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Y Xia

Publications and source records attributed to Y Xia.

At least 289 records · Page 16Linked to original sources
PubMed1994

Diffusion and relaxation mapping of cartilage-bone plugs and excised disks using microscopic magnetic resonance imaging.

Spatially resolved maps of proton self-diffusion coefficients (D) and relaxation times (T1 and T2) were obtained on cartilage-bone plug samples and on excised disks of canine cartilage at a transverse resolution of 30 microns, using microscopic magnetic resonance imaging (micro-MRI). Results are compared for excised disks of cartilage and intact cartilage-bone plugs. Correlations between the absolute water concentration, the self-diffusion coefficient and the T1 relaxation are reported. The diffusion coefficient is not a linear function of water concentration. The thickness of the disks is 600 microns, compared with the ca. 900 microns observed for the cartilage-bone plugs, presumably due to the absence of the interfacial or tidemark layer of interdigitated cartilage and bone in the former samples. Our results suggest that excised disks of cartilage are excellent models for the articular surface and the first 500 or so microns of tissue. The molecular parameters of spin-spin and spin-lattice relaxation times, as well as the water self-diffusion coefficient, are virtually identical in the two types of samples. However, the cartilage-bone plugs have the additional feature of permitting the study of the tidemark region, a region that likely plays a major role in the transmission of mechanical force.

Animals↗
PubMed1994

Stimulation of formation of cAMP by 5-hydroxytryptamine in myenteric ganglia isolated from guinea pig small intestine.

Effects of 5-hydroxytryptamine (5-HT) and related agonists and antagonists on formation of cAMP were determined for enzymatically dissociated ganglia from the myenteric plexus of the guinea-pig small intestine. Formation of cAMP was stimulated by 5-HT in both dose- and time- dependent manners. The stimulatory action of 5-HT was suppressed by the 5-HT1P antagonist, renzapride, but not by the 5-HT3 antagonist, tropisetron (formerly ICS 205-930). Neither renzapride nor cisapride increased the levels of cAMP. Levels of cAMP were suppressed by concentrations of tropisetron greater than 1.0 microM. Levels of cAMP were unaffected by the 5-HT3 agonist, 2-methyl-5-hydroxytryptamine. A putative 5-HT4 receptor agonist, 5-methoxytryptamine, stimulated formation of cAMP, but to a lesser extent than 5-HT. We conclude that 5-HT acts to stimulate adenylate cyclase and the formation of cAMP in myenteric ganglia. The 5-HT1P receptor is the most likely subtype involved in 5-HT action on cAMP formation.

5-Methoxytryptamine↗
PubMed1994

Extracellular matrix accumulation in immune-mediated tubulointerstitial injury.

The accumulation of excessive extracellular matrix (ECM) following tubular injury likely represents an imbalance between ECM production and degradation. We assessed the temporal relationship between the accumulation of ECM, cell adhesion molecules, matrix degrading proteinases, and their inhibitors in a rat model of anti-tubular basement membrane (TBM) antibody-associated tubulointerstitial nephritis (TIN) by the RNase protection assay and immunohistochemistry. There was an increase in the steady state expression of fibronectin (FN) and alpha 2(IV) collagen mRNAs beginning on day 7 with the onset of neutrophil infiltration. An increase in alpha 1(III) collagen and alpha 1-integrin did not occur until days 9 and 10, respectively, at which time mononuclear leukocytes were the predominant infiltrating cell. Increased levels of FN, alpha 1(III), alpha 2(IV) and alpha 1-integrin mRNAs occurred through day 14. By immunohistochemistry, increased accumulation of collagen IV, heparan sulfate proteoglycan, and laminin were detected along the thicken TBM; collagens I and III were immunolocalized within the tubulo-interstitium, while FN was present in both the TBM and interstitium in rats with TIN on day 14. The increase in matrix accumulation was associated with little or no increase in proteinases. u-PA transcripts fell beginning on day 8, with recovery to control values by day 12. Transin mRNA was found at low levels only on days 8 and 9, and the protein could not be detected by Western blotting. In contrast, these changes were associated with an increase in proteinase inhibitors, so that TIMP and PAI-1 mRNAs increased beginning on day 7 and persisted through day 14.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Dissociation of depolarization-activated and swelling-activated Cl- channels.

In many cells, patch excision and depolarization induce outwardly rectifying Cl- channels (ORDIC channels) whose function and normal mode of regulation are unknown. One possible function is the mediation of swelling-activated Cl- conductance, because in many cells rectifying Cl- currents are activated by cell swelling. However, swelling-activated Cl- channels in some epithelia have larger conductances than ORDIC channels and inactivate more rapidly, although both have similar anion selectivity and are blocked by stilbenes. Thus it has not been possible to determine whether the two types of channel current arise from distinct proteins or alternate states of a single protein. We studied 14 cell lines and found 2 lines, C127 mouse mammary epithelial cells and IEC-6 rat intestinal crypt cells, with very low levels of ORDIC channels. However, despite the near absence of ORDIC channels in these rodent cells, a large swelling-activated Cl-conductance was demonstrated by whole cell, efflux, and single-channel methods. Thus it is likely that ORDIC and swelling-activated channel currents arise from different channel proteins.

Animals↗
PubMed1994

Interleukin-1 alpha stimulates KC synthesis in rat mesangial cells: glucocorticoids inhibit KC induction by IL-1.

To assess the possible role of the production of chemokines by intrinsic glomerular cells in the generation of inflammation in glomerulonephritis, the chemokine, KC, was cloned from a rat macrophage cDNA library. Transfection of rat KC into COS-7 cells resulted in increased neutrophil chemotactic activity. The KC cDNA was expressed as a fusion protein in Escherichia coli for generation of an antibody. By using a riboprobe derived from the cDNA and the antibody, interleukin-1 (IL-1) was found to induce the expression of KC in rat mesangial cells. The induction of KC by IL-1 could be inhibited by dexamethasone (DEX). The protein synthesis inhibitor cycloheximide reversed the DEX-mediated inhibition, which suggested that new protein synthesis was necessary for the inhibitory effect. A nuclear runoff analysis indicated that DEX inhibited the transcription of KC induced by IL-1. The stability of KC mRNA was not decreased in the presence of DEX. Furthermore, immunoblots showed that DEX also inhibited KC expression at the level of translation. Together the inhibition of transcription and translation of the KC gene by DEX contribute to decreased KC expression in mesangial cells. The finding that mesangial cells express KC in response to proinflammatory cytokines, such as IL-1, points to a central role for the mesangial cell as a chemotactic source in glomerular inflammation.

Animals↗
PubMed1994

Functional properties of rat and human neocortical voltage-sensitive sodium currents.

1. The functional properties of sodium currents in acutely dissociated adult human, neonatal rat [postnatal day (P) 3 and P10], and mature rat (P21-23) neocortical pyramidal neurons were studied using whole-cell patch-clamp techniques. 2. The voltage dependence of activation and steady-state inactivation of neonatal rat sodium currents was shifted in the positive direction when compared with mature rat sodium currents. In contrast, no difference was detected between the voltage dependence of activation and steady-state inactivation of mature rat and adult human sodium currents. 3. The fast inactivation of rat (neonatal and mature) and human neocortical sodium currents were best fit with three components; a fast decay component, a slow decay component, and a persistent component. The magnitude of the persistent current in neocortical neurons averaged 1-3% of the peak current. Inactivation was faster for sodium currents in neonatal rat neocortical neurons than in mature neurons. No difference was detected in the kinetics of inactivation between mature rat and adult human sodium currents. 4. Saxitoxin (STX) inhibited neuronal sodium currents at nanomolar concentrations in neonatal and mature rat and adult human neocortical neurons. STX-insensitive channels were not detected. 5. STX affinity was also assayed using 3H-STX. A single high-affinity binding site was found in neonatal rat, mature rat, and adult human neocortical tissue. A developmental increase in STX binding site density in the rat neocortex was tightly correlated with the increase in the sodium current density (normalized to cell capacitance). Human neocortical tissue and mature rat neocortical tissue did not differ in STX binding site density or sodium current density. 6. From these electrophysiological and autoradiographic studies we conclude that 1) the increase in the normalized sodium current density and STX binding density with age postnatally reflects an increase in binding sites of sodium channels functionally expressed on neuronal membranes, 2) the functional differences in channel behavior with maturation can explain the higher threshold for excitation in neonatal neocortical neurons and the increase in accommodation or adaptation in firing in the mature neuron, and 3) mature rat neocortical neurons represent a valid model for the study of adult human pyramidal neocortical neurons in terms of Na+ channel expression and function.

Adult↗
PubMed1994

The apolipoprotein E allele epsilon 4 is overrepresented in patients with the Lewy body variant of Alzheimer's disease.

We determined apolipoprotein E (ApoE) genotypes in 122 autopsied demented patients. The frequency of the ApoE epsilon 4 allele was 39.6% in Alzheimer's disease (AD), 29.0% in the Lewy body variant of AD (LBV), and 6.25% in diffuse Lewy body disease. For AD and LBV patients, the epsilon 4 frequency was significantly higher than that reported in nondemented controls (10 to 15%). Therefore, LBV and AD share ApoE epsilon 4 as a genetic risk factor, providing further evidence that these conditions overlap.

Aged↗
PubMed1994

Pericardiocentesis and drainage by a silicon rubber line without echocardiographic guidance. Experience in 55 consecutive patients.

Pericardiocentesis and drainage with a silicon rubber line were performed safely in 55 patients via the subxiphoid (80 times) or apical (1 time) approach at the bedside without echocardiographic guidance. The subxiphoid approach, which is close to the posterior of the sternum or the costal cartilage with a small acute-angle (15-30 degrees) to the parietal pericardium in front of the right ventricle, can avoid injuring the heart, liver and lungs. A line with sideholes near the distal end, which provides convenient drainage and has better histocompatibility, can be kept in place for a long period of time (1-82 days). It was also convenient to inject air, drugs or fluid through the line. There were no procedure-related serious complications or deaths. Emergency drainage with the Seldinger technique, especially for small to moderate effusions, is safe and simple.

Catheters, Indwelling↗
PubMed1994

[The components of somatosensory evoked potentials P250-N350 induced by nervi tibialis posterior stimulation].

The pain components of somatosensory evoked potentials (SEPs) induced by nervi tibialis posterior stimulation were studied by blocking bloodstream of leg in 10 normal adults. The SEPs following the painful stimuli (0.1 msec square wave pulse) of the right ankle were recorded from the parietal median (C'Z) and the reference electrode at earlobe. The pressure of 80 mmHg above the arterial pressure was given to the right calf by sphygmomanometer. The result showed that the P250-N350 components (latency 244.2 +/- 10.1 msec and 344.2 +/- 14.9 msec) of the SEPs persisted and the others disappeared when tactile sensation disappeared but pain existed. It suggested the P250-N350 were the pain potentials of nervi tibialis posterior SEPs.

Adult↗
PubMed1994

CFTR and other Cl- channels in human airway cells.

CFTR is the major Cl- channel in several epithelia, but its importance in airway cells and its interactions with other channels are still poorly understood. We studied the role of CFTR and other Cl- channels in two well-differentiated human airway cell lines--16HBE and Calu-3. Both lines form tight junctions, and the Calu-3 line exhibits large currents in the Ussing chamber that represent Cl- secretion. Apical membrane Cl- conductance in both cell lines in mediated primarily and possibly exclusively by CFTR, because (1) CFTR channels are almost the only anion channels observed in cell-attached patches from confluent cells, (2) whole-cell Cl- current has a linear, time-independent signature, and (3) blockers of many Cl- channels, such as DIDS, do not block Isc. Outwardly rectifying (ORDIC) channels were identified in both airway cell lines. Activation of ORDIC channels in Calu-3 cells required 3 conditions: (1) stimulation with isoproterenol, (2) excision and depolarization, and (3) prior treatment of the cell to disrupt tight junctions. To further assess the physiological significance of ORDIC channels, we compared cell lines which have > 10-fold difference in functional expression of ORDIC channels. ORDIC channel expression was not associated with swelling-activated Cl- currents.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1994

The difference in EEG theta waves between concentrative and non-concentrative qigong states--a power spectrum and topographic mapping study.

The differences in EEG theta waves between concentrative and non-concentrative Qigong states were studied by means of power spectrum analysis and EEG mapping. The adult subjects included 20 practitioners of concentrative Qigong, 30 practitioners of non-concentrative Qigong and 23 control subjects. The results showed frontal mid-line theta rhythm was related to concentrative Qigong state. As the theta rhythm has been suggested to be one of the normal EEG patterns occurring in mental concentration, it is concluded that the theta rhythm is an indicator of mental concentration during Qigong state. This finding clarifies the implication of the theta rhythms appearing in Qigong and other meditation.

Adult↗
PubMed1994

[Biological study on prognosis of laryngeal carcinoma with regional metastatic lymph nodes].

The purpose of this study is to find out the biological feature of laryngeal cancer and metastatic lymph nodes with DNA Image Analysis, Argyrophilic Nucleolar Organizer Region (AgNOR), Carcinoembryonic Antigen (EA) and Estrogen Receptor (ER) 30 patients were included in this study. It was found that carcinomatous tissues showed a statistically significantly higher DNA content, AgNOR content, and positive reaction of CEA and ER than those of normal tissue (P < 0.01). Paired comparisons were performed in primary tumor and metastases and didn't show statistical difference (P > 0.05). The group with survival time over 5 years had a significantly lower DNA content, AgNOR content, CEA positive reaction of metastases and higher ER positive reaction of metastases than those with less than 5 years survival (P < 0.01). But there no was consistant relationship between primary tumor CEA or ER positive reaction and survival time (P > 0.05). The patients who accepted radiotheraphy had better prognosis than those who didn't (P < 0.05). The above results indicate that the combined analysis of metastases and primary tumor will provide a good feature for biological activity. In addition, radiotherapy before and after operation will be beneficial.

Carcinoembryonic Antigen↗
PubMed1994

Products of the TAL2 oncogene in leukemic T cells: bHLH phosphoproteins with DNA-binding activity.

The TAL2 gene is activated as a result of the (7;9) (q34;q32) translocation, a chromosome defect found in the malignant cells of some patients with T-cell acute lymphoblastic leukemia (T-ALL). TAL2 potentially encodes a basic helix-loop-helix motif that is highly related to those specified by TAL1 and LYL1, distinct genes that have also been implicated in T-ALL. In this report we show that leukemic cells bearing the (7;9) (q34;q32) translocation express a TAL2 gene product of 108 amino acids. In leukemic cells this product exists in both a phosphorylated (pp13TAL2) and an unphosphorylated (p12TAL2) form. Serine residue 100 is the major site of TAL2 phosphorylation in vivo, and it serves as an effective in vitro substrate for mitogen-activated protein (MAP) kinases such as ERK1. TAL2 polypeptides interact in vivo with the E2A gene products (E47 and E12) to form bHLH heterodimers that bind DNA in a sequence-specific manner. The TAL2 polypeptides do not bind DNA by themselves, however, suggesting that their functional properties may be contingent upon association with other bHLH proteins. Taken together, the properties of TAL2 evaluated here broadly resemble those described previously for TAL1, and therefore support the idea that both proteins promote T-ALL by a common mechanism.

Base Sequence↗
PubMed1993

Molecular cloning of cDNA encoding an unrecognized component of amyloid in Alzheimer disease.

A neuropathological hallmark of Alzheimer disease (AD) is a widespread amyloid deposition. We analyzed the entire amino acid sequences in an amyloid preparation and found, in addition to the major beta/A4-protein (A beta) fragment, two unknown peptides. We raised antibodies against synthetic peptides using subsequences of these peptides. These antibodies immunostained amyloid in neuritic and diffuse plaques as well as vascular amyloid. Electron microscopic analysis demonstrated that the immunostaining was localized on amyloid fibrils. We have isolated an apparently full-length cDNA encoding a 140-amino-acid protein within which two previously unreported amyloid sequences are encoded in tandem in the most hydrophobic domain. We tentatively named this 35-amino acid peptide NAC (non-A beta component of AD amyloid) and its precursor NACP. NAC is the second component, after A beta, identified chemically in the purified AD amyloid preparation. Secondary structure predictions indicate that the NAC peptide sequence has a strong tendency to form beta-structures consistent with its association with amyloid. NACP is detected as a M(r) 19,000 protein in the cytosolic fraction of brain homogenates and comigrates on immunoblots with NACP synthesized in Escherichia coli from NACP cDNA. NACP mRNA is expressed principally in brain but is also expressed in low concentrations in all tissues examined except in liver, suggesting its ubiquitous and brain-specific functions. The availability of the cDNA encoding full-length NACP should help to elucidate the mechanisms of amyloidosis in AD.

Alzheimer Disease↗
PubMed1993

Cloning a novel form of rat PDGF A-chain with a unique 5'-UT: regulation during development and in glomerulonephritis.

An unique form of rat platelet-derived growth factor A-chain (PDGF A-chain), with a novel 5' UT region, was cloned from a rat macrophage cDNA library and expressed. In the 5' UT, the homology of the 79 bp sequence adjacent to the ATG codon between rat and human was 92%; however, the homology of the remainder in the 5' UT was less than 30%. RNase mapping indicated this form was differentially expressed during development and immune glomerular injury, and that it probably arose from alternative splicing. We propose that the variant mRNAs reflect different levels of the control of PDGF A-chain expression.

Aging↗
PubMed1993

Functional expression of rat alpha 2B-adrenoceptor in Escherichia coli.

Rat alpha 2B-adrenoceptor was expressed in Escherichia coli using 'ATG vector' containing cDNA encoding the 'non-glycosylated rat alpha 2-adrenoceptor' (RNG alpha 2). The highest receptor binding activity (using the alpha 2-adrenoceptor ligand [3H]MK 912) was found when transfected bacteria cultures were grown at 30 degrees C for about 4 h after induction with isopropyl beta-D-thiogalactopyranoside (IPTG). Saturation experiments showed that the radioligand bound to a single saturable site with a Kd of 1.42 +/- 0.09 nM and capacity of 281 +/- 6 fmol/mg protein. Binding constants of 14 compounds for the rat alpha 2B-adrenoceptor expressed in E. coli were determined and compared to the values previously obtained for the rat alpha 2B-adrenoceptor when expressed in COS cells as well as for native neonatal rat lung alpha 2B-adrenoceptors. The results indicate that when the rat alpha 2B-adrenoceptor is expressed in E. coli it retains identical ligand binding properties to those found when the receptor is present in the eukaryotic system. Expressing alpha 2B-adrenoceptors in E. coli would, therefore, seem to constitute a valid alternative in, e.g., drug screening and structure analysis of the alpha 2B-adrenoceptors.

Adrenergic alpha-Antagonists↗