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1.
Artículo en Inglés | MEDLINE | ID: mdl-33577284

RESUMEN

Hierarchically porous ceramics with a high specific surface area and interconnected porosity may find potential application as particulate filters, catalyst supports, and battery electrodes. We report the design and programmable assembly of cellular ceramic architectures with controlled pore size, volume, and interconnectivity across multiple length scales via direct foam writing. Specifically, binary colloidal gel foams are created that contain entrained bubbles stabilized by the irreversible adsorption of attractive alumina and carbon (porogen) particles at their air-water interfaces. Composition effects on foam ink rheology and printing behavior are investigated. Sintered ceramic foams exhibited specific permeabilities that increased from 2 × 10-13 to 1 × 10-12 m2 and compressive strengths that decreased from 40 to 1 MPa, respectively, with increasing specific interfacial area. Using direct foam writing, 3D ceramic lattices composed of open-cell foam struts were fabricated with tailored mechanical properties and interconnected porosity across multiple length scales.

2.
Glob Health Action ; 13(1): 1715325, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32041498

RESUMEN

Less than 1% of biomedical research papers originate in Africa. Locally relevant mental health research, including synthesis of existing evidence, is essential for developing interventions and strengthening health systems, but institutions may lack the capacity to deliver training on systematic reviewing for publication in international journals. This paper describes the development and implementation of a training-of-trainers (ToT) course on systematic reviewing. The ToT prepared junior faculty ('trainers') from universities in Ethiopia, Malawi, and Zimbabwe to lead a five-day systematic reviewing workshop. Using an evaluation framework based on implementation science outcomes, the feasibility of the ToT was assessed by tracking the number of workshops the trainers subsequently conducted and the number of trainers and trainees who participated; acceptability was assessed through post-workshop surveys on trainee perspectives; impact was evaluated through trainee scores on a 15-item multiple choice test on systematic reviewing concepts; and sustainability was assessed based on whether the workshop was integrated into university curricula. Twelve trainers (86% of those trained) facilitated a total of seven workshops in their home countries (total 103 trainees). The first workshop run in each country was evaluated, and there was a significant improvement in mean knowledge scores between pre- and post-tests among trainees (MD= 3.07, t= 5.90, 95% CI 2.02-4.11). In two of the three countries, there are efforts to integrate the systematic review workshop into university curricula. The cost of the workshop led by the international trainer was $1480 per participant, whereas the trainer-led workshops cost approximately $240 per participant. Overall, ToT is relatively new to research capacity building, although it has been used widely in clinical settings. Our findings suggest ToT is a promising, low-cost way to develop both technical skills of individuals and the pedagogical capacity of universities, and to promote sustainability of research capacity building programs that often have time-limited grant funding.


Asunto(s)
Investigación Biomédica/educación , Investigación Biomédica/métodos , Creación de Capacidad , Educación Médica/organización & administración , Salud Mental/educación , Investigadores/educación , Revisiones Sistemáticas como Asunto , Adulto , Curriculum , Etiopía , Femenino , Humanos , Malaui , Masculino , Persona de Mediana Edad , Zimbabwe
3.
J Clin Epidemiol ; 122: 115-128.e1, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32105798

RESUMEN

OBJECTIVES: Depression symptom questionnaires are not for diagnostic classification. Patient Health Questionnaire-9 (PHQ-9) scores ≥10 are nonetheless often used to estimate depression prevalence. We compared PHQ-9 ≥10 prevalence to Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID) major depression prevalence and assessed whether an alternative PHQ-9 cutoff could more accurately estimate prevalence. STUDY DESIGN AND SETTING: Individual participant data meta-analysis of datasets comparing PHQ-9 scores to SCID major depression status. RESULTS: A total of 9,242 participants (1,389 SCID major depression cases) from 44 primary studies were included. Pooled PHQ-9 ≥10 prevalence was 24.6% (95% confidence interval [CI]: 20.8%, 28.9%); pooled SCID major depression prevalence was 12.1% (95% CI: 9.6%, 15.2%); and pooled difference was 11.9% (95% CI: 9.3%, 14.6%). The mean study-level PHQ-9 ≥10 to SCID-based prevalence ratio was 2.5 times. PHQ-9 ≥14 and the PHQ-9 diagnostic algorithm provided prevalence closest to SCID major depression prevalence, but study-level prevalence differed from SCID-based prevalence by an average absolute difference of 4.8% for PHQ-9 ≥14 (95% prediction interval: -13.6%, 14.5%) and 5.6% for the PHQ-9 diagnostic algorithm (95% prediction interval: -16.4%, 15.0%). CONCLUSION: PHQ-9 ≥10 substantially overestimates depression prevalence. There is too much heterogeneity to correct statistically in individual studies.

4.
Br J Nutr ; 121(2): 130-136, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30477593

RESUMEN

Non-communicable diseases are projected to become the most common causes of death in Africa by 2030. The impact on health of epidemiological and nutritional transitions in sub-Saharan Africa remains unclear. To assess the trends of dietary fatty acids over time in Uganda, we examined fatty acids in serum collected from individuals in rural south-west Uganda, at three time points over two decades. Independent cross-sectional samples of 915 adults and children were selected from the general population cohort in 1990 (n 281), 2000 (n 283) and 2008 (n 351). Serum phospholipid fatty acids were measured by GC. Multivariate regression analyses were performed to compare the geometric means of fatty acids by time period. Serum fatty acid profiling showed high proportions of SFA, cis-MUFA and industrial trans-fatty acids (iTFA), likely to be biomarkers of high consumption of palm oil and hydrogenated fats. In contrast, proportions of n-6 and n-3 PUFA from vegetable oils and fish were low. From 1990 to 2008, serum phospholipids showed increases in absolute amounts of SFA (17·3 % increase in adults and 26·4 % in children), MUFA (16·7 % increase in adults and 16·8 % in children) and n-6:n-3 PUFA (40·1 % increase in adults and 39·8 % in children). The amount of elaidic acid, iTFA from hydrogenated fats, increased in children (60·1 % increase). In this rural Ugandan population, we show evidence of unfavourable trends over time of dietary fatty acids.


Asunto(s)
Dieta/tendencias , Grasas de la Dieta/administración & dosificación , Ácidos Grasos/sangre , Población Rural , Adolescente , Adulto , Biomarcadores/sangre , Niño , Estudios Transversales , Ácidos Grasos/administración & dosificación , Ácidos Grasos Monoinsaturados/sangre , Ácidos Grasos Omega-3/administración & dosificación , Ácidos Grasos Omega-6/administración & dosificación , Femenino , Humanos , Masculino , Fenómenos Fisiológicos de la Nutrición , Ácidos Oléicos/sangre , Aceite de Palma/administración & dosificación , Fosfolípidos/sangre , Uganda
5.
BMC Womens Health ; 18(1): 4, 2018 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-29298699

RESUMEN

BACKGROUND: Management of menstruation can present substantial challenges to girls in low-income settings. In preparation for a menstrual hygiene intervention to reduce school absenteeism in Uganda, this study aimed to investigate menstruation management practices, barriers and facilitators, and the influence of menstruation on school absenteeism among secondary school students in a peri-urban district of Uganda. METHODS: Qualitative and quantitative studies were conducted among consenting girls and boys aged 14-17 years in four secondary schools in Entebbe sub-District, Uganda. Methods included group and in-depth interviews with students, a quantitative cross-sectional questionnaire, a prospectively self-completed menstrual diary, key informant interviews with policy makers, and observations of school water, sanitation and hygiene facilities. Multiple logistic regression was used to assess factors associated with school absenteeism during the most recent menstrual period. RESULTS: Girls reported substantial embarrassment and fear of teasing related to menstruation in the qualitative interviews, and said that this, together with menstrual pain and lack of effective materials for menstrual hygiene management, led to school absenteeism. All policy makers interviewed reported poverty and menstruation as the key factors associated with school attendance. The 352 girls with questionnaire data had a median age of 16 (inter-quartile range (IQR) = 15,16) years, with median age at menarche of 13 (IQR = 13,14) years. Of these, 64 girls (18.7%) reported having stained their clothes and 69 (19.7%) reported missing at least 1 day of school, during their most recent period. Missing school during the most recent period was associated with physical symptoms (headache (odds ratio (OR) = 2.15, 95%CI:1.20, 3.86), stomach pain (OR = 1.89, 95%CI:0.89, 4.04), back pain (OR = 1.75, 95%CI:0.97, 3.14), and with changing protection 4 or more times per 24 h period (OR = 2.08, 95%CI:1.06, 4.10). In the diary sub-study among 40 girls, school absence was reported on 28% of period-days, compared with 7% of non-period days (adjusted odds ratio = 5.99, 95%CI:4.4, 8.2; p < 0.001). CONCLUSION: In this peri-urban Ugandan population, menstruation was strongly associated with school attendance. Evaluation of a menstrual management intervention that address both psychosocial (e.g. self-confidence, attitudes) and physical (e.g. management of pain, use of adequate menstrual hygiene materials, improved water and sanitation facilities) aspects of menstruation are needed.


Asunto(s)
Absentismo , Conocimientos, Actitudes y Práctica en Salud , Menstruación/psicología , Estudiantes/psicología , Estudiantes/estadística & datos numéricos , Adolescente , Estudios Transversales , Dismenorrea/psicología , Desconcierto , Estudios de Factibilidad , Femenino , Productos para la Higiene Femenina/provisión & distribución , Humanos , Entrevistas como Asunto , Menarquia , Pobreza , Instituciones Académicas , Población Suburbana , Encuestas y Cuestionarios , Cuartos de Baño , Uganda
6.
PLoS One ; 12(10): e0185929, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29016651

RESUMEN

The Ugandan government is committed to scaling-up proven HIV prevention strategies including safe male circumcision, and innovative strategies are needed to increase circumcision uptake. The aim of this study was to assess the acceptability and feasibility of implementing a soccer-based intervention ("Make The Cut") among schoolboys in a peri-urban district of Uganda. The intervention was led by trained, recently circumcised "coaches" who facilitated a 60-minute session delivered in schools, including an interactive penalty shoot-out game using metaphors for HIV prevention, sharing of the coaches' circumcision story, group discussion and ongoing engagement from the coach to facilitate linkage to male circumcision. The study took place in four secondary schools in Entebbe sub-district, Uganda. Acceptability of safe male circumcision was assessed through a cross-sectional quantitative survey. The feasibility of implementing the intervention was assessed by piloting the intervention in one school, modifying it, and implementing the modified version in a second school. Perceptions of the intervention were assessed with in-depth interviews with participants. Of the 210 boys in the cross-sectional survey, 59% reported being circumcised. Findings showed high levels of knowledge and generally favourable perceptions of circumcision. The initial implementation of Make The Cut resulted in 6/58 uncircumcised boys (10.3%) becoming circumcised. Changes made included increasing engagement with parents and improved liaison with schools regarding the timing of the intervention. Following this, uptake improved to 18/69 (26.1%) in the second school. In-depth interviews highlighted the important role of family and peer support and the coach in facilitating the decision to circumcise. This study showed that the modified Make The Cut intervention may be effective to increase uptake of safe male circumcision in this population. However, the intervention is time-intensive, and further work is needed to assess the cost-effectiveness of the intervention conducted at scale.


Asunto(s)
Consumo de Bebidas Alcohólicas/epidemiología , Circuncisión Masculina , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Adolescente , VIH/patogenicidad , Infecciones por VIH/virología , Humanos , Masculino , Padres , Religión , Instituciones Académicas , Fútbol , Uganda , Adulto Joven
7.
Proc Natl Acad Sci U S A ; 114(8): 1832-1837, 2017 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-28179570

RESUMEN

Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (∼6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes.

8.
Bioinspir Biomim ; 12(2): 026014, 2017 03 17.
Artículo en Inglés | MEDLINE | ID: mdl-28192278

RESUMEN

Additive manufacturing technologies offer new ways to fabricate cellular materials with composite cell walls, mimicking the structure and mechanical properties of woods. However, materials limitations and a lack of design tools have confined the usefulness of 3D printed cellular materials. We develop new carbon fiber reinforced, epoxy inks for 3D printing which result in printed materials with longitudinal Young's modulus up to 57 GPa (exceeding the longitudinal modulus of wood cell wall material). To guide the design of hierarchical cellular materials, we developed a parameterized, multi-scale, finite element model. Computational homogenization based on finite element simulations at multiple length scales is employed to obtain the elastic properties of the material at multiple length scales. Parameters affecting the elastic response of cellular composites, such as the volume fraction, orientation distribution, and aspect ratio of fibers within the cell walls as well as the cell geometry and relative density are included in the model. To validate the model, experiments are conducted on both solid carbon fiber/epoxy composites and cellular structures made from them, showing excellent agreement with computational multi-scale model predictions, both at the cell-wall and at the cellular-structure levels. Using the model, cellular structures are designed and experimentally shown to achieve a specific stiffness nearly as high as that observed in balsa wood. The good agreement between the multi-scale model predictions and experimental data provides confidence in the practical utility of this model as a tool for designing novel 3D cellular composites with unprecedented specific elastic properties.


Asunto(s)
Materiales Biomiméticos , Bombacaceae/anatomía & histología , Bombacaceae/fisiología , Pared Celular , Compuestos Epoxi , Tinta , Impresión Tridimensional , Carbono , Módulo de Elasticidad , Elasticidad , Análisis de Elementos Finitos
9.
Plant Methods ; 13: 5, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28077951

RESUMEN

BACKGROUND: Biological materials have a complex, hierarchical structure, with vital structural features present at all size scales, from the nanoscale to the macroscale. A method that can connect information at multiple length scales has great potential to reveal novel information. This article presents one such method with an application to the bamboo culm wall. Moso (Phyllostachys edulis) bamboo is a commercially important bamboo species. At the cellular level, bamboo culm wall consists of vascular bundles embedded in a parenchyma cell tissue matrix. The microfibril angle (MFA) in the bamboo cell wall is related to its macroscopic longitudinal stiffness and strength and can be determined at the nanoscale with wide-angle X-ray scattering (WAXS). Combining WAXS with X-ray microtomography (XMT) allows tissue-specific study of the bamboo culm without invasive chemical treatment. RESULTS: The scattering contribution of the fiber and parenchyma cells were separated with spatially-localized WAXS. The fiber component was dominated by a high degree of orientation corresponding to small MFAs (mean MFA 11°). The parenchyma component showed significantly lower degree of orientation with a maximum at larger angles (mean MFA 65°). The fiber ratio, the volume of cell wall in the fibers relative to the overall volume of cell wall, was determined by fitting the scattering intensities with these two components. The fiber ratio was also determined from the XMT data and similar fiber ratios were obtained from the two methods, one connected to the cellular level and one to the nanoscale. X-ray diffraction tomography was also done to study the differences in microfibril orientation between fibers and the parenchyma and further connect the microscale to the nanoscale. CONCLUSIONS: The spatially-localized WAXS yields biologically relevant, tissue-specific information. With the custom-made bench-top set-up presented, diffraction contrast information can be obtained from plant tissue (1) from regions-of-interest, (2) as a function of distance (line scan), or (3) with two-dimensional or three-dimensional tomography. This nanoscale information is connected to the cellular level features.

10.
J Sex Res ; 54(1): 91-104, 2017 01.
Artículo en Inglés | MEDLINE | ID: mdl-26891245

RESUMEN

The timing of first sexual intercourse is often defined in terms of chronological age, with particular focus on "early" first sex. Arguments can be made for a more nuanced concept of readiness and appropriateness of timing of first intercourse. Using data from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), conducted in 2010-2012, this study examined whether a context-based measure of first intercourse-termed sexual competence-was associated with subsequent sexual health in a population-based sample of 17-to 24-year-olds residing in Britain (n = 2,784). Participants were classified as "sexually competent" at first intercourse if they reported the following four criteria: contraceptive protection, autonomy of decision (not due to external influences), that both partners were "equally willing," and that it happened at the "right time." A lack of sexual competence at first intercourse was independently associated with testing positive for human papillomavirus (HPV) at interview; low sexual function in the past year; and among women only, reported sexually transmitted infection (STI) diagnosis ever; unplanned pregnancy in the past year; and having ever experienced nonvolitional sex. These findings provide empirical support for defining the nature of first intercourse with reference to contextual aspects of the experience, as opposed to a sole focus on chronological age at occurrence.


Asunto(s)
Conocimientos, Actitudes y Práctica en Salud , Heterosexualidad/estadística & datos numéricos , Salud Reproductiva/estadística & datos numéricos , Conducta Sexual/estadística & datos numéricos , Adolescente , Adulto , Femenino , Humanos , Masculino , Conducta Sexual/psicología , Reino Unido , Adulto Joven
11.
Lancet ; 388(10044): 586-95, 2016 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-27229190

RESUMEN

BACKGROUND: In 2000, a 10-year Teenage Pregnancy Strategy was launched in England to reduce conceptions in women younger than 18 years and social exclusion in young parents. We used routinely collected data and data from Britain's National Surveys of Sexual Attitudes and Lifestyles (Natsal) to examine progress towards these goals. METHODS: In this observational study, we used random-effects meta-regression to analyse the change in conception rates from 1994-98 to 2009-13 by top-tier local authorities in England, in relation to Teenage Pregnancy Strategy-related expenditure per head, socioeconomic deprivation, and region. Data from similar probability sample surveys: Natsal-1 (1990-91), Natsal-2 (1999-2001), and Natsal-3 (2010-12) were used to assess the prevalence of risk factors and their association with conception in women younger than 18 years in women aged 18-24 years; and the prevalence of participation in education, work, and training in young mothers. FINDINGS: Conception rates in women younger than 18 years declined steadily from their peak in 1996-98 and more rapidly from 2007 onwards. More deprived areas and those receiving greater Teenage Pregnancy Strategy-related investment had higher rates of conception in 1994-98 and had greater declines to 2009-13. Regression analyses assessing the association between Teenage Pregnancy Strategy funding and decline in conception rates in women younger than 18 years showed an estimated reduction in the conception rate of 11.4 conceptions (95% CI 9.6-13.2; p<0.0001) per 1000 women aged 15-17 years for every £100 Teenage Pregnancy Strategy spend per head and a reduction of 8.2 conceptions (5.8-10.5; p<0.0001) after adjustment for socioeconomic deprivation and region. The association between conception in women younger than 18 years and lower socioeconomic status weakened slightly between Natsal-2 and Natsal-3. The prevalence of participation in education, work, or training among young women with a child conceived before age 18 years was low, but the odds of them doing so doubled between Natsal-2 and Natsal-3 (odds ratio 1.99, 95% CI 0.99-4.00). INTERPRETATION: A sustained, multifaceted policy intervention involving health and education agencies, alongside other social and educational changes, has probably contributed to a substantial and accelerating decline in conceptions in women younger than 18 years in England since the late 1990s. FUNDING: Medical Research Council, Wellcome Trust, Economic and Social Research Council, and Department of Health.


Asunto(s)
Madres/estadística & datos numéricos , Índice de Embarazo/tendencias , Embarazo en Adolescencia/estadística & datos numéricos , Adolescente , Inglaterra , Femenino , Encuestas Epidemiológicas , Humanos , Estilo de Vida , Embarazo , Prevalencia , Análisis de Regresión , Conducta Sexual/estadística & datos numéricos
12.
J Affect Disord ; 198: 50-5, 2016 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-27011359

RESUMEN

BACKGROUND: In low income countries in Sub-Saharan Africa there are few validated tools to screen for common disabling mental disorders such as depression and general anxiety disorder (GAD). OBJECTIVES: We validated three screening tools: the Shona Symptom Questionnaire for common mental disorders (SSQ-14), the Patient Health Questionnaire for depression (PHQ-9), and the Generalized Anxiety Disorder questionnaire (GAD-7). The study participants were attendees at a primary health care clinic in Harare, Zimbabwe. METHODS: Consecutive adults aged 18 and above attending the clinic were enrolled over a two-week period in September 2013. Trained research assistants administered the screening tools to eligible participants after obtaining written consent. Participants were then interviewed by one of four psychiatrists using the Structured Clinical Interview of the DSM-IV (SCID). Performance characteristics were calculated for each tool, against the SCID as the gold standard. RESULTS: A total of 264 participants were enrolled, of whom 52 (20%) met the SCID criteria for depression alone, 97 (37%) for mixed depression and anxiety and 9 (3%) for anxiety alone. Of the 237 where HIV status was known, 165 (70%) were HIV positive. With the optimal cutoff of ≥9, the sensitivity and specificity for the SSQ-14 against a diagnosis of either depression and/or general anxiety were 84% (95%CI:78-89%) and 73% (95%CI:63-81%) respectively. Internal reliability was high (Cronbach α=0.74). The optimal cutoff for PHQ-9 was ≥11, which provided a sensitivity of 85% (95%CI:78-90%) and specificity of 69% (95%CI:59-77%) against a SCID diagnosis of depression (Cronbach α=0.86). The GAD-7 (optimal cutoff ≥10) had sensitivity and specificity of 89% (95%CI:81-94%) and 73% (95%CI:65-80%) respectively against a SCID diagnosis of GAD (Cronbach α=0.87). CONCLUSION: Screening tools for depression and GAD had good performance characteristics in a primary health care population in Zimbabwe with a high prevalence of HIV. These can be used for research and also in clinical care to screen patients who may benefit from treatment.


Asunto(s)
Trastornos de Ansiedad/diagnóstico , Depresión/diagnóstico , Infecciones por VIH/epidemiología , Pobreza/estadística & datos numéricos , Atención Primaria de Salud , Escalas de Valoración Psiquiátrica/estadística & datos numéricos , Adolescente , Adulto , Trastornos de Ansiedad/complicaciones , Trastornos de Ansiedad/epidemiología , Depresión/complicaciones , Depresión/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Prevalencia , Psicometría , Reproducibilidad de los Resultados , Adulto Joven , Zimbabwe/epidemiología
13.
J Insect Physiol ; 74: 10-5, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25660065

RESUMEN

Many insect wings change shape dynamically during the wingbeat cycle, and these deformations have the potential to confer energetic and aerodynamic benefits during flight. Due to the lack of musculature within the wing itself, the changing form of the wing is determined primarily by its passive response to inertial and aerodynamic forces. This response is in part controlled by the wing's mechanical properties, which vary across the membrane to produce regions of differing stiffness. Previous studies of wing mechanical properties have largely focused on surface or bulk measurements, but this ignores the layered nature of the wing. In our work, we investigated the mechanical properties of the wings of the house cricket (Acheta domesticus) with the aim of determining differences between layers within the wing. Nanoindentation was performed on both the surface and the interior layers of cross-sectioned samples of the wing to measure the Young's modulus and hardness of the outer- and innermost layers. The results demonstrate that the interior of the wing is stiffer than the surface, and both properties vary across the wing.


Asunto(s)
Gryllidae/ultraestructura , Alas de Animales/ultraestructura , Animales , Fenómenos Biomecánicos , Vuelo Animal , Microscopía Electrónica de Rastreo
14.
Environ Health Perspect ; 122(2): 187-92, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24280536

RESUMEN

BACKGROUND: The presence of perfluoroalkyl acids (PFAAs) in breast milk has been documented, but their lactational transfer has been rarely studied. Determination of the elimination rates of these chemicals during breastfeeding is important and critical for assessing exposure in mothers and infants. OBJECTIVES: We aimed to investigate the association between breastfeeding and maternal serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonate (PFHxS). For a subset of the population, for whom we also have their infants' measurements, we investigated associations of breastfeeding with infant serum PFAA concentrations. METHODS: The present analysis included 633 women from the C8 Science Panel Study who had a child < 3.5 years of age and who provided blood samples and reported detailed information on breastfeeding at the time of survey. PFAA serum concentrations were available for all mothers and 8% (n = 49) of the infants. Maternal and infant serum concentrations were regressed on duration of breastfeeding. RESULTS: Each month of breastfeeding was associated with lower maternal serum concentrations of PFOA (-3%; 95% CI: -5, -2%), PFOS (-3%; 95% CI: -3, -2%), PFNA (-2%; 95% CI: -2, -1%), and PFHxS (-1%; 95% CI: -2, 0%). The infant PFOA and PFOS serum concentrations were 6% (95% CI: 1, 10%) and 4% (95% CI: 1, 7%) higher per month of breastfeeding. CONCLUSIONS: Breast milk is the optimal food for infants, but is also a PFAA excretion route for lactating mothers and exposure route for nursing infants.


Asunto(s)
Lactancia Materna/efectos adversos , Contaminantes Ambientales/análisis , Leche Humana/química , Factores de Edad , Ácidos Alcanesulfónicos/análisis , Ácidos Alcanesulfónicos/sangre , Caprilatos/análisis , Caprilatos/sangre , Contaminantes Ambientales/sangre , Femenino , Fluorocarburos/análisis , Fluorocarburos/sangre , Humanos , Londres , Ácidos Sulfónicos/análisis , Ácidos Sulfónicos/sangre , Encuestas y Cuestionarios
15.
Lancet ; 382(9907): 1807-16, 2013 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-24286786

RESUMEN

BACKGROUND: Unplanned pregnancy is a key public health indicator. We describe the prevalence of unplanned pregnancy, and associated factors, in a general population sample in Britain (England, Scotland, and Wales). METHOD: We did a probability sample survey, the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), of 15,162 men and women aged 16-74 years in Britain, including 5686 women of child-bearing age (16-44 years) who were included in the pregnancy analysis, between Sept 6, 2010, and Aug 31, 2012. We describe the planning status of pregnancies with known outcomes in the past year, and report the annual population prevalence of unplanned pregnancy, using a validated, multicriteria, multi-outcome measure (the London Measure of Unplanned Pregnancy). We set the findings in the context of secular trends in reproductive health-related events, and patterns across the life course. FINDINGS: 9·7% of women aged 16-44 years had pregnancies with known outcome in the year before interview, of which 16·2% (95% CI 13·1-19·9) scored as unplanned, 29·0% (25·2-33·2) as ambivalent, and 54·8% (50·3-59·2) as planned, giving an annual prevalence estimate for unplanned pregnancy of 1·5% (1·2-1·9). Pregnancies in women aged 16-19 years were most commonly unplanned (45·2% [30·8-60·5]). However, most unplanned pregnancies were in women aged 20-34 years (62·4% [50·2-73·2]). Factors strongly associated with unplanned pregnancy were first sexual intercourse before 16 years of age (age-adjusted odds ratio 2·85 [95% CI 1·77-4·57], current smoking (2·47 [1·46-4·18]), recent use of drugs other than cannabis (3·41 [1·64-7·11]), and lower educational attainment. Unplanned pregnancy was also associated with lack of sexual competence at first sexual intercourse (1·90 [1·14-3·08]), reporting higher frequency of sex (2·11 [1·25-3·57] for five or more times in the past 4 weeks), receiving sex education mainly from a non-school-based source (1·84 [1·12-3·00]), and current depression (1·96 [1·10-3·47]). INTERPRETATION: The increasing intervals between first sexual intercourse, cohabitation, and childbearing means that, on average, women in Britain spend about 30 years of their life needing to avert an unplanned pregnancy. Our data offer scope for primary prevention aimed at reducing the rate of unplanned conceptions, and secondary prevention aimed at modification of health behaviours and health disorders in unplanned pregnancy that might be harmful for mother and child. FUNDING: Grants from the UK Medical Research Council and the Wellcome Trust, with support from the Economic and Social Research Council and the Department of Health.


Asunto(s)
Encuestas Epidemiológicas , Embarazo no Planeado , Adolescente , Adulto , Femenino , Humanos , Entrevistas como Asunto , Embarazo , Resultado del Embarazo , Prevalencia , Factores de Riesgo , Reino Unido/epidemiología
16.
Lancet ; 382(9907): 1845-55, 2013 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-24286789

RESUMEN

BACKGROUND: Sexual violence is increasingly recognised as a public health issue. Information about prevalence, associated factors, and consequences for health in the population of Britain (England, Scotland, and Wales) is scarce. The third National Survey of Sexual Health Attitudes and Lifestyles (Natsal-3) is the first of the Natsal surveys to include questions about sexual violence and the first population-based survey in Britain to explore the issue outside the context of crime. METHODS: Between Sept 6, 2010, and Aug 31, 2012, we did a probability sample survey of women and men aged 16-74 years living in Britain. We asked participants about their experience of sex against their will since age 13 years and the circumstances surrounding the most recent occurrence. We explored associations between ever experiencing non-volitional sex and a range of sociodemographic, health, and behavioural factors. We used logistic regression to estimate age-adjusted odds ratios to analyse factors associated with the occurrence of completed non-volitional sex in women and men. FINDINGS: We interviewed 15,162 people. Completed non-volitional sex was reported by 9·8% (95% CI 9·0-10·5) of women and 1·4% (1·1-1·7) of men. Median age (interdecile range) at most recent occurrence was 18 years (14-32) for women and 16 years (13-30) for men. Completed non-volitional sex varied by family structure and, in women, by age, education, and area-level deprivation. It was associated with poor health, longstanding illness or disability, and treatment for mental health conditions, smoking, and use of non-prescription drugs in the past year in both sexes, and with binge drinking in women. Completed non-volitional sex was also associated with reporting of first heterosexual intercourse before 16 years of age, same-sex experience, more lifetime sexual partners, ever being diagnosed with a sexually transmitted infection, and low sexual function in both sexes, and, in women, with abortion and pregnancy outcome before 18 years of age. In most cases, the person responsible was known to the individual, although the nature of the relationship differed by age at most recent occurrence. Participants who were younger at interview were more likely to have told someone about the event and to have reported it to the police than were older participants. INTERPRETATION: These data provide the first population prevalence estimates of non-volitional sex in Britain. We showed it to be mainly an experience of young age and strongly associated with a range of adverse health outcomes in both women and men. FUNDING: Grants from the UK Medical Research Council and the Wellcome Trust, with support from the Economic and Social Research Council and the Department of Health.


Asunto(s)
Encuestas Epidemiológicas , Delitos Sexuales/estadística & datos numéricos , Conducta Sexual , Adolescente , Adulto , Factores de Edad , Anciano , Femenino , Humanos , Entrevistas como Asunto , Masculino , Persona de Mediana Edad , Prevalencia , Factores de Riesgo , Enfermedades de Transmisión Sexual/epidemiología , Reino Unido/epidemiología
17.
J R Soc Interface ; 9(76): 2749-66, 2012 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-22874093

RESUMEN

The cell walls in plants are made up of just four basic building blocks: cellulose (the main structural fibre of the plant kingdom) hemicellulose, lignin and pectin. Although the microstructure of plant cell walls varies in different types of plants, broadly speaking, cellulose fibres reinforce a matrix of hemicellulose and either pectin or lignin. The cellular structure of plants varies too, from the largely honeycomb-like cells of wood to the closed-cell, liquid-filled foam-like parenchyma cells of apples and potatoes and to composites of these two cellular structures, as in arborescent palm stems. The arrangement of the four basic building blocks in plant cell walls and the variations in cellular structure give rise to a remarkably wide range of mechanical properties: Young's modulus varies from 0.3 MPa in parenchyma to 30 GPa in the densest palm, while the compressive strength varies from 0.3 MPa in parenchyma to over 300 MPa in dense palm. The moduli and compressive strength of plant materials span this entire range. This study reviews the composition and microstructure of the cell wall as well as the cellular structure in three plant materials (wood, parenchyma and arborescent palm stems) to explain the wide range in mechanical properties in plants as well as their remarkable mechanical efficiency.


Asunto(s)
Arecaceae/anatomía & histología , Pared Celular/química , Celulosa/análisis , Lignina/análisis , Pectinas/análisis , Células Vegetales/química , Tallos de la Planta/citología , Polisacáridos/análisis , Madera/análisis , Arecaceae/citología , Fenómenos Biomecánicos , Pared Celular/ultraestructura , Fuerza Compresiva , Frutas/citología , Raíces de Plantas/citología
18.
J Natl Cancer Inst ; 104(9): 657-69, 2012 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-22472546

RESUMEN

BACKGROUND: Epidemiological studies have provided strong evidence for a role of endogenous sex steroids in the etiology of breast cancer. Our aim was to identify common variants in genes involved in sex steroid synthesis or metabolism that are associated with hormone levels and the risk of breast cancer in premenopausal women. METHODS: We measured urinary levels of estrone glucuronide (E1G) using a protocol specifically developed to account for cyclic variation in hormone levels during the menstrual cycle in 729 healthy premenopausal women. We genotyped 642 single-nucleotide polymorphisms (SNPs) in these women; a single SNP, rs10273424, was further tested for association with the risk of breast cancer using data from 10 551 breast cancer case patients and 17 535 control subjects. All statistical tests were two-sided. RESULTS: rs10273424, which maps approximately 50 kb centromeric to the cytochrome P450 3A (CYP3A) gene cluster at chromosome 7q22.1, was associated with a 21.8% reduction in E1G levels (95% confidence interval [CI] = 27.8% to 15.3% reduction; P = 2.7 × 10(-9)) and a modest reduction in the risk of breast cancer in case patients who were diagnosed at or before age 50 years (odds ratio [OR] = 0.91, 95% CI = 0.83 to 0.99; P = .03) but not in those diagnosed after age 50 years (OR = 1.01, 95% CI = 0.93 to 1.10; P = .82). CONCLUSIONS: Genetic variation in noncoding sequences flanking the CYP3A locus contributes to variance in premenopausal E1G levels and is associated with the risk of breast cancer in younger patients. This association may have wider implications given that the most predominantly expressed CYP3A gene, CYP3A4, is responsible for metabolism of endogenous and exogenous hormones and hormonal agents used in the treatment of breast cancer.


Asunto(s)
Neoplasias de la Mama/enzimología , Neoplasias de la Mama/genética , Citocromo P-450 CYP3A/genética , Estrona/orina , Glucurónidos/orina , Mamografía , Polimorfismo de Nucleótido Simple , Premenopausia , Globulina de Unión a Hormona Sexual/genética , Adulto , Factores de Edad , Andrógenos/sangre , Neoplasias de la Mama/sangre , Neoplasias de la Mama/diagnóstico por imagen , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/orina , Estudios de Casos y Controles , Estudios Transversales , Citocromo P-450 CYP3A/metabolismo , Grupo de Ascendencia Continental Europea/genética , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Estilo de Vida , Desequilibrio de Ligamiento , Ciclo Menstrual/orina , Oportunidad Relativa , Valor Predictivo de las Pruebas , Pregnanodiol/orina , Historia Reproductiva , Medición de Riesgo , Factores de Riesgo , Globulina de Unión a Hormona Sexual/metabolismo , Reino Unido/epidemiología
19.
J Natl Cancer Inst ; 103(5): 425-35, 2011 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-21263130

RESUMEN

BACKGROUND: Genome-wide association studies have identified several common genetic variants associated with breast cancer risk. It is likely, however, that a substantial proportion of such loci have not yet been discovered. METHODS: We compared 296,114 tagging single-nucleotide polymorphisms in 1694 breast cancer case subjects (92% with two primary cancers or at least two affected first-degree relatives) and 2365 control subjects, with validation in three independent series totaling 11,880 case subjects and 12,487 control subjects. Odds ratios (ORs) and associated 95% confidence intervals (CIs) in each stage and all stages combined were calculated using unconditional logistic regression. Heterogeneity was evaluated with Cochran Q and I(2) statistics. All statistical tests were two-sided. RESULTS: We identified a novel risk locus for breast cancer at 9q31.2 (rs865686: OR = 0.89, 95% CI = 0.85 to 0.92, P = 1.75 × 10(-10)). This single-nucleotide polymorphism maps to a gene desert, the nearest genes being Kruppel-like factor 4 (KLF4, 636 kb centromeric), RAD23 homolog B (RAD23B, 794 kb centromeric), and actin-like 7A (ACTL7A, 736 kb telomeric). We also identified two variants (rs3734805 and rs9383938) mapping to 6q25.1 estrogen receptor 1 (ESR1), which were associated with breast cancer in subjects of northern European ancestry (rs3734805: OR = 1.19, 95% CI = 1.11 to 1.27, P = 1.35 × 10(-7); rs9383938: OR = 1.18, 95% CI = 1.11 to 1.26, P = 1.41 × 10(-7)). A variant mapping to 10q26.13, approximately 300 kb telomeric to the established risk locus within the second intron of FGFR2, was also associated with breast cancer risk, although not at genome-wide statistical significance (rs10510102: OR = 1.12, 95% CI = 1.07 to 1.17, P = 1.58 × 10(-6)). CONCLUSIONS: These findings provide further evidence on the role of genetic variation in the etiology of breast cancer. Fine mapping will be needed to identify causal variants and to determine their functional effects.


Asunto(s)
Neoplasias de la Mama/genética , Cromosomas Humanos Par 9 , Grupo de Ascendencia Continental Europea/genética , Polimorfismo de Nucleótido Simple , Actinas/genética , Adulto , Anciano , Neoplasias de la Mama/etnología , Estudios de Casos y Controles , Cromosomas Humanos Par 10 , Cromosomas Humanos Par 6 , Enzimas Reparadoras del ADN/genética , Proteínas de Unión al ADN/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Genotipo , Humanos , Factores de Transcripción de Tipo Kruppel/genética , Desequilibrio de Ligamiento , Modelos Logísticos , Persona de Mediana Edad , Oportunidad Relativa , Control de Calidad , Factores de Riesgo , Encuestas y Cuestionarios , Reino Unido
20.
Biomaterials ; 31(18): 4835-45, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20362329

RESUMEN

The contractile behavior of cells is relevant in understanding wound healing and scar formation. In tissue engineering, inhibition of the cell contractile response is critical for the regeneration of physiologically normal tissue rather than scar tissue. Previous studies have measured the contractile response of cells in a variety of conditions (e.g. on two-dimensional solid substrates, on free-floating tissue engineering scaffolds and on scaffolds under some constraint in a cell force monitor). Tissue engineering scaffolds behave mechanically like open-cell elastomeric foams: between strains of about 10 and 90%, cells progressively buckle struts in the scaffold. The contractile force required for an individual cell to buckle a strut within a scaffold has been estimated based on the strut dimensions (radius, r, and length, l) and the strut modulus, E(s). Since the buckling force varies, according to Euler's law, with r(4)/l(2), and the relative density of the scaffold varies as (r/l)(2), the cell contractile force associated with strut buckling is expected to vary with the square of the pore size for scaffolds of constant relative density. As the cell density increases, the force per cell to achieve a given strain in the scaffold is expected to decrease. Here we model the contractile response of fibroblasts by analyzing the response of a single tetrakaidecahedron to forces applied to individual struts (simulating cell contractile forces) using finite element analysis. We model tetrakaidecahedra of different strut lengths, corresponding to different scaffold pore sizes, and of varying numbers of loaded struts, corresponding to varying cell densities. We compare our numerical model with the results of free-floating contraction experiments of normal human dermal fibroblasts (NHDF) in collagen-GAG scaffolds of varying pore size and with varying cell densities.


Asunto(s)
Colágeno/química , Fibroblastos/citología , Andamios del Tejido/química , Recuento de Células , Proliferación Celular , Supervivencia Celular , Dermis/citología , Humanos , Modelos Biológicos , Porosidad , Ingeniería de Tejidos
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