Biomedical subjects

Y Tian

Publications and source records attributed to Y Tian.

At least 91 records · Page 5Linked to original sources

PubMed1999

[Selenoproteins in rat brain].

Male Wistar rats fed with diets containing eight different levels of selenium(Se). Six rats in each group were killed after 20 weeks to obtain brains. The other 105 rats in the Se depleted group were then divided into four groups randomly and fed with diets containing four different levels of Se. The rats in these four groups were then killed at different time points to observe the kinetic change of selenoproteins. The lowest dietary Se required for reaching the plateau of the activities of cellular glutathione peroxidase (cGPX), phospholipid hydroperoxide glutathione peroxidase (PHGPX) and type II deiodinase (ID II) were 0.05, 0.03 and 0.01 mg/kg respectively. The lowest dietary Se required for reaching normal expression of selenoprotein P and selenoprotein W were 0.01 and 0.05 mg/kg respectively. While the rats were restored Se from diets supplemented with Se, the expression of selenoprotein P and type II deiodinase were in preference to PHGPX and cGPX, and the later two parameters were in preference to selenoprotein W. The results suggested that the function of selenoprotein P and ID II in brain were more important than the other three selenoproteins.

Animals↗

PubMed1999

[Selenoproteins in rats with chronic selenium intoxication].

Weaning male Wistar rats were fed with a Torula-yeast based semisynthetic diet supplemented with Na2SeO3 to provide selenium (Se) 0.2 or 0.5 mg/kg (adequate Se or high Sediet) respectively for 20 weeks. By the end of experiment, rats were sacrificed and various tissue of rats were collected to determine the activities of Se-containing enzymes and the mRNAs level of selenoprotein P and selenoprotein W and Se concentration. Livers were examined for pathological changes. It was found that the gain of body weight of the high Se group was significantly lower than that of adequate Se group. Much more Se was accumulated in the tissue of high Se group. The activities of eGPX in plasma, cGPX in kidney, heart and testis, ID I in liver, kidney and thyroid and PHGPX in heart and testis in the high Se group were significantly lower than those in the adequate Se group. However, no specific pathological changes have been found in the liver of both groups. The results suggested that these enzymatic changes could be used as early biochemical parameters for chronic selenium intoxication.

Animals↗

PubMed1999

[Priority of selenium incorporation into selenoproteins during selenium depletion in rats].

Male weanling Wistar rats were fed with either a basal selenium deficient diet (a Torula yeast based semisynthetic diet, containing Se 0.01 mg/kg) or a selenium sufficient diet supplemented with Se as Na2SeO3 (containing Se 0.5 mg/kg). Rats were killed after different weeks(0,1,2,4,8,12,15,17,19,20 and 24 respectively). Their organs were taken to observe the kinetic change of selenium concentration, the activities of intracellular glutathione peroxidase (cGPX), extracellular glutathione peroxidase (eGPX), and phospholipid hydroperoxide glutathione peroxidase (PHGPX) in different organs. The results showed that selenium levels and the activities of selenoenzyme in testis and pituitary were more resistant to selenium deficiency than other organs. During selenium deficiency, the utilization of selenium by PHGPX and deiodinase was prior to eGPX and cGPX, which suggested that the function of PHGPX and deiodinase were more important than that of eGPX and cGPX.

Animals↗

PubMed1999

Ah receptor and NF-kappaB interactions, a potential mechanism for dioxin toxicity.

The Ah receptor (AhR) mediates many of the toxic responses induced by polyhalogenated and polycyclic hydrocarbons (PAHs) which are ubiquitous environmental contaminants causing toxic responses in human and wildlife. NF-kappaB is a pleiotropic transcription factor controlling many physiological functions adversely affected by PAHs, including immune suppression, thymus involution, hyperkeratosis, and carcinogenesis. Here, we show physical interaction and mutual functional repression between AhR and NF-kappaB. This mutual repression may provide an underlying mechanism for many hitherto poorly understood PAH-induced toxic responses, and may also provide a mechanistic explanation for alteration of xenobiotic metabolism by cytokines and compounds that regulate NF-kappaB.

Animals↗

PubMed1999

Real-time dissolution measurement of sized and unsized calcium phosphate glass fibers.

The objective of this study was to develop an efficient "real time" measurement system able to directly measure, with microgram resolution, the dissolution rate of absorbable glass fibers, and utilize the system to evaluate the effectiveness of silane-based sizing as a means to delay the fiber dissolution process. The absorbable glass fiber used was calcium phosphate (CaP), with tetramethoxysilane selected as the sizing agent. E-glass fiber was used as a relatively nondegrading control. Both the unsized-CaP and sized-CaP degraded linearly at both the 37 degrees C and 60 degrees C test temperature levels used. No significant decrease in weight-loss rate was recorded when the CaP fiber tows were pretreated, using conventional application methods, with the tetramethoxysilane sizing for either temperature condition. The unsized-CaP and sized-CaP weight loss rates were each significantly higher at 60 than at 37 degrees C (both p < 0.02), as expected from dissolution kinetics. In terms of actual weight loss rate measured using our system for phosphate glass fiber, the unsized-CaP fiber we studied dissolved at a rate of 10.90 x 10(-09) and 41.20 x 10(-09) g/min-cm(2) at 37 degrees C and 60 degrees C, respectively. Considering performance validation of the developed system, the slope of the weight loss vs. time plot for the tested E-glass fiber was not significantly different compared to a slope equal to zero for both test temperatures.

Calcium Phosphates↗

PubMed1999

Preparation of adriamycin magnetic albumin microspheres and their experimental antitumor effects in vitro and in vivo.

The adriamycin magnetic microspheres (ADM-MAMs) were prepared by the heat-stabilized protein methods. Their physico-chemical properties were examined; their cytotoxicities against tumor cells in vitro were assayed by a modified MTT method, and their effects were observed on the implanted gastric tumor in Wistar rats given ADM-MAMs via alimentary canal at the presence of the external magnetic fields. The results showed that the ADM-MAMs were successfully prepared and had cytotoxic effect on tumor cells in vitro similar to the free ADM (P > 0.05). The inhibitory effects of ADM-MAMs on the implanted gastric tumor in vivo were significantly increased as compared with the controls (P < 0.01). Our results suggested that ADM-MAMs were a new type of adriamycin (ADM) preparation and its form alteration did not affect its anticancer effects.

Animals↗

PubMed1999

DNA damage effects of hydroxyapatite ultrofine powder on W-256 sarcoma cells and lymphocytes in rats.

To explore the anticancer mechanism and DNA damages of hydroxyapatite ultrofine powder (HAUFP) on lymphocytes of rats, DNA damages in W-256 sarcoma cells and lymphocytes of rats were measured by single cell gel electrophoresis (SCGE). The results showed that HAUFP damaged DNA of W-256 sarcoma cells obviously but only cause slight damage of DNA of lymphocytes in rats. It is suggested that HAUFP selectively damaged DNA of tumor cells with only mild damage of lymphocyte DNA. HAUFP has powerful anticancer effect and little genetic toxicity.

Animals↗

PubMed1999

The effect of locally implanted complexes of adriamycin-hydroxyapatite complexes on tumor--study of a new alternative treatment for hepatic cancer.

A new targeting anticancer system was prepared by using hydroxyapatite particles (2 mm in diameter) as carrier material and adriamycin as anticancer agent. The adsorption and release properties of the complexes were assayed by fluorometry in vivo and in vitro and the curative effect on W-256 sarcoma of rat was observed. The results showed that one particle of hydroxyapatite could adsorb approximately 0.08 mg adriamycin and they can maintain a steady and slow release of adriamycin from hydroxyapatite for one month. When hydroxyapatite-adriamycin complexes were implanted into the liver of rat, liver adriamycin concentration at the implanted region was obviously higher than that achieved by injection of adriamycin solution. The locally implanted complexes obviously inhibited the growth of subcutaneous implanted tumor of rat, and increased the survival rate of rat with implanted liver tumor.

Animals↗

PubMed1999

DNA content in pancreatic exocrinal cells after vagotomy and electron microscopy in rats.

Fifty-six SD rats were randomly divided into the normal control group and the operation group. The operating group was subdivided into six groups on the basis of killing time (the 12th h, the first day, 3rd day, first week, 2nd week and 4th week) after vagotomy (VG). The pancreatic tissues were taken for HE and Feulgen staining. The DNA content of pancreatic exocrine cells was determined by a domestically-fabricated computer image analyzing system. In the control group, on the first day or in the first week after VG, the pancreatic samples were taken for transmission electron microscopic examination. The DNA content of pancreatic exocrinal cells was decreased from 1 to 3 days after VG. The secretion was found to be in inhibitory state and One week later, it gradually restored. The results indicated that the proliferation and the function of the SD rat's pancreatic exocrinal cells were prohibited at initial stage after VG, which might be concerned, at least in part, with dominance and nutrition of vagus.

Animals↗

PubMed1999

Enlargement of atrophy and visual acuity loss in the geographic atrophy form of age-related macular degeneration.

OBJECTIVE: To describe the progression of geographic atrophy (GA) from age-related macular degeneration (AMD) with respect to visual acuity (VA) loss and enlargement of atrophy. DESIGN: A prospectively observed case series. SETTING: Tertiary retinal referral center. PARTICIPANTS: One hundred twenty-three patients with GA due to AMD who completed at least 1 year of follow-up (median follow-up, 3 years) were examined annually. METHODS: At each examination, a protocol best-corrected VA of each eye was measured, a clinical examination was performed, and color fundus photographs were taken. The areas of atrophy were drawn and measured. MAIN OUTCOME MEASURES: Visual acuity loss and enlargement of total and central atrophy. RESULTS: At baseline, median VA was poorer with larger areas of atrophy, but there was wide variation related to sparing of the fovea. Thirty-one percent of all study eyes suffered a three-line VA loss from baseline by 2 years, and 53% had a three-line loss by 4 years. Those eyes with VA better than 20/50 had the highest rate of acuity loss; 27% of these eyes had acuities of 20/200 or worse at 4 years. Visual acuity loss in the GA study eye was similar in patients with bilateral GA and in those with choroidal neovascularization in the fellow eye. Total atrophy enlarged a median of 1.8 Macular Photocoagulation Study disc areas (DA) at 2 years; atrophy within a 4-DA circle centered on the fovea enlarged a median of 0.9 DA. Two (22%) of nine patients with GA in one eye and only drusen without advanced AMD in the fellow eye developed GA in the fellow eye at 2 years. CONCLUSIONS: Geographic atrophy is associated with a significant decline in VA over time in many eyes. Areas of atrophy continue to enlarge over time, even when already large at baseline. The combination of reduced VA with enlargement of atrophy, occurring bilaterally in most patients, can lead to significant impairment of visual function.

Aged↗

PubMed1999

Cytokine and S100B levels in paediatric patients undergoing corrective cardiac surgery with or without total circulatory arrest.

OBJECTIVES: Neurological damage following cardiopulmonary bypass (CPB) is difficult to objectively evaluate in infants. In adults, serum elevations of astroglial S100B correlate with proven brain injury independent of operative temperature. The deleterious effects of inflammatory cytokines, generated during CPB, on the brain have not been studied in infants using S100B as a marker for cerebral injury. METHODS: Twelve neonates, weighing 3.3 +/- 0.2 kg (total circulatory arrest group (TCA)) and 12 infants weighing 7.0 +/- 1.0 kg (cardiopulmonary bypass group (CPB)) underwent corrective cardiac surgery for various pathologies. Serial blood samples on induction, at the end of CPB, 30 min, 2 h and 24 h after the administration of protamine, were taken. The resultant plasma was frozen to -80 degrees C and stored for batch analysis. Cytokines were measured using ELISAs and S100B using a luminometric assay. RESULTS: The TCA group were younger and experienced a longer perfusion time than the CPB group (137 +/- 8 vs. 113 +/- 7, P = 0.04). The mean TCA time was 23 +/- 4 min. The TCA group had significantly higher levels of IL-6 (P = 0.001), IL-8 (P = 0.005) and S100B (P = 0.002) at 24 h. C5b-9 levels were significantly lower in the TCA group: end of CPB (P = 0.001), 30 min (P < 0.001), 2 h (P = 0.002). There was a weak, but significant correlation between IL-6 levels at the end of CPB and S100B levels 2 h later (r = 0.55, P = 0.03). Long extubation times were associated with high 24-h S100B levels (r = 0.52, P = 0.01). CONCLUSIONS: (1) The TCA group have prolonged rises of IL-6, IL-8 and S100B. (2) The TCA group generates significantly lower complement. (3) Astroglial injury, seen after surgery, may, in part, be cytokine mediated.

Antibodies, Monoclonal↗

PubMed1999

SAG, a novel zinc RING finger protein that protects cells from apoptosis induced by redox agents.

SAG (sensitive to apoptosis gene) was cloned as an inducible gene by 1,10-phenanthroline (OP), a redox-sensitive compound and an apoptosis inducer. SAG encodes a novel zinc RING finger protein that consists of 113 amino acids with a calculated molecular mass of 12.6 kDa. SAG is highly conserved during evolution, with identities of 70% between human and Caenorhabditis elegans sequences and 55% between human and yeast sequences. In human tissues, SAG is ubiquitously expressed at high levels in skeletal muscles, heart, and testis. SAG is localized in both the cytoplasm and the nucleus of cells, and its gene was mapped to chromosome 3q22-24. Bacterially expressed and purified human SAG binds to zinc and copper metal ions and prevents lipid peroxidation induced by copper or a free radical generator. When overexpressed in several human cell lines, SAG protects cells from apoptosis induced by redox agents (the metal chelator OP and zinc or copper metal ions). Mechanistically, SAG appears to inhibit and/or delay metal ion-induced cytochrome c release and caspase activation. Thus, SAG is a cellular protective molecule that appears to act as an antioxidant to inhibit apoptosis induced by metal ions and reactive oxygen species.

Amino Acid Sequence↗

PubMed1999

Role of membrane-type matrix metalloproteinase 1 (MT-1-MMP), MMP-2, and its inhibitor in nephrogenesis.

Extracellular matrix (ECM) proteins, their integrin receptors, and matrix metalloproteinases (MMPs), the ECM-degrading enzymes, are believed to be involved in various biological processes, including embryogenesis. In the present study, we investigated the role of membrane type MMP, MT-1-MMP, an activator pro-MMP-2, in metanephric development. Also, its relationship with MMP-2 and its inhibitor, TIMP-2, was studied. Since mRNAs of MT-1-MMP and MMP-2 are respectively expressed in the ureteric bud epithelia and mesenchyme, they are ideally suited for juxtacrine/paracrine interactions during renal development. Northern blot analyses revealed a single approximately 4.5-kb mRNA transcript of MT-1-MMP, and its expression was developmentally regulated. Inclusion of MT-1-MMP antisense oligodeoxynucleotide (ODN) in the culture media induced dysmorphogenetic changes in the embryonic metanephros. MMP-2 antisense ODN also induced similar changes, but they were relatively less; on the other hand TIMP-2 antisense ODN induced a mild increase in the size of explants. Concomitant exposure of MT-1-MMP and MMP-2 antisense ODNs induced profound alterations in the metanephroi. Treatment of TIMP-2 antisense ODN to metanephroi exposed to MT-1-MMP/MMP-2 antisense notably restored the morphology of the explants. Specificity of the MT-1-MMP antisense ODN was reflected in the selective decrease in its mRNA and protein expression. The MT-1-MMP antisense ODN also resulted in a failure in the activation of pro-MMP-2 to MMP-2. These findings suggest that the trimacromolecular complex of MT-1-MMP:MMP-2:TIMP-2 modulates the organogenesis of the metanephros, conceivably by mediating paracrine/juxtacrine epithelial:mesenchymal interactions.

Aging↗

PubMed1999

Kidney aquaporin-2 expression during escape from antidiuresis is not related to plasma or tissue osmolality.

Recent results indicate that renal escape from vasopressin-induced antidiuresis is accompanied by a marked downregulation of whole kidney aquaporin-2 (AQP-2) protein and mRNA expression. However, in those studies, the escaped animals were also markedly hypo-osmolar compared to controls as a result of water loading during antidiuresis. The present studies evaluated whether systemic or local osmolality contributes to the downregulation of AQP-2 expression in this model. In the first study, two groups of 1-deamino-[8-D-arginine]-vasopressin (dDAVP)-infused rats were water-loaded; after establishment of escape, one group was then water-restricted for 4 d to reverse the escape, whereas the other group continued daily water loading. Whole kidney AQP-2 protein was measured by Western blotting, and inner medulla AQP-2 mRNA was determined by Northern blotting. Results were compared to dDAVP-infused rats fed solid chow. After 4 d of water restriction, urine volume decreased to the same level as in the rats on solid chow; however, plasma sodium concentrations and plasma osmolality remained low. Despite maintenance of significant hypo-osmolality, rats in which escape was subsequently reversed by water restriction reestablished high dDAVP-stimulated kidney levels of AQP-2 after 4 d of water restriction. In the second study, AQP-2 expression was evaluated in different regions of kidneys from water-loaded rats undergoing escape from antidiuresis. Despite markedly different interstitial osmolalities, significant downregulation of AQP-2 expression compared to dDAVP-infused control rats was seen in the inner medulla, outer medulla, and cortex. Thus, neither systemic nor interstitial osmolality appears to appreciably be correlated with downregulation of kidney AQP-2 expression during escape from antidiuresis. These results therefore suggest that additional vasopressin- and osmolality-independent factors, likely related to the effects of extracellular fluid volume expansion, also regulate kidney AQP-2 expression in rats.

Analysis of Variance↗

PubMed1999

Measuring geographic atrophy in advanced age-related macular degeneration.

PURPOSE: To present a method developed for measuring areas of geographic atrophy (GA) in advanced age-related macular degeneration, METHODS: A microfilm reader projected the 30 degrees fundus photograph of the macula. Retinal landmarks, atrophic areas, and spared areas within the atrophy were traced, without access to drawings of other years. The total atrophic area was calculated, as was the atrophy within a four-disc-area circle entered on the estimated foveal center. The configuration of the atrophy was documented. RESULTS: Avoidable sources of discrepancy included variability in peripapillary atrophy seen on the photograph, and variability seen in the extent of the field. Reproducibility studies found a median absolute difference of 0.19 Macular Photocoagulation Study disc areas (DA) in total atrophy between repeat drawings, with 75% of repeat drawings having a difference of less than 0.33 DA. For central atrophy measures, there was a median difference of 0.08 DA, with 75% of pairs having a difference of less than 0.18 DA. Features making the definition of borders of GA difficult include the presence of drusen and pigmentary alteration, a fundus in which choroidal vessels are easily visible, and variation in the appearance of GA within a single area of atrophy. CONCLUSIONS: This method provides a reliable means of measuring the size of atrophic areas in GA and will be useful for measuring longitudinal change. It may be difficult to determine whether central spared areas are present, and correlation with visual acuity and macular perimetry may be helpful.

Aged↗

PubMed1999

[The role of cytokeratin 13 gene in human nasopharyngeal carcinoma].

OBJECTIVE: To study the significance of cytokeratin 13 (CK13) gene expression and its methylation in human nasopharyngeal carcinoma (NPC). METHODS: The expression of CK13 in 32 cases of NPC and 8 cases of chronic inflammatory diseases of nasopharyngeal epithelia (CIDNE) was studied using Northern blot hybridization. The methylation pattern of CK13 gene was analyzed by Southern blot hybridization using methylation sensitive restriction endonuclease Hpa II and Msp I in NPC cell lines HNE1 and normal human primary cultures of nasopharyngeal epithelial cells. RESULTS: High expression of CK13 gene was found in 8(100%) CIDNE, low-expression of the gene in 12(37.5%) NPC, negative expression in 9(28.1%) and high expression in 11(34.4%). The degree of methylation was increased in NPC cell lines HNE1, compared to that of normal human primary cultures of nasopharyngeal epithelial cells. CONCLUSION: The expression of the CK13 gene in NPC is partly or completely down regulated. It is possibly related to hyper-methylation of CK13 gene.

Gene Expression Regulation, Neoplastic↗

PubMed1999

[Effect of total flavonoids of Astragalus on nitroxide in ischemia reperfusion injury].

OBJECTIVE: To study the protective effect of total flavonoids of Astragalus (TFA) on ischemia/reperfusion injury. METHODS: Change of nitrite (NO2-), the terminal product of nitric oxide (NO) metabolism, and the effect of TFA and chloroquine (a phospholipase A2 inhibitor) on it were observed with hemorrhagic shock/reperfusion injury (S/R) rabbit model. RESULTS: Plasma NO2- content was positively correlated with blood pH and total carbon dioxide content lowering. TFA and chloroquine could block the decrease of NO in certain degree and might have some effect on maintaining acid-base balance of body. CONCLUSION: TFA has protective effect on ischemia/reperfusion injury.

Animals↗

PubMed1999

[Clinical observation on treatment of bile regurgitational gastritis with danwei capsule].

OBJECTIVE: To evaluate the therpeutic effect of Danwei capsule in treating bile regurgitational gastritis. METHODS: One hundred and thirty-four patients with bile regurgitational gastritis were divided into two groups. Danwei capsule was used in therapeutic group and Motilium was used in control group. RESULTS: The total effective rate in therapeutic group was 92.59%, and 71.70% in control group (P < 0.01). The improvement in symptoms, physical findings and bile regurgitation in therapeutic group was better than that of control. CONCLUSION: Curative effect of Danwei capsule was better than that of Motilium, which should be used widely.

Adult↗