Biomedical subjects

W Tian

Publications and source records attributed to W Tian.

At least 37 records · Page 2Linked to original sources

PubMed2001

Complexation of trivalent lanthanide cations by galactitol in the solid state. The crystal structure and an FT-IR study of 2NdCl3.galactitol.14H2O.

The crystal structure of 2NdCl3.galactitol.14H2O has been determined. The crystal system is triclinic, space group: -1, with unit-cell dimensions: a = 9.736(2), b = 10.396, c = 8.027 A; alpha = 108.05(3), beta = 92.68(3), gamma = 88.44(3) degrees, V= 771.6(3) A3, Z = 2. Each Nd atom is coordinated to nine oxygen atoms, three from the alditol and six from water molecules, with Nd-O distances from 2.461 to 2.552 A. The seventh water molecule is hydrogen-bonded by the hydroxyl hydrogen on O-1 (O-1-H-ll...O-10, 2.639 A). The FT-IR spectra of 2NdCl3.galactitol.14H2O and 2PrCl3.galactitol.14H2O are analogous, and show that Pr and Nd have the same coordination mode. The IR results are consistent with the crystal structures.

Carbohydrates↗

PubMed2001

Sugar interaction with metal ions. The crystal structure and Raman spectra study of SmCl3-galactitol complex.

The crystal structure of 2SmCl3.galactitol.14H2O has been determined. The crystal system is triclinic, space group: P-1. The unit cell dimensions: a = 9.683(2) A, b = 10.341(2) A, c = 7.990(2) A; alpha = 108.01(3) degrees, beta = 92.71(3) degrees, gamma = 88.42(3) degrees. Each Sm atom is coordinated to nine oxygen atoms, three from the alditol and six from water molecules, with Sm-O distance from 2.417 to 2.520 A. The seventh water molecule is hydrogen-bonded by the hydroxy hydrogen on O-3 (O(3)-H(13)...O(10), 2.635 A). After forming complexes the peaks have shifted and the relative intensities have changed in the IR and Raman spectra, which are corresponding to the changes in bond distances and bond angles of the structures. The IR and Raman spectra of Pr-, Nd- and Sm-galactitol complexes are similar, which show that the three metal ions have the same coordination mode.

Crystallography, X-Ray↗

PubMed2001

Signaling and gene regulation by urea in cells of the mammalian kidney medulla.

Signaling by urea, although incompletely understood, is relevant both to cells of the mammalian kidney inner medulla and to all cells of the organism in the setting of advanced renal failure with its attendant accumulation of urea in the systemic circulation. The molecular events initiated by urea stress are distinct from those occurring in response to hypertonic stress; urea activates a characteristic subset of signaling events, which are in large part specific to cultured renal tubular epithelial cells. Interestingly, urea is protective of hypertonic NaCl-inducible apoptosis in this model. Details of this phenomenon are reviewed. The effect of urea has been likened to that of either hypertonicity or of a peptide mitogen. In preliminary expression array analyses, the profile of genes activated by urea stress in renal medullary cells, however, was found to be unique.

Animals↗

PubMed2001

Urea and hypertonicity increase expression of heme oxygenase-1 in murine renal medullary cells.

Epithelial cells derived from the mammalian kidney medulla are responsive to urea at the levels of signal transduction and gene regulation. Hybridization of RNA harvested from control- and urea-treated murine inner medullary collecting duct (mIMCD3) cells with a cDNA expression array encoding stress-responsive genes suggested that heme oxygenase (HO)-1 mRNA was upregulated by urea. RNase protection assay confirmed this upregulation; hypertonicity also increased HO-1 mRNA expression but neither hypertonic NaCl nor urea were effective in the nonrenal 3T3 cell line. The effect on HO-1 expression appeared to be transcriptionally mediated on the basis of mRNA half-life studies and reporter gene analyses using the promoters of both human and chicken HO-1. Although urea signaling resembles that of heavy metal signaling in other contexts, the effect of urea on HO-1 transcription was independent of the cadmium response element in this promoter. Urea-inducible HO-1 expression was sensitive to antioxidants but not to scavengers of nitric oxide. Urea also upregulated HO-1 protein expression and pharmacological inhibition of HO-1 action with zinc protoporphyrin-sensitized mIMCD3 cells to the adverse effects of hypertonicity but not to urea. Coupled with the prior observation of others that HO-1 expression increases along the renal corticomedullary gradient, these data suggest that HO-1 expression may comprise an element of the adaptive response to hypertonicity and/or urea in renal epithelial cells.

3T3 Cells↗

PubMed2001

Urea inhibits hypertonicity-inducible TonEBP expression and action.

Tonicity-responsive genes are regulated by the TonE enhancer element and the tonicity-responsive enhancer binding protein (TonEBP) transcription factor with which it interacts. Urea, a permeant solute coexistent with hypertonic NaCl in the mammalian renal medulla, activates a characteristic set of signaling events that may serve to counteract the effects of NaCl in some contexts. Urea inhibited the ability of hypertonic stressors to increase expression of TonEBP mRNA and also inhibited tonicity-inducible TonE-dependent reporter gene activity. The permeant solute glycerol failed to reproduce these effects, as did cell activators including peptide mitogens and phorbol ester. The inhibitory effect of urea was evident as late as 2 h after the application of hypertonicity. Pharmacological inhibitors of known urea-inducible signaling pathways failed to abolish the inhibitory effect of urea. TonEBP action is incompletely understood, but evidence supports a role for proteasome function and p38 action in regulation; urea failed to inhibit proteasome function or p38 signaling in response to hypertonicity. Consistent with its effect on TonEBP expression and action, urea pretreatment inhibited the effect of hypertonicity on expression of the physiological effector gene, aldose reductase. Taken together, these data 1) define a molecular mechanism of urea-mediated inhibition of tonicity-dependent signaling, and 2) underscore a role for TonEBP abundance in regulating TonE-mediated gene transcription.

Aldehyde Reductase↗

PubMed2001

[Effects of IL-8 on neutrophils under fluid shear].

OBJECTIVE: In order to elucidate the effect of IL-8 on neutrophils in a systematic and all-round way, we introduced an important physiological environment of neutrophils, fluid flow, into this study on the changes in some responses of neutrophils to IL-8 and the inter relationship of those responses under the conditions of different patterns of flow field. METHODS: After using IL-8 and steady flow or sinusoidal-oscillate fluid shear rate simultaneously acting on separated neutrophils for one minute, we measured the expression of CD18, CD62L and the F-actin content with flow cytometry and measured the free calcium concentration inside cells ([Ca2+]i) with the fluorescent stain Fura2/AM using the fluorescent spectrophotometer. RESULTS: It was found that flow shear stress could influence the expression of surface adherence molecule of neutrophils under the action of IL-8. CD18 surface expression increased, and CD62L shed under different flow shear rates, but no significant relationship of these changes with the intensity and pattern of shear stress was noted. On the other hand, the F-actin content in neutrophils under the action of shear stress and IL-8 decreased significantly at low shear rate and then gradually increased at high shear rate (600s -1) to the control value (without shear). The [Ca2+]i concentration under the action of shear stress and IL-8 decreased significantly at low shear rate followed by a quick increase at high shear rate. CONCLUSION: The flow shear stress can influence the activation effects of IL-8 on neutrophils and regulate the magnitude of neutrophil reactions to a great extent, and among these reactions, the change of [Ca2+]i concentration is the most sensitive one and the greatest one. This is in consistence with its second messenger role in the signal transduction pathway. Our results could serve as a basis on which to understand better the mechanism of inflammatory reaction wherein the neutrophils under flow condition of blood are involved.

Actins↗

PubMed2001

[Effects of fluid shear stress on PGE2 synthesis of primary osteoblast-like cells in rats].

OBJECTIVE: The purpose of this study is to study the function of PGE2 during the signal transduction in which fluid shear stress regulates the proliferation and differentiation of osteoblast-like cells. METHODS: The isolated rat primary osteoblast-like cells were exposed to fluid shear stress 0.12 mN/cm2 for 5, 10, 15, 30, 60 and 120 minutes respectively in a flow chamber. The release of PGE2 was examined. RESULTS: After exposure to fluid shear stress, the PGE2 synthesis of rat primary osteoblast-like cells increased significantly (P < 0.01) when compared with the control. After 10 minutes, the release of PGE2 began to increase significantly (P < 0.01) and the effect was maximal after 60 minutes (P < 0.01). CONCLUSION: PGE2 pathway may be one of the signal-transduction pathways which can transduce the fluid shear stress into osteoblast-like cells and then stimulate the bone remodeling.

Animals↗

PubMed2001

[Preliminary study of closing cleft of soft palate at an early age for complete cleft palate].

OBJECTIVE: The aim is to introduce the method closing the soft palate at an early age in order to produce better speech and lessen interruption to the development of maxilla. METHODS: Clinical data of 37 cases with treated cleft were preliminarily analyzed. Some dental casts were measured. RESULTS: 1. No complications of anaesthesia and surgery. Except 2 cases whose soft palates were split after surgery were observed as they were coughing. 2. A reduction in the width of the hard palate cleft was noticed. CONCLUSION: Closing the soft palate at an early age is possible and safe. It shows that the Langebeck method could be used to close the hard palate of patients at an early age.

Child, Preschool↗

PubMed2001

[A study on mRNA expression levels of integrin beta 1 during the healing process of mandibular fractures].

OBJECTIVE: The aim of this study was to investigate the spatial and temporal mRNA expression changes of integrin beta 1 during the healing process of mandibular fractures. METHODS: The in situ hybridization was performed using digoxigenin-labeled integrin beta 1 mRNA oligonucleotide probe. During the healing process of mandibular fractures, the staining pattern of beta 1 mRNA was examined both spatially and time-dependently. RESULTS: Integrin beta 1 was widely present in the cells of the fractured bone, especially in osteoblasts. The positive staining was observed in the cytoplasm and nucleolus of osteoblasts. After 7 days of fracture, the expression level of integrin beta 1 increased. The peak appeared between the 14th and the 30th day, and almost recovered to normal between the 60th and 90th day. CONCLUSION: During the healing process of mandibular fracture, the expression level of integrin beta 1 in bone, especially in osteoblasts rose. It is suggested that integrin beta 1 may play an important role in the fracture healing process.

Animals↗

PubMed2001

[Expression of bone morphogenetic protein (BMP)-2, 4 in mouse embryonic tooth during the bud stage].

OBJECTIVE: The purpose of this paper was to investigate the distributions of bone morphogenic protein (BMP)-2, 4 in the developing molars of mice during the bud stage and, the functional relationship between BMP-2 and BMP-4. METHODS: The distribution of BMP-2, 4 were examined in developing mouse molars on the 14th (the 14th embryonic day), using monoclonal antibodies and immunohistochemistry methods. RESULTS: BMP-2, 4 were detected both in the epithelial cells and dental mesenchyme cells. CONCLUSION: There is a similar distribution pattern between BMP-2 and BMP-4. Therefore, there may be a functional relationship between BMP-2 and BMP-4 during the development of mouse embryonic teeth in the bud stage.

Animals↗

PubMed2001

[The effect of fluid shear stress on the proliferation of rat primary osteoblast-like cells in vitro].

OBJECTIVE: To inquire into the cellular mechanism by which mechanical stress regulates bone remodeling and make an attempt at establishing the most suitable physiological stress to stimulate bone formation. METHODS: The isolated rat primary osteoblast-like cells were exposed to fluid shear stress 2, 4, 8, 12, 14, 17 and 19 dyn/cm2 for 60 min respectively in the flow chamber. The ability of proliferation of cells was studied by flow cytometry. RESULTS: After exposed to fluid shear stress, the cells rearranged and the cells' axes were elongated following the flow direction. The proliferation indexes (PI) of the cells went up with the gradual increase of shear stress. When fluid stress reached 12 dyn/cm2, the PI of cells increased significantly (P < 0.05), compared with the control. But the PI of cells began to decrease when the fluid stress continued to increase, and when fluid stress reached 14 dyn/cm2, the PI of cells decreased significantly (P < 0.01), compared with the control. CONCLUSION: The mechanism by which mechanical stress regulates bone remodeling is related to the proliferation of the osteoblast cells stimulated by stress-induced fluid flow. Low shear stress has no marked influence on the proliferation of cells. Medium shear stress (12 dyn/cm2) can stimulate cells significantly. Major shear stress (14 dyn/cm2) can inhibit cells significantly.

Animals↗

PubMed2001

[Growth and osteogenesis characteristics of cultured rat marrow stromal cells under bone induction condition].

OBJECTIVE: To investigate the growth and osteogenesis characteristics of cultured rat marrow stromal cells(rMSCs) under bone induction condition. METHODS: rMSCs were isolated from adult rat using density gradient separation method. The rMSCs attachment formed soon after seeding and grew into colonies with the appearance of fibroblastic cells. The osteogenic induction compound of Dex(10(-8) mol/L), beta-GP(10 mmol/L) and AA(50 micrograms/ml) was added to different passaged rMSCs and the proliferation and osteogenic differentiation of them was observed. RESULTS: The induction compound had strong effect on promoting proliferation, especially on that of further passaged rMSCs, and its stimulation effect on osteogenesis was also well proved with the expression of alkaline phosphatase (ALP) rising after one-week induction. Further subculturing from P1 to P6 led to the increase of proliferation activity of rMSCs. After three-week induction, mineral deposits appeared in the culture. CONCLUSION: The lower expression of ALP in P1 rMSCs and the increase of it in further passages or under induction condition suggest the rMSCs in our culture system are mainly undifferentiated osteoprogenitors.

Alkaline Phosphatase↗

PubMed2001

[Effects of estradiol and isoflavoid on the expression of adhesion molecules on neutrophils].

OBJECTIVE: To elucidate the effects of estradiol and isoflavoid on the expression of adhesion molecules on neutrophils. METHODS: Neutrophils of healthy subjects and ischemic stroke patients were treated with tumor necrosis factor alpha (TNF alpha), in the presence or absence of different concentrations of isoflavoid (WZ1, WZ2) and estradiol (WZ3, WZ4). Flow cytometry was used to detect the expression of CD18 and CD62L on neutrophil surface. RESULTS: 1. 10 ng/ml TNF alpha could activate neutrophils of healthy subjects; it increased the expression of CD18 by 10% on neutrophil surface and shed CD62L from the surface as shown by a 15% decrease of the fluorescence intensity and a 30% decrease of the percentage of positive cell. 2. Isoflavoid (WZ1, WZ2) had no significant effect on the expression of CD18 and CD62L on neutrophils. 3. Pretreatment of neutrophils with estradiol (WZ3, WZ4) could inhibit the activation of neutrophils by TNF alpha, which decreased the fluorescence intensity of CD18 by 8%, increased the fluorescence intensity of CD62L by 15% and increased the percentage of CD62L positive cell by 20%. 4. TNF alpha could activate the neutrophils of ischemic stroke patients strikingly; it increased the fluorescence intensity of CD18 by 20% and decreased the fluorescence intensity and percentage of positive cell of CD62L by 30%, and there was a significant difference when the patients were compared with the healthy subjects. Estradiol had the same effect on the expression of CD18 and CD62L as on those of healthy subjects. CONCLUSION: 1. TNF alpha is a strong activator of neutrophils; it plays an important role in the occurrence and development of ischemic stroke. 2. Isoflavoid has no obvious effect on the expression of adhesion molecules on neutrophils, so its role in protecting the cardiovascular system may come into play not by the way of affecting adhesion molecules expression. 3. Pretreatment of neutrophils with estradiol could protect them from activation by TNF alpha, thus decreasing the expression of adhesion molecules, the adhesion of neutrophils -endothelial cells, and hence the risk of ischemic stroke. However, in case that the neutrophils have been activated by TNF alpha, estradiol has no effect on the expression of adhesion molecules; this implies that estradiol possibly has no valid anti-adhesion therapeutic effect on ischemic stroke.

Adult↗

PubMed2000

Complexation of trivalent lanthanide cations by inositols in the solid state: crystal structure and an FT-IR study of PrCl3.myo-inositol.9 H2O.

The title compound, PrCl3.C6H12O6.9 H2O crystallized in the monoclinic space group P2(1)/n with cell dimensions a = 15.8293(3), b = 8.67750(10), c = 16.2292(3) A, beta = 107.0788(8) degrees, V = 2130.92(6) A3 and Z = 4. Each Pr ion is coordinated to nine oxygen atoms, two from the inositol and seven from water molecules, with Pr-O distances from 2.4729 to 2.6899 A; the other two water molecules are hydrogen-bonded. No direct contacts exist between Pr and Cl. There is an extensive network of hydrogen bonds formed by hydroxyl groups, water molecules, and chloride ions. The IR spectra of Pr-, Nd-, and Sm-inositol complexes are similar, which shows that the three metal ions have the same coordination mode. The IR results are consistent with the crystal structure.

Crystallization↗

PubMed2000

[Allelic polymorphism of HLA-DQA1 locus in Han nationality in Hunan province].

OBJECTIVE: To explore the genetic polymorphism of HLA-DQA1 locus in Han nationality in Hunan province. METHOD: Sixty samples randomly selected from healthy individuals of Han nationality in Hunan province were typed for HLA-DQA1 by PCR/SSP in combination with silver-staining PCR/SSCP. RESULTS: Ten types of HLA-DQA1 alleles were found in all 60 samples, HLA-DQA1*0302, *0501, *0102 were the common alleles with gene frequencies of 0.2254, 0.2254, and 0.2041 respectively. Twenty-six kinds of genotypes were found, and the genotype distribution fitted the Hardy-Weinberg equilibrium test (P > 0.05). Five samples which had ambiguity in their PCR/SSP typing were further clarified with PCR/SSCP analysis. CONCLUSIONS: Normal gene frequency values of HLA-DQA1 alleles in Han nationality in Hunan province are provided; PCR/SSCP can be used to eliminate the ambiguity which might exist in PCR/SSP typing for HLA-DQA1 locus.

Alleles↗

PubMed2000

[Correlative study on HLA-DR2 allelic polymorphism and systemic lupus erythematosus in the Han nationality in Hunan province].

Fifty-eight systemic lupus erythematosus (SLE) patients and 59 normal controls of the Han nationality in Hunan province were involved in this study to analyze the correlation between HLA-DR2 group specific amplification in combination with HLA-DRB generic amplification PCR/SSCP technique to detect the sequence variation within exon 2 of HLA-DR2 alleles outside the sequence specific primer matching positions. The results were that HLA-DR2 was strongly correlated with SLE (RR = 2.71, P < 0.01); and HLA-DRB1 * 1501 was the allele correlated with disease (RR = 3.01, Pc < 0.05). In addition, PCR/SSCP showed that there was not any novel sequence variation in exon 2 of HLA-DR2 alleles in the Han nationality in Hunan province.

Alleles↗

PubMed2000

Sugar interaction with metal ions. FT-IR study on the structure of crystalline galactaric acid and its K+, NH4+, Ca2+, Ba2+, and La3+ complexes.

The FT-IR spectra of galactaric acid and its K+, NH4+, Ca2+, Ba2+, and La3+ salts have been recorded and interpreted. Spectroscopic evidence shows that the dimeric carboxylic groups of the free acid are dissociated upon formation of the salt, and the asymmetric and symmetric stretching vibrations of the anionic COO- group in these salts are observed at about 1600 and 1400 cm-1, respectively. The two carboxylic groups of the galactarate coordinate with Ca2+ ions in a monodentate form. One of the carboxylic groups in the Ba2+ salt coordinates in a monodentate state; another group interacts with three cations in a tetradentate form. In the K+, NH4+, and La3+ salts, the COO- groups coordinate in a polydentate manner with the cations. By comparison of the spectra of the salts with that of the free acid, it is concluded that the hydroxyl groups of the galactarate skeleton take part in metal-oxygen interaction, and the hydrogen-bonding network is rearranged upon sugar metalation. The degree of participation of the sugar OH groups in metal-galactarate interaction is varied from the K+ and NH4+ salts to the Ca2+, Ba2+, and La3+ salts.

Barium↗

PubMed2000

Sugar interaction with metal ions. Crystal structure and FT-IR spectroscopic study of strontium galactarate mono-hydrate.

The crystal structure of strontium galactarate mono-hydrate, Sr2+ x C6H8O8(2-) x H2O, Mr = 313.76, monoclinic, P2(1)/c, a = 10.268(2), b = 10.333(2), c = 10.194(2) A, beta = 117.87(3) degrees, lambda(Mo K alpha) = 0.71073 A, Z = 4, Dx = 2.180 Mg m(-3), V = 956.1(3) A3, mu = 5.676 mm(-1), F(000) = 624, T = 293(2) K, R = 0.0260 for 1690 observed reflections and 145 parameters refined, has been determined. The galactarate ion is centro-symmetrical in the crystal structure, although it contains independent half-ions. The Sr2+ ion is nine-coordinated (tricapped trigonal prism) with five Sr-O bonds from carboxylic groups, and four from hydroxyl groups. The water molecule does not take part in the coordination. Six hydrogen bonds are formed, three of them related to the water molecule. The spectroscopic evidence shows that the carboxylic acid dimers of the free acid dissociate. The asymmetric stretching vibrations of the anionic COO groups in the salt are observed at 1609 and 1548, and 1581 cm(-1), assigned to a mono-dentate and a tetra-dentate coordination, respectively. The symmetric stretching vibration is located at 1397 cm(-1). The hydroxyl groups of the galactarate skeleton take part in the metal-oxygen interaction, and the hydrogen-bonding network is rearranged upon sugar metalation.

Carbohydrates↗