Biomedical subjects

Q Sun

Publications and source records attributed to Q Sun.

At least 19 recordsLinked to original sources

PubMed2007

Ultraviolet upconversion fluorescence in rare-earth-ion-doped Y2O3 induced by infrared diode laser excitation.

Room-temperature ultraviolet emission of Tm(3+) ions at 298 ((1)I(6)-->(3)H(6)), 364 ((1)D(2)-->(3)H(6)), and 391 nm ((1)I(6)-->(3)H(5)) was obtained in Y(2)O(3):Yb(3+)-Tm(3+) by continuous-wave diode laser excitation of 980 nm. Power dependence analysis demonstrates that five- and six-photon upconversion processes populate the (1)D(2) and (1)I(6) states, respectively. We believe that the (1)D(2) population originates from the cross relaxation (1)G(4)+(3)F(4)-->(3)H(4)+(1)D(2) of the Tm(3+) ions, while subsequent energy transfer from Yb(3+) to Tm(3+) excites the (1)D(2) state to the upper (1)I(6) state. High multiphoton-induced ultraviolet emission is also expected for other trivalent rare-earth ions similar to Tm(3+).

Journal Article↗

PubMed2006

Treatment of early mixed cellular and humoral renal allograft rejection with tacrolimus and mycophenolate mofetil.

This prospective study investigated the efficiency of the tacrolimus (Tac) combined with mycophenolate mofetil (MMF) alone without immunoadsorption (IA) or plasmapheresis (PPH) as treatment for early (within 2 weeks) acute humoral rejection (AHR) in non-sensitized renal allograft recipients. Of 160 patients enrolled in this prospective study, 11 patients had histologically and clinically confirmed early steroid-resistant acute rejection with an antibody response and received Tac-MMF therapy. No other aggressive rescue methods such as IA, PPH were used, according to the study design. Patients (n=11) were followed for 13.8+/-3.5 months; nine were females. The complement-dependent cytotoxicity crossmatch was negative before transplantation in all patients and only positive for panel-reactive antibody in one patient. Most of the rejection episodes were mixed with cellular rejection (four patients met Banff IIA criteria, five patients met Banff IIB, one patient met Banff IB, and one patient met Banff borderline). After 16.19+/-6.16 days of treatment, all rejection episodes were successfully reversed and all graft functions were stable, with a mean serum creatinine level of 1.12+/-0.32 mg/dl during follow-up. No patient suffered from severe infectious complications (except one case of urinary infection). Our investigation suggests that Tac combined with MMF alone is adequate to reverse early mixed cellular and humoral C4d-positive rejection in non-sensitized renal allograft recipients.

Acute Disease↗

PubMed2006

Induction of spindle cell morphology in human vascular endothelial cells by human herpesvirus 8-encoded viral FLICE inhibitory protein K13.

Human herpesvirus 8 (HHV8), also known as Kaposi's sarcoma-associated herpesvirus, is linked to the development of Kaposi's sarcoma, a disease characterized by the presence of distinctive proliferating spindle-like cells. Although HHV8 can induce spindle cell transformation of vascular endothelial cells in vitro, the viral gene(s) responsible for this phenotype remain to be identified. We demonstrate that expression of HHV8-encoded viral Fas-associated death domain protein-like IL-1beta-converting enzyme inhibitory protein K13 is sufficient to induce spindle cell phenotype in human umbilical vein endothelial cells (HUVEC), which is associated with the activation of the nuclear factor-kappaB (NF-kappaB) pathway and can be blocked by Bay-11-7082, a specific inhibitor of this pathway. K13 induces the expression of several genes known to be upregulated in HHV8-transformed vascular endothelial cells, such as interleukin (IL)-6, IL-8, CXC ligand 3 (CXCL3), orphan G protein coupled receptor (RDC1), cyclooxygenase-2 (COX-2) and dual-specificity phosphatase 5 (DUSP5). Furthermore, similar to K13, HHV8-induced spindle cell transformation of HUVEC is associated with NF-kappaB activation and can be blocked by Bay-11-7082. Thus, ectopic expression of a single latent gene of HHV8 is sufficient for the acquisition of spindle cell phenotype by vascular endothelial cells and NF-kappaB activation plays an essential role in this process.

Cells, Cultured↗

PubMed2006

Late and early C4d-positive acute rejection: different clinico-histopathological subentities in renal transplantation.

This study was performed to investigate the clinical and pathologic features of C4d-positive steroid-resistant acute rejection (AR) at different phases after renal transplantation. Fifty-six kidney allograft recipients with C4d-positive AR were divided into three groups, very early rejection (VER, occurring < or =14 days following transplantation, n=28), early rejection (ER, occurring 15-180 days following transplantation, n=5), and late rejection (LR, occurring >180 days following transplantation, n=23). Clinical and pathological features were evaluated. Significantly more patients in the ER and LR groups were associated with a reduction or withdrawal of immunosuppressants. More patients in the ER and LR groups experienced a significant (>3 g/l) decrease in serum albumin (80% ER, 91.3% LR, 7.1% VER, P<0.001) and a decrease in hemoglobin (>1 g/dl) (80, 100 vs 17.9%, P<0.001). Most VER patients reported a fever and had very rapid graft dysfunction requiring dialysis. Significantly more patients (87%) had interstitial fibrosis and tubular atrophy in the LR group compared with the other groups and 13% had transplant glomerulopathy. Most cases of VER were reversed with tacrolimus and mycophenolate mofetil treatment, with or without immunoadsorption, with a 1-year survival rate of 96.4%, compared with only 60 and 52.2% in the ER and LR groups. In conclusion, C4d-positive steroid-resistant AR at different time points is associated with unique clinico-histopathological manifestations requiring distinct treatment strategies. Late episodes are usually associated with significantly reduced serum albumin and hemoglobin levels and a poorer outcome. A more specialized treatment protocol should be established for these patients.

Acute Disease↗

PubMed2006

Induction of IRF-3 and IRF-7 phosphorylation following activation of the RIG-I pathway.

The induction of type I interferon (IFN) and the development of the innate antiviral response are mediated by the activation of interferon regulatory factor (IRF)-3 and IRF-7 under the control of the non-canonical kinases TBK-1 and IKKepsilon. The initial sensing of infection by RNA viruses is mediated by the cytoplasmic, retinoic acid inducible gene I (RIG-I), via a Toll-like receptor (TLR) independent signaling pathway. In the present study, we identify key residues involved in IRF-3 and IRF-7 phosphorylation using TAP-tag purification of TBK-1 and IKKepsilon proteins. Based on the identification of an extended sequence motif--SxSxxxS--common to both IRF-3 and IRF-7, an IRF-7 pSer477/479 phosphospecific antibody was generated. Virus infection, TBK-1/IKKepsilon expression or co-expression of different signaling adaptors such as RIG-I, MAVS and TRIF, all stimulated pSer477/479 phosphorylation. Furthermore, the newly identified adaptor of the RIG-I pathway (MAVS/IPS-1/VISA/Cardif) was able to induce IRF and NF-kappaB dependent promoter activity as efficiently as the constitutively active form of RIG-I (DeltaRIG-I). Co-expression of the NS3/4A protease activity of hepatitis C virus however blocked MAVS-mediated gene activation in a dose dependent manner. These studies link RIG-I sensing of viral RNA to downstream kinase signaling and phosphorylation of IRF-3 and IRF-7 via the MAVS/IPS/VISA/Cardif adaptor.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Induction of IL-8 expression by human herpesvirus 8 encoded vFLIP K13 via NF-kappaB activation.

Human herpesvirus 8 (HHV-8) encodes a viral FLICE inhibitory protein (vFLIP), called K13, with homology to the prodomain of caspase 8. K13 has been postulated to protect virally infected cells against death receptor-induced apoptosis. We report that K13 leads to constitutive upregulation of IL-8 secretion by transcriptional upregulation of its promoter. K13-induced IL-8 promoter activation is dependent on an intact NF-kappaB-binding site and is associated with increased binding of classical NF-kappaB pathway subunits p65, c-Rel and p50, respectively. IL-8 production is defective in K13 mutants defective in classical NF-kappaB activation and is blocked by genetic and pharmacological inhibitors of this pathway. In contrast, K13 failed to activate the JNK/AP-1 pathway and deletion of AP-1-binding site in the IL-8 promoter or use of a specific JNK inhibitor had only a partial effect on K13-induced IL-8 promoter activation. Collectively, above results demonstrate that K13 is a major mediator of IL-8 production and therapeutic agents targeting K13-induced NF-kappaB pathway may have a role in the treatment of conditions in which HHV-8-induced IL-8 production plays a pathogenic role.

Binding Sites↗

PubMed2006

Electronic structure of metal/molecule//metal junctions: a density functional theory study of the influence of the molecular terminal group.

We report on density functional theory calculations of the electronic structure of Au(111)/molecule//Au(111) junctions in which thiol molecules are chemically bound at one end to a gold electrode (the "substrate"), while the other end has a separation of a few to several angstroms from a second gold electrode (the "tip"). Our goal is to investigate the role of different molecular terminal groups and of the tip-molecule distance either on the spatial dependence of the local density of states (LDOS) at the Fermi energy E(f) or on the energy dependence of the projected density of states onto different molecular subunits. We consider conjugated diphenylthiol (SPh2R) molecules with terminal groups R = H, SH, CH3, or CF3 as well as "mixed" conjugated-saturated phenylthiol-pentane (SPhC4CH3) and butanethiol-toluene (SC4PhCH3) molecules. For SPh2R molecules, the LDOS at E(f) exhibits an oscillatory exponential decay along the molecule, with an average decay constant that depends weakly on the R terminal group. For the mixed aromatic-aliphatic molecules instead, there are large differences in the LDOS at E(f), with SC4PhCH3 showing a much larger LDOS in the proximity of the terminal CH3 group than SPhC4CH3.

Journal Article↗

PubMed2006

Identification of a quantitative trait locus on rat chromosome 4 that is strongly linked to femoral neck structure and strength.

Risk factors for osteoporotic hip fracture include reduced bone mineral density and poor structure of the femoral neck, both of which are heritable traits. Previously, we showed that despite similar body size, Fischer 344 (F344) rats have significantly different skeletal traits compared with Lewis (LEW) rats. To identify a gene or genes regulating fracture risk at the femoral neck, we mapped quantitative trait loci (QTL) for femoral neck density and structure phenotypes using a 595 F2 progeny derived from the inbred F344 and LEW strains of rats. Femoral neck phenotypes included volumetric bone mineral density (vBMD), neck width, femoral neck cross-sectional area and polar moment of inertia (Ip). A 20-cM genome-wide scan was performed using 118 microsatellite markers and linkage analysis was conducted to identify chromosomal regions harbor QTL for femoral neck phenotypes. Strong evidence of linkage (P<0.01) to femoral neck vBMD was observed on chromosomes (Chrs) 1, 2, 4, 5, 7, 10 and 15. QTL affecting femoral neck structure and biomechanical properties were detected only on Chr 4 where the F344 alleles were shown to improve femoral neck structure, whereas these alleles had no effect on bone measurements at the lumbar spine and only modest effects at the femoral midshaft. In contrast, QTL on Chrs 1, 2 and 10 affected multiple skeletal sites. Several QTL regions in this study are homologous to human chromosomal regions, where linkage to femoral neck and related phenotypes has been reported previously. These findings represent an important first step in localizing and identifying genes that influence hip fragility.

Animals↗

PubMed2006

Risk assessment of organic pesticides pollution in surface water of Hangzhou.

Advances in research on pollution of organic pesticides (OPs) in surface water, pollution survey and risk assessments of organochlorine pesticides (OCPs) and organophosphorus pesticides (OPPs) of surface water in Hangzhou are conducted. Total concentrations of dichloro-diphenyl-trichloroethane (DDT) and hexachloride-benzene (HCH) in surface water were observed to be 0-0.270 microg/L and 0-0.00625 microg/L respectively. DDE, as a metabolite of DDT and many species of OPP(S) were determined in some samples of surface water. Parathion, the main pollutant among OPPs in surface water of Hangzhou, was observed to be 0-0.445 microg/L. Based on these experimental results, health risk assessments on the organic pollution are developed. It is observed that the total risk "R (T)" at present time of surface water in Hangzhou is mainly contributed by organophosphorus pesticides, especially Parathion; HCH and DDT are not the main contaminants; on the contrary, organophosphorous pesticides, especially Parathion, must be of concern at the present time.

China↗

PubMed2006

In situ Raman spectroscopic study of the dissociation of methane hydrate at high pressure.

The dissociation of methane hydrate at high pressure is studied by in situ Raman spectroscopy in a diamond-anvil cell. As for the Raman spectrum of sI methane hydrate, the v(1) band of CH(4) is split into two peaks v'(1) and v''(1), indicating the partitioning of CH(4) between the large (5(12)6(2)) and small (5(12)) cavities, respectively. With increasing temperature, the intensity ratio of Iv'(1)/Iv''(1) decreases obviously, and the d(Iv'(1)/Iv''(1))/dT is -0.079 K(-1). Additionally, the v(1) band of the dissolved CH(4) is close to v''(1) of the CH(4) molecule engaged in the small 5(12) cavity. This implies that, in the initial stage of hydrate formation, the abundance of small 5(12) cavities is greater than that of large 5(12)6(2) cavities.

Journal Article↗

PubMed2006

Recombinant adenoviruses expressing TRAIL demonstrate antitumor effects on non-small cell lung cancer (NSCLC).

INTRODUCTION: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in a variety of malignant cells, but not in normal cells. This preferential toxicity to the abnormal cells renders TRAIL potentially a very powerful therapeutic weapon against cancer. However, a requirement for large quantities of TRAIL to suppress tumor growth in vivo is one of the major factors that has hindered it from being widely applied clinically. To overcome this, we constructed a replication-deficient adenovirus that carries a human full-length TRAIL gene (Ad-TRAIL) and tested its efficacy against a lung cancer model system in comparison to that of the recombinant soluble TRAIL protein. METHODS: To investigate the antitumor activity and therapeutic value of the Ad-TRAIL on the non-small cell lung cancer (NSCLC), four NSCLC cell lines, namely, YTMLC, GLC, A549, and H460 cells, were used. TRAIL protein expression was determined by Western blotting and flow cytometry. Cell viability was analyzed by proliferation assay, and DNA ladder and cell-cycle analysis were used to identify apoptosis. To further evaluate the effect of Ad-TRAIL in vivo, YTMLC cells were inoculated to the subcutis of nude mice. The Ad-TRAIL was subsequently administered into the established tumors. Tumor growth and the TRAIL toxicity were evaluated after treatment. RESULTS: YTMLC cells infected with Ad-TRAIL showed decreased cell viability and a higher percentage of apoptosis. Similar, Ad-TRAIL treatment also significantly suppressed tumor growth in vivo. CONCLUSIONS: TRAIL gene therapy provides a promising therapy for the treatment of NSCLC.

Adenoviridae↗

PubMed2005

Increase of glutathione in mine population of Sedum alfredii: a Zn hyperaccumulator and Pb accumulator.

Phytochelatins (PCs) have been induced in a large range of plant species, but their role in heavy metal tolerance is unclear. Sedum alfredii is a new zinc (Zn) hyperaccumulator and lead (Pb) accumulator found in an old Pb/Zn mine in the Zhejiang Province of China. Until now, the mechanisms of its hyperaccumulation/accumulation and tolerance were poorly understood. The aim of this work was to investigate whether PCs were differentially produced in mine populations of S. alfredii compared with a non-mine control of the same species. The results showed that plants from the mine site were more tolerant to increasing Zn and Pb concentrations than those from the control site. No PCs and cysteine (Cys) were detected by pre-column derivatization with HPLC fluorescence in any tissues of two populations at any treatment, which in turn indicated they were not responsible for Zn and Pb tolerance in the mine population. Instead, Zn and Pb treatments resulted in the increase of glutathione (GSH) for both populations in a tissue-dependent manner. Significant increases were observed in leaf, stem and root tissues of plants grown on the mine site. The results suggest that GSH, rather man PCs, may be involved in Zn and Pb transport, hyperaccumulation/accumulation and tolerance in mine population of S. alfredii.

Adaptation, Physiological↗

PubMed2005

Ferromagnetism in Mn-doped GaN nanowires.

Using density functional theory we show that the magnetic coupling of Mn atoms in the nanowires, unlike that in the thin film, is ferromagnetic. This ferromagnetic coupling, brought about due to the confinement of electrons in the radial direction and the curvature of the Mn-doped GaN nanowires' surface, is mediated by N as is evidenced from the overlap between Mn 3d and N 2p states. Calculations of the anisotropic energy further show that the magnetic moment orients preferably along the [1010] direction while the wire axis points along the [0001] direction.

Journal Article↗

PubMed2005

Genes in canine articular cartilage that respond to mechanical injury: gene expression studies with Affymetrix canine GeneChip.

The Affymetrix canine GeneChip with 23,836 probe sets was used to look for cartilage genes that are significantly altered in response to mechanical impact. The model using canine articular cartilage explants loaded in vitro has been described previously (Chen et al., J Orthop Res 19:703-711, 2001). It is our hypothesis that genes that are activated or repressed in articular cartilage after impact injury initiate cartilage degeneration, leading to osteoarthritis in dogs. Gene expression of known cartilage genes was generally consistent with cartilage biology. A total of 528 genes were significantly (P < .01) up- or down- regulated in response to mechanical damage. After applying the strict Bonferroni correction, 172 remained significantly affected. One of these genes, MIG-6/gene 33, was chosen for verification by real- time quantitative reverse transcriptase polymerase chain reaction (RT-PCR). A 3.8- fold increase in expression was confirmed, consistent with the microarray chip data. Deficiencies in the current annotation of the canine chip are discussed. Gene expression studies with the Affymetrix canine GeneChip are potentially valuable, but await more complete annotation.

Animals↗

PubMed2005

Effects of interactions between cadmium and zinc on phytochelatin and glutathione production in wheat (Triticum aestivum L.).

It has been proposed that phytochelatins (PCs) act as a biomarker for the evaluation of metal toxicity. Little attention has been paid to the effects on metal combinations and glutathione (GSH), the most abundant cellular thiol. In the present study the effects of interactions between cadmium (Cd) and zinc (Zn) on PC and GSH production were examined in wheat tissue over 14 days' exposure. The results showed that the presence of Zn alleviated Cd toxicity, accompanied by a reduction of Cd uptake. Cd and Zn exposure increased PC-SH levels in concentration-, tissue- and time-dependent manners. Of the two metals, Cd was more effective than Zn in PC-SH production. Interactions of Cd and Zn with respect to PC-SH production may be synergistic or inhibitory, strongly depending on duration of exposure and concentration of the metal combinations. Cd also stimulated GSH production in concentration-, tissue- and time-dependent manners, whereas Zn had no significant effects on GSH levels. Compared to the presence of Cd alone, the presence of Zn reduced GSH levels in a tissue-dependent manner over the growth period. The results of the study suggest that metal interactions should be highly considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity, as most metal-polluted natural environments are contaminated with more than one metal.

Biomarkers↗

PubMed2005

Effects of exogenous organic chelators on phytochelatins production and its relationship with cadmium toxicity in wheat (Triticum aestivum L.) under cadmium stress.

Phytochelatins (PCs) have been proposed as a potential biomarker for metal toxicity. In this study, cadmium (Cd) toxicity, PCs production and their relationship in wheat under Cd stress were examined using various exogenous organic chelator-buffered nutrient solutions. Single Cd stress produced strong toxic effects, as indicated by decreases of growth parameters, high level of lipid peroxidation in leaf and overproduction of PCs in root. Exogenous organic chelators with proper dose more or less reduced Cd toxicity by increasing growth parameters and decreasing lipid peroxidation in leaves. Of organic chelators (EDTA, DTPA, citric acid, malic acid and oxalic acid), EDTA was the most effective in decreasing Cd toxicity in plants, followed by DTPA and citric acid. Simultaneously, the concentrations of Cd-induced PCs in roots decreased, and the greatest decrease was caused by application of EDTA and DTPA. Linearly positive relationships were observed between Cd toxicity and root PCs concentrations under the influences of organic chelators, particularly EDTA, DTPA and citric acid. Furthermore, present results provide stronger evidence that PCs synthesis in plant cells was related to free Cd ion concentrations, not total Cd, and demonstrate that the levels of PCs production in plants correlated well with toxic effects caused by the bioavailable Cd levels.

Biomass↗

PubMed2005

Variation of CD4+ and CD8+ T lymphocytes as predictor of outcome in renal allograft recipients who developed acute respiratory distress syndrome caused by cytomegalovirus pneumonia.

INTRODUCTION: We investigated the variation of CD4+ and CD8+ T lymphocytes in renal allograft recipients who developed acute respiratory distress syndrome (ARDS) caused by cytomegalovirus (CMV) infection and their relationship to patients outcome. METHODS: Twenty one cadaveric renal allograft recipients who developed ARDS caused by CMV infection were enrolled in this study. CD4+ and CD8+ T lymphocytes were examined in peripheral blood on five occasions: the admission day (day 0) to ICU as ARDS, day 5, day 10, day 15 in ICU, and discharge day. A value taken in the second month after transplantation was assumed to be the preinfection value. RESULTS: Among 13 surviving patients, the numbers of CD4+ and CD8+ T cells and their ratio increased as the patients recovered. The numbers of CD4+ T cells increased significantly on day 10, day 15, and at discharge day compared with day 0 (P < .05). The number of CD8+ T cells on discharge day and the ratios after day 10 were also significantly higher than those on day 0 (P < .05). In eight nonsurviving patients, the numbers of CD4+ and CD8+ T cells and their ratio was similar to day 0. The number of CD4+ and CD8+ cells after day 5 and their ratio after day 10 were significantly lower than those of survival group (P < .05). CONCLUSION: The variations of CD4+ and CD8+ T lymphocytes and their ratio are useful indicators of the severity of disease and the outcome of patients with CMV infections accompanying ARDS after renal transplantation. Nevertheless, it may be helpful to evaluate the efficiency of ongoing treatment methods in these patients.

CD4 Lymphocyte Count↗

PubMed2005

Late developing C4d-positive humoral renal allograft rejection associated with withdrawal of mycophenolate mofetil.

In renal transplantation, C4d-positive acute humoral rejection (AHR) usually develops in the early stage posttransplantation. It is clear C4d can be detected late after the operation, when it is associated with chronic renal allograft rejection. We report a case of a renal allograft recipient who experienced C4d-positive acute renal allograft rejection associated with withdrawal of mycophenolate mofetil (MMF) at 10 months after transplantation. This 21-year-old single male patient received his first cadaveric renal allograft under immunosuppression with cyclosporine, MMF, and prednisolone. The serum creatinine recovered to the normal range within 4 days. A protocol biopsy performed at 1 month after transplantation revealed no signs of rejection. The graft function was stable until 10 months postoperation, when MMF was converted to mizoribin. Three days later a biopsy showed a C4d-positive rejection. Patient had no response to the MMF combined with tacrolimus and steroid bolus therapy, which generally improves 85% of AHR among Chinese. He finally returned to dialysis. Our report suggested that C4d positive AHR may occur late after transplantation. MMF is important to suppress the body's humoral response to allograft; when MMF was converted to a weaker immunosuppressant, the dose of the other immunosuppressants (cyclosporine for example) must be adjusted properly.

Acute Disease↗