Biomedical subjects

X J Zhou

Publications and source records attributed to X J Zhou.

At least 37 records · Page 2Linked to original sources

PubMed2003

Docosahexaenoic acid ameliorates murine ischemic acute renal failure and prevents increases in mRNA abundance for both TNF-alpha and inducible nitric oxide synthase.

This study demonstrates that intraperitoneal injections of DHA (all cis 4,7,10,13,16,19 docosahexaenoic acid C22: n-3) bound to bovine serum albumin ameliorate murine acute renal failure (ARF) induced by temporary occlusion of the renal artery. Three micromoles of DHA decreased serum creatinine (Scr) from 2.3 mg/dl to 1.1 mg/dl 24 h after reperfusion (n = 15; P < 0.05). Scr of the treated animals were significantly lower than controls throughout a 7-d time course. Although lower doses of DHA were less effective, higher doses were not more effective. Ribonuclease (RNase) protection assays showed that ischemia increased mRNA abundance for TNF-alpha and inducible nitric oxide synthase (iNOS) at 24 h. This increase was prevented by DHA administration. Because TNF-alpha and iNOS contribute to renal ischemic injury, their inhibition may contribute to DHA's salutary effect. In addition, the data may have therapeutic implications, because the DHA improves ARF even when administered at 4 h after reperfusion.

Acute Kidney Injury↗

PubMed2002

Anomalous momentum dependence of the quasiparticle scattering rate in overdoped Bi2Sr2CaCu2O8.

The question of the anisotropy of the electron scattering in high temperature superconductors is investigated using high resolution angle-resolved photoemission data from Pb-doped Bi2Sr2CaCu2O8 (Bi2212) with suppressed superstructure. The scattering rate of low energy electrons along two bilayer-split pieces of the Fermi surface is measured (via the quasiparticle peak width), and no increase of scattering towards the antinode (pi,0) region is observed, contradicting the expectation from Q=(pi,pi) scattering. The results put a limit on the effects of Q=(pi,pi) scattering on the electronic structure of this overdoped superconductor with still very high T(c).

Journal Article↗

PubMed2002

Electronic structure of the trilayer cuprate superconductor Bi(2)Sr(2)Ca(2)Cu(3)O(10+delta).

The low-energy electronic structure of the nearly optimally doped trilayer cuprate superconductor Bi(2)Sr(2)Ca(2)Cu(3)O(10+delta) is investigated by angle-resolved photoemission spectroscopy. The normal state quasiparticle dispersion and Fermi surface and the superconducting d-wave gap and coherence peak are observed and compared with those of single- and bilayer systems. We find that both the superconducting gap magnitude and the relative coherence-peak intensity scale linearly with T(c) for various optimally doped materials.

Journal Article↗

PubMed2002

The biological behaviour of human adenoid cystic carcinoma cells transduced with interleukin-2-gene.

Adenoid cystic carcinoma (ACC) of the salivary glands is a highly infiltrative malignant tumour with a tendency for lung metastasis. Gene therapy could be a potentially effective therapy for ACC and its metastasis. The aims of the study were: To transduce interleukin-2 (IL-2) gene into an ACC cell line with predisposition for lung metastasis (ACC-M); to compare the bioactivity of the gene-transduced cells and the parent cell line in vitro and in vivo. The IL-2 gene was transduced via a bicistronic retroviral vector into the ACC-M cells. The growth rate and DNA cell cycles of the parent ACC-M, the control viral vector AmGCEN, and the gene transduced AmIL-2 cell cultures were compared quantitatively and by flow cytometry, respectively. The tumourigenic ability of the three cell lines was verified by inoculation in athymic nude mice. The tumours developed were extracted and compared quantitatively and histologically. There was no difference in the growth rate and the DNA count between the ACC-M, AmGCEN, and AmIL-2 cell cultures. In the animal experiment, both the ACC-M and AmGCEN cells stimulated lung metastasis in all the mice, whereas there was no tumour found in the 1 x 10(6) AmIL-2 cells inoculation. On 3 x 10(6) AmIL-2 cells stimulation, three out of six mice developed tumours but the mass and volume of the tumours were smaller than the other two groups. Under light microscopy, the ACC-M tumours were mainly poorly differentiated with minimal cellular matrix, whereas the AmIL-2 tumours were well differentiated with ample matrix. The transduction of IL-2 gene can reduce the tumourigenicity of ACC-M cells and induces tumour cell differentiation in mice. The IL-2 gene can be a potential effective gene for the treatment of adenoid cystic carcinoma of salivary glands and its lung metastasis.

Animals↗

PubMed2002

The pathogenesis of oral lichen planus.

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

Animals↗

PubMed2001

Evidence for ubiquitous strong electron-phonon coupling in high-temperature superconductors.

Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the high-transition-temperature superconductors has driven an intensive search for an alternative mechanism. A coupling of an electron with a phonon would result in an abrupt change of its velocity and scattering rate near the phonon energy. Here we use angle-resolved photoemission spectroscopy to probe electron dynamics-velocity and scattering rate-for three different families of copper oxide superconductors. We see in all of these materials an abrupt change of electron velocity at 50-80 meV, which we cannot explain by any known process other than to invoke coupling with the phonons associated with the movement of the oxygen atoms. This suggests that electron-phonon coupling strongly influences the electron dynamics in the high-temperature superconductors, and must therefore be included in any microscopic theory of superconductivity.

Journal Article↗

PubMed2001

Dual nature of the electronic structure of (La(2--x--y)Nd(y)Sr(x))CuO(4) and La(1.85)Sr(0.15)CuO(4).

High resolution angle-resolved photoemission measurements have been carried out on (La(1.4--x)-Nd(0.6)Sr(x))CuO(4), a model system with static one-dimensional (1D) charge ordering (stripe), and (La(1.85)-Sr(0.15))CuO(4), a high temperature superconductor (T(c) = 40 K) with possible dynamic stripes. In addition to the straight segments near ( pi,0) and ( 0,pi) antinodal regions, we have identified the existence of spectral weight along the [1,1] nodal direction in the electronic structure of both systems. This observation of nodal state, together with the straight segments near antinodal regions, reveals the dual nature of the electronic structure of stripes due to the competition of order and disorder.

Journal Article↗

PubMed2001

Evidence of electron fractionalization from photoemission spectra in the high temperature superconductors.

In the normal state of the high temperature superconductors Bi(2)Sr(2)CaCu(2)O(8+delta) and La2(-x)Sr(x)CuO4, and in the related "stripe ordered" material, La(1.25)Nd(0.6)Sr(0.15)CuO4, there is sharp structure in the measured single hole spectral function, A<(k-->,omega), considered as a function of k--> at fixed small binding energy omega. At the same time, as a function of omega at fixed k--> on much of the putative Fermi surface, any structure in A<(k-->,omega), other than the Fermi cutoff, is very broad. This is characteristic of the situation in which there are no stable excitations with the quantum numbers of the electron, as is the case in the one-dimensional electron gas.

Journal Article↗

PubMed2001

Modulation of the pharmacokinetics of endogenous plasma uridine by 5-(phenylthio)acyclouridine, a uridine phosphorylase inhibitor: implications for chemotherapy.

PURPOSE: The purpose of this investigation was to evaluate the ability of oral PTAU, 5-(phenylthio)acyclouridine, to increase the concentration of endogenous plasma uridine. PTAU is a new potent and specific inhibitor of uridine phosphorylase (UrdPase, EC 2.4.2.3), the enzyme responsible for uridine catabolism. This compound was designed as a lipophilic inhibitor in order to facilitate its access to the liver and intestine, the main organs involved in uridine catabolism. METHODS: PTAU was administered to mice orally and parenterally. The plasma levels of PTAU as well as those of uridine and its catabolite uracil were measured by HPLC, and pharmacokinetic analysis was performed. RESULTS: PTAU was fully adsorbed after oral administration (over 100% oral bioavailability) and no PTAU metabolites were detected. PTAU administered orally had no apparent toxicity at doses up to 120 mg/kg per day for 5 days. Parenteral administration of PTAU at 30, 45 and 60 mg/kg increased the concentration of endogenous plasma uridine (1.8 +/- 0.2 microM) by approximately six-, seven-, and nine-fold, respectively. Plasma uridine concentration remained higher than control values until 8 h after PTAU administration. Similar results were obtained following oral administration of PTAU. The baseline concentrations of endogenous plasma uridine were increased by approximately six-, seven- and ten-fold by oral administration of PTAU at 30, 45 and 60 mg/kg, respectively, and remained higher than the controls until 8 h after PTAU administration. PTAU did not alter the concentration of endogenous plasma uracil. CONCLUSION: The effectiveness of the PTAU in elevating and sustaining high plasma uridine concentrations may be useful in rescuing or protecting the host from toxicities of various chemotherapeutic pyrimidine analogues as well as in the management of medical disorders that respond to the administration of uridine.

Animals↗

PubMed2001

Enhancement of the bioavailability of oral uridine by coadministration of 5-(phenylthio)acyclouridine, a uridine phosphorylase inhibitor: implications for uridine rescue regimens in chemotherapy.

PURPOSE: The purpose of this investigation was to evaluate the effectiveness of oral 5-(phenylthio)acyclouridine (PTAU) in improving the oral bioavailability of uridine. PTAU is a new potent and specific inhibitor of uridine phosphorylase (UrdPase, EC 2.4.2.3), the enzyme responsible for uridine catabolism. This compound was designed as a lipophilic inhibitor in order to facilitate its access to the liver and intestine, the main organs involved in uridine catabolism. PTAU is not toxic to mice and is fully absorbed after oral administration (100% oral bioavailability). METHODS: PTAU was administered orally to mice alone or with uridine. The plasma levels of PTAU as well as those of uridine and its catabolite uracil were measured using HPLC, and pharmacokinetic analysis was performed. RESULTS: Co-administration of PTAU with uridine elevated the concentration of plasma uridine in a dose-dependent manner over that resulting from the administration of the same dose of uridine alone, and reduced the clearance of uridine as well as the peak plasma concentration (Cmax) and area under the curve (AUC) of plasma uracil. Coadministration of PTAU at 30, 45 and 60 mg/kg improved the low oral bioavailability (7.7%) of uridine administered at 1320 mg/kg by 4.3-, 5.9- and 9.9-fold, respectively, and reduced the AUC of plasma uracil (1227.8 micromol x h/l) by 5.7-, 6.8- and 8.2-fold, respectively. Similar results were observed when PTAU was coadministered with lower doses of uridine. Oral PTAU at 30, 45 and 60 mg/kg improved the oral bioavailability of 330 mg/kg uridine by 1.8-, 2.6- and 2.8-fold, and that of 660 mg/kg uridine by 2.2-, 2.6- and 3.2-fold, respectively. CONCLUSION: The effectiveness of PTAU in improving the oral bioavailability of uridine could be useful in the rescue or protection from host toxicities of various chemotherapeutic pyrimidine analogues as well as in the management of medical disorders that are remedied by administration of uridine.

Administration, Oral↗

PubMed2001

Down-regulation of endothelial expression of endothelial cell protein C receptor and thrombomodulin in coronary atherosclerosis.

Coronary atherosclerosis with occlusive thrombosis is the major cause of acute myocardial infarction. Although plaque rupture is usually hypothesized to be the predisposing event in coronary thrombosis, the possibility cannot be excluded that local changes in the anticoagulant properties of the endothelium overlying the plaque contribute to this process. It is evident that thrombomodulin and the endothelial cell protein C receptor are critical players in the control of the thrombogenic process. This study examined whether thrombomodulin and the endothelial cell protein C receptor are down-regulated on endothelial cells overlying the atherosclerotic plaque in coronary arteries and thus could potentially favor local thrombus formation. Sections of archival left and right coronary arteries (n = 18 each) with severe atherosclerosis from the native heart of six patients who underwent heart transplantation were immunostained for CD31, CD34, endothelial cell protein C receptor, and thrombomodulin using a streptavidin-biotin-peroxidase method. Controls included left and right coronary arteries from autopsy cases with no atherosclerosis (n = 6), and also from cases with mild atherosclerosis (n = 5). The apparent density of all of these proteins was much higher in control than in atherosclerotic arteries. Our findings support the hypothesis that both endothelial cell protein C receptor and thrombomodulin are down-regulated in coronary arteries with atherosclerosis. These changes would be expected to result in reduced inhibition of thrombogenic and anti-inflammatory activity on the endothelium overlying atherosclerotic regions and thus could contribute to coronary thrombosis.

Antigens, CD34↗

PubMed2001

Matrix metalloproteinases and their inhibitors in oral lichen planus.

BACKGROUND: Oral lichen planus (OLP) is characterized by a sub-epithelial lymphocytic infiltrate, basement membrane (BM) disruption, intra-epithelial T-cell migration and apoptosis of basal keratinocytes. BM damage and T-cell migration in OLP may be mediated by matrix metalloproteinases (MMPs). METHODS: We examined the distribution, activation and cellular sources of MMPs and their inhibitors (TIMPs) in OLP using immunohistochemistry, ELISA, RT-PCR and zymography. RESULTS: MMP-2 and -3 were present in the epithelium while MMP-9 was associated with the inflammatory infiltrate. MMP-9 and TIMP-1 secretion by OLP lesional T cells was greater than OLP patient (p < 0.01) and healthy control subject (p < 0.001) peripheral blood T cells. MMP-9 and TIMP-1 mRNA levels were greater in OLP lesional T cells compared with healthy control subject peripheral blood T cells p < 0.01). Tumor necrosis factor (TNF)-alpha upregulated OLP lesional T-cell MMP-9 (not TIMP-1) mRNA and secretion (p < 0.05). The in vitro activation rate of MMP-9 from OLP lesional T cells was greater than that from OLP peripheral blood T cells (p < 0.05). CONCLUSION: T-cell-derived MMP-9 may be involved in the pathogenesis of OLP. Relative over-expression of MMP-9 (compared with TIMP-1) may cause BM disruption and facilitate intra-epithelial T-cell migration in OLP.

Adult↗

PubMed2001

Mast cell degranulation and the role of T cell RANTES in oral lichen planus.

OBJECTIVES: The present study investigated mast cell degranulation in oral lichen planus (OLP) and the effect of OLP lesional T cell supernatants on mast cell degranulation. MATERIALS AND METHODS: Immunohistochemistry was used to identify mast cell degranulation in both OLP (n = 22) and normal control (n = 14) tissues. OLP lesional T cell lines (n = 5) and HMC-1 (a human leukemia mast cell line) were used to examine the effects of OLP T cell supernatants on mast cell degranulation in vitro. RESULTS: Approximately 60% of mast cells were degranulated in OLP. OLP lesional T cells expressed mRNA for RANTES, and TNF-alpha stimulation upregulated OLP lesional T cell RANTES secretion. OLP lesional T cell supernatants induced degranulation of HMC-1 with release of TNF-alpha and histamine. Human recombinant RANTES similarly induced mast cell degranulation. Anti-RANTES antibody blocked OLP lesional T cell supernatant-induced mast cell degranulation. CONCLUSIONS: This study is the first to show that OLP lesional T cells produce and secrete RANTES which triggers human mast cell degranulation. Degranulating mast cells release TNF-alpha which upregulates OLP lesional T cell RANTES secretion. Such a cyclical mechanism may underlie disease chronicity and future therapies may include blocking RANTES or TNF-alpha activity in OLP.

Antibodies↗

PubMed2001

[The hypothalamic suprachiasmatic nucleus and pineal gland in the circadian rhythmic organization of mammals].

The hypothalamic suprachiasmatic nucleus (SCN) is a most important circadian pacemaker, which controls physiological and behaviour rhythm in mammals. SCN owns a intrinsic rhythm itself, and is entrained by photoperiodic signal and some endogenous chemical substances. Melatonin (MEL) is secreted by pineal gland, which is regulated by SCN. MEL triggers the second and third message systems, and regulates SCN circadian activity through high affinity MEL receptor within SCN. This regulation is time-sensitive.

Animals↗

PubMed2001

[Functional and morphological observation on cells in allergic rhinitis guinea-pigs with cold or heat syndrome].

OBJECTIVE: To investigate the functional and morphological characteristics of cells in allergic rhinitis (AR) guinea-pigs with Cold or Heat Syndrome. METHODS: The Cold Syndrome or Heat Syndrome guinea-pig model was made, and then reformed into AR model or rhinitis medicamentosa (RM) model by using nose drops of 10% toluene di-isocyanate (TDI) or 0.1% naphazoline hydrochloride. The cell function, count and ultramicroscopic morphology characteristics in the model animals were observed. RESULTS: The degranulation index (DI), of blood basophils and the count of mast cells (MC) in nasal mucosa were higher in AR guinea-pigs with Cold Syndrome than that in Heat Syndrome guinea-pigs, but the two parameters in AR with both Cold and Heat Syndrome were higher than those in the RM model. Mast cell and eosinophilic granulocyte in AR guinea-pigs with Cold Syndrome were high in count, widely infiltrated, indiscernible cellular capsule, heterogeneous in density, and vacuoles, fusions and tubules in granules while in those with Heat Syndrome, mast cells and eosinophils were scarcely found, without infiltration, granules with discernible membrane and homogeneous in density, no vacuoles, fusions and tubules in granules. CONCLUSION: The basophilic cells, mast cells and eosinophilic granulocytes in AR guinea-pigs with Cold Syndrome are in activated condition.

Animals↗

PubMed2001

[An experimental study on arthroscopic chondrocytes transplantation for repair of osteochondral defects in TMJ].

OBJECTIVE: To certify the feasibility of arthroscopic chondrocytes transplantation in temporomandibular joint (TMJ) and the nature of repaired tissue with autologous chondrocytes transplantation in osteochondral defects. METHODS: The animal models of osteochondral defects in TMJ were established in 12 rhesus monkeys. Autologous auricular chondrocytes were transplanted to the defects by arthroscope. Healing of the defects was assessed by gross examination, light microscope, immunohistochemical staining. RESULTS: The repaired tissues with chondrocytes transplantation were fibrocartilages. CONCLUSION: The technique of arthroscopic chondrocytes transplantation is feasible and the nature of repaired tissue is closest to the normal cartilage, compared with those of subchondral drilling and cartilage transplantation.

English Abstract↗

PubMed2001

[Comparison of anti-proliferation effects of two IFNs on Tca8113, ACC-M in vitro].

OBJECTIVE: Comparison of anti-proliferation and anti tumor specificity of two IFNs on Tca8113, ACC-M in Vitro. METHODS: MTT assay and HTCA were performed to determine direct anti-proliferation effects of two IFNs on Tca8113, ACC-M and L929 cells, respectively. RESULTS: When Tca8113 cells were treated with 1000U/ml alpha-IFN, gamma-IFN, respectively, cell proliferation inhabition rate was (45.4+/-4.1)% by gamma-IFN, (45.9+/-5.4)% by gamma-IFN; inhibition rate of colony formation was (52.0+/-2.9)% by alpha-IFN, (54.6+/-4.1)% by gamma-IFN; and ACC-M cell proliferation inhibition rate was (23.1+/-2.1)% by alpha-IFN,(26.5+/-1.3)% by gamma-IFN; inhibition rate of colony formation was (23.1+/-2.1)% by alpha-IFN, (26.5+/-1.3)% by gamma-IFN; inhibition rate of colony formation was (26.2+/-2.0)% by alpha-IFN, (27.3+/-1.8)% by gamma-IFN. There was no significant difference between two IFNs (P>0.05). When L929 cells were treated with 1000U/ml alpha-IFN, gamma-IFN,respectively, cell proliferation inhibition rate was (3.9+/-1.1)% by alpha IFN, (4.1+/-0.7)% by gamma-IFN; There was significant difference in antiproliferation on Tca8113 cells and L929 cells (P<0.01). CONCLUSION: Both alpha-IFN and gamma-IFN have better direct anti-cancer effect on tongue squamous cell cancer and anti-tumor specificity. But anti-proliferation effect of two IFNs on ACC-M cells was not obvious.

English Abstract↗

PubMed2001

[Effects of millimeter wave combined with gamma-ray radiation on human tongue squamous cell carcinoma cell].

OBJECTIVE: To observe the effects of millimeter wave combined with (60)Co gamma-ray radiation on human tongue squamous cell carcinoma cell(Tca8113). METHODS: Using mm-wave combined with (60)Co gamma-ray to irradiate Tca8113 cell suspensions. The colony forming inhibition efficiency was observed three weeks later. 24 hours after radiation, the samples were observed under electron microscope. RESULTS: The study showed that the radiation could result in significant decrease of the colony forming efficiency (P<0.001). The inhibition efficiency was higher when the samples were exposed to high power density mm-wave or for a long duration (P<0.05 or P<0.01). The inhibiting effect in combined groups was more obvious than in singly radiated group (P<0.001 or P<0.05). There was no difference between 'R+HL' group and 'HL+R' group (P>0.05). Electron microscopy showed the cells' suprastructures had some injuries and regressive changes. And more serious changes existed in 'H' group. CONCLUSION: It could be concluded that mm-wave radiation could efficiently inhibit the colony forming capability of Tca8113 cell. And mm-wave radiation could lead to morphological changes of exterior or interior ultrastructures of Tca8113 cell.

English Abstract↗