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M Imamura

Publications and source records attributed to M Imamura.

At least 19 recordsLinked to original sources
PubMed1992

A novel nonmuscle alpha-actinin. Purification and characterization of chicken lung alpha-actinin.

Two distinct alpha-actinin-like proteins were detected in chicken lung extract by immunoblot analysis with monoclonal antibodies against alpha-actinin. The mobilities of these proteins on SDS-polyacrylamide gel electrophoresis are very close (approximately 100 kDa). On SDS-polyacrylamide gel electrophoresis in the presence of 6 M urea, however, one of the proteins migrates at 115 kDa and is clearly separated from the other protein (105 kDa). The 115-kDa protein was purified and shown to have at least three unique amino acid sequences which were not detected in other kinds of alpha-actinins: one locates at the extreme NH2-terminal region, and the others locate at the COOH-terminal half region. Immunoblot and proteolytic cleavage analyses revealed that the 115-kDa protein has structural divergence at the COOH-terminal region that includes Ca(2+)-binding EF-hand motifs. Falling-ball viscometric studies showed that although the 115-kDa protein-induced gelation of F-actin is sensitive to Ca2+, the gelation activity of the 115-kDa protein is much higher than that of Ca(2+)-insensitive gizzard alpha-actinin regardless of Ca2+. This indicates that the 115-kDa protein is distinct from other nonmuscle alpha-actinins by its Ca2+ sensitivity.

Actinin↗
PubMed1992

Complete primary structure and tissue expression of chicken pectoralis M-protein.

M-Protein (165 kDa) is a structural constituent of myofibrillar M-band in striated muscle. We generated a monoclonal antibody which recognized a 165-kDa protein from chicken pectoralis muscle in immunoblot analysis and stained the M-band under immunofluorescence microscopy. By screening a lambda gt11 cDNA library from chicken embryonic pectoralis muscle with this antibody, we isolated a cDNA clone encoding the M-protein. Northern blot analysis showed that M-protein mRNA is expressed in pectoralis and cardiac muscle but not in gizzard smooth muscle or non-muscle tissues. Moreover, the anterior latissimus dorsi muscle, which consists almost exclusively of slow fiber types, contains no detectable levels of the mRNA. The full-length cDNA sequence predicted a 1,450-amino acid polypeptide with a calculated molecular weight of 163 x 10(3). The encoded protein contains several copies of two different repetitive motifs: five copies of fibronectin type III repeats are in the middle part of the predicted molecule, and two and four copies of the immunoglobulin C2-type repeats are located toward the NH2-terminal and COOH-terminal regions, respectively. This indicates that M-protein, along with other thick filament-associated proteins such as C-protein, twichin, and titin, belongs to the superfamily of cytoskeletal proteins with immunoglobulin/fibronectin repeats.

Amino Acid Sequence↗
PubMed1992

Characterization of 21 newly established esophageal cancer cell lines.

Twenty-one esophageal cancer cell lines (KYSE series) have been established from the resected specimens of patients with esophageal cancer. Three lines, KYSE-30, KYSE-50, and KYSE-70, were derived from the implanted tumor of nude mice (initial passage); others were derived from resected specimens. Each cell line was morphologically distinct. Detailed cytogenetic analysis indicated that each cell line was karyotypically unique, and DNA fingerprint analysis showed no cross-contamination among cells. Doubling time ranged from 13.7 to 75.5 hours, and modal chromosome numbers ranged from 46 to 120. Most cell lines grew in monolayer, but two cell lines (KYSE-50 and KYSE-360) grew as floating cell aggregates. No correlation was demonstrated between the establishment of cell lines and cell differentiation. These cell lines are the first reported to be homogeneous and individually unique and may provide a useful model for the study of human esophageal cancer.

Animals↗
PubMed1992

Evaluation of microcirculation in the tumor-bearing liver of rabbits by laser-Doppler flowmetry.

Hemodynamic changes in normal liver tissue and in intrahepatic tumors (Vx2 carcinoma) after occlusion of the hepatic arterial branch or the portal branch (ex. 1), and with intrahepatic arterial infusion of vasoactive agents (ex. 2) were studied in rabbits by a laser-Doppler flowmeter. Ex. 1: After occlusion of the hepatic arterial branch to the main lobe, laser-Doppler flow (LDF) in main lobe normal tissue decreased by 11 +/- 11% in the control group, 37 +/- 37% in group Ia (tumors were 10-20 mm in diameter) and 49 +/- 37% in group Ib (tumors were 25-50 mm), so it seemed that the proportion of portal blood flow in the normal tissue microcirculation decreased with tumor growth. The tumor LDF decreased by 88 +/- 13%. After occlusion of the portal branch, the normal tissue LDF in the main lobe decreased and then recovered slightly (most evident in the control group and least in group Ib). This recovery was probably due to the hepatic arterial buffer response. The tumor LDF decreased by 36 +/- 10% in group Ia and 11 +/- 17% in group Ib. There was no difference between group I (tumors were implanted directly) and group II (tumors were implanted via portal vein). Ex. 2: Adenosine and prostaglandin E1 increased blood flow in the normal tissue and decreased the tumor blood flow, while angiotensin II had the opposite effect. Vasoactive agents can be used to selectively increase or decrease tumor blood flow and are available as adjuvants for the treatment of liver tumors. Adenosine may enhance the selective tumor heating in local hyperthermia.

Animals↗
PubMed1992

Usefulness of preoperative low dose cisplatin treatment for advanced esophageal cancer.

In order to decrease the perioperative complications by preoperative cisplatin chemotherapy, the preoperative single administration of cisplatin (30 mg/m2) was performed weekly from one to six times in 36 consecutive patients with esophageal cancer classified as higher than Stage II. The survival curve of 17 patients in Stage III was significantly better (P < 0.05) than that of patients who had been treated without preoperative cisplatin treatment. In 3 of the 12 patients who had locally invasive cancer, either the main tumors or the metastatic lymph nodes, which had invaded the trachea or the left main bronchus, sufficiently receded, so that a curative esophagectomy became possible; 2 of them have survived over 33 months while 1 died of pneumonia 33 months after surgery. The number of perioperative complications was minimal, and thus, we consider that the postoperative use of cisplatin and fluorouracil is indicated in patients in whom a histological response is noted in the resected specimens.

Aged↗
PubMed1992

Hemodynamic changes after resection of thoracic duct for en bloc resection of esophageal cancer.

An en bloc resection of esophageal cancer is one of the most radical forms of esophagectomy, and includes the resection of the thoracic duct, but a relatively high hospital mortality rate has been reported. There is very little knowledge on the pathophysiological changes after resection of the thoracic duct. We examined 24 patients who underwent en bloc resection. Some patients developed severe tachycardia or shock postoperatively which subsided after a massive infusion of plasma. Analysis of the fluid balance revealed that much more fluid was necessary during surgery and the postoperative 24 h than in patients treated by a standard esophagectomy. Postoperative lymphangiography or CT revealed abnormal collateral lymphatics around the kidneys or in the pelvic cavity. This suggests the development of the lymphaticovenous shunts, which differed depending on the anatomy of each patient. One patient with chronic hepatitis developed uncontrollable ascites. These are important findings which can hopefully reduce the high rate of hospital death after this operation.

Aged↗
PubMed1992

Comparative sequence analysis and expression of bovine PrP gene in mouse L-929 cells.

A cDNA clone encoding bovine scrapie-associated fibril protein, PrP, from a bovine brain cDNA library and six amplified genomic DNA clones of bovine PrP were characterized. These clones possessed specific characteristics observed in other animal PrP genes. However, the bovine PrP was divided into two types by the number of repeats. One possessed four octapeptide repetitive sequences, like other animal PrP genes, and consisted of 256 amino acids; the other had five such repetitive sequences and 264 amino acids. The amino acid sequence of the former bovine PrP agreed with that of sheep PrP up to the 165th amino acid from the N-terminus. Bovine PrP cDNA introduced into mouse L-929 cells were stably expressed. The expression level of recombinant bovine PrP in the cells judged by immunofluorescence was higher than that of authentic mouse PrP. The recombinant PrP comigrated with authentic bovine PrP in SDS-polyacrylamide gel electrophoresis, suggesting that the recombinant product was fully glycosylated in L-929 cells. Distinct bundles of the intermediate filaments were frequently seen at the perinuclear region of the cells.

Amino Acid Sequence↗
PubMed1992

Altered expression of E-cadherin in gastric cancer tissues and carcinomatous fluid.

Expression of E-cadherin in 21 patients with various histological types of gastric carcinomas was studied by immunoperoxidase staining. Intercellular boundaries of almost all cancer cells in well and moderately differentiated adenocarcinomas stained as deeply for E-cadherin as normal gastric mucosa. However, singly infiltrating cells of those histological types were poorly stained. In poorly differentiated adenocarcinomas, cancer cells forming clusters stained lightly and those infiltrating singly stained even less. In signet ring cell carcinomas, hardly any staining was observed. In each histological type, the staining patterns and intensity at different layers of the gastric wall, were essentially the same. Cancer cells from carcinomatous ascites of gastric adenocarcinomas and pancreatic adenocarcinomas, and those from pleural effusion of lung adenocarcinomas were also studied by immunofluorescence staining. Of 11 specimens, ten were negative and only one from a lung adenocarcinomas was positively stained. By phase-contrast microscopic observations, none of these cancer cells including those from the lung adenocarcinomas, formed obvious cell-cell contacts. Cell aggregation assays confirmed the above results. The molecular weight of E-cadherin of cancer cells of lung adenocarcinomas was less than intact E-cadherin as revealed by Western blot analysis. These results suggest that depressed expression and/or impaired function of E-cadherin in cancer cells, facilitates their liberation from primary sites to infiltrate freely into tissue or fluid.

Adenocarcinoma↗
PubMed1992

Differences in left ventricular structural and functional changes between pheochromocytoma and essential hypertension. Role of elevated circulating catecholamines.

Experimental findings suggest that catecholamines increase protein synthesis and play a role in cardiac hypertrophy. We hypothesize that elevated circulating plasma catecholamines in pheochromocytoma influence cardiac structural and functional remodeling. We compared 15 patients with surgically proven pheochromocytoma and 15 with untreated essential hypertension; we matched the patients for age, sex, body surface area, and blood pressure (BP) levels. Left ventricular hypertrophy (LVH) was identified by M-mode echocardiography in six patients with pheochromocytoma and in four with essential hypertension. Among both groups there were no differences in cardiac structure, no correlation between left ventricular mass and BP, no significant differences in mitral E-F slope, no correlation between either plasma norepinephrine or plasma epinephrine levels, and no differences in the left ventricular structural indices measured. In the pheochromocytoma group, left ventricular end systolic stress and end systolic diameter were significantly lower and left ventricular percent fractional shortening was higher. Plasma norepinephrine levels were higher in the pheochromocytoma group, but did not differ among patients of that group with and without LVH. We conclude that in both pheochromocytoma and essential hypertension, only a subset of patients develop evidence of LVH, and that in pheochromocytoma, the elevation of circulating plasma catecholamines is not necessarily associated with LVH. These results indicate that factors other than catecholamines and BP determine the development of LVH in pheochromocytoma.

Adolescent↗
PubMed1992

Establishment of a novel granulocytic sarcoma cell line which can adhere to dermal fibroblasts from a patient with granulocytic sarcoma in dermal tissues and myelofibrosis.

A novel human myeloid cell line, designated HSM-1, has been established from the pleural effusion of a patient with granulocytic sarcoma (GS) who had been followed as having primary myelofibrosis for 10 years. When he was diagnosed as having granulocytic sarcoma in dermal tissues, no evidence of malignant transformation into leukaemia was found in both the peripheral blood and bone marrow. The established cell line was positive for myeloperoxidase, Sudan black B, Naphthol AS-D chloroacetate esterase. Surface marker analysis revealed that HSM-1 expressed CD4, CD13, CD11a, CD11b, Leu8, CD49b, CD49d, CD49e, CD29 and HLA-DR. To clarify why the unusual myeloid tumours developed in non-haematopoietic tissues, we examined the capability of HSM-1 to bind to skin fibroblast layers. The HSM-1 cells were found to bind to both bone marrow stromal layers and skin fibroblast layers. Among the other myeloid cell lines tested, none was found to bind to skin fibroblast layers. These findings suggest that the GS cell line may be derived from a haematopoietic precursor cell which can bind to skin fibroblasts and is localized in non-haematopoietic tissues resulting in the formation of extramedullary myeloid metaplasia. HSM-1 is a useful tool for analysing the characteristics of granulocytic sarcoma and homing receptors for haematopoietic stem cells.

Antigens, Surface↗
PubMed1992

Effects of massive small bowel resection on metabolism of bile acids and vitamin D3 and gastrin release in dogs.

The effects of ursodeoxycholic acid (UDCA) and 1 alpha-hydroxyvitamin D3 on pathophysiological changes following massive resection of the distal small bowel (75%) were investigated by using adult beagle dogs. After surgery, body weight decreased, watery diarrhea occurred, and the transit time of the alimentary tract shortened. These undesirable consequences lessened markedly after oral administration of UDCA, though 1 alpha-hydroxyvitamin D3 was not effective. Plasma levels of both 25-hydroxyvitamin D3 and 24, 25-dihydroxyvitamin D3 decreased after surgery, while plasma 1 alpha, 25-dihydroxyvitamin D3 concentrations remained unchanged during the observation period of six months. Although fasting plasma concentrations of total bile acid were not reduced, the integrated response to a meal decreased significantly after surgery in spite of the administration of UDCA. The concentration of UDCA in the gallbladder bile increased markedly in dogs which received UDCA. Taurine-conjugated bile acids accounted for more than 90% of the gallbladder bile. Postprandial hypergastrinemia occurred following the massive small bowel resection in the control group and in the group which received 1 alpha-hydroxyvitamin D3 alone, while it did not occur in the group given UDCA together with 1 alpha-hydroxyvitamin D3. These results indicate that administration of UDCA after massive resection of the small intestine is effective in maintaining good nutritional state.

Administration, Oral↗
PubMed1992

[The effect of oxygen free radical scavenger on endothelial cell at ischemic and reperfusion injury].

Although a lot of investigations indicated that free radical scavengers, such as superoxide dismutase (SOD) and catalase, reduced ischemia-reperfusion injury, the precise mechanism including the sites of action are still controversial. The purposes of this study were to investigate the sites of action of SOD and catalase by assessing postischemic cardiac and endothelial cell function. Wistar rats (450-550g) were used as support animals to establish blood perfused circuit. A peristaltic pump controlled the femoral arterial supply at 3.0 ml/min and the venous return to the jugular vein with gravity. Hearts (n = 8/group) from the Wistar rats were perfused (Langendorff model) and paced at 350 beats/min. After assessing baseline functions, hearts were rendered ischemia at 37.5 degrees C for 20 min. Then hearts were reperfused for 35 min, at the end of which left ventricular functions were re-assessed. One group of hearts received a continuous infusion of SOD and catalase during the period of 10 min before ischemia to 20 min after the onset of reperfusion. Left ventricular functions were measured with a left intraventricular balloon. The end-diastolic pressure was fixed at 10 mmHg, which was equivalent to the normal left ventricular end-diastolic pressure. The mean postischemic recovery of the left ventricular end-systolic pressure was increased from 55 +/- 3% in the control group to 67 +/- 2% in the SOD and catalase group (P less than 0.05). Similarly, the postischemic compliance was increased from 1.28 +/- 0.12 (microliters/mmHg) in the control group to 1.61 +/- 0.11 (microliters/mmHg) in the SOD and catalase group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Gastrin release from antral G cells stimulated with secretin.

Recently, gastrinoma cells were demonstrated to release gastrin when directly stimulated by secretin both in vivo and in vitro. In this study, the reaction of antral G cells was investigated. Secretin was injected into the right gastroepiploic artery in canines, and into the common hepatic artery during a selective arteriography in patients without gastrinomas. G cells obtained from the antrum of rats were attached to 0.45-microns filters and irrigated with medium containing secretin. The serum gastrin concentration increased rapidly in significant amounts and very quickly after an intraarterial injection of secretin, both in humans and in dogs. The rate of gastrin release from the rat antral G cells in vitro increased significantly when the medium contained secretin. In conclusion, secretin stimulated gastrin release from antral G cells both in vivo and in vitro.

Analysis of Variance↗
PubMed1991

Synergistic effects of interleukin-1 beta and interleukin-3 on the expansion of human hematopoietic progenitor cells in liquid cultures.

In the present study, we show that recombinant human interleukin-1 beta (rhIL-1 beta), which has no effect on the proliferation of human progenitor cells, has synergistic effects on the expansion of human progenitor cells induced by rhIL-3 in liquid cultures. The synergistic effects of rhIL-1 beta with rhIL-3 were observed in liquid cultures using not only fresh bone marrow mononuclear cells, but also selected populations of nonadherent cells, non-T nonadherent cells, and CD34-positive cells. Anti-granulocyte-macrophage colony-stimulating factor (anti-GM-CSF) antibody partially blocked the synergistic effects of rhIL-1 beta on the proliferation of colony-forming unit (CFU)-GM burst-forming unit-erythroid (BFU-E), and CFU-Mix in liquid cultures in the presence of rhIL-1 beta plus rhIL-3, suggesting that the synergistic effects of rhIL-1 beta plus rhIL-3 are explained in part by the secondary production of GM-CSF. Limiting dilution assays and liquid culture assays using CD34-positive cells indicate that rhIL-1 beta directly increases the numbers of colony-forming cells in liquid cultures. These results suggest that rhIL-1 beta has unique direct and indirect effects on the expansion of hematopoietic progenitor cells in liquid cultures.

Antibodies↗
PubMed1991

Deletion of 17p and amplification of the int-2 gene in esophageal carcinomas.

We have analyzed allelic deletion at 23 loci on 18 different chromosomes in 35 esophageal squamous cell carcinoma tissues by using restriction fragment length polymorphism markers. Loss of heterozygosity was detected on chromosomes 2, 3, 6, 7, 11-14, 16-18, 21, and 22, while no loss was detected on chromosomes 1, 4, and 8-10. Only the loss of chromosome 17p was detected with high frequency (45%), and losses on other chromosomes had frequencies of less than 22%. These losses with low frequencies might be random losses caused by chromosomal rearrangement during the course of tumor development and progression. On the contrary, the loss of 17p might play an important role in the development of esophageal squamous cell carcinoma, such as inactivation of a tumor suppressor gene. Amplification of the int-2 gene was observed in 39% of the tumors. However, no significant relationship between int-2 amplification and the deletion of any chromosome was detected.

Aged↗
PubMed1991

Transfection of chicken skeletal muscle alpha-actinin cDNA into nonmuscle and myogenic cells: dimerization is not essential for alpha-actinin to bind to microfilaments.

alpha-Actinins from striated muscle, smooth muscle, and nonmuscle cells are distinctive in their primary structure and Ca2+ sensitivity for the binding to F-actin. We isolated alpha-actinin cDNA clones from a cDNA library constructed from poly(A)+ RNA of embryonic chicken skeletal muscle. The amino acid sequence deduced from the nucleotide sequence of these cDNAs was identical to that of adult chicken skeletal muscle alpha-actinin. To examine whether the differences in the structure and Ca2+ sensitivity of alpha-actinin molecules from various tissues are responsible for their tissue-specific localization, the cDNA cloned into a mammarian expression vector was transfected into cell lines of mouse fibroblasts and skeletal muscle myoblasts. Immunofluorescence microscopy located the exogenous alpha-actinin by use of an antibody specific for skeletal muscle alpha-actinin. When the protein was expressed at moderate levels, it coexisted with endogenous alpha-actinin in microfilament bundles in the fibroblasts or myoblasts and in Z-bands of sarcomeres in the myotubes. These results indicate that Ca2+ sensitivity or insensitivity of the molecules does not determine the tissue-specific localization. In the cells expressing high levels of the exogenous protein, however, the protein was diffusely present and few microfilament bundles were found. Transfection with cDNAs deleted in their 3' portions showed that the expressed truncated proteins, which contained the actin-binding domain but lacked the domain responsible for dimerization, were able to localize, though less efficiently in microfilament bundles. Thus, dimer formation is not essential for alpha-actinin molecules to bind to microfilaments.

Actin Cytoskeleton↗