Kenji Omura

Proto-oncogene, Pim-3 with serine/threonine kinase activity, is aberrantly expressed in human colon cancer cells and can prevent Bad-mediated apoptosis

We previously observed that Pim‐3 with serine/threonine kinase activity, was aberrantly expressed in malignant lesions of endoderm‐derived organs, liver and pancreas. Because Pim‐3 protein was not detected in normal colon mucosal tissues, we evaluated Pim‐3 expression in malignant lesions of human colon, another endoderm‐derived organ. Pim‐3 was detected immunohistochemically in well‐differentiated (43/68 cases) and moderately differentiated (23/41 cases) but not poorly differentiated colon adenocarcinomas (0/5 cases). Moreover, Pim‐3 proteins were detected in adenoma (35/40 cases) and normal mucosa (26/111 cases), which are adjacent to adenocarcinoma. Pim‐3 was constitutively expressed in SW480 cells and the transfection with Pim‐3 short hairpin RNA promoted apoptosis. In the same cell line, a pro‐apoptotic molecule, Bad, was phosphorylated at Ser112 and Ser136 sites of phosphorylation that are representative of its inactive form. Ser112 but not Ser136 phosphorylation in this cell line was abrogated by Pim‐3 knockdown. Furthermore, in human colon cancer tissues, Pim‐3 co‐localized with Bad in all cases (9/9) and with phospho‐Ser112Bad in most cases (6/9). These observations suggest that Pim‐3 can inactivate Bad by phosphorylating its Ser112 in human colon cancer cells and thus may prevent apoptosis and promote progression of human colon cancer. (Cancer Sci 2007; 98: 321–328)

Experimental study on heat production by a 23.5-kHz ultrasonically activated device for endoscopic surgery

Abstract. An experimental study was carried out to evaluate heat production by an ultrasonically activated device (USAD) using an animal model. In an anesthetized living pig, the gastroepiploic and mesenteric vessels were coagulated and cut by an USAD at a power level of 70% (n= 8) or 100% (n= 8). During the division, the time-discrete temperature change on the surface of the animal tissue adjacent to the blade was measured by thermography. To compare the USAD with conventional electrocautery (EC), a full-thickness incision of the gastric wall was performed by each device, and the temperature change was measured. With the USAD, the temperature increased gradually and remained below 150°C during the entire activating time at both power levels. By contrast, with EC at 30 W, the temperature increased rapidly and exceeded 350°C within only a few seconds. The area above 60°C reached a final width of 10 mm for the USAD, as compared with 22 mm for EC. Microscopically, thermal alterations such as carbonization and vaporization were much more severe and extensive in the adjacent tissue when using EC rather than the USAD. With the USAD, heat production is much slower and more limited than with conventional EC; thus, the USAD causes fewer thermal alterations in adjacent tissue. USAD should be preferred for tissue coagulation and cutting during endscopic surgery.

Small amount of low-residue diet with parenteral nutrition can prevent decreases in intestinal mucosal integrity

OBJECTIVE To investigate the suitable combination ratio of low-residue diet (LRD) and parenteral nutrition (PN) for nutritional support of surgical patients. SUMMARY BACKGROUND DATA Bacterial translocation (BT) is a severe complication of total parenteral nutrition (TPN). However, it is sometimes impossible to supply sufficient amounts of nutrients to surgical patients by the enteral route. The authors reported previously that concomitant use of LRD with PN provided preferable nutritional support for patients undergoing surgery for colorectal cancer. METHODS Ninety male Donryu rats were used for three experiments. In experiment 1, rats were divided into two groups to receive TPN or total enteral nutrition with LRD. In experiment 2, rats were divided into six groups, receiving variable amounts of LRD. In experiment 3, rats were divided into five groups to receive isocaloric nutritional support with variable proportions of PN and LRD. Intestinal permeability was assessed by monitoring urinary excretion of phenolsulfonphthalein. BT was assessed in tissue cultures of mesenteric lymph nodes and spleen. RESULTS In experiment 1, increases in intestinal permeability and BT were observed in rats maintained on 7-day TPN, but not in those maintained on total enteral nutrition for up to 14 days. In experiment 2, the changes in body weight of rats were correlated with the dose of LRD. However, the intestinal permeability was increased only in rats receiving LRD at 15 kcal/kg per day. In experiment 3, additive LRD corresponding to 15% of total caloric intake prevented increases in intestinal permeability and BT. CONCLUSION Combined nutritional therapy consisting of PN and small amounts of LRD can provide better nutritional support than TPN for surgical patients.

Functional polymorphism of the thymidylate synthase gene in colorectal cancer accompanied by frequent loss of heterozygosity.

The thymidylate synthase (TS) gene has a polymorphic repeated sequence in its 5′‐untranslated region. The repeat length is associated with TS protein expression, which suggests that we may be able to predict the efficacy of 5‐fluorouracil (S‐FU)‐based chemotherapy from a patients TS genotype determined through analysis of normal tissue obtained non‐invasively. However, it is not yet elucidated whether the TS genotype is identical in tumor and normal tissue. In this study, we investigated the TS genotype in 151 matched tumor and normal DNA samples isolated from colorectal cancer and adjacent normal tissues by PCR analysis. The results showed that TS genotypes are identical in normal and tumor tissues of homozygous individuals, suggesting that the repeat sequence is stable through carcinogenesis. However, in heterozygous samples, an unbalance between the 2R and 3R alleles in the tumor DNA was frequently observed, suggesting loss of heterozygosity (LOH) at the TS locus. Detailed LOH analysis revealed that 62% (31 of 50) of 2R/3R‐heterozygous samples had LOH. Frequent LOH at the TS locus was confirmed by RT‐PCR of TS mRNA and microsatellite analysis using the marker D18S59, located on 18p11.3. There was no difference in the expressions of TS mRNA and TS protein between LOH and non‐LOH samples. However, when the heterozygous genotype bearing LOH was subdivided according to the number of repeats, the cancer tissue with 2R/loss genotype expressed a significantly lower level of TS protein than did that with 3R/loss genotype. The results suggest that the difference in TS genotype between tumor and normal tissue due to LOH should be considered when the genotype is analyzed with normal tissue, such as peripheral blood cells, because it is important for TS protein expression.

How secure are the arteries occluded by a newly developed ultrasonically activated device

AbstractBackground: We developed a new ultrasonically activated device (USAD) for endoscopic surgery. The current investigation was conducted to evaluate the security of the arteries occluded and divided by this USAD. Methods: The intraperitoneal arteries of anesthetized living pigs were individually occluded by the USAD at power levels of 70% or 100%. The burst pressures of the harvested arteries were measured in vitro. For comparison, arteries occluded by laparoscopic clips or silk ligatures were evaluated in the same manner. Results: The pressures to burst the occluded artery ranged from 353 to 2,148 mmHg with an average of 1,204 mmHg in the USAD group at 70% power level; from 324 to 2,207 mmHg with an average of 1,193 mmHg in the USAD group at 100% power level; from 794 to 1,868 mmHg with an average of 1,421 mmHg in the clip group; and from 618 to 3,207 mmHg with an average of 1,586 mmHg in the silk ligature group. Conclusion: The data suggest the improbability that small- to medium-size arteries appropriately occluded and divided by the USAD can burst when exposed to intravascular pressures commonly found in living animals.

Transanal endoscopic microsurgery in the treatment of rectal carcinoid tumor

BackgroundThis study aimed to assess the efficacy of transanal endoscopic microsurgery (TEM) in the treatment of rectal carcinoid tumor.MethodsBetween May 1994 and April 2006, 27 patients with rectal carcinoid tumor underwent TEM, and their clinical data were reviewed retrospectively.ResultsThe TEM procedure was performed as a primary excision (n = 14) or as completion surgery after incomplete resection by endoscopic polypectomy (n = 13). The average size of a primary tumor was 9.1 mm (range, 5–13 mm), and the average distance of the tumor from the anal verge was 8.5 cm. The mean duration of the operation was 51.6 min. Minor morbidities, transient soilage, and mild dehiscence occurred in two cases (7.4%). Histopathologically, all tumors were localized within the submucosal layer showing typical histology without lymphatic or vessel infiltration, and both deep and lateral surgical margins were completely free of tumors. Among 13 cases of completion surgery after endoscopic polypectomy, 4 (30.8%) were histologically shown to have a residual tumor in the specimens obtained by TEM. No additional radical surgery was performed. The mean follow-up period was 70.6 months, and no recurrence was noted.ConclusionThe results indicate that TEM is a safe, minimally invasive procedure for the local excision of rectal carcinoid tumors, particularly those in the proximal rectum. Furthermore, for patients with microscopic positive margins after endoscopic polypectomy, TEM can be an effective surgical option for complete removal of residual tumors.

Clinical implications of dihydropyrimidine dehydrogenase (DPD) activity in 5-FU-based chemotherapy: mutations in the DPD gene, and DPD inhibitory fluoropyrimidines.

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the degradation of pyrimidine bases. DPD is also responsible for the degradation of 5-fluorouracil (5-FU), which is the most frequently prescribed anticancer drug for the treatment of malignancies of the gastrointestinal tract. DPD could influence the antitumor effect and the adverse effects of 5-FU. High intratumoral DPD activity markedly decreases the cytotoxic effect of 5-FU. More than 80% of administered 5-FU is detoxified and excreted as F-β-alanine in urine. In 5-FU-based chemotherapy, escape from the degradation catalyzed by DPD is important. Recently, the dihydropyrimidine dehydrogenase gene (DPYD) was isolated, and its physical map and exon-intron organization were determined. To date, many DPYD variant alleles associated with a lack of DPD activity have been identified. In 5-FU-based cancer chemotherapy, severe toxicities were observed at higher rates in patients who were heterozygous for a mutant DPYD allele, compared with toxicities in patients who were homozygous for the wild DPYD allele. Furthermore, the adverse effects of 5-FU are often lethal for patients homozygous for the mutant DPYD allele. The apparently high prevalence of the DPYD mutation associated with lack of DPD activity in the normal population warrants genetic screening for the presence of these mutations in cancer patients before the administration of 5-FU. DPD inhibitory fluoropyrimidines (DIFs), including uracil plus tegafur (UFT) and tegafur plus 5-chloro-2,4-dihydroxypyridine plus potassium oxonate, in a molar ratio of 1 : 0.4 : 1 (TS-1), have recently been used in clinical settings. DIFs should provide chemotherapy that improves both quality of life and duration of survival.

A phase II study of preoperative chemotherapy with S-1 plus cisplatin followed by D2/D3 gastrectomy for clinically serosa-positive gastric cancer (JACCRO GC-01 study)

AIMS Clinically serosa-positive (T3-4) gastric cancer has a poor prognosis. This phase II trial explored the feasibility and safety of preoperative chemotherapy followed by D2 or D3 gastrectomy in this type of gastric cancer. METHODS Patients with T3-4 gastric cancer received one course of S-1 (80mg/m(2) daily for 3 weeks) and cisplatin (60mg/m(2) on day 8) chemotherapy and then underwent D2 or D3 gastrectomy with curative intent. Primary endpoint was toxicities. RESULTS Of 50 patients enrolled, 49 were eligible and received the treatment protocol. Chemotherapy-related toxicities were mild; grade 3 neutropenia in 2 patients, anorexia in 3, and nausea in 2, and no grade 4 toxicities. Clinical response was achieved in 13 of 34 evaluable patients. Of the 49 patients, 39 underwent D2 or D3 dissection. There was no surgical mortality. Operative morbidity occurred in 5 of 49 patients, including pancreatic fistula in 1 and abdominal abscess in 2. CONCLUSION This multi-modality treatment seems to be feasible and safe for T3-4 gastric cancer.

Tissue oxygen saturation during colorectal surgery measured by near-infrared spectroscopy: pilot study to predict anastomotic complications.

We investigated the relation between tissue oxygen saturation measured by near-infrared spectroscopy (NIRS) and anastomotic complications associated with colorectal surgery. A series of 20 patients with colorectal cancer underwent radical surgery with enteric anastomosis. Measurements of tissue oxygen saturation (StO2) were performed at both the proximal and distal portions of the anastomotic site; in cases of anterior resection, we measured StO2 only in the proximal portion. Two anastomotic complications (one leakage, one stenosis) occurred in the 20 cases. The StO2 in patients with anastomotic complications was 58.0%, and that in patients without complications was 71.0%. Altogether, 18 patients had StO2 values > 66%, and none of them had anastomotic complications. In contrast, 2 patients had StO2 values < 60%, and both had anastomotic complications. The StO2 of the anastomotic site can be safely and reliably measured by NIRS during colorectal surgery. Low StO2 on both sides of the anastomosis may indicate an increased risk of anastomotic complications. Further study is needed to determine the cutoff value for StO2 required to prevent serious complications.

The effects of an additive small amount of a low residual diet against total parenteral nutrition–induced gut mucosal barrier

BACKGROUND Total parenteral nutrition (TPN) negatively influences the gut mucosal barrier. It has been suggested that enteral nutrition is effective against the harmful influence. METHODS Forty-eight male Donryu rats underwent placement of a central venous catheter and tube gastrostomy. They were divided into six groups, receiving isocaloric nutrients in various proportions of PN and a low residual diet (LRD) for 7 days. RESULTS Intestinal permeability, villous height and crypt depth, and number of secretory IgA-positive cells in the villus were measured. Intestinal permeability was significantly reduced in rats receiving an LRD corresponding to more than 15% of total caloric intake. Gut morphological structure was maintained in rats receiving an LRD corresponding to more than 10%. A higher number of IgA-positive cells was observed in rats receiving an LRD corresponding to more than 15%. CONCLUSIONS A small amount of LRD could prevent decreases in gut mucosal integrity. There was a stepwise defense mechanism in the gut mucosal barrier.