Biomedical subjects

T Murakami

Publications and source records attributed to T Murakami.

At least 415 records · Page 23Linked to original sources

PubMed1999

Focal hepatic lesion detection: comparison of four fat-suppressed T2-weighted MR imaging pulse sequences.

PURPOSE: To evaluate fat-suppressed T2-weighted magnetic resonance (MR) imaging with conventional spin-echo (SE), breath-hold fast SE, respiratory-triggered fast SE, and breath-hold multishot SE echo-planar sequences for the detection of focal hepatic lesions. MATERIALS AND METHODS: Fat-suppressed T2-weighted MR images obtained with the four sequences in 55 patients with 81 solid and 129 nonsolid lesions were retrospectively analyzed. Image review was conducted on a segment-by-segment basis; a total of 440 liver segments were reviewed separately for solid and nonsolid lesions by three independent radiologists. Diagnostic accuracy was evaluated with receiver operating characteristic analysis. RESULTS: The mean lesion-to-liver contrast-to-noise ratio was highest on the multishot SE echo-planar images of both solid and nonsolid lesions. Fat-suppressed respiratory-triggered fast SE images had significantly better (P < .05) or comparative detectability of both solid and nonsolid lesions compared with the other types of images. Image quality was best on the respiratory-triggered fast SE images. CONCLUSION: Fat-suppressed respiratory-triggered fast SE imaging should replace fat-suppressed conventional SE imaging as a standard T2-weighted imaging examination in the detection of focal hepatic lesions.

Adipose Tissue↗

PubMed1999

Pancreatic CT imaging: effects of different injection rates and doses of contrast material.

PURPOSE: To assess the effects of the intravenous injection rate and dose of contrast material on pancreatic computed tomography (CT). MATERIALS AND METHODS: A total of 126 patients were divided at random into four groups with different injection rates and doses. Groups 1 and 2 underwent injection of 2 mL per kilogram of body weight of 300 mg of iodine per milliliter of contrast material, and groups 3 and 4 underwent injection of 1.5 mL/kg. The injection rate was 5 mL/sec for groups 1 and 3 and 3 mL/sec for groups 2 and 4. Single-level serial CT scanning was performed at the level of the pancreatic head, and the pancreatic enhancement value was calculated. RESULTS: The maximum pancreatic enhancement value was 99 HU +/- 18 (mean +/- SD) for group 1, 90 HU +/- 18 for group 2, 86 HU +/- 15 for group 3, and 74 HU +/- 13 for group 4. There were significant differences in the maximum pancreatic enhancement value between groups 1 and 2 (P = .045), between groups 3 and 4 (P = .001), between groups 1 and 3 (P = .016), and between groups 2 and 4 (P = .001). CONCLUSION: Both a higher dose and a faster injection rate increased the maximum pancreatic enhancement value.

Adult↗

PubMed1999

Overexpression of p53 protein associated with proliferative activity and histological degree of malignancy in solar keratosis.

BACKGROUND: Overexpression of p53 protein has frequently been demonstrated in human epithelial neoplasms including squamous cell carcinoma (SCC) and solar keratosis (SK). SK is a precursor lesion of SCC. In SCC of the skin, we have already reported that overexpression of p53 protein is associated with the proliferative activity, which is indicated by the percentage of Ki-67-positive cells. In SK, however, the significance of p53 overexpression is still unclear. OBJECTIVE: The aim of the present study was to clarify the relationship between p53 overexpression and proliferative activity, and between p53 overexpression and histological degree of malignancy in SK. METHODS: Sixty-eight cases of SK were divided into four grades according to the proportion of atypical cells in the epidermis (in grade I, up to 25% of the epidermal cells are atypical, in grade II 25-50%, in grade III 50-75%, in grade IV more than 75%) and were immunohistochemically analyzed for the expression of p53 protein and Ki-67 antigen. RESULTS: p53 overexpression was detected in 58 out of the 68 cases of SK. The percentage of p53-protein-positive cells (DO-7 index) ranged from 0 to 78.8 (mean +/- SD = 20.6 +/- 21.6). Mean DO-7 indices were 7.9 in grade I, 26.7 in grade II and 38.3 in grade III. The differences in mean DO-7 index between grades I and II and between grades I and III were statistically significant (p < 0.001). The percentage of Ki-67-antigen-positive cells (MIB-1 index) ranged from 0.8 to 38.2 (mean +/- SD = 10.5 +/- 9.0). Mean MIB-1 indices were 5.9 in grade I, 10.7 in grade II and 20.5 in grade III. The differences in the mean MIB-1 index between grades I and II and between grades II and III were statistically significant (p < 0.01). Cases with higher DO-7 indices tended to show higher MIB-1 indices, and the relation was statistically significant [y = 0.272x + 4.8; correlation coefficient r = 0.59 > r (n - 2, 0.01) = 0.31]. CONCLUSION: Overexpression of p53 protein was related to cell proliferation as well as histological degree of malignancy in SK. Dysfunction of p53 protein might be implicated in skin carcinogenesis.

Antigens, Nuclear↗

PubMed1999

Intercellular adhesion molecule-1 and hepatocyte growth factor in human endometriosis: original investigation and a review of literature.

Defects in the cell-mediated immune system may play a role in the pathogenesis or progression of pelvic endometriosis. Possible mediators include macrophages, interleukins-1 and -6, and tumor necrosis factor-alpha. More recent work points to the involvement of adhesion molecules and growth factors. To clarify the pathogenesis of endometriosis, we compared the characteristics of soluble intercellular adhesion molecule-1 (soluble ICAM-1) and hepatocyte growth factor (HGF) in women with and without endometriosis. We found that, in patients with endometriosis, the concentrations of soluble ICAM-1 in peritoneal fluid increased and interfered with the activity of natural killer cells. We also found that HGF secretion was significantly increased in cultured endometrial stromal cells, and that HGF stimulated the proliferation and migration of, and morphogenic changes in, endometrial epithelial cells. HGF and ICAM-1 play important roles in the initiation and regulation of endometriotic lesions on the microenvironment level. The increased secretion of HGF by eutopic endometrial stromal cells may contribute to the pathogenesis of endometriosis, whereas the increased levels of soluble ICAM-1 may impair natural killer cell activity and accelerate the progression of the disease.

Cell Division↗

PubMed1999

Dynamic changes in serum leptin concentrations during the fetal and neonatal periods.

We investigated the dynamics of the leptin concentration throughout the perinatal period. Serum leptin concentrations in venous cord blood at different gestational ages were measured in 20 preterm and 139 term newborns, as well as in 143 pregnant women and 24 term newborns at approximately 6 d of life. Leptin concentrations in preterm newborns (mean 4.6+/-6.9 ng/mL) were lower than those in term newborns (mean 19.6+/-14.3 ng/mL) and tended to increase according to gestational age and birth weight, especially from the late stage of gestation. Leptin concentrations in pregnant women increased from the first trimester and then remained higher than those in non-pregnant women throughout the remainder of pregnancy even after controlling for body mass index. The leptin concentrations of newborns declined rapidly and were extremely low by approximately 6 d of life (mean 1.9+/-1.1 ng/mL). These results suggest that fetuses might produce a part of circulating leptin in their own adipocytes and that the relatively high leptin concentrations at birth and their rapid decline in the early neonatal period might reflect the dramatic changes of the hormonal and nutritional state during the perinatal period.

Body Mass Index↗

PubMed1999

Development changes in long-form leptin receptor expression and localization in rat brain.

The expression and localization of long-form leptin receptor (OB-Rb) were studied immunocytochemically in the brain of fetal and adult rats using a polyclonal antibody that specifically recognized OB-Rb. At 14 days of gestation, immunoreactive cells were observed in the ventricular layer, which contains premature neuronal cells. At 18 days of gestation, they were weakly stained but obvious in the paraventricular nucleus (PVN), and ependymal cells also showed immunoreactivity. At birth, the immunoreactivity of OB-Rb in the PVN seemed to be much lower than that in adult rats and remained low during the suckling period. Considering the presence of neuroendocrine and structural neuronal abnormalities in Lepob/Lepob mice with genetic leptin deficiency, these results suggest that the expression of OB-Rb in premature neuronal cells may have some function, and that the regulation of energy balance by leptin through hypothalamic regions, such as PVN, may not yet be developed in the perinatal period.

Aging↗

PubMed1999

Dose-dependent intestinal and hepatic first-pass metabolism of midazolam, a cytochrome P450 3A substrate with differently modulated enzyme activity in rats.

The dose-dependent first-pass metabolism of midazolam, a cytochrome P450 (CYP) 3A substrate, was separately estimated in the intestine and liver after administration into a jejunal loop of rats with differently modulated enzyme activity. Modulation of CYP3A enzyme activity of Sprague-Dawley rats was performed by pretreating the rats with inducers such as dexamethasone or by co-administering ketoconazole (an inhibitor) with midazolam. Bioavailabilities of midazolam administered into the jejunal loop at a dose of 10 micromol were 12% in untreated (control) rats, and 2% in dexamethasone-pretreated rats. Co-administered ketoconazole (2 micromol) significantly increased the bioavailability to 53% and 7%, respectively, in these rats. The intestinal first-pass metabolism of midazolam administered into the jejunal loop at a dose of 50 nmol in untreated and dexamethasone-pretreated rats, estimated by the mesenteric blood-collecting method in-situ, was 25% and 49% of absorbed amount, respectively. The intestinal first-pass metabolism of midazolam was reduced when ketoconazole (0.5 micromol) was co-administered or when the dose of midazolam was increased to 0.5 micrommol in these rats. Assuming that the contribution of intestinal first-pass metabolism could be negligible when midazolam was administered at a much higher dose of 10 micromol, the estimated hepatic first-pass metabolism of midazolam at a dose of 10 micromol in untreated rats, dexamethasone-pretreated rats, untreated rats given ketoconazole, and dexamethasone-pretreated rats given ketoconazole was, respectively, 86, 97, 46, and 92% of the amounts absorbed. In conclusion, the dose-dependent intestinal first-pass metabolism and the hepatic first-pass metabolism of midazolam in rats with differently modulated CYP3A activities was quantitatively estimated by in-vivo and in-situ absorption studies.

Animals↗

PubMed1999

In-vivo and in-vitro metabolic clearance of midazolam, a cytochrome P450 3A substrate, by the liver under normal and increased enzyme activity in rats.

The metabolic clearance of midazolam, a cytochrome P450 (CYP) 3A substrate, by the liver under normal and increased enzyme activity in rats was determined in-vivo and in-vitro to elucidate the reproducibility of the in-vivo hepatic extraction ratio of midazolam from the in-vitro study. The hepatic enzyme activity was modified by pretreating rats with a CYP inducer such as dexamethasone and clotrimazole. The in-vivo hepatic extraction ratio (ERh,obs) of midazolam under a steady-state plasma concentration (approx. 3 nmolmL(-1)) in untreated (control) rats was 0.864. This value increased to 0.984 in dexamethasone-pretreated rats and to 0.964 in clotrimazole-pretreated rats. The in-vitro hepatic intrinsic clearance (CL(int,in-vitro)), expressed as mLmin(-1) (mg microsomal protein)(-1), of midazolam was estimated as Vmax (Km)(-1) by in-vitro metabolism studies using liver microsomes. The CL(int,in-vitro) value was converted to the CL(int,cal) value, expressed as mLmin(-1)kg(-1), by considering the microsomal protein content (g liver)(-1) and the microsomal protein content (g liver)(-1)kg(-1). The estimated CL(int,cal) value was then converted to the ERh value (ER(h,cal)) according to the well-stirred, the parallel-tube and the dispersion models. The ERh(h,cal) values obtained by the parallel-tube model were in good agreement with corresponding in-vivo ERh(h,obs) values. In conclusion, it was demonstrated that high hepatic clearances of midazolam under normal and increased CYP3A activity were reasonably predicted from in-vitro metabolism studies using liver microsomes.

Administration, Oral↗

PubMed1999

Plectin is a linker of intermediate filaments to Z-discs in skeletal muscle fibers.

Plectin is a versatile linker protein which is associated with various types of cytoskeletal components and/or filaments including intermediate filaments, and its deficiency causes the disruption of myofibrils, or muscular dystrophy. To better understand the functional role of plectin in skeletal muscle fibers, we have examined the topological and structural relationships of plectin to intermediate filaments and Z-discs in rat diaphragm muscles by confocal and immunoelectron microscopy. Immunofluorescence analysis revealed that plectin was colocalized with desmin at the periphery of Z-discs. This plectin localization around Z-discs was constantly maintained irrespective of the contracted or extended state of the muscle fibers, suggesting either direct or indirect association of plectin with Z-discs. Immunogold labeling in skinned muscle fibers clearly demonstrated that plectin-labeled fine threads linked desmin intermediate filaments to Z-discs and connected intermediate filaments to each other. These results indicate that through plectin threads desmin intermediate filaments form lateral linkages among adjacent Z-discs, preventing individual myofibrils from disruptive contraction and ensuring effective force generation.

Animals↗

PubMed1999

Antidiabetic principles of natural medicines. IV. Aldose reductase and qlpha-glucosidase inhibitors from the roots of Salacia oblonga Wall. (Celastraceae): structure of a new friedelane-type triterpene, kotalagenin 16-acetate.

The aqueous methanolic extract of an Indian natural medicine, the roots of Salacia oblonga Wall. (Celastraceae), was found to show inhibitory activity on the increase in serum glucose level in sucrose- and maltose-loaded rats. The water-soluble and ethyl acetate-soluble portions from the aqueous methanolic extract showed inhibitory activities on alpha-glucosidase and aldose reductase, respectively. From the water-soluble portion, potent alpha-glucosidase inhibitors, salacinol and kotalanol, were isolated, together with nine sugar related components, while a new friedelane-type triterpene, kotalagenin 16-acetate, was isolated from the ethyl acetate-soluble portion along with known diterpenes and triterpenes. The structure of kotalagenin 16-acetate was elucidated on the basis of physicochemical evidence. Principal components from this natural medicine were examined in terms of inhibitory activity on aldose reductase, and the diterpene and triterpene constituents, including the new kotalagenin 16-acetate, were found to be responsible components for the inhibitory activity on aldose reductase.

Aldehyde Reductase↗

PubMed1999

Bioactive saponins and glycosides. XIV. Structure elucidation and immunological adjuvant activity of novel protojujubogenin type triterpene bisdesmosides, protojujubosides A, B, and B1, from the seeds of Zizyphus jujuba var. spinosa (Zizyphi Spinosi Semen).

Following the elucidation of jujubosides A1 and C and acetyljujuboside B, novel protojujubogenin type triterpene bisdesmosides, protojujubosides A, B, and B1, were isolated from Zizyphi Spinosi Semen, the seeds of Zizyphus jujuba Mill. var. spinosa Hu. The structures of protojujubosides A, B, and B1 were determined on the basis of chemical and physicochemical evidence, which included the conversion of protojujubosides to known jujubosides using enzymatic hydrolysis. Protojujubosides A and jujubosides A, B, and C were found to show potent immunological adjuvant activity.

Adjuvants, Immunologic↗

PubMed1999

Bioactive saponins and glycosides. XV. Saponin constituents with gastroprotective effect from the seeds of tea plant, Camellia sinensis L. var. assamica Pierre, cultivated in Sri Lanka: structures of assamsaponins A, B, C, D, and E.

The saponin fraction from the seeds of the tea plant, Camellia sinensis L. var. assamica Pierre cultivated in Sri Lanka, was found to show a potent protective effect on gastric mucosal lesions induced by ethanol in rats. Nine new acylated polyhydroxyoleanene-type triterpene oligoglycosides called assamsaponins A-I were isolated from the active saponin fraction together with three known saponins, theasaponin E1 and E2 and camelliasaponin B1. The structures of assamsaponins A-E were elucidated on the basis of chemical and physicochemical evidence. Theasaponin E1 exhibited potent gastroprotective activity.

Animals↗

PubMed1999

Medicinal flowers. I. Aldose reductase inhibitors and three new eudesmane-type sesquiterpenes, kikkanols A, B, and C, from the flowers of Chrysanthemum indicum L.

The methanolic extract from the flowers of Chrysanthemum indicum L., Chrysanthemi Indici Flos, was found to show inhibitory activity against rat lens aldose reductase. By bioassay-guided separation, the active components, such as flavone and flavone glycosides, were isolated from the extract together with three new eudesmane-type sesquiterpenes, kikkanols A, B, and C. The structures of kikkanols A, B, and C were elucidated on the basis of chemical and physicochemical evidence, which included application of the modified Mosher's method.

Aldehyde Reductase↗

PubMed1999

[Bioactive saponins and glycosides. XIII. Horse chestnut. (3): Quantitative analysis of escins Ia, Ib, IIa, and IIb by means of high performance liquid chromatography].

As a part of our studies on the characterization of bioactive saponin constituents of horse chestnut trees, a quantitative method using high performance liquid chromatography (HPLC) has been developed for four principle saponin constituents, such as escins Ia, Ib, IIa, and IIb, isolated from the seeds of European horse chestnut trees (Aesculus hippocastanum L., Hippocastanaceae). As an application of this HPLC method, we examined the contents and compositions of these escins in the seeds of Japanese horse chestnut trees (A. turbinata BLUME) and in several commercial materials named as "beta-escin". Additionally, the distribution of escins in the Japanese horse chestnut trees was examined, and escins were found to be contained only in the seeds.

Chromatography, High Pressure Liquid↗

PubMed1999

Plasma endothelin-1 elevation associated with alcohol-induced variant angina.

Vasospastic angina as a result of alcohol ingestion has been reported, but the mechanism of alcohol-induced coronary artery spasm is presently unknown. This report presents 2 cases of alcohol-induced variant angina (VA) with elevated levels of plasma endothelin-1 after alcohol ingestion. In case 1, the plasma endothelin-1 concentration was 3.15 pg/ml before drinking (normal <2.30 pg/ml) and increased to 4.09 pg/ml when measured 5 h after alcohol ingestion. After 2 months of abstinence, the plasma endothelin-1 concentration was 2.88 pg/ml and 6 months after abstinence, it decreased to 2.03 pg/ml (normal range). In case 2, the plasma endothelin-1 concentration was 2.44 pg/ml before drinking and increased to 4.36 pg/ml when measured 5 h after alcohol ingestion. After 2 months of abstinence, the plasma endothelin-1 concentration was 3.04 pg/ml and 6 months after abstinence, it decreased to 2.09 pg/ml (normal range). These 2 cases suggest that a relationship may exist between alcohol-induced VA and elevation in the plasma endothelin-1 concentration after alcohol ingestion.

Aged↗

PubMed1999

Spinal oligodendroglioma with diffuse arachnoidal dissemination in a Japanese Black heifer.

A gelatinous focus with cystic spaces, was found in the posterior funiculus of the 2nd to 3rd lumbar levels of the spinal cord of a Japanese Black heifer, 2 years old, with clinical signs of severe dysstasia. Histopathological examination revealed that the spinal lesion consisted of multifocal and diffuse proliferation of round cells with abundant vacuolar cytoplasm and hyperchromatic nuclei. In the lesions there was a number of cystic spaces containing aggregates of small round cells. The neoplastic foci showed a honeycomb structure divided by thin blood vessels, representing typical lesions of oligodendroglioma. Diffuse and multifocal proliferation of these round cells were also recognized in the subarachnoidal space in the sacral spinal cord. Immunohistochemically, the proliferating round cells were negative for glial fibrillary acidic protein. Based on these morphological features, the case was diagnosed as lumbar spinal oligodendroglioma with diffuse arachnoidal dissemination.

Animals↗

PubMed1999

Multicystic renal dysplasia in a Japanese black bull.

Multicystic renal dysplasia was found in a 6-day-old Japanese black bull. Grossly, both kidneys were markedly small (2.0 x 3.5 cm) with numerous cysts ranging from 1 to 8 mm in diameter. Histopathologically, both kidneys consisted of many irregularly enlarged cysts, immature glomeruli, small ducts and anomalous stromal connective tissues containing focal persistent mesenchyme characterized by a proliferation of stellate cells with myxomatous area. These features are compatible with those of multicystic renal dysplasia in humans and other mammals.

Animals↗

PubMed1999

A novel A-kinase anchoring protein in the heart interacts with G alpha 13.

A cDNA of a tentative A-kinase anchoring protein, presumably coupled with heterotrimeric GTP binding protein alpha 13 subunit (G alpha 13), was cloned from a human heart cDNA library. It was approximately 650 bases and its mRNA was expressed in the heart. Homology search of DNA sequences revealed that it was a novel cDNA with 84% homology with the partial sequence of rabbit cDNA of AKAP 120 without a stop codon. 3'-Rapid Amplification of cDNA Ends (3'-RACE) and yeast functional assay were performed to determine the 3'-end of the cDNA and ribosomal frameshifting was suggested as a translational mechanism. Here we report that a protein encoded by the cDNA may be involved in intracellular signal transduction via the G alpha 13 and PKA in hearts.

A Kinase Anchor Proteins↗