Biomedical subjects

Y Yamagata

Publications and source records attributed to Y Yamagata.

At least 55 records · Page 3Linked to original sources

PubMed1999

Changes in interleukin-1beta mRNA expression in the rat ovary during the estrous cycle in response to lipopolysaccharide.

The changes in interleukin-1 (IL-1) beta mRNA expression and the number of macrophages were studied in the ovary during the estrous cycle in rats and after intraperitoneal injection of lipopolysaccharide (LPS, 2 mg/body) 2 hours before autopsy. IL-1beta mRNA expression was very low in the ovary, and there was no statistically significant change during the estrous cycle. Hybridization signals of IL-1beta mRNA were localized intensely in the thecal layer, moderately in the corpora lutea, and slightly in granulosa cells of the ovary during the cycle. The number of macrophages seen mainly in the hilum and interstitium significantly increased on proestrus compared with other estrous days. LPS significantly increased IL-1beta mRNA expression on each day with the highest response to LPS at 1500 h on proestrus, and caused an increase in the number of macrophages in the ovary within 2 hours. These results indicate that IL-1beta mRNA expressions are low during the estrous cycle in rats, and proestrus is the day of maximal IL-1beta synthesis in response to LPS. The increase in IL-1beta synthesis caused by LPS might be due to at least the influx of macrophages into the ovary.

Animals↗

PubMed1999

Changes in nitric oxide synthase activity in the ovary of gonadotropin treated rats: the role of nitric oxide during ovulation.

Immature rats receiving equine chorionic gonadotropin (eCG) and human CG (hCG) were used to study the time course changes in nitric oxide synthase (NOS) activity in the ovary during ovulation. To study the role of NO in ovulation, the effects of intrabursal injection of L-N(G)-monomethylarginine (L-NMMA, 125 microg/20 microl/bursa), a NOS inhibitor, on the number of ova shed were also examined. Rats were sacrificed at -48, 0, 3, 6, 9, 12, and 24 h after hCG injection, and the ovaries were collected for the NOS activity assay, Western blotting, NADPH-diaphorase histochemistry and immunohistochemistry. Total NOS and constitutive NOS activities in the ovary increased significantly at 9 h after hCG injection and the values remained high thereafter. Inducible NOS (iNOS) activity was detectable as a small peak at 3 and 6 h after hCG injection. Endothelial NOS (eNOS) protein production increased after hCG injection with a peak at 12 h, whereas iNOS protein production decreased at 12 and 24 h after hCG injection. NADPH-diaphorase positive cells increased at the thecae of growing follicles after hCG injection, appeared at mural granulosa cells before ovulation, and were detected in newly formed corpora lutea, which coincided with the results in eNOS positive cells by immunohistochemistry. L-NMMA given to rats at 5 or 7 h after hCG was most effective in reducing the number of ova shed. These results indicate that the NOS activity and NOS positive cells increased after hCG injection, and that eNOS was likely the main NOS increasing in the ovary during ovulation. It is concluded that NO produced between 5 and 9 h after hCG might play a supportive role in ovulation.

Animals↗

PubMed1998

Reactions of 7- and 9-aminoadenines with 2,4-pentanedione. Formation of new ring systems, pyridazino[6,1-f]purine and pyridazino[1,6-e]purine.

Reactions of 7-aminoadenines with 2,4-pentanedione yielded pyridazino[6,1-f]purines and 5-pyrazolylpyrimidines. The structure of the latter was identified by X-ray analysis. Reaction of 9-amino-N6-methyladenine with 2,4-pentanedione gave pyridazino[1,6-e]purine and Schiff base products. Possible reaction mechanisms are discussed.

Crystallography, X-Ray↗

PubMed1998

A general rule for the relationship between hydrophobic effect and conformational stability of a protein: stability and structure of a series of hydrophobic mutants of human lysozyme.

To get a general rule for the relationship between hydrophobic effect and conformational stability, five Ile to Val and nine Val to Ala mutants (3SS mutants) from 3SS (C77A/C95A) human lysozyme were constructed. As known from previous studies, the 3SS protein lacking a disulfide bond between Cys77 and Cys95 is destabilized by enthalpic factors, as revealed by a decrease of about 20 kJ/mol in the denaturation Gibbs energy change (DeltaG) value, as compared to the wild-type protein, which has four disulfide bonds. In this study, the stabilities and structures of the 3SS mutants were determined by differential scanning calorimetry and X-ray crystal analysis, respectively, and compared with those of the mutants (4SS mutants) from the wild-type (4SS) protein published previously. The stabilities of all the 3SS mutants, except for V110A-3SS were decreased as compared with that of the 3SS protein, coinciding with the results for the 4SS mutants. The change in the denaturation Gibbs energy change (DeltaDeltaG) values of the 3SS mutants relative to the 3SS protein at the denaturation temperature (49.2 degreesC) of the 3SS protein at pH 2.7 were similar to those of the equivalent 4SS mutants relative to the wild-type at 64.9 degreesC. The Delta DeltaG values of the 3SS mutants correlated with the changes in hydrophobic surface area exposed upon denaturation (Delta DeltaASAHP) for all of the hydrophobic residues when the effects of the secondary structure propensity were considered. This correlation is identical with that previously found for the 4SS mutants. The linear relation between Delta DeltaG and Delta DeltaASAHP for all of the hydrophobic residues with the same slope was found also for the mutants of T4 lysozyme already reported, indicating that this is a general relationship between changes in conformational stability and changes in ASA values of hydrophobic residues due to mutations.

Calorimetry↗

PubMed1998

Contribution of hydrogen bonds to the conformational stability of human lysozyme: calorimetry and X-ray analysis of six tyrosine --> phenylalanine mutants.

The contribution of hydrogen bonds to the conformational stability of human lysozyme was investigated by the combination of calorimetric and X-ray analyses of six Tyr --> Phe mutants. Unfolding Delta G and unfolding Delta H values of the Tyr --> Phe mutant proteins were changed by from +0.3 to -4.0 kJ/mol and from 0 to -16 kJ/mol, respectively, compared to those of the wild-type protein. The net contribution of a hydrogen bond at a specific site to stability (Delta Gwild/HB), considering factors affected by substitutions, was evaluated on the basis of X-ray structures of the mutant proteins. In the present study, one of six mutant proteins was suitable for evaluating the strength of the hydrogen bond. Delta Gwild/HB for the intramolecular hydrogen bond at Tyr124 was evaluated to be 7.5 kJ/mol. Results of the analysis of other mutants also suggest that hydrogen bonds of the hydroxyl group of Tyr, including the hydrogen bond with a water molecule, contribute to the stabilization of the human lysozyme.

Calorimetry, Differential Scanning↗

PubMed1998

Determination of alpha-fetoprotein concentration based on liquid-phase binding assay using anion exchange chromatography and sulfated peptide introduced antibody.

A new immunoassay for alpha-fetoprotein based upon liquid-phase binding reactions is described. In this procedure, a sample that contains alpha-fetoprotein is mixed with a solution of two anti-alpha-fetoprotein monoclonal antibodies complexed with peroxidase and sulfated peptide, respectively. After incubation, immune complex is separated from other components by anion exchange column chromatography. Immune complex is quantified using fluorometric detection by peroxidase enzymatic activity. Peroxidase activity correlated with a alpha-fetoprotein with a 1:1 relationship. The stoichiometric immunoreaction allowed a large analytical range (0.4-7500 ng/ml) with a linear dose-response relationship, high sensitivity and good precision. Endogenous substances did not interfere with assay performance. Assay results showed good correlation with other established methods. These results indicate that the method is useful for clinical alpha-fetoprotein determinations.

Anions↗

PubMed1998

Liquid-phase binding assay of alpha-fetoprotein using a sulfated antibody for bound/free separation.

A rapid immunoassay using a sulfated antibody for bound/free separation in a liquid-phase binding assay is described. A first anti-alpha-fetoprotein monoclonal antibody was labeled with peroxidase (Fab'-POD) and a second monoclonal antibody was conjugated with polysulfated tyrosine peptide (Fab'-YS). The monoclonal antibodies and alpha-fetoprotein (AFP) were mixed, incubated, and analyzed directly by anion-exchange column chromatography. The amount of POD activity in the column effluent was determined fluorophotometrically. The bound (Fab'-POD + AFP + Fab'-YS) and free (Fab'-POD) forms of the conjugate were clearly and easily separated by ionic charge, and the free sulfated antibody (Fab'-YS) was not detectable fluorophotometrically. The elution position of the bound conjugate was adjusted by varying the length of the polysulfated tyrosine peptide. This method is convenient for antigen measurement because (1) only two modified antibodies are used in a buffer solution, (2) the concentration of antibodies and other assay conditions are easily set, (3) no solid phase is required, and (4) no washing is necessary.

Antibodies, Monoclonal↗

PubMed1998

Isolation and characterization of cDNA encoding chicken egg yolk aminopeptidase Ey.

Aminopeptidase Ey (EC 3.4.11.20) from chicken (Gallus gallus domesticus) egg yolk is a homodimeric exopeptidase with a broad specificity for N-terminal amino acid residues at P1 position of the substrate. Aminopeptidase Ey is a 300-k metalloexopeptidase, containing 1.0 g atom of zinc per mole of a subunit with a relative molecular mass of 150 k. A full-length cDNA was cloned from chicken (female) liver cDNA library. Analysis of the 3196-base pairs (bp) nucleotide sequence of the cDNA revealed a single open reading frame coding for 967 amino acid residues. The coding region of aminopeptidase Ey gene, apdE, occupies 2901 bp of the cDNA. The predicted amino acid sequence of the enzyme is 66, 65, 64 and 63% identical with those of aminopeptidases N (EC 3.4.11.2) from human, pig, rabbit and rat, respectively. Aminopeptidase Ey contains the metallo-binding sequence motif, His-Glu-Xaa-His, found in zinc metallopeptidases. Zinc binding sites, His-386, His-390 and Glu-409, and catalytic site, Glu-387, were conserved in the homologous aminopeptidases N.

Amino Acid Sequence↗

PubMed1998

Dynamic regulation of the activated, autophosphorylated state of Ca2+/calmodulin-dependent protein kinase II by acute neuronal excitation in vivo.

Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been implicated in various neuronal functions, including synaptic plasticity. To examine the physiological regulation of its activated, autophosphorylated state in relation to acute neuronal excitation in vivo, we studied the effect of electroconvulsive treatment in rats on CaMKII activity and in situ autophosphorylation levels. As early as 30 s after the electrical stimulation, a profound but transient decrease in its Ca2+/calmodulin-independent activity, as well as in the level of its autophosphorylation at Thr286(alpha)/Thr287(beta) measured by using phosphorylation state-specific antibodies, was observed in homogenate from hippocampus and parietal cortex, which was reversible in 5 min. In the later time course, a moderate, reversible increase, which peaked at around 60 min after the electrical stimulation, was observed in parietal cortex but not in hippocampus. The early-phase decrease was found to occur exclusively in the soluble fraction. In addition, partial translocation of CaMKII from the soluble to the particulate fraction seems to have occurred in this early phase. Thus, the activated, autophosphorylated state of CaMKII is under dynamic and precise regulation in vivo, and its regulatory mechanisms seem to have regional specificity.

Animals↗

PubMed1998

Melatonin directly suppresses steroid production by preovulatory follicles in the cyclic hamster.

The purpose of these studies was to investigate the effects of melatonin on the production of steroids (progesterone, testosterone, and estradiol) and cAMP by preovulatory follicles and to examine changes in melatonin concentrations in the ovary during the estrous cycle. Adult cyclic hamsters were used in this study. Melatonin concentrations in the ovary, pineal gland, and serum were measured at mid-light and mid-dark during the estrous cycle. Effects of melatonin on steroidogenesis by preovulatory follicles, thecae, and granulosa cells were examined, and its effect on cAMP production by preovulatory follicles was also investigated. Melatonin (0.1-10 ng/ml) had no effect on steroid production in the absence of hCG, but melatonin decreased progesterone and estradiol production by preovulatory follicles in a dose-dependent and time-dependent manner in the presence of hCG (100 mIU/ml). The target of melatonin was thecae but not granulosa cells, and melatonin significantly reduced cAMP production by preovulatory follicles. Melatonin concentrations in the ovary showed a similar phasic variation with high levels during mid-dark and low during mid-light, as in the pineal gland and serum. These results show that the ovarian melatonin levels also exhibit a circadian rhythm and suggest that the high melatonin milieu in the ovary may induce gonadal regression in the cyclic hamster.

Animals↗

PubMed1998

Pinealectomy of melatonin implantation does not affect prolactin surge or luteal function in pseudopregnant rats.

The effects of melatonin on twice daily surges in PRL and luteal function were studied in pseudopregnant (PSP) rats. Cyclic rats received pinealectomy or sham operation under pentobarbital anesthesia on diestrus 1. Pinealectomized rats immediately received a melatonin capsule (the PINX+Mel group) or a blank capsule (the PINX group), and sham group of rats received a blank capsule (the control group). After operation, all rats were maintained under the same photoperiod conditions (14L: 10D), and estrous cyclicity was examined. At the 8th estrous cycle after operation, PSP was induced by mechanical stimulation of the uterine cervix. The last day on which the rat exhibited the estrous smear was designated as day 1 of PSP. Blood samples were obtained by jugular venipuncture under light ether anesthesia between 1200 and 1300 h on days 1, 3, 5, 7, 9 and 11, and between 0000 and 0100 h on day 13 of PSP. All rats were decapitated between 1200 and 1300 h on day 13 of PSP, and trunk blood was collected. A silicon catheter was inserted into the right jugular vein under ether anesthesia on day 4 of PSP. Blood samplings were performed every 2 h between 1000 h on day 5 and 1000 h on day 6 of PSP. Serum concentrations of melatonin, PRL and progesterone were measured by radioimmunoassay. Pinealectomy or melatonin installation did not disturb the estrous cyclicity or the induction of PSP. There were no differences among the three groups of rats during PSP in the pattern or serum PRL concentrations, and there were no significant differences among these three groups in the serum progesterone concentration or weight of the corpus luteum. The present results indicated that the continuously high or low melatonin in the physiological range did not affect the rhythm or strength of PRL surges or luteal function in PSP rats.

Animals↗

PubMed1998

[Squamous cell lung cancer with minimal-change nephrotic syndrome].

We report a case of squamous cell lung cancer with nephrotic syndrome. A 69-year-old man was admitted because of proteinuria and microhematuria. A plain chest X-ray film on admission showed a large mass in the left-lower lung field. The patient was given a diagnosis of minimal-change-nephrotic syndrome and squamous cell lung cancer. We first treated the nephrotic syndrome with glucocorticoid therapy, and then treated the lung cancer with chemo-radiotherapy. This reduced the lung cancer, alleviated the proteinuria, and completely resolved the nephrotic syndrome. Nephrotic syndrome is generally associated with malignant lymphoma and other nonepithelial neoplasms. As the underlying disease, epithelial neoplasms are less common, but lung cancer is one of the most widely reported. Histologically, most cases of cancer-associated nephrotic syndrome exhibit membranous nephropathy; Minimal-change nephrotic syndrome is rare. Deposits of immunocomplex on glomerular basement membrane are considered to play a pathogenic role in membranous nephropathy. However, the pathogenesis of minimal-change nephrotic syndrome is different.

Aged↗

PubMed1998

[Two cases of anti-neutrophil cytoplasmic antibody-negative generalized Wegener's granulomatosis with alveolar hemorrhage].

Anti-neutrophil cytoplasmic antibody (ANCA) is a distinct marker for Wegener's granulomatosis. We report two cases of ANCA-negative Wegener's granulomatosis. A 70-year-old woman (case 1) and a 27-year-old woman (case 2), who had sinus symptoms and renal disorders, were admitted to our hospital with alveolar hemorrhage. Wegener's granulomatosis was diagnosed on biopsy of the nasal mucosa. Case 1 responded well to the combination therapy with cyclophosphamide and prednisolone, while case 2 responded well to pulse therapy with methyl-prednisolone. These findings suggest that patients with ANCA-negative Wegener's granulomatosis may respond well to chemotherapy. This might lead to an improved prognosis in even severe cases, even though the prognosis of generalized Wegener's granulomatosis with alveolar hemorrhage is usually poor.

Adult↗

PubMed1997

Contribution of water molecules in the interior of a protein to the conformational stability.

Water molecules frequently occur in the interior of globular proteins. To elucidate the contribution of buried water molecules to the conformational stability of a protein, we examined the crystal structures and the thermodynamic parameters of denaturation of six Ile to Ala/Gly mutant human lysozymes, in which a cavity is created at each mutation site by the substitution of a smaller side-chain for a larger one. One or two ordered water molecules were found in the cavities created in some mutants (I106A, I59A and I59G). The cavity volumes for these three mutants were bigger than those that remained empty in the other mutants. The stability of the mutant proteins with the newly introduced water molecules was about 8 kJ/mol higher than that expected from the change in hydrophobic surface area (DeltaDeltaASAHP) exposed upon denaturation. It was concluded that a water molecule in a cavity created in the interior of a protein contributes favorably to the stability.

Amino Acid Substitution↗

PubMed1997

Contribution of the hydrophobic effect to the stability of human lysozyme: calorimetric studies and X-ray structural analyses of the nine valine to alanine mutants.

To clarify the contribution of the hydrophobic effect to the conformational stability of human lysozyme, a series of Val to Ala mutants were constructed. The thermodynamic parameters for the denaturation of these nine mutant proteins were determined using differential scanning calorimetry (DSC), and the crystal structures were solved at high resolution. The denaturation Gibbs energy (delta delta G) and enthalpy (delta delta H) values of the mutant proteins ranged from +2.2 to- 6.3 kJ/mol and from +7 to -17 kJ/mol, respectively. The structural analyses showed that the mutation site and/or the residues around it in some proteins shifted toward the created cavity, and the substitutions affected not only the mutations site but also other parts far from the site, although the structural changes were not as great. Correlation between the changes in the thermodynamic parameters and the structural features of mutant proteins was examined, including the five Ile to Val mutant human lysozymes [Takano et al. (1995) J. Mol. Biol. 254, 62-76]. There was no simple general correlation between delta delta G and the changes in hydrophobic surface area exposed upon denaturation (delta delta ASAHP). We found only a new correlation between the delta delta G and delta delta ASAHP of all of the hydrophobic residues if the effect of the secondary structure propensity was taken into account.

Alanine↗

PubMed1997

Congenital cystic adenomatoid malformation with extramedullary hematopoiesis of the lung: a case report.

The authors report a case of congenital cystic adenomatoid malformation of the lung (CCAM) with extramedullary hematopoiesis (EMH). A baby girl suffered from Rh incompatibility and hemolytic anemia. She exhibited respiratory distress. Chest radiography and magnetic resonance imaging findings showed a CCAM. A resection of the upper and middle lobes of the right lung was performed. Histological examination showed a CCAM of Stocker's type II with EMH. EMH in the lung is very rare. The authors speculate that the cause of our case originated from Rh incompatibility and development arrest in the CCAM lung.

Cystic Adenomatoid Malformation of Lung, Congenita↗

PubMed1997

Condensation of glycylglycine to oligoglycines with trimetaphosphate in aqueous solution. II: catalytic effect of magnesium ion.

The previously reported condensation reaction of glycylglycine with trimetaphosphate (Yamanaka et al., 1988) was reinvestigated and shown to be catalyzed by magnesium ion. Aqueous solutions containing glycylglycine (0.5 M), trimetaphosphate (0.5 M) and magnesium chloride (0.5 M) were incubated at 38 degrees C at pH 4, 5, 6, 7 and 8. After incubation for ten days at pH 5, the maximum yields of tetraglycine and hexaglycine as condensation products were found to be about 12 and 1.4%, respectively. This result indicated the presence of a considerable catalytic effect of magnesium ion compared with the maximum yield of about 2% for tetraglycine and approximately 0% for hexaglycine in the absence of magnesium ion.

Evolution, Chemical↗

PubMed1997

Inclusion of nucleic acid contribution into assessment of protein 3d-1D compatibility and prediction of binding sites for nucleic acids.

The novel three dimensional structure(3D)-amino acid sequence(1D) compatibility program, 3d-1D method has developed and expanded into protein-nucleic acid system. The environment characteristics are determined using the coordinates of backbone atoms and C beta atom. This simplified estimation allows the expanded application to monitor the change of environment class depending on different sequence alignment. This method has improved the detective performance of the different protein into the similar folds. If protein has a wide contact with nucleic acid molecule, the compatibility profile goes down in the contact region without ligand molecule. This phenomenon becomes useful to monitor the binding sites of the bulky ligand such as nucleic acid and to model the protein-nucleic acid complex.

Amino Acid Sequence↗