Southern Tohoku Research Articles

Retrospective analysis of treatment-positioning accuracy and dose error in boron neutron capture therapy using a sitting-position treatment system for head and neck cancer

The neutron beam in boron neutron capture therapy (BNCT) exhibits poor directionality and significantly decreasing neutron flux with increasing distance. Therefore, the treatment site must be close to the irradiation aperture. Some patients with head and neck cancer may benefit from a sitting-position setup. The study aim was to evaluate the treatment-positioning accuracy and dose error in sitting patients receiving BNCT. Thirty-two patients with head and neck cancer who underwent sitting-position BNCT at Southern Tohoku BNCT Research Center were included in the study. Horizontal (ΔX) and vertical (ΔY) errors were defined as the displacement between the treatment planning system (TPS) digital reconstructed radiograph and the pre-treatment X-ray image. Using in-house software, image matching was performed. The beam-axial directional (ΔZ) error was compared with the parameters entered into the TPS and the actual pre-treatment measured values. The translational-position error was reflected in the TPS’s patient coordinate system with respect to the reference plan. Re-dose calculations were performed to evaluate the effect of positional error on tumor and normal-tissue doses. The [ΔX, ΔY, ΔZ] DRR-CR mean ± 1SD were − 0.40 ± 2.0, 0.30 ± 2.3, and − 1.4 ± 1.5 mm, respectively. The Dmean and D98% tumor-dose errors were 1.22 % ± 1.44 % and 0.99 % ± 1.63 %, respectively. The D2% pharyngeal and oral mucosal-dose errors were 0.98 % ± 1.91 % and 1.21 % ± 1.78 %, respectively. The tumor- and normal-tissue dose errors were typically < 5 %. High-precision treatment was feasible in sitting-positioned BNCT.

Genetic effects of demographic bottleneck and recovery in Kinkazan Island and mainland populations of Japanese macaques (Macaca fuscata).

Populations of Japanese macaques were significantly reduced in most areas from the 1900s to the 1960s and then recovered mainly in the northeastern part of Honshu. A drastic reduction in population size reduces genetic variability through a bottleneck effect. Demographic expansion after the reduction that accumulates new mutations can reduce the bottleneck effects or drive the recovery of genetic variability. We examined the genetic status of a small island population (Kinkazan Island) and a larger mainland population (southern Tohoku) of Japanese macaques that experienced recent demographic bottlenecks and recovery using eight microsatellite loci. The two populations were significantly genetically different from each other. The Kinkazan population exhibited lower genetic variability, remarkable evidence of bottleneck (i.e., significant heterozygosity excess and lower frequency of rare alleles), and a considerably smaller effective population size based on genetic data than based on the current census size. These results indicate that the genetic status has not completely recovered from the demographic bottleneck despite a full recovery in census size on Kinkazan Island. New mutations might rarely have accumulated because of the small carrying capacity of the island. Therefore, the genetic variability of the population would have been restrained by the severe bottleneck size, small carrying capacity, and long-term isolation. On the other hand, the bottleneck effect seems to be limited in the southern Tohoku population considering higher genetic variability, non-significant heterozygosity excess in many mutation conditions, and the highest frequency of rare alleles.

Consistent estimation of strain-rate fields from GNSS velocity data using basis function expansion with ABIC

Present day crustal displacement rates can be accurately observed at stations of global navigation satellite system (GNSS), and crustal deformation has been investigated by estimating strain-rate fields from discrete GNSS data. For this purpose, a modified least-square inversion method was proposed by Shen et al. (J Geophys Res 101:27957–27980, 1996). This method offers a simple formulation for simultaneously estimating smooth velocity and strain-rate fields from GNSS data, and it has contributed to clarify crustal deformation fields in many regions all over the world. However, we notice three theoretical points to be examined when we apply the method: mathematical inconsistency between estimated velocity and strain-rate fields, difficulty in objectively determining the optimal value of a hyperparameter that controls smoothness, and inappropriate estimation of uncertainty. In this study, we propose a method of basis function expansion with Akaike’s Bayesian information criterion (ABIC), which overcomes the above difficulties. Application of the two methods to GNSS data in Japan reveals that the inconsistency in the method of Shen et al. is generally insignificant, but could be clear in regions with sparser observation stations such as in islet areas. The method of basis function expansion with ABIC shows a significantly better performance than the method of Shen et al. in terms of the trade-off curve between the residual of fitting and the roughness of velocity field. The estimated strain-rate field with the basis function expansion clearly exhibits a low strain-rate zone in the forearc from the southern Tohoku district to central Japan. We also find that the Ou Backbone Range has several contractive spots around active volcanoes and that these locations well correspond to the subsidence areas detected by InSAR after the 2011 Tohoku-oki earthquake. Thus, the method of basis function expansion with ABIC would serve as an effective tool for estimating strain-rate fields from GNSS data.

Unexpected Species Identities and Interspecific Relationships in a Subterranean Beetle Lineage, the Pterostichus macrogenys Species Group (Coleoptera, Carabidae), Revealed by Fine-Scale Field Sampling and Detailed Morphological Comparisons.

Simple SummaryMorphological and ecological features are highly specialized among subterranean insect species. Studies of such features reveal the vast diversity of insect taxa and can also provide insight into the general mechanisms associated with species diversity. The Pterostichus macrogenys species group is an endemic subterranean Japanese carabid beetle lineage that shows marked regional differentiation. However, to date, its diversity has not been fully elucidated, partly due to the difficulty of sample collection. We examined 103 specimens from this species group, which were collected by fine-scale field sampling, and classified these into one new and eight known species. The results of this study revealed that some of these species have disjunct distributions, which have not been reported in this species group. More importantly, some species of this group coexisted in some localities; in most such cases, two species with different body sizes coexisted, implying a role of differential body size in promoting coexistence. In the remaining case, one large and two small species coexisted, and the two small species have male genitalia of different sizes; in this system, body and genital size differences appear to have different effects on coexistence, implying a species coexistence mechanism that has rarely been reported in insects.An endemic subterranean Japanese carabid beetle lineage, the Pterostichus macrogenys species group, was recently revealed to have marked regional differentiation. Studies of such features reveal insect species diversity and provide insight into the mechanisms driving species diversity. We examined specimens of this species group collected from the southern Tohoku District of Honshu, Japan, where its diversity has not yet been fully elucidated, using fine-scale field sampling and detailed comparative morphological analysis of male genitalia. In total, 103 specimens from 13 localities were classified into one new (P. monolineatus sp. n.) and eight known species. In four of the known species, we observed disjunct distributions, which have not previously been reported in this species group and may be more common than previously recognized. Species coexistence was observed at four sites, with two species of different body sizes coexisting at three sites and three species coexisting at the remaining site. The three coexisting species included one large and two small species, the latter of which have male genitalia of a different size. This newly discovered coexistence pattern implies separate effects of differential body and genital size in species coexistence, which has rarely been reported in insects.

Wide Distribution but Low Differentiation: Phylogenetic Relationships and Phylogeography of Hynobius nigrescens (Amphibia: Caudata).

We surveyed the genetic structure of Hynobius nigrescens Stejneger, 1907, a lentic breeding salamander widespread throughout montane and lowland regions of northeastern Japan. We performed a mitochondrial DNA analysis to explore intraspecific genetic variation and infer the evolutionary population history of H. nigrescens. Complete 1141 bp sequences of the mitochondrial cytochrome b gene were studied for 134 adult and larval individuals collected from 62 localities, encompassing the known range of the species. Hynobius nigrescens proved to be monophyletic, including two major clades (Clade II from southwestern Hokuriku and Clade I from all other localities). The latter clade comprises four well-supported and geographically structured subclades, which show genetic distances smaller than those seen in the widely sympatric species Hynobius lichenatus. Results of population statistical analyses indicated that Clade II of the westernmost range of H. nigrescens seems to have maintained a constant population size, while Clade I from most of the northeastern species range shows a tendency of recent population expansion, which is evident in Subclades I-A from the northernmost range and I-B from southern Tohoku to northern Kanto and eastern Chubu. In contrast, Subclades I-C from northeastern Chubu and Sado Is. and I-D from northwestern Chubu to Hokuriku seem to have been relatively stable in population size. Hynobius nigrescens differs greatly from other salamander species from northeastern Japan in its much more recent periods of genetic differentiation and its pattern thereof, and is suggested to be a young faunal element in this region.

Age as a decisive factor in general anaesthesia use in paediatric proton beam therapy

Proton therapy for paediatric cancer patients is an effective treatment; however, young children have may have difficulties staying still during irradiation. This study investigated the indication of general anaesthesia in paediatric proton therapy. Background information and anaesthesia/treatment protocols were retrospectively extracted from the medical records of cancer patients under 15 years who underwent proton therapy at Southern TOHOKU General Hospital, Fukushima, Japan between April 2016 and December 2018. The anaesthesia and non-anaesthesia groups were compared to evaluate factors determining the need for general anaesthesia. Thirty-two patients who received 285 irradiations were analysed. The median age was 5 years old (range: 1–15), and 13 patients (40.6%) were female. Twelve (37.5%) patients received general anaesthesia. In the general anaesthesia group, airway management using a laryngeal mask was performed in 11 patients (91.6%). Patient age was significantly lower in the general anaesthesia group than in the non-anaesthetised group (p < 0.001). Considering all background factors, only age was strongly associated with anaesthesia in the univariate logistic regression model (odds ratio 0.55 [95% confidence interval 0.35–0.86]; P < 0.01). Thus, age is one of the most important factors determining the need for general anaesthesia during proton therapy in children.

Features of soil behavior in the near-fault zones during the 2011 Tohoku mega-thrust earthquake Mw 9

Soil behavior is studied during the Tohoku earthquake, where abnormally high accelerations > 1 g were recorded. Based on vertical array records, models of soil behavior are constructed at 28 sites in northern Honshu (Tohoku region). They are compared with previously studied models of soil behavior in southern Tohoku and Kanto regions, where shock waves were identified as possible causes of the recorded high accelerations. Shear moduli did not reduce during strong motion at many sites, and the behavior of softer and denser soils was similar to a large extent. The nonlinearity of soil response during the Tohoku earthquake was weaker than that observed earlier during the 1995 Kobe and 2000 Tottori earthquakes (Mw ~6.7–6.8). Instead, a widespread soil hardening was found, most expressed at stations recorded the highest PGAs. To explain the observed features of soil behavior, two possible mechanisms are suggested, such as, 1) shock wave fronts generated by rupture propagation along the fault plane induce soil hardening and high PGAs; 2) soil compaction and hardening is a soil response to long-lasting dynamic loadings during the earthquake. Most likely we may expect similar effects of soil hardening and generation of high PGAs during other mega-thrust earthquakes in future.

Fragmented Ancient Fore-arc Basin: Cretaceous–Paleogene Sandstones Sporadically Found in Kanto and Southern Tohoku, Japan, as Eastern Extensions of the Izumi Group

Fragmented Ancient Fore-arc Basin: Cretaceous–Paleogene Sandstones Sporadically Found in Kanto and Southern Tohoku, Japan, as Eastern Extensions of the Izumi Group

LiCSBAS: An Open-Source InSAR Time Series Analysis Package Integrated with the LiCSAR Automated Sentinel-1 InSAR Processor

For the past five years, the 2-satellite Sentinel-1 constellation has provided abundant and useful Synthetic Aperture Radar (SAR) data, which have the potential to reveal global ground surface deformation at high spatial and temporal resolutions. However, for most users, fully exploiting the large amount of associated data is challenging, especially over wide areas. To help address this challenge, we have developed LiCSBAS, an open-source SAR interferometry (InSAR) time series analysis package that integrates with the automated Sentinel-1 InSAR processor (LiCSAR). LiCSBAS utilizes freely available LiCSAR products, and users can save processing time and disk space while obtaining the results of InSAR time series analysis. In the LiCSBAS processing scheme, interferograms with many unwrapping errors are automatically identified by loop closure and removed. Reliable time series and velocities are derived with the aid of masking using several noise indices. The easy implementation of atmospheric corrections to reduce noise is achieved with the Generic Atmospheric Correction Online Service for InSAR (GACOS). Using case studies in southern Tohoku and the Echigo Plain, Japan, we demonstrate that LiCSBAS applied to LiCSAR products can detect both large-scale (&gt;100 km) and localized (~km) relative displacements with an accuracy of &lt;1 cm/epoch and ~2 mm/yr. We detect displacements with different temporal characteristics, including linear, periodic, and episodic, in Niigata, Ojiya, and Sanjo City, respectively. LiCSBAS and LiCSAR products facilitate greater exploitation of globally available and abundant SAR datasets and enhance their applications for scientific research and societal benefit.

Future risk of frost on apple trees in Japan

We investigated the spring frost risk over the main apple production areas in Japan under future climates using multiple sets of global circulation models and scenarios. Frost risk was judged by the daily minimum air temperature. Apple phenology was estimated with a phenology model under future meteorological conditions. Since spring cold hardiness of apple trees depends on the phenophase, we took the effect into consideration by decomposing the season into three phenophases. April temperatures are projected to increase by 0.5–2 °C for 2031–2050 and 1.5–6 °C for 2081–2100 relative to that of 1981–2000, depending on the climate models and scenarios. Spring phenology will advance by 10 days or more for the highest temperature increase case for 2081–2100. Frost risk will not monotonically change with the future temperature increase. For the scenario with the temperature increase by 1–2 °C in spring, corresponding to the medium temperature increase case among our simulation cases, frost risk will be maximized in the southern Tohoku region and central highlands, where frost risk is relatively high under the current climates. Frost risk will tend to decrease for the highest temperature increase case. During bud break to foliation, apple trees will be in highest frost risk under future climates.

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.

I–1 Low-Intensity Pulsed Ultrasound (LIPUS) Treatment Results With Targeting Method Using Ultrasonography for Fresh Fractures Humerus and Femur

Background: We previously reported that bone union rate for LIPUS therapy of humerus and femur was inferior as compared with that of tibia and radius/ulna. One of the reasons of this discrepancy may be affected on the distance from skin to the fracture site. We hypothesized that the ideal site and direction for application of LIPUS could be determined by ultrasonogram. Objective: The aim of our study was to report outcomes of treatment for femoral and humerus fresh fracture with LIPUS by targeting method using ultrasonography to detect the fracture location and to determine the direction of LIPUS treatment. Materials: Thirteen fresh fractures of humerus (n = 2) or femur (n = 11) for which LIPUS treatment were performed at Southern TOHOKU General Hospital between April 2015 and June 2018. Seven bones were women, 6 bones were men. Average age was 61.7 years (19–92 years old). Two bones were treated conservative, 4 bones were fixed by intramedullary nailing and 7 bones were by plating. Methods: In all cases, the treatment site and direction were determined by targeting using ultrasonography and LIPUS treatment was performed. Results: In all bone, radiographic bone union was obtained, and bone union rate was 100%. The average depth from skin to the fracture site was 38.0 mm (22.5–61.9 mm), and the average gap of the fracture site was 3.9 mm (0.6–7.7 mm). The average period of callus formation was 1.2 months and the average fusion period was 3.7 months (2.00–6.00 months). Conclusion: The targeting technique based on ultrasonographic examination can improve LIPUS treatment results of delayed union for humerus and femurs.

Herd-level risk factors associated with Leptospira Hardjo infection in dairy herds in the southern Tohoku, Japan

A cross-sectional study was designed to generate information on the herd level prevalence and the risk factors for Leptospira serovar Hardjo (L. Hardjo) in Yamagata, the southern Tohoku, Japan. Bulk tank milk samples from 109 dairy herds were used to test the herd level sero-prevalence of L. Hardjo using a commercial ELISA kit, which detects both L. interrogans serovar Hardjo and L. borgpetersenii serovar Hardjo. A questionnaire survey was conducted at the sampled farms, and univariable and multivariable analyses were performed. Spatial clustering of L. Hardjo at the herd level was examined using spatial scan statistics. Seventy-one herds were found to be positive for L. Hardjo, and the apparent herd prevalence was 65.1% (95% CI: 56.2-74.1%). The risk factors for sero-positivity were larger herd size (p=0.004) and cows with a history of staying in Hokkaido (p <0.001). The spatial scan statistic detected a most likely cluster (relative risk=1.87, log likelihood ratio=9.93, radius=13.70km, p<0.01) in the southern part of the study area where there are large herd sizes and farm density is high. This study revealed that L. Hardjo is prevalent throughout Yamagata, and large scale herd owners introducing cows from Hokkaido in particular should be aware of the risk of infection.

Elucidating the spawning migration and core reproductive duration of male flatfish using sperm duct volume as an index for better fishery advice and management

The conservation and management of heavily exploited fish stocks require reliable data on various aspects of reproduction. In particular, information about spawning migration and spawning period of both sexes is essential for protecting important spawning habitats. However, studies that focus on male spawning ecology are very limited. We elucidated the male spawning migration, core duration of reproduction, and seasonal changes in the maturity of the barfin flounder Verasper moseri, an important target flatfish for stock enhancement programs in Japan. We conducted histological observations of the testes and utilized the sperm duct volume index to facilitate accurate determination of the male spawning period. Fish before spermiation were mainly observed off Hokkaido and partially off northern Tohoku (40.2–43.4°N) during August–December. However, fish undergoing spermiation and sperm release were not found near these areas and were observed only off southernmost Tohoku (35.8–37.5°N approximately 300m deep) from late January to April. Very few spent fish were caught off southern Tohoku, but were frequently observed off Hokkaido during May–June. These results demonstrate that male V. moseri repeat widespread spawning migrations over 700km between feeding grounds off Hokkaido and spawning grounds off southern Tohoku. Moreover, a combined analysis related to seasonal variations in the sperm duct volume and the proportion of spawning adults identified that the core duration of male reproduction was during March. Until now, reproduction of the next generation in the wild has not been confirmed, despite the continual release of seedlings and local fishery restrictions around Hokkaido. Our results underscore the necessity of a more widespread fishery management plan for V. moseri that encompasses the waters off Hokkaido and Tohoku to more effectively enhance reproduction.

Development of 11 microsatellite markers in Pinus parviflora by the dual-suppression technique and next-generation sequencing

Pinus parviflora Sieb. et Zucc. var. parviflora is a coniferous tree species distributed in mountainous areas of temperate zones from southern Tohoku to the Kyushu area in Japan. Some P. parviflora populations have become small and endangered due to massive death resulting from pine wilt disease, scab canker, and presumably climate change. We developed 11 microsatellite markers for P. parviflora by the dual-suppression technique and next-generation sequencing using 32 individuals of P. parviflora collected from Aokigahara at the foot of Mt. Fuji. The number of alleles for each locus ranged from two to 10. The averages of observed and expected heterozygosities were 0.61 and 0.59, respectively. These markers will become powerful tools for assessing genetic diversity, genetic connectivity, and genetic structure in P. parviflora populations, which will facilitate our understanding and conservation of P. parviflora.

Re-irradiation using proton beam therapy combined with weekly intra-arterial chemotherapy for recurrent oral cancer.

The purpose of this study was to clarify the efficacy and toxicities of re-irradiation using proton beam therapy combined with weekly intra-arterial chemotherapy for recurrent oral cancer. Between October 2009 and July 2014, 34 patients who had recurrent oral cancer were treated by proton beam therapy combined with intra-arterial infusion chemotherapy at the Southern Tohoku Proton Therapy Center, Japan. For all patients, the median follow-up was 25 months (range, 3-77 months). After treatment, 22 patients (65%) achieved a complete response, and 12 patients (35%) achieved a partial response at the primary tumor site. One-year and 2-year overall survival (OS) rates were 62% and 42%, respectively. One-year and 2-year LC rates were 77% and 60%, respectively. No treatment-related deaths were observed during the treatment and follow-up periods. Re-irradiation using proton beam therapy combined with weekly intra-arterial chemotherapy improved OS and local control rates compared with other treatment modalities and could become a new treatment modality for patients with recurrent oral cancer.

Establishment of Endoscopic Spinal Neurosurgery and its Current Status

Percutaneous endoscopic lumbar discectomy(PELD)has been used as a standard surgical technique for lumbar disc herniation at the Southern TOHOKU Healthcare Group since its introduction in 2009. We present our clinical experiences with PELD for 6 years and discuss the decision-making process for its surgical indication with a review of the pertinent literature. PELD can be performed under both local anesthesia and general anesthesia, and requires only a stab wound for surgery and 3 days of hospitalization. Our surgical results showed generally satisfactory outcomes; however, a salvage surgery was required for 10 of the 96 patients(10.4%)because of early recurrence, insufficient removal of the transligamentous disc fragment, and coexistent canal stenosis. Surgery was discontinued because of unbearable intraoperative pain in one patient each undergoing transforaminal approach and extraforaminal approach under local anesthesia. Although our experience is limited, PELD is considered a promising minimally invasive surgery for lumbar disc herniation. It is generally indicated for patients who are young, sports oriented, or extremely busy. Recurrent disc herniation after microdiscectomy, high risk for general anesthesia, and emergency are considered ideal indications for this technique. Since PELD is a newer technique with a high learning curve, further study, continuous training, and education are required before its widespread implementation. Careful selection of patients is crucial to achieve satisfactory surgical results.

The inhibitory effects of potassium chloride versus potassium silicate application on 137Cs uptake by rice

After the accident at the Fukushima Dai-ichi Nuclear Power Plant owned by the Tokyo Electric Power Company on 11 March 2011, potassium fertilizer was applied to agricultural fields in the southern Tohoku and northern Kanto regions of Japan to reduce the uptake of radiocesium by crops. In this study, we examined the effects of two types of potassium fertilizers, potassium chloride (a readily available potassium fertilizer) and potassium silicate (a slow-release potassium fertilizer), as well as a split application of potassium, on the accumulation of 137Cs by rice plants in two pot experiments. The 137Cs concentrations in the brown rice and in the above-ground plants were significantly lower after potassium chloride application than after potassium silicate application. The potassium ion (K+) concentrations in soil solutions sampled 9 and 21 d after transplanting were significantly higher for the potassium chloride application than for the potassium silicate application. The K+ concentrations in soil solutions observed in the application of potassium silicate were similar to those in the treatment when no potassium was applied. This finding indicates that the application of potassium silicate did not sufficiently increase the available K+ for rice plants in the soil, which led to a greater uptake of 137Cs after the potassium silicate application than after the application of potassium chloride. The 137Cs concentration in brown rice was higher in the split application of potassium fertilizer with the second application at the full heading stage than that without split application and the split application with the second application before heading.

Population Genetic Structure of the Asian Black Bear (Ursus thibetanus) within and Across Management Units in Northern Japan

Abstract. We examined the population genetic structure of the Asian black bear (Ursus thibetanus) in a large continuous habitat in northern Japan. To determine how population subdivision relates to management units (MUs) proposed by the Ministry of the Environment, genetic variation in the mitochondrial DNA control region (mtDNA-CR) and seven autosomal microsatellite loci was assessed in bears captured in southern Tohoku. Geographical distribution of the subpopulations was assessed using landscape analyses to find the best-fit model based on maximum entropy (MaxEnt) prediction and cost of movement. Genetic differentiation analyses revealed unique mtDNA-CR haplotypes in the study population. Bayesian population assignment of autosomal loci inferred four genetically distinct subpopulations in the study area (pop 1–4). The main distribution areas of pop1 and pop4 were separated by a high-cost zone for bear movement as a result of land use. Another high-cost zone was identified between pop2 and pop4, while th...

第２報告 北関東・南東北の木材加工（2000年代以降における林業の主産地形成 2014年度東日本林業経済研究会シンポジウム）

第２報告 北関東・南東北の木材加工（2000年代以降における林業の主産地形成 2014年度東日本林業経済研究会シンポジウム）