PubMed Health⌕ Search

Biomedical subjects

Toshiaki Watanabe

Publications and source records attributed to Toshiaki Watanabe.

At least 19 recordsLinked to original sources
PubMed2007

Prognosis and risk factors of metastasis in colorectal carcinoids: results of a nationwide registry over 15 years.

BACKGROUND: Colorectal carcinoids are often described as low-grade malignant. However, no study has compared the survival between patients with colorectal carcinoids and those with carcinomas, in a large series. In addition, no global consensus has been established on the crucial determinants of metastasis in colorectal carcinoids. AIM: To determine the predictive factors for metastasis in colorectal carcinoids and clarify their prognosis compared with adenocarcinomas. METHODS: Data of all patients diagnosed as having colorectal carcinoids were extracted from a large nationwide database of colorectal tumours, the Multi-Institutional Registry of Large-Bowel Cancer in Japan, for the period from 1984 to 1998. Risk factors for lymph node (LN) metastases and distant metastases were analysed among those who were undergoing surgery, by univariate and multivariate analysis. Cancer-specific survival was also compared between patients with colorectal carcinoids and those with adenocarcinomas registered in the same period. RESULTS: Among the 90 057 cases of colorectal tumours that were diagnosed, a total of 345 cases of carcinoids were identified, including 247 colorectal carcinoids of those undergoing surgery. Risk factors for LN metastasis were tumour size >/=11 mm and lymphatic invasion, whereas those for distant metastasis were tumour size >/=21 mm and venous invasion. Colorectal carcinoids without these risk factors exhibited no LN metastasis or distant metastasis. Cancer-specific survival of patients with colorectal carcinoids without metastasis was better than that of those with adenocarcinomas. However, the survival was similar between carcinoids and adenocarcinomas if the tumours had LN metastasis or distant metastasis. CONCLUSIONS: The presence of metastasis in colorectal carcinoids could lead to survival that is as poor as in adenocarcinomas. Tumours </=10 mm and without lymphatic invasion could be curatively treated by local resection, but others would need radical LN dissection.

Adenocarcinoma↗
PubMed2007

Are free radical reactions increased in the diabetic eye?

Reactive oxygen species (ROS) are thought to play a significant role in the development of diabetic retinopathy; however, no direct evidence supports ROS generation in vivo. This study used in vivo electron spin resonance (ESR) spectroscopy with a surface resonator to detect local free radical reactions. The ESR signal decay of carbamoyl-PROXYL was enhanced in the eyes of streptozotocin (STZ)-induced diabetic mice. This enhanced signal decay was suppressed by the administration of SOD or the pretreatment with aminoguanidine. We demonstrate, for the first time, specific free radical reactions in the eyes of mice with STZ-induced diabetes.

Animals↗
PubMed2006

Phosphorylation of ribosomal p70 S6 kinase and rapamycin sensitivity in human colorectal cancer.

We investigated the Akt-mTOR pathway and effects of rapamycin using human colorectal cancer cell lines. LoVo and CaRI reduced proliferative activity in response to rapamycin in a dose-dependent manner. The phosphorylation of Akt and p70 S6K was prominent in these cells. Rapamycin quickly downregulated phospho-S6K but not phospho-Akt. Therefore, phospho-S6K is considered a good indicator of the activated Akt-mTOR pathway as well as rapamycin sensitivity in colorectal cancer cells. By immunohistochemical study, nearly 40% of adenomas and carcinomas of the colorectum exhibited either partial or whole positive staining for phospho-S6K, suggestive of rapamycin-sensitive lesions.

Antibiotics, Antineoplastic↗
PubMed2006

Distal colorectal cancers with microsatellite instability (MSI) display distinct gene expression profiles that are different from proximal MSI cancers.

Promoter methylation of the mismatch repair gene plays a key role in sporadic microsatellite instability (MSI) colorectal cancers. However, promoter methylation often occurs in proximal colon cancers, and molecular phenotypes underlying MSI cancers in distal colon have not been fully clarified. Our goal was to clarify the difference between MSI and microsatellite stability (MSS) cancers and, furthermore, to determine distinct characteristics of proximal and distal MSI cancers. By DNA microarray analysis of 84 cancers (33 MSI and 51 MSS), we identified discriminating genes (177 probe sets), which predicted MSI status with a high accuracy rate (97.6%). These genes were related to phenotypic characteristics of MSI cancers. Next, we identified 24 probe sets that were differentially expressed in proximal and distal MSI cancers. These genes included promoter methylation-mediated genes, whose expression was significantly down-regulated in proximal MSI cancers. Among discriminating genes between MSI and MSS, nine methylation-mediated genes showed down-regulation in MSI cancers. Of these, 7 (77.8%) showed down-regulation in proximal MSI cancers. Furthermore, methylation-specific PCR confirmed that frequency of hMLH1 promoter methylation was significantly higher in proximal MSI cancers (P = 0.0317). These results suggested that there is a difference between proximal and distal MSI cancers in methylation-mediated influence on gene silencing. In conclusion, using DNA microarray, we could distinguish MSI and MSS cancers. We also showed distinct characteristics of proximal and distal MSI cancers. The inactivation form of hMLH, per se, differed between proximal and distal MSI cancers. These results suggested that distal MSI cancers constitute a distinct subgroup of sporadic MSI cancers.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Identification and characterization of two novel classes of small RNAs in the mouse germline: retrotransposon-derived siRNAs in oocytes and germline small RNAs in testes.

Small RNAs ranging in size between 18 and 30 nucleotides (nt) are found in many organisms including yeasts, plants, and animals. Small RNAs are involved in the regulation of gene expression through translational repression, mRNA degradation, and chromatin modification. In mammals, microRNAs (miRNAs) are the only small RNAs that have been well characterized. Here, we have identified two novel classes of small RNAs in the mouse germline. One class consists of approximately 20- to 24-nt small interfering RNAs (siRNAs) from mouse oocytes, which are derived from retroelements including LINE, SINE, and LTR retrotransposons. Addition of retrotransposon-derived sequences to the 3' untranslated region (UTR) of a reporter mRNA destabilizes the mRNA significantly when injected into full-grown oocytes. These results suggest that retrotransposons are suppressed through the RNAi pathway in mouse oocytes. The other novel class of small RNAs is 26- to 30-nt germline small RNAs (gsRNAs) from testes. gsRNAs are expressed during spermatogenesis in a developmentally regulated manner, are mapped to the genome in clusters, and have strong strand bias. These features are reminiscent of Tetrahymena approximately 23- to 24-nt small RNAs and Caenorhabditis elegans X-cluster small RNAs. A conserved novel small RNA pathway may be present in diverse animals.

3' Untranslated Regions↗
PubMed2006

Prospective surveillance effectively reduced rates of surgical site infection associated with elective colorectal surgery at a university hospital in Japan.

At a university hospital in Japan, the introduction of prospective surveillance and subsequent interventions was effective in reducing the rate of surgical site infection associated with elective colorectal surgery from 27.5% to 17.8% of surgeries. Japan should both recognize the importance of broader surveillance for surgical site infection and establish its own nationwide surveillance database.

Colorectal Surgery↗
PubMed2006

Prediction of sensitivity of rectal cancer cells in response to preoperative radiotherapy by DNA microarray analysis of gene expression profiles.

Preoperative radiotherapy has been widely used to improve local control of disease and to improve survival in the treatment of rectal cancer. However, the response to radiotherapy differs among individual tumors. Our objective here was to identify a set of discriminating genes that can be used for characterization and prediction of response to radiotherapy in rectal cancer. Fifty-two rectal cancer patients who underwent preoperative radiotherapy were studied. Biopsy specimens were obtained from rectal cancer before preoperative radiotherapy. Response to radiotherapy was determined by histopathologic examination of surgically resected specimens and classified as responders or nonresponders. By determining gene expression profiles using human U95Av2 Gene Chip, we identified 33 novel discriminating genes of which the expression differed significantly between responders and nonresponders. Using this gene set, we were able to establish a new model to predict response to radiotherapy in rectal cancer with an accuracy of 82.4%. The list of discriminating genes included growth factor, apoptosis, cell proliferation, signal transduction, or cell adhesion-related genes. Among 33 discriminating genes, apoptosis inducers (lumican, thrombospondin 2, and galectin-1) showed higher expression in responders whereas apoptosis inhibitors (cyclophilin 40 and glutathione peroxidase) showed higher expression in nonresponders. The present study suggested the possibility that gene expression profiling may be useful in predicting response to radiotherapy to establish an individualized tailored therapy for rectal cancer. Global expression profiles of responders and nonresponders may provide insights into the development of novel therapeutic targets.

Combined Modality Therapy↗
PubMed2006

Risk factors for anastomotic leakage after surgery for colorectal cancer: results of prospective surveillance.

BACKGROUND: Anastomotic leakage in operations for colorectal cancer not only results in morbidity and mortality, but also increases the risk of local recurrence and worsens prognosis. So a better understanding of risk factors for developing anastomotic leakage in colorectal cancer surgery is important to surgeons. The aim of this study was to determine the incidence and risk factors for clinical anastomotic leakage after elective surgery for colorectal cancer. STUDY DESIGN: We conducted prospective surveillance of all elective colorectal resections performed by a single surgeon in a single university hospital from November 2000 to July 2004. The outcomes of interest was clinical anastomotic leakage. Eighteen independent clinical variables were examined by univariate and multivariate analyses. RESULTS: A total of 391 patients undergoing elective operations for colorectal cancer were admitted to the program. Clinical anastomotic leakage was identified in 11(2.8%) patients. Univariate and multivariate analyses showed that preoperative steroid use (odds ratio=8.7), longer duration of operation (odds ratio=9.9), and wound contamination (odds ratio=7.8) were independently predictive of clinical anastomotic leakage. Although there were no statistical differences in leakage rates between patients with and without covering stoma, all four patients requiring reoperation for leakage were without covering stoma. CONCLUSIONS: Preoperative steroid use, longer duration of operation, and contamination of the operative field were independent risk factors for developing clinical anastomotic leakage after elective resection for colorectal cancer. Surgeons should be aware of such high-risk patients, which would help them to decide whether to create a diversion stoma during surgery.

Adult↗
PubMed2006

Cytomegalovirus infection in ulcerative colitis.

OBJECTIVE: Cytomegalovirus (CMV) infection has been reported as an exacerbating factor in inflammatory bowel disease but the relationship between CMV infection and ulcerative colitis (UC) remains unclear. There has been no detailed research to elucidate the clinicopathologic features of CMV infection in UC using surgical specimens. The aim of this study was to investigate the clinicopathologic features of CMV infection in UC patients who had undergone colectomy. MATERIAL AND METHODS: Surgical specimens taken from UC patients were examined for CMV infection. The patients were divided into three groups: severe, refractory, and UC-associated dysplasia or cancer according to the operative indications. CMV infection rates were evaluated and a comparison of clinical parameters was made between CMV-positive and CMV-negative patients, and the risk factors for CMV infection were analyzed using multivariate analyses. RESULTS: It was found that 25% of 32 patients were positive for CMV in the severe UC group; 8.3% of 72 patients were positive for CMV in the refractory UC group. None of the 22 patients was positive for CMV in the UC-associated dysplasia or cancer group. The CMV-positive rate in the severe UC group was significantly higher than that in the other groups (p<0.05). Patients' age at the time of operation was higher in the CMV-positive group than in the CMV-negative group among the patients with severe UC (p<0.01), and age at operation was an independent risk factor for CMV infection. CONCLUSIONS: CMV is found more frequently in severe UC than refractory UC and UC-associated cancer or dysplasia. Higher age can be a risk factor for CMV infection in patients with severe UC. However, a high steroid dose may not always be a risk factor for CMV infection.

Adrenal Cortex Hormones↗
PubMed2006

One-stage completely laparoscopic restorative proctocolectomy for ulcerative colitis complicated with sigmoid colon cancer--a case report.

Recent advances in laparoscopic surgery have made it possible to perform restorative proctocolectomy (RP) for ulcerative colitis (UC) or familial adenomatous polyposis (FAC). However, most of these procedures are performed as two-stage operations with the creation of diverting ileostomy. Furthermore, they are performed with a small abdominal incision from 4 to 8 cm in length. We describe the first case of ulcerative colitis that underwent a single-stage completely laparoscopic restorative proctocolectomy without an abdominal incision. The patient also underwent lymph node dissection since he had a sigmoid colon cancer. The postoperative course was uneventful and the functional outcome was satisfactory. Considering the improved cosmetic as well as functional results achieved by this procedure, the present technology can be applied for selected patients, especially young UC or FAP patients needing RP who seek for a superior cosmetic result.

Adult↗
PubMed2006

Mucinous colorectal cancers with chromosomal instability: a biologically distinct and aggressive subtype.

Colorectal cancers can progress through 2 pathways of genomic instability: microsatellite instability (MSI) and chromosomal instability (CSI). We investigated the influence of CSI and MSI on clinicopathological features and survival of 35 patients affected by mucinous colorectal cancers (MCRC). MSI status was determined by PCR amplification using 5 standard markers. Evidence for CSI was gathered by identifying loss of heterozygosity (LOH) of 4 loci (2p, 5q, 17p, 18q). We defined "MSI-MCRC" as those that showed MSI-H, and "CSI-MCRC" as those that showed LOH at 1 or more of these sites but did not show MSI-H. Among 35 cases, 18 cases (51.4%) were CSI-MCRC, whereas 11 cases (31.4%) were MSI-MCRC. Significant differences were found between CSI-MCRC and MSI-MCRC regarding the following clinicopathological features: tumor location (P=0.00026), lymph node metastasis (P=0.026), and TNM stage (P=0.026). Kaplan-Meier survival curves and log-rank analysis demonstrated that MSI-MCRC was associated with better prognosis than CSI-MCRC, although no significant difference was found (P=0.10). CSI-MCRC correlates more strongly with lymph node metastasis and advanced stage than MSI-MCRC. This indicates that CSI-MCRC is an aggressive subtype.

Adenocarcinoma, Mucinous↗