181 research outputs found
Can current farmland landscapes feed declining steppe birds? Evaluating arthropod abundance for the endangered little bustard (Tetrax tetrax) in cereal farmland during the chick-rearing period: Variations between habitats and localities
Agriculture intensification threatens farmland bird populations because, among other reasons, it reduces the availability of food resources required to rear their offspring. In our study, we sampled and analyzed total arthropod abundance, biomass and richness, and orthopteran and coleopteran abundance and biomass in different agricultural habitats (alfalfa fields, stubble fields, grazed fields, and field margins) across 4 study localities with different levels of agriculture abandonment–intensification, comparing between areas used and not used by one of the most threatened farmland birds in Europe, the little bustard (Tetrax tetrax), during the chick-rearing season. Field margins were the taxonomically richest habitat, while alfalfa fields presented significantly higher total arthropod abundance and biomass than other habitats. All arthropod variables were the highest in the localities with clear conservation-focused agrarian management, and the lowest in the most intensive one. Areas used by little bustards had higher orthopteran and coleopteran abundance and biomass than nonused areas, except for coleopteran biomass in grazed fields. These results highlight the relevance of these arthropods for the species, the importance of dry alfalfa fields as food reservoirs in this critical time of year, the food scarcity in sites where agrarian management disregards farmland bird conservation, and the role of stubbles as providers of food resources during the chick-rearing season in areas used by the species. The adequate management of alfalfa fields and stubbles to provide those key resources seems crucial to improve little bustard breeding success.We thank the International Fund for Houbara Conservation (IFHC) and Fundación Patrimonio Natural (FPN) de Castilla y León in the persons of Cédric Ferlat (IFHC), David Cubero (Dirección General de Medio Natural, Junta de CyL), and Francisco Jiménez (FPN) for their financial, administrative, and logistic support. This paper also contributes to project S2018/EMT-4338 REMEDINAL TE-CM from Comunidad de Madrid. We are also thankful to the officers responsible for the Reserve of Villafáfila, Mariano Rodíguez y Jesús Palacios. Little bustard spring survey data were kindly provided by SEO-BirdLife.Peer reviewe
Nest and foraging‐site selection in Yellowhammers Emberiza citrinella: implications for chick provisioning
Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites and
nestling provisioning rate; when invertebrate availability is low, adults may take greater risks to provide
food for their young.
Aims To investigate nesting and foraging ecology in a declining farmland bird whose fledging success
is influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceived
predation risk during foraging can be mediated by vegetation structure.
Methods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arable
farmland. Foraging sites were compared with control sites of both the same and different microhabitats;
provisioning rate was related to habitat features of foraging-sites.
Results Foraging sites had low vegetation density, probably enhancing detection of predators, or high
invertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasing
vegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrate
abundance was low, provisioning rate increased with increasing vegetation cover.
Conclusions Vegetation structure at foraging sites suggests that a trade-off between predator detection
and prey availability influences foraging site selection in Yellowhammers. Associations between parental
provisioning rate and vegetation variables suggest that where invertebrate abundance is high birds
increase time spent scanning for predators at higher vegetation densities; however, when prey are scarce,
adults may take more risks to provide food for their young
Modeling the economic burden of postpartum hemorrhage due to substandard uterotonics in Ghana.
Uterotonics are essential in preventing postpartum hemorrhage (PPH), the leading direct cause of maternal death worldwide. However, uterotonics are often substandard in low- and middle-income countries, contributing to poor maternal health outcomes. This study examines the health and economic impact of substandard uterotonics in Ghana. A decision-tree model was built to simulate vaginal and cesarean section births across health facilities, uterotonic quality and utilization, PPH risk and diagnosis, and resulting health and economic outcomes. We utilized delivery data from Ghana's maternal health survey, risks of health outcomes from a Cochrane review, and E-MOTIVE trial data for health outcomes related to oxytocin quality. We compared scenarios with and without substandard uterotonics, as well as scenarios altering uterotonic use and care-seeking behaviors. We found that substandard uterotonic use contributes to 6.3 million and 1.6 million in costs due to substandard uterotonic use. Substandard uterotonics contribute to $6 million in long-term productivity losses from maternal mortality annually. Improving the quality of uterotonics could reduce 20,000 (11%) PPH cases, 5,000 (11%) severe PPH cases, and 100 (11%) deaths due to PPH annually in Ghana. Ensuring the quality of uterotonics would result in millions of dollars in cost savings and improve maternal health outcomes for the government and families in Ghana. Cost savings from improving uterotonic quality would provide financial protection and help Ghana advance toward Universal Health Coverage
Febrile illness diagnostics and the malaria-industrial complex: a socio-environmental perspective
Abstract Background Global prioritization of single-disease eradication programs over improvements to basic diagnostic capacity in the Global South have left the world unprepared for epidemics of chikungunya, Ebola, Zika, and whatever lies on the horizon. The medical establishment is slowly realizing that in many parts of sub-Saharan Africa (SSA), particularly urban areas, up to a third of patients suffering from acute fever do not receive a correct diagnosis of their infection. Main body Malaria is the most common diagnosis for febrile patients in low-resource health care settings, and malaria misdiagnosis has soared due to the institutionalization of malaria as the primary febrile illness of SSA by international development organizations and national malaria control programs. This has inadvertently created a “malaria-industrial complex” and historically obstructed our complete understanding of the continent’s complex communicable disease epidemiology, which is currently dominated by a mélange of undiagnosed febrile illnesses. We synthesize interdisciplinary literature from Ghana to highlight the complexity of communicable disease care in SSA from biomedical, social, and environmental perspectives, and suggest a way forward. Conclusion A socio-environmental approach to acute febrile illness etiology, diagnostics, and management would lead to substantial health gains in Africa, including more efficient malaria control. Such an approach would also improve global preparedness for future epidemics of emerging pathogens such as chikungunya, Ebola, and Zika, all of which originated in SSA with limited baseline understanding of their epidemiology despite clinical recognition of these viruses for many decades. Impending ACT resistance, new vaccine delays, and climate change all beckon our attention to proper diagnosis of fevers in order to maximize limited health care resources
Role of the p53/p21 system in the response of human colon carcinoma cells to Doxorubicin
BACKGROUND: Colon adenocarcinomas are refractory to a number of widely used anticancer agents. Multifactorial mechanisms have been implicated in this intrinsically resistant phenotype, including deregulation of cell death pathways. In this regard, the p53 protein has a well established role in the control of tumor cell response to DNA damaging agents; however, the relationship between p53-driven genes and drug sensitivity remains controversial. The present study investigates the role of the p53/p21 system in the response of human colon carcinoma cells to treatment with the cytotoxic agent doxorubicin (DOX) and the possibility to modify the therapeutic index of DOX by modulation of p53 and/or p21 protein levels. METHODS: The relationship between p53 and p21 protein levels and the cytotoxic effect of DOX was investigated, by MTT assay and western blot analysis, in HCT116 (p53-positive) and HT29 (p53-negative) colon cancer cells. We then assessed the effects of DOX in two isogenic cell lines derived from HCT116 by abrogating the expression and/or function of p53 and p21 (HCT116-E6 and HCT116 p21-/-, respectively). Finally, we evaluated the effect of pre-treatment with the piperidine nitroxide Tempol (TPL), an agent that was reported to induce p21 expression irrespective of p53 status, on the cytotoxicity of DOX in the four cell lines. Comparisons of IC50 values and apoptotic cell percentages were performed by ANOVA and Bonferroni's test for independent samples. C.I. calculations were performed by the combination Index method. RESULTS: Our results indicate that, in the colon carcinoma cell lines tested, sensitivity to DOX is associated with p21 upregulation upon drug exposure, and DOX cytotoxicity is potentiated by pre-treatment with TPL, but only in those cell lines in which p21 can be upregulated. CONCLUSIONS: p21 induction may significantly contribute to the response of colon adenocarcinomas cells to DOX treatment; and small molecules that can exploit p53-independent pathways for p21 induction, such as TPL, may find a place in chemotherapeutic protocols for the clinical management of colorectal cancer, where p53 function is often lost, due to genetic or epigenetic defects or to post-transcriptional inactivating mechanisms
Grazing management in saltmarsh ecosystems drives invertebrate diversity, abundance and functional group structure
1. Saltmarsh conservation management often involves livestock grazing
to maximise plant diversity and provide suitable breeding habitat for over-wintering
coastal birds. The effect of grazing on invertebrates is rarely quantified, but results
from limited studies of terrestrial and coastal grasslands demonstrate greater abundance
and species richness in un-grazed grassland.
2. The impact of short sward (<8 cm) cattle grazing on the ground dwelling invertebrate
community was assessed on an English inter-tidal upper salt marsh using pitfall
traps. Abundance, species richness, functional group structure, abundance of
coastal specialists, environmental factors that influence invertebrate habitat choice
and food web composition were compared for grazed and un-grazed marsh.
3. In total, 90 000 invertebrates were sampled. Predatory, zoophagus and detritivorous
Coleoptera were significantly more abundant on the un-grazed marsh. In contrast,
predatory Hemiptera and Araneae were significantly more abundant on the
grazed marsh. Sheet weaver spiders were significantly more abundant on the grazed
marsh, foliage running hunters and space web builders more abundant on the ungrazed
marsh. Most inter-tidal coastal specialist species exhibited clear habitat preference
for the grazed marsh. Total species richness was not significantly different
between grazing treatments.
4. Linear direct gradient analysis showed that two environmental variables influenced
by grazing intensity, soil temperature and vegetation height, significantly
explained the composition of invertebrate functional groups. Larger bodied invertebrates
dominated the un-grazed food web.
5. We conclude that both short sward cattle grazed and un-grazed saltmarsh habitat
should be maintained to maximise invertebrate abundance and diversity and provide
suitable habitat for coastal specialists
Integrated vector management for malaria control
Integrated vector management (IVM) is defined as "a rational decision-making process for the optimal use of resources for vector control" and includes five key elements: 1) evidence-based decision-making, 2) integrated approaches 3), collaboration within the health sector and with other sectors, 4) advocacy, social mobilization, and legislation, and 5) capacity-building. In 2004, the WHO adopted IVM globally for the control of all vector-borne diseases. Important recent progress has been made in developing and promoting IVM for national malaria control programmes in Africa at a time when successful malaria control programmes are scaling-up with insecticide-treated nets (ITN) and/or indoor residual spraying (IRS) coverage. While interventions using only ITNs and/or IRS successfully reduce transmission intensity and the burden of malaria in many situations, it is not clear if these interventions alone will achieve those critical low levels that result in malaria elimination. Despite the successful employment of comprehensive integrated malaria control programmes, further strengthening of vector control components through IVM is relevant, especially during the "end-game" where control is successful and further efforts are required to go from low transmission situations to sustained local and country-wide malaria elimination. To meet this need and to ensure sustainability of control efforts, malaria control programmes should strengthen their capacity to use data for decision-making with respect to evaluation of current vector control programmes, employment of additional vector control tools in conjunction with ITN/IRS tactics, case-detection and treatment strategies, and determine how much and what types of vector control and interdisciplinary input are required to achieve malaria elimination. Similarly, on a global scale, there is a need for continued research to identify and evaluate new tools for vector control that can be integrated with existing biomedical strategies within national malaria control programmes. This review provides an overview of how IVM programmes are being implemented, and provides recommendations for further development of IVM to meet the goals of national malaria control programmes in Africa
Structure-based mutagenesis reveals the albumin-binding site of the neonatal Fc receptor
Albumin is the most abundant protein in blood where it has a pivotal role as a transporter of fatty acids and drugs. Like IgG, albumin has long serum half-life, protected from degradation by pH-dependent recycling mediated by interaction with the neonatal Fc receptor, FcRn. Although the FcRn interaction with IgG is well characterized at the atomic level, its interaction with albumin is not. Here we present structure-based modelling of the FcRn–albumin complex, supported by binding analysis of site-specific mutants, providing mechanistic evidence for the presence of pH-sensitive ionic networks at the interaction interface. These networks involve conserved histidines in both FcRn and albumin domain III. Histidines also contribute to intramolecular interactions that stabilize the otherwise flexible loops at both the interacting surfaces. Molecular details of the FcRn–albumin complex may guide the development of novel albumin variants with altered serum half-life as carriers of drugs
Impact of urban agriculture on malaria vectors in Accra, Ghana
To investigate the impact of urban agriculture on malaria transmission risk in urban Accra larval and adult stage mosquito surveys, were performed. Local transmission was implicated as Anopheles spp. were found breeding and infected Anopheles mosquitoes were found resting in houses in the study sites. The predominant Anopheles species was Anopheles gambiae s.s.. The relative proportion of molecular forms within a subset of specimens was 86% S-form and 14% M-form. Anopheles spp. and Culex quinquefasciatus outdoor biting rates were respectively three and four times higher in areas around agricultural sites (UA) than in areas far from agriculture (U). The annual Entomological Inoculation Rate (EIR), the number of infectious bites received per individual per year, was 19.2 and 6.6 in UA and U sites, respectively. Breeding sites were highly transitory in nature, which poses a challenge for larval control in this setting. The data also suggest that the epidemiological importance of urban agricultural areas may be the provision of resting sites for adults rather than an increased number of larval habitats. Host-seeking activity peaked between 2–3 am, indicating that insecticide-treated bednets should be an effective control method
Alkylation of the Tumor Suppressor PTEN Activates Akt and β-Catenin Signaling: A Mechanism Linking Inflammation and Oxidative Stress with Cancer
PTEN, a phosphoinositide-3-phosphatase, serves dual roles as a tumor suppressor and regulator of cellular anabolic/catabolic metabolism. Adaptation of a redox-sensitive cysteinyl thiol in PTEN for signal transduction by hydrogen peroxide may have superimposed a vulnerability to other mediators of oxidative stress and inflammation, especially reactive carbonyl species, which are commonly occurring by-products of arachidonic acid peroxidation. Using MCF7 and HEK-293 cells, we report that several reactive aldehydes and ketones, e.g. electrophilic α,β-enals (acrolein, 4-hydroxy-2-nonenal) and α,β-enones (prostaglandin A2, Δ12-prostaglandin J2 and 15-deoxy-Δ-12,14-prostaglandin J2) covalently modify and inactivate cellular PTEN, with ensuing activation of PKB/Akt kinase; phosphorylation of Akt substrates; increased cell proliferation; and increased nuclear β-catenin signaling. Alkylation of PTEN by α,β-enals/enones and interference with its restraint of cellular PKB/Akt signaling may accentuate hyperplastic and neoplastic disorders associated with chronic inflammation, oxidative stress, or aging
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