19 research outputs found
Redox potentials, laccase oxidation, and antilarval activities of substituted phenols
No full textLaccases are copper-containing oxidases that are involved in sclerotization of the cuticle of mosquitoes and other insects. Oxidation of exogenous compounds by insect laccases may have the potential to produce reactive species toxic to insects. We investigated two classes of substituted phenolic compounds,
halogenated di- and trihydroxybenzenes and substituted di-tert-butylphenols, on redox potential, oxidation by laccase and effects on mosquito larval growth. An inverse correlation between the oxidation
potentials and laccase activity of halogenated hydroxybenzenes was found. Substituted di-tert-butylphenols however were found to impact mosquito larval growth and survival. In particular, 2,4-di-tert-butyl-
6-(3-methyl-2-butenyl)phenol (15) caused greater than 98% mortality of Anopheles gambiae larvae in a concentration of 180 nM, whereas 2-(3,5-di-tert-butyl-4-ydroxyphenyl)-2-methylpropanal oxime (13)
and 6,8-di-tert-butyl-2,2-dimethyl-3,4-dihydro-2H-chromene (33) caused 93% and 92% mortalities in concentrations of 3.4 and 3.7 lM, respectively. Larvae treated with di-tert-butylphenolic compounds died just before pupation
Electrochemical protease biosensor based on enhanced AC voltammetry using carbon nanofiber nanoelectrode arrays
No full textWe report an electrochemical method for measuring the activity of proteases using nanoelectrode arrays (NEAs) fabricated with vertically aligned carbon nanofibers (VACNFs). The VACNFs of ~150 nm in diameter and 3 to 5 μm in length were grown on conductive substrates and encapsulated in SiO[subscript 2] matrix. After polishing and plasma etching, controlled VACNF tips are exposed to form an embedded VACNF NEA. Two types of tetrapeptides specific to cancer-mediated proteases legumain and cathepsin B are covalently attached to the exposed VACNF tip, with a ferrocene (Fc) moiety linked at the distal end. The redox signal of Fc can be measured with AC voltammetry (ACV) at ~1 kHz frequency on VACNF NEAs, showing distinct properties from macroscopic glassy carbon electrodes due to VACNF’s unique interior structure. The enhanced ACV properties enable the kinetic measurements of proteolytic cleavage of the surface-attached tetrapeptides by proteases, further validated with a fluorescence assay. The data can be analyzed with a heterogeneous Michaelis-Menten model, giving “specificity constant” k[subscript cat]/K[subscript m] as (4.3 ± 0.8) x 10[superscript 4] Mˉ¹sˉ¹ for cathepsin B and (1.13 ± 0.38) x 10[superscript 4] Mˉ¹sˉ¹ for legumain. This method could be developed as portable multiplex electronic techniques for rapid cancer diagnosis and treatment monitoring
Enhanced Electron Transfer Rates by AC Voltammetry for Ferrocenes Attached to the End of Embedded Carbon Nanofiber Nanoelectrode Arrays
No full text
Kinetic properties of alternatively spliced isoforms of laccase-2 from Tribolium castaneum and Anopheles gambiae
No full textCitation: Gorman, M.J., Sullivan, L.I., Nguyen, T.D.T., Dai,H., Arakane,Y., Dittmer,
N.T.,…Kanost, M.R. (2012). Kinetic properties of alternatively spliced isoforms of
laccase-2 from Tribolium castaneum and Anopheles gambiae. Insect Biochemistry and
Molecular Biology, 42(3), 193-202.Laccase-2 is a highly conserved multicopper oxidase that functions in insect cuticle pigmentation and tanning. In many species, alternative splicing gives rise to two laccase-2 isoforms. A comparison of
laccase-2 sequences from three orders of insects revealed eleven positions at which there are conserved differences between the A and B isoforms. Homology modeling suggested that these eleven residues are
not part of the substrate binding pocket. To determine whether the isoforms have different kinetic properties, we compared the activity of laccase-2 isoforms from Tribolium castaneum and Anopheles
gambiae. We partially purified the four laccases as recombinant enzymes and analyzed their ability to oxidize a range of laccase substrates. The predicted endogenous substrates tested were dopamine, Nacetyldopamine (NADA), N-b-alanyldopamine (NBAD) and dopa, which were detected in T. castaneum previously and in A. gambiae as part of this study. Two additional diphenols (catechol and hydroquinone)and one non-phenolic substrate (2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)) were also tested. We observed no major differences in substrate specificity between the A and B isoforms. Dopamine,
NADA and NBAD were oxidized with catalytic efficiencies ranging from 51 to 550 min 1 mM 1.
These results support the hypothesis that dopamine, NADA and NBAD are endogenous substrates for both isoforms of laccase-2. Catalytic efficiencies associated with dopa oxidation were low, ranging from 8
to 30 min 1 mM 1; in comparison, insect tyrosinase oxidized dopa with a catalytic efficiency of 201 min 1 mM 1. We found that dopa had the highest redox potential of the four endogenous substrates, and this property of dopa may explain its poor oxidation by laccase-2. We conclude that laccase-2 splice isoforms are likely to oxidize the same substrates in vivo, and additional experiments will be required to
discover any isoform-specific functions
Electrochemical Protease Biosensor Based on Enhanced AC Voltammetry Using Carbon Nanofiber Nanoelectrode Arrays
No full textWe
report an electrochemical method for measuring the activity
of proteases using nanoelectrode arrays (NEAs) fabricated with vertically
aligned carbon nanofibers (VACNFs). The VACNFs of ∼150 nm in
diameter and 3–5 μm in length were grown on conductive
substrates and encapsulated in SiO2 matrix. After polishing
and plasma etching, controlled VACNF tips are exposed to form an embedded
VACNF NEA. Two types of tetrapeptides specific to cancer-mediated
proteases legumain and cathepsin B are covalently attached to the
exposed VACNF tip, with a ferrocene (Fc) moiety linked at the distal
end. The redox signal of Fc can be measured with AC voltammetry (ACV)
at ∼1 kHz frequency on VACNF NEAs, showing distinct properties
from macroscopic glassy carbon electrodes due to VACNF’s unique
interior structure. The enhanced ACV properties enable the kinetic
measurements of proteolytic cleavage of the surface-attached tetrapeptides
by proteases, further validated with a fluorescence assay. The data
can be analyzed with a heterogeneous Michaelis–Menten model,
giving “specificity constant” kcat/Km as (4.3 ± 0.8) ×
104 M–1s–1 for cathepsin
B and (1.13 ± 0.38) × 104 M–1 s–1 for legumain. This method could be developed
as portable multiplex electronic techniques for rapid cancer diagnosis
and treatment monitoring
Situating women: gender politics and circumstance in Fiji
No full textSince the time of decolonisation in Fiji, women’s organisations have navigated a complex political terrain. While they have stayed true to the aim of advancing women’s status, their work has been buffeted by national political upheavals and changing global and regional directions in development policy-making. This book documents how women activists have understood and responded to these challenges. It is the first book to write women into Fiji’s postcolonial history, providing a detailed historical account of that country’s gender politics across four tumultuous decades. It is also the first to examine the ‘situated’ nature of gender advocacy in the Pacific Islands more broadly. It does this by analysing trends in activity, from women’s radical and provocative activism of the 1960s to a more self-evaluative and reflexive mood of engagement in later decades, showing how interplaying global and local factors can shape women’s understandings of gender justice and their pursuit of that goal. [back cover
Enteral Nutrition in the Critically Ill. A Mixed-methods Study of Adherence to Evidence-Based Protocols, Nursing Responsibility and Teamwork
No full textObjectives: this study aimed to assess nurses’ practice and perception of their knowledge, responsibility and documentation in relation to enteral nutrition in the critically ill and to explore nurses’ attitudes towards establishing evidence-based practice and teamwork in three health care sectors in Jordan.
Background: poor nursing adherence to evidence-based guidelines has negative consequences leading to higher mortality rates, delayed recovery and longer length of stay. Evidence-based practice and team working is the key to minimising complications and discrepancies between nurses.
Design and methods: mixed-methods strategies were employed. A cluster randomised sample recruited 253 ICU nurse for the survey. Fourteen nurses were selected purposively for the interviews and fifty five patients were involved in bedside observations. Both statistical and thematic analysis findings were integrated and discussed together.
Results: Nurses revealed a tendency to undertake nutritional care despite the recognition clinical nutrition is a secondary role. In terms of nursing processes, nurses showed greater levels of knowledge and responsibility for ‘preventing complications’ and ‘evaluation’ more than ‘assessment’ and ‘identifying goals’. However, female nurses scored higher in taking responsibility for ‘assessment’ and ‘planning’ than male nurses. The internet and clinical experience were the most effective sources of knowledge along with university education and colleagues.
Nurses showed inconsistency in assessment tasks such as controlling gastric residual volume and confirming tube placements. Diarrhoea was the most frequent complication followed by abdominal pain, vomiting, tube dislodgment, weight loss. However, nurses realised that the incidences of complications is less likely when applying such evidence-based protocol for enteral nutrition.
Multidisciplinary team work was introduced as a source of evidence-based practice and establishing a nutritional team contributes to a greater nursing involvement in decision making. Poor cooperation and interaction within the team prohibits standardized care and increases the imparity in nursing practice.
Conclusion: increased nursing awareness of nutritional assessment through providing training programs and surveillance of clinical performance is necessary. Management should be concerned with offering an accessible source of knowledge, the required equipment and documentation systems. Enhancing collaboration between health care providers and offering appropriate counselling should also be emphasized
The dramaturgy of ritual performances in Indian parliamentary debates
No full textThe content, style and form of MPs' performances on the floor of both Houses of the
Indian Parliament has undergone dramatic change within the last decade. For example,
97% of the productive hours of the Winter (Nov-Dec) 2010 Session were lost due to
intense disruption by MPs across the political spectrum seeking to stall the House.
Moreover, an increasing number of Bills are debated for less than an hour, if at all, on
the floor of Parliament - raising the conceptual question of whether legislation can still
be considered one of parliament's key functions in India. These changes require, at the
very least, an attempt to re-conceptualize the meaning and significance attributed to
various tropes of parliamentary performances, including those which seemingly subvert
all notions of parliamentary procedure, decorum and etiquette. In my thesis, I adopt a
novel interdisciplinary analytical framework, drawing upon performance studies, microsociological
dramaturgy of face-to-face interaction, interpretations of procedural
invocations, rhetorical political analysis and the study of political rituals. My primary
research question was whether the concept of ritual could usefully be mapped onto
performances of debates in the Indian parliamentary context. I then asked what the
significance of the absence or presence of rituals in this context would mean. Two case
were studies selected for this analysis, namely the Prevention of Terrorism Act (2001-
2004) and the Women's Reservation Bill (1996-2011), informed by a more general
ethnography of the Indian Parliament undertaken for this research. Both studies were
chosen using the logic of 'extreme case study selection' as these performances exhibit
extreme forms of dramaturgical violence, protest and polarized rhetoric that is
increasingly reflective of the everyday performances of the Indian Parliament. In my
research, I have adopted an interpretivist-constructivist approach to the ethnographic
method and have conducted two tranches of field research in New Delhi for that
purpose. My analysis demonstrates the presence of a diverse range of rituals of debate
being performed simultaneously during the legislative process within the Indian
Parliament, namely, procedural rituals, interpersonal rituals and disruptive rituals. These
findings corroborate the broader argument that the study of rituals are integral to an
understanding of parliamentary processes. Moreover, instead of dismissing certain
aspects of performance (e.g. physical obstruction of debate) as being symptomatic of
what many scholars have called the 'decline of parliament', my findings support the
cause for re-signifying, or re-reading parliamentary disruption as supporting, rather than
diminishing, the processes of political representation and widening the spectrum of
forms of political action considered as legitimate modes of political deliberation. The
evolution of these newer, sometimes disruptive, forms of representative ritual can be
read into wider processes of vernacularization and mediatization currently transforming
the ethos, identity and modus operandi of the Indian Parliament
