Roles of reelin and disabled1 in neural development in zebrafish.

Reelin and Disabled 1 (Dabl) are known to be involved in neuronal migration in vertebrates and in particular in radial migration. Reelin is a secreted protein that can bind several receptors and the signal is intracellular transduced by Dabl. The final targets of the Reelin pathway are molecules that regulate cytoskeletal remodeling. In my project I studied the expression pattern of reelin and dabl in several areas of the zebrafish CNS. The differences found in the telencephalic expression of reelin and dabl between teleosts and tetrapods are likely to arise from the process of eversion, which is specific for the teleost telencephalon. On the contrary, all the other regions of the CNS present a conservative pattern of expression, in comparable structures among vertebrates, with the only exception of the olfactory bulb that does not express reelin in zebrafish. As the dabl gene shows a high degree of complexity in mammals and mice, I studied the genomic organization of the dabl gene in zebrafish and found a similarly complex organization. In order to study the functions of the Reelin pathway in neuronal migration in zebrafish, I performed loss of function experiments with morpholino antisense oligonucleotides. I found defects at level of several neuronal groups including the facial branchiomotor nucleus, the Mauthner neurons and neural crests. To investigate whether the role of dabl in the migration of these neuronal groups may be that of conveying a Reelin signal, I attempt to rescue these phenotypes by overexpressing full length dabl or truncated forms of the protein that lack the Reelin or the CDK5 responsive domains. It appears that the presence of the tyrosine domain, but not of the CDK5 phosphorylation domain, is necessary for partial resoiing of most of these phenotypes. I also found that some populations of neurons that express dabl show defects in neurites growth in morpholino injected embryos

Towards improving livestock export marketing support services in the Somali context: Survey findings and implications

This publication presents study carried out to provide empirical information that informs the debate and decision making process towards improving livestock trade and marketing in Somalia by enabling the development of effective and efficient marketing support services and accountable and competent rural institutions. The study focuses mainly on objectives which are to generate information that could be used to improve livestock export marketing institutions and support services. The study was conducted to: standardize quality and the criteria used for grading livestock for export; identify hazard analysis critical control points (HACCPs) along marketing chains; develop and formalize quality control systems; link primary, district & regional markets more effectively; reduce transactions costs for traders; increase competitiveness for producers; strengthen the regulatory role of local administrators; and to develop and disseminate relevant market information to stakeholders

A rapid appraisal of institutions supporting Somali livestock export

This publication presents finding of a rapid appraisal of institutions supporting livestock trade and marketing in Somalia. The study was carried to: identify institutions supporting livestock trade and marketing in the country; evaluate the roles played by these institutions in facilitating livestock trade and marketing information flow; application of grades and standards in livestock trade, and livestock export marketing promotional activities; assess the level of networking among these institutions while facilitating livestock export trade and marketing; analyze constraints faced by these institutions in executing their activities. It was anticipated that this will be useful in designing supportive infrastructure to enable them play an effective role in improving livestock trade and marketing through enhanced accountability and competence. Emphasis was put on organizations involved in livestock marketing information flow, application of grades and standards in livestock products, and, livestock export promotion. This study identifi ed some forms of organizations supporting livestock export trade in Somalia, viz. brokers, veterinary services delivery systems, port authorities, livestock shipping firms, money transfer services, local government and regional administrations that were in-charge of livestock markets, central government, and a variety of private traders associations. These organisations supported the principal market participants: the small-scale traders, agents of exporters, and exporters in their trial to make effective livestock export trade. The organizations operated under a set of rules and procedures that influenced their activities in facilitating livestock. However, it was noted that there was limited capacity to enforce adherence to some of the rules and regulations by these organizations. This appraisal recognized that although there exist informal grading system based on a number of attributes (age of animal, sex of animal, nutritional status, weight and size, breed and health status), none of the identified institutions was engaged in overt activities to develop further and publicize application of these grades in livestock trade. This was noted to persist despite the general knowledge that suitable grading would significantly promote trade. This appraisal established that currently, the main centre of attention of the public sector is at the ports of exit. In these ports, the government implements a rudimentary animal health certifi cation system, based on clinical inspection of animals prior to loading. There are also some instances of monitoring in some of the secondary markets. Implementation of an effective health and certification system is constrained by limited capacity, both human and physical within the respective institutions and by the absence of a central veterinary administration that is recognized internationally. These constraints need urgent redress to guarantee participation in livestock export trade by Somali traders. It is important to note that a certification system put in place should also be cost effective and easy to apply in order to be sustainable

The Somali chilled meat value chain: Structure, operation, profitability and opportunities to improve the competitiveness of Somalia’s chilled meat export trade

Export-oriented pastoral livestock production is an important source of livelihood of the Somali people. The country is largely food deficient, with imports forming a significant proportion of basic food requirements and which are largely financed through earnings from exports of live animals and meat. The export of meat products offers more avenues for increased earnings and tax revenue by exploiting the available opportunities for domestic value addition, than does live animal trade. This study characterizes the Somali chilled export meat value chain in terms of actors, institutions and practices, and provides an initial analysis of their profitability in handling four species of livestock. It also canvasses actors’ views on opportunities and constraints faced. Its main objective is to provide information that will enable development of strategies to improve the efficiency of the Somali chilled meat export value chain as a way of increasing incomes to market actors. Primary data used was obtained from a rapid appraisal of chilled meat export marketing value chains in Somalia and a formal survey of market actors (brokers, small-scale traders, agents of exporters, exporters and airfreight operators). Secondary data obtained from a review of relevant literature and interviews with expert informants was also generated. The study identified a widely-recognized and consistently-applied grading system for slaughter stock. Quality requirements in importing countries were revealed to be well known throughout the chain, in that actors’ rankings of attributes were consistent within and between actor stages. Conversely, knowledge of health and safety requirements in the importing countries was known only to exporters. Other inconsistencies throughout the chain included the nature and strength of trading relationships: long-lived at exporter and agent level but short term and cash-based at producer level. Although exporters made payments mostly on the basis of carcass weight, agents of exporters paid based on per head of live animals. There is evidence of economies of scale, and of financial advantage in species specialization (specifically, goats) by traders. Most actors’ aspirations feature expansion, but they report investment funding as their main constraint. The report presents preliminary recommendations for public and private sectors, many predicated on further study. These focus on value addition and information sharing on what constitutes value, building of product identity and legally protecting its unique status, and coordination to address costs

Ultra-high-field MR imaging in polymicrogyria and epilepsy

BACKGROUND AND PURPOSE: Polymicrogyria is a malformation of cortical development that is often identified in children with epilepsy or delayed development. We investigated in vivo the potential of 7T imaging in characterizing polymicrogyria to determine whether additional features could be identified. MATERIALS AND METHODS: Ten adult patients with polymicrogyria previously diagnosed by using 3T MR imaging underwent additional imaging at 7T. We assessed polymicrogyria according to topographic pattern, extent, symmetry, and morphology. Additional imaging sequences at 7T included 3D T2* susceptibility-weighted angiography and 2D tissue border enhancement FSE inversion recovery. Minimum intensity projections were used to assess the potential of the susceptibility-weighted angiography sequence for depiction of cerebral veins. RESULTS: At 7T, we observed perisylvian polymicrogyria that was bilateral in 6 patients, unilateral in 3, and diffuse in 1. Four of the 6 bilateral abnormalities had been considered unilateral at 3T. While 3T imaging revealed 2 morphologic categories (coarse, delicate), 7T susceptibility-weighted angiography images disclosed a uniform ribbonlike pattern. Susceptibility-weighted angiography revealed numerous dilated superficial veins in all polymicrogyric areas. Tissue border enhancement imaging depicted a hypointense line corresponding to the gray-white interface, providing a high definition of the borders and, thereby, improving detection of the polymicrogyric cortex. CONCLUSIONS: 7T imaging reveals more anatomic details of polymicrogyria compared with 3T conventional sequences, with potential implications for diagnosis, genetic studies, and surgical treatment of associated epilepsy. Abnormalities of cortical veins may suggest a role for vascular dysgenesis in pathogenesis

Semiautomated Evaluation of the Primary Motor Cortex in Patients with Amyotrophic Lateral Sclerosis at 3T

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Semiautomated evaluation of the primary motor cortex in patients with amyotrophic lateral sclerosis at 3t

Amyotrophic lateral sclerosis is a neurodegenerative disease involving the upper and lower motor neurons. In amyotrophic lateral sclerosis, pathologic changes in the primary motor cortex include Betz cell depletion and the presence of reactive iron-loaded microglia, detectable on 7T MR images as atrophy and T2*-hypointensity. Our purposes were the following: 1) to investigate the signal hypointensity-to-thickness ratio of the primary motor cortex as a radiologic marker of upper motor neuron involvement in amyotrophic lateral sclerosis with a semiautomated method at 3T, 2) to compare 3T and 7T results, and 3) to evaluate whether semiautomated measurement outperforms visual image assessment

Risk mapping of Rinderpest sero-prevalence in Central and Southern Somalia based on spatial and network risk factors

<p>Abstract</p> <p>Background</p> <p>In contrast to most pastoral systems, the Somali livestock production system is oriented towards domestic trade and export with seasonal movement patterns of herds/flocks in search of water and pasture and towards export points. Data from a rinderpest survey and other data sources have been integrated to explore the topology of a contact network of cattle herds based on a spatial proximity criterion and other attributes related to cattle herd dynamics. The objective of the study is to integrate spatial mobility and other attributes with GIS and network approaches in order to develop a predictive spatial model of presence of rinderpest.</p> <p>Results</p> <p>A spatial logistic regression model was fitted using data for 562 point locations. It includes three statistically significant continuous-scale variables that increase the risk of rinderpest: home range radius, herd density and clustering coefficient of the node of the network whose link was established if the sum of the home ranges of every pair of nodes was equal or greater than the shortest distance between the points. The sensitivity of the model is 85.1% and the specificity 84.6%, correctly classifying 84.7% of the observations. The spatial autocorrelation not accounted for by the model is negligible and visual assessment of a semivariogram of the residuals indicated that there was no undue amount of spatial autocorrelation. The predictive model was applied to a set of 6176 point locations covering the study area. Areas at high risk of having serological evidence of rinderpest are located mainly in the coastal districts of Lower and Middle Juba, the coastal area of Lower Shabele and in the regions of Middle Shabele and Bay. There are also isolated spots of high risk along the border with Kenya and the southern area of the border with Ethiopia.</p> <p>Conclusions</p> <p>The identification of point locations and areas with high risk of presence of rinderpest and their spatial visualization as a risk map will be useful for informing the prioritization of disease surveillance and control activities for rinderpest in Somalia. The methodology applied here, involving spatial and network parameters, could also be applied to other diseases and/or species as part of a standardized approach for the design of risk-based surveillance activities in nomadic pastoral settings.</p

Ultra-high-field targeted imaging of focal cortical dysplasia: The intracortical black line sign in type IIB

BACKGROUND AND PURPOSE: Conventional MR imaging has limitations in detecting focal cortical dysplasia. We assessed the added value of 7T in patients with histologically proved focal cortical dysplasia to highlight correlations between neuropathology and ultra-high-field imaging. MATERIALS AND METHODS: Between 2013 and 2019, we performed a standardized 7T MR imaging protocol in patients with drug-resistant focal epilepsy. We focused on 12 patients in whom postsurgical histopathology revealed focal cortical dysplasia and explored the diagnostic yield of preoperative 7T versus 1.5/3T MR imaging and the correlations of imaging findings with histopathology. We also assessed the relationship between epilepsy surgery outcome and the completeness of surgical removal of the MR imaging-visible structural abnormality. RESULTS: We observed clear abnormalities in 10/12 patients using 7T versus 9/12 revealed by 1.5/3T MR imaging. In patients with focal cortical dysplasia I, 7T MR imaging did not disclose morphologic abnormalities (n = 0/2). In patients with focal cortical dysplasia II, 7T uncovered morphologic signs that were not visible on clinical imaging in 1 patient with focal cortical dysplasia IIa (n = 1/4) and in all those with focal cortical dysplasia IIb (n = 6/6). T2*WI provided the highest added value, disclosing a peculiar intracortical hypointense band (black line) in 5/6 patients with focal cortical dysplasia IIb. The complete removal of the black line was associated with good postsurgical outcome (n = 4/5), while its incomplete removal yielded unsatisfactory results (n = 1/5). CONCLUSIONS: The high sensitivity of 7T T2*-weighted images provides an additional tool in defining potential morphologic markers of high epileptogenicity within the dysplastic tissue of focal cortical dysplasia IIb and will likely help to more precisely plan epilepsy surgery and explain surgical failures

Multi-centre and multi-vendor reproducibility of a standardized protocol for quantitative susceptibility Mapping of the human brain at 3T

Quantitative Susceptibility Mapping (QSM) is an MRI-based technique allowing the non-invasive quantification of iron content and myelination in the brain. The RIN – Neuroimaging Network established an optimized and harmonized protocol for QSM across ten sites with 3T MRI systems from three different vendors to enable multicentric studies. The assessment of the reproducibility of this protocol is crucial to establish susceptibility as a quantitative biomarker. In this work, we evaluated cross-vendor reproducibility in a group of six traveling brains. Then, we recruited fifty-one volunteers and measured the variability of QSM values in a cohort of healthy subjects scanned at different sites, simulating a multicentric study. Both voxelwise and Region of Interest (ROI)-based analysis on cortical and subcortical gray matter were performed. The traveling brain study yielded high structural similarity (∼0.8) and excellent reproducibility comparing maps acquired on scanners from two different vendors. Depending on the ROI, we reported a quantification error ranging from 0.001 to 0.017 ppm for the traveling brains. In the cohort of fifty-one healthy subjects scanned at nine different sites, the ROI-dependent variability of susceptibility values, of the order of 0.005–0.025 ppm, was comparable to the result of the traveling brain experiment. The harmonized QSM protocol of the RIN – Neuroimaging Network provides a reliable quantification of susceptibility in both cortical and subcortical gray matter regions and it is ready for multicentric and longitudinal clinical studies in neurological and pychiatric diseases