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N Igarashi

Publications and source records attributed to N Igarashi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Application of a fine thread beam to the structure analysis of a hemihedrally twinned crystal of hydroxylamine oxidoreductase.

Accurate diffraction intensity data have been collected from a twinned P6(3) crystal of the 24-haem protein hydroxylamine oxidoreductase, from a nitrifying chemoautotrophic bacterium Nitrosomonas europaea, using synchrotron radiation at station BL6A of the Photon Factory. Estimation of the twinning fraction and deconvoluted intensity data, including native and heavy-atom derivative data, gave an improved Patterson function. Four diffraction data sets were collected from one crystal and an estimation of the twinning fraction to confirm the phenomena was undertaken. The successfully detwinned data sets were utilized in the structure analysis of the present enzyme. The mechanism of twinned-crystal formation is also discussed.

Journal Article↗
PubMed1998

Structure and function of 6,7-dicarboxyheme-substituted myoglobin.

Myoglobin was reconstituted with 6,7-dicarboxy-1,2,3,4,5, 8-hexamethylheme, a compact synthetic heme with the shortest acid side chains, to pursue the structural and functional consequences after intensive disruption of the heme propionate-apoglobin linkages in the native protein. The electron-withdrawing carboxylate groups directly attached to the porphyrin ring lowered the oxygen affinity by 3-fold as compared with native myoglobin. Autoxidation of the oxy derivative to the ferric protein proceeded with 1.6 x 10(-)2 min-1 at pH 7.0 and 30 degrees C. The crystallographic structure of the cyanomet myoglobin with 1.9 A resolution shows that the heme adopts a unique orientation in the protein pocket to extend the two carboxylates toward solvent sphere. The native globin fold is conserved, and the conformations of globin side chains are almost intact except for those located nearby the heme 6,7-carboxylates. The 7-carboxylate only weakly interacts with Ser92 and His97 through two mediating water molecules. The 6-carboxylate, on the other hand, forms a novel salt bridge with Arg45 owing to conformational flexibility of the guanidinium side chain. The proton NMR shows that the small heme does not fluctuate about the iron-histidine bond even at 55 degreesC, suggesting that the salt bridge between Arg45 and heme 6-carboxylate is of critical importance to recognize and fix the heme in myoglobin.

Animals↗
PubMed1998

Distribution and expression of mRNAs for the proto-oncogenes c-fos and c-jun in bone cells in vivo.

In this study we assessed the expression and localization of the proto-oncogenes c-fos and c-jun in normal bone so as to gain more insight into the role of these proto-oncogenes in bone tissue. Femurs of 4-week-old rats were examined by non-radioactive in situ hybridization. cDNA probes for c-fos- and c-jun-labeled digoxygenin were produced by Polymerase Chain Reaction (PCR). C-fos and c-jun exhibited similar distribution in growth plate and bone tissue. Expression of c-fos and c-jun mRNAs in growth plate was observed in the proliferative zone and partly in the upper layer of the hypertrophic zone. In spongy bone, high expression of c-fos and c-jun mRNAs was observed in the osteoblast cytoplasm. However, there was little expression in bone lining cells. In the bony trabeculae, slight expression of c-fos and c-jun was observed in the premature osteocytes situated close to the bone surface, but no expression was detected in osteocytes that possessed relatively large lacunae in the center of the trabeculae. C-fos and c-jun were also slightly expressed in osteoclasts. These data strongly suggest that c-fos and c-jun are involved in regulating chondrocyte proliferation as immediate early genes, and may also be involved in the gene expression of bone matrix proteins as transcription factor (AP-1) in vivo. In addition, the fact that strong expression was observed in osteoblasts but hardly any expression at all in bone lining cells seems to suggest that these genes are also involved in osteoblast activation.

Animals↗
PubMed1998

Apoptosis in adenoma and early adenocarcinoma of the colon.

Twenty-six specimens of tubular adenoma and 7 specimens of adenocarcinoma in adenoma of the colon were examined to evaluate apoptosis between adenoma and early adenocarcinoma. Cell proliferation and cell death seemed to be balanced in adenoma with mild and moderate atypia, but unbalanced in adenoma with severe atypia and cancer. Apoptosis was considered to be suppressed at cancer in some cases. However, a number of apoptosis increased at cancer in other cases. Necrosis was seen only in cancer areas. The ratio of cells simultaneously stained by anti-Ki-67 antibody (MIB-1) and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling (TUNEL) tended to be high from adenoma with moderate atypia to cancer, suggesting the unstableness of DNA. It is possible that cancer cells having highly unstable DNA easily underwent apoptosis as well as necrosis, accidentally. The p53 protein was positive only in cancer areas of three cases. One of these three showed decreased apoptosis in a cancer area, but the other two cases showed increased apoptosis. Furthermore, certain numbers of cancer cells were double-stained by p53 immunohistochemistry and TUNEL. These results suggest that the p53 protein may contribute to suppress apoptosis in the last stage of carcinogenesis of the colonic adenocarcinoma, but other factors including extrinsic stimulation may cause apoptosis despite the mutation of p53 protein.

Adenocarcinoma↗
PubMed1998

[Laparoscopic surgery for early gastric cancer--its advantages and pitfalls].

We have successfully established two different laparoscopic procedures for early gastric cancer since March 1992, which are laparoscopic wedge resection of the stomach using a lesion-lifting method and laparoscopic intragastric mucosal resection. The indication is as follows; (A) mucosal cancer, (B) < 25 mm, if the lesion is elevated type, (C) < 15 mm and Ul (-), if the lesion is depressive type. The advantages of these methods are; 1) minimally invasiveness, 2) sufficient surgical margin, 3) feasibility of detailed histology, 4) feasivility of perigastric lymph node dissection. In contrast, there are several problems to be solved, which are; 1) preoperative diagnostic accuracy of the depth of cancer invasion, 2) possibility of reoperation because of sm invasion or lymphatic or venous invasion in final histology, 3) possibility of postoperative stenosis after laparoscopic intragastric mucosal resection for the lesion near the cardia, 4) incidence of metachronous multiple gastric cancer. In conclusion, if the indication is properly selected, these laparoscopic procedures are curative and minimally invasive treatment for early gastric cancer.

Gastric Mucosa↗
PubMed1998

Photosensitive drug eruption induced by flutamide.

We describe a 68-year-old man who showed a photosensitive drug eruption induced by flutamide. The minimal erythema dose with ultraviolet A light was reduced to 2 J/cm2 under administration of flutamide, which recovered to over 16 J/cm2 after cessation of the medication, without changing the reactivity to ultraviolet B. The absorption spectrum of flutamide was not altered after ultraviolet A irradiation, suggesting that flutamide is photostable with regard to ultraviolet A. In addition, bovine serum albumin was not covalently photocoupled with flutamide under ultraviolet A. Thus, flutamide seems to have low potency to act as a photohapten, and it is likely that a non-photohaptenic mechanism operates in this photosensitivity or its active metabolite may work as a photosensitizer.

Aged↗
PubMed1997

The role of stromal cells in the expression of interstitial collagenase (matrix metalloproteinase-1) in the invasion of gastric cancer.

BACKGROUND AND OBJECTIVES: In one of the steps of tumor invasion and metastasis, tumor cells must invade surrounding tissues and degrade the components of the basement membranes. Interstitial collagenase (matrix metalloproteinase-1: MMP-1) has been also investigated in relation to cancer invasion and metastasis. METHODS: We investigated the formation and mechanism of MMP-1 expression using gastric cancer cell lines and gastric fibroblasts derived from normal gastric mucosa by ELISA and immunohistochemistry. RESULTS: Production of MMP-1 protein in gastric fibroblasts was stimulated significantly by adding the conditioned medium of MKN-74. Localization of MMP-1 protein in the xenografted gastric cancer cell lines was heterogeneous according to different cell lines. CONCLUSIONS: These results suggested that the production of MMP-1 protein in tumor invasion was regulated by interaction between stromal cells, particularly fibroblasts, and tumor cells.

Animals↗
PubMed1997

The 2.8 A structure of hydroxylamine oxidoreductase from a nitrifying chemoautotrophic bacterium, Nitrosomonas europaea.

The 2.8 A crystal structure of hydroxylamine oxidoreductase of a nitrifying chemoautotrophic bacterium, Nitrosomonas europaea, is described. Twenty-four haems lie in the centre bottom of the trimeric molecule, localized in four clusters within each monomer. The haem clusters within the trimer are aligned to form a ring that has inlet and outlet sites. The inlet is occupied by a novel haem, P460, and there are two possible outlet sites per monomer formed by paired haems lying within a cavity or cleft on the protein surface. The structure suggests pathways by which electron transfer may occur through the precisely arranged haems and provides a framework for the interpretation of previous and future biochemical and genetic observations.

Amino Acid Sequence↗
PubMed1997

Analysis of the steroidogenic acute regulatory protein (StAR) gene in Japanese patients with congenital lipoid adrenal hyperplasia.

Genomic DNA from 19 Japanese patients with congenital lipoid adrenal hyperplasia (lipoid CAH) representing 16 different families was examined to identify the genetic alterations of steroidogenic acute regulatory protein (StAR). Ten of 19 patients had a 46,XX karyotype and nine had a 46,XY karyotype. Six of the 46,XX patients have experienced spontaneous pubertal changes including breast development and irregular menstruation whereas none of the 46,XY subjects displayed pubertal changes. Eight different mutations were identified. Sixteen patients were either homozygotes or compound heterozygotes for the Q258X mutation. The seven other mutations identified were 189delG, 246insG, 564del13bp, 838delA, Q212X, A218V and M225T. The 189delG, 246insG, 546del13bp and Q212X mutants encode truncated proteins. COS-1 cells transfected with expression vectors encoding cDNAs for the mutant StAR proteins which affect the C-terminus, 838delA, A218V and Q258X, exhibited no steroidogenesis enhancing activity. However, the M225T mutant retained some steroidogenic activity. The patient with the M225T mutation had late onset of this disorder and some capacity to secrete testosterone in response to hCG. These findings suggest: (i) that the Q258X mutation can be used as a genetic marker for the screening of Japanese for lipoid CAH, (ii) that the C-terminus of StAR plays an important role in the protein's activity and (iii) that there are differences in the extent of functional impairment of the testis and ovaries in lipoid CAH.

Adrenal Hyperplasia, Congenital↗
PubMed1997

Matrix metalloproteinase gene expression in chronic gastric ulcer: a potential role of eosinophils in perforation.

Gene expression of matrix degrading enzymes was investigated in surgical specimens of perforated gastric ulcers. In these ulcers, the inflammatory cells infiltrating into the granulation tissue were granulocytes, particularly eosinophils. The extracellular matrix of the stomach wall consists mainly of collagen types I and III, which are selectively degraded by matrix metalloproteinase-1 (MMP-1). MMP-1 mRNA was detected in the cytoplasm of infiltrating cells, suggesting that eosinophils play an important role in ulcer recurrence and in perforation of the stomach wall. The degree of eosinophil infiltration into an ulcer base may be a useful marker for the risk of perforation. Patients showing this marker may benefit from a prophylactic therapy for preventing severe complications. The control of MMP gene expression represents a potential strategy for the treatment of recurrent gastric ulcer.

Adult↗
PubMed1997

Cervical spinal cord infarction after surgery for a pineal region choriocarcinoma in the sitting position: case report.

OBJECTIVE AND IMPORTANCE: Spinal cord injury is one of several devastating complications after operation in the sitting position. Young patients exhibiting extraordinary growth spurts demonstrate a higher risk for this complication. CLINICAL PRESENTATION: We describe a 7-year-old male patient with a pineal region choriocarcinoma in whom a cervical spinal cord infarction (C5-T1) developed as an acute complication after operation in the sitting position. Preoperatively, high serum levels of human chorionic gonadotropin (5867.7 mIU/ml) and somatomedin-C (704 ng/ml) and an extreme growth velocity in height (16 cm/yr) were noted. CONCLUSION: It is assumed that, in addition to head flexion, the abnormal skeletal growth spurt resulting from an excessive secretion of human chorionic gonadotropin from a tumor was a possible predisposing factor for this complication. To prevent this complication, surgeons need to pay great attention to head positioning, especially in a young patient experiencing an active growth spurt.

Brain Neoplasms↗
PubMed1997

[Jejunal pouch interposition after total gastrectomy].

The results and procedures of interposed jejunal pouch after total gastrectomy for gastric cancer are reported. Basic requirements of reconstruction after total gastrectomy are 1) formation of a food reservoir, 2) maintenance of duodenal continuity, 3) avoidance of reflux esophagitis, 4) gradual emptying of reservoir into the small intestine. Since 1950's, several procedures of gastric substitutes have been reported. But they were not widely performed. Because scientific evaluation of the value of gastric substitutes was difficult and the operative procedures were time consuming and complicated. With an increasing ratio of early gastric cancer in 1990's, the importance of post-operative QOL, such as food intake and body weight maintenance, in patients after total gastrectomy has been recognized. Our procedure is a double lumen jejunal pouch distal to a interposed jejunum. The length of interposed jejunum is 20 cm and that of pouch is 10 cm. Using surgical staplers, this procedure is safe and simple. Jejunal pouch interposition leads to a satisfactory symptomatic and nutritional result in gastrectomized patients.

Gastrectomy↗
PubMed1997

[High fever during the treatment of acute promyelocytic leukemia with all-trans retinoic acid].

A 56-year-old woman was admitted for evaluation of petechiae and acute promyelocytic leukemia was diagnosed. Administration of all-trans retinoic acid (ATRA) at 60 mg per day was begun. On the same day, high fever was recognized. There was no evidence of infection nor other organ dysfunction. Administration of steroid caused a resolution of the fever. The same phenomenon was observed three times subsequently. High fever was the adverse reaction in this patient during the treatment of ATRA, and steroid was dramatically effective.

Anti-Inflammatory Agents↗
PubMed1997

Assessment of intravascular ultrasound-bearing balloon catheter-guided percutaneous transluminal coronary angioplasty and stenting.

To investigate the usefulness of an intravascular ultrasound (IVUS)-bearing balloon catheter, we analyzed results in 17 patients with 19 lesions who underwent percutaneous transluminal coronary angioplasty (PTCA) with IVUS-bearing balloon catheters (group A) and 25 patients with 28 lesions who underwent PTCA without IVUS (group B). The patients had angina pectoris with or without old myocardial infarction. The success rate (less than 50% residual stenosis on coronary angiography) in group A was 17/17 patients (100%) and 19/19 lesions (100%), and that in group B was 21/25 patients (84%) and 24/28 lesions (86%) (NS). The percent stenosis, by coronary angiography, in groups A and B was 71.3% and 76.8% before PTCA (NS) and 4.8% and 22.3% in groups A and B after PTCA (P = 0.005). Complication rates in the two groups were not significantly different, but non-Q myocardial infarction was observed in one patient with a type C lesion (according to the American Heart Association/American College of Cardiology [AHA/ACC] classification) in group A. Postdilation of Wiktor stents was determined by IVUS in four patients. These results suggest that the IVUS-bearing balloon catheter is useful to achieve larger lumen size for optimal PTCA.

Adult↗
PubMed1996

Morphological analysis of pancreatic endocrine cells in newborn animals delivered by experimental diabetic rats.

Rats with mildly impaired glucose tolerance (MIGT) were prepared by the administration of streptozotocin and subsequent islet-isotransplantation. Of pups born to these rats, 65% exhibited macrosomia that weighed over 6.8 g (average weight of control pups was 5.96 g). The morphological changes in the endocrine pancreas in pups born of MIGT and normal control rats were studied using immunohistochemical methods and quantitative morphological analysis. In macrosomic pups, the percentages of pancreatic tissue devoted to islet areas and B cell areas were significantly higher than in control pups. The percentage of pancreas devoted to A cell areas was also higher in macrosomic than normal pups, while the ratio of A/B cell areas was in normal range. In non-macrosomic pups born to MIGT rats, the percentages of pancreas devoted to islet tissues, B cell, and A cell areas were each lower than these in macrosomic pups. Moreover, increase in the proportions of islet and B cell areas in the pancreatic tissue in pups born of MIGT mothers was linearly correlated with increase in birthright. There were no significant differences in D cell area as a proportion of pancreas among macrosomic, non-macrosomic and control pups. These findings suggest that insulin secreted from B cells play important roles in the control of fetal growth.

Animals↗