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Biomedical subjects

T Ban

Publications and source records attributed to T Ban.

At least 199 records · Page 11Linked to original sources
PubMed1987

Clinical application of atrial natriuretic polypeptide in patients with congestive heart failure: beneficial effects on left ventricular function.

Synthetic alpha-human atrial natriuretic polypeptide was infused in patients with congestive heart failure (CHF) (New York Heart Association class III or IV) and in those without CHF. The infusion of atrial natriuretic polypeptide (ANP) at a rate of 0.1 microgram/kg/min significantly decreased pulmonary capillary wedge pressure and increased stroke volume index in all of the patients with CHF, whereas it decreased pulmonary capillary wedge pressure but caused no significant change in stroke volume index in the patients without CHF. Concomitant significant reductions in total systemic resistance were observed in both groups of patients. The ANP infusion significantly increased the urine volume, the excretion of sodium, and endogenous creatinine clearance in the patients without CHF. In the patients with CHF, it also showed a tendency to increase all these variables, but the urine volume did not correlate with the reduction in pulmonary capillary wedge pressure. The ANP infusion also decreased plasma aldosterone concentrations in these patients, although no significant difference was observed in the decrement of the plasma aldosterone concentration in the patients with and those without CHF. These findings indicate that the ANP infusion improves left ventricular function in patients with CHF, and suggest that this improvement results mainly from the vasodilating activity of ANP.

Adult↗
PubMed1987

A sandwich enzyme immunoassay of an adenocarcinoma-associated antigen, YH206, in cancer sera.

A sandwich enzyme immunoassay was established to measure an adenocarcinoma-associated antigen (antigen YH206) detected by monoclonal antibody YH206. Levels of antigen YH206 exceeding the cut-off value (25 U/ml) were found in the following percentages of 163 patients with various cancers: stomach cancer 37.2%, colon cancer 14.8%, pancreas cancer 43.3%, common bile duct cancer 28.6%. In contrast, only one out of 33 (3.0%) healthy donors and 7 of 104 (6.7%) patients with benign diseases had slightly elevated levels of the antigen. As regards the relationship between antigen YH206 levels and clinical stages, abnormally high levels of the antigen were found in the following percentages of 29 patients with stomach cancer: stage I 16.7%, II 0%, III 42.9% and IV 54.5%. Serial monitoring of antigen YH206 in two patients with cancer revealed that the level of the antigen increased as the disease progressed. It was also found that perchloric acid treatment of serum might be useful to decrease any false-positive reactions.

Adenocarcinoma↗
PubMed1986

Effects of tetraethylammonium on the action potential duration as modified by catecholamine-releasing action in guinea-pig papillary muscles.

The mechanism whereby tetraethylammonium ion (TEA) prolongs the action potential (AP) was examined by standard microelectrode techniques in papillary muscles isolated from nonreserpinized and reserpinized guinea-pig hearts. First, effects of 5 and 10 mmol/l TEA on steady-state AP parameters, i.e. the maximum rate of rise of AP (Vmax), AP amplitude, AP duration and resting potential, were examined at stimulation rates of 0.1 to 5 Hz. Second, effects of 5 and 10 mmol/l TEA on nonsteady-state AP parameters, i.e. the recovery processes of Vmax, AP duration and overshoot, were examined by introducing premature responses with various diastolic intervals between the basic stimulation rate of 0.1 Hz. TEA prolonged the AP more in the nonreserpinized preparations than in the reserpinized ones at all stimulation rates. In both preparations, this prolongation of the AP was greater at lower rates (0.1-1 Hz) than at higher rates (2-5 Hz), but the ratio of TEA-treated AP duration to control one was almost the same at all stimulation rates. TEA slowed the recovery process of AP duration in the nonreserpinized preparations, but not in the reserpinized ones. TEA had no effects on the recovery processes of Vmax and overshoot in both preparations. These results suggest that: TEA modifies its intrinsic prolonging action of the AP by releasing norepinephrine from sympathetic nerve terminals; TEA prolongs the AP by reducing the time-independent outward current rather than the time-dependent outward current; and a TEA-sensitive current does not effectively contribute to the total ionic current at the time of Vmax.

Action Potentials↗
PubMed1986

Effects of bucumolol, nadolol and nifenalol on maximum upstroke velocity of action potential in guinea pig papillary muscles.

The effects of bucumolol (BUC), nadolol (NAD) and nifenalol (NIF) on contractile forces and on action potentials (APs) were investigated in isolated guinea pig atrial and papillary muscles, respectively. Log 1/ED40 values for the negative inotropic effects of these drugs were 0.097, 10 and 0.74 mmol/l in this order. BUC (50 mumol/l), NAD (0.5 mmol/l) and NIF (0.2 mmol/l) produced about 60, 20 and 20% reduction of Vmax at 1 Hz. The frequency-dependent reductions at these and higher concentrations were greatest for BUC, intermediate for NAD and least for NIF. These potencies at certain frequencies were, as a whole, consistent with log P-potency relationship established in our previous papers (Harada et al. 1981; Ban et al. 1985). The reductions of Vmax in APs in response to premature stimuli during basic stimuli at the rate of 0.25 or 0.027 Hz decayed exponentially during diastolic intervals (DI). The time constants of these decay process (tau) estimated by linear and nonlinear regression analyses and by eye were 12.2-9.6 s for BUC (50-100 mumol/l) and 2.9-4.8 s for NAD (1-2 mmol/l) and 57-87 ms for NIF (0.2-1 mmol/l). In terms of the molecular weight (MW)-log tau relationship (Ban et al. 1985), these tau values are within the 95% fiducial limit for BUC and NAD and deviated from the lower fiducial limit for NIF. The frequency-dependent reductions of Vmax by these drugs were explained in terms of a function of tau and the intercept Ao. Based on the study made by Cohen et al.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1986

The pharmacokinetics of alpha-human atrial natriuretic polypeptide in healthy subjects.

We have analysed the pharmacokinetics of alpha-human atrial natriuretic polypeptide (alpha-hANP) in healthy subjects, using a two-compartment open model following bolus intravenous injection. The plasma half-times for the fast and slow components were 1.7 +/- 0.07 min and 13.3 +/- 1.69 min respectively. V1 (the volume of the central compartment), VZ (volume of distribution) and VSS (volume of distribution at steady-state) were 5370 +/- 855 ml (89.5 +/- 14.3 ml X kg-1), 32000 +/- 4620 ml (533 +/- 77.0 ml X kg-1), and 11900 +/- 1530 ml (198 +/- 25.5 ml X kg-1) respectively. The mean plasma clearance was 1520 +/- 121 ml X min-1 (25.4 +/- 2.0 ml X min-1 X kg-1.

Adult↗
PubMed1986

Frequency-dependent effects of phenytoin on the maximum upstroke velocity of action potentials in guinea-pig papillary muscles.

Phenytoin, at 50 to 200 micrograms reduced the maximum upstroke velocity of action potentials (Vmax) with increases in frequency from 0.25 to 5 Hz and in the external potassium concentration [( K+]0) from 2.7 to 8.1 mM. The drug-induced shortening of action potential duration was evident at 0.25 to 2 Hz but little at 3 to 5 Hz. Time courses of recovery of Vmax was studied by applying premature responses between the conditioning responses at 1 Hz both in control and in drug-treated preparations. Concerning the time courses of the difference between the Vmax values before and after drug treatments at the same diastolic interval, with increases in drug concentrations the intercepts at APD90 were increased but the time constants were not changed or slightly decreased in 8.1 to 5.4 mM [K+]0, whereas they were increased in 2.7 mM [K+]0. To understand the kinetic behavior of this drug on sodium channels, rate constants for the interaction of phenytoin with three states of channels in terms of Hondeghem-Katzung model were estimated from the above experiments of Vmax. The model most consistent with the present experiments was that with an affinity for inactivated channels 20 times greater than that for resting channels and with a minor affinity for open channels. Phenytoin produced a delay in the time course of recovery of overshoot and action potential duration at 0 mV (APD0), suggesting an additional inhibition of the slow channel by this drug.

Action Potentials↗
PubMed1986

Cortical neurons projecting to the posterior part of the superior temporal sulcus with particular reference to the posterior association area. An HRP study in the monkey.

Corticocortical connections from the posterior association area to the posterior part of the superior temporal sulcal cortex (STs area) were studied in the monkey by means of retrograde axonal transport of horseradish peroxidase (HRP) or wheatgerm-agglutinin-conjugated HRP (WGA-HRP). After injecting 0.05-0.2 microliter of 50% HRP or 5% WGA-HRP into the STs area, labeled cells were examined in various cortical regions. The dorsal wall of the STs receives fibers mainly from the inferior parietal lobule (area 7) and superior temporal gyrus (area 22), whereas the ventral wall and floor part of the STs receive fibers from the posterior inferotemporal gyrus (area TEO) and prestriate cortex (areas 18 and 19). The deeper parts of the dorsal wall close to the floor region of the STs area also receive many fibers from the cortical walls surrounding the intraparietal, lunate and lateral sulci. Both the dorsal and ventral cortical walls of the intraparietal sulcus send fibers mainly to the deep dorsal wall of the STs. The ventral wall of the STs, on the other hand, receives fibers only from the ventral wall of the intraparietal sulcus. The medial surface of the prestriate cortex and the parahippocampal region send fibers to both walls of the STs. In the prestriate-STs projections originating from areas around the parieto-occipital sulcus, a topographic correlation is present; area 19 located anterior to the sulcus projects to the dorsal wall, whereas area 18 situated posterior to the sulcus projects to the ventral wall. Only the dorsal wall receives fibers from the cingulate (areas 23 and 24) and subparietal gyri (area 7). The deeper part of the dorsal wall and the ventral wall of the posterior STs area are interconnected with each other, while the upper part of the dorsal wall does not appear to receive fibers from the ventral wall.

Animals↗