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Biomedical subjects

K Furihata

Publications and source records attributed to K Furihata.

At least 19 recordsLinked to original sources
PubMed2001

Glycosylative inactivation of chalcomycin and tylosin by a clinically isolated Nocardia asteroides strain.

Studies on the susceptibility of pathogenic Nocardia to macrolide antibiotics, chalcomycin and tylosin, showed that most of the Nocardia species examined were highly resistant to both antibiotics, although N. nova was moderately susceptible. N. asteroides IFM 0339 converted these macrolides into inactive metabolites by glycosylation at 2'-OH or glycosylation and reduction of the 20-formyl group. The structures of the metabolites were determined from NMR and MS data to be 2'-[O-(beta-D-glucopyranosyl)]chalcomycin (2), 2'-[O-(beta-D-glucopyranosyl)]tylosin (5) and 20-dihydro-2'-[O-(beta-D-glucopyranosyl)]tylosin (4).

Anti-Bacterial Agents↗
PubMed2000

Identification of novel metabolites in the degradation of phenanthrene by Sphingomonas sp. strain P2.

Sphingomonas sp. strain P2, which is capable of utilizing phenanthrene as a sole carbon and energy source, was isolated from petroleum-contaminated soil in Thailand. Gas chromatography-mass spectrometry and (1)H and (13)C nuclear magnetic resonance analyses revealed two novel metabolites from the phenanthrene degradation pathway. One was identified as 5,6-benzocoumarin, which was derived by dioxygenation at the 1- and 2-positions of phenanthrene, and the other was determined to be 1,5-dihydroxy-2-naphthoic acid. Other metabolites from phenanthrene degradation were identified as 7, 8-benzocoumarin, 1-hydroxy-2-naphthoic acid and coumarin. From these results, it is suggested that strain P2 can degrade phenanthrene via dioxygenation at both 1,2- and 3,4-positions followed by meta-cleavage.

Biodegradation, Environmental↗
PubMed2000

Sandhoff disease in Cyprus: population screening by biochemical and DNA analysis indicates a high frequency of carriers in the Maronite community.

In the last 15 years, four patients with the infantile form of Sandhoff disease were diagnosed in four different families in Cyprus (population 703,000, birth rate 1.7%). Three of these cases came from the Christian Maronite community (less than 1% of the population) and one from the Greek community (84% of the population). This relatively large number of patients prompted us to initiate an epidemiological study in order to establish the frequency of the mutant allele in Cyprus. Carrier detection was initially based on the measurement of beta-hexosaminidase A and B in both leucocytes and serum. Using the enzyme test, 35 carriers were identified among 244 random Maronite samples and 15 among 28 Maronites with a family history of Sandhoff disease, but only one carrier was found out of 115 random samples from the Greek community. In parallel to the biochemical screening, DNA studies were undertaken in one of the three Maronite patients and in a Greek carrier related to the Greek patient. These studies resulted in the identification of two novel mutations, a deletion of A at nt76 and a G to C transversion at position 5 of the 5'-splice site of intron 8, which have been published. We subsequently screened the carriers detected in the biochemical study for these two mutations using PCR-based tests. Of 50 Maronite carriers examined, 42 were found to have the nt76 deletion. Eight Maronite samples, designated carriers from the biochemical results, were negative for both mutations. It is possible that these individuals were incorrectly classified as carriers since their enzyme values are equivocal, although the presence of another mutation has not been excluded. Two Greek Cypriot carriers and two obligate Lebanese carriers were negative for both mutations. We conclude that there is a high frequency of Sandhoff disease carriers in the Maronite community of Cyprus, approximately 1 in 7, and that a single mutation predominates in this population.

Cyprus↗
PubMed2000

Influence of oral Helicobacter pylori on the success of eradication therapy against gastric Helicobacter pylori.

BACKGROUND: The goal of this study was to see whether Helicobacter pylori (H. pylori) in the oral cavity might adversely affect the outcome of eradication therapy for gastric H. pylori. MATERIALS AND METHODS: Forty-seven patients (36 males, 11 females) with gastric H. pylori infection were enrolled in this study. Gastric H. pylori infection was confirmed by both immunohistological staining with anti-H. pylori antibody and bacterial culture of biopsy specimens. The therapeutic regimen consisted of 30 mg/day lansoprazole, 750 mg/day metronidazole, and 400 mg/day clarithromycin administered for 2 weeks. A fragment of the H. pylori urease gene was amplified by nested PCR for DNA extracted from saliva and dental plaque from the same patients. We examined the correlation between the gastric eradication success rate and the prevalence of H. pylori in the oral cavity as determined by PCR before and after the eradication therapy. RESULTS: The eradication success rate was significantly lower in the oral H. pylori-positive cases (12/23, 52.1%) than in the negative cases (22/24, 91.6%) at 4 weeks after the therapy (p =. 0028). Two years later, only 16 of the 23 (69.5%) oral H. pylori-positive cases were disease-free, as compared to 23 of the 24 (95.8%) oral H. pylori-negative cases (p =.018). CONCLUSIONS: H. pylori in the oral cavity affected the outcome of eradication therapy and was associated with a recurrence of gastric infection. We recommend that oral H. pylori should be examined by nested PCR and, if positive, should be considered a causal factor in refractory or recurrent cases.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Competitive reverse transcription-polymerase chain reaction assay for quantification of human multidrug resistance 1 (MDR1) gene expression in fresh leukemic cells.

We have analyzed MDR1 gene expression in 69 clinical samples obtained from 64 patients with leukemic hematologic malignancies by using a competitive reverse transcription-polymerase chain reaction assay with a heterologous competitor RNA. To exclude a false-positive result caused by concomitant normal lymphocytes that physiologically express MDR1, in samples we determined a cut-off value of 8 amol MDR1 transcript per microgram of RNA by simultaneous measurement of rhodamine 123 dye efflux either in lymphocyte or gated leukemic cell populations. Consequently, 23 of 69 samples were concluded to be MDR1-positive in leukemic cells per se. The MDR1 expression rate was significantly correlated with factors such as a history of preceding chemotherapy, elder age of the patient, and certain disease types (eg, leukemia progressed from myelodysplastic syndrome). Moreover, the complete response rate after chemotherapy was significantly higher in MDR1-negative patients than in MDR1-positive patients (52% vs 17%, respectively; P = .01). The assay established will enable the quantification of MDR1 gene expression in blood samples from patients with leukemic hematologic malignancies and will be applicable to clinical laboratories as a routine test.

Adolescent↗
PubMed2000

A novel neuronal cell protecting substance mescengricin produced by Streptomyces griseoflavus.

Neuronal cell death in brain ischemia reperfusion injury such as stroke was induced by L-glutamate toxicity (Choi, D.W. J. Neurosci. 1990. 10, 2493 2501; Coyle, J.T. and Puttfarcken, P. Science 1993, 262, 689 695). In the course of our screening for neuronal cell protecting substances of microbial origin, we isolated a novel compound designated mescengricin from Streptomyces griseoflavus 2853-SVS4(Kim, J.-S., Shin-ya, K., Furihata, K., Hayakawa, Y. and Seto, H. Tetrahedron Lett. 1997. 38, 3431 3434). The structure of mescengricin was determined by a variety of NMR experiments such as HMBC, D-HMBC (Furihata, K., Seto, H. Tetrahedron Lett. 1995. 36, 2817 2820), 1H 15N HMBC (15N-HMBC). It possesses an alpha-carboline structure substituted by a glycerol-ester and a hydroxydihydropyrone. Mescengricin protected chick primary mesencephalic neurons from L-glutamate toxicity with EC50 value 6.0 nM.

Animals↗
PubMed2000

Identification of a taurine transport inhibitory substance in sesame seeds.

An ethanol extract from sesame seeds inhibited the taurine uptake in human intestinal epithelial Caco-2 cells. The uptake of such alpha-amino acids as leucine and glutamic acid was not inhibited by the extract, indicating that this inhibition is specific to the taurine uptake. The unknown inhibitor in the sesame extract was purifled by reversed-phase HPLC by monitoring the inhibitory effect on taurine uptake. The isolated substance was identified as lysophosphatidylcholine, linoleoyl (Lyso-PC), by NMR and MS analysis. Lyso-PC inhibited the taurine uptake in a dose-dependent manner with an IC50 value of approximately 200 microM. Although Lyso-PC is known to be a surface active and cell lytic compound, neither damage nor loss of integrity of the Caco2 cell monolayer was apparent after treating with 200 microM Lyso-PC. Inhibition was observed by incubating cells with Lyso-PC for only 1 min prior to the uptake experiments. These results suggest the direct effect of Lyso-PC on the cell membrane to be the main mechanism for this inhibition. Lyso-PC may play a role in the regulation of certain intestinal transporters.

Biological Transport, Active↗
PubMed2000

Structures of ADP-ribosylated rifampicin and its metabolite: intermediates of rifampicin-ribosylation by Mycobacterium smegmatis DSM43756.

23-(O-ADP-Ribosyl)rifampicin [RIP-TAs (3, Na+ form), RIP-TAf (4, H+ form)] was obtained as an intermediate in the conversion process of rifampicin (1) to RIP-Mb (2) that is mediated by cell homogenates of Mycobacterium smegmatis DSM43756 or of Escherichia coli carrying a mycobacterial mono(ADP-ribosyl) transferase gene, in the presence of NADH. 23-[O-(5'-Phosphoribosyl)]rifampicin (5, RIP-TAp) was also obtained by the reaction of rifampicin with NADH in the presence of a homogenate of M. smegmatis. The structures of 3, 4, and 5 were determined by means of MS and NMR analyses.

ADP Ribose Transferases↗
PubMed2000

Diheteropeptin, a novel substance with TGF-beta-like activity, produced by a fungus, Diheterospora chlamydosporia. II. Physico-chemical properties and structure elucidation.

The structure of diheteropeptin (1), a TGF-beta-like active substance from Diheterospora chlamydosporia Q58044, was determined to be a new cyclotetrapeptide, cyclo[2aminoisobutyryl-(S)-phenylalanyl-(R)-prolyl-(2S,8R,9R)-2-am ino-8,9-dihydroxydecanoyl-] by NMR, mass spectrometric and chemical studies.

Circular Dichroism↗
PubMed1999

A novel frameshift mutation in the McLeod syndrome gene in a Japanese family.

We report a novel mutation in the XK gene (XK) in a Japanese patient with McLeod syndrome. A 50-year-old man showed progressive muscular atrophy, choreic movement, elevated level of serum creatinine kinase, and acanthocytosis. The expression level of all the Kell antigens in erythrocyte was decreased and molecular analysis revealed a single-base (T) deletion at the nucleotide position 1095 in XK. This deletion caused a frameshift in translation, leading to a premature stop codon at the amino acid position 408. We conclude this single-base deletion causes defective Kx protein, which is responsible for the McLeod phenotype in this patient.

Amino Acid Transport Systems, Neutral↗
PubMed1999

Novel splice site mutation at IVS8 nt 5 of HEXB responsible for a Greek-Cypriot case of Sandhoff disease.

Sandhoff disease is caused by abnormalities in HEXB gene encoding the beta-subunit of beta-hexosaminidase. In this study, we analyzed the HEXB gene of a Sandhoff carrier in the Greek-Cypriot community. A G to C transversion was identified in one allele of her HEXB gene at position 5 of the 5'-splice site of intron 8 (IVS8 nt5). One of 13 cDNA clones derived from her lymphocyte HEXB mRNA lacked the last four nucleotides "GTTG" of exon 8, which created a premature termination codon at 11 codons downstream. In vivo transcription of the mutant HEXB gene fragment in CHO cells resulted in deletion of the "GTTG." The mutation has not been found in 40 DNA samples from anonymous donors, indicating that this is not a polymorphism in the Cypriot population. These results clearly indicate that the splice site mutation at IVS8 nt5 is responsible for this case of Sandhoff disease.

Bacterial Proteins↗
PubMed1999

Identification and characterization of a new intermediate in the ribosylative inactivation pathway of rifampin by Mycobacterium smegmatis.

Mycobacterium smegmatis DSM 43756 inactivates rifampin by ribosylation. To study this process of rifampicin, all possible inactivated forms of the antibiotic were extracted and purified. Structural studies showed the presence of a new inactivation product, designated RIP-TAp(23-phosphoribosyl-rifampin). Formation of 23-(O-ADP-ribosyl)rifampin (RIP-TAs) is the first step, followed by removal of AMP to give rise to the newly identified compound. Lastly, dephosphorylation leads to formation of 23-ribosyl-rifampin (RIP-Mb). Feeding experiments with the ADP-ribosylated antibiotic obtained from the cell homogenates of an Escherichia coli strain carrying the cloned M. smegmatis gene confirmed this rifampin inactivation process.

Antibiotics, Antitubercular↗
PubMed1999

ADP-ribosylation as an intermediate step in inactivation of rifampin by a mycobacterial gene.

Mycobacterium smegmatis DSM43756 inactivates rifampin, and the inactivated antibiotic product recovered from culture medium was ribosylated on the 23-OH group. To study this process, the gene responsible for the inactivation was expressed at high levels by the lac promoter in Escherichia coli conferring resistance to >500 microg of antibiotic per ml. Cell homogenates generated a novel derivative designated RIP-TAs; in this study, we determined that RIP-TAs is 23-(O-ADP-ribosyl)rifampin. Our results indicated that RIP-TAs is an intermediate in the pathway leading to ribosylated rifampin and that the previously characterized gene encodes a mono(ADP-ribosyl)transferase which, however, shows no sequence similarity to other enzymes of this class.

ADP Ribose Transferases↗
PubMed1999

Diverse oxygenations catalyzed by carbazole 1,9a-dioxygenase from Pseudomonas sp. Strain CA10.

Carbazole 1,9a-dioxygenase (CARDO) from Pseudomonas sp. strain CA10 is a multicomponent enzyme that catalyzes the angular dioxygenation of carbazole, dibenzofuran, and dibenzo-p-dioxin. It was revealed by gas chromatography-mass spectrometry and 1H and 13C nuclear magnetic resonance analyses that xanthene and phenoxathiin were converted to 2,2',3-trihydroxydiphenylmethane and 2,2',3-trihydroxydiphenyl sulfide, respectively. Thus, for xanthene and phenoxathiin, angular dioxygenation by CARDO occurred at the angular position adjacent to the oxygen atom to yield hetero ring-cleaved compounds. In addition to the angular dioxygenation, CARDO catalyzed the cis dihydroxylation of polycyclic aromatic hydrocarbons and biphenyl. Naphthalene and biphenyl were converted by CARDO to cis-1, 2-dihydroxy-1,2-dihydronaphthalene and cis-2,3-dihydroxy-2, 3-dihydrobiphenyl, respectively. On the other hand, CARDO also catalyzed the monooxygenation of sulfur heteroatoms in dibenzothiophene and of the benzylic methylenic group in fluorene to yield dibenzothiophene-5-oxide and 9-hydroxyfluorene, respectively. These results indicate that CARDO has a broad substrate range and can catalyze diverse oxygenation: angular dioxygenation, cis dihydroxylation, and monooxygenation. The diverse oxygenation catalyzed by CARDO for several aromatic compounds might reflect the differences in the binding of the substrates to the reaction center of CARDO.

Anthracenes↗