Mono-functional aminosilanes as primers for peptide functionalization

When covalently attaching biomolecules to surfaces such as titanium, trifunctional silanes are commonly used as primers to produce surface amine groups. However, these primed surfaces are rarely uniform in structure due to networking of the silane. Mono-functional aminosilanes may result in more uniform structures, although their long-term stability and effect on osteoblast cell responses are possible issues for orthopedic applications. This study examines for the first time the optimization of peptide coupling to titanium using mono-functional aminosilane reaction chemistry. The resultant surface topography, chemistry, and thicknesses were characterized showing improved surface uniformity compared with trifunctional silanized surfaces. The stability of the coatings was examined over a period of 8 days in environments of varying pH, temperature, and humidity. In addition, human osteosarcoma (HOS) cell adhesion and spreading on the samples was examined; adhesion was minimal on silanized surfaces, but after functionalization with cysteine the cell density was greater than the titanium control and showed no overall detrimental effect on initial cell responses.     

The modification of PLA and PLGA using electron-beam radiation

The degradable polymers polylactide (PLA) and polylactide-co-glycolide (PLGA) have found widespread use in modern medical practice. However, their slow degradation rates and tendency to lose strength before mass have caused problems. The aim of this study was to ascertain whether treatment with e-beam radiation could address these problems. Samples of PLA and PLGA were manufactured and placed in layered stacks, 8.1 mm deep, before exposure to 50 kGy of e-beam radiation from a 1.5 MeV accelerator. Gel permeation chromatography testing showed that the molecular weight of both materials was depth-dependent following irradiation, with samples nearest to the treated surface showing a reduced molecular weight. Samples deeper than 5.4 mm were unaffected. Computer modeling of the transmission of a 1.5 MeV e-beam in these materials corresponded well with these findings. An accelerated mass-loss study of the treated materials found that the samples nearest the irradiated surface initiated mass loss earlier, and at later stages showed an increased percentage mass loss. It was concluded that e-beam radiation could modify the degradation of bioabsorbable polymers to potentially improve their performance in medical devices, specifically for improved orthopedic fixation.     

Modelling the progression of pandemic influenza A (H1N1) in Vietnam and the opportunities for reassortment with other influenza viruses

Background  

A novel variant of influenza A (H1N1) is causing a pandemic and, although the illness is usually mild, there are concerns that its virulence could change through reassortment with other influenza viruses. This is of greater concern in parts of Southeast Asia, where the population density is high, influenza is less seasonal, human-animal contact is common and avian influenza is still endemic.     

Quantification of artemisinin in human plasma using liquid chromatography coupled to tandem mass spectrometry

A liquid chromatographic tandem mass spectroscopy method for the quantification of artemisinin in human heparinised plasma has been developed and validated. The method uses Oasis HLB™ μ-elution solid phase extraction 96-well plates to facilitate a high throughput of 192 samples a day. Artesunate (internal standard) in a plasma–water solution was added to plasma (50 μL) before solid phase extraction. Artemisinin and its internal standard artesunate were analysed by liquid chromatography and MS/MS detection on a Hypersil Gold C18 (100 mm × 2.1 mm, 5 μm) column using a mobile phase containing acetonitrile–ammonium acetate 10 mM pH 3.5 (50:50, v/v) at a flow rate of 0.5 mL/min. The method has been validated according to published FDA guidelines and showed excellent performance. The within-day, between-day and total precisions expressed as R.S.D., were lower than 8% at all tested quality control levels including the upper and lower limit of quantification. The limit of detection was 0.257 ng/mL for artemisinin and the calibration range was 1.03–762 ng/mL using 50 μL plasma. The method was free from matrix effects as demonstrated both graphically and quantitatively.     

Validation of a diagnostic algorithm for adult tuberculous meningitis

Tuberculous meningitis (TBM) remains difficult to diagnose. We prospectively evaluated a diagnostic algorithm for TBM in 205 HIV-negative patients with meningitis and a low CSF glucose. Patients were classified as having TBM or bacterial meningitis (BM) by two diagnostic methods: logistic regression method (LRM) and classification and regression tree (CART). We performed analyses of TBM versus BM and TBM versus non-TBM in all patients and in patients with microbiologically confirmed diagnoses. Diagnostic sensitivities for TBM were 99% (LRM) and 87% (CART). For BM, diagnostic sensitivities were 81.5% (LRM) and 86.5% (CART) in the primary analysis and 86.5% (LRM) and 74% (CART) in the secondary analysis. In microbiologically confirmed cases, similar rates were achieved. These figures are superior to microbiological confirmation rates in routine laboratories and support the use of this algorithm in high-prevalence TB settings with limited diagnostic facilities. Validation in an HIV-endemic setting is required.     

From the voices of women: facilitating survivor access to IPV services

This mixed-method study investigated perceptions women domestic violence survivors/victims have about why women do not seek help from formal support structures and actions domestic helping agencies can take to facilitate survivor access to services. Congruent with previous research, quantitative analysis identified 17 reasons women do not seek help from formal support structures. Expanding current knowledge, concept mapping revealed six ways family violence programs can better reach women in abusive relationships, including (1) remove barriers to services, (2) improve comfort with services, (3) "talk about it," (4) improve community awareness, (5) victim-targeted marketing, and (6) "I honestly don't know."