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Biomedical subjects

A Kawada

Publications and source records attributed to A Kawada.

At least 55 records · Page 3Linked to original sources
PubMed1999

In vitro phototoxicity of new quinolones: production of active oxygen species and photosensitized lipid peroxidation.

To elucidate photosensitization potentials of new quinolone antibacterial agents, production of active oxygen species and peroxidation of squalene after ultraviolet A exposure were investigated. Production of singlet oxygen and/or hydrogen peroxide was estimated by bleaching of p-nitroso-N,N-dimethylaniline. Lomefloxacin showed the greatest ability to produce active oxygen species, and this ability was reduced by the addition of the singlet oxygen quencher sodium azide. Ciprofloxacin and fleroxacin also had strong activity. Photosensitized peroxidation of squalene was evaluated by measurement of thiobarbituric acid-reactive substances. Lomefloxacin was the strongest sensitizer, followed by fleroxacin and ciprofloxacin. These results suggest that certain new quinolones are involved in phototoxicity via the mechanism of active oxygen species.

Anti-Infective Agents↗
PubMed1999

Leopard syndrome associated with hyperelastic skin: analysis of collagen metabolism in cultured skin fibroblasts.

We present a patient with Leopard syndrome and hyperelastic skin. Biochemical analysis using cultured skin fibroblasts showed normal type III and V collagen synthesis, lysyl hydroxylation level of type I procollagen and processing of pro-alpha(1) and alpha(2)(I). Our results suggest that molecular defects of hyperelasticity in Leopard syndrome are not related to abnormal collagen metabolism, although not all steps of collagen synthesis have been investigated.

Abnormalities, Multiple↗
PubMed1999

Development of a highly sensitive enzyme immunoassay for human calcitonin using solid phase coupled with multiple antibodies.

We have developed a highly sensitive chemiluminescent enzyme immunoassay for human calcitonin using three different mouse monoclonal antibodies that recognize the N-terminal, C-terminal and central portions of a human calcitonin molecule. The assay signal in a two-step sandwich enzyme immunoassay for human calcitonin using a solid phase coupled with a mixture of monoclonal antibodies. CT08 and OCT1, was 3.7-fold higher than when using either or both solid phases coupled with CT08 or OCT1, respectively. This enhancement is the result of improved avidity of immobilized antibodies and greater stability of the complex of immobilized antibodies and calcitonin in the first reaction, which resulted in greater reactivity of the immunocomplex with alkaline phosphatase-conjugate in the second reaction. The present assay showed a linear response up to 2.5 micrograms/L of human calcitonin and a high specificity for human calcitonin, but not for rat calcitonin, human calcitonin gene-related peptide and rat calcitonin gene-related peptide. The detection limit of human calcitonin was estimated to be 0.29 ng/L at zero (assay blank) + 3 SD. Interbatch coefficients of variation ranged from 2.2-26.7%.

Animals↗
PubMed1998

In vitro degradation of tropoelastin by reactive oxygen species.

The effects of reactive oxygen species (ROS) on elastin molecules (tropoelastin) were studied in vitro. ROS generated by ultraviolet A and hematoporphyrin rapidly degraded tropoelastin within 5 min. Their degradative activity was inhibited by the addition of NaN3. Treatment of tropoelastin with copper sulfate/ascorbic acid resulted in degradation of tropoelastin producing fragments of molecular weight 45, 30 and 10 kDa within 30 min. The degradation of tropoelastin was partially blocked by the addition of mannitol. ROS induced by the xanthine/xanthine oxidase system also degraded tropoelastin within 6 h. The degradation was blocked by catalase but not by superoxide dismutase (SOD). ROS generated by copper-ascorbate seems to be unique in that it cleaves relatively specific sites of the tropoelastin molecule. Thus ROS may play a degradative role in elastin metabolism which may cause the elastolytic changes or the deposition of fragmented elastic fibers in photoaged skin or age-related elastolytic disorders.

Ascorbic Acid↗
PubMed1998

A pediatric case of atypical Mycobacterium avium infection of the skin.

We report a case of cutaneous atypical mycobacteriosis in a 12-year-old healthy girl due to Mycobacterium avium. The cutaneous symptoms were three well-defined subcutaneous nodules on both buttocks and on the posterior surface of the left thigh. One had a fistulous opening on the skin surface. Histopathological examination revealed epithelioid cell granulomas surrounded by dense lymphocytic infiltration and acid-fast bacteria were seen with modified periodic acid-carbol fuchsin staining. Using Ogawa's medium at 37 degrees C, acid-fast bacteria were isolated from the biopsied specimen and identified by the DNA-DNA hybridization method as Mycobacterium avium. In drug susceptibility test, these were resistant to all antituberculous drugs. Oral administration of minocycline 100 mg/day for two months had little effect on the two remaining lesions, which were therefore excised. Based upon reported cases of Mycobacterium avium complex, we considered that our pediatric patient with multiple intradermal or subcutaneous nodules on the buttocks and the thigh exhibited the characteristic symptoms of M. avium infection.

Administration, Oral↗
PubMed1998

Characteristics of UVA-induced delayed tanning: seasonal variation.

We studied seasonal variation in UVA-induced delayed tanning and compared it to that in UVA + B-induced delayed tanning. The minimal tanning dose (MTD) and the minimal melanogenic dose (MMD) were determined one week after UVA exposure or UVA + B exposure, respectively. The MTD determined in the summer (June to August) was significantly higher than that in winter (December to February). In addition, while MTD in the winter correlated well with skin color, there was no correlation between MTD and skin color in summer. MTD tended to correlate with self-reported tanning history at the initiation of tanning in the winter, but they were not correlated with each other in the summer. The MMD measured in the summer was significantly lower than that in the winter. MMD correlated well with skin color in both seasons; the lighter the skin, the smaller the MMD. Also, a correlation was detected between MMD and self-reported tanning history. These results suggest that the susceptibilities of delayed tanning to UVA and UVA + B are affected by different factors.

Adult↗
PubMed1998

Cathepsin D expression in skin metastasis of breast cancer.

Cathepsin D, an aspartic proteinase, correlates with invasion and metastasis in breast cancer and with poor prognosis. In the present study, we examined the immunohistological expression of cathepsin D in both primary (5 cases) and skin-metastatic breast cancers (13 cases) and compared it to those in gastric (2 cases) and lung (4 cases), and primary eccrine cancers (3 cases). All breast and gastric cancers were adenocarcinomas. The 2 gastric cancers were poorly differentiated, while the 4 lung cancers consisted of 2 poorly differentiated adenocarcinomas, 1 poorly differentiated large cell carcinoma, and 1 moderately to poorly differentiated squamous cell carcinoma. We also surveyed the immunohistological distribution of cathepsin B, carcinoembryonic antigen, gross cystic disease fluid protein-15, c-erbB-2, and estrogen receptor. In almost all breast cancer samples, the cancer cells demonstrated strong expression of cathepsin D in the cytoplasm, but weak staining patterns with other antibodies. Gastric and lung cancer cells did not respond with cathepsin D (except one metastatic lung cancer) or the other immunohistological markers. Since cathepsin D is strongly expressed in primary and metastatic lesions of breast cancer, cathepsin D could be useful as an adjunct to a panel of immunohistochemical stains in determining the primary site of origin of metastatic cancer in the skin.

Adenocarcinoma↗
PubMed1998

Diabetic pigmented spots on the extrapretibial region: immunohistochemical study of type IV collagen in dermal vessel wall.

A case of diabetes mellitus associated with multiple pigment spots is reported. The patient had multiple pigmented atrophic patches on the abdominal area and thighs. There were no pigmented spots on the pretibial area. Histologically, dermal vessels showed intimal thickening and deposition of periodic acid-Schiff (PAS)-positive fibrillar material in vessel walls. Clinical and histological features indicated that these pigment spots were diabetic pigmented pretibial patches occurring in the extrapretibial area. Immunohistochemical studies of lesional and non-lesional skin using the antibodies for alpha1-alpha6 chains of type IV collagen revealed that PAS-positive material of vessel walls in both lesional and non-lesional skin was stained with alpha1 and alpha2 chain antibodies but not with alpha3-alpha6 chain antibodies, indicating that alpha1 and alpha2 chains of type IV collagen, which are normal components of the dermal vessel basement membrane, accumulate in the vessel walls in diabetes mellitus.

Abdomen↗
PubMed1997

Stimulation of human keratinocyte growth by alginate oligosaccharides, a possible co-factor for epidermal growth factor in cell culture.

Oligosaccharides, involved in regulation of plant developmental and defensive processes, were tested to determine their ability to enhance proliferation of human keratinocytes. A mixture of alginate oligosaccharides remarkably stimulated keratinocyte growth and [3H]thymidine uptake in the presence of epidermal growth factor (EGF). The activity was comparable to bovine pituitary extract, a common complement in keratinocyte culture, and additive on BPE-induced stimulation. The most effective oligosaccharide in the mixture was identified and its chemical structure was determined. These findings demonstrate a novel activity of alginate oligosaccharide(s) in keratinocyte growth and suggest a possible co-factor for EGF-dependent stimulation in medium for keratinocytes.

Alginates↗
PubMed1997

Processing of cathepsins L, B and D in psoriatic epidermis.

Proteinase activity is increased in psoriatic epidermis. To elucidate the involvement of enzymes in psoriatic epidermis, the expression of cathepsins, L, B and D was investigated by Western blotting and immunohistological studies. Normal epidermis contained abundant inactive precursors (39 kDa) of cathepsins L and B and an inactive intermediate form (45 kDa) of cathepsin D. Cathepsin L in psoriasis was processed to a variable extent from the precursor to a single-chain form (30 kDa) and a mixture of single- and heavy-chain (25 kDa) forms of the active mature enzyme, corresponding to the immunohistological staining patterns 'diffuse dense', 'small granular', and unevenly distributed 'condensed granular'. Cathepsin B showed a mixture of precursor form (39 kDa) and single-chain (30 kDa) forms and was expressed as a 'diffuse dense' staining pattern in the mid-spinous layer and as a 'condensed' pattern in the upper spinous and granular layers. Cathepsin D was processed to the heavy-chain (31 kDa) form of activated mature enzyme with small granular staining and a mixture of heavy-chain and degraded protein (28 kDa) with larger and more condensed granular staining. The distribution patterns of 'small granular' cathepsin L, and of cathepsins B and D expression in suprabasal keratinocytes were very similar to that of involucrin. After complete clinical resolution of psoriasis by 8-methoxypsoralen plus UVA treatment, the expression of the three cathepsins was normalized. These results suggest that cathepsins L, B and D in forms activated to a variable extent may be involved in the pathology of psoriasis.

Adolescent↗