Search PubMed⌕ Search

Biomedical subjects

T Ito

Publications and source records attributed to T Ito.

At least 253 records · Page 14Linked to original sources
PubMed2001

Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress.

Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.

Adrenal Cortex Hormones↗
PubMed2001

Dynamic changes in subcellular localization of mineralocorticoid receptor in living cells: in comparison with glucocorticoid receptor using dual-color labeling with green fluorescent protein spectral variants.

Mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) are ligand-dependent transcription factors. Although it is generally accepted that GR is translocated into the nucleus from the cytoplasm only after ligand binding, the subcellular localization of MR is still quite controversial. We examined the intracellular trafficking of MR in living neurons and nonneural cells using a fusion protein of green fluorescent protein (GFP) and rat MR (GFP-MR). Corticosterone (CORT) induced a rapid nuclear accumulation of GFP-MR, whereas in the absence of ligand, GFP-MR was distributed in both cytoplasm and nucleus in the majority of transfected cells. Given the differential action of MR and GR in the central nervous system, it is important to elucidate how the trafficking of these receptors between cytoplasm and nucleus is regulated by ligand. To examine the simultaneous trafficking of MR and GR within single living cells, we use different spectral variants of GFP, yellow fluorescent protein (YFP) and cyan fluorescent protein (CFP), linked to MR and GR, respectively. In COS-1 cells, expressing no endogenous corticosteroid receptors, the YFP-MR chimera was accumulated in the nucleus faster than the CFP-GR chimera in the presence of 10(-9) M CORT, while there was no significant difference in the nuclear accumulation rates in the presence of 10(-6) M CORT. On the other hand, in primary cultured hippocampal neurons expressing endogenous receptors, the nuclear accumulation rates of the YFP-MR chimera and CFP-GR chimera were nearly the same in the presence of both concentrations of CORT. These results suggest that CORT-induced nuclear translocation of MR and GR exhibits differential patterns depending on ligand concentrations or cell types.

Animals↗
PubMed2001

Overexpression of Hoxc13 in differentiating keratinocytes results in downregulation of a novel hair keratin gene cluster and alopecia.

Studying the roles of Hox genes in normal and pathological development of skin and hair requires identification of downstream target genes in genetically defined animal models. We show that transgenic mice overexpressing Hoxc13 in differentiating keratinocytes of hair follicles develop alopecia, accompanied by a progressive pathological skin condition that resembles ichthyosis. Large-scale analysis of differential gene expression in postnatal skin of these mice identified 16 previously unknown and 13 known genes as presumptive Hoxc13 targets. The majority of these targets are downregulated and belong to a subgroup of genes that encode hair-specific keratin-associated proteins (KAPs). Genomic mapping using a mouse hamster radiation hybrid panel showed these genes to reside in a novel KAP gene cluster on mouse chromosome 16 in a region of conserved linkage with human chromosome 21q22.11. Furthermore, data obtained by Hoxc13/lacZ reporter gene analysis in mice that overexpress Hoxc13 suggest negative autoregulatory feedback control of Hoxc13 expression levels, thus providing an entry point for elucidating currently unknown mechanisms that are required for regulating quantitative levels of Hox gene expression. Combined, these results provide a framework for understanding molecular mechanisms of Hoxc13 function in hair growth and development.

Alopecia↗
PubMed2001

Biodegradation and drug release of chitosan gel beads in subcutaneous air pouches of mice.

Chitosan (CS) gel beads were prepared in 10% amino acid solution (pH 9) and implanted into air pouches (AP) prepared subcutaneously on the dorsal surface of mice. No inflammatory response was observed, and degradation of the beads in the AP increased as their degree of deacetylation decreased. Degradation could be altered by changing the nature of the CS or by increasing the CS concentration. The release of prednisolone (PS) in vivo from CS gel beads was similar to the release in vitro. When a suspension of PS was injected into the AP, the PS had almost completely disappeared 24 h after injection. Retention of PS in the AP was not increased by using a viscous CS solution. Alginate (Alg) gel beads, which were not degraded, released PS slowly into the AP over 3d. The in vitro release profile of PS using 1% CS (deacetylation: 70% (7B) and 80% (8B)) and 1.5% CS (deacetylation: 90% (9B)) gel beads was similar to that with Alg gel beads. However, the in vivo release of PS was affected by the degradability of the gel beads. CS7B and 8B (1%) gel beads had released PS into the AP earlier than 3 d according to their rate of degradation. CS9B (1.5%) gel beads were not degraded after 3 d and went on to release PS into the AP for 3 d similar to the release profile of Alg gel beads. CS9B (2%) gel beads were also not degraded after 3 d and the release of PS from these beads into the AP was sustained; 76% and 27% of administered PS remained in the gel beads after 1 and 3 d, respectively. Therefore, degradation and drug release of CS gel beads can be controlled by changing the structure of the gel matrix, which appears to make these beads a promising biodegradable vehicle for sustained drug delivery.

Animals↗
PubMed2001

Stilbenoids in lianas of Gnetum parvifolium.

Five new stilbene dimers were isolated from the lianas of Gnetum parvifolium in addition to known stilbenoids. The structures of the compounds were established on the basis of spectroscopic evidence, including long-range coupling and nuclear Overhauser effect experiments, in NMR spectrum. Among the isolates, 2b-hydroxyampelopsin F showed potent inhibitory activity in the Maillard reaction.

Acetylation↗
PubMed2001

Activation-recovery intervals of 12-lead electrocardiograms before and after catheter ablation in patients with Wolff-Parkinson-White syndrome.

Preexcitation in Wolff-Parkinson-White syndrome (WPW) has been reported to induce long-lasting changes in ventricular recovery properties. However, there has not been a report concerning changes in the activation-recovery interval (ARI) in 12-lead ECGs before and after catheter ablation (CA) in patients with WPW syndrome. The present study compared changes in ARIs from 12-lead ECGs with those from body surface unipolar leads before and after CA to examine whether ARIs from limb leads of 12-lead ECGs provide useful information on changes in recovery properties in addition to the ARIs from precordial leads. The study population consisted of 27 manifest WPW patients with a left- (n=18, group A) or right-sided accessory pathway (n=9, group B). ARIs in leads I, II, and III were strongly correlated with those in unipolar leads over the left lateral, left lower, and right lower chest, respectively. ARIs in leads aVR, aVL, and aVF showed a significant correlation with those in unipolar leads over the right upper, left upper, and lower anterior chest, respectively. These correlations were maintained before and after CA. Furthermore, in group A, ARIs in lead V1 tended to increase on day 7 post CA compared with before CA and on day 1. In group B, ARIs in lead III significantly decreased on day 7 compared with before CA and on day 1. These findings suggest that ARIs from the limb leads of 12-lead ECGs may represent those from unipolar leads of a particular area over the body surface, and that ARIs from 12-lead ECGs may provide useful quantitative information on changes in recovery properties before and after CA in patients with manifest WPW syndrome.

Adolescent↗
PubMed2001

A case of cardiomyopathy showing progression from the hypertrophic to the dilated form: association of Mt8348A-->G mutation in the mitochondrial tRNA(Lys) gene with severe ultrastructural alterations of mitochondria in cardiomyocytes.

This report describes a case of cardiomyopathy with a novel point mutation of mitochondrial DNA coding lysine tRNA in association with severe ultrastructural alterations of the mitochondria in the cardiomyocytes. Abnormalities of energy production and/or abnormal protein synthesis because of the mutation of mitochondrial DNA may have played an important role in the pathogenesis of this case, which showed severe cardiomyocyte degeneration and deterioration from hypertrophic cardiomyopathy to severe dilated cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2001

Role of transesophageal echocardiography in the prediction of thromboembolism in patients with chronic nonvalvular atrial fibrillation.

The purpose of this study was to determine whether parameters derived from transesophageal echocardiography (TEE) could predict thromboembolism in patients with chronic nonvalvular atrial fibrillation (AF). Eighty-nine patients, mean age 66+/-9 years, who underwent TEE in 1996 to 1999 were studied. The clinical endpoint was a thromboembolic event, including transient ischemic attack (TIA). Sixty-seven patients (75%) were anticoagulated with warfarin after TEE. After a follow-up period of 29+/-10 months, 1 patient died suddenly, 4 had a thromboembolism, and 3 had a TIA; the annual embolic event rate was 3.3%. Left atrial appendage (LAA) thrombus (86% vs 17%, p<0.001), LAA dysfunction (LAA velocity <20 cm/s; 71% vs 25%, p=0.009), and severe LA spontaneous echo contrast (29% vs 2%, p=0.002) were more prevalent in patients with an embolic event than in those without. In patients with LAA thrombus, the annual event rate was 11% as compared with 1.2% in those without (p=0.004). On the Cox proportional hazards model analysis, LAA thrombus (chi-square 7.0, p=0.008), severe LA spontaneous echo contrast (chi-square 7.0, p=0.008), and LAA dysfunction (chi-square 5.9, p=0.015) were significantly related to thromboembolism. Multivariate analysis revealed that LAA thrombus (chi-square 5.5, p=0.019) and LAA dysfunction (chi-square 4.0, p=0.045) were the independent predictors. In conclusion, TEE parameters, particularly the presence of LAA thrombus, can be used to assess thromboembolic potential in patients with chronic nonvalvular AF.

Aged↗
PubMed2001

Disturbance of circadian rhythm in heart rate, blood pressure and locomotive activity at the stroke-onset in malignant stroke-prone spontaneously hypertensive rats.

Malignant stroke-prone spontaneously hypertensive rats (M-SHRSP), separated from SHRSP, develop severe hypertension and spontaneously develop stroke at early ages. Using this model of cerebrovascular stroke, influence of stroke-onset on the autonomic nervous system was investigated. Heart rate (HR), systolic and diastolic blood pressures (SBP and DBP) and locomotive activity were monitored during development of stroke using a telemetry system. Stroke-onset was assessed by neurologic symptoms, changes in body weight, fluid intake and serum NOx level. The rat displayed a nocturnal pattern of circadian rhythms. At stroke-onset, mean HR over 24 h increased by 20 to 30 bpm and rapidly increased at post stroke, approximately 100 bpm higher than that at pre stroke. Circadian variation in HR, which was normally 50 bpm higher during night than during day, attenuated at stroke-onset, and it was blunted or reversed at post stroke. BP variation, which was approximately 7 mmHg higher at night than at day, decreased one or two days before stroke-onset and reversed at post stroke, especially in DBP. Insufficient falls in HR and BP during the day mainly accounted for the disturbed circadian variations. Variation of locomotive activity also decreased. These changes serve as reliable and accurate markers for stroke-onset in evaluation of drugs for the prevention and outcome predictions of stroke.

Animals↗
PubMed2001

Lipase production in two-step fed-batch culture of organic solvent-tolerant Pseudomonas aeruginosa LST-03.

Efficient lipase production by two-step fed-batch culture of an organic solvent-tolerant bacterium, Pseudomonas aeruginosa LST-03, was investigated. When FB synthetic medium was used in flask culture, no lipase activity was detected, whereas lipase was produced at 2.3 I.U./ml in C2 complex medium. However, lipase production was induced in FB medium when a fatty acid was added to the culture broth in the stationary phase. Among fatty acids tested, long chain saturated fatty acids, such as C18 (stearic acid) and C20 (arachidic acid), were found to function as effective inducers for the production of lipase, giving an activity level almost the same as that obtained in C2 medium in flask culture. Two-step lipase production, comprised of a growth phase in fed-batch mode and a production phase in which lipase was induced by the addition of 5% (v/v) stearic acid, was carried out in a jar-fermentor. In the growth phase, the maximum cell concentration at 16 h was only 20 in terms of the optical density at 660 nm (OD660), and a low level of lipase production (8 I.U./ml) was obtained after 167 h. This was considered to be due to the exhaustion of several medium components brought about by the use of an unsuitable medium or feeding solution. After analyzing the contents of the compounds in the culture broth by inductively coupled plasma spectrometry for metal ions and HPLC for anions, a modified FB medium was designed. When this modified FB medium was used in two-step fed-batch culture, the maximum cell concentration reached an OD660 of 55 (30.2 g-dry cells/l) at 16.5 h, and lipase was produced at 96 I.U./ml after 35 h, which is approximately 40 times higher than the production level obtained in flask culture using C2 medium.

Journal Article↗
PubMed2001

Characterization of the cellulose-binding ability of Geotrichum sp. M111 cells and its application to dehydration of the distilled waste of sweet potato shouchu.

The cellulose-binding ability of Geotrichum sp. M111 cells was investigated by the micro-tube method which gives an indication of the binding ability of M111 cells. The optimum pH value and temperature were 3-7 and below 50 degrees C, respectively, from measurement of the aggregation height for a mixture of cellulose powder and M111 cells. The binding constant of 0.3% for M111 cells to cellulose powder was obtained in a 20 mm citrate buffer of pH 5.0 at 30 degrees C. Aggregation was inhibited by such surfactants as sodium dodecylsulfate. The binding ability of M111 cells to cellulose fiber disappeared after a treatment with Driselase or Pronase E. This suggests that the binding ability might be related to the cell surface proteins. The dehydration rate of the distilled waste of sweet potato shouchu was accelerated by the addition of M111 cells. The analysis of dehydration by a linear viscoelastic model suggests that the acceleration effect might have been due to the space increase between cellulose fibers with the cell addition.

Cellulose↗
PubMed2001

Isotope ratio by HRGC-MS of citrus Junos tanaka (yuzu) essential oils: m/z 137/136 of terpene hydrocarbons.

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, alpha-pinene, beta-pinene, sabinene, myrcene, alpha-phellandrene, alpha-terpinene, limonene, gamma-terpinene, beta-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.

Citrus↗
PubMed2001

ESR imaging on a solid-tumor-bearing mouse using spin-labeled dextran.

Imaging of a tumor with ESR was tried using two different types of spin probes, a low molecular weight spin probe, CPROXYL, and a polymer spin probe, TEMPO-DX. Spin probes were administered to a mouse bearing a solid tumor that was a transplanted Ehrlich's ascites carcinoma in the back, using two methods, conventional intraperitoneal injection and continuous intravenous injection with a micro-feeder. First, the accumulation of the probe was examined by X-band ESR. CPROXYL, which was administered to a mouse intraperitoneally, was exclusively retained in urine, showing that it was rapidly excreted into the bladder, while TEMPO-DX was absorbed from the peritoneal cavity with difficulty to the vessel. Using continuous intravenous injection, CPROXYL was also rapidly excreted, but it was confirmed that TEMPO-DX concentrated in tumor tissue because it has a long half-life in vivo. In addition, measurement of ESR imaging was done to measure the distribution of spin probes with continuous intravenous injection. The strongest spot of CPROXYL was observed on ESR images, showing the accumulation at the bladder, while the spot of TEMPO-DX was observed in the solid tumor of the back of the mouse. These results suggest that TEMPO-DX could stay much longer than a low molecular weight spin probe in vivo and concentrate at the tumor. TEMPO-DX may be useful for developing specific ESR imaging agents for tumor.

Animals↗
PubMed2001

An elderly patient with gastric carcinoma developing multiple metastasis in skeletal muscle.

We present a 70-year-old man with gastric carcinoma developing multiple metastasis in skeletal muscle. He had a right supraclavicular lymph node swelling. Brain, chest and abdomen CT scans revealed metastatic lesions in the brain, lung, liver and bilateral adrenal glands. Further, CT showed a ring enhanced soft-tissue mass in the left lumbar muscle. Needle aspirate of the mass in both the left lumbar muscle and the right enlarged supraclavicular lymph node revealed cells suggestive of poorly differentiated adenocarcinoma. Upper gastrointestinal endoscopic evaluation demonstrated an advanced gastric carcinoma. Two months after admission, the tumor in the left lumbar muscle had grown and some new lesions in the left iliopsoas muscles appeared. Intramuscular metastasis from gastric carcinoma is an extremely rare phenomenon.

Adenocarcinoma↗
PubMed2001

Impaired nitric oxide production and enhanced autoregulation of coronary circulation in young spontaneously hypertensive rats at prehypertensive stage.

In the current study, we investigated the NO-generation pathway in response to mechanical stimuli in SHR at the prehypertensive stage. To examine the role of NO in coronary autoregulation, we evaluated the effects of L-NAME on the coronary flow in SHR at both the prehypertensive and hypertensive stages. Isolated perfused hearts from 5- and 15-week-old SHR and from age-matched Wistar-Kyoto rats (WKY) were used. After stabilization at 60 mmHg, perfusion pressure was immediately raised to 90 mmHg to record the change in coronary flow for 10 min without (control) or with NO synthesis blockade by Nomega-nitro-L-arginine methyl ester (L-NAME). NOx- (nitrite/nitrate) was measured in coronary effluent. At 5 weeks of age, SHR did not have hypertension, while the coronary autoregulation was enhanced. L-NAME did not affect this enhanced autoregulation in 5-week-old SHR. At perfusion pressures of both 60 and 90 mmHg, 5-week-old SHR showed less coronary NOx- production than age-matched WKY. At 15 weeks, SHR showed a higher blood pressure than WKY. The coronary autoregulation in SHR remained higher than that in WKY, but was below that in 5-week-old SHR. NOx- production in 15-week-old SHR recovered to the level of age-matched WKY. These results indicate that NOx- production induced by mechanical stimulation was markedly reduced in 5-week-old SHR at the prehypertensive stage, which may have enhanced coronary autoregulation. An impaired nitric oxide production may precede the onset of hypertension in SHR.

Animals↗
PubMed2001

Altered expression of prostacyclin synthase in a subset of the thick ascending limb cells and mesangial cells in 5/6-nephrectomized rats.

The aim of this study was to evaluate the possible role of prostacyclin (PGl2) in the onset and development of hypertension and chronic renal failure in 5/6-nephrectomized rats (5/6NX). We measured the systolic blood pressure, 24-h urinary excretion levels of 6-keto-PGF1alpha, which was a stable metabolite of PGI2, and levels of PGI2 synthase (PCS) mRNA in the kidneys. Immunostaining for PCS in the kidneys was also evaluated. Systolic blood pressure was higher in 5/6NX than in sham-operated rats. The 24-h urinary excretion levels of 6-keto-PGF1alpha in 5/6NX at 1 week postsurgery were lower than in sham-operated rats. In renal morphology, tubulointerstitial injury was observed at 2 weeks postsurgery, and glomerulosclerosis at 4 weeks. Levels of PCS mRNA in 5/6NX decreased significantly at 1 and 2 weeks postsurgery compared with those in sham-operated rats, but at 8 weeks these levels showed a tendency to increase. Immunostaining for PCS was positive in a subset of the cortical thick ascending limb of Henle's loop cells, including macula densa in both groups. Moreover, in 5/6NX at 8 weeks postsurgery, mesangial cells also stained positive for PCS. In conclusion, our findings suggest that PCS might play an important role in mitigating glomerular hemodynamic changes associated with reduction of renal mass.

6-Ketoprostaglandin F1 alpha↗
PubMed2001

Serum growth hormone and insulin-like growth factor-1 concentrations in Japanese black cattle with growth retardation.

Serum concentrations of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were determined in 5 calves in the same lineage with growth retardation. They had normal appetites, activities, body proportion, and laboratory test results. Calves with growth retardation had higher serum GH concentrations and lower serum IGF-I concentrations. These findings suggested defects in the GH-IGF-1 axis, such as in the GH-receptor.

Animals↗