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Biomedical subjects

T Kitamura

Publications and source records attributed to T Kitamura.

At least 73 records · Page 4Linked to original sources

Seroepidemiological survey of wild rats for Seoul virus in Indonesia.

The prevalence of antibodies against Seoul virus was investigated in 655 wild rats (Rattus norvegicus, R. rattus, R. rattus diardii, R. exulans, R. tiomanicus) captured in seven port areas of Indonesia. Twenty-four of 238 R. norvegicus, one of 142 R. rattus and one of 102 R. exulans from two port areas had the antibodies against Seoul virus.

Animals

Applications of retrovirus-mediated expression cloning.

We have recently established a novel expression cloning system using retroviral vectors. The system is based on a high-efficiency packaging cell line, BOSC23, and a simplified retroviral vector, pBabeX, carrying no selection marker. cDNA libraries, constructed in the pBabeX vector, are transiently transfected into BOSC23 cells. The supernatant contains more than 3X10(6)/mL, which would cover large complexities of cDNA libraries. The retrovirus stock gave 100% infection efficiency in NIH3T3 cells and 5-40% infection efficiency in various hematopoietic cell lines. In contrast to the conventional expression cloning system, in which it is necessary to transfect cDNA libraries transiently into particular cell types such as COS cells, retrovirus-mediated expression cloning allows us to transduce cDNAs into a wide variety of cell types. This method therefore makes it possible to select cells expressing a cDNA of interest by various functional assays. When combined with polymerase chain reaction (PCR)-driven random mutagenesis, this system is also useful in searching for mutations of various molecules that will result in alterations of their functions.

3T3 Cells

[Urothelial carcinoma of the navicular fossa].

We report a case of transitional cell carcinoma arising in the fossa navicularis. The patient was a 74-year-old man. He had no history of sexually transmitted disease or urethral stricture. Clinically, the tumor was suspected to be a condyloma acuminatum; however, the pathological diagnosis yielded an unexpected result: transitional cell carcinoma. Radiological examinations and cystoscopy showed no other tumor besides the primary cancer in the fossa navicularis. Partial resection of the urethra was performed and the patient has been without evidence of disease for 3 years.

Aged

Diagnosis of pancreatic cancer by K-ras point mutation and cytology of pancreatic juice.

OBJECTIVES: Recently, it was reported that detection of K-ras point mutation at codon 12 in pancreatic juice is an objective method for the diagnosis of pancreatic cancer, but a few reports have suggested that this might represent an early event in pancreatic oncogenesis. In the present study we examined, in various patients, the occurrence of K-ras codon 12 point mutation in pancreatic juice and compared it with pancreatic juice cytology, which is also a reliable diagnostic method. METHODS: Pancreatic juice was obtained endoscopically from patients with various pancreatic disorders and those without definite diseases, and was examined cytologically and for the occurrence of K-ras codon 12 point mutation. The K-ras gene was amplified by polymerase chain reaction (PCR) and the mutation at codon 12 (GGT-->GAT) was examined by slot blot hybridization analysis. RESULTS: K-ras point mutation at codon 12 was detected in seven of 14 (50%) pancreatic cancers, in four of 10 (40%) mucin-producing tumors, in four of 13 (31%) chronic pancreatitis, and in two of 10 (20%) pancreas without definite disorders. K-ras point mutation was detected in nine of 18 (50%) pancreatic juice samples containing cancer cells, in eight of 18 (44%) pancreatic juice samples containing atypical cells, but in none of such samples containing only normal cells. CONCLUSION: Cancer cells were detected from pancreatic cancer exclusively, but K-ras point mutation at codon 12 was detected in pancreatic juice, not only from pancreatic cancer, but also from other diseases.

Aged

[Indocyanine green angiography of choroidal neovascularization in age-related macular degeneration].

One hundred forty eyes with choroidal neovascularization (ChNV) in age-related macular degeneration were examined with fluorescein and indocyanine green (ICG) angiography. ChNVs covered with subretinal hemorrhage, and ChNVs with retinal pigment epithelial (RPE) detachment were demonstrated at a higher rate and more clearly with ICG angiography than with fluorescein angiography. On the other hand, ChNVs in serous retinal detachment, and in disciform lesions were demonstrated more clearly with fluorescein angiography than with ICG angiography. These results show that ICG angiography is valuable for delineating "occult ChNVs" with subretinal hemorrhage or RPE detachment in age-related macular degeneration.

Aged

Ultrastructural study on the harderian gland of the rabbit (Oryctolagus cuniculus).

The ultrastructure of the Harderian gland of the rabbit has been studied. The gland can be divided into two lobes (pink and white) by the naked eye. At the microscopic level, their epithelial cells differ morphologically, the vacuoles in the cells of the pink lobe being large, while those of the white lobe, small. In addition to the pink and white lobes, an intermediate area can be distinguished around the boundary between the two lobes on the basis of epithelial cell compositions. The acini on this area consist of two epithelial cell types, one is similar to that found in the white lobe, the second consists of the same cells as the pink lobe Myoepithelial cells are located between the secretory epithelium and its basal lamina. Mast cells, macrophages and plasma cells are found in the interstitial connective tissue of the Harderian gland.

Animals

Efficient screening of retroviral cDNA expression libraries.

Expression cloning of cDNAs was first described a decade ago and was based on transient expression of cDNA libraries in COS cells. In contrast to transient transfection of plasmids, retroviral gene transfer delivers genes stably into a wide range of target cells. We utilize a simple packaging system for production of high-titer retrovirus stock from cDNA libraries to establish a cDNA expression cloning system. In two model experiments, murine interleukin (IL)-3-dependent Ba/F3 cells were infected with libraries of retrovirally expressed cDNA derived from human T-cell mRNA or human IL-3-dependent TF-1 cell line mRNA. These infected Ba/F3 cells were selected for the expression of CD2 by flow cytometry or for the alpha subunit of the human IL-3 receptor (hIL-3R alpha) by factor-dependent growth. CD2 (frequency, 1 in 10(4)) and hIL-3R alpha (frequency, 1 in 1.5 x 10(5)) cDNAs were readily detected in small-scale experiments, indicating this retroviral expression cloning system is efficient enough to clone low-abundance cDNAs by their expression or function.

3T3 Cells

Hepatocyte growth factor inhibits intercellular communication via gap junctions in rat hepatocytes.

We demonstrated that HGF reduces gap junctional intercellular communication of rat hepatocyte doublets and increases cell spreading. Intercellular communication via gap junctions was markedly reduced in hepatocyte doublets with HGF (20 ng/ml) 3-12 hr after inoculation. Immunocytochemistry revealed spotty localization of connexin 32 on the plasma membrane of 3-hr cultured control hepatocyte doublets, whereas HGF-treated doublets showed significantly less connexin 32 staining. Genistein maintained intercellular communication in the presence of HGF, indicating that HGF reduces intercellular communication by down regulation of connexin 32 through the c-met/HGF receptor-tyrosine-kinase-mediated pathway. Furthermore, TGF-beta 1 maintained intercellular communication in the presence of HGF. Regulation of intercellular communication in hepatocytes by HGF and TGF-beta 1 might play an important role during liver regeneration.

Analysis of Variance

Induction of endometrial adenocarcinomas by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine to aged Donryu rats showing spontaneously persistent estrus.

Induction of endometrial adenocarcinomas by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) to aged rats was examined. Donryu rats showing spontaneously persistent estrus were given a single intra-uterine administration of ENNG (20 mg/kg) at 10 months (44 weeks) of age. At the termination of the experiment (week 34 after the ENNG-treatment), 22% and 13% incidences of endometrial adenocarcinomas were observed in the experimental and control groups, respectively, the difference being without significance. No variation was found in the endocrine environment between experimental and non carcinogen-treated control animals throughout the experimental period. These results show that ENNG-treatment alone is not sufficient in aged rats for high induction of endometrial carcinomas. Comparison of the data with those from our previous studies, in which ENNG was given at a young age (10 weeks of age), indicates that young rats may be more sensitive than their old counterparts.

Adenocarcinoma

Interleukin 2 and erythropoietin activate STAT5/MGF via distinct pathways.

Signal transducers and activators of transcription (STAT) proteins play an important role in cytokine signal transduction in conjunction with Janus kinases (JAKs). MGF/STAT5 is known as prolactin regulated STAT. Here we demonstrate that interleukin 2 (IL-2) as well as erythropoietin (EPO) stimulate STAT5 and induce tyrosine phosphorylation of STAT5. These IL-2- and EPO-induced STATs have an identical DNA binding specificity and immunoreactivity. We also show that IL-4 induces a DNA binding factor which possesses similar, but distinct, DNA binding specificity from that of STAT5 and is immunologically different from STAT5. Analysis of two EPO receptor (EPOR) transfected CTLL-2 cell lines discloses that IL-2 activates JAK1 and JAK3 as well as STAT5, while EPO stimulates STAT5 and JAK2 in EPO-responsive CTLL-2 cells (ERT/E2). On the contrary, EPO activates neither JAK2 nor STAT5 in other cell lines that failed to respond to EPO (ERT cells). EPOR and JAK2 associate with each other regardless of EPO presence in ERT/E2 cells, however, such an interaction is not present in ERT cells. Thus, EPOR and JAK2 association seems to be important for EPO responsiveness in CTLL-2 cells.

Animals

Late rectal complication following high dose rate intracavitary brachytherapy in cancer of the cervix.

PURPOSE: To examine the incidence of radiation-induced late rectal complications using a rectal reference point in patients with cancer of the uterine cervix. METHODS AND MATERIALS: The subjects were 253 patients with cancer of the cervix who underwent high dose rate intracavitary brachytherapy (HDR-ICR). The rectal point (RP) was defined according to the criteria recommended in the ICRU Report 38. The time-dose factor (TDF) and the biologically effective dose (BED) were calculated as components of the cumulative reference rectal dose using the rectal reference point dose in intracavitary brachytherapy combined with the external whole pelvis dose. RESULTS: Statistical comparison of factors affecting the incidence of late rectal complication was conducted using data for 161 patients. The incidence of late rectal complications in the 161 patients was 9 patients (5.6%) for grade 1, 51 patients (31.7%) for grade 2, 11 patients (6.8%) for grade 3, and 13 patients (8.1%) for grade 4. The TDF and BED values were significantly correlated with the incidence of late rectal complication, and also showed strong correlation (r = 0.976) with each other. Grade 4 rectal complication was not observed in any patients with TDF below 130 or BED below 147. The calculated incidence of complications ranged from 5 to 10% at TDF values from 104 to 124 and at BED values from 119 to 146. CONCLUSION: These data regarding the incidence of rectal complication may be useful in reducing the incidence of late rectal complications arising after HDR-ICR treatment of cervical uterine cancer by adjusting the dose per fraction and number of fractions of HDR-ICR in individual patients and by improving the technique of inserting the intracavitary radiation apparatus.

Female

Human IL-3 receptor signaling: rapid induction of phosphatidylcholine hydrolysis is independent of protein kinase C but dependent on tyrosine phosphorylation in transfected NIH 3T3 cells.

Although tyrosine kinases are clearly activated after ligand engagement of the human IL-3R in both hematopoietic and nonhematopoietic cytoplasmic environments, a role for phospholipid hydrolysis and protein kinase C in IL-3R signal transduction is emerging. We have used NIH 3T3 cells transiently transfected with human IL-3R alpha- and beta-subunits to study phosphatidylcholine hydrolysis in response to human IL-3. We have found that NIH 3T3 cells expressing the complete human IL-3R respond to human IL-3 with a rapid and sustained increase in sn-1'2'-diacylglycerol. Accompanying this was a rapid increase in intracellular levels of phosphorylcholine. The protein kinase C inhibitor H-7, however, was not effective in inhibiting phosphatidylcholine hydrolysis in response to human IL-3 in NIH 3T3 cells expressing the human receptor. Thus the human IL-3R induces a rapid protein-kinase-C-independent hydrolysis induced by the murine receptor. Simultaneous with the increase in phosphatidylcholine hydrolysis induced by the murine receptor. Simultaneous with the increase in diacylglycerol levels was an increase in membrane-bound protein kinase C enzyme activity. Immunoblotting with isoform-specific Abs against protein kinase C showed that, whereas the zeta-isoform is constitutively membrane bound, the alpha-isoform of protein kinase C is translocated to the membrane in response to IL-3. Activation of phosphatidylcholine hydrolysis and protein kinase C activation required both alpha- and beta-receptor subunits. To determine the relationship of tyrosine phosphorylation to the activation of phosphatidylcholine hydrolysis and protein kinase C translocation, we used the specific and structurally unrelated tyrosine kinase inhibitors genistein and herbimycin. Both inhibitors effectively blocked human IL-3-induced tyrosine phosphorylation. In addition, both inhibitors blocked phosphatidylcholine hydrolysis and protein kinase C translocation. These data, combined with our previous report showing that c-jun induction by IL-3 is dependent on protein kinase C, suggest that, in hematopoietic and nonhematopoietic cells expressing the human IL-3R, phosphatidylcholine hydrolysis and protein kinase C are downstream effectors of tyrosine phosphorylation in the IL-3 signal transduction cascade resulting in immediate early response gene induction.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine

Endoscopic ultrasonography in diagnosis and staging of pancreatic cancer.

The accuracy of endoscopic ultrasonography (EUS) for diagnosis of pancreatic cancers was evaluated in consecutive 232 patients with possible pancreatic cancer, and that for assessment of their locoregional spread was evaluated in 28 patients with pancreatic cancer subjected to pancreatectomy, in comparison with the accuracies of transabdominal ultrasonography (US) and computed tomography (CT). EUS was found to be significantly more accurate than US or CT and was especially useful for detecting small pancreatic cancers of less than 2 cm in diameter. With EUS, pancreatic cancers could be detected as a hypoechoic mass with a relatively unclear margin and irregular internal echoes. EUS was also more sensitive than CT and US for detecting venous and gastric invasions: it was more useful for detecting direct invasion of pancreatic cancers when the tumors were less than 3 cm in diameter. These findings indicate that EUS is an accurate method for diagnosis of pancreatic cancer and assessment of their locoregional spread and is particularly useful for detecting small tumors.

Endoscopy, Digestive System

Porto-hepatic venous shunt via portal vein aneurysm with splenomegaly.

A 59-year-old woman presented with consciousness disturbance with flapping tremor. Laboratory examinations revealed normal liver functions, and imaging studies, ultrasonography, magnetic resonance imaging, and angiography, showed portal vein aneurysm communicating from the portal vein to the hepatic vein, splenomegaly, and splenic artery aneurysm. These examinations confirmed porto-systemic shunt leading to hepatic encephalopathy. Porto-hepatic venous shunt via portal vein aneurysm is extremely rare, and there are few reports that it causes encephalopathy; therefore, little is known about the entity and this association. The literature in English is reviewed and the etiology, clinical features, and prognosis discussed.

Aneurysm

Liver with hypoechoic nodular pattern as a risk factor for hepatocellular carcinoma.

BACKGROUND/AIMS: Ultrasonography should be used for screening of hepatocellular carcinoma, but there are few reports on the relationship between liver ultrasonographic findings and the development of hepatocellular carcinoma (HCC). Using prospective follow-up studies, we examined the role of liver with a hypoechoic nodular pattern as a high-risk factor in HCC. METHODS: The study was performed by follow-up on 593 patients with chronic liver disease recorded at our hospital. The ultrasonographic pattern of the liver parenchyma was classified either as a small or large hypoechoic nodular pattern or as a nonnodular pattern. Patients were followed up from the time of initial ultrasonographic examination (1985-1987) until January 1, 1991. RESULTS: During the follow-up period (average, 4.2 years, range, 0.3-6.0 years), 62 patients were found to have HCC (12%). Patients whose livers showed small or large hypoechoic nodular pattern had a significantly higher risk of HCC than did patients whose livers showed a nonnodular pattern (rate ratios were 14.0 and 20.0, respectively, adjusted for age, sex, hepatitis virus markers, ICG R15, alpha-fetoprotein concentration, and ultrasonographic pattern of the liver). CONCLUSIONS: Liver showing a hypoechoic nodular pattern is a major risk factor in HCC.

Adult

In vivo effect of GroESL on the folding of glutamate racemase of Escherichia coli.

The overexpression of the murI (glr) gene, which encodes the glutamate racemase of Escherichia coli, resulted in the formation of inclusion bodies of the enzyme, and little activity was found in the soluble fraction of the transformant cells. The coexpression of the groESL gene with murI caused an in vivo solubilization of glutamate racemase in an active form. We isolated the active enzyme and purified it effectively.

Amino Acid Isomerases

Increased prevalence of HTLV-I infection in patients with hepatocellular carcinoma associated with hepatitis C virus.

The progression from chronic hepatitis C virus (HCV) infection to hepatocellular carcinoma (HCC) has been reported. We evaluated whether co-infection with the human T-lymphotropic virus type I (HTLV-I) might be associated with this transition in a cross-sectional analysis of 127 patients with HCV-chronic hepatitis (mean age = 51.7) and 43 patients with HCV-associated HCC (mean age = 62.4); the seroprevalence of anti-HTLV-I was 9.5% and 30.2%, respectively. For subjects 50 years or older, the seroprevalence of anti-HTLV-I in HCC patients was 13/41 (31.7%) which was significantly higher than that in chronic hepatitis patients (6/82, 7.3%) (P = 0.001). The relative risk (RR) of association was 12.8 (P = 0.0004) among the males, however, no association was evident among the females, RR = 1.3 (P = 0.80). The increased prevalence of HTLV-I positivity among the HCC cases could not be attributed to a higher rate of prior transfusion. These data suggest that co-infection with HTLV-I may contribute to the development of HCC among patients with HCV-induced chronic liver diseases in a highly HTLV-I-endemic area.

Adolescent