Search PubMed⌕ Search

Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 55 records · Page 3Linked to original sources
PubMed2001

Eosinophil peroxidase catalyzes bromination of free nucleosides and double-stranded DNA.

Chronic parasitic infections are a major risk factor for cancer development in many underdeveloped countries. Oxidative damage of DNA may provide a mechanism linking these processes. Eosinophil recruitment is a hallmark of parasitic infections and many forms of cancer, and eosinophil peroxidase (EPO), a secreted hemoprotein, plays a central role in oxidant production by these cells. However, mechanisms through which EPO may facilitate DNA oxidation have not been fully characterized. Here, we show that EPO effectively uses plasma levels of bromide as a cosubstrate to brominate bases in nucleotides and double-stranded DNA, forming several stable novel brominated adducts. Products were characterized by HPLC with on-line UV spectroscopy and electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS). Ring assignments for brominated purine bases as their 8-bromo adducts were identified by NMR spectroscopy. Using stable isotope dilution LC/ESI/MS/MS, we show that while guanine is the preferred purine targeted for bromination as a free nucleobase, 8-bromoadenine is the major purine oxidation product generated following exposure of double-stranded DNA to either HOBr or the EPO/H(2)O(2)/Br(-) system. Bromination of nucleobases was inhibited by scavengers of hypohalous acids such as the thioether methionine, but not by a large molar excess of primary amines. Subsequently, N-monobromoamines were demonstrated to be effective brominating agents for both free nucleobases and adenine within intact DNA. A rationale for selective modification of adenine, but not guanine, in double-stranded DNA based upon stereochemical criteria is presented. Collectively, these results suggest that specific brominated DNA bases may serve as novel markers for monitoring oxidative damage of DNA and the nucleotide pool by brominating oxidants.

Adenine↗
PubMed2001

Cartilage matrix resorption in skeletogenesis.

Chondrocytes assemble an extracellular matrix in which the relative composition of type IX versus type II collagen and aggrecan changes during assembly. On maturation and differentiation into hypertrophic cells type IX collagen first loses the NC4 globular domain of the alpha 1(IX) chain that protrudes from the collagen fibril. Subsequently, collagenase 3 (matrix metalloproteinase 13; MMP13) is up-regulated as type X collagen is expressed leading to extensive cleavage and removal of type II collagen and of the remaining COL2 domain of type IX collagen alpha 1(IX) chain. The proteoglycan aggrecan is selectively retained in the extracellular matrix. Inhibition of collagenase leads to arrest of hypertrophy as well as gene expression of MMP13. Thus proteolysis and in particular MMP13 are required for chondrocyte differentiation and for matrix resorption in skeletal development.

Animals↗
PubMed2001

Lysophospholipids increase interleukin-8 expression in ovarian cancer cells.

OBJECTIVES: We have previously described that bioactive lysophospholipids-lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and sphingosylphosphorylcholine (SPC)-are present in ascitic fluids from patients with ovarian cancer. To understand the role of these lipids in ovarian cancer, we investigated the effects of these lipids on interleukin-8 (IL-8) production in ovarian cancer cells. IL-8 is a proinflammatory and proangiogenic factor, which is potentially involved in ovarian cancer development. METHODS: The Clontech PCR-Select cDNA subtraction method (Clontech Laboratories, Inc., Palo Alto, CA) was used to identify genes potentially regulated by LPA in HEY and OCC1 ovarian cancer cell lines. Northern blot analysis was used to confirm and examine IL-8 mRNA regulation by lysolipids. Enzyme-linked immunosorbent assay (ELISA) was used for detecting secreted IL-8. RESULTS: We describe here that LPA, S1P, and SPC increased mRNA levels (2- to 7-fold) and protein secretion (2- to 12-fold) of IL-8 from ovarian cancer cells (HEY, OCC1, and SKOV3) in vitro. These regulations were both dose- and time-dependent. All three lipids increased the stability IL-8 mRNA in HEY cells. In contrast to malignant ovarian cancer cells, immortalized human ovarian epithelial cells did not respond to any of these lipids to increase the secretion of IL-8, although these cells secreted similar basal levels of IL-8 (310 pg/ml/10,000 cells). Two breast cancer cell lines (MCF7 and T47D) secreted lower basal levels of IL-8 (48-80 pg/ml/10,000 cells), compared with ovarian cancer cells (200-500 pg/ml/10,000 cells). MCF7 cells responded to LPA, but not S1P and SPC, by increasing the secretion of IL-8. T47D and MCF10A, an immortalized breast cell line, did not respond to LPA, S1P, or SPC to increase IL-8 secretion. CONCLUSIONS: LPA, S1P, and SPC regulate the mRNA and protein levels of the proinflammatory and proangiogenic factor IL-8 in ovarian cancer cells. The pathological significance of these regulations in ovarian cancer remains to be further investigated.

Dose-Response Relationship, Drug↗
PubMed2001

Non-invasive lobular carcinoma within a fibroadenoma, a preoperatively diagnosed case.

Breast cancer within a fibroadenoma is rare and usually diagnosed postoperatively from pathological specimens. This paper reports a 54-year-old female with non-invasive carcinoma within a fibroadenoma, diagnosed preoperatively. She underwent a medical examination and mastopathy was suspected. On physical examination a mass 2 cm in diameter was palpated in the left breast. Ultrasonography showed a mass with smooth margins and uniform internal echoes, but cytology showed malignancy. Mammography showed a round mass with distinct margins and no calcification. As fibroadenoma, diagnosed by ultrasonography and mammography, and breast cancer, diagnosed by cytology, were not consistent results several core biopsies were performed. Needle biopsy showed proliferation of atypical epithelial cells; breast cancer within a fibroadenoma was diagnosed. MRI showed a circular mass with distinct, smooth margins and in a dynamic study, the mass showed irregular staining and the presence of early staining. Left lumpectomy and dissection of the left axillary lymph nodes was performed. Histological examination showed non-invasive lobular carcinoma occurring within a fibroadenoma.

Biopsy, Needle↗
PubMed2001

Uncoupling of ATP-induced inositol phosphate formation and Ca(2+) mobilization by phorbol ester in canine cultured tracheal epithelial cells.

The regulation of the increase in inositol phosphates (IPs) production and intracellular Ca(2+) concentration ([Ca(2+)](i)) by protein kinase C (PKC) was investigated in canine cultured tracheal epithelial cells (TECs). Pretreatment of TECs with phorbol 12-myristate 13-acetate (PMA, 1 microM) for 30 min attenuated the ATP- and UTP-induced IPs formation and Ca(2+) mobilization. The concentrations of PMA that gave half-maximal (EC(50)) inhibition of ATP- and UTP-induced IPs accumulation and an increase in [Ca(2+)](i) were 5-10 and 4-12 nM, respectively. Prior treatment of TECs with staurosporine (1 microM), a PKC inhibitor, partially inhibited the ability of PMA to attenuate ATP- and UTP-induced responses, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. Furthermore, analysis of cell extracts by Western blotting with antibodies against different PKC isozymes revealed that TECs expressed PKC-alpha, -betaI, -betaII, -gamma, -delta, -epsilon, -theta, and -zeta. With PMA treatment of the cells for various times, translocation of PKC-alpha, -betaI, -betaII, -gamma, -delta, -epsilon, and -theta from the cytosol to the membrane was seen after 5- and 30-min and 2- and 4-h treatment. However, 6-h treatment caused a partial down-regulation of these PKC isozymes. PKC-zeta was not significantly translocated and down-regulated at any of the times tested. In conclusion, these results suggest that activation of PKC may inhibit the phosphoinositide (PI) hydrolysis and consequently attenuate the [Ca(2+)](i) increase or inhibit independently both responses to ATP and UTP. The translocation of PKC-alpha, -betaI, -betaII, -delta, -epsilon, -gamma, and -theta induced by PMA caused an attenuation of ATP- and UTP-induced IPs accumulation and Ca(2+) mobilization in TECs.

Adenosine Triphosphate↗
PubMed2001

Fuzzy clustering of gait patterns of patients after ankle arthrodesis based on kinematic parameters.

Kinematic parameters for 10 normal subjects and 10 patients with ankle arthrodesis are grouped using the fuzzy cluster paradigm. The features chosen for clustering are Euler angles of the sagittal plane in the hindfoot, the forefoot and combined hindfoot and forefoot joints. Gait patterns are identified using information provided by cluster validity techniques, giving three, three and two clusters for the hindfoot, forefoot and combined hindfoot and forefoot joints, respectively. The cluster centers represent distinct walking strategies adopted by normal subjects and patients after ankle arthrodesis. Utilizing angle values normalized by gait cycle, it is possible to classify any subject and to generate an individual's membership value for each of the clusters. The clinical utility of the fuzzy clustering approach is demonstrated with data for subjects with ankle arthrodesis, where changes in membership of the clusters provide an objective technique for measuring changes of gait pattern after ankle arthrodesis. This approach can be adopted to study other clinical entities where different cluster centers would be established using the algorithm provided in this study.

Adult↗
PubMed2001

Cultivation of Bacillus thuringiensis in an airlift reactor with wire mesh draft tubes.

An aeration strategy was proposed for foam control in an airlift reactor with double wire mesh draft tubes. The airlift reactor was employed in the cultivation of Bacillus thuringiensis for thuringiensin production. The aeration strategy involved two situations. If the foam rose and touched the foam probe, the air flow rate was dropped to a low value for a certain period. However, if the DO value was already below 10% of the saturation when the air flow rate was dropped, the conventional foam control was employed. The production of thuringiensin based on the proposed strategy was up to 70% higher than that of using the conventional cultivation method with addition of antifoam agents for foam control.

Journal Article↗
PubMed2001

Five new insecticidal sesquiterpenoids from Celastrus angulatus.

Five new sesquiterpene polyol esters were isolated from the root bark of Celastrus angulatus by bioassay-guided fractionation. Their structures were determined by spectral data interpretation as 1alpha,2alpha,6beta,8beta,13-pentaacetoxy-9beta-benzoyloxy-4beta-hydroxy-beta-dihydroagarofuran (1), 1alpha,2alpha,6beta-triacetoxy-8alpha-(beta-furancarbonyloxy)-9beta-benzoyloxy-13-isobutanoyloxy-4beta-hydroxy-beta-dihydroagarofuran (2), 1alpha,2alpha,6beta-triacetoxy-8beta-isobutanoyloxy-9beta-(beta-furancarbonyloxy)-13-(alpha-methyl)butanoyloxy-4beta-hydroxy-beta-dihydroagarofuran (3), 1alpha,2alpha,6beta-triacetoxy-8alpha,13-diisobutanoyloxy-9beta-benzoyloxy-4beta-hydroxy-beta-dihydroagarofuran (4), and 1alpha,2alpha,6beta-triacetoxy-8alpha-isobutanoyloxy-9beta-benzoyloxy-13-(alpha-methyl)butanoyloxy-4beta-hydroxy-beta-dihydroagarofuran (5). Compounds 1-5 exhibited insecticidal activity against the larval of Mythimna separata.

Animals↗
PubMed2001

Studies on the clinical efficacy and pharmacokinetics of low-dose arsenic trioxide in the treatment of relapsed acute promyelocytic leukemia: a comparison with conventional dosage.

Twenty cases of patients with relapsed acute promyelocytic leukemia (APL) were entered into this study for evaluating the clinical efficacy and pharmacokinetics of low-dose arsenic trioxide (As2O3). As2O3 was given at a daily dose of 0.08 mg/kg intravenously for 28 days. Pharmacokinetic study was carried out in eight patients. 16/20 (80%) patients achieved CR. The occurrence of some toxic events including gastrointestinal disturbance, facial edema and cardiac toxicity seemed reduced in the low-dose group than those in the standard-dose group. Differentiation changes were observed in peripheral blood, as well as in bone marrow (BM). Pharmacokinetic study showed that the plasma concentration increased soon after administration of As2O3 with the peak values of 1.535-3.424 micromol/l. After infusion, the plasma concentration was around 0.1-0.5 micromol/l. The arsenic concentration of the plasma of BM aspirates 24 h after administration in five patients was close to the level needed for differentiation-inducing effect. The estimated 2-year OS and RFS were 61.55+/-15.79% and 49.11+/-15.09% respectively, with no difference as compared with those in patients treated with conventional dose (P = 0.2865 and 0.7146, respectively). In conclusion, we demonstrated that low-dose As2O3 had the same effect as the conventional dosage and the mechanism of low-dose arsenic seemed to primarily induce differentiation of APL cells.

Adolescent↗
PubMed2001

Neuroprotective effects in gerbils of spiramine T from Spiraea japonica var. acuta.

The neuroprotective effects of spiramine T, an atisine-type diterpenoid alkaloid isolated from the Chinese herbal medicine Spiraea japonica var. acuta (Rosaceaee), on cerebral ischemia-reperfusion injury produced by 10-min bilateral occlusion of the common carotid arteries followed by 5-day reperfusion in gerbils were investigated. Intravenous spiramine T (0.38, 0.75, and 1.5 mg.kg-1) markedly reduced the stroke index, enhanced the recovery of EEG amplitude during reperfusion and decreased the concentrations of cortex calcium and LPO in a dose-dependent manner. However, no significant effects on water and sodium contents were observed. These results suggested that spiramine T exhibited protective effects on cerebral ischemia-reperfusion injury in gerbils, and its mechanism might be related to reducing calcium accumulation and lipid peroxidation. This is the first report on spiramine T as a natural product with neuroprotective effects.

Animals↗
PubMed2001

Detection of sequence variations in the adenomatous polyposis coli (APC) gene using denaturing high-performance liquid chromatography.

We have evaluated the usefulness of denaturing high performance liquid chromatography (dHPLC) for scanning the adenomatous polyposis coli (APC) gene for point mutations, small deletions, and insertions. Our assay consists of 28 sets of primers to amplify the 15 exons of the APC gene. All PCR reactions were amplified simultaneously using the same reaction conditions in a 96-well format and then analyzed by dHPLC, using empirically determined optimum temperatures for partial fragment denaturation. Previously studied DNA specimens from 47 familial adenomatous polyposis (FAP) patients were analyzed by dHPLC and all mutations were correctly identified and confirmed by sequence analysis. This approach identified a single-base substitution in exon 6 and a 2-bp insertion in exon 15 that initially had not been detected by single-strand conformational polymorphism (SSCP) analysis. A novel mutation in exon 15 of the APC gene, 2065delG (codon 689) that had previously been undetected by the protein truncation test (PTT) was also identified by dHPLC. We present our validation studies of dHPLC technology for APC gene analysis in terms of sensitivity and specificity and compare it to current standard scanning technologies including PTT, SSCP, and conformational sensitive gel electrophoresis (CSGE).

Adenomatous Polyposis Coli↗
PubMed2001

Evolution of nuclear- and mitochondrial-encoded subunit interaction in cytochrome c oxidase.

Mitochondrial DNA (mtDNA)-encoded proteins function in eukaryotes as subunits of respiratory complexes that also contain nuclear DNA (nDNA)-encoded subunits. The importance of functional interactions between mtDNA- and nDNA-encoded proteins was previously demonstrated by testing the survivability of cybrid cells or individuals containing nDNA and mtDNA from different populations or species. This report focuses on the multisubunit respiratory complex cytochrome c oxidase (COX), made up of both mtDNA-encoded and nDNA-encoded subunits. A combination of evolutionary and crystallographic data is employed to determine whether rates of nonsynonymous substitutions have been higher, the same, or lower for residues in close proximity that are encoded by a different genome (nDNA or mtDNA). This determination is performed by simply taking the ratio, called the interaction ratio i, of the nonsynonymous substitution rate of the close-contact residues to the nonsynonymous substitution rate of the noncontact residues. We assume that the close-contact residues (which are more likely to interact) are functionally important and that, therefore, amino acid replacements among these residues cannot escape the scrutiny of natural selection. i = 1 indicates that the close-contact residues have been under neither greater purifying selection nor greater positive selection than the noncontact residues as a specific consequence of their being encoded by separate genomes. i < 1 indicates that the close-contact residues have been under greater purifying selection but less positive selection than have the noncontact residues. Conversely, i > 1 indicates that the close-contact residues have been under less purifying but greater positive selection than have the noncontact residues. i < 1 may be referred to as a constraining interaction; i.e., the close-contact residues compared with the noncontact residues appear to be under greater structural-functional constraints. On the other hand, i > 1 may be referred to as an optimizing interaction; i.e., apparently many different amino acid replacements are required to optimize this subunit's interaction with the other subunit. A major finding is that the nDNA-encoded residues in close physical proximity to mtDNA-encoded residues evolve more slowly than the other nuclear-encoded residues (and thus display a constraining interaction), whereas the mtDNA-encoded residues in close physical proximity to nDNA-encoded residues evolve more rapidly than the other mitochondrial-encoded residues (and thus display an optimizing interaction). A possible reason for this striking difference between the nuclear- and mitochondrial-encoded COX subunits in how their functional interaction evolves is discussed.

Amino Acid Substitution↗
PubMed2001

Activation of the EGF receptor signaling pathway in airway epithelial cells exposed to Utah Valley PM.

Exposure to ambient particulate matter (PM) in the Utah Valley has previously been associated with a variety of adverse health effects. To investigate intracellular signaling mechanisms for pulmonary responses to Utah Valley PM inhalation, human primary airway epithelial cells were exposed to aqueous extracts of PM collected from the year before (Y1), during (Y2), and after (Y3) the closure of a local steel mill located in the Utah Valley in this study. Transfection with kinase-deficient extracellular signal-regulated kinase (ERK) 1 constructs partially blocked Utah Valley PM-induced interleukin (IL)-8 promoter reporter activity. The mitogen-activated protein kinase/ERK kinase (MEK) activity inhibitor PD-98059 significantly abolished IL-8 released in response to Utah Valley PM, as did the epidermal growth factor (EGF) receptor kinase inhibitor AG-1478. Western blotting showed that Utah Valley PM induced phosphorylation of EGF receptor tyrosine, MEK1/2, and ERK1/2, which could be ablated with AG-1478 or PD-98059. For all findings, the potency of Utah Valley PM collected during Y2 was found to be lower relative to that of Y1 and Y3. These data demonstrate that Utah Valley PM can induce IL-8 expression partially through the activation of the EGF receptor signaling.

Air Pollutants, Occupational↗
PubMed2001

Degeneration of capsaicin-sensitive sensory nerves leads to increased salt sensitivity through enhancement of sympathoexcitatory response.

We have previously shown that neonatal degeneration of capsaicin-sensitive sensory nerves renders a rat responsive to a salt load with an increase in blood pressure and a decrease in natriuretic response. To test the hypothesis that the enhanced sympathoexcitatory response to a high salt intake contributes to the development of hypertension in this model, newborn Wistar rats were given 50 mg/kg capsaicin and/or 80 mg/kg guanethidine subcutaneously. Control rats were treated with vehicle. After the weaning period, male rats were grouped as the following and given a high sodium diet (4%) for 2 weeks: capsaicin and guanethidine coadministration (CAP-GUA), capsaicin only (CAP), guanethidine only (GUA), and vehicle control (CON). Norepinephrine concentrations in the atrium were significantly lower in CAP-GUA and GUA than in CON rats (P<0.05). Twenty-four-hour urine and sodium excretions were significantly lower in CAP than in CAP-GUA, GUA, and CON rats (P<0.05). Mean arterial pressure (mm Hg) was significantly higher in CAP (180+/-10) than in CAP-GUA (106+/-1), GUA (133+/-5), and CON (122+/-3) rats (P<0.05). Thus, sympathectomy restores the natriuretic response to a high salt intake and prevents the development of salt-sensitive hypertension induced by sensory denervation. These data indicate that sensory nerves counterbalance the prohypertensive effect of the sympathetic nerves to maintain blood pressure within normal range during salt loading.

Animals↗
PubMed2001

Postnatal expression in hyaline cartilage of constitutively active human collagenase-3 (MMP-13) induces osteoarthritis in mice.

It has been suggested that increased collagenase-3 (MMP-13) activity plays a pivotal role in the pathogenesis of osteoarthritis (OA). We have used tetracycline-regulated transcription in conjunction with a cartilage-specific promoter to target a constitutively active human MMP-13 to the hyaline cartilages and joints of transgenic mice. Postnatal expression of this transgene resulted in pathological changes in articular cartilage of the mouse joints similar to those observed in human OA. These included characteristic erosion of the articular cartilage associated with loss of proteoglycan and excessive cleavage of type II collagen by collagenase, as well as synovial hyperplasia. These results demonstrate that excessive MMP-13 activity can result in articular cartilage degradation and joint pathology of the kind observed in OA, suggesting that excessive activity of this proteinase can lead to this disease.

Animals↗
PubMed2001

Social isolation stress impairs the resistance of mice to experimental liver metastasis of murine colon 26-L5 carcinoma cells.

Our previous study has demonstrated that the exposure of male BALB/c mice to social isolation stress caused a suppressed immune response and enhanced liver metastasis of colon 26-L5 carcinoma cells. To more precisely understand the influence of psychosocial factors on the metastatic process, here we have investigated the effect of social isolation stress on the vulnerability of the host to develop liver metastasis of colon 26-L5 cells, including the time span and incidence of metastatic formation, survival time and chemotherapy response. Isolation stress decreased the time period required for the metastasis formation relative to that in controls. On day 7 after the tumor injection, the 75% incidence of tumor metastasis in the stressed mice was 5 times the 15% incidence in the unstressed mice. When exposed to the challenge of lower cell numbers (0.025, 0.05, 0.1 x 10(4)/mouse) of colon 26-L5 cells, mice subjected to isolation stress developed an elevated incidence of metastasis (33.3, 66.6, and 100%, respectively) as compared with the controls (0, 33.3 and 50%, respectively). The survival time following the tumor inoculation was also shorter in the stressed mice (21.83 +/- 1.59d) than in the control mice (24.08 +/- 1.68 d). Furthermore, the response of liver metastasis to chemotherapy consisting of 2 mg/kg cisplatin (CDDP) was worse in the stressed mice than that in unstressed mice. These findings suggested that social isolation stress could significantly impair the resistance of mice to the development of metastasis.

Animals↗
PubMed2001

Isoflurane aggravates the decrease of phosphatidycholine synthesis in alveolar type II cells induced by hydrogen peroxide.

The influence of isoflurane (Iso) on the synthesis and secretion of phosphatidylcholine (PC) of alveolar type II cells (AT II cells) injured by hydrogen peroxide (H2O2) was investigated. After primary culturing for 32 h, AT II cells isolated and purified from adult Sprague-Dawley rats were randomly divided into six groups: control group, 02.8 mM Iso group, 2.8 mM Iso group, 75 microM H2O2 group, 75 microM H2O2 + 0.28 mM Iso group, and 75 microM H202 + 2.8 mM Iso group. Synthesis and secretion of phosphatidylcholine (PC) were detected by 3H-choline chloride incorporation. It was found that 0.28 mM and 2.8 mM Iso significantly reduced PC synthesis compared with the control group (p <0.05, p <0.01, respectively), but not PC secretion. 75 microM H2O2 markedly decreased the synthesis and secretion of PC in AT II cells compared with the control group (p <0.01). 0.28 mM and 2.8 mM Iso aggravated the decrease of PC synthesis induced by H2O2 (p <0.05, p <0.01, respectively), but did not affect PC secretion. These findings suggest that Iso itself may inhibit the synthesis of PC of AT II cells in vitro and further damage the cells' function under peroxidation.

Anesthetics, Inhalation↗