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Biomedical subjects

S Sakurai

Publications and source records attributed to S Sakurai.

At least 217 records · Page 12Linked to original sources
PubMed1990

Differentiation of restriction sites in ribosomal DNA in the genus Apodemus.

Southern blot analysis of ribosomal DNA (rDNA) from seven species of Apodemus was carried out in order to examine the genetic relationships between the species. Analysis of heterogeneity in rDNA spacers in A. sylvaticus, A. flavicollis, A. semotus, A. agrarius, A. argenteus, A. speciosus, and A. peninsulae, using 13 different restriction enzymes and cloned mouse rDNA probes, revealed that the families of rDNA in these species can be characterized by restriction maps which show the major constituents of rDNA repeating units (repetypes). Based on differences in the arrangement of restriction sites, sequence divergence among the different major repetypes was estimated. Among the seven species of Apodemus examined, the major repetypes of A. flavicollis and A. sylvaticus were the most closely related, having only 1.0% sequence divergence. These repetypes and those of the remaining five species differ substantially from one another, with 4.3-8.5% divergence.

Animals↗
PubMed1990

Developmental regulation of calmodulin-dependent adenylate cyclase activity in an insect endocrine gland.

The insect prothoracic gland produces ecdysteroids that elicit molting and metamorphosis, and neurohormone stimulation of steroidogenesis by this gland involves both Ca2+ and cyclic adenosine monophosphate second messengers. Prothoracic gland adenylate cyclase exhibits a complex Ca2+/calmodulin (CaM) dependence, a component of which requires an activated Gs alpha for expression. A developmental switch in this system has been identified that correlates with a change in both regulation and function of the gland and involves the loss of sensitivity to extracellular Ca2+ at a time approximately concurrent with the loss of Ca2+/CaM sensitivity by the adenylate cyclase. The extent of cholera toxin activation of gland Gs alpha is lowered before this developmental switch. However, no alterations in Gs alpha levels or mobility are detected, suggesting that Gs alpha interaction with another component in the signaling pathway, perhaps adenylate cyclase itself, produces the apparent Ca2+/CaM dependence and influences the ability of toxin to modify Gs alpha.

Adenylyl Cyclases↗
PubMed1990

Bacterial Accumulation of Metallic Compounds.

Xanthomonas maltophilia accumulated metals or metallic compounds within the cell in the form of one or a few particles, in a peculiar condition similar to that of an electrolyte solution in an electric cell. The particles consisted of many little granules, most of which were assumed to be composed mainly of a compound of zinc and phosphorus in an amorphous state.

Journal Article↗
PubMed1990

Molecular mechanism of growth hormone (GH) deficiency in the spontaneous dwarf rat: detection of abnormal splicing of GH messenger ribonucleic acid by the polymerase chain reaction.

The spontaneous dwarf rat (SDR) is an experimental model for pituitary dwarfism with an autosomal recessive mode of inheritance. In the pituitary of the SDR, neither GH cells nor GH protein were detected by immunological methods, but SDR pituitary has a very small amount of GH mRNA. In the present study the effects of GH-releasing factor and an analog of its second messenger, (Bu)2cAMP, on the total accumulation and secretion of GH were studied in primary cultures from SDR pituitaries. GH-releasing factor and (Bu)2cAMP increased the amount of GH mRNA, but neither accumulation nor secretion of immunoreactive GH was detected. These results suggested that the mutation is not manifest during transcription, but at a later stage. The GH gene of SDR was cloned, and its sequence was determined. A point substitution was found in the consensus sequence of the 3' splice site of the third intron. Judging from this point mutation, one would predict an abnormal splicing and a 1-base deletion in the GH mRNA. Therefore, the fragment of SDR GH cDNA in which the deletion was predicted was amplified by the polymerase chain reaction. Its sequence analysis confirmed that the SDR GH mRNA had 1 base deletion which must cause a premature translational termination of GH mRNA. These results demonstrate that GH deficiency in SDR is caused by a point mutation in the GH gene producing an abnormal splicing of GH mRNA.

Animals↗
PubMed1990

Anionic complex-carbohydrate units of human thyroglobulin.

Human thyroglobulin (hTG) contains sulfate in chondroitin 6-sulfate chains and in complex carbohydrates. In this study the sulfate-containing complex carbohydrates were characterized by the number of sulfate and sialic acid residues that they contain. Samples of normal and nodular thyroid tissue were incubated for 16 h in [35S]sulfate-containing medium, and hTG was purified from the tissues and the media. Complex carbohydrates were enzymatically removed from hTG. Subsequent analysis on an HPLC anion exchange column at pH 2.2 separated the carbohydrate units according to their number of negative charges. Sulfate-containing peaks were monitored by radioactivity, and sialic acid-containing peaks were identified by their shift to lower charge after treatment with neuraminidase. Peaks corresponding to sialic acid-free carbohydrate units with one to four sulfates were identified. Also, carbohydrate units with two and three negative charges containing both sulfate and sialic acid were present. In the nodular tissue of one patient there were more sulfated units with higher charge, especially units containing sialic acid. In this patient the proportion of sulfated polyvalent units with sialic acid was 22.4% for normal and 64.6% for nodular tissue. No difference in the composition of the charged units between the tissues and their corresponding media was seen, making it unlikely that the sulfate-containing carbohydrates play a role in hTG release. It is concluded that hTG contains complex carbohydrate units with up to four sulfate groups and units with both sulfate and sialic acid. In some patients, the sulfate-containing anionic carbohydrate units of hTG from normal and nodular thyroid tissue are different.

Anions↗
PubMed1990

[Novel phenoxyalkylamine derivatives. VI. Synthesis and alpha-blocking activity of alpha-[(phenoxyethylamino)propyl]-alpha-phenylacetonitrile derivatives].

alpha-[(Phenoxyethylamino)propyl]-alpha-(4-methoxyphenyl) acetonitrile derivatives possessing methyl, bromo, nitro, amino or various sulfonamide groups at 3-position on ring A and an alkoxy group on ring B were synthesized. Their alpha-blocking activities were tested. The activity of 5-[1-cyano-4-[[2-(2-ethoxyphenoxy) ethyl]amino]-1-isopropylbutyl]-2-methoxy-benzenesulfonamide (15a) and 5-[1-cyano-4-[[2-(5-fluoro-2-methoxyphenoxy)ethyl] amino]-1-isopropylbutyl]-2-methoxybenzenesulfonamide (15c) was close to that of prazosin, a typical alpha-blocker. Structure-activity relationship of these derivatives is also stated.

Acetonitriles↗
PubMed1990

Genetic breeding of L-tyrosine producer from Brevibacterium lactofermentum.

A wild-type parent of Brevibacterium lactofermentum was converted into an L-Tyr producer by three steps of genetic breeding. First, acquirement of m-fluoro-D, L-phenylalanine resistance (1,000 microgram/ml) brought about MF1317 which produced 3.5 g/l of L-Tyr and a byproduct of 2.8 g/l of L-Phe. Second, increase in the drug resistance (5,000 microgram/ml) gave MF358 that produced 6.4 g/l of L-Tyr and a byproduct of 6.0 g/l of L-Phe. Third, an L-Phe auxotrophic mutant (FT-1) derived from MF358 accumulated 16 g/l of L-Tyr. In FT-1, L-Phe was not accumulated at all, but a small amount of anthranilate (0.4 g/l) was. A key enzyme in the biosynthesis of L-Tyr, 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase, was free from synergistic feedback inhibition by L-Tyr and L-Phe in the producers, and so L-Tyr accumulation occurred independently of L-Phe concentration in the production medium.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1990

[Pharyngeal area measured by acoustic reflection technique while breathing room-air].

Although there have been many reports on the airway area measured by breathing 80% He-20% O2 (He-O2) using the acoustic reflection technique (ART), there have been no reports on that by breathing room-air (Air) because of the lack of accuracy in evaluating the trachea. When measuring with He-O2, accidental introduction of Air into the airway makes the measurement inaccurate. Moreover, it is a time-consuming method and is hardly applicable to dyspneic patients. Therefore, we tried to assess whether the airway area, especially the upper airway, can be measured while breathing Air. In order to compare the areas determined by the two methods, area-distance functions from the pharynx to the trachea were arbitrarily divided into 9 divisions at interval of 2.8 cm. Each of these divisions was respectively compared. We took averages of the pharyngeal, tracheal areas in 8 normal subjects. We found no significant difference between the oropharyngeal area measured by breathing Air and that measured by breathing He-O2, and found a significant correlation between them. There was a significant correlation between the hypopharyngeal areas when using the two methods. The average tracheal area by breathing Air is 4.96 +/- 0.50 cm2, which is 40% above that when measured using He-O2 (3.55 +/- 0.32 cm2). In contrast, the average pharyngeal area when breathing Air is 4.13 +/- 0.93 cm2, which overestimates that by breathing He-O2, namely 3.54 %/- 0.84 cm2 by only 17%. In conclusion, it is possible and useful to estimate the pharyngeal area by breathing Air.

Acoustics↗
PubMed1990

[A role of ultrasound in radiotherapy of metastatic bone tumors].

The efficacy of ultrasonography was evaluated in radiotherapy for 32 patients with 82 metastatic bone tumor regions. Except for vertebral columns, ultrasonography was useful to detect metastatic bone tumors. Ultrasonography was applied to the radiotherapy planning in 21 regions, and was useful for the evaluation of radiotherapy effects in 22 regions. An appearance of "anechoic band" was useful for estimating tumor localization, and may be useful for the determination of the adequate dosage for palliative irradiation. Ultrasonography enable accurate localization of tumors such as sternal or costal metastases that are difficult by fluoroscopy. This means should be executed by radiotherapists.

Adenocarcinoma↗
PubMed1989

Establishment of strongly neutralizing monoclonal antibody to human interleukin-6 and its epitope analysis.

Three monoclonal antibodies against human interleukin-6 were established and characterized. One antibody was shown to strongly neutralize both the Ig-inducing and hybridoma/plasmacytoma growth activity of interleukin-6. The results of its epitope analysis using protease treated interleukin-6 and immobilized antibody indicated that this neutralizing antibody binds to a peptide corresponding to Leu151-Lys171 of interleukin-6 molecule. Further analysis using synthetic peptides showed that a shorter peptide corresponding to Ala153-Thr162 can also inhibit the binding of the antibody to interleukin-6. These results suggest that this carboxyl-terminal region plays a crucial role in interleukin-6 functions.

Amino Acid Sequence↗
PubMed1989

[NK activity in various liver diseases--especially the relation between NK activity and reserve function of the liver in liver cirrhosis and hepatocellular carcinoma].

NK activity in acute viral hepatitis, chronic hepatitis, liver cirrhosis (LC), metastatic liver cancer and hepatocellular carcinoma (HCC) was preserved and had no significant change compared with the normal control in each disease. In acute hepatitis, NK activity was higher in convalescent phase than in acute phase. Although in LC and HCC, some liver functions such as total bilirubin, the rate of ICG 15' excretion, AFP and IAP did not have significant correlation with NK activity, advanced cases according to Child's classification and E factor which was anatomical extent of HCC in liver showed significantly low NK activity. The low NK activity group advanced much more in Child's classification, performance status, stage and E factor of HCC than high NK activity group significantly. According to those facts, LC or HCC is not a single entity of disease in view point of NK activity. NK activity may change in accordance with the advancement of hepatic disease and reserve function of the liver in LC and HCC.

Adult↗
PubMed1989

Short-loop negative and positive feedback on ecdysone secretion by prothoracic gland in the tobacco hornworm, Manduca sexta.

Ecdysteroid production by the prothoracic glands of the tobacco hornworm, Manduca sexta was found to be under feedback control by the ecdysteroids in hemolymph using both culture in vivo in diapausing pupae lacking the brain-corpora cardiaca-corpora allata complex and the prothoracic glands and culture in vitro. Prothoracic glands having relatively high activity in larvae, prepupae, or developing pupae were inhibited by ecdysone or 20-hydroxyecdysone. By contrast, prothoracic glands with low activity from feeding larvae, day 1 non-diapausing pupae and diapausing pupae were activated by both ecdysone and 20-hydroxyecdysone in vivo and in vitro. Dose-response studies on diapausing pupal glands showed that ecdysone was the most effective activator. These findings suggest that prothoracic glands are either stimulated or inhibited by ecdysone or 20-hydroxyecdysone, depending on both the secretory activity of the gland and the effective level of ecdysteroids in hemolymph. Thus, when the glands are first activated, the ecdysteroids that are secreted show a positive feedback on the glands to increase ecdysteroid output. Then the activated glands are turned off by the increasing 20-hydroxyecdysone titer in the hemolymph leading to the rapid decrease in ecdysteroid titer at the end of the molt period.

Animals↗
PubMed1989

Juvenile hormone inhibits ecdysone secretion and responsiveness to prothoracicotropic hormone in prothoracic glands of Bombyx mori.

The role of juvenile hormone (JH) in the regulation of prothoracic gland activity was investigated during the early days of the last (fifth) larval instar of Bombyx mori. Allatectomy on the day of larval ecdysis into the fifth instar or 1 day before ecdysis shortened the time between larval ecdysis and gut purge. Prothoracic glands of the freshly ecdysed fifth instar larvae were inactive and did not respond to the prothoracicotropic hormone (PTTH), whereas those larvae that were allatectomized 1 day before ecdysis exhibited secretory activity in vitro and were capable of responding to PTTH. When corpora allata were removed from freshly ecdysed fifth instar larvae, the prothoracic glands became competent to respond to PTTH in 6 hr and exhibited secretory activity in vitro 9 hr after the allatectomy. Treatment of allatectomized larvae with a JH analog resulted in the recovery of the normal inactive state of the glands. These data suggest that JH acts during the early stages of the instar to suppress both the secretory activity of prothoracic glands and also the acquisition of competence to respond to PTTH.

Animals↗
PubMed1989

[Postoperative enterocolitis and current status of MRSA enterocolitis--the result of a questionnaire survey in Japan].

There is a trend of increase in the number of Staphylococcus aureus infection recently, and postoperative enterocolitis due to methicillin resistant strains is appearing. Because of this, a nation wide questionnaire survey on postoperative enterocolitis was conducted to clarify the status since 1980. Of the 875 major surgical institutes to which we sent the questionnaire, 370 (42.3%) replied and 67 case reports were obtained from 25 institutes. Twenty published reports were added to this and a total of 87 cases were evaluable. The number of postoperative enterocolitis increased after the year 1985, and those resulting from MRSA infection were more frequent in the northern half of Japan including the Kanto area. It was more frequent in males and the mean age was 57.9. Their onset was sudden, beginning with diarrhea and/or fever between the second and fifth postoperative days. In most of the cases, the cephalosporin group of antibiotics, especially of the third generation, were administered preceding the enterocolitis. Six of cases (24%) did not survive, and in some of the institutes they were considered to be hospital infections, as they appeared consecutively between a short period of time.

Adult↗
PubMed1989

High-frequency ventilation by bilateral phrenic nerve stimulation in dogs.

We succeeded in achieving good gas exchange by oscillatory phrenic nerve stimulation (PNS) in dogs. In 7 out of 14 dogs, adequate gas exchange was attained by PNS at 3, 4 and 5 pulses per sec (pps). VE increased with stimulation frequency up to 4 or 5 pps, but decreased above 6 pps. We also applied sinusoidal oscillation using a piston pump at the trachea in the same dogs to analyze the mechanical properties of the respiratory system. The V/P ratio, oscillatory volume divided by driving pressure, decreased markedly at 6 Hz while the pleural pressure remained constant up to 10 Hz. These facts indicate that the fall in VE is due to mechanical properties of the airway and lung, and not due to failure of the ventilatory pump system. We conclude that frequencies of 3-5 pps in high-frequency ventilation are optimal for maintaining effective gas transport when the diaphragma is used as the oscillatory generator.

Animals↗
PubMed1989

[A study of relation between hopelessness and causal attribution in school-aged children].

This study was conducted to investigate the relation between hopelessness and causal attribution in Japanese school-aged children. In Study 1, the Japanese edition of hopelessness scale for children developed by Kazdin, French, Unis, Esveldt-Dawsan, and Sherick (1983) was constructed. Seventeen original items were translated into Japanese and they were administrated to 405 fifth- and sixth-graders. All of the items could be included to the Japanese edition of hopelessness scale. The reliability and validity was examined. In Study 2, the relation between hopelessness and causal attribution in children were investigated. The causal attribution questionnaire developed by Higuchi, Kambare, and Otsuka (1983) and the hopelessness scale developed by Study 1 were administered to 188 sixth-graders. Children with high scores in hopelessness scale significantly attributed negative events to much more effort factor than children with low scores. It supports neither the reformulated learned helplessness model nor the causal attribution theory of achievement motivation. It was explained mainly from points of self-serving attribution, cultural difference, and social desirability. Some questions were discussed for developing studies on depression and causal attribution in Japan.

Achievement↗