(An) introduction to the study of public securities ..

Typewritten sheets in cover. Thesis (M.A.)--Boston University This item was digitized by the Internet Archive. Bibliography: p. 112-114

Vulnerability of Subsistence Systems Due to Social and Environmental Change: A Case Study in the Yukon-Kuskokwim Delta, Alaska

Arctic Indigenous communities have been classified as highly vulnerable to climate change impacts. The remoteness of Arctic communities, their dependence upon local species and habitats, and the historical marginalization of Indigenous peoples enhances this characterization of vulnerability. However, vulnerability is a result of diverse historical, social, economic, political, cultural, institutional, natural resource, and environmental conditions and processes and is not easily reduced to a single metric. Furthermore, despite the widespread characterization of vulnerability, Arctic Indigenous communities are extremely resilient as evidenced by subsistence institutions that have been developed over thousands of years. We explored the vulnerability of subsistence systems in the Cup’ik village of Chevak and Yup’ik village of Kotlik through the lens of the strong seasonal dimensions of resource availability. In the context of subsistence harvesting in Alaska Native villages, vulnerability may be determined by analyzing the exposure of subsistence resources to climate change impacts, the sensitivity of a community to those impacts, and the capacity of subsistence institutions to absorb these impacts. Subsistence resources, their seasonality, and perceived impacts to these resources were investigated via semi-structured interviews and participatory mapping-calendar workshops. Results suggest that while these communities are experiencing disproportionate impacts of climate change, Indigenous ingenuity and adaptability provide an avenue for culturally appropriate adaptation strategies. However, despite this capacity for resiliency, rapid socio-cultural changes have the potential to be a barrier to community adaptation and the recent, ongoing shifts in seasonal weather patterns may make seasonally specific subsistence adaptations to landscape particularly vulnerable.Les collectivités autochtones de l’Arctique sont classées comme étant fortement vulnérables aux incidences du changement climatique. L’éloignement des collectivités de l’Arctique, leur dépendance des espèces et des habitats locaux de même que la marginalisation historique des peuples autochtones intensifient cette vulnérabilité. Toutefois, la vulnérabilité est le résultat de conditions et de processus divers sur le plan historique, social, économique, politique, culturel, institutionnel, environnemental et des ressources naturelles. Il est difficile d’attribuer la vulnérabilité à un seul aspect. Malgré cette vaste caractérisation de la vulnérabilité, les collectivités autochtones de l’Arctique sont extrêmement résilientes, comme en attestent les modes de subsistance qui se sont développés au fil de milliers d’années. Nous avons exploré la vulnérabilité des systèmes de subsistance du village cup’ik de Chevak et du village yup’ik de Kotlik du point de vue des dimensions saisonnières fortes de la disponibilité des ressources. Dans le contexte des récoltes de subsistance des villages autochtones de l’Alaska, la vulnérabilité peut être déterminée au moyen de l’exposition des ressources de subsistance aux incidences du changement climatique, de la sensibilité d’une collectivité à ces incidences et de la capacité des institutions de subsistance à absorber ces incidences. Les ressources de subsistance, leur saisonnalité et les incidences perçues de ces ressources ont été étudiées au moyen d’entrevues semi-structurées et d’ateliers participatifs d’établissement de calendrier. Selon les résultats, bien que ces collectivités soient aux prises avec des incidences disproportionnées de changement climatique, l’ingéniosité et l’adaptabilité des Autochtones pavent le chemin à des stratégies d’adaptation convenant à leur culture. Cependant, malgré cette capacité de résilience, les changements socioculturels accélérés ont la possibilité de faire obstacle à l’adaptation collective, sans compter que la variation continue des tendances climatiques saisonnières peut rendre les adaptations de subsistance saisonnières au paysage particulièrement vulnérables

Data Quality from a Community-Based, Water-Quality Monitoring Project in the Yukon River Basin

This paper examines the quality of data collected by the Indigenous Observation Network, a community-based water-quality project in the Yukon River Basin of Alaska and Canada. The Indigenous Observation Network relies on community technicians to collect surface-water samples from as many as fifty locations to achieve their goals of monitoring the quality of the Yukon River and major tributaries in the basin and maintaining a long-term record of baseline data against which future changes can be measured. This paper addresses concerns about the accuracy, precision, and reliability of data collected by non-professionals. The Indigenous Observation Network data are examined in the context of a standard data life cycle: plan, collect, assure, and describe; as compared to professional scientific activities. Field and laboratory protocols and procedures of the Indigenous Observation Network are compared to those utilized by professional scientists. The data of the Indigenous Observation Network are statistically compared to those collected by professional scientists through a retrospective analysis of a set of water-quality parameters reported by all three projects over a number of years. No statistical differences were found among the three projects for pH, Calcium, Magnesium, or Alkalinity, although statistically significant differences were found for Sodium, Chloride, Sulfate, and Potassium concentrations. The statistical differences found were small and likely not significant in terms of interpreting the data for a variety of uses. Our results suggest that Indigenous Observation Network data are of high quality, and with consistent protocols and participant training, community based monitoring projects can collect data that are accurate, precise, and reliable

A Proteomic Approach to Study the Effect of Thiotaurine on Human Neutrophil Activation

Thiotaurine, a thiosulfonate related to taurine and hypotaurine, is formed by a metabolic process from cystine and generated by a transulfuration reaction between hypotaurine and thiocysteine. Thiotaurine can produce hydrogen sulfide (H2S) from its sulfane sulfur moiety. H2S is a gaseous signaling molecule which can have regulatory roles in inflammatory process. In addition, sulfane sulfur displays the capacity to reversibly bind to other sulfur atoms. Thiotaurine inhibits PMA-induced activation of human neutrophils, and hinders neutrophil spontaneous apoptosis. Here, we present the results of a proteomic approach to study the possible effects of thiotaurine at protein expression level. Proteome analysis of human neutrophils has been performed comparing protein extracts of resting or PMA-activated neutrophils in presence or in absence of thiotaurine. In particular, PMA-stimulated neutrophils showed high level of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression compared to the level of the same glycolytic enzyme in the resting neutrophils. Conversely, decreased expression of GAPDH has been observed when human neutrophils were incubated with 1 mM thiotaurine before activation with PMA. This result, confirmed by Western blot analysis, suggests again that thiotaurine shows a bioactive role in the mechanisms underlying the inflammatory process, influencing the energy metabolism of activated leukocytes and raises the possibility that thiotaurine, acting as a sulfur donor, could modulate neutrophil activation via persulfidation of target proteins, such as GAPDH

Does low volume high-intensity interval training elicit superior benefits to continuous low to moderate-intensity training in cancer survivors?

AIM To determine the impact of low volume high-intensity interval training (LVHIIT) and continuous low to moderate- intensity exercise training (CLMIT) on cardiovascular disease (CVD) risk and health outcomes in cancer survivors. METHODS Sedentary cancer survivors (n = 75, aged 51 ± 12 year) within 24 months of diagnosis, were randomised into three groups for 12 wk of LVHIIT (n = 25), CLMIT (n = 25) or control group (n = 25). The exercise intervention involved 36 sessions (three sessions per week). The LVHIIT group performed 7 × 30 s intervals (≥ 85% predicted maximal heart rate) with a 60 s rest between intervals, and the CLMIT group performed continuous aerobic training for 20 min (≤ 55% predicted maximal heart rate) on a stationary bike. Outcome variables were measured at baseline and at 12 weeks and analysed using a 3 × 2 (group × time) repeated measures ANCOVA to evaluate main and interaction effects. RESULTS Significant improvements (time) were observed for seven of the 22 variables (ES 0.35-0.97, P ≤ 0.05). There was an interaction effect (P < 0.01) after 12 wk in the LVHIIT group for six-minute walk test (P < 0.01; d = 0.97; 95%CI: 0.36, 1.56; large), sit to stand test (P < 0.01; d = -0.83; 95%CI: -1.40, -0.22; large ) and waist circumference reduction (P = 0.01; d = -0.48; 95%CI: -1.10, 0.10; medium). An interaction effect (P < 0.01) was also observed for quality of life in both the LVHIIT (d = 1.11; 95%CI: 0.50, 1.72; large) and CLMIT (d = 0.57; 95%CI: -0.00, 1.20; moderate) compared with the control group (d = -0.15; 95%CI: -0.95, 0.65; trivial). CONCLUSION Low-volume high-intensity training shows promise as an effective exercise prescription within the cancer population, showing greater improvements in cardiorespiratory fitness, lower body strength and waist circumference compared with traditional CLMIT and control groups. Both LVHIIT and CLMIT improved quality of life. A proposed benefit of LVHIIT is the short duration (3 min) of exercise required, which may entice more cancer survivors to participate in exercise, improving health outcomes and lowing the risk of CV

Biological hydropersulfides and related polysulfides - a new concept and perspective in redox biology

The chemical biology of thiols (RSH, e.g., cysteine and cysteine containing proteins/peptides) has been a topic of extreme interest for many decades due to their reported roles in protein structure/folding, redox signaling, metal ligation, cellular protection and enzymology. While many of the studies on thiol/sulfur biochemistry have focused on thiols, relatively ignored have been hydropersulfides (RSSH) and higher order polysulfur species (RSSn H, RSSn R, n > 1). Recent and provocative work has alluded to the prevalence and likely physiological importance of RSSH and related RSSn H. RSSH of cysteine (Cys-SSH) has been found to be prevalent in mammalian systems along with Cys-SSH-containing proteins. The RSSH functionality has not been examined to the extent of other biologically relevant sulfur derivatives (e.g., sulfenic acids, disulfides, etc.), whose roles in cell signaling are strongly indicated. The recent finding of Cys-SSH biosynthesis and translational incorporation into proteins is an unequivocal indication of its fundamental importance and necessitates a more profound look into the physiology of RSSH. In this Review, we discuss the currently reported chemical biology of RSSH (and related species) as a prelude to discussing their possible physiological roles. This article is protected by copyright. All rights reserved

Characterization of Ceftazidime Resistance Mechanisms in Clinical Isolates of Burkholderia pseudomallei from Australia

Burkholderia pseudomallei is a Gram-negative bacterium that causes the serious human disease, melioidosis. There is no vaccine against melioidosis and it can be fatal if not treated with a specific antibiotic regimen, which typically includes the third-generation cephalosporin, ceftazidime (CAZ). There have been several resistance mechanisms described for B. pseudomallei, of which the best described are amino acid changes that alter substrate specificity in the highly conserved class A β-lactamase, PenA. In the current study, we sequenced penA from isolates sequentially derived from two melioidosis patients with wild-type (1.5 µg/mL) and, subsequently, resistant (16 or ≥256 µg/mL) CAZ phenotypes. We identified two single-nucleotide polymorphisms (SNPs) that directly increased CAZ hydrolysis. One SNP caused an amino acid substitution (C69Y) near the active site of PenA, whereas a second novel SNP was found within the penA promoter region. In both instances, the CAZ resistance phenotype corresponded directly with the SNP genotype. Interestingly, these SNPs appeared after infection and under selection from CAZ chemotherapy. Through heterologous cloning and expression, and subsequent allelic exchange in the native bacterium, we confirmed the role of penA in generating both low-level and high-level CAZ resistance in these clinical isolates. Similar to previous studies, the amino acid substitution altered substrate specificity to other β-lactams, suggesting a potential fitness cost associated with this mutation, a finding that could be exploited to improve therapeutic outcomes in patients harboring CAZ resistant B. pseudomallei. Our study is the first to functionally characterize CAZ resistance in clinical isolates of B. pseudomallei and to provide proven and clinically relevant signatures for monitoring the development of antibiotic resistance in this important pathogen

Stratospheric aerosol - Observations, processes, and impact on climate

Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes

Allosteric Modulation of the HIV-1 gp120-gp41 Association Site by Adjacent gp120 Variable Region 1 (V1) N-Glycans Linked to Neutralization Sensitivity

The HIV-1 gp120-gp41 complex, which mediates viral fusion and cellular entry, undergoes rapid evolution within its external glycan shield to enable escape from neutralizing antibody (NAb). Understanding how conserved protein determinants retain functionality in the context of such evolution is important for their evaluation and exploitation as potential drug and/ or vaccine targets. In this study, we examined how the conserved gp120-gp41 association site, formed by the N- and Cterminal segments of gp120 and the disulfide-bonded region (DSR) of gp41, adapts to glycan changes that are linked to neutralization sensitivity. To this end, a DSR mutant virus (K601D) with defective gp120-association was sequentially passaged in peripheral blood mononuclear cells to select suppressor mutations. We reasoned that the locations of suppressors point to structural elements that are functionally linked to the gp120-gp41 association site. In culture 1, gp120 association and viral replication was restored by loss of the conserved glycan at Asn136 in V1 (T138N mutation) inconjunction with the L494I substitution in C5 within the association site. In culture 2, replication was restored with deletion of the N139INN sequence, which ablates the overlapping Asn141-Asn142-Ser-Ser potential N-linked glycosylation sequons inV1, in conjunction with D601N in the DSR. The 136 and 142 glycan mutations appeared to exert their suppressive effects by altering the dependence of gp120-gp41 interactions on the DSR residues, Leu593, Trp596 and Lys601. The 136 and/or 142glycan mutations increased the sensitivity of HIV-1 pseudovirions to the glycan-dependent NAbs 2G12 and PG16, and also pooled IgG obtained from HIV-1-infected individuals. Thus adjacent V1 glycans allosterically modulate the distal gp120-gp41 association site. We propose that this represents a mechanism for functional adaptation of the gp120-gp41 association site to an evolving glycan shield in a setting of NAb selection