Biomedical subjects

Hideyo Yamaguchi

Publications and source records attributed to Hideyo Yamaguchi.

At least 55 records · Page 3Linked to original sources

PubMed2004

Comparative evaluation of standard dilution method and commercial kit for frozen plate antifungal susceptibility testing of yeasts using 200 clinical isolates.

A comparative evaluation of standard microdilution methods and a commercial kit for frozen plate antifungal susceptibility testing of yeasts was performed using amphotericin B, flucytosine, fluconazole, miconazole, and itraconazole on 200 yeast isolates. The isolates included 100 strains of Candida albicans, eight of C. tropicalis, twelve of C. parapsilosis, eight of C. glabrata, five of Cryptococcus neoformans, thirteen of Trichosporon asahii, and 54 other strains of seven other species of ascomycotic yeasts. Microdilution testing was performed according to the standard method for antifungal susceptibility testing published by the Japanese Society for Medical Mycology (JSMM), which are a modification of the method developed by the National Committee for Clinical Laboratory Standards (NCCLS) M27-P. The commercial kit was prepared according to the manufacturer's instructions. The degree of agreement within +/-1 dilution for 200 clinical isolates against five antifungal agents was excellent with values for amphotericin B, flucytosine, fluconazole, miconazole, and itraconazole of 100%, 99.0%, 97.5%, 97.0%, and 97.0%, respectively. Overall, the frozen plate antifungal susceptibility testing kit provided convenient and reproducible results comparable to those obtained with the JSMM standard method.

Antifungal Agents↗

PubMed2004

Characterization of mechanisms of fluconazole resistance in a Candida albicans isolate from a Japanese patient with chronic mucocutaneous candidiasis.

We examined the mechanisms of fluconazole resistance in a fluconazole-resistant Candida albicans isolate from a Japanese patient with chronic mucocutaneous candidiasis. It was demonstrated that the highly resistant phenotype of this strain was associated with combined mechanisms of the energy-dependent reduced intracellular accumulation of fluconazole, presumably due to the increased expression of the ATP-binding cassette efflux pump CDR gene(s), and the reduced affinity of the target enzyme, Erg11p, to fluconazole. In particular, the reduced affinity of Erg11p was considered to contribute largely to the fluconazole resistance in the TIMM3209 strain. Biochemical studies indicated that the Erg11p from the TIMM3209 strain showed reduced susceptibility both to fluconazole and itraconazole of cell-free ergosterol biosynthesis, and cytochrome P-450 also showed reduced affinity to fluconazole in the carbon monoxidecytochrome P-450 complex formation assay. We identified two amino acid substitutions, Y132H and G448V, in Erg11p from the TIMM3209 strain. We found that the cytochrome P-450 from the TIMM3209 strain decayed during incubation at 37 C without fluconazole although it is unknown whether or not the phenomenon is linked to the resistant phenotype. These mutations are thought to confer the above-mentioned characteristics to Erg11p.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

[Status and issues of preclinical evaluation of the therapeutic effects of newly developed antifungal agents].

Preclinical evaluation of the efficacy of an antifungal agent is basically conducted by measuring both the in vitro and the in vivo antifungal activity of the drug using appropriate infection models. Although the first requisite for a method measuring in vitro activity is to obtain results with good reproducibility, an additional requirement is that there be good correlation with the in vivo activity, as described later. For the first condition, in recent years the National Committee for Clinical Laboratory Standards in the United States and the Standardization Committee of the Japanese Society for Medical Mycology have proposed reference techniques with the objective of standardizing drug susceptibility testing; these have been used extensively in measuring antifungal activities of novel agents. However, there are several issues involved when these methods are applied to newly developed drugs. First, standard methods are for particular currently available antifungal agents, but MIC determining standards have not been established for other agents. Reproducibility is therefore not guaranteed. Second, there is a question of whether reliable results can be obtained to test an antifungal spectrum with a limited number of fungal species. On the other hand, in vivo evaluation of novel antifungal agents is extremely important to predict the clinical outcome at the preclinical stage. The important requirements for this in vivo experimental system are: use of an animal model of mycosis that resembles the pathophysiology in humans; use of an administration schedule corresponding to that used in clinical studies, and evaluation of the therapeutic effect considering the dose and administration period. This review presents the present status of preclinical evaluation test methods and discusses the issues.

Animals↗

PubMed2004

Isolation of a promoter region of a secreted metalloprotease gene from Microsporum canis.

MEP3 of Microsporum canis encodes a 43.5 kDa extracellular keratinolytic metalloprotease, which is thought to be one of the virulence-related factors in dermatophytosis. In order to analyze the system underlying the regulation of MEP3 gene expression, the 5'-upstream region was isolated by inverse PCR. The nucleotide sequence of a DNA fragment of about 2.1 kb containing the coding region contains putative transcription factor binding sites and transcriptional initiation points. Further analyses of the regulatory sequence may be useful for understanding the molecular basis of the coordinated expression of the various genes involved in dermatophytosis.

Amino Acid Sequence↗

PubMed2003

Detachment activity of human saliva in vitro for Candida albicans cells attached to a plastic plate.

The effects of human saliva on Candida albicans attached to plastic plates were investigated. C. albicans cells were cultured for attachment to the bottoms of the wells of a 96-well plate, and saliva preparations collected from healthy adults were then added to each well. After various periods of incubation, the number of Candida cells attached to the bottom of each well was measured by the crystal violet staining method. The results showed that, when incubated with human saliva (final concentration, 10% or higher) for 3 h, Candida cells that were attached to the plates became detached from the wells. For characterization of the detachment factor(s), the saliva was divided into three fractions by ultrafiltration. The detachment activity recovered in fractions with molecular weights of 50 K or higher. When the saliva was heated at 100 degrees C for 20 min, its ability to detach Candida cells completely disappeared. When the saliva was treated with 0.025% trypsin, the detachment activity decreased by 57%. These findings suggested that human saliva contains factors for detachment of Candida cells, which are considered to be proteins with molecular weights of 50 K or higher.

Candida albicans↗

PubMed2003

In vitro activity of novel imidazole antifungal agent NND-502 against Malassezia species.

The in vitro activity of NND-502, a novel antifungal imidazole compound, was tested against the three major Malassezia species by an agar dilution method with modified Dixon medium and compared with the activities of three reference antifungal drugs of topical use, lanoconazole (LCZ), bifonazole (BFZ) and terbinafine (TBF). The geometric mean (GM)-MICs of NND-502 for 25 strains of M. furfur, 15 strains of M. sympodialis and ten strains of M. slooffiae were approximately 1.4, 0.1 and 1.0 mg/l, respectively, showing the greatest activity against M. sympodialis and the least against M. slooffiae. These values were similar to that of LCZ, but four to 69 times lower than that of BFZ and two to three times lower than that of TBF. The results suggest that NND-502 might be beneficial in the treatment of Malassezia-associated skin diseases.

Antifungal Agents↗

PubMed2003

Complete regression of mouse mammary carcinoma with a size greater than 15 mm by frequent repeated hyperthermia using magnetite nanoparticles.

Magnetite cationic liposomes (MCLs) have a positive surface charge and are used as a heating mediator for hyperthermia, because they generate heat in an alternating magnetic field (AMF) due to hysteresis loss. In our previous paper, hyperthermia using MCLs was applied to animals having several types of tumors in mice, rats, hamsters, and rabbits, and a strong anticancer effect was observed. For mice, complete tumor regression was observed when the tumor size was smaller than 5 mm. However, a protocol for large tumors is necessary for the clinical application. In the present paper, a protocol for tumors with a size greater than 15 mm in mice was investigated. MCLs were injected into an MM46 tumor (size, 15 mm) in C3H/HeN mice, which were subjected to AMF for 30 min. The temperature at the surface of the tumor reached 45 degrees C and was maintained by controlling the magnetic field intensity. Hyperthermia treatment was repeated twice with 24-h intervals (repeated hyperthermia; RH), and RH was carried out until complete tumor regression was observed. Complete tumor regression was achieved in all mice treated once, twice or six times with RH, and mice acquired antitumor immunity. This protocol, which is termed frequent RH, is a potent approach for cancer therapy.

Journal Article↗

PubMed2003

Suppression of tumor necrosis factor-alpha-induced neutrophil adherence responses by essential oils.

BACKGROUND: In aromatherapy, essential oils are used as anti-inflammatory remedies, but experimental studies on their action mechanisms are very limited. AIMS: To assess their anti-inflammatory activities, effects of essential oils on neutrophil activation were examined in vitro. METHODS: Neutrophil activation was measured by tumor necrosis factor-alpha (TNF-alpha)-induced adherence reaction of human peripheral neutrophils. RESULTS: All essential oils tested at 0.1% concentration suppressed TNF-alpha-induced neutrophil adherence,and, in particular, lemongrass, geranium and spearmint oils clearly lowered the reaction even at 0.0125%. Similar inhibitory activities for the neutrophil adherence were obtained by their major constituent terpenoids: citral, geraniol, citronellol and carvone. In contrast, very popular essential oils, tea tree oil and lavender oil, did not display the inhibitory activity at the concentration. CONCLUSION: Thus, some essential oils used as antiinflammatory remedies suppress neutrophil activation by TNF-alpha at a low concentration (0.0125-0.025 %) in vitro.

Acyclic Monoterpenes↗

PubMed2003

Proliferation of intracellular structure corresponding to reduced affinity of fluconazole for cytochrome P-450 in two low-susceptibility strains of Candida albicans isolated from a Japanese AIDS patient.

Three Candida albicans isolates, TIMM 3164, 3165 and 3166 with reduced fluconazole susceptibility, were isolated from two Japanese AIDS patients. We earlier reported that a reduced intracellular accumulation of fluconazole in these isolates played an important role in the resistance mechanism of fluconazole, but we did not exclude the involvement of other factors. We here examined characteristics related to cytochrome P-450 (CYP), especially sterol 14alpha-demethylase encoded by the ERG11 gene which is the target molecule for fluconazole. In TIMM 3164 and 3165, the ergosterol synthesis by cell-free extracts was somewhat less susceptible to fluconazole, due to a decrease in fluconazole affinity for CYP. The nucleotide substitutions in the ERG11 gene were identified to result in three amino acid changes of K143R, E266D and V488I in TIMM 3164, and of E266D, V404L and V488I in TIMM 3165. These amino acid substitutions might contribute to the decreased affinity for CYP in both isolates. However, a single amino acid change, E266D, observed in TIMM 3166 was unrelated to the decreased affinity for CYP. The most prominent finding on the ultrastructure of TIMM 3164 and 3165 was the development of mesh membrane structures of the endoplasmic reticula, which is a location related to sterol synthesis. This phenomenon was not observed in the cells of TIMM 3166 or the susceptible control strains of ATCC 90028 and 10231. In addition to the reduced intracellular accumulation, the decreased affinity of fluconazole for CYP in TIMM 3164 and 3165 is assumed to be associated with the fluconazole-resistance phenotype.

AIDS-Related Opportunistic Infections↗

PubMed2003

Achievement of complete mycological cure by topical antifungal agent NND-502 in guinea pig model of tinea pedis.

We examined the therapeutic effect of a 1% cream preparation of NND-502, a novel topical antifungal agent, in a guinea pig tinea pedis model produced by infecting the plantar skin of guinea pigs with Trichophyton mentagrophytes. Animals developing tinea pedis were divided into two groups: an untreated control group and a treated group. In the latter group, after confirming infection had been established, the infected animals were topically treated with the NND-502 cream once daily for one week. The animals were reared in a clean environment free from exposure to exogenous dermatophytes. At one week (5 weeks post-infection), 6 weeks (10 weeks post-infection) and 16 weeks (20 weeks post-infection) after completion of the treatment, plantar skin samples were taken from a certain number of both groups of animals. The results demonstrated that all of the animals in the untreated control group and none of those in the treated group were culture-positive in this animal model of tinea pedis. The topical treatment with NND-502 achieved a mycological cure. Thus NND-502 can be considered a promising candidate as a new anti-dermatophytic agent for topical use.

Administration, Topical↗

PubMed2003

DNA base alignment and taxonomic study of genus Malassezia based upon partial sequences of mitochondrial large subunit ribosomal RNA gene.

The sequences of the large subunit of mitochondrial ribosomal RNA (LsmtrRNA) gene of Malassezia species were analysed. The sequences of the seven species of Malassezia are well separated in each species. Therefore the LsmtrRNA gene is thought to be one of the gene targets for species identification in the genus Malassezia. The dendrogram obtained from this gene supports the previous study of Malassezia species based upon the chromosomal genes. This is the first report of taxonomic analysis of Malassezia species based upon the mitochondrial gene.

Base Sequence↗

PubMed2003

A novel murine model of oral candidiasis with local symptoms characteristic of oral thrush.

A conventional and easy method to establish a murine oral candidiasis model, which has not only a stable yeast population in the oral cavity but also symptoms characteristic of oral thrush, was developed by using a sedative agent. Mice were immunosuppressed with prednisolone and were given tetracycline hydrochloride. They were orally infected with 10(6) viable cells of Candida albicans by means of a cotton swab and enough chlorpromazine chloride had been injected to keep them in a sedative state about for 3 hr after inoculation. From day 3 to day 7 post inoculation, 10(5)-10(6) colony forming units of Candida were recovered from the oral cavity of each mouse and whitish, curd-like patches were observed on most parts of tongue. Microscopically, germ tubes had appeared on the tongue surface. This model would be a useful experimental oral candidiasis for investigating the pathogenesis of C. albicans oral infection and the efficacy of various antifungal agents microbiologically and symptomatically.

Amphotericin B↗

PubMed2003

Efficacy of CS-758, a novel triazole, against experimental fluconazole-resistant oropharyngeal candidiasis in mice.

The therapeutic efficacy of CS-758, a novel triazole, was evaluated against experimental murine oropharyngeal candidiasis induced by Candida albicans with various susceptibilities to fluconazole. Against infections induced by strains with various susceptibilities to fluconazole, the efficacy of fluconazole was strongly correlated with the MIC of fluconazole, as measured by the NCCLS method, and agreed with the NCCLS interpretive breakpoints, suggesting that the efficacies of new drugs could be predicted by using this model. The results of the fungal burden study corresponded with the results of the histopathological study. CS-758 exhibited potent in vitro activity (MICs, 0.004 to 0.06 micro g/ml) against the strains used in this murine model including fluconazole-susceptible dose-dependent and fluconazole-resistant strains (fluconazole MICs, 16 to 64 micro g/ml). CS-758 exhibited excellent efficacy against the infections induced by all the strains including a fluconazole-resistant strain, and the reductions in viable cell counts were significant at 10 and 50 mg/kg of body weight/dose. Fluconazole was not effective even at 50 mg/kg/dose against infections induced by a fluconazole-resistant strain (fluconazole MIC, 64 micro g/ml). These results suggest that CS-758 is a promising compound for the treatment of oropharyngeal candidiasis including fluconazole-refractory infections.

Animals↗

PubMed2003

Oral lactoferrin treatment of experimental oral candidiasis in mice.

We assessed the potential of lactoferrin (LF), a multifunctional milk protein, for treatment of oral candidiasis with immunosuppressed mice, which have local symptoms characteristic of oral thrush. Oral administration of bovine LF in drinking water starting 1 day before the infection significantly reduced the number of Candida albicans in the oral cavity and the score of lesions on the tongue on day 7 after the inoculation. The symptomatic effect of LF was confirmed by macroscopic and microscopic observations of the tongue's surface. Similar effects were also observed upon administration of LF pepsin hydrolysate, but not lactoferricin B, an antimicrobial peptide of LF. The anticandidal activity of LF was evident on administration either in drinking water or by intragastric intubation with a stomach tube. These results suggest that the effect of LF in this oral candidiasis model is not due to direct antifungal action. In conclusion, LF could have potential as a food component supporting antifungal drug treatment.

Administration, Oral↗

PubMed2003

[Prophylactic efficacy of a basidiomycetes preparation AHCC against lethal Candida albicans infection in experimental granulocytopenic mice].

The prophylactic effects of a Basidiomycetes preparation, AHCC, against lethal Candida albicans infection were investigated in non treated or immunosuppressed mice. In the cyclophosphamide-or 5-fluorouracil (5-FU)-treated leukopenic mice and nontreated mice, the intraperitoneal administration of AHCC prior to C. albicans infection clearly prolonged the survival periods of the infected mice. In doxorubicin-treated mice, AHCC was less but significantly effective. On the other hand, in prednisolone-treated mice, AHCC was not effective. Oral administration of AHCC also protected the 5-FU-treated mice from lethal Candida infection, as indicated by prolongation of the survival periods and inhibition of Candida growth in the kidneys of these mice and by the increase in a number of neutrophils in their peripheral blood. These results suggested that AHCC may display a protective role against opportunistic fungal infection in leukopenic hosts.

Adjuvants, Immunologic↗

PubMed2003

[Molecular biological analysis of Tinea faciei caused by a clinically anomalous strain of Trichophyton mentagrophytes].

We report a case of Trichophyton mentagrophytes infection. A 27-year-old female dairy worker visited our hospital in August 2001 for evaluation of an erythematous lesion near her right eye. The patient had been treated with antibiotics and an anti-allergic drug at another clinic with no effect on the lesion. KOH preparation of the scale revealed mycelia and T. mentagrophytes was isolated from the culture. The isolated pathogen was identified as T. mentagrophytes animal type 1 by the classification system based on the cluster analysis of nuclear ribosomal internal transcribed spacer 1 (ITS1) DNA sequences. The oral administration of terbinafine at 125 mg/day and antifungal cream was effective. T. mentagrophytes is one of the most common dermatophytes isolated from humans and animals. We should be aware that animals may carry this kind of fungal pathogen.

Administration, Oral↗

PubMed2003

[Anti-Candida albicans activity of essential oils including Lemongrass (Cymbopogon citratus) oil and its component, citral].

The effects of 12 essential oils, popularly used as antifungal treatments in aromatherapy, on growth of Candida albicans were investigated. Mycelial growth of C. albicans, which is known to give the fungus the capacity to invade mucosal tissues, was inhibited in the medium containing 100 micro g/ml of the oils: lemongrass (Cymbopogon citratus), thyme (Thymus vulgaris), patchouli (Pogostemon cablin) and cedarwood (Cedrus atlantica). Not only lemongrass oil but also citral, a major component of lemongrass oil (80%), in the range of 25 and 200 micro g/ml inhibited the mycelial growth but allowed yeast-form growth. More than 200 micro g/ml of citral clearly inhibited both mycelial and yeast-form growth of C. albicans. These results provide experimental evidence suggesting the potential value of lemongrass oil for the treatment of oral or vaginal candidiasis.

Candida albicans↗

PubMed2003

[Antifungal drug].

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Amphotericin B↗