Virological characteristics of the SARS-CoV-2 XBB variant derived from recombination of two Omicron subvariants

In late 2022, SARS-CoV-2 Omicron subvariants have become highly diversified, and XBB is spreading rapidly around the world. Our phylogenetic analyses suggested that XBB emerged through the recombination of two cocirculating BA.2 lineages, BJ.1 and BM.1.1.1 (a progeny of BA.2.75), during the summer of 2022. XBB.1 is the variant most profoundly resistant to BA.2/5 breakthrough infection sera to date and is more fusogenic than BA.2.75. The recombination breakpoint is located in the receptor-binding domain of spike, and each region of the recombinant spike confers immune evasion and increases fusogenicity. We further provide the structural basis for the interaction between XBB.1 spike and human ACE2. Finally, the intrinsic pathogenicity of XBB.1 in male hamsters is comparable to or even lower than that of BA.2.75. Our multiscale investigation provides evidence suggesting that XBB is the first observed SARS-CoV-2 variant to increase its fitness through recombination rather than substitutions

Development of Multi-Layer Ionization Chamber for Heavy-ion Therapy

放医研でMU値を決定する為に使用している多層電離箱は、その構成物質に因りフラグメントテイルが水の分布と異なることから、経験的な補正をして使用している。しかし、より高精度に放射線治療を行うためには水に近いフラグメント反応をする検出器で測定する事が望ましい。そこで、Zの低いPMMA基材とカーボン電極を用いた新しい多層電離箱を開発し、照射試験を行った。結果、水の分布に比べ、既存の多層電離箱ではフラグメントテイルが30％以上異なるのに対し、新しく製作した多層電離箱ではフラグメントテイルも含め、2~4％の精度で一致する検出器の開発が達成できた。World Congress on Medical Physics and Biological Engineering 200

Investigation of Basic Characteristics of Syntheic Diamond Radiation Detector

Diamonds have attractive properties for use as radiation detectors. Recent advances in diamond fabrication techniques have made it possible to produce almost perfect single crystal materials that have electrical properties suitable for radiation detectors. We developed detectors made of high-purity synthetic IIa diamond grown by the high-pressure, high-temperature method and investigated their basic properties. The leakage current is less than 20 pA with reverse bias voltages up to 2.4 kV, and the diode current is 0.1 µA with 1 V forward bias voltage. The energy resolution for the best detector is 15.4 keV (FWHM) for 5.486 MeV alpha particles from 241Am.IEEE 2004 Nuclear Science Symposium and Medical Imaging Conferenc

Interspecies Comparative Analyses Reveal Distinct Carbohydrate-Responsive Systems among Drosophila Species

栄養に柔軟に適応し成長するシステムの解明 --種間の適応能力の差を生む炭水化物応答機構--. 京都大学プレスリリース. 2019-09-04.Why fruit flies eat practically anything. 京都大学プレスリリース. 2019-09-05.During evolution, organisms have acquired variable feeding habits. Some species are nutritional generalists that adapt to various food resources, while others are specialists, feeding on specific resources. However, much remains to be discovered about how generalists adapt to diversified diets. We find that larvae of the generalists Drosophila melanogaster and D. simulans develop on three diets with different nutrient balances, whereas specialists D. sechellia and D. elegans cannot develop on carbohydrate-rich diets. The generalist D. melanogaster downregulates the expression of diverse metabolic genes systemically by transforming growth factor β (TGF-β)/Activin signaling, maintains metabolic homeostasis, and successfully adapts to the diets. In contrast, the specialist D. sechellia expresses those metabolic genes at higher levels and accumulates various metabolites on the carbohydrate-rich diet, culminating in reduced adaptation. Phenotypic similarities and differences strongly suggest that the robust carbohydrate-responsive regulatory systems are evolutionarily retained through genome-environment interactions in the generalists and contribute to their nutritional adaptabilities

Positional Dependence of the CT number use of a Cone-beam CT Scanner for an Electron Density Phantom in Particle Beam Therapy

We evaluated the CT number accuracy in determining a CT calibration method for treatment planning by use of a 256 multi-slice CT (MSCT) scanner. An electron density phantom, which extends full length in the longitudinal direction, was scanned by the 256 MSCT scanner in a single rotation. We inserted four types of samples (air, 100 % ethanol, 40 wt% aqueous K2HPO4, and water) into the phantom. The regions of interest were set for all image slices, and the average CT number was calculated in the transverse and longitudinal sections. For the transverse image direction, the CT number became lower toward the center of the phantom with almost all samples. The causes of these phenomena might be attributed to the effects of scattered radiation and those of beam hardening due to the high-atomic-number material (40 wt% aqueous K2HPO4). However, the phenomena were too complicated to allow us to determine their causes only from the present studies. Meanwhile, for increasing the accuracy of the CT number calibration, a single sample should be inserted, and this step should be repeated with different samples. For the longitudinal direction, the CT number for a 40 wt % aqueous K2HPO4 sample increased by 30 HU from the anode to the cathode side due to variations in the X-ray energy caused by the heel effect. The caveat is that the CT number varies in the longitudinal direction when a CT scanner with a wide beam width is used

External dose audits for high energy X-rays used in radiotherapy by ANTM

In 2007, the Association for Nuclear Technology in Medicine (ANTM) set up an external audit system to check doses of high energy X-rays used in radiotherapy. The audits are based on measurements made with glass dosimeters (GD-302M, Ashahi Technoglass, Co.) that consist of fluorescent glass of rod type. In the audit, glass dosimeters are sent to institution by delivery service according to the request. After the irradiation of certain dose glass dosimeters are returned to ANTM, and the dose given to dosimeter is evaluated at ANTM Dose Calibration Center. The dose is compared with the one stated by the institution, and results of the audit are reported to the institution. Initially, audits by ANTM were limited to outputs of standard condition. However, from 2010, objects of the audit have been expanded to field and wedge conditions. By the end of 2010, 499 beams of 187 treatment machines have been audited by this system. For 320 beams of reference condition the mean and standard deviation of the ratio of doses were 1.043 and 0.0101. In 2010 (the first year of non-reference condition service), the numbers of beams checked with wedge factor and for field factor were 53 and 126, respectively.Japan-Korea Joint Meeting on Medical Physics and 11th Asia-Osecania Congress of Medical Physic