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Biomedical subjects

Y Miyachi

Publications and source records attributed to Y Miyachi.

At least 19 recordsLinked to original sources
PubMed1995

Photoaging from an oxidative standpoint.

The free radical theory proposes that photoaging, which is both qualitatively and quantitatively different from chronological aging, may result from imperfect protection against cumulative stress of free radicals produced by chronic and repeated ultraviolet irradiation. Since the skin is always in contact with oxygen and is occasionally exposed to ultraviolet light, skin is one of the best target organs of environmental photo-oxidative stress. A growing body of evidence suggests that reactive oxygen species are generated by ultraviolet irradiation resulting in the structural and functional alteration of cutaneous components which should affect the photoaging process over a long period. The age-related alteration of cutaneous antioxidant defense capacity against cumulative effects of continual photo-oxidative stress to the skin may also affect the photoaging. Thus the possible use of antioxidants that attenuate photo-oxidative toxicity is believed to be an important strategy modulating photoaging. Several antioxidants have readily been proved to work in the experimental conditions. This paper reviews photoaging from a photo-oxidative standpoint and discusses the possible regulation of photoaging by antioxidants that is an important issue in the photodermatological field.

Animals↗
PubMed1995

Ulcerative colitis associated with preceding systemic lupus erythematosus.

We report a 50-year-old female patient who developed ulcerative colitis 31 after years being diagnosed with systemic lupus erythematosus. The overall clinical evaluation of her SLE activity differentiated ulcerative colitis from lupus colitis. Since the association of idiopathic systemic lupus erythematosus with ulcerative colitis has rarely been reported, the combination of these two diseases may be coincidental.

Adrenal Cortex Hormones↗
PubMed1995

Exacerbation of rheumatoid arthritis after removal of adrenal adenoma in Cushing's syndrome.

A 46-year-old woman with rheumatoid arthritis had been on non-steroidal antiinflammatory agents for eighteen years until she developed cushingoid features and hypertension resistant to antihypertensive drugs. She had high plasma cortisol and 24 h urinary 17-hydroxycorticosteroids (17HCS) which were not suppressed by 8 mg dexamethasone per day for two days. The circadian rhythm of plasma cortisol was absent and plasma ACTH concentrations were suppressed before and after intravenous administration of CRH. Abdominal computed tomography demonstrated a tumor (3.0 x 3.0 x 2.3 cm) in the right adrenal gland and a 131I-6 beta-19-nor-methylcholesterol scan revealed marked uptake on the same side. The patient underwent a right adrenalectomy and the diagnosis of a cortisol secreting benign adenoma was histologically confirmed. Blood pressure declined and cushingoid features regressed, but three months after the operation and while the patient was on replacement, she complained of pain on motion, marked tenderness and swelling of fingers, wrists, elbows, knees and foot joints, and had very high rheumatoid factors. Treatment with immunosuppressive drugs and oral and intraarticular administration of glucocorticoids were necessary to relieve the clinical symptoms of rheumatoid arthritis. In summary, we report a patient with rheumatoid arthritis and Cushing's syndrome due to an adrenal adenoma, in whom rheumatoid arthritis was exacerbated after curing the Cushing's syndrome. This suggests that it is imperative to follow the development and/or course of autoimmune diseases after the treatment of Cushing's syndrome.

17-Hydroxycorticosteroids↗
PubMed1995

[Competitive immunoassay and immunometric immunoassay].

Radioimmunoassays are simple and quite useful, being easily applied on a commercially serviceable basis. Furthermore radioimmunoassays are extremely sensitive and quite precise. Two site immunoradiometric assay in which one antibody was immobilized and another labelled with 125I becomes gradually popular, due to its higher sensitivity and the development of monoclonal antibody production by the hybridoma technique. Alternative analytical methods other than radioimmunoassays (radioimmunoassay, immunoradiometric assay) have been developed, in which the alternative labels to substitute for radioisotopes are enzymes, luminescent compounds and fluorescent probes.

Binding, Competitive↗
PubMed1994

Immediate arousal response and adaptation to low-dose x-rays in mouse and its disappearance by olfactory bulbectomy and nitric oxide inhibitor.

The effects of low-dose x-rays (4 cGy) on mouse brain were examined. EEG recording were made on sleeping mice before, during and after exposure. Exposure to x-rays induced the immediate change in EEG pattern from a low-frequency and high-amplitude (sleep) to a high-frequency and low-amplitude (arousal). Repeated exposure caused a decrease in number of mice showing arousal, suggesting that adaptation to x-ray stimuli was acquired by mice. In the olfactory bulbectomized mice, no arousal response could be noticed. When mice were injected with N-nitro-L-arginine or N-monomethyl-L-arginine, nitric oxide inhibitor, no decrease in the arousal mouse number occurred, even after the repeated exposure. These results indicate clearly that olfactory bulbs play an important role in immediate detection of x-rays and a possible involvement of NO in the adaptation to x-ray stimuli by mouse.

Adaptation, Physiological↗
PubMed1993

[Acromegaly].

Explore the source record for details and available documents.

Acromegaly↗
PubMed1992

Erythema multiforme: pathomechanism of papular erythema and target lesion.

Skin lesions of erythema multiforme show time-dependent changes from early papular erythema to the late target lesion which consists of a peripheral elevated erythematous area and a central depressed area. We investigated the pathomechanism of erythema multiforme, by examining the papular erythema and target lesion separately. In the early papular erythema, a small number of polymorphonuclear leukocytes and nuclear debris were seen intermingled with mononuclear cells around the slightly swollen blood vessels, on which immunoglobulin and complement components were deposited. Circulating immune complex levels were occasionally elevated. Sera from the patients generated high levels of reactive oxygen species and nitroblue tetrazolium test revealed positive reaction on the infiltrating cells around the blood vessels. These findings suggest that the papular erythema develops via incomplete type III allergic reaction, followed by damage through reactive oxygen species. In the target lesion, the activity of histamine-N-methyltransferase, which is the major histamine-degrading enzyme, was markedly decreased in the peripheral elevated erythematous area and it was recovering in the central clearing area. ICAM-1 and HLA-DR antigens were expressed on the surfaces of the keratinocytes. An increased number of epidermal Langerhans cells and CD4 cell infiltration were observed in the peripheral elevated erythematous area, while a decreased number of epidermal Langerhans cells and CD8 cell infiltration in the central depressed area were observed. These findings suggest that impaired histamine metabolism and cellular allergic reactions play important roles in the development of the target lesion.

Antigen-Antibody Complex↗
PubMed1992

Rapid decrease in brain enkephalin content after low-dose whole-body X-irradiation of the rat.

Methionine-enkephalin (ME) contents in the hypothalamus and other rat brain structures were measured immediately after 10 or 20 cGy whole-body X-irradiation. The ME contents of homogenates of the striatum, hypothalamus, midbrain + thalamus, hindbrain and pituitary were assayed radioimmunologically with 125I. The contents of all the structures, except the pituitary, decreased significantly after 20 cGy irradiation. The reduction in the hypothalamus was transient, ME content gradually recovering with time. These results suggest that the central nervous system of mammals is one of the most radiosensitive organs as judged by changes in stress-induced mediators such as ME.

Animals↗
PubMed1991

Inhibitory effect of azelaic acid on neutrophil functions: a possible cause for its efficacy in treating pathogenetically unrelated diseases.

It has been shown that acne, hyperpigmentation and lentigo malignant are more or less related pathogenetically to reactive oxygen species (ROS). It has recently been reported that azelaic acid is effective in treating these conditions and that it possesses anti-enzymatic and antimitochondrial activity, including cytochrome-P450 reductase and 5 alpha-reductase in microsomal preparations with nicotinamide adenine dinucleotide phosphate (NADPH). We therefore investigated the effects of azelaic acid on human neutrophil functions, such as chemotaxis, phagocytosis and ROS generation. ROS generation in a cell-free system was also assessed. The results revealed that neutrophil chemotaxis and phagocytosis as well as ROS generated in a xanthine-xanthine-oxidase system were not significantly changed in the presence of azelaic acid. However, azelaic acid markedly decreased O2- and OH. generated by neutrophils. It may be concluded that the reported clinical effectiveness of azelaic acid is partly due to its inhibitory action on neutrophil-generated ROS, leading to a reduction both in oxidative tissue injury at sites of inflammation and in melanin formation.

Chemotaxis↗
PubMed1991

A subpopulation of Langerhans cells (CD1a+Lag-) increased in the dermis of plaque lesions of mycosis fungoides.

The population of CD1a+ cells and the quantity of Birbeck granules were evaluated in comparison with the population of T lymphocytes in a variety of clinical lesions of mycosis fungoides. Anti-CD1a and Lag antibodies that specifically react with Birbeck granules and related structures of human Langerhans cells were used immunohistochemically. CD1a+ cells in the dermis of lesions of mycosis fungoides significantly increased in plaques of the plaque stage and in plaques of the tumor stage. They were most frequent in lesions with CD4+ cells ranging in number from 100 to 150/mm2. These lesions were suspected to be progressing from the plaque to the tumor stage. During the course of the disease, most of the dermal CD1a+ cells had few Lag antigens. These results suggest that dermal CD1a+Lag- cells may promote the progression of mycosis fungoides from the plaque to the tumor stage.

Antibodies, Monoclonal↗
PubMed1991

Immunohistochemical study of lepromin reaction in healthy adults.

Lepromin reaction was studied with immunoperoxidase techniques using monoclonal antibodies. The skin reactions were induced by injecting Mitsuda antigen into healthy adults without a family history of leprosy. Both early (48 hours) and late (3 weeks and 2 months) reactions were examined. In the late reaction, focal collections of epithelioid cells had formed, and not only T- but also B-lymphocytes were observed around the granuloma. CD1a+ cells were also confirmed to have increased in the late reaction.

Antigens, CD↗
PubMed1991

Why are natural plant medicinal products effective in some patients and not in others with the same disease?

We had previously found that the clinical efficacy of natural medicinal products was significantly enhanced by pretreatments of the natural compounds with far infrared radiation heating and brewing that effected degradation of high molecular polymers to yield free forms of low molecular monomers with anti-oxidant activity. The gastric samples from the patients were incubated with untreated or treated natural products, and the resulting materials assayed in vitro for the capacity to scavenge reactive oxygen species (ROS). The gastric fluid of patients who had responded to the untreated natural products showed a significantly greater scavenging ability than did the patients who had not responded to these agents. Similarly, the gastric fluid of patients who responded only to the treated, commercial products also showed a slightly greater scavenging ability than did those who failed to respond to any agent, treated or untreated. Acid and pepsin contents were demonstrated in largest amounts in the gastric juice from the patients who had responded well to the untreated natural medicines. Furthermore, the materials incubated with gastric fluid from the responding patients produced an increase in the free forms of alpha-tocopherol, beta-carotene, and flavoprotein as compared with the fluids of nonresponding patients. These findings suggest that one of the factors determining the clinical response to natural herbal medicinal products is the ability of the patient's digestive system to degrade the product to liberate bioactive low molecular compounds from repeating polymers.

Adult↗
PubMed1991

Salvage of distal flap necrosis by topical superoxide dismutase.

Significance of the reactive oxygen species in distal flap necrosis and the efficacy of superoxide dismutase (SOD) in salvaging necrosis have become indicated in recent studies. To enhance the therapeutic effect of SOD, topical application was designed. Water-soluble ointment containing 1% SOD was prepared, and three experiments were made to study the effect of topical SOD in improving flap survival. Simple application of SOD ointment to the upper surface of the flap had no effect, whereas its application to the under surface or occlusive dressing was effective. These effects were corroborated by assay of tissue SOD activity.

Administration, Topical↗