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Biomedical subjects

A Yagi

Publications and source records attributed to A Yagi.

At least 91 records · Page 5Linked to original sources
PubMed1991

Negative brain potentials reflect the subjective distance between standard and deviant tones.

The purpose of this study was to examine the effects on event-related brain potentials (ERPs) of occasionally presented deviants in a sequence of tones. The sequence consisted of a series of frequent standard C5 tones from the diatonic musical scale, in which three deviants (F #5, C6, and F #6) and a target (C4) were occasionally embedded. Twenty subjects were asked to detect the target. The deviants elicited frontal N2. The amplitude of the N2 was smaller for C6 than for the other two deviants, whereas peak latencies increased as a function of the frequency distance between the deviant and the standard. The smaller N2 to C6 than that to the other deviants was considered to reflect closer subjective distance due to the octave relationship between C6 and the standard C5.

Adult↗
PubMed1990

Influence of intensity of illumination during the light period on diurnal variations of pineal indoles in rats and mice.

The diurnal variations of pineal indoles in New-Zealand Black (NZB) mice and Wistar rats were determined by HPLC fluorometry. Pineal N-acetylserotonin (NAc5HT) in NZB mice showed a marked diurnal variation, but no melatonin (MLT) was detected at any time of day or night. The night-time increases of NAc5HT in NZB mice and MLT in Wistar rats were delayed about one hour in animals kept under illumination of high intensity (2000 lux) during the light period (12 h) compared with those in animals kept under illumination of low intensity (10 lux). These results suggest that the intensity of illumination during the light period affects the diurnal rhythms of pineal indoles in experimental animals.

Animals↗
PubMed1990

Beneficial effect of tan-shen, an extract from the root of Salvia, on post-hypoxic recovery of cardiac contractile force.

The present study was undertaken to elucidate the possible effects of tanshinone VI, one of the extracts from the root of Salvia, on post-hypoxic recovery of cardiac contractile force. For this purpose, rat hearts were perfused for 45 min under reoxygenated conditions following 20-min hypoxic perfusion, and changes in tissue high-energy phosphates and calcium contents, and release of ATP metabolites and creatine kinase were examined. Post-hypoxic recovery of cardiac contractile force was augmented when hearts were treated with 42 nM tanshinone VI during hypoxia. This beneficial recovery was accompanied by enhanced restoration of myocardial high-energy phosphates, depression of hypoxia- and reoxygenation-induced increase in tissue calcium content, and suppression of release of ATP metabolites such as adenosine, inosine and hypoxanthine from the perfused heart. The results suggest that tanshinone VI is beneficial for the recovery of cardiac contractility after a certain period of oxygen-deficiency, possibly through mechanisms involving improvement of myocardial energy production upon oxygen-replenishment and/or inhibition of calcium accumulation in the cardiac cell.

Abietanes↗
PubMed1989

Possible active components of tan-shen (Salvia miltiorrhiza) for protection of the myocardium against ischemia-induced derangements.

Extract of Tan-Shen (Salvia miltiorrhiza, Labiatae), a Chinese traditional crude drug, was reported to show beneficial activity for heart disease. Chemical examination on the extract was performed on the basis of screening for protective action on the ischemic myocardium. Isolated hearts were subjected to hypoxic perfusion for 20 min, followed by 45 min reoxygenation, and the recovery of cardiac contractile force and changes in UV absorbance of the perfusate were examined. Among the components isolated, tanshinone I, cryptotanshinone, and tanshinone VI elicited a significant enhanced recovery of the contractile force upon reoxygenation. This was associated with a decrease in the increase in UV absorbance of the perfusate, suggesting the preservation of ATP metabolites in the myocardium. This, in turn, may enhance the restoration of ATP upon oxygen-replenishment. The results suggest that tanshinone I, cryptotanshinone, and tanshinone VI can protect the myocardium against ischemia-induced derangements.

Animals↗
PubMed1989

Production of tropane alkaloids by cultured cells of a Duboisia hybrid.

The production of scopolamine-rich calli was investigated by the quantification of tropane alkaloids in a gas chromatograph equipped with a flame thermoionic detector (FTD). Stem and leaf segments from a selected strain, M-II-8-6, a hybrid between Duboisia myoporoides R. Br. and D. leichhardtii F. Muell, were used for this experiment. Stem-derived callus subcultured for over one year in the dark on Murashige-Skoog (MS) medium containing 0.1 mg/l indole-3-acetic acid (IAA) produced hyoscyamine ane scopolamine with a yield of 0.006 and 0.005% dry weight, respectively. Leaves of shoot cultures did not show any detectable levels of alkaloids. However, the leaf callus subcultured for over one year in the dark on MS medium containing 0.1 mg/l IAA produced hyoscyamine and scopolamine with a yield of 0.007 and 0.009% dry weight, respectively. These results indicate that the ability to synthesize tropane alkaloids in stem- and leaf-derived calli can be maintained on MS medium containing IAA.

Cells, Cultured↗
PubMed1988

Copper-induced hypercholesterolemia of golden hamsters: enhanced synthesis of cholesterol in the liver.

Effects of a subtoxic dose of copper on cholesterol metabolism were studied in male golden hamsters. Intraperitoneal injections of cupric acetate increased serum levels of cholesterol and phospholipids without liver damage. This lipidemia was associated with increased cholesterol of the liver. The participation of hemolysis was denied by peripheral red blood cell tests. Hepatic microsomal 3-hydroxy-3-methyl-glutaryl-CoA reductase was also elevated by copper administration. Biliary secretion of cholesterol increased but that of bile acids remained unchanged, suggesting no impaired degradation of cholesterol. We conclude that hepatic synthesis of cholesterol is enhanced by a subtoxic dose of copper, resulting in hypercholesterolemia.

Animals↗
PubMed1988

An outbreak of foodborne hepatitis A in a factory: a possible shift in age of patients in Japan.

We investigated extensively an outbreak of hepatitis A at a factory in suburban Nagoya. Epidemiological study indicated a foodborne outbreak by a supplier of lunches. Serologically, all the employees younger than 30 years of age had been susceptible to hepatitis A virus, but the highest morbidity was observed in the 40-44 age group. The age difference in morbidity from foodborne hepatitis and susceptible populations suggests a shift in mean patient age linked to a shift in antibody prevalence to hepatitis A virus. In communities where the prevalence started shifting after development of sanitary systems, effective prophylaxis for foodborne hepatitis A will be necessary to prevent the disease in an increasing number of older patients in a few decades.

Adult↗
PubMed1988

Effect of exercise on circulating atrial natriuretic peptide and left ventricular ejection fraction in healthy persons and patients with coronary artery disease.

Radionuclide angiographic measurements of left ventricular ejection fraction were performed at rest and during exercise in 10 normal persons and 11 patients with coronary artery disease. Exercise was continued on a supine bicycle exercise table up to a symptom-limited maximum. Plasma levels of atrial natriuretic peptide (ANP) were also determined at rest and during exercise. Ejection fraction in the normal volunteers was 59 +/- 3% (mean +/- SEM) at rest and increased significantly (p less than 0.01) to 69 +/- 3% during exercise. Ejection fraction in the patients was 47 +/- 5% at rest and did not change significantly during exercise (51 +/- 7%). Plasma ANP in the normals rose significantly (p less than 0.01) from 62 +/- 16 pg/ml at rest to 454 +/- 94 pg/ml during exercise. Plasma ANP in the patients also rose significantly (p less than 0.01) from 231 +/- 102 pg/ml to 794 +/- 170 pg/ml. The response of plasma ANP to exercise was enhanced significantly (p less than 0.05) in the patients as compared with the normals in relation to ejection fraction by analysis of covariance. In both the normals and the patients, plasma ANP was inversely and significantly correlated with ejection fraction during exercise (r = -0.46, p less than 0.05, n = 21), however, not at rest. Because it has been reported that plasma ANP is correlated positively with pulmonary artery wedge pressure, the estimation of plasma ANP during an exercise stress test might be used for the evaluation of cardiac reserve in coronary artery disease.

Adult↗
PubMed1988

Plasma levels of atrial natriuretic peptide in patients with borderline and essential hypertension.

Plasma levels of atrial natriuretic peptide (ANP) were measured in outpatients with borderline hypertension (n = 15) and essential hypertension (n = 13) and in normotensive subject (n = 11). There were no significant differences among the three groups in age, serum protein, albumin, or electrolyte levels, plasma renin activity (PRA), or plasma concentrations of aldosterone and cortisol. The plasma ANP levels in the normotensive, borderline hypertensive, and essential hypertensive subjects were 36 +/- 6 pg/ml (mean +/- S.E.), 64 +/- 11 pg/ml, and 82 +/- 14 pg/ml, respectively. The levels in the essential hypertensive subjects were significantly (p less than 0.05) higher than those in the normotensives. In both borderline and essential hypertensives (n = 28), the plasma ANP levels were significantly correlated positively with systolic blood pressure (r = +0.385, p less than 0.05), and negatively with PRA (r = -0.484, p less than 0.05) and serum total calcium (r = -0.516, p less than 0.01). These results suggest that the elevation of circulating ANP in hypertensives is involved in the pathogenesis of hypertension.

Adult↗
PubMed1987

Prostaglandins in enhanced pressor response in renal prehypertensive rabbits.

The role of prostaglandins (PGs) in the pressor response to norepinephrine (NE) was examined in one-kidney, one clip rabbits with renal artery stenosis for 3-day's duration (3-day clipped rabbits) and in sham operated rabbits with one-kidney without renal artery stenosis. An exaggerated pressor response to NE, 800 ng/kg/min, was observed in the 3-day clipped rabbits, and it was abolished by angiotensin II antagonist, [Sar1, Ile8] angiotensin II (AIIA). Treatment with indomethacin, 10 mg/kg, induced hyperresponsiveness to NE in the sham operated rabbits and also produced a further increase in the response in the 3-day clipped rabbits: the enhanced responses with similar levels were not attenuated by AIIA in both groups. A subdepressor dose of PGE2, 800 ng/kg/min, abolished the hyperresponsiveness in the 3-day clipped rabbits, while subdepressor or depressor dose of PGI2, 10 or 20 ng/kg/min did not, but the concurrent infusion of AIIA with PGI2 attenuated it. These results indicate that PGs, in particular PGE2 might be involved in the enhanced pressor response to NE in the 3-day clipped rabbits in addition to the altered renin-angiotensin system.

Angiotensin II↗
PubMed1987

Analyses on lipid-rich organelles of the rat liver after bile duct ligation.

A fraction of lipid-rich organelles of rat livers was analyzed to study the effect of bile duct ligation on lipid metabolism. The lipid fraction of the control rats consisted mainly of Golgi-derived dense bodies. Three days after the ligation, myelin-like figures and increased phospholipids and cholesterol were characteristic of the fraction. Two weeks ligation resulted in proliferation of lysosomal electron dense bodies. As their volume density expanded, phospholipids and cholesterol increased. Electrophoresis indicated a reduced rate of VLDL assembly after ligation. The Golgi-dominant phase is converted to the lysosomal phase in the heavy subfraction after the bile duct ligation. This subcellular change could be a consequence of secondary lipidosis: hepatocyte lysosomes have been exhausted in sorting accumulated lipids into secretory lipoproteins.

Animals↗
PubMed1987

Sentence verification and event-related brain potentials.

The purpose of this study was to examine whether the decision process affected scalp recorded event-related brain potentials (ERPs). ERPs were recorded while 10 subjects evaluated the veracity of four types of Japanese sentences; true-affirmative (TA), true-negative (TN), false-affirmative (FA), and false-negative (FN). Each sentence was presented visually, one word at a time in the following order: Subject (S); object (O); and verb (V). This order of words, which is normal in Japanese grammar, allowed the ERP waveforms associated with semantic mismatch between the S and O occurring in the middle of the sentence to be separated from those elicited by the decision concerning the sentence's truth or falsity occurring at the end of the sentence. Semantic mismatch was associated with a negative component (N310) following the O-word. In addition, P3s were elicited by sentence final words. Affirmative sentences elicited larger P3s than did negative sentences, and true sentences elicited earlier P3s than did false sentences. P3s were smaller in amplitude when they followed a mismatch between the S and O words. The result suggested that by using Japanese sentences, it may be possible to examine sentence-level rather than word-level processes.

Adult↗
PubMed1987

Specific suppression of antigen-antibody reactions by a dialysate from Dermatophagoides farinae.

Mite dialysate prepared from an extract of house dust mite, Dermatophagoides farinae, suppressed 48-h homologous passive cutaneous anaphylaxis (PCA) in rats caused by a non-dialyzable fraction of the mite extract (mite antigen), and the suppression was dose-dependent with a high specificity for the antigen. The mite dialysate itself slightly elicited the PCA. Fraction 3 obtained from the mite dialysate by means of DEAE-Sephadex A-25 column chromatography suppressed PCA in rats and guinea pigs more potently than mite dialysate. Histamine release from sensitized rat peritoneal exudate cells (PEC) induced by the mite antigen was suppressed in a dose-dependent manner when the PEC had been previously incubated with fraction 3. However, incubation of the PEC with fraction 3 caused a significant release of histamine compared to the spontaneous value. Fraction 3 clearly inhibited the passive hemagglutination of the mite antigen-conjugated sheep red blood cells caused by rat hyperimmunized serum. From these results it was considered that certain haptenic substances might be present in the mite dialysate.

Animals↗