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Biomedical subjects

Y Yu

Publications and source records attributed to Y Yu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Electron-hole duality and vortex rings in quantum dots.

In a quantum-mechanical system, particle-hole duality implies that instead of studying particles, we can get equivalent information by studying the missing particles, the so-called holes. Using this duality picture for fermions in a rotating trap the vortices appear as holes in the Fermi sea. Here we predict that the formation of vortices in quantum dots at high magnetic fields causes oscillations in the energy spectrum which can be experimentally observed using accurate tunneling spectroscopy. We use the duality picture to show that these oscillations are caused by the localization of vortices in rings.

Journal Article↗
PubMed2005

Desferrioxamine induces leukemic cell differentiation potentially by hypoxia-inducible factor-1 alpha that augments transcriptional activity of CCAAT/enhancer-binding protein-alpha.

We reported recently that cobalt chloride-simulated hypoxia and mild hypoxia modified the differentiation of human acute myeloid leukemic (AML) cells, probably acting via a hypoxia-inducible factor-1 alpha (HIF-1 alpha)-dependent mechanism. In this study, we investigated the effect of desferrioxamine (DFO), an iron chelator with 'hypoxia-mimetic' activity, on the differentiation of AML cells. The results showed that DFO at nontoxic concentrations induced the differentiation of AML cell lines NB4 and U937, as assessed by morphological criteria and differentiation-associated antigens. DFO-induced differentiation parallel to the rapid accumulation of HIF-1 alpha protein in these two cell lines. Of importance, the transient transfection of HIF-1 alpha cDNA induced U937 cells to develop the differentiation-related alterations such as growth arrest and increased CD11b expression. Furthermore, the inducible expression of chromosome translocation t(8;21)-generated leukemogenic AML1-ETO fusion gene attenuated DFO-induced differentiation of U937 cells with the decrease of CCAAT/enhancer-binding protein alpha (C/EBP alpha), a critical factor for granulocytic differentiation. Using immunoprecipitation and luciferase reporter assay, HIF-1 alpha was also shown to interact physically with and to increase the transcriptional activity of C/EBP alpha. Taken together, these results provided novel evidence for a role of HIF-1 alpha in AML cell differentiation, and suggested that C/EBP alpha might be a downstream effector for HIF-1 alpha-mediated differentiation.

Acute Disease↗
PubMed2005

Differential gene expression in liver of inbred chickens and their hybrid offspring.

Differential display of mRNA was used to analyse the differences of gene expression in liver between chicken hybrids and their parents in a 4 x 4 diallel crosses in order to study the molecular basis of heterosis in chickens. The results indicated that patterns of gene expression in hybrids differ significantly from their parents. Four patterns of differential gene expression were revealed, which included: (i) bands only detected in the hybrid F1s (UNF1); (ii) bands only absent in the hybrid F1s (ABF1); (iii) bands only detected in the parental P1 or P2 lines (UNP1 and UNP2) and (iv) bands absent in the parental P1 or P2 lines (ABP1 and ABP2). In addition, correlations between patterns of gene expression and heterosis percentages of nine carcass traits of 8-week-old chickens were evaluated. Statistical results showed that negative correlations between heterosis percentages and the percentage of F1-specific bands (UNF1) were significant at P < 0.01 for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens, and at P < 0.05 for intermuscular fat width. Heterosis percentage was negatively correlated with ABP (bands present in the hybrid F1s and one parental line but absent in the other parental line, ABP1 and ABP2) for breast muscle yield, leg muscle yield, wing weight, eviscerated weight and eviscerated weight with giblet of 8-week-old chickens (P < 0.01). Bands detected only in the hybrid F1s but not in either of the parental lines (UNF1) and bands absent in parental P1 or P2 lines (which includes ABP1 and ABP2) may play important roles in chicken heterosis.

Animals↗
PubMed2005

Analysis of community structures in anaerobic processes using a quantitative real-time PCR method.

The methanogenic community structures of four different anaerobic processes were characterized using a quantitative real-time PCR with group-specific primer and probe sets targeting the 16S rRNA gene (rDNA). The group specific primer and probe sets were developed and used to detect the orders Methanosarcinales, and the families Methanosarcinaceae and Methanosaetaceae. Two separate sets targeting the domains Archaea and Bacteria were also used. Each microbial population in different anaerobic processes was determined and the relative abundance in the system was compared with each other. Dominant methanogenic populations and the community structures in the processes were varied by hydraulic retention time and acetate concentration. This indicates that the real-time PCR method with the primer and probe sets is a promising tool to analyze community structures in anaerobic processes.

Acetates↗
PubMed2004

The FLUSH trial--flushing with lipiodol for unexplained (and endometriosis-related) subfertility by hysterosalpingography: a randomized trial.

BACKGROUND: To assess the effectiveness of flushing with the oil-soluble contrast medium lipiodol in women with unexplained infertility. METHODS: An open randomized controlled trial design in a single centre secondary and tertiary level infertility service setting. A total of 158 women with unexplained infertility were stratified into two populations: 96 women without confirmed endometriosis and 62 women with endometriosis who had normal Fallopian tubes and ovaries. Randomization was computer-generated, with allocation concealment by opaque sequentially numbered envelopes. Lipiodol flushing was tested versus no intervention. The main outcome measures were clinical pregnancy (assessed at 6 months following randomization) and live birth. RESULTS: Lipiodol flushing resulted in a significant increase in pregnancy [48.0 versus 10.8%, relative risk (RR) 4.44, 95% confidence interval (CI) 1.61-12.21] and live birth (40.0 versus 10.8%, RR 3.70, 95% CI 1.30-10.50) rates versus no intervention for women with endometriosis, although there was no significant difference in pregnancy (33.3 versus 20.8%, RR 1.60, 95% CI 0.81-3.16) or live birth (27.1 versus 14.6%, RR 1.86, 95% CI 0.81-4.25) rates for women with unexplained infertility without confirmed endometriosis. CONCLUSIONS: Lipiodol flushing is an effective treatment for couples with unexplained infertility (based on meta-analysis data), but is particularly effective for women with endometriosis who have normal Fallopian tubes and ovaries.

Adult↗
PubMed2004

Hepatic resection for metastasis from colorectal cancer.

BACKGROUND: Liver metastases from colorectal cancer are treatable and potentially curable when hepatic resection is applied. This paper is to illustrate surgical treatment of metastatic colorectal cancer in China. PATIENTS AND METHODS: Between January 1993 and December 2002, 485 patients with colorectal liver metastases from 6 institutes in China were reviewed. Among them were 340 males and 145 females with average ages of 55.6 years (23-81). Surgical intervention includes primary colorectal cancer resection, hepatic resection, hepatic arterial chemoembolisation and portal vein catheterisation, and systemic chemotherapy. RESULTS: Among 485 cases, data were not complete in 76, and their 3-year survival rate was 35.7%, while from 409 patients who underwent surgical intervention, 11 cases only underwent colorectal cancer resection (group A); 89 with hepatic resection (group B); 204 with hepatic arterial intervention or portal vein catheterisation chemotherapy (group C); 21 with regional ablation by radiofrequency or microwave thermal coagulation (group D); and 84 with systemic chemotherapy (group E). The cumulative 3- and 5-year survival rates were 0% in groups A and E, 43.5% and 32.1% in group B, 27.1% and 0% in group C, and 42.9% and 19.2% in group D. CONCLUSIONS: Surgery can offer long-term survival and resection should be considered when liver metastases can be totally resected with clear margins and when there is no nonresectable extrahepatic disease. The choice between anatomical or wedge resection depends on the number and the location of the metastases. Special multifunctional operative device limit blood loss and increase resectability.

Adult↗
PubMed2004

Sodium butyrate induces apoptosis in MSN neuroblastoma cells in a calcium independent pathway.

Sodium butyrate (NaBt), a histone deacetylase inhibitor, can cause apoptosis in a number of cancer cells. However, the mechanism of this action is poorly understood. Increased intracellular [Ca(2+)] level has been suggested as a likely mechanism, but there is little corroborating data. In this report we provide evidence that NaBt-treated MSN neuroblastoma cells undergo massive apoptosis in the presence of serum and regardless of external or internal [Ca(2+)] levels. Presented data suggest that apoptotic effect of NaBt is both time- and dose-dependent (LD50 1 mM); and that, presence of serum or cAMP, a second messenger molecule that modulates the apoptotic program in a wide variety of cells could not circumvent the apoptotic effect of NaBt. Our findings suggest that NaBt-induced apoptosis in MSN neuroblastoma cells occurs via a pathway that is independent of Ca(2+) flux, intracellular [Ca(2+)] or cAMP levels. Further, we also present data that exclude a role for PKC or histones acetylation.

Apoptosis↗
PubMed2004

A double-blind randomised controlled trial of laparoscopic uterine nerve ablation for women with chronic pelvic pain.

OBJECTIVE: To determine the effectiveness of laparoscopic uterine nerve ablation (LUNA) for chronic pelvic pain in women with endometriosis and women with no laparoscopic evidence of endometriosis. DESIGN: A prospective double-blind randomised controlled trial (RCT). SETTING: Single-centre, secondary-level gynaecology outpatient service and tertiary-level pelvic pain and endometriosis outpatient service in Auckland, New Zealand. POPULATION: One hundred and twenty-three women undergoing laparoscopy for investigation and management of chronic pelvic pain, 56 with no laparoscopic evidence of endometriosis and 67 with endometriosis. METHODS: Women were randomised from the two populations, firstly those with no evidence of endometriosis and secondly those undergoing laparoscopic surgical treatment for endometriosis, to receive LUNA or no LUNA. Participant and assessor blinding was employed. Follow up for pain outcomes was undertaken at 24 hours, 3 months and 12 months. MAIN OUTCOME MEASURES: Changes in non-menstrual pelvic pain, dysmenorrhoea, deep dyspareunia and dyschezia were assessed primarily by whether there was a decrease in visual analogue score for these types of pain of 50% or more from baseline and additionally whether there was a significantly different change in median visual analogue score. The numbers requiring further surgery or starting a new medical treatment for pelvic pain and complications were also measured. RESULTS: There was a significant reduction in dysmenorrhoea at 12 month follow up in women with chronic pelvic pain in the absence of endometriosis who underwent LUNA (median change in visual analogue scale (VAS) from baseline -4.8 versus-0.8 (P= 0.039), 42.1%versus 14.3% experiencing a successful treatment defined as a 50% or greater reduction in visual analogue pain scale for dysmenorrhoea (P= 0.045). There was no significant difference in non-menstrual pelvic pain, deep dyspareunia or dyschezia in women with no endometriosis undergoing LUNA versus no LUNA. The addition of LUNA to laparoscopic surgical treatment of endometriosis was not associated with a significant difference in any pain outcomes. CONCLUSIONS: LUNA is effective for dysmenorrhoea in the absence of endometriosis, although there is no evidence of effectiveness of LUNA for non-dysmenorrhoeic chronic pelvic pain or for any type of chronic pelvic pain related to endometriosis.

Adolescent↗
PubMed2003

Arsenic trioxide-induced mitotic arrest and apoptosis in acute promyelocytic leukemia cells.

Arsenic trioxide (As(2)O(3)), an effective drug for the treatment of acute promyelocytic leukemia (APL), can induce apoptosis and partial differentiation in APL cells in vitro and in vivo. However, As(2)O(3) also induces apoptosis in cancer cells other than APL with complex mechanisms, which seem to be cell type dependent. In this study, we report that APL cells (NB4 cell line) are arrested at early mitotic phase before the collapse of mitochondrial transmembrane potential (Deltavarphi(m)) and apoptosis after treatment with pharmacological concentrations (1.0-2.0 micro M) of As(2)O(3). We have also made the following new discoveries: (1) 0.5 micro M As(2)O(3) that fails to induce apoptosis has no effects on cell cycle distribution. (2) With inhibition of As(2)O(3)-induced Deltavarphi(m) collapse and apoptosis, dithiothreitol also effectively inhibits As(2)O(3)-induced mitotic arrest, suggesting that both As(2)O(3)-induced apoptosis and mitotic arrest involve proteins with thiol groups. (3) 1.5 mM caffeine that relieves cells from G(2)/M arrest also inhibits As(2)O(3)-induced Deltavarphi(m) collapse and apoptosis, (4) 1.0 micro M As(2)O(3) increases the expression of both cyclin B(1) and hCDC20 whereas it inhibits Tyr15 phosphorylation of p34(cdc2). In conclusion, our results strongly support that there is a tight link between As(2)O(3)-induced apoptosis and mitotic arrest, the latter being one of common mechanisms for As(2)O(3)-induced apoptosis in cancer cells.

Antineoplastic Agents↗
PubMed2003

The inhibitory effect of VitD3 on proliferation of keratinocyte cell line HACAT is mediated by down-regulation of CXCR2 expression.

Psoriasis is a disease characterized by inflammation and increased population of hyperproliferative keratinocytes. It is well known that chemokines and chemokine receptors, such as interleukin-8 and its receptors (CXCR1 and CXCR2), play important roles in the pathogenesis of psoriasis. So far, examination of CXCR2 expression in psoriatic lesional keratinocytes by FACS calibur has not been reported and whether VitD3 inhibits psoriatic lesional keratinocyte proliferation through down-regulation of CXCR2 expression has not been elucidated. In the present study, CXCR2 expression in psoriatic lesional keratinocytes and HACAT treated with VitD3 was detected by flow cytometry. The proliferative capacity of HACAT treated with VitD3 was assayed by MTT assay. The results showed that CXCR2 expression in psoriatic lesional keratinocytes was higher than that in normal human keratinocytes. At the correct concentration VitD3 could inhibit human keratinocyte proliferation and down-regulate CXCR2 expression in HACAT. The data demonstrate that the inhibitory effect of VitD3 on keratinocyte proliferation might be mediated by down-regulation of CXCR2 expression.

Administration, Topical↗
PubMed2003

Response of a calcium sulfate bone graft substitute in a confined cancellous defect.

Calcium sulfate, plaster of Paris, has a long clinical history for use as a bone graft substitute in various skeletal sites. The current authors examined the in vivo response of calcium sulfate pellets alone or in combination with autogenous bone graft in a bilateral critical-size distal femoral cancellous defect in an adult sheep model. New thick bone formation was seen in defects filled with calcium sulfate pellets alone. Increased immunostaining for bone morphogenetic protein-2, bone morphogenetic protein-7, transforming growth factor-beta, and platelet derived growth factor was seen in defects filled with calcium sulfate pellets alone and in combination with autograft. The local acidity during calcium sulfate resorption is proposed as a possible in vivo mechanism for this type of material.

Animals↗
PubMed2003

99mTc-MIBI myocardial perfusion imaging in myocarditis.

Myocardial perfusion imaging with technetium-99m-labelled methoxyisobutyl isonitrile single photon emission computed tomography (99mTc-MIBI SPECT) has proven to be an important clinical procedure in assessing the severity of myocardial ischaemia. The uptake and clearance of 99mTc-MIBI by the myocardium is affected by cell viability and membrane integrity. Consequently, infectious diseases, such as myocarditis, may also affect myocardial perfusion by inducing local inflammation and necrosis. We compared 99mTc-MIBI myocardial perfusion imaging with other heart monitoring methods in order to assess its value in the diagnosis of children with Coxsackie viral myocarditis. We examined 46 patients (age, 3-12 years) with Coxsackie viral myocarditis using 99mTc-MIBI myocardial perfusion imaging and compared the perfusion data with myocardial enzymes, electrocardiographic findings and echocardiography. Regions of hypoperfusion were found in all 46 patients. Seventeen patients (37%) showed two or more areas of diminished perfusion. Myocardial hypoperfusion was mild-to-moderate (<30%) in 33 (72%) patients and severe (>30%) in 13 (28%) patients. Characteristic creatine-kinase isoenzyme (CK-MB) increases, ST-T segment changes and diminished heart function were significantly correlated with reduced myocardial perfusion (all comparisons P<0.05). The results of this study suggest that the presence of myocardial uptake of 99mTc-MIBI may be a marker of myocardial inflammation and necrosis. All 46 patients with Coxsackie viral myocarditis showed a certain degree of reduced perfusion. When the perfusion findings were compared with other parameters, it was shown that myocardial enzyme levels, ST-T segment changes and left ventricular function correlated well with the 99mTc-MIBI-established perfusion defect severity. 99mTc-MIBI SPECT imaging is therefore helpful in providing additional diagnostic information in patients with Coxsackie viral myocarditis.

Child↗
PubMed2002

New genomic resources for the honey bee(Apis mellifera L.): development of a deep-coverage BAC library and a preliminary STC database.

We have constructed a bacterial artificial chromosome (BAC) library for a European honey bee strain using the cloning enzyme HindIII in order to develop resources for structural genomics research. The library contains 36,864 clones (ninety-six 384-well plates). A random sampling of 247 clones indicated an average insert size of 113 kb (range = 27 to 213 kb) and 2% empty vectors. Based on an estimated genome size of 270 Mb, this library provides approximately 15 haploid genome equivalents, allowing >99% probability of recovering any specific sequence of interest. High-density colony filters were gridded robotically using a Genetix Q-BOT in a 4 x 4 double-spotted array on 22.5-cm2 filters. Screening of the library with four mapped honey bee genomic clones and two bee cDNA probes identified an average of 21 positive signals per probe, with a range of 7-38 positive signals per probe. An additional screening was performed with nine aphid gene fragments and one Drosophila gene fragment resulting in seven of the nine aphid probes and the Drosophila probe producing positive signals with a range of 1 to 122 positive signals per probe (average of 45). To evaluate the utility of the library for sequence tagged connector analysis, 1152 BAC clones were end sequenced in both forward and reverse directions, giving a total of 2061 successful reads of high quality. End sequences were queried against SWISS-PROT, insect genomic sequence GSS, insect EST, and insect transposable element databases. Results in spreadsheet format from these searches are publicly available at the Clemson University Genomics Institute (CUGI) website in a searchable format (http://www.genome.clemson.edu/projects/stc/bee/AM__Ba/).

Animals↗
PubMed2002

Conjugated linoleic acid decreases production of pro-inflammatory products in macrophages: evidence for a PPAR gamma-dependent mechanism.

Conjugated linoleic acid (CLA) is a dietary fatty acid that has received considerable attention due to its unique properties in rodent models including anti-cancer, anti-atherogenic and anti-diabetic effects. The effects of CLA are similar to those seen with ligands for peroxisome proliferator-activated receptor (PPARs), most notably of the PPAR gamma subtype. With the recent observation of a role for PPAR gamma in regulation of immune responses, we suspected that CLA could affect immune function, in particular macrophage activity. The goal of our study was to examine whether this dietary fatty acid has anti-inflammatory properties similar to those reported for PPAR gamma activators such as 15-deoxy prostaglandin J(2) (PGJ(2)). In reporter assays, various CLA isomers activated PPAR gamma in RAW264.7 mouse macrophage (RAW) cells. CLA decreased the interferon-gamma (IFN gamma)-induced mRNA expression of mediators of inflammation including cyclooxygenase 2 (COX2), inducible NOS (iNOS), and tumor necrosis factor alpha (TNFalpha). Reporter assays also demonstrated reduced IFN gamma-stimulated transcriptional activity of the iNOS and COX2 promoters by CLA. Consequently, CLA decreased the production of PGE(2), TNFalpha and the inflammatory agent nitric oxide (NO) in RAW cells treated with IFN gamma. Other pro-inflammatory cytokines such as IL-1 beta and IL-6 were similarly decreased by CLA treatment of RAW cells. In addition, various CLA isomers induced HL60 cell differentiation along the monocytic lineage as assessed by measuring expression of the cell surface marker CD14. This differentiation process, as well as the regulation of iNOS and COX2 by 15dPGJ(2), is believed to involve PPAR gamma. Mutations of Leu(468) and Glu(471) to alanine in helix 12 of the ligand-binding domain of PPAR gamma resulted in a protein with strong dominant-negative activity (dnPPAR gamma). Transfecting dnPPAR gamma into RAW cells eliminated the ability of various CLA isomers to regulate the iNOS reporter construct. Taken together, these results suggest that CLA has anti-inflammatory properties that are mediated, at least in part, by the nuclear hormone receptor PPAR gamma.

Amino Acid Substitution↗