X-ray Measurements of the Particle Acceleration Properties at Inward Shocks in Cassiopeia A

We present new evidence that the bright non-thermal X-ray emission features in the interior of the Cassiopeia A supernova remnant (SNR) are caused by inward moving shocks based on Chandra and NuSTAR observations. Several bright inward-moving filaments were identified using monitoring data taken by Chandra in 2000-2014. These inward-moving shock locations are nearly coincident with hard X-ray (15-40 keV) hot spots seen by NuSTAR. From proper motion measurements, the transverse velocities were estimated to be in the range $\sim$2,100-3,800 km s$^{-1}$ for a distance of 3.4 kpc. The shock velocities in the frame of the expanding ejecta reach values of $\sim$5,100-8,700 km s$^{-1}$, slightly higher than the typical speed of the forward shock. Additionally, we find flux variations (both increasing and decreasing) on timescales of a few years in some of the inward-moving shock filaments. The rapid variability timescales are consistent with an amplified magnetic field of $B \sim$ 0.5-1 mG. The high speed and low photon cut-off energy of the inward-moving shocks are shown to imply a particle diffusion coefficient that departs from the Bohm regime ($k_0 = D_0/D_{\rm 0,Bohm} \sim$ 3-8) for the few simple physical configurations we consider in this study. The maximum electron energy at these shocks is estimated to be $\sim$8-11 TeV, smaller than the values of $\sim$15-34 TeV inferred for the forward shock. Cassiopeia A is dynamically too young for its reverse shock to appear to be moving inward in the observer frame. We propose instead that the inward-moving shocks are a consequence of the forward shock encountering a density jump of $\gtrsim$ 5-8 in the surrounding material.Comment: 16 pages, 8 figures, accepted for publication in Ap

Preparation of bioactive and antibacterial PMMA-based bone cement by modification with quaternary ammonium and alkoxysilane

Bone cement based on poly(methyl methacrylate) (PMMA) powder and methyl methacrylate (MMA) liquid is a very popular biomaterial used for the fixation of artificial joints. However, there is a risk of this cement loosening from bone because of a lack of bone-bonding bioactivity. Apatite formation in the body environment is a prerequisite for cement bioactivity. Additionally, suppression of infection during implantation is required for bone cements to be successfully introduced into the human body. In this study, we modified PMMA cement with γ-methacryloxypropyltrimetoxysilane and calcium acetate to introduce bioactive properties and 2-(tert-butylamino)ethyl methacrylate (TBAEMA) to provide antibacterial properties. The long-term antibacterial activity is attributed to the copolymerization of TBAEMA and MMA. As the TBAEMA content increased, the setting time increased and the compressive strength decreased. After soaking in simulated body fluid, an apatite layer was detected within 7 days, irrespective of the TBAEMA content. The cement showed better antibacterial activity against Gram-negative E. Coli than Gram-positive bacteria; however, of the Gram-positive bacteria investigated, B. subtilis was more susceptible than S. aureus

Effect of Calcium Acetate Content on Apatite-Forming Ability and Mechanical Property of PMMA Bone Cement Modified with Quaternary Ammonium

Polymethyl methacrylate (PMMA)-based bone cement is a popular biomaterial used for fixation of artificial joints. A next-generation bone cement having bone-bonding ability, i.e., bioactivity and antibacterial property is desired. We previously revealed that PMMA cement added with 2-(tert-butylamino)ethyl methacrylate, γ-methacryloxypropyltrimethoxysilane and calcium acetate showed in vitro bioactivity and antibacterial activity. This cement contains calcium acetate at 20% of the powder component. Lower content of the calcium acetate is preferable, because the release of a lot of calcium salt may degrade mechanical properties in the body environment. In the present study, we investigate the effects of calcium acetate content on the setting property and mechanical strength of the cement and apatite formation in simulated body fluid (SBF). The setting time increased and the compressive strength decreased with an increase in calcium acetate content. Although the compressive strength decreased after immersion in SBF for 7 d, all the cements still satisfied the requirements of ISO5833. Apatite was formed in SBF within 7 d on the samples where the calcium acetate content was 5% or more. Therefore, it was found that PMMA cement having antibacterial properties and bioactivity can be obtained even if the amount of the calcium acetate is reduced to 5%

Structural effects of phosphate groups on apatite formation in a copolymer modified with Ca2+ in a simulated body fluid

Organic–inorganic composites are novel bone substitutes that can ameliorate the mismatch of Young\u27s moduli between natural bone and implanted ceramics. Phosphate groups contribute to the formation of apatite in a simulated body fluid (SBF) and the adhesion of osteoblast-like cells. Therefore, modification of a polymer with these functional groups is expected to enhance the ability of the organic–inorganic composite to bond with bone. Two phosphate groups have been used, phosphonic acid (–C–PO3H2) and phosphoric acid (–O–PO3H2). However, the effects of structural differences between these phosphate groups have not been clarified. In this study, the apatite formation of copolymers modified with Ca2+ and either –C–PO3H2 or –O–PO3H2 was examined. The mechanism of apatite formation is discussed based on analytical and computational approaches. The copolymers containing –O–PO3H2, but not those containing –C–PO3H2, formed apatite in the SBF, although both released similar amounts of Ca2+ into the SBF. Adsorption of HPO42− from –O–PO3H2 in the SBF following Ca2+ adsorption was confirmed by zeta-potential measurement and X-ray photoelectron spectroscopy. The measurement of the complex formation constant revealed that the –O–PO32−⋯Ca2+ complex was thermodynamically unstable enough to convert into CaHPO4, which was not the case with –C–PO32−⋯Ca2+. The formation of CaHPO4-based clusters was found to be a key factor for apatite nucleation. In conclusion, this study revealed that modification with –O–PO3H2 was more effective for enhancing apatite formation compared with –C–PO3H2

Propagation of Asian isolates of canine distemper virus (CDV) in hamster cell lines

<p>Abstract</p> <p>Backgrounds</p> <p>The aim of this study was to confirm the propagation of various canine distemper viruses (CDV) in hamster cell lines of HmLu and BHK, since only a little is known about the possibility of propagation of CDV in rodent cells irrespective of their epidemiological importance.</p> <p>Methods</p> <p>The growth of CDV in hamster cell lines was monitored by titration using Vero.dogSLAMtag (Vero-DST) cells that had been proven to be susceptible to almost all field isolates of CDV, with the preparations of cell-free and cell-associated virus from the cultures infected with recent Asian isolates of CDV (13 strains) and by observing the development of cytopathic effect (CPE) in infected cultures of hamster cell lines.</p> <p>Results</p> <p>Eleven of 13 strains grew in HmLu cells, and 12 of 13 strains grew in BHK cells with apparent CPE of cell fusion in the late stage of infection. Two strains and a strain of Asia 1 group could not grow in HmLu cells and BHK cells, respectively.</p> <p>Conclusion</p> <p>The present study demonstrates at the first time that hamster cell lines can propagate the majority of Asian field isolates of CDV. The usage of two hamster cell lines suggested to be useful to characterize the field isolates biologically.</p

Examining Neutrino-Matter Interactions in the Cassiopeia A Supernova

Neutrino interactions with stellar material are widely believed to be fundamental to the explosion of massive stars. However, this important process has remained difficult to confirm observationally. We propose a new method to verify it using X-ray observations of the supernova remnant Cassiopeia A. The elemental composition in its Fe-rich ejecta that could have been produced at the innermost region of the supernova, where neutrinos are expected to interact, allows us to examine the presence of neutrino interactions. Here we demonstrate that the amount of Mn produced without neutrino nucleosynthesis processes (i.e., the $\nu$- and $\nu$p-process) is too small to explain the Mn/Fe mass ratio we measure (0.14--0.67\%). This result supports the operation of significant neutrino interactions in the Cassiopeia A supernova. If the observed Mn/Fe mass ratio purely reflects the production at the innermost region of the supernova, this would be the first robust confirmation of neutrino-matter interactions in an individual supernova. We further show that the Mn/Fe mass ratio has the potential to constrain supernova neutrino parameters (i.e., total neutrino luminosity, neutrino temperature). Future spatially-resolved, high-resolution X-ray spectroscopy will allow us to investigate the details of neutrino-supernova astrophysics through its signatures in elemental composition not only in Cassiopeia A but also in other remnants.Comment: 17 pages, 10 figures. Accepted for publication in Ap

Laparoscopic Resection of a Primary Retroperitoneal Mucinous Cystadenoma

Primary retroperitoneal mucinous cystadenoma (PRMC) is a rare cystic lesion occurring mostly in women with a histological analogy to ovarian mucinous cystadenoma. The tumor is difficult to detect during early stages because it causes symptoms only when it grows large enough to be palpable or to displace the adjacent internal organs. The primary treatment is resection, but the optimal surgical approach remains poorly known. We report the case of a 41-year-old woman who complained of right-sided intermittent abdominal pain. Imaging studies revealed a right retroperitoneal smooth cystic lesion (50 mm) without invasive features. Laparoscopic resection was then performed. During surgery, a right retroperitoneal mass with no connection to neighboring tissues was found. The tumor, wrapped by retroperitoneal fat tissue, was resected and removed from the body without exposure. Furthermore, histopathological findings indicated PRMC. The patient was discharged without any complications and observed to have no recurrence 6 months postoperatively

Laparoscopic Resection of an Abdominal Wall Metastasis 5 Years after Primary Colorectal Cancer Resection

We report the case of a 65-year-old male with a metachronous abdominal wall metastasis secondary to colorectal cancer. The patient had presented 5 years ago to another facility with a perforated sigmoid colon cancer (pT4a[SE], N0, M0, pStage II), rectal cancer (T2[MP], N0, M0, pStage I), and Fournier gangrene. He had then undergone sigmoidectomy and rectal resection along with S-1 adjuvant chemotherapy. No relapse was observed thereafter. However, currently, 5 years after initial surgery, the patient noticed a palpable mass in the left lower abdomen and was referred to our hospital for further assessment and treatment. Percutaneous echo-guided needle biopsy of the tumor revealed an adenocarcinoma tissue. Following 6 courses of FOLFOX plus cetuximab chemotherapy, laparoscopic resection for abdominal wall metastasis was successfully performed. The resected tissue was pathologically characterized as adenocarcinoma, which was compatible with the recurrence of the primary colorectal carcinoma resected 5 years ago. The abdominal wall metastasis was attributed to the cancer cell implantation secondary to the perforated sigmoid colon cancer treated 5 years ago

Late Cutaneous Metastasis Originating from Gastric Cancer with Synchronous Metastasis

An 89-year-old man was diagnosed with late cutaneous metastasis in the right axilla 6 years after undergoing a surgery for gastric cancer with synchronous cutaneous metastasis in the same site. The patient became aware of small reddish nodules in the right axilla, and computed tomography imaging showed an irregular thickening of the right axillary skin. No other sign of recurrence was observed. By en-bloc resection, the nodules were diagnosed as late cutaneous metastasis from gastric cancer. The patient received no additional postoperative chemo- or radiotherapy and was only carefully observed. Cutaneous metastases from gastric cancer have a high recurrence rate even if total resection with no residual cancer is achieved. Therefore, meticulous follow-up, including routine visual inspection, is required for the early detection of late cutaneous metastases