PubMed Health⌕ Search

Biomedical subjects

S Horii

Publications and source records attributed to S Horii.

At least 19 recordsLinked to original sources
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↗
PubMed1990

Calcitonin gene-related peptide augments parasympathetic contraction of rabbit tracheal smooth muscle in vitro.

The effect of calcitonin gene-related peptide (CGRP) on parasympathetic contraction of rabbit airway smooth muscle was studied under isometric conditions in vitro. CGRP (10(-7) M) did not contract tracheal smooth muscle, but it potentiated the contractile response to electrical field stimulation (EFS) in a dose-dependent manner, the maximal increase from the baseline response being 14.4 +/- 6.2%. In contrast, the contractile responses to exogenously administered acetylcholine were not altered by this peptide. The CGRP-induced potentiation of the contractile responses to EFS was further augmented by physostigmine (123.1%), but not influenced by phentolamine, propranolol, indomethacin, or thiorphan, an enkephalinase inhibitor. These results suggest that CGRP augments the neurally mediated contraction of rabbit airway smooth muscle probably through a prejunctional mechanism and that this effect may not be modulated by tissue enkephalinase.

Acetylcholine↗
PubMed1990

Angiotensin II stimulates airway ciliary motility in rabbit cultured tracheal epithelium.

We studied the effect of angiotensin II on ciliary activity in cultured rabbit tracheal epithelium in vitro. Administration of angiotensin II (10(-6) M) elicited an increase in ciliary beat frequency (CBF), as assessed by a photoelectric method, from the baseline value of 906 +/- 21 to 1260 +/- 33 beats min-1 (mean +/- SE, P less than 0.001). This ciliostimulatory effect was dose-dependent, with the maximal increase and EC50 value being 35.6 +/- 5.2% (P less than 0.001) and 5 x 10(-12) M respectively. Nifedipine, Ca2(+)-free medium, indomethacin and the phospholipase A2 inhibitor mepacrine, but not nordihydroguaiaretic acid, reduced the change in CBF. The ciliostimulation induced by angiotensin II was abolished by pretreatment of tissues with [Sar1-Ile8]angiotensin II, an angiotensin II receptor antagonist. Angiotensin II did not increase cyclic AMP levels in epithelial cells. These results suggest that angiotensin II interacts with its specific receptors and stimulates airway ciliary activity through a Ca2(+)-dependent prostaglandin release, without affecting intracellular cyclic AMP levels. Thus, angiotensin II may modulate mucociliary transport function in the respiratory tract.

Angiotensin II↗
PubMed1990

Relaxation of canine airway smooth muscle by the heparin preservative benzyl alcohol.

To characterize the actions of heparin and its common preservative benzyl alcohol (BA) on airway smooth muscle functions, we studied the effects of purified heparin, commercial heparin salt solution (HSS) containing heparin and BA, and BA on the contractile responses of canine bronchial segments to various agonists under isometric conditions in vitro. Addition of HSS or the equivalent volume of BA reversibly depressed acetylcholine-induced contraction in a dose-dependent fashion, IC50 values being 5.7 +/- 1.1 (SE) mM of BA, whereas purified heparin had no effect. This depression was not affected by pretreatment of tissues with propranolol, indomethacin or ouabain, or removal of epithelium, and BA at sufficient concentrations to cause muscle relaxation did not alter intracellular adenosine 3',5'-cyclic monophosphate contents. BA also attenuated the contractile responses to electrical field stimulation, histamine, and serotonin, but it was without effect on those to KCl. In addition, the acetylcholine-induced enhancement of hydrolysis of phosphatidylinositol 4,5-biphosphate in the lipid fraction and the resultant production of phosphatidic acid were inhibited in the presence of BA. These results suggest that the heparin preservative BA but not heparin relaxes airway smooth muscle, probably through the decrease in intracellular Ca2+ release by inhibiting agonist-mediated phosphatidylinositol turnover.

Acetylcholine↗
PubMed1990

Effects of lipopolysaccharide from Pseudomonas aeruginosa on airway smooth muscle functions in guinea pigs.

To elucidate the mechanisms of airway hyperreactivity induced by lipopolysaccharide (LPS), we studied isolated tracheal segments from guinea pigs under isometric conditions in vitro. Guinea pigs were injected intraperitoneally with endotoxin (1 mg/kg; LPS from Pseudomonas aeruginosa, serotype 10) for 4 days, and animals treated with sterile nonpyrogenic saline served as controls. Histological examination of trachea revealed moderate structural damage of epithelial layer in the LPS-treated group. Treatment with LPS potentiated the contractile responses of tracheal smooth muscle to acetylcholine, causing a leftward displacement of dose-response curves so that the EC50 values decreased from 1.1 +/- 3.7 x 10(-5) to 4.4 +/- 3.7 x 10(-7) M (mean +/- SE, p less than 0.01). Likewise, LPS shifted the dose-response curves for histamine and substance P to lower concentrations by approximately 0.5-1.0 log U. Each of these potentiations was not affected by pretreatment of tissues with indomethacin or propranolol. Addition of isoproterenol to tracheal segments precontracted with acetylcholine caused concentration-dependent relaxation, an effect that was significantly greater in controls than in the LPS-treated group. These results suggest that airway hyperreactivity induced by LPS in guinea pigs may be attributed to a decreased ability of respiratory epithelial cells to generate a relaxing factor.

Animals↗