Yutaro Hayashi

Fukushima Medical University, Hukusima, Fukushima, Japan

Are you Yutaro Hayashi?

Claim your profile

Publications (182)440.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Four disorders, including poor semen quality, testicular cancer, cryptorchidism and hypospadias, are thought to represent testicular dysgenesis syndrome and have been hypothesized to share a common etiology. We predicted testicular function in prepubertal boys with a history of cryptorchidism and/or hypospadias by measuring serum hormone levels. A total of 82 prepubertal boys who underwent orchiopexy and/or hypospadias repair in childhood were enrolled in the study. Patients were surgically treated for cryptorchidism (23 in group 1), hypospadias (49 in group 2), cryptorchidism and hypospadias (10 in group 3), and hydrocele testis (7 in control group 4). Serum hormones, including luteinizing hormone, follicle-stimulating hormone and total testosterone, were measured separately by age less than 12.5, 12.5 to 13.5 and greater than 13.5 years, and by Tanner pubertal stage. Follicle-stimulating hormone in group 3 was significantly higher than in groups 1, 2 and 4 at ages 12.5 to 13.5 and greater than 13.5 years, and for Tanner stages 2 and 3 (p <0.05). However, luteinizing hormone and testosterone did not differ among the groups regardless of age or Tanner stage. Group 3 patients had significantly higher follicle-stimulating hormone regardless of the severity of cryptorchidism or hypospadias. Data suggest that testicular function in patients with cryptorchidism plus hypospadias is more severely impaired than that in patients with cryptorchidism or hypospadias, lending clinical support to the testicular dysgenesis syndrome hypothesis of a common origin.
    The Journal of urology 06/2011; 185(6 Suppl):2444-50. · 3.75 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess the correlation between intratesticular pressure (ITP) after testicular torsion and subsequent testicular function using a rat model and to show that ITP at surgery is a useful predictor of future spermatogenesis. Fourteen rats were divided into a torsion group (n= 7) and a control group with sham operation (n= 7). Torsion was created by 720° rotation of the left testis in a counter-clockwise direction. Using a handheld compartment monitor, the ITP of the torsed testes was measured three times: before torsion (pre-torsion), just before torsion repair (pre-detorsion) and 5 min after torsion repair (post-detorsion). We evaluated the correlation between ITP and testicular weight, epididymal sperm count or pathological findings, such as the seminiferous tubule diameter (STD) and the modified Johnsen's score, 4 weeks after surgery. Mean (se) pre-torsion, pre-detorsion and post-detorsion ITP values in the torsion group were 5.9 (2.5), 19.7 (10.7) and 8.2 (4.8) cm H(2) O, respectively. The ITP in torsed testes significantly increased after torsion (P < 0.01) and decreased after detorsion (P < 0.01). Strong correlations were observed between the reduction of ITP after detorsion and testicular weight (r= 0.87, P < 0.05), epididymal sperm count (r= 0.94, P < 0.05), STD (r= 0.87, P < 0.05) or the Johnsen's score (r= 0.99, P < 0.001). A smaller reduction in ITP after detorsion can be a risk factor for subsequent disturbance of spermatogenesis, suggesting that ITP can be an index for determining whether the affected testis should be removed after testicular torsion.
    BJU International 05/2011; 109(3):466-70; discussion 470. · 3.13 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • Source
    The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • The Journal of Urology 04/2011; 185(4). · 3.75 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We established a new strategy for nonpalpable testis, including intra-abdominal testis, testicular nubbins, and intracanalicular testis, to correct these conditions by laparoscopic procedures. Of the 53 boys (mean age, 24.5 months), nonpalpable testis was on the right side in 13, on the left in 34, and bilateral in 6. Three boys with nonpalpable testis involved contralateral palpable undescended testis. We applied only laparoscopic treatment without open inguinal incision for all cases. After laparoscopic orchiopexy and orchiectomy, we performed subsequent laparoscopic inguinal ring and/or peritoneal defect closure to prevent postoperative inguinal hernia formation, and concurrent laparoscopic repair for cases of contralateral undescended testes and open processus vaginalis under the same anesthesia. All boys underwent laparoscopic treatment immediately after laparoscopic evaluation. We performed laparoscopic orchiopexy for 22 cases with intra-abdominal testes. Twenty-seven boys underwent laparoscopic groin exploration, and 24 underwent subsequent laparoscopic orchiectomy for testicular nubbins, and 3 underwent subsequent laparoscopic orchiopexy for intracanalicular testes. In two boys with testicular nubbin, an open processus vaginalis was present. Forty-nine boys underwent laparoscopic inguinal ring and/or peritoneal defect closure after orchiopexy or orchiectomy to prevent inguinal hernia formation or hydrocele testis. Concurrent laparoscopic contralateral inguinal closure was performed for two cases with opened contralateral processus vaginalis. Our new strategy is useful because all patients with nonpalpable testis could be treated successfully by only laparoscopic management, avoiding open inguinal incision, preventing inguinal hernia formation, and enabling the concurrent repair of contralateral undescended testis and open processus vaginalis.
    Journal of endourology / Endourological Society 03/2011; 25(4):635-40. · 1.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives:  In hypospadia patients, the urethral plate and the underlying tissue were previously thought to be the main cause of penile curvature and, because of this, they used to be excised to correct the curvature. Currently, they are preserved as they are not thought to cause penile curvature anymore. The aim of the present histology study was to elucidate the characteristic structure of the tissue beneath the urethral plate. Methods:  The experimental group consisted of 27 hypospadiac patients with moderately severe penile curvature, who underwent one-stage urethroplasty after dividing the urethral plate. Excised tissues were observed under light microscopy and transmission electron microscopy (TEM). Furthermore, the presence of collagen subtypes I, III and IV was examined with immunohistochemical staining and western blotting. Results:  Light microscopy showed the existence of many massed and intertwined collagen fibers and vessels that resembled those of the cavernous sinus. TEM showed the existence of many collagen fibers, capillary vessels and other structures. Immunohistochemical staining showed collagen subtype I in the interfascicular space and collagen fibers were densely stained. Collagen subtype IV was found in the basement membrane of vessels, but collagen subtype III was not detected. The same results were obtained by western blotting. Conclusions:  The tissue beneath the urethral plate was considered to originate from the corpus spongiosum penis. The distribution of collagen subtypes suggests that the presence of the tissue might affect ventral penile curvature. Long-term follow up is required after one-stage hypospadias repair with preservation of the urethral plate and the underlying tissue.
    International Journal of Urology 02/2011; · 1.80 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A 23-month-old boy presented with an 11-month history of abdominal distention. Examination disclosed a large tumor in the right kidney and transabdominal radical nephrectomy was performed. Histopathological study demonstrated clear cell sarcoma of the kidney (CCSK). Cytogenetic analyses performed with blood lymphocytes showed translocation (1;6) (p32.3;q21). This is the first case of CCSK showing chromosomal translocation in blood lymphocytes. In addition, molecular analyses demonstrated high expression levels of EGFR and KIT proteins in the tumor tissue of CCSK. These molecular findings suggest that tyrosine kinase receptors may be potential therapeutic targets for CCSK in the future.
    Urology 02/2011; 78(3):684-6. · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The management of multicystic dysplastic kidney (MCDK) is controversial. There has been a shift from routine surgical removal to nonoperative management. However, recently, an argument has emerged with regard to the management of MCDK, with several studies recommending surgical removal. We report a case of pelvic MCDK that was diagnosed and subsequently removed by a laparoscopic procedure. A laparoscopic approach to the renal and pelvic areas is a minimally invasive, safe, and effective procedure to diagnose and treat MCDK. We believe that laparoscopic nephrectomy should be offered as a management option to the families of children with unilateral MCDK.
    Urology 02/2011; 78(2):434-6. · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To examine whether the direct correlation between the expression of α₁-adrenoceptor (AR) subtype mRNA and severity of lower urinary tract symptoms (LUTS) or bladder outlet obstruction (BOO) in the prostate exists in benign prostatic hyperplasia (BPH) patients. Sixty-eight patients with LUTS and BOO secondary to BPH were enrolled. Four prostate needle biopsy specimens were obtained from the transition zone to examine the expression level of α₁-AR subtypes by Taqman reverse-transcription polymerase chain reaction. The correlation and regression between each expression level of α₁-AR subtype and clinical findings such as patient age, prostate volume, International Prostate Symptom Score (IPSS), quality of life (QOL) index, maximum flow rate in uroflowmetry (Qmax) and post-void residual urine volume (PVR) were assessed by stepwise multiple regression analysis. The correlation and regression between this expression level and individual symptoms of IPSS were assessed by Pearson's correlation coefficient and multiple regression analyses. Stepwise multiple regression analysis showed that the expression levels of α(1a) -AR, α(1b) -AR, α(1d) -AR and total α(1) -AR mRNA showed a significant regression with patient age, but not with prostate volume, IPSS, QOL index, Qmax and PVR. Pearson's correlation coefficient and multiple regression analyses demonstrated no correlation and regression between each α(1) -AR subtype mRNA expression level and individual symptoms of IPSS. There was no direct correlation between the expression of α₁-AR subtype mRNA in the prostate and severity of LUTS or BOO in BPH patients, although the significant regression of this expression with patient age existed. LUTS and BOO may be associated with multiple factors and several other conditions may contribute to LUTS and BOO.
    BJU International 02/2011; 107(3):438-42. · 3.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We compare the technical details and surgical outcomes of adult and pediatric laparoscopic pyeloplasty, and discuss the lessons learned from these comparisons. A total of 46 patients underwent laparoscopic pyeloplasty for repair of ureteropelvic junction obstruction between August 2006 and April 2010. Patients were divided into 2 groups-adults (older than 16 years, 21 patients) and children (15 years or younger, 25 patients). Medical records and surgical videos were reviewed with particular attention to patient characteristics, procedures and surgical outcomes. Crossing vessels were more common in adults (p <0.05). After June 2009 we tried to perform a transmesenteric approach for left ureteropelvic junction obstruction, and actually performed this procedure for 3 of 5 adults (60%) and 8 of 10 children (80%). There was no significant difference in median operative times between adults and children. However, mean time required for exposure of the ureteropelvic junction in children (54 minutes) was less than that in adults (81 minutes, p <0.005). Mean time required for ureteropelvic anastomosis tended to be longer in children. Postoperative complications were noted in 3 adults and 1 child. Percentage reduction in anteroposterior diameter of the renal pelvis was significantly greater in children than in adults (p <0.05). Successful resolution of ureteropelvic junction obstruction was observed in 90.0% of adults and 95.5% of children. Understanding of the key surgical steps of adult and pediatric laparoscopic pyeloplasty can provide for the improvement of laparoscopic skills, and facilitate procedures in adult and pediatric populations.
    The Journal of urology 02/2011; 185(4):1461-7. · 3.75 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The role of cyclooxygenases (COX) in the male reproductive organ remains unclear. However, there are some reports suggesting that COX-2 might have an effect on spermatogenesis or steroidogenesis. In this study, we examined whether COX-2 was induced in impaired testes, and we also investigated the possible role of COX in the testes using experimental cryptorchidism model mice. Five-week-old male mice underwent an operation to induce unilateral cryptorchidism via an abdominal incision and suturing of the left testes to the lateral abdominal wall, and they were then divided into 3 groups: 1) experimental cryptorchidism plus SC560 (selective COX-1 inhibitor) administration; 2) experimental cryptorchidism plus NS398 (selective COX-2 inhibitor) administration; 3) and experimental cryptorchidism alone. The expression levels of COX-1 and COX-2 were determined by immunohistologic staining and quantitative reverse transcription-polymerase chain reaction (RT-PCR). The influence of COX inhibitors on the testes was assessed by measuring the concentration of serum testosterone and evaluating the seminiferous tubules according to the Johnsen score. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining was also performed to detect apoptosis in the testes. Immunohistologic staining and RT-PCR revealed that the expression of COX-2 was increased in the experimental cryptorchid testes (groups 1-3). The concentration of serum testosterone was significantly lower in group 2 at 5 weeks after surgery than in the other groups. The Johnsen score of the cryptorchid testes in group 2 was significantly lower than those in other groups at 5 weeks after surgery. TUNEL staining revealed that the number of apoptotic cells was significantly increased in group 2 compared with the other groups. However, the COX-1 inhibitor did not appear to affect spermatogenesis in the experimental cryptorchid testes. These results suggest that the COX-2 inhibitor provoked testicular damage in experimental cryptorchidism by inducing germ cell apoptosis. The expression of COX-2 might be induced to protect germ cells from heat stress caused by experimental cryptorchidism.
    Journal of Andrology 01/2011; 32(1):77-85. · 1.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the magnetic resonance imaging (MRI) findings, diagnostic accuracy and clinical usefulness of fat-suppressed T2-weighted and diffusion-weighted imaging (DWI) in the management of non-palpable testes. In all, 56 children (63 non-palpable testes) aged 8 months-11 years (mean 24.7 months) with non-palpable testes were enrolled. T1- and T2-weighted imaging, as well as fat-suppressed T2-weighted imaging and DWI were performed during MRI examination, and the imaging results were compared with surgical findings. In the 63 non-palpable testes, MRI identified 22% (14/63) as intra-abdominal, 20% (13/63) as intra-canalicular, 29% (18/63) as testicular nubbins, and 29% (18/63) as unidentifiable. Although it was difficult to confirm their presence in the abdominal cavity using T1- and T2-weighted imaging alone, additional assessment, including fat-suppressed T2-weighted imaging and DWI facilitated the detection of intra-abdominal testes more easily because they were imaged at a markedly higher signal intensity. The sensitivity, specificity and positive and negative predictive values for the MRI vs the operative findings were 100, 97.3, 96.3, and 100%, respectively. The overall prediction accuracy was 98.4%. Additional MRI assessments, fat-suppressed T2-weighted imaging and DWI are useful examinations to improve the preoperative diagnostic accuracy of non-palpable testes.
    BJU International 01/2011; 107(2):290-4. · 3.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Phimosis is a condition in which the prepuce cannot be retracted over the glans penis. Actually, physiologic phimosis is common in male patients up to 3 years of age, but often extends into older age groups. Balanoposthitisis a common inflammation occurring in 4-11% of uncircumcised boys. Circumcision is generally undertaken for three reasons: first, as an item of religious practice, typically neonatally although occasionally transpubertally, as a rite of passage; second, as a prophylactic measure against future ailments for the reduction in the risk of penile cancer, urinary tract infection, and sexually transmitted infection; and third, for immediate medical indication. Balanitisxeroticaobliterans is an infiltrative skin condition that causes a pathological phimosis and has been considered to be the only absolute indication for circumcision. Various kinds of effective alternatives to circumcision have been described, including manual retraction therapy, topical steroid therapy, and several variations of preputioplasty. All of these treatments have the ability to retract the foreskin as their goal and do not involve the removal of the entire foreskin. Paraphimosis is a condition in which the foreskin is left retracted. When manipulation is not effective, a dorsal slit should be done, which is usually followed by circumcision.
    The Scientific World Journal 01/2011; 11:289-301. · 1.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The aim of this study was to clarify risk factors related to postoperative urinary incontinence after laparoscopic radical prostatectomy (LRP). Patients and Methods: Outcomes of 214 consecutive patients who underwent LRP at our institute between April 2001 and January 2009 were reviewed. Patients were divided into 2 groups, continent patients (group A: n = 172), who used one or fewer urinary pads per day 6 months after LRP, and incontinent patients (group B: n = 42), who used two or more pads per day 6 months after LRP. Patient age, prostate specific antigen before LRP, blood loss, duration of indwelling urethral catheter, and the positive margin rate between the 2 groups were compared. In addition, surgical videos were reviewed with attention paid to surgical procedures. We examined the correlation between the occurrence of urinary incontinence and the rate of patients with intra-operative damage to the pelvic diaphragm musculature and difficulty in exposure of the urethra during LRP. Results: There were no significant differences in patient age, prostate specific antigen before LRP, blood loss, duration of indwelling urethral catheter, positive margin rate between groups A and B. However, significant differences were found in the rate of patients with damage to the pelvic diaphragm musculature (16.3 and 73.8&percnt;, respectively) and difficulty in exposure of the urethra (20.9 and 83.3&percnt;, respectively) during LRP. Conclusions: Intra-operative damage to the pelvic diaphragm musculature and difficulty in exposure of the urethra during LRP are risk factors of urinary incontinence after LRP.Copyright © 2011 S. Karger AG, Basel
    Current Urology 01/2011; 5:185-189.

Publication Stats

941 Citations
440.83 Total Impact Points

Institutions

  • 2014
    • Fukushima Medical University
      Hukusima, Fukushima, Japan
  • 1996–2013
    • Nagoya City University
      • • Division of Nephrologyogy
      • • Department of Nephro-urology
      • • Department of Radiology
      • • Department of Urology
      Nagoya, Aichi, Japan
  • 2005
    • Numazu City Hospital
      Sizuoka, Shizuoka, Japan