The active site structure and catalytic mechanism of arsenite oxidase

Arsenite oxidase is thought to be an ancient enzyme, originating before the divergence of the Archaea and the Bacteria. We have investigated the nature of the molybdenum active site of the arsenite oxidase from the Alphaproteobacterium Rhizobium sp. str. NT-26 using a combination of X-ray absorption spectroscopy and computational chemistry. Our analysis indicates an oxidized Mo(VI) active site with a structure that is far from equilibrium. We propose that this is an entatic state imposed by the protein on the active site through relative orientation of the two molybdopterin cofactors, in a variant of the Rây-Dutt twist of classical coordination chemistry, which we call the pterin twist hypothesis. We discuss the implications of this hypothesis for other putatively ancient molybdopterin-based enzymes

The fabric of a career in mental health nursing from an Australian and UK perspective

As the prevalence of mental illness increases globally, Australia and the United Kingdom (UK) share concerns regarding the recruitment and retention of nurses to the field of mental health care. The level of preparedness of nurses is thought to have a bearing on recruitment and retention in mental health nursing practice. This study sought to uncover what Australian and UK undergraduate students perceived as motivational in choosing a career in, and being prepared for, working in mental health settings. METHOD This study employed mixed methods, using a questionnaire comprising of both quantitative and qualitative questions. Quantitative data was analysed using SPSS (V.16.0) and content analysis was undertaken for analysing the qualitative data. FINDINGS Following ethical approval, data was collected from, four universities in Australia and two in the UK. A total of 447 undergraduate nursing and midwifery students, who had completed a mental health placement, completed the questionnaire. Findings revealed that motivational factors influencing their interest in mental health nursing were clinical experience (49.7%), personal/life experiences (42.9%) and the role of the lecturer (23%). However, 47.7% of all participants had some previous experience of mental illness, with only 18.4% having had work experience in the field prior to starting their course. IMPLICATIONS This study adds to extant knowledge of what encourages people to choose a career trajectory in mental health nursing and what could be harnessed with regard to retention. The knowledge gained from these findings is useful in informing recruitment processes and can also inform curriculum

The future of mental health nursing education in the United Kingdom: Reflections on the Australian and New Zealand experience

This paper provides a debate related to how proposed changes to preregistration nurse preparation in the United Kingdom (UK) may impact on the future of undergraduate mental health nursing workforce. In the first instance we set out the proposed changes and the underlying reasoning provided for these changes. We compare the proposals in relation to the present curricula and possible outcomes of mental health nursing education in the UK. Our discussion also considers if there are lessons to be learned from the Australian and New Zealand where nursing education underwent similar changes during the 1990s. We offer a critique of the underlying political, economic and ideological reasons for these radial changes to nursing education with due consideration of lessons learned by others

Comparison of redox and ligand binding behaviour of yeast and bovine cytochrome c oxidases using FTIR spectroscopy

Redox and CO photolysis FTIR spectra of yeast cytochrome c oxidase WT and mutants are compared to those from bovine and P. denitrificans CcOs in order to establish common functional features. All display changes that can be assigned to their E242 (bovine numbering) equivalent and to weakly H-bonded water molecules. The additional redox-sensitive band reported at 1736 cm-1 in bovine CcO and previously assigned to D51 is absent from yeast CcO and couldn’t be restored by introduction of a D residue at the equivalent position of the yeast protein. Redox spectra of yeast CcO also show much smaller changes in the amide I region, which may relate to structural differences in the region around D51 and the subunit I/II interface

A systematic review and meta-analysis of factors that relate to aggression perpetrated against nurses by patients/relatives or staff

Aims and objectives- The aim of this meta-analysis was to identify the factors that related to aggression (verbal abuse, or physical abuse/assault) perpetrated against the nurse or other health professional by patients/relatives or staff. In light of the paucity of systematic reviews on this common issue in nursing, the objective was to present a comprehensive systematic review and meta-analysis of these papers. Background – Aggression towards nurses is common around the world and can be the impetus for nurses leaving the profession or developing anxiety when working in particular settings. Design- Systematic review with meta-analysis Data Sources- The databases of Medline (1966 to 2015), CINAHL (1982 to 2015) and PsychInfo (1920 to 2015). Methods- Meta-analyses were conducted to assess the effect of the factors of gender and context (dichotomised as mental health/psychiatric or non-mental health/psychiatric). Results - A total of 1571 papers were screened by two reviewers. At the final decision 14 were selected for analysis. A higher proportion of female nurses than male nurses were reported to be the victims of verbal abuse, with the difference in proportions being statistically significant. A statistically significant higher proportion of male nurses than female nurses were reported to be the victims of physical abuse. There was a significantly higher proportion of mental health nurses reported experiencing physical abuse as compared to non-mental health nurses. Conclusions – The analysis reveal female nurses have greater odds of verbal abuse than male nurses and male nurses have greater odds of physical abuse than female nurses. Overall mental health nurses had 3 times higher odds of physical assault than other nurses. Relevance to clinical practice- In light of the findings it is recommended organisational support improve in high aggression potential clinical areas and for nursing curriculums to incorporate education about the management of challenging behaviours in undergraduate programs

A new family of periplasmic-binding proteins that sense arsenic oxyanions

Arsenic contamination of drinking water affects more than 140 million people worldwide. While toxic to humans, inorganic forms of arsenic (arsenite and arsenate), can be used as energy sources for microbial respiration. AioX and its orthologues (ArxX and ArrX) represent the first members of a new sub-family of periplasmic-binding proteins that serve as the first component of a signal transduction system, that's role is to positively regulate expression of arsenic metabolism enzymes. As determined by X-ray crystallography for AioX, arsenite binding only requires subtle conformational changes in protein structure, providing insights into protein-ligand interactions. The binding pocket of all orthologues is conserved but this alone is not sufficient for oxyanion selectivity, with proteins selectively binding either arsenite or arsenate. Phylogenetic evidence, clearly demonstrates that the regulatory proteins evolved together early in prokaryotic evolution and had a separate origin from the metabolic enzymes whose expression they regulate

Factors that influence nurses' assessment of patient acuity and response to acute deterioration.

BACKGROUND: nurses play a crucial role in the early recognition and management of the deteriorating patient. They are responsible for the care they provide to their patients, part of which is the monitoring of vital signs (blood pressure, pulse, respiratory rate and temperature), which are fundamental in the surveillance of deterioration. The aim of this study was to discover what factors influence how nurses assess patient acuity and their response to acute deterioration. METHODS: a generic qualitative approach was used. Some 10 nurses working in an acute NHS trust were interviewed using a semi- structured approach, with equal representation from medical and surgical inpatient wards. RESULTS: the main themes identified were collegial relationships, intuition, and interpretation of the MEWS system (Modified Early Warning Score). Collegial relationships with the medical staff had some influence on the nurses' assessment, as they tended to accept the medical peers' assessment as absolute, rather than their own assessment. It was also highlighted that nurses relied on the numerical escalation of the MEWS system to identify the deteriorating patient, instead of their own clinical judgement of the situation. Interestingly, the nurses found no difficulty in escalating the patient's care to medical staff when the patient presented with a high MEWS score. The difficulty arose when the MEWS score was low-the participants found it challenging to authenticate their findings. CONCLUSION: this study has identified several confounding factors that influence the ways in which nurses assess patient acuity and their response to acute deterioration. The information provides a crucial step forward in identifying strategies to develop further training

Cold-adapted arsenite oxidase from a psychrotolerant Polaromonas species.

Polaromonas sp. str. GM1 is an aerobic, psychrotolerant, heterotrophic member of the Betaproteobacteria and is the only isolate capable of oxidising arsenite at temperatures below 10 °C. Sequencing of the aio gene cluster in GM1 revealed the presence of the aioB and aioA genes, which encode the arsenite oxidase but the regulatory genes typically found upstream of aioB in other members of the Proteobacteria were absent. The GM1 Aio was purified to homogeneity and was found to be a heterodimer. The enzyme contained Mo and Fe as cofactors and had, using the artificial electron acceptor 2,6-dichlorophenolindophenol, a Km for arsenite of 111.70 ± 0.88 μM and a Vmax of 12.16 ± 0.30 U mg(-1), which is the highest reported specific activity for any known Aio. The temperature-activity profiles of the arsenite oxidases from GM1 and the mesophilic betaproteobacterium Alcaligenes faecalis were compared and showed that the GM1 Aio was more active at low temperatures than that of A. faecalis. A homology model of the GM1 Aio was made using the X-ray crystal structure of the Aio from A. faecalis as the template. Structural changes that account for cold adaptation were identified and it was found that these resulted in increased enzyme flexibility and a reduction in the hydrophobicity of the core

Nursing and aggression in the workplace: a systematic review

Personal experiences of aggression or violence in the workplace lead to serious consequences for nurses, their patients, patient care and the organisation as a whole. While there is a plethora of research on this topic, no review is available that identifies types of aggression encountered, individuals perceived to be most at risk and coping strategies for victims. The aim of this systematic review was to examine occupational anxiety related to actual aggression in the workplace for nurses. Databases (MEDLINE, CINAHL and PsycINFO) were searched, resulting in 1543 titles and abstracts. After removal of duplicates and non-relevant titles, 137 papers were read in full. Physical aggression was found to be most frequent in mental health, nursing homes and emergency departments while verbal aggression was more commonly experienced by general nurses. Nurses exposed to verbal or physical abuse often experienced a negative psychological impact post incident

Arsenite oxidase as a novel biosensor for arsenite

Contamination of groundwater with the toxic soluble arsenic species, arsenite (AsIII) and arsenate (AsV) has led to an epidemic of arsenic poisoning effecting over 100 million people worldwide. The World Health Organisation (WHO) recommended maximum contaminant level (MCL) for arsenic in water is 0.13 μM (10 μg L−1). Accurate quantification of arsenic below the MCL usually requires highly sensitive laboratory based techniques, the practical uses of which are limited within the effected populations, principally due to cost. Biosensors are a potentially powerful technology for overcoming this problem. Amperometric biosensors couple the analytical sensitivity of electrochemistry with the selectivity of enzyme substrate interactions. The bioenergetic metalloenzyme AsIII oxidase (Aio) catalyses the oxidation of AsIII to AsV in a number of physiologically diverse microorganisms including the Rhizobium sp. str. NT-26. To develop a biosensor for AsIII it was first necessary to optimise the expression and purification of the biological recognition element, a recombinant NT-26 Aio in Escherichia coli str. DH5α. with final a yield of ca. 1.1 mg per L of culture. The recombinant NT-26 Aio was characterised using biophysical techniques to confirm the correct insertion of the enzyme cofactors during heterologous expression in E. coli. The reduction midpoint potentials of the 3Fe-4S (270 mV) and the Rieske 2Fe-2S (225 mV) clusters were confirmed by redox titration. The thermostability of the recombinant Aio was ≤ 64.5 °C. The oxidised structure of the Mo at the active site was confirmed to have a di-oxo (Mo = O2) coordination. The kinetics and pH dependence of AsIII oxidation were investigated using various artificial and physiological electron acceptors. Electrochemical studies were performed to develop a system for AsIII concentration determination, using the biological recognition element Aio. The electron transfer mediator ferrocene methanol was found to produce the greatest currents during catalytic voltammetry experiments at pH 8.0. A chronoamperometric detection system incorporating the electron transfer mediators ferrocene methanol and potassium ferricyanide was able to resolve AsIII concentrations of 0.07 – 0.53 μM (5 – 40 μg L−1), below the WHO MCL for arsenic, suggesting such a system would be capable of determining the safe levels of arsenic in drinking water