98 research outputs found
Extensive genomic diversity and selective conservation of virulence determinants in enterohemorrhagic Escherichia coli strains of O157 and non O157 serotypes
Background: Enterohemorrhagic Escherichia coli (EHEC) O157 causes severe food-borne illness in humans. The chromosome of O157 consists of 4.1 Mb backbone sequences shared by benign E. coli K-12, and 1.4 Mb O157-specific sequences encoding many virulence determinants, such as Shiga toxin genes (stx genes) and the locus of enterocyte effacement (LEE). Non-O157 EHECs belonging to distinct clonal lineages from O157 also cause similar illness in humans. According to the "parallel" evolution model, they have independently acquired the major virulence determinants, the stx genes and LEE. However, the genomic differences between O157 and non-O157 EHECs have not yet been systematically analyzed. Results: Using microarray and whole genome PCR scanning analyses, we performed a whole genome comparison of 20 EHEC strains of O26, O111, and O103 serotypes with O157. In non-O157 EHEC strains, although genome sizes were similar with or rather larger than O157 and the backbone regions were well conserved, O157-specific regions were very poorly conserved. Around only 20% of the O157- specific genes were fully conserved in each non-O157 serotype. However, the non-O157 EHECs contained a significant number of virulence genes that are found on prophages and plasmids in O157, and also multiple prophages similar to, but significantly divergent from, those in O157. Conclusion: Although O157 and non-O157 EHECs have independently acquired a huge amount of serotype- or strain-specific genes by lateral gene transfer, they share an unexpectedly large number of virulence genes. Independent infections of similar but distinct bacteriophages carrying these virulence determinants are deeply involved in the evolution of O157 and non-O157 EHECs
WIDGET: System Performance and GRB Prompt Optical Observations
The WIDeField telescope for Gamma-ray burst Early Timing (WIDGET) is used for
a fully automated, ultra-wide-field survey aimed at detecting the prompt
optical emission associated with Gamma-ray Bursts (GRBs). WIDGET surveys the
HETE-2 and Swift/BAT pointing directions covering a total field of view of 62
degree x 62 degree every 10 secounds using an unfiltered system. This
monitoring survey allows exploration of the optical emission before the
gamma-ray trigger. The unfiltered magnitude is well converted to the SDSS r'
system at a 0.1 mag level. Since 2004, WIDGET has made a total of ten
simultaneous and one pre-trigger GRB observations. The efficiency of
synchronized observation with HETE-2 is four times better than that of Swift.
There has been no bright optical emission similar to that from GRB 080319B. The
statistical analysis implies that GRB080319B is a rare event. This paper
summarizes the design and operation of the WIDGET system and the simultaneous
GRB observations obtained with this instrument.Comment: 19 pages, 11 figures, Accepted to appear in PAS
Prognostic significance of Ki-67 and p53 antigen expression in carcinomas of bile duct and gallbladder
Ki-67 and p53 protein expression was evaluated immunohistochemically in 32 patients with intrahepatic, extrahepatic bile duct and gallbladder carcinomas, who underwent surgery at First Department of Surgery, The University of Tokushima School of Medicine. p53 expression was found more in the well differentiated group than poorly differentiated group (p=0.007). MIB1 labelling index (MIB1 LI) was higher in EHC than in GBC (p=0.0061). MIB1 LI (T), (MIB1 LI in tumor) was higher in cases with lymph node metastasis than in those without lymph node metastasis (p=0.0189). Moreover, MIB1LI (L) (MIB1 LI in metastasized lymph node) was higher in poorly differentiated than in well differentiated carcinoma (p=0.0404). Prognostically, patients with high MIB1 LI (T) (>56.93) had a worse prognosis after surgery than those with low MIB1 LI (T) (p<0.05). There was no association between p53 positive tumors and MIB1 expression. These results suggest that cancer cell proliferative activity was markedly increased in cases with EHC compared to those with GBC and the poorly differentiated and lymph node metastasis group. MIB1 LI in tumor was found to be a good prognostic indicator whereas there was no association of p53 positive tumor with MIB1 expression and prognosis of the patients
Ventralex オ モチイタ フクヘキ ハンコン ヘルニア シュウフクジュツ ノ 1 レイ
A 78-year-old woman underwent cystectomy of left ovary 1 year ago. She came to our hospital with the chief complaint of bulging of the abdominal scar before 2 months. The bulging of 3×3 cm was recognized in the operation scar in a standing position. CT scan of the abdomen revealed incisional hernia in upper part of operation wound. The hernia orifice was 2.5×2.5 cm. A radical operation was therefore performed. Under local anesthesia, Ventralex was fixed by insertion, and the hernia was repaired. The adhesion between the omentum and the caudal part of operation scar was dissected. In the condition patch was inserted and made to adhere to abdominal wall, strap was fixed in the rectus sheath. The postoperative course was good. Repair of incisional hernia using Ventralex seemed to be useful operative method, which could enforce the tension free operation in the minimum invasion
Spectral Properties of Prompt Emission of Four Short Gamma-Ray Bursts Observed by the Suzaku-WAM and the Konus-Wind
We have performed a joint analysis of prompt emission from four bright short
gamma-ray bursts (GRBs) with the Suzaku-WAM and the Konus-Wind experiments.
This joint analysis allows us to investigate the spectral properties of
short-duration bursts over a wider energy band with a higher accuracy. We find
that these bursts have a high E, around 1 MeV and have a harder
power-law component than that of long GRBs. However, we can not determine
whether these spectra follow the cut-off power-law model or the Band model. We
also investigated the spectral lag, hardness ratio, inferred isotropic
radiation energy and existence of a soft emission hump, in order to classify
them into short or long GRBs using several criteria, in addition to the burst
duration. We find that all criteria, except for the existence of the soft hump,
support the fact that our four GRB samples are correctly classified as
belonging to the short class. In addition, our broad-band analysis revealed
that there is no evidence of GRBs with a very large hardness ratio, as seen in
the BATSE short GRB sample, and that the spectral lag of our four short GRBs is
consistent with zero, even in the MeV energy band, unlike long GRBs. Although
our short GRB samples are still limited, these results suggest that the
spectral hardness of short GRBs might not differ significantly from that of
long GRBs, and also that the spectral lag at high energies could be a strong
criterion for burst classification.Comment: 23 pages, 6 figures, accepted for Publications of the Astronomical
Society of Japa
A multi band study of the optically dark GRB 051028
Observations were made of the optical afterglow of GRB 051028 with the Lulin
observatory's 1.0 m telescope and the WIDGET robotic telescope system. R band
photometric data points were obtained on 2005 October 28 (UT), or 0.095-0.180
days after the burst. There is a possible plateau in the optical light curve
around 0.1 days after the burst; the light curve resembles optically bright
afterglows (e.g. GRB 041006, GRB 050319, GRB060605) in shape of the light curve
but not in brightness. The brightness of the GRB 051028 afterglow is 3
magnitudes fainter than that of one of the dark events, GRB 020124. Optically
dark GRBs have been attributed to dust extinction within the host galaxy or
high redshift. However, the spectrum analysis of the X-rays implies that there
is no significant absorption by the host galaxy. Furthermore, according to the
model theoretical calculation of the Ly absorption to find the limit of
GRB 051028's redshift, the expected band absorption is not high enough to
explain the darkness of the afterglow. While the present results disfavor
either the high-redshift hypothesis or the high extinction scenario for
optically dark bursts, they are consistent with the possibility that the
brightness of the optical afterglow, intrinsically dark.Comment: 5page, 5 figures, 1 table, accepted for publication in PASJ Letter.
PASJ styl
Spectral evolution of GRB 060904A observed with Swift and Suzaku -- Possibility of Inefficient Electron Acceleration
We observed an X-ray afterglow of GRB 060904A with the Swift and Suzaku
satellites. We found rapid spectral softening during both the prompt tail phase
and the decline phase of an X-ray flare in the BAT and XRT data. The observed
spectra were fit by power-law photon indices which rapidly changed from to within a few hundred
seconds in the prompt tail. This is one of the steepest X-ray spectra ever
observed, making it quite difficult to explain by simple electron acceleration
and synchrotron radiation. Then, we applied an alternative spectral fitting
using a broken power-law with exponential cutoff (BPEC) model. It is valid to
consider the situation that the cutoff energy is equivalent to the synchrotron
frequency of the maximum energy electrons in their energy distribution. Since
the spectral cutoff appears in the soft X-ray band, we conclude the electron
acceleration has been inefficient in the internal shocks of GRB 060904A. These
cutoff spectra suddenly disappeared at the transition time from the prompt tail
phase to the shallow decay one. After that, typical afterglow spectra with the
photon indices of 2.0 are continuously and preciously monitored by both XRT and
Suzaku/XIS up to 1 day since the burst trigger time. We could successfully
trace the temporal history of two characteristic break energies (peak energy
and cutoff energy) and they show the time dependence of while the following afterglow spectra are quite stable. This fact
indicates that the emitting material of prompt tail is due to completely
different dynamics from the shallow decay component. Therefore we conclude the
emission sites of two distinct phenomena obviously differ from each other.Comment: 19 pages, 9 figures, accepted for publication in PASJ (Suzaku 2nd
Special Issue
PETREL for Astrophysics and Carbon Business
A multi-purpose 50kg class microsatellite hosting astrophysical mission and earth remote sensing, PETREL , will be launched in 2023. In the night side, PETREL observe the ultra-violet sky with a wide-field telescope covering 50 deg^2 for surveying transient objects related to supernovae, tidal disruption events, and gravitational wave events. Our UV telescope can detect the early phase UV emission from a neutron star merger occurred within 150 Mpc. In addition to the satellite observation, PETREL sends a detection alert including the coordinate and brightness of the UV transient to the ground via the real time communication network within several minutes after detection to conduct follow-up observations with the collaborating ground based observatories over the world. In the day side, PETREL observes the surface of the earth by using the tunable multi-spectral cameras and a ultra-compact hyperspectral camera. Our potential targets are the tropical forests (Green Carbon) and coastal zones (Blue Carbon) in the tropical areas to evaluating the global biological carbon strages. For this purpose PETREL will conduct multiple scale mapping collaborating with drones and small aircraft not only satellite. The obtained data will be used for academical research and for business applications. The technical difficulty of this satellite is that carries out multi-purpose with different requirements, such as astronomical observations which requires a quite high attitude stability and the earth observations requiring a high pointing accuracy, with limited resources. If it is possible, a novel small satellite system or a business style can be realized that can share the payload with academia and industry. PETREL has been adopted as Innovative Satellite Technology Demonstration Program No.3 led by JAXA, and development is underway with the aim of launching in FY2023
- …