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Vitamin A deficiency is highly prevalent and remains the major cause of nutritional blindness in children in low-and middle-income countries, despite supplementation programmes. Xeropthalmia (severe drying and thickening of the conjunctiva) is caused by vitamin A deficiency and leads to irreversible blindness. Vitamin A supplementation programmes effectively reduce vitamin A deficiency but many rural children are not reached. Home food production may help prevent rural children's vitamin A deficiency. We aimed to systematically review trials assessing effects of home food production (also called homestead food production and agricultural interventions) on xeropthalmia, nightblindness, stunting, wasting, underweight and mortality (primary outcomes). We searched Medline, Embase, Scopus, Cochrane CENTRAL and trials registers to February 2019. Inclusion of studies, data extraction and risk of bias were assessed independently in duplicate. Random-effects meta-analysis, sensitivity analyses, subgrouping and GRADE were used. We included 16 trials randomizing 2498 children, none reported xerophthalmia, night-blindness or mortality. Home food production may slightly reduce stunting (mean difference (MD) 0.13 (z-score), 95% CI 0.01 to 0.24), wasting (MD 0.05 (z-score), 95% CI -0.04 to 0.14) and underweight (MD 0.07 (z-score), 95% CI -0.01 to 0.15) in young children (all GRADE low-consistency evidence), and increase dietary diversity (standardized mean difference (SMD) 0.24, 95% CI 0.15 to 0.34). Home food production may usefully complement vitamin A supplementation for rural children. Large, long-duration trials with good randomization, allocation concealment and correct adjustment for clustering are needed to assess effectiveness of home food production on nutritional blindness in young children.
Asunto(s)
Delgadez , Deficiencia de Vitamina A , Ceguera , Niño , Preescolar , Suplementos Dietéticos , Trastornos del Crecimiento/prevención & control , Humanos , Lactante , Ensayos Clínicos Controlados Aleatorios como Asunto , Deficiencia de Vitamina A/epidemiologíaRESUMEN
INTRODUCTION: Social comparisons strongly influence an individual's concept of self, their aspirations and decisions. This study investigates how non-traditional applicants used social comparison to shape their preferences, beliefs and predictions whilst preparing an application for medical school. METHODS: Semi-structured interviews were conducted with 12 UK medical students from non-traditional backgrounds to explore their process of 'getting ready' for medical school, and the role social comparison played in their experiences. Thematic analysis was used to inductively develop themes in the data, before findings were interpreted through the 'triadic model' of social comparison. RESULTS: Findings revealed that participants looked to the opinions of those with similar norms and backgrounds to accept their desire to study medicine. They sought the opinions of 'experts' to affirm a belief in their suitability but lacked confidence until success in crucial examinations 'proved', in their own view, that they had the ability to do medicine. Social comparison to peers who were perceived to be less committed to medicine, and to relatable role models, reassured participants that someone from their background could succeed in medicine. DISCUSSION: Our findings further understanding about 'how' and 'why' exposure to relevant experts, peers and role models can positively influence application to medicine through the lens of social comparison. We recommend widening access initiatives promote and foster various opportunities for social comparison to help counter non-traditional students' feelings of uncertainty about their ability and prospects, and to reorient their focus away from achieving the required grades before preparing the non-academic aspects of their application.
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Comparación Social , Estudiantes de Medicina/psicología , Selección de Profesión , Educación de Pregrado en Medicina/métodos , Humanos , Facultades de Medicina/organización & administración , Factores SocioeconómicosRESUMEN
Predator avoidance is fundamental for survival and it can be particularly challenging for prey animals if physical movement away from a predatory threat is restricted. Many sharks and rays begin life within an egg capsule that is attached to the sea bed. The vulnerability of this sedentary life stage is exacerbated in skates (Rajidae) as the compulsory ventilatory activity of embryos makes them conspicuous to potential predators. Embryos can reduce this risk by mediating ventilatory activity if they detect the presence of a predator using an acute electrosense. To determine how early in embryonic life predator elicited behavioral responses can occur, the reactions of three different age groups (1/3 developed, 2/3 developed, and near hatching) of embryonic thornback rays Raja clavata were tested using predator-type electric field stimuli. Egg capsules were exposed to continuous or intermittent stimuli in order to assess varying predator-type encounter scenarios on the ventilatory behavior of different developmental stages. All embryos reacted with a "freeze response" following initial electric field (E-field) exposure, ceasing ventilatory behavior in response to predator presence, demonstrating electroreceptive functionality for the first time at the earliest possible stage in ontogeny. This ability coincided with the onset of egg ventilatory behavior and may represent an effective means to enhance survival. A continuous application of stimuli over time revealed that embryos can adapt their behavior and resume normal activity, whereas when presented intermittently, the E-field resulted in a significant reduction in overall ventilatory activity across all ages. Recovery from stimuli was significantly quicker in older embryos, potentially indicative of the trade-off between avoiding predation and adequate respiration. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 721-729, 2016.
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Conducta Animal/fisiología , Fenómenos Electromagnéticos , Embrión no Mamífero/fisiología , Cadena Alimentaria , Sensación/fisiología , Rajidae/fisiología , Factores de Edad , Animales , Conducta Predatoria , Fenómenos Fisiológicos RespiratoriosRESUMEN
Halogen-labelled peptide organic acid (HPOA) monomers have been synthesised and incorporated into sequence-specific peptide nucleic acid (PNA) probes. Three different types of probe have been prepared; the unmodified PNA probe, the PNA probe with a mass marker, and the PNA probe with photocleavable mass marker. All three types of probe have been used in model studies to develop a mass spectrometry-based hybridisation assay for detection of point mutations in DNA.
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We describe a multi-platform ((1)H NMR, LC-MS, microarray) investigation of metabolic disturbances associated with the leptin receptor defective (db/db) mouse model of type 2 diabetes using novel assignment methodologies. For the first time, several urinary metabolites were found to be associated with diabetes and/or diabetes progression and confirmed in both NMR and LC-MS datasets. The confirmed metabolites were trimethylamine-n-oxide (TMAO), creatine, carnitine, and phenylalanine. TMAO and phenylalanine were both elevated in db/db mice and decreased in these mice with age. Levels of both creatine and carnitine increase in diabetic mice with age and creatine was also significantly decreased in db/db mice. Additionally, many metabolic markers were found by either NMR or LC-MS, but could not be found in both, due to instrumental limitations. This indicates that the combined use of NMR and LC-MS instrumentation provides complementary information that would be otherwise unattainable. Pathway analyses of urinary metabolites and liver, muscle, and adipose tissue transcripts from the db/db model were also performed to identify altered biochemical processes in the diabetic mice. Metabolite and liver transcript levels associated with the TCA cycle and steroid processes were altered in db/db mice. In addition, gene expression in muscle and liver associated with fatty acid processing was altered in the diabetic mice and similar evidence was observed in the LC-MS data. Our findings highlight the importance of a number of processes known to be associated with diabetes and reveal tissue specific responses to the condition. When studying metabolic disorders such as diabetes, multiple platform integrated profiling of metabolite alterations in biofluids can provide important insights into the processes underlying the disease.
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Diabetes Mellitus Tipo 2/metabolismo , Modelos Animales de Enfermedad , Metaboloma , Receptores de Leptina/deficiencia , Animales , Diabetes Mellitus Tipo 2/genética , Espectroscopía de Resonancia Magnética , Masculino , Espectrometría de Masas , Ratones , Receptores de Leptina/genéticaRESUMEN
The use of nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS) as complementary analytical techniques for open metabolic profiling is illustrated in the context of defining urinary biochemical discriminators between male and female Sprague-Dawley rats. Subsequent to the discovery of a female-specific urinary discriminator by LC-MS, further LC, MS, and NMR methods have been applied in a coordinated effort to identify this urinary component. Thereafter, the biological relevance and context of the identified component, in this case a steroid metabolite, has been achieved. This approach will be deployed in future studies of disease, drug efficacy, and toxicity to discover and identify biologically relevant markers.