The importance of commutability of reference materials used as calibrators: the example of ceruloplasmin.

BACKGROUND: Different methods for ceruloplasmin tend to give different results in external quality assessment schemes. During the production of the certified reference material ERM-DA470k/IFCC discrepant measurement results were also found for ceruloplasmin measured with different methods, and consequently the protein could not be certified in the material. METHODS: We performed a commutability study with 30 serum samples and the reference materials ERM-DA470, ERM-DA470k/IFCC, and ERM-DA472/IFCC, using 6 different methods. Data were analyzed according to the CLSI Guideline C53-A to assess whether the reference materials had the same behavior as the serum samples with respect to measurement results obtained with combinations of the methods used. RESULTS: Measurement results from different methods showed a good linear correlation for the serum samples. ERM-DA470 showed marked noncommutability for certain combinations of methods. ERM-DA470k/IFCC and ERM-DA472/IFCC were commutable for more combinations of methods. The lack of commutability of ERM-DA470 for certain combinations of methods correlates with results from the UK National External Quality Assessment Service showing discrepancies between results from these methods. For serum stored in the presence of sodium azide the results from different methods are essentially equivalent. CONCLUSIONS: Ceruloplasmin in ERM-DA470 is a fully documented example of a situation in which, due to lack of commutability, the use of a common material for calibration did not lead to harmonization .

To Fight or to Grow: The Balancing Role of Ethylene in Plant Abiotic Stress Responses.

Plants often live in adverse environmental conditions and are exposed to various stresses, such as heat, cold, heavy metals, salt, radiation, poor lighting, nutrient deficiency, drought, or flooding. To adapt to unfavorable environments, plants have evolved specialized molecular mechanisms that serve to balance the trade-off between abiotic stress responses and growth. These mechanisms enable plants to continue to develop and reproduce even under adverse conditions. Ethylene, as a key growth regulator, is leveraged by plants to mitigate the negative effects of some of these stresses on plant development and growth. By cooperating with other hormones, such as jasmonic acid (JA), abscisic acid (ABA), brassinosteroids (BR), auxin, gibberellic acid (GA), salicylic acid (SA), and cytokinin (CK), ethylene triggers defense and survival mechanisms thereby coordinating plant growth and development in response to abiotic stresses. This review describes the crosstalk between ethylene and other plant hormones in tipping the balance between plant growth and abiotic stress responses.

The role of calculated non-caeruloplasmin-bound copper in Wilson's disease.

Background US and European guidelines suggest the use of calculated non-caeruloplasmin-bound copper (free copper index) for the diagnosis and management of Wilson's Disease. However, there is concern that the required analytical measurements of caeruloplasmin and copper may not be sufficiently robust at the concentrations usually found. Methods Aliquots of six plasma specimens were sent to laboratories participating in the UK National External Quality Assessment Scheme for copper and caeruloplasmin. The variability of these two reported measurements and the calculated non-caeruloplasmin-bound copper concentrations were compared. The variability of caeruloplasmin reference ranges quoted by laboratories was also investigated. Results No laboratories use the required enzymatic methods in the calculation of non-caeruloplasmin-bound copper. The interlaboratory variations in caeruloplasmin concentrations and calculated non-caeruloplasmin-bound copper concentrations were very considerable so making clinical interpretation unreliable. Wide differences in the caeruloplasmin reference ranges used were also found. Conclusions Such variations of the calculated non-caeruloplasmin-bound copper concentrations and the predominant use of immunological methods for measuring caeruloplasmin preclude a clinical role for this calculated value in the investigation of Wilson's disease.

General practice characteristics associated with rates of testing and detection of hepatitis C: cross-sectional study in Nottingham and Derbyshire.

The aim of this study was to determine general practice characteristics associated with testing rates for hepatitis C virus (HCV) and the proportion of tests with a positive result. The study included all patients tested for HCV from all general practices in the primary care trusts in Nottingham and Southern Derbyshire, UK over 2 years. There was a large variation between practices in HCV testing rates and the proportion of positive tests. Single-handed practices had higher testing rates and rates of positive results. Practices where at least half of the GPs were female had higher testing rates but lower positivity rates. The variation observed was not explained by deprivation or rurality of the practice.

Developing and enhancing biodiversity monitoring programmes: a collaborative assessment of priorities.

Biodiversity is changing at unprecedented rates, and it is increasingly important that these changes are quantified through monitoring programmes. Previous recommendations for developing or enhancing these programmes focus either on the end goals, that is the intended use of the data, or on how these goals are achieved, for example through volunteer involvement in citizen science, but not both. These recommendations are rarely prioritized.We used a collaborative approach, involving 52 experts in biodiversity monitoring in the UK, to develop a list of attributes of relevance to any biodiversity monitoring programme and to order these attributes by their priority. We also ranked the attributes according to their importance in monitoring biodiversity in the UK. Experts involved included data users, funders, programme organizers and participants in data collection. They covered expertise in a wide range of taxa.We developed a final list of 25 attributes of biodiversity monitoring schemes, ordered from the most elemental (those essential for monitoring schemes; e.g. articulate the objectives and gain sufficient participants) to the most aspirational (e.g. electronic data capture in the field, reporting change annually). This ordered list is a practical framework which can be used to support the development of monitoring programmes.People's ranking of attributes revealed a difference between those who considered attributes with benefits to end users to be most important (e.g. people from governmental organizations) and those who considered attributes with greatest benefit to participants to be most important (e.g. people involved with volunteer biological recording schemes). This reveals a distinction between focussing on aims and the pragmatism in achieving those aims. Synthesis and applications. The ordered list of attributes developed in this study will assist in prioritizing resources to develop biodiversity monitoring programmes (including citizen science). The potential conflict between end users of data and participants in data collection that we discovered should be addressed by involving the diversity of stakeholders at all stages of programme development. This will maximize the chance of successfully achieving the goals of biodiversity monitoring programmes.

The binaural performance of a cross-talk cancellation system with matched or mismatched setup and playback acoustics.

Cross-talk cancellation is a method for synthesizing virtual auditory space using loudspeakers. One implementation is the "Optimal Source Distribution" technique [T. Takeuchi and P. Nelson, J. Acoust. Soc. Am. 112, 2786-2797 (2002)], in which the audio bandwidth is split across three pairs of loudspeakers, placed at azimuths of +/-90 degrees, +/-15 degrees, and +/-3 degrees, conveying low, mid, and high frequencies, respectively. A computational simulation of this system was developed and verified against measurements made on an acoustic system using a manikin. Both the acoustic system and the simulation gave a wideband average cancellation of almost 25 dB. The simulation showed that when there was a mismatch between the head-related transfer functions used to set up the system and those of the final listener, the cancellation was reduced to an average of 13 dB. Moreover, in this case the binaural interaural time differences and interaural level differences delivered by the simulation of the optimal source distribution (OSD) system often differed from the target values. It is concluded that only when the OSD system is set up with "matched" head-related transfer functions can it deliver accurate binaural cues.