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Biomedical subjects

S Horii

Publications and source records attributed to S Horii.

At least 19 recordsLinked to original sources
PubMed2003

Charge freezing in the zigzag chain PrBa2Cu4O8 cuprate.

We report nuclear quadrupole resonance (NQR) studies on the chain Cu sites of PrBa2Cu4O8, a quasi-one-dimensional conductor with a nearly quarter-filled band. The nuclear spin-lattice relaxation rate 1/T1 shows a pronounced peak near 100 K caused by fluctuations of electric field gradient. Similar peak was observed for the spin-echo decay rate 1/T2, however, at a different temperature near 50 K. These results and broadening of the NQR spectrum at low temperatures indicate that slow charge fluctuations of either electronic or ionic origin freeze gradually at low temperatures.

Journal Article↗
PubMed2002

Three-dimensional fermi-liquid ground state in the quasi-one-dimensional cuprate PrBa(2)Cu(4)O(8).

The interchain resistivity of PrBa(2)Cu(4)O(8) has been measured in high magnetic fields up to 30 T. Co-herent interchain transport at low temperatures is destroyed by a large magnetic field applied perpendicular to the CuO chains. Comparisons with quasiclassical transport theory provide strong experimental support for a three-dimensional Fermi-liquid ground state in PrBa(2)Cu(4)O(8), despite extreme anisotropy in its electronic properties and the presence of strong electron correlations.

Journal Article↗
PubMed2001

An automated results notification system for PACS.

The purpose of this study was to determine if the interval between an examination being ordered by an Emergency Department physician and his or her review of the report and images could be shortened by notifying the physician that the results were available. This hypothesis was based on work done previously in the Medical Intensive Care Unit that showed that physicians would wait to review results for a time considerably longer than the time required for the radiologist to review the images and provide a preliminary report. The software developments operate properly and show that even simple integration of multiple information systems (PACS, RIS, speech recognition) can provide useful features. Early results indicate that the Emergency Department (ED) physicians prefer the notification system over the previous (travel to check on images and reports) methods. The hypothesized time reductions did occur, although it is not clear that the notification system accounted for all of them. A system for automated notification of radiology results availability has been shown to be possible and practical. To do this automated interaction of 3 systems with a low-level or no electronic integration was required. Although not fully successful for this study, early physician response has been positive, and requests to expand this service hospitalwide now are common.

Emergency Service, Hospital↗
PubMed2000

Anisotropic optical spectra of PrBa2Cu4O8: possible Tomonaga-Luttinger liquid response of the quasi-one-dimensional metallic CuO double chains.

The optical spectra of PrBa2Cu4O8 show large in-plane anisotropy. For the a polarization (E perpendicular chain), the spectrum is characterized by a gap of 1.4 eV, indicating the charge-transfer insulating nature of the CuO2 planes. For the metallic chain direction (E // b), the spectrum deviates from a simple Drude response; reflectivity R(b)(omega) shows a sharp edge at approximately 1 eV but it also shows a dip at approximately 15 meV, which splits the conductivity spectrum into two parts--a zero-energy mode with small weight and a pronounced 40 meV mode. These features are discussed in terms of a Tomonaga-Luttinger liquid in a doped 1D Mott insulator and compared with 1D Bechgaard salts.

Journal Article↗
PubMed2000

Angle-resolved photoemission study of insulating and metallic Cu-O chains in PrBa2Cu3O7 and PrBa2Cu4O8

We compare the angle-resolved photoemission spectra of the hole-doped Cu-O chains in PrBa2Cu3O7 (Pr123) and in PrBa2Cu4O8 (Pr124). While, in Pr123, a dispersive feature from the chain takes a band maximum at k(b) (momentum along the chain) approximately pi/4 and loses its spectral weight around the Fermi level, it reaches the Fermi level at k(b) approximately pi/4 in Pr124. Although the chains in Pr123 and Pr124 are approximately 1/4 filled, they show contrasting behaviors: While the chains in Pr123 have an instability to charge ordering, those in Pr124 avoid it and show an interesting spectral feature of a metallic coupled-chain system.

Journal Article↗
PubMed1992

Non-opioid-dependent inhibitory action of loperamide on cholinergic neurotransmission in canine isolated bronchial smooth muscle.

The effect of loperamide on cholinergic neurotransmission in canine bronchial smooth muscle was studied under isometric conditions in-vitro. Addition of loperamide decreased contractile responses to electrical field stimulation in a dose-dependent fashion, the maximal decrease from the control response and the IC50 value being 65.4 +/- 5.9% and 1.5 microM, respectively. In contrast, loperamide was without effect on the responses to exogenously administered acetylcholine. The inhibitory effect of loperamide was not altered by pre-incubation of tissues with propanol, 6-hydroxydopamine, bicuculline, or naloxone. These results suggest that loperamide attenuates the neurally mediated airway contraction probably by inhibiting acetylcholine release from cholinergic nerve terminals through a non-opioid-dependent mechanism.

Animals↗
PubMed1992

Patterns of alcohol abuse from the viewpoint of multiple substance abuse.

1. As a result of examining the alcoholism of 172 subjects, from the view point of multiple abuse in a long-term process, we were able to classify alcoholism into three patterns: Pattern I is the alcohol alone type, Pattern II is the alcoholism with legal drugs, such as hypnotics and tranquilizers and Pattern III is the alcoholism with illicit drugs, such as organic solvents and methamphetamine. 2. We ascertained the alcohol alone abuse type (Pattern I) existed. 3. Pattern II resembles Pattern I in living status, delinquency, experience of criminal acts and characters except that the abusers in Pattern II were younger than those in Pattern I. 4. The abusers in Pattern III showed a trend to incline to multiple abuse. They had antisocial characters and family problems and the level of their social life was disrupted from their youth in many cases.

Adolescent↗
PubMed1992

A study of longitudinal patterns of substance abuse with special reference to multiple use problems.

1. Sequential patterns of abuse were analyzed in 222 subjects of substance abuse who had admitted mental hospitals. They were classified into four patterns and seven sub-patterns. 2. Alcohol alone type (Pattern I) was different from other patterns of abuse in their initiating ages, family status and the levels of social life. A marked tendency to multiple abuse was found in Pattern II and III including organic solvents and/or methamphetamine. 3. However, even in Pattern II and III, alcohol abuse was found in 18% of the subjects. This suggests alcohol is an important hidden substance in multiple drug abusers. 4. Many substance abusers without alcohol had also alcoholics in their family members. Especially those who initiated their abuse in early ages are supposed to have constitutional and family factors which are common to alcohol and drugs. 5. Patterns II and III of organic solvents and methamphetamine abuse, the existence of peers and their strong influence upon users were of prime importance. Initiation of abuse from an early age and disruption of social life were marked in those patterns. 6. Many alcoholics started their abuse in earlier ages than expected. The study shows that there were two groups; the group whose social lives had been disrupted at early ages, and the one whose level of social life had been maintained. 7. Physical illnesses were mostly found in the patterns which include alcohol abuse.

Adolescent↗
PubMed1991

Picture archiving and communication in radiology: an American perspective.

A comprehensive image management and communication (IMAC) network has been installed at Georgetown University Hospital (GUH) for an extensive clinical evaluation. The network is based on the AT&T CommView system and includes interfaces to 12 imaging devices, 15 workstations (inside and outside the radiology department), a teleradiology link to an imaging center, an optical jukebox, and a number of advanced image display and processing systems. Two years of clinical experience with the network enable us to develop a plan for future activities from an American perspective. The IMAC project is not just a technical challenge, but also a professional, organizational, and administrative one. Several obstacles remain, but they are gradually being overcome as more cost-effective and streamlined technologies become available and as users and developers gain more operational experience in managing diagnostic images in an electronic environment.

Computer Communication Networks↗
PubMed1991

Atrial natriuretic factor inhibits ciliary motility in cultured rabbit tracheal epithelium.

To study the effect of atrial natriuretic factor (ANF) on airway ciliary motility, we measured ciliary beat frequency by a photoelectric method in response to ANF in cultured tracheal epithelial cells from rabbits. Addition of ANF but not [Tyr8]ANF-(5-27) decreased ciliary beat frequency in a dose-dependent fashion; the maximal decrease from the baseline value was 24.1 +/- 1.5% (+/- SE, P less than 0.001), and a half-maximal inhibitory concentration (IC50) was 3 x 10(-12) M. Inhibition of neutral endopeptidase activity by phosphoramidon (10(-6) M) or thiorphan (10(-6) M) potentiated the effect of ANF so that the dose-response curve for ANF was shifted to lower concentrations by approximately 0.5 log units (P less than 0.05, in each case). The inhibition of ciliary motility induced by ANF was not affected by the blockade of arachidonic acid metabolism with indomethacin, piroxicam, or nordihydroguaiaretic acid, but it was blocked by methylene blue, a soluble guanylate cyclase inhibitor, and was potentiated by M & B 22948, a guanosine 3',5'-cyclic monophosphate (cGMP) phosphodiesterase inhibitor. The intracellular cGMP levels were increased by ANF, an effect that was further potentiated by phosphoramidon or thiorphan. These results suggest that ANF inhibits ciliary motility presumably through a guanylate cyclase-dependent regulatory pathway and that neutral endopeptidase may play a role in modulating the ANF effect on airway mucociliary transport function.

Animals↗
PubMed1990

Effects of beta-endorphin and dynorphin A on cholinergic neurotransmission in canine airway smooth muscle.

To determine the effects of the opioid peptides, beta-endorphin and dynorphin A, on airway smooth muscle function and its possible modulation by tissue peptidases, we studied canine bronchial segments under isometric conditions in vitro. Addition of beta-endorphin or dynorphin A did not alter the resting tension. However, beta-endorphin (10(-6) M) but not dynorphin A decreased the contractile responses to electrical field stimulation (EFS, 0.5-40 Hz). This effect was dose-dependent and reversed by naloxone. In contrast, acetylcholine-induced contractions were not affected by these opioids. The beta-endorphin-induced inhibition of the contractile responses to EFS was not augmented by peptidase inhibitors such as thiorphan, captopril, bestatin and leupeptin. These results suggest that beta-endorphin prejunctionally inhibits parasympathetic muscle contraction, and that endogenous peptidases do not play a modulatory role in this effect of beta-endorphin.

Animals↗