Biomedical subjects

A Kameda

Publications and source records attributed to A Kameda.

At least 19 recordsLinked to original sources

PubMed1991

The effect of site and mode of expression of a heterologous antigenic determinant on the properties of poliovirus hybrids.

The antigenic site normally situated in the EF loop of VP2 (2EF) of poliovirus type 2 (Lansing) [PV2 (L)] was expressed in 2EF or in the BC loop of VP1 (1BC) of PV1 (Mahoney) [PV1 (M)]. A hybrid virus expressing the site in 2EF of PV1 (M) is known to be neutralizable by PV2 (L)-specific antisera and to induce neutralizing antibodies against PV-2 (L). In contrast, a hybrid expressing a related sequence in 1BC of PV1 (M), which maintained the length of the native BC loop, was not neutralizable by PV2 (L)-specific antisera and did not induce PV2 (L)-neutralizing antibodies. However, when 1BC was extended, so that it was longer than the native 1BC, the resulting hybrids induced low titers of PV2 (L)-neutralizing antibody although they were still not neutralizable by PV2 (L)-specific antisera. Synthetic peptides copying the extended sequences raised neutralizing antibodies which were able to distinguish between the sequence expressed in the extended 1BC, in the native-length 1BC and in 2EF. The growth rates of the hybrids with modifications to 1BC depended upon the nature of the modifications. The hybrid with the native length 1BC grew poorly, but extending 1BC tended to improve the growth rate, and extending 1BC with PV1 (M)-specific sequences nearly restored wild-type growth rates. Thus, the size, precise sequence and location of a heterologous antigenic site expressed on poliovirus have significant effects on the properties of that determinant and of the hybrid expressing it. Antigenicity of hybrids can be modified and their growth rate can be enhanced by appropriate choices of these parameters.

Amino Acid Sequence↗

PubMed1991

Phenotypic characterization of antigenic hybrids of poliovirus.

Three poliovirus hybrids, modified in neutralization antigenic sites (NAgs) I or II, were characterized for several phenotypic traits. The modifications to the capsid interfered with some stage of the life-cycle of the virus, since all three hybrids were growth-impaired in comparison to poliovirus type 1 (Mahoney) [PV1 (M)], the wild-type parent virus. All hybrids exhibited a reduced growth rate and a small-plaque phenotype, but they were not temperature sensitive. Furthermore, only one hybrid was slightly less stable to heating than the parent virus; the other two were as stable as the parent. Therefore, decreased thermal stability of the capsid is not an important cause of the poor growth characteristics of these hybrids.

Amino Acid Sequence↗

PubMed1991

Lymphocyte subpopulations and function in childhood IgA nephropathy.

In order to examine T lymphocyte function in childhood IgA nephropathy, 13 patients and 10 age-matched control subjects were studied. T lymphocyte function was examined in terms of in vitro immunoglobulin synthesis by peripheral blood mononuclear cells (PBMC) and CD4-depleted (suppressor-rich) and CD8-depleted (helper-rich) PBMC in both unstimulated and pokeweed mitogen (PWM) and Staphylococcus aureus Cowan I (SAC) stimulated cultures. T lymphocyte subpopulations were examined by two-color immunofluorescence analysis using Fluorescein-Activated Cell Sorter (FACS). Children with IgA nephropathy showed (1) a significant increase in IgA synthesis by PBMC with or without mitogen stimulation, (2) a significant increase in IgG and IgA synthesis by CD4-depleted (suppressor-rich) PBMC, (3) a significant increase in IgG and IgA synthesis by CD8-depleted (helper-rich) PBMC, and (4) a significant decrease in suppressor-inducer T cells (Leu3a+Leu8+). These results suggest that a decrease in suppressor-inducer T cells, impaired suppressor T cell function and hyperactivity of helper T cell function are responsible for the increase in IgA production in children with IgA nephropathy.

Adolescent↗

PubMed1990

Effects of cytokines on human thymic epithelial cells in culture. II. Recombinant IL 1 stimulates thymic epithelial cells to produce IL6 and GM-CSF.

Our earlier study reported the ability of interleukin 1 (IL1) to promote proliferation and to induce morphological changes of human thymic epithelial cells (TEC) in culture. The present study was undertaken to examine the effects of IL1 on the secretory function of TEC. Both human recombinant IL1 alpha and IL1 beta induced TEC to produce molecules in the culture supernatant fluids (TES) which displayed marked thymocyte proliferative capacities. This activity was specifically induced by IL1 since other TEC growth factors such as epidermal growth factor and a bovine pituitary extract had no effect on promoting secretion of T cell-activating molecules by TEC. Using specific radioimmunoassays for both forms of IL1, we found that unstimulated TEC produced negligible amounts of IL1 alpha and IL1 beta in TES, which were not increased by IL1 stimulation, and we concluded that the IL1-induced TES molecules were not IL1. IL1 induced TEC to produce IL6, as detected by the hybridoma growth factor biological activity. Neutralizing anti-IL6 antibodies completely blocked the thymocyte activating capacities of the IL1-induced TES thus implying a major role for IL6 in TEC-derived T cell activation. IL1 also induced TEC to produce GM-CSF as measured by bioassay and confirmed by an immunoenzymetric assay. Our results confirm that TEC are a source of cytokines and show that TEC respond to IL1 by producing cytokines with consequences on the thymic lymphoid population. This further emphasizes the importance and complexity of paracrine molecular interactions involved in intrathymic development.

Antibodies↗

PubMed1990

[An X-ray crystallographic study on effect of acid etching method to enamel and enhancement of crystallinity of the etched enamel with gel method].

With the purpose of studying the influence of enamel acid etching technique, and the effectiveness of a strengthening of tooth enamel by silicahydro gel method, the following groups were compared, analyzed and observed by the measurements of diffracted X-ray from thin layer specimens and by microarea X-ray diffraction from an X-ray crystallographic point of view. Group I: non-treated tooth enamel Group II: acid-etched tooth enamel Group III: tooth enamel by application of silicahydro gel method after being acid etched. The results obtained were as follows: 1. Qualitative analyses by the measurements of diffracted X-ray from thin layer specimens 1) Ca5(PO4)3F, Ca5F (PO4)3 and Ca3(PO4)2.xH2O were detected in every group, and Ca3(PO4)2.xH2O demonstrated a high reliable value in group III. 2) In comparison with groups I and II, group III clearly revealed a peak shift toward high angle side, however, a halo peak was not recognized in every group. 3) As a result of evaluating crystallinity, crystallinity became favorable in order of group II, group I and group III. 4) A-axis lattice constant shortened in order of group II greater than group I greater than group III, and c-axis lattice constant shortened in order of group II greater than group I = group III. 2. Qualitative analyses by microarea X-ray diffraction 1) Solid solution of Ca5(PO4)3F and Ca5(PO4)3(OH) proved to exist in every group and in each microarea. 2) A halo peak appeared in group II and showed the trend of disappearance in group III, however, no peak shift was observed in all groups. From the foregoing results, the loss of the utmost enamel surface layer exhibiting high crystallinity and the lowering of crystallinity by acid etching technique were revealed from an X-ray crystallographic point of view and furthermore if silicahydro gel method was applied, it was suggested that enamel would be restored or that crystallinity would be enhanced.

Acid Etching, Dental↗

PubMed1990

The bond strength of a glass polyalkenoate cement to enamel and stainless steel.

An in vitro evaluation of bond strength of a glass polyalkenoate cement to human dental enamel and stainless steel is reported. Shear testing of adhesive strength was measured over time at 23 degrees C following a one minute mixing time. It was found that there is a significant difference in bond strengths between enamel and stainless steel with strength to enamel the greater. Bond strength increases with time with very low strength measured within 30 minutes from commencement of mixing.

Dental Bonding↗

PubMed1990

Repeat renal biopsy in children with IgA nephropathy.

Serial renal biopsy findings in 61 children with IgA nephropathy were correlated with their clinical course. At the time of the second biopsy, 23 patients showed clinical remission defined as complete disappearance of proteinuria and hematuria with normal renal function while 38 had persistent urinary abnormalities with normal renal function at the second biopsy. There were no differences between the two groups with regard to initial clinical findings and pathologic findings of the initial renal biopsy. The second biopsy of patients with clinical remission showed improvement of the glomerular changes on light microscopy, disappearance or diminution of IgA deposits in the mesangium and decrease of electron-dense deposits, whereas the second biopsy of patients with persistent urinary abnormalities showed progression of glomerular changes on light microscopy, persistence of mesangial IgA deposits and persistence of electron-dense deposits. Our study results show the importance of repeat renal biopsy in children with IgA nephropathy with persistent urinary abnormalities, as a progression of glomerular changes is common in these patients. These observations suggest that the deposition of IgA in the mesangium may be responsible for the glomerular damage in children with IgA nephropathy.

Adolescent↗

PubMed1989

[A study on the formation of apatite crystallized with gel method].

About apatite produced with a silicahydro gel method using calcium nitrate (group I) or calcium chloride (group II) and a gelatin gel method by use of calcium nitrate (group III) or calcium chloride (group IV), the formative volume as well as the formative condition of a periodic-layered precipitate (Liesegang ring), the pH measurement, calculation of Ca/P ratio, an estimation of the chlorine ion, morphological observation with a scanning electron microscope, qualitative analyses by X-ray diffraction (identification, crystallite size, lattice imperfections, lattice constants) and the composition analysis by infrared absorption spectroscopy were carried out to elucidate the formation of apatite using the gel method. The result showed that there were no distinct differences between group I-II and group III-IV, and it is suggested that it is possible to form satisfact fluorapatite with a gel method using calcium chloride as well as calcium nitrate.

Apatites↗

PubMed1989

[Study on the formation of fluorapatite with freeze-drying silicahydro gel method].

Resultant products and gel substance, formed with silicahydro gel method as well as with freeze-drying silicahydro gel method by use of tray, were compared and examined to materialize clinical application of gel method easily and the following results were obtained: 1. Evaluation of gel substance in control group gel (silicahydro gel) and in experimental group gel (gel prepared by the addition of deionized water to freeze-drying silicahydro gel) As the results of measuring the estimation of F- by ion chromatography and pH value, no clear-cut distinction between control group gel and experimental group gel was recognized, however, it was implied by naked-eye observations and through scanning electron microscope with the passage of time that experimental group gel had been inferior to control group gel. 2. Evaluation of resultant products in control group gel (resultant products formed with silicahydro gel method) and in experimental group gel (resultant products formed with freeze-drying silicahydro gel method) Naked-eye observations of reacting progress, the pH measurements, the calculation of Ca/P ratio, qualitative analyses by X-ray diffraction (reference; the measurements of crystallite size, lattice imperfection and lattice constant) and composition analyses by infrared absorption spectrum were carried out and as the results, resultant products in control group gel proved to be more favorable than those in experimental group gel. From the foregoing outcomes, it was suggested that fluorapatite of favorable crystallinity had been possible to be produced more with silicahydro gel method than with freeze-drying silicahydro gel method, and that further investigation inclusive of gel substance would be required in the event of clinically applying freeze-drying silicahydro gel method effectively.

Apatites↗

PubMed1989

[Study on the physico-chemical properties of fluoride gel in application of freeze-drying gelatin gel method (tray method)].

As a means of studies of securing freeze-drying method by application of tray for prevention of white spots, decalcification and secondary caries of enamel, which may develop during and after orthodontic treatment, comparison and review were made on physico-chemical properties of fluoride gel to be used for gelatin gel method and freeze-drying gelatin gel method (control group gel and experimental group gel), and the following results were obtained: 1. Physical properties As the results of naked-eye observations, morphological observations through scanning electron microscope and measurements of gelly strength and viscosity, no distinct difference between control and experimental group gel was noted. 2. Chemical properties The qualitative analyses of fluoride ion with ion chromatogram and pH measurement were carried out, and consequently experimental group gel indicated similar values to control group gel. From the foregoing results, it was learned that no significant difference in their physico-chemical properties was clearly confirmed between control and experimental group gel, and it was suggested that similarly to control group gel, experimental group gel would be an effective gel substance as gel media for the formation process of fluorapatite or the reinforcement method of tooth enamel.

Fluorides, Topical↗

PubMed1989

[Study on frictional characteristics of KB horizontal brackets. A comparative study of kinetic frictional forces to be caused between various kinds of brackets and wires].

KB horizontal brackets were designed to tip no more than 6 degrees at the maximum. This tipping amount is based on the idea of reducing friction between a wire and brackets to allow the effective tooth movement of the Begg technique even with horizontally long brackets, and does not originate in the concept of carrying out tipping movement. Thereon, experimental measurements by use of Rheometer were conducted to review for comparison of the kinetic frictional forces caused between various wires and the following four types of brackets; KB horizontal brackets, Tip edge brackets, Straight edge brackets and Begg brackets. 1. In case of utilizing ribbon arch wires and rectangular wires, no significant difference was acknowledged among Tip edge, KB horizontal and Straight edge brackets. 2. There proved to be a reduction in the kinetic frictional forces by incorporating tip into the edgewise slots, when using smaller dimensions of the wires which call for the effective tooth movement, however, Begg brackets (in conjunction with Ordinary T-pins and/or Safety T-pins) showed the small value which is far less than that of the three kinds of brackets.

Orthodontic Appliances↗

PubMed1989

[Enhancement of enamel crystallinity with gel method during orthodontic treatment. The 2nd report: application of micro-area X-ray diffraction method].

This study is to review an effect on the improvement of enamel crystallinity with gel method in the course of orthodontic treatment by applying gelatin gel method (group II) as well as silica-hydro gel method (group I) to bracket-bonded enamel surfaces of extracted teeth and for a relative review, the chopped cross sections of the above teeth were analyzed by the method of micro area X-ray diffraction. The results obtained were as follows: 1. As a result of identifying by the method of microarea X-ray diffraction, the present of hydroxyapatite, Ca5(PO4)3OH and fluorapatite, Ca5(PO4)3F was recognized at any section of every group. 2. In making a relative study of the variation of line profile and peak shift, an outstanding difference was not acknowledged in line profile, however, peak shift in the direction of high angle side was indicated on the experimental side of each group and a tendency for peak shift was more noticeable near by enamel cuticle. At boundary sites and on the control side, the variation was only shown in one part of group II. Also a tendency for peak shift in the direction of high angle side was recognized in group I rather than in group II. From the foregoing results, it was found to be effective to improve tooth substance of the bracket-bonded enamel and in that event, the silica-hydro gel method was suggested to be superior to the gelatin gel method. Also with the regard to the bracket-bonded sides, tooth substance was noticeably improved at enamel cuticle but not sufficiently improved at sites underneath the brackets and at boundary sites of the both, therefore, one of the future subjects would be to review such areas.

Apatites↗

PubMed1989

[Enhancement of enamel crystallinity with gel method during orthodontic treatment. The 1st report: Application of electron probe X-ray microanalyser].

This paper is to review the gel method of strengthening tooth enamel substance around bonded brackets and morphological observations and elemental analyses of the chopped cross section of the three below-mentioned groups were carried out by electron probe X-ray microanalyser (EPMA) for a relative review. Group I: bracket-bonded extracted tooth enamel in application of the silica-hydro gel method. Group II: bracket-bonded extracted tooth enamel in application of the gelatin gel method. Group III: bracket-bonded extracted tooth enamel in application of neither method. The results obtained were as follows: 1) As a result of making morphological observations through secondary electron image and back scattered electron image, the adhesive condition of the brackets and the state of the chopped cross sections were favorable and these combined observation proved effective as a supplementary method of elemental analysis. 2) Through qualitative analyses, Ca, P, F, O, Na, Mg and Cl were recognized as content elements on the experimental side (the non-bracket side) as well as on the control side (the bracket side) from group I through III. 3) In making ultrahigh-speed wide-area surface analyses (elemental concentration map), the incorporation of F was recognized from enamel cuticle to approximately 200 microns in group I and to 50-100 microns in group II, and the distribution of Ca was totally consistent, and P showed the slight downward trend from enamel cuticle to dentoenamel junction. 4) The incorporation of F was acknowledged to be until 150-200 microns on the experimental side of group I and to be until 80 microns on the experimental side of group II by line analyses. 5) As regards F on the experimental and the control side in group I as well as in group II through a quantitative analysis, the experimental side clearly revealed a high concentration of F and acknowledged 1% level to be a significant distinction. From the foregoing results through the electron probe X-ray microanalyser, strengthening tooth enamel substance in vitro by application of the gel method proved to be effective, and the silica-hydro gel method was indicated to be superior to the gelatin gel method.

Dental Bonding↗

PubMed1988