Publications by authors named "Minoru Nakao"

150 Publications

Treatment planning comparison between dynamic wave arc and volumetric modulated arc therapies for prostate-cancer treatment.

Med Dosim 2021 Sep 16. Epub 2021 Sep 16.

Hiroshima High-Precision Radiotherapy Cancer Center, 3-2-2, Futabanosato, Higashi-ku Hiroshima 732-0057, Japan; Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.

The aim of this study was to compare the quality of dynamic wave arc (DWA) and coplanar volumetric modulated arc therapy (co-VMAT) plans for the treatment of localized prostate cancer. The planning target volume (PTV)-rectum, a section of the PTV comprising the PTV minus that of the rectum, received 78 Gy in 39 fractions as the mean dose to the PTV-rectum. The DWA and co-VMAT plans were generated for each patient using the RayStation treatment planning system for the Vero4DRT system. The PTV-rectum dose (D: the percent dose irradiating 95% of the volume), homogeneity index (HI), conformity index (CI), as well as doses to the bladder wall, rectum wall (V Gy: the percent volume receiving 10-70 Gy), and bilateral femoral heads of the DWA and co-VMAT plans were compared. The output monitor unit (MU) and delivery time obtained for each set of plans were also investigated. In terms of target coverage, the DWA plans provided an average D of 75.5 Gy, which was comparable to the co-VMAT-plan D of 75.2 Gy (p < 0.05). The HI was significantly better with the DWA. As for the DWA plans, the bladder-wall volume receiving 10, 20, 30, and 40 Gy (V) was significantly smaller than that of the co-VMAT plans, and the volume of the rectal wall receiving 10 Gy (V) was significantly larger than that of the co-VMAT plans. The DWA plans yielded a reduced dose to the bilateral femoral heads compared with the co-VMAT plans (p < 0.05). The values of the CI and MU, and the delivery time exhibited no significant differences between the DWA and co-VMAT plans. The DWA plan is a feasible treatment option for prostate cancer radiotherapy.
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http://dx.doi.org/10.1016/j.meddos.2021.08.001DOI Listing
September 2021

Brachylaima phaedusae n. sp. (Trematoda: Brachylaimidae) from door snails in Japan.

Parasitol Int 2021 Sep 15;86:102469. Epub 2021 Sep 15.

Kyushu Mollusc Study Society, 4-21-17 Konan, Miyazaki, Miyazaki 880-0944, Japan.

The metacercarial infections of door snails (Gastropoda: Clausiliidae) with unknown species of the genus Brachylaima (Trematoda: Brachylaimidae) have recently been reported in eastern Honshu and Kyushu, Japan. A large scale snail survey was carried out to clarify their taxonomic status. From the period of 2015 to 2020, a total of 1239 land snails (768 door snails and 471 others) were collected from 32 localities in Honshu, Shikoku, and Kyushu. The resulting trematode isolates were identified as Brachylaima sp. by mitochondrial DNA barcoding. The sporocysts were found only a few from Megalophaedusa sublunellata (Clausiliidae), Tauphaedusa subaculus (Clausiliidae), and Aegista trochula (Camaenidae), while the metacercariae were frequently detected from 14 species of Clausiliidae and 2 species of other families. Although Brachylaima sp. showed a broad range of intermediate hosts, door snails seem to be very important to drive the life cycle. The gravid adults of Brachylaima sp. was experimentally raised from metacercariae using immunosuppressed mice. Morphological, phylogenetical, and ecological considerations prompted us to propose Brachylaima phaedusae n. sp. for this unknown species. The definitive hosts of the new species are completely unknown. The wide geographic distribution and high genetic diversity of the new species suggest a possibility that the definitive host is ground-foraging birds, which prefer door snails.
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http://dx.doi.org/10.1016/j.parint.2021.102469DOI Listing
September 2021

The phylogeographic puzzle of Pseudoacanthocephalus toshimai, an amphibian acanthocephalan in northern Japan.

Parasitol Int 2021 Oct 28;84:102400. Epub 2021 May 28.

Graduate course of Education, Hirosaki University, Hirosaki, Aomori 036-8560, Japan.

The amphibian acanthocephalan, Pseudoacanthocephalus toshimai, was considered to be an island-endemic species in Hokkaido, Japan. However, the parasite was found from Rana ornativentris, Rana tagoi, Zhangixalus arboreus, and Bufo japonicus formosus in northern Honshu (Aomori and Iwate Prefectures), which is separated from Hokkaido by the Tsugaru Strait. The mitochondrial DNA-based phylogenetic and population genetic analyses of P. toshimai showed that the northern Honshu isolates are far distantly related to the Hokkaido isolates, and that a demographic population expansion occurred in Hokkaido during the recent geological past. The rich genetic diversity of P. toshimai in northern Honshu suggests a scenario that anuran hosts invaded Hokkaido together with P. toshimai via the land bridge of the Tsugaru Strait. However, the evolutionary history of Rana pirica, a main definitive host for P. toshimai in Hokkaido, is contradictory to the introduction scenario inferred from the parasite. The finding of several geographically mismatched isolates of P. toshimai from both northern Honshu and Hokkaido suggests a possibility that the migration of the parasite infrequently occurred between the two areas even after the land bridge disappeared. More detailed information on the evolutionary history of anurans is needed to resolve the biogeographical enigma of P. toshimai.
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http://dx.doi.org/10.1016/j.parint.2021.102400DOI Listing
October 2021

Hydrogel spacer shrinkage during external-beam radiation therapy following low-dose-rate brachytherapy for high-risk prostate cancer: a case series.

J Med Case Rep 2021 May 26;15(1):296. Epub 2021 May 26.

Department of Radiation Oncology, Hiroshima University Hospital, 1-2-3 Kasumi Minami-ku Hiroshima-shi, Hiroshima, 734-8553, Japan.

Background: Few studies have assessed hydrogel spacer shrinkage during external-beam radiation therapy following brachytherapy for localized high-risk prostate cancer. This case presentation evaluated the changes in hydrogel spacer appearance by magnetic resonance imaging during external-beam radiation therapy after brachytherapy for prostate cancer and analyzed the effect of this shrinkage on the dose distribution in four cases.

Case Presentation: In all cases, we implanted I sources using a modified peripheral loading pattern for seed placement. The prescribed dose for each implant was 110 Gy. After delivering the sources, a hydrogel spacer was injected. All cases underwent external-beam radiation therapy approximately 1-2 months after brachytherapy. The prescribed dose of external-beam radiation therapy was 45 Gy in 1.8-Gy fractions. Magnetic resonance imaging was performed for evaluation on the day following seed implantation (baseline), at external-beam radiation therapy planning, and during external-beam radiation therapy. The median hydrogel spacer volume was 16.2 (range 10.9-17.7) cc at baseline, 14.4 (range, 9.4-16.1) cc at external-beam radiation therapy planning, and 7.1 (range, 2.0-11.4) cc during external-beam radiation therapy. The hydrogel spacer volume during external-beam radiation therapy was significantly lower than that at external-beam radiation therapy planning. The rectum V60-80 (rectal volume receiving at least 60-80% of the prescribed dose of external-beam radiation therapy) during external-beam radiation therapy was significantly higher than that at external-beam radiation therapy planning.

Conclusions: The potential reduction in hydrogel spacer size during external-beam radiation therapy following brachytherapy can lead to unexpected irradiation to the rectum. This case presentation would be helpful for similar cases.
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http://dx.doi.org/10.1186/s13256-021-02864-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152132PMC
May 2021

Uncertainty in the positioning of patients receiving treatment for brain metastases and wearing surgical mask underneath thermoplastic mask during COVID-19 crisis.

J Appl Clin Med Phys 2021 Jun 24;22(6):274-280. Epub 2021 May 24.

Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 732-0057, Japan.

Thermoplastic masks, used along with surgical masks, enable immobilization methods to reduce the risk of infection in patients undergoing intracranial stereotactic radiosurgery and stereotactic radiotherapy (SRS/SRT) during the COVID-19 crisis. The purpose of this study was to investigate the feasibility of thermoplastic mask immobilization with a surgical mask using an ExacTrac system. Twelve patients each with brain metastases were immobilized using a thermoplastic mask and a surgical mask and only a thermoplastic mask. Two x-ray images were acquired to correct (XC) and verify (XV) the patient's position at a couch angle of 0°. Subsequently, the XC and XV images were acquired at each planned couch angle for non-coplanar beams. When the position errors were detected after couch rotation for non-coplanar beams, the errors were corrected at each planned couch angle until a clinically acceptable tolerance was attained. The position errors in the translational and rotational directions (vertical, lateral, longitudinal, pitch, roll, and yaw) were retrospectively investigated using data from the ExacTrac system database. A standard deviation of XC translational and rotational position errors with and without a surgical mask in the lateral (1.52 vs 2.07 mm), longitudinal (1.59 vs 1.87 mm), vertical (1.00 vs 1.73 mm), pitch (0.99 vs 0.79°), roll (1.24 vs 0.68°), and yaw (1.58 vs 0.90°) directions were observed at a couch angle of 0°. Most of patient positioning errors were less than 1.0 mm or 1.0° after the couch was rotated to the planned angle for non-coplanar beams. The overall absolute values of the translational and rotational XV position errors with and without the surgical mask were less than 0.5 mm and 0.5°, respectively. This study showed that a thermoplastic mask with a surgical mask is a feasible immobilization technique for brain SRS/SRT patients using the ExacTrac system.
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http://dx.doi.org/10.1002/acm2.13279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8200509PMC
June 2021

Investigation of interfractional variation in lung tumor position under expiratory-phase breath hold using cone-beam computed tomography in stereotactic body radiation therapy.

Med Dosim 2021 May 11. Epub 2021 May 11.

Hiroshima High-Precision Radiotherapy Cancer Center,3-2-2, Futabanosato, Higashi-ku Hiroshima, 732-0057, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi Minami-ku Hiroshima-shi, Hiroshima 734-8553, Japan.

Purpose: We investigated the interfractional variation in the tumor position during lung stereotactic body radiotherapy (SBRT) under expiratory-phase breath hold (BH) using cone-beam computed tomography (CBCT).

Methods: A total of 79 patients with lung cancer were treated with lung SBRT, wherein the Abches system under expiratory-phase BH was used to study interfractional variation. The tumors were located in the upper lobe in 31 cases, in the middle lobe in 11 cases, and in the lower lobe in 37 cases. Planning CTs were scanned under expiratory-phase BH with the Abches system. The 3-degrees-of-freedom (DOF) tumor-based setup using CBCT images under expiratory-phase BH was performed after a 6-DOF bony vertebrae-based setup using an ExacTrac X-ray system. Interfractional variation in the lung tumor position was defined as the difference in the position of the lung tumor relative to the bone anatomy in the left-right (LR), antero-posterior (AP), and craniocaudal (CC) directions represented as absolute values.

Results: The interfractional variation in the lung tumor position was very similar in all the lung regions, and its mean ± standard deviation values in all patients were 1.0 ± 1.1, 1.6 ± 1.9, and 1.6 ± 1.9 mm in the LR, AP, and CC directions, respectively. Further, 99.1%, 92.4%, and 92.7% of all the fractions for the interfractional tumor positional variation in the LR, AP, and CC directions were less than 5 mm, respectively.

Conclusion: The interfractional variation in the tumor position was small for lung cancer patients treated with the Abches system under expiratory-phase BH.
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http://dx.doi.org/10.1016/j.meddos.2021.04.001DOI Listing
May 2021

Survey to detect tick-borne encephalitis virus from human-feeding ticks in Hokkaido, Japan.

J Dermatol 2021 Jul 23;48(7):1094-1097. Epub 2021 Mar 23.

National Research Center for the Control and Prevention of Infectious Diseases (CCPID, Nagasaki University, Nagasaki, Japan.

A tick infestation is one of the most common arthropod-related skin diseases in Hokkaido, the northernmost island of Japan. Ticks also act as an infectious disease vector for humans. Tick-borne encephalitis (TBE), a highly mortal central nervous system infection caused by TBE virus (TBEV), has sporadically occurred there recently. However, there have been no epidemiological data on the current surveillance of human tick bites and the prevalence of TBEV in human-feeding ticks. This study was performed to clarify those indeterminate issues. One hundred and fifty-three ixodid ticks feeding on humans were collected from 150 outpatients in Hokkaido during the season of April to August 2018. None of the cases showed any infectious symptoms. These ticks were morphologically identified to species, and a cytopathic assay on baby hamster kidney cells was carried out to detect TBEV from each tick. The tick collection consisted of 108 Ixodes persulcatus (one nymph and 107 adult females), 44 female Ixodes ovatus, and one female Haemaphysalis japonica. No tick extracts showed positive results of the cytopathic assay, suggesting the non-existence of TBEV in the present specimens. However, the survey to detect TBEV from human-feeding ticks is still important to monitor the occurrence of TBE, because human tick bites by I. ovatus, a possible vector of TBEV, are increasing even in the northern and eastern areas of Hokkaido.
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http://dx.doi.org/10.1111/1346-8138.15865DOI Listing
July 2021

Trematode diversity in freshwater snails from a stopover point for migratory waterfowls in Hokkaido, Japan: An assessment by molecular phylogenetic and population genetic analyses.

Parasitol Int 2021 Aug 20;83:102329. Epub 2021 Mar 20.

Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.

The cryptic diversity of trematodes was evaluated in the Nagayama-Shinkawa River, an artificial canal of the Ishikari River System of Hokkaido, Japan. Numerous migratory waterfowls use the canal as a stopover point in every spring season. The lymnaeid snail, Radix auricularia, and the semisulcospirid snail, Semisulcospira libertina, colonize the static and flowing water areas, respectively. The trematode fauna of the two snails was assessed by molecular phylogenetic and population genetic analyses. Each of distinctive clades in mitochondrial DNA trees was arbitrarily set as a species. In total, 14 species of the families Diplostomidae, Echinostomatidae, Notocotylidae, Plagiorchiidae, and Strigeidae occurred in R. auricularia, wherease S. libertina harbored 10 species of the families Echinochasmidae, Heterophyidae, Notocotylidae, and Lecithodendridae and Cercaria creta, an unclassified species whose adult stage is still unknown. The species diversity of the larval trematodes could be recognized as a "hot spot", suggesting that the seasonal visit of waterfowls is very important to spread trematodes and to keep their diversity. A high intraspecific genetic diversity was observed in the echinostomatid, notocotylid, echinochasmid, and heterophyid species, whose definitive hosts include birds. It seems likely that each of the parasite populations is always disturbed by repeated visits of waterfowls.
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http://dx.doi.org/10.1016/j.parint.2021.102329DOI Listing
August 2021

Notocotylus ikutai n. sp. (Digenea: Notocotylidae) from lymnaeid snails and anatid birds in Hokkaido, Japan.

Parasitol Int 2021 Aug 6;83:102318. Epub 2021 Mar 6.

Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.

An unknown species of the genus Notocotylus (Digenea: Notocotylidae) was found as the larval stage from the lymnaeid snail, Radix auricularia, in a static water area of the Chubetsu River, Hokkaido, the northernmost island of Japan. A DNA barcoding identification system was applied to detect the adult stage. Through the inspection of anatid game birds in Hokkaido, Anas crecca, Anas platyrhynchos, Anas zonorhyncha, and Mareca penelope were demonstrated to serve as the definitive hosts. The detailed morphological features of the species were characterized using adults raised experimentally in immunosuppressed mice and naturally developed larvae in R. auricularia. Although the species is morphologically similar to Notocotylus attenuatus and Notocotylus magniovatus in both adult and larval stages, its taxonomic independence was confirmed by a comprehensive study based on molecular phylogeny, morphology, and ecology. Here we propose Notocotylus ikutai n. sp. for this species. The migratory behavior of the anatid hosts and the North-Eurasian distribution of R. auricularia suggest that the new species is widely distributed in the northern Far East.
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http://dx.doi.org/10.1016/j.parint.2021.102318DOI Listing
August 2021

Frequent infections of mountain stream fish with the amphibian acanthocephalan, Pseudoacanthocephalus toshimai (Acanthocephala: Echinorhynchidae).

Parasitol Int 2021 Apr 1;81:102262. Epub 2020 Dec 1.

Department of Parasitology, Asahikawa Medical University, Midorigaoka-Higashi 2-1, Asahikawa, Hokkaido 078-8510, Japan.

Pseudoacanthocephalus toshimai is an intestinal acanthocephalan parasite of amphibians in Hokkaido, the northernmost island of Japan. In this study, common freshwater fish of the families Salmonidae and Cottidae in mountain streams around the Kamikawa basin of Hokkaido were examined for acanthocephalan infections with P. toshimai. A total of 160 salmonids and 14 cottids were caught in 4 streams by bait fishing during summer and autumn seasons of 2019. Adult acanthocephalans were found only from the salmonids, namely, Salvelinus leucomaenis leucomaenis, Salvelinus malma krascheninnikovi, Oncorhynchus masou, and Oncorhynchus mykiss. The maximum prevalence reached 58.1% in S. leucomaenis, but the mean worm burden was at low levels (e.g., 3.1 in S. leucomaenis and 2.2 in S. malma). All of the acanthocephalans were identified to P. toshimai by morphological observation and DNA barcoding. Although the male acanthocephalans became sexually mature, the females never reached the gravid adult stage, suggesting that salmonids are unsuitable or aberrant hosts for P. toshimai. The infected fish were found exclusively from a small stream with bush, in which a large habitat of amphibians is included. Ligidium japonicum, a terrestrial isopod, collected from the habitat was highly infected with cystacanth larvae of P. toshimai. The observation of fish stomach contents directly demonstrated that small salmonids eat L. japonicum. The terrestrial isopods, which are washed away by rain into a stream, seem to be a source of salmonid infections with P. toshimai. The habitat of intermediate hosts should be emphasized in the taxonomy of the closely related genera Acanthocephalus and Pseudoacanthocephalus.
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http://dx.doi.org/10.1016/j.parint.2020.102262DOI Listing
April 2021

Hybrid volumetric-modulated arc therapy for postoperative breast cancer including regional lymph nodes: the advantage of dosimetric data and safety of toxicities.

J Radiat Res 2020 Sep;61(5):747-754

Hiroshima High-Precision Radiotherapy Cancer Center, 3-2-2, Futabanosato, Higashi-ku, Hiroshima-shi, Hiroshima, 732-0057, Japan.

To improve the homogeneity and conformity of the irradiation dose for postoperative breast cancer including regional lymph nodes, we planned Hybrid volumetric-modulated arc therapy (VMAT), which combines conventional tangential field mainly for the chest area and VMAT mainly for the supraclavicular area and marginal zone. In this study, we compared the dosimetric impact between traditional 3D conformal radiotherapy (3DCRT) and Hybrid VMAT and observed toxicities following Hybrid VMAT. A total of 70 patients indicated between October 2016 and December 2017 were included. The prescribed dose was 50 Gy/25 fractions. For the dosimetric impact, 3DCRT and Hybrid VMAT plans were compared in each patient with respect to the dosimetric parameters. Toxicities were followed using the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up duration was 319 days. For the dosimetric impact, the homogeneity index (HI) and conformity index (CI) of PTV were significantly improved in the Hybrid VMAT plan compared with that in the 3DCRT plan (HI, 0.15 ± 0.07 in Hybrid VMAT vs 0.41 ± 0.19 in 3DCRT, P < 0.001; CI, 1.61 ± 0.44 in Hybrid VMAT vs 2.10 ± 0.56 in 3DCRT, P < 0.001). The mean irradiated ipsilateral lung dose was not significantly different in both plans (12.0 ± 2.4 Gy in Hybrid VMAT vs 11.8 ± 2.8 Gy in 3DCRT, P < 0.533). Regarding toxicity, there were no patients who developed ≥grade 3 acute toxicity and ≥grade 2 pneumonitis during the follow-up. Hybrid VMAT for postoperative breast cancer including regional lymph nodes was a reasonable technique that improved the homogeneity and conformity of the irradiation dose to the planning target volume while keeping the irradiation dose to organs at risk to a minimum.
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http://dx.doi.org/10.1093/jrr/rraa057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7482153PMC
September 2020

Effectiveness of robust optimization in volumetric modulated arc therapy using 6 and 10 MV flattening filter-free beam therapy planning for lung stereotactic body radiation therapy with a breath-hold technique.

J Radiat Res 2020 Jul;61(4):575-585

Hiroshima High-Precision Radiotherapy Cancer Center.

We investigated the feasibility of a robust optimization with 6 MV X-ray (6X) and 10 MV X-ray (10X) flattening filter-free (FFF) beams in a volumetric modulated arc therapy (VMAT) plan for lung stereotactic body radiation therapy (SBRT) using a breath-holding technique. Ten lung cancer patients were selected. Four VMAT plans were generated for each patient; namely, an optimized plan based on the planning target volume (PTV) margin and a second plan based on a robust optimization of the internal target volume (ITV) with setup uncertainties, each for the 6X- and 10X-FFF beams. Both optimized plans were normalized by the percentage of the prescription dose covering 95% of the target volume (D95%) to the PTV (1050 cGy × 4 fractions). All optimized plans were evaluated using perturbed doses by specifying user-defined shifted values from the isocentre. The average perturbed D99% doses to the ITV, compared to the nominal plan, decreased by 369.1 (6X-FFF) and 301.0 cGy (10X-FFF) for the PTV-based optimized plan, and 346.0 (6X-FFF) and 271.6 cGy (10X-FFF) for the robust optimized plan, respectively. The standard deviation of the D99% dose to the ITV were 163.6 (6X-FFF) and 158.9 cGy (10X-FFF) for the PTV-based plan, and 138.9 (6X-FFF) and 128.5 cGy (10X-FFF) for the robust optimized plan, respectively. Robust optimized plans with 10X-FFF beams is a feasible method to achieve dose certainty for the ITV for lung SBRT using a breath-holding technique.
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http://dx.doi.org/10.1093/jrr/rraa026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7336549PMC
July 2020

Brachylaima succini sp. nov. (Trematoda: Brachylaimidae) from Succinea lauta, an amber snail in Hokkaido, Japan.

Parasitol Int 2020 Aug 10;77:102104. Epub 2020 Mar 10.

Faculty of Science, Toho University, Funabashi, Chiba 274-8510, Japan.

Through a continuous survey of trematodes in land snails of Hokkaido, the northernmost island of Japan, we have discovered four species of the genus Brachylaima (Trematode: Brachylaimidae). Among them, Brachylaima ezohelicis, Brachylaima asakawai, and Brachylaima lignieuhadrae have already been described. Each of the three species is a strict specialist in selecting a particular species of land snail as the first intermediate host. In this report, we propose the fourth species, Brachylaima succini sp. nov., based on ecological, morphological, and phylogenetic considerations. Sporocysts and metacercariae of the new species were found exclusively from Succinea lauta, which is known as an amber snail indigenous to Hokkaido. Phylogenetic trees of nuclear 28S rDNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) demonstrated it to be distinct from the other sympatric species. Although metacercariae of the new species possessed unique morphological characters, adult worms experimentally raised from the metacercariae were similar to those of B. ezohelicis and B. lignieuhadrae. Natural definitive hosts of the new species are unknown, but the existence of common cox1 haplotypes from far-distant localities suggests a possibility that birds are involved as the definitive hosts. Findings of amber snails coinfected with both sporocysts of the new species and Leucochloridium perturbatum also support the involvement of birds.
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http://dx.doi.org/10.1016/j.parint.2020.102104DOI Listing
August 2020

Evaluation of interbreath-hold lung tumor position reproducibility with vector volume histogram using the breath-hold technique.

Med Dosim 2020 Autumn;45(3):252-255. Epub 2020 Feb 13.

Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Higashihiroshima, Japan.

Tumor geometric reproducibility for lung stereotactic body radiotherapy (SBRT) is an important issue in the breath-hold (BH) technique. We investigated the inter-BH reproducibility of the tumor position in expiratory BH using our proposed vector volume histogram (VVH) method. Subjects comprising 14 patients with lung cancer who were treated with lung SBRT under expiratory BH conditions were monitored by the Abches system. Multiple computed tomography (CT) scans were performed to evaluate the inter-BH reproducibility of the tumor position at the expiratory BH in the simulation session. Gross tumor volume was delineated by a physician. Deformable image registration was used to deform the images from the 3 expiratory BH-CTs to the treatment planning expiratory BH-CT. To evaluate the inter-BH reproducibility of the tumor positions, we measured the largest motion extent within the organ of 3 dimensions (left-right, LR; anterior-posterior, AP; cranio-caudal, CC) and a 3D vector using the VVH method. The average and standard deviations of the inter-BH reproducibility of the tumor position in the LR, AP, and CC directions, and the 3D vector were 1.7 ± 0.5, 2.0 ± 0.7, 2.1 ± 0.7, and 2.7 ± 0.7 mm, respectively. Ten patients exhibited inter-BH displacements of the lung tumor >3 mm in the 3D vector. No displacement >5 mm was observed in any direction for all patients. Our study indicated that the inter-BH variation of the tumor position was small for lung cancer patients, using the Abches system and the VVH method.
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http://dx.doi.org/10.1016/j.meddos.2020.01.003DOI Listing
July 2021

Development of a CT number calibration audit phantom in photon radiation therapy: A pilot study.

Med Phys 2020 Apr 29;47(4):1509-1522. Epub 2020 Feb 29.

Hiroshima High-Precision Radiotherapy Cancer Center, 3-2-2, Futabanosato, Higashi-ku, Hiroshima, 732-0057, Japan.

Purpose: In photon radiation therapy, computed tomography (CT) numbers are converted into values for mass density (MD) or relative electron density to water (RED). CT-MD or CT-RED calibration tables are relevant for human body dose calculation in an inhomogeneous medium. CT-MD or CT-RED calibration tables are influenced by patient imaging (CT scanner manufacturer, scanning parameters, and patient size), the calibration process (tissue-equivalent phantom manufacturer, and selection of tissue-equivalent material), differences between tissue-equivalent materials and standard tissues, and the dose calculation algorithm applied; however, a CT number calibration audit has not been established. The purposes of this study were to develop a postal audit phantom, and to establish a CT number calibration audit process.

Methods: A conventional stoichiometric calibration conducts a least square fit of the relationships between the MD, material weight, and measured CT number, using two parameters. In this study, a new stoichiometric CT number calibration scheme has been empirically established, using three parameters to harmonize the calculated CT number with the measured CT number for air and lung tissue. In addition, the suitable material set and the minimal number of materials required for stoichiometric CT number calibration were determined. The MDs and elemental weights from the International Commission on Radiological Protection Publication 110 were used as standard tissue data, to generate the CT-MD and CT-RED calibration tables. A small-sized, CT number calibration phantom was developed for a postal audit, and stoichiometric CT number calibration with the phantom was compared to the CT number calibration tables registered in the radiotherapy treatment planning systems (RTPSs) associated with five radiotherapy institutions.

Results: When a least square fit was performed for the stoichiometric CT number calibration with the three parameters, the calculated CT number showed better agreement with the measured CT number. We established stoichiometric CT number calibration using only two materials because the accuracy of the process was determined not by the number of used materials but by the number of elements contained. The stoichiometric CT number calibration was comparable to the tissue-substitute calibration, with a dose difference less than 1%. An outline of the CT number calibration audit was demonstrated through a multi-institutional study.

Conclusions: We established a new stoichiometric CT number calibration method for validating the CT number calibration tables registered in RTPSs. We also developed a CT number calibration phantom for a postal audit, which was verified by the performances of multiple CT scanners located at several institutions. The new stoichiometric CT number calibration has the advantages of being performed using only two materials, and decreasing the difference between the calculated and measured CT numbers for air and lung tissue. In the future, a postal CT number calibration audit might be achievable using a smaller phantom.
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http://dx.doi.org/10.1002/mp.14077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216906PMC
April 2020

Morphological and genetic characterizations of Avitellina tapeworms from domestic ruminants in Senegal: An evidence of specificity among sheep and cattle host.

Vet Parasitol Reg Stud Reports 2019 12 9;18:100337. Epub 2019 Oct 9.

Laboratoire de Biologie Évolutive, d'Écologie et de Gestion des Écosystèmes, Faculté des Sciences et Techniques, Université Cheikh Anta DIOP de Dakar, BP 5005 Dakar, Sénégal.

Avitellina tapeworms are common intestinal parasites of ruminants with a worldwide distribution. In Senegal, only Avitellina centripunctata tapeworm has been reported to date, and genetic diversity was previously confirmed by enzymatic analysis. This study aims to clarify the diversity of Avitellina tapeworms isolated from sheep and cattle in Senegal. In total, 613 adult Avitellina tapeworms were collected from sheep and cattle. Morphological analysis by the light microscopy and scanning electron microscopy identified three Avitellina "morphospecies": A. centripunctata and Avitellina sp.2 were detected in sheep while Avitellina sp.3 was identified in cattle. Molecular phylogenetic analysis based on the complete mitochondrial cytochrome c oxidase subunit 1 gene (cox1) sequences revealed that 101 Avitellina tapeworms were divided into 54 haplotypes grouped into three clades, of which two were specific to sheep and one specific to cattle. Three morphospecies corresponded to each of three clades and the maximum pairwise divergence among the clades ranged from 9.7 to 18.5% in cox1. The present study demonstrates the unexpected diversity of Avitellina tapeworms in domestic ruminants, and emphasize the necessity of re-evaluation of the taxonomy of the genus.
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http://dx.doi.org/10.1016/j.vprsr.2019.100337DOI Listing
December 2019

MRI appearance change during stereotactic radiotherapy for large brain metastases and importance of treatment plan modification during treatment period.

Jpn J Radiol 2019 Dec 15;37(12):850-859. Epub 2019 Oct 15.

Hiroshima High-Precision Radiotherapy Cancer Center, 2-2 Futabanosato Higashi-ku Hiroshima-shi, Hiroshima, 732-0057, Japan.

Purpose: We aimed to evaluate the magnetic resonance imaging (MRI) appearance changes during stereotactic radiotherapy (SRT) for large sized brain metastases, and analyze the lesions necessitating treatment plan modification.

Materials And Methods: A total of 23 patients (27 lesions, >2 cm in tumor diameter) underwent SRT and all lesions were evaluated the appearance changes which had the necessity of the treatment plan modification. The appearance change of tumor during SRT was evaluated using gadolinium-enhanced MRI. The reasons of the modification were classified into tumor reduction, tumor enlargement, displacement, and shape change.

Results: Among the 27 lesions, 55.6% required the treatment plan modification. The reasons were tumor reduction in six lesions, tumor enlargement in three lesions, displacement in three lesions, and shape change in three lesions. The planning target volume (PTV) size changed up to 43.0% and the shift of center of PTV was a maximum of 1.7 mm. The pathological status (adenocarcinoma vs others) and timing of steroid administration (prior vs after SRT start) were the predictive factors of tumor changes required the modification.

Conclusions: As tumor changes might occur even during short period of SRT, the treatment plan evaluation and modification were important in SRT for large brain metastases.
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http://dx.doi.org/10.1007/s11604-019-00886-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874519PMC
December 2019

Brachylaima lignieuhadrae n. sp. (Trematoda: Brachylaimidae) from land snails of the genus Euhadra in Japan.

Parasitol Int 2020 Feb 12;74:101992. Epub 2019 Sep 12.

Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.

Land snails of the genus Euhadra (Gastropoda: Bradybaenidae) are indigenous to the Japanese Archipelago. The larvae of an unknown species, tentatively named as Brachylaima sp. B (Trematoda: Brachylaimidae), have been found from Euhadra brandtii sapporo in Hokkaido, the northernmost island of Japan. In this study, a large-scale snail survey covering a wide area of Japan was conducted to confirm the larval parasite from members of Euhadra and related genera. Sporocysts with cercariae were found only from Eu. brandtii sapporo in Hokkaido and Euhadra callizona in central Honshu at low prevalence (1.0-9.6%). The metacercariae were detected widely from 6 species of Euhadra and the related genera at high prevalence (7.1-100%). A molecular identification by DNA barcoding demonstrated almost all of the larvae to be Brachylaima sp. B. Adult worms experimentally raised from the metacercariae were morphologically most similar to Brachylaima ezohelicis in Hokkaido, but could be differentiated by the microstructure of the tegumental surface. We propose Brachylaima lignieuhadrae n. sp. for the unknown species, based on the morphology, DNA profile, host specificity, and geographic distribution. Phylogeography of the new species suggests a possibility that migratory birds serve as the definitive hosts.
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http://dx.doi.org/10.1016/j.parint.2019.101992DOI Listing
February 2020

Automatic gas detection in prostate cancer patients during image-guided radiation therapy using a deep convolutional neural network.

Phys Med 2019 Aug 21;64:24-28. Epub 2019 Jun 21.

Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Science, Hiroshima University, Hiroshima, Japan.

Purpose: The detection of intestinal/rectal gas is very important during image-guided radiation therapy (IGRT) of prostate cancer patients because intestinal/rectal gas increases the inter- and intra-fractional prostate motion. We propose a deep convolutional neural network (DCNN) to detect intestinal/rectal gas in the pelvic region.

Material And Methods: We selected 300 anterior-posterior kilo-voltage (kV) X-ray images from 30 prostate cancer patients. Thirty images were randomly chosen for a test set, and the remaining 270 images used as the training set. The intestinal/rectal gas was manually delineated on kV X-ray images and segmented. The training images were augmented by applying artificial shifts and fed into a DCNN. The network models were trained to keep the quality of the output image close to the quality of the input image by pooling and upsampling. The training set was used to adjust the parameters of the DCNN, and the test set was used to assess the performance of the model. The performance of the DCNN was evaluated using a fivefold cross-validation procedure. The dice similarity coefficient (DSC) was calculated to evaluate the detection accuracy between the manual contour and auto-segmentation.

Results: The DCNN was trained within approximately 17 min with a time step of 20 s/epoch. The training and validation accuracy of the models after 50epochs were 0.94 and 0.85, respectively. The average ± standard deviation of the DSC for 30 test images was 0.85 ± 0.08.

Conclusions: The proposed DCNN method can automatically detect the intestinal/rectal gas in kV images with good accuracy.
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http://dx.doi.org/10.1016/j.ejmp.2019.06.009DOI Listing
August 2019

A Philophthalmid Eyefluke from a Human in Japan.

J Parasitol 2019 08;105(4):619-623

2   Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.

Philophthalmid eyeflukes are cosmopolitan parasites of birds and occasionally of mammals, including humans. A gravid adult of sp. was found from the bulbar conjunctiva of a 64-yr-old woman in Japan, who was diagnosed with acute conjunctivitis. The parasite was morphologically most similar to , but distinctive in lacking an esophagus and in having clearly lobed testes. The DNA sequence analysis of genes for nuclear ribosomal RNA and mitochondrial cytochrome oxidase subunit 1 supported the identification at generic level. The morphological and molecular analyses strongly suggest that the eyefluke from a human in Japan should be treated as an undescribed species of . The occurrence of human philophthalmosis is very rare. As far as we know, a total of 11 human cases have been reported worldwide to date.
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August 2019

Infection status of commercial fish with cystacanth larvae of the genus Corynosoma (Acanthocephala: Polymorphidae) in Hokkaido, Japan.

Int J Food Microbiol 2019 Sep 21;305:108256. Epub 2019 Jun 21.

Department of Parasitology, Asahikawa Medical University, Asahikawa, Hokkaido 078-8510, Japan.

Acanthocephalans of the genus Corynosoma are known as intestinal parasites, mainly of pinnipeds. Human corynosomiasis has been reported as an infrequent foodborne disease in Hokkaido, the northernmost island of Japan. Potential sources of the human infection are marine fish, because they are paratenic hosts of these parasites. In this study, the prevalence and intensity of larval Corynosoma in commercial fish from 17 fishing ports of Hokkaido were examined from April 2016 to January 2019. Out of a total of 1217 fish examined, 122 (10.0%) were infected with cystacanth larvae. The infected fish assemblage was composed of 7 families and 13 species from all the coastal seas of Hokkaido (the Pacific Ocean, Okhotsk Sea, and Japan Sea), showing that commercial fish can be source of human infection when eaten raw. Flatfish of the family Pleuronectidae showed the highest intensity of cystacanths, ranging from 1 to 56. A DNA barcoding system was developed in this study, based on the standard mitochondrial cox1 sequences of morphologically identified adults of Corynosoma spp. from pinnipeds in Hokkaido. By using the DNA barcoding, most of the fish-derived cystacanths were identified as either C. strumosum or C. villosum, and furthermore, a clinical isolate from human as C. villosum. Both of the species were commonly detected from various fish of Hokkaido, irrespective of the coastal seas. Flatfish frequently harbored C. villosum. Considering the wide range of commercial fish in Hokkaido and the advanced transportation system of fresh fish, there is a possibility that human corynosomiasis will occur everywhere in Japan.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2019.108256DOI Listing
September 2019

Distribution records of three species of Leucochloridium (Trematoda: Leucochloridiidae) in Japan, with comments on their microtaxonomy and ecology.

Parasitol Int 2019 Oct 31;72:101936. Epub 2019 May 31.

School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.

Insectivorous birds serve as definitive hosts for trematodes of the genus Leucochloridium. The parasites exclusively use amber snails of the family Succineidae as intermediate hosts. A pulsating and colorful display of the larval broodsac in the snail's eyestalk seems to be a caterpillar mimic for attracting birds. A colored design of the broodsac is very useful for parasite identification. In Japan, characteristic broodsacs from amber snails have been recorded from 1980's, but their taxonomic discrimination from Asian, European, and North American species has not been achieved. In this study, old scientific records, sighting information on broodsacs from the general public, and direct molecular evidence by DNA barcoding clearly showed that at least three species of Leucochloridium are distributed in Japan. A vertical-striped broodsac found from Succinea sp. in Okinawa, the subtropical island of Japan, were treated as Leucochloridium sp., but being almost identical to that of Leucochloridium passeri in neighboring Taiwan. The European species of Leucochloridium perturbatum and Leucochloridium paradoxum were frequently detected from Succinea lauta in Hokkaido, the northernmost island of Japan. The former species was common in inland areas of Hokkaido, whereas the latter species was frequently seen in the coastal areas. A possible explanation for the parasite distribution pattern is that principal definitive hosts (migratory or resident birds) differ in each parasite. The conspecificity of Leucochloridium variae in North America and L. perturbatum in Europe and the Far East is also discussed.
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http://dx.doi.org/10.1016/j.parint.2019.101936DOI Listing
October 2019

Tolerance levels of mass density for CT number calibration in photon radiation therapy.

J Appl Clin Med Phys 2019 Jun 13;20(6):45-52. Epub 2019 May 13.

Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan.

Computed tomography (CT) data are required to calculate the dose distribution in a patient's body. Generally, there are two CT number calibration methods for commercial radiotherapy treatment planning system (RTPS), namely CT number-relative electron density calibration (CT-RED calibration) and CT number-mass density calibration (CT-MD calibration). In a previous study, the tolerance levels of CT-RED calibration were established for each tissue type. The tolerance levels were established when the relative dose error to local dose reached 2%. However, the tolerance levels of CT-MD calibration are not established yet. We established the tolerance levels of CT-MD calibration based on the tolerance levels of CT-RED calibration. In order to convert mass density (MD) to relative electron density (RED), the conversion factors were determined with adult reference computational phantom data available in the International Commission on Radiological Protection publication 110 (ICRP-110). In order to validate the practicability of the conversion factor, the relative dose error and the dose linearity were validated with multiple RTPSes and dose calculation algorithms for two groups, namely, CT-RED calibration and CT-MD calibration. The tolerance levels of CT-MD calibration were determined from the tolerance levels of CT-RED calibration with conversion factors. The converted RED from MD was compared with actual RED calculated from ICRP-110. The conversion error was within ±0.01 for most standard organs. It was assumed that the conversion error was sufficiently small. The relative dose error difference for two groups was less than 0.3% for each tissue type. Therefore, the tolerance levels for CT-MD calibration were determined from the tolerance levels of CT-RED calibration with the conversion factors. The MD tolerance levels for lung, adipose/muscle, and cartilage/spongy-bone corresponded to ±0.044, ±0.022, and ±0.045 g/cm , respectively. The tolerance levels were useful in terms of approving the CT-MD calibration table for clinical use.
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http://dx.doi.org/10.1002/acm2.12601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6560312PMC
June 2019

Volumetric modulated arc therapy with robust optimization for larynx cancer.

Phys Med 2019 Feb 25;58:54-58. Epub 2019 Jan 25.

Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Science, Hiroshima University, Hiroshima, Japan.

Purpose: The aim of this study was to perform a comparison between robust optimization and planning target volume (PTV)-based optimization plans using volumetric modulated arc-therapy (VMAT) by evaluating perturbed doses induced by localization offsets for setup uncertainties in larynx cancer radiation therapy.

Methods: Ten patients with early-stage (T1-2N0) glottis carcinoma were selected. The clinical target volume (CTV), carotid arteries, and spinal cord were contoured by a radiation oncologist. PTV-based and robust optimization plans were normalized at D to the PTV and D to the CTV, respectively. Both optimization plans were evaluated using perturbed doses by specifying user defined shifted values from the isocenter. CTV dose (D, D, and D), homogeneity index (HI) and conformity index (CI, CI, and CI), as well as doses to the carotid arteries and spinal cord were compared between PTV-based and robust optimization plans.

Results: The robust optimization plans exhibited superior CTV coverage and a reduced dose to the carotid arteries compared to the PTV-based optimization plans (p < 0.05). HI, CI and the dose to the spinal cord did not significantly differ between the PTV-based and robust optimization plans (p > 0.05). The robust optimization plans showed better CI and CI compared to the PTV-based optimization plans (p < 0.05). Plan perturbed evaluations showed that the robust optimization plan has small variations in the doses to the CTV, carotid arteries, and spinal cord compared to the PTV-based optimization plan.

Conclusions: The robust optimization plan may be a suitable treatment method in radiotherapy for larynx cancer patient.
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http://dx.doi.org/10.1016/j.ejmp.2019.01.012DOI Listing
February 2019

Comparison of the intestinal helminth community of the large Japanese field mouse (Apodemus speciosus) between urban, rural, and natural sites in Hokkaido, Japan.

Parasitol Int 2019 Jun 1;70:51-57. Epub 2019 Feb 1.

Graduate School of Environmental Science, Hokkaido University, N10W5, Sapporo, Hokkaido 060-0810, Japan; Faculty of Environmental Earth Science, Hokkaido University, N10W5, Sapporo, Hokkaido 060-0810, Japan.

Anthropogenic ecosystem modification has affected over 80% of the global land cover. Interest in its effects on wildlife has been growing over the past several decades, specifically in regard to biodiversity and ecosystem function. Parasites are of particular interest, because they directly impact animal health, and can be transmitted to humans through the process of zoonosis. However, most studies so far tended to focus on only one or two parasites with few looking at the entire community, thereby limiting our understanding of the effects of ecosystem modification on parasitic organisms. In this study, we estimated the intestinal helminth diversity and species richness of the large Japanese field mouse (Apodemus speciosus), as well as the prevalence and abundance of each species in two modified ecosystems, a rural agricultural area and an urban park. We then compared them to a natural area to see how they have been altered. We found that diversity, prevalence, and abundance were all highly altered within both modified ecosystems, but generally to a greater degree within the urban park. However, there was great variation in the direction and degree of response of each helminth species, suggesting that generalized trends may be difficult to ascertain. Furthermore, it is important to analyze the entire helminth community, because interspecific interactions and the effect that ecosystem modification has on them may help determine what species persist.
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http://dx.doi.org/10.1016/j.parint.2019.02.001DOI Listing
June 2019

A case of small bowel obstruction due to infection with Bolbosoma sp. (Acanthocephala: Polymorphidae).

Parasitol Int 2019 Feb 2;68(1):14-16. Epub 2018 Oct 2.

Department of Infectious Disease Control, Department of Biomedicine, Faculty of Medicine, Oita University, Oita, Japan.

A case of small bowel obstruction caused by Bolbosoma sp. infection is reported. A 27-year-old woman admitted with abdominal pain was diagnosed as small bowel obstruction. Laparoscopic surgery revealed induration in jejunum at ca. 120 cm distal to the ligament of Treiz, attributed to a band connecting the serosa to the ascending mesocolon. Resected band contained an acanthocephalan accompanying foreign body reaction with abscess formation. The parasite belonged to the genus Bolbosoma, of which identification was made by DNA sequence analysis. This is the eighth case of Bolbosoma infection in humans, and the first one causing an ileus.
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http://dx.doi.org/10.1016/j.parint.2018.09.007DOI Listing
February 2019

MOLECULAR AND MORPHOLOGICAL DISCRIMINATION OF DICROCOELIID LARVAE (TREMATODA: DIGENEA) FROM TERRESTRIAL MOLLUSKS IN JAPAN.

J Parasitol 2018 Aug 29. Epub 2018 Aug 29.

* Meguro Prasitological Museum Meguro Prasitological Museum.

Trematodes of the family Dicrocoeliidae commonly use terrestrial mollusks as the first intermediate host. Despite the abundant studies on the adult worms in birds and mammals, few reports exist on their larval stage in snail intermediate hosts. A present survey of mollusks in Japan led us to the discovery of dicrocoeliid sporocysts with cercariae in 16 out of 303 individuals, encompassing eight snail species and one slug species. A DNA barcoding based on sequencing of mitochondrial cytochrome c oxidase subunit 1 showed that the larvae consisted of five species. Phylogenetic trees of nuclear 18S and 28S ribosomal DNAs confirmed the five species to be members of the Dicrocoeliidae. These were temporarily termed dicrocoeliid spp. 1 to 5, since conclusive identification was impossible without adult worms. These unknown species were phylogenetically related to each other, except sp. 5. The phylogenetic trees demonstrated close genetic relationships between sp. 3 and the genus Lutztrema, and between sp. 5 and the genus Lyperosomum. The phylogenetic analysis also suggested that a division into the subfamilies Dicrocoeliinae and Leipertrematinae is a wrong classification due to the paraphyly of the Dicrocoeliinae. Morphological characterization of the cercariae and their DNA barcodes provide a primary platform for differentiating dicrocoeliids from various mollusks in Japan. The DNA barcodes, in particular, will enable tracing the parasite life cycles, in case of finding metacercariae and adults from presently unknown hosts.
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http://dx.doi.org/10.1645/18-24DOI Listing
August 2018

Brachylaima asakawai sp. nov. (Trematoda: Brachylaimidae), a rodent intestinal fluke in Hokkaido, Japan, with a finding of the first and second intermediate hosts.

Parasitol Int 2018 10 27;67(5):565-574. Epub 2018 Apr 27.

Mie University Graduate School, Faculty of Bioresources, Tsu, Mie 514-8507, Japan.

In the 1970's and 1980's, an unknown species of the genus Brachylaima (Trematoda: Brachylaimidae) had been recorded from the intestines of Rattus norvegicus and Apodemus speciosus in Hokkaido, Japan. The rodent fluke was characteristic in extending a bilateral vitellarium till the level of posterior margin of anterior testis and in keeping almost the same-sized spherical ovary and testes. In this study, the rodent fluke was rediscovered from A. speciosus, Apodemus argenteus, and Myodes rufocanus in Hokkaido. The resultant parasite collection enabled us to make a mitochondrial DNA (mtDNA) barcode for tracking its intermediate hosts. The metacercaria of the rodent fluke was detected frequently from the kidney of three species of land snails (Discus pauper, Succinea lauta, and Ainohelix editha). However, its sporocyst with cercariae was found only from the hepatopancreas of D. pauper, a fairly small snail. The wide-spectrum of the second intermediate host seems to increase the chance of transmitting the parasite to various mammals and birds. The use of indigenous land snails as the first and second intermediate hosts, the distinctiveness of the mtDNA sequence, and the characteristic morphology of all the developmental stages prompted us to propose Brachylaima asakawai sp. nov. for the rodent intestinal fluke in Hokkaido. The present field survey suggests that the life cycle of the new species is primarily dependent on a predator-prey relationship between rodents and D. pauper.
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http://dx.doi.org/10.1016/j.parint.2018.04.010DOI Listing
October 2018

Morphological and molecular evidence for a new species of the genus Cosmocercoides Wilkie, 1930 (Ascaridida: Cosmocercidae) from the Asiatic toad Bufo gargarizans Cantor (Amphibia: Anura).

Parasitol Res 2018 Jun 21;117(6):1857-1864. Epub 2018 Apr 21.

Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology of Hebei Province, College of Life Sciences, Hebei Normal University, 20 East Road of 2nd South Ring, Yuhua District, Shijiazhuang, 050024, Hebei Province, People's Republic of China.

A new cosmocercid species, Cosmocercoides qingtianensis sp. n., collected from the intestine of the Asiatic toad Bufo gargarizans Cantor (Amphibia: Anura) is described using integrated approaches, including light and scanning electron microscopy, and sequencing and analyzing the ribosomal [small ribosomal DNA (18S) and internal transcribed spacer (ITS)] and mitochondrial [cytochrome c oxidase subunit 1 (cox1)] target regions, respectively. The new species can be distinguished from its congeners by the combination of the following morphological characters, including the large body size, the presence of lateral alae and somatic papillae in both sexes, the length of spicules, the particular morphology and length of gubernaculum, the number, arrangement and morphology of caudal rosettes, the presence of large medioventral precloacal papilla and the long tail. Our molecular analysis revealed the level of intraspecific genetic variation of C. qingtianensis sp. n. distinctly lower than that of the interspecific genetic variation in the ITS and cox1 regions. However, there are some overlaps in the range of intra- and interspecific 18S sequence divergence between the new species and some closely related species. The results of molecular analysis supported the validity of the new species based on the morphological observations. The 18S, ITS, and cox1 regions of C. pulcher collected from Bufo japonicus formosus in Japan were also sequenced and analyzed. The results showed a low level of intraspecific genetic variation in 18S and ITS regions (0-0.12% and 0-0.23% nucleotide differences, respectively), but a relatively high level of intraspecific genetic variation in cox1 region (0.78-4.69% nucleotide differences). In addition, it seems more powerful and practical to use the cox1 region as a genetic marker for the accurate identification and differentiation of species of Cosmocercoides than the 18S and ITS regions, especially for the closely related species.
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http://dx.doi.org/10.1007/s00436-018-5877-8DOI Listing
June 2018

Genetic and morphological characterization of Thysaniezia tapeworms from cattle and sheep in Senegal.

Vet Parasitol Reg Stud Reports 2018 01 21;11:27-31. Epub 2017 Nov 21.

Department of Parasitology, Asahikawa Medical University, Asahikawa 078-8510, Japan.

Genetic and morphological diversity of Thysaniezia tapeworms from cattle and sheep in Senegal was investigated using light and scanning microscopic observations and molecular analysis based on mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear small subunit ribosomal RNA gene (SSU rDNA). A total of 52 adult tapeworms were collected from sheep and cattle. Although the tapeworms of the two hosts were morphologically very close, phylogenetic analysis based on cox1 and SSU rDNA gene sequences showed that they were divided into two clades corresponding each to a host. The maximum pairwise divergence between the clades were 12.1% in cox1 and 2.9% in SSU rDNA, indicating they are distinct species. The tapeworms collected from sheep were morphologically identified as Thysaniezia ovilla, a cosmopolitan species in domestic ruminants. Detailed morphological observations revealed a consistent difference between the tapeworms obtained from sheep and those from cattle. The latter were identified as Thysaniezia connochaeti. The present study highlights presence of two species of Thysaniezia among domestic ruminants in Senegal: T. ovilla specific to sheep and T. connochaeti specific to cattle. Our work is the first report of T. connochaeti from domestic animals.
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http://dx.doi.org/10.1016/j.vprsr.2017.11.008DOI Listing
January 2018
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