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Biomedical subjects

K Yoshii

Publications and source records attributed to K Yoshii.

At least 109 records · Page 6Linked to original sources
PubMed1986

Synergistic effects of 5'-nucleotides on rat taste responses to various amino acids.

Synergism between 5'-nucleotides and L-amino acids in the rat taste nerve responses was investigated. The synergism was examined between low concentration of the nucleotides which induce only a negligibly small response and various concentrations of amino acids. A marked synergism was found between 5'-nucleotides and all the amino acids examined. Purine 5'-nucleotides such as GMP, deoxy GMP, GDP, GTP, AMP or IMP exhibited the synergistic effect on the responses to amino acids, while pyrimidine 5'-nucleotides such as CMP or UMP exhibited practically no synergistic effect. The presence of GMP led to a shift of the concentration-response curves for amino acids to a lower concentration region without affecting the response of the saturation level. These curves were analyzed under the assumption that there exist two types of receptor sites with different dissociation constants for each amino acid. The results suggest that GMP leads to a decrease in dissociation constants, especially for high affinity sites without affecting maximal responses. Monosodium glutamate (Glu) itself, which is known as a typical 'flavor potentiator', exhibited no enhancing effect on the responses to 4 primary taste stimuli. The mechanism of how Glu and the 5'-nucleotides 'potentiate' flavor of food is discussed.

Amino Acids↗
PubMed1986

Taste receptor mechanism of salts in frog and rat.

Salts carrying impermeable organic cations elicited large responses in the frog and rat taste nerves. Amiloride suppressed the responses of the frog and rat taste nerves to NaCl, KCl and the organic salts to a similar extent. The estimated equilibrium potentials for Na+ and K+ at the thresholds determined were more negative than the resting potentials of the taste cells. The results obtained suggest that the taste responses to salts including NaCl are not induced by entry of cations via apical membranes of taste cells.

Amiloride↗
PubMed1986

Estimation of exercise capacity from oxygen consumption in the recovery phase of submaximal exercise.

We analyzed the transient response of oxygen consumption (VO2) after the sudden termination of exercise. The study population consisted of 20 male athletes (age 13 to 15.9 years) and 87 male patients, 59 of whom (age 4.8 to 17.8 years) were considered to be normal subjects, and 28 of whom (age 6 to 14.8 years) had restricted physical activity because of underlying heart diseases (restricted group). The exercise tests were performed according to Bruce's protocol and terminated at signs of exhaustion. As soon as exercise ceased, the examinee sat on a chair and took rested completely. VO2 was measured every 30 seconds throughout the test. We characterized the rate of the initial decay of the VO2 transient as the ratio of the 30 second VO2 right after the exercise to that at the end of the exercise (Irv). This index did not differ significantly among the groups. On the other hand, Exc, the Irv normalized by the end-exercise VO2, was a sensitive index for separating the restricted group from the control and athlete groups. Should the Exc remain sensitive enough to quantify exercise capacity regardless of the intensity of the exercise imposed, even the submaximal exercise test should enable us to safely evaluate the exercise capacity of patients with impaired cardiac function.

Adolescent↗
PubMed1985

Direct estimation of cardiac reserve through analysis of relation between oxygen consumption and heart rate during exercise testing.

In order to elucidate fundamental relationship between exercise and cardiac reserve, we investigated the parameters of regression equation (VO2 = A X HR + B) between oxygen consumption (VO2 ml/kg/min) and heart rate (HR) during exercise test (Bruce). 62 male children were divided into 3 groups based on history and clinical evaluation. HR related linearly with VO2 (average r = 0.967, range 0.90-0.993). Both of the parameters A and [B] were significantly high in Athlete (A = 0.465 +/- 0.043, [B] = 36 +/- 6.07), low in Failed (0.297 +/- 0.055, 17.4 +/- 6.1) and middle in Ordinary group (0.366 +/- 0.078, 23.5 +/- 8.6) (p less than 0.005). Based on our result of linear VO2-HR relation, and on the previously reported studies that cardiac output linearly and consistently relates with VO2, we considered the meaning of the parameters as follows; A determines the possible maximum stroke volume (SV), and B determines the HR where SV reaches plateau. In conclusion, since the SV is considered as a measure of cardiac function, measuring the parameters of VO2-HR relation allows us to isolate cardiac functional reserve through the exercise tolerance test.

Adolescent↗
PubMed1985

Left ventricular diastolic pressure-volume and stress-strain relationship in children.

Diastolic pressure and volume (P-V) curves were approximately exponential and fitted the equation, dP/dV = aP + b, where a was left ventricular volume elastic constant. Stress and strain (sigma-epsilon) curves were expressed by the equation, d sigma/d epsilon = k sigma + c, where k was wall stiffness constant. These exponential curves have been fitted over the whole diastole, but theoretically, the mid-diastole should reflect diastolic elastic properties best. In the present study, therefore, special attention was paid to the mid-diastole in each patient, and both P-V and sigma-epsilon relationships were analyzed by fitting the data to the above mentioned curves during this period of time. This analysis was made in two separate groups of patients. One was the control group consisting of 2 patients with normal hearts, 2 patients with mild pulmonary stenosis, and 25 patients with post mucocutaneous lymph node syndrome. The other group consisted of patients with postoperative congenital heart disease, that is, 8 patients with atrial septal defect and 5 patients with tetralogy of Fallot. The elastic constant (a) could not be compared if the size of the hearts differed. The results of the present study, however, demonstrated that the size of the heart was closely related to the constant, a. In the control group, the constant (a) was exponentially related to the size of the heart, and expressed as follows: a = 0.30e-0.037EDV + 0.045 (r = 0.94, p less than 0.01) In contrast, the wall stiffness constant (k) was not related to the size of the heart. After surgical repair of congenital heart disease, the stiffness constant in the left ventricle was normal in patients with postoperative atrial septal defect, while it was significantly increased in patients with postoperative tetralogy of Fallot.

Cardiac Volume↗
PubMed1985

[A case of esophageal carcinoma with liver metastasis treated with cisplatin].

A patient with liver metastasis of esophageal carcinoma was treated with Cisplatin and showed complete response both in the esophageal region and liver metastasis. Combination chemotherapy using Cisplatin is now often employed against metastatic regions of epidermoid carcinoma of the esophagus, and shows certain degrees of response. Cisplatin is considered to be one of the most effective agents for the treatment of epidermoid carcinoma of the esophagus.

Carcinoma, Squamous Cell↗
PubMed1985

[Anti-platelet therapy in ischemic cerebrovascular disorder--clinical and hematological study].

Anti-platelet therapy (Aspirin 250 mg/every other day approximately 1000 mg/day + Dipyridamole 150 mg/day) was performed on 51 patients with ischemic cerebrovascular disorders (ICVD). Among these patients, 41 cases showed no recurrence of ICVD attack, whereas the remaining 10 cases had re-attacks. These 2 groups were compared from the viewpoint of various risk factors and other clinical findings: e.g. CT scan and angiographic appearance. But there was no statistically significant difference between them. Platelet aggregability and platelet survival time were examined in twenty-eight patients out of cases. We used a simple nonradioisotope technic for the determination of platelet survival time. Platelet survival time was shortened in 22 of 28 (79%) patients. On the other hand, platelet aggregability was found to have no definite tendency. In 9 of 10 cases, platelet survival time was revealed to be prolonged several months after administration of anti-platelet drugs. There was no re-attack in 7 of these 9 patients. Some reports also showed that platelet survival time was shortened in various thromboembolism and recovered by anti-platelet drugs. Measurement of platelet survival time is thought to be an important method as to the indication and the monitoring of anti-platelet therapy.

Adult↗
PubMed1984

Multiple receptor types for amino acids in the carp olfactory cells revealed by quantitative cross-adaptation method.

A quantitative method of cross-adaptation was developed to explore the difference in the receptor sites for various amino acids in the carp olfactory receptors. The olfactory responses were measured by recording the stimulant-induced waves from the olfactory bulb. Cross-adaptation was carried out by varying concentrations of amino acids in a wide range. Typical examples of the results obtained are as follows. The response to Thr after Ser was decreased with increasing concentration of Ser applied first and reached the spontaneous level, while that to Thr after Glu was decreased to 77% of the level of the original response with increasing Glu concentration and stayed this constant level with a further increase in Glu concentration. Application of the amino acids in the reverse order gave essentially similar results. Such types of experiments were carried out between various pairs of amino acids. The results obtained suggested that amino acids of very close species (e.g. Thr and Ser, Asp and Glu, Tyr and Phe) stimulate the same respective receptor sites and that amino acids of most other pairs stimulate more or less different receptor sites, although there exist the receptor sites stimulated commonly by both amino acids of one pair. It was concluded that the carp olfactory cells have many different receptor sites stimulated only by one species of amino acid and its close analogues.

Animals↗
PubMed1984

Physiological significance of the slope of the regression equation between oxygen consumption and heart rate in exercise testing.

The relationship between oxygen consumption (VO2) and heart rate (HR) was studied in 62 male children. Based on clinical evaluation and history, they were divided into three groups, i.e., athlete, ordinary and failed. There was a high linear correlation between HR and VO2 in each individual. The averaged values of the slope and standard deviations were 2.09 +/- 0.189 in the athlete group (n = 17), 2.60 +/- 0.140 in the ordinary group (n = 16) and 3.17 +/- 0.591 in the failed group (n = 29). The statistical differences were confirmed among the groups (p less than 0.005). The results suggested that the slope of the HR vs. VO2 relation was related to an inotropic state of cardiac function. We concluded that the slope was a more suitable and more direct evaluation of cardiac function during exercise. Moreover, the method was non-invasive and safe because it required no potentially hazardous maximum work load for the patients.

Child↗
PubMed1983

Ion dependence of the eel taste response to amino acids.

The effects of changed ionic environments on the taste responses to amino acids were examined by recording the activity of the palatine nerve. The responses to glycine, L-proline and L-arginine dissolved in deionized water were greatly reduced after ions were removed from the surface of the palatine epithelium by treatment with 5 mM EDTA. The addition of various species of salts to amino acid solutions caused reversible recovery of the responses. The response to 0.1 mM glycine increased with an increase in salt concentration in amino acid solutions and reached saturation level. The effects of salts of divalent cations (CaCl2 and MgCl2) appeared at much lower concentration (10(-7) M) than those of salts of monovalent cations (NaCl and KCl) (10(-4) M), suggesting that cations support the taste response. All the organic cations examined, including those of large molecular weights (choline, Tris, bis-Tris, bis-Tris propane, tetraethylammonium, triethanolamine and D-glucosamine), also supported the taste responses. The results obtained led to a conclusion that not a specific cation but various species of cations can support the eel taste responses. It is suggested that the cations do not act as current carrying ions to depolarize the taste cells but that the binding of the cations to the receptor membrane plays an essential role in taste reception.

Amino Acids↗
PubMed1983

Mechanism of the water response in carp gustatory receptors: independent generation of the water response from the salt response.

The carp gustatory responses to various salts and those to distilled water after adaptation of the receptors to the salts were recorded from the palatine nerve under varying conditions. (a) As far as Na4Fe(CN)6 solution prepared freshly was used, any peak in the dose-response curve was not observed, while the solution stored overnight induced a large peak response at the low concentration region as Konishi reported. The magnitude of the water response after adaptation to the stored solution was practically equal to that after adaptation to the fresh solution, suggesting that the receptor site for the water response is different from that for the dilute salts. (b) The responses to salts depended largely on the species of both cations and anions of the salts. The responses were deceased with an increase in the lyotropic number of the anions and increased with an increase in the number above 11. The response to distilled water was practically independent of the species of both monovalent cations and anions of the salts used for the adaptation. The pH dependence of the response to 10 mM NaCl was largely different from that to distilled water after adaptation to 10 mM NaCl. (c) The water response was suppressed by the presence of electrolytes in stimulating solution; the data obtained with different species of salts were described by a single curve as a function of the ionic strength. (d) The mechanism to explain how distilled water leads to depolarization of the taste cell was discussed in terms of the electric double-layer potential.

Animals↗
PubMed1983

Role of cations in olfactory reception.

The effects of changed ionic environments on the olfactory responses in the carp, the rainbow trout, and the bullfrog were examined by recording the stimulant-induced waves from the olfactory bulb. (a) Application of stimulants (various species of amino acids and beta-ionone) dissolved in deionized water to the EDTA-treated olfactory epithelium of the carp did not induce any response. The addition of various species of salts to the stimulating solution reversibly restored the response. (b) The responses of the carp to L-alanine in the presence of MgCl2 and MgSO4 and those in the presence of KCl and K4Fe(CN)6 are described by single curves, respectively, as a function of concentration of the cations, suggesting that the cations support olfactory reception. (c) All the inorganic cations examined (Li+, NH3+, K+, Ca2+, Mg2+, Co2+, Mn2+, Cd2+) and organic cations (Tris+, choline+, bis-Tris propane2+) were effective to support the response of the carp, whereas TEA+, TBA+, triethanolamine+, and bis-Tris+ were ineffective. (d) The olfactory responses of the rainbow trout and the bullfrog were also reduced by removal of ions from the surface of the epithelia and recovered by addition of ions. (e) It is suggested that the cations do not act as current carriers across the apical olfactory cell membrane for the generation of the receptor potential.

Amino Acids↗
PubMed1982

High sensitivity of Xenopus gustatory receptors to amino acids and bitter substances.

The gustatory nerve responses of the aquatic toad Xenopus laevis to salts, acids, amino acids, and bitter substances were recorded. 1) The gustatory receptors were sensitive to amino acids and bitter substances. The thresholds were 10(-7) M for Arg, 3 X 10(-9) M for strychnine, and 3 X 10(-8) M for quinine, 200-20,000 times lower than the thresholds for the respective stimuli in the bullfrog. 2) The basic and the neutral amino acids were effective whereas the acidic ones were not. Relations between the responses and log stimulus concentrations for the basic amino acids were linear in a wide concentration range whereas those for the neutral ones were of S shape. Cross-adaptation did not occur among pairs of a basic amino acid and a neutral one. 3) Responses to the basic amino acids and the basic bitter substances were suppressed by the addition of salts to the stimulating solutions, while those to the neutral and the acidic substances were not suppressed.

Amino Acids↗
PubMed1981

Selective enhancement and suppression of frog gustatory responses to amino acids.

Properties of the receptor sites for L-amino acids in taste cells of the bullfrog (Rana catesbeiana) were examined by measuring the neural activities of the glossopharyngeal nerve under various conditions. (a) The frogs responded to 12 amino acids, but the responses to the amino acids varied with individual frogs under natural conditions. The frog tongues, however, exhibited similar responses after an alkaline treatment that removes Ca2+ from the tissue. The variation in the responses under natural conditions was apparently due to the variation in the amount of Ca2+ bound to the receptor membrane. (b) The responses to hydrophilic L-amino acids (glycine, L-alanine, L-serine, L-threonine, L-cysteine, and L-proline) were of a tonic type, but those to hydrophobic L-amino acids (L-valine, L-leucine, L-isoleucine, L-methionine, L-phenylalanine, and L-tyrptophan) were usually composed of both phasic and tonic components. (c) The properties of the tonic component were quite different from those of the phasic component: the tonic component was largely enhanced by the alkaline treatment and suppressed by the acidic treatment that increases binding of Ca2+ to the tissue. Also, the tonic component was suppressed by the presence of low concentrations of salts, or the action of pronase E, whereas the phasic component was unchanged under these conditions. These properties of the phasic component were quite similar to those of the response to hydrophobic substances such as quinine. These results suggest that the hydrophilic L-amino acids stimulate receptor protein(s) and that the hydrophobic L-amino acids stimulate both the receptor protein and a receptor site similar to that for quinine. (d) On the basis of the suppression of the responses to amino acids by salts, the mechanism of generation of the receptor potential is discussed.

Amino Acids↗
PubMed1981

Taste transduction mechanism: similar effects of various modifications of gustatory receptors on neural responses to chemical and electrical stimulation in the frog.

Responses in the frog glossopharyngeal nerve induced by electrical stimulation of the tongue were compared with those induced by chemical stimuli under various conditions. (a) Anodal stimulation induced much larger responses than cathodal stimulation, and anodal stimulation of the tongue adapted to 5 mM MgCl2 produced much larger responses than stimulation with the tongue adapted to 10 mM NaCl at equal current intensities, as chemical stimulation with MgCl2 produced much larger responses than stimulation with NaCl at equal concentration. (b) The enhansive and suppressive effects of 8-anilino-1-naphthalenesulfonate, NiCl2, and uranyl acetate on the responses to anodal current were similar to those on the responses to chemical stimulation. (c) Anodal stimulation of the tongue adapted to 50 mM CaCl2 resulted in a large response, whereas application of 1 M CaCl2 to the tongue adapted to 50 mM CaCl2 produced only a small response. This, together with theoretical considerations, suggested that the accumulation of salts on the tongue surface is not the cause of the generation of the response to anodal current. (d) Cathodal current suppressed the responses induced by 1 mM CaCl2, 0.3 M ethanol, and distilled water. (e) The addition of EGTA or Ca-channel blockers (CdCl2 and verapamil) to the perfusing solution of the lingual artery reversibly suppressed both the responses to chemical stimulus (NaCl) and to anodal current with 10 mM NaCl. (f) We assume from the results obtained that electrical current from the microvillus membrane of a taste cell to the synaptic area supplied by anodal stimulation or induced by chemical stimulation activates the voltage-dependent Ca channel at the synaptic area.

Anilino Naphthalenesulfonates↗
PubMed1980

Left ventricular performance and compliance following acute febrile mucocutaneous lymphnode syndrome.

Right and left heart catheterizations and biplane cineangiographies were performed on 115 post-MCLS cases to study the left ventricular performance and compliance, and the following conclusions were obtained: 1) The left ventricular performance of the post-MCLS cases with macroscopic cardiac lesions such as coronary aneurysms and stenosis declined compared with the others. 2) The left ventricular contractility of the post-MCLS cases without macroscopic cardiac lesions were within normal limits. 3) The diastolic compliance of the post-MCLS cases seemed to be decreased but the value could be regarded as normal for children.

Child↗