Biomedical subjects

T Ban

Publications and source records attributed to T Ban.

At least 145 records · Page 8Linked to original sources

PubMed1990

Atrial pacing stimulates secretion of atrial natriuretic polypeptide without elevation of atrial pressure in awake dogs with experimental complete atrioventricular block.

To clarify whether or not tachycardia stimulates the secretion of atrial natriuretic polypeptide (ANP) without elevation of atrial pressure, we examined the effects of atrial pacing on ANP secretion in awake dogs with normal sinus rhythm and with complete atrioventricular block (CAVB), which was produced surgically by heat cauterization of His' bundle. In four dogs with normal sinus rhythm, atrial pacing increased the atrial rate from 146 +/- 20 to 260 +/- 10 beats/min, with marked elevation of right atrial pressure (from 0.2 +/- 0.1 to 3.9 +/- 0.8 mm Hg) and left atrial pressure (from 0.2 +/- 0.1 to 8.6 +/- 2.8 mm Hg). Along with the hemodynamic changes, the ANP level in plasma obtained from the coronary sinus was increased from 405 +/- 99 to 849 +/- 199 pg/ml (p less than 0.01). In five dogs with CAVB, the ANP level was also significantly increased from 730 +/- 82 to 1,137 +/- 35 pg/ml (p less than 0.01) by rapid atrial pacing (from 164 +/- 20 to 317 +/- 30 beats/min) in spite of the lack of any appreciable changes in either left or right atrial pressure. Furthermore, in the CAVB group, while the ventricular rate was increased by ventricular pacing from 52 +/- 5 to 146 +/- 16 beats/min, atrial pacing was performed simultaneously without atrioventricular (A-V) sequential form. Even under this condition, the ANP level was increased from 480 +/- 172 to 626 +/- 223 pg/ml (p less than 0.05) without any substantial changes in atrial pressure. Such effects of rapid atrial pacing on ANP secretion were suppressed after infusion of autonomic blocking agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

The participation of sterol carrier protein2 in cholesterol esterification in rat adrenal microsomes.

The effect of sterol carrier protein2 (SCP2) purified from rat liver on the formation of cholesterol esters by acyl-CoA: cholesterol acyl-transferase (ACAT: EC 2.3.1.26) in rat adrenal microsomes was studied. The rate of incorporation of [1-14C]oleoyl-CoA into cholesteryl oleate was determined in the presence or absence of exogenously added cholesterol or SCP2, or both. The addition of SCP2 had no effect on the formation of cholesterol esters from endogenous cholesterol by ACAT in rat adrenal microsomes. In contrast, the formation of cholesterol esters from exogenous cholesterol by ACAT was dose-dependently increased by the addition of SCP2. These experiments showed that SCP2 had an enhancing effect on cholesterol esterification by ACAT in rat adrenal microsomes most likely by modulating the availability of exogenous cholesterol and that SCP2 may participate in the formation of cholesterol esters in the rat adrenal gland.

Adrenal Cortex↗

PubMed1990

[Problems in patients with use of a ventricular assist device].

The purpose of the present study was to review the results obtained in patients with a ventricular assist devices (VAD) in our hospital, and to discuss various problems concerning a VAD use, such as indications, right ventricular failure, and evaluation of cardiac function. Fourteen VADs were applied to 11 patients for left ventricular assist, including two for right ventricular assist and for one as biventricular assist with a VAD in the left and a biopump in the right. The clinical diagnoses of the patients were as follows: 10 ischemic heart disease, two valvular disease, one acute aortic dissection, and one corrected transposition of the great arteries. VADs were indicated in 11 patients because of difficulty in weaning from cardiopulmonary bypass (CPB), and in three patients because of cardiogenic shock after discontinuing CPB. Among the 14 patients, 11 had an effective VAD, six were successfully weaned from a VAD, and two survived. The VAD was ineffective due to uncontrollable bleeding and improper indications for the device, as in applying a one-sided heart assist when a biventricular assist was necessary. In spite of an effective VAD, five patients could not be weaned from VAD because of brain damage, sepsis, and hypoxia. After removing a VAD, four patients died; one due to mediastinitis, two due to respiratory failure, and one due to low output syndrome. All the four patients had renal failure followed by multi-organ failure finally, because of prolonged CPB time. The CPB time was shorter among the long survivors than in others. Cardiac function during assist and the weaning probability from a VAD were evaluated not only by the so-called on-off test, but also by transesophageal Doppler echocardiography. Ventricular wall motion and pulmonary venous flow pattern were analyzed by transesophageal Doppler echocardiography. The pattern of monophasic forward flow in the pulmonary vein was associated with reduced wall motion during deteriorated cardiac function, while the flow pattern became biphasic as cardiac function recovered. From these results, we concluded as follows: 1. Early decisions as to whether VAD is indicated are important. 2. A right VAD should be considered in cases with biventricular failure, during left ventricular assist, if right atrial pressures elevated more than 18 mmHg constantly. 3. The evaluation of cardiac function by transesophageal Doppler echocardiography is useful for making decisions as to wean patients from a VAD.

Adolescent↗

PubMed1990

[Transesophageal Doppler echocardiography in the diagnosis of atrial septal defect].

To assess the usefulness of transesophageal Doppler echocardiography (TEE) in diagnosing atrial septal defect (ASD), we studied eight cases with secundum type ASD, in which the diagnosis was confirmed by cardiac catheterization and surgery. In all cases, TEE provided clear images of the interatrial septum with its defect. Shunt flow through the defect was observed by color Doppler technique, and its velocity was measured using the FFT mode. In two cases, right-to-left shunt blood flow was detected. Two types of probes were used in this study, a lateral scanning probe and a longitudinal scanning probe. The scanning plane of the former was perpendicular to the axis of the probe, and that of the latter was parallel to it. The two probes facilitated the measurement of the two right-angled dimensions, with which we could calculate the defect area, assuming the defect to be an ellipse. The volume of a left-to-right shunt was obtained by multiplying the defect area by the integration of flow velocity against time. Shunt volume per cardiac cycle obtained by this method correlated well with that obtained by the Fick's method during cardiac catheterization. In six cases without a right-to-left shunt, the coefficient of correlation was 0.98, and in all eight cases it was reduced to 0.72. Thus, we concluded that TEE is useful for diagnosing and evaluating ASD.

Adolescent↗

PubMed1990

[Clinical usefulness of transesophageal Doppler echocardiography].

The usefulness of transesophageal Doppler echocardiography (TEE) was assessed in patients with various cardiovascular diseases including 15 patients with dissecting aortic aneurysm (DAA), two with thoracic aneurysm, 16 with ischemic heart disease and 14 with acquired valvular diseases. In dissecting aortic aneurysms, TEE provided clear images of the intimal flaps even in the aortic arch and descending aorta in which clear images could not be obtained by conventional external Doppler echocardiography. The entry site was detected in 11 of the 15 (73%) cases using TEE, but in only three of the 15 cases using conventional Doppler technique. In two cases of true aortic aneurysms, TEE provided clear images of the aneurysm in the descending thoracic aorta, which was discriminated precisely from DAA. In valvular disease, all four valves (aortic, pulmonary and atrio-ventricular valves) were easily observed without disturbance by any other tissues using a transesophageal approach. In addition, valve aneurysms in the posterior mitral leaflets were detected using TEE in two cases. In two cases of mitral stenosis, a thrombus was observed in the left atrial appendage. These findings were confirmed during surgery, but could not be obtained by the conventional external studies. In 16 cases, TEE was performed during aorto-coronary bypass surgery under general anesthesia. In two of these cases, left ventricular assist devices were applied after surgery. In these cases, where conventional Doppler echocardiography was not applicable, cardiac function could be monitored by TEE. Thus, TEE is useful not only in evaluating morphological function in the cardiovascular system but also in monitoring cardiac hemodynamics during and after heart surgery.

Adult↗

PubMed1990

Significance of fill-in after thallium-201 reinjection following delayed imaging: comparison with regional wall motion and angiographic findings.

To identify reversible defects, reinjection of a small amount of thallium-201 (201Tl) following 3-hr delayed imaging was performed in 60 patients with coronary artery disease who had perfusion abnormalities on their post-exercise 201Tl images. Thallium-201 uptake was visually scored and judged as normal (Group 1), reversible defect (Group II), new fill-in after reinjection (Group IIIa) and no fill-in even after reinjection (Group IIIb). New fill-in after reinjection was observed in 27 segments of the 85 segments (32%), showing persistent defect on the stress and delayed images. The wall motion in Group IIIa was worse than Group II but better than Group IIIb. Group IIIa showed Q-wave on ECG more often (69%) than Group II (27%) (p less than 0.01), but less often than Group IIIb (85%) (p less than 0.05). These data indicate that the reinjection 201Tl imaging often identifies new fill-in in the areas of no redistribution on the delayed images and it may hold promise for assessing tissue viability which the conventional imaging may underestimate.

Adult↗

PubMed1990

[Long-term results after total correction of tetralogy of Fallot].

One hundred sixty-two patients underwent total correction of tetralogy of Fallot from 1962 to 1979. 130 of these were hospital survivors. We studied the current status of the hospital survivors by questionnaires which were sent to 93 patients. An excellent long-term result was maintained by 87.3% of the 63 hospital survivors who answered to the questionnaires. Although there was a trend toward a higher incidence of symptoms in patients with a higher late postoperative RV/LV pressure ratio and in patients with older age at repair, it did not reach statistical significance. Six patients in this series have undergone reoperation. The most common cardiac problem which required reoperation was residual of the VSD. There was one late sudden death postoperatively. The RV/LV pressure ratio of the patient was 0.7 and the electrocardiogram at rest showed no abnormality except CRBBB. The ventricular dysarrhythmia was supposed as the cause of sudden death. The patients who underwent total correction of tetralogy of Fallot should be followed up by exercise ECG or 24 hours electrocardiographic monitoring.

Adolescent↗

PubMed1990

[Effects of lidocaine and its metabolite, monoethylglycine xylidide (MEGX), on transmembrane action potentials in guinea-pig papillary muscles].

Effects of lidocaine 5, 10, 20 micrograms.ml-1 and its metabolite, MEGX 5, 10, 20 micrograms.ml-1, on transmembrane action potentials were studied in isolated guinea-pig papillary muscles, perfused with modified Tyrode's solution. The basic driving rate was 1 Hz and the rate was changed from 1 Hz to 0.25, 0.5, 2, 3 and 4 Hz in a stepwise manner. Both lidocaine and MEGX produced dose- and rate-dependent depression of maximum rate of rise of action potential (Vmax) without significant changes in resting membrane potentials. The recovery kinetics of Vmax was studied by either applying premature stimuli at basic driving rate of 0.25 Hz or by stopping the basic driving of 1 Hz for 1s to 60s. A slow component (time constant: 176-206 ms for lidocaine, 300-340 ms for MEGX) was observed in premature response. And a slower component (time constant: 3-4s for MEGX) was observed in the first response after stopping stimulation. Both drugs shortened the action potential duration. These results suggest that MEGX has a lidocaine-like class I antiarrhythmic actions and that it might modify the actions of lidocaine especially in patients with elevated plasma MEGX concentration.

Action Potentials↗

PubMed1990

[Changes in the immune response in postoperative patients while running the ventricular assist device (VAD)].

We examined the immunological parameters in two patients who were assisted with LVAD in postoperative LOS. Both patients demonstrated transient consumption of complements immediately after running the LVAD. The serum concentrations of immunoglobulins (IgG, IgM, IgA) showed no significant decrease. Both patients had significant postoperative lymphopenia, but recovered in a week. A decrease in the number of T cells was observed in both patients. The OKT4/OKT8 ratio initially increased in one patient, but gradually declined postoperatively. In the other patient, the OKT4/OKT8 ratio decreased. The lymphocyte response to mitogen (PHA) remained significantly depressed when the number of lymphocytes returned to the normal level, suggesting that the lymphocytes were functionally impaired. Such findings are generally observed after cardiac surgery. Thus, LVAD does not affect the immune response.

Adolescent↗

PubMed1990

[Assessment of resting thallium-201 reinjection after stress-delayed Tl imaging (I): Comparison with 24-hour scan and regional wall motion].

Clinical value of resting reinjection of 1 mCi (37 MBq) of Tl after stress-delayed scan was assessed in comparison with 24 hr delayed scan and regional wall motion (RWM) in 37 patients with coronary artery disease. Of 101 segments with initial perfusion abnormality, concordant findings were observed after Tl reinjection in 67 segments (66%). But redistribution (RD) after Tl reinjection was observed in 19 of the 52 persistent defect (PD) segments (37%), and complete RD was observed 15 of the 43 segments (35%) where 3 hr scan showed incomplete RD. On the other hand, concordant findings were observed on 24 hr delayed scan in 11 of the 20 segments with perfusion abnormality (55%). RD on 24 hr delayed scan was observed in 5 of the 13 PD (38%), but it was not apparent in 3 of the 7 segments where 3 hr scan showed RD. Furthermore the segments which showed RD after Tl reinjection in PD segments tend to have less severe RWM abnormality than the sustained PD segments (RWM score: 1.65 +/- 1.17 vs. 2.29 +/- 1.05, p less than 0.05). These data indicate that Tl reinjection which permits assessment of RD with good quality images on the same day is considered as a valuable means for assessing myocardial viability.

Adult↗

PubMed1990

[Repair of pure mitral insufficiency--experience in 50 patients].

Between February 1982 and March 1987, 50 adults underwent mitral valve repair for pure mitral insufficiency representing 54% of all adults having mitral valve surgery for pure mitral insufficiency. Ages ranged from 20 to 73 years (50.0 +/- 11.6). Anterior leaflet prolapse was present in 11, posterior leaflet prolapse in 26 and annulus dilation in 13. The mitral valve was repaired by quadrangular resection in 21, triangular resection in 2, plication without resection in 4, chordal shortening in 8 and annuloplasty alone in 15. Commissural annuloplasty was performed in addition to leaflet repair or chordal shortening in other 14 patients. The competence of the mitral valve was usually evaluated under beating conditions. 79% of the attempted repairs was considered successful in the posterior leaflet, contrasting to only 37% in the anterior leaflet. Prolapse of the anterior leaflet remains a surgical challenge. There were two early deaths (4%). During the follow up period (Mean 1.9 years, range 0.2-5.2 years), 2 late deaths (4%) were observed, one of them from thromboembolism, before adopting the policy of routinely anti-coagulating these patients during the first few months. 4 patients (9%), early in our experience, required reoperation within 4 months of surgery: two for severe mitral insufficiency and two for severe mechanical hemolysis. At reoperation, residual insufficiency was present in one, valve suture tear due to technical imperfection in two and complete disruption of the valve tissue at the suture line in one. Four additional patients had transient mechanical hemolysis requiring no specific therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[The recent trend of coronary surgery].

As the use of PTCA (Percutaneous Transluminal Coronary Angioplasty) is progressively widespread, the indication of CABG (Coronary Artery Bypass Grafting) and its candidates are changing accordingly. At present the candidates for CABG have left main trunk disease or severe triple-vessel disease, which are difficult or too dangerous to undergo PTCA. We should also note the population of operative candidates is becoming gradually older than before. The results from CABG appear to be limited according to the random follow-up studies in Europe and United States. The recurrence of angina and myocardial infarction tends to happen after five years. Our follow-up study shows the same tendency as those studies abroad. In order to improve the long-term results of CABG, we recommend the use of arterial grafts such as internal mammary artery, opt to the complete revascularization, and follow the patients postoperatively maximum medical therapy. At the same time, we should stress the importance of deciding the best operative opportunity, and not hesitate to make the decision for reoperation if it became necessary. Older candidates have tendency to suffer from neurological or respiratory complications during the postoperative period. If the risk of those complications appears great from the preoperative examination, we must make efforts to prevent those complications and finish CABG in the shortest possible time. Recently the cases for emergent CABG are decreasing for unstable angina or acute myocardial infarction, because PTCA is more effective for a short time. Time appears to be the most limiting factor for emergent coronary revascularization. Therefore the indication of emergent CABG is left only for left main trunk disease or severe triple vessel disease with complete occlusion of two coronary vessels. As a conclusion, CABG should be considered as only a palliative therapy same as PTCA and other medical treatments. Therefore the treatment of ischemic heart disease must be constituted by a integrated strategy including PTCA and drug therapy arranged for each patient.

Aged↗

PubMed1989

Immunohistological and immunochemical characterization of a novel pancreatic cancer-associated antigen MUSE11.

Using the ascites fractions of a cancer patient as an immunogen, we have recently prepared an interesting monoclonal antibody (MoAb), MUSE11 (IgG1), to a circulating pancreatic cancer-associated antigen (antigen MUSE11). Immunoperoxidase study revealed that antigen MUSE11 was detected in virtually all adenocarcinomas (especially pancreatic carcinoma), whereas it was either negative or faintly positive in their normal counterparts among the digestive organ tissues. Western blotting analysis and periodic acid-Schiff carbohydrate staining revealed that antigen MUSE11 is a Mr 300,000 glycoprotein that is clearly different from other high-molecular-weight glycoprotein antigens which have been used for detection of circulating antigens in pancreatic cancer patients. MoAb MUSE11 appears to react with a peptide epitope of this molecule, since periodic acid and neuraminidase treatment of the antigen did not affect the reactivity of MoAb MUSE11 with the antigen, but trypsin and protease treatment abolished the reactivity. The antigen MUSE11 was purified using affinity chromatography in conjunction with MoAb MUSE11. This antigen appears to be highly glycosilated with N-linked carbohydrate moieties, since treatment of the pancreatic carcinoma Panc-1 cells with tunicamycin reduced the molecular weight band to Mr 110,000. Once antigen MUSE11 has been purified by affinity chromatography, neither CA19-9 nor pancreatic oncofetal antigens can be detected, although they were present at very high levels in the crude ascitic starting material.

Animals↗

PubMed1989

TSK-Toyopearl gels for the preparative separation of sterol carrier protein2 from rat liver.

The application of TSK-Toyopearl gels to the preparative separation of a basic and low-molecular-weight protein, sterol carrier protein2 (SCP2), was studied. SCP2 was purified from 105,000 g supernatant of rat liver (S105) by ion-exchange chromatography on CM-Toyopearl 650M and gel permeation on Toyopearl HW60S. Separation of S105 by CM-Toyopearl 650M was carried out at a high flow-rate in the presence of 10% (v/v) glycerol, a stabilizer of the protein. Toyopearl HW60S showed a significant ion-exchange effect on the elution of SCP2. Using an elution buffer of ionic strength of 45 mM, a highly efficient purification of SCP2 on HW60S was achieved. SCP2 was purified approximately 5000-fold to apparent homogeneity with an overall yield of 69%.

Animals↗

PubMed1989

Assessment of transesophageal Doppler echography in dissecting aortic aneurysm.

To assess the clinical value of transesophageal Doppler echography in the diagnosis of dissecting aortic aneurysm, both transesophageal and conventional echograms were performed in 22 cases of dissecting aortic aneurysm. Of the 22 patients, 17 underwent angiography; 8, X-ray computed tomography; 4, both; and 12, surgery. The performance of each method was assessed in the following four segments: A, ascending aorta; B, aortic arch; C, thoracic descending aorta; and D, upper abdominal aorta. The results by angiography were presumed to be correct. In the group of 17 patients who underwent angiography, the rate of correct detection of an intimal flap using the transesophageal approach was 100% in all four segments, significantly better than detection by the conventional approach (segment A, 65%; segment B, 47%; segment C, 35%; segment D, 53%) (p less than 0.01), and the rate of correct detection of the entry sites using the transesophageal approach was 100%, significantly better than that by conventional approach (42%) (p less than 0.05). X-ray computed tomography was not capable of detecting the site of entry in all cases. The presence of thrombus, aortic regurgitation and pericardial hemorrhage were all revealed clearly by the transesophageal approach, and the results were partly proved by other methods. In conclusion, transesophageal Doppler echography provides a rapid and accurate method of diagnosing and evaluating dissecting aortic aneurysm and permits prompt initiation of appropriate treatment.

Adult↗

PubMed1989

Positron emission tomography using fluorine-18 deoxyglucose in evaluation of coronary artery bypass grafting.

To assess the clinical value of positron emission tomography (PET) in the evaluation of coronary artery bypass grafting (CABG), PET perfusion and metabolic imaging using nitrogen-13 ammonia and fluorine-18 deoxyglucose (FDG) was performed before and 5 to 7 weeks after CABG in 22 patients with coronary artery disease. Postoperative improvement in hypoperfusion was observed more often in the metabolically active segments (62%) than in the inactive segments (27%) on the preoperative PET study (p less than 0.05). Similarly, the postoperative lessening of wall motion abnormality was observed more often in the metabolically active segments (78%) than in the inactive segments (22%) (p less than 0.001). Of 19 asynergic segments showing increased FDG uptake before operation, the postoperative PET revealed a decrease in FDG uptake in 13 (68%) and persistent uptake in 6 (32%). The improvement in asynergy was observed in all the segments that showed a postoperative decrease in FDG uptake, but in only 50% of those with persistent uptake (p less than 0.01). On the other hand, 4 of 5 segments showing a new FDG uptake after operation revealed further wall motion abnormality. Furthermore, the segments metabolically active before operation were more likely to have patent grafts (95%) than the metabolically inactive segments (70%) (p less than 0.05). Thus, preoperative metabolic imaging using PET appears to be useful for predicting the response to CABG. Improvement in metabolic derangement was associated with improvement in regional function after CABG.

Adult↗

PubMed1989

Ultrastructural and immunocytochemical studies on the cytoskeleton in the anterior pituitary of rats, with special regard to the relationship between actin filaments and secretory granules.

As previously reported, in anterior pituitary cells of the rat, secretory granules are linked with adjacent granules, cytoorganelles, microtubules, and plasma membrane by thin filaments, 4-10 nm in diameter. The quick-freeze, deep-etching method revealed that some of the filaments linking adjacent secretory granules show 5 nm-spaced striations on their surface which are known to be characteristic of actin. Immunocytochemistry showed that actin is localized in the cytoplasm beneath the plasma membrane, and around or between secretory granules. The heavy meromyosin decoration method demonstrated that actin filaments are mainly located in the cytoplasm beneath the plasma membrane, while some actin filaments are connected with the limiting membrane of the secretory granules. The actin filaments associated with the secretory granules are considered to be involved in the intracellular transport of the granules, while those localized in the peripheral cytoplasmic matrix might control the approach of the secretory granules to the plasma membrane and their release.

Actins↗

PubMed1989

Sodium channel-blocking properties of flecainide, a class IC antiarrhythmic drug, in guinea-pig papillary muscles. An open channel blocker or an inactivated channel blocker.

Effects of flecainide (a class IC antiarrhythmic drug) on the maximum rate of rise (Vmax) of action potentials (APs) were studied in guinea-pig papillary muscles, with special reference to their time, voltage, and action potential duration (APD) dependence in the presence and absence of nicorandil. Nicorandil was used to shorten APD, i.e., the time period of inactivation state of sodium channels. APs were recorded from the preparations using standard microelectrode techniques. Flecainide (5 mumol/l) reduced Vmax without changing resting potential, AP amplitude, APD50, and APD90 examined at 1 Hz. The drug shifted the normalized Vmax-membrane potential curve (examined at 1/60 Hz) in the hyperpolarizing direction by 3.1 +/- 0.8 mV (n = 6) (voltage dependence). The drug caused a frequency-dependent reduction of Vmax at greater than or equal to 0.1 Hz, developed a use-dependent reduction of Vmax at 1 Hz with an onset time constant of 11.7 +/- 0.4 s (n = 6), and slowed the recovery process of Vmax, whose resultant recovery time constant was 19.9 +/- 1.2 s (n = 6) (time dependence). These flecainide-induced time-dependent reductions of Vmax were not antagonized by nicorandil (1 mmol/l) which shortened APD to about 1/4 of control (APD independence). These results suggest that flecainide is primarily an open channel blocker because its channel-blocking actions are independent of APD or the time period of inactivation.

Action Potentials↗