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Dive into the research topics where Hikaru Watarai is active.

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Featured researches published by Hikaru Watarai.


The Annals of Thoracic Surgery | 2014

Slip knot bronchial ligation method for thoracoscopic lung segmentectomy.

Hiroyuki Oizumi; Hirohisa Kato; Makoto Endoh; Takashi Inoue; Hikaru Watarai; Mitsuaki Sadahiro

We report a novel monofilament slip knot technique for bronchial ligation and for visualization of the anatomic plane during lung segmentectomy. After threading the bronchus, a slip knot is made outside the thorax. During lung ventilation, one end of the string is pulled, and the knot slips to reach the bronchus without a knot-pusher. Bronchial ligation is then performed to block the outflow of segmental air while the segment remains expanded, whereas the other segments become collapsed. This technique allows identification of the anatomic intersegmental plane, facilitating thoracoscopic anatomic lung segmentectomy.


Oncotarget | 2016

The novel JNK inhibitor AS602801 inhibits cancer stem cells in vitro and in vivo.

Masashi Okada; Kenta Kuramoto; Hiroyuki Takeda; Hikaru Watarai; Hirotsugu Sakaki; Shizuka Seino; Manabu Seino; Shuhei Suzuki; Chifumi Kitanaka

A phase 2 clinical trial investigating the efficacy and safety of AS602801, a newly developed JNK inhibitor, in the treatment of inflammatory endometriosis is complete. We are now examining whether AS602801 acts against human cancer cells in vitro and in vivo. In vitro, AS602801 exhibited cytotoxicity against both serum-cultured non-stem cancer cells and cancer stem cells derived from human pancreatic cancer, non-small cell lung cancer, ovarian cancer and glioblastoma at concentrations that did not decrease the viability of normal human fibroblasts. AS602801 also inhibited the self-renewal and tumor-initiating capacity of cancer stem cells surviving AS602801 treatment. Cancer stem cells in established xenograft tumors were reduced by systemic administration of AS602801 at a dose and schedule that did not adversely affect the health of the tumor-bearing mice. These findings suggest AS602801 is a promising anti-cancer stem cell agent, and further investigation of the utility of AS602801 in the treatment of cancer seems warranted.


Interactive Cardiovascular and Thoracic Surgery | 2013

Port-access thoracoscopic anatomical lung subsegmentectomy

Hirohisa Kato; Hiroyuki Oizumi; Takashi Inoue; Eiichi Oba; Nakamura K; Jun Hayashi; Hikaru Watarai; Takumi Yasumoto; Mitsuaki Sadahiro

OBJECTIVES The diagnosis of small lung nodules has increased in recent years; limited resection and minimally invasive surgery are highly desirable in patients with these lesions. While wedge resection may be curative for small lung nodules, the technique is sometimes difficult to perform when the tumour nodule is near the pulmonary hilum. In such situations, either anatomical segmentectomy or subsegmentectomy can obtain an adequate surgical margin; port-access thoracoscopic surgery is the preferred type of minimally invasive surgery. Three-dimensional (3D) computed tomography (CT) simulations are reportedly useful in planning and performing thoracoscopic surgery. We use 3D CT simulation to aid thoracoscopic segmentectomy for small lung nodules and subsegmentectomy for even smaller nodules and conduct here a retrospective evaluation of the clinical results of subsegmentectomy. We present our technique for 3D CT simulation-assisted port-access thoracoscopic subsegmentectomy in the superior segment of the left lower lobe. METHODS Between July 2008 and June 2012, 15 patients underwent port-access thoracoscopic subsegmentectomy. We evaluated the pathological diagnoses, the tumour sizes, the indications, the operative times and the volumes of blood loss. RESULTS Seven patients were diagnosed with lung cancer (LC) and eight had metastatic lung tumours (MLT). The median tumour size was 12 mm. The indication for using this surgical technique was to secure surgical margins in 13 patients (LC, 6; MLT, 7) and because of poor surgical risk in two patients (LC, 1; MLT, 1). The mean surgical time was 166 min and the median blood loss was 19 ml. There were no recurrences. CONCLUSIONS Port-access thoracoscopic lung subsegmentectomy using 3D CT simulation can be safely performed and is able to secure adequate surgical margins.


Annals of cardiothoracic surgery | 2014

Techniques to define segmental anatomy during segmentectomy

Hiroyuki Oizumi; Hirohisa Kato; Makoto Endoh; Takashi Inoue; Hikaru Watarai; Mitsuaki Sadahiro

Pulmonary segmentectomy is generally acknowledged to be more technically complex than lobectomy. Three-dimensional computed tomography (3D CT) angiography is useful for understanding the pulmonary arterial and venous branching, as well as planning the surgery to secure adequate surgical margins. Comprehension of the intersegmental and intrasegmental veins makes the parenchymal dissection easier. To visualize the segmental border, creation of an inflation-deflation line by using a method of inflating the affected segment has become the standard in small-sized lung cancer surgery. Various modifications to create the segmental demarcation line have been devised to accurately perform the segmentectomy procedure.


The Journal of Thoracic and Cardiovascular Surgery | 2017

Posterior approach to thoracoscopic pulmonary segmentectomy of the dorsal basal segment: A single-institute retrospective review

Makoto Endoh; Hiroyuki Oizumi; Hirohisa Kato; Jun Suzuki; Hikaru Watarai; Toshiaki Masaoka; Mitsuaki Sadahiro

Objective: Anatomic resection of the dorsal area of the basal segment of the lower lobe is difficult because of the deep location of vessels and bronchi in the parenchyma. This study aimed to describe a novel technique for port‐access thoracoscopic segmentectomy of the dorsal (S10) and lateral dorsal segments (S9+10). Methods: This retrospective study analyzed 20 patients who underwent S10 and S9+10 thoracoscopic segmentectomy via a posterior approach between January 2004 and March 2016. In this approach, the lung parenchyma between S6 and S10 was divided along V6b,c from the dorsal side of the lower lobe, which exposed the targeted bronchus (B10, B9+10) and artery (A10, A9+10) and enabled anatomic S10 and S9+10 segmentectomy. Results: Of the 20 patients, 15 had lung cancer, 3 had metastases, and 2 had benign nodules. The number of segmentectomies of the right S10, right S9+10, left S10, and left S9+10 was 5, 5, 1, and 9, respectively. Median operative time was 165 minutes (range, 107‐276 minutes). The median duration of chest tube insertion was 1 day (range, 1‐2 days). One patient had atelectasis. Median hospital stay was 6 days (range, 3‐11 postoperative days). No recurrence or mortality was observed during the median follow‐up period of 46 months. Conclusions: The posterior approach for port‐access thoracoscopic segmentectomy at S10 or S9+10 is technically challenging, but in our hands it has been feasible. It exposes the targeted bronchus (B10, B9+10) and artery (A10, A9+10) and enables anatomic S10 and S9+10 segmentectomy while avoiding inessential parenchymal splitting from the major fissure.


Interactive Cardiovascular and Thoracic Surgery | 2017

Thoracoscopic anatomical lung segmentectomy using 3D computed tomography simulation without tumour markings for non-palpable and non-visualized small lung nodules

Hirohisa Kato; Hiroyuki Oizumi; Jun Suzuki; Akira Hamada; Hikaru Watarai; Mitsuaki Sadahiro

OBJECTIVES Although wedge resection can be curative for small lung tumours, tumour marking is sometimes required for resection of non-palpable or visually undetectable lung nodules as a method for identification of tumours. Tumour marking sometimes fails and occasionally causes serious complications. We have performed many thoracoscopic segmentectomies using 3D computed tomography simulation for undetectable small lung tumours without any tumour markings. The aim of this study was to investigate whether thoracoscopic segmentectomy planned with 3D computed tomography simulation could precisely remove non-palpable and visually undetectable tumours. METHODS Between January 2012 and March 2016, 58 patients underwent thoracoscopic segmentectomy using 3D computed tomography simulation for non-palpable, visually undetectable tumours. Surgical outcomes were evaluated. RESULTS A total of 35, 14 and 9 patients underwent segmentectomy, subsegmentectomy and segmentectomy combined with adjacent subsegmentectomy, respectively. All tumours were correctly resected without tumour marking. The median tumour size and distance from the visceral pleura was 14 ± 5.2 mm (range 5-27 mm) and 11.6 mm (range 1-38.8 mm), respectively. Median values related to the procedures were operative time, 176 min (range 83-370 min); blood loss, 43 ml (range 0-419 ml); duration of chest tube placement, 1 day (range 1-8 days); and postoperative hospital stay, 5 days (range 3-12 days). Two cases were converted to open thoracotomy due to bleeding. Three cases required pleurodesis for pleural fistula. No recurrences occurred during the mean follow-up period of 44.4 months (range 5-53 months). CONCLUSIONS Thoracoscopic segmentectomy using 3D computed tomography simulation was feasible and could be performed to resect undetectable tumours with no tumour markings.


Oncology Reports | 2016

Time-staggered inhibition of JNK effectively sensitizes chemoresistant ovarian cancer cells to cisplatin and paclitaxel.

Manabu Seino; Masashi Okada; Hirotsugu Sakaki; Hiroyuki Takeda; Hikaru Watarai; Shuhei Suzuki; Shizuka Seino; Kenta Kuramoto; Tsuyoshi Ohta; Satoru Nagase; Hirohisa Kurachi; Chifumi Kitanaka

Ovarian cancer is the most lethal gynecological malignancy, for which platinum- and taxane-based chemotherapy plays a major role. Chemoresistance of ovarian cancer poses a major obstacle to the successful management of this devastating disease; however, effective measures to overcome platinum and taxane resistance are yet to be established. In the present study, while investigating the mechanism underlying the chemoresistance of ovarian cancer, we found that JNK may have a key role in the resistance of ovarian cancer cells to cisplatin and paclitaxel. Importantly, whereas simultaneous application of a JNK inhibitor and either of the chemotherapeutic agents had contrasting effects for cisplatin (enhanced cytotoxicity) and paclitaxel (decreased cytotoxicity), JNK inhibitor treatment prior to chemotherapeutic agent application invariably enhanced the cytotoxicity of both drugs, suggesting that the basal JNK activity is commonly involved in the chemoresistance of ovarian cancer cells to cisplatin and paclitaxel in contrast to drug‑induced JNK activity which may have different roles for these two drugs. Furthermore, we confirmed using non-transformed human and rodent fibroblasts that sequential application of the JNK inhibitor and the chemotherapeutic agents did not augment their toxicity. Thus, our findings highlight for the first time the possible differential roles of the basal and induced JNK activities in the chemoresistance of ovarian cancer cells and also suggest that time‑staggered JNK inhibition may be a rational and promising strategy to overcome the resistance of ovarian cancer to platinum- and taxane-based chemotherapy.


Journal of Visceral Surgery | 2017

Thoracoscopic wedge resection and segmentectomy for small-sized pulmonary nodules

Hirohisa Kato; Hiroyuki Oizumi; Jun Suzuki; Akira Hamada; Hikaru Watarai; Kenta Nakahashi; Mitsuaki Sadahiro

With the recent increase in the detection of small-sized lung nodules because of the widespread use of computed tomography (CT), limited resection and minimally invasive surgery are preferred by patients with these lesions. In particular, the detection of nodules that show ground-glass opacity during high-resolution CT has increased. Although lobectomy and lymph node dissection were the standard procedures used for treating lung cancer, limited wedge resection and segmentectomy have become acceptable for treating small-sized lung cancers with nodules showing ground-glass opacity. These limited procedures are widely performed, especially because they can be accomplished thoracoscopically. Furthermore, not only simple segmentectomy but also complex segmentectomy and subsegmentectomy can be performed using three-dimensional (3D)-CT to achieve sufficient resection based on tumor size. There are, however, technical difficulties in thoracoscopic wedge resection and segmentectomy. While it may be curative for small-sized lung nodules, it is sometimes difficult to correctly perform wedge resection when the tumor is not identified intraoperatively. In such cases, we usually perform tumor marking before operating. However, serious complications, such as cerebral air embolism, have been reported. Further, although it can sufficiently resect small-sized lung nodules, segmentectomy is more technically complex than wedge resection. Therefore, we have developed methods to overcome these technical difficulties. By using a hookwire method in a hybrid operating room and 3D-CT simulation for each wedge resection and segmentectomy, we have obtained good outcomes. Limited resection individualized for each patient will continue to evolve with applications such as CT.


Journal of Pediatric Surgery | 2016

Removal of foreign bodies from the respiratory tract of young children: Treatment outcomes using newly developed foreign-body grasping forceps

Makoto Endoh; Hiroyuki Oizumi; Naoki Kanauchi; Hirohisa Kato; Hiroshi Ota; Jun Suzuki; Hikaru Watarai; Megumi Nakamura; Mitsuaki Sadahiro

BACKGROUND Although a foreign body in the airway of children constitutes a medical emergency, most available therapeutic tools are insufficient, and treatment can be difficult. Herein, we evaluated the outcomes of various treatment methods of foreign body removal from the respiratory tract. METHODS We retrospectively analyzed 24 children (13 boys, 11 girls; median age, 18months [range, 9-60months]) treated for airway foreign bodies from January 1994 to December 2013 by examining their preoperative diagnoses and anesthesia and surgical methods. RESULTS The foreign body was a peanut, green soybean, almond, chestnut, dental prosthesis, and bead in 15, 3, 3, 1, 1, and 1 cases, respectively. General anesthesia was used in all cases, and flexible bronchoscopy was performed under airway maintenance using a laryngeal mask in 23 cases. The mean operation time was 51±32min. Grasping forceps, basket forceps, and a Fogarty catheter were used in 14, 7, and 2 cases, respectively. In July 2003, 3-pronged foreign-body grasping forceps with a 2.0-mm diameter designed for use with a thin bronchoscope were introduced. Of 16 treated cases, 9 were successfully treated with only forceps. The mean operation time was significantly shortened to 38±24min (range, 7-91min) compared to the traditional operation time of 82±42min (range, 23-147min) (p=0.01). CONCLUSIONS These novel forceps are useful for reducing the operation time and are suitable for removing airway foreign bodies from children with a narrow tracheobronchial caliber.


The Journal of Thoracic and Cardiovascular Surgery | 2013

Three-dimensional computed tomography image overlay facilitates thoracoscopic trocar placement

Hiroyuki Oizumi; Hirohisa Kato; Hikaru Watarai; Mitsuaki Sadahiro

FIGURE 1. The thoracic cage and affected lung were projected onto the body formance of a thoracoscopic anatomic left lateral and posterior basal segmente From the Second Department of Surgery, Faculty of Medicine, Yamagata University, Yamagata, Japan. Disclosures: Authors have nothing to disclose with regard to commercial support. Received for publication Aug 4, 2012; revisions received Feb 9, 2013; accepted for publication April 18, 2013; available ahead of print June 13, 2013. Address for reprints: Hiroyuki Oizumi, MD, PhD, Second Department of Surgery, Yamagata University, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan (E-mail: hohizumi@med.id.yamagata-u.ac.jp). J Thorac Cardiovasc Surg 2013;146:720-1 0022-5223/

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