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Biomedical subjects

Y Miyachi

Publications and source records attributed to Y Miyachi.

At least 55 records · Page 3Linked to original sources
PubMed2000

Ultraviolet B radiation downregulates inducible nitric oxide synthase expression induced by interferon-gamma or tumor necrosis factor-alpha in murine keratinocyte Pam 212 cells.

Ultraviolet radiation causes inflammation characterized by erythema and swelling, but also exhibits antiinflammatory effects which have led to the use of ultraviolet B radiation (UVBR) and psoralen plus ultraviolet A (PUVA) in the treatment of psoriasis, chronic severe atopic dermatitis and uremic pruritus. In inflammatory dermatoses, a pathogenic role of nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) has been suggested. To elucidate how UVBR regulates iNOS expression in skin under inflammatory conditions, we investigated the effect of UVBR on NO production and iNOS expression in cultured murine keratinocyte Pam 212 cells stimulated with interferon-gamma (IFN-gamma) or tumor necrosis factor-alpha (TNF-alpha). Low doses of UVBR significantly suppressed IFN-gamma- or TNF-alpha-induced NO production. UVBR also downregulated IFN-gamma- or TNF-alpha-induced iNOS expression at both the mRNA level and the protein level. These findings suggest the possibility that the down-regulatory effect of UVBR on IFN-gamma- or TNF-alpha-induced iNOS expression may, in part, explain the antiinflammatory and therapeutic properties of UVBR in inflammatory dermatoses.

Animals↗
PubMed2000

Facilitated wound healing by activation of the Transglutaminase 1 gene.

Transglutaminase 1 (TGase 1) is a Ca(2+)-dependent enzyme which catalyzes epsilon-(gamma-glutamyl)lysine cross-linking of substrate proteins such as involucrin and loricrin to generate the cornified envelope at the cell periphery of the stratum corneum. We have shown that disruption of the TGase 1 gene in mice results in neonatal lethality, absence of the cornified envelope, and impaired skin barrier function. Based on the importance of TGase 1 in epidermal morphogenesis, we have now assessed its role in wound healing. In neonatal mouse skin, TGase 1 mRNA as well as keratin 6alpha was induced in the epidermis at the wound edges as early as 2 hours after injury and that expression continued in the migrating epidermis until completion of re-epithelialization. The TGase 1 enzyme co-localized on the plasma membrane of migrating keratinocytes with involucrin, but not with loricrin, which suggests the premature assembly of the cornified envelope. Similar injuries to TGase 1 knockout mouse skins grafted on athymic nude mice showed substantial delays in wound healing concomitant with sustained K6alpha mRNA induction. From these results, we suggest that activation of the TGase 1gene is essential for facilitated repair of skin injury.

Animals↗
PubMed2000

Pathophysiology and diagnosis of Cushing's syndrome.

Prolonged exposure of every tissue in the body to an excess of cortisol produces Cushing's syndrome. Endogenous causes of Cushing's syndrome are ACTH-dependent, including Cushing's disease, ectopic ACTH-producing tumors. CRH-producing tumors, and ACTH-independent Cushing's syndrome, including cortisol-producing adrenal benign or malignant tumors, and rare micronodular adrenal hyperplasia. In Japan the incidence of ACTH-dependent Cushing's syndrome due to endogenous causes is about 60%, in which autonomous pituitary ACTH secretion is responsible for 95%, and the rest are ectopic ACTH-producing tumors. Cortisol-secreting tumors are responsible for about 40% of endogenous causes, in which benign adenoma is 90% and adrenocortical carcinoma is 10%. The first step for the diagnosis of Cushing's syndrome is to demonstrate the presence of hypercortisolism biochemically by determining 24-hour urinary free cortisol excretion and low-dose dexamethasone suppression test. The next step is to identify the precise etiologic causes. To differentiate Cushing's syndrome, the most important procedures are dynamic endocrine tests to check the integrity of hypothalamic-pituitary-adrenal function by high dose dexamethasone suppression test, CRH test arid measurement of steroid hormone profile. Imaging techniques can help to determine the etiology of Cushing's syndrome.

Adrenocorticotropic Hormone↗
PubMed2000

Stem cell factor and IL-6 do not promote complete maturation of human cultured mast cells from umbilical cord blood cells: an ultrastructural study.

Human mast cells are classified into two phenotypes based on their neutral protease compositions. One type is a tryptase-positive and chymase-positive MCTC cell that is predominant in the skin, another is a tryptase-positive and chymase-negative MCT cell that is predominant in the lung. Cord blood-derived human mast cells cultured in the presence of stem cell factor and interleukin-6 are a mixture of MCTC and MCT at various ratios, as revealed by immunocytochemical staining. We performed an electron microscopic analysis of cord blood-derived human cultured mast cells and found that they were so immature that we could not distinguish MCT and MCTC from their ultrastructural morphology. The response to secretagogues was not the response of MCTC but rather of MCT. Although human cultured mast cells are the most useful cells for use in in vitro experiments, the present culture condition supplemented with stem cell factor and interleukin-6 does not develop fully mature mast cells in vitro.

Cell Differentiation↗
PubMed2000

Mast cells in the cutaneous lesions of sarcoidosis: their subtypes and the relationship to systemic manifestations.

Possible involvement of mast cells in pulmonary sarcoidosis has been suggested, however whether mast cells are involved in cutaneous sarcoidosis remains unknown. We undertook a morphological study of mast cells in the lesional skin from 17 patients with cutaneous sarcoidosis using immunohistochemical methods. Mast cells were present in non-parenchymal fibrous areas, but not in granulomatous areas, in the biopsy specimens from the cutaneous lesions. However, there were no significant differences between the number of mast cells in the lesional skin and that in non-lesional skin from the patients. Mast cells containing substantial quantities of both tryptase and chymase (MC(TC) cells) were present in 41% of the patients, and cells containing tryptase but not chymase (MC(T) cells) were present in 59% of patients. All patients of the former group showed systemic manifestations of the disease concomitantly. Serum angiotensin I-converting enzyme levels were elevated in 71.4% of the former group, and in 30% of the latter group. This study for the first time demonstrated that mast cells were present in non-parenchymal fibrous areas of the cutaneous lesions of sarcoidosis, and the mast cell subtypes may be related to systemic manifestations.

Adult↗
PubMed2000

Cultured human mast cells derived from umbilical cord blood cells in the presence of stem cell factor and interleukin-6 cannot be a model of human skin mast cells: fluorescence microscopic analysis of intracellular calcium ion mobilization.

To know whether cultured human mast cells raised from umbilical cord blood cells in the presence of stem cell factor (SCF) and interleukin-6 (IL-6) can be a model of human skin mast cells, the cells were stimulated, and intracellular calcium ion ([Ca(2+)](i)) mobilization was analyzed by fluorescence microscopic techniques in parallel with a measurement of histamine released from the cells. When IgE-sensitized mast cells were activated by anti-IgE, [Ca(2+)](i) elevation began at the periphery and subsequently proceeded toward the center of the cells. The increase in [Ca(2+)](i) in calcium ionophore A23187-stimulated mast cells began at the center and spread to the periphery of the cells. Significant histamine release was observed by each stimulation. However, either compound 48/80 or substance P failed to increase [Ca(2+)](i) with no appreciable histamine release. This study shows that there is heterogeneity of [Ca(2+)](i) mobilization in the activated human mast cells, and that cultured human mast cells derived from umbilical cord blood cells in the presence of SCF and IL-6 can not be a model of human skin mast cells.

Antibodies, Anti-Idiotypic↗
PubMed2000

Suppressive effect of zinc ion on iNOS expression induced by interferon-gamma or tumor necrosis factor-alpha in murine keratinocytes.

Zinc, an essential metal, is a critical component of zinc binding proteins such as zinc fingers, zinc enzymes and metallothioneins. Recently, evidence for its anti-inflammatory property in skin has been accumulating, as shown in the treatment of acne, alopecia and zinc deficiency. In cutaneous inflammations, a large amount of nitric oxide (NO) is produced through induction of inducible nitric oxide synthase (iNOS) under the influence of proinflammatory cytokines, resulting in tissue damages in skin, as clarified in other organs. Therefore, we asked if the effect of zinc on NO production and/or on iNOS expression in keratinocytes may explain the anti-inflammatory property of zinc in skin. Accordingly, we sought to determine in this study whether zinc ion may have effect on IFN-gamma or TNF-alpha induced NO production and iNOS expression in cultured murine keratinocytes. Ten microM of zinc ion remarkably suppressed cytokine-induced NO production in keratinocytes. Furthermore, zinc ion also suppressed cytokine-induced iNOS expression in the protein level as well as in the messenger RNA level. These results suggest the possibility that the suppressive effect of zinc ion on cytokine-induced NO production in keratinocytes may be in part implicated in the anti-inflammatory property of zinc in some of skin disorders.

Animals↗
PubMed2000

The effect of ultraviolet B irradiation on nitric oxide synthase expression in murine keratinocytes.

Nitric oxide (NO), which has several physiological functions in skin, is generated by NO synthase (NOS). NOS has at least three isoforms; endothelial NOS (eNOS), brain NOS (bNOS), and inducible NOS (iNOS). Ultraviolet B (UVB) irradiation has been reported to stimulate NO production in skin via induction or activation of NOS, however, the exact mechanism of NOS induction by UVB irradiation remains obscure. In this study, we investigated the direct effect of UVB on the expression of NOS isoforms in murine keratinocytes, and found a significant increase in NO production within 48 h. mRNA and protein expressions of bNOS were both enhanced by UVB irradiation in murine keratinocytes, whereas iNOS mRNA expression was suppressed at 4 and 12 h after UVB irradiation. These results suggest that the enhancement of NO production observed after UVB irradiation in murine keratinocytes may be explained in part by the upregulation of bNOS expression, but not iNOS expression.

Animals↗
PubMed2000

Up-regulation of tyrosinase gene by nitric oxide in human melanocytes.

Ultraviolet light (UV) radiation causes skin-tanning, which is thought to be mediated by stimulating the release of melanogenic factors from keratinocytes as well as other cells. Nitric oxide (NO) has been reported to be generated after UV radiation and to stimulate melanocytes as one of the melanogens. In a previous experiment by another group on melanogenesis induced by NO, increases in both tyrosinase activity and tyrosinase protein levels were observed after daily stimulation of NO for 4 days. In the present study, we investigated tyrosinase gene expression within the first 24 hr of NO-induced melanogenesis. Tyrosinase mRNA expression was found to be induced 2 hr after a single treatment with S-nitroso-N-acetyl-L-arginine. An increase of tyrosinase activity was also detected time-dependently within the 24-hr period, accompanied by an increase of tyrosinase protein levels. The induction of mRNA expression was suppressed by a cyclic guanosine 3',5'-monophosphate (cGMP)-dependent protein kinase (cGMP/PKG) inhibitor. These results suggest that the enhancement of tyrosinase gene expression via the cGMP pathway may be a primary mechanism for NO-induced melanogenesis.

Alkaloids↗
PubMed2000

Involvement of nitric oxide in UVB-induced pigmentation in guinea pig skin.

Ultraviolet (UV) B irradiation evokes erythema and delayed pigmentation in skin, where a variety of toxic and modulating events are known to be involved. Nitric oxide (NO) is generated from L-arginine by NO synthases (NOS). Production of NO is enhanced in response to UVB-stimulation and has an important role in the development of erythema. NO has recently been demonstrated as a melanogen which stimulates melanocytes in vitro, however, no known in vivo data has been reported to support this finding. In this study, we investigated the contribution of NO with UV-induced pigmentation in an animal model using an NOS inhibitor. UVB-induced erythema in guinea pig skin was reduced when an NOS inhibitor, L-NAME (N-nitro-L-arginine methylester hydrochloride), was topically applied to the skin daily, beginning 3 days before UVB-irradiation. Delayed pigmentation and an increased number of DOPA-positive melanocytes in the skin were markedly suppressed by sequential daily treatment with L-NAME. Furthermore, melanin content 13 days after UVB-irradiation was significantly lower in skin treated with L-NAME than in the controls. In contrast, D-NAME (N-nitro-D-arginine methylester hydrochloride), an ineffective isomer of L-NAME, demonstrated no effect on these UV-induced skin responses. These results suggest that NO production may contribute to the regulation of UVB-induced pigmentation.

Animals↗
PubMed2000

Nerve growth factor prevents apoptosis of cord blood-derived human cultured mast cells synergistically with stem cell factor.

BACKGROUND: Stem cell factor (SCF) has been identified as a critical survival factor of human mast cells. Other cytokines which possess survival promotion activity on human mast cells are less known. OBJECTIVE: We examined the survival promotion activity of nerve growth factor (NGF) on cord blood-derived human cultured mast cells. METHODS: Expression and function of NGF receptors on the mast cells were examined by RT PCR, flowcytometric analysis, immunoprecipitaion and western blotting. The survival promotion activity of NGF to the mast cells was examined. To evaluate the proliferating activity of NGF on the human cultured mast cells, flow cytometric analysis with propidium iodide staining was applied. To confirm whether the human mast cell growth activity of NGF was caused by a suppression of apoptosis, the proportion of the cells containing in situ DNA fragmentation was counted. RESULTS: The human cultured mast cells expressed the high affinity receptor p140trk but not the low affinity receptor p75LNGFR. NGF induced the phosphorylation of p140trk. NGF alone could not support the survival of the mast cells, however, the addition of NGF to the culture medium containing recombinant SCF led to a significant increase of the number of survival mast cells. No significant changes of the cell cycle from G0/G1 phase to the S/G2 + M phases were observed by NGF. In contrast, the addition of NGF to the medium with SCF showed a significant inhibitory effect on the apoptosis of the mast cells. CONCLUSION: NGF may act as a key factor to promote the survival of human mast cells synergistically with SCF through the prevention of apoptosis.

Apoptosis↗
PubMed2000

Tufted angioma (angioblastoma): case report and review of 41 cases in the Japanese literature.

We report a 53-year-old man with a 2-year history of a violaceous indurated plaque on the shoulder. Although angiosarcoma was clinically suspected, histological examination revealed numerous lobules ('tufts') with cleft-like vascular lumina throughout the dermis and subcutaneous tissue. Tumour cells had no nuclear atypia and were positive for CD34, but almost negative for factor VIII-related antigen. These findings were compatible with a diagnosis of tufted angioma, or angioblastoma. We reviewed 41 cases reported in Japan and found that, although most patients presented during the first year of life (23/41), the condition does occur throughout childhood and adult life. Both sexes are affected equally and, contrary to some reports, it is unlikely that oestrogens have a pathogenic role.

Aged↗
PubMed2000

Effect of mast cell-derived mediators and mast cell-related neutral proteases on human dermal fibroblast proliferation and type I collagen production.

BACKGROUND: Possible involvement of mast cells in various fibrotic conditions has been suggested, but the relative contribution of each mast cell mediator and neutral protease to fibroproliferative activity remains to be elucidated. OBJECTIVE: We investigated the effect of mast cell-derived mediators and mast cell-related neutral proteases on type I collagen production and proliferation by human dermal fibroblasts. METHODS: Mast cell-derived mediators or neutral proteases were added to cultured fibroblasts from normal dermis, and cell proliferation and type I collagen synthesis were assayed. RESULTS: Fibroblast proliferation was increased by 2.8 x 10(-9) mol/L prostaglandin D(2) and 10 microgram/mL carboxypeptidase A, but not by leukotriene D(4) or cathepsin G at the concentrations studied. Proliferation was increased by tryptase in a concentration-dependent manner, and a significant increase was observed at concentrations of 1 and 10 microgram/mL. Production of type I collagen by fibroblasts was increased in the presence of 2.0 x 10(-9) mol/L leukotriene D(4) and 10 microgram/mL tryptase. CONCLUSION: Mast cell-derived mediators prostaglandin D(2) and leukotriene D(4) and mast cell-related neutral proteases carboxypeptidase A and tryptase increase the proliferation and type I collagen production of human dermal fibroblasts in various manners.

Cell Division↗
PubMed2000

Influence of IgE-mediated activation of cultured human mast cells on proliferation and type I collagen production by human dermal fibroblasts.

BACKGROUND: Mast cells have been suggested to be involved in fibrotic conditions, but it still remains unknown whether IgE-mediated activation of human mast cells promotes fibrogenesis by human fibroblasts. OBJECTIVE: The purpose of this study was to determine whether IgE-mediated activation of cultured human mast cells can promote fibrogenesis by cultured human dermal fibroblasts. METHODS: Mast cells derived from human umbilical cord blood cells were incubated with IgE and then activated by anti-IgE, and histamine release was measured. IgE-sensitized mast cells were cocultured with fibroblasts from normal dermis and activated with anti-IgE to induce histamine release, after which proliferation and type I collagen synthesis by the fibroblasts were determined. RESULTS: Coculture of subconfluent human dermal fibroblasts with IgE-sensitized mast cells did not affect fibroblast proliferation. However, fibroblast proliferation was increased by activated mast cells, and a significant increase was observed in the presence of 10(5) or 3 x 10(5) mast cells/mL. The promotion of fibroblast proliferation by mast cells (3 x 10(5)/mL) was partly inhibited by ketotifen at a concentration that significantly reduced histamine release from mast cells. On the other hand, IgE-mediated activation of mast cells did not increase type I collagen production by confluent human dermal fibroblasts. CONCLUSION: IgE-mediated activation of cultured human mast cells could increase the proliferation of human dermal fibroblasts, but did not promote type I collagen production by the fibroblasts under the conditions tested.

Cell Division↗
PubMed2000

Production of fibrogenic cytokines by cord blood-derived cultured human mast cells.

BACKGROUND: Mast cells are a potential source of cytokines, but their contribution to nonallergic inflammatory conditions, such as fibrosis, remains unclear. OBJECTIVE: We investigated whether cord blood-derived cultured human mast cells could produce fibrogenic cytokines by IgE-mediated activation. METHODS: Mast cells were obtained from human cord blood mononuclear cells by culture with stem cell factor and IL-6. The mast cells were incubated with human myeloma IgE and were activated with anti-IgE. The expression of messenger RNA for fibrogenic cytokines was examined by the reverse-transcription polymerase chain reaction, and cytokine protein was assayed by enzyme-linked immunosorbent assay, or bioassay. RESULTS: Cultured human mast cells constitutively expressed mRNA for transforming growth factor-beta(1), and its expression was not increased by anti-IgE stimulation. The cells released this factor into the culture medium spontaneously, which showed bioactivity after heat treatment. The mast cells also expressed mRNA for platelet-derived growth factor A, which was enhanced with a peak at 3 hours by stimulation with anti-IgE. Conditioned medium from nonactivated mast cells did not contain basic fibroblast growth factor, but this cytokine was released into the medium in a time-dependent manner after stimulation with anti-IgE. CONCLUSION: Human mast cells activated by IgE-mediated stimulation show production of fibrogenic cytokines that varies depending on the cytokine, which suggests possible involvement of mast cell cytokines in the development of fibrosis.

Cells, Cultured↗
PubMed2000

Disappearance of stress-induced hyperthermia following a low dose of X-irradiation: involvement of the vomeronasal system in the modulation of the radiation-induced effects.

When the rectal temperatures of group-housed mice are measured sequentially, the temperature of the last mouse to be measured is higher than that of the first mouse. The hyperthermia effect observed in the last animal to be measured forms the basis of an experimental paradigm for studying the neurobiology of anticipatory anxiety. Stress-induced hyperthermia (SIH) was calculated as the difference (delta T) between the basal temperature (the averages of the first three mice) and the final temperature (the averages of the last three mice) when the temperatures of the 15 mice were measured sequentially, with a 2 min interval between each temperature measurement. The hyperthermia observed in the last animals measured was abolished by prior treatment with X-irradiation at the relatively low dose of 5-15 cGy. Prevention of the SIH response could be found when the irradiation was confined to the head region only, suggesting the importance of the brain in the radiation-induced effect. Relatively higher doses of 25 or 35 cGy failed to reduce the hyperthermia stress effect. Furthermore, the effect of X-irradiation was not observed following olfactory bulbectomy or resection of the vomeronasal tract. These results indicate that the disappearance of SIH response may only be found following irradiation at low dose levels. Furthermore, the results implicate the olfactory system in the radiation-induced anti-stress effect.

Animals↗