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K Ubukata

Publications and source records attributed to K Ubukata.

At least 19 recordsLinked to original sources
PubMed2001

Macrophage-oriented cytotoxic activity of novel triterpene saponins extracted from roots of Securidaca inappendiculata.

It is recognized that macrophages in peripheral tissues often proliferate under pathological conditions such as tumors, inflammation and atherosclerosis. Because the growth state of macrophages is believed to be a factor regulating the pathological process of the diseases, substances that regulate macrophage growth or survival may be useful for disease control. In this paper, we identified the activity inhibiting macrophage growth in a hot water extract of roots of Securidaca inappendiculata. The extract markedly inhibited macrophage colony-stimulating factor (M-CSF/CSF-1)-induced growth of macrophages, whereas it exerted a less potent effect on growth of Concanavalin A (Con A)-stimulated thymocytes or M-CSF-stimulated bone marrow cells. The inhibition of macrophage growth was caused by a cytotoxic effect rather than a cytostatic effect. Cell death was due to the induction of apoptosis, as judged by staining with terminal deoxynucleotidyl transferase-mediated d-UTP nick end labelling (TUNEL). The cytotoxic activity seemed to be specific to peripheral macrophages; it showed a weak effect on the growth and survival of tumor cell lines including a macrophage-like cell line, J-774.1. Moreover, the saponin fraction induced apoptotic cell death of macrophages only when they were stimulated by M-CSF; it did not affect the viability of macrophages cultured without M-CSF or with granulocyte/macrophage-CSF. We determined the structures of the two active triterpene saponin compounds in the fraction, named securioside A and securioside B having a 3,4-dimethoxycinnamic group which is essential for the cell death-inducing activity. They are believed to be the primary compounds of new drugs for the treatment of pathological states in which macrophage proliferation occurs.

Animals↗
PubMed2001

Evaluation of PCR primers to screen for Streptococcus pneumoniae isolates and beta-lactam resistance, and to detect common macrolide resistance determinants.

Pneumococcal isolates (n = 148) from various countries (mostly from the USA) were tested by a primer set for PCR. Thirty-eight (86.4%) of the 44 penicillin G-susceptible isolates (MIC < or = 0.06 mg/L) had unaltered pbps, while six isolates (13.6%) had either one or two alterations in pbps. Of 47 penicillin G-resistant strains (MIC > or = 2 mg/L), 41 isolates (87.2%) had all three pbps altered, six isolates (12.8%) had altered pbp1a + 2x. Various combinations of altered pbp were seen in penicillin G-intermediate isolates. Prevalence of macrolide resistance genes mef(A) and erm(B) in isolates was clearly reflected by their MICs. All isolates were positive for lytA. The primers were useful for screening for Streptococcus pneumoniae and beta-lactam resistance, and for detection of common macrolide resistance determinants.

Anti-Bacterial Agents↗
PubMed2001

[The trend of childhood bacterial meningitis in Japan (1997.7-2000.6)].

We surveyed the epidemiology of purulent meningitis in pediatrics for 3 years between July 1997 and June 2000 in Japan and obtained the following results. The number of cases of purulent meningitis was 428, which was equivalent of 1.1-1.7 children out of 1,000 hospitalized those in pediatrics per year. The age-distribution for the infections was the highest under 1 year of age and it decreased as the age increased. Under 1 year of age, the highest distribution was observed in one month of age and under 1 month of age, the highest distribution was observed in 7 days of or younger ages. Haemophilus influenzae was the most common pathogen causing the infections, followed by Streptococcus pneumoniae, group B streptococcus, and Escherichia coli. Relationship between causing pathogens and age-distribution was as follows: group B streptococcus and E. coli were major pathogens under 4 months of age and H. influenzae and S. pneumoniae were major pathogens over 3 months of age. Susceptibility tests performed at each facility demonstrated that 25.3% of H. influenzae isolates and 38.7% of S. pneumoniae isolates were drug-resistant. Analysis of resistant genes for H. influenzae and S. pneumoniae isolates, which were stored and sent, demonstrated higher rates of resistance than those observed in susceptibility tests. These results suggest that the increase in insufficient efficacy of usual treatment with combination of ampicillin and cefotaxime is predictable against the infections. Therefore, the treatment for the infections should be reconsidered.

Female↗
PubMed2001

Association of amino acid substitutions in penicillin-binding protein 3 with beta-lactam resistance in beta-lactamase-negative ampicillin-resistant Haemophilus influenzae.

The affinity of [(3)H]benzylpenicillin for penicillin-binding protein (PBP) 3A was reduced in 25 clinical isolates of beta-lactamase-negative ampicillin (AMP)-resistant (BLNAR) Haemophilus influenzae for which the AMP MIC was > or =1.0 microg/ml. The affinities of PBP 3B and PBP 4 were also reduced in some strains. The sequences of the ftsI gene encoding the transpeptidase domain of PBP 3A and/or PBP 3B and of the dacB gene encoding PBP 4 were determined for these strains and compared to those of AMP-susceptible Rd strains. The BLNAR strains were classified into three groups on the basis of deduced amino acid substitutions in the ftsI gene, which is thought to be involved in septal peptidoglycan synthesis. His-517, near the conserved Lys-Thr-Gly (KTG) motif, was substituted for Arg-517 in group I strains (n = 9), and Lys-526 was substituted for Asn-526 in group II strains (n = 12). In group III strains (n = 4), three residues (Met-377, Ser-385, and Leu-389), positioned near the conserved Ser-Ser-Asn (SSN) motif, were replaced with Ile, Thr, and Phe, respectively, in addition to the replacement with Lys-526. The MICs of cephem antibiotics with relatively high affinities for PBP 3A and PBP 3B were higher than those of AMP and meropenem for group III strains. The MICs of beta-lactams for H. influenzae transformants into which the ftsI gene from BLNAR strains was introduced were as high as those for the donors, and PBP 3A and PBP 3B showed decreased affinities for beta-lactams. There was no clear relationship between 7-bp deletions in the dacB gene and AMP susceptibility. Even though mutations in another gene(s) may be involved in beta-lactam resistance, these data indicate that mutations in the ftsI gene are the most important for development of resistance to beta-lactams in BLNAR strains.

Ampicillin↗
PubMed2001

[Beta-lactam and macrolide resistance in Streptococcus pneumoniae].

The resistance of beta-lactam antibiotics in penicillin-resistant Streptococcus pneumoniae (PRSP) is due to alterations in penicillin-binding proteins(PBPs). Recently, highly beta-lactam-resistant strains(MIC: > or = 4 micrograms/ml for penicillin, > or = 8 micrograms/ml for ampicillin, and > or = 4 micrograms/ml for cefotaxime) have been isolated. High resistance of these strains is caused by further alterations in pbp2x and pbp2b genes adjacent to conserved amino acid motifs, in addition to that detected in common PRSP. The resistant mechanisms of macrolides in S. pneumoniae is recognized as production of a 23s rRNA methylase encoded by ermB and efflux system mediated by mefA gene. We detected these genes by PCR in clinical isolates, and showed the relationship between the presence of each gene and the susceptibilities of 14-, 15-, 16-membered macrolides.

Anti-Bacterial Agents↗
PubMed2001

[Beta-lactamase negative ampicillin-resistant Haemophilus influenzae(BLNAR)].

The affinity of [3H]-benzylpenicillin for penicillin-binding protein(PBP) 3A/3B was reduced in clinical isolates beta-lactamase-negative ampicillin(ABPC)-resistant Haemophilus influenzae(BLNAR) with MIC of > or = 1 microgram/ml to ABPC. The sequence of ftsI gene encoding the transpeptidase domain of PBP3A/3B were determined for these strains, and compared to those of ABPC-susceptible Rd strain. Common substitutions of deduced amino acid residues were identified in transpeptidase region on the ftsI gene in BLNAR strains. Homology modeling of the three-dimensional structure of PBP3 showed that every common substitution occurred at active site pocket surrounded by three conserved motifs. The MICs of beta-lactams for H. influenzae transformants in which ftsI gene from BLNAR was introduced, were as high as those for the donors and PBP3A/3B showed a decreased affinity for beta-lactams. These data indicate that mutations in the ftsI gene are the most important for development of resistance to beta-lactams in BLNAR.

Ampicillin Resistance↗
PubMed2000

[Identification of bacterial strain at each episode of recurrent acute otitis media].

This study was undertaken to investigate whether each episode of recurrent acute otitis media (rAOM) is caused by the same strain of bacteria or different strains at each episode. Seventy infants less than 3-years of age, having experienced rAOM for a period shorter than 8 weeks, were selected and included in the present study. The total number of AOM episodes experienced by this group was 282. At each subsequent episode of AOM, otorrhea and nasopharyngeal swabs were taken for bacterial culture and determination of the MIC for antibiotics. When S. pneumoniae was identified, its serotype, and its pbp, ermAM, and mefE genes were also investigated to determine the bacterial species and strains. S. pneumoniae was the most frequently cultured bacteria with 26 penicillin-sensitive S. pneumoniae (PSSP), 65 penicillin-insensitive S. pneumoniae (PISP), and 50 penicillin-resistant S. pneumoniae (PRSP). H. influenzae was the next most frequently cultured bacteria of which 65 were sensitive to penicillin, 27 were found to be beta-bactamase-negative-ampicillin-resistant (BLNAR) and 17 were found to be beta-bactamase positive. Bacteria cultured from each pair of two successive episodes of AOM were compared as to the identity of the bacteria during the two episodes. In 150 out of 202 pairs (74%), the cultured pathogen was different. In 22 cases in which either PISP or PRSP was the pathogen detected in two consecutive AOM episodes, 15 cases (68%) were found in which the involved strain differed between the two episodes. This study indicates that the pathogen involved in rAOM is likely to differ at each episode of AOM, not only in cases caused by PSSP, but also in those caused by PRSP.

Acute Disease↗
PubMed2000

[Drug-resistant bacteria of current topics and their resistance mechanisms--PRSP and BLNAR].

The prevalence of resistant isolates for beta-lactam antibiotics have been rapidly increasing in Streptococcus pneumoniae and Haemophilus influenzae. These strains having resistant elements are called penicillin-resistant S. pneumoniae(PRSP) and beta-lactamase-negative ampicillin-resistant H. influenzae(BLNAR). The mechanism of resistance was identified as the reduction of penicillin-binding proteins(PBPs) affinities as the target of beta-lactams. In PRSP, pbp1a, pbp2x, and pbp2b encoding PBP1A, -2X, and -2B enzymes, respectively, were altered. In contrast, mutations in the ftsI gene encoding PBP3A were only clarified in BLNAR. Characteristics of the resistance caused by PBPs alterations are a low-level resistance that decrease bactericidal action.

Ampicillin Resistance↗
PubMed1999

Prothiofos metabolites in human poisoning.

CASE REPORT: A 63-year-old woman was admitted to a local hospital after the ingestion of 40% prothiofos preparation (Tokuthion) 370 mL. Gastric lavage was performed and cathartics, active charcoal, diuretics, atropine sulfate, and pralidoxime were administered. Serum cholinesterase activity was 1.3 IU/L (normal 200-460 IU/L). The patient's consciousness was gradually restored after 4 hours of charcoal hemoperfusion and she was discharged 5 days after admission with no sequelae. METHOD: Plasma and urine prothiofos and metabolites were detected by gas chromatography-flame photometry and gas chromatography-mass spectrometry. Two despropyl metabolites were synthesized for identification and estimation. RESULTS: The main metabolites were identified with authentic prothiofos and methyl esters of synthesized des-S-propyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phosphate), despropyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phospholothiolate), and des-S-propyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorothioate). Despropyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorodithioate) was also identified in plasma. Large amounts of the hydrolyzed product, 2,4-dichlorophenol and its conjugate were also found. The metabolic pattern of prothiofos in humans appears to be different from that in rats.

Charcoal↗
PubMed1999

Diversity of substitutions within or adjacent to conserved amino acid motifs of penicillin-binding protein 2X in cephalosporin-resistant Streptococcus pneumoniae isolates.

The sequence of an approximately 1.1-kb DNA fragment of the pbp2x gene, which encodes the transpeptidase domain, was determined for 35 clinical isolates of Streptococcus pneumoniae for which the cefotaxime (CTX) MICs varied. Strains with substitutions within a conserved amino acid motif changing STMK to SAFK and a Leu-to-Val change just before the KSG motif were highly resistant to CTX (MIC, >==2 microgram/ml). Strains with substitutions adjacent to SSN or KSG motifs had low-level resistance. The amino acid substitutions were plotted on the three-dimensional crystallographic structure of the transpeptidase domain of PBP2X. Transformants containing pbp2x from strains with high-level CTX resistance increased the CTX MIC from 0. 016 microgram/ml to 0.5 to 1.0 microgram/ml.

Amino Acid Sequence↗
PubMed1999

[Susceptibilities of Enterococcus faecium, PRSP and MRSA to RP59500 and their correlations with those to other drugs].

Investigations on emergence of vancomycin-resistant Enterococcus faecium (VREF) which has recently been attracting attention, especially in the Western countries, have been conducted in Japan. A total of 1,239 isolates of E. faecium were collected from 19 institutions during the period of April 1995 and June 1996, in the purpose of evaluating susceptibilities to variety of antimicrobial agents, including RP59500 and vancomycin (VCM), and detecting vancomycin-resistant genes (van genes). Susceptibilities of penicillin-resistant Streptococcus pneumoniae (PRSP) and methicillin-resistant Staphylococcus aureus (MRSA) were also studied. As a result, 2 isolates of E. faecium were found to be moderately resistant to VCM showing MIC of 8 micrograms/ml though the final identification in species level and the detection of van genes by PCR method have not been completed. On the other hand there detected no MRSA nor PRSP showing moderately resistant or resistant to VCM. It was concluded that RP59500 and VCM possessed favorable activity against clinically isolated E. faecium, PRSP and MRSA. Among other species of enterococci, moderately resistant strains to VCM showing MIC of 8 micrograms/ml were detected; 10 isolates of E. gallinarum, 4 of E. casseliflavus and 2 of E. flavescens. In those isolates, vanC1 and vanC2 were detected by PCR, and vanB was also detected in a isolates of E. gallinarum simultaneously.

Anti-Bacterial Agents↗
PubMed1998

Association of a thr-371 substitution in a conserved amino acid motif of penicillin-binding protein 1A with penicillin resistance of Streptococcus pneumoniae.

We determined the nucleotide sequence between 1,903 and 3,097 bp of pbp1a, which encodes the transpeptidase domain of PBP 1A, from clinical isolates of penicillin-resistant Streptococcus pneumoniae (PRSP) serotypes 19 (n = 8), 6 (n = 9), 23 (n = 6), and 14 (n = 2) and two penicillin-susceptible S. pneumoniae (PSSP) isolates. These serotyped PRSP strains were isolated predominantly in Japan from 1993 through 1997. The 25 resistant strains were classified into five groups on the basis of the extent of sequence differences. Strains in groups I (n = 5; serotype 6), II (n = 3; serotype 19), and III (n = 12; different serotypes) had sequences highly homologous to the sequence of pbp1a of PRSP strains from South Africa, Spain, and the United States. The group IV strain (n = 1; serotype 14) had unique deletions from or insertions in the sequences. The sequences of group V strains (n = 4; serotypes 6 and 23) had relatively few differences from the sequences of the PSSP strains. For strains (n = 18) for which the threonine at codon 371 (Thr-371) in a conserved STMK motif of PBP 1A was substituted with an alanine or a serine (in addition to having altered pbp2x and pbp2b genes), penicillin MICs were >/= 1.0 microgram/ml. The PBPs 1A of these strains showed decreased affinities for [3H]benzylpenicillin and slightly faster mobilities on sodium dodecyl sulfate-polyacrylamide gels. In contrast, for strains (n = 4) without a substitution at Thr-371 in PBP 1A but with mutations in both pbp2x and pbp2b, penicillin MICs were 0.125 to 0.25 microgram/ml, and the affinities of their PBPs 1A were similar to that of PSSP PBPs 1A. Furthermore, for the Thr-371-substituted strains (n = 3) with altered pbp2x genes but native pbp2b genes, penicillin MICs were 0.125 to 0.25 microgram/ml. These results suggest that amino acid substitution of Thr-371 contributes to the development of penicillin resistance in PRSP strains with altered pbp2x and pbp2b genes.

Amino Acid Sequence↗
PubMed1998

[Identification of penicillin-resistant Streptococcus pneumoniae in nasopharynx of patient with acute otitis media by PCR].

Streptococcus Pneumoniae is a leading cause of acute otitis media (AOM). For most AOM caused by S. pneumoniae, penicillin is the antibiotic of choice. However, there are some recent reports of clinical resistance to penicillin by S. pneumoniae. The sequences of penicillin binding protein, pbpla, pbp2b and pbp2x, genes of penicillin-resistant S. pneumoniae (PRSP) were more highly divergent than those of penicillin-succeptible S. pneumoniae (PSSP). The polymerase chain reaction (PCR) can easily determine whether an S. pheumoniae isolate is susceptible or resistant to penicillin by amplifying the target gene by using a combination of primers. In this study, clinical isolates (n = 12) were obtained from the nasopharynx of patients with AOM. PCR was used to confirm the identification of an isolate as S. pneumoniae by amplifying the autolysin gene and to detect three PBP genes by amplifying parts of pbp1a, pbp2x and pbp2b. The resistance of S. pneumoniae to penicillin and other beta-lactams has been shown to be associated with mosaic mutations in the pbp1a, pbp2b and pbp2x genes. These findings suggest that rapid identification of PSSP and PISP/PRSP by PCR is possible and very useful for proper treatment of acute otitis media.

Acute Disease↗