Junichi Matsuzaki

Bio: Junichi Matsuzaki is an academic researcher from Yokohama City University. The author has contributed to research in topics: Ureteroscopy & Nephrostomy. The author has an hindex of 14, co-authored 64 publications receiving 792 citations.

Ureteral stent encrustation, incrustation, and coloring: morbidity related to indwelling times.

Abstract: Background and Purpose: Ureteral stents are a fundamental part of many urologic procedures. Serious complications, including migration, fragmentation, and stone formation, still occur, especially when stents have been forgotten for a long time. No widespread consensus for the type or indwelling time to avoid ureteral stent complications has been reached, however. We investigated the correlation between the indwelling time and encrustation, incrustation, coloration, and resistance to removal. Patients and Methods: A total of 330 ureteral stents in 181 patients were examined. Results: Overall, 155 (47.0%) stents were encrusted, and the encrustation rate was 26.8% at less than 6 weeks, 56.9% at 6 to 12 weeks, and 75.9% at more than 12 weeks. A total of 46 (13.9%) stents resisted removal, and 3 of these could not be removed by cystoscopy. The median indwelling time was 72 (14–124) days for stents that resisted removal and 31 (30–60) days for irremovable stents. The frequency of encrustation with colo...

Predictive Value of Attenuation Coefficients Measured as Hounsfield Units on Noncontrast Computed Tomography During Flexible Ureteroscopy with Holmium Laser Lithotripsy: A Single-Center Experience

Abstract: Purpose: To assess the utility of attenuation coefficients as predictors of surgical outcome after a single flexible ureteroscopy (URS) with holmium laser lithotripsy. Many reports indicate that the efficacy of extracorporeal shockwave lithotripsy (SWL) can be predicted by the target's radiofrequency attenuation, measured as Hounsfield units (HUs) on noncontrast CT (NCCT). Studies of flexible URS, however, have not assessed the predictive value of attenuation coefficients on NCCT. Patients and Methods: Patients with renal stones who were treated by flexible URS with holmium laser lithotripsy between December 2009 and October 2011 at a single institute were retrospectively evaluated. Stone-free (SF) status was determined by kidneys-ureters-bladder (KUB) radiography at postoperative month 3. Correlations of possible predictors with SF status were analyzed using a logistic regression model. The comparison between groups with low and high HUs was examined using the Mann-Whitney U test. Results: There...

Ureteroscopy assisted retrograde nephrostomy: a new technique for percutaneous nephrolithotomy (PCNL).

Abstract: UNLABELLED Study Type - Therapy (case series). Level of Evidence 4. What's known on the subject? and What does the study add? Retrograde nephrostomy was first developed by Lawson et al. in 1983, and Hunter et al. reported 30 cases of retrograde nephrostomy in 1987. This procedure uses less radiation exposure and has a shorter duration compared with the previous percutaneous nephrostomy techniques. Retrograde nephrostomy using Lawson's procedure was reported in the late 1980s by several authors. But since then, few studies have been reported about this procedure due to the development of ultrasonography assisted percutaneous nephrostomy. With the arrival and development of the flexible ureteroscope (URS) both observation and manipulation in the renal pelvis are now easily achieved. The present procedure provides less radiation exposure, less bleeding, and a shorter procedure than previous percutaneous nephrostomy techniques. Using this procedure, after the needle has exited through the skin, no further steps are required in preparation for dilatation. In the present study, we continuously visualised from puncture to inserting the nephron-access sheath with the URS. OBJECTIVE • To describe a technique for ureteroscopy assisted retrograde nephrostomy. PATIENTS AND METHODS • Under general and epidural anaesthesia, the patient is placed in a modified-Valdivia position. Flexible ureteroscopy is carried out, and a Lawson retrograde nephrostomy puncture wire is placed in the ureteroscope (URS). • After the needle has exited through the skin, no further steps are required in preparation for dilatation. RESULTS • After informed consent was obtained, two patients (a 43-year-old man with left renal stones and a 57-year-old woman with right renal stones) underwent this procedure. • The URS was positioned in the middle posterior calyx and punctured toward the skin. CONCLUSIONS • This procedure involves less radiation exposure and shorter surgery than the previous percutaneous nephrostomy technique. • Our technique represents another new option for percutaneous nephrolithotomy in patients with a non-dilated intrarenal collecting system.

A Mutator Phenotype in Cancer

Abstract: We have proposed that an early step in tumor progression is the expression of a mutator phenotype resulting from mutations in genes that normally function in the maintenance of genetic stability. There is new and strong experimental evidence that supports the concept of a mutator phenotype in cancer. As technologies for chromosomal visualization and DNA advance, there are increasing data that human cancer cells contain large numbers of mutations. First, I will review the concept of a mutator phenotype. Second, I will present the recent evidence that individual cancer cells contain thousands of mutations. Third, I will explore potential target genes that are required for maintenance of genetic stability in normal cells and ask if they are mutated in cancer cells. Fourth, I will address the timing of a mutator phenotype; is it an early event during tumor progression? Do tumors already contain cells that harbor mutations rendering them resistant to most chemotherapeutic agents? Lastly, I will speculate on the theoretical and practical implication of a mutator phenotype in cancer and consider the possibility of cancer prevention by delay, i.e., a reduction in mutation rates early during carcinogenesis might slow the progression of tumors.

The Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study: indications, complications, and outcomes in 5803 patients.

Abstract: Purpose: To assess the current indications, perioperative morbidity, and stone-free outcomes for percutaneous nephrolithotomy (PCNL) worldwide. Patients and Methods: The Clinical Research Office of the Endourological Society (CROES) collected prospective data for consecutive patients who were treated with PCNL at centers around the world for 1 year. PCNL was performed according to study protocol and local clinical practice guidelines. Stone load and location were recorded, and postoperative complications were graded according to the modified Clavien grading system. Results: Between November 2007 and December 2009, 5803 patients were treated at 96 centers in Europe, Asia, North America, South America, and Australia. Staghorn calculus was present in 1466 (27.5%) patients, and 940, 956, and 2603 patients had stones in the upper, interpolar, and lower pole calices, respectively. The majority of procedures (85.5%) were uneventful. Major procedure-related complications included significant bleeding (7....

Is there a link between DNA polymerase beta and cancer

Abstract: Recent small-scale studies have shown that 30% of human tumors examined to date express DNA polymerase beta variant proteins. One of the DNA polymerase beta colon cancer-associated mutants, K289M, has been shown to synthesize DNA with a lower fidelity than wild-type Pol beta. Thus, the K289M protein could confer a mutator phenotype to the cell, resulting in genomic instability. Another DNA polymerase beta variant identified in colon carcinoma interferes with base excision repair in cells. This may result in unfilled gaps which can serve as substrates for recombination and result in genomic instability. DNA polymerase beta has also been shown to be overexpressed in a variety of tumors. In some cases, overexpression of polymerase beta in cells confers a transformed phenotype to the cells. In other cases, overexpression results in telomere fusions. Thus, mutant forms or aberrant quantities of polymerase beta confer a mutator phenotype to cells. Combined with the small-scale tumor studies, these mechanistic studies implicate variant forms of DNA polymerase beta in the etiology of human cancer.

Expression Profiles of ErbB Family Receptors and Prognosis in Primary Transitional Cell Carcinoma of the Urinary Bladder

Abstract: In vitro experiments have demonstrated that epidermal growth factor (EGF)-related peptides activate distinct subsets of ErbB receptors and differ in their biological activities. The implications of cross-talk among ErbB family receptors in human cancer, however, remain to be clarified. This cohort study was performed to examine the expression patterns of ErbB receptors by immunohistochemistry in primary human bladder cancer (n = 245) and compared with conventional biological indicators for their prognostic significance. Expression of individual EGF receptor (EGFR) and ErbB2, ErbB3, or ErbB4 receptors was detected in 72.2, 44.5, 56.3, and 29.8% of bladder cancer cases, respectively. Expression of two of the receptors varied from 14.7 to 42.4%, of three of the receptors between 11.0 and 22.0%, and of all four of the ErbB receptors by 8.6%. Important indicators in association with patient survival were tumor staging (P = 0.017), ErbB2 (P = 0.018), EGFR-ErbB2 (P = 0.023), and ErbB2-ErbB3 (P = 0.042). In the subset of grade-2 tumors, EGFR-ErbB2-ErbB3 and EGFR-ErbB2 predicted the development of second recurrence (P = 0.026 and 0.039, respectively), and ErbB2-ErbB3 tended to correlate with patient survival (P = 0.09). The results indicate that a combination of EGFR, ErbB2, and ErbB3 expression profile may be a better prognostic indicator than any family member alone. Given that ErbB2 is the preferred coexpression partner of ErbB family members, expression of other ErbB receptors may significantly affect the prognostic implication of ErbB2 for bladder cancer patients.

Cancer cells exhibit a mutator phenotype.

Abstract: This review analyzes the concept and evidence in support of a mutator phenotype in human cancer. The large number of mutations reported in tumor cells cannot be accounted for by the low mutation rates observed in normal somatic cells; rather, it must be a manifestation of a mutator phenotype present early during the tumorigenic process. The interaction between increased mutagenesis and clonal selection provides a mechanism for the selection of cells with increased proliferative advantage. The concept of a mutator phenotype in cancer has gained considerable support from the findings of enormous numbers of somatic mutations in repetitive sequences in human tumors. Moreover, cell lines exhibiting microsatellite instability demonstrate an increased mutation frequency in expressed genes. A knowledge of mechanisms that generate multiple mutations in cancer cells has important implications for prevention. For many tumors, a delay in the rate of accumulation of mutations by a factor of two could drastically reduce the death rates from these tumors.