439 research outputs found
Investigations of the infection by schistosome parasites of their molluscan intermediate hosts
The respiratory pigments
and
the
amino
acid
composition of planorbid
snails
which
act
as
intermediate hosts for
human
schistosomes
were
compared
with those of insusceptible snail
species.
The absorption spectra
of
haemoglobins from
different snail species were similar
to
one
another
and
closely related to those of mammalian
haemoglobins.
The occasional appearance
of
additional
absorption
bands
suggested that substances
other
than the
pigment
protein
appear infrequently in snail
blood.
Electrophoresis showed
that, in
general,
the
respiratory pigment was
the
only
protein
present
in the
blood. The mobility
of
haemoglobin
and
haemocyanin
pigments was not affected by
change
in
pH, and
the
rates
of movement of haemoglobins from twelve
different
snail
species were the same.
Other
proteins
occurred
occasionally
in the blood of most species examined,
and
these
additional
fractions seemed to form a
common pattern
in four
species.
The factors determining their
appearance
were
investigated.
No qualitative differences
were
observed
in the
amino acid content of haemoglobins from
different snails,
but quantitative differences were
demonstrated.
The free amino acids of snail
blood
were
in low
concentration but were qualitatively similar
in three
snail species, which also contained
similar
bound
and
free amino acids in the digestive
glands
and
ovotestes.
Australorbis glabratus,
however,
differed from
Planorbarius corneus and Lymnaea stagnalis
since
free
methionine was found in its
anterior
tissues.
The
methionine was not present
in
glabratus
snails
infected
with Schistosoma mansoni, and
they
contained
lower
concentrations of free amino
acids
than
uninfected
snails.
It was shown that methionine was
one
of
the
seventeen
amino acids identified in the
protein
of
S. mansoni cercariae
Artesunate reduces but does not prevent posttreatment transmission of Plasmodium falciparum to Anopheles gambiae.
Combination therapy that includes artemisinin derivatives cures most falciparum malaria infections. Lowering transmission by reducing gametocyte infectivity would be an additional benefit. To examine the effect of such therapy on transmission, Gambian children with Plasmodium falciparum malaria were treated with standard regimens of chloroquine or pyrimethamine-sulfadoxine alone or in combination with 1 or 3 doses of artesunate. The infectivity to mosquitoes of gametocytes in peripheral blood was determined 4 or 7 days after treatment. Infection of mosquitoes was observed in all treatment groups and was positively associated with gametocyte density. The probability of transmission was lowest in those who received pyrimethamine-sulfadoxine and 3 doses of artesunate, and it was 8-fold higher in the group that received pyrimethamine-sulfadoxine alone. Artesunate reduced posttreatment infectivity dramatically but did not abolish it completely. The study raises questions about any policy to use pyrimethamine-sulfadoxine alone as the first-line treatment for malaria
Linear magnetic resonance imaging measurements of the hippocampal formation differ in young versus old dogs
Age-related hippocampal formation (HF) atrophy has been documented on MRI studies using volumetric analysis and visual rating scales.This retrospective cross-sectional study aimed to compare linear MRI measurements of the HF between young (1–3 years) and old (>10 years) non-brachycephalic dogs, with normal brain anatomy and cerebrospinal fluid (CSF) analysis. Right and left hippocampal formation height (HFH), height of the brain (HB) and mean HFH/HB ratio were measured by two observers on a transverse T2 fluid-attenuated inversion recovery sequence containing rostral colliculi and mesencephalic aqueduct.119 MRI studies were enrolled: 75 young and 44 old dogs. Left and right HFH were greater (p<0.0001) in young, while HB was greater in old dogs (p=0.024). Mean HFH/HB ratio was 15.66 per cent and 18.30 per cent in old and young dogs (p<0.0001). No differences were found comparing measurements between epileptic and non-epileptic dogs.Old dogs have a greater HB; this may represent the different study populations or a statistical phenomenon. Ageing affects HF linear measurements. A reduction of mean HFH/HB ratio between 18.30 per cent and 15.66 per cent should be considered a physiological age-related process of the canine lifespan. The use of mean HFH/HB ratio could be considered for quantifying brain atrophy in elderly dogs
SMS for Life: a pilot project to improve anti-malarial drug supply management in rural Tanzania using standard technology
Background:
Maintaining adequate supplies of anti-malarial medicines at the health facility level in rural sub-Saharan Africa is a major barrier to effective management of the disease. Lack of visibility of anti-malarial stock levels at the health facility level is an important contributor to this problem.
Methods:
A 21-week pilot study, 'SMS for Life', was undertaken during 2009-2010 in three districts of rural Tanzania, involving 129 health facilities. Undertaken through a collaborative partnership of public and private institutions, SMS for Life used mobile telephones, SMS messages and electronic mapping technology to facilitate provision of comprehensive and accurate stock counts from all health facilities to each district management team on a weekly basis. The system covered stocks of the four different dosage packs of artemether-lumefantrine (AL) and quinine injectable.
Results:
Stock count data was provided in 95% of cases, on average. A high response rate (≥ 93%) was maintained throughout the pilot. The error rate for composition of SMS responses averaged 7.5% throughout the study; almost all errors were corrected and messages re-sent. Data accuracy, based on surveillance visits to health facilities, was 94%. District stock reports were accessed on average once a day. The proportion of health facilities with no stock of one or more anti-malarial medicine (i.e. any of the four dosages of AL or quinine injectable) fell from 78% at week 1 to 26% at week 21. In Lindi Rural district, stock-outs were eliminated by week 8 with virtually no stock-outs thereafter. During the study, AL stocks increased by 64% and quinine stock increased 36% across the three districts.
Conclusions:
The SMS for Life pilot provided visibility of anti-malarial stock levels to support more efficient stock management using simple and widely available SMS technology, via a public-private partnership model that worked highly effectively. The SMS for Life system has the potential to alleviate restricted availability of anti-malarial drugs or other medicines in rural or under-resourced areas
Bidirectional lipid droplet velocities are controlled by differential binding strengths of HCV Core DII protein
Host cell lipid droplets (LD) are essential in the hepatitis C virus (HCV) life cycle and are targeted by the viral capsid core protein. Core-coated LDs accumulate in the perinuclear region and facilitate viral particle assembly, but it is unclear how mobility of these LDs is directed by core. Herein we used two-photon fluorescence, differential interference contrast imaging, and coherent anti-Stokes Raman scattering microscopies, to reveal novel core-mediated changes to LD dynamics. Expression of core protein’s lipid binding domain II (DII-core) induced slower LD speeds, but did not affect directionality of movement on microtubules. Modulating the LD binding strength of DII-core further impacted LD mobility, revealing the temporal effects of LD-bound DII-core. These results for DII-core coated LDs support a model for core-mediated LD localization that involves core slowing down the rate of movement of LDs until localization at the perinuclear region is accomplished where LD movement ceases. The guided localization of LDs by HCV core protein not only is essential to the viral life cycle but also poses an interesting target for the development of antiviral strategies against HCV
Little change in the sizes of the most massive galaxies since z = 1
Recent reports suggest that elliptical galaxies have increased their size
dramatically over the last ~8 Gyr. This result points to a major re-think of
the processes dominating the latetime evolution of galaxies. In this paper we
present the first estimates for the scale sizes of brightest cluster galaxies
(BCGs) in the redshift range 0.8 < z < 1.3 from an analysis of deep Hubble
Space Telescope imaging, comparing to a well matched local sample taken from
the Local Cluster Substructure Survey at z ~ 0.2. For a small sample of 5 high
redshift BCGs we measure half-light radii ranging from 14 - 53 kpc using de
Vaucuoleurs profile fits, with an average determined from stacking of 32.1 \pm
2.5 kpc compared to a value 43.2 \pm 1.0 kpc for the low redshift comparison
sample. This implies that the scale sizes of BCGs at z = 1 are ~ 30% smaller
than at z = 0.25. Analyses comparing either Sersic or Petrosian radii also
indicate little or no evolution between the two samples. The detection of only
modest evolution at most out to z = 1 argues against BCGs having undergone the
large increase in size reported for massive galaxies since z = 2 and in fact
the scale-size evolution of BCGs appears closer to that reported for radio
galaxies over a similar epoch. We conclude that this lack of size evolution,
particularly when coupled with recent results on the lack of BCG stellar mass
evolution, demonstrates that major merging is not an important process in the
late time evolution of these systems. The homogeneity and maturity of BCGs at z
= 1 continues to challenge galaxy evolution models.Comment: Accepted for publication in MNRA
Genome-to-genome analysis highlights the effect of the human innate and adaptive immune systems on the hepatitis C virus
Outcomes of hepatitis C virus (HCV) infection and treatment depend on viral and host genetic factors. Here we use human genome-wide genotyping arrays and new whole-genome HCV viral sequencing technologies to perform a systematic genome-to-genome study of 542 individuals who were chronically infected with HCV, predominantly genotype 3. We show that both alleles of genes encoding human leukocyte antigen molecules and genes encoding components of the interferon lambda innate immune system drive viral polymorphism. Additionally, we show that IFNL4 genotypes determine HCV viral load through a mechanism dependent on a specific amino acid residue in the HCV NS5A protein. These findings highlight the interplay between the innate immune system and the viral genome in HCV control
The Hawk-I UDS and GOODS Survey (HUGS): Survey design and deep K-band number counts
We present the results of a new, ultra-deep, near-infrared imaging survey
executed with the Hawk-I imager at the ESO VLT, of which we make all the data
public. This survey, named HUGS (Hawk-I UDS and GOODS Survey), provides deep,
high-quality imaging in the K and Y bands over the CANDELS UDS and GOODS-South
fields. We describe here the survey strategy, the data reduction process, and
the data quality. HUGS delivers the deepest and highest quality K-band images
ever collected over areas of cosmological interest, and ideally complements the
CANDELS data set in terms of image quality and depth. The seeing is exceptional
and homogeneous, confined to the range 0.38"-0.43". In the deepest region of
the GOODS-S field, (which includes most of the HUDF) the K-band exposure time
exceeds 80 hours of integration, yielding a 1-sigma magnitude limit of ~28.0
mag/sqarcsec. In the UDS field the survey matches the shallower depth of the
CANDELS images reaching a 1-sigma limit per sq.arcsec of ~27.3mag in the K band
and ~28.3mag in the Y-band, We show that the HUGS observations are well matched
to the depth of the CANDELS WFC3/IR data, since the majority of even the
faintest galaxies detected in the CANDELS H-band images are also detected in
HUGS. We present the K-band galaxy number counts produced by combining the HUGS
data from the two fields. We show that the slope of the number counts depends
sensitively on the assumed distribution of galaxy sizes, with potential impact
on the estimated extra-galactic background light (abridged).Comment: Accepted for publication on Astronomy and Astrophysic
Physical properties of z>4 submillimeter galaxies in the COSMOS field
We study the physical properties of a sample of 6 SMGs in the COSMOS field, spectroscopically confirmed to lie at z>4. We use new GMRT 325 MHz and 3 GHz JVLA data to probe the rest-frame 1.4 GHz emission at z=4, and to estimate the sizes of the star-forming (SF) regions of these sources, resp. Combining our size estimates with those available in the literature for AzTEC1 and AzTEC3 we infer a median radio-emitting size for our z>4 SMGs of (0.63"+/-0.12")x(0.35"+/-0.05") or 4.1x2.3 kpc^2 (major times minor axis; assuming z=4.5) or lower if we take the two marginally resolved SMGs as unresolved. This is consistent with the sizes of SF regions in lower-redshift SMGs, and local normal galaxies, yet higher than the sizes of SF regions of local ULIRGs. Our SMG sample consists of a fair mix of compact and more clumpy systems with multiple, perhaps merging, components. With an average formation time of ~280 Myr, derived through modeling of the UV-IR SEDs, the studied SMGs are young systems. The average stellar mass, dust temperature, and IR luminosity we derive are M*~1.4x10^11 M_sun, T_dust~43 K, and L_IR~1.3x10^13L_sun, resp. The average L_IR is up to an order of magnitude higher than for SMGs at lower redshifts. Our SMGs follow the correlation between dust temperature and IR luminosity as derived for Herschel-selected 0.1=1.95+/-0.26 for our sample, compared to q~2.6 for IR luminous galaxies at z4 SMGs put them at the high end of the L_IR-T_dust distribution of SMGs, and that our SMGs form a morphologically heterogeneous sample. Thus, further in-depth analyses of large, statistical samples of high-redshift SMGs are needed to fully understand their role in galaxy formation and evolution
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