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Biomedical subjects

S Imayama

Publications and source records attributed to S Imayama.

At least 91 records · Page 5Linked to original sources
PubMed1992

Scanning electron microscopic study on dendritic cells and fibroblasts in connective tissue.

Perfusion fixation and intravascular resin injection were used to study in situ the cells of superficial fascia (loose connective tissue) of the rat limb by scanning and transmission electron microscopy. These procedures enabled us to differentiate fibroblasts, representative cells of the connective tissue and so-called "dendritic cells," the other cellular constituent of the tissue, known as possible antigen presenting cells. "Dendritic cells" were amoeboid with some spatular processes by which the cells clung to the collagen fiber bundles. The fine structures characteristics of macrophages; they contained abundant primary and secondary lysosomes and expressed factor XIIIa in their cytoplasm. Fibroblasts, on the other hand, were attenuated, sheet-like cells whose edges were juxtaposed closely to collagen and elastic fibers, and were further anchored by microfibrils. The cells were usually interconnected to each other with gap junctions, thus producing a cellular network in the connective tissue.

Animals↗
PubMed1991

Malignant granular cell tumor.

A malignant granular cell tumor (MGCT) appeared on the subungual tissue of the right index finger of a 51-year-old woman. Two years after resection of the tumor, it recurred, and the finger finally had to be amputated. Six months later, she noticed multiple cutaneous nodules on her trunk. Despite chemotherapy and X-ray irradiation, the patient died 18 months after the second operation. Histology of the specimen revealed a proliferation of both polygonal and spindle-shaped cells with large hyperchromatic nuclei and an eosinophilic granular cytoplasm. Peripheral nerves were encompassed by the tumor cells. Immunohistochemically, the tumor cells were positive for S-100 protein and Leu 7 (myelin-associated glycoprotein). These findings support the hypothesis that MGCT cells are of Schwann cell origin.

Diagnosis, Differential↗
PubMed1991

Drug eruptions following treatment with prodrugs: a review of the reported cases in Japan from 1984 to 1989.

A review of 872 cases of drug eruption reported in the Japanese dermatological journals from 1984 to 1989 has revealed a growing subset related to treatment with prodrugs, in which the responsible agent may be the metabolite rather than the prodrug itself. This situation is the result of the presence in tissues and fluids of only the metabolite following absorption and degradation of the prodrug. Because of this condition, patients with drug eruptions after prodrug treatment may develop positive patch test and/or lymphocyte stimulation test reactions not only with the introduced prodrug but also with the metabolite produced in vivo and further with other prodrugs which degrade into the same metabolite.

Adult↗
PubMed1991

[The mite-free room (MFR) for the management of atopic dermatitis: living in the MFR improved first the itch and then the dermatitis].

While there are increasing data supporting the view that mite allergen sensitivity is one of the major causes of atopic dermatitis (AD) as well as asthma, it is practically difficult to avoid house dust allergens as part of the management of AD. Therefore, we served a conditioned room in which mites were eliminated to the level less than 3 mites/m2, named mite free room (MFR) for experimental treatment of AD to evaluate the possible therapeutic effect of the mite-free condition. Thirteen relatively severe patients with high-IgE RAST score to the mite allergens were treated with night time admission to the MFR without disturbing their social activities in the day time. Our MFR treatment gave eleven of the thirteen patients relief from itch and dermatitis within 2 to 3 weeks, yet they stayed average only 11 hours a day in the MFR. These results may provide a possible candidate in the treatment of AD instead of topical and/or systemic medicines of which prolonged usage is sometimes associated with adverse side effects.

Adolescent↗
PubMed1990

Two cases of pilomatrix carcinoma.

We report two cases of pilomatrix carcinoma. Wide surgical excision, radiation, and chemotherapy were required for the first patient. The tumor eventually revealed the characteristics of a carcinoma, both clinically and histopathologically, as it recurred. In the second case, although the tumor exhibited the histology of pilomatricoma in the central part of the lesion, there were numerous outgrowing irregular nests of basaloid tumor cells with cellular atypia and frequent mitoses; these are the characteristic features of the pilomatrix carcinoma in its early stages.

Adult↗
PubMed1990

Formation of nerve twig-like nests and schwannoma in an unusual case of neurofibroma.

A case of unusual neurofibroma in an 18-year-old Japanese male is reported. The histology of the tumor was characterized by nerve twig-like nests intermingled with fascicular bundles. In the central portion, the tumor also contained a lobular lesion showing features characteristic of schwannoma. Immunohistochemically, the tumor cells in both the nests and the lobular lesion demonstrated a mostly positive reaction for S-100 protein. S-100 protein-positive and -negative cells were observed in equal numbers in the fascicular bundles surrounding the nests. This unusual nerve sheath tumor in which the S-100 protein-positive cells form both nerve twig-like nests and lobular schwannoma has not been reported previously. The origin of the S-100 protein-positive cells in the two lesions is also discussed.

Adolescent↗
PubMed1989

Two cases of myocardial infarction in type 4 Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome is an inherited connective tissue disorder. Clinical manifestations of this syndrome are due to fragile connective tissue. Though many cardiovascular disorders in association with it have been reported, myocardial infarction is quite rare. In this report, two cases with type 4 Ehlers-Danlos syndrome and myocardial infarction are described. Patient 1 was a 30-year-old woman. She was diagnosed as having myocardial infarction on the basis of typical changes in electrocardiograms and serum enzymes (CPK, SGOT and LDH). The diagnosis of type 4 Ehlers-Danlos syndrome was made by the microscopic examination of her connective tissue. Patient 2 was a 32-year-old man. He was also diagnosed as having acute myocardial infarction. His fibroblasts were cultured and they could not synthesize type 3 collagen. Type 4 Ehlers-Danlos syndrome was diagnosed. It was likely that myocardial infarction might have resulted from the fragility of their coronary arteries in type 4 Ehlers-Danlos syndrome.

Adult↗
PubMed1989

A hypothetical explanation for the aging of skin. Chronologic alteration of the three-dimensional arrangement of collagen and elastic fibers in connective tissue.

To provide a morphologic basis for a better understanding of the "aging" of human skin, the authors studied the three-dimensional arrangement and chronological alterations of the fibrous components of the connective tissue using rats aged 2 weeks to 24 months with a new technique for scanning electron microscopy. These studies showed that with postnatal growth there was a dynamic rearrangement of the collagen and elastic fibers: an ordered arrangement of mature collagen bundles was attained by producing a distortion of the elastic fiber meshwork of relatively straight fibers. During adulthood, there was a subsequent tortuosity of the distorted elastic fibers coupled with an incomplete rebuilding of the elastic fiber network, laid down in a form to interlock with the collagen bundles. These changes provide a model for explaining manifestations of aged skin, such as laxity, sagging, and wrinkling. The tortuously fixed elastic fibers imply that they have been stretched and have lost their original elasticity and ability to restitute short and straight. Interlocking of both collagen and elastic fibers should disturb the two independent fibrous systems, as would normally be the case, and thus decrease tissue compliance.

Aging↗
PubMed1988

Scanning electron microscope study of elastic fibers of the loose connective tissue (superficial fascia) in the rat.

A combination of intravascular resin injection and formic acid incubation was utilized to study the three-dimensional arrangement of the elastic fibers in the loose connective tissue (superficial fascia) of the rat limb by scanning electron microscopy (SEM). The cast of the microvasculature served as a scaffolding for the otherwise collapsible connective tissue. SEM study demonstrated that the elastic fibers did not form an anastomosing network but were arranged in multiple layers. The fibers in each layer lay parallel to each other but were oriented differently from the fibers in the layers on either side, thereby producing a meshwork. Each individual fiber was composed of a small bundle of discrete fibrils. Some of these component fibrils separated from the parent fiber and united with other fibers, thus producing branching. The elastic fiber either decreased or grew in size by the respective sharing or joining of these component fibrils with neighboring fibers in their respective layers. Interconnections between elastic fibers of different layers were rare. These findings may provide a morphological explanation for the characteristic function of the superficial fascia, which allows the skin and underlying muscles to have a rapid and extensive alteration in their relative positions.

Animals↗
PubMed1988

Metastatic adenocarcinoma. A case report demonstrating bullous pemphigoid antigen in the tumor.

A case of metastatic adenocarcinoma in the skin of the thigh with an unconfirmed origin is described. Bullous pemphigoid antigen, which is present in the normal basement zone of stratified epithelia, was haphazardly present in the basement membrane zone of the aggregated tumor cells and within the cytoplasm of some cells. This finding indicates that metastatic malignant epithelial cells may produce bullous pemphigoid antigen in the alternative environment, especially if situated in the skin.

Adenocarcinoma↗
PubMed1987

A new concept of basal cell epitheliomas based on the three-dimensional growth pattern of the superficial multicentric type.

Little is known about the growth characteristics of basal cell epitheliomas (BCEs), largely because of the difficulty in studying these tumors, both in situ and in vitro. In this study, the authors report that a scanning electron microscopic examination of 2 cases of superficial BCEs reveals that the tumor proliferates centrifugally as a monolayer beneath the epidermis as well as over the surfaces of hair follicles, while eroding and replacing the original basal architecture. Behind the leading edge of this monolayer, the cells split away from the epidermis to form a round border resembling a carpet being rolled up. This border then develops into a mass lesion, which represents the tumor cell foci seen in routine paraffin sections. These findings have led the authors to propose a fundamentally different explanation for the pathogenesis of these tumors: BCEs are conditioned neoplasms that require contact with the epidermal or hair follicular epithelium in order to grow. This hypothesis could explain the behavior of BCEs as well as the clinical and pathologic varieties observed in clinical practice.

Aged↗
PubMed1985

Delayed type hypersensitivity (DTH) skin reaction to hepatitis B surface antigen (HBsAg) in patients with type B acute and chronic hepatitis.

Skin reactivity to HBsAg was studied in patients with type B acute and chronic hepatitis and in healthy controls. HBsAg preparations containing 50 micrograms/ml of antigen both with and without alum elicited positive skin reactions in all seven anti-HBs+ persons. Histological examination of skin tissue from the reactive area using monoclonal antibodies to the cell surface of lymphocytes revealed accumulation of Leu-3a positive lymphocytes, showing that the inflammation was a typical delayed type hypersensitivity (DTH) reaction. Irrespective of the presence of HBeAg and anti-HBe, patients with chronic type B hepatitis responded clearly to PPD and SK/SD antigens, whereas they did not exhibit DTH skin reactivity to HBsAg. In contrast, although patients with acute type B hepatitis did not exhibit specific DTH a reaction to HBsAg in the acute period, they began to develop DTH skin reactivity to HBsAg in the convalescent phase of the disease preceding the appearance of anti-HBs antibody. It is suggested that DTH reaction to HBsAg might play an important role in the pathogenesis of type B viral hepatitis.

Acute Disease↗
PubMed1984

Pericytes on the dermal microvasculature of the rat skin.

Surface morphology of pericytes of the subepidermal capillary network of rat skin was studied by scanning electron microscopy. Pericytes showed considerable variation in shape, one end of the spectrum representing a fusiform cell body and lateral projections, the other end a club-like, undulated appearance. Most cells of whatever form were disposed parallel to the capillary course and aligned on the dermal side of the vessels. The pericytic processes encompassed up to half of the endothelial circumference, and were not tapered but spatulated at the ends; the cells adhered to the vessel wall only in certain areas. These findings, together with our previous observation that the subepidermal capillaries exhibit fenestrations mainly at the epidermal side of the endothelial lining, suggest a possible functional role of the pericyte in control of material exchange through the vessel wall. The lateral processes of the fusiform pericytes may, by contraction, cause thinning of the capillary endothelium and the formation of fenestrae, while the club-like pericytes may straighten and push the capillary towards the epidermis, if pericytes are indeed contractile cells, as recent studies indicate.

Animals↗