Biomedical subjects

Kun Yang

Publications and source records attributed to Kun Yang.

At least 55 records · Page 3Linked to original sources

PubMed2005

[Genotypic antiretroviral resistance testing and phylogenetic analysis of protease and reverse transcriptase in antiretroviral drug-naïve AIDS patients in Henan province].

OBJECTIVE: Frequency, type and clinical implications on protease and reverse transcriptase drug resistance mutations were investigated and phylogenetic analysis in antiretroviral drug-naïve AIDS patients was carried out in Henan province. METHODS: 45 plasma samples were separated from the anticoagulatory whole blood, from which reverse transcription-polymerase chain reaction technique was used to amplify the partial pol gene. The sequences were analysed for genotypic antiretroviral resistance and phylogenetic relation through landing the websites http://hivdb.stanford.edu and http://hiv-web.lanl.gov, under BioEdit and DNAClub software. RESULTS: Partial pol sequences of 36 samples were successfully amplified. The major mutation rate of resistance to protease was 8.3% (3/36), including types D30A, V32A, G73C and V82A. Minor mutation rate of resistance was 100%, including types of L63PS (36/36), I93L (35/36), V77IL (34/36), A71IVT (10/36) and D60E (2/36). The mutation rate of resistance to reverse transcriptase was 38.9% (14/36). Mutation-scoring and clinical implication clewed drug resistance rates were 5.6% (2/36) and 22.2% (8/36) to protease inhibitors and reverse transcriptase inhibitors respectively, while 1 sample was potentially low-level resistant to all of the protease inhibitors and 3 samples to part of the reverse transcriptase inhibitors. Phylogenetic analysis revealed that the pol gene of 36 samples were highly homologous and having a near relative to B.US.83.RF ACC M17451. 36 samples seemed to have the same infection source while their resistance mutations were not due to drug-resistant virus infection but to the evolving of virus in vivo. CONCLUSION: Most of the antiretroviral drug-naïve AIDS patients in Henan province were sensitive to the currently available antiviral medicine, but antiviral treatment must be in accordance with the strict procedure and to keep better adherence, to avoid the epidemics caused by drug-resistant virus.

Acquired Immunodeficiency Syndrome↗

PubMed2005

[Comparison of clinical and surgico-pathological TNM stage of 2007 lung cancer patients].

OBJECTIVE: An accurate clinical TNM staging of lung cancer is essential for the precise determination of the extent of the disease in order that an optimal therapeutic strategy can be planned. This is especially true in patients with marginally resectable tumors. Clinical over-staging of the disease may deny a patient the benefit of surgery, whereas under-staging may oblige a patient to accept a fruitless or even harmful surgery. We aimed to analyze preoperative clinical (c-TNM) and postoperative surgico-pathologic staging (p-TNM) of lung cancer patients in order to evaluate the accuracy of our clinical staging and its implications on the surgical strategy for lung cancer. METHODS: We did a retrospective comparison of c-TNM and p-TNM staging of 2007 patients with lung cancer surgically treated from January 1999 to May 2003. Preoperative evaluation and c-TNM staging of all patients were based on physical examination, laboratory studies, routine chest X-ray and CT scan of the chest and upper abdomen. Other examinations included sputum cytology, bronchoscopy, abdominal ultrasonography, bone scintiscan, brain CT/MRI, and mediastinoscopy whenever indicated. RESULTS: In the present study the comparison of c-TNM and p-TNM staging of 2007 patients with lung cancer revealed an overall concurrence rate of only 39.0%. In the entire series the extent of disease was clinically underestimated in 45.2% and overestimated in 15.8% of the patients. Among all c-TNM stages the c-IA/B stage of 1105 patients gave the highest rate (55.2%) of underestimating the extent of disease. Clinical staging of T subsets was relatively easy with an overall accuracy rate of 72.9%, while that of N subsets was relatively more difficult with an overall accuracy rate of 53.5%. Analysis also showed that c-IV stage may not be an absolute contraindication to surgery, because in half of the patients, c-M1 turned out to be p-M0, providing the possibility of resectional surgery depending on the status of T and N. CONCLUSION: For reasons to be further determined, the present preoperative clinical TNM staging of lung cancer remains a crude evaluation. Further efforts to improve its accuracy are needed.

Adult↗

PubMed2004

Effects of ionizable organic compounds in different species on the sorption of p-nitroaniline to sediment.

In natural water systems, sorption of an organic pollutant to soil/sediment is often influenced by coexisting organic compounds. For ionizable organic compounds, molecular form may do differently competitive effect from ionic form. In order to examine competitive power of ionizable organic compounds in different forms, effects of some ionizable organic compounds including organic acids and organic bases in molecular form or ionic form on the sorption of p-nitroaniline to a sediment from water were investigated by batch equilibrium experiments. Results exhibit that molecular organic acids are much stronger in competitive power to p-nitroaniline than ionic ones, while ionic ones of organic bases compete with p-nitroaniline stronger than molecular ones. In addition, the competitive powers of coexisting organic acids in molecular form or ionic form in binary-solute systems are good correlated with the nonlinear sorption of cosolutes in single-solute systems, i.e., the stronger nonlinear sorption of the cosolute in single-solute systems, the stronger competitive effect of the cosolute on p-nitroaniline is showed in binary-solute systems. For organic amines, organic cations could be adsorbed through cationic exchange to the sediment more favorably than their molecular forms, and consistently, the former shows stronger competitive power than the latter. These results are of significance for one to describe accurately sorption of ionizable organic compounds in natural environment.

Adsorption↗

PubMed2004

Fluctuation-driven first-order transition in Pauli-limited d-wave superconductors.

We study the phase transition between the normal and nonuniform (Fulde-Ferrell-Larkin-Ovchinnikov) superconducting state in quasi-two-dimensional d-wave superconductors at finite temperature. We obtain an appropriate Ginzburg-Landau theory for this transition, in which the fluctuation spectrum of the order parameter has a set of minima at nonzero momenta. The momentum shell renormalization group procedure combined with epsilon expansion is then applied to analyze the phase structure of the theory. We find that all fixed points have more than one relevant direction, indicating the transition is of the fluctuation-driven first-order type for this universality class.

Journal Article↗

PubMed2004

Strong and durable TCR clustering at the T/dendritic cell immune synapse is not required for NFAT activation and IFN-gamma production in human CD4+ T cells.

The exact function of TCR clustering and organized macromolecular patterns at the immune synapse between APCs and T lymphocytes is unclear. Using human immature or mature dendritic cells (DCs) and autologous CD4(+) effector T cells, we demonstrate that, within a given conjugate, mature DCs induce strong and long-lasting TCR clustering and protein kinase C-theta translocation in a superantigen dose-dependent manner. Moreover, mature DCs promote CD43 exclusion in a dose-independent manner. In contrast, immature DCs are less potent at inducing these molecular rearrangements. Using these models to correlate T cell functions with the frequency, the intensity, and the duration of TCR clustering, we show, in Jurkat T cells, that weak and transient TCR clustering is sufficient to promote TCR down-modulation, protein kinase C-theta translocation at the synapse, and substantial NFAT transcriptional activation. Moreover, we show, in CD4(+) T cell blasts, that strong TCR clustering is required for neither TCR down-modulation nor optimal IFN-gamma production. Together, our results demonstrate that some CD4(+) functional responses, such as cytokine production, are independent of central supramolecular activation cluster formation.

CD4-Positive T-Lymphocytes↗

PubMed2004

Ferromagnetic transition in one-dimensional itinerant electron systems.

We use bosonization to derive the effective field theory that properly describes ferromagnetic transition in one-dimensional itinerant electron systems. The resultant theory is shown to have dynamical exponent z = 2 at tree level and upper critical dimension dc = 2. Thus one dimension is below the upper critical dimension of the theory, and the critical behavior of the transition is controlled by an interacting fixed point, which we study via epsilon expansion. Comparisons will be made with the Hertz-Millis theory, which describes the ferromagnetic transition in higher dimensions.

Journal Article↗

PubMed2004

Adenosine inhibits GABAergic and glycinergic transmission in adult rat substantia gelatinosa neurons.

The effect of adenosine on inhibitory postsynaptic currents (IPSCs) was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole cell patch-clamp technique. Adenosine reversibly reduced the amplitude of GABAergic and glycinergic electrically evoked IPSCs (eIPSCs) in a dose-dependent manner (EC50 = 14.5 and 19.1 microM, respectively). The A1 adenosine-receptor agonist N6-cyclopentyladenosine also reduced the eIPSCs, whereas the A1 antagonist 8-cyclopentyl-1,3-dimethylxanthine reversed the inhibition produced by adenosine. In paired-pulse experiments, the ratio of the second to first GABAergic or glycinergic eIPSC amplitude was increased by adenosine, whereas the response of SG neurons to exogenous GABA or glycine was unaffected. Adenosine reduced the frequency of GABAergic and glycinergic spontaneous IPSCs without changing their amplitude. This reduction in frequency disappeared in the presence of a K+ -channel blocker (4-aminopyridine) but not in the absence of Ca2+. The inhibition by adenosine disappeared in the presence of cyclic-AMP analog (8-Br-cyclic AMP) and adenylate-cyclase activator (forskolin) but not protein-kinase C (PKC) activator (phorbol-12,13-dibutyrate). We conclude that adenosine suppresses inhibitory transmission in SG neurons by activating presynaptic A1 receptors and that this action is mediated by K+ channels and cyclic AMP but not by Ca2+ channels and PKC. This inhibitory action of adenosine probably contributes to the modulation of pain transmission in the SG.

4-Aminopyridine↗

PubMed2004

A novel model of the pulse decay method for measurement of local tissue blood perfusion.

The blood perfusion of biological tissue is a basic parameter of physiology and medical engineering. A novel average temperature model (ATM) is presented in this paper to measure the blood perfusion of tissue based on the thermal pulse-decay method. Differing from the existing point source model (PSM) and spherical source model (SSM), the probe bead average temperature analytical solution is derived and used to estimate the blood perfusion. The blood perfusion prediction errors caused by the approximate assumptions used in each model are studied using the numerical experiment method. Contributions of the tissue parameters, probe thermistor bead parameters, and measurement parameters, such as tissue thermal conductivity, tissue thermal diffusivity, blood perfusion rate, bead thermal conductivity, bead radius, measurement time, and thermal pulse length are discussed. The predicting accuracy of the ATM model is compared with the PSM model and SSM model. The results show that, for all the cases tested, the ATM model is better than the other two.

Biomedical Engineering↗

PubMed2004

Distributions of polycyclic aromatic hydrocarbons in surface waters, sediments and soils of Hangzhou City, China.

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 17 surface water samples and 11 sediments of four water bodies, and 3 soils near the water-body bank in Hangzhou, China in December 2002. It was observed that the sum of PAHs concentrations ranged from 0.989 to 9.663 microg/L in surface waters, from 132.7 to 7343 ng/g dry weight in sediments, and from 59.71 to 615.8 ng/g dry weight in soils. The composition pattern of PAHs by ring size in water, sediment and soil were surveyed. Three-ring PAHs were dominated in surface waters and soils, meanwhile sediments were mostly dominated by four-ring PAHs. Furthermore, PAHs apparent distribution coefficients (K(d)) and solid f(oc)-normalized K(d) (e.g. K(oc)= K(d) / f(oc)) were calculated. The relationship between logK(oc) and logK(ow) of PAHs for field data on sediments and predicted values were compared. The sources of PAHs in different water bodies were evaluated by comparison of K (oc) values in sediments of the river downstream with that in soils. Hangzhou section of the Great Canal was heavily polluted by PAHs released from industrial wastewater in the past and now PAHs in sediment may serve as sources of PAHs in surface water. PAHs in Qiantang River were contributed from soil runoff. Municipal road runoff was mostly contributed to West Lake PAHs.

China↗

PubMed2004

The prognosis of acute respiratory failure in critically ill cancer patients.

Acute respiratory failure (ARF) in patients with cancer is frequently a fatal event. To identify factors associated with survival of cancer patients admitted to an intensive care unit (ICU) for ARF, we conducted a prospective 5-year observational study in a medical ICU in a teaching hospital in Paris, France. The patients were 203 cancer patients with ARF mainly due to infectious pneumonia (58%), but also noninfectious pneumonia (9%), congestive heart failure (12%), and no identifiable cause (21%). We measured clinical characteristics and ICU and hospital mortality rates.ICU mortality was 44.8% and hospital mortality was 47.8%. Noninvasive mechanical ventilation was used in 79 (39%) patients and conventional mechanical ventilation in 114 (56%), the mortality rates being 48.1% and 75.4%, respectively. Among the 14 patients with late noninvasive mechanical ventilation failure (>48 hours), only 1 survived. The mortality rate was 100% in the 19 noncardiac patients in whom conventional mechanical ventilation was started after 72 hours. By multivariable analysis, factors associated with increased mortality were documented invasive aspergillosis (odds ratio [OR], 2.13; 95% confidence intervals [CI], 1.05-14.74), no definite diagnosis (OR, 3.85; 95% CI, 1.26-11.70), vasopressors (OR, 3.19; 95% CI, 1.28-7.95), first-line conventional mechanical ventilation (OR, 8.75; 95% CI, 2.35-35.24), conventional mechanical ventilation after noninvasive mechanical ventilation failure (OR, 17.46; 95% CI, 5.04-60.52), and late noninvasive mechanical ventilation failure (OR, 10.64; 95% CI, 1.05-107.83). Hospital mortality was lower in patients with cardiac pulmonary edema (OR, 0.16; 95% CI, 0.03-0.72). Survival gains achieved in critically ill cancer patients in recent years extend to patients requiring ventilatory assistance. The impact of conventional mechanical ventilation on survival depends on the time from ICU admission to conventional mechanical ventilation and on the patient's response to noninvasive mechanical ventilation.

Acute Disease↗

PubMed2004

Interaction of human fibrinogen receptor (GPIIb-IIIa) with decorsin.

AIM: To build up the structure of human fibrinogen receptor GPIIb-IIIa, subsequently combined with its antagonist decorsin, and to investigate the interaction between decorsin and its receptor GPIIb-IIIa at the molecular level. METHODS: A three-dimensional (3D) molecular model of human fibrinogen receptor GPIIb-IIIa was generated by InsightII, a distance geometry-based homologous modeling package. The structure of human fibrinogen receptor GPIIb-IIIa was built by the InsightII/Homology module using the corresponding of integrin alphaVbeta3 (PDB filecode 1JV2) as the template. Then the primary structures were optimized by energy minimization. Subsequently the structural model was docked with its antagonist decorsin (PDB filecode 1dec). RESULTS: A good substrate-receptor interaction model was achieved. The interaction sites with decorsin converge at domain 8 (betaA domain of beta3 subunit) of GPIIb-IIIa. The direct interatomic contacts were made between 16 GPIIb/IIIa residues and 10 decorsin amino-acid residues. These included van der Waals contacts, electrostatic interaction, hydrogen bond, and salt bridge. Residues in contact were concentrated in four dispersed regions of human GPIIb-IIIa: the RGD reaction motif (118-132 of GPIIIa), the span from 210 to 213 of GPIIIa, Thr182 residue and Asp251 residue of GPIIIa; and they were distributed over five segments of decorsin: Asp10 residue, Asn18 and Lys19 residues, Arg28 residue, RGD motif, and Asp35-Pro36-Tyr37 segment. CONCLUSION: This complex model plays an important role in development and research of some new drugs, especially a new guided fusion-type fibrinogen receptor antagonist.

Amino Acid Sequence↗

PubMed2004

[Adsorption of cation-nonionic mixed surfactants onto sediment and their effects on adsorption of nitrobenzene from water].

Adsorption behaviors of nitrobenzene, a nonionic surfactant (Triton X-100), a cation surfactant (CPC) and their mixture onto a sediment were investigated. The adsorption of Triton X-100 onto the sediment is enhanced with increasing of co-existed CPC at relatively low concentrations but decreased at relatively high concentrations. The adsorption of CPC onto the sediment decreased a little with increasing of co-existed Triton X-100. In natural waters, cation surfactants and nonionic surfactants will be largely adsorbed by soils or sediments. The adsorption of nitrobenzene onto sediment is linear and enhanced by the co-existed Triton X-100 or CPC, and will be significantly enhanced by the mixture of CPC-Triton X-100. Therefore, cation-nonionic mixed surfactants are potentially used to enhance adsorption of organic contaminants onto soils or sediments and to prepare organobentonite for improving their performance in wastewater treatment.

Adsorption↗

PubMed2004

[Survey sources of polycyclic aromatic hydrocarbons in surface water of Hangzhou by K(OC)* values].

Ten polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in 9 surface water samples of Qiantang River and Hangzhou Canal in Hangzhou, China, in December of 2002. It was observed that the sum of PAHs concentrations ranged from 1.104 to 9.663 microg x L(-1) in surface water, from 132.7 to 7343 microg x kg(-1) dry sediments, and from 59.71 to 219.5 microg x kg(-1) dry soils. The accumulative coefficients of PAHs in sediments and soils (K) and apparent partition coefficients normalized by solid organic carbon contents (K(OC)*) were calculated. In Hangzhou Canal, K and K(OC)* values in sediments increased with downstream, and ratio of K(OC)* on sediment to K(OC)* on soil were much larger than 1. Those indicated that Hangzhou Canal was heavily polluted by PAHs released from factory wastewater and PAHs in sediment were mainly sources of PAHs in surface water. In Qiantang River, K and K(OC)* values in sediments decreased with the downstream, and the ratio of K(OC)* on sediment to K(OC)* on soil near 1, and ratio fOC of sediment to fOC of soil approximate to 1, which showed that PAHs in Qiantang River were attributed to soil runoff.

China↗

PubMed2004

Incorporating sorption/desorption of organic pollutants into river water quality model.

Preliminary research was conducted about how to incorporate sorption/desorption of organic pollutants with suspended solids and sediments into single-chemical and one-dimensional water quality model of Jinghang Canal. Sedimentation-resuspension coefficient k3 was deduced; characteristics of organic pollutants, concentrations and components of suspended solids/sediments and hydrological and hydraulic conditions were integrated into k3 and further into river water quality model; impact of sorption/desorption of organic pollutants with suspended solids and sediments on prediction function of the model was discussed. Results demonstrated that this impact is pronounced for organic pollutants with relatively large Koc and Kow, especially when they are also conservative and f.o of river suspended solids/sediments is high, and that incorporation of sorption/desorption of organic pollutants into river water quality model can improve its prediction accuracy.

Adsorption↗

PubMed2004

[Prediction of the impact of climate warming on transmission of schistosomiasis in China].

OBJECTIVE: To predict the intensity and scale of impact on transmission of schistosomiasis japonica in China caused by the climate warming. METHODS: By using climate data from 193 weather stations in China from 1951 to 2000, the GIS database was created to analyze the tendency of average daily temperature. By using the results from the effective accumulated temperature models on Oncomelania snails and Schistosoma japonicum, the climate-transmission model for schistosomiasis was established at country level, by which the spatio-temporal analysis was performed to create the distribution maps of Oncomelania snails and Schistosoma japonicum, respectively, by means of GIS approaches based on the ratio of effective accumulated temperature to the snail or the parasite development temperature (ET/SDT) in all 193 stations. The potential distribution maps with the dispersal risk areas of schistosomiasis japonica in 2030 and 2050 were created based on forecast data that the average temperature of the country will increase by 1.7 degrees C in 2030 and by 2.2 degrees C in 2050. RESULTS: The GIS database of climate-schistosomiasis of the country was established. It was found that the average temperature in the last 5 decades inclined, especially after 1990 it increased significantly with its increasing regression formula T = 0.0198X - 28.476. The climate-transmission model for schistosomiasis was established, and it was found that the geographical distribution of Schistosoma japonicum was much larger than that of Oncomelania snails based on the ratio of ET/SDT. The prediction maps for distribution of schistosomiasis in 2030 and 2050 were created, respectively, which showed that the sensitive areas were extended with the time, the risk of expansion northward for schistosomiasis will be increasing due to directly the climate warming. CONCLUSION: It is predicted that a northward expansion of transmission area of schistosomiasis may occur due to the climate warming, the expanded potential area for schistosomiasis transmission will be important for future surveillance.

Animals↗

PubMed2003

The thrH gene product of Pseudomonas aeruginosa is a dual activity enzyme with a novel phosphoserine:homoserine phosphotransferase activity.

The thrH gene product of Pseudomonas aeruginosa has been shown to complement both homoserine kinase (thrB gene product) and phosphoserine phosphatase (serB gene product) activities in vivo. Sequence comparison has revealed that ThrH is related to phosphoserine phosphatases (PSP, EC 3.1.3.3) and belongs to the l-2-haloacid dehalogenase-like protein superfamily. We have solved the crystal structures of ThrH in the apoform and in complex with a bound product phosphate. The structure confirms an overall fold similar to that of PSP. Most of the catalytic residues of PSP are also conserved in ThrH, suggesting that similar catalytic mechanisms are used by both enzymes. Spectrophotometry-based in vitro assays show that ThrH is indeed a phosphoserine phosphatase with a K(m) of 0.207 mm and k(cat) of 13.4 min(-1), comparable with those of other PSPs. More interestingly, using high pressure liquid chromatography-based assays, we have demonstrated that ThrH is able to further transfer the phosphoryl group to homoserine using phosphoserine as the phosphoryl group donor, indicating that ThrH has a novel phosphoserine:homoserine phosphotransferase activity.

Amino Acid Sequence↗

PubMed2003

Alterations in primary afferent input to substantia gelatinosa of adult rat spinal cord after neonatal capsaicin treatment.

Primary afferent fibers are divided into three main subgroups: Abeta-, Adelta-, and C-fibers. Morphological studies have demonstrated that neonatal capsaicin treatment (NCT) depletes C-fiber inputs in the spinal dorsal horn; the electrophysiological features of the NCT-induced changes, however, remain unclear. This issue was addressed by performing whole-cell voltage-clamp recordings from substantia gelatinosa (SG) neurons in dorsal root-attached spinal cord slices. When estimated from excitatory postsynaptic currents (EPSCs) evoked by stimulating primary afferent fibers, 24 (49%) of 49 neurons examined exhibited C-fiber EPSCs that were either monosynaptic (n = 15) or polysynaptic (n = 9) in origin; only two of the neurons had Abeta-fiber responses. In NCT rats, however, SG neurons exhibiting C-fiber-mediated EPSCs decreased to 7% (3 of 41 neurons tested), whereas Abeta-fiber EPSCs were observed in 21 (51%) of the neurons, and 14 (67%) of them exhibited monosynaptic ones. There was no change in the cell proportion having Adelta-fiber innervation after NCT. Our electrophysiological data suggest that NCT diminishes primary afferent C-fiber inputs while enhancing Abeta-fiber direct innervation in the SG in adulthood.

Action Potentials↗

PubMed2003

Autoantibodies to interferon-gamma in a patient with selective susceptibility to mycobacterial infection and organ-specific autoimmunity.

We evaluated a patient with disseminated Mycobacterium tuberculosis and Mycobacterium chelonae infection, of which he died. He also developed autoimmune (type I) diabetes and primary hypothyroidism. His serum contained a high titer of immunoglobulin G autoantibody to interferon-gamma (IFN-gamma) capable of blocking in vitro responses to this cytokine by peripheral blood mononuclear cells from normal donors. These results suggest that autoantibodies to IFN-gamma can induce susceptibility to disseminated mycobacterial infection, which may be refractory to chemotherapy.

Autoantibodies↗