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Biomedical subjects

K Miyake

Publications and source records attributed to K Miyake.

At least 541 records · Page 30Linked to original sources
PubMed1989

In vitro inhibition of lens epithelial cell growth by continuous wave Nd:YAG laser.

Bovine lens epithelial cells were suspended in MEM medium and subjected to continuous wave, low power, pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation. The temperature of each suspension was maintained at 36 degrees C. Laser applications ranged from 1 to 10 watts and from 100 to 2000 seconds, but the total dose to each of the epithelial cell suspension was 2000 J. Six to thirty-nine percent of the cells were dead immediately after irradiation. Surviving cells, cultured for 15 days, showed decreased attachment and failed to grow. These preliminary results suggest that the Nd:YAG laser may be used during cataract surgery to prevent subsequent lens epithelial cell proliferation and the resulting vision reduction and glare.

Animals↗
PubMed1989

In vitro effect of naftidrofuryl oxalate on cerebral mitochondria impaired by microsphere-induced embolism in rats.

The present study was designed to determine whether naftidrofuryl oxalate (Naftidrofuryl) may exert a beneficial effect on the cerebral mitochondria after microsphere-induced embolism assessed under in vitro conditions. For this purpose, 600 microspheres (48 microns in diameter) were injected into the right carotid canal of rats, which induced an irreversible embolism in the right cerebrum. Three days after the operation, the cerebral mitochondria were isolated and their oxidative phosphorylation ability and succinate dehydrogenase activity were determined. Two types of mitochondria were obtained after cerebral embolism: one was mitochondria which revealed a marked decline in the oxidative phosphorylation activity when measured in the presence of glutamate or succinate as a substrate (severely injured mitochondria), and the other, those which revealed a decrease in the activity in the presence of succinate and an appreciable increase in the activity in the presence of glutamate (mildly injured mitochondria). Naftidrofuryl at the concentration of 3 microM elicited slight but significant restoration of the oxidative phosphorylation ability of the mildly injured mitochondria isolated from rats after the cerebral embolism, but not of the severely injured mitochondria. The succinate dehydrogenase activity of the brain mitochondria isolated from rats 3 days after the cerebral embolism was significantly decreased. Exposure of these mitochondria to 0.1 to 1 microM Naftidrofuryl significantly restored the succinate dehydrogenase activity. The results suggest that Naftidrofuryl is capable of exerting a beneficial effect in vitro on the brain mitochondria activity impaired by the cerebral embolism, particularly on the activity of mildly injured mitochondria.

Adenosine Triphosphate↗
PubMed1989

Hypotheses on the role of prostaglandins in the pathogenesis of epinephrine maculopathy and aphakic cystoid macular edema.

This article presents hypotheses regarding pathogenesis of epinephrine maculopathy. According to these hypotheses, two points are the most essential in the development of epinephrine-induced CME: one is the stimulation of PG synthesis by some tissues, presumably, the anterior uvea by the applied epinephrine, the other is the dysfunction, in some aphakic eyes, of the active transport system (Bito's pump) which is responsible for the removal of PGs from intraocular fluids. To test these hypotheses, the authors and their group conducted several experimental studies. The results of these studies, which have been reviewed in this article, strongly suggest that epinephrine maculopathy is induced by a mechanism involving PGs or possibly, other related eicosanoids and not simply by epinephrine per se, as has previously been suggested. This in turn suggest the existence of some common factors in the pathogenesis of epinephrine maculopathy and aphakic or pseudophakic CME.

Animals↗
PubMed1989

[Ectopic ureteral opening: clinical assessment of 13 cases].

Thirteen cases of ectopic ureteral opening, surgically intervened during the past 10 years, were reviewed regarding the patients profiles, diagnostic procedure, treatment and concomitant anomalies. The diagnostic procedures are consisted of the conventional methods such as an intravenous urography, a vaginography, and a renoscintigraphy, which are important to identify and locate the immature kidney or the kidney with duplication anomaly. An angiographic examination is to be abandoned because it is invasive and rather insensitive. The surgical treatment should be determined depending on the renal function remained, ureteral morphology and the site of the ureteral opening.

Adolescent↗
PubMed1989

Neurobehavioral analysis of high-rate Sidman avoidance rat strain.

The neurobehavioral characteristics of the Tokai High-Avoider (THA) rats, which had an innate high-avoidance ability, were clarified by comparing with the Wistar rats from which the THA rat strain had been derived. THA rats performed superior learning and displayed small individual differences of learning performance, not only in the Sidman avoidance task, which had already been used in selective breeding, but also in two different tasks, namely water maze and two-way shuttle avoidance. No apparent difference was present in development, circadian rhythm, and open-field activity between the two strains. On the other hand, sensitivity of the THA rat to electric shock or to heat stress was less than that of the Wistar rat. From these results, it might be considered that the high and uniform avoidance performance exhibited in the THA rat was caused by an innately acquired ability but not by sensitivity to the shock or developmental differences.

Animals↗
PubMed1989

Beneficial effects of lidocaine and disopyramide on oxygen-deficiency-induced contractile failure and metabolic disturbance in isolated rabbit hearts.

The purpose of the present study was to determine whether antiarrhythmic agents, lidocaine and disopyramide, which reveal a membrane stabilizing action, may exert a beneficial effect on posthypoxic recovery of cardiac function and metabolism. Rabbit hearts were perfused for 20 min under hypoxic conditions, followed by 45-min reoxygenation. Hypoxic insults induced cessation of cardiac contractile force, rise in resting tension, depletion of myocardial high-energy phosphates, accumulation of tissue calcium and release of creatine kinase and ATP metabolites such as adenosine, inosine and hypoxanthine. These alterations were not returned to the initial levels upon reoxygenation. Administration of either 69 microM lidocaine or 55 microM disopyramide after the onset of oxygen deficiency (between 8th and 20th min of the hypoxia) resulted in a significant suppression of hypoxia-induced rise in resting tension, tissue calcium accumulation and release of creatine kinase and ATP metabolites, whereas hypoxia-induced decline in cardiac contractile force and depletion of myocardial high-energy phosphates were not affected by the treatment. The latter two variables were improved markedly during 45-min reoxygenation when the heart had been treated with the agents. The improvement was accompanied by a suppression of the release of creatine kinase and ATP metabolites and the tissue calcium accumulation. The results suggest that lidocaine and disopyramide are beneficial for posthypoxic recovery of cardiac function and metabolism.

Adenosine Triphosphate↗
PubMed1988

Structural requirements of salicylanilides for uncoupling activity in mitochondria: quantitative analysis of structure-uncoupling relationships.

The uncoupling activities of more than 20 salicylanilides were measured in rat liver mitochondria. The activities, expressed as the minimum concentrations required for full release of state-4 respiration, ranged over three orders of magnitude. The acid dissociation constant, pKA, and the partition coefficient between octanol and water (Poct) of some of the salicylanilides were determined. These two parameters were found to be well expressed in terms of the Hammett constant, sigma, and the hydrophobic substituent coefficient, II, respectively. The pKA and log Poct values of all the salicylanilides were predicted according to these relationships. Furthermore, the capacity factor, k', on high-performance liquid chromatography was determined on glyceryl-coated-controlled pore glass (gly-CPG). Values of log k' correlated well with those of log Poct. The uncoupling activities of the salicylanilides were analyzed in terms of these three parameters. Both hydrophobic and electron-withdrawing properties were found to be essential for induction of potent uncoupling activity. The correlations using log k' were better than those using log Poct.

Animals↗
PubMed1988

Long-term corneal endothelial changes after intraocular lens implantation.

We studied the morphologic characteristics of the corneal endothelium in a series of patients who had undergone phacoemulsification with intraocular lens implantation performed by one surgeon. Specular microscopy and computer-assisted morphometry were performed preoperatively and three years after surgery. Nineteen eyes that received posterior chamber lenses with intracapsular fixation had a mean endothelial cell loss of 18.1%, without any significant change in cell size (polymegethism) or shape variability (pleomorphism). Implantation of anterior chamber lenses with the posterior capsule left intact (18 eyes) caused a similar degree of cell loss (23.5%) but caused marked polymegethism and pleomorphism of the cells. Endothelial cell loss (28.5%) and morphologic changes were greatest in five eyes that received anterior chamber lenses because of a rupture of the posterior capsule.

Cataract Extraction↗
PubMed1988

Bone trabecular pattern analysis in Down's syndrome with the use of computed panoramic tomography with a laser scan system. Quantitative analysis with the power spectrum method.

A quantitative analysis of the mandibular bone trabeculae of 44 patients with Down's syndrome and 68 normal persons by means of panoramic tomography was performed with a laser scan system. The results showed that the normal persons exhibited a correlation between the trabecular pattern and aging, whereas the patients with Down's syndrome showed no such correlation. These findings were consistent with geromorphism, which is one of the systemic features of Down's syndrome.

Adult↗
PubMed1988

Adenine nucleotide metabolites are beneficial for recovery of cardiac contractile force after hypoxia.

In a previous study, we demonstrated a significant release of adenosine, inosine and hypoxanthine during hypoxia and subsequent reoxygenation. The present study was designed to determine whether or not exogenous adenosine, inosine and hypoxanthine are beneficial for the recovery of hypoxia-induced loss of cardiac contractile force. Hearts were perfused for 20 min under hypoxic conditions, followed by 45 min-perfusion under reoxygenated conditions, and changes in contractile force, resting tension and metabolic parameters of the perfused heart were examined. When either adenosine, inosine or hypoxanthine were exogenously infused during hypoxia at the rate of 3 mumol/min, remarkable recovery (61 to 68%) of cardiac contractile force was observed upon reoxygenation. The recovery was accompanied by a significant restoration of myocardial ATP (90 to 100%) and CP contents (80 to 86%), suggesting that exogenous metabolites are utilized for the restoration of myocardial ATP during reoxygenation, which may lead to a beneficial recovery of hypoxia-induced loss of cardiac contractile force upon reoxygenation. Infusion of exogenous metabolites also resulted in an almost complete inhibition of hypoxia- and reoxygenation-induced release of creatine phosphokinase from the perfused heart as well as a significant depression of hypoxia-induced calcium accumulation in the cardiac tissue. Since these phenomena are considered to represent increases in cell membrane permeability, protection of the myocardium against hypoxia- and reoxygenation-induced changes in cell membrane permeability may be an alternative mechanism for the beneficial effect of adenosine, inosine and hypoxanthine on the hypoxic myocardium.

Adenosine↗
PubMed1988

Increased mast cells in the limiting membrane of seminiferous tubules in testes of patients with idiopathic infertility.

In the course of our histological studies on the testes of idiopathically infertile men, we found an increased number of mast cells in the limiting membrane of the seminiferous tubule. In 16 patients with idiopathic infertility, quantification of mast cells within the limiting membrane of the seminiferous tubule was performed. There apparently was a tendency to increased numbers of mast cells in the seminiferous tubule wall with decreased sperm count and an average Johnsen score for each tubule. These findings suggest that quantification of mast cells in the seminiferous tubule wall may be a useful marker in the histopathological evaluation of testis biopsies in patients with idiopathic infertility.

Cell Count↗
PubMed1988

Evaluation of intravesical alum irrigation for massive bladder hemorrhage.

The efficacy of intravesical alum irrigation was analyzed after application to 9 patients with continuous and severe bladder hemorrhage. Causes of bleeding were radiation cystitis in 4 patients, vesical invasion by cervical cancer in 3, bladder cancer in 1 and cyclophosphamide-induced cystitis in 1. Though alum treatment was initially effective for control of massive bladder hemorrhage in all patients, it eventually failed to suppress a subsequent hemorrhage in 2 patients (78% success rate). No significant side effects directly related to this therapy were observed. In conclusion, alum irrigation is effective for controlling massive bladder hemorrhage for a rather short time. Therefore, additional treatment modalities should also be considered for primary diseases.

Administration, Intravesical↗
PubMed1988

Ocular pharmacokinetics of latamoxef and cefaclor in rabbits. Penetration into aqueous humor.

Penetrations of latamoxef (LMOX) and cefaclor (CCL) into the aqueous humor after intravenous or oral administration were investigated in rabbits. Concentrations of antibiotics in plasma and aqueous humor after administration were determined periodically by microbiological assay. LMOX disappeared from plasma in a monoexponential manner with a half-life of 43 min after intravenous administration at a dose of 50 mg/kg. The maximum concentration of LMOX in aqueous humor (6.4 micrograms/ml) was observed 1 h after administration. When CCL was administered orally at a dose of 50 mg/kg, the maximum concentration of CCL in aqueous humor was 1.00 microgram/ml 1.5 h after administration, whereas the maximum plasma concentration of 19.2 micrograms/ml was observed at 30 min. Pharmacokinetic analysis (simultaneous simulation) of plasma and aqueous humor concentration-time courses was made using the best fitted compartment model examined (modified two-compartment model). Prediction of the concentration of antibiotics in aqueous humor from the plasma concentration profile was also examined using the same compartment model in a separate experiment. The predicted concentration in aqueous humor was proved to coincide reasonably well with the measured concentration.

Administration, Oral↗