مجال
التميز
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تميز دراسي
وبحثي
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البحوث المنشورة
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البحث (1):
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عنوان البحث:
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Susceptibility to experimental
infection of the invertebrate locusts (Schistocerca gregaria) with the
apicomplexan parasite Neospora caninum
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رابط إلى البحث:
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Click here
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تاريخ النشر:
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02/12/2014
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موجز عن البحث:
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Neuropathogenesis is a feature of
Neospora caninum infection. In order to explore this in the absence of
acquired host immunity to the parasite, we have tested infection in locusts
(Schistocerca gregaria).We show for the first time that locusts are permissive
to intra-hemocoel infection with N. caninum tachyzoites. This was
characterized by alteration in body weight, fecal output, hemoparasitemia,
and sickness-related behavior. Infected locusts exhibited progressive signs
of sickness leading to mortality. Also, N. caninum showed neuropathogenic
affinity, induced histological changes in the brain and was able to replicate
in the brain of infected locusts. Fatty acid (FA) profiling analysis of the
brains by gas chromatography and multi-variate prediction models
discriminated with high accuracy (98%) between the FA profiles of the
infected and control locusts. DNA microarray gene expression profiling
distinguished infected from control S. gregaria brain tissues on the basis of
distinct differentially-expressed genes. These data indicate that locusts are
permissible to infection with N. caninum and that the parasite retains its
tropism for neural tissues in the invertebrate host. Locusts may facilitate
preclinical testing of interventional strategies to inhibit the growth of N.
caninum tachyzoites. Further studies on how N. caninum brings about changes
in locust brain tissue are now warranted.
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البحث (2):
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عنوان البحث:
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Influence of culture medium pH on internalization,
growth and phenotypic plasticity of Neospora caninum
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رابط إلى البحث:
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Click here
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تاريخ النشر:
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29/11/2010
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موجز عن البحث:
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Neospora caninum, a strictly intracellular
protozoan, is a major leading cause of parasiteinduced abortion in cattle. A
widely held view of N. caninum infection is that both cellular proliferation
and stage interconversion (tachyzoite–bradyzoite transformation) are
triggered, perhaps even modulated by, changes in cultural conditions. This
study tested the hypothesis that exposure of N. caninum tachyzoites to
different pH culture media affects the parasite’s entry, proliferation and
cyst formation in cultured cells. The endocytic pathway for N. caninum entry
into the K562 cell line was found to be mediated by low pH of culture medium.
Internalization of N. caninum by host cells was significantly increased in
acidic and alkaline culture medium compared to cells maintained in neutral
medium as revealed by transmission electron microscopy. Parasite proliferation
within Vero cells was assessed by plaque formation assay and was found to be
highest when pH level was optimum, paralleled by a decrease in the number of
cysts. In contrast, parasite encystation increased when thepHlevel was
alkaline or acidic, as evaluated by indirect immunofluorescence and
immunocytochemical analyses. Acidic pH regardless of state of host cell
infection suppressed the rate of host cell division. These findings suggest
that culture medium pH has a determinable effect on the host cell-N. caninum
interaction and support the hypothesis that pH of culture medium influence
the entry, growth, and phenotypic plasticity of N. caninum in mammalian
cells.
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البحث (3):
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عنوان البحث:
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Metabolic footprinting of extracellular metabolites
of brain endothelium infected with Neospora caninum in vitro
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رابط إلى البحث:
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Click here
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تاريخ النشر:
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12/11/2014
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موجز عن البحث:
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Background: The survival of the intracellular
protozoan parasite Neospora caninum depends on its ability to adapt to
changing metabolic conditions of the host cell. Thus, defining cellular and
metabolic changes in affected target tissues may aid in delineating
pathogenetic mechanism. We undertook this study to assess the metabolic
response of human brain microvascular endothelial cells (HBMECs) to N.
caninum infection in vitro. Methods: HBMECs were exposed to N. caninum
infection and the cytotoxic effects of infection were analyzed by the
3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromidin (MTT) assay
and lactate dehydrogenase (LDH) release assay. Metabolic footprinting of the
extracellular metabolites of parasite-infected and non-infected culture
supernatant was determined by using targeted (Randox RX Imola clinical chemistry
analyser) and unbiased RS (Raman microspectroscopy) approaches. Results: The
MTT assay did not reveal any cytotoxic effect of N. caninum challenge on host
cell viability. Measurement of LDH activity showed that N. caninum
significantly induced loss of cell membrane integrity in a time-dependent and
dose-dependent manner compared to control cells. Targeted biochemical
analysis revealed that beta hydroxybutyrate, pyruvate, ATP, total protein,
non-esterified fatty acids, and triglycerides are significantly different in
infected cells compared to controls. RS-based footprinting with principal
component analysis (PCA) were able to correctly distinguish extracellular
metabolites obtained from infected and control cultures, and revealed
infection-related spectral signatures at 865 cm−1, 984 cm−1, 1046 cm−1, and
1420 cm−1, which are attributed to variations in the content of lipids and
nucleic acids in infected cultures. Conclusions: The changing pattern of
extracellular metabolites suggests that HBMECs are target of metabolic
alterations in N. caninum infection, which seem to reflect the changing
metabolic state of infected cells and constitute a level of information
exchange that host and parasite use to coordinate activities. Keywords:
Adaptation, Blood brain barrier, Host-pathogen interaction, Metabolic
footprinting, Metabolomics, Neospora caninum.
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المؤتمرات العلمية:
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المؤتمر (1):
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عنوان المؤتمر:
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Saudi
Scientific International Conference
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تاريخ الإنعقاد:
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11-14 Oct 2012
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مكان
الإنعقاد:
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Brunel,
UK
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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Extra cellular pH governs the entry and
phenotypic plasticity of Neospora caninum
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ملخص المشاركة:
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Background
and aims: Neospora caninum, a strictly intracellular protozoan, is a major
leading cause of parasitic-induced abortion in cattle. Despite this prevalence, very little is
known about the pathogenesis of N. caninum infection. A widely held view of N. caninum infection
is that both cellular proliferation and stage interconversion
(tachyzoite-bradyzoite switching) are triggered, perhaps even modulated by,
changes in culture conditions. The present study aimed to examine the effects
of modification of the growth medium pH on N. caninum entry, proliferation
and transformation in cultured K-652 and Vero cell lines. Materials and
methods: The entry pathway of N. caninum in K-562 cells was studied by using
a cell membrane potential-sensitive probe. Parasite invasion and
proliferation of Vero cells was assessed by plaque formation assay. Stage
transformation was studied using indirect double immunofluorescence and
electron microscopy approaches. Results: Here we report that a major pathway
for N. caninum entry into the K-562 cell line is dependent on endocytosis and
exposure to a low pH. Also, N. caninum proliferation in Vero cells was
highest when pH level was optimum and parasite encystation increased when the
pH level was alkaline or acidic. Conclusions: These data suggest that
external pH has a determinable effect on the host cells and free N. caninum
parasites and provide evidence that the extracellular pH regulates the
colonisation and phenotypic plasticity of N. caninum in mammalian cells.
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المؤتمر (2):
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عنوان المؤتمر:
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Society for General Microbiology Autumn
Conference 2012
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تاريخ الإنعقاد:
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3-5 September 2012
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مكان
الإنعقاد:
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Warwick, UK
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طبيعة المشاركة:
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Poster presentation
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عنوان المشاركة:
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Neospora caninum jumps species barrier
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ملخص المشاركة:
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In a previous study we showed for the
first time that the invertebrate locust is permissible to infection with the
apicomplexan protozoan parasite Neospora caninum. A viable strain of N.
caninum was recovered from experimentally infected locusts and maintained in
vitro via serial passages in cultured endothelial cells for up to 4 months
before being stored in liquid nitrogen.
Herein, we compared the genetic difference and chemical profile of N.
caninum strain isolated from brain of infected locust to original strain
normally maintained in tissue culture.
Locust-derived strain produced more productive infection compared to
the original strain. However,
PCR-sequencing analysis based on N. caninum species-specific primer pair
Np21plus–Np6plus which anneals into the Nc5 region revealed that both
parasite strains are identical. Also,
we used the micro-Raman spectroscopy technique and Principal Component
Analysis to identify the chemical structural differences between the two
strains and minor, non-significant differences were found between the 2
strains. These results indicate that
the current definition of the species barrier, which has been based on host
specificity, needs to be reassessed.
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المؤتمر (3):
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عنوان المؤتمر:
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Apicomplexa
in Farm Animals
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تاريخ الإنعقاد:
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31 Oct to 2 Nov 2013
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مكان
الإنعقاد:
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Kusadsi,
Turkey
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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Metabolic
profiling of culture medium of brain microvascular endothelial cells
challanged with neospora caninum
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ملخص المشاركة:
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This
study aimed to assess if the pathophysiological impact of N. caninum
infection on cultured endothelial cells could be explained by changes in the
nutritional needs of host cells during the course of intracellular (i.c.)
infection. Fluctuations of culture medium nutrients in response to growth of
N. caninum were determined using three approaches. First, concentrations of
several extracellular biochemical parameters of Brain Microvascular
Endothelial Cell (BMEC) culture medium were monitored in a time course as a
function of infection using a Randox RX Imola clinical chemistry analyser.
Second, extracellular metabolite changes in culture medium were monitored by
using Raman spectroscopy (RS). Third, a targeted LC-MS method was employed to
quantify important metabolite groups like amino acids, organic acids, sugar
phosphates, other phosphorylated metabolites, and nucleotides in the medium
of infected cell cultures and control cultures at 24 hr pi. Cell viability
was determined by LDH assay and demonstrated that N. caninum caused
cytotoxicity in endothelial cells in a dose-response manner. Beta
hydroxybutyrate, pyruvate, ATP, total protein (tp), non-esterified fatty
acids (NEFA), and triglycerides were significantly different in infected
cells compared with controls. RS and metabolite profiling using LC-MS/MS
revealed alteration in certain metabolites.
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المؤتمر (3):
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عنوان المؤتمر:
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Saudi scientific international
conference SSC2014
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تاريخ الإنعقاد:
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1-2 February
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مكان
الإنعقاد:
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Edinburgh UK
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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A novel
alternative model to study neuropathogenesis of cerebral neosporosis
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ملخص المشاركة:
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The
apicomplexan protozoan Neospora caninum circulates in nature between bovine
and canine hosts as well as other vertebrate species. Until the present
study, N. caninum was known to circulate between mammalian species only and
was thought to be thus limited by a “species barrier,” which might depend on
differences in the parasite virulence traits and the host animal physiology. Herein,
we demonstrate for the first time that a strain of Neospora caninum
(NC1-Liverpool) was able to infect the invertebrate desert locust (Schistocerca
gregaria) with induction of signs of illness in infected locusts. There was a
reduction of body weight in a dose-dependent manner. Also, infected locusts
showed slow mobility and sickness, which was dose-dependent. Control locusts
appeared normal. Live parasites were recovered in tissue cultured from brain
homogenates of infected locusts and were maintained successfully for up to 4
months before being stored in Liquid Nitrogen. These findings indicate that
locusts could be a useful model to test for neuropathogenic strains and
neuropathology and mechanisms of host specificity and tissue tropism. The possibility
that N. caninum can cross species barriers may have important public health
implications.
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