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Biomedical subjects

F Hayashi

Publications and source records attributed to F Hayashi.

At least 145 records · Page 8Linked to original sources
PubMed1990

A synthetic peptide corresponding to residues 137 to 157 of p60v-src inhibits tyrosine-specific protein kinases.

A 21-residue synthetic peptide corresponding to a part of the noncatalytic domain of p60v-src (residues 137 to 157) was found to inhibit the tyrosine kinase activity of p60v-src. The half inhibition concentration was ca. 7.5 microM. The peptide (peptide A) did not compete with substrate proteins or ATP. Peptide A also inhibited the autophosphorylation of epidermal growth factor receptor/kinase and the tyrosine-specific protein phosphorylation in the acetylcholine receptor-rich membranes isolated from electroplax of Narke japonica. However, serine/threonine-specific protein kinases such as cAMP-dependent and cGMP-dependent protein kinases were not inhibited by peptide A.

Amino Acid Sequence↗
PubMed1990

Interactions between the subunits of transducin and cyclic GMP phosphodiesterase in Rana catesbiana rod photoreceptors.

In bullfrog (Rana catesbiana) rods the activity of cyclic GMP (cGMP) phosphodiesterase was stimulated 10 times by washing disc membranes with an isotonic, GTP-containing buffer. This stimulation was maintained following hydrolysis of GTP and after removal of guanine nucleotides. At least 60-70% of the inhibitory gamma subunit of cGMP phosphodiesterase (P gamma) was physically released from membranes by these washing procedures. When cGMP phosphodiesterase was activated by a hydrolysis-resistant GTP analogue, P gamma was found in the supernatant complexed with the transducin alpha subunit (T alpha) using three chromatography systems. When GTP was used to activate cGMP phosphodiesterase, P gamma was also found in the supernatant complexed with GDP.T alpha. This complex was also isolated using the same three chromatography systems, indicating that P gamma remained tightly bound to T alpha even after bound GTP was hydrolyzed. Interaction with the beta,gamma subunits of transducin, which remained associated with disc membranes, was required for the release of P gamma from the GDP.T alpha complex, which resulted in the deactivation of active cGMP phosphodiesterase. We conclude that during activation of cGMP phosphodiesterase, P gamma is complexed with T alpha (both GTP and GDP forms) in the supernatant and that, following GTP hydrolysis, beta,gamma subunits of transducin are necessary for the release of P gamma from the complex and the resulting inactivation of cGMP phosphodiesterase in frog photoreceptors.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1990

Identification of two essential histidine residues of ribonuclease T2 from Aspergillus oryzae.

Ribonuclease (RNase) T2 from Aspergillus oryzae was modified by diethyl pyrocarbonate and iodoacetic acid. RNase T2 was rapidly inactivated by diethyl pyrocarbonate above pH 6.0 and by incorporation of a carboxymethyl group. No inactivation occurred in the presence of 3'AMP. 1H-NMR titration and photo-chemically induced dynamic nuclear polarization experiments demonstrated that two histidine residues were involved in the active site of RNase T2. Furthermore, analysis of inactive carboxymethylated RNase T2 showed that both His53 and His115 were partially modified to yield a total of one mole of N tau-carboxymethylhistidine/mole enzyme. The results indicate that the two histidine residues in the active site of RNase T2 are essential for catalysis and that modification of either His53 or His115 inactivates the enzyme.

Amino Acid Sequence↗
PubMed1990

A nuclear magnetic resonance study of the cyclic AMP receptor protein (CRP): assignments of the NH protons of histidine and tryptophan residues and the effect of binding of cAMP to CRP.

Seven well-resolved signals could be observed in the field lower than 9.5 ppm in the 1H-NMR spectrum of the H2O solution of cyclic AMP receptor protein (CRP). The signals of the tryptophan and histidine residues were identified on the basis of the CPMG spin echo spectra, the intra-residue NOE, 15N labeling, deuterium labeling, and the results of pH titration. The assignments of peaks to specific tryptophan and histidine residues are discussed in relation to the amino acid sequence and X-ray crystallographic data, and were confirmed by experiments involving partial subtilisin digestion. The four signals E (11.25 ppm), F (11.15 ppm), G (10.75 ppm), and H (10.65 ppm) were tentatively assigned to the resonances of the histidine residue at position 159, the arginine residue at position 82, and the tryptophan residues at positions 85 and 13, respectively. On the addition of cAMP and cGMP, signals F and G shifted up- and downfield respectively and conformational changes in the structure of CRP could be detected. The conformational transition mostly occurs when one cAMP molecule binds to one of the dimer subunits, but is completed only when both cAMP binding sites are saturated.

Carrier Proteins↗
PubMed1990

The structure of PA48009: the revised structure of duramycin.

PA48009, a lanthionine-containing peptide antibiotic was isolated from the culture broth of Streptoverticillium griseoverticillatum PA-48009, and identified as duramycin. Determination of the structure using both Edman degradations and 2D NMR spectroscopy showed the need to revise the structure of duramycin given in literature. Duramycin (PA48009) was different from lanthiopeptin (Ro 09-0198, cinnamycin) only by a Lys/Arg exchange at position 2.

Amino Acid Sequence↗
PubMed1989

Photo-CIDNP studies of Bence Jones proteins, immunoglobulins, and their proteolytic fragments.

The results of photo-CIDNP measurements of Bence Jones proteins, immunoglobulins, and their proteolytic fragments are reported. The CIDNP spectra of constant region CL fragments, which were derived from lambda-type Bence Jones proteins with three different isotypes, gave polarizations originating from two Tyr and one Trp residues. From comparisons of the results obtained by using lambda-type Bence Jones proteins that possess the known amino acid sequences with those for the CL fragments, it was concluded that the CIDNP signals observed in the case of Bence Jones proteins are all due to the hypervariable region. On the basis of the results obtained by using IgG1, IgG2, IgG3, and IgG4 myeloma proteins along with their Fab, Fc, and pFc' fragments, it was concluded that CIDNP signals for the Fab region all originate from the variable region. The Fc region gives two Tyr polarizations, one of which has been assigned to Tyr-296. We have also shown that the second Tyr signal is due to Tyr-373. Interaction of Fc and staphylococcal protein A has also been examined by the CIDNP technique.

Amino Acid Sequence↗
PubMed1989

Further development of experimental techniques for refilling the lens of animal eyes with a balloon.

Various techniques for experimental refilling of the lens of animal eyes are possible. We describe two new methods: Balloon insertion after endocapsular phacoemulsification and after phacoemulsification with circular capsulorhexis. The feasibility of these techniques was tested in both rabbit eyes and pig cadaver eyes. With organo-silicone gel as the balloon filling material, post-operative refractive changes of up to 4 diopters of residual hyperopia were achieved; accommodation changes were up to -1 diopter. The technique of refilling the lens with a balloon to avoid leakage of filling material warrants further study.

Animals↗
PubMed1989

Clinical application of sodium-23 nuclear magnetic resonance for measurement of red cell sodium concentrations.

Red cell sodium (RBC-Na+) concentrations were measured using 23Na nuclear magnetic resonance (NMR), without the destruction of erythrocyte membranes. Subjects were categorized into four groups: 20 normotensive subjects (NT group), 20 age-matched essential hypertensive patients (EHT group), 10 patients with primary aldosteronism (PA group), and 18 patients treated with digoxin (DIG group). Although RBC-Na+ concentrations were similar between the NT group (6.14 +/- 0.80 (Mean +/- SD) mmol/l) and the EHT group (5.92 +/- 0.99), they were significantly higher in both the PA group (7.55 +/- 0.88, p less than 0.001) and the DIG group (8.43 +/- 3.81, p less than 0.02). In the PA group, RBC-Na+ concentrations decreased significantly after resection of the adenoma, and there was an inverse relationship between serum potassium and RBC-Na+ concentrations (r = -0.65, p less than 0.01). In the DIG group, RBC-Na+ concentrations tended to increase in proportion to serum digoxin levels (r = 0.53, p less than 0.05). These results support the view that RBC-Na+ concentrations are determined primarily by Na+/K+-pump activity of red cell membranes. This study showed also that Na+ NMR is an useful method determining intracellular Na+ concentrations.

Digoxin↗
PubMed1989

Protection against pertussis by acellular pertussis vaccines (Takeda, Japan): household contact studies in Kawasaki City, Japan.

To evaluate the vaccine efficacy of an acellular pertussis vaccine which has been in clinical use in Japan since 1981, a retrospective study was performed by a questionnaire survey of secondary pertussis attacks through family contact in 146 children with pertussis diagnosed in the period from January 1981 through May 1988. In this study, acellular vaccine made by Takeda Pharmaceutical Company, which contains a high level of FHA (filamentous hemagglutinin), a low level of PT (pertussis toxin) and a small amount of agglutinogen, was evaluated. Secondary pertussis attacks through family contact were found in 17 of 29 siblings (58.6%) not immunized with pertussis vaccine. On the other hand, 27 siblings immunized with Takeda's acellular vaccine were exposed to pertussis through family contact and a secondary attack was seen in only one of them (3.7%). The present study revealed an efficacy rate of 93.7% for Takeda's acellular pertussis vaccine.

Child↗
PubMed1989

[Protection against pertussis by Japanese T type acellular pertussis vaccine: household contact study in Kawasaki City].

To evaluate the vaccine efficacy of acellular pertussis vaccine which has been in clinical use in Japan since 1981, a retrospective study was made by a questionnaire from secondary pertussis attack through family contact in 149 children with pertussis diagnosed in the period from January 1981 through May 1988. In this study, Takeda's acellular vaccine which contains a high level of FHA, low level of PT and a small amount of agglutinogen, was evaluated. Secondary pertussis attacks through family contact were found in 17 of 29 siblings (58.6%) not immunized with pertussis vaccine. On the other hand of the siblings immunized with Takeda's acellular vaccine 27 were exposed to pertussis through family contact and a secondary attack was seen in only one of them (3.4%). The present study revealed an efficacy rate of 94.2% for the Takeda's acellular pertussis vaccine.

Child↗
PubMed1988

A photo-chemically induced dynamic nuclear polarization NMR study on rabbit and bovine cytochrome b5.

Although it has been indicated that proteins with chromophoric groups are not suitable for photo-chemically induced dynamic nuclear polarization (photo-CIDNP) measurements, we have successfully obtained these spectra for a heme protein, cytochrome b5. The characteristics of the spectra differed in some points from those so far reported. The intensities of the signals in the aromatic region were very weak, while those of the beta-methylene protons of one histidine and one tryptophan were extremely strong in comparison with the aromatic protons. It was demonstrated, on the basis of the photo-CIDNP spectrum, that one of seven histidines, all three tyrosines and a single tryptophan of the rabbit soluble cytochrome b5 are exposed on the surface of the protein. The results of comparison of the photo-CIDNP spectra for the rabbit soluble and intact, and bovine intact, cytochrome b5 led us to the conclusion that the conformation of the hydrophilic, catalytic part of cytochrome b5 is quite similar among these three proteins. In the presence of Chaps micelles, bovine intact cytochrome b5 was in monomeric form and the histidine signals disappeared from its photo-CIDNP spectrum. When bovine intact cytochrome b5 was reconstituted into egg yolk phosphatidylcholine liposomes, although separate signals due to the protein part were observed in the normal 1H-NMR spectrum, no photo-CIDNP signal could be detected. The normal spectrum suggests that the conformation of the protein embedded in liposomes is similar to that of the oligomeric form without lipids or a detergent.

Animals↗
PubMed1988

Hydrogen-exchange kinetics of the indole NH proton of the buried tryptophan in the constant fragment of the immunoglobulin light chain.

The constant fragment of the immunoglobulin light chain (type lambda) has two tryptophyl residues at positions 150 and 187. Trp-150 is buried in the interior, and Trp-187 lies on the surface of the molecule. The hydrogen-deuterium exchange kinetics of the indole NH proton of Trp-150 were studied at various pH values at 25 degrees C by 1H nuclear magnetic resonance. Exchange rates were approximately first order in hydroxyl ion dependence above pH 8, were relatively independent of pH between pH 7 and 8, and decreased below pH 7. On the assumption that the exchange above pH 8 proceeds through local fluctuations of the protein molecule, the exchange rates between pH 7 and 8 through global unfolding were estimated. The exchange rate constant within this pH range at 25 degrees C thus estimated was consistent with that of the global unfolding of the constant fragment under the same conditions as those reported previously [Kikuchi, H., Goto, Y., & Hamaguchi, K. (1986) Biochemistry 25, 2009-2013]. The activation energy for the exchange process at pH 7.8 was the same as that for the unfolding process by 2 M guanidine hydrochloride. The exchange rates of backbone NH protons were almost the same as that of the indole NH proton of Trp-150 at pH 7.1. These observations also indicated that the exchange between pH 7 and 8 occurs through global unfolding of the protein molecule and is rate-limited by the unfolding.(ABSTRACT TRUNCATED AT 250 WORDS)

Bence Jones Protein↗
PubMed1988

Influence of controlled breathing with diminished tidal volume on hypoxic heart rate response in man.

In 12 normal healthy males, the effect of preventing augmentation in tidal volume (VT) on the heart rate (HR) was examined during isocapnic progressive hypoxia. The amount of diminished tidal volume (delta VT) was 0.61 +/- 0.36 liters from the maximal VT value attained in the free breathing hypoxia. Hypoxic HR response in terms of arterial oxygen saturation (SaO2)/HR response slope (delta HR/delta SaO2) was significantly decreased from the free to controlled breathing (p less than 0.05). The effective VT range for eliciting such a HR change appeared to be more than 1,000 ml as has been demonstrated in the Hering-Breuer reflex on ventilation in humans. However, the magnitude of delta HR/delta SaO2 decrement was not significantly correlated with delta VT, suggesting that the command signal from the higher nervous center interfered with the expected response. Contrary to the HR response, the hypoxic ventilatory and occlusion pressure responses were not significantly influenced by the controlled breathing. We conclude that the hypoxic HR response is significantly depressed by the diminished VT breathing.

Heart Rate↗
PubMed1988

Posterior chamber lens implantation: histopathological report of a successful case.

Using electron microscopy, we examined an eye obtained at autopsy in which a C-loop intraocular lens had been implanted into the posterior chamber 2 years and 4 months prior to the patient's death. The lens was affixed with the superior loop outside the capsular bag and the inferior loop within the capsular bag. The two ciliary epithelial layers to which the superior loop was attached were thinned; the pigmented epithelial layer was completely absent and the nonpigmented epithelial layer was disrupted, suggesting breakdown of the blood-aqueous barrier. Proliferating lens epithelial cells, basement membrane-like material, collagen fibers and microfibrils were seen surrounding the inferior loop. The lens capsule, the zonular fibers and the ciliary epithelium adjacent to the inferior loop showed no pathological changes.

Anterior Eye Segment↗