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K Oikawa

Publications and source records attributed to K Oikawa.

At least 19 recordsLinked to original sources
PubMed1992

Construction and characterization of a spectral probe mutant of troponin C: application to analyses of mutants with increased Ca2+ affinity.

A spectral probe mutant (F29W) of chicken skeletal muscle troponin C (TnC) has been prepared in which Phe-29 has been substituted by Trp. Residue 29 is at the COOH-terminal end of the A helix immediately adjacent to the Ca2+ binding loop of site I (residues 30-41) of the regulatory N domain. Since this protein is naturally devoid of Tyr and Trp, spectral features can be assigned unambiguously to the single Trp. The fluorescent quantum yield at 336 nm is increased almost 3-fold in going from the Ca(2+)-free state to the 4Ca2+ state with no change in the wavelength of maximum emission. Comparisons of the Ca2+ titration curves of the change in far-UV CD and fluorescence emission indicated that the latter was associated only with the binding of 2Ca2+ to the regulatory sites I and II. No change in fluorescence was detected by titration with Mg2+. The Ca(2+)-induced transitions of both the N and C domains were highly cooperative. Addition of Ca2+ also produced a red shift in the UV absorbance spectrum and a reduction in positive ellipticity as monitored by near-UV CD measurements. The fluorescent properties of F29W were applied to an investigation of five double mutants: F29W/V45T, F29W/M46Q, F29W/M48A, F29W/L49T, and F29W/M82Q. Ca2+ titration of their fluorescent emissions indicated in each case an increased Ca2+ affinity of their N domains. The magnitude of these changes and the decreased cooperativity observed between Ca2+ binding sites I and II for some of the mutants are discussed in terms of the environment of the mutated residues in the 2Ca2+ and modeled 4Ca2+ states.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Human apolipoprotein A-I liberated from high-density lipoprotein without denaturation.

Apolipoprotein A-I (apoA-I) was liberated from human high-density lipoprotein (HDL) without exposure to organic solvents or chaotropic salts by the action of isolated insect hemolymph lipid transfer particle (LTP). LTP-catalyzed lipid redistribution results in transformation of HDL into larger, less dense particles accompanied by an overall decrease in HDL particle surface area:core volume ratio, giving rise to an excess of amphiphilic surface components. Preferential dissociation of apolipoprotein versus phospholipid and unesterified cholesterol from the particle surface results in apolipoprotein recovery in the bottom fraction following ultracentrifugation at a density = 1.23 g/mL. ApoA-I was then isolated from other contaminating HDL apolipoproteins by incubation with additional HDL in the absence of LTP, whereupon apolipoprotein A-II and the C apolipoproteins reassociate with the HDL surface by displacement of apoA-I. After a second density gradient ultracentrifugation, electrophoretically pure apoA-I was obtained. Sedimentation equilibrium experiments revealed that apoA-I isolated via this method exhibits a tendency to self-associate in an aqueous solution while its circular dichroism spectrum was indicative of a significant amount of alpha-helix. Both measurements are consistent with that observed on material prepared by denaturation/renaturation. The ability of apoA-I to activate lecithin:cholesterol acyltransferase was found to be similar to that of apoA-I isolated by conventional methods. The present results illustrate that LTP-mediated alteration in lipoprotein particle surface area leads to dissociation of substantial amounts of surface active apoprotein components, thus providing the opportunity to isolate apoA-I without the denaturation/renaturation steps common to all previous isolation procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effect of particle lipid content on the structure of insect lipophorins.

Four distinct subspecies of the major insect lipoprotein, lipophorin, that range in overall lipid content from 20 to 51% of the particle mass, were isolated from the hemolymph or oocytes of the tobacco hornworm, Manduca sexta. Examination of these subspecies by electron microscopy revealed distinctive morphologies. Adult high density lipophorin (HDLp-A) was found to be an approximately spherical particle with a diameter of 15 +/- 1 nm, while HDLp-Wanderer 1 (W1), was more rectangular in shape and had a distinct cleft extending into the particle at one end. In the case of HDLp-Wanderer 2 (W2) the cleft was deeper and wider than that in HDLp-W1. In egg very high density lipophorin (VHDLp-E) the cleft was increased in size to the extent that the particle had an overall crescent-like conformation. Circular dichroism spectroscopy of the three lipophorin subspecies that contain only apolipophorin I and II revealed that only minor differences in the global protein secondary structure occur as the particle lipid content is decreased. The VHDLp-E apolipoproteins are an exception in that, while having the same alpha-helix content as HDLp-W1 and HDLp-W2, they contain less beta-structure and correspondingly more random coil. Limited digestion of the apolipoprotein components of the lipophorin subspecies with trypsin revealed that as the lipid content of the particles decreases the susceptibility of the apolipoprotein to proteolytic degradation increases. Likewise, tryptophan fluorescence quenching experiments demonstrated that the relative exposure of lipophorin apolipoprotein tryptophan residues also increases as the particle lipid content decreases.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Heme peptide as a model substance for halogenomethane activation and heme modification.

Octa-heme peptide (CHP) obtained from Candida krusei cytochrome c was tested for suicidal activation of halogenomethanes. Under anaerobic conditions, CHP was kept in the reduced state in the presence of NADPH and NADPH-cytochrome P-450 reductase. Addition of CBrCl3 to the reduced CHP caused spectral changes such as rapid disappearance of alpha and beta bands and gradual decrease in the gamma-peak height, accompanied by oxidation of NADPH. Heme content of the reaction mixture, determined as pyridine hemochrome, also decreased NADPH dependently. CCl4 was less effective than CBrCl3, while CHCl3 had almost no effect. N-tert-butyl-alpha-phenylnitrone (PBN) suppressed the CBrCl3-induced heme damage, and resulted in the formation of radical adduct .PBN-CCl3 as evidenced by ESR spectroscopy. Radical formation was also observed with CCl4. The CHP damage induced by CBrCl3 was also accompanied by the release of Br- about 11-12-times molar excess of CHP, whereas the release of CHCl3 was about 20% that of Br-.FD-MS assay of the product of CHP reaction suggested that 10 trichloromethyl radicals bonded with CHP. Thus, CBrCl3 undergoes single-electron reduction in the presence of reduced CHP to trichloromethyl radicals, which covalently bind to CHP molecules. Heme peptide may be a useful tool in the study of mechanisms involved in the destruction of cytochrome P-450 by halogenomethanes.

Amino Acid Sequence↗
PubMed1991

Determination of and corrections to sequences of turkey and chicken troponins-C. Effects of Thr-130 to Ile mutation on Ca2+ affinity.

Reported differences in the primary structures of chicken muscle troponin C (Wilkinson, J.M. (1976) FEBS Lett. 70, 254-256) and recombinant protein deduced from a chick muscle cDNA (Reinach, F.C. and Karlsson, R. (1988) J. Biol. Chem. 263, 2371-2376) have been reinvestigated. The complete amino acid sequence of turkey muscle troponin C has also been elucidated. Residue 100, originally reported as Asp in the chicken muscle protein, is shown to be Asn in all three structures. The three amino acid sequences are identical except as follows: 1) the blocked NH2-terminal Ala at residue 1 of the chicken protein is replaced by nonblocked Met-Ala in the recombinant protein and by nonblocked Pro in turkey troponin-C; 2) residue 130 is Thr in both avian muscle proteins but Ile in the recombinant protein; 3) Asp-133 in the chicken muscle and recombinant troponins-C is replaced by Glu in the turkey protein; 4) residue 99, originally identified as Glu in the x-ray structure of the turkey protein, is shown to be Ala in all three proteins. Calcium titration of the metal-induced conformational transition of the protein as monitored by far UV CD measurements indicated a significant decrease in Ca2+ affinity of the high-affinity sites in the case of the recombinant protein as compared with the chicken muscle protein. Both pairs of sites showed high cooperativity. That this decreased Ca2+ affinity could be attributed to different amino acid residues at position 130 and not to the differences at the NH2 termini was confirmed by site-specific mutation of Ile-130 to Thr in the recombinant protein. The mutated recombinant protein now titrated identically to the chicken muscle protein. Thr-130, whereas over 21 A from the metal of sites III and IV, is involved in a hydrogen bonding network with structured water and the NH2-terminal region of helix G.

Amino Acid Sequence↗
PubMed1991

[Anti-bacterial defense mechanisms of the urinary tract constructed from intestinal segments. Studies on cell population and phagocytotic activity of urinary leucocytes, and bacterial growth in urine].

Cell population of urinary leucocytes of 22 patients (intestine group) who underwent operations using intestinal segments for the urinary tract was compared with that of 26 complicated UTI patients without surgical intervention (control group). Eosinophils were recognized in 15.5 per cent of urinary leucocytes of the intestine group. However, in the control group, urine eosinophils were recognized only in 0.15 per cent. Although in sterile urines of the intestine group eosinophils were recognized in 30.8 per cent, in infected urines, the percentage of eosinophils decreased. Conversely, the percentage of neutrophils increased to 91.9 per cent. These findings suggest that neutrophils play an important role in infected urines of the intestine group as in urines of the control group. Significant differences were found in the values of urinary secretory IgA, IgG, IgM and urinary osmolarity. To evaluate the influence of these differences on the activity of phagocytosis of urinary leucocytes, the activity of phagocytosis of polymorphonuclear leucocytes (PMN), isolated from the peripheral blood, was investigated in immersion in urines of both groups. The mean rate of phagocytosis of E. coli in urines of both groups showed no statistically significant differences. However, urinary osmolarity of the intestine group was within the suitable range for phagocytosis and the activity of phagocytosis in urine was correlated with the value of IgG, which suggests that IgG has the opsonic effect. In contrast, the activity of phagocytosis in urine of the control group was strongly correlated with the value of urinary osmolarity. The growth of Providencia, Streptococcus, P. aeruginosa, whose frequency of isolation from urine of both groups was different in our previous study, and E. coli was studied in urine of the two groups. No significant difference in the growth of all bacteria was found, however. This finding suggests that the difference in the frequency of isolation of these bacteria from urine possibly depends on the adhesion of bacteria to intestinal epithelium.

Adolescent↗
PubMed1990

Placental site trophoblastic tumor: immunohistochemical and nuclear DNA study.

A rare case of placentae site trophoblastic tumor (PSTT) studied by immunohistochemistry and nuclear DNA analysis is reported. The patient, a 24-year-old Japanese female, complained of amenorrhea. Dilatation and curettage revealed a small specimen that contained trophoblastic cells and caused intractable bleeding. Pelvic sonography revealed a 5-cm mass in the posterior uterine wall with multiple cystic lesions of several sizes. The cystic lesions were shown to be dilated vessels by magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). Serum beta-hCG (beta subunit of human chorionic gonadotropin) was 3.7 ng/ml. Total abdominal hysterectomy revealed a well-circumscribed, yellow, soft mass in the posterior uterine wall. Microscopic findings were consistent with PSTT and the mitotic count was extremely low. Immunohistochemically, most of the tumor cells were intensely stained with human placental lactogen, whereas few were stained with human chorionic gonadotropin. The nuclear DNA content of the trophoblastic cells showed a sharp peak at the triploid range coexistent with a few cells of higher ploidy. This is the first report of sonographic findings and nuclear DNA analysis by spot cytometry in a case of PSTT.

Adult↗
PubMed1990

An adenocarcinoma in situ of the uterine cervix that developed into invasive adenocarcinoma after 5 years.

An extremely rare case of in situ adenocarcinoma of the uterine cervix that developed into invasive cancer is reported. The patient was a 54-year-old Japanese female who complained of vaginal spotting. Pelvic examination revealed no abnormalities and routine Papanicolaou smear was misinterpreted as negative. Multiple wedge biopsies of the uterine cervix were done because Papanicolaou smears taken after 7 months were reported as suspicious. The wedge biopsy revealed dysplastic changes of the endocervical glands. It was diagnosed as being in situ adenocarcinoma by a later review. The patient was examined by cytology and colposcopy every 3 to 12 months. An advanced adenocarcinoma was found in the uterine cervix after 5 years. Total abdominal hysterectomy, resection of the vagina and cardinal ligament, and postoperative irradiation were performed. The patient is alive and well at this writing. This is the second case of in situ adenocarcinoma of the uterine cervix that developed into invasive cancer.

Adenocarcinoma↗
PubMed1990

Functional degeneracy of residues in a T cell peptide epitope contributes to its recognition by different T cell hybridomas.

Synthetic antigen Poly EYK(EYA)5 induces T cells of narrowly defined fine specificity as represented by the two I-Ad-restricted T cell hybridomas, A.1.1 and B.1.1. Both these hybridomas recognize the minimum 15-amino-acid peptide sequence EYK(EYA)4. We have characterized the residues involved in the recognition of EYK(EYA)4 peptide by these hybridomas with synthetic peptides and discovered a distinct functional hierarchy for the residues in the sequence. Even with the repeating tripeptide (EYA)5, which is recognized by B.1.1 cells, the residues that are essential cluster near the middle of the sequence but not near the N- or C-terminal region. Different MHC binding and TCR contacting residues were found for each of the hybridomas. The results suggest that different T cells either recognize different parts of the peptide MHC complex or that the peptide binds to MHC in multiple conformations. This was supported by the fact that Poly EYK(EYA)5 is alpha-helical but the peptides used here showed only a slight propensity to adopt this structure and it did not correlate with their functional activity. We also found that (EYA)5 does not compete with EYK(EYA)4 in the stimulation of A.1.1 cells despite its obvious capacity to interact with I-Ad when it stimulates B.1.1 cells. This may be because these peptides have a low affinity for Ia and therefore only appropriate TCR interactions would stabilize the antigen-Ia complex. In conclusion, antigen-MHC-TCR interaction appears to be a dynamic process which allows recognition of different residues of a T cell determinant by different T cells.

Amino Acid Sequence↗
PubMed1990

[A study of dynamics of orthodontic archwire on the dental arch. 1. Distribution of orthodontic forces during labial movement of bilateral incisors].

The study on labial movement of maxillary unilateral incisor had been reported previously. This study was the case of maxillary bilateral incisors. Orthodontic forces during labial movement of maxillary bilateral incisors which were produced by stainless steel archwire with vertical loops and nickel titanium archwire, were measured and were examined the distribution of orthodontic forces to the dental arch in the experimental apparatus with strain gauges. The following results were found: 1. In nickel titanium archwire, orthodontic forces were distributed to the entire dental arch, and the distribution of orthodontic forces could be classified into three types, which were similar to the previous study. 2. In stainless steel archwire with vertical loops, orthodontic forces were distributed only to bilateral incisors and adjacent tooth to bilateral incisors. 3. When bilateral incisors displaced lingually, it showed that there were additional orthodontic forces distributions as if two unilateral distributions were overlapped. 4. For maxillary bilateral incisors were moved in optimum force, some consideration to adjust the loops of stainless steel archwire was needed.

Dental Stress Analysis↗
PubMed1990

[Clinical study concerning of latamoxef concentration in the obstructed urinary tract].

Urinary LMOX concentration was studied in 18 patients with unilateral ureteral obstruction. The concentration of LMOX in the urine from the mild obstructed kidney was 124 to 2,140 micrograms/ml and 10 micrograms/ml in the severely obstructed ones. The difference was probably due to the intensity and the duration of the obstruction. The patient with 99mTc-DMSA renal uptake of less than 3% also had a urinary LMOX concentration of less than 7 micrograms/ml. The above results seem to show that 7 micrograms/ml in urinary LMOX concentration is a significant figure for treatment of UTI. 99mTc-DMSA renal uptake and renal echogram were used to estimate the excretion rate of antibiotics into the urine.

Adolescent↗
PubMed1989

Studies on two siblings with recessive dystrophic epidermolysis bullosa (Hallopeau-Siemens) and the plasminogen activator and its inhibitor in the lesion.

Activities of plasminogen activators (PA) and their inhibitors were studied in the bullous lesions of 2 siblings with recessive dystrophic epidermolysis bullosa (RDEB). The hematological findings of the patients revealed hyperfibrinogenemia, hyper-gamma-globulinemia and marked thrombocytosis. The immunofluorescent studies showed strong deposits of plasminogen, fibrin-degenerative products and alpha 1-antitrypsin around the blister lesions. On the other hand, alpha 2-macroglobulin (alpha 2-M) was sparsely deposited. The levels of alpha 2-M in the blister fluid of the patients were also decreased in comparison with those from patients with other bullous dermatoses. The topical application of antibiotic ointment with strong PA inhibitor was clinically effective when applied to the blister and eroded lesions of the patients. These findings suggest that the increased activity of PA may play an important role in the development of blister formation in patients with RDEB.

Adolescent↗
PubMed1989

[Partial remission of pulmonary metastasis of malignant gonadal stromal tumor by salvage chemotherapy].

Fourteen malignant cases of gonadal stromal tumor were found among the cases reported in literature, but the roles of chemotherapy and radiotherapy have not been defined. We treated a malignant case and achieved 98.9 per-cent remission of lung metastases by salvage chemotherapy (cis-platinum + VP-16). A 34 year-old desk-worker, underwent left orchiectomy for testicular tumor on March 20, 1984. Histologic examination showed a malignant gonadal stromal tumor invading into the epididymis. Three course of adjuvant chemotherapy with cis-platinum, vinblastine, and peplomycin (PVP) were performed. However, chest X-ray films 13 months later revealed multiple lung metastases. Although 3 courses of combination chemotherapy with cyclophosphamide, adriamycin, vincristine, and prednisolone (CHOP) were given, no remission was obtained. However following 4 courses of combination chemotherapy with cis-platinum and VP-16, 98.9 per-cent remission of lung metastases was achieved. Subsequent bilateral residual lung tumors were resected. However, lung metastases recurred 3 months later, and the patient died on February 29, 1988. The autopsy revealed extensive lung, liver and pancreas metastases, but no lymph node metastases.

Adult↗
PubMed1989

[Evaluation of cytotoxicity of VLC Dycal in tissue culture for clinical use].

The purpose of this study was to evaluate the VLC Dycal (visible light cured composite-calcium hydroxide material) to see whether it is suitable or not as a direct or indirect pulp capping agent for clinical use by means of the cell culture test. Two light cured composite resins, P-30 and Silux, and also Dycal and Ca(OH)2 were used as a control for a comparative cytotoxicity test with VLC Dycal. All test materials were put into the glass tubes (4 mm diameter X 1 mm high), then illuminated for 10, 20, 30, 40, 50 and 60 seconds through a matrix strip with direct contact with a Prisma-light source (L.D. Caulk), just before testing. Fibroblasts, 5 ml of 1 X 10(5) cells per ml in Eagle's MEM medium with 10% FCS, penicillin (100 U/ml) and streptomycin (100 micrograms/ml) were evenly seeded on a cover glass in a tissue culture dish and incubated for 24 hours at 37 degrees C in a humidified atmosphere of a 5% CO2 in air. After 24 hours, the medium was replaced with 5 ml of agar overlay medium consisting of 10% FCS, Eagle's MEM medium and 1.5% agar. Glass tubes (n = 8) filled with the test materials were placed at the center of the agar, and incubated for 24 hours in 5% CO2 in air at 37 degrees C. After 24 hours of incubation, the cover glass was removed and the cells were fixed in 10% neutral formalin and then stained by H.E. to differentiate the areas of affected and unaffected cells beneath the test specimens. The affected area was quantitatively determined using an image analysis system.(ABSTRACT TRUNCATED AT 250 WORDS)

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

[Clinical effectiveness of arterial infusion chemotherapy in advanced and recurrent gastric cancer].

Arterial infusion therapy was applied to 77 patients with 18 unresectable, 29 non-curatively resected and 20 recurrent gastric cancers. 5-fluorouracil (5-FU) was administered by arterial continuous infusion, and adriamycin (ADM) and mitomycin C (MMC) by bolus infusion. The clinical effectiveness of each was evaluated. One-year cumulative survival rate of primary case by Kaplan-Meier method was 19.2%, and that of recurrent gastric cancer was 5.3%. Median survival time of primary case was 6.5 months, showing prolongation compared with recurrent ones. Also, in primary cases, the arterial infusion therapy was more effective in non-curatively resected cases than in unresectable ones. Two of the patients are now alive and another is apparently free of tumor and the remaining one had a recurrence. Continuous arterial 5-FU infusion and ADM low-dose intermittent bolus infusion chemotherapy (AF therapy) were considered an effective supportive treatment without any serious side effects for unresectable, noncuratively resected and recurrent gastric cancer.

Adult↗
PubMed1988

Purification and characterization of beta-N-acetylhexosaminidase I from human placenta.

beta-N-Acetylhexosaminidase (hexosaminidase) I, which has an intermediate charge character between those of hexosaminidases A(alpha beta 2) and B[beta beta)2), was purified 1,500-fold from human placenta by procedures including chromatographies on concanavalin A (Con A)-Sepharose and an immunoadsorbent column. The isolated hexosaminidase I was heat-stable, and antigenically cross-reactive to anti-beta chain-IgG but not to anti-alpha chain-IgG. The results of substrate specificity experiments using 3H-labeled natural substrates indicated that the hexosaminidase I hydrolyzed Gb4Cer to Gb3Cer but not GM2 to GM3. The tryptic peptide map of the hexosaminidase I was similar to that of hexosaminidase B, though some differences were observed. The hexosaminidase I after treatment with neuraminidase or endo-beta-N-acetylglucosaminidase H was partly converted to less acidic forms. Treatment of the hexosaminidase I with acid phosphatase did not change the charge character. Therefore hexosaminidase I is an acidic variant form of hexosaminidase B, possibly resulting from sialylation and the presence of phosphodiester bonds at the carbohydrate moiety.

Cross Reactions↗