Shinnosuke Kuroda

Development and internal validation of a nomogram for predicting stone-free status after flexible ureteroscopy for renal stones.

To develop and internally validate a preoperative nomogram for predicting stone‐free status (SF) after flexible ureteroscopy (fURS) for renal stones, as there is a need to predict the outcome of fURS for the treatment of renal stone disease.

Retrograde intrarenal surgery for urinary stone disease in patients with solitary kidney: A retrospective analysis of the efficacy and safety

To compare outcomes of retrograde intrarenal surgery for urolithiasis between patients with solitary kidneys and patients who have single‐side urolithiasis with bilateral kidneys.

Inverse correlation between reactive oxygen species in unwashed semen and sperm motion parameters as measured by a computer-assisted semen analyzer.

This study investigated the correlation between sperm motion parameters obtained by a computer-assisted semen analyzer and levels of reactive oxygen species in unwashed semen. In total, 847 patients, except for azoospermic patients were investigated. At the time of each patient′s first consultation, semen parameters were measured using SMAS™ or CellSoft 3000™, and production of reactive oxygen species was measured using a computer-driven LKB Wallac Luminometer 1251 Analyzer. The patients were divided into two groups: reactive oxygen species - positive and negative. The semen parameters within each group were measured using one of the two computer-assisted semen analyzer systems and then compared. Correlations between reactive oxygen species levels and sperm motion parameters in semen from the reactive oxygen species - positive group were also investigated. Reactive oxygen species were detected in semen samples of 282 cases (33.3%). Sperm concentration (P < 0.01; P < 0.01), motility (P < 0.01; P < 0.05), and progressive motility (P < 0.01; P < 0.01) were markedly lower in the reactive oxygen species - positive group than in the reactive oxygen species - negative group. Among the sperm motion parameters in the reactive oxygen species - positive group, sperm concentration (P < 0.01; P < 0.01), motility (P < 0.05; P < 0.01), mALH (P < 0.05; P < 0.01), and progressive motility (P < 0.05; P < 0.01) also showed inverse correlations with the logarithmic transformed reactive oxygen species levels. Therefore, this study demonstrated that excessive reactive oxygen species in semen damage sperm concentration, motility, and other sperm motion parameters.

Preoperative factors predicting spontaneous clearance of residual stone fragments after flexible ureteroscopy

To investigate factors predicting spontaneous clearance of residual renal fragments after flexible ureteroscopy.

Effect of density gradient centrifugation on reactive oxygen species in human semen.

ABSTRACT Density gradient centrifugation can separate motile sperm from immotile sperm and other cells for assisted reproduction, but may also remove antioxidants from seminal plasma, resulting in oxidative stress. Therefore, we investigated reactive oxygen species (ROS) concentrations and distribution in semen before and after density gradient centrifugation. We assessed semen volume, sperm concentration, sperm motility, and ROS levels before and after density gradient centrifugation (300 x g for 20 minutes) in 143 semen samples from 118 patients. The ROS removal rate was evaluated in ROS-positive samples and ROS formation rate in ROS-negative samples. Thirty-eight of 143 untreated samples (26.6%) were ROS-positive; sperm motility was significantly lower in these samples than in ROS-negative samples (p < 0.05). After density gradient centrifugation, only seven of the 38 ROS-positive samples (18.42%) exhibited a ROS-positive lower layer (containing motile sperm) with a ROS removal rate of 81.58%, whereas the upper layer was ROS-positive in 24 samples (63.16%). In the ROS-negative group (n = 105), ROS was detected in 19 samples after centrifugation (18.10%, ROS generation rate), of which 18 were ROS-positive only in the upper layer or interface and the other was ROS-positive in both layers. Density gradient centrifugation can separate motile sperm from immotile sperm as well as remove ROS (including newly generated ROS). This data supports the view that density gradient centrifugation can select motile spermatozoa without enhancing oxidative stress. Abbreviations: ROS: reactive oxygen species; SOD: superoxide dismutase; GPx: glutathione peroxidase; DNA: deoxyribonucleic acid; DGC: density gradient centrifugation; IUI: intrauterine insemination; IVF: in vitro fertilization; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; EDTA: ethylenediaminetetraacetic acid; HTF: HEPES-buffered human tubal fluid; IMSI: intracytoplasmic morphologically selected sperm injection; SMAS: sperm motility analyzing system; CASA: computer-assisted semen analyzer; WHO: World Health Organization

Reactive oxygen species measured in the unprocessed semen samples of 715 infertile patients

To determine whether reactive oxygen species (ROS) in semen samples could be measured with the Monolight™ 3010 Luminometer.

Risk factors of systemic inflammation response syndrome after endoscopic combined intrarenal surgery in the modified Valdivia position

To identify risk factors of developing systemic inflammation response syndrome after endoscopic combined intrarenal surgery in the modified Valdivia position for renal stone treatment.

Developing a preoperative predictive model for ureteral length for ureteral stent insertion

BackgroundUreteral stenting has been a fundamental part of various urological procedures. Selecting a ureteral stent of optimal length is important for decreasing the incidence of stent migration and complications. The aim of the present study was to develop and internally validate a model for predicting the ureteral length for ureteral stent insertion.MethodsThis study included a total of 127 patients whose ureters had previously been assessed by both intravenous urography (IVU) and CT scan. The actual ureteral length was determined by direct measurement using a 5-Fr ureteral catheter. Multiple linear regression analysis with backward selection was used to model the relationship between the factors analyzed and actual ureteral length. Bootstrapping was used to internally validate the predictive model.ResultsPatients all of whom had stone disease included 76 men (59.8%) and 51 women (40.2%), with the median and mean (± SD) ages of 60 and 58.7 (±14.2) years. In these patients, 53 (41.7%) right and 74 (58.3%) left ureters were analyzed. The median and mean (± SD) actual ureteral lengths were 24.0 and 23.3 (±2.0) cm, respectively. Using the bootstrap methods for internal validation, the correlation coefficient (R2) was 0.57 ± 0.07.ConclusionWe have developed a predictive model, for the first time, which predicts ureteral length using the following five preoperative characteristics: age, side, sex, IVU measurement, and CT calculation. This predictive model can be used to reliably predict ureteral length based on clinical and radiological factors and may thus be a useful tool to help determining the optimal length of ureteral stent.

A new prediction model for operative time of flexible ureteroscopy with lithotripsy for the treatment of renal stones

This study aimed to develop a prediction model for the operative time of flexible ureteroscopy (fURS) for renal stones. We retrospectively evaluated patients with renal stones who had been treated successfully and had stone-free status determined by non-contrast computed tomography (NCCT) 3 months after fURS and holmium laser lithotripsy between December 2009 and September 2014 at a single institute. Correlations between possible factors and the operative time were analyzed using Spearman’s correlation coefficients and a multivariate linear regression model. The P value < 0.1 was used for entry of variables into the model and for keeping the variables in the model. Internal validation was performed using 10,000 bootstrap resamples. Flexible URS was performed in 472 patients, and 316 patients were considered to have stone-free status and were enrolled in this study. Spearman’s correlation coefficients showed a significant positive relationship between the operation time and stone volume (ρ = 0.417, p < 0.001), and between the operation time and maximum Hounsfield units (ρ = 0.323, p < 0.001). A multivariate assessment with forced entry and stepwise selection revealed six factors to predict the operative time of fURS: preoperative stenting, stone volume, maximum Hounsfield unit, surgeon experience, sex, and sheath diameter. Based on this finding, we developed a model to predict operative time of fURS. The coefficient of determination (R2) in this model was 0.319; the mean R2 value for the prediction model was 0.320 ± 0.049. To our knowledge, this is the first report of a model for predicting the operative time of fURS treatment of renal stones. The model may be used to reliably predict operative time preoperatively based on patient characteristics and the surgeons’ experience, plan staged URS, and avoid surgical complications.

Oxidative stress marker 8-hydroxyguanosine is more highly expressed in prostate cancer than in benign prostatic hyperplasia

Oxidative stress is a primary cause of vascular endothelial damage. In the prostate, ischemia increases the levels of reactive oxygen species, growth factors and cytokines, and induces the development of angiogenesis, which results in cancer progression. The expression levels of an oxidative stress marker, 8-hydroxyguanosine (8-OHdG), were compared between prostate cancer and non-neoplastic prostate tissues. A prostate tissue microarray composed of 10 cases of prostatic adenocarcinoma and 70 cases of benign prostatic hyperplasia was immunohistochemically stained for 8-OHdG. All cases expressed 8-OHdG. The levels of 8-OHdG expression in prostatic cancer (30.0% moderate and 70.0% strong) were significantly higher than those in benign prostatic hyperplasia (71.4% moderate and 28.6% strong; (p<0.01). Notably, 8-OHdG is expressed more highly in prostate cancer tissues in comparison to benign prostate tissues.