Search PubMed⌕ Search

Biomedical subjects

T Ban

Publications and source records attributed to T Ban.

At least 235 records · Page 13Linked to original sources
PubMed1984

Immunocytochemical demonstration of caldesmon and actin in thyroid glands of rats.

The distribution of caldesmon (a calmodulin-binding, F-actin interacting protein; Sobue et al. 1982) and actin was studied in the rat thyroid gland by means of light-microscopic immunocytochemistry, and the fine-structural distribution of actin filaments was examined by use of heavy meromyosin (HMM). Caldesmon and actin were demonstrated in the apical cytoplasm of almost all the follicle epithelial cells in normal as well as TSH-treated animals. Immunoreactivities for both caldesmon and actin showed almost the same pattern in localization. The smooth muscle cells of the blood vessels were also positive for caldesmon and actin. By electron microscopy, numerous actin filaments decorated by HMM and running perpendicularly or randomly to the apical surface were recognized in the apical cytoplasm of the follicle epithelial cell. These results suggest that caldesmon and actin, in conjugation with calmodulin, play a role in the regulation of cellular activity such as exocytosis and endocytosis in the apical portion of the follicle epithelial cell.

Actins↗
PubMed1984

Chronic disease and depression in the geriatric population.

A brief review is given of the incidence and nature of psychiatric symptoms, particularly depression, that are associated with chronic physical diseases common in the elderly. A discussion of medical illnesses that mimic depression, and depression presenting as somatic disease, illustrates the challenge of differential diagnosis. Guidelines are presented for the treatment of depression in patients with central nervous system, cardiovascular, hepatic and renal, and gastrointestinal disorders. Pharmacokinetic factors relevant to the use of cyclic and monoamine oxidase inhibitor antidepressants in the elderly are reviewed.

Adjustment Disorders↗
PubMed1983

Effects of beta-adrenoceptor blocking agents of N-tertiary butyl derivatives on maximum upstroke velocity of action potential in guinea-pig papillary muscles.

The effects of bufetolol (27.8-138.9 mumol/l), bunitrolol (70.2-351.1 mumol/l), bupranolol (16.2-100 mumol/l), carteolol (60.7-607 mumol/l), D32 (17.3-100 mumol/l), penbutolol (1.5-29.4 mumol/l) and timolol (115.5 and 231.2 mumol/l) on action potentials were investigated in isolated guinea-pig papillary muscles. All these beta-adrenoceptor blocking agents of teritary butyl aminopropranol derivatives produced a concentration-dependent reduction of Vmax at driving rates of 1 Hz, 0.027 Hz and 4 Hz. The reduction was frequency-dependent but at all the rates penbutolol was highest in potency, as estimated by ED30 (0.027 Hz) and ED 50 values (1 and 4 Hz), followed by bupranolol, D-32, bufetolol and bunitrolol. These were followed in turn by timolol and carteolol in ED30 at 0.027 Hz and ED50 at 1 Hz, but by carteolol and timolol in ED50 at 4 Hz. Each log (1/ED) value is a linear function of log n-octanol/water partition coefficient (log P). The slope and intercept (the value at log P = 0) of the line of log (1/ED50) at 4 Hz are steeper and higher, respectively, than those of the lines at the other frequencies. The time course of recovery of Vmax during diastole was studied by assessing Vmax in premature responses at 0.027 Hz, being approximated by a single exponential function. The time constants of recovery (tau) and intercepts (Ao: the value extrapolated to the time of APD90 of the conditioning responses) at the level of ED50 and at 100 mumol/l of the drugs were thus estimated.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1983

Computer analysis of prolongation of cardiac action potential duration.

Using Beeler and Reuter's mathematical model of action potential in myocardial fibers, a similar extent of prolongation of action potential duration at -60 mV (APD -60) was produced at the infinite interval of stimulation by altering parameter values for slow inward current (is) time-independent (ik1) and time-dependent (ix1) outward currents. Among five types of prolongation of APD -60 thus produced, the plateau height is high in two types at this interval, but in three at a shorter interval. The degree of prolongation varies between these five types at this shorter interval. The stimulus interval-action potential duration (interval-duration) relation curves reflect changes in time-dependent parameters of these currents. Thus various types of APD prolongation may be distinguished from each other by the different behavior of action potentials at low and high frequencies of stimulation. ix1 increases by 40-fold at the moment of the maximum rate of depolarization at an interval of 330 msec, but is still negligibly small as compared with sodium current.

Action Potentials↗
PubMed1983

Surgical treatment for severe coronary heart disease--its indication and result.

There still remain several controversies in the treatment of severe coronary heart disease. We examined 147 patients who underwent surgery during the past 6 years. These patients were classified into the following 4 groups: 1) patients with serious mechanical complications, such as ventricular septal perforation and cardiac rupture, in the acute stage of myocardial infarction (11 patients), 2) unstable angina (45 patients), 3) those with congestive heart failure (15 patients) and 4) stable angina with left main trunk and/or triple-vessel disease (76 patients). Surgical mortality rates in each group were 45.5, 11.1, 6.6 and 3.9%, respectively. It was concluded: 1) In the patients with mechanical complications in acute myocardial infarction emergency surgery should be undertaken even in the acute stage, if cardiogenic shock has deteriorated despite the use of intraaortic balloon pumping. 2) The necessity of urgent surgery of patients with unstable angina who have severe organic lesions is self-evident. In some patients, however, coronary vasospasm played a significant role in its clinical manifestations and surgery at this stage was not satisfactory. Medical treatment should precede the surgery. 3) In patients with early symptoms of congestive heart failure surgery should be performed before heart failure ensues. 4) Results of the surgery for stable angina with left main trunk and/or triple-vessel disease were satisfactory.

Adult↗
PubMed1982

Negative inotropic effects of tiapamil (Ro11-1781) and verapamil in rabbit myocardium.

The effects of tiapamil (Ro11-1781) and verapamil on contractility were studied at 1 Hz in isolated rabbit left atrium and right ventricular papillary muscle. The ED50 of tiapamil for the depression of contractility was 33 and 18 times higher than that of verapamil in the former and latter tissue, respectively. In the presence of 100 microM of tiapamil or 10 microM verapamil, the positive staircase phenomenon in papillary muscle was reversed to a negative one. Also, the depression of contractility tended to be less in the first and second responses after a longer interruption of driving stimuli. Both drugs antagonized the inotropic effects of Ca2+ competitively and the pA2 for tiapamil was less than that for verapamil by 1.01. The potency ratios of tiapamil to verapamil for the contractility in this study correspond roughly with those found in clinical use.

Animals↗
PubMed1982

Central nervous system receptors in neuropsychiatric disorders.

1. Introduction of radioligand binding techniques has opened new possibilities in the study of the biological basis of psychiatric disorders. 2. The possible role of CNS receptors in schizophrenia, depression, anxiety, Huntington's disease and Alzheimer's dementia is discussed. 3. Data are presented in a systematic manner starting with the identification of receptors which appear to be the primary locus of action of drugs currently used in the treatment of these disorders. 4. A review of the data on the changes in receptor levels and/or affinity that might be associated with the respective disease follows. 5. Changes in receptor number and/or affinity after chronic drug therapy are outlined and the possible utilization of radioligand binding techniques in drug plasma level determination is discussed.

Aging↗
PubMed1982

Effects of disopyramide on the maximum rate of rise of action potential (Vmax) in guinea-pig papillary muscles.

The correlation between the steady state and non-steady state depression of Vmax by 50 microM disopyramide was investigated in 2.7, 5.4 and 8.1 mM [K+]o using isolated guinea-pig papillary muscles. An elevation of [K+]o from 2.7 to 8.1 mM strengthened the depressant action of the drug on Vmax (steady state) at 1 to 5 Hz, but attenuated this action at 0.05 and 0.1 Hz. The Vmax-membrane potential (Vm) relationship (steady state) was examined at stimulation rates of 0.1 and 1 Hz by increasing [K+]o from 2.7 to 19 mM. The drug shifted the normalized Vmax-Vm curve at 1 Hz in a hyperpolarizing direction, but shifted the curve at 0.1 Hz upward at Vm between -90 and -65 mV without a shift along the Vm axis. The recovery process of Vmax (non-steady state) was examined by introducing premature stimuli or by interrupting the basic stimulus of 1 Hz for a certain period. The control recovery processes in three [K+]o were approximated by a triple exponential function (the earliest, intermediate and latest components). The drug slowed the intermediate component, but accelerated the latest one (the earliest component was situated within the refractory period) of [K+]o attenuated the depressant action of disopyramide on the Vmax at 0.05 and 0.1 Hz and accelerated the recovery process of Vmax at long diastolic intervals of more than 10 sec was quite unique.

Action Potentials↗