Search PubMed⌕ Search

Biomedical subjects

T Tomiyama

Publications and source records attributed to T Tomiyama.

At least 73 records · Page 4Linked to original sources
PubMed1997

Diagnosing extrahepatic bile duct stones using intraductal ultrasonography: a case series.

BACKGROUND AND STUDY AIMS: Intraductal ultrasonography (IDUS), a new ultrasonographic diagnostic procedure, was used to assess the presence of extrahepatic bile duct stones. PATIENTS AND METHODS: The IDUS apparatus consisted of a 6-French high-frequency (20 MHz) probe. Prior to clinical application, in-vitro studies were conducted in a water tank. Clinically, IDUS was successful in 31 patients after endoscopic retrograde cholangiography. Interpretations of IDUS images were evaluated in comparison with cholangiographic and fluoroscopic findings. RESULTS: Experimental testing demonstrated that stones or fragments were typically visualized as strong, high-echo images with acoustic shadowing; air bubbles were seen as fan-shaped high-echo areas or comet-shaped high-echo areas; and sludge was visualized as soft, easily changing, high-echo structures. Extrahepatic bile duct stones were visualized by IDUS in 30 of 31 patients (96.8%), while fluoroscopy and cholangiography identified 19 (61.3%) and 25 (80.6%), respectively. Accurate differentiation between stones and air bubbles was also possible. CONCLUSION: IDUS could be a useful modality in the diagnosis of extrahepatic bile duct stones.

Adult↗
PubMed1997

Limitations of intraductal ultrasonography in differentiating between bile duct cancer in stage T1 and stage T2: in-vitro and in-vivo studies.

BACKGROUND AND STUDY AIMS: We investigated whether intraductal ultrasonography (IDUS) could distinguish between stage T1 and T2 bile duct cancer. MATERIALS AND METHODS: In-vitro study. Resected bile duct specimens (n = 8) were immersed in a water tank and were pierced with straight pins to clarify the normal layer structure. Ultrasonosgraphic images (20MHz) of the positions of pin echoes were compared to the positions of pin holes as seen on histologic analysis of the specimens. In-vivo study. A thin-caliber high-frequency (6 Fr, 20 MHz) ultrasonic probe was inserted into the bile duct via a transhepatic route or a transpapillary route in 26 patients with bile duct cancer who underwent surgical resection. RESULTS: In-vitro study. The inner hypoechoic layer on the IDUS image corresponded not only to the fibromuscular layer but also to a part of fibrous layer of the perimuscular loose connective tissue on histologic analysis, especially in the cases with moderate to severe bile duct wall fibrosis. The outer hyperechoic layer corresponded to the subserosal fat tissue. In-vivo study. In four of six patients with tumor limited to the inside hypoechoic layer on IDUS images, the histologic findings showed tumor invasion to the fibrous layer of the perimuscular loose connective tissue. Due to this limitation, accuracy of IDUS in T-staging was only 20/26 (77 %). CONCLUSIONS: IDUS cannot reliably distinguish bile duct cancer in stage T1 from that in stage T2.

Adult↗
PubMed1997

Change of mechanical activity to contraction from the relaxation induced by the intracellular Ca2+ antagonist KT-362; effects of alkylation of side chain, and substitution of 2,3,4,5-tetrahydro-1,5-benzothiazepine derivatives.

KT-362 (5-[3-[2-(3,4-Dimethoxyphenyl)ethyl]aminopropionyl]-2,3,4, 5-tetrahydro-1,5-benzothiazepine fumarate) is an intracellular Ca2+ antagonist. The compound obtained by introducing methyl groups onto the nitrogen (R2) of the side chain of KT-362 showed vasoconstrictive activity. Therefore we synthesized various derivatives, and examined their activities. Substitution at position R2 of the side chain resulted in potent contractile activity, and the optimal alkyl length was two or three carbons. The potency was further increased by the introduction of a chloro group at the R1 position of 2,3,4,5-tetrahydro-1,5-benzothiazepines. One of the synthesized compounds, 8-chloro-5-¿N-ethyl-N-[2-(3,4-dimethoxyphenyl)ethyl]aminopropionyl¿-2,3,4, 5-tetrahydro-1,5-benzothiazepine fumarate (9b), showed an EC50 value of 3.47 x 10(-8) M for contraction of rabbit iliac artery. The action of compound 9b was antagonized competitively by an H1-histamine receptor antagonist, diphenhydramine, and the pA2 value was 7.82. The maximum constriction was inhibited by a Ca2+ entry blocker, nicardipine, but not by an alpha 1-adrenoreceptor antagonist, prazosin. In a Ca(2+)-free medium, tonic constriction induced by 9b disappeared, and only a phasic constriction was observed. Though this phasic constriction was inhibited by diphenhydramine, it was not inhibited by prazosin or nicardipine.

Adrenergic alpha-Antagonists↗
PubMed1997

Color Doppler ultrasonography in the diagnosis of portal vein invasion in patients with pancreatic cancer.

We retrospectively evaluated the diagnostic usefulness of color Doppler ultrasonography for detecting portal vein invasion in 21 patients with pancreatic cancer who underwent surgical exploration (14 resection, seven inspection). Real-time gray scale ultrasonography, color Doppler ultrasonography, computed tomography, and angiography were performed in all patients to evaluate portal vein invasion, and the images were compared with the histopathologic or surgical inspection findings. On comparison between gray scale ultrasonographic and color Doppler ultrasonographic images, the tumor-vessel relations were visualized more clearly on color Doppler ultrasonography than on gray scale ultrasonography in 14 (22.2%) of 63 vessels. The sensitivity of color Doppler ultrasonography, computed tomography, and angiography for diagnosing portal invasion was 73.7%, 73.7%, and 73.6%, and the specificity was 95.1%, 95.5%, and 90.9%, respectively; the overall accuracy was 84.1%, 88.9% and 85.7%, respectively. A mosaic signal pattern was observed in 12 vessels and showed an accuracy of 86.4% for diagnosing portal vein invasion. In conclusion, compared with gray scale ultrasonography, color Doppler ultrasonography provided improved images of the tumor and portal vein. Furthermore, the accuracy of color Doppler evaluation of portal vein invasion appears to be equal to that of computed tomography and angiography. Therefore, color Doppler ultrasonography may play an important role as an initial examination for evaluating portal vein invasion.

Adult↗
PubMed1996

Inhibition of amyloid beta protein aggregation and neurotoxicity by rifampicin. Its possible function as a hydroxyl radical scavenger.

Aggregation of physiologically produced soluble amyloid beta protein (Abeta) to insoluble, neurotoxic fibrils is a crucial step in the pathogenesis of Alzheimer's disease. Aggregation studies with synthetic Abeta1-40 peptide by the thioflavin T fluorescence assay and electron microscopy and cytotoxicity assays using rat pheochromocytoma PC12 cells showed that an antibiotic, rifampicin, and its derivatives, which possess a naphthohydroquinone or naphthoquinone structure, inhibited Abeta1-40 aggregation and neurotoxicity in a concentration-dependent manner. Hydroquinone, p-benzoquinone, and 1,4dihydroxynaphthalene, which represent partial structures of the aromatic chromophore of rifampicin derivatives, also inhibited A beta1 40 aggregation and neurotoxicity at comparable molar concentrations to rifampicin. Electron spin resonance spectrometric analysis revealed that the inhibitory activities of those agents correlated with their radical-scavenging ability on hydroxyl free radical, which was shown to be generated in cell-free incubation of Abeta1-40 peptide. These results suggest that at least one mechanism of rifampicin-mediated inhibition of A beta aggregation and neurotoxicity involves scavenging of free radicals and that rifampicin and/or appropriate hydroxyl radical scavengers may have therapeutic potential for Alzheimer's disease.

Alzheimer Disease↗
PubMed1996

Azulene derivatives as TXA2/PGH2 receptor antagonists--II. Synthesis and biological activity of 6-mono- and 6-dihydroxylated-isopropylazulenes.

In order to examine the correlation between activity and hydrophilicity of the side chain of sodium 3-[4-(4-chlorobenzenesulfonylamino)butyl]-6-isopropylazulene -1-sulfonate (KT2-962), a non-prostanoid TXA2/PGH2 receptor antagonist, one or two hydroxyl groups were introduced into the isopropyl moiety. A series of 6-hydroxylated-isopropylazulenes were synthesized by regioselective oxidation of 6-isopropylazulenes and their in vitro and in vivo antagonistic activities were studied. Both the primary and tertiary alcohols, monohydroxylated derivatives, exhibited potent biological activities comparable to unmodified 6-isopropylazulenes both in vitro and in vivo. In contrast, the activities of 1,2- and 1,3-diols of 6-substituted derivatives, markedly decreased, but recovered by O-isopropylidenation of the dihydroxyl moiety. These findings indicate that the moderate hydrophobicity of substituent at the 6-position of the azulene ring might be required for the activity and the size of the substituent at this position, not so rigid for keeping potent biological activity.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Assessment of the course and variations of the hepatic artery in bile duct cancer by intraductal ultrasonography.

BACKGROUND: We evaluated the course and variations of the hepatic artery in bile duct cancer using intraductal ultrasonography (IDUS). METHODS: IDUS was used to demonstrate the course of the hepatic artery preoperatively in 20 patients with extrahepatic bile duct cancer, and the image was compared with angiographic and surgical findings. RESULTS: IDUS was able to assess tumor invasion to the main branch of the right hepatic artery in all cases. However, it demonstrated only three cases in the left hepatic artery and four cases in the proper hepatic artery. When the hepatic artery indicated re-entry or bifurcation on the IDUS image, the proximal portion of re-entry or bifurcation was established as the proper hepatic artery, but when it showed neither re-entry nor bifurcation it was established as the right hepatic artery. CONCLUSIONS: IDUS demonstrated the main branch of the right hepatic artery in all cases, but was not useful for demonstration of the left and proper hepatic arteries. Correct assessment of re-entry and bifurcation was essential on IDUS images for making the distinction between the right hepatic artery and the proper hepatic artery.

Aged↗
PubMed1996

Assessment of pancreatic parenchymal invasion by bile duct cancer using intraductal ultrasonography.

BACKGROUND AND STUDY AIMS: This study was performed to clarify the diagnostic accuracy of intraductal ultrasonography (IDUS) in assessing pancreatic parenchymal invasion by bile duct cancer. PATIENTS AND METHODS: Preoperative assessment of pancreatic parenchymal invasion was carried out by IDUS via a percutaneous tract or a transpapillary route in 18 patients with extrahepatic bile duct cancer. Various probes with diameters of 1.4, 2.0, 2.4, 2.6 and 3.2 mm, and frequencies of 7.5, 15, 20 and 30 MHz were used. All patients underwent angiography and endoscopic ultrasonography (EUS). In the first six cases, IDUS and EUS images were analyzed retrospectively without knowledge of the operative outcome or the results of other imaging tests. In the subsequent 12 cases, the IDUS und EUS images were prospectively reviewed prior to surgery. The diagnostic accuracy of IDUS was compared with angiography and EUS by means of a histopathological examination of the resected specimens. RESULTS: The accuracy of IDUS, EUS, and angiography in assessing pancreatic parenchymal invasion was 100%, 78% and 61%, respectively. However, IDUS could not assess pancreatic capsular invasion. The accuracy of IDUS in assessing horizontal tumor extension to the intrapancreatic bile duct and to the hepatic side was 83% and 72%, respectively. CONCLUSIONS: IDUS proved useful for assessing the extension of cancer invasion to the pancreatic parenchyma, but not to the pancreatic capsule or mucosal surface.

Aged↗
PubMed1996

[New intracellular calcium antagonists. I. Synthesis and pharmacological evaluation of 2,3,4,5-tetrahydro-1,5-benzothiazepine analogs].

A series of 2,3,4,5-tetrahydro-1,5-benzothiazepine and related compounds were prepared, and the intracellular Ca2+ inhibitory effects were examined using methoxamine- or caffeine-induced contraction of isolated rabbit arteries. Structure-activity relationship studies of these compounds are discussed and the results suggest that novel 5-[3-[2-(3,4-dimethoxyphenyl)ethyl]aminopropionyl]-2,3,4,5- tetrahydro-1,5-benzothiazepine fumarate (20d) showed the most potent inhibitory action on the intracellular Ca2+ release.

Animals↗
PubMed1996

Utility of endoscopic ultrasonography with color Doppler function for the diagnosis of islet cell tumor.

OBJECTIVE: To evaluate the efficacy of endoscopic ultrasonography with color Doppler function for the diagnosis of islet cell tumor. METHODS: Endoscopic ultrasonography was compared with other modalities such as ultrasonography, computed tomography, and angiography in the evaluation of seven patients with islet cell tumor and 28 patients with duct cell cancer. RESULTS: In cases of islet cell tumor, the tumor detection rates by ultrasonography and endoscopic ultrasonography were 86% and 100%, respectively. Color signals were detected in 14% and 100% of the cases of islet cell tumor by ultrasonography and endoscopic ultrasonography, respectively. The pattern of color signals obtained was rich and abundant, showing pulsatile and/or continuous wave patterns. Angiography and computed tomography showed hypervascularity. However, in cases of duct cell cancer, the tumor detection rates by ultrasonography and endoscopic ultrasonography were 96% and 100%, respectively, whereas color signals were detected in 78% with both ultrasonography and endoscopic ultrasonography. The image of blood flow, which was connected to surrounding vessels, showed a linear pattern and few blood flow signals. In these cases, angiography and computed tomography demonstrated encasement of the artery or portal vein without hypervascularity. CONCLUSIONS: Endoscopic ultrasonography was usefull for the localization and differential diagnosis of islet cell tumor because of its excellent ability to visualize small lesions and tumor vascularity simultaneously.

Adenoma, Islet Cell↗
PubMed1996

Assessment of arterial invasion in pancreatic cancer using color Doppler ultrasonography.

OBJECTIVE: We report the first study on the value of color Doppler ultrasonography (CDUS) in assessing arterial invasion of pancreatic cancer. METHODS: The relationships between tumors and surrounding major splanchnic arteries (celiac, superior mesenteric, common hepatic, splenic, and gastroduodenal arteries) were preoperatively evaluated with CDUS in 33 consecutive patients with pancreatic cancer. When a tumor partially or completely surrounded the artery, the invasion was diagnosed as positive. Imaging results were then compared with angiographic, surgical, and histopathological findings. RESULTS: In 22 nonsurgical patients, the correspondence rate of CDUS with angiography for the presence of invasion, absence of invasion, and overall was 78%, 95%, and 88%, respectively. In 11 surgical patients, a sensitivity of 60%, specificity of 93%, and accuracy of 87% for detection of arterial invasion were obtained in comparing CDUS with surgical and histopathological findings. There was no significant difference between the accuracy of CDUS and that of CT, or that of angiography. However, the accuracy of CDUS was higher than that of CT (72%) and equal to that of angiography (91%). CONCLUSION: Color Doppler ultrasonography is useful for detecting arterial invasion in pancreatic cancer. It may make angiography unnecessary, especially with advanced tumors, if thorough evaluation for the large artery invasion is performed initially.

Adult↗
PubMed1996

Diagnosis of gallbladder carcinoma with color Doppler ultrasonography.

A 65-yr-old woman was referred to our department for evaluation of a gallbladder lesion detected at another institution, where she was diagnosed with chronic cholecystitis. Conventional ultrasonography revealed that the gallbladder lumen was filled with debris-like components, and the gallbladder wall was mildly thickened. Color Doppler ultrasonography revealed color signals in both the lesion and the gallbladder wall. These signals showed a high-speed pulsatile wave, and one of the visualized signals revealed a high-resistance index (1.0) on fast Fourier transform analysis. These findings were highly suggestive of malignancy. Surgery was performed, and histological examination of the resected specimen revealed carcinoma of the gallbladder. We conclude that color Doppler ultrasonography can be useful in the diagnosis of tumefactive gallbladder lesions.

Adenocarcinoma↗
PubMed1996

[Progress and clinical usefulness of color Doppler method in diagnosing abdominal diseases].

We report the clinical usefulness of extracorporeal color Doppler ultrasonography (CDUS), color Doppler endoscopic ultrasonography (CDEUS), and recent progress in diagnosing abdominal diseases by the color Doppler method. CDUS has the advantage of being able to be performed repeatedly and noninvasively, it is thought to be useful for the evaluation of tumor vascularity and diagnosis of vascular tumor invasion and analysis of hemodynamics in abnormal vessels found in several abdominal diseases. CDEUS, which is performed under endoscopic ultrasonography (EUS), can evaluate the hemodynamics more minutely and visualize small vessels more clearly than conventional CDUS. Recent progress in the color Doppler method, such as US color angiography and the use of contrast agents is expected to lead to a higher resolution of visualization and easier detection of abdominal vessels.

Abdomen↗
PubMed1995

Apoptosis of cultured mouse luteal cells induced by tumor necrosis factor-alpha and interferon-gamma.

BACKGROUND: Macrophages and T lymphocytes have been identified in the regressing corpus luteum, and they are thought to participate in structural luteolysis (destruction and removal of luteal cells). Since these cells produce cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), we investigated the effects of these two cytokines on death of luteal cells in vitro. METHODS: Mouse luteal cells were cultured in serum-free medium with TNF-alpha at 0, 500, 1,000, 3,000, or 5,000 U/ml in the presence or absence of IFN-gamma at 1,000 U/ml for 3 or 6 days. Then, for estimation of the actions of these cytokines on induction of luteal cell death, we determined the number of viable cells, the percentage of fragmented DNA in total DNA extracted from cultured cells, and the percentage of cells with fragmented DNA in their nuclei by the trypan blue exclusion test, the sensitive micromethod for DNA assay, and the in situ DNA 3' end labeling method, respectively. DNA fragmentation was also analysed by agarose gel electrophoresis, and cultured cells were examined by electron microscopy. RESULTS: On day 3 of culture, IFN-gamma alone at 1,000 U/ml or TNF-alpha alone at 500-5,000 U/ml did not decrease the number of viable cells, but a combination of IFN-gamma (1,000 U/ml) and TNF-alpha (5,000 U/ml) did. On day 6, IFN-gamma alone at 1,000 U/ml or TNF-alpha alone at 500, 1,000 and 3,000 U/ml did not decrease the number of viable cells, whereas TNF-alpha alone at 5,000 U/ml did, and combinations of IFN-gamma and TNF-alpha at 1,000, 3,000, and 5,000 U/ml decreased the number of viable cells in proportion to the concentration of TNF-alpha. On days 3-6 of culture, combinations of IFN-gamma and TNF-alpha that decreased the number of viable cells also increased the percentages of fragmented DNA in total DNA of cultured luteal cells and the percentages of luteal cells with fragmented DNA in their nuclei. Agarose gel electrophoresis of fragmented DNA showed a ladder-like pattern, and electron microscopic examination showed luteal cells with the characteristics of apoptosis. CONCLUSIONS: The presence of IFN-gamma modulates the ability of TNF-alpha to induce a reduction in the number of viable cells, although TNF-alpha alone at high concentrations can induce a reduction in the number of viable cells.

Animals↗
PubMed1995

Assessment of portal vein invasion by bile duct cancer using intraductal ultrasonography.

BACKGROUND AND STUDY AIMS: We recently reported on the contribution of intraductal ultrasonography (IDUS) to the regional staging of bile duct cancer, and we present here the first detailed study of the value of IDUS in assessing the portal vein invasion by bile duct cancer. PATIENTS AND METHODS: Preoperative assessment of portal vein invasion was performed by IDUS via a percutaneous tract or via transpapillary route in 18 patients with extrahepatic bile duct cancer. Various probes, with diameters of 1.4, 2.0, 2.4, 2.6, and 3.2 mm, and frequencies of 7.5, 15, 20, and 30 MHz, were used. All patients additionally underwent endoscopic ultrasonography (EUS) and angiography. In the first six cases, the IDUS and EUS images were analyzed retrospectively without the knowledge of operative results or the other imaging tests. In the remaining 12 cases, IDUS and EUS images were prospectively reviewed prior to surgery, without knowledge of the angiographic findings. The gold standard for the results of IDUS, EUS and angiography was the histopathological findings in 17 resected tumors, and the intraoperative findings in one patient who did not undergo resective surgery. RESULTS: IDUS was able to demonstrate the portal vein in all cases. Its accuracy in diagnosing portal vein invasion was 100% for all locations. EUS was useful in assessing portal vein invasion at the middle and distal bile duct (the accuracy was 91%), but was not useful in assessing invasion at the proximal bile duct (the accuracy was 57%). CONCLUSIONS: IDUS proved useful for assessing the extension of cancer invasion into the portal vein, even in proximal bile duct tumors.

Aged↗
PubMed1995

Assessment of hepatic artery invasion by bile duct cancer using intraductal ultrasonography.

BACKGROUND AND STUDY AIMS: This study was performed to clarify the diagnostic accuracy of intraductal ultrasonography (IDUS) in assessing hepatic artery invasion by bile duct cancer. PATIENTS AND METHODS: Preoperative assessment of hepatic artery invasion was performed by IDUS via a percutaneous tract or the transpapillary route in a total of 22 patients with extrahepatic bile duct cancer. The probes used had a diameter of 1.4, 2.0, 2.4, 2.6, and 3.2 mm, and frequencies of 7.5, 15, 20, and 30 MHz. In the first six cases, IDUS images were analyzed retrospectively with no knowledge of the operative results or of the other imaging tests. In the following 16 cases, the IDUS images were prospectively reviewed prior to surgery without knowledge of the angiographic findings. The diagnostic accuracy of IDUS was compared with angiography in all cases, with the histopathological results in 20 resected cases, and with the intraoperative findings in two cases with only surgical exploration. RESULTS: IDUS was able to demonstrate the right hepatic artery in all cases, and its accuracy in diagnosing right hepatic invasion was 100%. However, IDUS was able to visualize the proper hepatic artery in only four cases (18%), and the left hepatic artery in only three cases (14%), respectively. IDUS could not visualize the area outside of the hepatoduodenal ligament, because of its low penetration depth. CONCLUSIONS: IDUS proved useful for assessing the extension of bile duct cancer invasion into the right hepatic artery. However, IDUS did not sufficiently demonstrate the proper hepatic artery and the left hepatic artery for diagnosing vascular involvement.

Aged↗