the SERS effect is enhanced. The SERS effects are just opposite when the two molecules separately adsorbed on the surface of the positive colloid of nano-silver particles. The paper hypothesizes that strong SERS effect can be got by using proper colloid of nano-silver particles. It is practical to develop the use of SERS.

Adsorption↗
PubMed2001

[Blue shift of Raman peak of DBS/TiO2 nanoparticles].

Nanosized TiO2 coated with dodecylbenzenesulphonic acid (DBS) was prepared using the hydrothermal procedure. The average size of DBS/TiO2 is very small, about 8 nm. Raman spectra from DBS/TiO2 was measured, and scattering signals from both TiO2 and DBS were observed. It was found that in contrast to the red shift of Raman peaks in the nanoparticle with reducing the particle size, a blue shift, namely the Raman peak shift to higher frequency, in the nanosized DBS/TiO2 particles was recorded. Meanwhile, we found that every Raman peak of TiO2 show different amount of Raman shifts. We discussed the possible origin of the blue shift.

Benzenesulfonates↗
PubMed2001

[The enhanced mechanism of Cl- to SERS in silver colloid].

The SERS is enhanced when KCl is added to silver colloid and cation molecule. The hypothesis supposed that Cl- bridged between nano-silver and molecule, as a result the molecule adsorbing on nano-silver surface is promoted and the SERS is therefore enhanced. The CN- and NH3 can be better adsorbed when they are added separately to the nano-silver particles, Cl- and anion molecule. The SERS reduces when CN- and NH3 are added separately to Cl-, anion molecule and silver colloid. The result is that the CN- and NH3 are so strong that they have replaced Cl- and anion molecules. Therefore the SERS reduces. This has proved the bridge role of Cl-.

Adsorption↗