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Biomedical subjects

H Okabayashi

Publications and source records attributed to H Okabayashi.

At least 55 records · Page 3Linked to original sources
PubMed1992

[A case of successful repair of aorto-pulmonary artery fistula secondary to aortic arch aneurysm].

A report of a rare case of successful repair of rupture of an aortic aneurysm into the pulmonary artery. A 55-year-old male was transferred to our hospital because of dyspnea with sudden onset, hemoptysis and palpitation. A loud, continuous, "machine-like" murmur was heard on the anterior wall of the chest. Various examinations revealed an acquired shunt between the thoracic aortic aneurysm and the pulmonary artery and high-output heart failure. Aortic arch replacement was performed expeditiously and the patient recovered, and was able to return to work. 108 cases of rupture of a thoracic aortic aneurysm into the pulmonary artery have been reported in the literature. Operation for repair was performed in only thirteen of these. Only four cases have been reported in the literature in which the patients were successfully treated.

Aorta, Thoracic↗
PubMed1991

Interfacial dehydration by anesthetics: an electrocapillary study of surface charge density of adsorbed monolayer.

We have proposed that anesthetics destruct the hydration shell of macromolecules irrespective of lipid membranes or proteins. These macromolecular structures are supported by the hydrogen-bonded matrix of water molecules. A loss of this support destabilizes the membranes and proteins. The disordered structures are suboptimal for the assigned biological functions, and anesthesia may ensue. We postulated that the dehydration is prompted mainly by the decrease in the interactions of the surface charges with the water dipole. To prove or disprove the above hypothesis, this study measured the effect of volatile anesthetics (chloroform, halothane, and enflurane) on the surface charge density in adsorbed monolayers by an electrocapillary method. The oil phase was methylisobutylketone (MIBK) with cetyltrimethylammonium chloride (CTAC). The aqueous phase was 0.1 M NaCl. The anesthetics decreased the surface charge density, and the effect paralleled the clinical anesthetic potency. At concentrations that induce surgical stage anesthesia in 50% of the population, these anesthetics reduced the surface charge density by 5%.

Adsorption↗
PubMed1991

Genetic resistance to a Marek's disease transplantable tumor cell line in chicken lines selected for different immunological characters.

The tumor incidence and mortality of Marek's disease (MD) were determined for 471 progeny from four pairs of lines two-way selected for different immunological characters: graft versus host reaction (GVHR) competence, IgG levels, antibody response to rabbit serum albumin (RSA), and anaphylactic shock to BSA. All chicks were inoculated at 1 wk of age with 1 to 2 x 10(6) viable cells of a MD lymphoblastoid cell line, MDCC-MSB1-41C (41 C). Tumor incidence differed significantly between the high (H) and low (L) lines of each GVHR-, IgG-, RSA-, or BSA-selected group. There were also significant differences in mortality rates between H and L lines of all selected groups. The IgG-H, BSA-H, and RSA-H lines were more resistant than their respective L lines. The H line of the GVHR-selected lines was more susceptible than the L line. Tumor regression could be detected only in the IgG- and RSA-selected lines. No definite correlation could be found between genetic resistance to 41C and genetic resistance to MD virus.

Anaphylaxis↗
PubMed1990

[Experimental study of application of excimer laser to laser angioplasty].

The possible application of excimer laser to laser angioplasty was studied. In the first experiment, the ablative effects of excimer laser at wavelengths of 248 nm and 308 nm on the pig myocardium were examined in vitro at an air-tissue interface. Crater depth increased with total delivered energy and energy per pulse. Very clear cuts could be observed by histological examination. There was no evidence of thermal damage at a wavelength of 248 nm, at 10 pps. Above 10 pps, a thin bordering zone of suspicious thermal damage was noted with the wavelengths of 248 nm and 308 nm. Thermal damage increased with pulse repetition rate. In the second experiment, the effects of excimer laser irradiation on blood were examined. Five vials, each of which contained 3 ml of blood, were exposed to 37.5 mJ laser beam at 10 pps in repetition rate for 10, 20, 30, 40, 50 seconds. One vial was left untreated as a control. No change in hematocrit value was observed after excimer laser irradiation. In contrast, the level of plasma free hemoglobin rose progressively with each increased duration of exposure. This result indicates that the lysis of erythrocytes does not occur in the laser-exposed cells. However, the damage to erythrocyte membrane took place as it was evidenced by progressive hemoglobin leakage into plasma. In the third experiment, the excimer laser was coupled to a 400 microns quartz optical fiber and the laser energy transmitted through the fiber was measured. At a wavelength of 308 nm, pulse energies up to 9 mJ were noted at the tip of the fiber. At a wavelength of 248 nm, the fiber tip was destroyed. In the fourth experiment, acute and chronic healing responses of normal canine arteries to excimer laser irradiation were studied in 4 mongrel dogs. The artery healed completely at the 18th day after the excimer laser irradiation. There was no evidence of thrombus formation and intimal hyperplasia in these arteries. The results suggest the applicability of excimer laser to laser angioplasty.

Angioplasty, Laser↗
PubMed1990

Proton flow along lipid bilayer surfaces: effect of halothane on the lateral surface conductance and membrane hydration.

Impedance dispersion in liposomes measures the lateral charge transfer of lipid membrane surfaces. Depending on the choice of frequency between 1 kHz and 100 GHz, relaxation of the counterions at the interface, orientation of the head group, and relaxation of the bound and free water are revealed. This study measured the impedance dispersion in dipalmitoylphosphatidylcholine (DPPC) liposomes at 10 kHz. The surface conductance and capacitance showed breaks at pre- and main transition temperatures. Below the pre-transition temperature, the activation energy of the ion movement was 18.1 kJ.mol-1, which corresponded to that of the spin-lattice relaxation time of water (18.0 kJ.mol-1). At temperatures between pre- and main transition it increased to 51.3 kJ.mol-1, and agreed with 46.2-58.0 kJ.mol-1 of the activation energy of the dielectric relaxation of ice. Because the present system was salt-free, the ions were H3O+ and OH-, hence, their behavior represents that of water. The above results show that below the pre-transition temperature, the conductance is regulated by the mobility of free ions, or the number of free water molecules near the interface. On the other hand when the temperature exceeded pre-transition, melting of the surface-bound water crystals became the rate-limiting step for the proton flow. Halothane did not show any effect on the ion movement when the temperature was below pre-transition. When the temperature exceeded pre-transition, 0.35 mM halothane (equilibrium concentration) decreased the activation energy of the ion movement to 29.3 kJ.mol-1. This decrease indicates that halothane enhanced the release of the surface-bound water molecules at pre-transition. The surface-disordering effect of halothane was also shown by depression of the pre-transition temperature and decrease of the association energy among head groups from 9.7 kJ.mol-1 of the control to 5.2 kJ.mol-1 at 0.35 mM.

1,2-Dipalmitoylphosphatidylcholine↗
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

[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

[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↗
PubMed1989

Changes in surface capacitance and conductance parallel to phospholipid membranes associated with phase transition: effects of halothane.

The effects of phase transition on the surface capacitance and conductance parallel to dipalmitoyl- (DPPC) and dimyristoyl-phosphatidylcholine (DMPC) membranes were studied by impedance dispersion. The phospholipid aggregates were embedded into pores of a polycarbonate filter and the impedance dispersions were measured at a frequency range from 30 Hz to 1.0 MHz. When the frequency was below 120 kHz, the capacitance showed a peak at the pretransition temperature and a steep rise at the main-transition temperature. In this system, the observed capacitance consists of frequency-dependent and -independent parts. The frequency-dependent part is a surface phenomenon and arises from the lateral motion of counterions at the membrane/water interface. The frequency-independent part represents mainly the properties of the bulk lipid phase. Addition of halothane decreased the total capacitance of the DPPC aggregates at the low frequency range to 1/2 to 1/8 of the control depending upon the temperature. The surface component was solely responsible for this capacitance decrease, because the non-surface component was slightly increased instead. The data suggest that halothane inhibited the lateral ionic flow parallel to the interface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Saturable and unsaturable binding of a volatile anesthetic enflurane with model lipid vesicle membranes.

Presence of specific receptors for volatile anesthetics has recently been proposed (Evers, A.S. et al. (1987) Nature 328, 157-160) by a finding that halothane uptake by the rat brain was characterized, in part, by saturable binding. We report here that volatile anesthetics bind model lipid membranes also with saturable and unsaturable kinetics. Binding of enflurane to dipalmitoylphosphatidylcholine vesicle membranes was measured by gas chromatography. At low anesthetic concentrations, comparable to the clinical level, the interaction was saturable. After reaching a temporary saturation, a sudden increase in the anesthetic binding to the membrane occurred, when the anesthetic concentration in the aqueous phase exceeded 2.7 mM, or 6.3 x 10(-2) atm partial pressure in the gas phase in equilibrium with the aqueous phase. The secondary binding was linear to the aqueous anesthetic concentrations and was unsaturable to the limit of this study. We also found that enflurane self-aggregated in water above 4 mM. When the aqueous concentration exceeded 6 mM, the aggregation number was about 8. We conclude that the saturable binding indicates adsorption onto the vesicle surface, and the unsaturable binding indicates multilayer stacking of the enflurane molecules, where the initially adsorbed molecules provide the binding sites to the succeeding molecules according to the multilayer condensation kinetics. The tendency of enflurane to self-aggregate in water promotes the multilayer stacking at the surface of the membrane.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Effects of coronary artery bypass surgery on regions showing persistent defects in thallium myocardial images.

The indications for revascularization surgery and its effects on myocardial regions showing persistent defects in thallium myocardial images are controversial. The effects of aortocoronary bypass surgery on myocardial perfusion and wall motion in the regions with persistent defects were evaluated in 47 patients with thallium-201 single photon emission computed tomography and left ventriculography. In areas showing persistent thallium defects preoperatively the rate of improvement of perfusion was only 24% by postoperative thallium imaging, and 57% by wall motion analysis. These results were significantly inferior to those of regions with transient defects, which were 84% and 82%, respectively. A persistent defect may not be a definitive marker of a non-viable scar, but the results of surgery on such regions were unsatisfactory. It is concluded, therefore, that revascuralization surgery in regions with persistent defects is not always recommended and that the indications for surgery should be individually determined with operative risk balanced against benefits.

Adult↗
PubMed1989

[Aortic aneurysm associated with coarctation of the aorta].

An 8-year-old female of coarctation of the aorta associated with thoracic aortic aneurysm is reported. Under cardiopulmonary bypass, a 7 cm section of the aorta containing the aneurysm and coarctation was resected and replaced by a 16 mm woven Dacron tube. The postoperative recovery was complicated by chylothorax treated by thoracic aspiration. She is doing well 3 months after the operation. Histologic sections of the resected portions of the thoracic aorta revealed intimal hyperplasia, medial fibrosis and decrease of elastic fibers, especially in the aneurysm.

Aorta, Thoracic↗
PubMed1989

Comparison of nisoldipine and atenolol in the treatment of essential hypertension.

The antihypertensive effects of nisoldipine, a calcium channel blocker, and atenolol, a beta-adrenergic blocker, were compared in patients with mild or moderate essential hypertension. Both drugs produced significant reductions in blood pressure from the 8th week through the end of the 12-week treatment period. The hear rate decreased significantly in the atenolol group but not in the nisoldipine group. Following oral administration of 50 mg of captopril, the rise in plasma renin activity was significantly smaller in both treatment groups than in normotensive controls. The magnitude of the pressor response during a hand-grip test tended to be smaller in both groups of patients than in the controls, with no significant difference between the treated groups. Although the plasma catecholamine concentration rose significantly in the control and nisoldipine groups, there were no significant intergroup differences in these parameters. The hemoglobin, GOT, creatinine, total cholesterol and serum sodium and potassium concentrations all decreased significantly in the nisoldipine group, although the values remained within normal limits. These results indicate that both nisoldipine and atenolol significantly suppress both plasma renin activity and the pressor response to stress leading to reduction of blood pressure.

Adult↗
PubMed1989

[Unilateral pulmonary vein atresia].

A case of unilateral pulmonary vein atresia in a 20-month-old girl is described in this report. A chest X-ray revealed a reticular shadow on the right side, while an electrocardiogram revealed right ventricular hypertrophy. After cardiac catheterization and angiography, a diagnosis of a ventricular septal defect, patent ductus arteriosus, severe pulmonary hypertension, and atresia of the right pulmonary vein was made. The patient underwent an operation for the ventricular septal defect and ligation of the patent ductus arteriosus. During the operation, the right pulmonary vein was found to be atretic, and unrepairable. Pneumonectomy was not performed because the pulmonary arterial pressure decreased to 41 mmHg after the surgical treatment of the intracardiac lesions. Pneumonectomy will be necessary if one or more complications such as persistent hemoptysis, repeated pulmonary infections or the development of pulmonary hypertension, may occur in future.

Ductus Arteriosus, Patent↗
PubMed1988

Endogenous digitalislike substance in an adult population in Japan.

Possible involvement of an endogenous digitalislike substance (EDLS) in blood pressure regulation was investigated using a Japanese population. Mean arterial pressure (MAP) significantly correlated with urinary excretion of the EDLS, age, and the obesity index. The plasma EDLS correlated with urinary EDLS. Urinary EDLS excretion well correlated with the inhibitory activity on Na+,K+-ATPase, and also with the urinary excretion of NaCl. Obesity index correlated with the Na+,K+-ATPase inhibition and arterial pressure. Although plasma content of atrial natriuretic polypeptide correlated with the urinary Na+,K+-ATPase inhibition, it did not correlate with the rest of all parameters. Plasma vasopressin level did not correlate with these parameters either. These results clearly indicate that the circulating EDLS (ie, Na+,K+-ATPase inhibitor) is implicated in the hypertension associated with an excess intake of sodium, aging and obesity.

Adult↗
PubMed1988

Myocardial positron tomography with N-13 ammonia in assessment of aortocoronary bypass surgery.

A total of 20 patients were examined at rest and during stress with N-13-ammonia myocardial positron emission tomography (PET) before and after aortocoronary bypass surgery in an attempt to evaluate the effect of surgery on myocardial perfusion and to predict the graft status. The PET images were divided into anterior, septal, apical, lateral and posteroinferior segments for analysis and were evaluated as "normal" (no perfusion defects during stress and at rest), "ischemia" (stress-induced defects) and "fibrosis" (persistent defects both at rest and during stress). Approximately 90% of the segments which were ischemic before surgery became normal after surgery. Thus, ischemic changes are highly reversible, and the vessels perfusing these ischemic areas are most suitable for bypass surgery. However, most of the persistent defects failed to respond to revascularization surgery and, hence, represented irreversibly damaged myocardium. In predicting graft status, graft patency could be demonstrated by normal perfusion in postoperative images (p less than 0.01) or by improved perfusion when pre- and postoperative images were compared (p less than 0.01). However, graft occlusion could not be predicted reliably. This study demonstrated that PET with N-13 ammonia was useful in the assessment of the effects of aortocoronary bypass surgery. However, this technique was not significantly superior to thallium-201 single-photon emission computed tomography for only qualitative analysis.

Adult↗