Biomedical subjects

Hitoshi Nagata

Publications and source records attributed to Hitoshi Nagata.

4 recordsLinked to original sources

PubMed2007

Rectal angiolipoma diagnosed after surgical resection: a case report.

Angiolipoma is a common benign tumor with a characteristic vascular component that usually occurs in subcutaneous tissue. Although lipomas are frequently encountered at colonoscopy as submucosal tumors, angiolipomas are rarely found in the gastrointestinal tract including the large intestine. Here we report a 77-year old Japanese man who underwent transanal resection of a tumor that was diagnosed tentatively as a leiomyoma. Histologically, the tumor consisted of mature fat cells and blood vessels. Immunohistochemically, the tumor cells were negative for c-kit and HMB-45, which are consistently expressed in tumors such as gastrointestinal stromal tumor and angiomyolipoma. The tumor was therefore diagnosed as an angiolipoma. This is thought to be the first case report of a surgically resected angiolipoma of the rectum.

Aged↗

PubMed2006

Total colectomy improves altered distribution of regulatory T cells in patients with ulcerative colitis.

BACKGROUND: It is now generally believed that regulatory T cells (Tregs) play an important role in peripheral tolerance, and a defect in Tregs is considered one of the most important factors in the induction of various kinds of autoimmune disease including ulcerative colitis (UC). Here, we examined the change in frequency of Tregs phenotype in five patients with UC whose condition had not been controllable by conventional conservative therapy and who were scheduled for total colectomy. AIMS: The aim of this study was to elucidate the role of Tregs in the pathogenesis of UC in a clinical setting. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from five patients with UC, and the change in frequency of Tregs was analyzed by flow cytometry before total colectomy and on postoperative days 1, 7, and 20. Tregs were defined as CD4+ CD25+ CD45RA+ T cells, and data (%) were expressed as frequency of Tregs/CD4+ T cells. Peripheral blood mononuclear cells (PBMCs) from healthy blood donors (n = 5) and from patients undergoing other types of major surgery (n = 5) were used as controls. RESULTS: Comparison with normal subjects showed that generation of Tregs was suppressed in UC patients before they underwent total colectomy (0.95 versus 5.06; P = 0.009). The frequency of Tregs increased shortly after total colectomy. The frequency at postoperative days 1, 7, and 20 was 3.81%, 8.13%, and 3.76%, respectively. There were significant differences in the change in frequency in the period before surgery and postoperative day 1, between postoperative days 1 and 7, and between days 7 and 20. CONCLUSIONS: Elimination of targeted antigens residing in the colorectal mucosa by total colectomy improved the suppressed distribution of Tregs in UC patients. The present study provides the first direct clinical evidence that Tregs play a pivotal role in the pathogenesis of UC.

Adult↗

PubMed2002

Mature dendritic cells make clusters with T cells in the invasive margin of colorectal carcinoma.

Dendritic cells (DCs) take up tumour-specific antigen and migrate to regional lymph nodes to generate anti-tumour immunity. Although DC infiltration within human tumour tissue has been reported, the subset distribution has not been fully investigated. This study used immunohistochemistry to investigate DC subset distribution in colorectal adenocarcinoma. DCs expressing CD83, which are considered to be mature DCs, were present mainly in the invasive margin of cancer stroma. CD83(+) DCs in the invasive margin formed clusters with lymphocytes, the majority of which were CD45RO(+) T cells. The number of CD4(+) T cells was greater than that of CD8(+) T cells in these DC-lymphocyte clusters. The elongated cytoplasmic processes of CD83(+) DCs engulfed CD4(+) T cells. DCs that express CD1a were located throughout tumour tissue. Although the number of CD1a(+) DCs was almost the same as that of CD83(+) DCs in the invasive margin of cancer stroma, CD1a(+) DCs were mostly scattered and rarely formed clusters with lymphocytes. DCs that expressed both CD1a and CD83 were rare. Moreover, about 20% of lymphocytes in DC-lymphocyte clusters were positive for Ki-67, and CD83(+) DCs were attached to Ki-67(+) cells. CD83(+) DCs were also present in T-cell areas that had a distinctive structure involving the presence of B-cell lymphoid follicles. These results suggest that in the invasive margin of the colorectal cancer stroma, mature CD83(+) DCs form clusters with T cells to promote T-cell activation for the generation of tumour-specific immunity.

Adenocarcinoma↗

PubMedDate not supplied

Total intraoperative enteroscopy using a colonoscope for detecting the bleeding point.

We report a case of bleeding in the small intestine of a 59-year-old man that was successfully diagnosed and treated by total intraoperative enteroscopy. The patient was admitted to our hospital because of gastrointestinal bleeding. Gastroscopy, colonoscopy and mesenteric arteriography could not identify the bleeding point. Technetium-99m-labeled red blood cell scintigraphy suggested bleeding from the small intestine but could not reveal the precise lesion. As the patient presented melena and went into a state of shock, we performed emergency laparotomy with total intraoperative enteroscopy using a colonoscope. A small ulceration was found at the jejunum, and subsequently partial resection of the jejunum was performed. The lesion was diagnosed histopathologically as angiodysplasia. The patient recovered uneventfully and was discharged on the 24th postoperative day. Bleeding in the small intestine is rare and difficult to diagnose but it sometimes induces a severe condition. Total intraoperative enteroscopy using a colonoscope is effective for detecting the bleeding point in the small intestine and can be performed at most centers without special fiberscopes and techniques.

Angiodysplasia↗