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Biomedical subjects

T Mashimo

Publications and source records attributed to T Mashimo.

At least 73 records · Page 4Linked to original sources
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

[Clinical evaluation of norfloxacin in gonococcal urethritis].

Norfloxacin, a new quinolinecarboxylic acid derivative, was administered to 30 male patients with gonococcal urethritis at a daily dose of 600 mg for 7-21 days. The clinical response was evaluated after administration of 7 days as excellent; Negative culture of N. gonorrhoeae. WBC less than 3/hpf in first voided urine sediment, good; Negative culture, WBC greater than or equal to 3/hpf, and poor; Positive culture. The result was excellent in 14 cases and good in 16 cases. No subjective side effects were observed. The minimum inhibitory concentration (MIC) distribution against the clinically isolated 30 strains of N. gonorrhoeae ranged from 0.0096 micrograms/ml to 0.34 micrograms/ml. Seven of thirty strains were resistant to ABPC. The MIC of these 7 strains ranged from 0.018 micrograms/ml to 0.18 micrograms/ml. Seven cases with ABPC resistant strains had a similar clinical response to other cases. Twelve patients (40%) developed post gonococcal urethritis for 7-14 days after treatment. Clinical observation of this series suggests that a 7 day therapy of Norfloxacin for the patients with gonococcal urethritis is sufficiently effective and that treatment should be changed to other antibacterial agents in the case of post gonococcal urethritis, since continuous administration for more than 7 days of Norfloxacin is not so effective.

Adult↗
PubMed1986

Anesthetic-protein interaction: surface potential of bovine serum albumin estimated by a pH-sensitive dye.

It is often contended that inhalation anesthetics act on proteins via perturbation of lipid membranes. However, direct interaction between anesthetics and water-soluble proteins also has been demonstrated. We postulate that the anesthetic action is directed to the interface between water and macromolecules, irrespective of lipid membranes or proteins. The present study deals with anesthetic effects upon interfacial properties of a water-soluble, crystalline delipidated bovine serum albumin. A pH-indicator dye, bromothymol blue, was used to probe the surface potential of the protein. When a pH-indicator dye binds to a macromolecule, the pH, indicated by the color of the dye, differs from the bulk pH measured by a pH meter. This is because the pH of the microscopic area, where the dye is adsorbed, differs from the bulk due to the surface electrostatic potential that interacts with hydrogen ions (electrostatic terms), and the physical property that affects the color of the dye at the bound region is different from the bulk (nonelectrostatic terms). The mismatch between the bulk pH and the color of the bound pH indicator can be used to probe the property of the dye binding site. By screening the electrostatic effects with high ionic strength, the anesthetic effects upon the nonelectrostatic term were shown to be negligible under the present experimental conditions; the pH-color mismatch was mainly caused by the anesthetic effect upon the electrostatic potential of the macromolecular surface interacting with the dye. Accordingly, the surface potential of the dye binding site was estimated from the mismatch. It was found that inhalation anesthetics decreased the surface potential. The partial pressures of diethylether, enflurane, and methoxyflurane that decreased the surface potential by 10 mV were 2.1 X 10(-2), 1.7 X 10(-2), and 0.17 X 10(-2) bar, respectively, which were in agreement with the minimal alveolar concentrations of these anesthetics to achieve surgical anesthesia.

Anesthesia, Inhalation↗
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

Blood glucose control by an artificial endocrine pancreas in a patient with phaeochromocytoma.

In a patient with phaeochromocytoma who presented with unstable diabetes mellitus, an artificial endocrine pancreas was used intraoperatively. Anaesthetic agents included enflurane, nitrous oxide and oxygen. Nicardipine was used to control hypertensive episodes. The initial blood glucose concentration was 173 mg X dl-1 and it decreased to 110 mg X dl-1 in response to insulin infusion, but plasma catecholamines were markedly increased. Seventy minutes later, the glucose concentration increased progressively to 249 mg X dl-1 despite massive insulin infusion, maximally 5.64 mU X kg-1 X min-1. The blood glucose concentration reached a peak at the time of the ligation of the venous drainage from the tumour and the peak was coincident with that of plasma catecholamine levels (epinephrine: 20.8 ng X ml-1, norepinephrine 16.4 ng X ml-1). Both glucose and catecholamine concentrations decreased promptly after removal of the tumour and hypotension followed likely because of a persistent vasodilatatory effect of nicardipine. The profiles of blood glucose, insulin and glucose infusion rates provided by the artificial endocrine pancreas suggested that the insulin resistance began to be reversed shortly after removal of the phaeochromocytoma.

Adrenal Gland Neoplasms↗
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↗
PubMed1983

Effect of inhalational anesthetics on the opioid receptors in the rat brain.

Effects of inhalational anesthetics, methoxyflurane and halothane, on the binding of various opioid ligands were studied. The binding affinity of 3H-methionine enkephalin (delta) was reduced by both anesthetics in the same manner, but the receptor density was not significantly affected. Methoxyflurane decreased the binding affinity but increased the receptor density of 3H-dihydromorphine (mu), while halothane had little effects on both affinity and density. Methoxyflurane also decreased binding affinities of 3H-ethylketocyclazocine (kappa) and 3H-SKF-10047 (sigma), but halothane did not decrease significantly. These effects of the anesthetics were completely disappeared by unsealing and ventilation.

Animals↗
PubMed1983

[The maternal and fetal acid-base status during general or spinal anesthesia for elective cesarean section in the left tilt position].

Thirty one healthy parturients received spinal or general anesthesia for elective cesarean section. Maternal blood pressures, maternal and fetal acid-base values, induction to delivery intervals (I-DI) and Apgar scores were determined. On spinal anesthesia, acute hydration by 6% hydroxyethyl starch solution and intramuscular injection of ephedrine were enforced prior to the block and in the left tilt position (17 degrees) oxygen inhalation immediately after the block was begun (group OII: 16 cases). As to general anesthesia, the same left tilt position was applied before the anesthesia by thiopental-0.5% halothane with-50% nitrous oxide in oxygen (group G: 15 cases). No significant decrease in maternal blood pressure was noticed, and maternal and the fetal acid-base status and Apgar scores were excellent in both groups. A positive correlation between umbilical venous pH values and 1 or 5 minutes Apgar scores was confirmed in group OII, and a negative correlation between 1 minute Apgar scores and I-DI was noticed in group G. Fetal acid-base values were not correlated with I-DI in either group, and it was postulated that placental or fetal circulation was sufficiently maintained. Biochemical status and clinical conditions in mothers and their infants are very favorable in well-conducted general or spinal anesthesia for elective cesarean section.

Acid-Base Equilibrium↗
PubMed1982

Anesthetics expand partial molal volume of lipid-free protein dissolved in water: electrostriction hypothesis.

The present study was undertaken to critically examine whether the dilating action of inhalation anesthetics is specific to lipid membranes. Delipidated crystalline bovine serum albumin was used as a model and the density of a salt-free aqueous solution was measured by a high-precision oscillation densimeter. The partial molal volumes of albumin at infinite dilution were 50,326, 51,019 and 51,698 cm3 . mol-1, respectively at 293, 308 and 323 degrees K. From the difference between the present value and the volume of dry albumin, the number of electrostricted water molecules at the surface of albumin in aqueous solution at 293.15 degrees K is estimated to be about 720. Addition of diethylether to the albumin solution increased the partial molal volume of albumin, dose-dependently. At 57.88 mmolal, diethylether expanded the partial molal volume of albumin at 293 degrees K by 295 cm3 . mol-1 or 0.59%. This volume expansion does not include the space occupied by the anesthetic molecules in albumin. If the expansion can be assumed to be caused mainly by melting of electrostricted water molecules, about 110 water molecules were released from the protein surface. The partial molal volume of diethylether was increased when bound to albumin. The increase indicates that the contact between diethylether and water is partially destroyed and that high pressure squeezes out anesthetic molecules from the protein.

Anesthetics↗