Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 55 records · Page 3Linked to original sources

PubMed2005

Activation of CD44 facilitates DNA repair in T-cell lymphoma but has differential effects on apoptosis induced by chemotherapeutic agents and ionizing radiation.

Expression of CD44s (standard form) in malignant lymphoma is a poor indicator of survival. To investigate whether activation of CD44s can protect from cell death, this study compared the extent of apoptosis induced by chemotherapeutic agents and ionizing radiation (IR) on T-lymphoma cell lines in the presence or absence of adherent hyaluronan and monoclonal antibodies (MoAbs). Growth in the presence of adherent ligands enhanced apoptosis induced by dexamethasone (Dex), but protected cells from epirubicin-induced apoptosis. In IR-induced apoptosis, mouse lymphoma cells had resistance against apoptosis when treated with hyaluronan (HA), although acute cell death reached the same plateau regardless of treatment with adherent MoAbs in human lymphoma cell line. However, the post-irradiated repopulation of lymphoma cells was strikingly accelerated in those treated with CD44 adherent ligands. This repopulation process correlated with the remarkable upregulation of proliferating cell nuclear antigen (PCNA), which is a protein involved in DNA repair. Unscheduled DNA synthesis (UDS), a measure of DNA repair, was consistently enhanced in CD44s-stimulated cells after exposure to radiation. The results suggest that the poor prognostic indication of CD44 expression is more a consequence of enhanced DNA repair following genotoxic damage than of direct resistance to apoptosis.

Animals↗

PubMed2005

Investigation of seven Vibrio virulence genes among Vibrio alginolyticus and Vibrio parahaemolyticus strains from the coastal mariculture systems in Guangdong, China.

AIMS: To investigate the distribution of the virulence of two Vibrio species among different strains obtained from the mariculture systems on the coast of Guangdong in China and the correlation between the virulence strains and the virulence genes among Vibrio alginolyticus. METHODS: Besides three strains, 72 V. alginolyticus strains and seven Vibrio parahaemolyticus strains were examined by PCR or semi-nested PCR for the virulence genes (tlh, trh, tdh, toxR, toxRS, ctxA, VPI). Additionally, the virulence of 18 V. alginolyticus strains was tested. SIGNIFICANCE AND IMPACT OF THE STUDY: Virulence genes homologous to those in the V. parahaemolyticus and Vibrio cholerae are widely distributed among V. alginolyticus and V. parahaemolyticus in the coastal mariculture systems in Guangdong, China. Some of the V. alginolyticus strains are pathogenic to aquatic animals, and might have derived their virulence genes from V. parahaemolyticus or V. cholerae, representing a possible reservoir of these genes. However, there is no correlation between presence and absence of the virulence genes used to investigate V. alginolyticus and its virulent strains. In this report, we also show that tlh is distributed among V. alginolyticus.

China↗

PubMed2005

The cytolethal distending toxin induces receptor activator of NF-kappaB ligand expression in human gingival fibroblasts and periodontal ligament cells.

Actinobacillus actinomycetemcomitans is associated with localized aggressive periodontitis, a disease characterized by rapid loss of the alveolar bone surrounding the teeth. Receptor activator of NF-kappaB Ligand (RANKL) and osteoprotegerin (OPG) are two molecules that regulate osteoclast formation and bone resorption. RANKL induces osteoclast differentiation and activation, whereas OPG blocks this process by acting as a decoy receptor for RANKL. The purpose of this study was to investigate the effect of A. actinomycetemcomitans on the expression of RANKL and OPG in human gingival fibroblasts and periodontal ligament cells. RANKL mRNA expression was induced in both cell types challenged by A. actinomycetemcomitans extract, whereas OPG mRNA expression remained unaffected. Cell surface RANKL protein was also induced by A. actinomycetemcomitans, whereas there was no change in OPG protein secretion. A cytolethal distending toxin (Cdt) gene-knockout strain of A. actinomycetemcomitans did not induce RANKL expression, in contrast to its wild-type strain. Purified Cdt from Haemophilus ducreyi alone, or in combination with extract from the A. actinomycetemcomitans cdt mutant strain, induced RANKL expression. Pretreatment of A. actinomycetemcomitans wild-type extract with Cdt antiserum abolished RANKL expression. In conclusion, A. actinomycetemcomitans induces RANKL expression in periodontal connective tissue cells. Cdt is crucial for this induction and may therefore be involved in the pathological bone resorption during the process of localized aggressive periodontitis.

Aggregatibacter actinomycetemcomitans↗

PubMed2005

Serum DDT, age at menarche, and abnormal menstrual cycle length.

BACKGROUND: Although dichlorodiphenyl trichloroethane (DDT) exposure is known to affect human endocrine function, few previous studies have investigated the effects of DDT exposure on age at menarche or menstrual cycle length. METHODS: A cross sectional study was conducted to study the effects of DDT exposure on age at menarche and menstrual cycle length among 466 newly married, nulliparous female Chinese textile workers aged 20-34 years enrolled between 1996 and 1998. Serum was analysed for DDT and its major metabolites. Multivariate linear regression was used to estimate DDT exposure effects on age at menarche and multivariate logistic regression was used to estimate DDT exposure effects on odds of experiencing short or long cycles. RESULTS: Relative to those in the lowest DDT quartile, the adjusted mean age at menarche was younger in those in the fourth quartile (-1.11 years). Modeled as a continuous variable, a 10 ng/g increase in serum DDT concentration was associated with an adjusted reduction in age at menarche of 0.20 years. Relative to those in the lowest DDT quartile, odds of any short cycle (<21 days) in the previous year were higher for those in the fourth quartile (odds ratio = 2.78; 95% CI 1.07 to 7.14). There were no associations between serum DDT concentrations and odds of experiencing a long cycle (>40 days). CONCLUSION: Results suggest that DDT exposure was associated with earlier age at menarche and increased risk of experiencing a shortened menstrual cycle.

Adult↗

PubMed2005

Expression of granulocyte colony stimulating factor receptor in human colorectal cancer.

AIMS: To discover if human colorectal cancer expresses granulocyte colony stimulating factor receptor (G-CSFR) and if granulocyte colony stimulating factor (G-CSF) plays an important part in the development and progression of human colorectal cancer. METHODS: Forty two specimens of colorectal cancer and normal colorectal mucosa were investigated, taken from the colon or rectum in group of colorectal cancer patients. Immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) technique were used to show G-CSFR expression. The relation between expression of G-CSFR and clinical or pathological factors was analysed. RESULTS: Immucohistochemical analyses showed that G-CSFR was expressed in the human colorectal cancer (25 of 42, 59.52%) and seemed to be up-regulated compared with the normal mucosa (14 of 42, 33.33%, p<0.001). In pronounced contrast with mostly strongly positive tumours, corresponding normal colorectal mucosa was negative or weakly positive. A significant correlation was found between G-CSFR expression and tumour stage (p = 0.001), tumour differentiation (p<0.001), but there was no significant relation between the expression of G-CSFR and the age, sex, and tumour size (p = 0.346, p = 0.686, p = 0.459). In RT-PCR, 21 of all 42 tumours had G-CSFR mRNA expression, while only 11 of 42 normal colorectal mucosa had such expression. CONCLUSIONS: These data show that G-CSFR is commonly expressed in human colorectal cancers, thus supporting a possible role for G-CSF in colorectal cancer physiology.

Adolescent↗

PubMed2005

Wire-guided excision of mammographic abnormalities.

OBJECTIVE: A review of wire-guided excision of abnormal lesions viewed on screening mammography. DESIGN. Retrospective review. SETTING: Regional hospital, Hong Kong. PATIENTS: Patients who underwent wire-guided excision of abnormalities visualised on screening mammography between 1999 and 2002. INTERVENTION: Wire-guided excision. MAIN OUTCOME MEASURES: Biopsy rate and positive biopsy rate. RESULTS: A total of 65 patients underwent wire-guided excision of an abnormal lesion previously identified by screening mammography. Twenty-one were benign, two were lobular carcinoma in situ, and 42 were malignant. Of the latter, 30 were identified as ductal carcinoma in situ, and 12 as invasive breast cancer. Thirty-eight of the 42 malignant cases required further treatment, and 24 of them underwent further operation. Radiological assessment of the 65 patients suggested that nine lesions were probably benign, 31 indeterminate, 20 suspicious, and five malignant. Malignancy was subsequently confirmed by histological examination in 6, 20, 13, and 3 cases of the respective group of radiological assessment. CONCLUSION: The biopsy rate was approximately 3.7 per 1000 screened women, with results benign in 1.19 per 1000. The positive biopsy rate was 64.6%, and invasion was evident in 28.6%.

Biopsy↗

PubMed2004

Search for doubly charged Higgs bosons decaying to dileptons in pp collisions at square root of s=1.96 TeV.

We present the results of a search for doubly charged Higgs bosons (H+/-+/-) decaying to dileptons (ll(')) using approximately 240 pb(-1) of pp collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign ll(') mass m(ll('))>80 GeV/c(2) (100 GeV/c(2) for ee channel), we observe no evidence for H+/-+/- production. We set limits on sigma(pp -->H++H---->l(+)l('+)l(-)l('-)) as a function of the mass of the H+/-+/- and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H(+/-+/-)(L) of 133, 136, and 115 GeV/c(2) in the ee, mumu, and emu channels, respectively, and a lower mass limit of 113 GeV/c(2) on H(+/-+/-)(R) in the mumu channel, all at the 95% confidence level.

Journal Article↗

PubMed2004

Inclusive double-pomeron exchange at the fermilab tevatron p p collider.

We report results from a study of events with a double-Pomeron exchange topology produced in p p collisions at sqrt[s]=1800 GeV. The events are characterized by a leading antiproton and a large rapidity gap on the outgoing proton side. We find that the differential production cross section agrees in shape with predictions based on Regge theory and factorization, and that the ratio of double-Pomeron exchange to single diffractive production rates is relatively unsuppressed as compared to the O(10) suppression factor previously measured in single diffractive production.

Journal Article↗

PubMed2004

Measurement of the tt production cross section in pp collisions at sqrt[s]=1.96 TeV using dilepton events.

We report a measurement of the tt production cross section using dilepton events with jets and missing transverse energy in pp collisions at a center-of-mass energy of 1.96 TeV. Using a 197+/-12 pb(-1) data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a tt production cross section of 7.0(+2.4)(-2.1)(stat)+1.6-1.1(syst)+/-0.4(lum) pb.

Journal Article↗

PubMed2004

Observation of the narrow state X(3872)-->J/psipi+pi- in pp collisions at sqaure root of s=1.96 TeV.

We report the observation of a narrow state decaying into J/psipi+pi- and produced in 220 pb(-1) of p p-bar collisions at =1.96 Tesqaure root of sV in the CDF II experiment. We observe 730+/-90 decays. The mass is measured to be 3871.3+/-0.7(stat)+/-0.4(syst) MeV/c2, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.

Journal Article↗

PubMed2004

Inclusive search for anomalous production of high-pT like-sign lepton pairs in pp collisions at square root s = 1.8 TeV.

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with pT > 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV pp collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(+0.84)(-0.07) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta = 3) model.

Journal Article↗

PubMed2004

Search for B0s-->micro+micro- and B0d-->micro+micro- decays in pp collisions at square root s = 1.96 TeV.

We report on a search for B(0)(s)-->micro(+)micro(-) and B(0)(d)-->micro(+)micro(-) decays in pp collisions at square root of s=1.96 TeV using 171 pb(-1) of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of B(B(0)(s)-->micro(+)micro(-))<5.8x10(-7) and B(B(0)(d)-->micro(+)micro(-))<1.5x10(-7) at 90% confidence level.

Journal Article↗

PubMed2004

Search for Kaluza-Klein graviton emission in pp collisions at square root[s] = 1.8 TeV using the missing energy signature.

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb(-1) of ppmacr; collisions at sqrt[s]=1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a (3+1+n)-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for n=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.

Journal Article↗

PubMed2004

Patient preferences for acute pain treatment.

BACKGROUND: Optimal treatment for acute pain is a function of an individual's willingness to make trade-offs between treatment side effects and pain control. The objective was to investigate the degree to which patients are willing to make these trade-offs. METHODS: Fifty patients undergoing major abdominal surgery were enrolled and completed interviews before and after surgery. Measures included an experience with pain questionnaire and an adaptive conjoint analysis (ACA) interview. RESULTS: Percentage of pain relief obtained post-surgery was between 70 and 80%. Eight-two per cent reported at least one moderate or severe side effect. ACA results demonstrated that pain efficacy and side effect type/severity have almost equal 'importance' scores. Patients varied in their willingness to trade-off pain efficacy for different or milder side effects. CONCLUSIONS: We conclude that people have different relative preferences for different side effects and are willing to trade-off pain relief for less upsetting and/or less severe side effects but to different degrees. Thus, physicians should consider offering pain medications with fewer side effects than narcotics as a first choice. Our study indicates the need to balance analgesia and side effects in order for patients to achieve optimal pain control.

Abdomen↗

PubMed2004

Neuromuscular hamartoma arising in the brachial plexus.

We report a case brachial plexus neuromuscular hamartoma (choristoma) in a 28-year-old man who complained of numbness of the left hand and forearm for several years. MRI revealed a circumscribed, rounded mass in the left brachial plexus. The patient is well 2 years after surgery, with no neurological deficit.

Adult↗

PubMed2004

Search for pair production of scalar top quarks in R-parity violating decay modes in pp collisions at square root of s=1.8 TeV.

We present the results of a search for pair production of scalar top quarks (t(1)) in an R-parity violating supersymmetry scenario in 106 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab. In this mode each t(1) decays into a tau lepton and a b quark. We search for events with two tau's, one decaying leptonically (e or mu) and one decaying hadronically, and two jets. No candidate events pass our final selection criteria. We set a 95% confidence level lower limit on the t(1) mass at 122 GeV/c(2) for Br(t(1)-->tau b)=1.

Journal Article↗

PubMed2004

Suppressing effects of bisphenol A on the secretory function of ovine anterior pituitary cells.

We investigated the action of bisphenol A (BPA) on cellular GH release and content, cell number, GHmRNA expression, and concentrations of cellular cyclic AMP ([cAMP]c) and calcium ion ([Ca2+]c) in primary cultured ovine anterior pituitary cells. The following results were found: (1) BPA as well as nonylphenol (NP) at 10(-6) to 10(-3) M significantly and concentration-dependently suppressed basal and GHRH-stimulated GH release, and the cellular GH content, (2) BPA suppressed the cell number in a time- and concentration-dependent manner, (3) 10(-4)M BPA suppressed GHmRNA expression to 68% of control (BPA-free), and abolished GHRH (10(-8) M)-induced increases in [cAMP]c and [Ca2+]c. From these findings we conclude that BPA possesses a suppressing action on GH synthesis and release, and this suppressing action is probably related to impairment of cellular signal transduction systems in ovine anterior pituitary cells.

Animals↗

PubMed2004

Autologous stem cell transplantation in primary systemic amyloidosis: the impact of selection criteria on outcome.

Autologous stem cell transplantation (ASCT) for primary systemic amyloidosis (AL) produces high hematologic and organ responses. However, treatment-related mortality remains high and reported series are subject to selection bias. In all, 48 of 80 amyloid patients referred to our center had AL in the absence of myeloma, 26 of these 48 were deemed transplant candidates and 20 actually underwent ASCT. Transplant-related mortality has fallen from 50 to 20% since January 1999 due to better patient selection and prophylactic measures. Intent-to-treat organ responses were renal (46%), cardiac (25%) and liver (50%). Organ responses in patients who survived transplantation were renal (75%), cardiac (40%) and liver (100%). The 3-year OS post-ASCT was 56% with improved outcome predicted by a better performance status (P=0.08), normal ALP (P=0.08), nephrotic syndrome (P=0.01) and the absence of severe hypotension (P=0.01). The 3-year OS for all referred patients was 44% and this was not significantly better for transplant candidates. Patients with significant hypotension (systolic blood pressure < or =90 mmHg) or poor performance status (ECOG >2) have an exceedingly high treatment-related mortality and should not be transplanted. For those undergoing ASCT, organ response rates appear promising, but conclusive evidence of improved survival for this select group of patients is still lacking and will require randomized trials.

Adult↗