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Dive into the research topics where Hirotaka Niwa is active.

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Featured researches published by Hirotaka Niwa.


Journal of Gastroenterology | 2007

Coagulation disorder as a prognostic factor for patients with colorectal perforation

Kazushige Kawai; Takeyuki Hiramatsu; Ryo Kobayashi; Naoki Takabayashi; Yukio Ishihara; Ko Ohata; Hirotaka Niwa; Junji Yasuike; Hiroki Tanaka; Mitsutoshi Kimura; Junichi Shindoh

BackgroundAlthough sepsis after surgery for colorectal perforation frequently results in severe coagulation disorders and consequent death of the patient, the correlation between coagulation abnormalities and postoperative mortality of colorectal perforation has not been clarified.MethodsThe medical records of 101 consecutive patients receiving surgery for colorectal perforations between January 1994 and July 2006 were retrospectively reviewed. The abnormalities of preoperative laboratory data reflecting coagulation disorders and other possible risk factors were analyzed by univariate and multivariate analysis.ResultsProlonged prothrombin time and activated partial thromboplastin time significantly correlated with a poor prognosis (both P < 0.001). Among the several risk factors analyzed, only the presence of coagulation disorders was an independent predictive factor of postoperative mortality.ConclusionsProlonged prothrombin time and activated partial thromboplastin time are useful prognostic factors for predicting the surgical outcome for patients with colorectal perforation.


World Journal of Surgery | 2005

Role of Ganglion Cells in Sigmoid Volvulus

Yoshitaka Furuya; Hiroshi Yasuhara; Hironobu Yanagie; Shuji Naka; Tomohiro Takenoue; Hiroki Shinkawa; Hirotaka Niwa; Tsuyoshi Kikuchi; Toshitaka Nagao

The aim of this study was to clarify the role of ganglion cells in the development and recurrence of sigmoid volvulus. We analyzed 9 samples obtained from 9 patients who had undergone sigmoidectomy for sigmoid volvulus, and, for comparison, 18 samples from 18 patients who had undergone sigmoidectomy or low anterior resection for rectal cancer. Neuron-specific enolase was used for immunohistochemical staining to detect ganglion cells, and the number of ganglion cells in 20 contiguous fields was counted at 200? magnification. The average number of ganglion cells per 1000 cm3 was corrected using the ratio of the circumference of the resected sigmoid colon to the average circumference in the control group.The raw numbers of ganglion cells in the Meissner’s and Auerbach’s plexuses in the volvulus group were significantly lower than those in the non-volvulus group (Meissner: p = 0.017, Auerbach: p = 0.007). The circumference of the resected sigmoid colons with volvulus was greater than that of those without volvulus (p = 0.00013). There was no significant difference in the corrected numbers of ganglion cells in the Meissner’s plexus or Auerbach’s plexus per 1000 cm3 between the volvulus and non-volvulus groups (Meissner: p = 0.410, Auerbach: p = 0.890).Furthermore, there was no significant difference in the corrected numbers of ganglion cells between the revolvulus and non-revolvulus groups. These findings led us to conclude that functional disorder of bowel movement or elongation of the bowel in sigmoid volvulus or revolvulus is not related to the number of ganglion cells in Auerbach’s or Meissner’s plexus.


Hepato-gastroenterology | 2011

Diagnostic power of inflammatory markers in predicting severity of appendicitis.

Junichi Shindoh; Hirotaka Niwa; Kawai K; Ohata K; Ishihara Y; Takabayashi N; Kobayashi R; Hiramatsu T

BACKGROUND/AIMS Severity of inflammation may be a risk factor for negative outcome in non-operative therapy of appendicitis. However, optimal screening test for predicting the pathological severity of appendicitis has not been established. METHODOLOGY 632 consecutive patients who underwent appendectomy at a single institute were retrospectively reviewed. Clinical parameters are compared among the three pathological grades: simple (G1), gangrenous (G2), and perforated appendicitis (G3). The diagnostic power of inflammatory markers (WBC count and CRP concentration) in discriminating the advanced appendicitis from the milder one was evaluated. RESULTS CRP concentration was well correlated with the severity of appendicitis (p>0.0001), while WBC count showed only slight increase in advanced pathology (G1 vs. G2-G3). In receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) was remarkably higher in CRP (AUC 0.809) compared with that in WBC count (AUC 0.617), suggesting that CRP is a more sensitive test in discriminating the pathological severity of appendicitis. Multivariate analysis confirmed that CRP concentration >6.2mg/dL (OR: 5.12; 95% CI: 2.17-12.7) and diameter >12mm (OR: 4.33; 95% CI: 1.98-9.90) were strong predictive factors for advanced appendicitis. CONCLUSIONS CRP concentration may be a potent objective predictor of pathological severity in appendicitis. Combination with the other diagnostic modalities may improve the diagnostic accuracy in predicting the severity of appendicitis.


European Journal of Radiology | 2016

Added value of pretreatment 18F-FDG PET/CT for staging of advanced gastric cancer: Comparison with contrast-enhanced MDCT

Yusuke Kawanaka; Kazuhiro Kitajima; Kazuhito Fukushima; Miya Mouri; Hiroshi Doi; Tsutomu Oshima; Hirotaka Niwa; Nobuaki Kaibe; Mitsuru Sasako; Toshihiko Tomita; Hiroto Miwa; Shozo Hirota

PURPOSE To evaluate the added clinical value of pretreatment (18)F-FDG PET/CT compared with conventional contrast-enhanced multidetector-row CT (CECT) alone for staging of advanced gastric cancer MATERIALS AND METHODS We studied 106 patients with locally advanced gastric cancer who underwent pretreatment CECT and (18)F-FDG PET/CT. Two experienced reviewers assessed the diagnostic performance of both CECT alone and the combination of CECT and (18)F-FDG PET/CT for the primary tumor, regional lymph node metastasis (N) and distant metastasis (M), rating their diagnostic confidence with a 5-point scoring system for each location. The two methods were compared using receiver operating characteristic (ROC) curve analysis for histopathologic findings, imaging, and clinical follow-up as the reference standards. RESULTS Among the 106 patients, 96 primary tumors (90.6%) were detected by CECT, while 101 (95.3%) were clearly identified by (18)F-FDG PET/CT (p=0.074). Patient-based areas under the ROC curves for CECT alone versus the combination of CECT and (18)F-FDG PET/CT for diagnosis of N stage, peritoneal dissemination, liver metastasis, distant lymph node metastasis, bone metastasis, metastasis at other sites and overall M stage were 0.787 vs. 0.858 (p=0.13), 0.866 vs. 0.878 (p=0.31), 0.998 vs. 1.0 (p=0.36), 0.744 vs. 0.865 (p=0.049), 0.786 vs. 0.998 (p=0.034), 0.944 vs. 0.984 (p=0.34), and 0.889 vs. 0.912 (p=0.21), respectively. The diagnostic performance of primary tumor detection and NM staging was not influenced by the histologic subtype. CONCLUSION Adding (18)F-FDG PET/CT to CECT provides better diagnostic accuracy for detection of distant lymph node metastasis and bone metastasis in patients with untreated advanced gastric cancer.


Surgical Laparoscopy Endoscopy & Percutaneous Techniques | 2008

A case of catamenial pneumothorax.

Hirotaka Niwa; Ryo Kobayashi; Takeyuki Hiramatsu

Catamenial pneumothorax is a subclass of secondary spontaneous pneumothorax occurring in women in their third or fourth decade of life. We describe a classic and typical case of this disease. Although it is believed to be rare historically, the recent study showed the much higher prevalence. It is essential to consider this disease in recurrent spontaneous pneumothorax of a middle-aged woman.


Annals of Surgical Oncology | 2018

Efficacy of Endoscopic Management for Early Remnant Gastric Cancer: Is Completion Gastrectomy Truly Necessary in Cases with Marginally Noncurative Histopathologic Features?

Yudai Fukui; Junichi Shindoh; Naoko Inoshita; Aya Mizuno; Shusuke Haruta; Harushi Udagawa; Shu Hoteya; Shigeru Tsunoda; Shin’ichi Miyamoto; Rie Ozawa; Hirotaka Niwa; Yoshiharu Sakai; Hisashi Shinohara

BackgroundFor patients with early primary gastric cancer, endoscopic management has become a standard of care. However, its efficacy for early remnant gastric cancer (ERGC) remains controversial and an invasive surgical procedure remains the primary choice of treatment.MethodsA multi-institutional database of ERGC cases was retrospectively reviewed. Efficacy of endoscopic resection was analyzed by reviewing the clinicopathologic features of patients who underwent endoscopic resection and comparing the long-term outcomes with those of surgical resection.ResultsOf the 121 patients who were histopathologically diagnosed with ERGC after distal gastrectomy, 80 underwent endoscopic resection and 41 underwent completion gastrectomy (Group S). According to the histopathological criteria, 55 of the 80 endoscopic resection cases were classified as “curative resection” (Group E1) and the remaining 25 were classified as “noncurative resection” (Group E2). Tumor recurrence was observed only in three patients (12%) in Group E2, and no tumor recurrence was confirmed in Group S and Group E1. Multivariate analyses confirmed that completion gastrectomy [hazard ratio (HR), 6.2; 95% confidence interval (CI), 1.5–26.3] was associated with poor survival compared with endoscopic resection, and lymphovascular infiltration (HR 9.5; 95% CI 2.5–36.7) was correlated with tumor recurrence. Histopathological positive resection margin, tumor size, or deeper tumor invasion were not correlated with tumor recurrence after endoscopic resection.ConclusionsEndoscopic management might be an effective treatment option for ERGC with potential long-term survival advantage over the completion gastrectomy even in cases with histopathological features, suggesting noncurative resection.


PLOS ONE | 2018

The eCura system as a novel indicator for the necessity of salvage surgery after non-curative ESD for gastric cancer: A case-control study

Hirotaka Niwa; Rie Ozawa; Yasunori Kurahashi; Tsutomu Kumamoto; Yasutaka Nakanishi; Koichi Okumura; Ikuo Matsuda; Yoshinori Ishida; Seiichi Hirota; Hisashi Shinohara

Endoscopic submucosal dissection (ESD) for early gastric cancer does not always lead to complete cancer resection. The aim of this study was to determine indicators for cancer residue (CR) status in cases of non-curative ESD. We analyzed 47 cases of non-curative ESD followed by salvage surgery and collected data regarding the rates of CR, which included both local CR and lymph node metastasis (LNM). To elucidate the risk factors for CR status, we compared the CR positive and the CR negative groups among surgical specimens according to the following variables obtained from ESD findings: tumor location, tumor size, depth of invasion, lympho-vascular invasion, histological margin, and histological diagnosis. The eCura system, which is an LNM risk scoring system, was also applied and scores were calculated in each case as follows: 3 points for lymphatic invasion and 1 point each for tumor size >30 mm, positive vertical margin, venous invasion, and submucosal invasion ≥500 μm. There were 9 (19%) CR positive cases, which included 6 cases of local CR and 4 cases of LNM; no cancer was detected in over 80% of the patients. The eCura scoring system was the only significant factor for CR status: the higher the eCura score, the greater the CR positivity (p = 0.0128). In particular, all patients in the low-risk group (score = 0–1 point) had no CR. Although no cancer recurrence was observed during a median follow-up of 4 years, 2 patients died of pneumonia. In conclusion, the eCura system might make it possible to select appropriate cases for salvage surgery.


Journal of Gastrointestinal Surgery | 2010

Predictive Factors for Negative Outcomes in Initial Non-operative Management of Suspected Appendicitis

Junichi Shindoh; Hirotaka Niwa; Kazushige Kawai; Ko Ohata; Yukio Ishihara; Naoki Takabayashi; Ryo Kobayashi; Takeyuki Hiramatsu


Hepato-gastroenterology | 2005

Factors influencing mortality of acute intestinal infarction associated with SIRS

Hiroshi Yasuhara; Hirotaka Niwa; Tomohiro Takenoue; Shuji Naka


Japanese Journal of Forest Environment (Japan) | 2008

Estimating decay rates of dead wood by changes in wood density in coniferous plantations in Japan

Y. Sakai; Motoichiro Takahashi; Shunichirou Ishizuka; Y. Inagaki; Yojiro Matsuura; A. Unno; Kyosuke Nakata; A. Nagasaka; Hirotaka Niwa; S. Sawata; Y. Houjyou; Yasushi Tamaki; T. Kasetani; Hiromu Takeda; H. Aiura; M. Yamanouchi; Haruo Shimada; Iwatsuki. T.; A. Yamaba; Takehito Yamada; Hiroo Maeda; M. Muro

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Rie Ozawa

Hyogo College of Medicine

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Mitsuru Sasako

Hyogo College of Medicine

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