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Biomedical subjects

S Takagi

Publications and source records attributed to S Takagi.

At least 163 records · Page 9Linked to original sources
PubMed1998

Mild hypothermia disturbs regional cerebrovascular autoregulation in awake rats.

The effects of mild hypothermia on regional CBF (rCBF) and autoregulation were investigated in 60 awake and spontaneously breathing Wistar rats. They were divided into normothermic (rectal and brain temperatures: 37.0 +/- 0.5 degrees C) and mildly hypothermic (33.0 +/- 0.5 degrees C) groups the temperature of the latter group was controlled by cooling a lead cast around each rat with ice-cold water. rCBF was measured by means of an autoradiographic technique with 14C-iodoantipyrine. In normothermia, rCBF in most of the supratentorial cortical regions was maintained down to a mean arterial blood pressure (MABP) of 50 mmHg, produced by exsanguination, while rCBF in most of the brain stem regions showed a tendency to increase despite this reduction of MABP (predysautoregulatory overshoot of CBF). In the mildly hypothermic group, pre-exsanguination rCBF values were lower than those in normothermia, and rCBF in all brain regions declined significantly in proportion to decreasing MABP, produced by exsanguination. It is, therefore, concluded that mild hypothermia disturbs cerebrovascular autoregulation in awake rats.

Animals↗
PubMed1998

Favorable strategy for the ostial lesion of the left anterior descending coronary artery: influence on narrowing of circumflex coronary artery.

We examined the effectiveness of Palmaz-Schatz (P-S) stent and directional coronary atherectomy (DCA) in ostial lesions of left anterior descending arteries (LAD). The P-S stent was implanted in 11 cases at LAD ostial lesions, and DCA was performed in 13 cases. Percent stenosis and vessel diameter at the target site and the ostium of the circumflex coronary artery (LCX) were measured before and after the procedure. The initial success rate was 100% in both groups. No major complication occurred. LAD ostial lesions were improved from 81.3+/-3.4% to -8.1+/-5.7% by P-S stent and from 82.8+/-2.6% to -2.7+/-3.9% by DCA. LCX ostial vessel diameter was not changed by DCA (from 3.0+/-0.2 mm to 3.1+/-0.3 mm); however, it was significantly decreased by P-S stent (from 2.9+/-0.2 mm to 2.6+/-0.2 mm, P < 0.01). When the angle of LAD and LCX was < or = 80 degrees from the view of RAO 30 degrees and Caudal 30 degrees, the LCX ostium was significantly narrowed by stenting at LAD ostium (P < 0.01). These findings indicate that both the P-S stent and DCA are effective and safe therapies for LAD ostial lesions in cases with LAD-LCX angle > 80 degrees. In cases with LAD-LCX angle < or = 80 degrees, however, DCA is a favored therapy rather than P-S stenting to avoid narrowing of the LCX ostium.

Atherectomy, Coronary↗
PubMed1998

Successful predilation of a resistant, heavily calcified lesion with cutting balloon for coronary stenting: a case report.

A 65-year-old man with a restenotic lesion of the mid LAD was scheduled for Wiktor stent placement. The IVUS revealed circumferential severe calcification. Two conventional, non-compliant angioplasty balloons inflated to high pressures failed to achieved sufficient dilatation and both ruptured. At this point, we selected high pressure inflation of the Cutting Balloon. The Cutting Balloon achieved adequate dilation for stenting and proved to be useful in predilating a circumferential, heavily calcified lesion.

Aged↗
PubMed1998

BoneSource hydroxyapatite cement: a novel biomaterial for craniofacial skeletal tissue engineering and reconstruction.

BoneSource-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems.

Animals↗
PubMed1998

A lymphocyte-specific CC chemokine, secondary lymphoid tissue chemokine (SLC), is a highly efficient chemoattractant for B cells and activated T cells.

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine expressed mainly in lymph nodes, appendix and spleen, and specifically chemotactic for lymphocytes (Nagira et al., J. Biol. Chem. 1997. 272: 19518-19524). Here, we carried out transendothelial migration assays to determine the classes and subsets of lymphocytes migrating toward SLC. SLC attracted freshly isolated B cells with high efficiency and T cells modestly. Thus, SLC is the first CC chemokine with a strong chemotactic activity on fresh B cells. Among T cell types and subsets, SLC broadly attracted CD4+ and CD8+ cells, CD45RO- (naive) and CD45RO+ (memory) cells, and CD26high (activated) and CD26low- (resting) cells. SLC also attracted both L-selectin+ and L-selectin- subpopulations of various T cell subsets and B cells. Furthermore, mitogenic stimulation strongly enhanced migratory responses of T cells and B cells toward SLC. By in situ hybridization, SLC mRNA was detected in the cortical parafollicular regions (the T cell areas) of a lymph node and an appendix. Collectively, SLC may be a basic chemokine supporting homeostatic migration of a broad spectrum of lymphocytes into the secondary lymphoid tissues. SLC may also be involved in immune responses by inducing highly efficient migration of T and B cells following antigenic stimulation.

Adult↗
PubMed1998

Hepatic and portal vein blood flow during carbon dioxide pneumoperitoneum for laparoscopic hepatectomy.

BACKGROUND: Laparoscopy under carbon dioxide (CO2) pneumoperitoneum has many advantages. However, the risks of CO2 pneumoperitoneum during laparoscopic hepatectomy (LH) have not been defined. METHODS: The hemodynamics of the hepatic vein were examined during CO2 pneumoperitoneum both pre- and posthepatectomy in eight pigs. Portal blood flow was measured with Doppler ultrasound during laparoscopic cholecystectomy in 10 human patients. RESULTS: Experimentally, elevated intraabdominal pressure (IAP) with CO2 insufflation produced significant increases in CO2 partial pressure and echogenicity of the hepatic vein in the posthepatectomy group. Clinically, elevated IAP caused significant narrowing of the portal vein and significant decreases in portal blood velocity. The mean portal flow was significantly decreased with elevation of IAP >10 mmHg. CONCLUSIONS: LH with CO2 pneumoperitoneum may lead to embolism caused by CO2 bubbling through the hepatic vein. Elevated IAP may cause a decrease in hepatic blood flow and induce severe liver damage, especially in patients with poor liver function. Gasless laparoscopy using abdominal wall lifting should be employed in LH to avoid the risks of CO2 embolism and liver damage.

Abdomen↗
PubMed1998

Telomere shortening in the colonic mucosa of patients with ulcerative colitis.

Telomere length in human somatic cells gradually decreases with the number of cell divisions and is regarded as a marker of somatic cell turnover. Mucosal cells of the affected colon show rapid turnover in individuals with active ulcerative colitis (UC). Telomere length was determined by Southern blot analysis of terminal restriction fragments (TRFs) from the colonic mucosa of 17 patients with UC in remission, two of whom showed dysplasia, and 17 control subjects without colitis. For each individual, mean TRF length was compared between rectal mucosa and unaffected cecal mucosa. The mean TRF length of the rectal mucosa was significantly less than that of cecal mucosa in UC patients (7.87 +/- 0.36kb versus 8.77 +/- 0.21 kb; P = 0.0015, Wilcoxon signed rank test), whereas no significant difference was detected in the control subjects. The extent of telomere shortening was 10.6 +/- 3.35% in UC patients, compared with 0.8 +/- 0.64% in noncolitis controls (P = 0.0024, Mann-Whitney U-test). Four UC patients, two of whom had dysplasia, showed telomere shortening of more than 20% in the rectal mucosa. These observations suggest that telomere shortening in the colonic mucosa of individuals with UC may represent the history of mucosal inflammation during disease of long duration, and that it may contribute to aneuploidy in UC.

Adolescent↗
PubMed1998

Formation of hydroxyapatite in new calcium phosphate cements.

Tetracalcium phosphate (TTCP) has been shown previously to be an essential component of self-setting calcium phosphate cements that form hydroxyapatite (HA) as the only end-product. We report herein on a new self-setting calcium phosphate cement that does not contain TTCP. These cements consist of dicalcium phosphate anhydrous (DCPA), dicalcium phosphate dihydrate (DCPD), alpha-tricalcium phosphate, or amorphous calcium phosphate and, as an additional source of calcium, calcium hydroxide or calcium carbonate. These cements require the use of a phosphate (0.2 moll(-1) or higher) solution or a high pH solution as the cement liquid. The cements harden in relatively short time (5-30 min) and form HA as the dominant end-product in 24 h. The diametral tensile strengths of the 24-h samples are in the range of 0.2 to 7.5 MPa. Results from X-ray diffraction studies suggest that the cement setting is caused by rapid HA formation induced by the high phosphate concentration of the cement liquid. Because DCPA and DCPD are highly soluble at pH values above 12.7, which is the pK3 of phosphoric acid, high phosphate concentration in the slurry solution was also attainable by using a highly alkaline solution as the cement liquid. The physicochemical properties of these cements are comparable to those of TTCP-containing cements, and the new cements may be expected to have in vivo characteristics similar to those of TTCP-containing cements as well.

Biocompatible Materials↗
PubMed1998

Crossing inputs of the superior laryngeal nerve afferents to medullary swallowing-related neurons in the cat.

To understand the neural mechanism for generation of synchronous activity on both sides during swallowing, we examined the convergence of inputs from the bilateral superior laryngeal nerves (SLNs) in the urethane-anesthetized cat medulla and we also examined the changes in swallowing outputs after a longitudinal brain-stem split in decerebrate cats. Twenty-six (31%) of 84 swallowing-related neurons (SRNs) that were oligosynaptically activated by ipsilateral SLN stimulation and recorded mostly in the reticular formation received contralateral inputs, which were confirmed by orthodromic spike responses (n = 16) or were detected as subliminal facilitatory or inhibitory inputs (n = 10) using conditioning-test stimuli. The rate of convergence of inputs from bilateral SLNs in these SRNs was significantly higher than that (4%) in the SRNs that were regarded as sensory-relay neurons in the nucleus tractus solitarius (NTS). The SRNs receiving signals from the contralateral SLN were located diffusely from the NTS and the adjacent reticular formation to the nucleus ambiguus (NA) and the reticular formation dorso-medial to the NA. A midsagittal split from 3 mm caudal to 6 mm rostral to the obex could change symmetrical swallowing to unilateral swallowing. Thus the crossing projections to the contralateral SRNs appear to contribute to symmetrical swallowing.

Afferent Pathways↗
PubMed1998

Detection of suppression of bitterness by sweet substance using a multichannel taste sensor.

A multichannel taste sensor whose transducer is composed of several kinds of lipid/polymer membranes with different characteristics can detect taste in a manner similar to human gustatory sensation. Taste information is transformed into a pattern composed of electric signals of membrane potentials of the receptor part. In the present study, it was shown that the suppression of the bitterness of quinine and a drug substance by sucrose can be quantified using a multichannel taste sensor. The present method can be expected to provide a new automated method to measure the strength of bitterness of drug substance in the place of sensory evaluation.

Chemistry, Pharmaceutical↗
PubMed1998

Effect of fluoride on apatite formation from Ca4(PO4)2O in 0.1 mol L(-1) KH2PO4.

The effect of fluoride on the hydrolysis of tetracalcium phosphate (TTCP; Ca4(PO4)2O) was investigated in 0.1 mol l(-1)KH2PO4 containing 0-83 mol l(-1) KF. Characterization of the final apatite phase formed by the hydrolysis was made with X-ray diffraction and SEM. The initial pH was between 4.5 and 5.4, depending on the solutions, and the pH rapidly increased and was kept constant between 7.3 and 6.5. An increase in KF concentration tended to lower the pH in the final stage of hydrolysis. The calcium concentration was considerably lower than the phosphorus concentration throughout the reaction. The fluoride concentration decreased shortly after the start of hydrolysis. The hydrolysis of TTCP in 0.1 mol l(-1) KH2PO4 proceeded to form hydroxyapatite via DCPD when the KF concentration was low. The hydrolysis product was a calcium-deficient non-stoichiometric hydroxyapatite with a Ca/P ratio of about 1.5. With an increase in the KF concentration in the 0.1 mol l(-1) KH2PO4 solution, TTCP directly transformed into hydroxyapatite containing F- ions or fluorapatite and with improved crystallinity. The addition of fluoride in the solution initially accelerated the formation of apatite. However, the layer of newly formed apatite adhering to the TTCP particles retarded TTCP dissolution; as a result, hydrolysis was delayed. IR analysis showed that the apatite phase contained HPO2-4 ions in the structure. The formula for the hydrolysis product of TTCP in the presence of fluoride can be expressed as follows: Ca10-x(HPO4)x(PO4)10-x(OH)2-x-yFy.

Journal Article↗
PubMed1998

Electroencephalographic findings in functional psychoses: state or trait indicators?

The clinical significance of electroencephalographic (EEG) changes in patients with functional psychoses is not yet clearly defined, particularly whether these changes are state indicators or trait indicators. In the present review, the EEG abnormalities in schizophrenia are discussed. In early EEG studies of schizophrenics, the various specific EEG patterns were suggested to be trait indicators, but those findings were not confirmed. The EEG patterns of some patients with catatonic schizophrenia, especially periodic catatonia, were thought to be episode or state indicators, and some of the patients diagnosed as having atypical psychoses in Japan were suggested to show state indicator EEG findings. As the computerized and spectral analyses of EEG have advanced, the contradictory findings of EEG in schizophrenia have been reported, interpreted as 'hyperstable' or 'hypernormal' EEG findings and 'hypofrontal' EEG findings (slow waves in the frontal region). However, no conclusion can be made as to whether these EEG findings are state or trait indicators. On the borderland of functional psychoses, the behavioral changes in temporal lobe epilepsy were described as a trait indicator, and the psychotic states in non-convulsive generalized status epilepticus and acute confusional states were suggested to be state indicators. Further studies of EEG abnormalities in schizophrenia are necessary from multi-dimensional perspectives, including in comparison with the symptomatic psychoses.

Catatonia↗
PubMed1998

EBI1-ligand chemokine (ELC) attracts a broad spectrum of lymphocytes: activated T cells strongly up-regulate CCR7 and efficiently migrate toward ELC.

EBI1-ligand chemokine (ELC) is a CC chemokine constitutively expressed in various lymphoid tissues and a high-affinity functional ligand for EBI1/CCR7, a seven transmembrane G-protein-coupled receptor originally identified as an Epstein-Barr virus (EBV)-inducible gene. Here we examined chemotactic activity of ELC on peripheral blood leukocytes. ELC attracted both CD4+ and CD8+ T cells, particularly efficiently after activation with IL-2 or with phytohemagglutinin (PHA) plus IL-2, as well as CD19+ B cells, but not CD16+ NK cells, CD14+ monocytes or neutrophils. Among CD3+ T cells, ELC attracted both CD45RO- naive and CD45RO+ memory subsets. ELC also induced vigorous calcium mobilization in T cells stimulated with IL-2 with an ED50 of 3 nM. ELC fused with the secreted form of alkaline phosphatase (ELC-SEAP) specifically bound to lymphocytes and this binding was blocked only by ELC among 10 CC chemokines so far tested. Notably, lymphocytes stimulated with IL-2 or T cells expanded by PHA plus IL-2 showed much higher levels of binding than fresh lymphocytes. Consistently, CCR7 mRNA was detected in CD4+ and CD8+ T cells as well as B cells, but not in NK cells, monocytes or neutrophils, and was dramatically increased in T cells upon treatment with IL-2 or with PHA plus IL-2. Like ELC mRNA, CCR7 mRNA was expressed in various lymphoid tissues. By in situ hybridization, ELC and CCR7 mRNA were detected in the parafollicular and inner cortical regions of a lymph node, and in the parafollicular regions of an appendix. Collectively, ELC and CCR7 may be involved in the trafficking of a broad spectrum of lymphocytes, especially activated T cells, into and within various lymphoid tissues.

Adult↗
PubMed1998

Primary colorectal cancers detected with PET.

Positron emission tomography (PET) using 18F-fluorodeoxyglucose can sensitively detect cancers of increased glucose metabolism. We describe three asymptomatic individuals who were found to have colorectal cancer and underwent potentially curative surgery. On the PET images, lesions were easily discernible. Our experience and the experience of others suggest that primary colorectal cancer can be detected with PET in a resectable stage. Our three cases are presented and the potential utility of PET is discussed.

Adult↗