PubMed Health⌕ Search

Biomedical subjects

H Nikawa

Publications and source records attributed to H Nikawa.

At least 55 records · Page 3Linked to original sources
PubMed1995

Effect of components of resilient denture-lining materials on the growth, acid production and colonization of Candida albicans.

Variation in the components of soft lining materials, i.e. the size of polymer particles, the ethyl alcohol content of the liquids and the type of plasticizer, were investigated with respect to their effects on the growth and colonization of Candida albicans. Inhibitory effects on fungal growth and/or acid production were found to vary depending upon the components of soft lining materials. In particular, two plasticizers, benzyl benzoate (BB) and benzyl salicylate (BS), significantly decreased the growth rate, whereas the size of polymer particle had little effect on fungal growth. Ethyl alcohol content of liquid significantly affected the fungal growth and/or acid production depending upon the plasticizer used. For instance, in the case of BS, the antifungal effect was related to ethyl alcohol contents, whereas a reverse effect was observed with benzyl n-butyl phthalate (BBP). Further examination using scanning electron microscopy revealed that Candida blastospores colonized lining materials in the following two ways depending on the plasticizers used. On the BS and dibutyl phthalate (DBP) specimen, the blastospore of this yeast associated loosely, whereas, in the case of BB, BBP and butyl phthalyl butyl glycorate (BPBG), fungal blastospore tightly and invasively colonized onto the specimens. These results clearly demonstrated a relationship between components of soft lining materials and fungal growth and colonization.

Analysis of Variance↗
PubMed1995

A novel method to study the hyphal phase of Candida albicans and to evaluate its hydrophobicity.

As little is known about the surface properties of the hyphal phase of the dimorphic fungus Candida albicans due to the difficulty in examining the latter phase in isolation, a novel method was designed to compartmentalize the two phases of the yeast using a commercially available filter-type device-Chemotaxicell. When yeast cells in the blastospore phase were incubated in filter chambers of Chemotaxicell submerged in hyphal-induction media, hyphae traversed through the pores of the filter into the exterior of the chamber enmeshing the entire outer filter surface, after 72 h of incubation. However, the inner or the chamber surface of the filter comprised mainly blastospores. The hydrophobicity of the two morphologic phases of the yeast was then compared using this method, by contact angle measurement. When the 72-h specimens with matted hyphal elements were evaluated, the contact angles varied depending on the incubation medium (such as TC 199 or serum), and in each case hydrophobicity of the hyphal phase was significantly higher than the blastopore phase yeasts. This simple, reproducible method should help not only in evaluating the properties of the hyphal elements of C. albicans but also in studying parameters such as saliva and serum, which are known to affect hyphal formation in vivo.

Analysis of Variance↗
PubMed1994

The effect of antifungal agents on the in vitro susceptibility of Candida albicans to apo-lactoferrin.

The effect of subminimal inhibitory concentrations (MICs) of nystatin, amphotericin B, clotrimazole, miconazole and 5-fluorocytosine on the in vitro susceptibility of Candida albicans to physiological concentrations of apo-lactoferrin was investigated. Pre-exposure of C. albicans in 1:4 and 1:16 MICs of the antifungals resulted in an increased resistance to apo-lactoferrin-mediated cell death. Preincubation of Candida in tunicamycin (an agent that inhibits the synthesis of yeast cell-wall mannoproteins) and subsequent exposure to apo-lactoferrin enhanced the antifungal activity, whilst addition of ergosterol (a yeast cell-wall component) to the assay suspension had no significant effect. These results taken together indicate that apo-lactoferrin, an important component of saliva, interacts with cell-membrane constituents of C. albicans such as mannoproteins, and may modulate the effect of topical antifungal agents commonly prescribed for oral candidoses.

Amphotericin B↗
PubMed1994

Effects of denture cleansers on direct soft denture lining materials.

The deterioration of six commercial resilient denture lining materials immersed in seven groups of denture cleansers was investigated. Although the grades of deterioration of these soft liners were not related to the amount of peroxide content or the pH of denture cleansers, the effects of peroxide cleansers were, with few exceptions, more severe than those of the other types. For example, an enzyme cleanser caused severe changes of one soft liner. The grades of surface porosity were correlated well with the log of the gelation time of the tissue conditioners (except for one soft liner), in four kinds of peroxide cleansers. These results suggest that various components of denture cleansers and soft lining materials, particularly peroxides, in cleansers and gel formation components of soft liners play important roles in the deterioration of soft liners caused by cleansers.

Acrylic Resins↗
PubMed1994

Growth and/or acid production of Candida albicans on soft lining materials in vitro.

Effects of soft lining materials on the growth and/or acid production of Candida albicans were investigated using a simplified method monitoring the pH change in the growth medium. Reverse sigmoidal pH curves were observed with all samples and, as compared with acrylic, all soft lining materials inhibited fungal growth or acid production in the following way, i.e. delay of the beginning of a rapid and linear decline in pH, decreases in the rate of linear change in pH and increases in minimum pH. Further examinations using a surface-modified glass tube revealed that the order of Candida growth agreed with the relative hydrophobicity and adherence capacity of substrates, suggesting that this adherence capacity affected the yeast growth on their surfaces. Besides adherence capacities of substrates, the powder, liquid and plasticizer of some soft lining materials directly inhibited Candida growth. Thus, the results obtained here revealed that several factors within soft lining materials affected Candida growth and/or acid production.

Acrylic Resins↗
PubMed1993

Interactions between denture lining material, protein pellicles and Candida albicans.

The interactions between pellicles derived from saliva, serum, mucin and lysozyme deposited on lining material (tissue conditioner) and Candida albicans were investigated by monitoring pH changes associated with protein-free and protein-coated lining material and by ultrastructural observations of yeast colonization. No significant differences in pH reduction between culture media in contact with the protein-free, control lining materials and those coated with saliva, serum or mucin were observed after 120 h of incubation. However, scanning electron microscopy revealed that much greater numbers of the yeasts colonized the saliva- or serum-coated lining material than the lysozyme-, mucin-coated or control material. Hyphal invasion was observed in saliva-coated lining material. These results suggested that denture pellicle derived from saliva and/or serum may potentiate candidal colonization of denture lining materials.

Adhesiveness↗
PubMed1993

The fungicidal effect of human lactoferrin on Candida albicans and Candida krusei.

Five oral isolates each of Candida albicans and Candida krusei were studied for their sensitivity to the fungicidal effect of human lactoferrin. Significant inter- and intraspecies variations were observed and with most isolates the sensitivity of C. krusei to lactoferrin was greater than that of C. albicans. Fungicidal activity of lactoferrin was dose-dependent and observable only with the iron-free form of the molecule (apo-lactoferrin). Iron-saturated lactoferrin was ineffective against all isolates. Supernatant protein assays and scanning electron microscopy indicated cell surface alterations--leakage of proteins and formation of surface blebs--only in those Candida isolates that were sensitive to apo-lactoferrin. As lactoferrin is a common, non-immune, mucosal defence protein, its varying mode of action against C. albicans and C. krusei may be related to their different oral carriage rates.

Analysis of Variance↗
PubMed1992

Factors involved in the adherence of Candida albicans and Candida tropicalis to protein-adsorbed surfaces. An in vitro study using immobilized protein.

The adherence of Candida albicans and C. tropicalis to protein-adsorbed surfaces was investigated with surface-modified glass slides to which serum or salivary proteins were covalently bound. A specific adherence like a ligand-receptor interaction was observed between C. albicans and mucin- or salivary protein-immobilized glass slides. This interaction was eliminated by deglycosylation of the slides, suggesting that the receptor may be an oligosaccharide(s) contained mucin or saliva. A similar specific interaction was also observed between C. tropicalis and fibrinogen-immobilized glass surfaces. When the numbers of adherent cells to deglycosylated protein-immobilized glass glides were plotted against zeta potentials and contact angles of these protein-immobilized glass slides, a significant correlation was observed between the numbers of adherent cells and zeta potentials in the case of C. albicans (r = -0.87), whereas a significant correlation was observed between cell numbers and contact angles (r = 0.82) in the case of C. tropicalis. These results suggest that the forces governing the adherence of fungi to pellicle in dentures may vary depending upon the surface properties of fungi and substrate.

Adsorption↗
PubMed1992

In vitro evaluation of Candida albicans adherence to soft denture-lining materials.

The adherence of Candida albicans to seven commercial soft denture-lining materials was studied in vitro with BCA protein assay reagent. A good correlation was observed between the amount of protein in yeast cells and the number of yeasts (r = 0.993, p < 0.01), and it was revealed that the adherence of C. albicans to bare surfaces of these soft denture-lining materials correlated well with their relative hydrophobic properties (r = 0.905, p < 0.01); thus there was consistency with the thermodynamic theory. These results combined corroborated the accuracy of this method. To know the effect of pellicle on fungal adherence, the adherence of C. albicans to saliva-coated samples was examined. It was revealed that neither the amount of protein adsorbed by substrates nor the adherence of yeast to saliva-coated substrates correlated with the relative hydrophobic properties of these samples, suggesting that factors other than hydrophobic interaction play an important role in the adherence of C. albicans to pellicle-coated soft liners and tissue conditioners.

Analysis of Variance↗
PubMed1991

Denture stomatitis and ABO blood types.

To determine the interrelation between ABO blood types of denture wearers, denture plaque accumulation, and denture stomatitis, 442 denture wearers were studied using a simplified culture method, which is convenient to use in the dental office. The degree of plaque accumulation and the occurrence of denture stomatitis varied depending on the blood type of the patients. Especially in blood group O compared with other types, both denture plaque accumulation and denture stomatitis were found to be higher or more severe. These results suggest that the ABO blood group is one of the etiologic factors of denture stomatitis and that denture wearers of blood group O are more susceptible to denture stomatitis.

ABO Blood-Group System↗
PubMed1990

Binding of salivary or serum proteins to Candida albicans in vitro.

This binding was investigated with a simplified method: whole saliva and mucin bound to C. albicans in significantly greater quantities than other proteins such as whole serum, albumin, lysozyme or fibrinogen; and the enzymatic treatment of C. albicans with chymotrypsin, papain or mannosidase decreased the amounts of these proteins bound. These results, taken together, suggest that salivary proteins or mucin may bind to the mannoprotein of C. albicans.

Blood Proteins↗
PubMed1990

[Clinical survey on denture stomatitis. 2. The relation between the maintenance of denture and denture stomatitis].

A previous study suggested that denture plaque played an etiologic role in denture stomatitis. In daily practice, it is important to instruct denture wearers about denture plaque control. In this study, the major areas of investigation were the degree of denture stomatitis and denture plaque, denture hygiene habits, wearing habits and age of present denture. 643 patients wearing dentures (1981-1988) were selected, from 47 to 91 years old. The following results were obtained. 1. About 50 percent of the 643 patients used brush for cleaning their dentures. The number of people wearing dentures during sleep was fewer than those who preferred removal of dentures during sleep. 2. Soaking dentures in denture cleanser reduced the degree of denture stomatitis and denture plaque. 3. The patients wearing dentures during sleep showed much more occurrence of denture stomatitis than those who had not that habit. 4. Denture stomatitis occurred frequently with increasing the age of the present denture. The present results indicate that the occurrence of denture stomatitis is closely related to the quality of the maintenance of denture.

Aged↗
PubMed1989

[Clinical survey on denture stomatitis. 1. Relation between denture plaque and denture stomatitis].

Denture stomatitis is a very frequent complication of the denture wearers. In this study, the relation between denture plaque and denture stomatitis was evaluated by a simplified culture (STOMASTAT). 583 patients wearing dentures (1981-1987) were selected, from 47 to 91 years old. The following results were obtained. 1. Degree of denture plaque in 583 patients was severe, moderate, and no detection: 30, 35 and 35%, respectively. 2. Grade of denture stomatitis in 583 patients was severe, moderate, and no symptom: 24, 36 and 40%, respectively. In this survey, the occurrence of denture stomatitis was about 60%. 3. The good correlation between degree of denture plaque and grade of denture stomatitis was recognized in this study. The present results suggest that denture plaque plays an etiologic role in denture stomatitis and, in daily practice, it is important to instruct denture plaque control for denture wearers.

Aged↗
PubMed1989

Non-specific adherence of Candida species to surface-modified glass.

The nature of the physicochemical forces involved in the adherence of Candida species to a solid surface was investigated using modified glass slides. It was found that hydrophobic yeasts adhered to hydrophobic surfaces mainly by hydrophobic interactions, whereas in less hydrophobic yeasts electrostatic interactions seemed to play a more important role in adherence to the solid phase.

Candida↗
PubMed1985

[Apparatus for heart rate biofeedback training].

Present study was undertaken to develop an apparatus for heart rate biofeedback training in clinical basis. The plethysmographic transducer was used for detection of pulses. The main part of this apparatus is composed of three systems in function, that is, an audiovisual feedback system of heart rate in analogue and digital manners, a reinforcement system of exteroceptive stimuli of light and/or sound and operant biofeedback system. Experimental inspection of the apparatus showed no problem except a case of angiospasm of fingers. Clinical trials revealed that this apparatus was available to the biofeedback control of heart beats in both normal volunteers and some cardiac patients.

Adult↗
PubMedDate not supplied

Relationship between thigmotropism and Candida biofilm formation in vitro.

The biofilm formation of the oral fungal pathogen Candida on denture acrylic strips coated with saliva or serum was examined in relation to the ability to induce hyphae by thigmotropic reaction, using C. albicans (4 isolates), C. glabrata (3 isolates) and C. tropicalis (3 isolates). Both the degree of biofilm formation and the amount of hyphae exhibiting thigmotropism varied depending upon both the species and strains of Candida. Although there was no significant correlation between the amount of hyphae induced by thigmotropic reaction of fungal isolates and biofilm formation on uncoated control specimens (r = 0.577; p < 0.05), the ability of hyphae induced by thigmotropic reaction significantly correlated with the amount of both saliva- and serum-admixed biofilms (r = 0.734; p < 0.05 and r = 0.793; p < 0.01, respectively). Taken together our in vitro data suggested that the hyphal induction by thigmotropic reaction is of importance in candidal biofilm formation on saliva- or serum-coated acrylic surfaces.

Acrylic Resins↗