Search PubMed⌕ Search

Biomedical subjects

N Ishida

Publications and source records attributed to N Ishida.

At least 37 records · Page 2Linked to original sources
PubMed2001

Defective cellular trafficking of lacrimal gland aquaporin-5 in Sjögren's syndrome.

Dry eyes and dry mouth are clinical hallmarks of Sjögren's syndrome. We assessed the distribution of aquaporin-5 (AQP5) in lacrimal gland biopsy samples. Healthy controls and patients with Mikulicz's disease or non-Sjögren's syndrome dry eye had the expected apical distribution of AQP5 in lacrimal acinar cells. By contrast, cytoplasmic AQP5 was seen in patients with Sjögren's syndrome. Sodium channel and sodium-potassium ATPase distributions were normal in all groups. These findings show a selective defect in lacrimal gland AQP5 trafficking in Sjögren's syndrome that might contribute to decreased lacrimation and dry eye in these patients.

Aquaporin 5↗
PubMed2001

Down-regulation of p27Kip1 expression is required for development and function of T cells.

The proliferation of T cells is regulated in a development-dependent manner, but it has been unclear whether proliferation is essential for T cell differentiation. The cyclin-dependent kinase inhibitor p27(Kip1) is abundant throughout development in cells of the T cell lineage, with the exception of late stage CD4(-)CD8(-) thymocytes and activated mature T cells, both of which show a high rate of proliferation. The role of down-regulation of p27(Kip1) expression in T cell development and function has now been investigated by the generation and characterization of three strains of p27 transgenic mice that express the transgene at various levels specifically in the T cell lineage. The numbers of thymocytes at CD4(+)CD8(+), CD4(+)CD8(-), and CD4(-)CD8(+) stages of development as well as those of mature T cells in peripheral lymphoid tissues were reduced in transgenic mice in a manner dependent on the level of p27(Kip1) expression. The development of thymocytes in the transgenic strain in which p27(Kip1) is most abundant (p27-Tg(high) mice) appeared to be blocked at the CD4(-)CD8(-)CD25(+)CD44(low) stage. Peripheral T cells from p27-Tg(high) mice exhibited a reduced ability to proliferate in response to mitogenic stimulation compared with wild-type T cells. Moreover, Ag-induced formation of germinal centers and Ig production were defective in p27-Tg(high) mice. These results suggest that down-regulation of p27(Kip1) expression is required for the development, proliferation, and immunoresponsiveness of T cells.

Animals↗
PubMed2001

Pulmonary ventilation-perfusion MR imaging in clinical patients.

The purpose of this study was to evaluate the feasibility of comprehensive magnetic resonance (MR) assessment of pulmonary perfusion and ventilation in patients. Both oxygen-enhanced ventilation MR images and first-pass contrast-enhanced perfusion MR images were obtained in 16 patients with lung diseases, including pulmonary embolism, lung malignancy, and bulla. Inversion recovery single-shot fast spin-echo images were acquired before and after inhalation of 100% oxygen. The overall success rate of perfusion MR imaging and oxygen-enhanced MR imaging was 94% and 80%, respectively. All patients with pulmonary embolism showed regional perfusion deficits without ventilation abnormality on ventilation-perfusion MR imaging. The results of the current study indicate that ventilation-perfusion MR imaging using oxygen inhalation and bolus injection of MR contrast medium is feasible for comprehensive assessment of pulmonary ventilation-perfusion abnormalities in patients with lung diseases.

Adult↗
PubMed2001

Characterization of a mouse gene (Fbxw6) that encodes a homologue of Caenorhabditis elegans SEL-10.

The SCF complex is a type of ubiquitin ligase that consists of the invariable components SKP1, CUL1, and RBX1 as well as a variable component, known as an F-box protein, that is the main determinant of substrate specificity. The Caenorhabditis elegans F-box- and WD40-repeat-containing protein SEL-10 functionally and physically associates with LIN-12 and SEL-12, orthologues of mammalian Notch and presenilin, respectively. We have now identified a gene (which we call Fbxw6) that encodes a mouse homologue (F-box-WD40 repeat protein 6, or FBW6) of SEL-10 and is expressed mainly in brain, heart, and testis. Co-immunoprecipitation analysis showed that FBW6 interacts with SKP1 and CUL1, indicating that these three proteins form an SCF complex. Comparison of the genomic organization of Fbxw6, which is located on mouse chromosome 3.3E3, with that of mouse Fbxw1, Fbxw2, and Fbxw4 showed only a low level of similarity, indicating that these genes diverged relatively early and thereafter evolved independently.

Amino Acid Sequence↗
PubMed2001

Tear in the trabecular meshwork caused by an airsoft gun.

PURPOSE: To report a case of a tear in the trabecular meshwork caused by an airsoft gun, a toy that propels a plastic bullet. METHODS: Case report. RESULTS: A 7-year-old Japanese boy sustained an ocular injury to the right eye from an airsoft gun. Ophthalmic examination 1 hour after the injury showed a best-corrected visual acuity in the injured eye of hand motion, corneal abrasion and edema, hyphema, and commotio retinae. Gonioscopy 6 days after the injury revealed a tear in the trabecular meshwork as well as an angle recession. Ultrasound biomicroscopy (UBM) strongly suggested that the tear extended into Schlemm's canal. Corneal abrasion and edema, hyphema, and commotio retinae resolved over 10 days, and best-corrected visual acuity improved to 20/15. Two months after the injury, the trabecular meshwork had not healed. CONCLUSION: Airsoft guns can cause a full-thickness tear in the trabecular meshwork, which may contribute to development of late-onset glaucoma. UBM is useful to evaluate the tomographic features of the disrupted trabecular meshwork. The potential force of airsoft guns to cause substantial ocular injuries should be recognized. Wearing ocular protection should be mandatory while playing with airsoft guns.

Child↗
PubMed2001

Architecture of baked breads depicted by a magnetic resonance imaging.

The architecture of baked breads made of fresh dough and frozen dough was depicted by magnetic resonance imaging (MRI). Pieces of bread (16 mm cubic cakes) were soaked in organic solvents containing various concentrations of heavy metals (Cu(2+), Co(2+) and Fe(3+)) and images of the grain structure of the breads were obtained. Of the organic solvents tested, acetone was preferable because of its single peak that prevents chemical shift effects on images, the retention of the bread structure, and the solubility of heavy metals. The heavy metals, especially Fe(3+), shortened the overly long relaxation times of acetone to practical lengths for imaging and stained the materials to provide high contrasts. The images obtained in acetone with 8 mM Fe(3+) were suitable for analyzing crumb grain structures. The bread of fresh dough showed a uniform distribution of pores of various sizes made of thin gluten sheets, whereas the pores in the bread of frozen dough were less, prominently large, non-uniformly distributed, and made of thick gluten sheets.

Bread↗
PubMed2001

Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk.

Increasing evidence indicates a significant role for vitamin K in bone metabolism and osteoporosis. In this study, we found a large geographic difference in serum vitamin K2 (menaquinone-7; MK-7) levels in postmenopausal women. Serum MK-7 concentrations were 5.26 +/- 6.13 ng/mL (mean +/- SD) in Japanese women in Tokyo, 1.22 +/- 1.85 in Japanese women in Hiroshima, and 0.37 +/- 0.20 in British women. We investigated the effect of Japanese fermented soybean food, natto, on serum vitamin K levels. Natto contains a large amount of MK-7 and is eaten frequently in eastern (Tokyo) but seldom in western (Hiroshima) Japan. Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration. We analyzed the relation between the regional difference in natto intake and fracture incidence. A statistically significant inverse correlation was found between incidence of hip fractures in women and natto consumption in each prefecture throughout Japan. These findings indicate that the large geographic difference in MK-7 levels may be ascribed, at least in part, to natto intake and suggest the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.

Aged↗
PubMed2001

Prefabricated bone graft induced from grafted periosteum for the repair of jaw defects: an experimental study in rabbits.

PURPOSE: The purpose of the study was to determine whether a prefabricated graft of new bone induced from periosteum grafted into muscle was an effective material for the repair of jaw defects. MATERIAL AND METHODS: Artificial mandibular jaw defects in young Japanese rabbits were covered either with free grafted periosteum (n = 5) or a prefabricated graft of newly formed bone induced from periosteum, which was first grafted into the floor of the mouth, and placed as a revascularized muscle-pedicled bone flap (n = 5). Bone formation in jaw defects was examined radiographically and histologically 28 days after grafting into defects. RESULTS: Bone formation was confirmed radiographically and histologically in both groups. However, the free grafted periosteum formed thin bone and fibrous tissue existed between the new and the original bone. In contrast, more active bone formation was observed with the prefabricated graft. This grafted new bone developed further and fused to the mandible. Blood vessels surrounding the new bone were observed histologically. CONCLUSION: These experimental findings suggested that prefabricated bone grafts induced from periosteum grafts are potentially useful for correction of jaw defects.

Animals↗
PubMed2001

Association of structural polymorphisms in the human period3 gene with delayed sleep phase syndrome.

Recent progress in biological clock research has facilitated genetic analysis of circadian rhythm sleep disorders, such as delayed sleep phase syndrome (DSPS) and non-24-h sleep-wake syndrome (N-24). We analyzed the human period3 (hPer3) gene, one of the human homologs of the Drosophila clock-gene period (Per), as a possible candidate for rhythm disorder susceptibility. All of the coding exons in the hPer3 gene were screened for polymorphisms by a PCR-based strategy using genomic DNA samples from sleep disorder patients and control subjects. We identified six sequence variations with amino acid changes, of which five were common and predicted four haplotypes of the hPer3 gene. One of the haplotypes was significantly associated with DSPS (Bonferroni's corrected P = 0.037; odds ratio = 7.79; 95% CI 1.59-38.3) in our study population. Our results suggest that structural polymorphisms in the hPer3 gene may be implicated in the pathogenesis of DSPS.

Adolescent↗
PubMed2001

Guanabenz, an antihypertensive centrally acting alpha2-agonist, suppresses morning elevations in aggregation of human platelets.

To determine whether the antihypertensive agent guanabenz affects the circadian rhythm in the hemorheologic properties of the platelet, we evaluated the aggregability of platelets collected from 11 healthy subjects in the morning and the evening after the oral administration of this agent, daily for 2 weeks. We analyzed platelet aggregation by the turbidimetric method. In an in vitro study, guanabenz, 10 nM-100 microM, did not affect platelet aggregation, whereas epinephrine induced platelet aggregation at an EC50 of 1.5 microM. The healthy volunteers demonstrated a diurnal variation in platelet aggregability that was high in the morning and low in the evening (66 +/- 10% and 56 +/- 11% respectively, of the percent platelet aggregation induced by epinephrine). The same variation was seen with the platelet aggregation induced by adenosine diphosphate (ADP) (62 +/- 8% [morning] vs. 51 +/- 7% [evening]). After the administration of guanabenz, platelet aggregability was significantly reduced in the morning compared with that before drug administration, when platelet aggregation was induced by epinephrine (49 +/- 9%, p < 0.05) or ADP (48 +/- 7%, p < 0.05), although the plasma levels of catecholamine were unchanged. A suppressive effect of guanabenz on platelet aggregability was observed in the evening, as the platelets were stimulated by epinephrine (38 +/- 9%, p < 0.05), but not by ADP (49 +/- 5%). Findings suggest that guanabenz mainly suppressed the morning enhancement in platelet aggregability, which contributes to the formation of intravascular thrombi. Thus, in addition to its antihypertensive actions, guanabenz may help to reduce the risk of vascular accidents, which frequently occur in the morning.

Adenosine Diphosphate↗
PubMed2001

Suppression of cell proliferation by tissue plasminogen activator during the early phase after balloon injury minimizes intimal hyperplasia in hypercholesterolemic rabbits.

Thrombus formation is a key component of the pathogenesis of restenosis after arterial balloon injury. The purpose of this study was to determine whether intimal hyperplasia could be attenuated by infusion of recombinant tissue plasminogen activator (tPA). Forty-two Kurosawa and Kusanagi hypercholesterolemic rabbits were divided into tPA (n = 20) and control (n = 22) groups, the former receiving 7 days of continuous tPA infusion (0.6 mg/kg/day) via ear veins. The walls of the common iliac arteries were injured using 2.5-mm balloon catheters and then examined histologically 7, 14, 21, and 28 days later. Cell proliferation was assessed by immunohistochemical analysis of proliferating cell nuclear antigen (PCNA), and transforming growth factor (TGF)-beta immunohistochemistry was carried out to estimate cell proliferation and differentiation. It was observed that 28 days after balloon injury, intimal cross-sectional areas in the tPA group were significantly smaller than in controls (0.11 +/- 0.03 mm2 vs. 0.57 +/- 0.08 mm2, p < 0.01), as were ratios of the cross-sectional areas of the intima and media (0.21 +/- 0.07 vs. 1.06 +/- 0.18, p < 0.05). In addition, the numbers of PCNA-positive medial cells were significantly lower (0.06 +/- 0.01 vs. 0.36 +/- 0.08, p < 0.05) and TGF-beta-positive vessel wall areas were significantly smaller in tPA-treated animals 7 days after balloon injury (0.47 +/- 0.28% vs. 4.55 +/- 1.44%, p < 0.05). Thus infusion of tPA after arterial balloon injury appears to decrease medial cell proliferation and suppress intimal hyperplasia.

Animals↗
PubMed2001

Nuclear entry mechanism of rat PER2 (rPER2): role of rPER2 in nuclear localization of CRY protein.

Mammalian PERIOD2 protein (PER2) is the product of a clock gene that controls circadian rhythms, because PER2-deficient mice have an arrhythmic phenotype. The nuclear entry regulation of clock gene products is a key step in proper circadian rhythm formation in both Drosophila and mammals, because the periodic transcription of clock genes is controlled by an intracellular, oscillating, negative feedback loop. The present study used deletion mutants of rat PER2 (rPER2) to identify the functional nuclear localization signal (NLS) in rPER2. The elimination of putative NLS (residues 778 to 794) from the rPER2 fragment resulted in the loss of nuclear entry activity. Adding the NLS to the cytosolic protein (bacterial alkaline phosphatase) translocates the fusion protein to the nuclei. The data indicate the presence of a functional NLS in rPER2. Furthermore, intact rPER2 was preferentially translocated from the cytoplasm to the nucleus when coexpressed with human CRY1 (hCRY1). However, rPER2 mutants lacking a carboxyl-terminal domain could not enter the nucleus even in the presence of hCRY1. In addition, coexpression of the nuclear localization domain (residues 512 to 794) lacking rPER2 and CRY1 changed the subcellular localization of CRY1 from the nucleus to the cytoplasm. In vitro protein interaction studies demonstrated that the carboxyl-terminal domain of rPER2 is essential for binding to CRY1. The data suggested that both the rPER2 NLS and carboxyl-terminal CRY binding domain are essential for nuclear entry of the rPER2-CRY1 complex.

Active Transport, Cell Nucleus↗
PubMed2001

Mr flow measurement in the internal mammary artery-to-coronary artery bypass graft: comparison with graft stenosis at radiographic angiography.

PURPOSE: To evaluate the sensitivity and specificity of breath-hold magnetic resonance (MR) flow measurement for detection of significant stenosis in internal mammary artery bypass grafts. MATERIALS AND METHODS: Twenty-six consecutive patients who had undergone coronary artery bypass surgery were examined. Breath-hold velocity-encoded cine MR images were obtained at the midpoint of the internal mammary artery between its origin from the subclavian artery and the distal anastomosis to the left anterior descending artery. RESULTS: MR images were obtained successfully in 24 patients. At conventional angiography, no significant stenosis was observed in 17 patients (group A), and significant stenosis (diameter > 70%) was observed in seven patients (group B). The mean diastolic-to-systolic peak velocity ratio in group B (0.61 +/- 0.44 [SD]) was significantly lower than that in group A (1.88 +/- 0.96; P <.01). Evaluation of graft stenosis with the diastolic-to-systolic peak velocity ratio revealed a sensitivity of 86% and a specificity of 88%. The mean blood flow rate at baseline in group B (16.9 mL/min +/- 5.5) was significantly lower than that in group A (79.8 mL/min +/- 38.2; P <.01). The sensitivity and specificity of MR blood flow measurement in predicting significant stenosis were 86% and 94%, respectively. The mean pharmacologic flow reserve ratios were 2.00 +/- 1.43 in group A and 1.39 +/- 1.46 in group B (P >.05). CONCLUSION: Fast MR blood flow measurement at baseline is highly useful for predicting significant stenosis in internal mammary arterial grafts.

Aged↗
PubMed2001

tPA via infusion catheters followed by continuous IV infusion for 3 days prevents intimal hyperplasia after balloon injury.

A rabbit model was used to examine the effects of tissue plasminogen activator (tPA) on development of intimal hyperplasia following balloon injury. Thirty-two hereditary hypercholesterolemic (KHC) rabbits underwent percutaneous transluminal coronary artery balloon catheterization and injury to the common iliac artery, after which they were divided into four groups: untreated (control); Dispatch catheterized-30 minutes local saline delivery [D(+)-tPA(-)]; D(+)-30 minutes local tPA delivery (0.6 mg/kg) [D(+)-tPA(30 min)]; and D(+)-30 minutes local tPA + 3 days intravenous infusion (0.6 mg/kg/24 h) [(D(+)-tPA(30 min + 3 d)]. Twenty-eight days later, the intimal cross-sectional areas of all three Dispatch catheterized groups were significantly smaller than those of control groups, as were the intimal/medial area ratios. Moreover, the intima/media ratios of the D(+)-tPA(30 min + 3 d) group were significantly smaller than those of the D(+)-tPA(-) group. Thus, local delivery of tPA via Dispatch catheters followed by continuous intravenous infusion of tPA for 3 days prevented intimal hyperplasia after angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed2001

Cytotoxicity of the hinokitiol-related compounds, gamma-thujaplicin and beta-dolabrin.

Gamma-thujaplicin and beta-dolabrin, the constituents of the wood of Thujopsis dolabrata Sieb. et Zucc. var. hondai showed strong in vitro cytotoxic effects against the human stomach cancer cell lines KATO-III and Ehrlich's ascites carcinoma. The cytotoxic effects of the two compounds against both tumor cell lines were clear when cell growth was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Gamma-thujaplicin and beta-dolabrin at 0.32 microg/ml inhibited cell growth of human stomach cancer KATO-III by 85 and 67%, and Ehrlich's ascites carcinoma by 91 and 75%, respectively. There is no large difference in cytotoxicity between these compounds, but the activity of gamma-thujaplicin was slightly more potent than that of beta-dolabrin. On the other hand, hinokitiol acetate did not show a cytotoxic effect, suggesting that at least a part of the mechanism of the cytotoxic effect of hinokitiol-related compounds is due to metal chelation between the carbonyl group at C-1 and the hydroxyl group at C-2 in the tropolone skeleton of these molecules. The acute toxicities [50% lethal dose (LD50) value: intraperitoneal injection, Van der Waedem] of gamma-thujaplicin and beta-dolabrin in mice were 277 mg/kg and 232 mg/kg, respectively.

Animals↗
PubMed2001

Biological activity of alpha-thujaplicin, the minor component of Thujopsis dolabrata SIEB. et ZUCC. var. hondai MAKINO.

Alpha-thujaplicin, a minor component of Thujopsis dolabrata SIEB. et ZUCC. var. hondai MAKINO, which was synthesized, showed the antibacterial activity, phytogrowth-inhibitory effect, inhibition of carboxypeptidase A and cytotoxic effect. Antibacterial activity of alpha-thujaplicin on Enterococcus faecalis IFO-12965 [minimum inhibitory concentration (MIC): 1.56 microg/ml] was higher than that of gentamicin (MIC: 6.25 microg/ml) used as a positive control. Inhibitory activity of alpha-thujaplicin on carboxypeptidase A [50% inhibitory concentration (IC50): 3.24 x 10(-5) M] was higher than that of 1,10-phenanthroline used as a positive control. Alpha-thujaplicin showed germination inhibition toward the seed of Echinochloa utilis Ohwi et Yabuno even at the low concentration of 10 ppm and its growth inhibitory effect was stronger than that of sodium 2,4-dichlorophenoxyacetate used as a standard. Alpha-thujaplicin at 1.25 microg/ml inhibited cell growth of human stomach cancer KATO-IIl by 86%, and Ehrlich's ascites carcinoma by 87%, respectively. This compound even at the low concentration of 0.32 microg/ml also inhibited cell growth of the former by 66%, and the latter by 75%, respectively. The acute toxicity of alpha-thujaplicin [50% lethal dose (LD50) value: 256 mg/kg] in mice was as strong as those of beta-dolabrin (LD50 value: 232 mg/kg) and gamma-thujaplicin (LD50 value: 277 mg/kg).

Animals↗
PubMed2001

Molecular cloning of horse Hsp90 cDNA and its comparative analysis with other vertebrate Hsp90 sequences.

Heat shock protein 90 (Hsp90), a molecular chaperone, is ubiquitous and involved in numerous cellular processes. To contribute to the relatively small collection of vertebrate Hsp90 sequences in the gene data bank, we cloned and sequenced horse (Equus caballus) Hsp90 alpha and beta cDNAs. This enabled identification of horse-specific primers for development of a convenient PCR-based method that could monitor horse stress tolerance. We analyzed the sequence data comparatively and phylogenetically with other Hsp90 cDNA sequences, and identified vertebrate-specific and isoform-specific conserved regions to facilitate future molecular investigations of Hsp90 functions. We found 4 highly conserved regions to vertebrate Hsp90 exclusively and 27 amino acids conserved among but differing between Hsp90 alpha and Hsp90 beta sequences. Protein-based phylogenetic trees revealed high conservation between mammal species within Hsp90 alpha and beta clusters. Comparison of nucleotide and amino acid substitution levels suggests that horse Hsp90 beta has undergone strong purifying selection, while rat Hsp90 beta and hamster Hsp90 alpha have been positively selected. Surprisingly, fish Hsp90 alpha genes clearly clustered with Hsp90 beta genes, and no distinct placement of fish Hsp90 alpha protein was found. The Hsp90 alpha isoform is apparently the result of beta gene duplication. Our results highlight the importance of organism- and isoform-specific Hsp90 functional analyses in describing the role of Hsp90 in cells.

Amino Acid Sequence↗