Recombinant expression and purification of phenylalanyl-tRNA synthetase from wheat: a long-lasting poly(U)-dependent poly(Phe) synthesis system.

Synthetic genes for the two subunits of phenylalanyl-tRNA synthetase (PheRS) from wheat were expressed in Escherichia coli. When each gene was induced individually, the α subunit with a cleavable 6 × His tag at the amino terminus was largely soluble, while the ß subunit was almost completely insoluble. When the two subunits were co-expressed, a soluble fraction containing the two subunits were obtained. This was purified by a standard method in which the tag was cleaved off with a specific protease after affinity purification. As the sample contained slightly more PheRSα than PheRSß, we further resolved the sample by gel filtration to obtain the fraction that showed the size of the conventional α2ß2 tetrameric complex and contains an almost equal amount of the two subunits. The final yield was 0.6 mg per 1 liter of the culture medium, and the specific activity was 28 nmol min-1 mg-1, which was higher than that of a fraction purified from wheat germ. This recombinant PheRS was used, along with purified samples of the elongation factors and the ribosomes from wheat germ, for a poly(U)-dependent poly(Phe) synthesis reaction. The reaction was dependent on the added components and lasted for more than several hours.

Analysis of respiratory-induced motion trajectories of individual liver segments in patients with hepatocellular carcinoma.

PURPOSE: To analyze the respiratory-induced motion trajectories of each liver segment for hepatocellular carcinoma (HCC) to derive a more accurate internal margin and optimize treatment protocol selection. MATERIALS AND METHODS: Ten-phase-gated four-dimensional computed tomography (4DCT) scans of 14 patients with HCC were analyzed. For each patient, eight representative regions of interest (ROI) were delineated on each liver segment in all 10 phases. The coordinates of the center of gravity of each ROI were obtained for each phase, and then the respiratory motion in the left-right (LR), anteroposterior (AP), and craniocaudal (CC) directions was analyzed. Two sets of motion in each direction were also compared in terms of only two extreme phases and all 10 phases. RESULTS: Motion of less than 5 mm was detected in 12 (86%) and 10 patients (71%) in the LR and AP directions, respectively, while none in the CC direction. Motion was largest in the CC direction with a maximal value of 19.5 mm, with significant differences between liver segment 7 (S7) and other segments: S1 (p < 0.036), S2 (p < 0.041), S3 (p < 0.016), S4 (p < 0.041), and S5 (p < 0.027). Of the 112 segments, hysteresis >1 mm was observed in 4 (4%), 2 (2%), and 15 (13%) in the LR, AP, and CC directions, respectively, with a maximal value of 5.0 mm in the CC direction. CONCLUSION: A significant amount of respiratory motion was detected in the CC direction, especially in S7, and S8. Despite the small effect of hysteresis, it can be observed specifically in the right lobe. Therefore, caution is required when using 4DCT to determine IM using only end-inspiration and end-expiration. Understanding the respiratory motion in individual liver segments can be helpful when selecting an appropriate treatment protocol.

Radioactivation effects of titanium caused by clinical proton beam: a simulation study.

Objective. In proton beam therapy (PBT), metals in the patient body perturb the dose distribution, and their radioactivation may affect the dose distribution around the metal; however, the radioactivation effect has been not clarified with PBT. In this study, we aimed to evaluate the radioactivation effect of metal depending on proton energies and secondary neutrons with a clinical proton beam using a Monte Carlo (MC) simulation.Approach.The radionuclides produced from a titanium alloy (Ti-6Al-4V) and their radioactivity were calculated using a 210-MeV passive scattering proton beam with a 60-mm Spread-out Bragg Peak, and the deposited doses caused by the radioactivation were computed using the MC simulation. The position of metal was changed according to the proton mean energy in water. To assess neutron effects on the radioactivation, we calculated the radioactivation in following three situations: (i) full MC simulation with neutrons, (ii) simulation without secondary neutrons generated from the beamline components, and (iii) simulation without any secondary neutrons.Main results.Immediately after the irradiation, the radionuclide with the largest activity was Sc-45 m (half-life of 318 ms) regardless of the proton energy and the presence of neutrons. Total radioactivity tended to increase according to the proton energy. The accumulated dose for 24 h caused by the metal activation showed an increasing trend with the proton energy, with a maximum increase rate of 0.045% to the prescribed dose. The accumulated dose at a distance of 10 mm from the metal was lower than 1/10 of that at a distance of 1 mm.Significance.The radioactivation effect of the titanium was comprehensively evaluated in the clinical passive scattering proton beam. We expect that radioactivation effects on the clinical dose distribution would be small. We consider that these results will help the clinical handling of high-Z metals in PBT.

Characterization and clinical utility of different collimator shapes in accelerator-based BNCT systems for head and neck cancer.

NeuCure® is the only accelerator-based boron neutron capture therapy (BNCT) system in the world with pharmaceutical approval. Until now, only flat collimators (FCs) on the patient side have been installed. However, in some cases of head and neck cancer patients, positioning the patient close enough to the collimator when using FCs was difficult. Thus, there are concerns about the prolongation of the irradiation time and overdose to normal tissues. To address these issues, a collimator with a convex-extended section on the patient side (extended collimators [ECs]) was developed, and its pharmaceutical approval was obtained in February 2022. This study evaluated the physical characterization and usefulness of each collimator using a simple geometry water phantom model and human model. In the water phantom model, the thermal neutron fluxes at 2 cm depth on the central axis were 5.13 × 108, 6.79 × 108, 1.02 × 109, and 1.17 × 109n/cm2/s for FC(120), FC(150), EC50(120), and EC100(120), respectively, when the distance from the irradiation aperture was kept constant at 18 cm. With ECs, the relative off-axis thermal neutron flux decreased steeply. In the hypopharyngeal cancer human model, the tumor dose changes were within <2%, but the maximum oral mucosa doses were 7.79, 8.51, 6.76, and 4.57 Gy-Eq, respectively. The irradiation times were 54.3, 41.3, 29.2, and 24.8 min, respectively. In cases where positioning the patient close to the collimator is difficult, the use of ECs may reduce the dose to normal tissues and shorten the irradiation time.

The Clinical Characteristics of Allergic Bronchopulmonary Mycosis Differ Among Pathogenic Fungi.

Background: Allergic bronchopulmonary mycosis (ABPM) occurs with fungi, other than Aspergillus fumigatus. However, the clinical characteristics of ABPM caused by non-Aspergillus species are unspecified. Methods: We retrospectively reviewed all patients with ABPM who visited to our hospital between April 2005 and December 2020. The causative fungi and clinical characteristics were analyzed. Patients were divided into the Aspergillus group and the non-Aspergillus group. Results: Fourteen patients and five patients were included in the Aspergillus group and the non-Aspergillus group, respectively. Compared to the Aspergillus group, the non-Aspergillus group had a significantly low serum immunoglobulin E level and low forced vital capacity. In addition, the non-Aspergillus group had a lower rate of the requirement for oral corticosteroid treatment and a low frequency of recurrence. Conclusion: Patients with non-Aspergillus ABPM had lower type 2 inflammation than did patients with allergic bronchopulmonary aspergillosis.

Dosimetric effect of six degrees of freedom couch top with rotational setup error corrections in proton therapy.

PURPOSE: To investigate the dosimetric effect of six degrees of freedom (6DoF) couch top with rotational corrections in proton therapy (PT). METHODS: The water equivalent thickness (WET) was measured using a proton beam with a 6DoF couch top and patient immobilization base plate (PIBP) placed in front of a motorized water phantom. The accuracy verification was performed with the beam axis set perpendicular to the 6DoF couch top and tilted in 10° steps from 10° to 30°. Up to 3° rotational correction may be added during the actual treatment to correct the rotational setup error on our system. The measured and calculated values using the treatment planning system were compared. Additionally, the effect of the 3° difference was evaluated using actual measurements concerning each angle on the proton beam range. RESULTS: The WET of the 6DoF couch top and PIBP were 8.5 ± 0.1 mm and 6.8 ± 0.1 mm, respectively. The calculation and the actual measurement at each angle agreed within 0.2 mm at the maximum. A maximum difference of approximately 0.6 mm was confirmed when tilted at 3° following 30° with the 6DoF couch top plus PIBP. CONCLUSIONS: The dosimetric effect of the 6DoF couch top with rotational corrections in PT differs depending on the incidence angle on the couch top, and it increased with the increased oblique angle of incidence. However, the effect on the range was as small as 0.6 mm at the maximum. The amount of rotational correction, the angle of incidence of the beam, and the effect of rotational corrections on the proton beam range may differ depending on the structure of the couch top. Therefore, sufficient prior confirmation, and subsequent periodical quality assurance management are important.

Identification of Induced Radionuclides Produced from Dental Metals in Proton Beam Therapy for Head and Neck Cancer.

Purpose: To identify the induced radionuclides produced from dental metals in proton beam therapy and investigate the accuracy of the Monte Carlo (MC) simulation by comparing the measured radioactivity. Methods and Materials: Two dental metals of pure titanium and gold-silver-palladium alloy, commonly used in Japan, were used in this study. The dental metal placed at the center of Spread-out Bragg Peak was irradiated by 150-MeV passive scattering proton beam. The gamma rays emitted from the activated dental metals were measured using a high purity germanium (HPGe) detector. The induced radionuclides were identified from the measured gamma-ray energies. Furthermore, the Particle and Heavy Ion Transport code System v.3.24 and DCHAIN were used for the MC simulation. The measured radionuclides and their radioactivity were compared with the simulation results. Results: In the MC simulation for the activated titanium, vanadium-47, with a half-life of 32.6 minutes had the strongest radioactivity among the induced radionuclides. The energy peaks of gamma rays emitted from titanium-51, scandium-43, scandium-44, and annihilation gamma rays were observed for the activated titanium in the HPGe detector. In the MC simulation for the activated gold-silver-palladium alloy, silver-108, with a half-life of 2.4 minutes had the strongest radioactivity. The energy peaks of gamma rays emitted from silver-104, silver-104 m, silver-108, and annihilation gamma rays were observed for the activated gold-silver-palladium alloy in the HPGe detector. Furthermore, the induced radionuclides and their radioactivity in the MC simulation were consistent with the measurement results for both dental metals, except for a few radionuclides. Conclusions: We identify the induced radionuclides produced from 2 dental metals and compared their radioactivity between the measurements and the MC simulation. Although the identification of the induced radionuclides using the MC simulation remains uncertain, the MC simulation can be clinically effective for pre-estimating the induced radionuclides in proton beam therapy.

Dosimetric effects of the ipsilateral shoulder position variations in the sitting-positioned boron neutron capture therapy for lower neck tumor.

We aimed to evaluate dosimetric effects of ipsilateral shoulder position variations (ISPVs) in sitting-positioned boron neutron capture therapy (BNCT) for lower neck tumor. The ISPVs were simulated using deformed shoulder images that can simulate arbitrary shape. The dose-volume parameters for the tumor in the rotated shoulder plans considerably varied compared with that for the mucosa. Even in a small number of cases, these differences were clearly observed among patients. The ISPVs in lower neck BNCT have great dosimetric effects.

Pembrolizumab-induced aseptic meningitis in a patient with non-small cell lung cancer: A case report and literature review of aseptic meningitis as an immune-related adverse event.

Aseptic meningitis is a rare immune-related adverse event (irAE), which occurs during treatment with immune checkpoint inhibitors (ICIs). This condition has non-specific symptoms and exhibits no clear signs on magnetic resonance imaging (MRI). There are only a few reports of aseptic meningitis caused by pembrolizumab treatment for non-small cell lung cancer (NSCLC). The present study includes a report of such a case and a review of the related literature. A 67-year-old Japanese man received first-line pembrolizumab treatment for NSCLC and subsequently developed severe nausea and vomiting. No significant findings were observed following a computed tomography (CT) scan, MRI of the brain and upper gastrointestinal tract, or upper gastrointestinal endoscopy. Cerebrospinal fluid analysis revealed lymphocyte infiltration and elevation of the IgG index, without indications of metastasis or infection, which suggested the presence of aseptic meningitis. The symptoms immediately improved following prednisolone treatment, and aseptic meningitis was diagnosed as an irAE related to pembrolizumab treatment. Given that aseptic meningitis can cause non-specific symptoms, including headache and nausea, the possibility of an irAE should be considered in patients with non-specific symptoms who are receiving ICIs, and a cerebrospinal fluid examination should be performed.

Determining a methodology of dosimetric quality assurance for commercially available accelerator-based boron neutron capture therapy system.

The irradiation field of boron neutron capture therapy (BNCT) consists of multiple dose components including thermal, epithermal and fast neutron, and gamma. The objective of this work was to establish a methodology of dosimetric quality assurance (QA), using the most standard and reliable measurement methods, and to determine tolerance level for each QA measurement for a commercially available accelerator-based BNCT system. In order to establish a system of dosimetric QA suitable for BNCT, the following steps were taken. First, standard measurement points based on tissue-administered doses in BNCT for brain tumors were defined, and clinical tolerances of dosimetric QA measurements were derived from the contribution to total tissue relative biological effectiveness factor-weighted dose for each dose component. Next, a QA program was proposed based on TG-142 and TG-198, and confirmed that it could be assessed whether constancy of each dose component was assured within the limits of tolerances or not by measurements of the proposed QA program. Finally, the validity of the BNCT QA program as an evaluation system was confirmed in a demonstration experiment for long-term measurement over 1 year. These results offer an easy, reliable QA method that is clinically applicable with dosimetric validity for the mixed irradiation field of accelerator-based BNCT.

Dosimetric effect of set-up error in accelerator-based boron neutron capture therapy for head and neck cancer.

The dosimetric effect of set-up error in boron neutron capture therapy (BNCT) for head and neck cancer remains unclear. In this study, we analyzed the tendency of dose error by treatment location when simulating the set-up error of patients. We also determined the tolerance level of the set-up error in BNCT for head and neck cancer. As a method, the distal direction was shifted with an interval of 2.5 mm, from 0.0 mm to +20.0 mm and compared with the dose at the reference position. Similarly, the horizontal direction and vertical direction were shifted, with an interval of 5.0 mm, from -20.0 mm to +20.0 mm. In addition, cases with 3.0 mm and 5.0 mm simultaneous shifts in all directions were analyzed as the worst-case scenario. The dose metrics of the minimum dose of the tumor and the maximum dose of the mucosa were evaluated. From unidirectional set-up error analysis, in most cases, the set-up errors with dose errors within ±5% were Δdistal < +2.5 mm, Δhorizontal < ±5.0 mm and Δvertical < ±5.0 mm. In the simulation of 3.0 mm shifts in all directions, the errors in the minimum tumor dose and maximum mucosal dose were -3.6% ±1.4% (range, -5.4% to -0.6%) and 2% ±1.4% (range, 0.4% to 4.5%), respectively. From these results, if the set-up error was within ±3.0 mm in each direction, the dose errors of the tumor and mucosa could be suppressed within approximately ±5%, which is suggested as a tolerance level.

Asymmetric synthesis of intermediate for (1R,2S)-ethyl 1-amino-2-vinylcyclopropanecarboxylate by desymmetrization using engineered esterase from Bacillus subtilis.

(1R,2S)-Ethyl 1-amino-2-vinylcyclopropanecarboxylate (VCPA), is a key intermediate for anti-hepatitis C virus drugs. In this study, we developed an efficient manufacturing method of intermediate for (1R,2S)-VCPA by enzymatic desymmetrization of a malonate diester derivative. In synthesis scheme of VCPA (1S,2S)-1-(ethoxycarbonyl)-2-vinylcyclopropanecarboxylic acid (VCPME) is the monoester intermediate, which is converted from 2-vinylcyclopropane-1,1-dicarboxylate diethyl ester (VCPDE). As a result of esterase screening for producing (1S,2S)-VCPME from VCPDE by enzymatic desymmetrization, p-nitrobenzyl esterase from Bacillus subtilis NBRC3027 (PNBE3027) showed high enantioselectivity (more than 90% e.e.). Based on the homology model of PNBE3027, a library of mutants with the substitution of L70, L270, L273, and L313 in substrate-binding pocket was created for improvement in enantioselectivity. (1S,2S)-VCPME produced by the best variant harboring L70D, L270Q, L273R, and L313M showed 98.9% e.e. of enanthiopurity. Furthermore, preparative scale production of (1S,2S)-VCPME using the quadruple mutant was achieved. Our investigations present a new efficient process for (1R,2S)-VCPA using esterase and diverse to be applied for the industrial scale production.

Dosimetric properties of a newly developed thermoluminescent sheet-type dosimeter for clinical proton beams.

PURPOSE: This study aimed to evaluate the dosimetric properties of a newly developed thermoluminescent sheet-type dosimeter (TLD-sheet) for clinical proton beams. MATERIALS AND METHODS: The TLD-sheet is composed mainly of manganese doped lithium triborate, with a physical size and thickness of 150 mm × 150 mm and 0.15 mm respectively. It is flexible and can be cut freely for usage. The TLD-sheet has an effective atomic number of 7.3 and tissue-equivalent properties. We tested the reproducibility, fading effect, dose linearity, homogeneity, energy dependence, and water equivalent thickness (WET) of the TLD-sheet for clinical proton beams. We conducted tests with both unmodulated and modulated proton beams at energies of 150 and 210 MeV. RESULTS: The measurement reproducibility was within 4%, which included the inhomogeneity of the TLD-sheet. The fading rates were approximately 20% and 30% after 2 and 7 days respectively. The TLD-sheet showed notable energy dependence in the Bragg peak and distal end of the spread-out Bragg peak regions. However, the dose-response characteristics of the TLD-sheet remained linear up to a physical dose of 10 Gy in this study. This linearity was highly superior to those of commonly used radiochromic film. The thin WET of the TLD-sheet had little effect on the range. CONCLUSION: Although notable energy dependences were observed in Bragg peak region, the response characteristics examined in this study, such as reproducibility, fading effects, dose linearity, dose homogeneity and WET, showed that the TLD-sheet can be a useful and effective dosimetry tool. With its flexible and reusable characteristics, it may also be an excellent in vivo skin dosimetry tool for proton therapy.

The efficacy and safety of reduced-dose sulfamethoxazole-trimethoprim for chemoprophylaxis of Pneumocystis pneumonia in patients with rheumatic diseases.

OBJECTIVES: Pneumocystis pneumonia (PCP) is a life-threatening opportunistic infection. Sulfamethoxazole-trimethoprim (SMX/TMP) is the first-line drug for PCP prophylaxis. However, adverse events (AEs) force clinicians to alter or reduce the drug dosage. METHODS: We retrospectively reviewed all patients with rheumatic diseases who received SMX/TMP for prophylaxis and glucocorticoid therapy between April 2004 and March 2018. The rates of AEs, SMX/TMP discontinuation, and incidence of PCP were analyzed. Patients were divided into the conventional group and the dose-reduction group. RESULTS: One hundred forty-five patients and 75 patients were included in the conventional group and the dose-reduction group, respectively. Compared to the dose-reduction group, the conventional group had a significantly high frequency of AEs (10.7% vs. 24.1%; p = .017); however, the rate of discontinuing SMX/TMP was not significantly different (8.0% vs. 14.5%; p = .165). Thirteen conventional group patients required a reduced SMX/TMP dose because of AEs; no patient developed PCP. The conventional SMX/TMP dose and renal dysfunction were associated with AEs in multivariate analysis. CONCLUSION: Patients who received a reduced SMX/TMP dose did not have PCP and had a lower frequency of AEs. A reduction in SMX/TMP for PCP prophylaxis is effective and safe in patients with rheumatic disease.

Adult-onset Still's disease with concurrent thrombotic thrombocytopenic purpura: case report and literature review.

Thrombotic thrombocytopenic purpura (TTP) is rare complication resulting from adult-onset Still's disease (AOSD). We report the case of a 69-year-old Japanese man who initially presented with fever and joint pain and was diagnosed as having concurrent AOSD with TTP 1 month later. He had extremely high ferritin levels (32 696 ng/mL). He initially responded to plasma exchange but subsequently died of septic shock. AOSD accompanied by extremely high ferritin levels might be considered a sign of concurrent TTP.

End-to-end test to evaluate the comprehensive geometric accuracy of a proton rotating gantry using a cone-shaped scintillator screen detector.

In this study, we aim to evaluate the comprehensive geometric accuracy of proton rotating gantries by performing an end-to-end test using a cone-shaped scintillator screen detector, known as XRV-124. The XRV-124 comprises a cone-shaped sheet-like scintillator and charge-coupled device camera that detects the scintillation light. First, the results of the Winston-Lutz and end-to-end XRV-124 tests performed on a conventional linear accelerator were compared to confirm the reliability of the XRV-124, and the snout position dependency of the geometric accuracy was evaluated for the proton rotating gantry as a pre-verification process. Thereafter, an end-to-end test including computed tomography imaging and irradiation in 30° steps from 0° to 330° for two proton rotating gantries, which have the same specifications, was performed. The results of the pre-verification indicated that sufficient accuracy was obtained for the end-to-end test of the proton rotating gantry. The end-to-end test results showed a peak-to-peak deviation of up to 2 mm for some of the coordinate axes. The two gantries exhibited almost similar results in terms of the absolute quantity; however, a few trends were different. Thus, the beam axis deviations were confirmed to be within the safety margin, as expected in clinical practice. Based on the results of this study, the XRV-124 can be used as a comprehensive end-to-end constancy test tool, as it enables a comparative verification of multiple rotating gantries and geometric accuracy verification of different treatment modalities.

Design and construction of an accelerator-based boron neutron capture therapy (AB-BNCT) facility with multiple treatment rooms at the Southern Tohoku BNCT Research Center.

Installation of an accelerator-based boron neutron capture therapy (AB-BNCT) system was started in April 2014 at the Southern Tohoku BNCT Research Center (STBRC), and clinical trials began in January 2016. There are two treatment rooms, which have same specifications, and the beam quality equivalency was confirmed both rooms. Here, we describe the design and construction of the first hospital-based AB-BNCT facility in the world with multiple treatment rooms.

[Influence and Countermeasure of Respiratory Motion on Matchline Profile of Field Matching Technique in Passive Scattering Proton Therapy for Esophageal Cancer].

This study aimed to evaluate the influence of change in respiratory motion on matchline (ML) and reduction of the effect by increasing ML levels of field matching technique in passive scattering proton therapy for esophageal cancer. To evaluate the influence of respiratory motion in terms of stability, we measured relative dose around ML using a respiratory motion phantom. The relative error was -0.5% when the respiratory motion phantom worked stable, whereas there was obvious change that the relative error was -25.5% when the difference of amplitude between upper field and lower field was one side 3 mm on each cranially and caudally direction. In clinical case of the seven esophageal cancer patients simulated by the treatment planning system, assuming the difference of amplitude was 3 mm, the relative error of maximum (minimum) dose in clinical target volume around ML against the original treatment plan were 5.8±1.2% (-6.0±2.7%), 3.3±0.9% (-3.8±1.0%), and 2.4±0.5% (2.6±0.8%) on average (±SD) when ML levels were 2, 4, and 6, respectively. Increasing ML levels can reduce the influence of respiratory motion.

Patient-specific quality assurance for proton depth dose distribution using a multi-layer ionization chamber in a single-ring wobbling method.

The use of a multi-layer ionization chamber, Zebra, in patient-specific quality assurance (QA) for proton depth dose distributions in a single-ring wobbling method is investigated. The depth dose distributions measured using Zebra are compared with those calculated using the treatment planning system (TPS), XiO-M, and measured using an ionization chamber with a motorized water phantom system. Because the TPS only provides point doses, the average doses are calculated using in-house software. The detector size-corrected depth dose distributions are obtained by determining the average of the dose distributions from the TPS over a cylindrical region similar to the size of the Zebra detectors. The calculated depth dose distributions from the cases with a simple compensator shape are in good agreement with those obtained from the TPS without performing volume averaging; however, a 15% difference was shown when compared with those from the cases with a complex compensator shape. Then, the measurements are compared with the detector size-corrected depth dose distributions, showing an improved agreement within 3% for the highly steep dose gradient regions. Although there are some field size limitations, the Zebra system is a useful device for the fast measurement of patient-specific QA for depth dose distributions in wobbled proton beams. However, careful consideration is required for complex dose distribution fields, because the measurements obtained using Zebra cannot be directly compared to the depth dose distributions from the TPS owing to the finite detector size of the Zebra chamber.