Jusot J.-F.,Epidemiology Health Environment Climate Unit |
Tohon Z.,University of Kentucky |
Yazi A.A.,Epidemiology Unit |
Collard J.-M.,Biology Unit
BMC Infectious Diseases | Year: 2013
Background: Beside high mortality, acute bacterial meningitis may lead to a high frequency of neuropsychological sequelae. The Sahelian countries belonging to the meningitis belt experience approximately 50% of the meningitis cases occurring in the world. Studies in Africa have shown that N. meningitidis could cause hearing loss in up to 30% of the cases, exceeding sometimes measles. The situation is similar in Niger which experiences yearly meningitis epidemics and where rehabilitation wards are rare and hearing aids remain unaffordable. The aim of this study was to estimate the frequency of neuropsychological sequelae after acute bacterial meningitis in four of the eight regions of Niger.Methods: Subjects exposed to acute bacterial meningitis were enrolled into a cohort with non exposed subjects matched on age and gender. Consenting subjects were interviewed during inclusion and at a control visit two months later. If clinical symptoms or psychological troubles persisted at both visits among the exposed subjects with a frequency significantly greater than that observed among the non exposed subjects, a sequelae was retained. The comparison of the frequency of sequelae between non exposed and exposed subjects to bacterial meningitis was also calculated using the Fisher exact test.Results: Three persisting functional symptoms were registered: headaches, asthenia, and vertigo among 31.3, 36.9, and 22.4% respectively of the exposed subjects. A significant motor impairment was retrieved among 12.3% of the exposed versus 1.6% of the non exposed subjects. Hearing loss significantly disabled 31.3% of the exposed subjects and 10.4% exhibited a serious deafness.Conclusions: This study carried out in Niger confirms two serious neurological sequelae occurring at high frequencies after bacterial meningitis: severe and profound hearing loss and motor impairment. Cochlear implantation and hearing aids are too expensive for populations living in developing countries. Neurological sequelae occurring after meningitis should sensitize African public health authorities on the development of rehabilitation centers. All these challenges can be met through existing strategies and guidelines. © 2013 Jusot et al.; licensee BioMed Central Ltd.
Hefke G.,University of the Western Cape |
Hefke G.,Biology Unit |
Davison S.,University of the Western Cape |
D'Amato M.E.,University of the Western Cape
Electrophoresis | Year: 2015
The utilization of binary markers in human individual identification is gaining ground in forensic genetics. We analyzed the polymorphisms from the first commercial indel kit Investigator DIPplex (Qiagen) in 512 individuals from Afrikaner, Indian, admixed Cape Colored, and the native Bantu Xhosa and Zulu origin in South Africa and evaluated forensic and population genetics parameters for their forensic application in South Africa. The levels of genetic diversity in population and forensic parameters in South Africa are similar to other published data, with lower diversity values for the native Bantu. Departures from Hardy-Weinberg expectations were observed in HLD97 in Indians, Admixed and Bantus, along with 6.83% null homozygotes in the Bantu populations. Sequencing of the flanking regions showed a previously reported transition G>A in rs17245568. Strong population structure was detected with Fst, AMOVA, and the Bayesian unsupervised clustering method in STRUCTURE. Therefore we evaluated the efficiency of individual assignments to population groups using the ancestral membership proportions from STRUCTURE and the Bayesian classification algorithm in Snipper App Suite. Both methods showed low cross-assignment error (0-4%) between Bantus and either Afrikaners or Indians. The differentiation between populations seems to be driven by four loci under positive selection pressure. Based on these results, we draw recommendations for the application of this kit in SA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
News Article | October 29, 2015
"This 'rotation model', which made the cover of BioEssays, represents a true paradigm shift in the membrane receptor field," stated Prof. Pierre De Meyts, a renowned researcher of insulin and receptor binding for almost half a century and one of the reviewers of the paper by Prof. Ichiro Maruyama, the head of the Information Processing Biology Unit at Okinawa Institute of Science and Technology Graduate University (OIST).
As the 20th-century novelist Joseph Conrad famously wrote, "It's only those who do nothing that make no mistakes, I suppose," and Nature is very busy, so she makes lots of them. But as a genius, she can use them to advantage. Take for example whole genome duplication—an error in DNA replication, or mating between different species, that doubles the number of chromosomes, leading to a duplication of the vast majority of genes. Such grand mistakes turn out to be among the major forces accelerating evolution. Organisms with additional sets of genes can accumulate and test mutations much faster and with less selection pressure than organisms with just one set of genes. One of the copies of a gene can maintain normal functioning of the cells even if the other copy mutates to become harmful or useless. Other possible alternatives are when one of the genes acquires a completely new function, or both genes start to specialise, each taking over a certain part of the ancestral function. Redundancy is common in nature, for example many human genes exist in several copies. However, excessive redundancy can interfere with efficiency. Therefore, each whole genome duplication event is followed by the loss of duplicate genes. A new collaborative paper, published in Proceedings of the National Academy of Sciences (PNAS) by scientists from the Okinawa Institute of Science and Technology Graduate University (OIST), the University of the Ryukyus, Tohoku University, and Nihon University, proposes a two-phase mathematical model describing gene loss patterns over two differing time scales after a whole genome duplication. The research, started by Dr Jun Inoue, now a staff scientist in the OIST Mathematical Biology Unit, Assistant Prof. Yukuto Sato, now at Tohoku University, and Prof. Mutsumi Nishida, now Vice President of the University of the Ryukyus, while all three were working together at the University of Tokyo, focused on teleost fishes, the largest group of bony fishes (Fig. 1). These fishes underwent their own specific whole genome duplication approximately 300 million years ago. "By contrast, the last whole genome duplication in the human lineage happened about half a billion years ago, and it is extremely difficult to trace," explains Prof. Robert Sinclair, the head of the Mathematical Biology Unit. The work required the development of both new computational and also mathematical tools, each one adapted to the previously determined evolutionary history of the species involved. These tools, developed by the research group, can be applied to other cases of whole genome duplications in organisms of any kind, including humans. Comparison of the genomes of zebrafish and the common Japanese fish medaka—two distantly related species with 250 million years of independent evolution (Fig. 2A)—shows that they are very similar (Fig. 2B). "Their shapes, habitats, and reproductive patterns are very different, which suggests that the basic structure of the teleost genome was established before the major diversification of teleost species," says Dr Inoue. Genome analysis of seven other well-studied fishes supports this conclusion. The results of this study suggest that approximately 80% of the duplicate genes were lost in the first 60 million years after the whole genome duplication event (Fig. 2C). Considering that the first vertebrates appeared on Earth about 500 million years ago (Fig. 2A), 60 million years is a very short time. Dr Inoue states that it is possible that genome reduction happened even faster. "We are waiting for the eel genome to be fully decoded to check this hypothesis," he says. Eels and their relatives are one of the first groups separated from the majority of teleost fishes after the teleost-specific whole genome duplication. Comparison of eels with the other teleosts will eventually shed even more light on the evolution of all fishes. The idea of loss of redundant genes is not new; however, an important new result is that "we found evidence that genes are disposed of rapidly and in bulk after the whole genome duplication, and it leads to a rapid reshaping of the genome," says Prof. Sinclair. In the first phase, clusters of adjacent genes or even large chromosomal segments may have been deleted if they were useless or problematic. Interestingly, the diversification of many major lineages of living teleosts did not occur in this rapid phase (Fig. 2A). The second phase is characterised by slower gene loss (Fig. 2C). The scientists suggest that some paired genes are retained if each copy becomes essential. Other duplicate genes continue to be lost, but mostly one-by-one. This process continues to this day. Evolution never stops! The methods of genome analysis developed for this study will pave the road to a better understanding of evolution, including our own. Explore further: Paddlefish's doubled genome may question theories on limb evolution More information: Rapid genome reshaping by multiple-gene loss after whole-genome duplication in teleost fish suggested by mathematical modeling, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1507669112
Gunnarsson J.,Biology Unit |
Gunnarsson J.,Swedish National Police Academy |
Eriksson H.,Biology Unit |
Ansell R.,Biology Unit |
Ansell R.,Linkoping University
Z Zagadnien Nauk Sadowych | Year: 2010
In forensic biology, trace recovery by lifting traces for DNA typing using adhesive mini-tapes, is an efficient complement to traditional recovery methods such as swabbing or cutting. Here we present real crime case success rates for DNA sampling using mini-tapes based on a large data-set. The major findings are an increase in DNA mixtures compared to using conventional trace recovery techniques such as cutting, but in general with a significantly lower degree of inhibited DNA extracts and a higher proportion of usable DNA results. © by the Institute of Forensic Research.