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Biomedical subjects

K Yamao

Publications and source records attributed to K Yamao.

At least 37 records · Page 2Linked to original sources
PubMed1997

Intraductal ultrasonography of the pancreas: development and clinical potential.

Intraductal ultrasound (IDUS) probes mounted with 30 MHz or 20 MHz transducers were evaluated in the diagnosis of 239 patients with pancreatic disease (including 48 cancers, 90 mucin-producing tumors, seven islet-cell tumors, two metastatic pancreatic tumors, seven serous cystadenomas, one pancreatic teratoma, three solid cystic tumors, 49 cases of chronic pancreatitis, 25 cases of focal pancreatitis, and seven cases of pancreatolithiasis). The probe was inserted via the papilla into the main pancreatic duct. In terms of resolution, IDUS at 20 MHz was able to image cystic lesions of less than 30 mm in diameter and solid lesions of less than 20 mm in diameter. With regard to vessels, IDUS was able to image the entire cross-section of the portal vein and other large veins. IDUS was useful in detecting carcinoma in situ and small tumors, in assessing the intraductal spread of the tumor and its pancreatic parenchymal invasion in mucin-producing tumors of the main duct, and in assessing the indications for surgery by revealing mural nodules in mucin-producing tumors of the ductal branches. IDUS was also useful in evaluating the feasibility of partial resection of the tumor in mucin-producing tumors of the ductal branches and pancreatic islet-cell tumors, in accurately locating multiple lesions in pancreatic islet-cell cancer, and in differentiating benign from malignant cases of localized stenosis of the main pancreatic duct related to pancreatic stenting. With IDUS, the site of pancreatic stones could be identified in order to assess the need for endoscopic treatments such as stenting of the pancreatic duct and the bile duct, and the use of pulsed-dye laser treatment under pancreatoscopy for pancreatic stones. Acute pancreatitis as a complication occurred in one of the 239 patients who underwent IDUS (0.4%). An awareness of the limitations and usefulness of IDUS in evaluating pancreatic diseases can contribute to the treatment of these conditions.

Aged↗
PubMed1997

[The studies of extracorporeal shock wave lithotripsy (ESWL) for pancreatic ductal stones].

30 patients with main pancreatic duct stones were treated by ESWL. In 18 of 22 patients who had not previously undergone endoscopic pancreatic sphincterotomy (EPST) or endoscopic sphincterotomy (EST), the stone fragments disappeared after ESWL. The fragments were removed endoscopically in the remaining 4 cases. Complete clearance was achieved in 8 cases with endoscopically unextractable stones by ESWL. After the ESWL procedure, absolute relief from pain was reported by in 19 of 22 patients with abdominal complaints. Serum amylase levels decreased significantly, and dilatation of the main pancreatic duct (MPD) was reduced. In the medium-term follow-up period, pancreatic exocrine function and endocrine function had a possibility to be preserved. One case of pancreatic cancer and one case of an intraductal papillary tumor of the pancreas were found, indicating that careful observation is necessary even after complete removal of pancreatic stones. In cases of Santorini duct dominant, multiple stones, or stricture of the MPD, ESWL should be combined with EPST and endoscopic stenting for preventing recurrence of acute pancreatitis and pancreatic stones. In conclusion, ESWL is the first choice of treatment for pancreatolithiasis and useful procedure and the limited complications.

Adult↗
PubMed1997

[A case of malignant lymphoma after renal transplantation].

A case of a primary brain malignant lymphoma after renal transplantation and immunosuppressive therapy is reported. A 41-year-old male patient had been treated with 125 mg/day of azathioprine and 10 mg/day of prednisolone after renal transplantation. He had also been suffering from various infectious diseases. Multiple brain tumors were found and diagnosed as having B-cell, diffuse large cell type malignant lymphoma. In spite of moderate response to irradiation, he died of pneumonia. The anti-Epstein Barr virus antibodies changed from a negative to a positive level after renal transplantation and they increased markedly after brain malignant lymphoma had been found. The number of T- and B-lymphocytes also decreased markedly at that time. So the Epstein-Barr virus was suspected to be the cause of the malignant lymphoma.

Adult↗
PubMed1996

Cellular differentiation and development of pyloric mucosal metaplasia in the human gall-bladder.

The development of pyloric mucosal metaplasia (PMM) with regard to cellular differentiation in the human gallbladder was studied by mucin staining (paradoxical concanavalin A (Con A), galactose oxidase-Schiff (GOS) and alcian blue (pH 2.5) PAS (AB-PAS) and immunohistochemistry (pepsinogen II (PgII) and SH-9, and proliferating cell nuclear antigen (PCNA). PMM was divided into three stages of development by three-dimensional (3D) computer graphic reconstruction analysis. In the early stage, a transitional zone of PCNA positive cells was observed between areas of SH-9 and/or GOS reactive cells and class III and/or Pg II positive cells in flat monolayered epithelium. In the middle stage, shallow pits became apparent as areas enlarged, with these becoming deeper in the advanced stage, whereby SH-9 and/or GOS reactive cells and class III and/or Pg II positive cells were observed at the upper and lower portion of the pits, respectively, with PCNA-positive cells forming a narrow zone between the two cell populations. Consequently, the structure of PMM gradually resembles that of the normal gastric pyloric mucosa.

Cell Differentiation↗
PubMed1996

[Intravascular ultrasound in determining the end point of percutaneous transluminal coronary angioplasty].

Intravascular ultrasound (IVUS) imaging was used to measure internal luminal area immediately after percutaneous transluminal coronary angioplasty (PTCA) in 83 patients (59 males, 24 females, mean age 63 +/- 12 years) with angina pectoris to determine the need for additional intervention. The effectiveness of these interventions to prevent restenosis was also studied. Thirty-five patients (42%) with insufficient dilatation revealed an internal luminal area less than 5 mm2 or luminal stenosis greater than 60% as evaluated by IVUS imaging following the procedure. The luminal area increased from 4.5 +/- 1.1 to 7.9 +/- 2.8 mm2 and the percentage luminal stenosis improved from 66 +/- 9% to 54 +/- 9% in patients who underwent further dilatation with a larger size balloon, longer dilatation time, directional coronary atherectomy, or stenting. The insufficient dilatation group exhibited hard plaque and calcification more frequently than in the other group (48 patients, 58%) in whom sufficient dilatation of the target lesion was achieved. The incidence of restenosis in the sufficient dilatation group was 25%, compared to 33% of the patients receiving additional treatment after IVUS imaging and 42% in the 192 patients who underwent PTCA without IVUS imaging. IVUS imaging is a useful method for evaluation of complex luminal morphology to decrease the incidence of restenosis and for determination of the end point and the extent of dilatation required.

Aged↗
PubMed1995

Endoscopic MRI: preliminary results of a new technique for visualization and staging of gastrointestinal tumors.

BACKGROUND AND STUDY AIMS: The principle of endoscopic ultrasonography--introducing the transducer of an external imaging method, such as ultrasonography, in combination with an endoscope into the gastrointestinal tract for higher-resolution imaging--has also been applied to magnetic resonance imaging (MRI). We report here on our preliminary experience with a new method of endoscopic MRI in the upper gastrointestinal tract. PATIENTS AND METHODS: Endoscopic MRI was performed in 32 patients with esophageal (n = 8) or gastric diseases (n = 24), mostly tumors (n = 26). Most cancers were at an advanced stage (T3/T4). A prototype MRI endoscope connected to a 1.5 tesla MRI scanner was used. The accuracy of endoscopic MRI in visualizing and staging gastrointestinal lesions was assessed. RESULTS: The normal gastrointestinal wall consisted of three layers, and tumors were visualized as having a low signal intensity on both T1- and T2-weighted sequences. Destruction of the wall layers was found to be characteristic of malignancy. Sufficient images were obtained in seven of eight esophageal cases (88%), but in only 14 of 24 gastric cases (58%). In patients in whom adequate visualization was achieved, the endoscopic MRI results of local and regional staging were consistent with surgical, histopathological, CT and/or EUS results in all six esophageal cancer cases and in 89% (T stage) and 56% (N stage) of the nine patients with gastric cancer. CONCLUSIONS: These preliminary results of endoscopic MRI are the first to be reported in the English literature. They show the potential of the method for local and regional staging, three-dimensional visualization of lesions being a potential advantage. Further technical improvements are expected.

Diagnosis, Differential↗
PubMed1995

[A study of the relationship between nocturnal intragastric pH and sleep stages of peptic ulcer].

We studied the correlation of the gastric acid secretion and the depth of sleep at night with no medication in 32 cases (19 gastric ulcer, 6 duodenal ulcer patients and 7 healthy controls). Using Memory PH: Monitor intragastric pH values were consecutively measured without antiulcer drugs. The depth of sleep were monitored continuously by recording without any sleeping drugs. In healthy controls, the pH values of awake phase was significantly lower than that of sleep stage 1, 4 and rapid eye movement (REM) phases. The pH values of REM phases were significantly high rather than that of sleep stage 1 and 2 phases. In patients with gastric ulcer, the pH values of awake phases were significantly lower than that of sleep stage 1 and REM phases. The pH values of REM phases were significantly high rather than that of the other sleep stages. On the other hand, in patients with duodenal ulcer, the obvious changes of the pH values were not seen with sleep stages. The pH values of healthy controls and gastric patients were changed with sleep stages. But the pH of duodenal ulcer patients were not changed obviously. Therefore, it is suggested that the dysfunction of autonomous nervous system was influenced the nocturnal intragastric pH in the patients with duodenal ulcer and played one of the important role in the occurrence of duodenal ulcer.

Adult↗
PubMed1994

A new method of real-time endoscopic measurement with an electric catheter.

A new method for measuring distances using electrically charged jets of water is described, and its precision examined. When combined with endoscopy, this method can be utilized to measured the lengths and areas of objects inside human body cavities. The apparatus used consists of a catheter with three metal needles at the tip, a personal computer, and a commercially available videoendoscopy system. To test the system, a regulated voltage was passed between the catheter tip and a wooden board, and two salt solutions of different concentrations were ejected at three different angles from the catheter to the board. The coordinates of the board were then computed from the amperages of the currents passing through the three jets of saline, and optical distortion was corrected using the computer. The length and area of an object could be measured rapidly by setting electrically the coordinates to match the endoscopic image. Lengths ranging from 10 to 50 mm were measured while varying the distance between catheter tip and board (10, 20, and 30 mm), as well as the angle formed by the catheter and the board (45, 60, and 90 degrees). The mean measurement error was less than 5.6% and accuracy was relatively independent of the angle between catheter and target.

Catheterization↗
PubMed1994

[Diagnostic strategy for malignancy and parenchymal invasion of so-called mucin-producing tumor of the pancreas].

This study investigated diagnostic indications of malignancy and parenchymal invasion of so-called mucin-producing tumor of the pancreas (MPT). We reviewed 40 patients with this type tumor. In diagnosis of malignancy, jaundice, mural nodule (EUS), displacement or compression of the portal vein (angiography), compression of the common bile duct (cholangiography) and Group IV-V in biopsy, Class III-V in brushing cytology were important. In diagnosis of parenchymal invasion, solid mass (US, EUS, CT), arterial encasement (angiography), defect in the common bile duct (cholangiography), stenosis or obstruction of the MPD (pancreatography) and elevation of serum CA19-9, CEA levels were important. By these findings, MPT diagnosed as benign can be observed without surgical treatment. On the other hand, MPT diagnosed as malignant must be treated by surgical resection, and operative procedure must be chosen according to whether the MPT was accompanied by parenchymal invasion or not.

Aged↗
PubMed1994

[A study of the influence of gastric acid on the extension of regenerative epithelium of gastric ulcer].

To study the influence of gastric acid on the extension of the regenerative epithelium, 26 patients (28 ulcers) of gastric ulcer were examined by the stereo video-endoscope being able to measure the length and 24-hours intragastric pH monitoring. Extending speeds of the regenerative epithelium were measured from the time the regenerative epithelium of the ulcer was observed till the last examination, but which was limited 8 weeks after the first observation of the regenerative epithelium. The relationship was not observed between the extending speeds and the stages (A2-H1, H1-H2, H2-S1) of the ulcer. For 21 ulcers followed up by the stereo video-endoscope from active stage, the extending speed of the regenerative epithelium and the pH 3 holding time in a day were significantly correlated (r = 0.51, p = 0.014), and the same relationship (r = 0.56, p = 0.008) were observed in the nighttime. It was confirmed that the gastric acid regulated strongly the extending speed of regenerative epithelium of gastric ulcer. The intragastric circumstance of the low acid secretion induced by the antacid-drugs was considered to accelerate the extension of regenerative gastric epithelium.

Adult↗
PubMed1993

A mucous histochemical and immunohistochemical study of precancerous and neoplastic lesions in the human pancreas.

A total of 44 cases of pancreatic lesions, including hyperplasia (six) cases, adenoma (mucinous cystadenomas [eight] and intraductal papillary adenoma [eight]), noninvasive intraductal papillary tumors (five), and invasive ductal carcinomas (17) were investigated possibly to establish a diagnostic marker. We examined the type of mucin secreted and immunoreactivities of antibodies to ras-p21 and c-erB-2 oncogene products. A significant decrease in the amount of mucin was found in invasive lesions, and this was associated with a shift toward production of neutral mucins and especially sialomucins. Hyperplasia and adenoma, in contrast, demonstrated a predominance of neutral mucin. The sulfated mucins found in normal epithelium were only very weakly stained in any of the tumor types. Thirty-three percent of non-invasive intraductal papillary tumors and 88% of invasive ductal adenocarcinomas demonstrated strong binding of the ras-p21 antibody. In contrast no obvious differences in expression of c-erbB-2 were evident between the groups. In conclusion, a combined mucin histochemical/immunohistochemical approach may facilitate accurate diagnosis.

Biomarkers, Tumor↗
PubMed1993

[The effects of synthetic protease inhibitor on motility of the human duodenal papilla].

We studied the effects of synthetic protease inhibitors on the motility of the human duodenal papilla. Before and after the intravenous administration of gabexate mesilate (GM) or nafamostat mesilate (NM), the duodenal papillary pressure was measured with a catheter tip pressure transducer under duodenoscopy. GM was administered to fourteen subjects at 1 and 3 mg/kg/h. The peak pressure and the basal pressure were dose-dependently reduced by GM, but the frequency did not change. The blood CCK concentration was not changed after GM administration. NM was administered to twelve subjects at 0.3 mg/kg/h. Both the papillary pressure and the frequency were not changed by NM. GM inhibited the papillary motility, but NM had no consistent effect on the papillary motility.

Adult↗