Biomedical subjects

Y Zou

Publications and source records attributed to Y Zou.

At least 19 recordsLinked to original sources

PubMed2006

ATR-dependent checkpoint modulates XPA nuclear import in response to UV irradiation.

In response to DNA damage, mammalian cells activate various DNA repair pathways to remove DNA lesions and, meanwhile, halt cell cycle progressions to allow sufficient time for repair. The nucleotide excision repair (NER) and the ATR-dependent cell cycle checkpoint activation are two major cellular responses to DNA damage induced by UV irradiation. However, how these two processes are coordinated in the response is poorly understood. Here we showed that the essential NER factor XPA (xeroderma pigmentosum group A) underwent nuclear accumulation upon UV irradiation, and strikingly, such an event occurred in an ATR (Ataxia-Telangiectasia mutated and RAD3-related)-dependent manner. Either treatment of cells with ATR kinase inhibitors or transfection of cells with small interfering RNA targeting ATR compromised the UV-induced XPA nuclear translocation. Consistently, the ATR-deficient cells displayed no substantial XPA nuclear translocation while the translocation remained intact in ATM (Ataxia-Telangiectasia mutated)-deficient cells in response to UV irradiation. Moreover, we found that ATR is required for the UV-induced nuclear focus formation of XPA. Taken together, our results suggested that the ATR checkpoint pathway may modulate NER activity through the regulation of XPA redistribution in human cells upon UV irradiation.

Active Transport, Cell Nucleus↗

PubMed2006

Efficacy of emergent transcatheter transplantation of stem cells for treatment of acute myocardial infarction (TCT-STAMI).

OBJECTIVE: To study whether emergent intracoronary autologous bone marrow cell transplantation (BMT) is applicable for the treatment of acute myocardial infarction (AMI). METHODS: 20 patients admitted within 24 h after the onset of a first AMI were randomly allocated to receive intracoronary autologous BMT (n = 10) or bone marrow supernatant (controls, n = 10) immediately after primary percutaneous coronary intervention. Left ventricular ejection fraction (LVEF), left ventricular end diastolic internal diameter (LVDd) and myocardial perfusion defect scores were examined respectively by echocardiography and single-photon emission computed tomography at one week and six months after AMI. RESULTS: From one week to six months after AMI, LVEF was enhanced from mean 53.8 (SD 9.2)% to 58.6 (9.9)% (p < 0.05) in the BMT group but was unchanged in the control group (58.2 (7.5)% v 56.3 (3.5)%, p > 0.05); LVDd remained unchanged (52.5 (2.8) v 52.1 (3.2) mm, p > 0.05) in the BMT group but was significantly enlarged in the control group (50.4 (6.0) v 55.2 (7.1) mm, p < 0.05). Additionally, myocardial perfusion defect scores decreased from 21 (11) to 13 (10) (p < 0.01) in the BMT group but were unchanged in the control group (20 (14) v 17 (15), p > 0.05). CONCLUSION: Emergent intracoronary transplantation of bone marrow mononuclear cells after AMI is practicable, and it improved cardiac function, prevented myocardial remodelling and increased myocardial perfusion at six months' follow up.

Bone Marrow Transplantation↗

PubMed2006

Toward quantifying the effectiveness of water trading under uncertainty.

This paper presents a methodology for quantifying the effectiveness of water-trading under uncertainty, by developing an optimization model based on the interval-parameter two-stage stochastic program (TSP) technique. In the study, the effectiveness of a water-trading program is measured by the water volume that can be released through trading from a statistical point of view. The methodology can also deal with recourse water allocation problems generated by randomness in water availability and, at the same time, tackle uncertainties expressed as intervals in the trading system. The developed methodology was tested with a hypothetical water-trading program in an agricultural system in the Swift Current Creek watershed, Canada. Study results indicate that the methodology can effectively measure the effectiveness of a trading program through estimating the water volume being released through trading in a long-term view. A sensitivity analysis was also conducted to analyze the effects of different trading costs on the trading program. It shows that the trading efforts would become ineffective when the trading costs are too high. The case study also demonstrates that the trading program is more effective in a dry season when total water availability is in shortage.

Agriculture↗

PubMed2006

Substrate effect on the melting temperature of thin polyethylene films.

Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization.

Crystallization↗

PubMed2006

Organ changes and bacterial translocation in a rat model of chronic rejection after small bowel transplantation.

UNLABELLED: Rejection after small bowel transplantation (SBTx) may allow bacterial translocation damaging the liver and lungs. This study investigated these issues in a rat model of chronic rejection. MATERIALS AND METHODS: Orthotopic SBTx was performed in syngeneic (SYN) (ACI-ACI, n=8) and allogeneic (ALLO) (ACI-Lewis, n=8) rat strain combinations. Cyclosporine was given to ALLO rats for 28 days. Animals were sacrified between 55 and 65 days. Lymph nodes and venous samples were cultured; Escherichia coli DNA was assessed by polymerase chain reaction. We measured intestine, liver, spleen, and lung protein and DNA contents. Chronic rejection was histologically confirmed. RESULTS: Two of eight and four of eight rats died in the first week after SYN and ALLO SBTx, respectively. There were no differences in organ weights or DNA and protein contents compared with the controls. Gram-negative enteric bacteria were found in two of four ALLO and two of six SYN rats (ns), and aerobic gram-positive were found in two of four and two of six (ns), respectively. Anaerobic growth occurred in mesenteric lymph nodes in only one ALLO rat. E. coli DNA was negative in all animals. Lungs were severely emphysematous in ALLO rats with no histologic changes observed in the other phagocytic organs. Mild rejection was found in the intestine of ALLO rats. CONCLUSIONS: Bowel lesions in ALLO rats might be consistent with chronic rejection and lung lesions could be related to bacterial translocation after SBTx. However, contrary to our expectations, no significant bacterial translocation was demonstrated in either group at the end of the experiments.

Animals↗

PubMed2005

A QTL located on chromosome 4A associated with dormancy in white- and red-grained wheats of diverse origin.

Improved resistance to preharvest sprouting in modern bread wheat (Triticum aestivum. L.) can be achieved via the introgression of grain dormancy and would reduce both the incidence and severity of damage due to unfavourable weather at harvest. The dormancy phenotype is strongly influenced by environmental factors making selection difficult and time consuming and this trait an obvious candidate for marker assisted selection. A highly significant Quantitative Trait Locus (QTL) associated with grain dormancy and located on chromosome 4A was identified in three bread wheat genotypes, two white- and one red-grained, of diverse origin. Flanking SSR markers on either side of the putative dormancy gene were identified and validated in an additional population involving one of the dormant genotypes. Genotypes containing the 4A QTL varied in dormancy phenotype from dormant to intermediate dormant. Based on a comparison between dormant red- and white-grained genotypes, together with a white-grained mutant derived from the red-grained genotype, it is concluded that the 4A QTL is a critical component of dormancy; associated with at least an intermediate dormancy on its own and a dormant phenotype when combined with the R gene in the red-grained genotype and as yet unidentified gene(s) in the white-grained genotypes. These additional genes appeared to be different in AUS1408 and SW95-50213.

Australia↗

PubMed2005

Identification and mapping of SNPs from ESTs in sunflower.

More than 67,000 expressed sequence tags (ESTs) have recently been generated for sunflower (Helianthus), including 44,000 from cultivated confectionery (RHA280) and oilseed (RHA801) lines of Helianthus annuus and 23,000 from drought- and salt-tolerant wild sunflowers, H. argophyllus and H. paradoxus, respectively. To create a transcript map for sunflower, we identified 605 ESTs that displayed small insertion-deletion polymorphism (SNP) variation in silico, had apparent tissue-specific expression patterns, and/or were ESTs with candidate functions in traits such as development, cell transport, metabolism, plant defense, and tolerance to abiotic stress. Primer pairs for 535 of the loci were designed from the ESTs and screened for polymorphism in recombinant inbred lines derived from a cross between the same cultivars (RHA280 x RHA801) employed for sequencing. In total, 273 of the loci amplified polymorphic products, of which 243 mapped to the 17 linkage groups previously identified for sunflower. Comparisons with previously mapped QTL revealed some cases where ESTs with putatively related functions mapped near QTLs identified in other crosses for salt tolerance and for domestication traits such as stem diameter, shattering, flowering time, and achene size.

Chromosome Mapping↗

PubMed2005

A comparison of fine structures in high-resolution x-ray-absorption spectra of various condensed organic molecules.

We report on a high-resolution C-K and O-K near-edge x-ray-absorption fine-structure (NEXAFS) study of large aromatic molecules in condensed thin films, namely, anhydrides 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride, 3,4,9,10-perylene-tetracarboxylic acid dianhydride, benzoperylene-(1,2)-dicarboxylic acid anhydride, and 1,8-naphthalene-dicarboxylic acid anhydride and the quinoic acenaphthenequinone. Due to the high-energy resolution of the third-generation synchrotron source BESSY II we observe large differences in the NEXAFS fine structures even for very similar molecules, resulting in a wealth of new information. The rich fine structure can unambiguously be assigned to the coupling of electronic transitions to vibronic excitations. Backed by ab initio calculations we present a detailed analysis of the spectra that allows the complete interpretation of the near-edge features. It also yields information on the vibronic properties in the electronically excited state as well as on the response of the electronic system upon core excitation. The strong differences in the electron-vibron coupling for different molecules are discussed.

Journal Article↗

PubMed2005

Observation of the anomalous increase of the longitudinal energy spread in a space-charge-dominated electron beam.

We report a new experimental study of the growth of longitudinal energy spread in a space-charge-dominated electron beam, with a beam energy of several keV and beam current of approximately 100 mA. At relatively low beam densities, we measure growing energy spreads with distance along the transport channel, which are in remarkably good agreement with the theory of energy relaxation via Coulomb collisions. At higher beam densities, however, anomalous energy spreads exceeding the predictions of the relaxation theory are observed, which, we believe, could be caused by collective longitudinal-transverse instabilities observed in computer simulation studies. The onset of these instabilities occurs after several plasma periods according to calculations.

Journal Article↗

PubMed2004

Bacterial translocation in acute rejection after small bowel transplantation in rats.

Acute rejection after small bowel transplantation (SBTx) may facilitate bacterial translocation (BT) and subsequent changes in the liver, spleen, and lungs. This study investigated whether BT occurs after acute rejection and whether this is followed by changes in the structure of the intestine and the phagocytic organs interposed between the gut and the general circulation. Orthotopic SBTx was performed in allogeneic (ALLO) rat-strain combinations (BN-Wistar, n=5). For comparison we used syngeneic SBTx (SYN) (BN-BN, n=6) controls. Animals were sacrificed on postoperative day 7. Mesenteric lymph nodes and portal and caval blood were cultured for aerobes and anaerobes. Escherichia coli beta-galactosidase DNA was assessed by polymerase chain reaction in the blood samples. Intestine, liver, spleen, and lung protein and DNA contents were measured. Histologic changes were graded according to standard criteria of acute rejection. For comparisons we used chi(2) and nonparametric Mann-Whitney test with a threshold of significance of p<0.05. ALLO rats lost more weight after SBTx than SYN rats (-13.02+/-4.39% vs. -8.04+/-5.08% of preoperative weight), although the difference was not significant (ns). A variable degree of graft rejection was histologically demonstrated in all ALLO rats, and DNA/protein content in the graft was significantly higher in this group (0.245+/-0.85 vs. 0.134+/-0.21, p<0.05). Gram-negative enteric bacteria were found in 4/5 ALLO and 4/6 SYN rats (ns), and aerobic Gram-positive bacteria in 2/5 and 3/6 (ns), respectively. Anaerobic growth occurred in mesenteric lymph nodes in one ALLO rat and in the bloodstream in another one. E. coli DNA was isolated in none of the ALLO but in two SYN rats (ns). BT was frequent after SBTx in both syngeneic and allogeneic strain combinations. Contrary to our expectations, BT after SBTx was not higher in ALLO group rats. However, anaerobic germs were isolated only in this group.

Acute Disease↗

PubMed2004

Line shapes and satellites in high-resolution x-ray photoelectron spectra of large pi-conjugated organic molecules.

We present a high-resolution C1s and O1 s x-ray photoemission (XPS) study for condensed films of pi-conjugated organic molecules, namely, of the anhydrides 3,4,9,10-perylene-tetracarboxylic acid dianhydride, 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride, 1,8-naphthalene dicarboxylic acid anhydride, and benzoperylene-(1,8)-dicarboxylic acid anhydride as well as the quinoic acenaphthenequinone. Although the functional groups are identical for the anhydrides, the molecules show very different photoemission fine structure thus providing a detailed fingerprint. A simultaneous peak fit analysis of the XPS spectra of all molecules allows to consistently determine the ionization potentials of all chemically different carbon and oxygen atoms. Additional structures in the C1s and O1s spectra are interpreted as shakeup satellites and assigned with the help of singles and doubles configuration interaction calculations. These satellites provide further information on multielectron excitations and must be taken into account for quantitative investigations.

Journal Article↗

PubMed2004

Electron-vibron coupling in high-resolution X-Ray absorption spectra of organic materials: NTCDA on Ag(111).

We report additional rich fine structures in high-resolution near-edge x-ray-absorption fine structure (NEXAFS) spectra of large organic molecules using NTCDA on Ag(111) as an example. These fine structures are completely interpreted as vibronic coupling to electronic core excitations. The coupling is mode selective; predominantly one vibronic mode couples to each excitation. The fit results suggest the occurrence of a Davydov splitting, first observed for core excitons. Morphological differences substantially influence the electron-vibron coupling, indicating a strong intermolecular interaction. Thus NEXAFS becomes a more subtle probe for organic solids.

Journal Article↗

PubMed2004

Electron-electron interaction in strong electromagnetic fields: the two-electron contribution to the ground-state energy in He-like uranium.

Radiative recombination transitions into the ground state of cooled bare and hydrogenlike uranium ions were measured at the storage ring ESR. By comparing the corresponding x-ray centroid energies, this technique allows for a direct measurement of the electron-electron contribution to the ionization potential in the heaviest He-like ions. For the two-electron contribution to the ionization potential of He-like uranium we obtain a value of 2248+/-9 eV. This represents the most accurate determination of two-electron effects in the domain of high-Z He-like ions, and the accuracy reaches already the size of the specific two-electron radiative QED corrections.

Journal Article↗

PubMed2004

Critical assessment of the methods used for detection of bacterial translocation.

AIM: Bacterial translocation (BT) can be demonstrated by blood and lymph node cultures and also by polymerase chain reaction (PCR) detection of DNA of enteric bacteria. Aiming at investigating BT after gastrointestinal operations we assessed it on two endpoints after ischemia-reperfusion (IR) or sham operation (SO). METHODS: 2 groups of 200-g Brown Norway male rats were treated as follows: SO animals ( n=12) had laparotomy alone and IR animals ( n=12) had successively 15 min clamping of the portal vein and the mesenteric artery. Half the animals in each group were killed on postoperative (p.o.) day 2 the other half on p.o. day 7. Under sterile conditions regional lymph nodes and vena cava and portal vein blood samples were recovered and cultured for aerobes and anaerobes. Escherichia coli beta-galactosidase DNA was assessed in blood samples by PCR. The findings in the two groups were compared by means of chi(2) tests. RESULTS: Post-hepatic (peripheral blood) BT was detected by cultures of gram-negative bacteria in 16% and 0% of SO and IR animals, respectively, on p.o. day 2 and in 16% and 50% on p.o. day 7. These differences were not significant (ns). E. coli DNA was found in one SO rat. Pre-hepatic BT (portal blood and/or lymph nodes) of gram-negative bacteria was found in 16% and 33%, respectively, on day 2 and in 16% and 16% on day 7 (ns). However, if gram-positive cultures were taken into account, the figures were 66% and 66% on day 2 and 66% and 83% on day 7 (ns). No anaerobes could be cultured. CONCLUSIONS: (1) BT is frequent in surgically manipulated animals. (2) To limit the assessment of BT to Enterobacteriaceae is probably misleading, since consistent amounts of gram-positive bacteria are found in the pre-hepatic territory. (3) PCR tests limited to E. coli DNA alone are likely incomplete. (4) Short periods of vascular clamping do not increase BT on the two endpoints selected in comparison with SO animals.

Animals↗

PubMed2004

Spontaneous basilar membrane oscillation and otoacoustic emission at 15 kHz in a guinea pig.

A spontaneous otoacoustic emission (SOAE) measured in the ear canal of a guinea pig was found to have a counterpart in spontaneous mechanical vibration of the basilar membrane (BM). A spontaneous 15-kHz BM velocity signal was measured from the 18-kHz tonotopic location and had a level close to that evoked by a 14-kHz, 15-dB SPL tone given to the ear. Lower-frequency pure-tone acoustic excitation was found to reduce the spontaneous BM oscillation (SBMO) while higher-frequency sound could entrain the SBMO. Octave-band noise centered near the emission frequency showed an increased narrow-band response in that frequency range. Applied pulses of current enhanced or suppressed the oscillation, depending on polarity of the current. The compound action potential (CAP) audiogram demonstrated a frequency-specific loss at 8 and 12 kHz in this animal. We conclude that a relatively high-frequency spontaneous oscillation of 15 kHz originated near the 15-kHz tonotopic place and appeared at the measured BM location as a mechanical oscillation. The oscillation gave rise to a SOAE in the ear canal. Electric current can modulate level and frequency of the otoacoustic emission in a pattern similar to that for the observed mechanical oscillation of the BM.

Acoustic Stimulation↗

PubMed2004

Iodine nutritional status of adults during a period of salt iodization.

BACKGROUND: To measure the iodine nutritional status of island adults in Zhoushan, China. METHODS: A comparison study was carried out in eight villages. These were selected from iodized salt and non-iodized salt districts of Zhoushan island by random sampling. The Mann-Whitney test was used to compare the urinary iodine concentration and dietary iodine intake between the two districts. RESULTS: The median of urinary iodine concentration in the non-iodized salt group was 90 micrograms/l, which was lower than 194 micrograms/l in the iodized salt group (u = 14.673; p < 0.000), whereas the median of daily dietary iodine intake in the two groups was 128 and 147 micrograms, respectively (u = 1.847; p = 0.065). There was no significant correlation between dietary iodine intake and urinary iodine concentration (p = 0.095). CONCLUSIONS: Salt iodization is necessary. Special characteristics of the island diet should also be considered.

Adult↗

PubMed2003

High precision wavelength measurements of QED-sensitive forbidden transitions in highly charged argon ions.

We present the results of an experimental study of magnetic dipole (M1) transitions in highly charged argon ions (Ar X, Ar XI, Ar XIV, Ar XV) in the visible spectral range using an electron beam ion trap. Their wavelengths were determined with, for highly charged ions, unprecedented accuracy up to the sub-ppm level and compared with theoretical calculations. The QED contributions, calculated in this Letter, are found to be 4 orders of magnitude larger than the experimental error and are absolutely indispensable to bring theory and experiment to a good agreement. This method shows great potential for the study of QED effects in relativistic few-electron systems.

Journal Article↗

PubMed2003

Measurement of decay parameters for Xi- --> Lambda pi- decay.

Based on 1.35 x 10(6) polarized Xi(-) events, we measure the parameter phi(Xi) to be -1.61 degrees +/-2.66 degrees +/-0.37 degrees for the Xi(-)-->Lambda pi(-) decay. New results for the parameters beta(Xi) and gamma(Xi) are also presented. Assuming that the CP-violating phase difference is negligible, we deduce the strong phase difference between the P-wave and S-wave amplitudes of the Lambda pi final state to be 3.17 degrees +/-5.28 degrees +/-0.73 degrees, reducing the uncertainty in estimating the level of CP violation in Xi-hyperon decay.

Journal Article↗