Global response of Plasmodium falciparum to hyperoxia: a combined transcriptomic and proteomic approach

<p>Abstract</p> <p>Background</p> <p>Over its life cycle, the <it>Plasmodium falciparum </it>parasite is exposed to different environmental conditions, particularly to variations in O₂pressure. For example, the parasite circulates in human venous blood at 5% O₂pressure and in arterial blood, particularly in the lungs, at 13% O₂pressure. Moreover, the parasite is exposed to 21% O₂levels in the salivary glands of mosquitoes.</p> <p>Methods</p> <p>To study the metabolic adaptation of <it>P. falciparum </it>to different oxygen pressures during the intraerythrocytic cycle, a combined approach using transcriptomic and proteomic techniques was undertaken.</p> <p>Results</p> <p>Even though hyperoxia lengthens the parasitic cycle, significant transcriptional changes were detected in hyperoxic conditions in the late-ring stage. Using PS 6.0™ software (Ariadne Genomics) for microarray analysis, this study demonstrate up-expression of genes involved in antioxidant systems and down-expression of genes involved in the digestive vacuole metabolism and the glycolysis in favour of mitochondrial respiration. Proteomic analysis revealed increased levels of heat shock proteins, and decreased levels of glycolytic enzymes. Some of this regulation reflected post-transcriptional modifications during the hyperoxia response.</p> <p>Conclusions</p> <p>These results seem to indicate that hyperoxia activates antioxidant defence systems in parasites to preserve the integrity of its cellular structures. Moreover, environmental constraints seem to induce an energetic metabolism adaptation of <it>P. falciparum</it>. This study provides a better understanding of the adaptive capabilities of <it>P. falciparum </it>to environmental changes and may lead to the development of novel therapeutic targets.</p

The Nigerian national blindness and visual impairment survey: Rationale, objectives and detailed methodology.

BACKGROUND: Despite having the largest population in Africa, Nigeria has no accurate population based data to plan and evaluate eye care services. A national survey was undertaken to estimate the prevalence and determine the major causes of blindness and low vision. This paper presents the detailed methodology used during the survey. METHODS: A nationally representative sample of persons aged 40 years and above was selected. Children aged 10-15 years and individuals aged <10 or 16-39 years with visual impairment were also included if they lived in households with an eligible adult. All participants had their height, weight, and blood pressure measured followed by assessment of presenting visual acuity, refractokeratomery, A-scan ultrasonography, visual fields and best corrected visual acuity. Anterior and posterior segments of each eye were examined with a torch and direct ophthalmoscope. Participants with visual acuity of < = 6/12 in one or both eyes underwent detailed examination including applanation tonometry, dilated slit lamp biomicroscopy, lens grading and fundus photography. All those who had undergone cataract surgery were refracted and best corrected vision recorded. Causes of visual impairment by eye and for the individual were determined using a clinical algorithm recommended by the World Health Organization. In addition, 1 in 7 adults also underwent a complete work up as described for those with vision < = 6/12 for constructing a normative data base for Nigerians. DISCUSSION: The field work for the study was completed in 30 months over the period 2005-2007 and covered 305 clusters across the entire country. Concurrently persons 40+ years were examined to form a normative data base. Analysis of the data is currently underway. CONCLUSION: The methodology used was robust and adequate to provide estimates on the prevalence and causes of blindness in Nigeria. The survey would also provide information on barriers to accessing services, quality of life of visually impaired individuals and also provide normative data for Nigerian eyes

Visual impairment and blindness: an overview of prevalence and causes in Brazil

Our purpose is to provide a summary overview of blindness and visual impairment on the context of recent Brazilian ocular epidemiologic studies. Synthesis of data from two cross-sectional population-based studies - the São Paulo Eye Study and the Refractive Error in School Children Study is presented. 3678 older adults and 2441 school children were examined between July 2004 and December 2005. Prevalence of blindness in older adults using presenting visual acuity was 1.51% decreasing to 1. 07% with refractive correction. The most common causes of blindness in older adults were retinal disorders, followed by cataract and glaucoma. In school children, the prevalence of uncorrected visual impairment was 4.82% decreasing to 0.41% with refractive correction. The most common cause of visual impairment in school children was uncorrected refractive error. Visual impairment and blindness in Brazil is an important public health problem. It is a significant problem in older Brazilians, reinforcing the need to implement prevention of blindness programs for elderly people with emphasis on those without schooling. In school-children cost-effective strategies are needed to address a readily treatable cause of vision impairment - prescription and provision of glasses.<br>Nosso objetivo é fazer uma revisão de cegueira e deficiência visual no contexto de recentes estudos epidemiológicos oculares brasileiros. É apresentada a síntese dos dados de dois estudos populacionais transversais - o Estudo Ocular de São Paulo e o Estudo de Erros Refrativos em Escolares. Entre julho de 2004 e dezembro de 2005 foram examinados 3678 adultos e 2441 escolares. A prevalência de cegueira em adultos mais velhos considerando a acuidade visual apresentada foi de 1, 51% diminuindo para 1, 07% com a correção refrativa. As causas mais comuns de cegueira em adultos mais velhos foram os distúrbios de retina, seguidos de catarata e glaucoma. Em escolares a prevalência de deficiência visual não corrigida foi de 4,82% diminuindo para 0,41% com a correção refrativa. Em escolares a causa mais comum de deficiência visual foram erros refrativos não corrigidos. A deficiência visual e a cegueira são um importante problema de saúde pública no Brasil. É um problema significante em brasileiros mais velhos reforçando a necessidade de implementação de programas de prevenção de cegueira para pessoas idosas com ênfase nos indivíduos sem escolaridade. Em escolares são necessárias estratégias de custo-eficácia para atingir uma causa de deficiência visual facilmente tratável - a prescrição e a provisão de óculos

Variation of adult Great Tit Parus major body condition and blood parameters in relation to sex, age, year and season

In recent years, an increasing number of studies have focused on the ranges of variation of health related biochemical and haematological parameters in wildlife, but information is still scarce for enzymatic activities which can be extremely important in detecting potential responses to environmental change. In a Great Tit (Parus major) population, we describe the variation in relation to age, sex, season and year of: (1) morphological: body condition index, fat and muscle, (2) haematological: hematocrit, haemoglobin, white blood cell count and heterophil/lymphocyte ratio, and (3) biochemical parameters: plasma protein and activities of plasma cholinesterases (acetylcholinesterase and butyrylcholinesterase) activity and red blood cell glutathione peroxidase. Sex had significant effects on all morphological parameters except fat. Age significantly affected cholinesterase activities, H/L ratio and haemoglobin, and there was a significant interaction between sex and age affecting hematocrit. There were significant interactions of year and season affecting almost all parameters studied - body condition index, fat, protein, acetyl and butyrylcholinesterase activities, glutathione peroxidase activity and haemoglobin. This study indicates that these parameters are largely influenced by year and seasonal effects, besides the individual's intrinsic variation. Therefore, when evaluating experimental or environmental change effects, appropriate controls should be used. © Dt. Ornithologen-Gesellschaft e.V. 2009