Biomedical subjects

J Tian

Publications and source records attributed to J Tian.

At least 55 records · Page 3Linked to original sources

PubMed2001

Regional glucose metabolic increases in left auditory cortex in tinnitus patients: a preliminary study with positron emission tomography.

OBJECTIVE: To investigate the relationship between tinnitus and glucose metabolism in auditory cortex and whether positron emission tomography (PET) can be an objective tool in measuring tinnitus. METHODS: Eleven right-handed patients with severe tinnitus and ten right-handed control subjects participated in the 18F-FDG/PET study. Analysis with regions of interests was used to calculate asymmetry indices according to the formula: [(L-R) x 100/[(L + R) divided by 2]]. RESULTS: Glucose metabolism in the auditory cortex of tinnitus patients was asymmetric between the left and right auditory cortices, with that of the left being much higher than that of the right. The asymmetry indices of tinnitus patients was significantly higher than that of the control group (unpaired t test, P < 0.001). This revealed that the increased metabolic activity was present in the predominant left hemisphere with a significant focus on the superior and transverse temporal gyri (Brodmann areas 41 and 42, respectively corresponding to primary and secondary auditory cortex), and the results were independent of the subjective localization of the tinnitus sensation. CONCLUSION: It is suggested that the increased metabolism in the left auditory cortex is related to the tinnitus sensation. PET is capable of providing objective evidence for tinnitus and may be used as a potential tool in measuring tinnitus.

Adolescent↗

PubMed2001

[Research on the matching between alumina-glass composite and Vita alpha veneering ceramic].

OBJECTIVE: To investigate the matching between self-made alumina-glass composite and Vita alpha veneering ceramic. METHODS: By using thermal shock test and SEM. RESULTS: The crazing resistance of alumina glass composite via Vita alpha ceramic expressed as the mean delta T was 170 degrees C. SEM micrograph indicate that Vita alpha ceramic fused to alumina glass composite, and no crack between the combination interface. CONCLUSION: Alumina-glass composite can match to the Vita alpha ceramic fairly.

Aluminum Oxide↗

PubMed2001

Alpha 1-antitrypsin and alpha 1-acid glycoprotein reduce the sensitivity of human dermal fibroblast to endotoxin.

OBJECTIVE: To test the hypothesis that acute phase reactants, such as alpha 1-antitrypsin and alpha 1-acid glycoprotein, could protect mammalian cells from further damage. METHODS: Human dermal fibroblasts (5 x 10(4)) were cultured with DMEM plus 10% FBS at 37 degrees C in a 5% CO(2) incubator. Different doses of LPS (lipo polysaccharide) and/or acute phase reactants were added. After 24 hours, the cultured supernatant was aspirated, the cells were washed, fixed and stained by methylene blue. The unbound stain was washed off. The stained cells were solubilize d in 0.1 ml of 1% Triton X-100. The absorbance of each well was measured us ing an ELISA spectrophotometer. The concentration of LPS which decreased the absorbance to 70% of the control (LPS-free) cultures was defined as LD(30). RESULTS: In order to achieve LD(30) in the presence of acute phase proteins, it was necessary to alter the LPS concentrations. The LD(3 0) of LPS treated with 0, 0.5, 2, 10 mg/ml antitrypsin and 0, 0.5, 2, 10 mg/ml glycoprotein was 5.4, 6.5, 7.6, 14.2 mg/ml and 5.2, 5.9, 6.9, 10.5 mg/ml, respectively. Statistically, with the treatment of more than 2 mg/ml antitrypsin or glycoprotein, LD(30) increased significantly. CONCLUSIONS: Our data show that fibroblasts are susceptible to the direct toxicity of LPS. Alpha 1-antitrypsin and alpha 1-acid glycoprotein can reduce the toxicity and/or increase the tolerance of mammalian cells to LP S.

Acute-Phase Reaction↗

PubMed2001

[A study on the myocardial contractile function and intracellular free calcium in scalded rats].

OBJECTIVE: To explore the relationship between postburn myocardial function and intracellular free calcium concentration. METHODS: Sprague-Dawley (SD) rats were employed as the model in which 7 were inflicted with 43% TBSA degree scalding (S group) and 7 as sham scalding control group (C group). The hearts of the injured rats were isolated and perfused in vitro by Langendorff method after 24 postburn hours (PBHs). The hearts were connected to a cardiac function monitor, and the dynamic changes in left ventricular develop pressure (LVDP) were continuously monitored. The cardiac 19F and 31P NMR spectroscopy was determined before and after and TF-BAPTA was added to the perfusate. RESULTS: When compared with those in C group, the LVDP of scalded rat heart decreased by 40% (P < 0.01), and the myocardial cytoplasmic free calcium concentration was four times above that in C group (P < 0.01). After TF-BAPTA was taken by myocytes, cardiac LVDP only decreased by 15% to 20%, and the PCr/Pi ratio decreased, while there was no change in ATP. CONCLUSION: Myocardial contractile function could be inhibited after burn injury, which might be related to the increase of myocardial cytoplasmic free calcium concentration.

Animals↗

PubMed2001

[Chemical constituents of Gymnotheca involucrata Pei].

OBJECTIVE: To study the chemical constituents of Gymnotheca involucrata. METHOD: Separating the constituents by means of chromatography and identifying their structures on the basis of NMR spectra and TLC with authentic samples. RESULT: From the methanolic extract of the whole plant of G. involucrata, three compounds were isolated and identified as kaempferol-4',7-dimethyl-3-O-glucoside, daucosterol and stigmasterol. CONCLUSION: All the three compounds were isolated from this genus for the first time.

Flavonoids↗

PubMed2001

[Research on the high strength all ceramic crown by the combination of CAD/CAM and glass infiltrated alumina blocks].

OBJECTIVE: To search for a method that fabricates the high strength all ceramic crown by the combination of CAD/CAM and glass-infiltrated alumina. METHODS: Alumina coping was milled by the Cerec II CAD/CAM and glass was infiltrated into alumina by the capillary effect. Vita alpha ceramic was used to veneer the surface of substructure for all ceramic crown. RESULTS: This technology need not duplicate die and sinter alumina substructure for 10 h, compared with the conventional In-ceram technology. The time of glass infiltration has been decreased from 4 h to 40 minutes by the high capillary effects of prefabricated alumina blocks. CONCLUSION: This is a new method for all ceramic crown by using Cerec II CAD/CAM to mill a simple ceramic block so as to fabricate prosthetics in clinic.

Aluminum Oxide↗

PubMed2001

[Determination of puerarin in three traditional Chinese patent medicines by high performance liquid chromatography].

A simple and accurate reversed-phase high performance liquid chromatographic method to determine puerarin in three traditional Chinese patent medicines, namely "Xiao'er qingganling" tablet, "Buchang xinnaoxintong" capsulae and "Ganmao qingre" granule is described. "Xiao'er qingganling" tablet and "Buchang xinnaoxintong" capsulae were extracted with methanol in an ultrasonic bath and "Ganmao qingre" granule was extracted with water and ethanol. After being centrifuged and filtered, the samples were separated on an ODS column with a mobile phase of 100 mmol/L ammonium acetate buffer (pH 5.0)-methanol(75:25, volume ratio). The flow rate was 0.8 mL/min, and the detection wavelength was 250 nm. The calibration curve was linear in the range of 2 mg/L-20 mg/L puerarin (r = 0.9999). The average recoveries were 99.0%, 93.4% and 97.5% for "Xiao'er qingganling" tablet, "Buchang xinnaoxintong" capsulae, "Ganmao qingre" granule respectively. The average contents of puerarin in the medicines were 3.48 mg/g, 1.08 mg/g and 1.52 mg/g (sucrose), and the relative standard deviations were 1.9%, 1.4% and 1.4% respectively.

Chromatography, High Pressure Liquid↗

PubMed2001

[Chemical constituents of Diuranthera inarticulata].

AIM: To investigate the chemical constituents from the roots of Diuranthera inarticulata Wang et K. Y. Lang. METHODS: The compounds were isolated with silica gel column chromatography and their structures were identified on the basis of spectral data and TLC with authentic samples. RESULTS: From the methanolic extracts of the roots of Diuranthera inarticulata, ten compounds were obtained and nine of them were identified as chloromaloside A (III), diuranthoside A (IV), diuranthoside B (V), diuranthoside F (VI), diuranthoside G (VII), 2 alpha, 3 alpha, 19 alpha-trihydroxy-urs-12-en-28-oic acid (VIII), 3,6,7,3',4'-pentamethoxy flavone (IX), gitogenin (X) and daucosterol (XI). III-VI showed inhibition of growth with the yeast, Candida albicans. III, IV and VI also showed inhibition of growth with fungus, Aspergillus niger, in the test of antibacterial activity. CONCLUSION: All of these compounds were isolated from this plant for the first time. Among them, VI and VII are new steroidal saponins.

Anti-Infective Agents↗

PubMed2001

[Application of 18FDG-PET in the diagnosis of lung cancer].

OBJECTIVE: To evaluate the ability of 18FDG-PET in the identification of pulmonary mass and preoperative mediastinal lymph node staging of lung cancer. METHODS: Thirty-four patients with pulmonary neoplasm were evaluated with 18FDG-PET and CT scan respectively. PET data were analyzed semiquantitatively by calculating standardized uptake value (SUV) and also by a visual method. PET and CT results were compared with pathological results. RESULTS: When the visual method was used, the sensitivity and accuracy for detection of malignant mass of 18FDG-PET were 93% and 85% respectively, whereas those of CT were 63% and 53% (P < 0.05) respectively. The accuracy of preoperative mediastinal lymph node staging was 100% by PET and 78% by CT (P < 0.05). Semiquantitative method also provided an accuracy of 74% for detection of malignant mass. CONCLUSIONS: Compared with CT, 18FDG-PET was more accurate to discriminate the property of tumor and mediastinal lymph node stage status of lung cancer.

Adult↗

PubMed2000

Identification of XPR-1, a progesterone receptor required for Xenopus oocyte activation.

Quiescent full-grown Xenopus oocytes remain arrested at the G(2)/M border of meiosis I until exposed to progesterone, their natural mitogen. Progesterone triggers rapid, nontranscriptional responses that lead to the translational activation of stored mRNAs, resumption of the meiotic cell cycles, and maturation of the oocyte into a fertilizable egg. It has long been presumed that progesterone activates the oocyte through a novel nontranscriptional signaling receptor. Here, we provide evidence that a conventional transcriptional progesterone receptor cloned from Xenopus oocytes, XPR-1, is required for oocyte activation. Overexpression of XPR-1 through mRNA injection increases sensitivity to progesterone and accelerates progesterone-activated cell cycle reentry. Injection of XPR-1 antisense oligonucleotides blocks the ability of oocytes to respond to progesterone; these oocytes are rescued by subsequent injection of XPR-1 or the human progesterone receptor PR-B. Antisense-treated oocytes can be activated in response to inhibition of protein kinase A, one of the earliest known changes occurring downstream of progesterone stimulation. These results argue that the conventional progesterone receptor also functions as the signaling receptor that is responsible for the rapid nontranscriptional activation of frog oocytes.

Amino Acid Sequence↗

PubMed2000

SIMPL is a tumor necrosis factor-specific regulator of nuclear factor-kappaB activity.

The IL-1 receptor-associated kinase (IRAK/mPLK) is linked to the regulation of nuclear factor-kappaB (NF-kappaB)-dependent gene expression. Here we describe a novel binding partner of IRAK/mPLK that we term SIMPL (signaling molecule that associates with the mouse pelle-like kinase). Overexpression of SIMPL leads to the activation of NF-kappaB-dependent promoters, and inactivation of SIMPL inhibits IRAK/mPLK as well as tumor necrosis factor receptor type I-induced NF-kappaB activity. Dominant inhibitory alleles of IkappaB kinase (IKKalpha or IKKbeta) block the activation of NF-kappaB by IRAK/mPLK and SIMPL. Furthermore, SIMPL binds IRAK/mPLK and the IKKs in vitro and in vivo. In the presence of antisense mRNA to SIMPL, the physical association between IRAK/mPLK and IKKbeta but not IRAK/mPLK and IKKalpha is greatly diminished. Moreover, dominant-negative SIMPL blocks IKKalpha- or IKKbeta-induced NF-kappaB activity. These results lead us to propose a model in which SIMPL functions to regulate NF-kappaB activity by linking IRAK/mPLK to IKKbeta/alpha-containing complexes.

Amino Acid Sequence↗

PubMed2000

Development of a Diversity-Based Approach for the Discovery of Stereoselective Polymerization Catalysts: Identification of a Catalyst for the Synthesis of Syndiotactic Polypropylene This work was supported by the Cornell Center for Materials Research (CCMR), a Materials Research Science and Engineering Center of the National Science Foundation (DMR-9632275), and the Exxon Chemical Corporation. G.W.C. gratefully acknowledges an NSF Career Award (CHE-9875261), a Camille and Henry Dreyfus New Faculty Award, a Research Corporation Research Innovation Award, an Alfred P. Sloan Research Fellowship, an Arnold and Mabel Beckman Foundation Young Investigator Award, a Camille Dreyfus Teacher-Scholar Award, a 3M Untenured Faculty Grant, an IBM Partnership Award, and a Union Carbide Innovation Recognition Award.

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Journal Article↗

PubMed2000

Membrane localization of Raf assists engagement of downstream effectors.

We have previously described a small molecule-directed protein dimerization strategy, using coumermycin to juxtapose Raf fusion proteins containing the coumermycin-binding domain GyrB. Oligomerization of cytoplasmically localized Raf-GyrB fusion proteins leads to an increase in the kinase activity of both Raf and its substrate Mek. Surprisingly, more distal targets, such as Erk1 and Erk2, are not activated using this approach. Here we report that coumermycin-induced oligomerization of a membrane-localized Raf-GyrB fusion protein potently activated Erk1 and Erk2, up-regulated Fos protein levels, and induced expression of many immediate-early response genes. Thus, both membrane localization and oligomerization of Raf-GyrB are required to target Raf signals to downstream effectors. The ability to activate the entire Raf signal transduction cascade conditionally, using coumermycin-induced oligomerization, should prove useful for dissecting Raf-mediated effects on gene expression and cellular differentiation.

3T3 Cells↗

PubMed2000

Ouabain interaction with cardiac Na+/K+-ATPase initiates signal cascades independent of changes in intracellular Na+ and Ca2+ concentrations.

We have shown previously that partial inhibition of the cardiac myocyte Na(+)/K(+)-ATPase activates signal pathways that regulate myocyte growth and growth-related genes and that increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) and reactive oxygen species (ROS) are two essential second messengers within these pathways. The aim of this work was to explore the relation between [Ca(2+)](i) and ROS. When myocytes were in a Ca(2+)-free medium, ouabain caused no change in [Ca(2+)](i), but it increased ROS as it did when the cells were in a Ca(2+)-containing medium. Ouabain-induced increase in ROS also occurred under conditions where there was little or no change in [Na(+)](i). Exposure of myocytes in Ca(2+)-free medium to monensin did not increase ROS. Increase in protein tyrosine phosphorylation, an early event induced by ouabain, was also independent of changes in [Ca(2+)](i) and [Na(+)](i). Ouabain-induced generation of ROS in myocytes was antagonized by genistein, a dominant negative Ras, and myxothiazol/diphenyleneiodonium, indicating a mitochondrial origin for the Ras-dependent ROS generation. These findings, along with our previous data, indicate that increases in [Ca(2+)](i) and ROS in cardiac myocytes are induced by two parallel pathways initiated at the plasma membrane: One being the ouabain-altered transient interactions of a fraction of the Na(+)/K(+)-ATPase with neighboring proteins (Src, growth factor receptors, adaptor proteins, and Ras) leading to ROS generation, and the other, inhibition of the transport function of another fraction of the Na(+)/K(+)-ATPase leading to rise in [Ca(2+)](i). Evidently, the gene regulatory effects of ouabain in cardiac myocytes require the downstream collaborations of ROS and [Ca(2+)](i).

Animals↗

PubMed2000

CC chemokine receptor (CCR)3/eotaxin is followed by CCR4/monocyte-derived chemokine in mediating pulmonary T helper lymphocyte type 2 recruitment after serial antigen challenge in vivo.

Isolated peripheral blood CD4 cells from allergic individuals express CC chemokine receptor (CCR)3 and CCR4 after expansion in vitro. In addition, human T helper type 2 (Th2) cells polarized in vitro selectively express CCR3 and CCR4 at certain stages of activation/differentiation and respond preferentially to the ligands eotaxin and monocyte-derived chemokine (MDC). However, controversy arises when the in vivo significance of this distinct expression is discussed. To address the functional role of CCR3/eotaxin and CCR4/MDC during the in vivo recruitment of Th2 cells, we have transferred effector Th cells into naive mice to induce allergic airway disease. Tracking of these cells after repeated antigen challenge has established that both CCR3/eotaxin and CCR4/MDC axes contribute to the recruitment of Th2 cells to the lung, demonstrating the in vivo relevance of the expression of these receptors on Th2 cells. We have shown that involvement of the CCR3/eotaxin pathway is confined to early stages of the response in vivo, whereas repeated antigen stimulation results in the predominant use of the CCR4/MDC pathway. We propose that effector Th2 cells respond to both CCR3/eotaxin and CCR4/MDC pathways initially, but that a progressive increase in CCR4-positive cells results in the predominance of the CCR4/MDC axis in the long-term recruitment of Th2 cells in vivo.

Adoptive Transfer↗

PubMed2000

Improved production of adenovirus vectors expressing apoptotic transgenes.

Adenovirus vectors expressing gene products that can induce apoptosis have potential utility in gene therapy applications ranging from the treatment of proliferative diseases to transplantation. However, adenovirus vectors carrying proapoptotic gene products are difficult to produce, as the apoptotic environment is not conducive to adenovirus gene expression and replication. Production of AdFasL/G, an adenovirus vector that expresses high levels of Fas ligand, was severely reduced in the 293 packaging cell line. Increased yields of AdFasL/G were achieved by inclusion of peptide-based caspase inhibitors in the growth medium. However, use of these inhibitors for large-scale production would be difficult and expensive. A screen for gene products that increase the yield of AdFasL/G in 293 cells revealed that the poxvirus serpin CrmA and the adenovirus 14.7K product were able to increase virus yields significantly. Apoptosis induced by AdFasL/G was attenuated in 293CrmA cell lines and virus titers were increased dramatically. However, serial passage of AdFasL/G on 293CrmA cells resulted in the generation of replication-competent adenovirus. To resolve this problem, the CrmA gene was introduced into AE25 cells, an E1-complementing cell line that has limited sequence identity with the vectors. AdFasL/G titers were increased 100-fold on AE25CrmA cells relative to the AE25 cells and RCA contamination was not detectable. In addition, adenovirus vectors that express FADD, caspase 8, and Fas/APO1 were produced efficiently in AE25CrmA and 293CrmA.

Adenoviridae↗

PubMed2000

A simple sample preparation for enhancing the sensitivity of mass spectrometric oligosaccharide determinations through the use of an adsorptive hydrophobic resin.

A simple microadsorption technique is described to remove detergent additives from oligosaccharide samples before their mass spectrometric analysis. The described methodology has been validated with submicrogram quantities of contaminated glycoproteins. This procedure is applicable to investigating minute quantities of glycans in both the positive- and negative-ion mode of matrix-assisted laser desorption/ionization mass spectrometry.

Animals↗

PubMed2000

Open-loop and closed-loop optokinetic nystagmus (OKN) in myasthenia gravis and nonmyasthenic subjects.

Optokinetic nystagmus (OKN) eye movements of myasthenia gravis (MG) and nonmyasthenic ocular palsies, and normal subjects were examined under closed-loop and open-loop conditions. The open-loop OKN condition was achieved by adding the signal of eye-movement velocity of OKN to the computer-generated signal controlling the stimulus grating moving. The OKN was recorded by means of electromagnetic search scleral coil technique. In MG patients, the open-loop gains of OKN increased significantly after the intramuscular injection of an acetylcholinesterase inhibitor, neostigmine, while the closed-loop OKN gains were not significantly changed. Both the closed-loop and open-loop OKN gains of normal subjects and nonmyasthenic patients were not increased for the administration of neostigmine. The experimental results indicated that the open-loop OKN gain could be sensitive to reflect the changes of the function of neuromuscular junction in MG patients.

Adolescent↗