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Biomedical subjects

N Yoshioka

Publications and source records attributed to N Yoshioka.

At least 127 records · Page 7Linked to original sources
PubMed1986

T-cell recognition of human haemoglobin. Localization of the full T-cell recognition profile of the beta-chain by a comprehensive synthetic strategy.

This paper reports the localization of the regions on the beta-chain that are recognized by T cells from mice immunized with haemoglobin. The 14 overlapping peptides encompassing the entire beta-chain were examined in vitro for their ability to stimulate lymph-node cells from haemoglobin-primed B10.D2 (H-2d) and SJL (H-2s) mice. Several regions of the molecule (T sites) were found to stimulate haemoglobin-primed lymph-node cells. This strategy has enabled the localization of the full profile of T-cell recognition of the beta-chain by these mouse strains. Some of the regions that stimulated T cells appeared to coincide with those recognized by antibodies (i.e. B cells). It is noteworthy that, in addition to sites recognized by both T and B cells, the protein has other sites that are recognized exclusively by T cells and to which no detectable antibody response is directed.

Animals↗
PubMed1986

Haemoglobin binding with haptoglobin. Localization of the haptoglobin-binding sites on the beta-chain of human haemoglobin by synthetic overlapping peptides encompassing the entire chain.

A synthetic approach was employed to identify the haptoglobin-binding sites on the beta-chain of human haemoglobin. This approach consists of the synthesis of a series of consecutive overlapping peptides that, together, systematically represent the entire protein chain. Fourteen synthetic peptides (beta 1-15, beta 11-25 etc.) were examined for their ability to bind human haptoglobin by quantitative solid-phase radiometric titrations of 125I-labelled haptoglobin. Of these 14 peptides only peptides beta 11-25 and beta 131-146 bound haptoglobin significantly; peptide beta 21-35 exhibited a small binding activity as a consequence of the overlap with peptide beta 11-25. On this basis and by examination of the three-dimensional structure of haemoglobin, it was concluded that the beta-chain of haemoglobin has two binding sites for haptoglobin that reside in, but do not necessarily encompass all of, the regions beta 11-25 and beta 131-146.

Binding Sites↗
PubMed1986

Subunit interacting surfaces of human haemoglobin. Localization of the alpha-subunit-beta-subunit interacting surfaces on the beta-chain by a comprehensive synthetic strategy.

A synthetic approach is introduced for localization of subunit interacting surfaces in oligomeric proteins. It consists of studying the binding activity of consecutive uniform overlapping peptides encompassing an entire subunit to the other, radiolabelled, subunit. This permits the establishment of the full profile of peptides that bind the other intact subunit. This approach has been demonstrated with haemoglobin, and its application here with the beta-chain peptides has enabled the localization on the beta-chain of the submolecular regions responsible for its binding to alpha-chain in solution. There was good agreement between the binding surfaces found here in solution and those expected from the crystal structure. There were also, however, some significant differences in the levels of binding found in solution and those expected from the crystal. Peptide 21-35 possessed much higher binding activity than would be expected from its contribution to subunit association in the crystal. Conversely, other regions expected to possess considerable binding capacity for alpha-chain either showed low (peptides 111-125 and 121-135) or almost no binding (peptides 91-105 and 101-115) capacity. On the other hand, two interacting surfaces (within peptides 11-25 and 71-85) that make a contribution in solution do not appear to play a role in the crystal. It is concluded that the regions of subunit association in solution are close to, but not identical with, those in the crystal. The approach should serve as an effective method for localization of subunit interacting surfaces of unknown proteins, even those that can be isolated only in traces.

Binding Sites↗
PubMed1986

Structure of the mutant prealbumin gene responsible for familial amyloidotic polyneuropathy.

Familial amyloidotic polyneuropathy (FAP) is a genetic disorder showing autosomal dominant inheritance. Amyloid fibrils of FAP patients from various origins have been shown to contain a prealbumin variant with Val30----Met30 substitution as a major component. However, the structure of the prealbumin gene responsible for the variation has not been characterized. We determined the complete nucleotide sequence of the prealbumin gene from a patient with the Japanese type of FAP. In comparison with a normal prealbumin gene sequence, the patient's gene was found to be carrying seven base substitutions. The substitution responsible for the Val----Met change was found in exon 2, as expected, and the others were in introns. Hybridization analyses of normal and FAP patient DNAs showed that the base substitution in exon 2 was specific for FAP but the others were polymorphic changes. It was concluded that the mutation responsible for the Val----Met change is the only base change specific for FAP in the prealbumin gene.

Amyloidosis↗
PubMed1985

Structure of the chromosomal gene for human serum prealbumin.

The human prealbumin gene has been cloned and its complete nucleotide sequence determined. The gene has a size of about 6.9 kb and is composed of four exons and three introns. Two Alu family sequences having opposing polarity were found in introns. In the 5'-flanking region, we found two overlapping sequences which have extensive homology to the glucocorticoid-responsive element. Three sequences identical with the enhancer core sequence were identified in introns and the 3'-flanking region. Unusual tandem repeats of a sequence, TTTTG, were also found in the 5'-flanking region and introns.

Amino Acid Sequence↗
PubMed1981

Specific staining of sialic acid components on sodium dodecyl sulfate polyacrylamide gel.

Specific staining of sialic acid components after sodium dodecyl sulfate polyacrylamide gel electrophoresis can be carried out as follows: 1) extract glycoprotein of erythrocyte membranes or serum by the phenol-saline method, 2) electrophorese the extract on 5% polyacrylamide gel containing 0.1% sodium dodecyl sulfate at constant current, 3) treat the gel with chilled 0.04 M HIO4 for 45 minutes, 4) replace the periodic acid solution with one containing resorcinol 0.6 g, conc. HCl 50 ml, 0.1 M CuSO4 0.5 ml and H2O 50 ml, 5) warm the container in boiling water until blue violet sialic acid bands become clear, 6) replace the staining solution with a mixture of equal parts water and concentrated HCl and observe at once.

Amido Black↗
PubMed1980

An improved isolation procedure for carbonic anhydrase C from red cell lysate.

An effective isolation of carbonic anhydrase C (CA-C) from red cell lysate was described. The lysate dialyzed against 0.0175 M phosphate buffer pH 6.3 was applied onto a CM-Sephadex column equilibrated with the same buffer. The elution was performed with the starting buffer and 0.1 M dibasic potassium phosphate containing 0.14 M NaCl. The hemoglobin fraction eluted with the second eluant was applied onto a DEAE-cellulose column and eluted with 0.2 M glycine containing 0.01 percent KCN, resulting in complete isolation of CA-C at high recovery rate. For the preparation in a large scale, the hemoglobin fraction prepared from CM-Sephadex semi-batch-type chromatography was treated with cold ethanol and chloroform. The purity of these preparations was confirmed by polyacrylamide gel disc electrophoresis and immunoelectrophoresis.

Animals↗
PubMed1978

Comparative vasodilator effects of nitroprusside, phentolamine, and nitroglycerin on hemodynamics, regional myocardial function and epicardial electrogram in dogs with acute myocardial ischemia.

The effects of nitroprusside (NP), phentolamine (PH), and nitroglycerin (NTG) were studied on systemic hemodynamics, regional contraction and epicardial ST segment in the border and non-ischemic zones of the left ventricle of anesthetized open chest dogs. The anterior descending coronary artery (LAD) was completely occluded. NP (5 microgram/Kg/min) or PH (100 microgram/Kg/min) was drip-infused, or a bolus injection of NTG (20 microgram/Kg) was administered intravenously. The 3 vasodilator agents produced somewhat similar reductions in systemic arterial pressure. However, NP caused a greater reduction in total peripheral resistance (TPR) than in left ventricular end-diastolic pressure (LVEDP), and caused a decline, in the ischemic marginal zone, in both ST segment eievation and paradoxical systolic lengthening. PH decreased TRP without reducing LVEDP and elevated the ST segment. NTG markedly reduced LVEDP and TPR slightly. NTG improved the elevated ST segment and paradoxical systolic expansion of the segmental myocardium in the border zone. Cardiac output rose with NP and PH, whereas injected NTG caused a reduction in cardiac output. These findings suggest that NP favourably affects the ischemic myocardium mainly by reducing the afterload and that the NTG-induced improvement of myocardial ischemia can be attributed mainly to preload reduction, while PH enhances cardiac function with slight or no improvement of myocardial ischemia in the border zone.

Acute Disease↗
PubMed1978

Effect of myocardial ischemia and nitroglycerin on systolic time intervals in the segmental myocardium.

Effects of ischemia and nitroglycerin on systolic time intervals in the segmental myocardial length were studied in anesthetized open-chest dogs. Two strain-gauges were sutured on the surface of the left ventricular wall; one was in the central area perfused by the left circumflex coronary artery (LCX) and the other was in the area perfused by the left anterior descending coronary artery. LCX was partially occluded with a screw type constrictor to the degree at which reactive hyperemia after the transient total coronary occlusion almost disappeared. After the hemodynamics stabilized nitroglycerin (20 microgram/kg) was injected into the femoral vein. In the ischemic area, contraction time was shortened and precontraction time was prolonged in association with an elongation of end-systolic and early systolic segment-length, respectively. The systolic time intervals in the ischemic segment were improved as a result of the recovery in the segment-length toward the control. The results suggest the usefulness of analyzing the segmental myocardial systolic time intervals for verifying the asynchronous contraction of the ventricle and the favourable effects of nitroglycerin on segmental myocardial function in the ischemic area.

Animals↗
PubMed1978

Correlation of systolic time interval with abnormal myocardial contraction by coronary occlusion in anesthetized open-chest dogs.

The correlation between the systolic time interval and abnormal contraction in ischemic myocardium was studied in anesthetized open-chest dogs. A strain-gauge was sutured on the surface of the left ventricular wall perfused by the left anterior descending coronary artery (LAD) for measuring segment-length. The left ventricular stroke volume decreased progressively after occlusion of LAD. The left ventricular ejection time (LVET) was progressively shortened in close correlation with the elongation of segment-length at the onset of isometric relaxation in 20 seconds after LAD occlusion when early systolic myocardial contraction and isometric contraction time (ICT) were not affected. ICT was gradually prolonged and closely related with the lengthening of the early systolic segment-length, while LVET recovered toward the control level in spite of further decrease in stroke volume. A close relationship was observed between ICT/LVET and stroke volume (gamma = 0.76, P less than 0.01). The results suggested the possibility that LVET was normalized even when the left ventricular function was impaired, and ICT/LVET ratio was the most sensitive index of LV dysfunction.

Animals↗
PubMed1978

Effect of propranolol on regional myocardial function in anesthetized open-chest dogs with myocardial ischemia.

Effects of propranolol on ischemic segmental function were studied in anesthetized open-chest dogs. Two segment-length gauges were used for measuring the regional myocardial function: one was sutured on to the left ventricular surface perfused by the anterior descending coronary artery (ischemic zone) and the other was on to that perfused by the circumflex coronary artery (normal zone). A bolus of propranolol (0.5 mg/kg) was injected into the right femoral vein. Five min later, the left anterior descending coronary artery (LAD) was completely occluded for one mine and thereafter released. Then a second coronary occlusion for 20 min was performed; an interval of 20 min was allowed between two occlusions. Propranolol, in the ischemic segment, apparently decreased the extent of paradoxical lengthening in the late systole following one min LAD occlusion, and facilitated improvement of segmental function after release of the occlusion. Moreover, the extent of abnormal stretching induced by 20 min occlusion during early systole, was also reduced by propranolol pretreatment. In contrast, compensatory increase in shortening by the normal segment was disturbed by propranolol. These results suggest that propranolol might exert a favourable influence on the segmental myocardial function during either transient or maintained myocardial ischemia.

Animals↗