Seiji Sadamoto

Radiation Induction of Germline Mutation at a Hypervariable Mouse Minisatellite Locus

Paternal 60Co gamma-irradiation was tested for the induction of germline mutation at the mouse hypervariable minisatellite locus, Ms6hm. Male C3H/HeN mice were exposed to 3 Gy 60Co gamma-ray and mated with C57BL/6N females. Matings were made at 1-7, 15-21 and 71-77 days post-treatment to test spermatozoa, spermatids and spermatogonia stages. Reciprocal crosses were also made with irradiated C57BL/6N males. Southern analysis was carried out on DNA from parents and F1 mice. The paternal mutation frequencies per gamete of the Ms6hm locus were 8.3, 13, 28 and 15% for the C3H/HeN control, exposed spermatozoa, spermatids and spermatogonia stages, respectively. The paternal mutation frequencies per gamete were 7.7% for the C57BL/6N control and 13% for the C57BL/6N exposed spermatozoa stage. The increase in the paternal germline mutation frequency was statistically significant for C3H/HeN spermatids irradiation (p < 0.005). The induced mutation frequencies were of the order of 10(-1), and was too high to be accounted for by the direct action of radiation on the locus. These results suggest the presence of a previously unexpected mechanism of radiation induction of germline mutation. In addition, we demonstrate that the hypervariable minisatellite locus can serve as a sensitive monitor for genetic damages to germline cells.

Induction of Transplantable Tumors by Repeated Subcutaneous Injections of Natural and Synthetic Vitamin E in Mice and Rats

Natural vitamin E and synthetic vitamin E (dl/‐α‐tocopheryl acetate) were tested for their tnmorigenicity in rodents. Transplantable tumors, at the site of injection, were induced by repeated injections of these compounds in two strains of mice, NFS/N and C57BL/6N × C3H/He Fl, and in a strain of rats, Fischer 344. Natural vitamin E was tumorigenic in both strains of female mice only when injected with soya oil. In contrast, dl‐α‐tocopheryl acetate alone was capable of inducing tumors in Fischer 344 rats. Only one out of 5 male NFS/N mice given dl‐α‐tocopheryl acetate developed a tumor. Therefore, Fischer 344 rats were more susceptible to tumor formation by dl‐α‐tocopheryl acetate than NFS/N mice. dl‐α‐Tocopheryl acetate with soya oil or with palm oil also resulted in the formation of transplantable tumors in NFS/N mice and Fischer 344 rats. There was no difference in the tumor incidence between mice treated with dl‐α‐a‐tocopheryl acetate alone and dl‐α‐tocopheryl acetate plus soya oil or palm oil. However, in rats, the incidence was lower for a group treated with dl‐α‐tocopheryl acetate plus palm oil than for those with dl‐αa‐tocopheryl acetate alone and with dl‐α‐tocopheryl acetate plus soya oil.

Primary anorectal malignant melanoma: report of a case.

Primary anorectal malignant melanoma is a fairly uncommon but highly malignant disease. This disease is sometimes mistaken for such benign conditions as either a hemorrhoid or rectal polyp. We herein describe a case of early primary malignant melanoma of the anal canal. In this case, magnetic resonance (MR) imaging was found to be useful for diagnosing the melanotic melanoma. We especially emphasize the usefulness of a fat-saturation MR image in distinguishing melanotic melanoma from other rectal tumors.

Prognostic Nutritional Index Predicts Treatment Outcomes following Palliative Surgery for Colorectal Adenocarcinoma

Objectives: Palliative surgeries such as stoma creation and bypass are effective for relieving symptoms related to incurable abdominal malignancies; however, these methods are controversial in patients with severe metastatic disease or poor pre-surgical health. The aim of this study was to examine the clinical significance of the prognostic nutritional index (PNI) in evaluations for palliative surgery. Methods: We retrospectively analyzed data from 37 patients who underwent palliative surgery for histologically-proven colorectal adenocarcinoma from 2009 to 2015. We investigated both risk factors for postoperative complications and prognostic factors. We used a PNI cutoff value of 40, as defined by previous studies. Results: The reason for surgery was stenosis in 18 patients, obstruction in 12, fistula in 5, and bleeding in 2. Bypass was performed in 10 cases, ileostomy in 5, and colostomy in 22. Postoperative morbidity and mortality occurred in 9 and 2 patients, respectively. Median overall survival time was 8.9 months. Only low PNI correlated with postoperative complications at trend-level (p=0.07), and the 2 patients with mortality were classified as PNI-low. The presence of ascites (p=0.003) and PNI (p=0.02) were identified as independent prognostic factors. Conclusions: PNI could be used as an objective marker for deciding whether to proceed with palliative surgery, independent of the extent of metastatic disease.

Hemorrhagic Cholecystitis in a Patient on Maintenance Dialysis

The present paper describes a case of hemorrhagic cholecystitis in a patient on maintenance dialysis. The patient presented with right upper quadrant abdominal pain. Computed tomography revealed swelling of the gallbladder, high- and isodensity contents of the gallbladder, and high-density stone in the gallbladder neck. He was hospitalized for suspected acute cholecystitis. After hospitalization, his levels of total bilirubin, aspartate aminotransferase, and alanine aminotransferase increased. T2-weighted magnetic resonance imaging showed low-intensity contents expanded to include a wide area from the common bile duct to the cystic duct and gallbladder neck. Endoscopic retrograde cholangiopancreatography revealed clotting from the duodenal papilla. After cannulation of the bile duct, old blood and pus began to flow from the mammary papilla, and an endoscopic nasobiliary drainage tube was placed. After his liver function had improved, the patient underwent laparoscopic cholecystectomy. His sample revealed that the gallbladder was filled with blood clots and stones. His postoperative course was uneventful and he was discharged on day 19 after the procedure. Although hemorrhagic cholecystitis is rare, it should be considered as a differential diagnosis for patients on dialysis who have acute abdominal symptoms.

Significance of Mass Screening for Simultaneous Thyroid Disease and Breast Cancer

乳癌集団検診における甲状腺同時検診の意義について, 当教室の甲状腺疾患合併乳癌症例を併せて検討した。広島県集団検診では, 1985年より1991年の間にのべ約27万人の30歳以上の女性を対象として, 乳癌146人と甲状腺癌56人を発見した。その発見率はそれぞれ0.05%, 0.02%であった。発見乳癌および甲状腺症例の平均年齢はいずれも約50歳で, 年齢別発生率にも差を認めなかった。一方, 広島大学第2外科において1965年から1991年末までに加療した原発性女性乳癌506症例中, 確診の得られた甲状腺疾患合併症例は32例, 6.3%であった。そのうち特に甲状腺癌および甲状腺機能亢進症がそれぞれ10例と多く見られた。また甲状腺疾患合併群には比較的早期の乳癌が多く, 逆に進行例が少ない傾向が見られ, したがってその生存率も非合併群に比して比較的良好であった。甲状腺疾患と乳癌発生のリスクに関しては依然として未解明な点も多く, また今回, 甲状腺機能検査値からは明らかな相違を見出せなかった。しかし乳腺疾患と同様, 甲状腺疾患も女性に多い疾病の1つとしてまったく無関係とは言い難く, また重複癌例では乳癌家系や両側乳癌例, 被爆例が多いなど両者の発生要因として, 共通の内分泌あるいは遺伝・環境因子の関与が示唆された。したがって乳癌検診時に同時に甲状腺の視・触診を行うこと, また甲状腺疾患の既往などを十分聴取することの意義は大いにあるものと考えられた。