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Biomedical subjects

T Sakai

Publications and source records attributed to T Sakai.

At least 325 records · Page 18Linked to original sources
PubMed1999

A relationship between urine specific gravity and hyponatremia in hospitalized schizophrenic patients.

The relationship between urine specific gravity (USG) and the incidence of polydipsia/hyponatremia in hospitalized schizophrenic patients was examined. On the basis of five independent USG values, we identified 49% (35 out of 72) of male and 22% (8 out of 37) of female patients with hyposthenuria (mean USG < or = 1.008). Review of 2 years of records of routine laboratory examinations identified 12 males with hyponatremia, 11 males with borderline hyponatremia, and 49 males with normal values; among female patients, only one patient with hyponatremia and three patients with borderline values were identified. A significantly lower mean USG (1.003 +/- 0.001) for the male patients with hyponatremia compared with the male patients with normal serum sodium data (1.011 +/- 0.005) was observed. All of the male patients with hyponatremia, as well as 18 of the 49 male patients with normal serum sodium values, exhibited hyposthenuria. The USG values of all the patients with hyponatremia were consistently quite low (< or = 1.005), whereas 14 of the 18 normonatremia/hyposthenuria patients had normal USG values (i.e. > or = 1.009) in at least one of five determinations; the mean USG values for most (16 of 18) of the normonatremia/hyposthenuria patients ranged from 1.006 to 1.008. Thus, many hospitalized schizophrenic patients exhibit hyposthenuria of varying degrees, but consistently low USG values are most suggestive of the risk of polydipsia/hyponatremia.

Adult↗
PubMed1999

The ubiquitous transcription factor NF-Y positively regulates the transcription of human p27Kip1 through a CCAAT box located in the 5-upstream region of the p27Kip1 gene.

Abnormally low levels of the cyclin-dependent kinase inhibitor p27Kip1 are found frequently in human carcinomas, and these levels correlate directly with both histological aggressiveness and patient mortality. p27Kip1 is haplo-insufficient for tumor suppression. Thus, p27Kip1 may be a useful molecule for the development of cancer therapies. To know the possible mechanisms underlying transcriptional control, we previously cloned the promoter region of human p27Kip1 gene. We report here the characterization of the 5'-regulatory region of the human p27Kip1 gene. Promoter analysis using 5'-deletion mutants revealed that a 39-bp region between -549 and -511 was required for maximal promoter activity. Point mutation analysis revealed that a CCAAT box within this region was essential for promoter activity. Gel shift assays and cotransfection experiments using a dominant negative form of the NF-Y transcription factor showed that NF-Y directly regulates p27Kip1 transcription through this CCAAT box. This finding might provide a clue to approach the mechanism of tumorigenesis.

Base Sequence↗
PubMed1999

Synergism among lysophosphatidic acid, beta1A integrins, and epidermal growth factor or platelet-derived growth factor in mediation of cell migration.

GD25 cells lacking the beta1 integrin subunit or expressing beta1A with certain cytoplasmic mutations have poor directed cell migration to platelet-derived growth factor (PDGF) or epidermal growth factor (EGF), ligands of receptor tyrosine kinases, or to lysophosphatidic acid (LPA), a ligand of G-protein-coupled receptors (Sakai, T., Zhang, Q., Fässler, R., and Mosher, D. F. (1998) J. Cell Biol. 141, 527-538 and Sakai, T., Peyruchaud, O., Fässler, R., and Mosher, D. F. (1998) J. Biol. Chem. 273, 19378-19382). We demonstrate here that LPA synergizes with signals induced by beta1A integrins and ligated EGF or PDGF receptors to modulate migration. When LPA was mixed with EGF or PDGF, migration was greater than with EGF or PDGF alone. The enhancement was greater for beta1A-expressing cells than for beta1-null cells. Cells expressing beta1A with mutations of prolines or tyrosines in conserved cytoplasmic NPXY motifs had blunted migratory responses to mixtures of LPA and EGF or PDGF. The major effects on beta1A-expressing cells of LPA when combined with EGF or PDGF were to sensitize cells so that maximal responses were obtained with >10-fold lower concentrations of growth factor and increase the chemokinetic component of migration. Sensitization by LPA was lost when cells were preincubated with pertussis toxin or C3 exotransferase. There was no evidence for transactivation or sensitization of receptors for EGF or PDGF by LPA. EGF or PDGF and LPA caused activation of mitogen-activated protein kinase by pertussis toxin-insensitive and -sensitive pathways respectively, but activation was not additive. These findings indicate that signaling pathways initiated by the cytoplasmic domains of ligated beta1A integrins and tyrosine kinase receptors interact with signaling pathways initiated by LPA to facilitate directed cell migration.

ADP Ribose Transferases↗
PubMed1999

Syntheses of biotinylated alpha-galactosylceramides and their effects on the immune system and CD1 molecules.

A representative alpha-galactosylceramide (alpha-GalCer), KRN7000, has strong immunostimulatory and antitumor activity. Recent studies demonstrated that KRN7000-pulsed antigen-presenting cells (APC) can activate natural killer T (NKT) cells, a novel T-cell lineage, and CD1d molecules on APC play an important role in the activation of NKT cells. However, it remains unclear whether alpha-GalCers actually bind to CD1d molecules. To address this question, we synthesized three kinds of biotinylated alpha-GalCer and a biotinylated beta-GalCer and found that the biotinylated alpha-GalCers significantly stimulate the proliferation of murine spleen cells, but the biotinylated beta-GalCer does not and that all biotinylated compounds bind to CD1d molecules.

Animals↗
PubMed1999

Lipid bodies and lipid body formation in an oleaginous fungus, Mortierella ramanniana var. angulispora.

Mortierella ramanniana var. angulispora accumulates triacylglycerol (TG) in lipid bodies. Studies on lipid transport into lipid bodies are essential for elucidating mechanisms of lipid body formation. We used fluorescent dyes and fluorescent lipid analogs to visualize lipid body formation with a confocal laser scanning microscope. Different sizes of lipid bodies were stained by Nile red, a lipid body marker - one with a diameter of about 1 micrometer and the other with a diameter of about 2-3 micrometers. Lipid bodies matured into larger ones with culture. To metabolically monitor lipid bodies, we used 1-palmitoyl, 2-[5-(5,7-dimethyl boron dipyrromethene difluoride)-1-pentanoyl]-phosphatidic acid (C5-DMB-PA), and C5-DMB-phosphatidylcholine (C5-DMB-PC). These were taken up into fungal cells and incorporated into intracellular organelles at 30 degrees C. C5-DMB-PA was quickly incorporated into lipid bodies while C5-DMB-PC was initially incorporated into internal membranes, presumably endoplasmic reticulum membranes, and fluorescence was then gradually transported into lipid bodies. The transport of fluorescent lipids accompanied their metabolism into diacylglycerol (DG) and TG, which, taken together with the fluorescence distribution, suggested that conversion to TG was not necessary for transport into lipid bodies. It is likely that the synthesized DG was mainly located in lipid bodies and the conversion to TG took place in lipid bodies. C5-DMB-PA and C5-DMB-PC were converted to DG and TG in the membrane and lipid body fractions of this fungus, which agreed with in vivo metabolism of these fluorescent lipids and in vitro enzyme activity related to PA and PC metabolism. These results indicate that transport and metabolism of C5-DMB-PA and C5-DMB-PC represent two different routes for lipid body formation in this fungus.

Animals↗
PubMed1999

Type I collagen metabolites as tumor markers in patients with lung carcinoma.

BACKGROUND: Components of the extracellular matrix play a fundamental role in the process of tumor invasion. The objective of this study was to evaluate the value of Type I collagen metabolites as tumor markers in patients with lung carcinoma. METHODS: In this study, the serum concentrations of the cross-linked carboxyterminal telopeptide of Type I collagen (ICTP) and the aminoterminal propeptide of Type I collagen (PINP) were measured in 59 consecutive patients with lung carcinoma. The blood concentrations of neuron-specific enolase (NSE), carcinoembryogenic antigen (CEA), sialyl Le-1 antigen (SLX), squamous cell carcinoma antigen (SCC), and D-dimer were also evaluated. Data obtained on 18 age-matched healthy subjects and 12 age-matched patients with benign lung disease were available for comparison. RESULTS: The serum concentrations of PINP were significantly higher in patients with lung carcinoma than in age-matched controls. Prechemotherapy values of PINP and ICTP were significantly increased in patients who did not respond to chemotherapy compared with those who did respond. PINP and ICTP were significantly correlated with clinical stage, extent of bone metastasis, survival time, and D-dimer. PINP was also significantly correlated with tumor size. ICTP was significantly correlated with CEA, SLX, SCC, and NSE. PINP also tended to correlate with these tumor-associated glycoproteins. PINP had a better receiver operating characteristic curve than ICTP. The specificity of PINP (79%) for the diagnosis of bone metastasis was superior to that of ICTP (58%). CONCLUSIONS: The results of this study showed that, in addition to the important information that ICTP and PINP provide about the tumor cell-extracellular matrix interaction, they appear to be of great value as adjunct tools for the diagnosis of bone metastasis and as markers of the clinical response to therapy, clinical progression, and prognosis in lung carcinoma patients. However, more studies must be conducted to evaluate further the utility of these markers before their application in clinical practice.

Adult↗
PubMed1999

High-performance liquid chromatographic determination of 1,3-diethyl-2-thiobarbituric acid--malonaldehyde adduct in fish meat.

The reaction conditions of 1,3-diethyl-2-thiobarbituric acid (DETBA)-malonaldehyde (MA) adduct formation were examined in order to analyze MA in fish tissue by high-performance liquid chromatography. A reaction mixture containing 4 mM butyl hydroxytoluene was heated at 100 degrees C for 150 min and the DETBA-MA adduct formed was separated by a Inertsil ODS column for 20 min. The detection limit was 5 pmol.

Chromatography, High Pressure Liquid↗
PubMed1999

Spatiotemporal patterns of activity in an intact mammalian network with single-cell resolution: optical studies of nicotinic activity in an enteric plexus.

Multiple Site Optical Recording of Transmembrane Voltage (MSORTV) has been used to measure, continuously and simultaneously, the spontaneous electrical activity from all of the neurons in individual ganglia or up to five interconnected ganglia of the submucous plexus of the guinea pig small intestine. These are the first optical recordings of electrical activity with single-cell resolution from a mammalian nervous system. They are used to investigate the effects of acute and chronic application of nicotine on the firing patterns of this neural network containing important cholinergic components. After washout of acutely applied nicotine, the firing rates of selected neurons were dramatically elevated. These results suggest that nAChRs that reversibly desensitize after exposure to nicotine may be responsible for the enhancement of activity that is observed after a brief application of this agonist. In addition, immunostaining with monoclonal antibodies was used to localize alpha3/alpha5, alpha7, and beta2 nAChR subunits, and the results demonstrate the prevalence of alpha3/alpha5. It is this alpha3-containing nAChR subtype that probably accounts for most of the excess activity elicited by nicotine application.

Animals↗
PubMed1999

Two-step spreading mode of human glioma cells on fibrin monomer: interaction of alpha(v)beta3 with the substratum followed by interaction of alpha5beta1 with endogenous cellular fibronectin secreted in the extracellular matrix.

Glioma cells, a human astrocyte-derived glioma cell line, were found to spread on immobilized fibrin monomer but not on fibrinogen. As a synthetic RGD-containing peptide GRGDSP blocked the spreading of glioma cells on fibrin monomer concentration-dependently, the spreading was thought to be mediated by their cell surface receptors. In fact, both the beta1- and beta3-integrins were located at 3 hours of incubation in the cytoplasmic areas and at 24 hours in the peripheral areas as well, although their distribution profiles were not necessarily identical with each other by immunohistochemical studies. By cytometry analysis utilizing respective monoclonal antibodies against alpha5- and alpha v-integrins, we were able to show expression of alpha5 (alpha5beta1) but not alpha v on the surface of glioma cells at 24 hours of incubation on immobilized fibrin monomer. A 50-kDa transmembrane protein designated as integrin-associated protein (IAP) known to be closely associated with the beta3-integrin was also located in the cytoplasmic and apical areas of spreading glioma cells, but its specific antibody B6H12 failed to inhibit the spreading. Thus, the IAP-dependent involvement of beta3-integrin may not be predominantly involved in the glioma cell spreading on fibrin monomer. As an anti-alpha v beta3 antibody LM 609 inhibited the spreading of glioma cells partially at approximately 35%, the spreading seems to proceed in a two-step mode, i.e., via alpha vbeta3 with its ligand exposed in fibrin monomer, and then via alpha5beta1 with endogenous cellular fibronectin secreted from the glioma cells themselves. In fact, the cellular fibronectin was clearly visualized by confocal microscopic observation. Thus, upon contact with fibrin in clots formed at traumatized areas in the brain, for example, glioma cells may have a chance to adhere to and spread via alpha v beta3 with fibrin monomer and then via alpha5beta1 with endogenous cellular fibronectin in the extracellular matrices.

Cell Adhesion↗
PubMed1999

Effects of 3alpha- and 3beta-galactosylated alpha-galactosylceramides on the immune system.

We compared effects of alpha-galactosylceramide (alpha-GalCer) and its 3alpha- or 3beta-galactosylated derivatives on the proliferation of murine spleen cells. The 3alpha-galactosylated alpha-GalCer showed stronger proliferative response than the parental alpha-GalCer, but the 3beta-galactosylated alpha-GalCer possessed weaker activity than the alpha-GalCer. In addition, alpha-Gal-3-Cer did not show immunostimulatory activity.

Adjuvants, Immunologic↗
PubMed1999

Functional beta1-integrins release the suppression of fibronectin matrix assembly by vitronectin.

beta1-null GD25 fibroblasts adherent to vitronectin fail to bind the N-terminal 70-kDa matrix assembly domain of fibronectin or to assemble fibronectin (Sakai, T., Zhang, Q., Fässler, R., and Mosher, D. F. (1998) J. Cell Biol. 141, 527-538). We have made four observations that extend this finding. First, the presence of vitronectin on a substrate that otherwise can support fibronectin assembly has a dominant-negative effect on assembly. Second, the dominant-negative effect is lost when active beta1A is expressed. Third, beta1A containing the extracellular D130A inactivating mutation has a dominant-negative effect on fibronectin assembly. Fourth, beta1-null cells adherent to vitronectin are flat and lack filopodia, whereas beta1-null cells adherent to fibronectin or beta1A-expressing cells adherent to either vitronectin or fibronectin are contracted and exhibit numerous filopodia. These results reveal, therefore, that GD25 cells adherent to vitronectin can only assume a shape suitable for assembly of fibronectin when there is a countervailing signal from functional beta1-integrins.

Amino Acid Sequence↗
PubMed1999

Effects of mean and swing pressures on piston-type high-frequency oscillatory ventilation in rabbits with and without acute lung injury.

To determine whether low mean airway pressure (MAP) and/or stroke volume (SV) settings cause lung injury during piston-type high-frequency oscillatory ventilation (HFOV), we investigated the influence of various combinations of MAP and SV on the amplitude of the pressure swing at four different sites in the normal lung of rabbits. We also examined the effects of these factors on progression of lung injury in lavaged surfactant-deficient lungs. We measured changes in the mean pressure (MP) and swing pressure (SP) during HFOV at MAPs ranging between 5-30 cm H2O in combination with SVs ranging from 5-30 mL in 13 rabbits at four different sites: 1) the proximal airway, 2) the distal end of the endotracheal tube, 3) the bronchi, and 4) the pleural space. Lung lavage was performed in 8 rabbits and differences in MP and SP between normal and surfactant-deficient rabbits were investigated. In the remaining 5 rabbits, lungs were lavaged and subjected to two trials of sustained inflation to 30 cm H2O for 15 s to reverse atelectasis, and the resulting SP was measured. In normal lungs, SP increased at the bronchial and pleural sites as MAP was increased. Alterations in SV did not affect MP in normal or lavaged lungs. In the lavages, surfactant-deficient lungs at MAPs < or = 15 cm H2O, there were significant increases in SP at the distal end of the endotracheal tube and the bronchial sites. SP decreased to the prelavaged level following sustained inflation to 30 cm H2O for 15 s. We conclude that low MAP settings are insufficient to open alveoli in the low-compliance lung and allow for development of atelectasis rather than air trapping. SP was markedly increased in the presence of atelectasis, possibly leading to excessive expansion of the airway. In the clinical setting, such overexpansion of the distal airways may contribute to lung injury. Our findings suggest that physicians should use caution in reducing MAP during piston-type HFOV until lung compliance has normalized, especially in infants with respiratory distress syndrome.

Air Pressure↗
PubMed1999

Contrast-enhanced magnetic resonance imaging in a nontraumatic rabbit osteonecrosis model.

We investigated early osteonecrosis using in vivo magnetic resonance imaging in a nontraumatic rabbit model of serum-sickness osteonecrosis in which osteonecrosis was induced after two intravenous injections of horse serum with a 3-week interval. One week (group A, 17 rabbits) and 3 weeks (group B, 13 rabbits) after the second serum injection, coronal magnetic resonance images of the femur were obtained and it was removed for histological study. Some of the necrotic lesions in the diaphysis were detected on T1-weighted, T2-weighted, or fat-suppression T1-weighted images (six of 24 necrotic lesions in group A and 16 of 18 in group B), and all of the necrotic lesions in the epiphysis, metaphysis, and diaphysis were detected on T1-weighted or fat-suppression T1-weighted images enhanced with gadolinium-diethylene triamine pentaacetic acid. All focal homogeneous enhanced areas on T1-weighted or fat suppression T1-weighted images corresponded to necrotic lesions (22 of 24 necrotic lesions in group A and 18 of 18 in group B); the contours of the enhanced areas were displayed more clearly on the fat-suppression T1-weighted than on the T1-weighted images. The fat-suppression T1-weighted image enhanced with gadolinium-diethylene triamine pentaacetic acid was thus the most sensitive and specific of five kinds of magnetic resonance images for the detection of early necrotic lesions. The results suggest that this image may be useful for early diagnosis of clinical osteonecrosis and for obtaining information about the pathomechanism of osteonecrosis.

Animals↗
PubMed1999

Effect of lomerizine, a new Ca(2+)channel blocker, on the microcirculation in the optic nerve head in conscious rabbits: a study using a laser speckle technique.

We examined the effect of a new Ca(2+)channel blocker, lomerizine (KB-2796), and compared it with that of nilvadipine, on the optic nerve head circulation in conscious rabbits using a laser speckle method. Lomerizine (0.03, 0.1 and 0.3 mg kg(-1), i.v.) and nilvadipine (0.003, 0.01 and 0.03 mg kg(-1), i.v.) each significantly increased the normalized blur values (an index of tissue blood velocity) in the optic nerve head in a dose-dependent manner. Neither lomerizine nor nilvadipine caused a significant change in intraocular pressure. Lomerizine produced no significant change in mean arterial blood pressure, although at 0.3 mg kg(-1), i. v. heart rate was significantly increased 5 min after its administration. In contrast, nilvadipine significantly decreased mean arterial blood pressure at 5 to 15 min after its administration and increased heart rate at 5-30 min after its administration (both effects being dose-dependent). Our results indicate that while lomerizine, like nilvadipine, increased tissue blood velocity in the optic nerve head, it did not affect mean arterial blood pressure at the doses that affected optic nerve head circulation, unlike nilvadipine. The plasma concentration of lomerizine (free base) obtained from rabbits at 15 min after administration at a dose of 0. 03 mg kg(-1)i.v., when time there was a significant increase in tissue blood velocity in the optic nerve head, was very similar to plasma concentration with healthy subjects receiving lomerizine at 10 mg (5 mgx2) day(-1), p.o., a dose that achieved a significant reduction in the frequency and mean duration of headache attacks but did not affect the blood pressure or heart rate. These results suggest that lomerizine may be clinically effective in favorably affecting the optic nerve circulation without producing systemic effects such as the hypotension seen during treatment with other Ca(2+)channel blockers.

Animals↗
PubMed1999

An external ion microbeam for studies of biological samples.

A new external ion-beam system was developed and combined with a light ion-microbeam system in JAERI Takasaki. The system is designed for micro-particle-induced X-ray emission analysis of biological samples in air environment with 1 micron spatial resolution. One of the most serious problems in keeping such a high spatial resolution is multiple scattering in a beam exit window. Thin Kapton film (7.5 microns thick) was adopted as the exit window as well as a sample backing foil to minimize the distance between the film and samples. The lifetime of the foil under ion irradiation and spatial resolution of the external microbeam were investigated. The results shows that the film can endure sufficient long-time irradiation to take elemental maps and the resolution can be kept nearly 1 micron.

Biological Assay↗
PubMed1999

Stem length and canal filling in uncemented custom-made total hip arthroplasty.

We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio.

Adult↗