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T Tamura

Publications and source records attributed to T Tamura.

At least 307 records · Page 17Linked to original sources
PubMed1998

A T cell activation antigen, Ly6C, induced on CD4+ Th1 cells mediates an inhibitory signal for secretion of IL-2 and proliferation in peripheral immune responses.

A T cell activation antigen, Ly6C, is considered to be involved in the autoimmunity of some autoimmune-prone mice; however, the function of Ly6C remains largely unknown. We prepared a rat anti-mouse Ly6C monoclonal antibody (mAb) (S14) that inhibits the proliferation of peripheral T cells stimulated with anti-CD3 mAb in vitro. S14 mAb, the specificity of which is confirmed by a cDNA transfectant, recognizes Ly6C antigen preferentially expressed on a part of CD8+ T cells in peripheral lymphoid organs. The immunohistochemical analysis demonstrates that Ly6C appears on CD8+ T cells in the conventional T cell-associated area of BALB/c but not of nonobese diabetic (NOD) mice, confirming the absence of Ly6C+ T cells in NOD mice. Addition of soluble S14 mAb to the culture does not influence the proliferation of T cells in vitro; however, the S14 mAb coated on the plate clearly inhibits the proliferation and IL-2 production of anti-CD3-stimulated peripheral T cells. The T cells are arrested at the transitional stage from G0/G1 to S+G2/M phases, but they are not induced to undergo apoptotic changes in vitro. This inhibitory signal provided through the Ly6C molecule inhibited IL-2 secretion in a subpopulation of the activated CD4+ T cells. Ly6C is expressed on T cell clones of both Th1 and Th2 cells, but the cytokine secretion from Th1 clones is preferentially inhibited. These results suggest that Ly6C mediates an inhibitory signal for secretion of cytokines from Th1 CD4+ T cells, potentially causing the inhibition of immune response in peripheral lymphoid tissues.

Animals↗
PubMed1998

Correlation of myocyte lengthening to chamber dilation in the spontaneously hypertensive heart failure (SHHF) rat.

Chronic congestive heart failure of various etiologies is characterized by progressive chamber dilation. Although myocyte lengthening is involved, it is not known if this cellular change can account for all of the chamber dilation. The controversy is due largely to technical limitations in collecting data on chamber circumference, myocyte length, and sarcomere length simultaneously. To address this issue, the contributions of myocyte and sarcomere lengthening to progressive chamber dilation in spontaneously hypertensive heart failure (SHHF) rats was examined using a new approach. Female SHHF rats (n=31) were examined at various time points between 2 months of age and the onset of end-stage heart failure (18 months or older). A new method enabled simultaneous collection of data on myocyte length, sarcomere length, and chamber circumference using formalin-fixed tissue. Reliability of cellular measurements was confirmed with an alternate method. LV myocyte length increased linearly between 2 and 24 months of age due to series addition of sarcomeres. Myocyte length increased in direct proportion to chamber circumference during this period (r=0.93, P<0.001). Results suggest that myocyte lengthening alone can account for chamber dilation in the progression to heart failure. Excessive myocyte lengthening is a slow, progressive change that begins long before clinical signs and symptoms of heart failure appear in this model of hypertension and failure. Since myocyte remodeling in hypertensive humans with and without failure is known to resemble that in SHHF rats, these data should provide important insight into chamber dilation and the progression of heart failure in humans.

Animals↗
PubMed1998

Activation of a Ca2+-dependent K+ current by the oncogenic receptor protein tyrosine kinase v-Fms in mouse fibroblasts.

We investigated the effects of the receptor-coupled protein tyrosine kinase (RTK) v-Fms on the membrane current properties of NIH3T3 mouse fibroblasts. We found that v-Fms, the oncogenic variant of the macrophage colony-stimulating factor receptor c-Fms, activates a K+ current that is absent in control cells. The activation of the K+ current was Ca2+-dependent, voltage-independent, and was completely blocked by the K+ channel blockers charybdotoxin, margatoxin and iberiotoxin with IC50 values of 3 nM, 18 nM and 76 nM, respectively. To identify signalling components that mediate the activation of this K+ current, NIH3T3 cells that express different mutants of the wild-type v-Fms receptor were examined. Mutation of the binding site for the Ras-GTPase-activating protein led to a complete abolishment of the K+ current. A reduction of 76% and 63%, respectively, was observed upon mutation of either of the two binding sites for the growth factor receptor binding protein 2. Mutation of the ATP binding lobe, which disrupts the protein tyrosine kinase activity of v-Fms, led to a 55% reduction of the K+ current. Treatment of wild-type v-Fms cells with Clostiridium sordellii lethal toxin or a farnesyl protein transferase inhibitor, both known to inhibit the biological function of Ras, reduced the K+ current amplitude to 17% and 6% of the control value, respectively. This is the first report showing that an oncogenic RTK can modulate K+ channel activity. Our results indicate that this effect is dependent on the binding of certain Ras-regulating proteins to the v-Fms receptor and is not abolished by disruption of its intrinsic protein tyrosine kinase activity. Furthermore, our data suggest that Ras plays a key role for K+ channel activation by the oncogenic RTK v-Fms.

3T3 Cells↗
PubMed1998

Adenylate cyclases in keratinocytes: FRSK cells express types I, II, III, IV, VI and VIII, and 1,25(OH)2D3, retinoic acid and TPA augment forskolin-induced cyclic AMP accumulation in the absence of altered isozyme expression.

Molecular cloning analysis has detected at least nine adenylate cyclase isozymes in mammalian tissues. Using fetal rat skin keratinocytes (FRSK), we investigated adenylate cyclase expression and its modulation by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), a retinoid (Ro10-1670), and 12-O-tetradecanoylphorbol-13-acetate (TPA). Reverse transcription polymerase chain reaction (RT-PCR) indicated that FRSK contain adenylate cyclases I, II, III, IV, VI and VIII. Treatment with 1,25(OH)2D3 (1 x 10(-7) M), Ro10-1670 (1 x 10(-6) M), and TPA (100 ng/ml) resulted in increased forskolin-induced cyclic AMP accumulation by FRSK cells and normal human keratinocytes (NHK). Quantitative RT-PCR and Western blot analysis, however, detected no alteration in mRNA and protein levels of each adenylate cyclase isozyme for at least 48 h. These results indicate that FRSK contain at least six (I, II, III, IV, VI and VIII) adenylate cyclase isozyme mRNAs, suggesting a complex regulatory mechanism of cyclic AMP generation in keratinocytes. Although 1,25(OH)2D3, Ro10-1670, and TPA augmented forskolin-induced cyclic AMP accumulation, they do not seem to affect the expression of specific adenylate cyclase isozymes by FRSK cells.

Adenylyl Cyclases↗
PubMed1998

Lymphangioma of the jejunum and mesentery presenting with acute abdomen in an adult.

We describe a patient, 54-year-old woman, with lymphangiomas of the jejunum and mesentery presenting as acute abdomen. She had sudden onset of severe abdominal pain with guarding and fever. Physical examination revealed an elastic hard mass, with marked tenderness in the right abdominal region. Ultrasonography and computed tomography revealed a heterogenous mass, 20 x 15 x 8cm in size, in the mesentery. An emergency operation was performed with the diagnosis of diffuse peritonitis due to an inflammatory tumor in the mesentery. At operation, the tumor was found in the mesentery, adhering to a 60-cm segment of the jejunum. Multiple small tumors were seen in the submucosal layer of jejunum. The tumor was excised with a 60cm length of the jejunum. Histologically, the tumors were diagnosed as cavernous lymphangiomas. Although lymphangioma in the abdomen is rare in adults, we should consider it as one of the causes of acute abdomen.

Abdomen, Acute↗
PubMed1998

Ruptured distal anterior choroidal artery aneurysm presenting with casting intraventricular haemorrhage.

This report describes a rare case of a distal anterior choroidal artery aneurysm which developed intraventricular haemorrhage without subarachnoid haemorrhage as shown on computerized tomographic (CT) scan. A 69-year-old hypertensive man suddenly became unconscious. An emergency CT scan showed a severe intraventricular haemorrhage and a small round low-dense lesion within the haematoma at the right trigone. The haematoma with obstructive hydrocephalus made the lateral ventricles larger on the right than on the left. CT scan could not detect any subarachnoid haemorrhage. Right interal carotid angiography revealed a saccular aneurysm at the plexal point of the right anterior choroidal artery. We approached the aneurysm and the small round lesion through the trigone via a right temporo-occipital corticotomy. We could clip the aneurysmal neck and remove the intraventricular haematoma and the papillary cystic mass (corresponding to the small round lesion on CT scan) totally in one sitting. Histological examination revealed the aneurysm to be a true one and the papillary cystic mass to be a choroid plexus cyst.

Aged↗
PubMed1998

Plasma ferritin, premature rupture of membranes, and pregnancy outcome.

OBJECTIVE: The objective of this study was to determine whether plasma ferritin levels predict maternal or neonatal outcomes in women with preterm rupture of membranes at <32 weeks' gestation. METHODS: Plasma from 223 women with premature rupture of membranes at <32 weeks' gestation who had participated in a randomized antibiotic trial were analyzed for ferritin at random assignment and at delivery, and the results were compared with the development of clinical chorioamnionitis, latency until delivery, neonatal sepsis, and a composite adverse neonatal outcome variable. RESULTS: The mean plasma ferritin level rose from 19.2 +/- 29.1 microgram/L on admission to 38.3 +/- 54.3 microgram/L at delivery, with a mean latency of 9.3 +/- 14.6 days. Plasma ferritin levels were significantly higher at both times in mothers whose infants acquired sepsis than in those whose infants did not, especially at delivery (68.5 +/- 96.3 microgram/L vs 32.5 +/- 40.5 microgram/L, P =.01), and neonatal sepsis was 2 to 3 times more common among women with plasma ferritin levels above the median than among those with levels below the median. CONCLUSIONS: Among women with premature rupture of membranes at <32 weeks' gestation, plasma ferritin levels were significantly associated with neonatal sepsis. These data suggest that higher plasma ferritin levels may serve as a marker of infection among women with premature rupture of membranes; however, the clinical utility of plasma ferritin levels in predicting neonatal outcome appears limited.

Adult↗
PubMed1998

Serum leptin concentrations during pregnancy and their relationship to fetal growth.

OBJECTIVE: To test the hypothesis that maternal and cord serum leptin concentrations correlate with birth weight of infants. METHODS: Pregnant women (n = 135) of low socioeconomic status who delivered full-term infants were selected from more than 1500 women who participated in a study to identify factors related to fetal growth restriction (FGR). They were divided into two groups based on their infants being classified as having FGR (n = 66) or not (n = 69), and each group was divided further into three subgroups based on prepregnancy body mass index (BMI): less than 19.8, 19.8-28.9, and 29 or more. Sample estimations indicated that 20 subjects per subgroup would be adequate to detect 50% difference in leptin concentrations. RESULTS: Mean maternal serum leptin concentrations adjusted for BMI were highest at approximately 22-27 weeks' gestation (29.8 ng/mL) and declined thereafter until term (25.2 ng/mL). Leptin concentration and prepregnancy BMI correlated significantly. We found neither significant difference in leptin concentrations between the subjects with and without FGR infants nor significant correlation between maternal leptin concentrations and birth weight of infants. Mean cord serum leptin concentration (10.8 ng/mL) was lower than maternal concentrations and correlated significantly with birth weight (r = .61, P < .001). CONCLUSION: Our findings suggest that maternal leptin concentration during pregnancy is not an accurate indicator of fetal growth. Cord serum leptin concentrations were lower than maternal serum concentrations and correlated significantly with birth weight.

Adult↗
PubMed1998

Prenatal plasma matrix metalloproteinase-9 levels to predict spontaneous preterm birth.

OBJECTIVE: Matrix metalloproteinase-9, a zinc-dependent proteinase, may be important in initiating labor or rupture of membranes. We determined plasma levels of this enzyme in nonpregnant and pregnant women and evaluated whether they predict spontaneous preterm delivery. METHODS: A sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure matrix metalloproteinase-9 levels in plasma samples from 25 nonpregnant women (mean age 39+/-9 years) and in stored plasma samples obtained during a randomized trial of zinc supplementation in pregnancy. Women were selected who delivered following spontaneous labor or premature rupture of membranes at 24-32 weeks (n = 20), 33-36 weeks (n = 29), and greater than 37 weeks (n = 30). Plasma samples were obtained sequentially at 19, 26, 31, and 36 weeks if undelivered and at presentation for delivery. RESULTS: Plasma matrix metalloproteinase-9 levels for non-pregnant women averaged 18.6+/-11.2 (mean +/- standard deviation) ng/mL. Prenatal values averaged 298+/-227 ng/mL from 19 weeks until 36 weeks (not including presentation for delivery) and did not change significantly as the gestational age increased, regardless of whether women ultimately delivered at 24-32, 33-36, or after 37 weeks. Values obtained prior to, but within 1 week of, presentation for delivery (n = 7, 281+/-103 ng/mL) were not significantly different than those obtained earlier in pregnancy (n = 71, 309+/-307 ng/mL, [P = .60]). Plasma matrix metalloproteinase-9 levels for women in spontaneous labor were similar regardless of gestational age and were increased three-fold (852+/-301 ng/mL) compared with those drawn at each prenatal visit (for example, 26 week values = 285+/-144 ng/mL [P < .001]). CONCLUSION: Plasma matrix metalloproteinase-9 levels remain unchanged throughout pregnancy until the onset of spontaneous labor when there is a three-fold increase. Plasma matrix metalloproteinase-9 levels obtained prior to presentation for delivery do not appear to predict spontaneous preterm birth.

Adult↗
PubMed1998

Sasanquol, a 3,4-seco-triterpene alcohol from sasanqua oil, and its anti-inflammatory effect.

A novel 3,4-seco-triterpene alcohol, named sasanquol, was isolated from the non-saponifiable lipid of sasanqua oil from the seeds of Camellia sasanqua. Its structure was established to be 3,4-seco-D:B-friedobacchara-4,21-dien-3-ol by spectroscopic methods. This is the first example of naturally occurring triterpene with a D:B-friedobaccharane skeleton. The 50% inhibitory dose of this compound against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear inflammation (1 microgram per ear) in mice was 0.4 mg per ear.

Animals↗
PubMed1998

Measurement of cytokines in the cavernous sinus plasma from patients with Cushing's disease.

In order to know more about the in vivo secretion of various cytokines from the human pituitary, this study measured the concentrations of interleukin (IL)-1alpha, IL-1beta, IL-2, IL-6, tumor necrosis factor-alpha and IL-1 receptor antagonist (ra) in both the peripheral blood and the cavernous sinus (CS) plasma from six patients with Cushing's disease before and after an intravenous bolus injection of human corticotropin-releasing hormone (CRH, 100 microg). As a routine procedure for the diagnosis of Cushing's disease, adrenocorticotropin (ACTH) levels were also determined in the same samples. In four of the six patients, unstimulated levels of IL-1ra in the CS ipsilateral to the ACTH-secreting adenoma were higher than those in the peripheral blood, with a ratio of > or = 1.5:1, even though CRH was without effect on the cytokine's concentration in the CS. In contrast, no consistent data were obtained for any of the remaining five cytokines. These results demonstrate for the first time that the in vivo release of IL-1ra is detectable in at least some corticotroph adenomas, and also suggest a possible role of the cytokine in physiological and pathophysiological processes occurring in the human pituitary.

Adolescent↗
PubMed1998

Establishment of a serum-free culture cell line, CPK-NS, which is useful for assays of classical swine fever virus.

A stable porcine kidney cell line, CPK-NS, was established and maintained in serum-free culture. A cytopathic effect (CPE) was observed clearly in CPK-NS cells infected with some classical swine fever virus (CSFV) strains which did not show the exaltation of Newcastle disease virus (END) phenomenon. Chromosome condensation and DNA fragmentation, a marker for apoptosis, were detected in cells infected with END phenomenon-negative CSFV strains. By using the CPE induced by infection with an END phenomenon-negative CSFV strain in CPK-NS cells, assays of CSFV were established. The virus titer determined in CPK-NS cells shows a high correlation with the usual peroxidase-linked assay, dome disappearance method and END method. Furthermore, the antibody titer by neutralizing test with CPK-NS cells also correlated with that measured by the usual neutralizing peroxidase-linked assay and dome disappearance method. These stable CPK-NS cells have the great advantage that a clear CPE was caused by infection with END phenomenon-negative CSFV strains and bovine serum is not necessary for cell culture and virus assays.

Animals↗
PubMed1998

Dilution is effective in reducing infusion phlebitis in peripheral parenteral nutrition: an experimental study in rabbits.

To clarify conflicting clinical results that had been reported as to whether dilution is effective or not in reducing infusion phlebitis, this study was undertaken. We undertook two experiments with the different infusion conditions in rabbits to confirm the generality and the reproducibility of the results. To test the effect of dilution, 120 mL/kg of solution A (784 mOsm/kg) was infused into rabbit ear veins at 10 mL.kg-1.h-1 for 12 h, and 144 mL/kg of 1.2-fold-diluted solution A (648 mOsm/kg) was infused at 12 mL.kg-1.h-1 for 12 h. Similarly, 120 mL/kg of solution B (718 mOsm/kg) was infused at 5 mL.kg-1.h-1 for 24 h, and 168 mL/kg of 1.4-fold-diluted solution B (514 mOsm/kg) was infused at 7 mL.kg-1.h-1 for 24 h. The infused veins were sampled 24 h after the end of the infusion and examined histopathologically. After the 12-h infusion, phlebitic changes were observed in six of eight rabbits given solution A but in only one of eight rabbits given diluted solution A, although the same quantities of the same nutrients were infused. Also, after the 24-h infusion, phlebitic changes were observed in six of eight rabbits given solution B but in no animals given diluted solution B. The same result that dilution reduced or eliminated phlebitic changes was confirmed in the different conditions. These results suggest that osmolality of the infusion solution is an important factor in the development of phlebitis regardless of infusion volume or infusion rate and that dilution is effective in reducing the phlebitic potential of infusion solutions.

Animals↗
PubMed1998

Functional alteration of guanine nucleotide binding proteins (Gs and Gi) in psoriatic epidermis.

Psoriatic involved epidermis has been characterized by a defective beta-adrenergic adenylate cyclase response. It is also characterized by increased cholera toxin- and forskolin-induced cyclic AMP accumulations. Due to the fact that receptor signals are transduced to adenylate cyclase through guanine nucleotides binding proteins (G-proteins), that affect cholera toxin- and forskolin-induced cyclic AMP accumulations, possible alterations of G-proteins of psoriatic involved and perilesional uninvolved epidermis by using toxin-catalyzed ADP-ribosylation and immunoblot analyses was investigated. Cholera toxin catalyzes ADP-ribosylation of stimulatory guanine nucleotides binding protein (Gs) in either trimeric (inactive) or monomeric (active) form, while islet activating protein (IAP) catalyzes ADP ribosylation of inhibitory guanine nucleotide binding protein (Gi) in only trimeric (inactive) form. Results indicate that although the psoriatic involved epidermis shows increased cholera toxin- and IAP-catalyzed ADP-ribosylations, the amounts of immunoreactive Gs alpha or Gi alpha are not significantly altered. The increase in IAP-catalyzed ADP-ribosylation indicates increased inactive Gi, explaining the increased forskolin-induced cyclic AMP accumulation. The increase in cholera toxin-catalyzed ADP-ribosylation of Gs explains the increased cholera toxin-induced cyclic AMP accumulation in the psoriatic involved epidermis.

Adenosine Diphosphate Ribose↗
PubMed1998

Oncogenic Ras modulates epidermal growth factor responsiveness in endometrial carcinomas.

Since the majority of endometrial carcinomas do not contain any detectable ras mutations, the precise contribution of aberrant Ras function, if any, to endometrial carcinoma development remains to be determined. Since there is considerable evidence that Ras transformation is associated with a decreased requirement for growth factors, we compared the growth response of endometrial carcinoma cells harbouring wild-type (Ishikawa cells) or mutated (HHUA cells) K-ras to epidermal growth factor (EGF). K-ras mutation did not significantly affect the level of the EGF receptor (EGFR) expressed in these carcinoma cells. EGF could stimulate the growth of Ishikawa, but not HHUA cells. Furthermore, EGF caused elevation of Ras-GTP levels in Ishikawa, but not HHUA cells. However, the introduction of mutated, but not normal, K-ras into Ishikawa cells rendered them non-responsive to EGF growth stimulation. Thus, the presence of mutated K-ras alone modulated the growth response of endometrial carcinoma cells to EGF. An inhibitor of the EGFR tyrosine kinase activity could prevent soft agar colony formation of Ishikawa cells, but not HHUA or mutant K-ras(12V)-transfected Ishikawa cells. Taken together, these results suggest that mutated K-ras causes a loss of responsiveness to EGF stimulation and that EGFR function is dispensable for the growth of mutant Ras-positive endometrial carcinoma cells.

Apoptosis↗
PubMed1998

Expression of exon 5 deleted estrogen receptor variant messenger RNA in human uterine myometrium and leiomyoma.

To examine the relationship between uterine leiomyoma, an estrogen-dependent tumor and its estrogen receptor, the relative amounts of wild type estrogen receptor (WT) mRNA and exon 5 deleted estrogen receptor variant (D5-ER) mRNA to G3PDH mRNA were examined in human uterine myometrium and leiomyoma specimens obtained from 46 patients in 3 age groups (group A: 41-45 years old, group B: 46-50 years old, group C: 51-54 years old) using a quantitative reverse transcription polymerase chain reaction method (RT-PCR). D5-ER mRNA was co-expressed with WT mRNA in all myometrium and leiomyoma specimens. In myometrium, the relative amount of WT decreased with aging, but in leiomyoma, it was high in group B. The relative amount of D5-ER mRNA and the ratio of D5-ER mRNA to WT mRNA (D5/WT ratio) were significantly higher in group C in both myometrium and leiomyoma. The percentage of the patients whose D5/WT ratio was higher in leiomyoma than in myometrium (L/M ratio>1.0) increased with age. These findings suggest that D5-ER increases to supplement the decreasine in WT in uterine tissues toward menopause and that D5-ER plays a more active role in leiomyoma than in myometrium during the perimenopausal period.

Adult↗