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Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 667 records · Page 37Linked to original sources
PubMed1990

The difference in the type of codon-anticodon base pairing at the ribosomal P-site is one of the determinants of the translational rate.

By utilizing an enzymatically reconstructed tRNA variant containing an altered anticodon sequence, we have examined the different biochemical behavior of translation between the Watson-Crick type and the wobble type base pair interactions at the first anticodon position. We have found that the Watson-Crick type base pair has an advantage in translation in contrast to the wobble type base pair by comparing the efficiency of transpeptidation of native tRNA(Phe) (anticodon; GmAA) with its variant tRNA (anticodon; AAA) in the poly(U)-programmed ribosome system. Thomas et al. [Proc. Natl. Acad. Sci. U.S. (1988) 85, 4242-4246] showed that the wobble codon at the ribosomal A-site accepted its cognate tRNA less efficiently than the Watson-Crick base pairing codon. We report here that the wobble interaction at the ribosomal P-site also affected the rate of translation. This variable translational rate may be a mechanism of gene regulation through preferential codon usage.

Anticodon↗
PubMed1990

Soluble factor requirements for the Tetrahymena peptide elongation system and the ribosomal ATPase as a counterpart of yeast elongation factor 3 (EF-3).

Peptide elongation factor 3 (EF-3), which is widely present in yeasts and fungi (Eumycota), does not occur in another lower eukaryote, the unicellular protozoan Tetrahymena pyriformis, as was shown by the following findings: (a) there is no activity to satisfy the EF-3 requirement of yeast ribosomes in the post-ribosomal supernatant fraction from Tetrahymena, and (b) the Tetrahymena ribosomes displayed their full capacity for polyphenylalanine synthesis with purified EF-1 alpha and EF-2 alone from either Tetrahymena or yeast, and their activity on the Tetrahymena ribosomes was not further enhanced by the addition of yeast EF-3, in contrast to the case of the yeast ribosomes. However, as a substitute for the ribosome-activated nucleotidase activity of EF-3, Tetrahymena ribosomes were shown to harbor strong, firmly bound ATPase and GTPase activities, which probably involve the same active site. The ribosome-bound ATPase activity was inhibited by a polyclonal antibody raised against yeast EF-3 with the same inactivation profile as that of polyphenylalanine synthesis on Tetrahymena ribosomes, indicating that the ribosomal ATPase plays an essential role in the elongation process on Tetrahymena ribosomes as previously revealed in the yeast system. It was also shown that the ribosomal nucleotidase plays a pivotal role in the elongation cycle in other eukaryotes.

Adenosine Triphosphatases↗
PubMed1990

Rheumatoid factors and glomerulonephritis.

It is presently unknown whether rheumatoid factors have a pathogenic role in the development of various types of glomerulonephritis with immune deposits. Three isotypes of rheumatoid factors (RFs), which are autoantibodies to IgG, were measured using the solid-phase fluorescence immunoassay in sera from patients with diffuse proliferative lupus nephritis (DPLN), membranous lupus nephritis (MLN), IgA nephropathy (IgAN) and idiopathic membranous nephropathy (MN). RF activity of immunoglobulins deposited in the glomeruli from these patients was also studied by examining the binding of the FITC-conjugated human IgG and Fc portion of IgG to the glomeruli of renal biopsy specimens. IgG, IgA and IgM RFs were significantly increased in sera from patients with DPLN, and the increase was significantly lower in patients with MLN, IgAN and MN. Human IgG bound to immunoglobulin on the glomeruli only in DPLN, but not in MLN, IgAN or MN. The Fc portion of IgG was demonstrated to be involved in this reaction. It was suggested that RFs and IgG may play a major role in immune deposits on the glomeruli in DPLN and may be involved in the development of DPLN; however, this is not likely in MLN, IgAN or MN.

Antigen-Antibody Complex↗
PubMed1990

The interaction of neuromuscular relaxants with rabbit lung muscarinic receptors.

The interaction of muscle relaxants with airway muscarinic receptors of rabbit lung was investigated in vitro by the [3H]QNB binding technique. Pancuronium, vecuronium, alcuronium and succinyl choline chloride (SCC) inhibited the binding of [3H]QNB to rabbit lung muscarinic receptors in a dose-dependent manner. The values of IC50 (the concentration giving 50% inhibition) of pancuronium, vecuronium, alcuronium and SCC were 1.54 x 10(-5), 2.52 x 10(-5), 8.40 x 10(-5), and 4.00 x 10(-3) mol/l respectively. As the values of Kd increased with minimal change in the value of Bmax, while not influencing the number of receptors, these muscle relaxants had an inhibitory action on the affinity of muscarinic receptors to [3H]QNB in the order: pancuronium greater than or equal to vecuronium greater than alcuronium greater than SCC. Applying IC50 values to human conditions, clinical doses of these muscarinic relaxants are unlikely to exhibit any significant vagolytic action in lung tissue.

Alcuronium↗
PubMed1990

Subcellular distribution and physicochemical properties of scrapie-associated precursor protein and relationship with scrapie agent.

We studied the biologic properties of hamster-adapted scrapie (strain 263K) and its relationship to the precursor protein of scrapie (PrP33-35Sc). The highest titer of infectious material and the greatest concentration of PrP33-35Sc were in the fractions containing microsomal and synaptosomal membranes. We found traces of infectivity in the absence of PrP33-35Sc associated with matrix protein. Partitioning of membranes with neutral chloroform-methanol resulted in concentration of PrP33-35Sc and infectivity within the interphase layer. Recombination of membrane glycoproteins (interphase) with lipids extracted from homologous brains decreased infectivity greater than or equal to 4 logs. Temperature-dependent phase separation of infected synaptosomal and microsomal membranes with Triton X-114 yielded a phospholipid-rich phase containing a high concentration of PrP33-35Sc and greatest infectivity titers. This material spontaneously formed liposomes, indicating that PrP33-35Sc and PrP33-35C precursor proteins are highly hydrophobic intrinsic membrane components integrated with phospholipids. Homologous membrane phospholipids appear to prevent aggregation of the scrapie isoform of PrP and maintain high levels of infectivity.

Animals↗
PubMed1990

Release characteristics of cisplatin chitosan microspheres and effect of containing chitin.

To increase cisplatin (CDDP) content, to suppress burst effect during the initial phase of drug release, and to improve the capacity of the system for sustained release, we prepared various types of CDDP chitosan microspheres incorporating chitin and investigated the content of CDDP and its in vitro release kinetics from these microspheres. The results of this study showed that the CDDP content increased with increasing chitosan concentration and that the incorporation of chitin in the carrier matrix produced a more pronounced increase in drug content. The addition of chitin also led to inhibition of the initial burst effect. The rate of CDDP release reduced with increasing concentration of chitosan: that is, the 50% CDDP release time was about 0.5 h with the microspheres prepared with 1.0% of chitosan and about 4.5 h with those prepared with 5.0% of chitosan, indicating about nine-fold prolongation. The addition of chitin further resulted in retardation of the rate of CDDP release. Meanwhile, our chitosan microspheres were shown to undergo enzymatic degradation by lysozymes.

Chitin↗
PubMed1990

Effect of nicardipine hydrochloride on circulating blood volume and vascular compliance in dogs.

We studied the effect of nicardipine on the canine cardiovascular system, especially on total blood volume and vascular compliance. Under light halothane anesthesia, nicardipine decreased total blood volume significantly (from 80.0 +/- 8.4 ml/kg in the control state to 75.3 +/- 8.0 ml/kg under nicardipine administration, p less than 0.01), while it increased central circulating blood volume (from 17.1 +/- 5.9 ml/kg to 25.5 +/- 8.2 ml/kg, p less than 0.01), increased cardiac output and central venous pressure, and decreased mean arterial pressure (from 134.3 +/- 16.2 mmHg to 93.9 +/- 17.1 mmHg, p less than 0.01) and total peripheral resistance. Vascular compliance derived from fluid infusion experiments showed a significant decrease (from 8.9 +/- 3.8 ml/mmHg/kg to 5.5 +/- 8.0 ml/mmHg/kg, p less than 0.01). In addition to the vasodilatory action of nicardipine on arteries, these findings also suggest that 1) nicardipine causes a fluid shift from the vascular to the interstitial fluid space as a result of increased capillary pressure, 2) it increases preload through blood redistribution from the peripheral to the central circulation, and 3) it decreases compliance of the vessels, perhaps due to an indirect splanchnic venoconstriction.

Animals↗
PubMed1990

Branching morphogenesis in the embryonic mouse submandibular gland: a scanning electron microscopic study.

The embryonic development of the salivary gland in the mouse was studied by scanning electron microscope (SEM). The submandibular morphogenesis was found to take place within its associated mesenchymal tissue. This stromal mesenchymal element has prevented us from observing three-dimensional details of the branching morphogenesis by SEM. In the present study, we applied a modified Evan's enzymatic digestion method to the embryonic submandibular gland. Consequently, we obtained important information about the morphogenetic events for the branching development of the mouse submandibular gland, demonstrating that a pit and shallow clefts are formed on the lateral aspect of the spherical end bud. This pit and cleft formation likely represents the initial morphogenetic movement of the epithelium that establishes primary branchings. Furthermore, SEM observation of the basal surface of the embryonic epithelial cells provided us views of the developmental change of cell projections probably involving epithelial-mesenchymal contacts.

Animals↗
PubMed1990

Selection of medium for serum-free primary culture of adult rat hepatocytes.

To select a suitable medium for serum-free primary culture of adult rat hepatocytes, ten commercially-available synthetic media were compared for their ability to maintain the cells under serum-free and serum-supplemented conditions with special reference to attachment, survival and albumin secretion. It was found that Williams' medium E and DM-160 medium were the best among the ten media for maintaining hepatocytes under serum-free conditions in primary culture.

Albumins↗
PubMed1990

[Clinicopathological significance of intrahepatic micrometastases in hepatic metastatic carcinomas].

The micrometastases confirmed only by microscopic examination were investigated in resected liver specimen of hepatic metastatic carcinomas. Twenty three hepatic metastases from gastrointestinal carcinomas were subjected. The micrometastases defined as histologically discontinuous from macroscopic metastatic nodules and less than 1mm in diameter, were found in 8 cases (34.8%). These were 0.2 to 1.0mm (0.52 +/- 0.35, mean +/- SD) in diameter, 1 to 19 (4.1 +/- 6.0) in number and were 2.0 to 29.0 mm distant from the macroscopic metastatic nodules. Histological localization of these metastases were in portal vein in most of cases and rarely in sinusoidal space and hepatic vein. These results suggest that the surgical margin in hepatectomy for hepatic metastases is required more than 3 cm from the tumor and therefore wedge resection is not suitable for the choice of the operative procedure for hepatic metastases because of unsatisfactory surgical margin.

Gastrointestinal Neoplasms↗
PubMed1990

Influenza antibody titers after vaccination of chronic renal failure patients; before and during hemodialysis, or on continuous ambulatory peritoneal dialysis.

Anti-influenza antibody (Ab) titers were measured in order to elucidate whether there are any disturbances in Ab production in chronic renal failure (CRF) patients. A total of 55 CRF patients plus 15 normal individuals were vaccinated with influenza vaccine twice, 4 weeks apart of the 55 CRF patients, 15 were not on dialysis, 10 were undergoing hemodialysis (HD), and 30 were on continuous ambulatory peritoneal dialysis (CAPD). Of the 30 CAPD patients, 14 had peritonitis. Serum Ab titers were measured by complement fixation (CF) and hemagglutination inhibition (HI) tests, and IgG and IgM class specific antibodies by ELISA. All groups responded to immunization, but CAPD patients with peritonitis and CRF patients not yet on dialysis did not show a significant elevation in IgM class Ab titers. The number of CAPD patients with peritonitis who achieved positive titers was significantly lower in HI (p less than 0.01) and IgG class antibodies (p less than 0.05) compared with normal controls. Two patients with frequent peritonitis did not show any response to vaccination. It was concluded that patients with renal dysfunction have some abnormalities in Ab production against influenza vaccine, the effects of which were more pronounced in the CAPD patients with frequent peritonitis.

Adolescent↗
PubMed1990

[A comparison of oral- and intramuscular-preoperative administration of ranitidine in children].

The effect of preoperative oral and intramuscular ranitidine administration on intragastric pH and volume was evaluated in children. Thirty healthy inpatients whose ages were 2-13 years, were randomly assigned to three groups. Twelve hours before the elective operation apple juice was given to the control group, and apple juice with 0.4 mg.kg-1 ranitidine to the second group (Oral group). For the third group (IM group) an intramuscular injection of 0.1 mg.kg-1 ranitidine was done. Intragastric pH was significantly elevated and gastric volume was also significantly reduced in IM group, and serum ranitidine concentration showed a high level of 359.4 +/- 85.6 ng.dl-1 (mean +/- SD). In oral group ranitidine effect on pH and volume was not significant, and the drug serum concentration was 31.6 +/- 13.3 ng.dl-1 which was slightly lower than the effective level. Though the intramuscular injection guaranteed safer gastric content, a painful injection is stressful for children. With the knowledge of elimination rate of serum ranitidine we recommend oral ranitidine (0.4 mg.kg-1) six hours preoperatively for pediatric premedication.

Administration, Oral↗
PubMed1990

[Anesthetic management of a patient with progressive spinal muscular atrophy].

Various problems especially weakness of respiratory muscle and abnormal reaction to muscle relaxant exist during the management of anesthesia for the patients with neuromuscular disease with the disturbance of motor neurons. We had a patient for trans-urethral resection of prostate with spinal progressive muscular atrophy. Using nitrous oxide-oxygen with halothane, and without muscle relaxant, we succeeded in avoiding respiratory failure, aspiration and other serious complications. By measuring serum sodium, rapid discovery and treatment of water intoxication could be achieved.

Aged↗
PubMed1990

[Electrophysiological studies on hydranencephaly].

Electrophysiological studies were performed on two children with hydranencephaly that was diagnosed by CT and/or magnetic resonance imaging (MRI). Case 1 was a 4-months-old boy who had no rostral tissue above the midbrain. Case 2 was a 5-years-old boy in whom CT showed the presence of the thalamus. Short latency somatosensory evoked potentials (SSEP) in both cases exhibited the absence of cortical activity (N1 and P4) with the preservation of waves of brainstem origin. However, in case 1, the wave component N0 was not observed, while N0 was seen in case 2. Thus, the N0 was component of SSEP on median nerve stimulation in children, which corresponds to N16 in adults, may originate in the thalamus.

Child, Preschool↗
PubMed1990

[Double chambered right ventricle: surgical experience in a 60-year-old woman].

The patients reported as double chambered right ventricle are mainly children. A 60-year-old woman had been pointed out for her systolic cardiac murmur without any symptom. She was admitted to our hospital for her gradual onset of fatigue, lassitude. Cardiac catheterization data revealed a 105 mmHg peak-to-peak gradient within the right ventricular cavity with normal pulmonary pressures [20/5 (12) mmHg]. Right ventricular end-diastolic pressure was 4 mmHg. Right ventriculogram demonstrated double chambered right ventricle. Electrocardiogram showed neither right ventricular hypertrophy nor upright T wave in V3R. In order to release intraventricular pressure gradient and her symptom, the anomalous muscle bundles were resected through both the right atrium and the pulmonary artery. Surgical repair without right ventriculotomy is suitable for such an elder patient with double chambered right ventricle whose ventricular function may decrease.

Age Factors↗