Commissioning and evaluation of a new commercial small rodent x-ray irradiator

An appropriate radiation source is essential in studies of tissue response in animal models. This paper reports on the evaluation and commissioning of a new irradiator suitable for studies using small animals or cell culture. The Faxitron is a 160-kVp x-ray machine that was adapted from an x-ray imaging unit through modifications to facilitate experimental irradiation. The x-ray unit is housed in a shielded cabinet, and is configured to allow multiple irradiation positions and a range of field sizes and dose rates. Use of this machine for animal irradiation requires characterisation of relevant dosimetry, and development of methodology for secondary beam collimation and animal immobilisation. In addition, due to the limitation of the irradiator, the optimal selection of three characteristics of the x-ray beam is important. These three characteristics, namely, the dose rate, the beam uniformity, and the field size are inter-dependent and the selection of a combination of these parameters is often a compromise and is dependent on the application. Two different types of experiments are selected to illustrate the applicability of the Faxitron. The Faxitron could be useful for experimental animal irradiation if the experimental design is carried out carefully to ensure that accurate and uniform radiation is delivered

Growing Older in Hong Kong, New York and London

published_or_final_versio

A tale of three world cities: health care policy implications

Conference Theme: Managing World Citiespublished_or_final_versio

Androgen deprivation therapy and fracture risk in Chinese patients with prostate carcinoma

OBJECTIVE: Androgen deprivation therapy (ADT) increases fracture risk in men with carcinoma of the prostate, but little is known about the fracture risk for different types of ADT. We studied the fracture risk amongst Chinese patients with carcinoma of the prostate prescribed different ADT regimens. SUBJECTS AND METHODS: This was a single-centered observational study that involved 741 patients with carcinoma of the prostate from January 2001 to December 2011. RESULTS: After a median follow-up of 5 years, 71.7% of the study cohort received ADT and the incidence rate of fracture was 8.1%. Multivariable Cox regression analysis revealed that use of ADT was significantly associated with risk of incident fracture (Hazard Ratio [HR] 3.60; 95% Confidence Interval [95% CI] 1.41-9.23; p = 0.008), together with aged >75 years and type 2 diabetes. Compared with no ADT, all three types of ADT were independently associated with the risk of incident fracture: anti-androgen monotherapy (HR 4.47; 95% CI 1.47-13.7; p = 0.009), bilateral orchiectomy ± anti-androgens (HR 4.01; 95% CI 1.46-11.1; p = 0.007) and luteinizing hormone-releasing hormone agonists ± anti-androgens (HR 3.16; 95% CI 1.18-8.43; p = 0.022). However, there was no significant difference in the relative risks among the three types of ADT. CONCLUSIONS: Fracture risk increases among all types of ADT. Clinicians should take into account the risk-benefit ratio when prescribing ADT, especially in elderly patients with type 2 diabetes.published_or_final_versio

Mp1p Is a Virulence Factor in Talaromyces (Penicillium) marneffei

published_or_final_versio

Identification of Trypanosome Proteins in Plasma from African Sleeping Sickness Patients Infected with T. b. rhodesiense

Control of human African sleeping sickness, caused by subspecies of the protozoan parasite Trypanosoma brucei, is based on preventing transmission by elimination of the tsetse vector and by active diagnostic screening and treatment of infected patients. To identify trypanosome proteins that have potential as biomarkers for detection and monitoring of African sleeping sickness, we have used a ‘deep-mining” proteomics approach to identify trypanosome proteins in human plasma. Abundant human plasma proteins were removed by immunodepletion. Depleted plasma samples were then digested to peptides with trypsin, fractionated by basic reversed phase and each fraction analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This sample processing and analysis method enabled identification of low levels of trypanosome proteins in pooled plasma from late stage sleeping sickness patients infected with Trypanosoma brucei rhodesiense. A total of 254 trypanosome proteins were confidently identified. Many of the parasite proteins identified were of unknown function, although metabolic enzymes, chaperones, proteases and ubiquitin-related/acting proteins were found. This approach to the identification of conserved, soluble trypanosome proteins in human plasma offers a possible route to improved disease diagnosis and monitoring, since these molecules are potential biomarkers for the development of a new generation of antigen-detection assays. The combined immuno-depletion/mass spectrometric approach can be applied to a variety of infectious diseases for unbiased biomarker identification

Suppression of HBV by Tenofovir in HBV/HIV coinfected patients : a systematic review and meta-analysis

Background: Hepatitis B coinfection is common in HIV-positive individuals and as antiretroviral therapy has made death due to AIDS less common, hepatitis has become increasingly important. Several drugs are available to treat hepatitis B. The most potent and the one with the lowest risk of resistance appears to be tenofovir (TDF). However there are several questions that remain unanswered regarding the use of TDF, including the proportion of patients that achieves suppression of HBV viral load and over what time, whether suppression is durable and whether prior treatment with other HBV-active drugs such as lamivudine, compromises the efficacy of TDF due to possible selection of resistant HBV strains. Methods: A systematic review and meta-analysis following PRISMA guidelines and using multilevel mixed effects logistic regression, stratified by prior and/or concomitant use of lamivudine and/or emtricitabine. Results: Data was available from 23 studies including 550 HBV/HIV coinfected patients treated with TDF. Follow up was for up to seven years but to ensure sufficient power the data analyses were limited to three years. The overall proportion achieving suppression of HBV replication was 57.4%, 79.0% and 85.6% at one, two and three years, respectively. No effect of prior or concomitant 3TC/FTC was shown. Virological rebound on TDF treatment was rare. Interpretation: TDF suppresses HBV to undetectable levels in the majority of HBV/HIV coinfected patients with the proportion fully suppressed continuing to increase during continuous treatment. Prior treatment with 3TC/FTC does not compromise efficacy of TDF treatment. The use of combination treatment with 3TC/FTC offers no significant benefit over TDF alone

New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a `strained' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.Comment: 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for Phys. Lett.