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Biomedical subjects

S Zhang

Publications and source records attributed to S Zhang.

At least 379 records · Page 21Linked to original sources
PubMed2000

Protective effect of bradykinin against glutamate neurotoxicity in cultured rat retinal neurons.

PURPOSE: To identify the localization and expression of bradykinin (BK)-B2 receptors in rat retina and examine the effects of BK on glutamate-induced neurotoxicity using cultured rat retinal neurons. METHODS: An immunohistochemical study using a specific antibody against BK-B2 receptor was performed with rat retina. Primary cultures were obtained from the retina of fetal rats (gestation day 17-19). Expression of BK-B2 receptor mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR) using total RNA obtained from cultured retinal neurons. Cultured cells were exposed to glutamate (1 mM) for 10 minutes and followed by incubation in glutamate-free medium for 1 hour. The effects of BK were assessed by simultaneous application of BK with glutamate. The neurotoxic effects on retinal cultures were quantitatively assessed by the trypan blue exclusion method. RESULTS: Immunohistochemical study demonstrated that BK-B2 receptors were expressed in the ganglion cell, inner nuclear layers, and outer nuclear layers. Furthermore, BK-B2 receptor mRNA expression was observed in cultured retinal neurons. Cell viability was markedly reduced by 10-minute exposure to 1 mM glutamate followed by a 1-hour incubation in glutamate-free medium. Simultaneous application of BK at concentrations of 0.001 to 1 microM with glutamate demonstrated dose-dependent protection against glutamate neurotoxicity. The protective action of BK (1 microM) was inhibited by simultaneous application of BK-B2 receptor antagonist, Hoe140 (1 microM). Furthermore, 1 microM BK had protective effects on neurotoxicity induced by 1 microM ionomycin, a calcium ionophore, and sodium nitroprusside (SNP, 500 microM), a nitric oxide (NO)-generating agent. However, BK did not inhibit neurotoxicity induced by 3-morpholinosydnonimine (SIN-1, 10 microM), an NO and oxygen radical donor. CONCLUSIONS: These results suggest that BK-B2 receptors were distributed in rat retinas and cultured retinal neurons and that BK had a protective action against glutamate neurotoxicity through BK-B2 receptors in cultured retinal neurons. It is suggested that BK-induced protection against glutamate neurotoxicity took place downstream to NO generation and upstream to oxygen radical generation.

Adrenergic beta-Antagonists↗
PubMed2000

[Genetic polymorphisms of eight STR loci in a Chinese Han population].

OBJECTIVE: To understand the allele structure and genetic polymorphism at eight STR loci in Chinese Han population and construct a preliminary database. METHODS: EDTA-blood specimens were collected from the unrelated individuals in Chengdu, China. The DNA samples were extracted with Chelex method and were amplified by PCR technique. The PCR products were analyzed by the PAG horizontal electrophoresis with discontinuous buffer system and by the approach of the automated fluorescence detection. RESULTS: Five STR loci consist of simple repeat motifs, while three STR loci contain complex repeat structures. The STR polymorphisms at all of the eight loci have been observed in Chinese Han population. According to the obtained data, the combined exclusion probability and the combined discrimination power for these STR markers in Chinese population are 0.9978 and 0.999 999 992, respectively. CONCLUSION: The obtained data are beneficial to understanding the population genetics of the eight STR loci in Chinese Han population. For forensic genetics, the obtained data can be used to calculate the probabilities dealing with the paternity test and the individual identification.

China↗
PubMed2000

[Polymorphisms of four STRs and their associations with IDDM in Chinese Han population].

OBJECTIVE: To obtain the polymorphic data of short tandem repeat(STR) loci of D15S657, D11S1369, D6S2420 and D6S503 in Chinese Han population and to study the association of these four STR loci with insulin-dependent diabetes mellitus(IDDM). METHODS: The polymorphisms of the four STRs were studied by polymerase chain reaction-polyacrylamide gel electrophoresis(PCR-PAGE) followed by direct sequencing of PCR products in 105 normal Chinese Hans and 48 patients with IDDM. RESULTS: Seven alleles at D15S657 locus, 5 alleles at D11S1369 locus, 7 alleles at D6S2420 locus and 4 alleles at D6S503 locus were found. No deviation from Hardy-Weinberg equilibrium was observed. The heterozygosities of these loci were 0. 7524, 0.6000, 0.6286, 0.6571 and the polymorphic information contents(PIC) 0.7616, 0.4430, 0.5345 and 0.5932, respectively. The allele frequencies of allele A(5) at D15S657 locus, allele A(5) at D11S1369 locus and allele A(4) at D6S2420 locus were increased significantly in patients with IDDM, compared to those in the control group. CONCLUSION: The four STRs, used as genetic markers, were suitable for case-control study, forensic medicine identification and population genetic study. There is an association between the polymorphisms of D15S657, D11S1369, D6S2420 and IDDM.

Adult↗
PubMed2000

Milk thistle, a herbal supplement, decreases the activity of CYP3A4 and uridine diphosphoglucuronosyl transferase in human hepatocyte cultures.

Milk thistle extract is one of the most commonly used nontraditional therapies, particularly in Germany. Milk thistle is known to contain a number of flavonolignans. We evaluated the effect of silymarin, on the activity of various hepatic drug-metabolizing enzymes in human hepatocyte cultures. Treatment with silymarin (0.1 and 0.25 mM) significantly reduced the activity of CYP3A4 enzyme (by 50 and 100%, respectively) as determined by the formation of 6-beta-hydroxy testosterone and the activity of uridine diphosphoglucuronosyl transferase (UGT1A6/9) (by 65 and 100%, respectively) as measured by the formation of 4-methylumbelliferone glucuronide. Silymarin (0.5 mM) also significantly decreased mitochondrial respiration as determined by MTT reduction in human hepatocytes. These observations point to the potential of silymarin to impair hepatic metabolism of certain coadministered drugs in humans. Indiscriminate use of herbal products may lead to altered pharmacokinetics of certain drugs and may result in increased toxicity of certain drugs.

Cells, Cultured↗
PubMed2000

An enzymologic study on bone marrow cells in patients with aplastic anemia treated by supplementing the kidney and removing blood stasis.

The content of cytochrome oxidase (CCO), succinate dehydrogenase (SDH) and neutrophil alkaline phosphatase (NAP) in bone marrow cells in 68 cases of aplastic anemia before and after treatment was determined by computerized graphical analysis and compared with that of normal volunteers (control group). The significantly lowered CCO and SDH levels and the markedly increased NAP content before treatment (P < 0.01) became approximately normal after that of supplementing the kidney and removing blood stasis (P > 0.05).

Adolescent↗
PubMed2000

[Studies on the polymorphism of MICA gene in four Chinese populations].

OBJECTIVE: To understand with greater clearness the genetic polymorphism of (GCT)n repeat of MHC class I chain-related gene A (MICA)in some Chinese populations and provide preliminary genetic evidence for the independent origin of Chinese Baima Tibetan (BMT). METHODS: ACD-blood or saliva specimens of 411 unrelated individuals from four Chinese populations were collected. A primer pair spanning exon 5 of MICA gene was used to amplify the GCT region. Alleles were detected by PCR and denaturing PAGE. Comparison of the allelic distributions among the four populations was carried out. RESULTS: Five previously reported alleles have been observed in all the four populations, but the allelic distributions are different from one another. The most frequent allele is the A5 in all the four populations (0.325 in BMT, 0.345 in Tibetans, 0.390 in Chengdu Hans and 0.319 in Qiangs). A5.1 allele is the second most frequent allele in Chengdu Hans (0.230) and in Qiangs (0.293), while the second most frequent alleles for BMT and Tibetans are A4 (0.254) and A9 (0.272) respectively. The distribution of alleles in BMT is significantly different from that in the other three populations. CONCLUSION: Alleles of MICA gene exon 5 are conservative in all populations studied so far. The results suggest that genetically BMT might be an independent ethnic population.

Alleles↗
PubMed2000

[Genotyping cytochrome P450IIE1 in alcoholic liver diseases and its significance].

OBJECTIVE: To study the relationship between genotypes of cytochrome P450IIE1 (IIE1 ) and development of chronic liver diseases. METHODS: Cytochrome P450IIE1 was genotyped by PCR and restricted endonucleases digestion of DNA prepared from peripheral white blood cells. RESULTS: IIE1 could be divided into three types: A, B and C based on different products digested by two endonucleases. In normal controls predominant genotypes were A and B. No relationship was found between development of non-alcoholic chronic liver diseases and IIE1 genotypes. Its genotype distribution was similar to normal controls. Detection of type A in alcoholic liver diseases was significantly decreased and type B was significantly increased (P<0.01). Detection of type A in alcohol-related hepatocellular carcinoma was also decreased and type B increased compared to non-alcohol-related hepatocellular carcinoma. CONCLUSION: IIE1 genotypes play some roles in development of alcoholic liver diseases and alcohol-related hepatocellular carcinoma.

Adult↗
PubMed2000

[Study on preparation and biodistribution of PEG-immunoliposomes with active carboxylic terminals].

AIM: In order to accumulate into its target specifically, the immunoliposomes must possess two characteristics: specific target efficiency to its target cells and prolonged circulation in blood. A new type of polyethylene glycol (PEG)-immunoliposomes carrying monoclonal antibodies at the distal end of PEG chains should be developed. METHODS: A dipalmitoylphosphatidylethanolamine (DPPE) derivative of PEG with carboxyl group (DPPE-PEG3000-COOH) was newly synthesized. Small unilamellar liposomes were prepared from egg phosphatidyl choline and cholesterol (5:4, mol/mol) containing 6 mol% DPPE-PEG3000-COOH using reverse-phase evaporation method followed with bath sonication. Monoclonal antibody of human bladder cancer cell (BDI-1), which is highly specific to human bladder cancer cell, was conjugated to PEG-liposomes as well as mouse IgG at the distal end of polyethylene glycol chain. Doxorubicin was entrapped into these immunoliposomes by remote (NH4)2SO4 gradient loading method. The specific targeting efficiency of these immnoliposomes was tested by cytotoxicity test in vitro, enzyme-linked immune sorbent assay (ELISA) and indirect fluorescent immunoassay. Its biodistribution was carried out in mice. RESULTS: The specific targeting efficiency of BDI-1 immunoliposomes (BDI-1-IML) to EJ cells has been demonstrated, in contrast to the nonspecific human colon carcinoma cells (LOVO). PEG-liposomes linked with mouse IgG (mouse-IgG-immunoliposomes, IgG-IML) displayed lower reticulo-endothelial systems (RES) uptake and longer circulation time than liposomes without PEG after intravenous injection. CONCLUSION: The long circulation of these PEG-immunoliposomes in vivo, combined with its specific targeting efficiency demonstrated in vitro, guarantees the positive targeting efficiency of these immunoliposomes to its target carcinoma in vivo.

Animals↗
PubMed2000

Peptide-mediated cellular delivery.

Peptide-mediated molecular therapeutic delivery systems have recently emerged as an alternative means to effectively substitute or augment present gene therapy technologies, e.g., TAT, VP22, engineered peptides. These systems show great promise for the elimination of the main bottleneck to safe, efficient, targeted gene therapy delivery and are able to efficiently introduce DNA, antisense peptide nucleic acids, oligonucleotides, small molecules and proteins into cells both in vitro and in vivo. They are versatile and easily designed to incorporate a number of specific attributes required for efficient cargo delivery. A fundamentally new property of these moieties will allow the therapeutic intervention in the biochemistry of the target cell without the need to alter its genome.

Animals↗
PubMed2000

Leukoplakia and angiopoiesis resistance of Herba Erigerontis.

OBJECTIVE: To evaluate the effects of Herba Erigerontis on angiopoiesis and carcinogenesis; to seek an effective drug for prevention of leukoplakia progression to carcinoma and to stop the mechanism of angiopoiesis. METHODS: Carcinomatous conversions of golden hamster cheek pouches induced by Salley way and inhibited by Herba Erigerontis. Ink perfusion, analysis of images, resin cast form of micro-vessel, a-SMA detection and histopathological examination were applied to observe their changing patterns. RESULTS: The rate of leukoplakia conversion to tumor of the Herba Erigerontis group was half that of model group. The proportion of normal cells was approximately 4 times greater than that of model. The a-SMA levels of the Herba Erigerontis treated group was higher than that of model (P < 0.001). There was no significant difference between angeion vessel area and density (P > 0.05) in these 2 groups, which were elevated compared to the control. Nevertheless, the resin casts of the microvasculature in the Herba Erigerontis group showed that its configuration and spatial arrangement was similar to the control group. CONCLUSIONS: Herba Erigerontis has the function of inhibiting leukoplakia progression to tumor. This may be due to its ability to upregulate the expression of a-SMA. It has no obvious effect on angio-hyperplasia and expansion in the course of leukoplakia progression to tumor. However, it may preserve the angio-configuration and spatial arrangement and keep intact the angeion vessel wall. Its mechanism of promoting blood circulation may be through removing blood stasis and benign angiopoiesis so as to resist carcinogenesis.

Actins↗
PubMed2000

[Study on unsupervised classification in marshland of endemic area of Schistosomiasis Japonica using satellite TM image data].

OBJECTIVE: To categorize the vegetation of marshland in the endemic areas of Schistosomiasis Japonica using satellite thematic mapper (TM)data in Liupo Village, Anhui Province. METHODS: Data of three satellite TM hands, namely TM3, TM4 and TM5, were selected to be used in classification with principal component analysis. Then, satellite TM images were applied to false color composite and unsupervised classification with computer software to manage the images. Finally, the resulting clusters were identified and reclassified by site visits to categorize the land coverage and vegetation. RESULTS: Five classifications of land coverage were generated, including poplar forest, bulrush and marshland, all with snail habitants. Based on the survey in the spring of 1998, the overall live snail density and infested snail density in the study areas were 0.510/0.11 m2 and 0.007/0.11 m2, respectively. CONCLUSION: Unsupervised classification, which is a technique for the interpretation of remotely sensed imagery, can contribute to the classification of environment with snail habitants and ecological diseases and become a new method in epidemiological studies.

Animals↗
PubMed2000

[Studies on the chemical constituents of Kaempferia marginata].

AIM: To study the chemical constituents of the rhizomes of Kaempferia galanga L. (Zingiberaceae). METHODS: Various chromatographic techniques were used to separate and purify. Their physico-chemical properties and spectral data were used to elucidate the structures. RESULTS: Six compounds were isolated from the hexane extract of K. galanga. Their structures were identified as marginatol (1), 8 (14), 15-sanderacopimaradiene-1 alpha, 9 alpha-diol (2), 8 (14), 15-sanderacopimaradiene-1 alpha, 6 beta, 9 alpha-triol (3), germacrone (4), trans-ethyl p-methoxycinnamate (5) and n-pentadecane (6) on the basis of spectral data (IR, MS, 1H-1H, 13C-1H NMR, NOEs and HMBC). CONCLUSION: Marginatol (1) is a new isopimarene diterpenoid and was elucidated as 8(14), 15-isopimaradiene-6 alpha-ol. Compounds 2, 3 and 4 were isolated for the first time from this plant.

Diterpenes↗
PubMed2000

[Contraception in early 20th century China].

Modern contraception began early this century. In 1922, Mrs. Sanger of America came to China. Her theories of contraception and methods became the classical basis cited by Chinese workers on contraception. The Modern Women published since 1922 was the first professional publication in China, carrying many articles written by Chinese scholars. Monographs and translation of foreign works were also published. An institute for contraception was also founded in 1930. The Chinese Medical Association officially recognized contraceptive work as one of the public health works, marking the contraception, once lead by sociologists, under the category of the professional medical works.

China↗
PubMed2000

[Effect of temperature and food on Spodoptera litura population].

The relationship between temperature and development of Spodoptera litura was simulated by the sine model V(T) = A + B sin(C0 + C1eC3T + C2e-C3T), and the threshold temperature and thermal requirement for its development at different stages were estimated by the direct optimum method. The model for the relationship between temperature and survival rate was fitted by the experimental data. The theoretical optimum temperature for the development of eggs, young instar larvae, old instar larvae and pupae was 26.7, 24.7, 24.9 and 25.8 degrees C, respectively. The life table parameters under different feed conditions (cabbage, lotus, sweet potato, soybean leaves) were estimated by the method of bisexual life table with age-structure. At temperature 25 degrees C, the intrinsic rates of increase under the four different feed conidtions were 0.1836, 0.1719, 0.1778 and 0.1206, respectively.

Animals↗
PubMed2000

[Continuous cropping obstacle and rhizospheric microecology. II. Root exudates and phenolic acids].

This paper discussed the effect of main crop root exudates the relationship between the kinds and amounts of root exudates and the growth of different kinds of crops and their environments. From the aspects of the decompostion of crop residues and the excretion of root systems, the source, form and adsorption mechanism of soil phenolic acids and their effect on crop growth and soil bio-activity were also elaborated.

Agriculture↗
PubMed2000

[Continuous cropping obstacle and rhizospheric microecology. III. Soil phenolic acids and their biological effect].

The contents of phenolic acids in the extracts of soil and roots of continuously cropped for five years and normally cropped soybean in Heilongjiang province and their biological effects were studied with HPLC method. The result showed that the contents of p-hydroxy benzoic acid, vanillic acid(extracted by 1 mol.L-1 NaOH) in continuous cropping soil were significant higher than that in normal cropping soil, and the content of vanillin had no significant difference in these soils. The contents of p-hydroxybenzoic acid, vanillic acid, vanillin, ferulic acids, and coumarin of aqueous extracts of soyhean roots were higher in continuous cropping than in normal cropping soil. The activity of polyphenol oxidase in continuous cropping soil was higher than in normal cropping soil. Under conditions of water culture and adding exogenous p-hydroxybenzoic acid, the aqueous extract of soybean roots inhibited the growth of soybean seedlings. After a week of exogenous phenolic acids addition, the residual rates of p-hydroxybenzoic acid, vanillic acid, vanillin, benzoic acid, ferulic acids, and coumarin were 10.4%, 15.3%, 4.1%, 2.3%, 5.2%, 17.5%, respectively. There was a very significant exponential relationship between the addition amount of exogenous phenolic acids and the fungi population in soil.

Agriculture↗
PubMed2000

[Rhizosphere effect of nutrients in different maize soils with different fertility levels].

Maize plants and soil samples were collected from Jilin Province to study the nutrient dynamics in soil-maize plant rhizosphere and their relationship with plant uptake. The results showed that NH4(+)-N and NO3(-)-N were accumulated in rhizospheric soil, and mainly controlled by the application of chemical fertilizers. Soil available P was depleted in high fertility fields, especially in high seedling density, while accumulated in low fertility fields. Soil available K was accumulated in rhizospheric soil, and its accumulation rate was higher in high fertility than in low fertility fields. The nutrient absorption amount was N approximately K > P for maize plant shoots and roots, but was N > K > P for seeds. The contribution rate of chemical fertilizers to maize yield was only 1/5-1/3 in Jilin Province, and the rest was contributed by the application of organic manure, such as chicken feces or cow feces, and by the mineralization of soil organic matter.

Biomass↗