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Biomedical subjects

M Doi

Publications and source records attributed to M Doi.

At least 325 records · Page 18Linked to original sources
PubMed1988

Synthesis and solubility properties of peptide fragments of human hemoglobin alpha-chain (123-136).

The solubility prediction method for protected peptides was successfully applied to relatively small peptide fragments of human hemoglobin alpha-chain (123-136) which contained various polar amino acid residues such as Asp(OBzl), Glu(OBzl), Lys(Z), Ser(Bzl), and Thr(Bzl). As reported previously for hydrophobic peptides and human proinsulin C-peptide fragments, solubility data indicated that the insolubility of protected peptides having a mean value of Pc value below 0.90 appeared to begin at the octa- or nonapeptide sequence level and that beta-sheet structure played an important role in the insolubility of peptides. When a peptide has a beta-sheet structure in the solid state, we can clearly determine the critical chain length for peptide insolubility, the solubility dependence on solvent properties, and the solubility independence of amino acid compositions of peptides.

Amino Acid Sequence↗
PubMed1988

Determinations of the DNA sequence of the mreB gene and of the gene products of the mre region that function in formation of the rod shape of Escherichia coli cells.

The 6.5-kilobase mre region at 71 min in the Escherichia coli chromosome map, where genes involved in formation of a rod-shaped cell form a gene cluster, was analyzed by in vivo protein synthesis in a maxicell system and by base sequencing of DNA. An open reading frame that may code for a protein with an Mr of about 37,000 on sodium dodecyl sulfate-polyacrylamide gels was found and was correlated with the mreB gene. N-terminal amino acid sequencing of the hybrid mreB-lacZ protein confirmed the production by mreB of a protein of 347 amino acid residues with a molecular weight of 36,958. The amino acid sequence of this protein deduced from the DNA sequence showed close similarity with that of a protein of the ftsA gene which is involved in cell division of E. coli. Three other contiguous genes that formed three proteins with Mrs of about 40,000, 22,000, and 51,000, respectively, were detected downstream of the mreB gene by in vivo protein synthesis. The mreB protein and some of these three proteins may function together in determination of cell shape.

Amino Acid Sequence↗
PubMed1988

[On the mechanism underlying spasmogenic actions of oxy-hemoglobin on the cerebral artery, analyzed from the inhibitory effects of nicardipine, procaine and indomethacin].

The present study was to analyze the basic mechanism underlying spasmogenic actions of Oxy-hemoglobin (Oxy-Hb) on the bovine cerebral arteries. Using helical strips of the middle cerebral arteries (M2), the changes in muscular tension during an isometric contraction induced by either Oxy-Hb, hydrogen peroxide (H2O2), high potassium-ion-Tyrode (30 mM K+), prostaglandin F2 alpha (PGF2 alpha), or carbocyclic thromboxane A2 (cTXA2) were recorded on the polygraph. Blocking effects of nicardipine, procaine indomethacin were compared on the contractions produced by each reagent described above. The results obtained are summarized as follows. 1) H2O2 dissolved in different concentrations produced arterial contractions similar to those by equimolar Oxy-Hb, showing similar dose-response curves. In contrast, equimolar met-hemoglobin (Met-Hb) always produced much weaker contractions. When the equimolar H2O2 was applied during an Oxy-Hb-induced contraction, the response to H2O2 was completely occluded. When H2O2 was applied during a Met-Hb-induced contraction, the response to H2O2 was not occluded and always additive to the response to Met-Hb. Indomethacin blocked both responses to Oxy-Hb and H2O2, showing similar dose dependence. 2) The above results suggested that Oxy-Hb induced contraction consisted of two components; a strong contraction by active oxygen within Hb molecule, and a weak contraction by Hb molecule itself. The former may be mediated by some PG's which are produced inside the muscle cells as the results of arachidonic acid release and subsequent cyclooxygenase activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Postanesthetic respiratory depression in humans: a comparison of sevoflurane, isoflurane and halothane.

The postanesthetic respiratory depression with sevoflurane, isoflurane and halothane was studied in twenty-one patients. They were divided into three groups of seven patients each. One group underwent sevoflurane anesthesia, another group isoflurane and the third group halothane. Following extubation, the decrease in blood concentration of the anesthetic agent was most rapid with sevoflurane and slowest with halothane. Twenty minutes following extubation, resting ventilation and ventilatory response to carbon dioxide returned to the preanesthetic state with sevoflurane and isoflurane anesthesia. With halothane anesthesia, however, the depressive respiratory effects of halothane remained; depressed ventilatory response to carbon dioxide, decreased tidal volume and increased respiratory frequency. Although halothane has been reported to have the least depressive respiratory effect of the three, its elimination was slowest. Thus the respiratory effects of halothane persisted up to and past the twenty minute mark, far longer than with sevoflurane or isoflurane.

Journal Article↗
PubMed1987

Evolution of an inducible penicillin-target protein in methicillin-resistant Staphylococcus aureus by gene fusion.

A new beta-lactam-inducible penicillin-binding protein (PBP) that has extremely low affinity to penicillin and most other beta-lactam antibiotics has been widely found in highly beta-lactam(methicillin)-resistant Staphylococcus aureus (MRSA). The gene for this protein was sequenced and the nucleotide sequence in its promoter and close upstream area was found to show close similarity with that of staphylococcal penicillinase, while the amino acid sequence over a wide range of the molecule was found to be similar to those of two PBPs of Escherichia coli, the shape-determining protein (PBP 2) and septum-forming one (PBP 3). Probably the MRSA PBP (Mr 76462) evolved by recombination of two genes: an inducible type I penicillinase gene and a PBP gene of a bacterium, causing the formation of a beta-lactam-inducible MRSA PBP.

Anti-Bacterial Agents↗
PubMed1987

The three-dimensional similarity between a dimeric antiparallel extended structure and a beta-turn folded form of enkephalin.

The three-dimensional similarity between two fundamental conformations, a dimeric antiparallel extended structure and a type I' beta-turn folded form, of enkephalin was examined by computer graphic and empirical energy calculation methods. By the rotation of Tyr and Phe side chains, one half of the former structure could mimic the three-dimensional form of the latter without a large loss of conformational energy. This result provides a new idea for considering the conformation of enkephalin suitable for the multiple opioid receptors. The active conformation of enkephalin for mu- and delta-opioid receptors is discussed in the light of the present study.

Enkephalins↗
PubMed1987

Crystal structures of [Met5] and [(4-bromo)Phe4,Met5]enkephalins: formation of a dimeric antiparallel beta-structure.

The crystal structure of [(4-bromo)Phe4,Met5]enkephalin (Tyr-Gly-Gly-(4-bromo)-Phe-Met) shows two independent molecular conformations. The molecules are arranged in parallel in a head-to-tail fashion and form an antiparallel beta-sheet structure involving intermolecular hydrogen bonds. This dimeric beta-structure is also observed in the [Met5]enkephalin crystal, in spite of their different crystal packing environments, which shows the energetic stability of this molecular conformation. The three-dimensional similarity between the dimeric beta-structure and the beta-turn form is discussed in the relation to the opioid delta and mu receptors.

Crystallography↗
PubMed1987

Purification and Characterization of Two Benzoyl-l-Tyrosine p-Nitroanilide Hydrolases from Etiolated Leaves of Zea mays L.

Two benzoyl-l-tyrosine p-nitroanilide hydrolases (BTPAases I and II) were purified from the etiolated leaves of Zea mays L. and characterized. BTPAase I was electrophoretically homogeneous and consisted of two identical subunits having a molecular weight of 53,000. The molecular weight of BTPAase II was 65,000. The Michaelis constants for substrate, BTPA, were 4 millimolar and 1.3 millimolar for BTPAases I and II, respectively. Based on the action of various inhibitors on both enzyme activities, these enzymes were classified as serine proteases. BTPAase I showed caseinolytic activity at neutral pH and the activity was strongly inhibited by the serine protease inhibitors.

Journal Article↗
PubMed1987

Ventriculo-coronary micro-communications in pulmonary atresia and sequential changes of coronary arteries.

In the present paper, numerous micro-communications between myocardial sinusoids and small branches of coronary arteries are studied which existed in a rudimentary right ventricle of a female neonate with pulmonary atresia and an intact ventricular septum, who was born on the 40th week of gestation. Cardioangiography revealed a large fistulous subepicardial communication. At autopsy, myocardium of the right ventricle appeared spongy with extensive sinusoid slits. In addition to the large communication which was connecting a deeply extending sinusoid of the right ventricle to the main trunk of the anterior descending artery, numerous micro-communications were found between myocardial sinusoids in the rudimentary right ventricle and intramural small branches of the coronary artery. Furthermore, morphometrical analysis demonstrated that the medias of the intramural arteries in both ventricles of the present case were significantly hypertrophic, as compared with those in the control cases without communications (p less than 0.05). These facts indicate the significance of hemodynamic factors on the persistence of embryonic sinusoid-coronary communication.

Angiocardiography↗
PubMed1987

Production of low-affinity penicillin-binding protein by low- and high-resistance groups of methicillin-resistant Staphylococcus aureus.

Methicillin- and cephem-resistant Staphylococcus aureus (137 strains) for which the cefazolin MICs are at least 25 micrograms/ml could be classified into low-resistance (83% of strains) and high-resistance (the remaining 17%) groups by the MIC of flomoxef (6315-S), a 1-oxacephalosporin. The MICs were less than 6.3 micrograms/ml and more than 12.5 micrograms/ml in the low- and high-resistance groups, respectively. All strains produced penicillin-binding protein 2' (PBP 2'), which has been associated with methicillin resistance and which has very low affinity for beta-lactam antibiotics. Production of PBP 2' was regulated differently in low- and high-resistance strains. With penicillinase-producing strains of the low-resistance group, cefazolin, cefamandole, and cefmetazole induced PBP 2' production about 5-fold, while flomoxef induced production 2.4-fold or less. In contrast, penicillinase-negative variants of low-resistance strains produced PBP 2' constitutively in large amounts and induction did not occur. With high-resistance strains, flomoxef induced PBP 2' to an extent similar to that of cefazolin in both penicillinase-producing and -negative strains, except for one strain in which the induction did not occur. The amount of PBP 2' induced by beta-lactam antibiotics in penicillinase-producing strains of the low-resistance group correlated well with resistance to each antibiotic. Large amounts of PBP 2' in penicillinase-negative variants of the low-resistance group did not raise the MICs of beta-lactam compounds, although these strains were more resistant when challenged with flomoxef for 2 h. Different regulation of PBP 2' production was demonstrated in the high- and low-resistance groups, and factor(s) other than PBP 2' were suggested to be involved in the methicillin resistance of high-resistance strains.

Anti-Bacterial Agents↗
PubMed1987

Increased susceptibility to cephamycin-type antibiotics of methicillin-resistant Staphylococcus aureus defective in penicillin-binding protein 2.

A methicillin-resistant strain of Staphylococcus aureus which produced low-affinity penicillin-binding protein 2' (PBP 2') spontaneously lost PBP 2 when the strain was cultivated at 43 degrees C overnight. At 37 degrees C, the mutant had increased susceptibility to cephamycin-type beta-lactams, which showed high affinity for PBP 4. This result suggests that inhibition of PBP 4, in addition to that of PBP 2, is necessary to kill methicillin-resistant strains.

Anti-Bacterial Agents↗
PubMed1987

Mutant isolation and molecular cloning of mre genes, which determine cell shape, sensitivity to mecillinam, and amount of penicillin-binding proteins in Escherichia coli.

A chromosomal region of Escherichia coli contiguous to the fabE gene at 71 min on the chromosomal map contains multiple genes that are responsible for determination of the rod shape and sensitivity to the amidinopenicillin mecillinam. The so-called mre region was cloned and analyzed by complementation of two closely related but distinct E. coli mutants characterized, respectively, by the mutations mre-129 and mre-678, that showed a rounded to irregular cell shape and altered sensitivities to mecillinam; the mre-129 mutant was supersensitive to mecillinam at 30 degrees C, but the mre-678 mutant was resistant. The mre-678 mutation also caused simultaneous overproduction of penicillin-binding proteins 1Bs and 3. A chromosomal region of the wild-type DNA containing the total mre region and the fabE gene was first cloned on a lambda phage; a 7-kilobase (kb) fragment containing the whole mre region, but not the fabE gene, was then recloned on a mini F plasmid, pLG339; and finally, a 2.8-kb fragment complementing only mre-129 was also cloned on this low-copy-number plasmid. The whole 7-kb fragment was required for complementing the mre-678 mutant phenotypes. Fragments containing fabE but not the mre-129 region could be cloned on a high-copy-number plasmid. Southern blot hybridization indicated that the mre-678 mutant had a large deletion of 5.25 kb in its DNA, covering at least part of the mre-129 gene.

Amdinocillin↗
PubMed1987

Genes encoding two lipoproteins in the leuS-dacA region of the Escherichia coli chromosome.

The coding of two rare lipoproteins by two genes, rlpA and rlpB, located in the leuS-dacA region (15 min) on the Escherichia coli chromosome was demonstrated by expression of subcloned genes in a maxicell system. The formation of these two proteins was inhibited by globomycin, which is an inhibitor of the signal peptidase for the known lipoproteins of E. coli. In each case, this inhibition was accompanied by formation of a new protein, which showed a slightly lower mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and which we suppose to be a prolipoprotein with an N-terminal signal peptide sequence similar to those of the bacterial major lipoproteins and lysis proteins of some bacteriocins. The incorporation of 3H-labeled palmitate and glycerol into the two lipoproteins was also observed. Sequencing of DNA showed that the two lipoprotein genes contained sequences that could code for signal peptide sequences of 17 amino acids (rlpA lipoprotein) and 18 amino acids (rlpB lipoprotein). The deduced sequences of the mature peptides consisted of 345 amino acids (Mr 35,614, rlpA lipoprotein) and 175 amino acids (Mr 19,445, rlpB lipoprotein), with an N-terminal cysteine to which thioglyceride and N-fatty acyl residues may be attached. These two lipoproteins may be important in duplication of the cells.

Amino Acid Sequence↗
PubMed1987

Clonal lifespan of Paramecium tetraurelia: effect of selection on its extension and use of fissions for its determination.

Paramecia cells, like human diploid cells cultured in vitro, provide a useful model system for understanding the mechanism that limits division potential. The reported maxima of the clonal lifespan of Paramecium tetraurelia fall into two ranges: from 220 to 258 fissions and from 310 to 325 fissions. We found that neither the selection of vigorous lines nor the cryptic occurrence of autogamy offers a plausible explanation for the much longer lifespans in the latter range. We found the sporadic occurrence of very long clonal lifespans, such as 330 fissions, without selection and autogamy. Selection, which was evaluated by using different methods to maintain lines, had little effect on the extension of the maximal clonal lifespan, whereas it did have a marked effect on the extension of the mean clonal lifespan. Autogamy, which was checked with two closely linked marker genes, was frequent, but only during the period when lines were terminating. Statistical analysis on the mean clonal lifespans of two groups of subclones cultured at 25 and 20 degrees C or with rich and poor nutrition showed that the clonal lifespan that was fission-related under favourable conditions tended to dissociate from fissions under less favourable conditions. We discuss mechanisms that determine the clonal lifespan, programmed events contributing to the maximum clonal lifespan and random events contributing to the mean clonal lifespan.

Animals↗
PubMed1987

Recent morbidity trends in myocardial infarction in Japan: investigation of death certificates and the survival rates at coronary care units.

To elucidate recent trends in the mortality and morbidity of myocardial infarction (MI), we investigated death certificates and changes in the survival rate of MI patients at coronary care units (CCUs), which may affect the death rates. For all cases of MI, acute heart failure (AHF), heart failure (HF) as underlying cause, and hypertension as underlying cause with HF or AHF (categorized as hypertensive heart disease) on death certificates in two rural and two urban populations between 1981 and 1984, medical records were reviewed and case histories obtained from interviews with patients' families to validate the diagnosis. The number of MI deaths on the death certificates was not underestimated because some MI deaths were misdiagnosed as AHF, HF and hypertensive heart disease and some MI death certificates were misdiagnosed. Survival of MI patients at CCUs improved in several major cities, Tokyo, Osaka, Wakayama and Asahikawa between 1978 and 1984; a total of 4318 MI deaths were estimated to be averted by CCUs in 1984 compared with the number of deaths in 1978. Therefore, improvement of MI cases at CCUs may be one of the factors attenuating the rise in death rates in all of Japan.

Coronary Care Units↗