Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Naoto Sassa is active.

Publication


Featured researches published by Naoto Sassa.


The Prostate | 2014

Prognostic value of intraductal carcinoma of the prostate in radical prostatectomy specimens.

Kyosuke Kimura; Toyonori Tsuzuki; Masashi Kato; Akiko M. Saito; Naoto Sassa; Ryo Ishida; Hiroki Hirabayashi; Yasushi Yoshino; Ryohei Hattori; Momokazu Gotoh

Intraductal carcinoma of the prostate (IDC‐P) is an adverse prognostic factor for radical prostatectomy (RP). The endpoint in most IDC‐P studies is increased prostate‐specific antigen (PSA) levels. The aim of this study was to evaluate whether IDC‐P in RP specimens is an adverse prognostic factor for progression‐free survival (PFS) and cancer‐specific survival (CSS).


The Journal of Urology | 2009

Efficacy of Silodosin for Relieving Benign Prostatic Obstruction: Prospective Pressure Flow Study

Yoshihisa Matsukawa; Momokazu Gotoh; Tomonori Komatsu; Yasuhito Funahashi; Naoto Sassa; Ryohei Hattori

PURPOSE We investigated the effect of the new sympathetic alpha1A-adrenoceptor antagonist silodosin for relieving benign prostatic obstruction by pressure flow study. MATERIALS AND METHODS In this open, nonblinded, prospective study we administered 8 mg silodosin daily for 4 weeks in 60 patients with lower urinary tract symptoms associated with benign prostatic enlargement. As a primary outcome measure, we assessed changes in bladder function and benign prostatic obstruction using pressure flow study. As secondary outcome measures, changes in subjective symptoms and quality of life were assessed by the International Prostate Symptom Score. Objective changes in urination status were also assessed by free uroflowmetry in terms of maximum flow rate and post-void residual urine volume. RESULTS A total of 57 patients were enrolled for analysis. In the storage phase of the pressure flow study bladder capacity at first desire to void increased significantly with no significant change in maximum cystometric capacity. Of 24 patients 14 (58.3%) with uninhibited detrusor contractions before administration showed apparent improvement in detrusor overactivity after administration, including 6 in whom uninhibited contractions disappeared. In the voiding phase mean detrusor pressure at maximum flow significantly decreased from 72.5 to 51.4 cm H(2)O. The mean bladder outlet obstruction index decreased significantly from 60.6 to 33.8. Obstruction grade assessed by the Schaefer nomogram improved in all except 1 patient. Total symptom and quality of life scores, maximum flow rate and post-void residual urine volume on free uroflowmetry significantly improved. CONCLUSIONS Silodosin improved lower urinary tract symptoms by improving bladder storage function and relieving benign prostatic obstruction.


Urology | 2012

Effect of Warm Ischemia on Renal Function During Partial Nephrectomy: Assessment With New 99mTc-Mercaptoacetyltriglycine Scintigraphy Parameter

Yasuhito Funahashi; Ryohei Hattori; Tokunori Yamamoto; Naoto Sassa; Takashi Fujita; Momokazu Gotoh

OBJECTIVE A decrease in renal function after partial nephrectomy caused by ischemic damage or nephron loss cannot be distinguished by conventional methods. We quantified renal function using a new 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renal scintigraphy parameter. MATERIAL AND METHODS We included 32 patients with a normally functioning contralateral kidney who received open partial nephrectomy with average warm ischemic time of 26.0 (range 14-46) min in this study. Effective renal plasma flow (ERPF) was calculated from 99mTc-MAG3 renal scintigraphy before and at 1 week and 6 months after surgery. We also analyzed regional 99mTc-MAG3 uptake in the surgically nonaffected parts. RESULTS One week after surgery, average ERPF in the operated kidney decreased to 66.4% from baseline (from 177.8 to 116.9 mL/min/1.73 m2) and regional 99mTc-MAG3 uptake decreased to 83.4%. A stronger correlation was found between ischemic time and the decrease in regional 99mTc-MAG3 uptake (P<.001) compared with ERPF (P=.029). The decrease in regional 99mTc-MAG3 uptake remained at 6 months in the group with ischemic time≥25 minutes, whereas it recovered when ischemic time was <25 minutes. CONCLUSION This new parameter quantified ischemic renal damage better than the conventional split functional evaluation. When warm ischemic time was ≥25 minutes, irreversible diffuse damage was seen in surgically preserved nephrons.


Urology | 2011

Relationship Between Renal Parenchymal Volume and Single Kidney Glomerular Filtration Rate Before and After Unilateral Nephrectomy

Yasuhito Funahashi; Ryohei Hattori; Tokunori Yamamoto; Osamu Kamihira; Naoto Sassa; Momokazu Gotoh

OBJECTIVES To measure the renal parenchymal volume (RPV) before and after unilateral nephrectomy and investigate the relationship between the RPV and single kidney glomerular filtration rate (GFR). METHODS From November 2003 to August 2009, 183 patients who had undergone unilateral nephrectomy were enrolled in the present study. All patients had undergone preoperative technetium-99m dimercaptosuccinic acid renal scintigraphy. Contrast-enhanced computed tomography was performed before and 6 months after surgery. RPV was calculated as the normally functioning tissue, excluding tumors or nonenhanced areas, using a 3-dimensional image reconstruction program. RESULTS The mean split GFR of the remaining kidney increased by 21.2%, from 41.6 to 49.5 mL/min/1.73 m(2) at 6 months after nephrectomy. The mean RPV of the remaining kidney increased by 9.3%, from 164.2 to 178.8 cm(3) after nephrectomy. The preoperative relative RPV of the remaining kidney was 58.8% (range 37.2%-97.9%) and the technetium-99m dimercaptosuccinic acid uptake was 62.2% (range 39.6%-100%), indicating a significant linear correlation (R = 0.865, P <.001). RPV correlated well with the single kidney GFR and patient age, both preoperatively and postoperatively. The postoperative GFR could be predicted by combining the preoperative factors. Multivariate regression analysis revealed that the RPV was positively associated with the single kidney GFR and negatively associated with patient age. CONCLUSIONS The differential renal function correlated well with the RPV and can be estimated by calculating the RPV. Even without using renal scintigraphy, the postoperative GFR can be predicted using our established formula.


Urology | 2014

Comparison of warm and cold ischemia on renal function after partial nephrectomy.

Yasuhito Funahashi; Yasushi Yoshino; Naoto Sassa; Yoshihisa Matsukawa; Shun Takai; Momokazu Gotoh

OBJECTIVE To assess renal functional deterioration after partial nephrectomy with warm and cold ischemia using (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) renal scintigraphy parameters. METHODS Open partial nephrectomy was performed in 59 patients with warm ischemia and 64 patients with cold ischemia. (99m)Tc-MAG3 renal scintigraphy was performed and effective renal plasma flow was calculated to evaluate split renal function. In addition, regional (99m)Tc-MAG3 uptake was analyzed in the surgically unaffected parts to evaluate ischemic damage. RESULTS The mean tumor size in the warm and cold ischemia groups was 2.9 and 3.2 cm, respectively, and the mean ischemic time was 24.2 minutes (range, 8-46 minutes) and 26.7 min (range, 8-58 minutes), respectively. One week after surgery, effective renal plasma flow in the operated kidney decreased to 66.2% (from 160.2 to 105.4 mL/min/1.73 m(2)) in the warm ischemia group and to 77.4% (from 152.3 to 116.6 mL/min/1.73 m(2)) in the cold ischemia group. Regional (99m)Tc-MAG3 uptake changed to 89.2% of baseline in the warm ischemia group and 101.5% of baseline in the cold ischemia group. When the ischemic time was ≥ 25 minutes, regional (99m)Tc-MAG3 uptake in the warm ischemia group did not recover to the baseline level at 6 months. Multiple regression analyses demonstrated a significant correlation between ischemic time and the decrease in regional (99m)Tc-MAG3 uptake in the warm ischemia group, but not in the cold ischemia group. CONCLUSION Warm ischemia for ≥ 25 minutes caused long lasting diffuse damage throughout the operated kidney, whereas cold ischemia for up to 58 minutes prevented ischemic injury to the renal remnant.


Nephrology Dialysis Transplantation | 2011

Renal cell carcinomas in haemodialysis patients: does haemodialysis duration influence pathological cell types and prognosis?

Naoto Sassa; Ryohei Hattori; Toyonori Tsuzuki; Yoshihiko Watarai; Akitoshi Fukatsu; Satoshi Katsuno; Tosinori Nishikimi; Takashi Fujita; Kenji Ohmae; Momokazu Gotoh

BACKGROUND It is well known that renal cell carcinoma (RCC) is one of the most important complications in haemodialysis (HD) patients. However, the influence of HD duration on the development of RCCs has not yet been described. This study sought to determine whether HD duration is related to pathological RCC types and to prognosis. METHODS We examined 69 patients having HD (73 kidneys) who underwent radical nephrectomy for renal tumours between 1991 and 2008. We divided the patients into three groups according to the duration of HD (< 10 years, between 10 and 20 years, and > 20 years). All histological examinations were performed without knowledge of clinical outcomes. In each case, pathological cell types and clinical parameters were recorded. RESULTS The patients with HD duration of > 10 years showed distinct pathological characteristics, including acquired cystic disease of kidney-associated RCCs. The disease-free survival (DFS) rates of these groups were statistically different from one another (P < 0.05). RCC with a sarcomatoid component was found in cases having HD durations of > 10 years. The DFS rate of the patients with a sarcomatoid component was 55.9% at 5 years and 37.3% at 10 years. CONCLUSIONS HD duration influenced pathological cell types and tumour stages of RCCs in HD patients. Patients receiving > 10 years of HD experienced RCCs with a sarcomatoid component, which resulted in poor outcomes. Hence, patients receiving long-term HD, and especially those with > 10 years of HD, should have frequent and careful medical examinations.


International Journal of Urology | 2010

De novo detrusor underactivity after laparoscopic radical prostatectomy

Yoshihisa Matsukawa; Ryohei Hattori; Tomonori Komatsu; Yasuhito Funahashi; Naoto Sassa; Momokazu Gotoh

Objective:  The aim of this study was to investigate bladder function following laparoscopic radical prostatectomy, with a focus on de novo detrusor underactivity.


Urology | 2009

Direct Visualization of Renal Hemodynamics Affected by Carbon Dioxide-induced Pneumoperitoneum

Naoto Sassa; Ryohei Hattori; Tokunori Yamamoto; Masashi Kato; Tomonori Komatsu; Yoshihisa Matsukawa; Yasuhito Funahashi; Momokazu Gotoh

OBJECTIVES To examine the direct renal hemodynamics during carbon dioxide pneumoperitoneum in both human and porcine models. Laparoscopic living donor nephrectomy has become widespread because of its minimally invasive nature. However, it has been clear that the renal hemodynamics and function are affected during carbon dioxide pneumoperitoneum. METHODS The erythrocyte velocity in the cortical peritubular capillary (CPC) was monitored and measured during laparoscopic nephrectomy on human donors and laparoscopic partial nephrectomy on humans with renal cell carcinoma during carbon dioxide pneumoperitoneum (pressure of 8, 12, 15, 18, and 20 mm Hg). We used a direct imaging system of renal microcirculation by magnifying endoscopy, as previously described. We maintained the same pressure for 5 minutes. In the porcine model (6 pigs), we measured the erythrocyte velocity in the CPC using the same method during carbon dioxide pneumoperitoneum (pressure of 0, 5, 10, 15, 20, and 25 mm Hg). RESULTS The erythrocyte velocity in the renal artery did not change during increased carbon dioxide pneumoperitoneum. When the pneumoperitoneal pressure was 25 mm Hg, we found that >90% of the erythrocyte velocity in the CPC was nonflowing. In the human model, the erythrocyte velocity in the CPC decreased when the carbon dioxide pneumoperitoneum pressure was 12 mm Hg. CONCLUSIONS The erythrocyte velocity in the CPC decreased during carbon dioxide pneumoperitoneum in all kidneys in both the human and the porcine models. However, erythrocyte velocity in the renal artery did not change during carbon dioxide pneumoperitoneum. After stopping the pneumoperitoneum, the erythrocyte velocity in the CPC recovered immediately. The findings of our study have shown that the suitable carbon dioxide pneumoperitoneal pressure for renal microcirculation is <8 mm Hg for laparoscopic surgery.


American Journal of Clinical Pathology | 2013

Growth Pattern, an Important Pathologic Prognostic Parameter for Clear Cell Renal Cell Carcinoma

Akitoshi Fukatsu; Toyonori Tsuzuki; Naoto Sassa; Toshinori Nishikimi; Tohoru Kimura; Tsuyoshi Majima; Yasushi Yoshino; Ryohei Hattori; Momokazu Gotoh

OBJECTIVES To assess the validity of growth pattern as a unique prognostic parameter for clear cell renal cell carcinoma (ccRCC). METHODS In total, 561 patients with pathologic tumor stage 1 (pT1), pT2, and pT3a ccRCC without preoperative metastasis were evaluated. Clinicopathologic parameters, including pathologic tumor stage, Fuhrman grade, tumor necrosis, lymphovascular invasion, and growth pattern, were analyzed to predict disease-free survival (DFS) and cancer-specific survival (CSS). RESULTS Growth patterns were defined as follows: expansive included tumors with well-circumscribed margins without normal renal tissue in the tumor, and infiltrative involved tumors with ill-circumscribed margins or normal renal tissue in the tumors. In multivariate analysis, Fuhrman grade, tumor necrosis, and growth pattern were useful predictors of DFS, whereas Fuhrman grade and growth pattern were useful predictors of CSS, although only 30 cases showed the infiltrative pattern. CONCLUSIONS Growth pattern can be considered a new prognostic parameter for ccRCC.


Modern Pathology | 2016

The presence of intraductal carcinoma of the prostate in needle biopsy is a significant prognostic factor for prostate cancer patients with distant metastasis at initial presentation

Masashi Kato; Toyonori Tsuzuki; Kyosuke Kimura; Akihiro Hirakawa; Fumie Kinoshita; Naoto Sassa; Ryo Ishida; Akitoshi Fukatsu; Tohru Kimura; Yasuhito Funahashi; Yoshihisa Matsukawa; Ryohei Hattori; Momokazu Gotoh

Intraductal carcinoma of the prostate is an adverse prognostic factor in localized prostate cancer patients. However, whether it influences outcome of those patients with distant metastases discovered at initial diagnosis is unclear. Here, we evaluated whether the presence of intraductal carcinoma of the prostate in prostate needle biopsies is an adverse prognostic factor for cancer-specific survival and overall survival in such prostate cancer patients. We retrospectively enrolled 150 eligible patients. All patients received androgen-deprivation therapy and/or chemotherapy. Their age, performance status, pain, metastatic sites, clinical T stage, serum prostate-specific antigen, alkaline phosphatase, hemoglobin, Gleason score, and the presence of Gleason pattern 5 were analyzed. Primary end point was cancer-specific survival; secondary end points included prostate-specific antigen progression-free survival and overall survival. Fine and Gray’s model and the Cox proportional hazards model were used as statistical tests. Intraductal carcinoma of the prostate was detected in 100 (67%) patients. At a median follow-up of 38 months, 79 patients (53%) had died of the disease and nine (6%) had died of other causes. The average time interval to cancer-related death was 28 months. On multivariate analysis, only intraductal carcinoma of the prostate was significantly associated with cancer-specific survival (P=0.018) and overall survival (P=0.001), and only the presence of Gleason pattern 5 was significantly associated with prostate-specific antigen progression-free survival (P=0.026). The presence of intraductal carcinoma of the prostate was the only significant prognostic parameter for cancer-specific survival and overall survival in prostate cancer patients with distant metastasis at presentation. These results may prove useful in planning future treatments.

Collaboration


Dive into the Naoto Sassa's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge