Analysis of CD45 variants effecting alternative splicing.

The CD45 (leukocyte common) antigen is a haemopoietic cell specific tyrosine phosphatase essential for antigen receptor signalling in lymphocytes. Multiple isoforms of CD45 are expressed in a cell type and activation-specific manner, but the exact function of the different isoforms remains obscure. In humans, naive T cells express high molecular weight isoforms (containing CD45RA), but following activation switch to expression of low molecular weight (CD45R0 and CD45RB) isoforms. Human CD45 variant alleles which alter CD45 isoform expression have been identified and associated with infectious and autoimmune diseases. Two contrasting allelic variants have been analysed. The exon 4 77G allele is present at a low frequency in Caucasoids and prevents splicing from high to low molecular weight isoforms. An increased frequency of this allele is found in multiple sclerosis, HIV and Hepatitis C infected individuals. The exon 6 138G allele is found at a high frequency in Far Eastern populations and promotes splicing towards low molecular weight isoforms. This allele is protective in Graves' disease and Hepatitis B infection. Both alleles are associated with altered phenotype and in vitro functional response of T cells. Similarly CD45 transgenic mice exhibit altered T cell phenotype and function. These data demonstrate that subtle changes in isoform expression lead to an alteration in cell phenotype and that both combinations of isoforms and the total level of expression are important for CD45 function

Determination of pharmaceuticals in freshwater sediments using ultrasonic-assisted extraction with SPE clean-up and HPLC-DAD or LC-ESI-MS/MS detection

A robust and sensitive analytical method is presented for the extraction and determination of six pharmaceuticals in freshwater sediments. The pharmaceuticals were extracted from sediment using ultrasonic extraction with 2% NH4OH in methanol (MeOH), followed by extraction into 2% formic acid in MeOH and then MeOH only. The resulting extracts were then analysed, after clean-up on HLB solid phase extraction cartridges, using a single gradient run using a Zorbax Eclipse XDB-C18 (150 × 4.6 mm, 5 μm) column and a mobile phase consisting of 10 mM ammonium acetate and MeOH (pH = 4.8). Analytes were detected and quantified using either Diode Array Detector (DAD) or tandem mass spectrometry (MS/MS) with electrospray ionization in positive mode. Validation studies were carried out using ten sediments sampled from the UK and Iraq with a wide range of characteristics. The mean calculated recoveries for fortified samples in all studied sediments ranged from 74.5 to 114.6% for atenolol, 72.3 to 124.9% for amitriptyline, 76.5 to 105% for mefenamic acid and 70.1 to 102% for diltiazem. Cimetidine and ranitidine showed lower recoveries which ranged from 40.2 to 68.4% and 30.4 to 55.2% respectively. Relative standard deviations (RSD) of recoveries for all sediment-pharmaceutical combinations ranged from 1.6 to 15.8%. The detection limits in sediments for the six analytes ranged from 15 to 58.5 ng g-1 and 0.03 to 3.5 ng g-1, dry weight, for HPLC-UV and LC-ESI-MS/MS respectively. Overall the results indicate that the developed method is effective for use in monitoring the concentrations of pharmaceuticals in aquatic sediments in different regions

Floc formation reduces the pH stress experienced by microorganisms living in alkaline environments

The survival of microorganisms within a cementitious geological disposal facility for radioactive wastes is heavily dependent on their ability to survive the calcium dominated, hyper-alkaline conditions resulting from the dissolution of the cementitious materials. The present study shows that the formation of flocs, composed of a complex mixture of extracellular polymeric substances (EPS), provides protection against alkaline pH values up to pH 13.0. The flocs were dominated by Alishewanella and Dietzia sp, producing a mannose rich carbohydrate fraction incorporating extracellular DNA, resulting in Ca2+ sequestration. EPS provided a ~10 µm thick layer around the cells within the centre of the flocs, which were capable of growth at pH 11.0 and 11.5, maintaining internal pH values of pH 10.4 and 10.7 respectively. Survival was observed at pH 12.0, where an internal floc pH of 11.6 was observed alongside a reduced associated biomass. Limited floc survival (<2 weeks) was observed at pH 13.0.This study demonstrates that flocs are able to maintain a lower internal pH in response to the hyperalkaline conditions expected to occur within a cementitious, geological disposal facility for radioactive wastes and indicates that floc communities within such a facility would be capable of survival up to a pH of 12.0

Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance

Much of the human resource management literature has demonstrated the impact of high performance work systems (HPWS) on organizational performance. A new generation of studies is emerging in this literature that recommends the inclusion of mediating variables between HPWS and organizational performance. The increasing rate of dynamism in competitive environments suggests that measures of employee adaptability should be included as a mechanism that may explain the relevance of HPWS to firm competitiveness. On a sample of 226 Spanish firms, the study’s results confirm that HPWS influences performance through its impact on the firm’s human resource (HR) flexibility

Identifying water prices at which Australian farmers will exit Irrigation: results of a stated preference survey

Among the measures taken by the Australian government to address one of the worst droughts on record in the Murray-Darling Basin, exit package issues have rarely been investigated. A stated preference survey was designed to identify the range of water prices required for irrigators to sell all their water entitlements and leave the irrigation industry. Farmer participation responses are generally price elastic. There are large regional differences in price elasticities, but within a region there are few differences based on subgroups of farmers.Alec Zuo, Sarah Ann Wheeler, Peter Box, W.L. (Vic) Adamowicz, and Darla Hatton MacDonal

The hydrolysis of hydroxamic acid complexants in the presence of non-oxidizing metal ions 1: Ferric ions.

Hydroxamic acids (XHAs) are organic compounds with affinities for cations such as Fe3+, Np4+ and Pu4+ and have been identified as useful reagents in nuclear fuel reprocessing. Acid catalyzed hydrolysis of free XHAs is well known and may impact negatively on reprocessing applications. The hydrolysis of metal-bound XHAs within metal ion-XHA complexes is less understood. With the aid of speciation diagrams, we have modelled UV-visible spectrophotometric kinetic studies of the acid-catalyzed hydrolysis of acetohydroxamic acid (AHA) bound to the model ion Fe(III). These studies have yielded the following information for the hydrolysis of AHA in the Fe(AHA)2+ complex at 293 K: (i) the order with respect to [H+] during the rate determining step, m=0.97, is the same as for the free ligand, indicating a similarity of mechanisms; and (ii) the kinetic rate parameter, k 1=1.02×10−4 dm3⋅mol−1⋅s−1, is greater than that for the free ligand, k 0=1.84×10−5 dm3⋅mol−1⋅s−1 for pH>−0.5, a result that is consistent with a Hammett analysis of the system