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Biomedical subjects

T Hamada

Publications and source records attributed to T Hamada.

At least 451 records · Page 25Linked to original sources
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↗
PubMed1992

Dimensional accuracy of castable apatite ceramic crowns: the influence of heat treatment on dimensional changes and distortion of crowns.

Castable apatite ceramic crowns are subjected to heat treatment during crystallizing and during coloring after casting. The dimensional accuracy of the heat-treated crowns was investigated with respect to its influence on dimensional changes in castable apatite ceramic crowns and on distortion of the interior of the crowns, using two investment techniques and a three-coordinate measuring machine. Dimensional changes were not influenced by the number of coloring firings. Distortion of the interior of crowns was slightly outward at the gingival plane. Shrinkage because of crystallizing was approximately 20 microns and the shrinkage of the gingival plane was equal to that of the occlusal plane.

Apatites↗
PubMed1992

The usage period of dentures and their residual monomer contents.

The quantity of residual monomer content in 24 maxillary dentures was detected by gas liquid chromatography. The residual monomer contents tended to be lower in dentures used for long periods than in those used for short periods. Decreases in the quantities of residual monomer in acrylic resin dentures as a result of aging can be expressed in a hyperbola. The fitted curve also suggests that most of the loss could be accomplished in 5 years; however, complete loss of the residual monomer content takes many years.

Acrylic Resins↗
PubMed1992

Use of plastic bar molded casting in the modification of variably expanding investment to compensate for casting shrinkage of nickel-chromium alloy.

Trial plastic bar molded castings were compared for accuracy with cast crowns by means of a nickel-chromium alloy, which was used to establish the liquid density of variably expanding investments. The plastic bars were invested to evaluate the change of expansion rate in a wide range of six liquid densities from 0% to 100%, and the distances between the sections were measured before and after casting. Wax crowns were cast to obtain a more detailed relation around 0% expansion at seven liquid densities, and the gaps between the base of the die and the margin of the crown were measured before and after casting. The expansion rates of both castings were calculated and thus were proportional to the liquid density; both regression curves indicated high correlation coefficients. As a result of the statistics of the Student's t-test, the difference between the two methods was not significant. The trial plastic bar was useful in establishing the variably expanding investment for precise casting of artificial crowns.

Chromium Alloys↗
PubMed1992

The dimensional accuracy of rectangular acrylic resin specimens cured by three denture base processing methods.

The dimensional accuracy of rectangular acrylic resin specimens was examined when they were processed by three methods: a conventional method, the SR-Ivocap system, and a microwave curing method. The dimensional accuracy was evaluated by the change of the distance vector V, which is calculated by means of measurements of the distances between fixed points on specimens. The specimen cured by the SR-Ivocap system exhibited less dimensional change (p less than 0.05) than those cured by the conventional and the microwave curing methods. The SR-Ivocap system might produce a more accurate denture base than the conventional and the microwave curing methods.

Acrylic Resins↗
PubMed1992

MRI findings of multiple sclerosis with acute transverse myelopathy.

We classified clinically definite multiple sclerosis (MS) patients who underwent brain MRI with superconductive magnet into 2 subgroups: group A, consisting of 14 patients who had shown acute transverse myelopathy (ATM) during the course of illness; and group B, 35 patients without ATM, and the same neuroradiologist, blinded to clinical profiles of the patients, investigated the MR scans. We analyzed some parameters such as distribution, size, shape and number of the lesions. Although the total number of lesions were similar in each group, and the number of small size or patchy shape solitary lesions were not different, the moderate, large, ovoid or confluent lesions were lower in number in group A, compared with group B. The degree of cerebral white matter lesions and periventricular lesions were higher in group B. Brainstem lesions were significantly less common in group A. These results show characteristic differences in MR-detected, possibly pathological, changes between these 2 groups, and support our previous report that group A may constitute a distinct subgroup in patients with MS.

Adult↗
PubMed1992

Myasthenogenicity in the main immunogenic region of acetylcholine receptor as modified by conformational design: an approach to antigenic synthetic peptides.

Myasthenogenic regions in the acetylcholine receptor (AChR) alpha-subunit were studied in view of the conformation-dependent B-cell epitope expected at beta-turn and the MHC class II-restricted T-cell epitope expected at alpha-helix. Torpedo AChR alpha 67-76 and alpha 107-116 were synthesized as the main immunogenic region and the site specific for T-cell epitope in Lewis rat, respectively. Model peptides, synthesized by combining these natural sequence segments or by intervening the segment aligned as Asn-Pro-Gly-Gly (NPGG) in natural sequence segments, were tested in terms of antigenic conformation. The model peptide, alpha 107-116.alpha 67-76.alpha 107-116, was immunogenic in the induction of the animal model of myasthenia, accompanied by the anti-peptide antibody cross-reactive with the native AChR. High antigenicity in antibody assays for various peptide- and native AChR-immunized rats was found when the model peptides, alpha 107-116.alpha 67-76 and/or alpha 107-116.NPGG.alpha 67-76 were used for measurement as antigens. Antigenic conformation for the induction of the disease may thus be different from that for the reactivity to antibody.

Amino Acid Sequence↗
PubMed1992

Differences in HTLV-I integration patterns between skin lesions and peripheral blood lymphocytes of HTLV-I seropositive patients with cutaneous lymphoproliferative disorders.

We examined HTLV-I integration patterns in nine cases of HTLV-I-seropositive patients with cutaneous lymphoproliferative disorders. The Southern blot on EcoRI digests of DNA revealed a discrete band of HTLV-I provirus (monoclonal integration) in either skin lesions or peripheral blood lymphocytes (PBL). Four cases showed the monoclonal integration of HTLV-I provirus only in skin lesions: one case showed only in PBL and two cases showed in both skin and PBL. The Southern blot on PstI digests of DNA revealed a 2.4 Kb band of the internal construct of HTLV-I provirus (polyclonal integration) in the PBL of EcoRI-negative samples. The difference in HTLV-I integration patterns between skin lesions and PBL in these cases suggests that the monoclonal outgrowth of HTLV-I-infected cells in the skin is causatively associated with the pathogenesis of cutaneous ATL.

Aged↗
PubMed1992

Expression of human T-cell lymphotropic virus type-1 gene products in the short-term cultured skin tissues of an adult T-cell leukemia/lymphoma patient with cutaneous manifestations.

Adult T-cell leukemia/lymphoma (ATLL) is recognized as a disease etiologically associated with human T lymphotropic virus type-1 (HTLV-1) infection, but, neither viral replication nor specific virus antigen expression have been detected on ATLL cells distributed in organs, including skin. To examine the latent expression of HTLV-1 in the cutaneous lesions of ATLL patients, we cultured the lesional skin tissues in vitro and applied immunofluorescence staining with mouse monoclonal antibodies Lt-4, GIN-14, and F10, which react with p40tax, p19 and gp21, respectively. We recognized HTLV-1 specific antigens on clustered ATLL cells only in the deeper dermis of the skin after 24 hrs cultivation of the lesional skin tissue from an ATLL patient in RPMI-1640 medium supplemented with 20% fetal calf serum. In the electron microscope, we observed HTLV-1 like particles, 80-140 nm in diameter with envelope and core structures, in the same tissue specimen. These findings suggest that HTLV-1 gene products may be expressed in the skin lesions of ATLL patients and involved in the pathogenesis of skin eruptions in cutaneous type ATLLs. To our knowledge, this is the first report that envisages the potency of intracutaneous HTLV-1 expression in vivo.

Aged↗
PubMed1992

Effects of butylated hydroxyanisole on ornithine decarboxylase activity induced by ultraviolet-B and PUVA in mouse skin.

The effects of butylated hydroxyanisole (BHA), a representative phenolic antioxidant, on the activity of ornithine decarboxylase (ODC, an indicator of tumor promotion and epidermal hyperproliferation) induced by ultraviolet-B (UVB) or PUVA in mouse skin were investigated. By topical application of BHA (55 mumol), PUVA-induced ODC activity was suppressed by about 60% at both 12 h and 24 h after treatment. In contrast, BHA failed to suppress UVB-induced ODC activity in mouse skin. These results suggest that the induction of ODC activity by UVB or PUVA is mediated by different pathways.

Animals↗
PubMed1992

Secondary T-cell lymphoma presenting as a giant ulcer.

Secondary cutaneous T-cell lymphoma may present with various types of skin lesions, but rarely produces ulceration in contrast to primary cutaneous T-cell lymphoma. We report a case of malignant lymphoma of the tonsil that recurred as a giant cutaneous ulcer on the back of a 45-year-old man. Biopsy of the ulcer revealed a malignant lymphoma of diffuse, mixed-cell type. Surface marker analysis of the tumour cells showed suppressor/cytotoxic T-cell characteristics. The skin lesions were treated by electron beam therapy.

Humans↗
PubMed1992

Shrinkage of tissue conditioners with time--effect of the particle size in powder and the EtOH content in liquid.

The dimensional change of tissue conditioners with time was measured until 4 weeks after mixing. Shrinkage of the materials was evaluated in relation to particle size in powder and the EtOH content in liquid. The dissolution of EtOH and plasticizer were also measured to investigate the relation to dimensional change. Shrinkage with time was recorded. The smaller the particle size in powder and the more EtOH in liquid, the greater the shrinkage rate. The smaller the particle size in the powder and the more EtOH contained in the liquid, the greater the dissolution of EtOH. The dissolution of BPBG was below 1/100 comparing that of EtOH and no difference was recognized by particle size and EtOH content. On the basis of these results it is suggested that the dissolution of EtOH is related to shrinkage of tissue conditioners with time and that the component particle size in the powder and EtOH content in the liquid have a significant influence on dissolution of EtOH associated with shrinkage.

Chromatography, Gas↗
PubMed1992

Incidence of Paneth cells in minute tubular adenomas and adenocarcinomas of the large bowel.

This study attempted to demonstrate the incidence of Paneth cells within large bowel tubular adenoma and adenocarcinoma according to location and macroscopic appearance using minute tumors (up to 5 mm in size). We have shown that Paneth cells were sometimes seen in the early stage of the development of large bowel epithelial neoplasia. According to the macroscopic appearance (elevated or depressed type), in large bowel epithelial neoplasia, there was a statistical difference between the depressed type (32.5%, 14 of 40 cases) and the elevated type (16.6%, 24 of 145 cases) (Chi square analysis, p < 0.05) in the incidence of Paneth cells. Paneth cells were seen more frequently in adenocarcinoma (45.8%, 11 of 24 cases) than in tubular adenoma (16.8%, 27 of 161 cases), with a significant statistical difference (Chi square analysis, p < 0.01). According to location, in both tubular adenoma and adenocarcinoma, Paneth cells were more frequently observed in the proximal colon (tubular adenoma: p < 0.01, adenocarcinoma: p < 0.05, Chi square analysis).

Adenocarcinoma↗
PubMed1992

Ultrasonography and Doppler studies in twin-to-twin transfusion syndrome.

In 40 twin pregnancies, the evaluation of hemodynamics by ultrasound was performed during the period January 1986 through September 1991. The blood flow velocities' waveforms in the umbilical artery, umbilical vein and tricuspid valve, and the total cardiac dimension, were obtained by ultrasonography in conjunction with 3.5 MHz pulsed Doppler ultrasound. Six patients with twin pregnancies were identified as having twin-to-twin transfusion syndrome (TTS), on the basis of like-sex twins with monochorionic diamniotic placentation, vascular anastomosis in the placenta, and umbilical cord venous blood hemoglobin difference exceeding 5 g/dl at delivery. No distinctive findings for TTS were revealed by the measurement of umbilical artery blood flow velocity waveforms. However, cardiomegaly in 5 recipient fetuses and tricuspid regurgitation and biphasic umbilical vein waveforms in 3 recipient fetuses constituted characteristic features of TTS. Ultrasonography and a Doppler study might be beneficial in diagnosing TTS and evaluating the hemodynamics in a recipient fetus.

Blood Flow Velocity↗
PubMed1992

The effects of glucose concentration on early embryogenesis using the whole embryo culture system on rats.

In order to investigate the effect of hyperglycemia on fetal teratogenesis, rat embryo culture was performed according to the method of New et al. The effect of hyperglycemia was then studied at glucose concentrations of 300, 600, 900 and 1,200 mg/dl in the medium. The embryos from the high glucose medium (600 mg/dl) had significantly shorter CRLs and fewer somites. Major anomalies characterized by neural lesions and minor anomalies characterized by extraneural lesions increased as the glucose concentration increased. However, fetal growth was promoted with statistical significance in the medium with 300 mg/dl of glucose, where the incidence of malformations remained unchanged as compared to the control group. The findings indicate that the glucose is one of the substantial compounds which influences embryo growth, development and abnormalities, but glucose alone appears to have no major effect on early embryogenesis in diabetic pregnancy.

Animals↗
PubMed1992

HLA profiles of multiple sclerosis in Hokkaido, the northernmost island of Japan.

We studied HLA haplotypes in 43 consecutive clinically definite MS patients in Hokkaido. The patients were classified into Group A, 12 patients with acute transverse myelopathy (ATM) during the course of illness, and Group B, 31 without ATM. We found an association with HLA-DQw7 in Group A, and with DR4 and DRw8 in Group B. The frequency of DQw7 and DR4 were significantly different between Groups A and B. This study may indicate the different genetic backgrounds between the groups. DRw8 and DRw52 antigens were significantly more common in MS than in controls. Our result is inconsistent with previous Japanese studies, and ethnic variation might be considered as a possible cause of the contradiction.

Adult↗