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Mitsunori Ikeda

Publications and source records attributed to Mitsunori Ikeda.

17 recordsLinked to original sources
PubMed2006

Contribution of xanthoma tissue-derived LDL density substances in the transformation of macrophages to foam cells.

BACKGROUND: The source of accumulated lipids in the foam cells of xanthoma is primarily the lipoproteins existing in the lesional dermis. OBJECTIVE: This study was designated to clarify the contribution of low density lipoprotein (LDL) density substances existing in xanthoma tissue to foam cell formation. METHODS: An LDL density fraction was obtained from homogenized rabbit experimental xanthoma tissue. Biochemical and functional characteristics of xanthoma-extracted LDL density substance were examined. The in vivo foam cell-inducing ability of xanthoma-extracted LDL density substance was examined microscopically at the intradermal injection site. RESULTS: Xanthoma-extracted LDL density substance showed more negatively charged mobility on agarose gel electrophoresis than plasma native LDL. A small amount of aggregated material remained at the origin on agarose gel electrophoresis. Xanthoma-extracted LDL density substance contained much higher level of lipid peroxides than native LDL. Mouse peritoneal macrophages internalized xanthoma-extracted LDL density substance extensively and transformed into foam cells by incubation with xanthoma-extracted LDL density substance. Intradermal injection of the xanthoma-extracted LDL density substance induced foam cell infiltration in the skin of a normolipemic rabbit. CONCLUSION: LDL density substances prepared ex vivo from experimental xanthoma tissue contained lipid-protein complexes that have physiochemical properties of oxidized LDL. The lipid-protein complexes were incorporated into foam cells. The substances were considered to contribute to foam cell recruitment during the persistence of xanthoma lesions.

Animals↗
PubMed2006

Neuronal conditions of spinal cord in dermatitis are improved by olopatadine.

Intense pruritus and cutaneous reactivity represent cardinal features of eczema. The resulting scratching behaviors alter neuronal conditions of the spinal dorsal horn where the primary sensory afferent fibers transmit cutaneous stimulation and deteriorate eczematous skin lesions. We investigated the effects of olopatadine hydrochloride (olopatadine) on alteration of neuronal conditions of the spinal dorsal horn and eczematous skin lesions induced by contact dermatitis. Eczematous lesions were induced by repeated application of diphenylcyclopropenone (DCP) in BALB/c mice. Olopatadine suppressed scratching behavior caused by repeated application of DCP in mice. Increased expressions of c-Fos and substance P in the spinal dorsal horn following DCP application were improved by olopatadine. Furthermore, olopatadine diminished the number of infiltrating cells and levels of cytokines in eczematous skin lesions resulting from DCP application. Olopatadine improves neurological conditions in the spinal cord and eczematous skin lesions in a murine contact dermatitis model.

Animals↗
PubMed2005

Hyaluronan forms complexes with low density lipoprotein while also inducing foam cell infiltration in the dermis.

BACKGROUND: Xanthoma is a foam cell infiltrating lesion similar to atherosclerosis. Glycosaminoglycans and proteoglycans have long been considered to play a role in atherogenesis. OBJECTIVE: The purpose of this study is to investigate the role of hyaluronan, the main dermal glycosaminoglycan, in xanthoma formation. METHODS: The complex formation of low density lipoprotein (LDL) with hyaluronan was investigated by assaying the cholesterol level of precipitates that were formed by incubating LDL, hyaluronan and cetylpyridinium chloride in the presence of Ca2+. The uptake of LDL by mouse peritoneal macrophages was studied by assaying the cellular cholesterol esterification activity. The responsible receptor for the LDL internalization was examined by saturating hyaluronan receptor and blocking class A macrophage scavenger receptor (CD204). Hyaluronan was injected into the dorsal skin of diet-induced hypercholesterolemic rabbits to reveal the xanthoma inducing activity of hyaluronan. RESULTS: Cetylpyridinium chloride precipitated hyaluronan, which had formed complexes with LDL. The macrophages incorporated hyaluronan-LDL complexes and oxidized LDL via CD204. Foam cell infiltration and cholesterol accumulation were induced by intradermal injections of hyaluronan in diet-induced hypercholesterolemic rabbits. CONCLUSION: Hyaluronan, like other sulfated glycosaminoglycans, retains LDL by forming a complex. Via macrophage scavenger receptors, macrophages incorporate not only LDL-hyaluronan complexes, but also oxidized LDL, which has been oxidized during the retention time.

Animals↗
PubMed2005

Histamine helps development of eczematous lesions in experimental contact dermatitis in mice.

Histamine is released from mast cells in the skin, causing urticaria and itching. However, little is known about the roles of histamine in development of eczematous lesions in contact dermatitis. Effects of histamine on development of eczematous lesions in contact dermatitis were assessed using histamine-deficient mice in which contact dermatitis was developed by repeated application of diphenylcyclopropenone. Development of eczematous lesions in contact dermatitis was suppressed in histamine-deficient mice compared to wild-type mice. H(1) agonist ((6-12-(4-imidazol)ethylamino)-N-(4-trifluoro- methylphenyl)hepatanecarboxamide) promoted development of eczematous lesions in histamine-deficient mice. H(1) receptor antagonist (loratadine) suppressed development of eczematous lesions in wild-type mice, whereas H(2) agonist (dimaprit) and receptor antagonist (cimetidine) were ineffective. These results suggest that histamine facilitates the development of eczematous lesions in a murine model of contact dermatitis via H(1) receptors.

Animals↗
PubMed2005

Alteration of sensorineural circuits in spinal cord by chronic contact dermatitis.

In the present study, eczema-induced alteration of sensorineural circuits of the spinal dorsal horn was investigated. Eczematous lesions resembling atopic dermatitis were induced by repeated application of diphenylcyclopropenone (DCP) onto murine right hind paws. Immunohistochemical labeling of calcitonin gene-related peptide and substance P was increased in the dorsal horn on the DCP-treated side. Expression of calcium binding proteins, calretinin and calbindin-D28K, normally widely seen in dorsal horn interneurons, was up-regulated on the DCP-treated side. E-Cadherin and alpha-N-catenin, synapse-related molecules, were intensely expressed in the spinal dorsal horn of the DCP-treated side. Interestingly, c-Fos positive cells were also significantly increased in laminae I and III of the DCP-treated side. These results suggest an enhanced release of neuropeptides from peripheral afferents and alterations in the sensorineural circuitry of the dorsal horn. These changes may account for the enhanced sensory sensitivity recognized in patients with chronic eczema and atopic dermatitis.

Animals↗
PubMed2005

Mucinous nevus.

A 15-year-old boy first noticed multiple firm papules on his right upper chest two years before presenting to our clinic. These papules were densely distributed and showed epidermal nevus-like linear arrangement at some sites. The number, size, and distribution of these papules remained unchanged for one year of our observation. The papules flattened leaving scars and did not recur within a year after one shaving abrasion using a scalpel. Histopathologically, epidermis of the papule displayed acanthosis with elongated rete ridges. Accumulation of mucin was apparent in the papillary and subpapillary dermis. In mucinous nevus, the origin of cells with nevoid proliferation is obscure. In contrast with common collagenous connective tissue nevus, it is hard to define the localized persistent mucin accumulation as a nevoid manifestation. The present case of mucinous nevus might be caused by significantly stimulated glycosaminoglycan synthesis in a kind of epidermal nevus without extreme hyperkeratosis.

Adolescent↗
PubMed2005

Spindle cell squamous cell carcinoma showing continuous mesenchymal dedifferentiation in a single tumor.

We report the case of an 85-year-old man who presented with an enlarging tumor on the right temple. Histologically, spindle-shaped cells were proliferating continuously within well-differentiated squamous cell carcinoma that was immunohistochemically negative for vimentin and alpha-smooth muscle actin (ASMA) but positive for cytokeratin (AE1/3). These spindle-shaped cells expressed vimentin and ASMA but not cytokeratin (AE1/3). Intermediate cells with round nuclei and small amounts of cytoplasm displayed slight expression of vimentin, ASMA, and cytokeratin. This case illustrated spindle cell squamous cell carcinoma with mesenchymal metaplasia of malignant epithelial cells.

Actins↗
PubMed2005

Discrete papular mucinosis on the back.

A rare case of papular mucinosis on the back of a 78-year old man is described. The patient developed approximately 20 discrete papules on the upper back. His serum glucose concentration was borderline elevated, but no other systemic symptoms or signs were apparent. A biopsy revealed mucin deposits only in the upper reticular dermis. The papules were distinctly different from lichen myxedematosus in clinical and histochemical appearance. The present case may represent very early-stage lichen myxedematosus complicated by borderline diabetes mellitus.

Aged↗
PubMed2003

Different mechanisms of adhesion molecule expression in human dermal microvascular endothelial cells by xanthoma tissue-mediated and copper-mediated oxidized low density lipoproteins.

BACKGROUND: Oxidation of low density lipoprotein (LDL) has been implicated in infiltration of foam cells derived from circulating monocytes. Monocyte adhesion to endothelial cells and migration into dermis are essential steps for infiltration of foam cells. OBJECTIVE: We investigated the role of adhesion molecules contributing to the process of monocyte adhesion to human dermal microvascular endothelial cells (HDMEC). Special attention was paid to the signal transduction for adhesion molecule expression induced by two distinct types of oxidized LDL. METHODS: HDMEC were incubated with xanthoma tissue-modified LDL (x-LDL), a model of extravasated LDL oxidized in xanthoma lesions, or Cu(2+)-treated LDL (Cu-LDL), a model of oxidized LDL. Adhesion of U937 cells, a human monocytic leukemia cell line, to HDMEC and expression of endothelial cell adhesion molecules on HDMEC were examined. Signal transduction pathways for the adhesion molecule expression were evaluated by employing specific inhibitors. RESULTS: x-LDL induced adhesion of U937 cells to HDMEC through vascular cell adhesion molecule-1 (VCAM-1) and E-selectin by activating tyrosine kinase pathway. Cu-LDL up-regulated the adhesion through not only VCAM-1 and E-selectin but also intercellular cell adhesion molecule-1 (ICAM-1) by activating G(i) protein pathway. CONCLUSION: Extravasated and oxidized LDL in xanthoma lesions contributes to foam cell recruitment by activating tyrosine kinase pathway and inducing adhesion of monocytes to HDMEC through VCAM-1 and E-selectin. Cu-LDL, on the other hand, activates G(i) protein pathway and induces the adhesion through ICAM-1, VCAM-1 and E-selectin.

Cell Adhesion↗
PubMed2003

Coexistence of Riehl's melanosis and lichen planus.

A 61-year-old man presented with purple-red papules and plaques. These lesions on the nape and dorsal aspects of both hands displayed the histological findings characteristic of lichen planus. Riehl's melanosis, which is synonymous with pigmented contact dermatitis, was present on the forehead and bald scalp. Riehl's melanosis typically appears on the face and is induced by cosmetics. Causative factors in this case, however, remained undefined. The coexistence of lichen planus and Riehl's melanosis at separate sites in a single patient suggests that the two diseases represent manifestations of specific immune responses characteristic of lichenoid tissue reaction and situate in the same spectrum. The differences in the skin manifestations of lichen planus and Riehl's melanosis might depend on the severity of immune responses against intrinsic or extrinsic antigens. In addition, the skin manifestations of lichenoid tissue reaction might depend on the disposition of the lesion sites.

Humans↗
PubMed2002

Increased synthesis of calcitonin gene-related peptide stimulates keratinocyte proliferation in murine UVB-irradiated skin.

Repeated ultraviolet (UV) irradiations have been shown to induce keratinocyte proliferation with acanthosis, stimulate the cutaneous nerve proliferation, and increase the synthesis of calcitonin gene-related peptide (CGRP). In the current study, we examined the role of CGRP in the UVB-induced proliferation of murine keratinocytes. UVB irradiation increased the number of bromodeoxyuridine (BrdU)-labeled basal keratinocytes and caused acanthosis. In addition, CGRP expression was up-regulated in the peripheral nerves of the upper dermis and lower epidermis. Repeated intradermal injections of CGRP increased the number of BrdU-labeled basal cells and caused acanthosis. Intradermal injections of capsaicin prior to UVB-irradiation inhibited the UVB-induced CGRP expression, BrdU labeling in basal keratinocytes and epidermal thickening. Intradermal injections of anti-CGRP antibody inhibited the UVB-induced BrdU labeling in basal keratinocytes, but epidermal thickening was not significantly inhibited. These results indicate that CGRP is one of the stimulators to UVB-induced keratinocyte proliferation. On the other hand, expression of substance P, another neuropeptide in the peripheral nerve, was not up-regulated by UVB irradiation.

Animals↗
PubMed2002

Low density lipoprotein oxidized in xanthoma tissue induces the formation and infiltration of foam cells.

Human low density lipoprotein (LDL) was incubated with rabbit xanthoma tissue or non-lesional dermis. The xanthoma tissue-modified LDL (x-LDL) was oxidized showing a 12-fold higher level of thiobarbituric acid-reactive substances (TBARSs) and a faster anodic electrophoretic mobility than native LDL (n-LDL). The LDL treated with non-lesional dermis (d-LDL) had a twofold higher TBARS level compared with n-LDL, but the electrophoretic mobility of d-LDL and n-LDL was similar. Cholesterol esterifying activity in mouse peritoneal macrophages, an indicator of LDL uptake, was up-regulated 5-fold and 1.8-fold by incubation with x-LDL and d-LDL, respectively, compared with n-LDL. Macrophages transformed into foam cells in incubation with x-LDL, and intradermal injections of x-LDL induced infiltration of great many foam cells in the normolipemic rabbit dermis. d-LDL had much less effects on the foam cell formation and foam cell infiltration than x-LDL. Cholesterol:protein ratio was higher in x-LDL than in n-LDL and d-LDL, suggesting that x-LDL-induced foam cells accumulated the lipids by incorporating the cholesterol-rich x-LDL. In conclusion, extravasated LDL receives oxidation and contributes to foam cell recruitment in xanthoma lesions. On the other hand, extravasated LDL in non-lesional dermis receives limited oxidation and additional promoting factors are necessary for initiation of xanthoma development.

Animals↗
PubMed2002

Multiple palmar epidermoid cysts.

Implantation of epidermal fragments into the dermis has been pointed out as the cause of common epidermal cysts. However, some palmoplantar epidermoid cysts have been reported to be caused by human papillomavirus (HPV) infection or to be derived from eccrine ducts. A 65-year-old left-handed woman presented with extraordinary multiple epidermoid cysts on the palm and volar aspect of the fingers of her left hand. HPV infection was not detected by immunohistochemistry, in situ hybridization and polymerase chain reaction. Histological investigation revealed syringeal structures within the cyst wall and in the cyst cavity. Carcinoembryonic antigen was observed in these syringeal structures but was not specifically stained in the cyst wall cells by immunohistochemistry. The cytokeratin composition of the cyst wall cells was similar to that of the nonadnexal epidermis.

Aged↗