Network


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

Hotspot


Dive into the research topics where Yasunori Itoh is active.

Publication


Featured researches published by Yasunori Itoh.


International Journal of Urology | 2007

Examination of alpha 1 adrenoceptor subtypes in the human ureter

Yasunori Itoh; Yoshiyuki Kojima; Takahiro Yasui; Keiichi Tozawa; Shoichi Sasaki; Kenjiro Kohri

Aim:  Urinary stone disease is a common condition affecting up to 12% of the population. Speedy elimination of ureterolithiasis in the lower part of ureters is reported with the alpha 1‐blocker. This study was carried out to characterize the alpha 1 adrenoceptors (AR) subtype gene and protein expression in the proximal, medial, and distal regions of the human ureter with the aim of facilitating stone expulsion.


Journal of Bone and Mineral Research | 2010

Renal macrophage migration and crystal phagocytosis via inflammatory-related gene expression during kidney stone formation and elimination in mice: Detection by association analysis of stone-related gene expression and microstructural observation†

Atsushi Okada; Takahiro Yasui; Yasuhiro Fujii; Kazuhiro Niimi; Shuzo Hamamoto; Masahito Hirose; Yoshiyuki Kojima; Yasunori Itoh; Keiichi Tozawa; Yutaro Hayashi; Kenjiro Kohri

Mice have a strong ability to eliminate renal calcium oxalate crystals, and our previous examination indicated a susceptibility in which monocyte‐macrophage interaction could participate in the phenomenon. To clarify the macrophage‐related factors playing roles in the prevention of crystal formation in mouse kidneys, morphologic and expression studies based on microarray pathway analysis were performed. Eight‐week‐old male C57BL/6N mice were administered 80 mg/kg of glyoxylate by daily intraabdominal injection for 15 days, and the kidneys were extracted every 3 days for DNA microarray analysis. Based on the raw data of microarray analysis, pathway analyses of inflammatory response demonstrated macrophage activation through the increased expression of chemokine (C‐X‐C) ligand 1, fibronectin 1, and major histocompatability (MHC) class II. Association analysis of related gene expression values by quantitative reverse transcription polymerase chain reaction (RT‐PCR) indicated the high association of chemokine (C‐C) ligand 2, CD44, colony‐stimulating factor 1, fibronectin 1, matrix gla protein, secreted phosphoprotein 1, and transforming growth factor β1 (TGF‐β1) with the amount of both renal crystals and F4/80, a macrophage marker. Immunohistochemically, interstitial macrophages increased during the experimental course, and CD44 and MHC class II were upregulated around crystal‐formation sites. Ultrastructural observation of renal macrophages by transmission electron microscopy indicated interstitial macrophage migration with the phagocytosis of crystals. In conclusion, increased expression of inflammation‐related genes of renal tubular cells induced by crystal formation and deposition could induce monocyte‐macrophage migration and phagocytosis via the interaction of CD44 with osteopontin and fibronectin. Such crystal‐removing ability of macrophages through phagocytosis and digestion might become a new target for the prevention of stone formation.


Journal of Bone and Mineral Research | 2008

Morphological conversion of calcium oxalate crystals into stones is regulated by osteopontin in mouse kidney.

Atsushi Okada; Shintaro Nomura; Yukihiko Saeki; Yuji Higashibata; Shuzo Hamamoto; Masahito Hirose; Yasunori Itoh; Takahiro Yasui; Keiichi Tozawa; Kenjiro Kohri

An important process in kidney stone formation is the conversion of retentive crystals in renal tubules to concrete stones. Osteopontin (OPN) is the major component of the kidney calcium‐containing stone matrix. In this study, we estimated OPN function in early morphological changes of calcium oxalate crystals using OPN knockout mice: 100 mg/kg glyoxylate was intra‐abdominally injected into wildtype mice (WT) and OPN knockout mice (KO) for a week, and 24‐h urine oxalate excretion showed no significant difference between WT and KO. Kidney crystal depositions were clearly detected by Pizzolato staining but not by von Kossa staining in both genotypes, and the number of crystals in KO was significantly fewer than in WT. Morphological observation by polarized light optical microphotography and scanning electron microphotography (SEM) showed large flower‐shaped crystals growing in renal tubules in WT and small and uniform crystals in KO. X‐ray diffraction detected the crystal components as calcium oxalate monohydrate in both genotypes. Immunohistochemical staining of OPN showed that the WT crystals contained OPN protein but not KO crystals. We concluded that OPN plays a crucial role in the morphological conversion of calcium oxalate crystals to stones in mouse kidneys.


Journal of Bone and Mineral Research | 2009

Genome‐Wide Analysis of Genes Related to Kidney Stone Formation and Elimination in the Calcium Oxalate Nephrolithiasis Model Mouse: Detection of Stone‐Preventive Factors and Involvement of Macrophage Activity

Atsushi Okada; Takahiro Yasui; Shuzo Hamamoto; Masahito Hirose; Yasue Kubota; Yasunori Itoh; Keiichi Tozawa; Yutaro Hayashi; Kenjiro Kohri

We previously established a mouse kidney stone formation model and showed that mice have a higher tolerance to stone formation than rats. Furthermore, we showed that the generated calcium oxalate crystal deposits could be eliminated after several days. This study investigated the transcriptome of stone formation and elimination in the mouse kidney based on gene selection using a microarray technique. Eight‐week‐old male C57BL/6N mice were administered 80 mg/kg glyoxylate for 15 days, and kidney calcium oxalate crystal depositions had increased by day 6; thereafter, depositions decreased gradually and had almost disappeared by day 15. On microarray analysis, mRNA expression in the crystal‐formed kidneys showed the significant expression of 18,064 genes. Thirty‐one, 21, and 25 genes showed at least a 2‐fold increased expression during the experimental course (days 3–15), stone formation phase‐specific (days 3–6), and stone elimination phase‐specific (days 9–15) stages, respectively. Among these genes, those related to chemotaxis and monocyte/macrophage activation were identified. Gene ontology analysis to identify overexpressed genes highlighted categories related to inflammation, immune reactions and the complement activation pathway. Quantitative PCR of 17 previously reported stone‐related genes with a significant expression on microarray analysis showed significantly increased chemokines, stone matrix proteins, and their receptors; the significant decrease of several types of transporters and superoxide dismutase; and the persistently high expression of Tamm‐Horsfall protein throughout the experiment. In conclusion, inflammation and immune reactivity through macrophage migration are involved in stone formation and elimination in mouse kidneys.


International Journal of Urology | 2011

Efficacy of selective α1A adrenoceptor antagonist silodosin in the medical expulsive therapy for ureteral stones

Yasunori Itoh; Atsushi Okada; Takahiro Yasui; Shuzo Hamamoto; Masahito Hirose; Yoshiyuki Kojima; Keiichi Tozawa; Shoichi Sasaki; Kenjiro Kohri

Recently, we reported that α1A adrenoceptor (AR) is the main participant in phenylephrine‐induced human ureteral contraction. We therefore decided to carry out a prospective randomized study to evaluate the effects of silodosin, a selective α1A AR antagonist, as a medical expulsive therapy for ureteral stones. A total of 187 male patients, who were referred to our department for the management of symptomatic unilateral ureteral calculi of less than 10 mm, were randomly divided into two groups: group A (92 patients), who were instructed to drink 2 L of water daily, and group B (95 patients), who received the same instruction and were also given silodosin (8 mg/daily) for a maximum of 8 weeks. Expulsion rate, mean expulsion time and need for analgesics were examined. Overall, the mean expulsion time was 15.19 ± 7.14 days for group A and 10.27 ± 8.35 days for group B (P = 0.0058). In cases involving distal ureteral stones, the mean expulsion time was 13.40 ± 5.90 and 9.29 ± 5.91 days, respectively (P = 0.012). For stones of 1–5 mm in diameter, the mean expulsion time was 14.28 ± 6.35 and 9.56 ± 8.45 days, respectively (P = 0.017). For stones of 6–9 mm in diameter, the stone expulsion rate was 30.4% and 52.2% (P = 0.036), and the mean expulsion time was 21.00 ± 9.9 and 11.33 ± 8.31 days, respectively (P = 0.038). Herein, we report the first on silodosin in the management of ureteral lithiasis. Our findings suggest that silodosin might have potential as a medical expulsive therapy for ureteral stones.


International Journal of Urology | 2010

Renal tubular epithelial cell injury and oxidative stress induce calcium oxalate crystal formation in mouse kidney.

Masahito Hirose; Takahiro Yasui; Atsushi Okada; Shuzo Hamamoto; Hideo Shimizu; Yasunori Itoh; Keiichi Tozawa; Kenjiro Kohri

Objectives:  To clarify the role of renal tubular cell (RTC) injury and oxidative stress in the early stage of renal calcium oxalate crystal formation in a mouse model.


Journal of Endourology | 2015

Efficacy of Endoscopic Combined Intrarenal Surgery in the Prone Split-Leg Position for Staghorn Calculi

Shuzo Hamamoto; Takahiro Yasui; Atsushi Okada; Satoshi Koiwa; Kazumi Taguchi; Yasunori Itoh; Noriyasu Kawai; Yoshihiro Hashimoto; Keiichi Tozawa; Kenjiro Kohri

UNLABELLED Abstract Purpose: To evaluate the efficacy of endoscopic combined intrarenal surgery (ECIRS) using retrograde flexible ureteroscopy and miniature percutaneous nephrolithotomy (PNL) for the treatment of patients with staghorn calculi in the prone split-leg position. PATIENTS AND METHODS We retrospectively reviewed the records of 42 patients with staghorn calculi (45.8±3.2 mm) who underwent ECIRS using retrograde flexible ureteroscopy and miniature PNL in the prone split-leg position for the treatment of staghorn calculi in our center between December 2010 and August 2013. A flexible ureteroscope with a laser fiber was inserted through a ureteral access sheath, and lithoclast lithotripsy was performed through a mini-percutaneous tract. Both procedures were performed simultaneously by two urologists. Surgical parameters, including surgical time, stone-free (SF) rates, modified Clavien complication grades, and risk factors for residual stones, were analyzed. RESULTS Fifteen patients (35.7%) had complete staghorn calculi. Among the 42 staghorn calculi treated, 23 had 0 to 5 stone branches, 14 had 6 to 10 stone branches, and 5 had ≥11 stone branches. All procedures were performed successfully using a single lithotripsy tract with the patient in the prone split-leg position. The mean surgical time was 143.2±9.2 minutes. The initial SF rate was 71.4%, and the final SF rate was 83.3% after further treatment. One patient required a blood transfusion (2.4%), but no patient experienced a ≥3 Clavien grade complication. Risk factors for residual stones were stone size, stone surface area, complete staghorn calculi, and the number of stone branches. CONCLUSIONS ECIRS for staghorn calculi in the prone split-leg position is a safe, efficient, and versatile method for the effective management of staghorn calculi without the creation of multiple percutaneous tracts.


Free Radical Biology and Medicine | 2012

Mitochondrial permeability transition pore opening induces the initial process of renal calcium crystallization.

Kazuhiro Niimi; Takahiro Yasui; Masahito Hirose; Shuzo Hamamoto; Yasunori Itoh; Atsushi Okada; Yasue Kubota; Yoshiyuki Kojima; Keiichi Tozawa; Shoichi Sasaki; Yutaro Hayashi; Kenjiro Kohri

Renal tubular cell injury induced by oxidative stress via mitochondrial collapse is thought to be the initial process of renal calcium crystallization. Mitochondrial collapse is generally caused by mitochondrial permeability transition pore (mPTP) opening, which can be blocked by cyclosporine A (CsA). Definitive evidence for the involvement of mPTP opening in the initial process of renal calcium crystallization, however, is lacking. In this study, we examined the physiological role of mPTP opening in renal calcium crystallization in vitro and in vivo. In the in vitro study, cultured renal tubular cells were exposed to calcium oxalate monohydrate (COM) crystals and treated with CsA (2 μM). COM crystals induced depolarization of the mitochondrial membrane potential and generated oxidative stress as evaluated by Cu-Zn SOD and 4-HNE. Furthermore, the expression of cytochrome c and cleaved caspase 3 was increased and these effects were prevented by CsA. In the in vivo study, Sprague-Dawley rats were administered 1% ethylene glycol (EG) to generate a rat kidney stone model and then treated with CsA (2.5, 5.0, and 10.0 mg/kg/day) for 14 days. EG administration induced renal calcium crystallization, which was prevented by CsA. Mitochondrial collapse was demonstrated by transmission electron microscopy, and oxidative stress was evaluated by measuring Cu-Zn SOD, MDA, and 8-OHdG generated by EG administration, all of which were prevented by CsA. Collectively, our results provide compelling evidence for a role of mPTP opening and its associated mitochondrial collapse, oxidative stress, and activation of the apoptotic pathway in the initial process of renal calcium crystallization.


Urology | 2008

Inverse Relationship Between Obesity and Serum Prostate-Specific Antigen Level in Healthy Japanese Men: A Hospital-Based Cross-Sectional Survey, 2004-2006

Ryosuke Ando; Teruo Nagaya; Yoshihiro Hashimoto; Sadao Suzuki; Yasunori Itoh; Yukihiro Umemoto; Nobuo Ikeda; Keiichi Tozawa; Kenjiro Kohri; Shinkan Tokudome

OBJECTIVES To confirm an inverse relationship between obesity and serum prostate-specific antigen (PSA) levels in Japanese men with a smaller body mass index (BMI) than white and African-American men. METHODS We analyzed 5246 apparently healthy Japanese men aged >20 years who visited our medical center for a health checkup from January 2004 to December 2006. The men were divided into 6 groups by age decade, and the BMI was categorized into 5 groups. The body fat percentage (BFP) was also used and was grouped into quartiles. The Mantel-Haenszel chi(2) test was used to check for trends in proportions of subjects with abnormal PSA values for each cutoff point (2.5 and 4.0 ng/mL) in these groups. The relationships between the PSA levels and BMI or BFP were examined using multivariate analysis. RESULTS The median age, BMI, BFP, and PSA level was 46 years, 23.2 kg/m(2), 21.5%, and 0.78 ng/mL, respectively. The proportion of subjects with an abnormal PSA value increased significantly with age (P for trend < .0001); however, no trends were found across the BMI or BFP categories. The geometric mean PSA level increased significantly with age (P for linear trend < .0001) and decreased with BMI and BFP categories (P for linear trend = .001 and P for linear trend = .002, respectively). CONCLUSIONS Our findings have demonstrated an inverse relationship between obesity and PSA levels even in Japanese men with a low prevalence of obesity, such as was previously reported for American men. Therefore, in prostate cancer screening, obesity, which can affect the accuracy of PSA testing, independent of race and ethnicity, should be taken into account.


Journal of Bone and Mineral Research | 2009

Effects of impaired functional domains of osteopontin on renal crystal formation: Analyses of OPN transgenic and OPN knockout mice.

Shuzo Hamamoto; Shintaro Nomura; Takahiro Yasui; Atsushi Okada; Masahiro Hirose; Hideo Shimizu; Yasunori Itoh; Keiichi Tozawa; Kenjiro Kohri

Osteopontin (OPN) has been described as playing a nonredundant role in renal crystal formation. Here we investigated the effects of impaired domains of OPN, namely, the Arg‐Gly‐Asp (RGD) sequence and two calcium‐binding sites on crystal formation. We used wild‐type mice (WT group), OPN knockout mice (KO group), and OPN knockout mice carrying either a transgene in which the RGD sequence had been modified to Arg‐Gly‐Glu (RGE group) or whose two calcium‐binding sites had been deleted (CaX group). Following intraperitoneal injection of glyoxylate for 9 days, the changes occurring in three parameters of crystal formation—localization, number, and microstructure—were analyzed. In the WT group, crystal deposits increased gradually at the renal corticomedullary junction in an orderly fashion, whereas those in the KO group were observed sporadically in the renal cortex. In both the CaX and RGE groups, deposits were localized near the corticomedullary junction. Crystal deposition was greatest in the WT group and least in the KO group. The number of deposits in the RGE group was nearly equal to that in the KO group. Microscopic observations revealed that the crystal nuclei in the CaX group were stratified and occurred in a disordered pattern; this pattern was dissimilar to that in the WT group, in which a rosette petal–like radial pattern was observed. In the RGE group, the nuclei exhibited a radial pattern similar to that in the WT group. The results indicated the possibility that each domain contributes to the mechanism by which OPN stimulates crystal formation.

Collaboration


Dive into the Yasunori Itoh'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