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Biomedical subjects

S Kurata

Publications and source records attributed to S Kurata.

At least 55 records · Page 3Linked to original sources
PubMed1997

Regeneration of Sarcophaga imaginal discs in vitro: implication of 20-hydroxyecdysone.

When the 3/4 sectors of leg imaginal discs of Sarcophaga were cultured in vitro in the presence of 2.5 x 10(-8) M 20-hydroxyecdysone, wound healing and restoration of their morphology occurred. This concentration of ecdysone was critical for wound healing and was 40 times lower than that necessary for inducing differentiation of imaginal discs in vitro. Lost positional values revealed by expression of the wingless gene were found to show partial recovery under these conditions. These results suggest that a low titer of ecdysone is essential for the regeneration of imaginal discs.

Amino Acid Sequence↗
PubMed1997

Molecular cloning of cDNA for Sarcophaga prolyl endopeptidase and characterization of the recombinant enzyme produced by an E. coli expression system.

A cDNA for prolyl endopeptidase (PEP) of Sarcophaga peregrina (flesh fly) was cloned and its sequence determined. The overall amino acid sequence identity between Sarcophaga and mammalian PEPs was 53%, indicating that these enzymes are structurally very similar. Northern blot hybridization revealed that the Sarcophaga PEP gene was activated significantly at the eversion stage of imaginal disc differentiation. We obtained recombinant PEP by expressing the cDNA in Escherichia coli. The recombinant and authentic enzymes showed almost identical characteristics, in terms of substrate specificities and sensitivities to inhibitors.

Amino Acid Sequence↗
PubMed1997

Nuclear localization and involvement in DNA synthesis of Sarcophaga prolyl endopeptidase.

A specific prolyl endopeptidase (PEP) inhibitor, ZTTA, selectively inhibited DNA synthesis by imaginal discs and cultured embryonic cells of Sarcophaga peregrina (flesh fly). PEP was found to be localized in restricted nuclear regions. Unfertilized eggs were shown to contain a maternal message for PEP and analysis of Sarcophaga embryos at blastdermal stage revealed PEP was localized exclusively in the nuclei. These results suggest that PEP participates in DNA synthesis by, and therefore cell proliferation, of insect cells. This is the first demonstration of a biological function of PEP.

Animals↗
PubMed1997

Perineural and neural involvement in skin cancers.

BACKGROUND: Malignant skin tumors rarely spread along nerves. Complete resection of involved nerves is often unsuccessful. OBJECTIVE: In the treatment of tumors with perineural invasion, surgeons should accurately estimate the extent of distant spread. METHODS: We report six cases of skin cancers, including two basal cell carcinomas, two squamous cell carcinomas, and two neurotropic malignant melanomas, that invaded nerve or perineural spaces. RESULTS: In three of the cases, the tumors developed on the face and involved the infraorbital nerves or its branches. Two patients suffered from tumors on old burn scars of lower legs. Branches of posttibal nerves were involved in both cases. In the last case, tumor invasion of a branch of the greater occipital nerve was detected. CONCLUSION: The extent of surgical excision should include the area of skin supplied by the affected nerve, which must be resected in continuity.

Adult↗
PubMed1997

Basic study of a new denture base resin applying hydrophobic methacrylate monomer.

To improve the water sorption of poly(methyl methacrylate), new hydrophobic monomers, such as norbonyl and phenyl methacrylate, were studied to determine the resin with lower water sorption with no decrease in mechanical property. Water sorption of the copolymers of the hydrophobic monomers and MMA decreased with the increase in the concentration of the monomers. Compressive and bending strength of the copolymers were higher than that of PMMA, and the elastic modulus in bending was the same as that of PMMA. In addition, the transverse-deflection values satisfied ADA specifications. Dynamic mechanical thermal analysis of the copolymers showed a similar tendency to that of PMMA in spite of the introduction of bulky groups, such as norbonyl and phenyl, in the polymer molecule. The polymerization shrinkage in volume was in the following order: norbonyl < phenyl < methyl methacrylate.

Compressive Strength↗
PubMed1997

Extended V-Y flap: patient reports and reconsideration.

The extended V-Y flap, a modified V-Y advancement flap, is very useful in closing relatively large defects on the face. Its extension limb is hinged down as a transposition flap on the end of the V-Y advancement flap to close the most distal portion of the defect. We applied this flap in closing a defect following excision of skin tumors on the face with excellent cosmetic results in 11 patients. However, this flap tended to make a distortion at the base of the flap in the primary closure site. By drawing figures, we concluded that the distortion was due to the characteristic of this technique as a V-Y advancement-rotation flap or V-Y advancement flap with rotation.

Aged↗
PubMed1996

Transcriptional control of the heme oxygenase gene in mouse M1 cells during their TPA-induced differentiation into macrophages.

It has long been known that heme oxygenase (HO) is a key enzyme in heme catabolism and recently it was also found to acts as an oxidative stress protein to produce carbon monoxide (CO), which has similar actions to those of nitrogen monoxide (NO). Therefore, we examined transcriptional control of the HO gene in mouse M1 (myeloleukemia) cells during their differentiation into macrophages. Since the promoter region of this gene is known to have a TPA-responsive element (TRE), its expression might be regulated by a C-kinase signal transduction pathway. Then we investigated the activation of the HO gene after treatment of M1 cells with TPA and inhibitors of C-kinase. When M1 cells were treated with TPA, they differentiated into macrophage-like cells. Upon treatment with TPA, H2O2 was produced first, the nuclear proto-oncogenes fos and jun were activated, and then the HO gene was activated. The extent of transcriptional activation of the fos, jun, and HO genes in M1 cells treated with TPA was reduced by a specific inhibitor of C-kinase and a scavenger of oxygen radicals. When M1 cells were treated with H2O2, essentially the same level of transcription of the HO gene was observed, but the extent of transcriptional activation of the fos and jun genes was about half of the treatment with TPA. Super-shift assays using the TRE of the HO gene revealed that the Fos and Jun proteins from nuclei of M1 cells treated with TPA bound to the TRE, and same assays using DNA with the NF-kappa B motif also revealed that the active NF-kappa B protein from M1 cells treated with H2O2 or TPA also bound to the corresponding motif. These results strongly suggest that the HO gene in M1 cells is activated by TPA through a production of H2O2, an oxidative activation pathway of NF-kappa B, and a signal-transduction pathway that involves C-kinase during the differentiation of macrophages that occurs upon treatment with TPA.

Acetylcysteine↗
PubMed1996

Purification, characterization, and cDNA cloning of a galactose-specific C-type lectin from Drosophila melanogaster.

We purified a lectin from a pupal extract of Drosophila melanogaster. This lectin agglutinated trypsinized and glutaraldehyde-fixed bovine red blood cells in the presence of calcium or magnesium. The hapten sugar of this lectin was galactose. The molecular mass of the intact lectin was determined to be 41 kDa, and it comprised 14- and 17-kDa subunits. The 17-kDa subunit was shown to be a glycosylated form of the 14-kDa subunit. Analysis of the cDNA for this lectin revealed that the 14-kDa subunit consists of 163 amino acid residues and contains all residues conserved in various C-type lectins. It was suggested that the Drosophila lectin and Sarcophaga lectin share some properties and function similarly in defense and development, but probably they are not structural homologues.

Amino Acid Sequence↗
PubMed1996

Lipopolysaccharide activates transcription of the heme oxygenase gene in mouse M1 cells through oxidative activation of nuclear factor kappa B.

It has been known for a long time that heme oxygenase (HO) is a key enzyme in heme catabolism, and it was found to act as an oxidative-stress protein to produce carbon monoxide, which has similar actions to those of nitrogen monoxide. We examined transcriptional control of the HO gene in mouse M1 (myeloleukemia) cells during treatment with lipopolysaccharide (LPS; an oxidative reagent). Since the promoter region of this gene in human cells contains a 12-O-tetradecanoyl- phorbol-13-acetate(TPA)-responsive element (TRE) and a nuclear-factor-kappa B-responsive element. HO mRNA expression might be regulated by an oxidative activation pathway. We investigated activation of the HO gene after treatment of M1 cells with LPS. Upon treatment with LPS, H2O2 was produced, the nuclear proto-oncogenes fos and jun were activated, then the HO gene was activated. The extent of transcriptional activation of the fos, jun and HO genes in M1 cells treated with LPS was strongly reduced by a scavenger of oxygen radicals (N-acetyl-L-cysteine), but a specific inhibitor of protein kinase C only reduced transcriptional activation by 10-20%. These results suggest that LPS may be an oxidative reagent. Some oxidative reagents (e.g., H2O2) are strong activators of NF-kappa B, and therefore we treated M1 cells with H2O2. Essentially the same extends of transcriptional activation of the fos, jun and HO genes were observed as those observed after LPS treatment. Super-shift assays with DNA that contained the TRE motif revealed that the Fos and Jun proteins from nuclei of M1 cells treated with LPS and H2O2 bound weakly to the TRE motif, and, in assays with DNA that contained the NF-kappa B motif, nuclear protein from M1 cells treated with H2O2 or LPS bound strongly to the NF-kappa B motif. These results strongly suggest that the HO gene in M1 cells is mainly activated by LPS through oxidative activation of NF-kappa B due to production of H2O2.

Animals↗
PubMed1996

Purification and characterization of N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine, a novel antibacterial substance of Sarcophaga peregrina (flesh fly).

We purified a novel antibacterial substance from immunized adult Sarcophaga and determined its molecular structure to be N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD). We synthesized 5-S-GAD enzymatically from N-beta-alanyl-3, 4-dihydroxyphenylalanine (beta-Ala-Dopa) and reduced glutathione (GSH). The antibacterial activity of 5-S-GAD was found to be due to its production of H2O2. This is a novel antibacterial mechanism as it differs from the mechanisms of known antibacterial peptides. Two possible roles of 5-S-GAD in insect immunity, suppression of bacterial growth and activation of a Rel family transcription factor, are proposed.

Animals↗
PubMed1996

Concomitant transcriptional activation of nitric oxide synthase and heme oxygenase genes during nitric oxide-mediated macrophage cytostasis.

During in vitro activation of mouse peritoneal macrophages with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS), their synthesis of peroxynitrite and their cytostatic activity against mouse lymphocytic leukemia (L1210) cells were examined. The activation of the genes for nitric oxide synthase (iNOS) and heme oxygenase (HO-1) was also determined during the activation of the macrophages. Results showed that activation of peroxynitrite synthesis in macrophages was accompanied by the transcriptional activation of iNOS and HO-1 genes. Both genes seem to be activated simultaneously upon activation of the macrophages. Simultaneous activation of iNOS and HO-1 genes may be important because degradation of heme by HO-1 is one of the most important reaction that produces CO in higher organisms, and nitric oxide (NO) and carbon monoxide (CO) can react with heme-containing guanylate cyclase.

Animals↗
PubMed1996

Cloning and sequencing of mouse complementary DNA for heme oxygenase-2.

A mouse cDNA encoding a human homologue of heme oxygenase-2 (HO-2) was isolated. The deduced protein contains 315 amino acids and has a calculated molecular mass of 35.8 kDa. The nucleotide sequence is 85.6% identical and the amino acid sequence 87% identical to those of the human protein. The corresponding mRNA is present in brain and testis, but not in ovary, kidney, liver, or spleen.

Amino Acid Sequence↗
PubMed1996

Selective interaction of synthetic antimicrobial peptides derived from sapecin B with lipid bilayers.

By measuring carboxyfluorescein leakage from liposomes and the increase in membrane current through planar lipid bilayer membranes, we examined the capacities of a series of low-molecular-weight cationic amphiphilic peptides derived from the alpha-helix domain of sapecin B for membrane-perturbation and ion-channel formation. Some of these peptides strongly interact with membranes containing acidic phospholipids and phosphatidylethanolamine, with a very negative potential, which are characteristic of the Escherichia coli membrane, in parallel with their antimicrobial activity. In contrast, they do not interact with membranes which predominantly contain choline phospholipids and cholesterol in their outer leaflets, with a slightly negative potential, all of which are characteristic of eukaryotic membranes, thereby providing a molecular basis for their selective toxicity. Membranes doped with these peptides are as permeable to inorganic phosphates as to chloride ions and are far more permeable to cations. The loss of inorganic phosphates may damage bacterial cells due to rapid depletion of cytoplasmic ATP. Examination of the structure-activity relationships of a series of derived peptides in their interaction with a model of the E. coli membrane confirmed the necessity of cationic amphiphilicity for the peptides to attack the bacterial membrane and to exhibit antimicrobial activity.

Adenosine Triphosphate↗
PubMed1996

Free composite graft for lip reconstruction after tumor excision.

This paper represents 10 patients for whom lip defects following excision of malignant tumors were reconstructed by the free composite graft technique using the opposite side of the lip. Usually, for upper lip reconstruction, a switch flap or Zisser-Madden method is commonly used. For lower lip reconstruction, the methods of the double cross-lip flaps or the rotation flap are most frequently used. However, we recommend the free composite graft technique for selective patients, since this method is simpler than the other techniques and the results are excellent both cosmetically and functionally.

Aged↗
PubMed1996

Lymphoepithelioma-like carcinoma of the skin.

Lymphoepithelioma-like carcinoma of the skin is a rare tumor with a microscopic resemblance to lymphoepitheliomatous tumors of the nasopharynx. A 62-year-old woman exhibited such a tumor on the nose together with regional lymph node metastases. Histologically, irregular islands of atypical epithelial cells unconnected to the overlying epidermis were surrounded by or mixed with numerous lymphocytes in the primary tumor. No squamous or glandular differentiation was present. Metastases to the submandibular lymph nodes appeared as glassy squamous cells that resembled trichilemmal keratinization. Staining of the tumor tissues with S-100 protein antibody revealed the presence of numerous short dendritic cells in clusters of epithelial cells. Total resection and adjunctive radiotherapy have led to a 6-year period free of recurrence. This is the second case report of this condition in Japan.

Carcinoma, Squamous Cell↗
PubMed1996

Frontonasal flap for reconstruction of complete alar defects.

BACKGROUND: It is difficult to reconstruct a satisfactory ala. Axial frontonasal flap has been common in reconstruction of nasal tip. We modified this flap to reconstruct nasal ala. OBJECTIVE: A modified axial frontonasal flap was applied for reconstruction of complete unilateral alar defects in two patients. METHODS: Skin from an intact nasal tip covered the alar defect. The resulting defect in the nasal tip was covered with dorsal skin from the nose. Extended mucosa or a hinged nasolabial flap was used to line the mucosal side of the reconstructed ala. RESULTS: The outcome judged by shape, and texture, was satisfactory. This technique can be employed under field block. CONCLUSION: The modified frontonasal flap is one of the ideal techniques to reconstruct an entire nasal ala.

Aged↗