Biomedical subjects
Publications and source records attributed to I Kawamoto.
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Novel 1beta-methyl carbapenems with a cycloalkylamine moiety as a side chain were synthesized and their structure-activity relationships were studied. These carbapenems showed potent antibacterial activities against a wide range of Gram-positive and Gram-negative bacteria, and moderate urinary recovery when administered intraperitoneally in mice.
Synthesis of new tricyclic carbapenems (trinems) with a pyrrolidinyl moiety at the C-4 position of the tricyclic ring and their antimicrobial activities were studied. These trinems showed potent activities against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Among them, (4R)-[(S)-pyrrolidin-3-ylthiomethyl]trinem (14a) exhibited good activity against MRSA in vitro and in vivo.
The synthesis and biological properties of 1beta-methylcarbapenems with 1-methyl-5-oxopyrrolidin-3-ylthio group at the C-2 position were studied. The sodium (1R,5S,6S)-6-[(R)-1-hydroxyethyl]-1-methyl-2-[(R)-1-methyl-5-oxopyrro lidin-3-ylthio]-1-carbapen-2-em-3-carboxylate and its (S)-isomer at the 2-position show potent and well-balanced antibacterial activity. The pharmacokinetic parameters of the pivaloyloxymethyl esters of these two carbapenems were compared in mice. The in vivo potency of these carbapenems was compared with that of cefdinir. Good in vivo efficacy of these ester prodrugs reflected the high and prolonged blood levels in parent drugs achieved after oral administration to mice.
The synthesis and antibacterial activity of 1beta-methylcarbapenems with quaternary ammonium groups at the C-2 position have been studied. Two types of new carbapenem derivatives have been synthesized. These 1beta-methylcarbapenems, one type having a (2S,4S)-2-[1,1-dimethyl-2-(1-piperazinyl)carbonyl]pyrrolidinio-4-+ ++ylthio group and the other type having a (2S,4S)-2-(4-carbamoylmethyl-4-methylhomopiperazinio-1-yl carbonyl)pyrrolidin-4-ylthio group, show potent and well balanced antibacterial activity as well as high stability against dehydropeptidase-I. The in vivo potency of these two carbapenems was compared with that of meropenem. The structure-activity relationships leading to these carbapenems are also described.
We have studied an ester prodrug of a carbapenem to develop a potent orally active beta-lactam antibiotic. A variety of 1 beta-methylcarbapenem derivatives have been synthesized. We have found that some derivatives having an amide group in the C-2 side chain show potent and well balanced antibacterial activities as well as high stability against dehydropeptidase-I. Oral absorption of derivatives has been optimized by modifying the C-3 ester promoiety. Pivaloyloxymethyl (1R, 5S, 6S)-6-[(R)-1-hydroxyethyl]-l-methyl-2-[(R)-5-oxopyrrolidin-3-yl thio]- l-carbapen-2-em-3-carboxylate, CS-834, has been selected as the most promising compound for further evaluation.
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Interviews with 57 college students were conducted. In order to investigate how they experienced "confidence" or "pride" in everyday life. The framework of the study was "locus of reality", which was the degree that reality was felt inside self as opposed to in others. Results showed that the subjects tended to become conscious of themselves when they were to share information about situations with others. Also, locus of reality had a relative tendency to oscillate between self and others. Moreover, differences were found for mental experiences ascribed for themselves and others, even when the same words were used for both. The experiences of "confidence" and "no-confidence" were characteristically asymmetrical in the feeling of reality. "Pride" was different from "confidence", in that the former was associated more with experiences that had defensive connotations. These results suggested that people might have a tendency not to differentiate interpretation processes of their own from others.
Developmental change in the potentiation of N-methyl-D-aspartate (NMDA) responses by spermine was investigated on the ventromedial hypothalamic neurones acutely dissociated from the rats aged between 5 and 21 days, using a nystatin perforated patch clamp recording in a whole cell mode. Spermine potentiated the NMDA response in a concentration dependent manner between 10(-5) M and 10(-5) M at all ages examined. This potentiation decreased significantly with age. On the other hand, spermine did not affect the kainate and AMPA responses at any age. This developmental change of the modulation of NMDA responses might influence to or be influenced by the behavioural and neuronal changes related to the VMH in the early postnatal life.
Ribosomal proteins from 22 strains of 15 different species belong to the genus Arthrobacter were analyzed by an improved two-dimensional gel electrophoresis. Electrophoretograms of ribosomal proteins from 15 type strains had species-specific patterns. Similarity coefficients (SAB values) of ribosomal proteins with mol. wt. of greater than about 20,000, among strains of the same species (DNA relatedness values of more than 61%) were greater than 0.85, but the SAB values among strains of different species were less than 0.60. The N-terminal amino acid sequences of the AL2 proteins, which migrated into similar positions in this method, from 5 type strains were shown to be highly homologous. Our results indicated that ribosomal proteins have been conserved within species during evolution and that the members of the genus Arthrobacter are phylogenetically homogeneous. Thus, ribosomal protein profiles by this method are a potential tool for strain identification.
A novel compound MS-444 was isolated from the culture broth of a bacterial strain KY7123. The strain was identified as Micromonospora sp. from its morphological and cultural characteristics. The compound inhibited the activity of purified smooth muscle myosin light chain kinase with an IC50 value of 10 microM. The production, isolation, physico-chemical properties and biological activities of MS-444 were described in this paper.
The developmental change of Mg2+ block of NMDA-induced response (INMDA) was investigated in the freshly dissociated nucleus tractus solitarii (NTS) neurons of the rats by the use of a nystatin-perforated patch-recording configuration. Mg2+ block was less obvious in a number of fetal NTS neurons than in the neurons of > 9 days after birth (P9) and became rapidly apparent by P3. Protein kinase C (PKC) modulators, such as staurosporine, H-7 and phorbol ester, did not clearly affect the generation of the voltage dependency of INMDA in immature rats. In addition, the facilitatory effect of glycine on the INMDA did not change in development. These evidences suggest that an appearance of the voltage dependency of INMDA in NTS neurons might be due to a developmental change in combinations of subunits composing the NMDA receptor and/or in the intracellular modulators of the INMDA other than PKC.
AS-186a, b, c, d, and g were isolated from the cultured broth of Penicillium asperosporum KY1635 as inhibitors of acyl-CoA: cholesterol acyltransferase (ACAT). IC50 values for the effect of AS-186a, b, c, d, and g against ACAT activity of the microsomes from cholesterol-fed rabbit liver were calculated to be 22.9, 8.2, 11.5, 12.4, and 13.9 microM, respectively. Although AS-186a, and b were identical to penicillide and purpactin A, respectively, AS-186c, d, and g were found to be new compounds.
RES-701-1, a novel cyclic peptide endothelin antagonist, was isolated from the culture broth of Streptomyces sp. RE-701. RES-701-1 selectively inhibited the ET-1 binding to type B endothelin receptor (ETB receptor) with an IC50 of 10 nM expressed in CHO cells and blocked the ET-1-induced elevation of intracellular free Ca2+ concentration in ETB receptor-expressing COS-7 cells. Characterization of producing strain, fermentation, isolation, structure, physico-chemical and biological properties of RES-701-1 are described.
MS-282a and MS-282b were isolated from the culture broth of Streptomyces tauricus ATCC 27470 as inhibitors of smooth muscle myosin light chain kinase (MLCK). MS-282a and MS-282b inhibited the activity of chicken gizzard MLCK with IC50 values of 3.8 microM and 5.2 microM, respectively. Cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase and protein kinase C were not inhibited by 150 microM MS-282a at all. It is likely that MS-282a blocks MLCK activity by antagonizing calmodulin since 1) the compound inhibited calmodulin-dependent but not calmodulin-independent activity of MLCK; 2) the inhibition of MLCK was antagonized by increasing concentrations of calmodulin, and 3) the compound inhibited calmodulin-dependent cyclic nucleotide phosphodiesterase.
A novel compound, AS-183, which inhibits acyl-CoA: cholesterol acyltransferase (ACAT), was isolated from the culture broth of a fungus, Scedosporium sp. SPC-15549. AS-183 inhibited ACAT activity in an enzyme assay system using rabbit liver microsomes with an IC50 value of 0.94 microM. AS-183 also inhibited cholesterol ester formation in HepG2, CaCo2, and THP-1 cells with IC50 values of 18.1, 25.5, and 34.5 microM, respectively.
MS-347a was isolated from the culture broths of Aspergillus sp. KY52178 as an inhibitor of smooth muscle myosin light chain kinase (MLCK). MS-347a inhibited the activity of chicken gizzard MLCK with an IC50 value of 9.2 microM. The inhibition was dependent on time of preincubation of MS-347a with the enzyme, suggesting irreversible inhibition. It is likely that the inhibitor binds to the catalytic domain of MLCK, since the compound inhibited not only calmodulin-dependent but also calmodulin-independent activity of MLCK. Calmodulin-dependent cyclic nucleotide phosphodiesterase, cAMP-dependent protein kinase and cGMP-dependent protein kinase were not inhibited by 150 microM MS-347a at all, although the compound inhibited protein kinase C with an IC50 value of 16 microM. MS-347b, a minor component was also isolated from the same culture broths. This minor component at 150 microM did not inhibit the activity of MLCK.
Verticillium sp. SPC-15898 was found to produce novel metabolites, designated ES-242-2-(-)8, which were structurally related to ES-242-1. These compounds were isolated from the culture broth and the physico-chemical and biochemical properties were examined. ES-242-2-(-)8 inhibited [3H]thienyl cyclohexypiperidine ([3H]TCP) binding to rat crude synaptic membranes (CSM) with IC50 values of 0.116, 2.9, ca. 2.9, 25.3, 1.0, 59, 24, and 13 microM, respectively. None of these compounds showed inhibitory effects against the binding of [3H]kainate to its receptor, which is another subtype of the excitatory amino acid receptor.