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T Sakaguchi

Publications and source records attributed to T Sakaguchi.

At least 55 records · Page 3Linked to original sources
PubMed2000

Ecto-5'-nucleotidase plays a role in the cardioprotective effects of heat shock protein 72 in ischemia-reperfusion injury in rat hearts.

OBJECTIVE: Heat shock protein 72 (HSP72) is involved in the myocardial self-preservation system under several conditions such as ischemia-reperfusion injury or late preconditioning. However, its mechanism is not fully understood. Ecto-5'-nucleotidase is a key enzyme for synthesizing adenosine and plays an important role in ischemic preconditioning. In this study, we tested the hypothesis that ecto-5'-nucleotidase plays a role in the cardioprotection of HSP72. METHODS: Rat hearts (H group, n=6) were transfected with HSP72 gene by an intracoronary infusion of hemagglutinating virus of Japan (HVJ)-liposome complex. Control hearts (C group, n=6) were transfected with the beta-galactosidase gene. Following 30 min of normothermic ischemia, grafts were reperfused using Langendorff apparatus. RESULTS: The activity of ecto-5'-nucleotidase was significantly higher in H group than C group both before and after ischemia-reperfusion (H vs. C; 0.51+/-0.05 vs. 0.29+/-0.06, and 1.41+/-0.15 vs. 0.85+/-0.11 nmol/mg protein/min, P<0.05). H group also showed significant better functional recoveries than C group (P<0.05), as well as less creatine phosphokinase leakage (4.4+/-2.8 vs. 14.2+/-3.4 mU/min, P<0.05) and higher adenosine release (247.5+/-35.1 vs. 54.3+/-1.7 pmol/min, P<0.05). Administration of alpha,beta-methylene adenosine diphosphate (AMP-CP), an inhibitor of ecto-5'-nucleotidase, significantly diminished the tolerance to ischemia-reperfusion injury in H group (P<0.05). CONCLUSION: These results demonstrated that ecto-5'-nucleotidase activated by an overexpression of HSP72 attenuated ischemia-reperfusion injury in the rat myocardium. They suggest that ecto-5'-nucleotidase plays a role in the cardioprotective effects of HSP72 in rat hearts.

Adenosine Diphosphate↗
PubMed2000

Claudins regulate the intestinal barrier in response to immune mediators.

BACKGROUND & AIMS: To determine the functional role of immune mediators in the formation of the intestinal barrier, we have examined the regulation of claudin expression by interleukin (IL)-17 in human intestinal epithelial cells. METHODS: Expression of claudins, extracellular signal-related (ERK) mitogen-activated protein kinases (MAPKs), and activated ERK MAPKs was determined by immunoblotting. Claudin membrane association was assessed by immunohistochemistry and claudin messenger RNA expression by Northern blot analysis. Intestinal epithelial barrier function was characterized through transepithelial electrical resistance and mannitol tracer flux. RESULTS: IL-17 induced the development of a paracellular barrier of T84 cell monolayers. Inhibition of ERK activation with the MEK inhibitor PD98059 blocked IL-17 as well as basal development of tight junctions in T84 cells. IL-17 induced formation of tight junctions correlated with up-regulation of claudin-1 and claudin-2 gene transcription. Inhibition of MEK reduced the activated and basal expression of claudin-2 messenger RNA and protein expression. Functional MEK was required for the expression and membrane association of claudin-2 but not claudin-1 in T84 cells. CONCLUSIONS: MEK activity is required for claudin-mediated formation of tight junctions. IL-17 is able to regulate the intestinal barrier through the ERK MAPK pathway.

Blotting, Northern↗
PubMed2000

Recurrent nerve nodal involvement is associated with cervical nodal metastasis in thoracic esophageal carcinoma.

BACKGROUND: Because three-field dissection for esophageal carcinoma is one of the most invasive operations, this procedure should be selected only when strictly indicated; but there are no useful criteria for it. The goal of this study was to identify the useful clinicopathologic factors for indicating three-field dissection. STUDY DESIGN: In this study, we reviewed the survival of patients after three-field dissection and identified factors associated with metastases in cervical nodes (CN), especially internal jugular nodes and supraclavicular nodes. Eighty-six patients who underwent curative esophagectomy with three-field dissection for squamous cell carcinoma of the thoracic esophagus were enrolled in this study. Survival rates were compared with respect to the presence of nodal metastasis. The relationship between recurrent nerve nodal (RNN) involvement and CN metastasis (bilateral internal jugular nodes, supraclavicular nodes, or both) was examined. Clinicopathologic factors possibly influencing CN metastasis were studied by multivariate logistic regression analysis. RESULTS: The overall 5-year survival rate was 45.1%. The 5-year survival rate for patients without metastatic nodes was 67.5%, for patients with one to four metastatic nodes it was 53.1%, and for patients with five or more it was 9.1 %. The prognosis of those with five or more metastatic nodes was significantly poorer than those of the other two groups. In the positive-node group, the 5-year survival rate for patients with RNN metastasis was 21.7%, and for patients with negative RNN it was 47.0% (p = 0.2). In the positive-node group, the 5-year survival rate for patients with positive CN was 13.7% and for patients with negative CN it was 45.8% (p = 0.01). Fifty-six (88.9%) of 63 patients without RNN metastasis had no CN metastasis in contrast to 13 of 23 patients (56.5%) with RNN metastasis who had no CN metastasis (p = 0.001). The positive predictive value, negative predictive value, sensitivity, and specificity were 43.5%, 88.8%, 58.8%, and 81.2%, respectively. The number of metastatic nodes (5 or more versus 0-4) (odds ratio: 2.9, 95% Confidence Interval (CI) = 1.6-5.5, p = 0.0008) and RNN involvement (odds ratio: 4.5, 95% CI = 1.3-15.9, p = 0.02) were the significant factors associated with CN metastasis in the multivariate analysis. CONCLUSIONS: RNN involvement is associated with CN metastasis as is the number of metastatic nodes and may be an indicator for the selection of three-field dissection in thoracic esophageal carcinoma.

Adult↗
PubMed2000

Molecular mechanism of magnet formation in bacteria.

Magnetic bacteria have an ability to synthesize intracellular ferromagnetic crystalline particles consisting of magnetite (Fe3O4) or greigite (Fe3S4) which occur within a specific size range (50-100 nm). Bacterial magnetic particles (BMPs) can be distinguished by the regular morphology and the presence of an thin organic membrane enveloping crystals from abiologically formed magnetite. The particle is the smallest magnetic crystal that has a regular morphology within the single domain size. Therefore, BMPs have an unfathomable amount of potential value for various technological applications not only scientific interests. However, the molecular and genetic mechanism of magnetite biomineralization is hardly understood although iron oxide formation occurs widely in many higher animals as well as microorganisms. In order to elucidate the molecular and genetic mechanisms of magnetite biomineralization, a magnetic bacterium Magnetospirillum sp. AMB-1, for which gene transfer and transposon mutagenesis techniques had been recently developed, has been used as a model organism. Several findings and information on the BMPs formation process have been obtained within this decade by means of studies with this model organism and its related one. Biomineralization mechanism and potential availability in biotechnology of bacterial magnets have been elucidated through molecular and genetic approach.

Journal Article↗
PubMed2000

Involvement of the zinc-binding capacity of Sendai virus V protein in viral pathogenesis.

The V protein of Sendai virus (SeV) is nonessential to virus replication in cell culture but indispensable to viral pathogenicity in mice. The highly conserved cysteine-rich zinc finger-like domain in its carboxyl terminus is believed to be responsible for this viral pathogenicity. In the present study, we showed that the cysteine-rich domain of the SeV V protein could actually bind zinc by using glutathione-S-transferase fusion proteins. When the seven conserved cysteine residues at positions 337, 341, 353, 355, 358, 362, and 365 were replaced individually, the zinc-binding capacities of the mutant proteins were greatly impaired, ranging from 22 to 68% of that of the wild type. We then recovered two mutant SeVs from cDNA, which have V-C(341)S and V-C(365)R mutations and represent maximal and minimal zinc-binding capacities among the corresponding mutant fusion proteins, respectively. The mutant viruses showed viral protein synthesis and growth patterns similar to those of wild-type SeV in cultured cells. However, the mutant viruses were strongly attenuated in mice in a way similar to that of SeV V(DeltaC), which has a truncated V protein lacking the cysteine-rich domain, by exhibiting earlier viral clearance from the mouse lung and less virulence to mice. We therefore conclude that the zinc-binding capacity of the V protein is involved in viral pathogenesis.

Amino Acid Sequence↗
PubMed2000

Abdomen, pelvis, and extremities: diagnostic accuracy of dynamic contrast-enhanced turbo MR angiography compared with conventional angiography-initial experience.

To determine the value of contrast material-enhanced three-dimensional turbo magnetic resonance (MR) angiography compared with conventional cut-film or digital subtraction angiography for evaluating arterial stenosis in the abdomen, pelvis, and extremities. For detection of significant stenosis, MR angiography had 91% sensitivity and 89% specificity. This technique is highly sensitive in lesion detection, but stenosis tended to be overestimated.

Abdomen↗
PubMed2000

[Availability of antibacterial towels and fabrics against enterohemorrhagic Escherichia coli].

OBJECTS: After outbreaks of enterohemorrhagic Escherichia coli, various varieties of antibacterial kitchen and table materials are being used in Japan. The actual of availability of towels and fabrics, designated as antibacteria, against enterohemorrhagic E. coli was evaluated. METHODS: For an indicator strain a clinically isolated strain of E. coli O157:H7 C2 in Canada was utilized. Material kept in a tube was autoclaved at 121 degrees C for 15 mins, and 200 microliters of the bacterial culture was inoculated on the material, and cultured at 35 degrees C for an adequate interval. Colony forming units (CFU) of the materials were estimated. We also studied bactericidal effects of copper-fixed towels after washing. Materials without antibacterial processing or white cotton towels were used as controls. RESULTS: CFU of E. coli on silver- or copper-fixed materials at 18 hrs after inoculation were markedly decreased, compared to CFU of bacteria on the controls at 0 hr after inoculation. These materials were found to have bactericidal activity. Three materials of 23 samples were found to have bacterial inhibitory activity, because CFU of bacteria on the 3 materials at 18 hrs after inoculation were less than CFU of bacteria on the controls at 18 hrs. Thirteen materials (56.5%) were found to have no evident bactericidal nor inhibitory activity. CFU of silver- or copper-fixed materials were clearly decreased at 3 hrs and 20 mins after inoculation, respectively. It was also recognized that bactericidal activity was sustained at 18 hrs after inoculation even after the copper-fixed towel was washed 50 times. CONCLUSION: Evaluation of bactericidal effects of towels and fabrics, that claim to be antibacterial, showed that a few materials had bactericidal or inhibitory activity. Consumers must not have too much confidence in claims of a product being antibacteria. Even if antibacterial materials are available, the most important measure for us is to wash sufficiently and maintain sanitary conditions.

Colony-Forming Units Assay↗
PubMed2000

[Surgical treatment of unruptured cerebral aneurysms and complications in patients with ischemic cerebrovascular disease].

Patients who have unruptured intracranial aneurysms associated with ischemic cerebrovascular disease are a high-risk group for surgery. We have done clipping surgery in 15 patients among 40 with ischemic cerebrovascular disease. The criteria for surgery included an age below 65 years, CBF of more than 35 ml/100 g/min, and favorable ADL comparable to Rankin score 0-III. Two patients received simultaneous aneurysm clipping and superficial-middle cerebral artery anastomosis. Only one patient suffered from ischemia-related permanent neurological worsening, and one had direct optic nerve injury. Surgical mortality was 0%, and morbidity was 15%. There were two patients who had transient neurological worsening. These results suggest that surgical treatment of unruptured cerebral aneurysms is not contraindicated in patients with ischemic brain disease, but careful selection and careful perioperative management are mandatory for preventing surgical complications.

Activities of Daily Living↗
PubMed2000

[Vascular anastomoses in free jejunal reconstruction to the neck vessels: an experience of consecutive 20 cases without using surgical microscope].

Twenty consecutive cases of pharyngoesophageal cancer who underwent free jejunal reconstruction were reported. The common carotid or external carotid artery was used for a feeder of the free graft. The internal jugular vein were served as a drainage vein. All anastomoses were performed in an end-to-side fashion without using surgical microscopes. Mean carotid artery clamping time was 16 minutes and no neurological complications were noticed postoperatively. Graft failure was occurred in 1 patient. The presenting technique, showing 95% success rate, is recommended as a simple option for vascular anastomosis in free jejunal reconstructive surgery.

Anastomosis, Surgical↗
PubMed1999

Application of real-time radiation dosimetry using a new silicon LET sensor.

A new type of real-time radiation monitoring device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs), has been developed and tested on-board the Space Shuttle mission STS-84. The test succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2 keV/micrometer to 600 keV/micrometer for 178 h. The Shuttle cruised at an altitude of 300 to 400 km and an inclination angle of 51.6 degrees for 221.3 h, which is equivalent to the International Space Station orbit. The LET distribution obtained for particles was investigated by separating it into galactic cosmic ray (GCR) particles and trapped particles in the South Atlantic Anomaly (SAA) region. The result shows that the contribution in dose-equivalent due to GCR particles is almost equal to that from trapped particles. The total absorbed dose rate during the mission was 0.611 mGy/day; the effective quality factor, 1.64; and the dose equivalent rate, 0.998 mSv/day. The average absorbed dose rates are 0.158 mGy/min for GCR particles and 3.67 mGy/min for trapped particles. The effective quality factors are 2.48 for GCR particles and 1.19 for trapped particles. The absorbed doses obtained by the RRMD-III and a conventional method using TLD (Mg(2)SiO(4)), which was placed around the RRMD-III were compared. It was found that the TLDs showed a lower efficiency, just 58% of absorbed dose registered by the RRMD-III.

Calibration↗
PubMed1999

Disparity of cell swelling and rapid neuronal death by excitotoxic insults in rat hippocampal slice cultures.

The rapidly (< 1 h) developing neuronal death induced by a 15-min-exposure to N-methyl-D-aspartate (NMDA) in rat hippocampal slice cultures is associated with cell swelling. We examined whether the swelling directly leads to neuronal death. The rapid neuronal death assayed by propidium iodide was Cl(-)-dependent, as reported for the cell swelling. However, the dose-dependence for NMDA-induced neuronal death differed from that for the cell swelling. Also, cell swelling alone induced by hypotonic insults led to neuronal death only when the cell size increased far more than the extent achieved by NMDA insults. Moreover, contrary to the previous notion, the rapid neuronal death was Ca2+-dependent. Thus, the primary cause of the rapid neuronal death induced by NMDA cannot be attributed to cell swelling.

Animals↗
PubMed1999

Double-layered membrane vesicles released from mammalian cells infected with Sendai virus expressing the matrix protein of vesicular stomatitis virus.

The matrix (M) protein of vesicular stomatitis virus (VSV) was reported to form vesicles on the cell surface and subsequently to be released into the cultured medium when expressed from cDNA by virus vectors. To further investigate VSV M activity, we generated a recombinant Sendai virus (SeV) expressing the VSV M protein (SeV-M(VSV)). When cells were infected with SeV-M(VSV), VSV M was found abundantly in the culture medium. Electron microscopy demonstrated the budding of two-membraned vesicles (>/= 0.8 microm in diameter) from the infected cells. The outer membrane of the vesicle was derived from the plasma membrane and the inner one possibly derived from the membrane of an intracellular vesicle. Immuno-gold labeling showed that VSV M was exclusively located in a double-layered region. The released membranes were divided into three parts: the VSV M vesicles with SeV F and HN glycoproteins, SeV particles, and vesicles associated with the cytosolic components. The last abundantly contained phosphorylated SeV matrix (M) protein, which is not released in a usual SeV infection. Furthermore the VSV M protein expressed without using a virus vector was efficiently released into the culture medium. These results suggest that the VSV M protein has a budding activity per se and that SeV proteins are passively involved in the release of VSV M.

Animals↗
PubMed1999

Measurement of the directional distribution of incident particles in the Shuttle-Mir mission orbit.

The measurement of the directional distribution of incident particles was made by using the Real time Radiation Monitoring Device (RRMD)-III placed inside the Space Shuttle STS-84 cruised at an altitude of 400 km and an inclination angle of 51.6 degrees, which are the same as the cruising orbit of the International Space Station (ISS). The directional distributions of incident particles were evaluated over the observed linear energy transfer (LET) range (1-100 keV/micrometers). The pitch angle distribution is also obtained using the geomagnetic model of IGRF-95. The result is roughly in good agreement with the distribution obtained by the VF1-MIN anisotropy model calculation within the present experimental errors, if the shielding distribution is assumed to be uniform.

Anisotropy↗
PubMed1999

Flux of the L-serine metabolism in rat liver. The predominant contribution of serine dehydratase.

L-Serine metabolism in rat liver was investigated, focusing on the relative contributions of the three pathways, one initiated by L-serine dehydratase (SDH), another by serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT), and the other involving serine hydroxymethyltransferase and the mitochondrial glycine cleavage enzyme system (GCS). Because serine hydroxymethyltransferase is responsible for the interconversion between serine and glycine, SDH, SPT/AGT, and GCS were considered to be the metabolic exits of the serine-glycine pool. In vitro, flux through SDH was predominant in both 24-h starved and glucagon-treated rats. Flux through SPT/AGT was enhanced by glucagon administration, but even after the induction, its contribution under quasi-physiological conditions (1 mM L-serine and 0.25 mM pyruvate) was about (1)/(10) of that through SDH. Flux through GCS accounted for only several percent of the amount of L-serine metabolized. Relative contributions of SDH and SPT/AGT to gluconeogenesis from L-serine were evaluated in vivo based on the principle that 3H at the 3 position of L-serine is mostly removed in the SDH pathway, whereas it is largely retained in the SPT/AGT pathway. The results showed that SPT/AGT contributed only 10-20% even after the enhancement of its activity by glucagon. These results suggested that SDH is the major metabolic exit of L-serine in rat liver.

Adenosine Triphosphate↗