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T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 415 records · Page 23Linked to original sources
PubMed1998

Effect of contrast on the perception of moving multiple Gabor patterns.

The present study examined the way in which the perception of motion coherency depends on luminance contrast. Pseudo-plaid patterns were presented to subjects who judged whether coherent motion or component motion of the Gabor patterns was perceived. Michelson contrast, eccentricity, spatial separation, and angular separation between two groups of Gabor patches were varied systematically. When the contrast was high, coherent motion perception was dominant in peripheral viewing but not in foveal viewing. When the contrast was low, coherent motion was perceived at all eccentricities. Under low-contrast conditions and with peripheral viewing, coherent motion was perceived over broader spatial areas and at wider angular separations. The contrast dependency of motion coherency can be qualitatively explained in terms of the relative activity of hypothetical local-motion units in area V1 and global-motion units in area MT of the visual cortex.

Contrast Sensitivity↗
PubMed1998

Postnatal development of EEG patterns, catecholamine contents and myelination, and effect of hyperthyroidism in Suncus brain.

The postnatal development of the central nervous system (CNS) in house musk shrew in the early stage of maturation was studied. The electroencephalogram (EEG) and visual evoked potential (VEP) in association with catecholamine contents and myelin basic protein (MBP) immunoreactivity were carried out from the 1st to the 20th day of postnatal age. Different EEG patterns which were specific to behavioral states (awake and drowsy) were first recorded on the 5th day, and the total power which was obtained by power spectrum analysis increased after this stage. The latencies of all peaks in VEP markedly shortened between the 5th and the 7th day. Noradrenalin (NA) content of the brain showed a slight increase after the 3rd day, and reached maximum levels on the 7th day, which was delayed a few days compared to dopamine (DA). In hyperthyroidism, the peak latency of VEP was shortened and biosynthesis of NA in cerebral cortex and DA in hippocampus was accelerated. The most obvious change in MBP-immunoreactivity of the telencephalon occurred from the 7th to the 10th day. These morphological changes in the brain advanced at the identical time-course to those in the electrophysiological development and increment of DA and NA contents.

Aging↗
PubMed1998

Osteoclast-like giant cell tumor of the pancreas with metastases to gallbladder and lymph nodes. A case report.

Osteoclast-like giant cell tumor of the pancreas (OGTP) is a rare neoplasm, of which the histogenesis is still controversial. Here we report a case of OGTP involving the head of the pancreas in a 71-year-old woman with metastases to the gallbladder and lymph nodes. The primary and metastatic tumors had identical histopathological, immunohistochemical, ultrastructural and molecular biological features. Microscopically, the tumors were characterized by atypical, often pleomorphic mononuclear cells associated with the proliferation of benign-appearing osteoclast-like giant cells (OGCs). Electron microscopic observation provided ultrastructural evidence of epithelial differentiation of the mononuclear cells, including microvilli and desmosomes, which was not obtained for OGCs. On immunohistochemical study, OGCs stained for CD68 (KP-1), LCA and HAM56, whereas mononuclear cells only reacted with PCNA. These findings clearly suggest that mononuclear cells are capable of differentiation and proliferation and may have been the only true tumor cells in this neoplasm, and that OGCs may have been a paraneoplastic product of this rare tumor. On examination of DNA from dewaxed sections of the tumor, we found no p53 mutation in the tumor tissue, but found two K-ras mutations in codon 12; this pattern of mutation commonly occurs in pancreatic carcinoma, indicating a somewhat genetic relationship of OGTP to pancreatic carcinoma. Although OGTP often has a favorable prognosis, the outcome in the present case was poor due to early tumor spread, with less than two years postoperative survival.

Aged↗
PubMed1998

Effects of homologous natriuretic peptides in isolated skin of the bullfrog, Rana catesbeiana.

The effects of frog atrial (fANP), brain (fBNP) and C-type natriuretic peptide (fCNP) on transepithelial ion transport were investigated in the bullfrog, Rana catesbeiana. The transepithelial potential difference (PD) and short-circuit current (Isc) of the abdominal skin were measured according to the technique of Ussing and Zerahn. When the abdominal skin was exposed to homologous natriuretic peptides (NPs) at concentrations ranging from 4 x 10(-13) to 5 x 10(-7) M, no significant changes in PD or Isc were observed. The influence of the NPs on the arginine vasotocin (AVT)-induced increase in Isc was then examined. Treatments with ANP and BNP (4 x 10(-9)-4 x 10(-8) M) inhibited the increase in the AVT (10(-8) M)-induced Isc. Furthermore, fCNP I and fCNP II (5 x 10(-13)-5 x 10(-7) M) did not significantly inhibit the increase in the AVT-induced Isc. The cyclic GMP analog, 8-BrcGMP, (> 10(-4) M) with AVT inhibited the increase of AVT-induced ISc, as well as fANP and fBNP. HS-142-1, an inhibitor of particulate guanylyl cyclase, (10(-5) g ml-1) significantly reduced the inhibitory action of fANP on the increase of AVT-induced Isc. These results suggest that fANP and fBNP act through the guanylyl cyclase systems to increase cellular cGMP and modulate AVT-induced epithelial transport in a concentration-dependent manner. It is also suggested that fCNPs have no effect on the natriferic response in the skin of the bullfrog.

Animals↗
PubMed1998

Diagnosis of measles viral pneumonia in a patient with Hodgkin's disease by reverse transcription-polymerase chain reaction of serum.

We report a case of fatal measles viral pneumonia in a patient with Hodgkin's disease who had no rash. The measles viral cDNA was detected in autopsy tissue from the lung by reverse transcription-polymerase chain reaction. This method was then applied successfully to stored serum. The diagnosis of measles viral pneumonia may be improved by the application of RT-PCR using peripheral blood. Sequence analysis of amplified cDNA suggested the virus infecting this patient was a recent strain, predominantly isolated after 1980. The fatal outcome may have been due to a lack of immune response to the newer strain.

Aged↗
PubMed1998

Pranidipine, a new 1,4-dihydropyridine calcium channel blocker, enhances cyclic GMP-independent nitric oxide-induced relaxation of the rat aorta.

Pranidipine, a new calcium channel blocker, prolonged endothelium-dependent relaxation induced by acetylcholine in an aortic ring preparation, contracted with prostaglandin F2alpha. This action was not shared by amlodipine. The effect was not modified by indomethacin, suggesting that the action of pranidipine does not involve prostanoid metabolism. N(G)-nitro-L-arginine completely prevented the action of Pranidipine. The drug affected neither nitric oxide (NO) synthase activity nor the level of cyclic GMP in the vessel. Pranidipine did not affect the sensitivity of the contractile proteins to calcium. Pranidipine also did not alter cyclic GMP-induced relaxation in alpha-toxin-skinned vascular preparations. Pranidipine also prolonged glyceryl trinitrate-induced relaxation in the endothelium denuded rat aorta. Furthermore, pranidipine enhanced relaxation of the aorta induced by glyceryl trinitrate even in the presence of methylene blue, a guanylyl cyclase inhibitor. This action was not modified by iberiotoxin or by charybdotoxin, two inhibitors of the calcium-activated potassium channel. The results strongly suggest that pranidipine enhances cyclic GMP-independent NO-induced relaxation of smooth muscle by a mechanism other than through NO-induced hyperpolarization. These effects were in direct contrast to amlodipine, another new 1,4-dihydropyridine calcium antagonist.

Amlodipine↗
PubMed1998

Regulatory mechanism of pepsinogen gene expression in monolayer cultured guinea pig gastric chief cells.

We have investigated the effects of dibutyryl cAMP, forskolin, carbamylcholine chloride (carbachol), ionomycin, and 12-O-tetradecanoylphorbol-13-acetate (TPA) on the expression of guinea pig pepsinogen mRNA in monolayer cultured gastric chief cells. After exposure of the cells to each of these compounds for 4 to 24 hr, and at 48 hr after primary culture, total cellular RNA was isolated using acid guanidium-phenol-chloroform and then was reverse transcribed to cDNA. Obtained cDNA was amplified by polymerase chain reaction (PCR) using primers detecting guinea pig pepsinogen mRNA and human beta-actin mRNA as an internal standard. The PCR products were separated and quantified using capillary electrophoresis. Dibutyryl cAMP and forskolin significantly increased pepsinogen mRNA, but carbachol, ionomycin, and TPA failed to increase that. These findings suggested that pepsinogen gene expression was up-regulated by intracellular cAMP, but not by intracellular calcium or protein kinase C in guinea pig chief cells.

Animals↗
PubMed1998

Trichomonas foetus meningoencephalitis after allogeneic peripheral blood stem cell transplantation.

A 34-year-old man with refractory acute myelogenous leukemia underwent allogeneic peripheral blood stem cell transplantation (PBSCT) from his HLA-matched sibling. Engraftment was prompt and no acute GVHD developed. However, high fever persisted even after engraftment, and the patient developed headache, diplopia, vertigo and nuchal rigidity on day 20 posttransplant. Cerebrospinal fluid (CSF) showed pleocytosis with no detectable microorganisms. Despite therapy with broad-spectrum antibiotics, antifungal agents and antituberculous drugs, he developed rapid mental deterioration with seizures and died on day 40. Just prior to his death, trichomonads were isolated from both CSF and urine. Scanning electron microscopic examination identified the trichomonad as Trichomonas foetus. At autopsy, trichomonads were detected histopathologically in an area involving meningoencephalitis. To our knowledge, this is the first case of T. foetus meningoencephalitis in a recipient of allogeneic PBSCT and, more importantly, the first human case of T. foetus infection.

Adult↗
PubMed1998

Regulatable production of insulin from primary-cultured hepatocytes: insulin production is up-regulated by glucagon and cAMP and down-regulated by insulin.

To utilize hepatocytes for insulin-producing surrogate cells, we devised a regulatory secretion system by placing proinsulin DNA under the regulatable promoter for phosphoenolpyruvate carboxykinase (PEPCK). The expression of PEPCK is down-regulated by insulin, and up-regulated by cAMP and glucagon. To express insulin in hepatocytes, we constructed an adenoviral insulin expression system. After infection, the hepatocytes secreted immunoreactive insulin (IRI) at an increasing rate. IRI secretion increased over four-fold upon stimulation with 300 microM cAMP and 500 microM of the cAMP-dependent phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). This increase was also observed with glucagon and IBMX. Production was augmented two-fold by the addition of wortmannin, phosphatidylinositol (PI)-3-kinase inhibitor, suggesting that inhibitory insulin signaling to the PEPCK promoter may be mediated through PI-3-kinase. Addition of exogenous insulin to the culture decreased insulin mRNA expression remarkably on Northern blot. Thus, by using a PEPCK promoter for insulin expression, we were able to up-regulate insulin production from hepatocytes with cAMP and glucagon, and down-regulate with insulin itself.

1-Methyl-3-isobutylxanthine↗
PubMed1998

A histopathological study of the morphological changes at the apical seat and in the periapical region after irradiation with a pulsed Nd:YAG laser.

In this study, the effects of pulsed Nd:YAG laser irradiation on the apical seat and periapical region of instrumented root canals were investigated. One hundred and ninety-two teeth, including incisors and molars (239 root canals), in 18 healthy adult beagle dogs were used. After extirpation of the pulp under anaesthesia, each root canal was shaped up to at least a size 40 K-file, and then laser irradiated using the following parameters: 1 W, 15 pps for 2, 3, and 4 s; 2 W, 15 pps for 2 s. The effectiveness of debris removal and carbonization on the root canal walls immediately laser irradiation were examined and inflammation of the periapical region at 1, 2, and 4 weeks after laser irradiation was examined using light microscopy. Effective debris removal was observed in most cases in the laser-treated groups and was dependent on irradiated energy. Carbonization was observed in the irradiated root canals except at the parameter of 1 W for 2 s. Periapical inflammation was observed at 1 W for 2 s to the same extent as in the control group (P > 0.01). These results suggest that the pulsed Nd:YAG laser is useful for debris removal with no adverse effects immediately after extirpation of the pulp if appropriate parameters are selected.

Aluminum Silicates↗
PubMed1998

Immunohistochemical study of Fas, Fas ligand and interleukin-1 beta converting enzyme expression in human prostatic cancer.

OBJECTIVE: To determine the cellular expression of Fas, Fas ligand and interleukin-1 beta converting enzyme (ICE) in prostatic cancer. PATIENTS AND METHODS: Specimens of prostate were obtained from 21 patients (mean age 66 years, SD 5) undergoing radical prostatectomy for prostatic cancer. Nine of the 21 patients had received endocrine therapy before surgery. Specimens were also obtained from 10 patients with benign prostatic hypertrophy (BPH) and during autopsy from 10 patients who had died from hormone-unresponsive prostate cancer. Paraffin-embedded sections were cut from the specimens and stained immunohistochemically to detect Fas, Fas ligand and ICE. RESULTS: Fas was expressed in all 21 of the cancer specimens while Fas ligand was detected in none and ICE was expressed in 11. The difference between the expression of Fas and ICE was significant (P < 0.001). ICE was expressed in nine of 12 patients who were untreated before surgery and in two of nine treated with endocrine therapy (P < 0.05). Fas expression was detected in the specimens from all 10 patients with BPH and in all 10 autopsy specimens; the expression, tended to be more marked than that in specimens from total prostatectomy (P < 0.1). CONCLUSION: The expression of ICE was weaker than that of Fas in the total prostatectomy specimens, suggesting a possible interruption of the apoptotic signalling pathway. Prostates with BPH and hormone-unresponsive cancer therefore showed no appreciable change in Fas expression when compared with total prostatectomy samples.

Aged↗
PubMed1998

Proliferation and cellular kinetics of villous epithelial cells and M cells in the chicken caecum.

The proliferation sites and cellular kinetics of villous epithelial cells and M cells in the intestine of the adult chicken have never been clarified. In this study, we determined the proliferation sites in the chicken caecum using colchicine treatment and detection of proliferative cell nuclear antigen (PCNA). The cellular kinetics of these cells were also studied using bromodeoxyuridine (BrdU) as a tracer. Enterocytes in their mitotic period were observed along the entire length of the intestinal crypt of the caecum, with a denser distribution in the middle portion of the crypt, except for the caecal tonsil. The centres of distributions were at 49% of the distance from the bottom of the crypt in the base and 41% in the apex of the caecum. In the caecal tonsil, the centres of distributions were at 64% in the long type of crypt from the bottom of the crypt and at 44% in the short type of crypt. On the other hand, the PCNA-positive enterocytes were distributed more densely at the bottom of the crypt, except for the caecal tonsil. The centres of distributions were at 36% in the base from the bottom of the crypt, 37% in the body, and 34% in the apex. In the caecal tonsil, they were at 54% in the long type of crypt and 44% in the short type. The BrdU-labelled enterocytes reached to the basement of the intestinal villi in all caecal portions at 1 d after the BrdU administration. The leading edge of the labelled enterocytes disappeared from the villous tips at 4 d in the base and the body and 3 d in the apex. In the caecal tonsil, the BrdU-labelled microvillous epithelial cells and the M cells appeared near the orifice of the crypt at 1 d, and BrdU-labelled M cells were not observed in the crypt. Thereafter, almost all of these cells disappeared at 5 d from the follicle associated epithelium (FAE). These results suggest that M cells are transformed from their precursors within 1 d, and the turnover time for M cells occurs within 4 d after the cell division of the precursors.

Animals↗
PubMed1998

A novel in vivo model for evaluating agents that protect against ultraviolet A-induced photoaging.

Increasing evidence demonstrates that ultraviolet A radiation (UVA) contributes to photoaging, which results in the accumulation of massive amounts of abnormal elastic material in the dermis of photoaged skin. To study UVA-induced photoaging in an in vivo system, we utilized a line of transgenic mice containing the human elastin promoter linked to a chloramphenicol acetyl transferase reporter gene. Our prior work demonstrates promoter activation in response to ultraviolet B radiation (UVB), UVA, and psoralen plus ultraviolet A radiation in the skin of these mice. The addition of psoralen (8-MOP) prior to administration of UVA results in substantial increases in promoter activation, as compared with UVA alone. To demonstrate the utility of these mice as a model of UVA-induced photodamage, we administered four lotions to the skin of our transgenic mice that included: a sunscreen containing octyl methoxycinnamate and benzophenone-3 with a sun protection factor (SPF) of 15, the UVA filter butyl methoxydibenzoylmethane, the SPF 15 sunscreen and the UVA filter together, and the lotion vehicle alone. Following sunscreen administration, mice received a single psoralen plus ultraviolet A radiation treatment. All sunscreens decreased chloramphenicol acetyl transferase activity with the SPF 15 sunscreen, the UVA filter, and the combination SPF 15 sunscreen and UVA filter, resulting in increasing degrees of protection against psoralen plus ultraviolet A radiation. These results demonstrate that this model functions as a rapid and sensitive model of UVA photodamage for the identification and comparison of compounds that protect against UVA-induced photoaging.

Animals↗
PubMed1998

Correlation of epidermal growth factor receptor and radiosensitivity in human maxillary carcinoma cell lines.

To determine the relationship between epidermal growth factor receptor (EGFR) and radiosensitivity, we immunostained cells from three maxillary carcinoma cell lines with an anti-EGFR antibody. The intensity of staining reactivity, determined by means of an image analysis system, was expressed as grey value (0-black to 255-white). The mean grey values for cell lines IMC-2, IMC-3, and IMC-4 were 181, 210, and 222, respectively, and differed significantly (p < 0.001). This indicates that IMC-2 had the highest number of EGFR, followed by IMC-3 and IMC-4. The cells were then irradiated at 1, 2, 4, or 6 Gy, and cell survival was assessed by means of a standard colony-forming assay. IMC-2 had the highest survival rates at 1, 2 and 4 Gy, followed by IMC-3 and IMC-4. Therefore, the survival rates for IMC-2, IMC-3, and IMC-4 after irradiation increased in proportion to the amount of EGFR in each cell line. These results support the findings of previous clinical studies which showed that increased expression of EGFR was associated with higher recurrence rates of glottic and maxillary sinus carcinoma in patients treated with radiation therapy. The amount of EGFR in cells may therefore be associated with their radiosensitivity.

Carcinoma, Squamous Cell↗
PubMed1998

Pulsed Nd:YAG laser application to one-visit treatment of infected root canals in dogs: a histopathological study.

OBJECTIVE: In this study, the effects of pulsed Nd:YAG laser irradiation during root canal treatment of infected teeth were investigated histopathologically in dogs. SUMMARY BACKGROUND DATA: Effects of Nd:YAG laser on infected root canal treatment have not been reported in vivo. METHODS: One hundred thirty-five teeth with a single root, including incisors and premolars, in 15 healthy adult beagle-strain dogs were used in this study. After inducing infection in the teeth, each root canal was shaped with at least a # 40 K-file, then the canal was irradiated using the following parameters: 1 W, 30 pps for 1 and 2 sec; 2 W, 30 pps for 1 and 2 sec. Efficacy of debris removal and evaporation on the root canal walls at 2 weeks, and the degree of inflammation of the periapical region at 2, 4, and 8 weeks after laser irradiation were examined histopathologically by light microscopy. RESULTS: Effective debris removal was observed in all cases of the laser-treated groups. No evaporation was observed except at the conditions of 2 W for 2 sec. Inflammation of periapical region in the laser-treated groups was similar in the control group at 2 weeks, but was significantly less than that in the control group at 8 weeks (p < 0.05). CONCLUSION: These results suggest that pulsed Nd:YAG laser is useful for one-visit root canal treatment of infected teeth in dogs, if appropriate parameters are selected, and this is a potential therapy for human apical lesions of teeth.

Animals↗