Soluble manganese (IV); a new chemiluminescence reagent

The oxidations of twenty five organic and inorganic species, with solublised manganese(IV), were found to elicit analytically useful chemiluminescence with detection limits (3 × S/N) for Mn(II), Fe(II), morphine and codeine of 5 × 10^–8 M, 2.5 × 10^–7 M, 7.5 × 10^–8 M and 5 × 10^–8 M, respectively. Additionally, the corrected spectra from four different analytes gave wavelengths of maximum emission in the range from 733 nm up to 740 nm suggesting that all these chemiluminescence reactions shared a common emitting species.

Attitudes and perceptions of workers to sexual harrassment

The authors investigated how individual factors (age, gender, gender role, past experiences of sexual harassment) and organizational factors (gender ratio, sexual harassment policies, the role of employers) related to workers' attitudes toward and perceptions of sexual harassment. In Study 1, participants were 176 workers from a large, white-collar organization. In Study 2, participants were 75 workers from a smaller, blue-collar organization. Individuals from Study 2 experienced more sexual harassment, were more tolerant of sexual harassment, and perceived less behavior as sexual harassment than did individuals from Study 1. For both samples, organizational and individual factors predicted workers' attitudes toward and experiences of sexual harassment. Individual factors—such as age, gender, gender role, past experiences of sexual harassment, and perceptions of management's tolerance of sexual harassment—predicted attitudes toward sexual harassment. Workers' attitudes, the behavioral context, and the gender of the victim and perpetrator predicted perceptions of sexual harassment. The authors discussed the broader implications of these findings and suggested recommendations for future research.

Increasing central adiposity: the Nepean longitudinal study of young people aged 7-8 to 12-13y

BACKGROUND: Estimates of the prevalence of overweight and obesity in young people are typically based on body mass index (BMI). However, BMI may not indicate the level of central adiposity. Waist circumference has therefore been recommended to identify young people at risk of morbidity associated with central adiposity.

OBJECTIVE: To investigate (a) change in total and central adiposity between 7–8 and 12–13 y (b) agreement between classifying young people as overweight or obese based on total adiposity and central adiposity, and (c) risk factors associated with the development of total and central adiposity.

DESIGN: Anthropometric measurements were taken on 342 children in 1996/97 and 5 y later. Risk factors examined included birth weight, physical activity, TV viewing, pubertal status, parental adiposity, diet and socio-economic status.

RESULTS: Between 7–8 and 12–13 y indices of central adiposity increased more than total adiposity; waist circumference z-score increased by (means.d.) 0.740.92 and BMI z-score increased by 0.180.67. At 12–13 y there was moderate agreement between the two measures of adiposity (weighted kappa=0.64). However, waist circumference identified a greater number of young people as overweight or obese compared to BMI (41.2 vs 29.3%, P<0.001). Adiposity status at 7–8 y, maternal obesity, and pubertal stage were the strongest predictors of BMI status at 12–13 y. Risk factors associated with increased central adiposity were similar.

CONCLUSIONS: Overweight and obesity, as measured by waist circumference, is a bigger problem than is currently assessed by BMI. Targeting known risk factors for total adiposity may be an appropriate strategy for preventing increased central adiposity.

A pseudosymmetric cell adhesion regulatory domain in the β7 tail of the integrin α4β7 that interacts with focal adhesion kinase and src

The β7 integrins α4β7 and Eβ7 play key roles in forming the gut-associated lymphoid tissue, and contribute to chronic inflammation. The α4β7 integrin-mediated adhesion of activated lymphocytes is largely due to a transient increase in avidity from ligand-induced clustering of α4β7 at the cell-surface. Here, we report that L and D enantiomers of a cell-permeable peptide YDRREY encompassing residues 735-740 of the cytoplasmic tail of the β7 subunit inhibit the adhesion of T cells to β7 integrin ligands. The YDRREY peptide abrogated mucosal addressin cell adhesion molecule-1-induced clustering of α4β7 on the surface of activated T cells. A mutated form of the YDRREY peptide carrying either single or double conservative mutations at Tyr⁷³⁵Phe and Tyr⁷⁴⁰Phe was unable to inhibit T cell adhesion, suggesting that both tandem tyrosines are critical for activity. The YDRREY peptide was bound and phosphorylated by focal adhesion kinase and src, which may serve to sequester cytoskeletal proteins to the cytoplasmic domain of 4β7. The quasi-palindromic sequence YDRREY within the β7 cytoplasmic tail constitutes a cell adhesion regulatory domain that modulates the interaction of β7-expressing leukocytes with their endothelial and epithelial ligands. Cell-permeable peptidomimetics based on this motif have utility as anti-inflammatory reagents for the treatment of chronic inflammatory disease.

Chemistry, spectroscopy and analytical applications of certain chemiluminescent reactions

Chemiluminescence, the production of light from a chemical reaction, has found widespread use in analytical chemistry. Both tris (2, 2’-bipyridyl) ruthenium (II) and acidic potassium permanganate are chemiluminescence reagents that have been employed for the determination of a diverse range of analytes. This thesis encompasses some fundamental investigations into the chemistry and spectroscopy of these chemiluminescence reactions as well as extending the scope of their analytical applications. Specifically, a simple and robust capillary electrophoresis chemiluminescence detection system for the determination of codeine, O6-methylcodeine and thebaine is described, based upon the reaction of these analytes with chemically generated tris(2,2'-bipyridyl)ruthenium(III) prepared in sulfuric acid (0.05 M). The reagent solution was contained in a glass detection cell, which also held both the capillary and the cathode. The resultant chemiluminescence was monitored directly using a photomultiplier tube mounted flush against the base of the detection cell. The methodology, which incorporated a field amplification sample introduction procedure, realised detection limits (3a baseline noise) of 5 x 10~8 M for both codeine and O6-methylcodeine and 1 x 10~7 M for thebaine. The relative standard deviations of the migration times and the peak areas for the three analytes ranged from 2.2 % up to 2.5 % and 1.9 % up to 4.6 % respectively. Following minor instrumental modifications, morphine, oripavine and pseudomorphine were determined based upon their reaction with acidic potassium permanganate in the presence of sodium polyphosphate. To ensure no migration of the permanganate anion occurred, the anode was placed at the detector end whilst the electroosmotic flow was reversed by the addition of hexadimethrine bromide (0.001% m/v) to the electrolyte. The three analytes were separated counter to the electroosmotic flow via their interaction with a-cyclodextrin. The methodology realised detection limits (3 x S/N) of 2.5 x 10~7 M for both morphine and oripavine and 5 x 10~7 M for pseudomorphine. The relative standard deviations of the migration times and the peak heights for the three analytes ranged from 0.6 % up to 0.8 % and 1.5% up to 2.1 % respectively. Further improvements were made by incorporating a co-axial sheath flow detection cell. The methodology was validated by comparing the results realised using this technique with those obtained by high performance liquid chromatography (HPLC), for the determination of both morphine and oripavine in seven industrial process liquors. A complimentary capillary electrophoresis procedure with UV-absorption detection was also developed and applied to the determination of morphine, codeine, oripavine and thebaine in nine process liquors. The results were compared with those achieved using a standard HPLC method. Although over eighty papers have appeared in the literature on the analytical applications of acidic potassium permanganate chemiluminescence, little effort has been directed towards identifying the origin of the luminescence. It was found that chemiluminescence was generated during the manganese(III), manganese(IV) and manganese(VII) oxidations of sodium borohydride, sodium dithionite, sodium sulfite and hydrazine sulfate in acidic aqueous solution. From the corrected chemiluminescence spectra, the wavelengths of maximum emission were 689 ± 5 nm and 734 ± 5 nm when the reactions were performed in sodium hexametaphosphate and sodium dihydrogenorthophosphate or orthophosphoric acid environments respectively. The corrected phosphorescence spectrum of manganese(II) sulfate in a solution of sodium hexametaphosphate at 77 K, exhibited two peaks with maxima at 688 nm and 730 nm. The chemical and spectroscopic evidence presented strongly supported the postulation that the emission was an example of solution phase chemically induced phosphorescence of manganese(II). Thereby confirming earlier predictions that the chemiluminescence from acidic potassium permanganate reactions originated from an excited manganese(II) species. Additionally, these findings have had direct analytical application in that manganese(IV) was evaluated as a new reagent for chemiluminescence detection. The oxidations of twenty five organic and inorganic species, with solublised manganese(IV), were found to elicit analytically useful chemiluminescence with detection limits (3 x S/N) for Mn(II), Fe(II), morphine and codeine of 5 x 10-8 M, 2.5 x 10-7 M, 7.5 x 10-8 M and 5 x 10-8M, respectively. The corrected emission spectra from four different analytes gave wavelengths of maximum emission in the range from 733 nm up to 740 nm indicating that these chemiluminescence reactions also shared a common emitting species, excited manganese(II). Whilst several analytical problems were addressed in this thesis and answers to certain questions regarding the fundamentals of acidic potassium permanganate chemiluminescence were proposed, there are several areas that would benefit from further research. These are outlined in the final chapter of this thesis.

Photoinduced shape conversion and reconstruction of silver nanoprisms

A series of shapes of silver nanoplates were achieved by adjusting the concentration of citrate in the colloid in the photoinduced process. The local surface plasmon resonance (LSPR) of the silver nanoplates could be tuned gradually in a range from 740 to 440 nm. In contrast, the LSPR band can be photomediated again to the long wavelength region within 620-690 nm only by adding more citrate to the colloidal system. The initial silver nanoprisms converted to the discal shape under the light effect. In this conversion, the coupling effect of the plasmon resonance and the light source speeds up the photothermal reaction. Subsequently, the reconstruction of silver nanoprisms from the nanodisks took place in the presence of more citrate through the photoconversion.

Cost-effectiveness analysis of a hospital electronic medication management system

OBJECTIVE: To conduct a cost-effectiveness analysis of a hospital electronic medication management system (eMMS). METHODS: We compared costs and benefits of paper-based prescribing with a commercial eMMS (CSC MedChart) on one cardiology ward in a major 326-bed teaching hospital, assuming a 15-year time horizon and a health system perspective. The eMMS implementation and operating costs were obtained from the study site. We used data on eMMS effectiveness in reducing potential adverse drug events (ADEs), and potential ADEs intercepted, based on review of 1 202 patient charts before (n = 801) and after (n = 401) eMMS. These were combined with published estimates of actual ADEs and their costs. RESULTS: The rate of potential ADEs following eMMS fell from 0.17 per admission to 0.05; a reduction of 71%. The annualized eMMS implementation, maintenance, and operating costs for the cardiology ward were A$61 741 (US$55 296). The estimated reduction in ADEs post eMMS was approximately 80 actual ADEs per year. The reduced costs associated with these ADEs were more than sufficient to offset the costs of the eMMS. Estimated savings resulting from eMMS implementation were A$63-66 (US$56-59) per admission (A$97 740-$102 000 per annum for this ward). Sensitivity analyses demonstrated results were robust when both eMMS effectiveness and costs of actual ADEs were varied substantially. CONCLUSION: The eMMS within this setting was more effective and less expensive than paper-based prescribing. Comparison with the few previous full economic evaluations available suggests a marked improvement in the cost-effectiveness of eMMS, largely driven by increased effectiveness of contemporary eMMs in reducing medication errors.