586 research outputs found
Novel bi- and trifunctional inhibitors of tumor-associated proteolytic systems
Serine proteases, cysteine proteases, and matrix metalloproteinases (MMPs) are involved in cancer cell invasion and metastasis. Recently, a recombinant bifunctional inhibitor (chCysuPA(19-31)) directed against cysteine proteases and the urokinasetype plasminogen activator (uPA)/plasmin serine protease system was generated by introducing the uPA receptor (uPAR)binding site of uPA into chicken cystatin (chCysWT). In the present study, we designed and recombinantly produced multifunctional inhibitors also targeting MMPs. The inhibitors comprise the Nterminal inhibitory domain of human TIMP-1 (tissue inhibitor of matrix metalloproteinase-1) or TIMP-3, fused to chCysuPA(19-31) or chCysWT. As demonstrated by various techniques, these fusion proteins effectively interfere with all three targeted protease systems. In in vitro Matrigel invasion assays, the addition of recombinant inhibitors strongly reduced invasion of ovarian cancer cells (OVMZ-6\#8). Additionally, OVMZ 6\#8 cells were stably transfected with expression plasmids encoding the various inhibitors. Synthesis and secretion of the inhibitors was verified by a newly developed ELISA, which selectively detects the recombinant proteins. Invasive capacity of inhibitorproducing cells was significantly reduced compared to vectortransfected control cells. Thus, these novel, compact, and smallsize inhibitors directed against up to three different tumorassociated proteolytic systems may represent promising agents for prevention of tumor cell migration and metastasis
Oil palm leaf fibre and its suitability for paper-based products
Due to the shortage of wood as origin materials for paper-based production, agro-residue materials have been explored in the quest of finding the best alternative fibre. Oil palm leaf (OPL) is one of agro-residue that has potential due to its comparable characteristics with wood fibre. Studies on chemical compositions, fibre morphology, and mechanical property of OPL have been carried out aiming to evaluate its potential as a substitute raw material for pulp and paper-based production. The chemical compositions were analysed according to the TAPPI standard, Kurscher-Hoffner and chlorite methods accordingly. The mechanical property (tensile, tearing and bursting strengths) were determined as described in TAPPI test methods. Fibre dimensions were determined using Franklin method and analysed under the optical microscope. The content of cellulose in the OPL is determined to be 43.8%. Although, this result is lower than wood fibre (53%), OPL has higher hemicellulose content (36.4%) than the wood fibre (27.5%). In addition, the lignin content (19.7%) of OPL is in the low range of those in wood resources (18 - 25%). These parameters are important components to produce good quality pulp and will provide high mechanical strength of the paper-based products. The measured fibre length of oil palm leaf (1.13 mm) is shorter than the wood fibre (1.90 mm). Meanwhile, the mechanical property of OPL showed lower indexes than wood resources, however, tear (1.80 mN.m2/g) and burst (0.95 kPa.m2/g) indexes of OPL are higher than other published and successful wood resources (Eucalyptus). Based on the analyses, the oil palm leaf is indeed a suitable alternative of raw material for pulp and paper-based industries
Detecting neutral hydrogen in emission at redshift z ~ 1
We use a large N-body simulation to examine the detectability of HI in
emission at redshift z ~ 1, and the constraints imposed by current observations
on the neutral hydrogen mass function of galaxies at this epoch. We consider
three different models for populating dark matter halos with HI, designed to
encompass uncertainties at this redshift. These models are consistent with
recent observations of the detection of HI in emission at z ~ 0.8. Whilst
detection of 21 cm emission from individual halos requires extremely long
integrations with existing radio interferometers, such as the Giant Meter Radio
Telescope (GMRT), we show that the stacked 21 cm signal from a large number of
halos can be easily detected. However, the stacking procedure requires accurate
redshifts of galaxies. We show that radio observations of the field of the
DEEP2 spectroscopic galaxy redshift survey should allow detection of the HI
mass function at the 5-12 sigma level in the mass range 10^(11.4) M_sun/h <
M_halo < 10^(12.5)M_sun/h, with a moderate amount of observation time. Assuming
a larger noise level that corresponds to an upper bound for the expected noise
for the GMRT, the detection significance for the HI mass function is still at
the 1.7-3 sigma level. We find that optically undetected satellite galaxies
enhance the HI emission profile of the parent halo, leading to broader wings as
well as a higher peak signal in the stacked profile of a large number of halos.
We show that it is in principle possible to discern the contribution of
undetected satellites to the total HI signal, even though cosmic variance
limitation make this challenging for some of our models.Comment: 14 pages, 9 figures, Submitted To MNRA
HI as a Probe of the Large Scale Structure in the Post-Reionization Universe
We model the distribution of neutral Hydrogen (HI hereafter) in the
post-reionization universe. This model uses gravity only N-Body simulations and
an ansatz to assign HI to dark matter haloes that is consistent with
observational constraints and theoretical models. We resolve the smallest
haloes that are likely to host HI in the simulations, care is also taken to
ensure that any errors due to the finite size of the simulation box are small.
We then compute the smoothed one point probability distribution function and
the power spectrum of fluctuations in HI. This is compared with other
predictions that have been made using different techniques. We highlight the
significantly high bias for the HI distribution at small scales. This aspect
has not been discussed before. We then discuss the prospects for detection with
the MWA, GMRT and the hypothetical MWA5000. The MWA5000 can detect visibility
correlations at large angular scales at all redshifts in the post-reionization
era. The GMRT can detect visibility correlations at lower redshifts,
specifically there is a strong case for a survey at z=1.3. We also discuss
prospects for direct detection of rare peaks in the HI distribution using the
GMRT. We show that direct detection should be possible with an integration time
that is comparable to, or even less than, the time required for a statistical
detection. Specifically, it is possible to make a statistical detection of the
HI distribution by measuring the visibility correlation, and, direct detection
of rare peaks in the HI distribution at z = 1.3 with the GMRT in less than 1000
hours of observations.Comment: 15 pages, 11 figures. Accepted for publication in the MNRAS. This is
a merged manuscript also containing material covered in 0908.385
A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud
We present a study of the magnetic field of the Small Magellanic Cloud (SMC),
carried out using radio Faraday rotation and optical starlight polarization
data. Consistent negative rotation measures (RMs) across the SMC indicate that
the line-of-sight magnetic field is directed uniformly away from us with a
strength 0.19 +/- 0.06 microGauss. Applying the Chandrasekhar-Fermi method to
starlight polarization data yields an ordered magnetic field in the plane of
the sky of strength 1.6 +/- 0.4 microGauss oriented at a position angle 4 +/-
12 degs, measured counter-clockwise from the great circle on the sky joining
the SMC to the Large Magellanic Cloud (LMC). We construct a three-dimensional
magnetic field model of the SMC, under the assumption that the RMs and
starlight polarization probe the same underlying large-scale field. The vector
defining the overall orientation of the SMC magnetic field shows a potential
alignment with the vector joining the center of the SMC to the center of the
LMC, suggesting the possibility of a "pan-Magellanic'' magnetic field. A
cosmic-ray driven dynamo is the most viable explanation of the observed field
geometry, but has difficulties accounting for the observed uni-directional
field lines. A study of Faraday rotation through the Magellanic Bridge is
needed to further test the pan-Magellanic field hypothesis.Comment: 28 pages, 6 figures, accepted for publication in Ap
Structural Parameters of Seven SMC Intermediate-Age and Old Star Clusters
We present structural parameters for the seven intermediate-age and old star
clusters NGC121, Lindsay 1, Kron 3, NGC339, NGC416, Lindsay 38, and NGC419 in
the Small Magellanic Cloud. We fit King profiles and Elson, Fall, and Freeman
profiles to both surface-brightness and star count data taken with the Advanced
Camera for Surveys aboard the Hubble Space Telescope. Clusters older than 1 Gyr
show a spread in cluster core radii that increases with age, while the youngest
clusters have relatively compact cores. No evidence for post core collapse
clusters was found. We find no correlation between core radius and distance
from the SMC center, although consistent with other studies of dwarf galaxies,
some relatively old and massive clusters have low densities. The oldest SMC
star cluster, the only globular NGC121, is the most elliptical object of the
studied clusters. No correlation is seen between ellipticity and distance from
the SMC center. The structures of these massive intermediate-age (1-8 Gyr) SMC
star clusters thus appear to primarily result from internal evolutionary
processes.Comment: 16 pages, 13 figure
Increases of Antibiotic Resistance in Excessive Use of Antibiotics in Smallholder Dairy Farms in Northern Thailand
Antibiotic resistance patterns of bacterial isolates from both quarter teat-tip swabs and their quarter milk samples were evaluated in smallholder dairy farms in northern Thailand with excessive use of antibiotics (HIGH) compared with normal use (NORM). Results from teat-tip swab samples showed that the percentage of Bacillus spp. resistance to overall antibiotics was significantly lower in the NORM group than that of the HIGH group, whereas, the resistance percentage of coagulase-negative staphylococci in the NORM group was higher than that of the HIGH one. The overall mastitis-causing bacteria isolated from milk samples were environmental streptococci (13.8%), coagulase-negative staphylococci (9.9%), Staphylococcus aureus (5.4%), and Corynebacterium bovis (4.5%). Both staphylococci and streptococci had significantly higher percentages of resistance to cloxacillin and oxacillin in the HIGH group when compared to the NORM one. An occurrence of vancomycin-resistant bacteria was also observed in the HIGH group. In conclusion, the smallholder dairy farms with excessive use of antibiotics had a higher probability of antibiotic-resistant pattern than the farms with normal use
Biophysical Characteristics of Tropical Peatland
Based on Jenny’s equation (1941) of soil forming factors i.e. S = f(C, R, B, P, T)
with the five soil forming factors, the biotic (B) factor of soil formation is the most
multifaceted among them. The biotic factor can be grouped into vegetation, microorganisms,
animals and human activities. Vegetation is considered to be the most
important facet of the biotic factor. Efforts to explain soil characteristics in terms of the
influence of biota are best facilitated by biosequence studies. These studies contain a
series of soil profiles across which the biotic soil forming factor varies while other soil
forming factors remain constant. Within the context of a biosequence, the effect of
changing biotic factor upon any soil property can be assessed quantitatively. For
tropical peat, vegetation is both a biotic and parent material for soil forming factors.
The elemental composition of soil differs from that of geologic materials in its
striking enrichment of carbon and nitrogen compounds relative to most rocks. The
organic compounds of the plants are the ultimate sources of this C and N. Plants
contribute organic compounds to the soil in a variety of ways, including the senescence
or necrosis of tissue, exudation or respiration from the roots, and the liberation of
reproductive tissues such as pollen, seeds and fruits. Thus plants that live on the soil
both influence soil properties and are influenced by soil properties. And these have been
observed on the tropical peat of Sarawak whereby there is an existence of biosequence
in each peat basin i.e. different forest types on a peat basin means different soil
characteristics caused by different biophysical characteristics of the peat. This
biosequence in the peat swamps of Peninsular Malaysia is less highly developed than
those in Sarawak (Anderson, 1964). Therefore the objective of this paper is to describe
the physical characteristics of the peat in relation to the forest types and its implication to
agriculture development especially oil palm cultivation on tropical peat
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