Search PubMed⌕ Search

Biomedical subjects

Y Nakada

Publications and source records attributed to Y Nakada.

At least 73 records · Page 4Linked to original sources
PubMed1991

Metabolism of 2,4-dinitrotoluene by Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6, and mutagenicity of the metabolites of 2,4-dinitrotoluene and related compounds to strains TA98 and TA100.

The products detected in the incubation of 2,4-dinitrotoluene (2,4-DNT) with Salmonella typhimurium strains TA98 and TA98/1,8-DNP6 were nitrosonitrotoluenes, hydroxylaminonitrotoluenes, aminonitrotoluenes and dimethyl dinitroazoxybenzene. The capacity of TA98NR to reduce 2,4-DNT was much lower than that of TA98 and TA98/1,8-DNP6. The bacterial products showed no mutagenic activity in the Ames assay using TA98 and TA100. These results indicate that the lack of mutagenic activity of 2,4-DNT is not due to low reductive metabolism of 2,4-DNT by the bacteria, but to the lack of mutagenic activity of the bacterial reductive products of 2,4-DNT, including dimethyl dinitroazoxybenzene.

Acetylesterase↗
PubMed1991

[Anxiolytic effects of lisuride and its agonistic action to central 5-HT1A receptors].

Effects of lisuride, a derivative of ergot alkaloid, on central 5-HT1A receptors were investigated biochemically, behaviorally and electroencephalographically (EEG) in rats and rabbits. Effects of lisuride in water-lick conflict tests were also investigated in rats. Lisuride was found to strongly inhibit the bindings of [3H]8-OH-DPAT to 5-HT1A receptors in the raphe nucleus, hippocampus, cortex, amygdala and hypothalamus of rat brain. Inhibitory effects of lisuride on bindings of [3H]8-OH-DPAT in the hippocampus was almost the same as that of 5-HT (Ki = 0.5 nM) and stronger than those of the 5-HT agonist 5-MeO-DMT (Ki = 2.1 nM) or other ergot derivatives (bromocriptine and pergolide, Ki = 3.0 nM). Lisuride (0.1-0.5 mg/kg, i.p.), like 8-OH-DPAT, dose-dependently induced a 5-HT behavioral syndrome in rats. Lisuride affected locomotor activity in rats, whereas 8-OH-DPAT did not. In hippocampal EEG of rabbits, lisuride (0.01-0.03 mg/kg, i.v.), like 8-OH-DPAT and diazepam, dose-dependently inhibited rhythmical slow activity (RSA) induced by acoustical stimulation (3100 Hz) and also inhibited the RSA increased by administration of anxiogenic FG7142. In water-lick conflict tests, lisuride (0.05-0.1 mg/kg, i.p.), like diazepam, increased the number of shocks. These findings indicated that lisuride acts as a strong agonist on central 5-HT1A receptors and suggested that lisuride might be a potential anxiolytic.

Animals↗
PubMed1991

[Interaction of the hypnotic lormetazepam with central benzodiazepine receptor subtypes omega 1, omega 2 and omega 3].

To clarify the action of lormetazepam, 3-hydroxybenzodiazepine, on the benzodiazepine (BZ) receptor subtypes, effects of lormetazepam on motor performance in the traction test and hexobarbital-induced loss of righting reflex in mice and the binding to BZ receptor subtypes were investigated in comparison with those of other BZ hypnotics. Lormetazepam prolonged the duration of hexobarbital-induced loss of righting reflex. The minimal effective dose (1 mg/kg, p.o.) was higher than that of flunitrazepam, lower than those of diazepam and zopiclone, and the same as those of triazolam and brotizolam. Lormetazepam showed the ataxic effect at 10 mg/kg, p.o., but the separation between its effective doses for the hypnotic and ataxic effects was the largest among the hypnotics tested. In the displacement study on [3H]flumazenil binding to cerebellar and spinal cord membranes, lormetazepam bound with a higher affinity to omega 1 receptor (Ki = 10 nM) than to omega 2 receptor (Ki = 29 nM). The GABA-ratios of lormetazepam to omega 1 and omega 2 receptors were 3.9 and 4.0, respectively; and they were higher and lower than those of flunitrazepam to omega 1 and omega 2 receptors, respectively. In the displacement study on [3H] Ro5-4864 binding to kidney membranes, lormetazepam bound with a lower affinity to the omega 3 receptor (Ki = 213 nM) than flunitrazepam. Thus, lormetazepam was suggested to be a potent hypnotic with weaker ataxic effects than other BZ hypnotics, which may be due to its selective and potent agonistic action on central omega 1 receptors.

Animals↗
PubMed1991

Portable digital subtraction angiography in the operating room and intensive care unit.

A simple, inexpensive method of portable digital subtraction angiography (DSA) using an image processor (Sigma X), still-videorecorder and control panel combined with a surgical x-ray television unit can provide real time subtraction images on the monitor. This portable DSA unit was used in 161 cases (130 in the operating room and 31 in the intensive care unit). In the operating room it is useful: 1) to confirm patency of the parent artery and its branches after aneurysm clipping, 2) to identify feeding arteries of arteriovenous malformation and to confirm total extirpation, 3) to confirm the patency of extracranial-intracranial bypass, 4) to confirm patency of the internal carotid artery and absence of flap formation after carotid endarterectomy. In the intensive care unit, it is particularly useful for visualizing cerebral vasospasm after subarachnoid hemorrhage and recanalization of an occluded major intracranial artery. Absence of intracranial circulation can be demonstrated in patients with suspected brain death.

Angiography, Digital Subtraction↗
PubMed1991

[An elderly case of idiopathic retroperitoneal fibrosis].

An elderly case of idiopathic retroperitoneal fibrosis (IRPF) with bilateral ureteral obstruction was reported. A 74-year-old man was admitted with complaints of general fatigue and loss of appetite. An elastic hard mass with a smooth surface was palpated in the left upper quadrant of the abdomen. Abnormal ESR and CRP were noticed. Abdominal ultrasonography showed both a homoechoic mass which surrounded the aorta in the retroperitoneal space and bilateral hydronephrosis. Computed tomography revealed a retroperitoneal mass involving bilateral ureters. Magnetic resonance imaging demonstrated a mass with a sharp image and signal intensity. Furthermore the morphological relationship between the mass and the ureters and major vessels clearly indicated the characteristics of benign retroperitoneal fibrosis. Based upon the above findings, a diagnosis of IRPF was made. After confirming the histological diagnosis by biopsy, treatment consisting of bilateral ureterolysis, intra-abdominal transposition of ureters and oral administration of prednisolone was performed, resulting in a normalization of laboratory findings. Analysis of 86 previously cases of IRPF reported up to 1990 in Japan, revealed the peak age to be in the 7th decade with predominance in males (males: females = 57:29).

Acute Kidney Injury↗
PubMed1991

Cross-resistance patterns in ACNU-resistant glioma sublines in culture.

Three ACNU-resistant clones (R1, R3, and R12) were isolated from 9L rat glioma cells under selection pressure of ACNU in vitro. The authors have investigated the mechanisms of resistance and characteristics of these clones at the cellular level by studying cross-resistance patterns to chemical and physical agents. Although these resistant sublines showed complete cross-resistance to methyl-chloroethylnitrosourea (MCNU), no cross-resistance was observed for other alkylating agents, while each of the resistant sublines showed partial cross-resistance to structurally dissimilar toxic agents (vinblastine, Adriamycin, and VP-16). No difference in ACNU uptake was observed between 9L and R3 cells, and resistance patterns among alkylating agents suggested that the mechanism of ACNU resistance was specific to bifunctional nitrosoureas. Based on a transport study, this multidrug resistance could be explained by reduced intracellular uptake of these drugs, but there seemed little possibility that membrane P-glycoprotein, which usually is observed in typical multidrug-resistant cells, was expressed in these ACNU-resistant cells because enhanced drug efflux was not found in ACNU-resistant sublines. Significant collateral sensitivity to L-asparaginase indicated that ACNU might disturb the asparagine synthetic pathways by its mutagenic action. The increased level of total glutathione in the resistant sublines may be one mechanism of radiation or ACNU resistance.

Animals↗
PubMed1991

Hypersensitivity of rat glioma sublines with acquired ACNU resistance to L-asparaginase.

Cell lines resistant to 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3- (2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) show a high degree of collateral sensitivity to L-asparaginase. The mechanism for this phenomenon was investigated by comparing the nutritional requirements and asparagine synthetase activity of the resistant sublines to those of parent cells. Nine ACNU-resistant sublines were isolated from rat glioma 9L cells after incubation with various concentrations of ACNU in Ham's F-12 medium. The 9L cells grew independently of asparagine, developing well in asparagine-deficient Dulbecco's modified Eagle's medium. In contrast, the growth rates of all nine ACNU-resistant sublines decreased under the same conditions and required the addition of 10(-4) M asparagine for maximum growth. Asparagine synthetase activity in the ACNU-resistant cells was much lower than in the 9L cells, suggesting that the requirement for asparagine in the resistant sublines was due to reduced activity of this enzyme. A growth-inhibition assay showed that the ACNU-resistant sublines were more sensitive to L-asparaginase than 9L cells by up to 2 x 10(5)-fold. These results suggest that L-asparaginase therapy has the potential to become a new approach for treating acquired ACNU resistance.

Animals↗
PubMed1991

Synthesis of 5-keto-5-oxime derivatives of milbemycins and their activities against microfilariae.

Starting from milbemycin D (1), milbemycin A4 (2) and milbemycin A3 (3), a series of 5-keto-5-oxime derivatives were synthesized by selective oximation at the alpha,beta-conjugated carbonyl function of the 5-ketomilbemycins (4-6). The activities of the synthesized compounds were studied in dogs naturally infested with microfilariae of Dirofilaria immitis. The 5-keto-5-oximes of milbemycin D (7), A4 (8) and A3 (9) had quite high efficacy to control the microfilariae and more potency than their parents, while the 5-O-acyl oximes (11-15) also exhibited high activity.

Animals↗
PubMed1991

Comparison of the acute hemodynamic and coronary vasodilating effects between nicorandil and glyceryl trinitrate.

Acute hemodynamic and coronary vasodilating effects of nicorandol (SG-75, Sigmat; CAS 65141-46-0) and glyceryl trinitrate (GTN, nitroglycerin) were examined in 20 subjects under cardiac catheterization and coronary arteriography. Nicorandil 4 mg i.v. produced significant increases in heart rate, cardiac index and stroke volume index and significant decreases in systolic, diastolic and mean blood pressure, pulmonary capillary wedge pressure, left ventricular enddiastolic pressure, systemic vascular resistance and total pulmonary resistance. Degree of percent changes in these parameters by nicorandil were similar to that by GTN 0.3 mg i.v. Coronary vasodilating effects of both drugs were also at the same degree. Results indicate that nicorandil has cardiovascular and coronary vasodilating effects similar to those of GTN when administered intravenously.

Adult↗
PubMed1990

Determination of the antiplatelet agent. KB-3022, and its metabolite by high-performance liquid chromatography.

A rapid, accurate and reproducible high-performance liquid chromatographic method for the simultaneous determination of a new antiplatelet agent, ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetate (KB-3022), and its main metabolite, 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetic acid (desethyl KB-3022), in biological fluids has been developed. KB-3022 and desethyl KB-3022 in plasma or urine were extracted with a mixture of n-hexane and dichloromethane (1:1), separated on a reversed-phase C18 column with a mixture of 0.01 M (NH4)2HPO4 (pH 3.0), acetonitrile and isopropyl alcohol as a mobile phase, and quantitated by ultraviolet absorbance measurement at 340 nm. 4-[2-(4,5-bis(4-methoxyphenyl)thiazol-2-yl)pyrrol-1-yl]butyric acid was used as an internal standard. The detection limit of KB-3022 in plasma was 3 ng/ml, and that of KB-3022 in urine and desethyl KB-3022 in plasma or urine was 1 ng/ml. The coefficients of variation for the determination of KB-3022 or desethyl KB-3022 in plasma or urine were below 5.6%. This method was applied to the determination of the plasma concentration of KB-3022 and desethyl KB-3022 after intravenous administration to rats.

Animals↗
PubMed1989

IS421, a new insertion sequence in Escherichia coli.

The nucleotide sequence of a new insertion sequence (IS) in Escherichia coli, IS421, was determined. It is 1340 bp long and contains inverted repeats of 22 bp at its termini. It is flanked by 13 bp direct repeats apparently generated upon insertion. There are two ORFs longer than 200 bp in IS421. One can encode a polypeptide of 371 amino acids (aa) and the other, which is on the other strand, can encode a polypeptide of 102 aa. The C-terminal part of the 371 aa polypeptide shows some homology to that of transposases encoded in some other known IS elements. The copy number of IS421 in chromosomal DNA was 4 for E. coli K-12 and B, and 5 for E. coli C, as determined by the Southern hybridization of restriction fragments.

Amino Acid Sequence↗
PubMed1989

Molecular cloning and the nucleotide sequence of the Clostridium thermocellum trpE gene.

The trpE gene of Clostridium thermocellum, a moderately thermophilic and absolutely anaerobic bacterium, was cloned by its ability to complement growth of an Escherichia coli tryptophan auxotroph (trpE) deficient in anthranilate synthase I. The nucleotide sequence of trpE and its flanking region was determined. The trpE gene overlapped at the termination codon with a putative initiation codon of trpG (trp[G]D), as deduced from the amino acid sequence homology with anthranilate synthase II of Serratia marcescens. S1-nuclease mapping of the trpE transcript produced in E. coli cells suggested that the promoter of C. thermocellum was utilized by E. coli. The amino acid sequence of anthranilate synthase I of C. thermocellum predicted from the nucleotide sequence is more similar to that of an extremely thermophilic bacterium, Thermus thermophilus HB8, than that of mesophilic bacteria.

Amino Acid Sequence↗
PubMed1989

The effect of bile salts on the oral mucosal absorption of human calcitonin in rats.

The relationship between the inhibition of the degradation of human calcitonin (HCT) in the supernatant of the rat's oral mucosa homogenate and the promoting effect on the rat's oral mucosal absorption of HCT was investigated by using ten kinds of sodium bile salts. The promoting effects and the inhibition of the degradation by the dihydroxy bile salts were related to the hydrophobicity, respectively. The inhibition of the degradation of HCT was related to the promoting effect on the oral mucosal absorption of HCT in the presence of the dihydroxy bile salts and to the concentration of the bile salts. Furthermore, the micelle formed by the bile salts would be concerned with the inhibition of the degradation of HCT.

Absorption↗
PubMed1989

[Effects in animal models of depression of lisuride alone and upon coadministration with antidepressants].

Effects of lisuride, a central dopamine and serotonin agonist of the ergot type, in animal models of depression were investigated in comparison with those of desipramine, mianserin and rolipram. Lisuride, like desipramine and mianserin, inhibited reserpine-induced hypothermia in mice (0.5-5.0 mg/kg, i.p.) and suppressed muricide in olfactory bulbectomized rats (ED50 = 0.16 mg/kg, i.p.) in a dose-dependent manner. The anti-muricidal effect was slightly enhanced by the repeated administration of 0.25 mg/kg lisuride. Lisuride (0.05-0.25 mg/kg, i.p.), like desipramine, dose-dependently reduced the duration of immobility in rats forced to swim, and this effect was antagonized by haloperidol. The reduction of immobility time was enhanced by the repeated administration of lisuride; at the same time, the ambulation in rats increased. Furthermore, the immobility-reducing effects of desipramine and rolipram were markedly enhanced by the co-administration of a low dose of lisuride (0.025 mg/kg, i.p.), which by itself had no effect on the immobility time. These results indicate that lisuride may be useful for the treatment of depression and indicate that a low dose of lisuride may enhance the clinical effectiveness of antidepressants such as desipramine.

Agonistic Behavior↗
PubMed1989

[Pulmonary embolism as a complication in neurosurgical patients].

The overall incidence of pulmonary embolism (PE) among neurosurgical in-patients, whose ages ranged from 23 to 80, was 0.7%. Our report here is based on five cases of patients with PE. Four of these five patients were over 50 years of age. They had been admitted because of such reasons as brain tumor, spinal cord injury, intracerebral hematoma, and venous sinus thrombosis. Deep vein thrombosis (DVT) was seen in four but none were diagnosed before they had developed PE. Decreased level of consciousness and prolonged bed rest appeared to be common risk factors for PE. Mean duration between admission and onset of PE was 31 days. Although non-specific, tachycardia, tachypnea and hypoxemia were the most common signs and symptoms. As a definitive diagnostic procedure, pulmonary angiography was performed in most of cases. One patient required surgical embolectomy and others were treated with anticoagulation or fibrinolytic agents. In order to prevent recurrent thromboembolic phenomena, ligation of the inferior vena cava was a useful mode of treatment when anticoagulation was not indicated. And this approach seemed to be valid in most neurosurgical patients. We conclude that PE and DVT were not uncommon complications among Japanese neurosurgical patients and they can be treated successfully in collaboration with a cardiovascular surgeon if the diagnosis can be made correctly.

Adult↗
PubMed1989

[General pharmacology of T-3262, a new pyridonecarboxylic acid].

General pharmacological activities of (+/-)-7-(3-amino-1-pyrrolidinyl)-6-fluoro-1-(2,4-difluorophenyl)-1,4- dih ydro- 4-oxo-1,8-naphthyridine-3-carboxylic acid p-toluenesulfonate hydrate (T-3262), which is a new pyridonecarboxylic acid, were examined with the following results. 1. Central nervous system: T-3262 did not show any significant pharmacological effects at oral doses of 100-1,000 mg/kg but caused slow waves in spontaneous EEG in cats at intravenous doses of 10-30 mg/kg. 2. Respiratory and cardiovascular system: T-3262 produced little effect in normotensive rats and anesthetized rabbits at oral doses of 100-1,000 mg/kg and intravenous doses of 3-30 mg/kg, respectively. But T-3262 caused, dose-dependently, an increase of respiratory rate, hypotension, decrease of heart rate and changes in ECG patterns (elevation of T waves, slow amplitudes of QRS complexes and prolongation of RR interval, etc.) in anesthetized dogs at intravenous doses of 3-10 mg/kg. 3. Renal functions: T-3262 increased electrolyte excretions at oral doses of 300-1,000 mg/kg but did not affect PSP excretion in rats. 4. Autonomic nervous system and smooth muscle organs: T-3262 exerted slight inhibition of gastric output in rats and slight miosis in mice at an oral dose of 1,000 mg/kg. But T-3262 did not affect the contraction of nictitating membrane in anesthetized cats at intravenous doses of 1-30 mg/kg. T-3262 increased spontaneous motilities of isolated stomach, ileum and uterus, but decreased that of isolated colon at concentrations of 10(-5)-10(-4) g/ml. 5. Hematological examinations: T-3262 did not show any significant effects on bleeding time, blood coagulation, platelet aggregation and blood glucose level in rats at oral doses of 100-1,000 mg/kg. 6. Miscellaneous effects: T-3262 exerted slight inhibitions of gastric secretion and of carrageenin-induced hind paw edema in rats at a dose of 1,000 mg/kg administered intraduodenally and orally, respectively. T-3262 did not affect neuromuscular junction and bile secretion in rats at intravenous doses of 3-30 mg/kg and oral doses of 100-1,000 mg/kg, respectively. From these results, it can be assumed that T-3262 has a wide safety margin as an oral antibacterial agent.

4-Quinolones↗