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1.
Heliyon ; 9(2): e13502, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36825191

RESUMO

Understanding how extended excess soil moisture exacerbated by extreme weather events affects changes in iron (Fe) chemistry is crucial for assessing environmental risk associated with soil phosphorus (P) in high P soils. The objective of our study was to assess the effects of three soil moisture regimes (field capacity, water saturation, and waterlogging), two Fe3+ nitrate level (Fe3+ nitrate addition and no Fe3+ nitrate addition), and the duration of incubation (0, 3, 7, 14, 21, 28, 35, 49, 63, 90, and 120 days) on the (i) reduction of ferric (Fe3+) to ferrous (Fe2+) iron, (ii) solubility of soil P, and (iii) soil microbial biomass and greenhouse gas emissions. Surface soils (0-20 cm) were collected from a maize silage field located in the Fraser Valley (British Columbia, Canada). Decreased redox potential (Eh) of 155 mV in waterlogged soils coincided with the reduction of Fe3+ to Fe2+ of about 1190 mg kg-1 and an increase in soil pH of 0.8 unit compared to field capacity regime at 120 days after pre-incubation (P < 0.001). The increase of pH is due to the microbially-mediated reduction of metal cations which consumes H+ cations. Water-extractable P (Pw) concentrations increased with increasing soil moisture regimes from 1.47 to 2.27, and 2.58 mg kg-1 under field capacity, water saturation, and waterlogged regime respectively. Mehlich-3 extractable P concentrations significantly decreased from 196 to 184 and 172 mg kg-1 under water saturation, field capacity, and waterlogged regime respectively. Concomitant to Pw concentrations, microbial biomass carbon and nitrogen as well as DOC, CO2 and N2O emissions increased with increasing soil moisture regimes. The Fe3+ nitrate addition had an inhibitory effect on Fe reduction, Pw concentration at the first 35 days, and DOC but a stimulating effect on N2O emission. A high N2O emission at the first 63 days, CO2 emission after 35 days, and a non-remarkable concentration of Fe2+ at the first 63 days with Fe3+ nitrate addition under waterlogged soil suggests that NO3 - is more preferable than Fe3+ as an electron acceptor. Our results showed that soils maintained under extended anoxic conditions could increase the soluble and available P and subsequent risk of P transport to surface and drainage waters, whereas Fe3+ nitrate addition could minimize or delay this effect.

2.
J Comp Pathol ; 189: 72-76, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34886988

RESUMO

Mixed pneumoconiosis is a pulmonary disease associated with several inhaled mineral irritants. Dust was found in the alveolar macrophages, alveolar and bronchial walls and pulmonary interstitial tissue of two female coyotes (Canis latrans). The dust contained large amounts of silica, coal, iron and copper particles, which were associated with severe pulmonary disease. Lung injury in the animals was characterized by pulmonary nodules, severe interstitial fibrosis, alveolar hyperplasia and bone formation within alveolar spaces. Coyotes inhaled mineral dust while roaming a field close to three mineral extraction zones. To our knowledge, this is the first report of the concomitant inhalation of multiple minerals in association with diffuse pulmonary ossification in the pulmonary parenchyma of two wild canine animals.


Assuntos
Coiotes , Doenças do Cão , Pneumoconiose , Animais , Cães , Poeira , Feminino , Pulmão , Osteogênese , Pneumoconiose/veterinária
3.
Glob Health Sci Pract ; 9(4): 990-999, 2021 12 31.
Artigo em Inglês | MEDLINE | ID: mdl-34933992

RESUMO

INTRODUCTION: Effective digital health management information systems (HMIS) support health data validity, which enables health care teams to make programmatic decisions and country-level decision making in support of international development targets. In 2015, mental health was included within the Sustainable Development Goals, yet there are few applications of HMIS of any type in the practice of mental health care in resource-limited settings. Zanmi Lasante (ZL), one of the largest providers of mental health care in Haiti, developed a digital data collection system for mental health across 11 public rural health facilities. PROGRAM INTERVENTION: We describe the development, implementation, and evaluation of the digital system for mental health data collection at ZL. To evaluate system reliability, we assessed the number of missing monthly reports. To evaluate data validity, we calculated concordance between the digital system and paper charts at 2 facilities. To evaluate the system's ability to inform decision making, we specified and then calculated 4 priority indicators. RESULTS: The digital system was missing 5 of 143 monthly reports across all facilities and had 74.3% (55/74) and 98% (49/50) concordance with paper charts. It was possible to calculate all 4 indicators, which led to programmatic changes in 2 cases. In response to implementation challenges, it was necessary to use strategies to increase provider buy-in and ultimately to introduce dedicated data clerks to keep pace with data collection and protect time for clinical work. LESSONS LEARNED: While demonstrating the potential of collecting mental health data digitally in a low-resource rural setting, we found that it was necessary to consider the ongoing roles of paper records alongside digital data collection. We also identified the challenge of balancing clinical and data collection responsibilities among a limited staff. Ongoing work is needed to develop truly sustainable and scalable models for mental health data collection in resource-limited settings.


Assuntos
Atenção à Saúde , População Rural , Coleta de Dados , Haiti , Humanos , Reprodutibilidade dos Testes
4.
Medicina (Kaunas) ; 57(11)2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34833355

RESUMO

Background and Objectives: Nutritional deficiencies are one of the main triggers for the development of gastrointestinal diseases, such as ulcerative colitis (UC). Therefore, the objective of the present work consisted of determining the nutrients present in the bone broth (BB) and evaluating their anti-inflammatory properties in a murine model of UC, induced by intrarectal administration of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS), and acetic acid (AcOH). The BB was prepared from the femur of bovine cattle and cooked in distilled water for 8 h at 100 ± 2 °C. Materials and Methods: The BB was administered ad libitum to BALB/c mice for 10 days before the induction of UC. Colon samples were collected for histological analysis and determination of cytokine expression levels by qPCR. Results: It was found that amino acids (AA) are the main nutritional contribution of BB, 54.56% of these correspond to essential AA. The prophylactic administration of BB in the murine model of UC reduced histological damage, decreased the expression of IL-1ß (61.12%), IL-6 (94.70%), and TNF-α (68.88%), and increased the expression of INF-γ (177.06%), IL-4 (541.36%), and IL-10 (531.97%). Conclusions: This study shows that BB has anti-inflammatory properties, and its consumption can decrease the symptoms of UC.


Assuntos
Colite Ulcerativa/etiologia , Colite Ulcerativa/terapia , Desnutrição/complicações , Nutrientes/uso terapêutico , Animais , Anti-Inflamatórios/uso terapêutico , Bovinos , Citocinas , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos BALB C , Ácido Trinitrobenzenossulfônico/uso terapêutico
5.
Artigo em Inglês | MEDLINE | ID: mdl-34168884

RESUMO

BACKGROUND: There is a growing literature in support of the effectiveness of task-shared mental health interventions in resource-limited settings globally. However, despite evidence that effect sizes are greater in research studies than actual care, the literature is sparse on the impact of such interventions as delivered in routine care. In this paper, we examine the clinical outcomes of routine depression care in a task-shared mental health system established in rural Haiti by the international health care organization Partners In Health, in collaboration with the Haitian Ministry of Health, following the 2010 earthquake. METHODS: For patients seeking depression care betw|een January 2016 and December 2019, we conducted mixed-effects longitudinal regression to quantify the effect of depression visit dose on symptoms, incorporating interaction effects to examine the relationship between baseline severity and dose. RESULTS: 306 patients attended 2052 visits. Each visit was associated with an average reduction of 1.11 in depression score (range 0-39), controlling for sex, age, and days in treatment (95% CI -1.478 to -0.91; p < 0.001). Patients with more severe symptoms experienced greater improvement as a function of visits (p = 0.04). Psychotherapy was provided less frequently and medication more often than expected for patients with moderate symptoms. CONCLUSIONS: Our findings support the potential positive impact of scaling up routine mental health services in low- and middle-income countries, despite greater than expected variability in service provision, as well as the importance of understanding potential barriers and facilitators to care as they occur in resource-limited settings.

6.
Foods ; 10(3)2021 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-33802384

RESUMO

For centuries, some Indigenous Peoples of the Americas have planted corn, beans and squash or pumpkins together in mounds, in an intercropping complex known as the Three Sisters. Agriculturally, nutritionally and culturally, these three crops are complementary. This literature review aims to compile historical foods prepared from the products of the Three Sisters planting system used in Indigenous communities in the region encompassing southern Quebec and Ontario in Canada, and northeastern USA. The review does not discuss cultural aspects of the Three Sisters cropping system or describe foods specific to any one Indigenous group, but rather, gives an overview of the historical foods stemming from this intercropping system, many foods of which are common or similar from one group to another. Some of the methods of food preparation used have continued over generations, some of the historical foods prepared are the foundation for foods we eat today, and some of both the methods and foods are finding revival.

7.
Plants (Basel) ; 9(11)2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33182648

RESUMO

Nutrient leaching losses from horticultural production threaten the quality of groundwater and freshwater systems worldwide. The objectives of this study were to (a) assess the effects of annual applications of ammonium sulfate fertilizer through fertigation (FERT) and broadcast (BROAD) on nutrient leaching losses and (b) determine the links among chemical property changes in leachates and soil with berry yields after 9 and 11 years of blueberry production. The long-term blueberry site was established in 2008 using seven combinations of treatments including an unfertilized control (CONT) and three N fertilizer rates (100%, 150%, 200% of recommended rates) using BROAD and FERT methods. Nutrients concentrations (NO3--N, NH4+-N and SO42--S) and chemical properties (pH and electrical conductivity (EC)) of leachate, sawdust and soil and berries were assessed. All FERT methods resulted in concentrations of NO3--N in the leachates > 100 mg L-1 with a maximum of 200 mg L-1 for FERT-200 during the growing season due to the easy transport of dissolved nutrients with the irrigation water. All BROAD methods resulted into concentrations of NO3--N in the leachates >10 mg L-1 with a maximum of 35 mg L-1 for BROAD-200 between April and July, as well as between November and April, indicating two periods of NO3--N leaching losses. The pattern observed with BROAD indicates that irrigation water in the summer and heavy rainfall in the winter contribute to NO3--N leaching losses. Concentrations of NH4+-N in the leachates >1 mg L-1 were measured under FERT with a peak at 64.78 mg L-1 for FERT-200, during the period April to August, due to NH4+'s ability to quickly move through the sawdust layer with irrigation water. Principal component analysis linked berry yield decrease with ammonium sulfate applications above recommended rates (FERT and BROAD) and with changes in soil pH and EC. Our results demonstrated that excess fertilizer applications above recommended rates using FERT and BROAD can threaten the sustainability of blueberry production by enhancing nutrient leaching losses and reducing berry yield.

8.
Environ Monit Assess ; 192(5): 322, 2020 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-32361825

RESUMO

Outdoor hog-rearing operations are of interest for both producers and consumers due to high product quality, animal welfare status, and low input and potential environmental risks. However, hog manure is rich in phosphorus (P), an environmentally sensitive nutrient, and distribution of different P fractions down the soil profile in these production systems is not well understood. The objective of this study was to determine the spatial variability of soil P in different soil depth intervals following 1-year outdoor farrowing sows in a 0.5-ha paddock in cold-temperate climate of Eastern Canada. Soil samples were collected with 0-15, 15-30, and > 30 cm depth intervals (up to 60 cm or the depth that sampling was possible) in grazing/rooting, feeding, wallow, and farrowing hut areas. Soil samples were analyzed for Olsen P (Pol), organic P (PO), and total P (PT). Areas with more frequent presence of hogs showed 45-80% greater Pol concentrations, and movement of soluble PO down the soil profile was higher in these areas compared with the grazing/rooting area. The PO formed 80% of PT throughout the paddock, and the spatial distribution of PO was similar to PT in all soil depth intervals but different from Pol. Results also showed that PO concentrations in the paddock decreased at > 30 cm depth except for the feeding area. Findings of this study reveal that farrowing sow cycle in an outdoor hog-rearing farm setting can result in hot spots of P, which enhance the risk of environmental pollution.


Assuntos
Criação de Animais Domésticos , Monitoramento Ambiental , Fósforo , Solo , Suínos , Animais , Canadá , Feminino , Fósforo/análise , Solo/química
9.
Artigo em Inglês | MEDLINE | ID: mdl-32180989

RESUMO

Between 2010 and 2019 the international health care organization Partners In Health (PIH) and its sister organization Zanmi Lasante (ZL) mounted a long-term response to the 2010 Haiti earthquake, focused on mental health. Over that time, implementing a Theory of Change developed in 2012, the organization successfully developed a comprehensive, sustained community mental health system in Haiti's Central Plateau and Artibonite departments, directly serving a catchment area of 1.5 million people through multiple diagnosis-specific care pathways. The resulting ZL mental health system delivered 28 184 patient visits and served 6305 discrete patients at ZL facilities between January 2016 and September 2019. The experience of developing a system of mental health services in Haiti that currently provides ongoing care to thousands of people serves as a case study in major challenges involved in global mental health delivery. The essential components of the effort to develop and sustain this community mental health system are summarized.

10.
Confl Health ; 14: 13, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32140176

RESUMO

BACKGROUND: The Zanmi Lasante Depression Symptom Inventory (ZLDSI) is a screening tool for major depression used in 12 primary care clinics in Haiti's Central Plateau. Although previously validated in a clinic-based sample, the present study is the first to evaluate the validity and clinical utility of the ZLDSI for depression screening in a school-based population in central Haiti. METHODS: We assessed depressive symptoms in a school-based sample of transitional age youth (18-22 years; n = 120) with the ZLDSI. Other mental health-related assessments included a modified Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID) for current Major Depressive Episode, the Center for Epidemiologic Studies Depression Scale, and selected items adapted from the Global School-Based Health Survey mental health module. Diagnostic assignments of major depressive episode (MDE) were based on modified SCID interviews. RESULTS: The ZLDSI demonstrated good overall accuracy in identifying current MDE (Area under the Curve = .92, 95% CI = .86, .98, p < .001). We ascertained ≥12 as the optimal cut-off point to screen for depression with a sensitivity of 100% and a specificity of 73.9%. In addition, the ZLDSI was associated with other measures of depressive symptoms, suggesting that it demonstrates construct validity. CONCLUSIONS: Study findings support that the ZLDSI has clinical utility for screening for depression among school-going transitional age youth.

11.
Psychiatry Res ; 269: 369-375, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30173043

RESUMO

The association between earthquakes and youth post-traumatic stress disorder (PTSD) has been well described, but little is known about the relationship between other stressful life events (SLEs) and PTSD among earthquake-affected youth. This study examines a variety of SLEs, including earthquake, and their association with PTSD among school-going Haitian youth following a major earthquake in 2010. In 2013, we assessed 120 students ages 18-22 for PTSD and other SLEs using a modified Structured Clinical Interview for DSM-IV (SCID)-based interview and the Stressful Life Events Checklist (SLE Checklist). Only 51.7% of participants on the SLE Checklist and 31.7% in the interview endorsed being affected by the earthquake or another disaster. Sexual assault showed the strongest association with PTSD in multivariable logistic regression. Contrary to our hypothesis, exposure to earthquake or another disaster was not significantly associated with current PTSD. In this population, exposure to interpersonal violence may have had a greater impact on PTSD risk than exposure to natural disaster. These data underscore the need to examine and reduce both acute and chronic stressors among disaster-affected youth.


Assuntos
Acontecimentos que Mudam a Vida , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Estudantes/psicologia , Adolescente , Terremotos , Exposição à Violência/psicologia , Exposição à Violência/estatística & dados numéricos , Feminino , Haiti/epidemiologia , Humanos , Masculino , Prevalência , Instituições Acadêmicas/estatística & dados numéricos , Transtornos de Estresse Pós-Traumáticos/psicologia , Adulto Jovem
12.
PLoS One ; 13(6): e0199313, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29924866

RESUMO

This study evaluates the use of a mental health mobile clinic to overcome two major challenges to the provision of mental healthcare in resource-limited settings: the shortage of trained specialists; and the need to improve access to safe, effective, and culturally sound care in community settings. Employing task-shifting and supervision, mental healthcare was largely delivered by trained, non-specialist health workers instead of specialists. A retrospective chart review of 318 unduplicated patients assessed and treated during the mobile clinic's first two years (January 2012 to November 2013) was conducted to explore outcomes. These data were supplemented by a quality improvement questionnaire, illustrative case reports, and a qualitative interview with the mobile clinic's lead community health worker. The team evaluated an average of 42 patients per clinic session. The most common mental, neurological, or substance abuse (MNS) disorders were depression and epilepsy. Higher follow-up rates were seen among those with diagnoses of bipolar disorder and neurological conditions, while those with depression or anxiety had lower follow-up rates. Persons with mood disorders who were evaluated on at least two separate occasions using a locally developed depression screening tool experienced a significant reduction in depressive symptoms. The mental health mobile clinic successfully treated a wide range of MNS disorders in rural Haiti and provided care to individuals who previously had no consistent access to mental healthcare. Efforts to address these common barriers to the provision of mental healthcare in resource-limited settings should consider supplementing clinic-based with mobile services.


Assuntos
Serviços de Saúde Comunitária , Atenção à Saúde , Serviços de Saúde Mental , Unidades Móveis de Saúde , População Rural , Escolaridade , Feminino , Seguimentos , Haiti , Humanos , Masculino , Resultado do Tratamento
13.
Artigo em Inglês | MEDLINE | ID: mdl-28596905

RESUMO

BACKGROUND: Engagement and training of educators in student mental health holds promise for promoting access to care as a task sharing strategy but has not been well-studied in low-income regions. METHODS: We used a prospective and convergent mixed methods design to evaluate a customized school mental health 2½ day training for teachers in rural Haiti (n = 22) as the initial component of formative research developing a school-based intervention to promote student mental health. Training prepared teachers to respond to student mental health needs by providing psychoeducational and practical support to facilitate access to care. We examined level of participation and evaluated feasibility, acceptability, and perceived effectiveness by calculating mean scores on self-report Likert-style items eliciting participant experience. We examined effectiveness of the training on improving mental health knowledge and attitudes by comparing mean scores on an assessment administered pre- and post-training. Finally, we examined self-report written open-ended responses and focus group discussion (FGD) interview data bearing on perceived feasibility, acceptability, and effectiveness to contextualize participant ratings of training and to identify recommendations for enhancing the utility of mental health training locally for educators. RESULTS: Mean scores of knowledge and attitudes significantly improved between the pre-test and post-tests; e.g., knowledge improved from 58% correct at baseline to 68% correct on the second post-test (p = 0.039). Mean ratings of the training were favorable across all categories and FGD data demonstrated widespread participant endorsement of training acceptability and effectiveness; participants recommended extending the duration and number of training sessions. CONCLUSIONS: Findings support feasibility, acceptability, and a limited scope of effectiveness of brief mental health training for secondary school teachers in Haiti. Further development of approaches to engage teachers in promoting school mental health through training is warranted.

14.
Int J Soc Psychiatry ; 63(4): 314-324, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28367718

RESUMO

BACKGROUND: Task-sharing with teachers to promote youth mental health is a promising but underdeveloped strategy in improving care access in low-income countries. AIMS: To assess feasibility, acceptability and utility of the teacher accompaniment phase of a school-based Teacher- Accompagnateur Pilot Study (TAPS) in Haiti. METHODS: We assigned student participants, aged 18-22 years ( n = 120), to teacher participants ( n = 22) within four Haitian schools; we instructed participants to arrange meetings with their assigned counterparts to discuss mental health treatment, academic skills, and/or well-being. We measured student and teacher perceived feasibility, acceptability and utility of meetings with self-report Likert-style questions. We examined overall program feasibility by the percentage of students with a documented meeting, acceptability by a composite measure of student satisfaction and utility by the percentage with identified mental health need who discussed treatment with a teacher. RESULTS: Favorable ratings support feasibility, acceptability and utility of teacher- accompagnateur meetings with students. The majority of students (54%) met with a teacher. Among students with an identified mental disorder, 43.2% discussed treatment during a meeting. CONCLUSION: This accompaniment approach to mental health task-sharing with teachers provided a school-based opportunity for students with mental health need to discuss treatment and has potential relevance to other low-income settings.


Assuntos
Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Saúde Mental , Serviços de Saúde Escolar/estatística & dados numéricos , Estudantes/psicologia , Ensino , Adolescente , Feminino , Haiti , Humanos , Masculino , Transtornos Mentais/terapia , Projetos Piloto , Estudos Prospectivos , Pesquisa Qualitativa , Autorrelato , Adulto Jovem
15.
Int J Soc Psychiatry ; 63(3): 261-274, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28367719

RESUMO

BACKGROUND: The mental health treatment gap for youth in low- and middle-income countries (LMICs) is substantial; strategies for redress are urgently needed to mitigate the serious health and social consequences of untreated mental illness in youth. AIMS: To estimate the burden of major depressive episode (MDE) and posttraumatic stress disorder (PTSD) as well as utilization of care among Haitian youth in order to describe the mental health treatment gap in a LMIC setting. METHODS: We estimated the point prevalence of MDE, PTSD, and subthreshold variants in a school-based sample of youth ( n = 120, ages 18-22 years) using a modified Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID)-based interview and examined treatment utilization among those receiving one of these diagnoses. We assessed additional psychopathology with self-report measures to examine validity of study diagnostic assignments. RESULTS: The combined prevalence of full-syndrome or subthreshold MDE or PTSD was high (36.7%). A large majority of affected individuals (88.6%) had accessed no mental health services in the health sector, and 36.4% had accessed no care of any kind in either the health or folk sectors in the past year. CONCLUSION: Findings demonstrate a high mental health burden among Haiti's youth and that many youth with MDE and PTSD are not accessing mental health care.


Assuntos
Transtorno Depressivo Maior/epidemiologia , Transtorno Depressivo Maior/terapia , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Transtornos de Estresse Pós-Traumáticos/terapia , Adolescente , Efeitos Psicossociais da Doença , Estudos Transversais , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Haiti/epidemiologia , Humanos , Masculino , Saúde Mental , Projetos Piloto , Pobreza , Escalas de Graduação Psiquiátrica , Psicoterapia/métodos , Instituições Acadêmicas , Autorrelato , Adulto Jovem
16.
PLoS One ; 6(6): e20619, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21731620

RESUMO

Precipitous declines in Africa's native fauna and flora are recognized, but few comprehensive records of these changes have been compiled. Here, we present population trends for African elephants in the 6,213,000 km² Sudano-Sahelian range of West and Central Africa assessed through the analysis of aerial and ground surveys conducted over the past 4 decades. These surveys are focused on the best protected areas in the region, and therefore represent the best case scenario for the northern savanna elephants. A minimum of 7,745 elephants currently inhabit the entire region, representing a minimum decline of 50% from estimates four decades ago for these protected areas. Most of the historic range is now devoid of elephants and, therefore, was not surveyed. Of the 23 surveyed elephant populations, half are estimated to number less than 200 individuals. Historically, most populations numbering less than 200 individuals in the region were extirpated within a few decades. Declines differed by region, with Central African populations experiencing much higher declines (-76%) than those in West Africa (-33%). As a result, elephants in West Africa now account for 86% of the total surveyed. Range wide, two refuge zones retain elephants, one in West and the other in Central Africa. These zones are separated by a large distance (∼900 km) of high density human land use, suggesting connectivity between the regions is permanently cut. Within each zone, however, sporadic contacts between populations remain. Retaining such connectivity should be a high priority for conservation of elephants in this region. Specific corridors designed to reduce the isolation of the surveyed populations are proposed. The strong commitment of governments, effective law enforcement to control the illegal ivory trade and the involvement of local communities and private partners are all critical to securing the future of elephants inhabiting Africa's northern savannas.


Assuntos
Ecossistema , Elefantes/fisiologia , Extinção Biológica , África Central , África Ocidental , Animais , Conservação dos Recursos Naturais/estatística & dados numéricos , Coleta de Dados , Bases de Dados como Assunto , Geografia , Humanos , Carne , Dinâmica Populacional , Fatores de Tempo
17.
Nano Lett ; 6(11): 2554-60, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17090090

RESUMO

The dynamical behavior of a nanomeniscus is investigated with a oscillating nanoneedle recording information on the change of the shape and viscous contribution. At the air-glycerol interface, the dynamical properties exhibit a nonlinear behavior making the nanomeniscus evolution similar to a first-order phase transition. Also shown is the capability to record height images of the liquid interface with resolutions at nanometer scale. At the air-water interface, evaporation leads to more complex dynamical properties. The viscous damping first increases as a consequence of a thinning effect, then, when the contact angle reaches zero, the nanomeniscus is unable to sustain the dissipation.


Assuntos
Glicerol/química , Nanotubos/química , Ar , Teste de Materiais , Oscilometria/métodos , Propriedades de Superfície , Fatores de Tempo , Molhabilidade
18.
Cell Mol Biol (Noisy-le-grand) ; 50(3): 255-66, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15209346

RESUMO

Atomic force microscopy (AFM) is a non-invasive microscopy to explore living biological systems like cells in liquid environment. Thus AFM is an appropriate tool to investigate surface chemical modification and its influence on biological systems. In particular, control over biomaterial surface chemistry can result in a regulated cell response. This report investigates the influence of adhesive and non-adhesive surfaces on the cell morphology and the influence of the cytoskeleton structure on the local mechanical properties. In this study, the main work concerns a thorough investigation of the height images obtained with an AFM as therecorded images provide the evolution of the mechanical properties of the cell as function of its local structure. Information on the cell elasticity due to the cytoskeleton organization is deduced when comparing the AFM tip indentation depth versus the distance between the cytoskeleton bundles for the different samples.


Assuntos
Células/ultraestrutura , Citoesqueleto/ultraestrutura , Microscopia de Força Atômica , Adesão Celular , Forma Celular , Elasticidade , Osteoblastos/ultraestrutura , Plásticos/química , Dióxido de Silício/química
19.
Cytometry A ; 54(1): 36-47, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12820119

RESUMO

BACKGROUND: Atomic force microscopy (AFM) can be used to visualize the cell morphology in an aqueous environment and in real time. It also allows the investigation of mechanical properties such as cell compliance as a function of cell attachment. This study characterized and evaluated osteoblast adhesion by AFM. METHODS: Human bone marrow stromal cells were cultured on two types of surface to induce weak and strong cellular adhesions. RESULTS: Cells were considered as spreading if they had a flattened and lengthened shape and a cytoskeletal organization in the submembrane cytosolic region. Cell detachment demonstrated different adhesion states between adherent cells to be distinguished. The stability of the cytoskeletal fibers indicated that cells were adherent. The elastic modulus was estimated by two complementary approaches. The values deduced were between 3 x 10(2) and 2 x 10(5) Nm(-2) according to the state of cell adhesion and the approaches used to measure this elastic modulus. CONCLUSIONS: Although the results were qualitative, a relation may be deduced between the elasticity of living cells as demonstrated by cytoskeletal organization and the state of cell adhesion. The technique could be used to determine the adhesion state of an adherent osteoblast observed under AFM.


Assuntos
Células da Medula Óssea/citologia , Citometria por Imagem , Microscopia de Força Atômica , Osteoblastos/citologia , Células da Medula Óssea/fisiologia , Adesão Celular/fisiologia , Células Cultivadas , Humanos , Microscopia Eletrônica de Varredura , Osteoblastos/fisiologia , Células Estromais/fisiologia
20.
J Colloid Interface Sci ; 251(2): 278-83, 2002 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-16290731

RESUMO

In order to establish a 3-aminopropyltriethoxysilane (APTES) grafting procedure with limited number of APTESs noncovalently linked to the silica surface, two different methods of grafting (in acid-aqueous solution and in anhydrous solution) were compared. The grafted surface state was investigated by atomic force microscopy (AFM). The stability of the grafting was checked at different temperatures by AFM. Continuous and plane APTES grafted surfaces were successfully prepared using both grafting preparations. The grafting in an anhydrous solution behaves homogeneously and stably compared to the grafting in an acid-aqueous solution. Moreover, with anhydrous solution, results showed that a unique monolayer of APTES was grafted.


Assuntos
Membranas Artificiais , Silanos/química , Dióxido de Silício/química , Propilaminas , Propriedades de Superfície
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