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T Kigawa

Publications and source records attributed to T Kigawa.

At least 37 records · Page 2Linked to original sources
PubMed1995

Synthesis of N-acetylglucosaminyl asparagine-substituted puromycin analogues.

As part of our project aimed to introduce specifically glycosylated amino acids into proteins, new glycosylated puromycin analogues were chemically synthesized. Introduction of a free N-acetylglucosaminyl asparaginyl side chain abolished the activity of puromycin completely, but when the sugar OH groups were rendered increasingly hydrophobic by acetylation or benzylation, up to 8% of the activity was recovered. The results of our preliminary inhibition tests suggest that the interaction of puromycin analogues and therefore also of glycosylated aminoacyl tRNA, with the ribosomal A site increase with hydrophobicity of the modifying protecting groups.

Acetylglucosamine↗
PubMed1994

Receptor-binding affinities of human epidermal growth factor variants having unnatural amino acid residues in position 23.

Ile-23 of human epidermal growth factor (hEGF) has been indicated, by mutagenesis and NMR studies, to be directly recognized by the receptor. In the present study, an unnatural phenylalanine analog, either 2-azaphenylalanine (2aF), 3-azaphenylalanine (3aF), 4-azaphenylalanine (4aF), or 4-fluorophenylalanine (4fF), was incorporated by an in vivo protein synthesis system into position 23 of [Phe23]hEGF, which retains appreciable receptor-binding affinity (about 20% of the wild type). We compared the receptor-binding affinities of the variants with that of [Phe23]hEGF and found that substitution of Phe-23 with 2aF or 3aF raised the affinity, while substitution with 4aF or 4fF remarkably reduced the affinity. The tertiary structure of [Phe23]hEGF was not significantly affected by the substitution of Phe-23 with 2aF, as shown by the two-dimensional nuclear magnetic resonance analysis. In addition, the substitution of residue 23 with His or Tyr produced an hEGF variant with a slightly higher receptor-binding affinity than that of [Phe23]hEGF. Our results suggest that the receptor has an asymmetric hydrophobic pocket for recognition of the side chain in position 23 of hEGF. Furthermore, on the receptor surface, this pocket seems to be adjacent to a less hydrophobic region with a hydrogen-bond acceptor and donor. Thus, the use of unnatural amino acids in addition to the 20 natural ones allows analyses of the structure-function relationship of a protein at a higher resolution than conventional site-directed substitution by only natural amino acid residues.

Amino Acids↗
PubMed1991

A continuous cell-free protein synthesis system for coupled transcription-translation.

A continuous cell-free protein synthesis system [Spirin et al. (1988) Science 242, 1162-1164] was modified so as to be suitable for coupled transcription-translation, a process useful for obtaining products of cloned genes or cDNAs. A reaction chamber equipped with an ultrafiltration membrane was newly designed and an HPLC pump was used to supply a low molecular weight substrate solution at a constant rate to the viscous reaction mixture in the chamber. By using an Escherichia coli S30 extract in this modified flow system (1 ml), coupled transcription-translation could be continuously performed for 17 h, the synthesized chloramphenicol acetyltransferase (congruent to 0.1 mg) being subsequently eluted through the chamber's membrane and then purified.

Cell-Free System↗
PubMed1989

Non-steroidal low molecular substance from porcine follicular fluid inhibits aromatase activity.

To clarify the underlying mechanism of the inhibitory control of the non-steroidal substance from porcine follicular fluid on estradiol secretion by granulosa cells, the suppression of aromatase activity was studied in vitro. Follicular fluid from porcine small follicles was filtered through an Amicon PM-10 membrane and a filtrate with a molecular weight of less than 10,000 was obtained. The filtrate was eluted on a Sephadex G-25 column (1.5 x 70 cm) using 0.01N CH3COOH, pH 4.0 as the elution buffer. The fraction containing the first peak of peptide (Fraction A) was used for subsequent experiments. Human placental microsomal fraction was used for the aromatase source. Aromatase activity was examined by counting the radio-activity of 3H2O converted from (1 beta, 2 beta 3H)-testosterone. The conversion of 3H2O from (1 beta, 2 beta 3H)-testosterone by rat's granulosa cells cultured in serum-free medium was also examined. Fraction A significantly suppressed aromatase activity of placental microsomal fraction by 57% at 120 min, and by 38% at 180 min, in dose and time-dependent manners. The aromatase activity of cultured rat granulosa cells was also inhibited by Fraction A in a dose-dependent manner. These results demonstrate the presence of a low molecular non-steroidal substance in the follicular fluid which is capable of inhibiting aromatase activity. This substance could provide important insights into the regulatory mechanism of differentiated functions of granulosa cells.

Animals↗
PubMed1988

Immunohistochemical and immunoelectron microscopic study of an amylase-producing, CA19-9 positive ovarian mucinous cystadenocarcinoma.

A 75-year-old woman with a right ovarian tumor revealed high levels of serum amylase and CA19-9 which decreased to within normal limits after the operation. A histopathological study of surgically excised tumor tissue revealed a mucinous cystadenocarcinoma. The tumor was composed of three elements: adenoma, adenoma with low potential malignancy, and adenocarcinoma. Using the light microscopic indirect immunoperoxidase technique for amylase and CEA, and the Avidin-Biotin affinity technique for CA19-9 and CA12-5, the amylase and CA19-9 were stained in the cytoplasm of the adenoma and adenocarcinoma although CEA was stained only in the cytoplasm of the adenocarcinoma. An ultrastructural study using the immunoperoxidase method revealed that CA19-9 was positive in the apical portion of the tumor cells and amylase was positive in the entire secretory vesicles of the tumor cells. Furthermore, ciliated tumor cells derived from fallopian tube epithelium were not observed in the light and electron microscopic specimens.

Aged↗
PubMed1987

Vascular pattern of the mammalian ovary with special reference to the three-dimensional architecture of the spiral artery.

Casts of blood vessels in the ovaries of the female rat, pig and monkey were made with methacrylate, dissected out under a dissecting microscope and observed in a scanning electron microscope (SEM). The ovarian arteries and their branches were characterized by the presence of a spiral configuration. The spiral course of the arteries, however, varied greatly in detail among the different species. The arteries in the pig and monkey ovaries had tightly spiraling configurations, while there was only an image suggestive of a spiral in the rat ovarian arteries. The former species showed a rich plexus of the spiral arteries in the hilus and medulla of the organ. Their branches straightened at the transitional region between the medulla and cortex but again showed spiral configurations in the cortex. Further, the arterial branches supplying the growing and mature follicles showed a much more marked extent to the spiral configurations as compared with those of the corpus luteum. In this paper morphological findings shall be discussed in correlation with their physiological implications.

Animals↗
PubMed1987

[Clinical evaluation of the prolactin secreting capacity for the diagnosis of occult hyperprolactinemia].

To clarify the diagnostic criteria of occulted or transient hyperprolactinemia, the resting prolactin level and the prolactin secreting capacity of normal women, which were tested with a 500 micrograms of TRH injection, were compared with those of patients with occulted hyperprolactinemia. Results revealed that: resting levels of prolactin in normal women were 13.4 +/- 4.4 ng/ml (mean +/- S.D.) in the follicular phase and 13.4 +/- 5.6 ng/ml in the luteal phase, which overlapped those of occulted hyperprolactinemia. the prolactin secreting capacity of occulted hyperprolactinemia was significantly greater than that of the normal women. These results indicated that it was impossible to distinguish the occulted hyperprolactinemia from the normal by the measuring the resting prolactin level, but possible by the evaluating the prolactin secreting capacity. If the serum prolactin was more than 150 ng/ml at 15 min. after TRH administration, occulted hyperprolactinemia was strongly suggested.

Circadian Rhythm↗
PubMed1987

[Semi-quantitative evaluation of the intrapartum variable deceleration of the FHR pattern and its association with umbilical cord blood gas analysis].

Variable daceleration of FHR combined with no other abnormal pattern was semi-quantitatively evaluated to establish the diagnostic value of variable deceleration for fetal distress. FHR charts of 55 low risk vaginal deliveries by direct monitoring were analysed and the SDA (Sum of Dip Area) was calculated using the following equation: SDA = sigma Duration of dip (sec.) X Amplitude of dip (bpm.) X 10(-2) and correlation between SDA and umbilical cord blood gas analysis was obtained. A significant correlation was observed between SDA during labor (from 5 cm cervical dilation to delivery) and cord blood gas data. pHuv:r = -0.445 (p less than 0.005), PO2uv:r = -0.358 (p less than 0.01), BEuv:r = -0.538 (p less than 0.001), pHua:r = -0.441 (p less than 0.005), BEua:r = -0.463 (p less than 0.001). In 14 cases which showed prolonged deceleration (PD:more than 120 sec. in duration and below 100 bpm. in dip), excellent correlation was observed between the SDA of PD and pHuv:pHuv = 7.425-7.74 X 10(-4) SDA of PD (r = -0.756, p less than 0.005), whereas in 21 cases with severe variable deceleration (SVD:more than 60 sec. and recovered within 120 sec. in duration or below 60 bpm. in dip) no significant correlation was seen between the SDA of SVD and pHuv. These results suggest that the SDA value is helpful in evaluating variable deceleration during labor.

Female↗
PubMed1987

Effects of sitting position on uterine activity during labor.

To determine which components of uterine activity are affected by different positions of labor, 116 intrauterine pressure records in the sitting and supine positions were analyzed in order to measure resting, contraction, and bearing down pressures. The resting pressure in the sitting position showed consistent elevation compared to the supine position, while the contraction pressure did not differ strikingly in the two positions. The bearing down pressure in the sitting position for nulliparas during the second stage and for multiparas at the time of the 8- to 10-cm dilation was significantly higher than that in the supine position. Also, the sitting position led to a significantly shorter duration of the second stage in nulliparas and the 5- to 10-cm dilation period in multiparas. These findings suggest that the maternal position does not affect uterine contractility, that the increased resting pressure in the sitting position is of some importance in supplementing the downward delivery force, and that the increased bearing down pressure in the sitting position could help to significantly shorten the duration of labor.

Female↗
PubMed1986

[Inhibitory effect of prolactin secretion by luteinizing hormone releasing hormone agonist (buserelin)].

The LH RH agonist Buserelin was continuously administered through the nose over an extended period to 5 patients with endometriosis at daily doses ranging between 300 micrograms and 1,200 micrograms. The clinical findings and endocrinological dynamics, with emphasis on PRL secretion function, were investigated and the findings below were obtained. The clinical findings showed Buserelin to be effective against endometriosis. The administration of Buserelin markedly inhibited the secretion of LH and FSH under LH-RH loading. The administration of Buserelin markedly inhibited the secretion of PRL and the degree of inhibition appeared to be dependent on the dose and duration of Buserelin administration. No correlation between E2 and PRL was observed during Buserelin administration. The findings suggest that Buserelin inhibits PRL secretion by direct CNS activity, not indirectly through inhibition of E2 production.

Administration, Intranasal↗
PubMed1986

Inhibitory effects of the porcine follicular fluid on estradiol and progesterone secretion by cultured rat granulosa cells.

The effect of porcine follicular fluid on estradiol and progesterone secretion was examined using a rat granulosa cell culture with FSH and testosterone in the medium. Follicular fluids from small (less than 5 mm) and large (greater than 6 mm) follicles (SFFI, LFF1) were treated with charcoal, and then fractionated by filtration through an Amicon XM-50 and an PM-10 membrane. The addition of 25% SFF1 and LFF1 into the culture system significantly inhibited estradiol and progesterone secretion (P less than 0.005). These inhibitory activities were observed in PM-10 retentates (10,000-50,000 MW) and filtrates (less than 10,000 MW) of SFF1 and LFF1. The addition of XM-50 filtrates (less than 50,000 MW) of SFF1 and LFF1 caused a dose-dependent inhibition of estradiol and progesterone secretion. The dose-response relationship between the filtrates and estradiol secretion was linear with a significant correlation coefficient. The addition of the filtrates exerted no inhibitory effect on the growth of the cells cultured. XM-50 filtrate of LFF1 from a batch with a low ratio of small/large follicles showed a lower inhibitory activity on estradiol secretion than that of LFF1, while the inhibitory activities in both filtrates on progesterone secretion were almost equivalent. These results suggest that the follicular fluid of small porcine follicle contains nonsteroidal regulators capable of inhibiting estradiol and progesterone secretion by cultured rat granulosa cells, and that the estradiol secretion inhibitor activity decreases in the fluid of large follicle while the progesterone secretion inhibitor activity does not decrease in it.

Animals↗
PubMed1986

Inhibitory activity of a low molecular weight substance extracted from porcine small follicular fluid on estradiol and progesterone secretions by rat granulosa cells in vitro and by rat ovaries in vivo.

Follicular fluid from small porcine follicles was filtrated through an Amicon XM-50 membrane to obtain a filtrate less than 50,000 MW. The filtrate was eluted through a Sephadex G-25 column (1.5 X 70 cm) using 0.01 N CH3COOH, pH 4.0, as elution buffer, and divided to five fractions. To test the inhibitory activity of these fractions on the in vitro estradiol and progesterone secretion, each fraction was added into a rat granulosa cell culture with FSH and testosterone in the medium. Two of five fractions exerted a significant inhibitory activity on the estradiol and progesterone secretions by the granulosa cells. They were in a range of low molecular weight fractions (MW 1,000-3,000) on the elution profile. Whether the in vitro active fractions are capable of inhibiting the in vivo estradiol and progesterone secretions by the ovary was assessed using the hypophysectomized DES-treated immature rat with hMG stimulation and the testosterone-treated immature rat with PMSG stimulation. The administration of the fractions to the former animal significantly suppressed the increases due to gonadotropin in the ovarian and serum estradiol concentrations. The administration of the fractions to the latter animal significantly suppressed the increases due to gonadotropin in the estradiol and progesterone concentrations of the ovary and serum. These results suggest that a low molecular weight substance from porcine small follicular fluid is capable of inhibiting the estradiol and progesterone biosyntheses in the follicle of the rat ovary.

Animals↗
PubMed1986

[Immunosuppressive factor(s) present in crude preparations of human chorionic gonadotropin].

The present study was undertaken to purify and characterize the immunosuppressive factor(s) present in commercially available crude human chorionic gonadotropin (crude hCG). Amberlite CG-50 column chromatography of crude hCG(2,680 IU/mg) produced hCG(7,130 IU/mg) and non hCG(130 IU/mg) fractions. The hCG fraction was further fractionated by Sephadex G-100 column chromatography and a highly purified fraction with a potency of 18,600 IU/mg was obtained. The non hCG fraction was separated into two fractions, F-1 and F-2, on Sephadex G-75. Each fraction was examined for its inhibitory effect on the incorporation of 3H-thymidine by normal human peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA test) or mixed lymphocyte reaction (MLR test). The original crude hCG showed considerable inhibition in both PHA and MLR tests, but the purified hCG showed no inhibition. F-1 fraction, having a molecular weight (M.W.) ranging from 75,000 to 100,000 daltons, was the most potent in the inhibition of all the other fractions. The inhibitory activity in the F-1 fraction was dose-dependent and relatively stable when exposed to heat and trypsin treatment, but completely inactivated by neuraminidase treatment. These results strongly suggest that the macromolecular substance(s), with a M.W. of 75,000 to 100,000, which is present in crude hCG but different from genuine hCG, has potent immunosuppressive effects and that sialic acid residues in the substance(s) are related to the manifestation of these effects.

Chorionic Gonadotropin↗
PubMed1986

[Determination of urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion as a parameter of nephrotoxicity due to cis-platin and the effect of fosfomycin (FOM) on its nephrotoxicity].

CDDP is often dose-limited owing to its nephrotoxicity. Urinary NAG was measured to evaluate the nephrotoxicity of CDDP in 18 patients (DIV: 12 patients, Intra-Peritoneal: 6 patients) with or without Fosfomycin. The gradual increase in urinary NAG activity was noted on repeating the therapy. 24 hour NAG excretion was correlated with that of urinary beta 2-microglobulin. However, urinary NAG was not correlated with Ccr 24 or BUN. Though Ccr 24 and BUN were normal, urinary NAG and beta 2-microglobulin markedly increased during CDDP therapy. Fosfomycin administration significantly decreased urinary NAG, which was increased by CDDP. These results indicate that: The measurement of urinary NAG and beta 2-microglobulin are most useful in estimating the nephrotoxicity of CDDP. Fosfomycin decreases the nephrotoxicity of CDDP.

Acetylglucosaminidase↗