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Biomedical subjects

I Yoshiya

Publications and source records attributed to I Yoshiya.

At least 181 records · Page 10Linked to original sources
PubMed1986

Stereospecific effects of d- and l-pentazocine on contractions of the mouse vas deferens.

The effects of the d- and l-isomers of pentazocine were compared to that of racemic pentazocine on contractions of the mouse isolated vas deferens. L-pentazocine inhibited electrically evoked contractions of the mouse vas deferens (MVD) in a dose-dependent manner (ID50 0.37 +/- 0.04 microM). In contrast, d-pentazocine augmented field stimulated contractions dose-dependently; per cent increases in contractions at 10 and 30 microM were 57.8 +/- 18.0 and 98.0 +/- 15.1%, respectively. Racemic pentazocine produced an intermediate effect between the two isomers. The effect of 1-pentazocine was antagonized by naloxone, whereas that of d-pentazocine was not. L-pentazocine did not effect the response of the MVD to exogenous norepinephrine at any concentration tested, while d-pentazocine depressed the response of the MVD to exogenous norepinephrine at one dose (0.3 microM). These findings demonstrate that d- and l-pentazocine produce opposite effects on the MVD. The effects of l-pentazocine are opioid mediated, while those of d-pentazocine are not. In the racemic mixture the opposing effects of the two isomers modulate each other, resulting in a diminished effect.

Animals↗
PubMed1986

Electroretinogram as a possible monitor of anesthetic depth.

The effects of volatile anesthetics, i.e., methoxyflurane, halothane and enflurane, on the electroretinogram (ERG) were studied in 15 albino rabbits. The ERG was analyzed in terms of the a-wave, and the first oscillatory component (01) in the b-wave. The 01 peak latency showed a significant dose-related prolongation when anesthetic end-tidal concentrations were in excess of 0.8 minimum alveolar concentration (MAC). One MAC, a measure of anesthetic potency, is the end-tidal concentration of an anesthetic at 1 atmosphere that induces immobility in 50% of animals against a noxious stimulus. The amplitudes of the a-wave and the 01 decreased in dose-dependent manners, but their changes were less striking than those of the 01 latency. The peak latency of the a-wave remained unchanged. We conclude that the 01 peak latency is a useful monitor of the depth of inhalational anesthesia.

Anesthesia↗
PubMed1986

Dual effect of local anesthetics on the function of excitable rod outer segment disk membrane.

The effects of local anesthetics and a divalent cation, Ca2+, on the function of rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced proton uptake by rhodopsin in the rod outer segment disk membrane was enhanced at lower pH (4) but depressed at higher pHs (6 to 8) by the tertiary amine local anesthetics lidocaine, bupivacaine, tetracaine, and dibucaine. The order of local anesthetic-induced depression of the proton uptake followed that of their clinical anesthetic potencies. The depression of the proton uptake versus the concentration of the uncharged form of local anesthetic nearly describes the same curve for small and large dose of added anesthetic. Furthermore, a neutral local anesthetic, benzocaine, depressed the proton uptake at all pHs between 4 and 7. These results indicate that the depression of the proton uptake is due to the effect of only the uncharged form. It is hypothesized that the uncharged form of local anesthetics interacts hydrophobically with the rhodopsin in the disk membrane. The dual effect of local anesthetics on the proton uptake, on the other hand, suggests that the activation of the function of rhodopsin may be caused by the charged form. There was no significant change in the light-induced proton uptake by rhodopsin when 1 mM of Ca2+ was introduced into the disk membrane at varying pHs in the absence or presence of local anesthetics. This fact indicates that Ca2+ ion does not influence the diprotonating process of metarhodopsin; neither does it interfere with the local anesthetic-induced changes in the rhodopsin molecule.

Anesthetics, Local↗
PubMed1986

Serial changes in cellular immunity of septic patients with multiple organ-system failure.

Total lymphocyte count, lymphocyte cell-surface markers (OKT3, OKT4, OKT8, and B-1), serum complement factors (C3 and C4), immunoglobulins (IgG, IgA, and IgM), ceruloplasmin (Crl), and transferrin (Trf) were determined weekly for nine septic postoperative patients, all of whom had multiple organ-system failure. The peripheral blood total lymphocyte count, its subpopulation, T-cell subset, and proliferative responses of lymphocyte to phytohemagglutinin (PHA) and concanavalin A (Con A) decreased in all patients. OKT3 and B-1 decreased progressively in the four nonsurvivors compared with the five survivors. Although immunoglobulin levels were within the normal range in both groups, they tended to increase in survivors and decrease in nonsurvivors. Serial levels of C3, C4, Crl, and Trf increased in survivors but did not change in nonsurvivors. T-cell function and antibody-producing activity diminished progressively in nonsurvivors. These changes in cellular immunity may represent another manifestation of multiple organ-system failure during sepsis.

Adult↗
PubMed1986

Portal blood flow measured by duplex scanning during mesenteric infarction.

The portal blood flow of a 70-yr-old man with suspected massive mesenteric infarction was measured using duplex scanning. The main portal flow was 109 ml/min, while cardiac output was 4.2 L/min. Laparotomy revealed a massive mesenteric infarction from proximal jejunum to rectum. Duplex scanning may be a useful method for studying the course of mesenteric infarction.

Aged↗
PubMed1986

Hemodialysis using gabexate mesilate (FOY) in patients with a high bleeding risk.

The efficacy of gabexate mesilate (FOY), a synthetic serine proteinase inhibitor, was compared with that of heparin in preventing the acceleration of bleeding after hemodialysis. Transfused blood volume (TBV) was measured 24 h before and after 24 dialyses in 14 bleeding patients with impaired hemostatic function. The predialysis TBV did not differ significantly between heparin and FOY groups; however, TBV was significantly (p less than .05) larger after heparin dialysis than after FOY dialysis. After dialysis, TBV was increased in eight of nine heparin patients, compared to only three of 15 FOY subjects (p less than .01). FOY is an effective agent and may decrease postdialysis bleeding complications in certain high-risk patients.

Acute Kidney Injury↗
PubMed1986

Lipid peroxidation in experimental septic rats.

We previously reported increased lipid peroxide and decreased alpha-tocopherol levels in the blood of critically ill septic patients. To clarify these results, we investigated lipid peroxidation in experimental septic rats and severely traumatized rats. In septic rats, both platelet count and plasma alpha-tocopherol decreased significantly, while lipid peroxide in plasma and major organs significantly increased. Serum transaminases also increased significantly. Traumatized rats had a significant but transient decrease in platelet count and a continuous decrease in plasma alpha-tocopherol; lipid peroxide did not change significantly in the plasma but increased significantly in the lung and kidney. Serum transaminases of traumatized rats showed transient increases. Thus, although traumatic stress caused lipid peroxidation similar to sepsis in the major organs, plasma lipid peroxide did not change.

Animals↗
PubMed1985

Volatile anesthetics cause conformational changes of bacteriorhodopsin in purple membrane.

We examined the effects of volatile anesthetics on the structure of the bacteriorhodopsin in the purple membrane by measurements of the absorption spectrum and the visible circular dichroism (CD) spectrum and assay of the retinal composition. As the concentrations of halothane, enflurane and methoxyflurane were increased, the absorption at 560 nm decreased but that at 480 nm increased with an isosbestic point around 510 nm. These anesthetic-induced spectroscopic changes were reversible. The CD spectrum showed the biphasic pattern with a positive and a negative band. As the concentration of halothane was increased from 4 mM to 8mM, the negative band reversibly diminished more drastically than the positive band, and at 8 mM of halothane the positive band shifted to around 480 nm. These results show that halothane disturbed the exciton coupling among bacteriorhodopsin molecules. The retinal isomer composition was analyzed using high performance liquid chromatography. The ratio of 13-cis- to all-trans-retinal was 47:53, 34:66 and 19:81 at control, 7.4 mM and 14.9 mM enflurane, respectively. After elimination of enflurane, the ratio returned to the control value. These findings indicate that volatile anesthetic directly affect a bacteriorhodopsin in the purple membrane and induce conformational changes in it.

Anesthetics↗
PubMed1985

Effects of driving pressure and respiratory rate on airway pressure and PaCO2 in rabbits during high-frequency jet ventilation.

The effects of driving pressure (DP) and respiratory rate (RR) on mean airway pressure (Paw), PaCO2, and other respiratory variables were studied during high-frequency jet ventilation (HFJV) in anesthetized rabbits. The animals were tracheotomized and paralyzed, and various combinations of RR (4, 8, 12, and 16 Hz) and DP (0.5, 1.0, and 2.0 kg/cm2) were applied randomly with an inspiratory/expiratory ratio of 1.0. HFJV was delivered via a 2.5-Fr catheter through a T-attachment, using 100% oxygen, and a hot-wire flowmeter was connected to the outlet of the T-attachment for measurement of the minute volume (MV). Heart rate, arterial BP and CVP, respiratory variables, and arterial blood gases were monitored during the study. There were no direct correlations between PaCO2 and DP, MV, or RR. However, there was an inverse correlation between PaCO2 and tidal volume, and linear correlations were found between Paw and DP, and between DP and MV. It is concluded that HFJV over an RR range of 4 to 16 Hz depends mainly upon tidal volume. When the desired PaCO2 and Paw are determined, DP and RR can be calculated following the equations established in this study.

Animals↗
PubMed1985

Elimination of false-positive limulus amebocyte lysate tests in patients with hyperlipidemia.

Varying concentrations of lipopolysaccharide (LPS) and mannan suspensions were mixed with either saline or plasma from normal volunteers, heated to 100 degrees C for 10 min, and then subjected to the limulus amebocyte lysate test (LAL). A positive LAL in saline required minimum LPS and mannan concentrations of 10(-11) and 10(-5) g/ml, respectively, while the minimum concentrations premixed with plasma were 10(-13) and 10(-9) g/ml, respectively. Thus, use of plasma instead of saline increased assay sensitivity 100-fold for LPS and 10,000-fold for mannan. In the second part of the experiment, normal plasma was separated into lipid and nonlipid phases by Folch's method. LAL analysis of each phase revealed equal sensitivity for LPS and mannan in the nonlipid phase, but no sensitivity in the lipid extract. Subsequently, 200 ml of a fat emulsion (Intralipos) was administered to the normal volunteers, and LAL and lipid analyses were performed. The LAL turned positive in all volunteers. When LAL was positive, triglycerides (TG), chylomicron (Chyl), and very low-density lipoprotein (VLDL) increased significantly compared with when LAL was negative. It is concluded that plasma lipids increase the sensitivity of LAL and directly activate LAL when TG, Chyl, and VLDL concentrations are high. This effect of plasma lipids on LAL can be eliminated by extracting LPS and mannan in the nonlipid phase.

Escherichia coli↗
PubMed1985

Effects of breathing therapy with a dead-space-resistance device on post-cardiac surgical patients.

The effects of a dead-space-resistance device (IDSEP breather) on Pao2, Paco2 and functional residual capacity (FRC) in 11 post-cardiac surgical patients were studied. There were no significant changes in Pao2, Paco2 and FRC after the IDSEP therapy. Changes in Pao2 between the pre- and post-IDSEP therapy correlated well with changes in FRC (r = 0.797, P less than 0.01). Breathing therapy with the dead-space-resistance device appeared not to bring any benefit in early post-cardiac surgical patients.

Adult↗
PubMed1984

Evaluation of a system for on-line analysis of VO2 and VCO2 for clinical applicability.

The authors evaluated the accuracy of a system to measure respiratory gas exchange on an on-line basis by comparing it with a gas collection method. The system incorporates a hot-wire flowmeter, a mass spectrometer, and a microcomputer. It performs on-line compensation for both transport delay and dynamic response of the mass spectrometer. Compensation of flow measurement for changing gas fractions also is performed. Excellent linear correlations were obtained between the two methods: 1) in animals during mechanical ventilation with room air (VO2:r = 0.995; VCO2:r = 0.993), and nitrous oxide in oxygen (VO2:r = 0.975; VCO2:r = 0.976); and 2) in men spontaneously breathing room air at different workloads (VO2:r = 0.999; VCO2:r = 0.998), and higher inspired oxygen fractions (FIO2 0.38 to 0.75) (VO2:r = 0.910; VCO2:r = 0.988). The authors consider that the system is suited for accurate and continuous measurement of respiratory gas exchange during mechanical ventilation, anesthesia, and exercise testing.

Adult↗
PubMed1984

Effects of volatile anesthetics on light-induced proton uptake of rhodopsin in bovine rod outer segment disk membrane.

The effects of volatile anesthetics upon the function of bovine rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced pH changes were measured at both 20 degrees C and 37 degrees C with suspensions to which volatile anesthetics were added in the liquid form. Each anesthetic depressed the light-induced proton uptake concentration-dependently. The anesthetic-induced depression was greater at 37 degrees C than at 20 degrees C. For each anesthetic the concentration needed to depress the proton uptake by 10% was roughly identical to that used clinically. Anesthetics also were added to the suspensions in the gaseous form with air. The light-induced proton uptake was decreased in proportion to the partial pressure of the anesthetic. The partial pressures of halothane and methoxyflurane that depressed the proton uptake by 10% at 37 degrees C were 2.0 x 10(-7) and 1.1 x 10(-2) atm., respectively. From these facts it is suggested that volatile anesthetics affect the light-induced conformational changes of rhodopsin molecule during the metarhodopsin I to metarhodopsin II transition and cause inhibition of the light-induced proton uptake of rhodopsin in the rod outer segment disk membrane.

Anesthetics↗