Detection and Sizing of Ti-Containing Particles in Recreational Waters Using Single Particle ICP-MS

Single particle inductively coupled plasma mass spectrometry (spICP-MS) was used to detect Ti-containing particles in heavily-used bathing areas of a river (Salt River) and five swimming pools. Ti-containing particle concentrations in swimming pools ranged from 2.8?×?10³ to 4.4?×?10³ particles/mL and were an order of magnitude lower than those detected in the Salt River. Measurements from the Salt River showed an 80% increase in Ti-containing particle concentration over baseline concentration during peak recreational activity (at 16:00 h) in the river. Cloud point extraction followed by transmission electron microscopy with energy dispersive X-ray analysis confirmed presence of aggregated TiO₂ particles in river samples, showing morphological similarity to particles present in an over-the-counter sunscreen product. The maximum particle mass concentration detected in a sample from the Salt River (659 ng/L) is only slightly lower than the predicted no effect concentration for TiO₂ to aquatic organisms (<?1 μg/L).     

Individually-matched etiologic studies: classical estimators made new again

With greater access to regression-based methods for confounder control, the etiologic study with individual matching, analyzed by classical (calculator) methods, lost favor in recent decades. This design was costly, and the data sometimes mis-analyzed. Now, with Big Data, individual matching becomes an economical option. To many, however, conditional logistic regression, commonly used to estimate the incidence density ratio parameter, is somewhat of a black box whose output is not easily checked. An epidemiologist-statistician pair recently proposed a new estimator that is easily applied to data from individually-matched series with a 2:1 ratio (and no other confounding variables) using just a hand calculator or spreadsheet. Surprisingly—or possibly not—they overlooked classical estimators developed in earlier decades. This prompts me to re-introduce some of these, to highlight their considerable flexibility and ease of use, and to update them. Nowadays, for any matching ratio (M:1), the Maximum Likelihood result can be easily computed from data gathered under the matched design in two different ways, each using just the summary data. One is via any binomial regression program that allows offsets, applied to just M ‘rows’ of data. The other is by hand! The aim of this note is not to save on computation; instead, it is to make connections between classical and regression-based methods, to promote terminology that reflects the concepts and structure of the etiologic study, and to focus attention on what parameter is being estimated.     

Effect of CYP3A4, CYP3A5, and ABCB1 Polymorphisms on Intravenous Tacrolimus Exposure and Adverse Events in Adult Allogeneic Stem Cell Transplant Patients

Pharmacogenetics influences oral tacrolimus exposure; however, little data exist regarding i.v. tacrolimus. We investigated the impact of genetic polymorphisms in CYP3A4, CYP3A5, and ABCB1 on i.v. tacrolimus exposure and toxicity in adult patients receiving an allogeneic hematopoietic stem cell transplant for hematologic malignancies. Germline DNA was extracted from buccal swabs and genotyped for CYP3A4, CYP3A5, and ABCB1 polymorphisms. Continuous i.v. infusion of tacrolimus .03 mg/kg/day was initiated on day +5 post-transplant, and steady-state blood concentrations were measured 4days later. We evaluated the association between phenotypes and prevalence of nontherapeutic target concentrations (below or above 5 to 15 ng/mL) as well as tacrolimus-related toxicities. Of 63 patients, 28.6% achieved the target concentration; 71.4% were >15ng/mL, which was more common in CYP3A4 intermediate/normal metabolizers (compared with rapid) and those with at least 1 ABCB1 C2677T loss-of-function allele (P < .05). ABCB1 C2677T was significantly associated with concentrations >15ng/mL (odds ratio, 6.2; 95% confidence interval, 1.8 to 23.6; P = .004) and tacrolimus-related toxicities (odds ratio, 7.5; 95% confidence interval, 1.6 to 55.2; P = .02). ABCB1 C2677T and CYP3A4 are important determinants of i.v. tacrolimus exposure, whereas ABCB1 C2677T also impacts tacrolimus-related toxicities in stem cell transplants.     

Comparison of incremental concentrations of micron-sized superparamagnetic iron oxide for labelling articular cartilage derived chondroprogenitors

IntroductionIn vivo tracking of labelled cells can provide valuable information about cellular behavior in the microenvironment, migration and contribution of transplanted cells toward tissue regeneration. Articular cartilage derived chondroprogenitors (CPs) show promise as a candidate for cell-based therapy as they have been classified as mesenchymal stem cells with inherent chondrogenic potential. Iron oxide labelling is known to withstand harsh processing techniques known to be associated with staining of osteochondral specimens.Aim and methodsThe aim of our study was to investigate the feasibility of labelling CPs with micron-sized super paramagnetic iron oxide (M-SPIO) particles and to study the effects of this approach on the labelling efficiency, viability, maintenance of phenotype and potential for differentiation. Human CPs were isolated using fibronectin adhesion assay, passage 2 cells were labelled using three concentrations of M-SPIO (12.75 μg/ml, 25.5 μg/ml and 38.25 μg/ml). At sub confluence, cells were assessed for a) iron uptake by Prussian blue stain and colorimetry b) viability using 7-amino actinomycin D, c) MSC marker expression by flow cytometric analysis and d) trilineage differentiation potential.Results and conclusionIron uptake was higher with increase in M-SPIO concentration whereas CD73, CD90 marker expression significantly decreased and chondrogenic potential appreciably reduced with increase in M-SPIO concentration. In conclusion, 12.75 μg/ml M-SPIO can successfully label human articular cartilage derived chondroprogenitors with minimal effect on cellular viability, MSC marker expression and potential for differentiation.     

Practices and Processes Used in the Return to Work of Injured New South Wales nurses: Are These Consistent With RTW Best Practice Principles?

Purpose Workplace injury and illness rates are high within the nursing profession, and in conjunction with current nursing shortages, low retention rates, and the high cost of workplace injury, the need for effective return to work (RTW) for injured nurses is highlighted. This study aimed to identify current practices and processes used in the RTW of injured nurses, and determine if these are consistent with the seven principles for successful RTW as described by the Canadian Institute for Work & Health. Method As part of a larger cross-sectional study, survey data were collected from New South Wales nurses who had sustained a major workplace injury or illness. Survey questions were coded and matched to the seven principles for successful RTW. Results Of the 484 surveys eligible for analysis, most were from Registered Nurses (52%) in the Public Hospital Sector (48%). Responses indicated four main areas of concern: a commitment to health and safety by the workplace; early and considerate employer contact; provision of modified work; and individual knowledge of and involvement in the RTW process. Positive participant responses to co-worker and supervisor involvement were identified as areas consistent with best practice principles. Conclusions These findings suggest the practices and processes involved in the RTW of injured nurses are inconsistent with best practice principles for RTW, highlighting the need for interventions such as targeted employer education and training for improved industry RTW outcomes.