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1.
J Acoust Soc Am ; 149(3): 2055, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33810766

RESUMO

Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection and localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates the amplitude and phase fluctuations of acoustic signals propagating along such paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO). A ground-based loudspeaker was placed at the base of the tower for vertical propagation or 56 m from the base of the tower for slanted propagation. Phasor scatterplots qualitatively characterize the amplitude and phase fluctuations of the received signals during different meteorological regimes. The measurements are also compared to a theory describing the log-amplitude and phase variances based on the spectrum of shear and buoyancy driven turbulence near the ground. Generally, the theory correctly predicts the measured log-amplitude variances, which are affected primarily by small-scale, isotropic turbulent eddies. However, the theory overpredicts the measured phase variances, which are affected primarily by large-scale, anisotropic, buoyantly driven eddies. Ground blocking of these large eddies likely explains the overprediction.

2.
BMC Public Health ; 21(1): 554, 2021 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-33743663

RESUMO

BACKGROUND: In South Africa, human geographic mobility is high as people engage in both permanent and temporary relocation, predominantly from rural to urban areas. Such mobility can compromise healthcare access and utilisation. The objective of this paper is to explore healthcare utilisation and its determinants in a cohort of internal migrants and permanent residents (non-migrants) originating from the Agincourt sub-district in South Africa's rural northeast. METHODS: A 5-year cohort study of 3800 individuals aged 18 to 40 commenced in 2017. Baseline data have been collected from 1764 Agincourt residents and 1334 temporary, mostly urban-based, migrants, and are analysed using bivariate analyses, logistic and multinomial regression models, and propensity score matching analysis. RESULTS: Health service utilisation differs sharply by migrant status and sex. Among those with a chronic condition, migrants had 0.33 times the odds of non-migrants to have consulted a health service in the preceding year, and males had 0.32 times the odds of females of having used health services. Of those who utilised services, migration status was further associated with the type of healthcare utilised, with 97% of non-migrant rural residents having accessed government facilities, while large proportions of migrants (31%) utilised private health services or consulted traditional healers (25%) in migrant destinations. The multinomial logistic regression analysis indicated that, in the presence of controls, migrants had 8.12 the relative risk of non-migrants for utilising private healthcare (versus the government-services-only reference category), and 2.40 the relative risk of non-migrants for using a combination of public and private sector facilities. These findings of differential utilisation hold under statistical adjustment for relevant controls and for underlying propensity to migrate. CONCLUSIONS: Migrants and non-migrants in the study population in South Africa were found to utilise health services differently, both in overall use and in the type of healthcare consulted. The study helps improve upon the limited stock of knowledge on how migrants interface with healthcare systems in low and middle-income country settings. Findings can assist in guiding policies and programmes to be directed more effectively to the populations most in need, and to drive locally adapted approaches to universal health coverage.

3.
Artigo em Inglês | MEDLINE | ID: mdl-33445686

RESUMO

Cardiovascular disease and the metabolic syndrome are major contributors to health care expenditure. Increased physical activity reduces disease risk. The study compared effects of walking up and down stairs at home with continuous, gym-based stair climbing on the disease risk factors of aerobic fitness, serum lipids, body composition, fasting blood glucose, and resting cardiovascular variables. Sedentary women (31.7 ± 1.4 years) were randomly assigned to home-based (n = 26) or gym-based (n = 24) climbing for five days.week-1 over an eight-week period. Each ascent required a 32.8-m climb, with home-based climbing matching the vertical displacement in the gym. Participants progressed from two ascents.day-1 to five ascents.day-1 in weeks 7 and 8. Relative to controls, stair climbing improved aerobic fitness (V˙O2max +1.63 mL.min-1.kg-1, 95% CI = 1.21-2.05), body composition (weight -0.99 kg, 95% CI = 1.38-0.60), and serum lipids (LDL cholesterol -0.20 mmol.L-1, 95% CI = 0.09-0.31; triglycerides -0.21 mmol.L-1, 95% CI = 0.15-0.27), with similar risk reductions for home and gym-based groups. Only the home-based protocol reduced fasting blood glucose. Discussion focuses on stair climbing bouts as time-efficient exercise and the potential benefits of a home-based intervention. Stair use at home offers a low-cost intervention for disease risk reduction to public health.


Assuntos
Subida de Escada , Adulto , Composição Corporal , Peso Corporal , Exercício Físico , Feminino , Humanos , Caminhada
4.
Sci Total Environ ; 747: 141112, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32791405

RESUMO

How anticipated climate change might affect long-term outcomes of present-day agricultural conservation practices remains a key uncertainty that could benefit water quality and biodiversity conservation planning. To explore this issue, we forecasted how the stream fish communities in the Western Lake Erie Basin (WLEB) would respond to increasing amounts of agricultural conservation practice (ACP) implementation under two IPCC future greenhouse gas emission scenarios (RCP4.5: moderate reductions; RCP8.5: business-as-usual conditions) during 2020-2065. We used output from 19 General Circulation Models to drive linked agricultural land use (APEX), watershed hydrology (SWAT), and stream fish distribution (boosted regression tree) models, subsequently analyzing how projected changes in habitat would influence fish community composition and functional trait diversity. Our models predicted both positive and negative effects of climate change and ACP implementation on WLEB stream fishes. For most species, climate and ACPs influenced species in the same direction, with climate effects outweighing those of ACP implementation. Functional trait analysis helped clarify the varied responses among species, indicating that more extreme climate change would reduce available habitat for large-bodied, cool-water species with equilibrium life-histories, many of which also are of importance to recreational fishing (e.g., northern pike, smallmouth bass). By contrast, available habitat for warm-water, benthic species with more periodic or opportunistic life-histories (e.g., northern hogsucker, greater redhorse, greenside darter) was predicted to increase. Further, ACP implementation was projected to hasten these shifts, suggesting that efforts to improve water quality could come with costs to other ecosystem services (e.g., recreational fishing opportunities). Collectively, our findings demonstrate the need to consider biological outcomes when developing strategies to mitigate water quality impairment and highlight the value of physical-biological modeling approaches to agricultural and biological conservation planning in a changing climate.


Assuntos
Ecossistema , Rios , Agricultura , Animais , Mudança Climática , Conservação dos Recursos Naturais , Hidrologia
5.
Exp Physiol ; 105(5): 917-918, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32352610
6.
Exp Physiol ; 104(11): 1605-1621, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31429500

RESUMO

NEW FINDINGS: What is the topic of this review? In this review, we examine the evidence for control mechanisms underlying exercise hyperpnoea, giving attention to the feedback from thin-fibre skeletal muscle afferents, and highlight the frequently conflicting findings and difficulties encountered by researchers using a variety of experimental models. What advances does it highlight? There has been a recent resurgence of interest in the role of skeletal muscle afferent involvement, not only as a mechanism of healthy exercise hyperpnoea but also in the manifestation of breathlessness and exercise intolerance in chronic disease. ABSTRACT: The ventilatory response to dynamic submaximal exercise is immediate and proportional to metabolic rate, which maintains isocapnia. How these respiratory responses are controlled remains poorly understood, given that the most tightly controlled variable (arterial partial pressure of CO2 /H+ ) provides no error signal for arterial chemoreceptors to trigger reflex increases in ventilation. This review discusses evidence for different postulated control mechanisms, with a focus on the feedback from group III/IV skeletal muscle mechanosensitive and metabosensitive afferents. This concept is attractive, because the stimulation of muscle mechanoreceptors might account for the immediate increase in ventilation at the onset of exercise, and signals from metaboreceptors might be proportional to metabolic rate. A variety of experimental models have been used to establish the contribution of thin-fibre muscle afferents in ventilatory control during exercise, with equivocal results. The inhibition of afferent feedback via the application of lumbar intrathecal fentanyl during exercise suppresses ventilation, which provides the most compelling supportive evidence to date. However, stimulation of afferent feedback at rest has no consistent effect on respiratory output. However, evidence is emerging for synergistic interactions between muscle afferent feedback and other stimulatory inputs to the central respiratory neuronal pool. These seemingly hyperadditive effects might explain the conflicting findings encountered when using different experimental models. We also discuss the increasing evidence that patients with certain chronic diseases exhibit exaggerated muscle afferent activation during exercise, resulting in enhanced cardiorespiratory responses. This might provide a neural link between the well-established limb muscle dysfunction and the associated exercise intolerance and exertional dyspnoea, which might offer therapeutic targets for these patients.


Assuntos
Exercício Físico/fisiologia , Hipercapnia/fisiopatologia , Hiperventilação/fisiopatologia , Fibras Musculares Esqueléticas/fisiologia , Neurônios Aferentes/fisiologia , Animais , Humanos , Ventilação Pulmonar/fisiologia , Respiração
8.
Exp Physiol ; 104(10): 1472-1481, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31206823

RESUMO

NEW FINDINGS: What is the central question of this study? Classically, the stimulation of thin-fibre skeletal muscle afferents, via the application of postexercise circulatory occlusion (PECO) at rest, fails to generate ventilatory responses. We used a new experimental protocol to examine whether the involvement of these metabosensitive afferents in ventilatory control can only be revealed during exercise, when other potentially synergistic inputs that increase central respiratory drive are activated. What is the main finding and its importance? We found that PECO of one leg augmented the ventilatory and heart rate responses to single-legged exercise of the contralateral leg, suggesting that metaboreceptive muscle afferents contribute to the control of the exercise hyperpnoea. ABSTRACT: Inhibition of thin-fibre skeletal muscle afferent neurotransmission attenuates ventilatory and cardiovascular responses to exercise. However, stimulation of muscle metaboreceptive afferents at rest, via postexercise circulatory occlusion (PECO), classically fails to generate increases in ventilation or heart rate. It is possible that the involvement of muscle afferent feedback in ventilatory control can only be revealed during exercise, when other potentially synergistic inputs that increase central respiratory drive are activated. Therefore, we assessed the cardiorespiratory responses to single-legged cycling exercise with or without PECO of the contralateral leg. Thirteen healthy participants performed left-legged cycling exercise (40 or 60 W) followed by either: (i) no PECO (Con trial); or (ii) PECO (PECO trial) of the left leg for 3 min. During this 3 min period, right-legged cycling exercise was performed at the same workload as the preceding left-legged exercise (40 or 60 W). During 60 W right-legged cycling, ventilation relative to baseline was significantly higher in the PECO versus Con trial (22.9 ± 2 versus 18.7 ± 1.8 l min-1 ; P < 0.05), but there was no difference between the trials performed at 40 W. The change in heart rate was significantly greater during right-legged cycling in the PECO versus Con trial in the 40 (41.2 ± 4 versus 34.1 ± 3.1 beats min-1 ; P < 0.05) and 60 W trials (49.7 ± 2.7 versus 43.4 ± 3.7 beats min-1 ; P < 0.05). There were no differences in oxygen uptake, carbon dioxide production and ratings of perceived exertion between trials. These findings suggest that stimulation of muscle metaboreceptive afferents can drive increases in ventilation and heart rate during dynamic exercise.


Assuntos
Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Músculo Esquelético/fisiologia , Taxa Respiratória/fisiologia , Vias Aferentes/fisiologia , Ciclismo/fisiologia , Pressão Sanguínea/fisiologia , Dióxido de Carbono/metabolismo , Retroalimentação Fisiológica , Humanos , Perna (Membro)/irrigação sanguínea , Masculino , Consumo de Oxigênio/fisiologia , Adulto Jovem
9.
J Biosoc Sci ; 51(6): 827-842, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31131777

RESUMO

Hypertension prevalence is on the rise in low- and middle-income countries (LMICs) like South Africa, and migration and its concomitant urbanization are often considered to be associated with this rise. However, relatively little is known about the relationship between blood pressure (BP) and internal migration - a highly prevalent population process in LMICs. This study employed data for a group of 194 adult men and women from an original pilot dataset drawn from the Agincourt Health and Demographic Surveillance System in north-east South Africa conducted in 2012. Migrants in the sample were identified, tracked and interviewed. The relationship between BP and migration distance and the number of months an individual spent away from his/her home village was estimated using robust OLS regression, controlling for a series of socioeconomic, health and behavioural characteristics. It was found that migrants who moved a longer distance and for longer durations had significantly higher systolic and diastolic blood pressures compared with shorter-term migrants and those who remained nearby or in their home village. These associations remained robust and statistically significant when adjusting for measures of socioeconomic conditions, as well as body mass index and the number of meals consumed per day. Migration, both in terms of distance and time away, explained significant variation in the blood pressure of migrants in this typical South African context. The findings suggest the need for further studies of the nutritional and psycho-social factors associated with geographic mobility that may be important to understand rising hypertension levels in LMICs.


Assuntos
Pressão Sanguínea , Países em Desenvolvimento , Hipertensão/epidemiologia , Mobilidade Social , Migrantes/estatística & dados numéricos , Adulto , Demografia , Emprego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , População Rural/estatística & dados numéricos , África do Sul , Urbanização
10.
Blood ; 133(24): 2559-2569, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-30975637

RESUMO

During wound healing, the distribution, availability, and signaling of growth factors (GFs) are orchestrated by their binding to extracellular matrix components in the wound microenvironment. Extracellular matrix proteins have been shown to modulate angiogenesis and promote wound healing through GF binding. The hemostatic protein von Willebrand factor (VWF) released by endothelial cells (ECs) in plasma and in the subendothelial matrix has been shown to regulate angiogenesis; this function is relevant to patients in whom VWF deficiency or dysfunction is associated with vascular malformations. Here, we show that VWF deficiency in mice causes delayed wound healing accompanied by decreased angiogenesis and decreased amounts of angiogenic GFs in the wound. We show that in vitro VWF binds to several GFs, including vascular endothelial growth factor-A (VEGF-A) isoforms and platelet-derived growth factor-BB (PDGF-BB), mainly through the heparin-binding domain (HBD) within the VWF A1 domain. VWF also binds to VEGF-A and fibroblast growth factor-2 (FGF-2) in human plasma and colocalizes with VEGF-A in ECs. Incorporation of the VWF A1 HBD into fibrin matrices enables sequestration and slow release of incorporated GFs. In vivo, VWF A1 HBD-functionalized fibrin matrices increased angiogenesis and GF retention in VWF-deficient mice. Treatment of chronic skin wounds in diabetic mice with VEGF-A165 and PDGF-BB incorporated within VWF A1 HBD-functionalized fibrin matrices accelerated wound healing, with increased angiogenesis and smooth muscle cell proliferation. Therefore, the VWF A1 HBD can function as a GF reservoir, leading to effective angiogenesis and tissue regeneration.


Assuntos
Neovascularização Fisiológica/fisiologia , Cicatrização/fisiologia , Fator de von Willebrand/metabolismo , Animais , Diabetes Mellitus Experimental , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Camundongos , Domínios Proteicos
11.
Elife ; 82019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30803483

RESUMO

Correct cell/cell interactions and motion dynamics are fundamental in tissue homeostasis, and defects in these cellular processes cause diseases. Therefore, there is strong interest in identifying factors, including drug candidates that affect cell/cell interactions and motion dynamics. However, existing quantitative tools for systematically interrogating complex motion phenotypes in timelapse datasets are limited. We present Motion Sensing Superpixels (MOSES), a computational framework that measures and characterises biological motion with a unique superpixel 'mesh' formulation. Using published datasets, MOSES demonstrates single-cell tracking capability and more advanced population quantification than Particle Image Velocimetry approaches. From > 190 co-culture videos, MOSES motion-mapped the interactions between human esophageal squamous epithelial and columnar cells mimicking the esophageal squamous-columnar junction, a site where Barrett's esophagus and esophageal adenocarcinoma often arise clinically. MOSES is a powerful tool that will facilitate unbiased, systematic analysis of cellular dynamics from high-content time-lapse imaging screens with little prior knowledge and few assumptions.


Assuntos
Comunicação Celular , Movimento Celular , Técnicas Citológicas/métodos , Células Epiteliais/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Esôfago/citologia , Humanos , Fenótipo
14.
Exp Physiol ; 104(3): 359-367, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30588681

RESUMO

NEW FINDINGS: What is the central question of this study? What is the relationship between the level of systemic hypercapnia and the magnitude of the additional hyperpnoea produced in response to a standardized level of muscle metaboreflex activation? What is the main finding and its importance? When a standardized activation of the muscle metaboreflex was combined with exposure to increasing levels of hypercapnia, the hyperpnoea this caused increased linearly. The concept of a synergistic interaction between the muscle metaboreflex and the central chemoreflex in humans is supported by this finding. ABSTRACT: Ventilation increases during muscle metaboreflex activation when postexercise circulatory occlusion (PECO) traps metabolites in resting human muscle, but only in conditions of concurrent systemic hypercapnia. We hypothesize that a linear relationship exists between the level of hypercapnia and the magnitude of the additional hyperpnoea produced in response to a standardized level of muscle metaboreflex activation. Fifteen male subjects performed four trials, in which the end-tidal partial pressure of carbon dioxide ( P ET , C O 2 ) was elevated by 1, 3, 7 or 10 mmHg above resting values using a dynamic end-tidal forcing system. In each trial, subjects were seated in an isometric dynamometer designed to measure ankle plantar flexor force. Rest for 2 min in room air was followed by 15 min of exposure to one of the four levels of hypercapnia, at which 5 min further rest was followed by 2 min of sustained isometric calf muscle contraction at 50% of predetermined maximal voluntary strength. Immediately before cessation of exercise, a cuff around the upper leg was inflated to a suprasystolic pressure to cause PECO for 3 min, before its deflation and a further 5 min of rest, concluding exposure to hypercapnia. The PECO consistently elevated mean arterial blood pressure by ∼10 mmHg in all trials, indicating similar levels of metaboreflex activation. Increased ventilation during PECO was related to P ET , C O 2 as described by the following linear regression equation: Change in minute ventilation (l min-1 ) = 0.85 ×  P ET , C O 2 (mmHg) + 0.80 (l min-1 ). This finding supports our hypothesis and furthers the idea of a synergistic interaction between muscle metaboreflex activation and central chemoreflex stimulation.


Assuntos
Hipercapnia/fisiopatologia , Reflexo/fisiologia , Pressão Sanguínea/fisiologia , Dióxido de Carbono/metabolismo , Exercício Físico/fisiologia , Humanos , Hipercapnia/metabolismo , Contração Muscular/fisiologia , Músculos/metabolismo , Músculos/fisiopatologia , Ventilação/métodos
15.
J Acoust Soc Am ; 144(3): 1258, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30424635

RESUMO

The prediction accuracy of outdoor sound is in large part limited by uncertainties in the state of the atmosphere. These uncertainties can potentially be reduced by inferring scaling parameters of the atmospheric surface layer from wind noise. Screened microphones sense wind noise as a result of mean atmospheric flow, turbulent eddy interaction with the windscreen, and pressure fluctuations within the turbulent flow. Under conditions of terrain homogeneity and atmospheric quasi-steadiness, the Monin-Obukhov similarity theory (MOST) states that only a handful of parameters governs the dynamics of the atmospheric surface layer. This study explores the relationships of atmospheric similarity parameters to the acoustic spectrum of wind noise in a convective boundary layer. Ambient noise data collected in a high desert during a 2007 long-range sound propagation experiment are analyzed for the purposes of establishing a nondimensional empirical relationship between the acoustic power spectrum and MOST parameters. Furthermore, this paper examines the consequences of inferring surface-layer scaling parameters with different parameter priors. This study shows that, for minimizing the variance in the inversion, the most important parameter to constrain is the Obukhov length.

16.
Nat Commun ; 9(1): 2163, 2018 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-29867149

RESUMO

Laminin, as a key component of the basement membrane extracellular matrix (ECM), regulates tissue morphogenesis. Here, we show that multiple laminin isoforms promiscuously bind to growth factors (GFs) with high affinity, through their heparin-binding domains (HBDs) located in the α chain laminin-type G (LG) domains. These domains also bind to syndecan cell-surface receptors, promoting attachment of fibroblasts and endothelial cells. We explore the application of these multifunctional laminin HBDs in wound healing in the type-2 diabetic mouse. We demonstrate that covalent incorporation of laminin HBDs into fibrin matrices improves retention of GFs and significantly enhances the efficacy of vascular endothelial cell growth factor (VEGF-A165) and platelet-derived growth factor (PDGF-BB) in promoting wound healing in vivo, under conditions where the GFs alone in fibrin are inefficacious. This laminin HBD peptide may be clinically useful by improving biomaterial matrices as both GF reservoirs and cell scaffolds, leading to effective tissue regeneration.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Heparina/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Laminina/metabolismo , Peptídeos/metabolismo , Animais , Sítios de Ligação , Células Cultivadas , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/fisiopatologia , Fibrina , Humanos , Masculino , Camundongos Endogâmicos C57BL , Ligação Proteica , Pele/lesões , Cicatrização
17.
Cell Death Differ ; 25(7): 1289-1303, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29352264

RESUMO

Desmosome components are frequently mutated in cardiac and cutaneous disorders in animals and humans and enhanced inflammation is a common feature of these diseases. Previous studies showed that inhibitor of Apoptosis Stimulating p53 Protein (iASPP) regulates desmosome integrity at cell-cell junctions and transcription in the nucleus, and its deficiency causes cardiocutaneous disorder in mice, cattle, and humans. As iASPP is a ubiquitously expressed shuttling protein with multiple functions, a key question is whether the observed cardiocutaneous phenotypes are caused by loss of a cell autonomous role of iASPP in cardiomyocytes and keratinocytes specifically or by a loss of iASPP in other cell types such as immune cells. To address this, we developed cardiomyocyte-specific and keratinocyte-specific iASPP-deficient mouse models and show that the cell-type specific loss of iASPP in cardiomyocytes or keratinocytes is sufficient to induce cardiac or cutaneous disorders, respectively. Additionally, keratinocyte-specific iASPP-deficient mice have delayed eyelid development and wound healing. In keratinocytes, junctional iASPP is critical for stabilizing desmosomes and iASPP deficiency results in increased and disorganized cell migration, as well as impaired cell adhesion, consistent with delayed wound healing. The identification of a cell autonomous role of iASPP deficiency in causing cardiocutaneous syndrome, impaired eyelid development and wound healing suggests that variants in the iASPP gene also may contribute to polygenic heart and skin diseases.


Assuntos
Desmossomos/metabolismo , Cardiopatias/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Queratinócitos/metabolismo , Miócitos Cardíacos/metabolismo , Proteínas Repressoras/deficiência , Dermatopatias/metabolismo , Animais , Desmossomos/genética , Desmossomos/patologia , Cardiopatias/genética , Cardiopatias/patologia , Queratinócitos/patologia , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/patologia , Dermatopatias/genética , Dermatopatias/patologia , Síndrome
18.
J Leukoc Biol ; 103(1): 119-128, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29345066

RESUMO

Compared to neutrophil chemoattractants, relatively little is known about the mechanism neutrophils use to respond to chemorepellents. We previously found that the soluble extracellular protein dipeptidyl peptidase IV (DPPIV) is a neutrophil chemorepellent. In this report, we show that an inhibitor of the protease activated receptor 2 (PAR2) blocks DPPIV-induced human neutrophil chemorepulsion, and that PAR2 agonists such as trypsin, tryptase, 2f-LIGRL, SLIGKV, and AC55541 induce human neutrophil chemorepulsion. Several PAR2 agonists in turn block the ability of the chemoattractant fMLP to attract neutrophils. Compared to neutrophils from male and female C57BL/6 mice, neutrophils from male and female mice lacking PAR2 are insensitive to the chemorepulsive effects of DPPIV or PAR2 agonists. Acute respiratory distress syndrome (ARDS) involves an insult-mediated influx of neutrophils into the lungs. In a mouse model of ARDS, aspiration of PAR2 agonists starting 24 h after an insult reduce neutrophil numbers in the bronchoalveolar lavage (BAL) fluid, as well as the post-BAL lung tissue. Together, these results indicate that the PAR2 receptor mediates DPPIV-induced chemorepulsion, and that PAR2 agonists might be useful to induce neutrophil chemorepulsion.


Assuntos
Dipeptidil Peptidase 4/farmacologia , Pulmão/imunologia , Neutrófilos/imunologia , Receptor PAR-2/fisiologia , Tripsina/farmacologia , Triptases/farmacologia , Animais , Células Cultivadas , Quimiotaxia de Leucócito , Modelos Animais de Doenças , Feminino , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , /metabolismo
19.
Popul Res Policy Rev ; 37(6): 1079-1108, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31543557

RESUMO

In a rural African context, the saying, "it takes a village to raise a child," suggests that community characteristics are substantially important in children's lives as they transition to adulthood. Are these contextual factors also related to youth migration? Demographers are uncertain about how community characteristics improve our understanding of an individual's propensity to migrate, beyond individual and household factors. In many low and middle-income country settings, youth become migrants for the first time in their lives to provide access to resources that their families need. We employ discrete-time event history models from the 20032011 Agincourt Health and socio-Demographic Surveillance System in rural South Africa to test whether markers of development in a village are associated with the likelihood of youth and young adults migrating, distinguishing between becoming temporary and permanent migrants during this critical life cycle phase. We find that village characteristics indeed differentially predict migration, but not nearly as substantially as might be expected.

20.
Ann Am Acad Pol Soc Sci ; 674(1): 27-58, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30416198

RESUMO

Using the 2009-2012 waves of the High School Longitudinal Survey, this article examines the role of parental engagement on academic achievement in the United States. Specifically, we examine the influence of parental engagement while also investigating the academic trajectories of racial/ethnic and immigrant groups, controlling for other standard factors. Results suggest that the progression of students' academic performance varies substantially by race/ethnicity and by immigrant generational status. After controlling for 9th grade test scores and family and other school-level characteristics, we find that first-generation immigrant youth generally have higher 11th grade test scores and lower probability of dropping out compared to native-born students who are second or third generation. Greater levels of parental engagement predict superior test scores and lower rates of dropout for youth of various racial and immigrant generation backgrounds, even in the presence of a variety of controls.

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