Prevalence and causes of blindness at a tertiary hospital in Douala, Cameroon

André Omgbwa Eballé1,4, Côme Ebana Mvogo1,3, Godefroy Koki2, Nyouma Mounè3, Cyrille Teutu5, Augustin Ellong2,3, Assumpta Lucienne Bella2,41Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon; 2Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon; 3General Hospital of Douala, Ophthalmology Unit, Douala, Cameroon; 4Cameroon National Blindness Control Programme, Ministry of Public Health, Yaoundé, Cameroon; 5Higher Institute of Health Sciences, Mountain University, Banganté, CameroonPurpose: The aim of this study was to determine the prevalence and causes of bilateral and unilateral blindness in the town of Douala and its environs based on data from the ophthalmic unit of a tertiary hospital in Douala.Methods: We conducted a retrospective epidemiological survey of consultations at the eye unit of the Douala General Hospital over the last 20 years (from January 1, 1990 to December 31, 2009).Results: Out of the 1927 cases of blindness, 1000 were unilateral, corresponding to a hospital prevalence of 1.84% and 927 cases were bilateral, corresponding to a hospital prevalence of 1.71%. No statistically significant difference was noted between the two (P = 0.14). The leading causes of bilateral blindness were cataract (50.1%), glaucoma (19.7%), and diabetic retinopathy (7.8%) while the leading causes of unilateral blindness were cataract (40.4%), glaucoma (14.1%), and retinal detachment (9.1%). Cataract (51.2%), cortical blindness (16.3%), and congenital glaucoma (10%) were the leading causes of bilateral blindness in children aged less than 10 years.Conclusion: Blindness remains a public health problem in the Douala region with a hospital prevalence which is relatively higher than the national estimate given by the National Blindness Control Program.Keywords: bilateral blindness, unilateral blindness, prevalence, Douala, Cameroo

Céphalées chez la jeune femme : ne pas négliger une hypertension intracrânienne

Nous rapportons le cas d’une jeune femme ayant consulté pour céphalées et diplopie binoculaire sans baisse d’acuité visuelle. Le fond d’oeil a objectivé un oedème papillaire bilatéral de stase.L’imagerie cérébrale magnétique (IRM) était normale et la ponction lombaire avait ramené un liquide céphalo-rachidien (LCR) hypertendu, clair, eau de roche avec une pression d’ouverture de 37 cm d’H2O, sans signes infectieux et/ou inflammatoire. La diplopie et les céphalées avaient régressé après réalisation d’une ponction lombaire soustractive de 30 ml de LCR. La régression de l’oedème papillaire et la normalisation du champ visuel furent obtenus en 3 semaines de traitement par acétazolamide. L’absence d’étiologie et la bonne réponse aux thérapeutiques ont fait retenir le diagnostic de l’HTIC idiopathique. La survenue de céphalées tout comme leur récurrence impose une anamnèse détaillée et un examen clinique précis. Ceci afin de ne pas méconnaître une hypertension intracrânienne et permettre une prise en charge appropriée. L’HTIC idiopathique reste un diagnostic d’élimination. Mots clés : céphalées, oedème papillaire ; hypertension intracrânienne idiopathique English Abstract: Headaches in young women: do not neglect intracranial hypertensionWe report the case of a young woman who consulted for headache and binocular diplopia without any loss of visual acuity. The fundus objectified a bilateral papillary oedema of stasis. Magnetic brain imaging (MRI) was normal and the lumbar puncture had brought back a hypertensive, clear, rock-watery cerebrospinal fluid (CSF) with an opening pressure of 37 cm H2O, without signs of infection and/or inflammation. Diplopia and headache regressed after a subtractive lumbar puncture of 30 ml CSF. The regression of papilloedema and normalisation of the visual field was achieved in 3 weeks of treatment with acetazolamide. The lack of etiology and the good response to therapy led to the diagnosis of idiopathic ICH. The occurrence and recurrence of headaches require a detailed history and a precise clinical examination. This is to ensure that intracranial hypertension is not overlooked and to enable appropriate treatment. Idiopathic HTIC remains a diagnosis of elimination. Key words: headaches, papilloedema; idiopathic intracranial hypertensio

From mass selection to genomic selection: one century of breeding for quantitative yield components of oil palm (Elaeis guineensis Jacq.)

International audienceMore efficient methods are required to breed oil palm (Elaeis guineensis Jacq.) for yield maximization in order to meet the increased demand for palm oil while limiting environmental impacts. This review article analyzes the evolution of breeding schemes for oil palm yield and its quantative components and the changes expected to take place with genomic selection (GS). Genetic improvement of oil palm yield started in the 1920s through mass selection. Later, several disruptive improvements dramatically increased the rate of genetic progress: (1) understanding the heredity of fruit form and the adoption of tenera, with thicker mesocarp, in plantations; (2) the discovery of hybrid vigor and the adoption of modified reciprocal recurrent selection; and (3) clonal selection, exploiting intra-hybrid variability. In addition, the use of linear mixed models to estimate genetic values has made selection more efficient. Today, GS appears to be a new disruptive improvement that can speed up breeding schemes by avoiding field trials in some cycles and increase selection intensity by evaluating more candidates. The genetic potential for oil palm yield has increased considerably over one century of breeding. GS is expected to bring the rate of genetic progress to a previously unprecedented level. The future studies on oil palm GS will aim at making it efficient for all yield components. For this purpose, they should focus in particular on the optimization of training populations and on the improvement of prediction models. Minimizing environmental impacts will also require improvement in other aspects (resistance to diseases, cultural practices, etc.)

Improving the accuracy of genomic predictions in an outcrossing species with hybrid cultivars between heterozygote parents: a case study of oil palm (Elaeis guineensis Jacq.)

International audienceGenomic selection (GS) is a method of marker-assisted selection revolutionizing crop improvement, but it can still be optimized. For hybrid breeding between heterozygote parents of different populations or species, specific aspects can be considered to increase GS accuracy: (1) training population genotyping, i.e., only genotyping the hybrid parents or also a sample of hybrid individuals, and (2) marker effects modeling, i.e., using population-specific effects of single nucleotide polymorphism alleles model (PSAM) or across-population SNP genotype model (ASGM). Here, this was investigated empirically for the prediction of the performances of oil palm hybrids for yield traits. The GS model was trained on 352 hybrid crosses and validated on 213 independent hybrid crosses. The training and validation hybrid parents and 399 training hybrid individuals were genotyping by sequencing. Despite the small proportion of hybrid individuals genotyped and low parental heterozygosity, GS prediction accuracy increased on average by 5% (range 1.4-31.3%, depending on trait and model) when training was done using genomic data on hybrids and parents compared with only parental genomic data. With ASGM, GS prediction accuracy increased on average by 3% (- 10.2 to 40%, depending on trait and genotyping strategy) compared with PSAM. We conclude that the best GS strategy for oil palm is to aggregate genomic data of parents and hybrid individuals and to ignore the parental origin of marker alleles (ASGM). To gain a better insight into these results, future studies should examine the respective effect of capturing genetic variability within crosses and taking segregation distortion into account when genotyping hybrid individuals, and investigate the factors controlling the relative performances of ASGM and PSAM in hybrid crops

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

International audienceLandscapes of eastern Adamaoua highlands have been shaped by successive weathering and erosion processes of Pan-African crystalline rocks and Neogene volcanics cover. Basalts have outpoured through major inherited structural discontinuities mostly in shallow incisions of lateritic pediplains previously shaped on the granitic basement. That has resulted in formation of a singular composite lateritic weathering profile on basalt superimposed to a truncated profile composed of mottled clays and saprolite on granite. The composite profile studied here is little evolved, mostly kaolinised on granite while basalt is weakly to moderately lateritised owing to differences in silica and iron oxide contents of the two contrasted parent rocks. During lateritic weathering, Cu, Ni, and Co are enriched in profile on granite but depleted on basalt, while Zr/Ti is relatively constant. Behavior and fractionation of REE are comparable except higher Eu* and Ce* anomaly on granite profile than on weathered basalt, owing to parent minerals differences, mostly feldspars in granite versus plagioclase and Fe-Mg minerals in basalt. The contrast in Eu* is also linked to differences in the Index Of Laterization (IOL) in weathered horizons of the two parent rocks. Beyond quite classical litho-dependent geochemical differences in the composite profile, persistence of per-humid climate and good drainage over Neogene have sustained rock-weathering and local surface erosion processes upon volcanic outpours and their contact surface with pediplains formed on Pan-African granitoids of Adamaoua highland

Genomic predictions improve clonal selection in oil palm (Elaeis guineensis Jacq.) hybrids

The prediction of clonal genetic value for yield is challenging in oil palm (Elaeis guineensis Jacq.). Currently, clonal selection involves two stages of phenotypic selection (PS): ortet preselection on traits with sufficient heritability among a small number of individuals in the best crosses in progeny tests, and final selection on performance in clonal trials. The present study evaluated the efficiency of genomic selection (GS) for clonal selection. The training set comprised almost 300 Deli x La Me crosses phenotyped for eight palm oil yield components and the validation set 42 Deli x La Me ortets. Genotyping-by-sequencing (GBS) revealed 15,054 single nucleotide polymorphisms (SNP). The effects of the SNP dataset (density and percentage of missing data) and two GS modeling approaches, ignoring (ASGM) and considering (PSAM) the parental origin of alleles, were assessed. The results showed prediction accuracies ranging from 0.08 to 0.70 for ortet candidates without data records, depending on trait, SNP dataset and modeling. ASGM was better (on average slightly more accurate, less sensitive to SNP dataset and simpler), although PSAM appeared interesting for a few traits. With ASGM, the number of SNPs had to reach 7,000, while the percentage of missing data per SNP was of secondary importance, and GS prediction accuracies were higher than those of PS for most of the traits. Finally, this makes possible two practical applications of GS, that will increase genetic progress by improving ortet preselection before clonal trials: (1) preselection at the mature stage on all yield components jointly using ortet genotypes and phenotypes, and (2) genomic preselection on more yield components than PS, among a large population of the best possible crosses at nursery stage