Biomedical subjects

N Sata

Publications and source records attributed to N Sata.

23 records · Page 2Linked to original sources

PubMedDate not supplied

A new 3-D diagnosis strategy for duodenal malignant lesions using multidetector row CT, CT virtual duodenoscopy, duodenography, and 3-D multicholangiography.

Recent advances in multidetector row computed tomography (MD-CT) technology provide new opportunities for clinical diagnoses of various diseases. Here we assessed CT virtual duodenoscopy, duodenography, and three-dimensional (3D) multicholangiography created by MD-CT for clinical diagnosis of duodenal malignant lesions. The study involved seven cases of periduodenal carcinoma (four ampullary carcinomas, two duodenal carcinomas, one pancreatic carcinoma). Biliary contrast medium was administered intravenously, followed by intravenous administration of an anticholinergic agent and oral administration of effervescent granules for expanding the upper gastrointestinal tract. Following intravenous administration of a nonionic contrast medium, an upper abdominal MD-CT scan was performed in the left lateral position. Scan data were processed on a workstation to create CT virtual duodenoscopy, duodenography, 3D multicholangiography, and various postprocessing images, which were then evaluated for their effectiveness as preoperative diagnostic tools. Carcinoma location and extent were clearly demonstrated as defects or colored low-density areas in 3-D multicholangiography images and as protruding lesions in virtual duodenography and duodenoscopy images. These findings were confirmed using multiplanar or curved planar reformation images. In conclusion, CT virtual duodenoscopy, doudenography, 3-D multicholangiography, and various images created by MD-CT alone provided necessary and adequate preoperative diagnostic information.

Aged↗

PubMedDate not supplied

Mesoscopic fast ion conduction in nanometre-scale planar heterostructures.

Ion conduction is of prime importance for solid-state reactions in ionic systems, and for devices such as high-temperature batteries and fuel cells, chemical filters and sensors. Ionic conductivity in solid electrolytes can be improved by dissolving appropriate impurities into the structure or by introducing interfaces that cause the redistribution of ions in the space-charge regions. Heterojunctions in two-phase systems should be particularly efficient at improving ionic conduction, and a qualitatively different conductivity behaviour is expected when interface spacing is comparable to or smaller than the width of the space-charge regions in comparatively large crystals. Here we report the preparation, by molecular-beam epitaxy, of defined heterolayered films composed of CaF2 and BaF2 that exhibit ionic conductivity (parallel to the interfaces) increasing proportionally with interface density--for interfacial spacing greater than 50 nanometres. The results are in excellent agreement with semi-infinite space-charge calculations, assuming a redistribution of fluoride ions at the interfaces. If the spacing is reduced further, the boundary zones overlap and the predicted mesoscopic size effect is observed. At this point, the single layers lose their individuality and an artificial ionically conducting material with anomalous transport properties is generated. Our results should lead to fundamental insight into ionic contact processes and to tailored ionic conductors of potential relevance for medium-temperature applications.

Journal Article↗

PubMedDate not supplied

The role of calcium in pancreatitis.

BACKGROUND/AIMS: A large, sustained increase in acinar [Ca2+]i may play a key role in the pathogenesis of acute pancreatitis. Many mechanisms which lead to cell damage in vitro and pancreatitis in vivo, such as free radicals or supraphysiological cerulein concentrations, cause a rapid increase in [Ca2+]i in pancreatic acinar cells. Little is known about why [Ca2+]i increases in some instances stimulate secretion and in other instances initiate cell death. So far, [Ca2+]i increases were thought to represent physiological signals when they occurred as oscillations at the single cell level. METHODOLOGY: This paper reviews recent literature and our own original research about the role of calcium in the function of pancreatic acinar cells and the development of pancreatitis. RESULTS: Recent studies showed that exposure of acinar cells to free radicals not only caused a bulk increase in [Ca2+]i but also resulted in calcium oscillations which had a lower frequency than, but similar amplitude to oscillations occurring after physiological stimuli. The absolute increase in [Ca2+]i did not definitely determine the cellular response. Instead, the duration of [Ca2+]i increase may have been more important. In contrast to previous belief of a direct relationship between [Ca2+]i oscillations and exocytosis, recent results show that radicals can induce [Ca2+]i oscillations which do not exert exocytosis but inhibit the secretory response to physiological stimuli. Further experiments showed that the [Ca2+]i release caused by radicals originates from thapsigargin-insensitive, ryanodine-sensitive stores. CONCLUSIONS: The origin and duration of [Ca2+]i increases rather than their extent or oscillatory nature, determine whether the cell will secrete or die. An abnormal [Ca2+]i increase can trigger trypsin activation, acinar cell damage and acute pancreatitis. This hypothesis is supported by studies which show that calcium chelators inhibit radical-induced trypsin activation as well as cell necrosis and apoptosis. Thus, an inhibition of pathological [Ca2+]i release may have a therapeutic potential.

Acute Disease↗

PubMedDate not supplied

Long-term survival after surgical resection for pancreatic cancer.

BACKGROUND/AIMS: Pancreatic cancer remains one of the most formidable tumors defying early detection and effective treatment. Long-term survivors, however, do exist after resection. We investigated the clinicopathologic features of patients with pancreatic cancer who survived more than 5 years to draw out some suggestions concerning the indication of surgical treatment. METHODOLOGY: We studied the clinicopathologic features of 13 patients with pancreatic cancer who survived more than 5 years after resection. We reviewed their clinical records to investigate preoperative symptoms, serum tumor markers, operative findings, postoperative adjuvant therapy, and modes of recurrence and survival periods. Information on the location, size, histology and spread of the primary tumors were mainly obtained from pathology reports. RESULTS: Histologic types of the long survivors included ductal adenocarcinoma of common type in 4 patients, mucinous noncystic adenocarcinoma in 2, intraductal papillary-mucinous carcinoma (invasive) in 4, undifferentiated carcinoma in 1, endocrine tumor (islet cell carcinoma) in 1 and acinar cell carcinoma in 1. All 4 cases of ductal adenocarcinoma of the common type showed a moderate invasion either to the retroperitoneum, the portal vein or the duodenum. Two patients with mucinous noncystic carcinoma attained a long survival despite extensive invasion of the pancreatic stroma, although one died of peritoneal carcinomatosis. Two of 4 patients with intraductal papillary-mucinous cancer (invasive) died of peritoneal dissemination 6 and 11 years after resection, respectively. Three patients with cancer of other special histologic types, i.e., undifferentiated, well-differentiated endocrine carcinoma and acinar cell carcinoma, showed invasion of the portal vein and splenic artery, involvement of the retroperitoneum and a metastatic tumor in the liver, respectively. CONCLUSIONS: Whereas special histologic types including ductal variants tended to predispose to long-term survival, ductal adenocarcinoma of the common type had some chance of long survival even with invasion of the surrounding tissues.

Adenocarcinoma, Mucinous↗

PubMedDate not supplied

A case of gallbladder cancer with para-aortic lymph node metastasis who has survived more than seven years after the primary extended radical operation.

A 55-year-old man with gallbladder cancer was surgically treated in our hospital in July 1988. The tumor was about 8 cm in diameter, replaced the entire gallbladder, and invaded the liver and the hepatoduodenal ligament. In addition, extensive tumor metastasis to lymph nodes, including those of the para-aortic area was noted (Stage IV). Extended cholecystectomy with resection of the liver and lymph node dissection were performed. Although all of the macroscopic tumors were removed surgically, we believed that the tumor would recur in the near future, since all of the excised para-aortic lymph nodes were involved by carcinoma histologically. After surgery, the patient received 5'-deoxy-5-fluorouridine (5'-DFUR) orally at a dose of 600 mg per day. In December 1993, more than 5 years after the primary operation, cancer recurrence in para-aortic lymph nodes was demonstrated by computed tomography (CT). In June 1994, the patient underwent a second operation for treatment of recurrent tumor. The lymph nodes firmly adhered to both the aorta and left renal vein, and could not be removed. Since August 1994, he has received external radiation therapy, and there has been no further enlargement of the nodes. This is the first reported case of gallbladder cancer with para-aortic lymph node metastasis who survived more than seven years after the primary extended radical operation with cholecystectomy, resection of the liver, and extended lymph node dissection.

Adenocarcinoma↗