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Biomedical subjects

S Imayama

Publications and source records attributed to S Imayama.

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

Effect of 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) enantiomers, major metabolites of phenytoin, on the occurrence of chronic-gingival hyperplasia: in vivo and in vitro study.

The purpose of this study was to assess the possible role of the (R)- and (S)- enantiomers of the phenytoin metabolite p-HPPH in the pathogenesis of gingival hyperplasia (GH). About 98% of circulating p-HPPH is in the (S)-form. There were significant differences between patients with and without GH in (R)-p-HPPH level (0.055 vs 0.042 microgram.ml-1), both enantiomer/racemate level ratios, and R/S enantiomeric ratio (0.0313 vs 0.0232); an increase in serum (R)-p-HPPH level was observed in patients with GH. In separate experiments, the effect of p-HPPH enantiomers on the proliferation of the normal human dermal fibroblast was studied. The in vitro study showed that (R)-p-HPPH selectively stimulated fibroblast growth. The results suggest that the least abundant metabolite, (R)-p-HPPH, is the most toxic with respect to gingival hyperplasia.

Adult↗
PubMed1995

Angiocentric immunoproliferative lesions of the skin show lobular panniculitis and are mainly disorders of large granular lymphocytes.

Eleven patients with angiocentric immunoproliferative lesion (AIL) of the skin were studied. Histologically, three patients were grouped into AIL grade II (AIL-II), whereas eight showed angiocentric lymphoma (AIL-III). All the patients' specimens exhibited lobular panniculitis. Infiltrating atypical lymphocytes in nine patients possessed electron-dense membrane bound granules in electron microscopy. Phenotypically, the lymphoid cells in the AIL-II patients were positive for CD3 epsilon; two of these showed a positive reaction to CD2, CD7, and CD8, but lacked natural killer-associated (NKa) antigens CD16, CD56, and CD57. In six AIL-III patients, lymphoma cells were positive for CD2 in all patients, CD56 in five, CD3 epsilon in four, CD7 in four, interleukin-2 beta receptor in four, a pore-forming protein in four, and CD30 in three patients. The remaining two AIL-III patients had B-cell lymphoma. By the Southern blot analysis, three patients with AIL-III showed a rearranged T-cell-receptor beta-gene or a deletion of its germline. The preceding results in nine of 11 patients suggest that abnormal or neoplastic large granular lymphocytes with the characteristics of T and NK cells have an important role in producing the angiocentric/angiodestructive features and lobular panniculitis. Clinically, all three patients with AIL-II and four with AIL-III showed liver dysfunction, cytopenia, and abnormal coagulopathy during the clinical course. Five patients with AIL-III died within 8 months. The histological grading of AIL, patients' age, and limited clinical stage of the disease seem to correlate with response to the treatment and prognosis.

Adolescent↗
PubMed1995

Degree of ultraviolet-induced tortuosity of elastic fibers in rat skin is age dependent.

To elucidate differential effects of ultraviolet (UV) exposure on three-dimensional networks of elastic fibers during maturation of rat skin, Sprague-Dawley rat hind limbs were irradiated with suberythemal doses of UV light (UVB, 130 mJ/cm2, or UVA, 27 J/cm2) in three different time courses of exposure: 3-9 weeks old, 9-15 weeks old, and 3-15 weeks old. Three-dimensional arrangement with special reference to linearity of elastic fibers was quantified by image analysis using a scanning electron microscope after a combination of intravascular resin injection and selective digestion technique using formic acid. Among the three irradiation groups, the group irradiated with UVB or UVA between 3 and 15 weeks old (UVB, three times per week; UVA, five times per week) elicited the most marked decrease in the linearity of elastic fibers. Despite the same irradiation period, there was a significant difference in the decreased linearity between the two irradiation groups of 3-9 and 9-15 weeks old, with the former irradiation group exhibiting greater loss of linearity than the latter irradiation group. The magnitude of the decreased linearity was greater in the UVB-exposed groups than in the UVA-exposed group. These findings indicate that the three-dimensional linearity of elastic fibers is more susceptible to disruption by UV exposures during the growth period than that after the growth period.

Aging↗
PubMed1995

Increased serum level of interleukin-6 in patients with psoriatic arthritis and thrombocytosis.

The role of elevations of serum cytokines in psoriasis is a provocative issue. We report two patients with psoriasis who had episodes of fever, arthritis, and general fatigue. Their symptoms seemed to be associated with increases in serum levels of interleukin (IL)-6, which paralleled the severity of clinical symptoms as well as elevated serum titers of C-reactive protein (CRP) and platelet counts. Since IL-6 is a multipotential cytokine with B-cell activating, T-cell activating, and thrombocytopoietic functions, the symptoms and abnormal laboratory findings in these patients may have been related to their increased serum levels of IL-6. Monitoring the serum level of this cytokine may thus be useful in evaluating the clinical status of patients with psoriatic arthritis.

Adult↗
PubMed1995

A simple method for measuring the amount of immunoglobulin A secreted onto the skin surface.

We developed a simple method for measuring the amount of the secretory form of immunoglobulin A (sIgA) present in sweat. A small disk (10 x 10 mm) made of cellulose membrane was attached to the skin surface for periods of 1 to 24 h. SIgA was absorbed to the membrane and accumulated during the period of application. Enzyme immunoassay using anti-sIgA and antisecretory component (SC) antibodies revealed distinct dots on the disk that corresponded to the eccrine excretory ducts. A densitograph was used to determine the number and density of the dots, thus obtaining the amount of sIgA excreted to the surface of the skin (per mm2). The amount of skin sIgA excreted differed inter-individually as well as intra-individually. That is, it varied according to the region of the skin, and its distribution roughly reflected that of the sweat ducts. SIgA excretion was maintained at a certain level, regardless of the increased sweating produced by either heat or exercise, which raised the output of sweat 3- to 15-fold. Immunohistochemical studies revealed that fewer glandular cells expressed SC in their cytoplasm as the amount of sIgA decreased. Such an independence of the excretion of sIgA from that of sweat may be necessary to the local immune defenses of the skin.

Absorption↗
PubMed1994

Epidermolysis bullosa herpetiformis (Dowling-Meara type) exhibits ultrastructural derangement of tonofilaments and desmosomes.

Ultrastructural and immunohistochemical studies of clinically intact skin obtained from three severe neonatal cases of epidermolysis bullosa herpetiformis (Dowling-Meara type) demonstrated disorders in the assembly of keratin intermediate filaments and desmosomes of the keratinocytes. During mitosis, K5- and K14-positive and K1- and K10-negative tonofilaments were disrupted and formed spherical bodies associated with intracytoplasmic desmosomes by invagination of the desmosomes and the adjacent plasma membrane. During the invagination process, destructive changes in the internalized membrane were noted. These were accompanied by gradual loss of reactivity with a monoclonal antibody ZK31, which detected plasma membrane adjacent to the attachment plaques of desmosomes. However, the reactivity of the attachment plaques of the internalized desmosomes for desmoplakins and desmoglein did not decline during the process of internalization. In the suprabasal layers of the epidermis, filamentous substructures and K1 and K10 appeared at the periphery of the spherical bodies. Simultaneously, the desmosomes that were sparsely located in the lower epidermis, increased in number as cell differentiation progressed. Thus, the keratinocytes attained an almost normal appearance with respect to tonofilaments and desmosomes by the time they reached the upper layer of the epidermis. These findings may be relevant to the mechanism responsible for the clinical appearance of the herpetiform blisters in epidermolysis bullosa herpetiformis, which are also characterized by spontaneous involution during childhood or when exposed to high ambient temperatures.

Cell Membrane↗
PubMed1994

Reduced secretion of IgA to skin surface of patients with atopic dermatitis.

To investigate whether the secretory form of immunoglobulin A (sIgA) was reduced on the skin surface in atopic dermatitis, the amount of sIgA present in sweat was measured in 40 patients with atopic dermatitis and in 50 healthy volunteers by attaching a cellulose membrane disk (10 x 10 mm) to the inner aspect of the upper arm skin for 24 hours. The secretory form of IgA, which was absorbed to the membrane and accumulated during the period of application, was revealed as dots by an enzyme immunoassay in which antibodies for IgA and for the secretory component were used. The density and number of dots (per mm2/day), which corresponded to the openings of eccrine excretory ducts, were determined with a densitometer. The mean amount of sIgA secreted by those patients was 3.86 +/- 0.71 pg/mm2/day (range, 0 to 21.17 pg/mm2/day), whereas that of the control subjects was significantly higher (p < 0.001), 16.79 +/- 2.80 pg/mm2/day (range, 0.79 to 133.77 pg/mm2/day). This may be related to the high incidence of bacterial and viral skin infections seen in patients with atopic dermatitis, and in addition, to the development of eczematous lesions through a defect in ridding the skin of allergens and/or microorganisms.

Adolescent↗
PubMed1994

Ultraviolet-B irradiation deforms the configuration of elastic fibers during the induction of actinic elastosis in rats.

We used scanning electron microscopy combined with perfusion fixation, resin injection and a selective digestion procedure to determine the effects of ultraviolet-B (UVB) radiation on the three-dimensional architecture of elastic fibers of rat skin. Chronic irradiation with a suberythematous dose of UVB (3 times/week for 12 weeks) produced a tortuous deformation of the superficial elastic fibers in the skin of the rat sole which normally are linearly arranged. Using computer analysis, we evaluated 40 individuals elastic fibers every 3 weeks for 12 weeks following the irradiation. This procedure confirmed the increasing tortuosity of the fibers, which was related to a decline in the elastic property of the skin in situ. Fine elastic branches developed among the deformed fibers and eventually anastomosed to produce an irregular network in the superficial dermal connective tissue, which may correspond to the development of actinic elastosis, that is, the UV-related accumulation of elastic fiber material.

Animals↗
PubMed1994

Clinical and immunohistochemical studies of skin eruptions: relationship to administration of interferon-alpha.

We observed transient, erythematous skin eruptions in 6 patients during the intravenous administration of interferon (INF)-alpha for chronic active hepatitis C. The eruptions appeared 5 to 14 days (mean: 6.8 days) after initiating its administration. They were localized or disseminated and consisted of edematous, erythematous, and/or papular changes. Vesicles and petechiae also appeared in some cases. The eruptions disappeared in 10 to 14 days, despite the continuance of INF-alpha and without specific treatment. Histological examination obtained from skin eruptions revealed perivascular infiltration of lymphoid cells, the majority which were CD4-positive, of the upper dermis. Edematous changes were present in the papillary dermis. Vascular endothelial cells in the upper dermis expressed both intercellular adhesion molecule-1 (ICAM-1) and endothelial leukocyte adhesion molecule-1 (ELAM-1), while the epidermal keratinocytes produced neither. These findings suggested a nonallergic mechanism for such eruptions.

Adult↗
PubMed1994

Differential cell surface distribution of adhesion molecules demonstrated by immuno-scanning electron microscopy.

Scanning electron microscopy with immuno-gold labeling revealed that epidermal keratinocytes expressed ICAM-1 and HLA-DR molecules on their surfaces in patterns that differed in mycosis fungoides (MF) and lichenoid reaction (LR). ICAM-1 molecules, visualized as deposits of gold particles, were present as clusters adjacent to the junctions interconnecting the keratinocytes of MF lesions. LFA-1 molecules were seen as granules on the surfaces of all infiltrates, most of which also expressed ICAM-1. HLA-DR molecules were seen continuously along the borders of the individual keratinocytes. In LR, ICAM-1 and HLA-DR were expressed only sparsely on the undersurface of the epidermis, whereas the infiltrates expressed LFA-1 molecules on their surfaces. These findings may explain the differing histological features of MF and LR: ICAM-1 molecules present on the intercellular junctions of MF epidermis lead the LFA-1-bearing cells to migrate into the interspaces of the keratinocytes, thus producing "epidermotropism". These cells aggregate by means of co-expressed ICAM-1 to thus produce the appearance of a "microabscess". In LR, on the other hand, the minimal expression of ICAM-1 on the epidermal undersurface leaves most infiltrates within the dermis, thus producing a "band-like infiltrate" beneath the epidermis.

Aged↗
PubMed1994

Mite-antigen-stimulated cytokine production by peripheral blood mononuclear cells of atopic dermatitis patients with positive mite patch tests.

To investigate possible involvement of Th1-type immunoreaction in the development of skin lesions of atopic dermatitis (AD), we measured mite-antigen-stimulated production of IL-2, IL-4 and IFN-gamma, using peripheral blood mononuclear cells (PBMC) obtained from 23 patients with AD who developed positive patch test reactions to house dust mite antigens extracted from Dermatophagoides pteronyssinus (Dp). Incubation of these PBMC with the Dp antigen for 72 h produced marked secretion of IL-2 and IFN-gamma, but not IL-4, indicating that Dp-specific T cells were found in these patients' circulating peripheral blood and were capable of producing IL-2 and IFN-gamma, known as major mediators of the delayed-type allergic reaction. Our study suggests that Th1-type cells may be involved in the development of skin lesions of AD patients with positive patch test reactions to house dust mite antigen.

Adolescent↗
PubMed1994

Deposition of basic fibroblast growth factor on surface of epidermal melanocytes suggesting the stromal control of epidermal pigmentation.

Scanning electron microscopy with immunogold labeling was used to demonstrate the in vivo distribution of molecules of basic fibroblast growth factor (bFGF) that were expressed and/or present on the surface of the cells of the normal epidermis and dermal connective tissue of humans. We found that molecules of bFGF, seen as deposits of gold particles, were present densely on the surfaces of the melanocytes but not the epidermal keratinocytes. In connective tissue, these molecules were present exclusively on the surfaces of the fibroblasts, macrophages, vascular endothelial cells, and the basement membrane surrounding the endothelial tube. The selective deposition of bFGF molecules on the melanocytes suggests that the dermal connective tissue may be involved in controlling the proliferation of melanocytes by means of bFGF molecules in vivo, since these melanocytes require bFGF to proliferate in vitro. The latter is synthesized and stored exclusively in the connective tissue.

Adolescent↗