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Biomedical subjects

K Ikai

Publications and source records attributed to K Ikai.

At least 55 records · Page 3Linked to original sources
PubMed1989

Changes of the activities of enzymes involved in prostaglandin synthesis in rat skin during development and aging.

The developmental changes of enzymes involved in prostaglandin (PG) synthesis were investigated in rat skin from birth to 1.5 years old. In all stages of development, the activities of PG-synthesizing enzymes were found in 100,000 x g supernatants of homogenates of rat skin, and PGD2 was the major PG among those formed from PGH2 in the presence of 1 m zeta glutathione (GSH). The PGD synthetase activity in rat skin at birth was 2.14 nmol/min per mg protein, increasing to the highest level (3.69 nmol/min per mg protein) at 3 weeks after birth and then gradually decreasing up to 1.5 years old. The activities of PGE2 and PGF2 alpha synthetases in rat skin were almost unchanged during development and aging. In contrast, the activity of GSH-S-transferase was at its lowest level at birth and gradually increased, reaching a plateau at 3 weeks after birth and remaining relatively constant during the development. The increase of PGD synthetase activity in 3-week-old rats was mainly due to the increase of specific activity of PGD synthetase in the epidermis, which was separated from the dermis by heat treatment (55 degrees C, 30 s). Immunohistochemical study, using (rat spleen PGD synthetase)-specific antibody, revealed that the number of immunopositive cells, which were identified as Langerhans cells, increased in the epidermis in 3-week-old rats. These results suggest that a change of PGD2 synthetase activity during aging of the skin is closely related to the development of ATPase+ Langerhans cells in the epidermis.

Aging↗
PubMed1989

Effects of 1 alpha,25-dihydroxyvitamin D3 on the transglutaminase activity of transformed mouse epidermal cells in culture.

Induction of the transglutaminase activity of a transformed mouse epidermal cell line (PAM 212 cells) by 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2-D3), the active form of vitamin D3, was investigated. Addition of 1 alpha,25-(OH)2-D3 to a culture medium stimulated twice the transglutaminase activity at a concentration of 10(-7) M, but vitamin D3, prostaglandin E1, E2, and F2 alpha failed to show this induction. Phorbol 12-o-tetradecanoylphorbol-13-acetate (TPA) and dexamethasone also induced an increase in transglutaminase activity. Exposure to both 1 alpha,25-(OH)2-D3 and retinoic acid caused remarkably synergistic effects on the induction of transglutaminase in the PAM 212 cells. In contrast, simultaneous addition of 1 alpha,25-(OH)2-D3 and TPA was antagonistic and resulted in less than additive induction. Vitamin D3 also showed a similar but lesser effect. These results suggest that 1 alpha,25-(OH)2-D3 induces the transglutaminase activity via mechanisms disparate from those of retinoic acid and modifies epidermal differentiation.

Animals↗
PubMed1989

Effect of ultraviolet irradiation on the activity of rat skin prostaglandin D synthetase.

The effect of ultraviolet light-B (UVB) irradiation on the activity of prostaglandin (PG) D synthetase was investigated in adult rat skin. Rats were irradiated with 500 mJ/cm2 of UVB, and PGD synthetase activity was determined in 100,000 g supernatant of the homogenate of rat skin in the presence of glutathione (GSH) before and 3, 6, 12, and 24 h after irradiation. The PGD synthetase activity was decreased time dependently, and within 24 h after UVB irradiation it had dropped to 50% of the control level before irradiation. In contrast, the synthesizing activities of PGE2 and PGF2 alpha were unaffected by UVB irradiation. The reduction of PGD synthetase activity after UVB irradiation was much more prominent in the epidermis than in the dermis, which was separated by heat treatment (55 degrees C, 30 sec). Immunohistochemical studies, using anti-(rat spleen PGD synthetase) antibody, revealed that the number of immunopositive cells, which were identified as Langerhans cells, decreased in the basal layer of the epidermis 24 h after UVB irradiation. These results, together with the reduction of ATPase positive cells in the epidermis after UVB irradiation, suggest that the decrease of PGD synthetase activity in rat skin by UVB irradiation is, at least in part, due to the reduced Langerhans cell population in the basal layer of the epidermis.

Adenosine Triphosphatases↗
PubMed1988

Prostaglandin D2 formation and characterization of its synthetases in various tissues of adult rats.

When the amounts of primary prostaglandins formed from endogenous arachidonic acid were determined in homogenates of various tissues of adult rats, prostaglandin D2 was the major prostaglandin found in most tissues. It was formed actively in the spleen (3100 ng/g tissue/5 min at 25 degrees C), intestine (2600), bone marrow (2400), lung (1100), and stomach (630); moderately in the epididymis, skin, thymus, and brain (140-340); and weakly in other tissues (less than 100). Addition of exogenous arachidonic acid (1 mM) accelerated the formation of prostaglandin D2 in all tissues as follows: spleen (15,000); bone marrow, intestine, thymus, liver, and lung (1600-5200); stomach, adrenal gland, epididymis, brain, salivary gland, skin, spinal cord, and seminal vesicle (380-1000); and other tissues (80-310). The activity of prostaglandin D synthetase (prostaglandin-H2 D-isomerase) was detected in 100,000g supernatants of almost all tissues. As judged by glutathione requirement for the reaction, inhibition of the activity by 1-chloro-2,4-dinitrobenzene, and immunotitration or immunoabsorption analyses with specific antibodies, the enzyme in the epididymis, brain, and spinal cord (1.8-9.2 nmol/min/mg protein) was glutathione-independent prostaglandin D synthetase (Y. Urade, N. Fujimoto, and O. Hayaishi (1985) J. Biol. Chem. 260, 12410-12415). The enzyme in the spleen, thymus, bone marrow, intestine, skin, and stomach (2.0-57.1) was glutathione-requiring prostaglandin D synthetase (Y. Urade, N. Fujimoto, M. Ujihara, and O. Hayaishi (1987) J. Biol. Chem. 262, 3820-3825). The activity in the kidney and testis (3.7-4.5) was catalyzed by glutathione S-transferase. The activity in the liver, lung, adrenal gland, salivary gland, heart, pancreas, and muscle (0.6-5.1) was due to both the glutathione-requiring synthetase and the transferase.

Animals↗
PubMed1988

Letterer-Siwe disease: immunopathologic study with a new monoclonal antibody.

Three cases of Letterer-Siwe disease were studied with the monoclonal antibody Lag, which reacts to the antigen on the membranes of Birbeck granules and related structures of human Langerhans cells. Both lymph nodes and lesional skin contained abundant Lag-positive cells. By two-dimensional gel electrophoresis, antigenic substances in the lymph nodes of patients with Letterer-Siwe disease were found to have the same molecular weight of 40,000 dalton and isoelectric points extending from 4.7 to 6.5 as those in normal human skin and lymph nodes. Our results support the contention that Letterer-Siwe disease is a proliferative disorder of Langerhans cells. A double-staining method with Lag and anti-T6 antibody revealed that Lag reacted to 70% of T6-positive cells in the lymph nodes but to almost all such cells in skin lesions of patients with Letterer-Siwe disease, suggesting that the proliferating cells consist of at least Lag+, T6+, and Lag-, T6+ subpopulations.

Antibodies, Monoclonal↗
PubMed1988

Phaeohyphomycosis caused by Phialophora richardsiae.

A case of phaeohyphomycosis caused by Phialophora richardsiae is presented. The patient was a 30-year-old man with end stage malignant lymphoma. A subcutaneous abscess that developed on the dorsum of the right foot was removed surgically but immediately recurred. The causative mold was isolated from the pus in the lesion and identified as P. richardsiae. This is the fifth known case of phaeohyphomycosis caused by P. richardsiae and the first recorded in Japan.

Adult↗
PubMed1988

Effects of substance P and substance K on the growth of cultured keratinocytes.

The effects of substance P and substance K, which are coexpressed in the same mRNA as a beta-preprotachykinin in peripheral tissues and released in the inflammatory lesion of the skin, were examined on epidermal proliferation using spontaneously transformed mouse epidermal cell line (Pam 212 cells). Substance P stimulated the synthesis of DNA of Pam 212 cells in the medium containing 2%-10% fetal calf serum (FCS). Stimulation of DNA synthesis was dose dependent if the cells were cultured in the medium containing 2% FCS (quiescent condition). This effect was inhibited by spantide. In a serum-free medium, substance P had no effect on keratinocyte proliferation. In contrast, substance K, which shares a common amino acid sequence with substance P on its C-terminal, did not affect DNA synthesis of Pam 212 cells in either medium condition. Substance P released in inflammation may stimulate epidermal proliferation.

Animals↗
PubMed1988

Characterization and distribution of prostaglandin D synthetase in rat skin.

The biochemical properties and immunohistochemical localization of prostaglandin D synthetase were investigated in adult rat skin. The activity of prostaglandin D synthetase, which isomerizes prostaglandin H2 to prostaglandin D2, was detected in the 100,000 g supernatant of the homogenate of adult rat skin. Whole skin showed considerable activity (1.9 nmol/min/mg protein), and prostaglandin D2 was the major prostaglandin among those formed from prostaglandin H2 in the presence of glutathione. The epidermis, which was separated from whole skin by heating (55 degrees C, 30 s), exhibited about three times higher activity (3.5) than the dermis (1.0). The enzymatic properties of both layers were similar; they were absolutely glutathione-dependent, were inhibited only a few percent by 1 mM 1-chloro-2,4-dinitro-benzene, and were completely absorbed by anti-rat spleen prostaglandin D synthetase antibody. Immunohistochemical studies, using anti-rat spleen prostaglandin D synthetase antibody and the immunoperoxidase method, showed that prostaglandin D synthetase was localized in Langerhans cells (not in keratinocytes) in the epidermis, in macrophages or histiocytes, and also in mast cells in the dermis. Immunoelectron microscopy also supported these findings. These results suggest that prostaglandin D2 is one of the most important arachidonic acid metabolites and plays a significant role in immunological function in the skin via Langerhans cells and macrophages.

Animals↗
PubMed1988

Hidrotic ectodermal dysplasia: a clinical and ultrastructural observation.

Hidrotic ectodermal dysplasia (HED) was observed in a 49-year-old Japanese man. His clinical signs included alopecia, dystrophic nails and palmoplantar keratoderma, but his teeth, facial appearance and sweating were normal. In his family, 9 members in 5 generations were affected, suggesting that the disorder has an autosomal dominant mode of inheritance. Biopsy specimens of the hyperkeratotic lesions of the palm and sole were studied with an electron microscope. The most prominent feature was the increase of the number of desmosomal discs in the thickened stratum corneum, suggesting that hyperkeratosis observed in HED is due to the delayed desquamation of the stratum corneum.

Ectodermal Dysplasia↗
PubMed1987

Latent and clinically manifest prostatic carcinoma.

In a histological study of 17 prostates excised in toto for stages B and C primary carcinoma, we found one focus of well differentiated carcinoma in each of six prostates, which, in addition to these foci, had large tumors of invasive prostatic carcinoma. In four of the six prostates, the foci were located near but separate from the main tumor, and in the remaining two they were invaded by the main tumor. These findings strongly suggest that prostatic carcinoma is multifocal in origin and that focal well differentiated carcinomas are different in biological behavior from invasive poorly differentiated carcinomas.

Aged↗
PubMed1987

Inhibition of the proliferation of transformed epidermal cells in culture by various prostaglandins.

Cytotoxic action of various prostaglandins (PGs) was examined on the PAM 212 transformed mouse epidermal cell line, and delta 7-PGA1 was found most active. delta 7-PGA1 exerted a dose-dependent inhibition of PAM 212 cell growth over 0.1 microgram/ml (0.3 microM). At 1.6 microgram/ml (4.6 microM) growth was completely inhibited, and the number of viable cells decreased remarkably during culture. The concentration needed for 50% growth inhibition (IC50) value of delta 7-PGA1 on PAM 212 cell growth was calculated as 0.4 microgram/ml (1.1 microM). At this concentration, the DNA synthesis in 24- and 48-h cultured cells was decreased to a half of the level in the control cells, and microscopically, remaining cells showed degenerative changes with many vacuoles in their cytoplasm. Prostaglandin D2, a major PG in mast cells, also showed potent cytotoxic activity. However, this action was expressed as 9-deoxy-delta 9,12-13,14-dihydro-PGD2 (delta 12-PGJ2), which was converted from PGD2 in plasma, and had a 3-fold stronger growth inhibitory activity than PGD2; the IC50 values of PGD2 and delta 12-PGJ2 were 2 micrograms/ml (5.7 microM) and 0.75 microgram/ml (2.1 microM), respectively. Among other PGs tested, PGA2 showed a comparable growth inhibitory activity, and PGB2, PGE1, and PGE2 less but significant activity. Prostaglandin F2 alpha and PGI2 however, had no such effect on cell proliferation at 5 micrograms/ml (14.3 microM) concentration, suggesting that cyclopentenone structure is an essential moiety of PG derivatives for cell growth inhibition. This cytotoxic action of delta 7-PGA1 and delta 12-PGJ2 appears to be independent of cyclic-AMP, since these PGs were virtually inactive in raising intracellular cyclic-AMP levels in PAM 212 cells.

Animals↗
PubMed1987

Synthesis and antitumor activity of spergualin analogues. III. Novel method for synthesis of optically active 15-deoxyspergualin and 15-deoxy-11-O-methylspergualin.

Optically active 15-deoxyspergualin (II) and 15-deoxy-11-O-methylspergualin (IIa) were synthesized, and their antitumor activities were examined. The (-)-enantiomers of both II and IIa were active against mouse leukemia L1210, while the (+)-enantiomers were almost inactive. The optical resolution of the key intermediate, (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycine (VI) was achieved by use of an exopeptidase, serine (acid) carboxypeptidase [EC 3.4.16.1] and (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycyl-L-amino acid (VIII) as the substrate. Considering the enzymatic susceptibility of the substrate (VIII), we deduced that the absolute configuration of the carbon at 11 (C-11) of the bioactive (-)-enantiomer, and so that of natural spergualin (I), is S. This is, to our knowledge, the first report of the use of carboxypeptidase for the resolution of N-acyl amino acid.

Animals↗