53 research outputs found
Rabies virus seroprevalence among dogs in Limpopo National Park and the phylogenetic analyses of rabies viruses in Mozambique
Rabies is considered a neglected disease among many developing Asian and African
countries, including Mozambique, where its re-emergence is often attributed to low dog parenteral
vaccination coverage. The objectives of this study were two-fold: (1) to assess the level of antibodies
against rabies virus in dogs (n = 418) in Limpopo National Park (LNP), and (2) to genetically
characterise selected rabies viruses from brain tissue samples collected in 2017 and 2018. To meet
the first objective, we used the BioProTM Rabies blocking ELISA antibody kit, and the results were
expressed as the percentage of blocking (%PB). Dog sera with PB ≥ 40% were considered positive
for antibodies to rabies virus, whereas sera with PB < 40% were negative. Just under ninety percent
(89.2%; n = 373) of dogs were seronegative, and the rest (10.8%; n = 45) had detectable levels of rabies
virus-specific antibodies. All eight brain tissue samples were positive for rabies virus antigen using a
direct fluorescent antibody test and amplified in a quantitative real-time PCR, but only five (n = 4
from dogs and n = 1 from a cat) were amplified in a conventional reverse-transcription PCR targeting
partial regions of the nucleoprotein (N) and the glycoprotein (G) genes. All samples were successfully
sequenced. Phylogenetically, the rabies viruses were all of dog origin and were very closely related to
each other (Africa 1b rabies virus lineage). Furthermore, the sequences had a common progenitor
with other rabies viruses from southern Africa, confirming the transboundary nature of rabies and the
pivotal role of dogs in maintaining rabies cycles. The study demonstrates the principal application
of the BioProTM rabies ELISA antibody for the detection of anti-lyssavirus-specific antibodies in the
serum samples of dogs, and most importantly, it highlights the low levels of antibodies against rabies
virus in this dog population.The Third Framework Agreement Program “FA 3 III DGD/ITM 2014–2016” Project: “Communities on the move: animal and human health challenges” from the University of Pretoria (UP) and the Directorate-General Development Cooperation and Humanitarian Aid (DGD)/the Institute of Tropical Medicine of Antwerp (ITM) and by Fundo para a Investigação Aplicada e Multissectorial-FIAM.https://www.mdpi.com/journal/pathogensdm2022Centre for Veterinary Wildlife StudiesVeterinary Tropical Disease
Formation of Pd2Si on single-crystalline Si (100) at ultrafast heating rates : an in-situ analysis by nanocalorimetry
The kinetics of intermediate phase formation between ultrathin films of Pd (12 nm) and single-crystalline Si (100) is monitored by in-situ nanocalorimetry at ultrafast heating rates. The heat capacity curves show an exothermic peak related to the formation of Pd2Si. A kinetic model which goes beyond the conventional linear-parabolic growth to consider independent nucleation and lateral growth of Pd2Si along the interface and vertical growth mechanisms is developed to fit the calorimetric curves. The model is used to extract the effective interfacial nucleation/growth and diffusion coefficients at the unusually high temperatures of silicide formation achieved at very fast heating rates
Enhanced diagnosis of rabies and molecular evidence for the transboundary spread of the disease in Mozambique
Rabies is a neglected zoonotic disease with veterinary and public health significance,
particularly in Africa and Asia. The current knowledge of the epidemiology of rabies in
Mozambique is limited because of inadequate sample submission, constrained diagnostic
capabilities and a lack of molecular epidemiological research. We wanted to consider the
direct, rapid immunohistochemical test (DRIT) as an alternative to the direct fluorescent
antibody (DFA) for rabies diagnosis at the diagnostic laboratory of the Central Veterinary
Laboratory (CVL), Directorate of Animal Science, Maputo, Mozambique. Towards this aim, as
a training exercise at the World Organisation for Animal Health (OIE) Rabies Reference
Laboratory in South Africa, we performed the DRIT on 29 rabies samples from across
Mozambique. With the use of the DRIT, we found 15 of the 29 samples (52%) to be negative.
The DRIT-negative samples were retested by DFA at the OIE Rabies Reference Laboratory, as
well as with an established real-time Polymerase chain reaction, confirming the DRIT-negative
results. The DRIT-positive results (14/29) were retested with the DFA and subsequently
amplified, sequenced and subjected to phylogenetic analyses, confirming the presence of
rabies RNA. Molecular epidemiological analyses that included viruses from neighbouring
countries suggested that rabies cycles within Mozambique might be implicated in multiple
instances of cross-border transmission. In this regard, our study has provided new insights
that should be helpful in informing the next steps required to better diagnose, control and
hopefully eliminate rabies in Mozambique.The National Research Foundation
(NRF) of South Africahttp://www.jsava.co.zaam2017Microbiology and Plant Patholog
Hidden spin-texture at topological domain walls drive exchange bias in a Weyl semimetal
Exchange bias is a phenomenon critical to solid-state technologies that
require spin valves or non-volatile magnetic memory. The phenomenon is usually
studied in the context of magnetic interfaces between antiferromagnets and
ferromagnets, where the exchange field of the former acts as a means to pin the
polarization of the latter. In the present study, we report an unusual instance
of this phenomenon in the topological Weyl semimetal Co3Sn2S2, where the
magnetic interfaces associated with domain walls suffice to bias the entire
ferromagnetic bulk. Remarkably, our data suggests the presence of a hidden
order parameter whose behavior can be independently tuned by applied magnetic
fields. For micron-size samples, the domain walls are absent, and the exchange
bias vanishes, suggesting the boundaries are a source of pinned uncompensated
moment arising from the hidden order. The novelty of this mechanism suggests
exciting opportunities lie ahead for the application of topological materials
in spintronic technologies.Comment: Main text: 11 pages, 4 figures. Supplementary information: 7 pages, 6
figures. Supplementary videos:
Errors in chromosome segregation during oogenesis and early embryogenesis
Errors in chromosome segregation occurring during human oogenesis and early embryogenesis are very common. Meiotic chromosome development during oogenesis is subdivided into three distinct phases. The crucial events, including meiotic chromosome pairing and recombination, take place from around 11 weeks until birth. Oogenesis is then arrested until ovulation, when the first meiotic division takes place, with the second meiotic division not completed until after fertilization. It is generally accepted that most aneuploid fetal conditions, such as trisomy 21 Down syndrome, are due to maternal chromosome segregation errors. The underlying reasons are not yet fully understood. It is also clear that superimposed on the maternal meiotic chromosome segregation errors, there are a large number of mitotic errors taking place post-zygotically during the first few cell divisions in the embryo. In this chapter, we summarise current knowledge of errors in chromosome segregation during oogenesis and early embryogenesis, with special reference to the clinical implications for successful assisted reproduction
Design and implementation of a generalized laboratory data model
<p>Abstract</p> <p>Background</p> <p>Investigators in the biological sciences continue to exploit laboratory automation methods and have dramatically increased the rates at which they can generate data. In many environments, the methods themselves also evolve in a rapid and fluid manner. These observations point to the importance of robust information management systems in the modern laboratory. Designing and implementing such systems is non-trivial and it appears that in many cases a database project ultimately proves unserviceable.</p> <p>Results</p> <p>We describe a general modeling framework for laboratory data and its implementation as an information management system. The model utilizes several abstraction techniques, focusing especially on the concepts of inheritance and meta-data. Traditional approaches commingle event-oriented data with regular entity data in <it>ad hoc </it>ways. Instead, we define distinct regular entity and event schemas, but fully integrate these via a standardized interface. The design allows straightforward definition of a "processing pipeline" as a sequence of events, obviating the need for separate workflow management systems. A layer above the event-oriented schema integrates events into a workflow by defining "processing directives", which act as automated project managers of items in the system. Directives can be added or modified in an almost trivial fashion, i.e., without the need for schema modification or re-certification of applications. Association between regular entities and events is managed via simple "many-to-many" relationships. We describe the programming interface, as well as techniques for handling input/output, process control, and state transitions.</p> <p>Conclusion</p> <p>The implementation described here has served as the Washington University Genome Sequencing Center's primary information system for several years. It handles all transactions underlying a throughput rate of about 9 million sequencing reactions of various kinds per month and has handily weathered a number of major pipeline reconfigurations. The basic data model can be readily adapted to other high-volume processing environments.</p
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