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Biomedical subjects

N Chino

Publications and source records attributed to N Chino.

At least 91 records · Page 5Linked to original sources
PubMed1987

Binding of synthetic beta-human atrial natriuretic peptide to cultured rat vascular smooth muscle cells.

We have studied the effects of synthetic beta-human atrial natriuretic peptide (beta-hANP), an antiparallel dimer of alpha-hANP, on receptor binding and cGMP generation in cultured rat vascular smooth muscle cells and compared the effects with those of alpha-hANP. Characteristics of temperature-dependent binding and degradation of 125I-beta-hANP were similar to those of 125I-alpha-hANP. Scatchard analysis indicated a single class of binding sites for beta-hANP with a maximal binding capacity one-half that of alpha-hANP. Parallel and antiparallel dimers were equipotent in inhibiting the binding and stimulating intracellular cGMP formation, of which the maximal effect was about one-half that of alpha-hANP. Reverse-phase high performance liquid chromatography revealed that most of beta-hANP added to cells was converted to a small molecular mass component corresponding to alpha-hANP after incubation. These data suggest that the less potent effect of beta-hANP in receptor binding and cGMP generation may be partly accounted for by the possible conversion of beta-hANP to alpha-hANP at the site of target cells.

Animals↗
PubMed1986

Synthesis and biological properties of antiparallel and parallel dimers of alpha-human atrial natriuretic peptide.

To obtain antiparallel and parallel dimers of alpha-human atrial natriuretic peptide (alpha-hANP), two fully protected peptides I and II having the same amino acid sequence as alpha-hANP with different protective groups at the cysteinyl residues were synthesized, the former having Acm and Npys and the latter MeBzl and Acm. Equivalent amounts of peptides I and II were mixed and subjected to HF deprotection. Next, the first disulfide bond was linked between the remaining Npys group in I and the liberated SH group in II to form a monodisulfide dimer. The second disulfide bond was formed within the newly formed dimer between the remaining Acm groups by treatment with iodine, giving an antiparallel dimer. The parallel dimer of alpha-hANP was synthesized similarly starting from the protected peptide II. These dimers could be clearly segregated on HPLC. The retention time on HPLC of the antiparallel dimer was identical with that of natural beta-hANP. Both dimers showed biological activities as high as one third to one sixth of alpha-hANP in smooth muscle spasmolytic activity, and almost the same level of natriuretic activity as alpha-hANP at a high dose (10 nmol/kg) but about one fifth the activity at a low dose (1 nmol/kg). In these assay systems, the antiparallel dimer showed a slower onset and a tendency of longer duration than alpha-hANP.

Amino Acid Sequence↗
PubMed1985

Comparison of reversed-phase and cation-exchange high-performance liquid chromatography for separating closely related peptides: separation of Asp76-human parathyroid hormone (1-84) from Asn76-human parathyroid hormone (1-84).

Cation-exchange high-performance liquid chromatography (CE-HPLC) was compared with ordinary reversed-phase high-performance liquid chromatography (RP-HPLC) for separating closely related peptides. Some synthetic samples of bradykinin and angiotensins, which were homogeneous according to RP-HPLC, were found to be inhomogeneous when analyzed by CE-HPLC. On the other hand, diastereomeric peptides could be separated much more efficiently by RP-HPLC than by CE-HPLC. These results indicated that the purity of synthetic peptides should be checked not only by RP-HPLC but also by ion-exchange HPLC. In the case of human parathyroid hormone (hPTH), baseline separation of Asp76-hPTH from Asn76-hPTH by RP-HPLC was not possible, but was by CE-HPLC. Using this method we confirmed that the Asn residue in hPTH at position 76 could not be converted into the Asp residue under the conditions used to isolate and purify it from human organs.

Angiotensin II↗
PubMed1985

Reconstruction of the total cheek defect by free myocutaneous flap.

Our reconstructive method utilizing the free latissimus dorsi myocutaneous flap by microneurovascular anastomosis is a rewarding method for the patient with total cheek defect after cancer surgery of the maxillary sinus from the standpoint of morphology, function, and psychology.

Aged↗
PubMed1984

Nuclear-magnetic-resonance studies on the conformations of tridecapeptide alpha-mating factor from yeast Saccharomyces cerevisiae and analog peptides in aqueous solution. Conformation-activity relationship.

The conformation of tridecapeptide alpha-mating factor from yeast Saccharomyces cerevisiae in aqueous solution was analyzed, in comparison with those of active analog and inactive analog peptides. 270-MHz 1H-NMR spectra of these peptides were observed and the spectral patterns of main-chain N-H proton resonances were classified into three groups. alpha-mating factor and Trp1-bearing active peptides belong to the group A1, active des-Trp1-peptides belong to the group A2 while the peptides of group B are inactive. The main-chain N-H proton resonances of the groups A1 and A2 and side-chain N-H proton resonances were all assigned to individual residues. The 13C-NMR analysis of alpha-mating factor indicates that the Lys7-Pro8 and Gln10-Pro11 peptide bonds exclusively take the trans form. From the temperature and pH dependences of chemical shifts and Gd(III)-induced relaxation enhancements of amide proton resonances, alpha-mating factor is found to take partly a folded conformation in aqueous solution, with an alpha-helical form in the N-terminal domain and two beta-turn forms in the central and C-terminal domain. The pH dependence of fluorescence intensity indicates that, in this folded conformation, the C-terminal carboxylate group lies close to the N-terminal domain. The presence of the folded form in the N-terminal domain and the beta-turn form in the central domain correlates with the biological activity of alpha-mating factor and analog peptides. However, the folded conformation of alpha-mating factor is in equilibrium with predominantly unordered form, as found from the circular dichroism and NMR analyses. The N-H proton and C-alpha proton resonances of free alpha-mating factor as assigned in the present study allow the transferred nuclear Overhauser enhancement (NOE) analysis of the membrane-bound conformation that is more directly related with the activity.

Amides↗
PubMed1984

Conduction study in human muscle fibers in situ--a useful technique for diagnosing myopathies.

Direct muscle conduction studies were carried out using monopolar needle electrodes in the distal portion of the brachial biceps muscles in 13 normal and 10 myopathic subjects. Two monopolar Teflon-coated needles with exposed tips were placed as stimulation electrodes in the distal end of the biceps muscle. A pick-up monopolar electrode was then placed 4 cm proximal to the stimulation electrodes along the same muscle with a surface reference electrode in the vicinity of the active electrode. After the maximal evoked response was detected, the shape, amplitude and duration were recorded. The results revealed that the muscle conduction velocity was slower in polymyositis patients compared with normal subjects but was not significantly different in patients with progressive muscular dystrophy. However, the shape, amplitude and duration of the muscle-evoked potential were characteristic in the myopathies. It is concluded that this muscle conduction study technique is simple and of clinical use in making electrodiagnosis.

Action Potentials↗
PubMed1984

Biological properties of chicken luteinizing hormone-releasing hormone: gonadotropin release from rat and chicken cultured anterior pituitary cells and radioligand analysis.

We have examined the biological properties of chicken LHRH, which has been isolated and characterized in our laboratory, using primary monolayer cultures of rat and chicken anterior pituitary cells. The radioligand receptor analysis using rat pituitary LHRH receptor was also performed. Biological activities of mammalian LHRH and a more potent analog, [D-Leu6]des-Gly10-LHRH N-ethylamide ([D-Leu6] LHRH analog), were compared with those of chicken LHRH. The ED50 values for [D-Leu6]LHRH analog, mammalian LHRH, and chicken LHRH were, respectively, 0.0166, 0.455, and 18.2 nM for LH secretion and 0.0089, 0.263, and 8.28 nM for FSH secretion from rat pituitary cells. Relative potencies of chicken LHRH were 2.5% that of mammalian LHRH for LH and 3.2% that for FSH. On the other hand, the ED50 for chicken LHRH for LH release from chicken anterior pituitary cells was 1.03 nM, indicating that the biological potency of chicken LHRH acting on chicken pituitary cells was higher than that of chicken LHRH acting on mammalian pituitary cells. The ID50 of chicken LHRH to inhibit the binding of 125I-labeled [D-Leu6]LHRH analog to rat anterior pituitary membrane was 708.5 nM, and was 200 times that of mammalian LHRH (3.39 nM). These results suggest that the substitution of arginine residue of mammalian LHRH for glutamine residue of chicken LHRH causes a decrease in the binding affinity of the hormone for the mammalian LHRH receptor and that the mammalian LHRH receptor has a binding site for the cationic center of the arginine residue of LHRH. On the other hand, chicken pituitary LHRH receptor seems to have more broad specificity than mammalian LHRH receptor.

Animals↗
PubMed1983

Evidence that chicken hypothalamic luteinizing hormone-releasing hormone is [Gln8]-LH-RH.

As previously reported, chicken LH-RH has been purified in a yield of ca. 2.5 micrograms from 2,000 chicken hypothalmi, and we have estimated its chemical structure to be [Gln8]-LH-RH (1). Based on our previous observation (1), [Gln8]-LH-RH and [Glu8]-LH-RH have been synthesized by the solution method for the purpose of the structural confirmation. Synthetic [Gln8]-LH-RH was confirmed to be identical to natural chicken LH-RH on a HPLC system. For further structural confirmation, chymotryptic and thermolytic peptides from synthetic [Gln8]-LH-RH and natural chicken LH-RH were also identified. Thus, these studies support the view that chicken LH-RH has the following structure; pGlu-His-Trp-Ser-Tyr-Gly-Leu-Gln-Pro-Gly-NH2, [Gln8]-LH-RH. The gonadotropin releasing potency of synthetic [Gln8]-LH-RH was also in a good agreement with that of natural preparation.

Amino Acid Sequence↗
PubMed1981

Electrophysiological investigation on shoulder subluxation in hemiplegics.

Twenty-one consecutive hemiplegic patients underwent electrophysiological evaluation of their shoulder subluxation. The patients comprised 13 men amd 8 women, with a mean age of 57 years. The distal latency times of the suprascapular, axillary, musculocutaneous and radial nerves were 4.8, 6.2, 5.3 and 5.5 msec, respectively, and all nerves tested were statistically delayed. Ten out of 21 suprascapular nerves did not respond adequately. Based on needle EMG studies, about 75% of the supraspinatus and deltoid muscles revealed increased insertional activity and/or positive sharp waves. It is postulated that shoulder subluxation in hemiplegics may be caused by brachial plexus lesions. As regards therapeutic measures, the paralysed flaccid shoulder should be placed in a retracted posture or suspended to prevent the joint from being overstretched and ROM exercise of the shoulder joint should be carried out as a cautious maneuver to avoid displacement of the glenohumeral joint.

Adult↗
PubMed1975

Negative pressures during swing phase in below-knee prostheses with rubber sleeve suspension.

Negative pressures in the small space between the distal stump and the below-knee prosthetic socket were measured during swing phase for a series of nine subjects. A molded rubber sleeve connecting the prosthesis and the thigh was found to enhance this effect so that suction suspension occurred during the entire swing phase. Deterioration of the suction occurred when the sleeve was intentionally pierced, and when other suspensions such as a suprapatellar cuff or thigh band were tested. The findings indicate that the total-contact socket, gel liner and elastic sleeve combine to create suction in the below-knee socket which improves overall comfort and function for the patient in using the prosthesis.

Adult↗