Search PubMed⌕ Search

Biomedical subjects

T Imamura

Publications and source records attributed to T Imamura.

At least 181 records · Page 10Linked to original sources
PubMed1998

Induction of Smad6 mRNA by bone morphogenetic proteins.

Members of the transforming growth factor-beta (TGF-beta) superfamily transduce signals via Smad proteins. Smad2 and Smad3 mediate TGF-beta signaling, whereas Smad1 and Smad5 transduce bone morphogenetic protein (BMP) signals. Smad4 is a common mediator required for both pathways. Smad6 and Smad7 are recently identified members in the Smad family; they inhibit the signaling activity of the other Smad proteins. Here we show that expression of the Smad6 mRNA is dramatically induced by BMP-2 or osteogenic protein-1 (OP-1)/BMP-7 in various cells. BMP-2 induced expression of Smad7 in one cell type, although much less potently than that of Smad6. Smad6 message was induced by TGF-beta 1 in TGF-beta 1-responsive Mv1Lu cells, but the induction was transient in contrast to the induction by BMPs. These results indicate that Smad6 may form a feedback loop to regulate the signaling activity of BMPs.

Animals↗
PubMed1998

Cognitive loss in dementia with Lewy bodies and Alzheimer disease.

BACKGROUND: Dementia with Lewy bodies (DLB) is emerging as a common cause of degenerative dementia. Some preliminary evidence exists that the pattern of cognitive impairment in DLB is different from that in Alzheimer disease (AD). OBJECTIVE: To delineate features of cognitive impairment of DLB on standardized neuropsychological tests. METHODS: We performed neuropsychological assessments of 26 patients with probable DLB (based on criteria of the consortium on DLB international workshop) and of 52 patients with probable AD (based on criteria of the National Institute of Neurological and Communicative Disorders and Stroke [now the National Institute of Neurological Disorders and Stroke])-Alzheimer's Disease and Related Disorders Association) who were matched to the patients with DLB 2:1 by age, sex, education, and Mini-Mental State Examination score. RESULTS: Compared with the group with probable AD, the group with probable DLB scored significantly lower on the picture arrangement, block design, object assembly, and digit symbol substitution subtests of the Wechsler Adult Intelligence Scale-Revised and on the Raven Colored Progressive Matrices test and significantly higher on the Mini-Mental State Examination locational orientation subtest and the Alzheimer's Disease Assessment Scale word recall subtest. A discriminant analysis revealed that the word recall score on the Alzheimer's Disease Assessment Scale and the block design score on the Wechsler Adult Intelligence Scale-Revised were the best discriminant factors. CONCLUSIONS: The disproportionately severe visuoperceptual, visuoconstructive, and visuospatial dysfunction and the disproportionately mild memory impairment in DLB compared with AD, which likely reflect the distribution of the pathologic changes in DLB, can help to differentiate DLB from AD.

Aged↗
PubMed1998

Development of Wernicke-Korsakoff syndrome after long intervals following gastrectomy.

BACKGROUND: Surgical exclusion of portions of the gastrointestinal tract is a predisposing risk factor for the development of Wernicke-Korsakoff syndrome. When this disease occurs, it is usually within weeks after the gastrointestinal surgery. However, it is not well known that Wernicke-Korsakoff syndrome may occur after a long latent interval following gastrectomy. SETTING: A research-oriented hospital. PATIENTS: Three patients without a history of alcoholism or dietary deprivation developed Wernicke-Korsakoff syndrome 2 to 20 years after undergoing gastrectomy. In these patients, minor changes in dietary habit led to the development of Wernicke-Korsakoff syndrome. CONCLUSIONS: In addition to a long-standing latent deficiency in thiamin levels due to defective absorption following gastrectomy or gastrojejunostomy, other minor factors that may influence the intake of thiamin and the need for thiamin in subjects who have undergone gastrectomy may cause a state of thiamin deficiency resulting in Wernicke-Korsakoff syndrome. Results from our study indicate that the following measures are mandatory: educating patients about proper dietary habits, carefully monitoring their thiamin intake, recognizing Wernicke-Korsakoff syndrome early, and treating it immediately with appropriate measures.

Aged↗
PubMed1998

Immunohistochemical detection of activin A, follistatin, and activin receptors during fracture healing in the rat.

Activins are multifunctional proteins that belong to the transforming growth factor-beta superfamily and are thought to play an important role in modulating the formation of bone. Activins exert their cellular effects by way of activin type-I and type-II serine/threonine kinase receptors. Follistatin is an activin-binding protein that can suppress the biological effects of activins. In this study, the immunohistochemical expression of activin A, follistatin, and activin receptors was studied during fracture healing in the rat. Activin A was weakly detected in the periosteum near the fracture ends at an early stage but was absent in the chondrocytes around the fracture gap, where endochondral ossification took place. An antibody to follistatin stained osteogenic cells in the periosteum near the fracture ends; moderate and strong staining were observed in proliferating, mature, and hypertrophied chondrocytes at the sites of endochondral ossification. Levels of activin A and follistatin were high near the osteoblasts on the surface of the newly formed trabecular bone. In addition, an intense localization of activin A was noted where multinucleated osteoclast-like cells were present. This study suggests that the activin-follistatin system may contribute to cellular events related to the formation and remodeling of bone during fracture healing. Activin type-I and type-II receptors were co-expressed in intramembranous and endochondral ossification sites. The expression of activin type-I, type-II, and type-IIB receptors in the absence of activin A in the endochondral ossification suggests that other isoforms of activins may signal by way of these receptors.

Activin Receptors↗
PubMed1998

Microsatellite instability and somatic mutations in endometrial carcinomas.

Recently, microsatellite instability (MI) has been demonstrated in some types of human cancers. In this study, we attempted to determine the frequency of MI in endometrial cancers and evaluate whether replication error (RER)-positive phenotype is correlated with known genetic mutations or the aberrations of other pathways in endometrial cancers. Seventy-two primary endometrial cancers were examined for microsatellite instability. Eleven tumors (15%) had RERs at two or more microsatellite loci, suggesting that generalized MI may be a molecular manifestation of endometrial cancers. We next examined whether the MI was associated with changes in the K-ras protooncogene, p53 tumor suppressor gene, and 18q LOH, which were frequently detected in endometrial cancers. The MI did not confer the potential to produce point mutations in the K-ras gene or 18q LOH, whereas the data were insufficient to identify the correlation between MI and p53 mutations in the cancers. These results suggest the presence of multiple mutation subsets that act in a complementary fashion in endometrial cancer development.

Chromosomes, Human, Pair 18↗
PubMed1998

Diffuse bilateral thalamic astrocytomas as examined serially by MRI.

We report the case of a 13-year-old girl with diffuse bilateral thalamic astrocytomas. Incoordination was observed at the onset. Cranial computed tomography (CT) showed enlarged thalami, and magnetic resonance imaging (MRI) revealed these lesions to be symmetrically enlarged with high intensity on the T2-weighted image. Owing to these atypical findings in the neuroimaging studies, we had difficulty in making the correct diagnosis of a brain tumor. After the diagnosis of diffuse bilateral thalamic astrocytomas was obtained, we performed hyperfractionated radiotherapy followed by chemotherapy. Radiation therapy was effective for a while, but the girl's condition deteriorated again and she died 8 months after admission. Although diffuse bilateral thalamic astrocytomas are difficult to diagnose because they do not resemble most other neoplasms on neuroimaging studies, pediatricians should keep this entity in mind in order to arrive at a precise and prompt diagnosis.

Adolescent↗
PubMed1998

Identification of beverages and beverage stains by GC/MS using aroma components as indicators.

A method to identify brown coloured beverages or beverage stains for criminological purposes was devised using aroma components as indicators. The examined beverages comprised three brands each of beer, coffee, cola and black tea, two brands of oolong tea, and four brands of green tea. Aroma components in each sample were efficiently concentrated with a porous polymer beads column (Porapak Q) and were analyzed by gas chromatography/mass spectrometry (GC/MS) using n-octyl alcohol as the internal standard. Specific aroma components were found in each beverage and beverage stain, for example cis-terpin hydrate in cola, and thus identification of beverages or beverage stains became feasible through the detection of these specific components. The present method was applied efficiently to two practical criminological cases.

Beer↗
PubMed1998

Expression of membrane-type matrix metalloproteinase-1 in human pancreatic adenocarcinomas.

The expression of a new type of matrix metalloproteinase, membrane-type matrix metalloproteinase-1 (MT-MMP-1), was examined in 24 cases of primary pancreatic adenocarcinomas and 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas, using a non-radioactive in situ hybridization and immunohistochemical methods. Out of 24 cases of primary pancreatic adenocarcinomas, 18 showed positive expression of MT-MMP-1 transcripts in cancer cells and 20 of 24 showed positive expression in the tumor stromal cells. The immunoreactivity of the gene products for MT-MMP-1 was demonstrated to be almost the same, as shown by in situ hybridization in these 24 cases. In particular, both the staining intensity for MT-MMP-1 transcripts and the immunoreactivity of the gene products in the tumor stromal cells of mucinous cystadenocarcinomas were significantly weaker than those of common-type ductal adenocarcinomas among the 24 cases. All of the 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas showed positive expression for MT-MMP- transcripts but less immunoreactivity for the gene products. These results suggest that MT-MMP-1 is transcribed and translated in both cancer cells and the tumor stromal cells in human pancreatic adenocarcinomas. Furthermore, considering that common-type ductal adenocarcinoma of the pancreas usually shows a strong desmoplastic reaction, while mucinous cystadenocarcinoma typically does not, MT-MMP-1 expressed in the tumor stromal cells of common-type adenocarcinomas may be involved in processes leading to the desmoplastic reaction.

Adenocarcinoma↗
PubMed1998

Rectal carcinoid tumor associated with the Peutz-Jeghers syndrome.

A 16-year-old man who had been diagnosed with the Peutz-Jeghers syndrome at the age of 8 years presented with crampy abdominal pain. Thorough examinations revealed a large jejunal polyp causing intussusception, as well as multiple polyps in the small and large intestines. Preoperative proctoscopy demonstrated the coexistence of a submucosal tumor in the rectum. Proctoscopic mucosal resection was performed and histological and immunohistochemical examinations led to a diagnosis of carcinoid tumor. Additional transanal resection of the rectal wall showed no residual tumor and the patient has been well for 2 years to date. Although malignant tumors are increasingly reported in association with the Peutz-Jeghers syndrome, to our knowledge, there have been no previous reports of such an association in the English-language and Japanese literature.

Adolescent↗
PubMed1998

The use of transbronchial lung biopsy to establish a diagnosis of benign clear cell tumor of the lung: report of a case.

Benign clear cell tumor (BCCT) is an extremely rare pulmonary neoplasm. We report herein a case of BCCT of the lung that was diagnosed by a transbronchial lung biopsy (TBLB). The findings of hematoxylin-eosin and immunohistochemistry obtained by the TBLB were consistent with a diagnosis of BCCT of the lung. Wedge resection was subsequently performed by video-assisted thoracotomy. To the best of our knowledge, this is the first reported case of BCCT diagnosed by TBLB.

Adult↗
PubMed1998

Membrane-type matrix metalloproteinase-1(MT1-MTP) gene is overexpressed in highly invasive hepatocellular carcinomas.

BACKGROUND/AIMS: The matrix metalloproteinase (MMP) family play important roles in the invasion of cancer cells by degrading the extracellular matrices. The current study was designed to determine the expression pattern of membrane-type matrix metalloproteinase-1 (MT1-MMP) in hepatocellular carcinomas and its participation in invasion potential. METHODS: MT1-MMP mRNA expression was examined in 25 human hepatocellular carcinoma specimens using Northern blot, and the correlation to clinicopathological features was evaluated. In situ hybridization and immunohistochemistry were performed to study the localization and the cells responsible for the production. RESULTS: Northern blot analysis revealed high levels of MT1-MMP mRNA expression in tumorous portions in all cases, whereas in non-tumorous portions moderate or faint expression was evident in 22/25 cases. In 21/25 cases, the expression levels in tumorous portion were higher than those in non-tumorous portion. In particular, hepatocellular carcinoma with capsule infiltration demonstrated significantly higher expression than those without (p<0.05). In situ hybridization and immunohistochemical study revealed MT1-MMP transcripts and proteins in cancer cells and stromal cells, respectively. MT1-MMP positive cells were preferentially observed in the invading border of tumor nests. The MMP-2 transcript showed a similar pattern to that of MT1-MMP by in situ hybridization. CONCLUSION: The present study showed that the MT1-MMP gene is strongly expressed in hepatocellular carcinoma cells and is involved in the invasion potential of hepatocellular carcinoma, and also that MT1-MMP may be one of the key molecules responsible for the invasion potential of hepatocellular carcinoma. Furthermore, the evidence suggests that MT1-MMP and MMP-2 cooperate in the process of cancer invasion.

Adult↗
PubMed1998

Age at onset and language disturbances in Alzheimer's disease.

This study examined the effect of age at symptom onset of Alzheimer's disease (AD) on the pattern of language disturbance. We assessed 150 consecutive patients with a clinical diagnosis of mild-to-moderate AD using the Western Aphasia Battery and a 100-item picture-naming test. A multivariate linear regression analysis examined the effect of age at onset after controlling for gender, education, severity of dementia and duration of the disease. Patients with early onset performed significantly worse than did patients with late onset on the word comprehension and sequential commands subtests. On the other hand, late-onset patients performed more poorly than early-onset patients on the picture-naming test in a subgroup with mild language deficits. However, the trend disappeared in other subgroups with more degraded language function. We consider that the concomitant effects of normal aging worsened the picture-naming deficits in the late-onset patients, and the rapid decline of naming ability in the early-onset patients masked the aging effect with the progression of language deficits. The deterioration of word comprehension and the rapid decline of naming ability are the characteristics of early-onset patients. The different patterns of language deficits between early- and late-onset patients may correspond to the genetic heterogeneity of AD.

Age of Onset↗
PubMed1998

Acetylcholine reactivates latent pseudorabies virus in mice.

The latency model of pseudorabies virus (PrV) wild strain, YS-81, in mice was established and latent PrV reactivated with acetylcholine. The latent PrV was reactivated from the trigeminal ganglia with acetylcholine. It was found that this model is useful in investigating the mechanism of latent PrV reactivation by acetylcholine.

Acetylcholine↗
PubMed1998

Long-term survival after repeated resections of Askin tumor recurrences.

The case of a 16-year-old boy is reported who underwent surgery for the excision of an Askin tumor and has subsequently undergone six excisions of local Askin tumor recurrences, with follow-up postoperative chemo- and radiotherapy over a 7-year period. The patient continues to survive. As far as can be determined, this patient appears to be the first reported case of long-term survival after repeated resections of local Askin tumor recurrences. It thus may be that postoperative chemo- and radiotherapy after repeated excisions of these local Askin tumor recurrences plays a role in prolonging survival.

Adolescent↗
PubMed1998

Signal transduction by bone morphogenetic proteins.

Bone morphogenetic proteins (BMPs) are multifunctional cytokines, which are members of the transforming growth factor-beta (TGF-beta) superfamily. Activities of BMPs are extracellularly regulated by BMP-binding proteins, Noggin and Chordin. BMPs bind to two different types of serine-threonine kinase receptors, type I and type II. Two BMP type I receptors and a BMP type II receptor have been identified in mammals. Intracellular signals are transduced by Smad proteins. Smad1, Smad5 and probably MADH6, are activated by BMP receptors, form heteromeric complexes with Smad4, and translocate into the nucleus where they may activate transcription of various genes. Smad6 and Smad7 are inhibitory Smads, and may act as autocrine switch-off signals. In Drosophila melanogaster, Decapentaplegic (Dpp) is a homologue of mammalian BMPs. In this review, mechanism of action of Dpp will be discussed in comparison with that of BMPs.

Animals↗
PubMed1998

Distinct and overlapping patterns of localization of bone morphogenetic protein (BMP) family members and a BMP type II receptor during fracture healing in rats.

Bone morphogenetic proteins (BMPs) and their receptors (BMPRs) are thought to play an important role in bone morphogenesis. The purpose of this study was to determine the locations of BMP-2/-4, osteogenic protein-1 (OP-1, also termed BMP-7), and BMP type II receptor (BMPR-II) during rat fracture healing by immunostaining, and thereby elucidate the possible roles of the BMPs and BMPR-II in intramembranous ossification and endochondral ossification. In the early stage of fracture repair, the expression of BMP-2/-4 and OP-1 was strongly induced in the thickened periosteum near the fracture ends, and coincided with an enhanced expression of BMPR-II. On day 7 after fracture, staining for BMP-2/-4 and OP-1 immunostaining was increased in various types of chondrocytes, and was strong in fibroblast-like spindle cells and proliferating chondrocytes in endochondral bone. On day 14 after fracture, staining with OP-1 antibody disappeared in proliferating and mature chondrocytes, while BMP-2/-4 staining continued in various types of chondrocytes until the late stage. In the newly formed trabecular bone, BMP-2/-4 and OP-1 were present at various levels. BMPR-II was actively expressed in both intramembranous ossification and endochondral ossification. Additionally, immunostaining for BMP-2/-4 and OP-1 was observed in multinucleated osteoclast-like cells on the newly formed trabecular bone, along with BMPR-II. In reference to our previous study of BMP type I receptors (BMPR-IA and BMPR-IB), BMPR-II was found to be co-localized with BMPR-IA and BMPR-IB. BMP-2/-4 and OP-1 antibodies exhibited distinct and overlapping immunostaining patterns during fracture repair. OP-1 may act predominantly in the initial phase of endochondral ossification, while BMP-2/-4 acts throughout this process. Thus, these findings suggested that BMPs acting through their BMP receptors may play major roles in modulating the sequential events leading to bone formation.

Animals↗
PubMed1998

Overexpression of the rhoC gene correlates with progression of ductal adenocarcinoma of the pancreas.

It has been reported that the rho genes, which consist of a ras-related small GTPase protein family, regulate cytoskeletal structures and have the potential to transform cultured cells. To investigate the biological relevance of the rho genes in pancreatic carcinogenesis, we examined expressions of the rhoA, B and C genes by polymerase chain reaction after reverse transcription (RT-PCR) in 33 cases of ductal adenocarcinoma of the pancreas. In addition, mutations of the K-ras, rhoA, B and C genes were studied in the same series of tumour tissues to correlate with rho gene expressions. The expression levels of the rhoC gene were significantly higher in tumours than in non-malignant portions (P < 0.001). Metastatic lesions overexpressed the rhoC gene compared with primary tumours (P < 0.05). Carcinoma tissues with perineural invasion and lymph node metastasis exhibited significantly higher expressions of the rhoC gene than tumours without these manifestations (P < 0.001 and P < 0.05 respectively). Overexpression of the rhoC gene significantly correlated with poorer prognosis of patients with pancreatic adenocarcinoma (P < 0.05). In contrast, the expression levels of the rhoA and B genes showed no significant relationship with clinicopathological findings. Mutation was not found either in the rhoA, B or C gene sequences examined. K-ras gene mutation, detected in 27 out of 33 (81.8%) cases, did not affect the expression levels in any of the rho genes. These suggest that elevated expression of the rhoC gene may be involved in the progression of pancreatic carcinoma independent of K-ras gene activation.

Adult↗