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Biomedical subjects

W Su

Publications and source records attributed to W Su.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Raman and infrared spectroscopic investigation of SO4(2-)/TiO2 solid acids].

The structure, crystal phase transition and surface acid centers of SO4(2-)/TiO2 solid acids calcined at different temperatures were studied by IR and Raman spectroscopy. The results showed that SO4(2-) is combined with metal ions of TiO2 in a chelating bidentate mode. When the calcination temperature is below 500 degrees C, the samples possess stable structure with anatase as the main crystal phase, and there are two types of acid sites (Lewis and Bronsted acid) on the samples, the amount of B acid is about twice as that of L acid. When the temperature is above 500 degrees C, surface SO4(2-) desorb gradually with increasing calcination temperature, leading to crystal phase transition from anatase to rutile and the surface B acid sites fade away.

Acids↗
PubMed2000

[Comparative studies on the spectral behavior between SO4(2-)/TiO2 and TiO2 photocatalysts].

The differences of spectral behavior between SO4(2-)/TiO2 and TiO2 photocatalysts were studied by using IR, Raman as well as UV-Vis diffuse reflectance spectroscopy(DRS). The results showed that both L and B acid sites exist on SO4(2-)/TiO2 photocatalyst while only L acid sites on TiO2 photocatalyst. As compared with unmodified TiO2, the sulfated TiO2 (SO4(2-)/TiO2) exhibits higher resistance to crystal phase transition from anatase to rutile, higher resistance to growth of crystal grain. As the results of sulfation, SO4(2-)/TiO2 samples possess higher anatase content, smaller crystal grain, and the blue-shifted band edge of adsorption spectra, which increases the optical absorption threshold value and yield larger redox potential.

Adsorption↗
PubMed1999

Ser-534 in the hinge 1 region of Arabidopsis nitrate reductase is conditionally required for binding of 14-3-3 proteins and in vitro inhibition.

14-3-3 proteins bind to the hinge 1 region of nitrate reductase (NR) and inhibit its activity. To determine which residues of NR are required for 14-3-3-inhibitory interactions, wild-type and mutant forms of Arabidopsis NR were examined in the yeast two-hybrid system and in vitro inhibition assays. NR fragments with or without hinge 1 were introduced into yeast with one of seven Arabidopsis 14-3-3 isoforms (called GF14s). NR fragments (residues 1-562 or 487-562) containing hinge 1 interacted with all GF-14s tested; an NR fragment (residues 1-487) lacking hinge 1 did not. GF14 binding to NR fragments was dependent on Ser-534, since Asp or Ala substitutions at this site blocked the interaction. Revertants with second site substitutions restoring interaction between GF14omega and the Ala- or Asp-substituted NR fragments were identified. One isolate had a Lys to Glu substitution at position 531, which is in hinge 1, and six isolates had Ile to Leu or Phe substitutions at 561 in the heme binding region. Double mutant forms of holo-NR (S534D plus K531E, I561F, or I561L) were constructed and found to be partially inhibited by protein extracts from Arabidopsis containing 14-3-3 proteins. Wild-type NR is phosphorylated and inhibited by these extracts, but S534D single mutant forms are not. These results show that inhibitory NR/14-3-3 interactions are dependent on Ser-534 but only in the context of the wild-type sequence, since substitutions at second sites render 14-3-3 binding and in vitro NR inhibition independent of Ser-534.

14-3-3 Proteins↗
PubMed1999

Age-related changes in susceptibility of rat brain slice cultures including hippocampus to encephalomyocarditis virus.

Replication of the D variant of encephalomyocarditis virus (EMC-D) and its cytopathic effects were studied in the brain slice cultures including hippocampus (hippocampal slice) obtained from postnatal 1-, 4-, 7-, 14-, 28-and 56-day-old Fischer 344 rats. At 0, 12, 24, 36 and 48 h after infection, virus titres of the slices and culture media were assayed. Viral replication was observed in cultures from 1-to 28-day-old rats, and the highest titre was recorded in the slice and culture medium from the youngest rat. The peak of virus titre decreased with age and no distinct viral replication was observed in the cultures from 56-day-old rats. Light microscopy revealed that degenerative and necrotic changes appeared in the infected hippocampal slices from 1- to 28-day-old rats, and the changes became less prominent with age. In situ hybridization and indirect immunofluorescence staining showed that positive signals of viral RNA and antigen were prominent in younger rats and decreased with age. These results suggest that an age-related decrease in the susceptibility of rat brain to EMC-D is less related to the maturation of the immune system but possibly to that of the neurone.

Aging↗
PubMed1999

Mouse K-Cl cotransporter KCC1: cloning, mapping, pathological expression, and functional regulation.

Although K-Cl cotransporter (KCC1) mRNA is expressed in many tissues, K-Cl cotransport activity has been measured in few cell types, and detection of endogenous KCC1 polypeptide has not yet been reported. We have cloned the mouse erythroid KCC1 (mKCC1) cDNA and its flanking genomic regions and mapped the mKCC1 gene to chromosome 8. Three anti-peptide antibodies raised against recombinant mKCC1 function as immunoblot and immunoprecipitation reagents. The tissue distributions of mKCC1 mRNA and protein are widespread, and mKCC1 RNA is constitutively expressed during erythroid differentiation of ES cells. KCC1 polypeptide or related antigen is present in erythrocytes of multiple species in which K-Cl cotransport activity has been documented. Erythroid KCC1 polypeptide abundance is elevated in proportion to reticulocyte counts in density-fractionated cells, in bleeding-induced reticulocytosis, in mouse models of sickle cell disease and thalassemia, and in the corresponding human disorders. mKCC1-mediated uptake of (86)Rb into Xenopus oocytes requires extracellular Cl(-), is blocked by the diuretic R(+)-[2-n-butyl-6,7-dichloro-2-cyclopentyl-2, 3-dihydro-1-oxo-1H-indenyl-5-yl-)oxy]acetic acid, and exhibits an erythroid pattern of acute regulation, with activation by hypotonic swelling, N-ethylmaleimide, and staurosporine and inhibition by calyculin and okadaic acid. These reagents and findings will expedite studies of KCC1 structure-function relationships and of the pathobiology of KCC1-mediated K-Cl cotransport.

3' Untranslated Regions↗
PubMed1999

[Chemical pattern recognition of traditional Chinese medicine xixin (II)].

The data matrix of macro and trace elements from 45 samples of traditional Chinese medicine Xixin were treated with principal component analysis and cluster analysis in order to establish why and how Xixin samples from different species can be recognized. According to the results of hierarchical clustering, three species of Xixin (Asarum heterotropoides Fr. var. mandshuricum (Maim.) Kitag., Asarum sieboldii Miq. var. seoulense Nakai and Asarum sieboldii Miq.) were classified and recognized accurately.

Aluminum↗
PubMed1999

[Chemical pattern recognition of traditional Chinese medicine xixin (I)].

In this paper, three species of traditional Chinese medicine Xixin (Asarum heterotropoides Fr. var. mandshuricum (Maxim.) kitag, Asarum sieboldii Miq. var. seoulense Nakai and Asarum sieboldii Miq.) were identified by means of chemical pattern recognition, with 26 samples as training set and 19 samples as test set. The numerical characteristic features for identification were obtained from GC-MS analysis of volatile oils, all of obtained data were treated with PRIMA (Pattern Recognition by Independent Multivariate Analysis), thus computerized classification of Xixin samples was accomplished. The results agree with those from pharmacognosy. As a new method, chemical pattern recognition is especially suitable for identification of a large number of traditional Chinese medicine samples.

Asarum↗
PubMed1998

Discovery of estrogen-responsive genes using an improved method which combines subtractive hybridization and PCR.

Here we describe a reliable method for isolating genes that are differentially expressed in two cell populations. The method is a combination of subtractive hybridization and PCR. Among many improvements to previously described methods is the incorporation of a new technology into the procedure which sterilizes(inactivates) PCR amplicons, and thereby overcomes the limitation of similar procedures. To test this improved method, we conducted a search for estrogen-responsive genes. Estrogen-regulated genes dominated the subtracted libraries after four rounds of subtractive hybridizations. Four estrogen-regulated genes were identified from the initial screening.

Estrogens↗
PubMed1998

Encephalomyocarditis (EMC) virus infection in PC12 and C6 cells.

PC12 cells derived rom rat pheochromocytoma and C6 cells derived from rat glioma were infected with 0.3 plaque forming units (PFU)/cell of the D variant of encephalomyocarditis virus (EMC-D), after pretreatment with or without nerve growth factor (NGF). The virus titres in medium and cells were investigated at 6, 12, 24, 48 and 72 h post infection (HPI), and histopathology and viral antigens in cells were examined at 24 and 48 HPI, respectively. As a result, neither viral replication nor light and electron microscopic changes were observed in PC12 cell cultures without NGF-pretreatment. On the contrary, in PC12 cell cultures with NGF-pretreatment, the virus titre prominently increased at 12 HPI, and peaked at 48 HPI. In addition, distinct histological and ultrastructural changes with viral antigens in cells were observed. C6 cells showed similar morphology and susceptibility to EMC-D-infection irrespective of NGF-pretreatment. Namely, the virus titres in C6 cell cultures increased slightly and viral antigens were found in a small number of C6 cells, but there were no evident histological and ultrastructural changes. These results suggest that PC12 cells pretreated with NGF and C6 cells are susceptible to EMC-D infection in vitro.

Animals↗
PubMed1998

Metabolism of Apo(a) and ApoB100 of lipoprotein(a) in women: effect of postmenopausal estrogen replacement.

The metabolism in plasma of apo(a) and apoB100, the major protein components of lipoprotein(a) [Lp(a)], and the mechanism by which estrogen lowers Lp(a) concentration are both not well understood. Estrogen or placebo were administered to 12 postmenopausal women in a double-blind cross-over design; and after each treatment, apo(a) and apoB100 in Lp(a) were endogenously labeled by i.v. trideuterated leucine. After estrogen treatment, mean Lp(a) concentration decreased during estrogen, from 25 mg/dL, by 20% (P < 0.01); and the mean production rate of apo(a) decreased, from 0.31 nmol/kg.day, by 34% (P = 0.046). In contrast, the mean fractional catabolic rates of apo(a) were similar, 0.36 vs. 0.31/day (P = 0.23). In 6 women, the kinetics of apo(a) and apoB100, the two major proteins of Lp(a), were studied during estrogen and placebo periods. During both periods, the rate of appearance of tracer was similar in Lp(a)-apo(a) and Lp(a)-apoB100, as were the resulting metabolic rates and the changes during estrogen treatment. In conclusion, the findings are more compatible with intracellular synthesis of Lp(a) from nascent apo(a) and apoB100 than extracellular assembly from plasma low-density lipoproteins. Reduced flux into plasma of Lp(a), an atherogenic lipoprotein, could contribute to the lower cardiovascular disease rates in women receiving estrogen replacement therapy.

Aged↗
PubMed1998

[Chemical pattern recognition of traditional Chinese medicine kudingcha (I)].

In this paper, the non-linear mapping method of pattern recognition was adopted to classify 78 samples of traditional Chinese medicine Kudingcha, with macro and trace elements as classified characteristic features. Ilex cornuta Lindl., Ilex latifolia Thunb. and Ligustrum lucidum Ait. were identified accurately. The results agree with those from pharmacognosy. This paper provides a new method for identification of traditional Chinese medicine.

Drugs, Chinese Herbal↗
PubMed1998

[Chemical pattern recognition of traditional Chinese medicine kudingcha (II)].

In this paper, the HPLC data from 78 samples of Kudingcha were treated with back propagation algorithm of artifical neural network pattern recognition, and the computer-aided classification of Ilex cornuta Lindl., Ilex latifolia Thunb. and Ligustrum lucidum Ait. was accomplished. This paper provides a scientific, advanced and feasible method for identification of traditional Chinese medicine.

Chromatography, High Pressure Liquid↗
PubMed1998

Serum leptin levels and energy expenditure in normal weight women.

To investigate whether circulating leptin levels are associated with energy expenditure in healthy humans, doubly labeled water energy measurements and food intake assessment were carried out in 27 women (mean age, 48.6 years; weight, 61.9 kg; body mass index, 23.2). Energy expenditure was determined over 13 days. Food intake was measured by 7-day food records. Leptin was measured by radioimmunoassay. Leptin level was strongly associated with percentage body fat (r = 0.59; p < 0.001), fat mass (r = 0.60; p < 0.001), and body mass index (r = 0.41; p = 0.03), but no correlation was observed with energy expenditure (r = 0.02; p = 0.93). After controlling for percentage body fat, a positive association of leptin level with energy expenditure of marginal significance (p = 0.06) was observed. There were no significant univariate associations of age, physical activity, lean body mass, height, or dietary variables with leptin level. When controlling for body fat, a significant positive correlation was observed for percent energy from carbohydrate and negative correlations with dietary fat and alcohol intake. These findings confirm previous associations between leptin and body fat content and suggest a relationship between serum leptin and energy expenditure level in healthy humans.

Body Weight↗