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Biomedical subjects

T Hamada

Publications and source records attributed to T Hamada.

At least 307 records · Page 17Linked to original sources
PubMed1995

Mild emphysema: a novel method using formalin-fixed lungs for computed tomography and pathological analyses.

We evaluated a novel method of computed tomography (CT) analysis using formalin-fixed lungs of autopsy cases with mild emphysema. Eight formalin-inflated lungs (FILs) obtained at autopsy were examined using CT after draining off the formalin and air inflation with an air pump, and subjected to pathological study including pathological scoring of emphysema and microscopic image analysis (MIA). Satisfactory CT examination was carried out within 5 h of lung fixation. The mean alveolar area determined by MIA correlated highly with the lung volume (r = 0.845) and CT score (r = 0.722). This method is simple compared with conventional polyethylene glycol fixation for CT and enables CT examination of resected lungs without anxiety about biohazards, Mild emphysema can be detected by MIA.

Aged↗
PubMed1995

Spinocerebellar ataxia 1 (SCA1) in the Japanese: analysis of CAG trinucleitide repeat expansion and instability of the repeat for paternal transmission.

SCA1 is caused by expansion of an unstable CAG triplet repeat in a novel gene located on the short arm of chromosome 6. In 126 Japanese individuals from 12 pedigrees with SCA1, studies were done to determine if they carried this mutant gene. All the affected and pre-symptomatic individuals, determined by haplotype segregation analyses, carried an abnormally expanded allele with the range of 39-63 repeat units. This repeat size inversely correlated with the age at onset. However, contrary to reported results, size of the repeat did not correlate with gender of the transmitting parent. Therefore, the CAG triplet repeat instability on paternal transmission is not likely to be fundamental to SCA1.

Adolescent↗
PubMed1995

Modulation of the anti-Candida activity of apo-lactoferrin by dietary sucrose and tunicamycin in vitro.

The sensitivity to apo-lactoferrin (apo-LF) of two oral isolates each of Candida albicans and C. krusei preincubated in either sucrose- or tunicamycin-supplemented media was investigated. Known apo-LF-sensitive isolates of both C. albicans and C. krusei demonstrated significantly increased resistance to apo-LF when preincubated in sucrose-supplemented media, but such preincubation had no effect on an apo-LF-resistant isolate of C. albicans, irrespective of the sugar concentration in the medium. Surprisingly, an apo-LF-resistant isolate of C. krusei demonstrated increased susceptibility to apo-LF when preincubated in sucrose. Further, when preincubated with tunicamycin, a chemical that interferes with candidal cell-wall formation, the susceptibility to apo-LF of the resistant isolates increased significantly. These results, when extrapolated in vivo, imply that dietary sucrose may diminish the anticandidal potency of salivary lactoferrin. However, the aberrant behaviour of a single isolate of C. krusei under these circumstances is possibly due to the different cell-wall structure of this yeast and needs to be further investigated.

Apoproteins↗
PubMed1995

CAG repeat expansion of Machado-Joseph disease in the Japanese: analysis of the repeat instability for parental transmission, and correlation with disease phenotype.

Machado-Joseph disease (MJD) is caused by abnormal expansion of an unstable CAG repeat in a novel gene locating on chromosome 14q32.1. We analysed this CAG repeat polymorphism with 66 Japanese MJD patients. All the patients were selectively associated with abnormal expansion of the CAG repeat. Repeat length of the mutant allele did not overlap that of normal allele and closely correlated with not only age at onset but also with clinical phenotypes. CAG repeat size is apparently related to a wide variety of phenotypic presentations in MJD.

Adult↗
PubMed1995

Transfer of methyl chloroform, trichloroethylene and tetrachloroethylene to milk, tissues and expired air following intraruminal or oral administration in lactating goats and milk-fed kids.

The distribution of methyl chloroform was determined (MCF), trichloroethylene (TRI) and tetrachloroethylene (PCE) in milk, tissues and expired air by intraruminally administering 0.625 ml kg(-0.75) of an equal-volume mixture of the three compounds to lactating goats. The milk secreted during 24 h after the intraruminal administration contained 1.42 mg of MCF, 1.87 mg of TRI, 6.43 mg of PCE and 0.33 mg of trichloroethanol (TCE). MCF, TRI and PCE appeared in the blood less than 30 min after administration. Oral administration of these chemicals to milk-fed kids showed that at 3.5 h post-administration, the liver contained these chemicals in greatest abundance. The adaptation of milk-fed kids to 3 weeks administration of small amounts of propylene glycol stimulated the metabolic conversion of TRI to TCE. There were linear relationships between the blood concentrations of these chemicals and the expiration rates after oral administration of 0.4 ml kg(-1) of each chemical to milk-fed kids. The expiration rates of MCF, TRI and PCE were 605, 122 and 46 microg min(-1) kg(-1) at 2 microg ml(-1) blood concentrations of MCF, TRI and PCE, respectively. These results suggested that MCF is little metabolized, being most readily exhaled in expired air, while PCE demonstrates the greatest tissue-partitioning, being largely secreted into the milk or retained in the liver. TRI can be extensively metabolized to other compounds such as TCE in milk-fed kids.

Journal Article↗
PubMed1995

In vitro study on the effects of trial denture cleansers with berberine hydrochloride.

The antifungal activity of trial denture cleansers prepared with berberine hydrochloride was examined against Candida albicans, C. tropicalis, and C. glabrata. A commercial denture cleanser and a trial denture cleanser that exhibited strong antifungal activity were tested for their effects on Candida spp., the color stability of the dental material, and the surface roughness of acrylic resin plates. The results of these tests revealed that the trial denture cleanser removed 64% to 89% of adhered cells from acrylic resin surfaces and had little effect on the other physical properties tested.

Acrylic Resins↗
PubMed1995

Properties of highly cross-linked autopolymerizing reline acrylic resins.

Transverse bend strength tests and water sorption and solubility tests were done to compare the properties of highly cross-linked autopolymerizing reline resin with those of conventional non-cross-linked autopolymerizing reline resins. The relationship between composition and properties of autopolymerizing reline resins was also investigated. Highly cross-linked reline resins and the one that contained mainly poly(methyl methacrylate) and methyl methacrylate had a higher transverse bend strength and modulus of elasticity than the other reline resins (p < 0.01). The highly cross-linked reline resins also had significantly lower water sorption than the other reline resins (p < 0.01). Reline resins, except for one, had significantly higher solubility than heat-polymerizing denture base acrylic resins (p < 0.01).

Acrylic Resins↗
PubMed1995

Effects of cyclosporin and ultraviolet radiation on growth and ornithine decarboxylase activity in cultured human epidermal keratinocytes.

Both cyclosporin (CyA) and ultraviolet radiation are effective in the treatment of psoriasis, but their precise mechanisms of action are uncertain. We investigated their effects on ornithine decarboxylase (ODC) activity, ODC gene expression, and cellular proliferation stimulated by epidermal growth factor (EGF), in cultured normal human epidermal keratinocytes. CyA (5 micrograms/ml) inhibited ODC activity, ODC mRNA level, and cell growth induced by 50 ng/ml EGF. Ultraviolet B (10 mJ/cm2) irradiation suppressed the induction of ODC, ODC mRNA, and cell proliferation stimulated by EGF, but ultraviolet A (0-15 J/cm2) irradiation inhibited neither EGF-stimulated ODC activity nor cell proliferation. These findings indicate that reduction of ODC activity in CyA- or ultraviolet B-treated human keratinocytes may contribute to the antiproliferative mechanism of these agents. These results also suggest that the regulation of ODC activity by ultraviolet B and A irradiation may be mediated by different signal transduction pathways.

Cell Division↗
PubMed1995

Increased expression of lysyl oxidase in skin with scleroderma.

Lysyl oxidase initiates cross-linkage of collagen and elastin by catalysing the formation of a lysine-derived aldehyde. In order to study cross-linking in scleroderma, we used monoclonal antibodies to lysyl oxidase to determine the localization of this enzyme in systemic and localized scleroderma, and compared the distributions obtained with that in normal skin. Using an indirect immunofluorescent antibody method and an avidin-biotinylated enzyme complex method, 11 cases of diffuse type of systemic scleroderma and seven cases of localized scleroderma were studied. In the oedematous stage of systemic scleroderma, intracellular and extracellular lysyl oxidase were remarkably increased in the dermis, particularly in groups around blood vessels. In the sclerotic stage of systemic scleroderma, lysyl oxidase was detected intracellularly in fibroblasts and extracellularly among collagen bundles between the lower dermis and the subcutaneous fat tissue. In localized scleroderma, a marked increase in lysyl oxidase was observed in mononuclear cells and fibroblasts near blood vessels in the lower dermis and in the subcutaneous fat tissue, in addition to the extracellular deposits between collagen bundles. The increase in lysyl oxidase in localized scleroderma was much more common than in the oedematous stage of systemic scleroderma. These findings indicated that intracellular and extracellular expression of lysyl oxidase expression was greater in sclerodermatous skin than in normal skin.

Adolescent↗
PubMed1995

Effects of occlusal splints on the asymmetry of masticatory muscle activity during maximal clenching.

The effects of stabilization splints on the electromyographic activity patterns of the masseter and anterior temporal muscles during maximal clenching in healthy subjects and subjects with different types of stomatognathic dysfunction syndrome were investigated. No marked effect of splints on the asymmetry of muscle activity during bilateral clenching was revealed immediately after splint insertion. During unilateral clenching in the intercuspal position (ICP), the relative asymmetry index (rAI) of the masseter muscles, detecting the imbalance of left and right muscular activity, was significantly increased. The use of splints suppressed the asymmetry of masseter muscle activity during unilateral clenching. This result suggests that the use of a splint is a method of suppressing clench-caused aggravation of stomatognathic dysfunction in the presence of an imbalance between left and right muscle activities.

Adult↗
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

Asymmetry of masticatory muscle activity during intercuspal maximal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome.

The present study investigated the asymmetry of masticatory muscle activity during maximal intercuspal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome, unilateral mastication and the asymmetry of masticatory muscle activity appear to be related to each other. The asymmetry of masseter muscle activity was greater as stomatognathic dysfunction became increasingly severe. Because fatigue and pain are produced more quickly by unilateral clenching than bilateral clenching, clenching under conditions of left and right muscular imbalance can further aggravate stomatognathic dysfunction. It is suggested the asymmetry of masseter muscle activity during maximal clenching correlates with the onset of the stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome is closely related to the asymmetry of masseter muscle activity and only slightly related to the asymmetry of temporal muscle activity. The asymmetry of anterior temporal muscle activity appears to have little clinical significance.

Adolescent↗
PubMed1995

Factors influencing gelation time of tissue conditioners.

To investigate the effects of the composition and structure on the gelation of tissue conditioners, we measured gelation time with an oscillating rheometer. Also, the plasticizer factor was determined using linear multiple regression equations with the dependent variable of gelation time and the independent variables of molecular weight, molar volume, solubility parameter and viscosity of plasticizers. The results obtained were (i) gelation time decreased as the average particle size of poly-ethyl-methacrylate was decreased and its weight average molecular weight increased; (ii) gelation time decreased as ethanol content in the liquid increased. It varied depending on the type of plasticizer; (iii) it was suggested that gelation time was explained by linear multiple regression equations with independent variable of molar volume, solubility parameter and viscosity of plasticizer. In particular, the most influential factor was suggested to be molar volume.

Ethanol↗