Measurement of the Lambdab0 lifetime using semileptonic decays

We report a measurement of the Lambda(b)(0) lifetime using a sample corresponding to 1.3 fb(-1) of data collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. The Lambda(b)(0) baryon is reconstructed via the decay Lambda(b)(0)-->micronuLambda(c)(+)X. Using 4437+/-329 signal candidates, we measure the Lambda(b)(0) lifetime to be tau(Lambda(b)(0))=1.290(-0.110)(+0.119)(stat)(-0.091)(+0.087)(syst) ps, which is among the most precise measurements in semileptonic Lambda(b)(0) decays. This result is in good agreement with the world average value.

Properties of L=1 B(1) and B(2)* mesons

This Letter presents the first strong evidence for the resolution of the excited B mesons B(1) and B(2)* as two separate states in fully reconstructed decays to B(+)(*)pi(-). The mass of B(1) is measured to be 5720.6+/-2.4+/-1.4 MeV/c(2) and the mass difference DeltaM between B(2)* and B(1) is 26.2+/-3.1+/-0.9 MeV/c;{2}, giving the mass of the B(2)* as 5746.8+/-2.4+/-1.7 MeV/c(2). The production rate for B(1) and B(2)* mesons is determined to be a fraction (13.9+/-1.9+/-3.2)% of the production rate of the B+ meson.

Measurement of the Lambda b lifetime in the exclusive decay Lambda b --> J/psi Lambda

We have measured the Lambda b lifetime using the exclusive decay Lambda b --> J/psi Lambda, based on 1.2 fb(-1) of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda b decays, where the J/psi and Lambda are identified via the decays J/psi --> mu+ mu- and Lambda --> ppi, we measured the Lambda b lifetime to be tau(Lambda b)=1.218 (+0.130)/(-0.115) (stat) +/- 0.042(syst) ps. We also measured the B0 lifetime in the decay B0 --> J/psi(mu+ mu-)K(0)/(S)(pi+ pi-) to be tau(B0)=1.501 (+0.078)/(-0.074) (stat) +/- 0.050(syst) ps, yielding a lifetime ratio of tau(Lambda b)/tau(B0)=0.811 (+0.096)/(-0.087) (stat) +/- 0.034(syst).

Surveillance mammography after breast conservation therapy in Hong Kong: effectiveness and feasibility of risk-adapted approach

Annual surveillance mammography is commonly recommended after breast conservation therapy (BCT). We retrospectively reviewed its effectiveness on 511 invasive and non-invasive breast cancers treated with BCT between 1994 and 2003. The median follow-up was 5.9 years. The 5-year actuarial ipsilateral breast tumour recurrence (IBTR) rate was 4.5% and contralateral breast cancer (CBC) rate was 2.0% (representing eight times increase in risk). IBTR of 43% and 62% CBC were first detected by surveillance mammography. The IBTR detection rates per 1000 mammograms were 5.2 for patients (n=349) with one or more IBTR risk factors (age 45, positive/close margins or histological grade 3) and 0.6 for patients (n=162) without. No survival difference was observed between different modes of IBTR detection (p=0.342). In conclusion, a risk-adapted approach of limiting ipsilateral surveillance to patients with IBTR risk is possible but its implementation will be complicated by the continued need of contralateral surveillance.

Search for stopped gluinos from pp collisions at square root s = 1.96 TeV

Long-lived, heavy particles are predicted in a number of models beyond the standard model of particle physics. We present the first direct search for such particles' decays, occurring up to 100 h after their production and not synchronized with an accelerator bunch crossing. We apply the analysis to the gluino (g), predicted in split supersymmetry, which after hadronization can become charged and lose enough momentum through ionization to come to rest in dense particle detectors. Approximately 410 pb(-1) of pp collisions at square root(s) = 1.96 TeV collected with the D0 detector during Run II of the Fermilab Tevatron collider are analyzed in search of such "stopped gluinos" decaying into a gluon and a neutralino (chi(1)(0)). Limits are placed on the (gluino cross section) x (probability to stop) x [BR(g --> g chi(1)(0))] as a function of the gluino and chi(1)(0) masses, for gluino lifetimes from 30 micros-100 h.

Evaluation of the prognostic value of 2005 St Gallen risk categories for operated breast cancers in Hong Kong

Incorporating various new and conventional risk factors, the 2005 St Gallen risk categorization is a potentially useful prognostic tool for breast cancers. We conducted a retrospective study to evaluate its application in Hong Kong. Of the 902 included female breast cancers with median follow-up of 5.4 years, 7%, 63% and 30% patients were classified as low-, intermediate- and high-risk categories, respectively. Their corresponding 5-year distant disease-free survivals (DDFS) were 100%, 92% and 72%, respectively (p<0.00005). In the intermediate-risk category, node-positive patients had marginally inferior 5-year DDFS than node-negative patients (89% vs. 93%, p=0.0551). In the high-risk category, patients having HER2 overexpressed tumors and 1-3 positive nodes had significantly better DDFS than other patients with > or = 4 positive nodes (89% vs. 65%, p=0.0001). Overall, the 2005 St Gallen risk categorization had high prognostic value. However, the impact of HER2 overexpression might be affected by reproducibility of HER2 tests.

Improving general practitioners' interviewing skills in managing patients with depression and anxiety: a randomized controlled clinical trial

BACKGROUND

Studies regarding the effectiveness of CME programmes on physicians' behaviour and communication skills showed inconsistent results. Few randomized controlled trials have been conducted in Asia.

METHODS

To evaluate the effectiveness of a 4 2-hour education programme to improve GP interviewing behaviours, 16 general practitioners were randomized to the intervention and control groups, respectively. Physicians assigned to the intervention group received 8 hours of training emphasizing interviewing behaviours in the diagnosis and treatment of depression and generalized anxiety disorders (GDS). Those assigned to the control group did not receive any training until the completion of study. Standardized patients were used to evaluate the performance of physicians. Two consultations before and after enrolling in the education programme were videotaped. Independent evaluations of consultations were made by a trained clinical psychologist and a social worker blinded to the study status of physicians. The rating schedule for the videotapes was based on the tasks listed on the Calgary Cambridge Observation Guide.

RESULTS

The change of score between the intervention and control physicians was significantly different in 'active listening and facilitating patients' response' (p = 0.011) with the intervention physicians having improvement of score. For 'non-verbals', 'understanding patient's perspective' and 'negotiating mutual plan of action', positive change of score in the intervention physicians were seen when compared to that of the control, although the difference did not reach statistical significance (p = 0.06, p = 0.05, p = 0.06, respectively). However, for 'opening', 'structuring the consultation', 'explanation and planning' and 'closure', there were no statistical significant differences between control and intervention group.

CONCLUSIONS

Our results showed that only certain communication skills, such as active listening and facilitating patient's response, can be taught in the management of depression and generalized anxiety disorder (GAD) in Chinese primary care physicians.

Search for third-generation scalar leptoquarks in pp at square root s=1.96 TeV

We report on a search for charge-1/3 third-generation leptoquarks (LQ) produced in pp collisions at square root s =1.96 TeV using the D0 detector at Fermilab. Third-generation leptoquarks are assumed to be produced in pairs and to decay to a tau neutrino and a b quark with branching fraction B. We place upper limits on sigma(pp --> LQLQ)B2 as a function of the leptoquark mass M(LQ). Assuming B=1, we exclude at the 95% confidence level third-generation scalar leptoquarks with M(LQ)<229 GeV.

Direct observation of the strange b baryon Xib-

We report the first direct observation of the strange b baryon Xi(b)- (Xi(b)+). We reconstruct the decay Xi(b)- -->J/psiXi-, with J/psi-->mu+mu-, and Xi--->Lambdapi--->ppi-pi- in pp collisions at square root of s =1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(b)- candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psiLambda, we measure the relative rate sigma(Xi(b-) x B(Xi)b})- -->J/psiXi-)/sigma(Lambda(b)) x B(Lambda(b)-->J/psiLambda) = 0.28+/-0.09(stat)(-0.08)(+0.09)(syst).

Clinical Outcome of Breast Conservation Therapy for Breast Cancer in Hong Kong: Prognostic Impact of Ipsilateral Breast Tumor Recurrence and 2005 St. Gallen Risk Categories

PURPOSE

The aim of this study was to evaluate the clinical outcome of breast conservation therapy (BCT) for invasive breast cancers in our predominantly Chinese population.

METHODS AND MATERIALS

Clinical outcomes of 412 T1-2 invasive breast cancers treated by wide local excision and external radiotherapy from 1994 to 2003 were retrospectively analyzed. Only 7% lesions were first detected by mammograms. Adjuvant tamoxifen and chemotherapy were added in 74% and 45% patients, respectively.

RESULTS

The median follow-up was 5.4 years. The 5-year actuarial ipsilateral breast tumor recurrence (IBTR) rate, distant failure-free survival, cause-specific survival, and overall survival were 4%, 92%, 96%, and 98%, respectively. The 5-year distant failure-free survival for the low-risk, intermediate-risk, and high-risk categories (2005 St. Gallen) were 98%, 91%, and 80%, respectively (p = 0.0003). Cosmetic results were good to excellent in more than 90% of the assessable patients. Grade 3 histology (hazard ratio [HR], 4.461; 95% CI, 1.216-16.360; p = 0.024), age (HR, 0.915; 95% CI, 0.846-0.990; p = 0.027), and close/positive final margins (HR, 3.499; 95% CI, 1.141-10.729; p = 0.028) were significant independent risk factors for IBTR. Both St. Gallen risk categories (p = 0.003) and IBTR (HR, 5.885; 95% CI, 2.494-13.889; p < 0.0005) were independent prognostic factors for distant failure-free survival.

CONCLUSIONS

Despite the low percentage of mammographically detected lesions, the overall clinical outcome of BCT for invasive breast cancers in the Chinese population is comparable to the Western series. The 2005 St. Gallen risk category is a promising clinical tool, but further validation by large studies is warranted.

Validation of the 2005 St. Gallen risk categories for operated breast cancers using a database from a regional cancer center in Hong Kong

11019

Background: Breast cancer risk categories were revised by the St Gallen international expert consensus meeting in 2005. This study was to validate their application in Hong Kong. Methods: The clinical outcomes of female breast cancer patients presented from 1994 to 2002 were retrospectively analyzed. Patients with non-invasive cancers, unknown HER-2 status, unclear primary (T) or nodal (N) stage, distant metastases at presentation, induction chemotherapy or no definitive surgery were excluded. Results: 902 breast cancers were eligible for further analysis. Adjuvant radiotherapy, hormonal therapy and chemotherapy were given in 74%, 68% and 56% of patients respectively. The median follow-up was 5.4 years (range 0.3- 12.5 years). The risk categories were highly predictive of all survival outcome parameters (p<0.00005; Table). In the intermediate risk category, node-negative patients with endocrine responsive/ responsiveness uncertain tumors had better 5-year distant failure-free survival (DFFS) than the rest with either 1–3 positive nodes or endocrine non-responsive tumors (95% vs 89%, p=0.005). Patients with 1–3 positive nodes and HER-2 overexpressed tumors were classified as high risk but their 5-year DFFS was similar to that in the worse subgroup of intermediate risk and significantly better than those with ≥4 positive nodes (89% vs 65%, p=0.0001). Further analysis showed that HER-2 overexpression had adverse impact on DFFS of patients with ≥4 positive nodes (hazard ratios (HR) 1.78; 95% CI, 1.12 - 2.84; p=0.015) but not on those with ≤ 3 positive nodes (HR 1.15; 95% CI, 0.67 - 1.97; p= 0.61). Conclusions: The 2005 St Gallen risk category is a useful clinical tool but we cannot confirm the adverse impact of HER-2 overexpression in our patients with ≤ 3 positive nodes.

[Table: see text]

No significant financial relationships to disclose.

Characterization of the pathogenic mechanism of a novel BRCA2 variant in a Chinese family

10541

Background: Despite the identification of a large number of sequences in BRCA1/2 mutation analyses, many genetic alterations are classified as variants of unknown significance (VUS). Increasing data demonstrates ethnic variation of BRCA mutation. We report a novel BRCA2 VUS in a Chinese family with multiple breast cancers and characterized it as pathogenic by RNA analysis. Method: Peripheral blood was collected from the breast cancer proband and her family who were suspected to have a pathogenic mutation due the segregation of the disease phenotype and the young age of presentation of breast cancer. DNA and RNA was extracted from the blood. The entire coding regions and flanking introns of BRCA1/2 were screened for germline mutations using full gene sequencing and Multiplex Ligation -dependent Probe Amplification. Variant DNA alteration leading to an aberrant BRCA transcript was demonstrated by RT-PCR of the RNA and Polyacrylamide Gel Electrophoresis. Abnormal bands were cloned and direct sequencing conducted. Results: A germline mutation c.7806–9T>G was identified in the proband at the BRCA2 intron 16. This mutation was also found in 3 of her 4 sibling sisters with early breast cancer. The proband's mother harbored the same BRCA2 mutation in DNA extracted from archival gastric tumor tissues. Computational analyses showed that this mutation might give rise to a cryptic splice site for alternative RNA splicing. To confirm the pathogenicity, RT- PCR using specific primers flanking the cryptic splice site and sequencing was performed on RNA extracted from the proband's blood. Four different sizes of transcripts were found: wild type, r.7806_7874del , r.7806_7976del and r.7806–8_7806-lins. The latter 3 aberrant transcripts were not found in the 30 controls therefore polymorphism is unlikely. The r.7806–8_7806-lins transcript caused a frameshift which created a truncated protein; whereas the other two short transcripts produced shorter BRCA2 protein isoforms. Conclusion: We identified a novel BRCA2 VUS and classified it as pathogenic. Classification of VUS as neutral or pathogenic, particularly in ethnic groups where limited knowledge is known is a challenge. Research on the spectrum of mutations in diversed ethnic groups has important implications on management. [Genbank: DQ889340 ]

No significant financial relationships to disclose.

Evaluation of an in-house genotyping resistance test for HIV-1 drug resistance interpretation and genotyping

INTRODUCTION

The human immunodeficiency virus type 1 (HIV-1) genotyping resistance test (GRT) has been considered essential for HIV-1 drug resistance monitoring. However, it is not commonly used in some developing countries in Asia and Africa due to its high running cost.

OBJECTIVE

This study aims to evaluate a new low-cost in-house GRT for both subtype B and non-B HIV-1.

STUDY DESIGN

The in-house GRT sequenced the entire protease and 410 codons of reverse transcriptase (RT) in the pol gene. Its performance on drug resistance interpretation was evaluated against the FDA-approved ViroSeq HIV-1 Genotyping System. Particularly, a panel of 235 plasma samples from 205 HIV-1-infected patients in Hong Kong was investigated. The HIV-1 drug resistance-related mutations detected by the two systems were compared. The HIV-1 subtypes were analyzed through the REGA HIV-1 Genotyping Tool and env phylogenetic analysis.

RESULTS

Among the 235 samples, 229 (97.4%) were successfully amplified by both in-house and ViroSeq systems. All PCR-negative samples harbored viral RNA at <400 copies/mL. The in-house and ViroSeq system showed identical drug resistance-related mutation patterns in 216 out of 229 samples (94.3%). The REGA pol genotyping results showed 93.9% (215/229) concordance with the env phylogenetic results including HIV-1 subtype A1, B, C, D, G, CRF01_AE, CRF02_AG, CRF06_cpx, CRF07_BC, CRF08_BC, CRF15_01B and other recombinant strains. The cost of running the in-house GRT is only 25% of that for the commercial system, thus making it suitable for the developing countries in Asia and Africa.

CONCLUSIONS

Overall, our in-house GRT provided comparable results to those of the commercial ViroSeq genotyping system on diversified HIV-1 subtypes at a more affordable price which make it suitable for HIV-1 monitoring in developing countries.

HIV and ethnicity in Canada: is the HIV risk-taking behaviour of young foreign-born MSM similar to Canadian born MSM?

There is a dearth of information on the HIV risk-taking behaviour of foreign-born men who have sex with men (MSM) in Canada. This study focused on identifying sexual risk behaviour among MSM who immigrated to Canada and compared them to MSM who were born in Canada. Baseline data from the Omega Cohort in Montreal and the Vanguard Project in Vancouver were combined to form four ethnicity/race analytical categories (n = 1,148): White born in Canada (WBIC), White born outside of Canada, non-White born in Canada (NBIC) and non-White born outside of Canada (NBOC). Psychological, demographic and sexual behaviour characteristics of the groups were similar except: NBOC were more likely to be unemployed, less likely to be tattooed, had fewer bisexual experiences and less likely worried of insufficient funds. WBOC were more likely to report unprotected sex with seropositives and more likely to have had unprotected sex while travelling. NBIC were more likely to have ever sold sex and to have had body piercing. WBOC are at high risk of acquiring as well as transmitting HIV. It is important to consider place of birth in addition to ethnicity when developing programmes to prevent the transmission of HIV.

Inadequacies in antiretroviral therapy use among Aboriginal and other Canadian populations

We undertook this study to provide a profile of Aboriginal people initiating antiretroviral therapy and their response to treatment. Aboriginal peoples were identified through self-report. Baseline socio-demographics and risk factors were compared between Aboriginal and non-Aboriginal participants as were baseline factors associated with two consecutive plasma viral load measures below 500 copies/ml using contingency table analysis. Multivariate survival analysis of the prognostic factors associated with time to two consecutive plasma viral load measures below 500 copies/ml among eligible participants was undertaken to characterize response to antiretroviral therapy. There were 892 participants with available data for this analysis, of those 146 (16%) self-identified as Aboriginal. Aboriginal participants were more likely to be female (p < or = 0.001), have lower baseline plasma viral loads (p = 0.010), be co-infected with HCV (p < 0.001), live in unstable housing (p < or = 0.001), and report an income of >10K CDN (p < or = 0.001) per annum. Aboriginal people were less likely to report men who have sex with men (p < or = 0.001) and more likely to report injection drug use (p < or = 0.001) as a risk factor for HIV infection. Aboriginal participants were more likely to receive double versus triple combination antiretroviral therapy (p = 0.002), be less adherent in the first year on therapy (p = 0.001) and to have a physician less experienced with treating HIV (p < or = 0.001). When these factors were controlled for, Aboriginal people treated with triple combination therapy were as likely to respond and suppress their viral load below 500 copies. In the era of HAART, our results indicate that Aboriginal people living with HIV/AIDS were less likely to receive optimal therapy. However, when Aboriginals did receive triple drug therapy they suppressed just as well as non-Aboriginals.

Lifetime difference and CP-violating phase in the Bs0 system

From an analysis of the decay Bs0-->J/psi phi, we obtain the width difference between the light and heavy mass eigenstates DeltaGamma identical with (GammaL-GammaH)=0.17+/-0.09(stat)+/-0.02(syst) ps-1 and the CP-violating phase phis=-0.79+/-0.56(stat)(-0.01)(+0.14)(syst). Under the hypothesis of no CP violation (phis identical with 0), we obtain 1/Gamma=tau(Bs0)=1.52+/-0.08(stat)(-0.03)(+0.01)(syst) ps and DeltaGamma=0.12(-0.10)(+0.08)(stat)+/-0.02(syst) ps-1. The data sample corresponds to an integrated luminosity of about 1.1 fb-1 accumulated with the D0 detector at the Fermilab Tevatron collider. This is the first direct measurement of the CP-violating mixing phase in the Bs0 system.

Statistical study of effective anisotropy field in ordered ferromagnetic nanowire arrays

Soft ferromagnetic nanowire arrays were obtained by electrodeposition of Co-Fe-P alloy into the pores of high quality home-made anodized aluminum oxide (AAO) templates. Bath acidity and current density were the two parameters used in order to tailor the orientation of local anisotropy axes in individual nanowires. In order to quantify the influence of the induced anisotropies on the magnetization processes in individual nanowires, the in-plane magnetization loops of the arrays are modeled as log-normal distributions of Stoner-Wohlfarth transverse magnetization processes. Using the lognormal mean parameter as an approximation for the saturation applied field of the array, we compute the effective anisotropy of the nanowires, which is found to increase with the pH of the electrodeposition bath.

Evaluation of NucliSens EasyQ™ HIV-1 assay for quantification of HIV-1 subtypes prevalent in South-east Asia

BACKGROUND

Monitoring anti-retroviral therapy requires that viral load assays for human immunodeficiency virus type 1 (HIV-1) be applicable to diverse HIV-1 subtypes.

OBJECTIVES

To evaluate NucliSens EasyQ HIV-1 assay for quantitation of common HIV-1 subtypes prevalent in South-east Asia.

STUDY DESIGN

One hundred and nineteen plasma samples collected in Hong Kong and Cambodia were used to compare the performance of NucliSens EasyQ HIV-1 and COBAS Amplicor HIV-1 Monitor version 1.5 assays. Viral RNA extracted from the NucliSens MiniMAG was also used for HIV-1 subtyping.

RESULTS

Performance of NucliSens EasyQ correlated well with COBAS Amplicor (r=0.777, p<0.001) and the small mean difference (0.0462log(10)IU/mL) obtained in the Bland and Altman model indicated good agreement between two assays. The NucliSens EasyQ assay demonstrated a 95% sensitivity at 500IU/mL and 100% specificity. Reproducibility of this assay was within log(10)2-4IU/mL and had a coefficient of variation between 2.3% and 10.4%. Among the 109 specimens included in the analysis, HIV-1 subtyping identified 64 CRF01_AE, 38 subtype B, 3 subtype C, 3 CRF07_BC and 1 subtype G viruses.

CONCLUSIONS

Performance of NucliSens EasyQ was comparable to COBAS Amplicor for HIV-1 viral load monitoring. RNA extracts from NucliSens MiniMAG could be used for HIV-1 viral load monitoring, subtyping and drug resistance mutations detection. Our findings highlight the versatility of both NucliSens EasyQ and COBAS Amplicor in monitoring prevalent subtypes and rare circulating recombinant forms (CRFs) in the South-east Asia region.