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Biomedical subjects

H Yasui

Publications and source records attributed to H Yasui.

At least 361 records · Page 20Linked to original sources
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Different responses in adult and neonatal hearts to changes in coronary perfusion pressure.

The influence of coronary perfusion pressure on neonatal heart function has not been evaluated. We compared the coronary perfusion pressure-cardiac function relationship between neonatal and adult hearts. Neonatal and adult rabbit hearts were examined. The coronary perfusion pressure was changed in increments of 10 mmHg. Coronary blood flow and left ventricular functions were measured at each coronary perfusion pressure. Autoregulatory capacity for coronary blood flow was quantified by calculating the autoregulation index. In neonatal hearts, left ventricular developed pressure was decreased at high perfusion pressure, whereas in adult hearts left ventricular developed pressure increased at high perfusion pressure. In neonatal hearts, left ventricular enddiastolic pressure was elevated at both low and high perfusion pressure, whereas in adult hearts left ventricular enddiastolic pressure remained constant at all perfusion pressures. Adult hearts exhibited coronary blood flow autoregulation in the perfusion pressure range between 40 and 90 mmHg. In contrast, neonatal hearts did not show autoregulation in any perfusion pressure range. In neonatal hearts, both low and high perfusion pressure caused deterioration in ventricular function attributable to the immaturity of coronary autoregulatory capacity. We conclude that coronary perfusion pressure should be controlled within a narrow range for neonates.

Adult↗
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Distribution of cells labelled by a monoclonal antibody (A3) against a cloned cell line derived from a rat malignant fibrous histiocytoma.

To pursue the histogenesis of malignant fibrous histiocytoma (MFH), of which the cell of origin is still debated, a monoclonal antibody (A3) was produced against a rat MFH-derived cloned cell line (MT-8). Antigen recognized by A3 was around 80 kDa in molecular weight and was seen on the cytoplasmic membrane of MT-8 cells by immunoelectron microscopy. A3 reacted specifically with MT-8 cells, with another rat MFH-derived cell line (MT-9) and with their induced tumours in syngeneic rats, but not with other rat tumours such as fibrosarcoma, histiocytic sarcoma, malignant meningioma, uterine leiomyosarcoma, endometrial stromal sarcoma, mononuclear cell leukaemia and malignant schwannoma. These findings indicate that A3 has a high specificity for rat MFH cells. In fetuses on gestation days 15, 18 and 20 and in postnatal rats aged 1, 4 and 8 days, A3 reacted with primitive mesenchymal cells in visceral organs and around arteries and bronchi, as well as in the lamina propria of intestinal mucosa, renal interstitium, meninges and perineurium. There were no A3-positive connective tissue cells in organs or other sites in adult rats more than 10 weeks old. It is therefore likely that MFH cells share antigens with primitive mesenchymal cells, which may be multipotent for mesenchymal differentiation. The present study suggests that MFH consists of a population of primitive, undifferentiated mesenchymal cells. A3 also immunolabelled endothelial cells of arteries, venules and pulmonary capillaries in fetal, postnatal and adult rats; vascular endothelial cells in chemically induced hepatic and renal lesions also reacted strongly with A3. However, the significance of endothelial immunoreactivity with A3 remains to be elucidated.

Animals↗
PubMedDate not supplied

Dandy-Walker like malformation in a Fischer-344 rat.

A spontaneous cerebellar malformation was found in a 32-day-old male Fischer 344 rat. The cerebellar malformation was composed of a vermis defect and markedly dilated fourth ventricle. The cerebellar hemispheres were separated, with the left hemisphere being smaller than the right one. Degenerative/inflammatory lesions consisting of macrophage/lymphocyte infiltration, spheroidal calcium depositions, and astrocytic gliosis were seen adjacent to the cerebral aqueduct. Abnormally arranged hyperplastic ependymal cells were observed beneath the fourth ventricle in the medulla oblongata. The gross findings of the present case resemble those of the human Dandy-Walker malformation. While a precise mechanism remains to be elucidated, degenerative/inflammatory lesions in the present rat may be involved in the pathogenesis of this malformation.

Animals↗
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Efficacy of perioperative portal venous inoculation with donor lymphocytes on skin graft survivals in the rat.

Although the administration of donor lymphocytes via portal vein (PV) on the day of transplantation significantly prolongs rat renal allograft survivals and the unresponsive state is mediated by an antigen-specific suppressor factor in the serum, significant variations exist among rodent models in terms of immunogenicity and mechanism of antigen presentation. The present studies sought to assess the effect of perioperative PV inoculation with donor lymphocytes on skin allograft survivals. Donor lymphocytes were prepared from Brown-Norway (BN, RT-1n) or third-party DA (RT-1a) rat spleens and lymph nodes and injected via PV or intravenously to Lewis (LEW, RT-1l) hosts on the day of skin grafting. Untreated LEW hosts rejected BN skin grafts at 9.0 +/- 1.4 days (n = 10). Intravenous administration of 1 x 10(8) BN cells into LEW hosts on day 0 did not prolong the skin graft survivals (MST = 8.6 +/- 1.2 days, n = 7, NS), whereas PV inoculation of 1 x 10(8) BN cells prolonged skin graft survival to 13.4 +/- 3.9 (n = 8, P < .01). PV administration of 1 x 10(8) DA cells to LEW hosts did not prolong the survival of BN skin grafts (MST = 8.6 +/- 1.5 days, n = 6). PV inoculation with BN cells inhibited the generation of anti-BN delayed-type hypersensitivity (DTH) response in the hosts, whereas untreated control hosts or hosts inoculated with third-party DA cells could not inhibit the anti-BN DTH response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Immunomodulatory function of lactic acid bacteria.

Using mice, we found that oral administration of Bifidobacterium breve YIT4064 (B. breve) activated the humoral immune system, augmented anti-rotavirus IgA production or anti-influenza virus (IFV) IgG production and protected against rotavirus infection or influenza infection, respectively. Furthermore, when the B. breve was given to infants from an infant home, there was a significant reduction of the frequency of rotavirus shedding in stool samples during the administration of the bacteria. It was also found, again using mice, that oral administration of Lactobacillus casei strain Shirota (LcS) stimulated type 1 helper T (Th1) cells, activated the cellular immune system and inhibited incidence of tumors and IgE production. These results demonstrated that these two strains of lactic acid bacteria modulated the different immune systems each in its own way and prevented against various diseases.

Animals↗
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Preservation of the pulmonary valve during intracardiac repair of tetralogy of Fallot.

From January 1981 to December 1990, intracardiac repair of tetralogy of Fallot in 148 pediatric patients, with one surgical death, was directed toward preservation of the native pulmonary valve. Using the accepted preoperative angiographic criterion for the pulmonary valve annulus area (PVA) of 1.8 cm2/m2, 85 patients were candidates for transannular right ventricular outflow patch (TAP). However, in 54 patients with a mean PVA of 1.5 cm2/m2 (range 1.06-1.76), the valve was preserved without using TAP because the morphological changes (cusp thickening and annular distensibility) seemed acceptable for preservation in view of its probable hemodynamic efficiency and growth potential. A morphological classification of pulmonary valve changes has evolved. Retrospectively, 24 (77%) of the 31 patients with TAP had moderate to severe cusp thickening and ring rigidity; this incidence was significantly higher (p < 0.001) than that in preserved patients (18 of 54 or 33%). The incidence of morphological changes increased with operative age; that is, 2 of 13 (15%) patients younger than 1 year versus 23 of 40 (58%) patients older than 4 years (p < 0.01). All 54 patients with preserved pulmonary valves were catheterized one month postoperatively. The intraoperative right to left ventricular systolic pressure ratio (RVP/LVP) decreased significantly (p < 0.005) in one month, from a mean of 0.79 (range 0.44-1.36) to 0.57 (range 0.36-0.97). The PVA increased from a mean of 1.5 to 1.9 cm2/m2 (range 1.20-2.65), and the rate of its increase was significantly larger (p < 0.005) as operative age decreased. Pulmonary valve regurgitation of greater than mild degree occurred in 8 of 54 (15%) patients with the valve preserved.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
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Arterial switch operation for transposition of the great arteries: surgical techniques to avoid complications.

From June 1984 to November 1990, 109 patients with transposition of the great arteries underwent arterial switch operation. There were 5 deaths, yielding a mortality rate of 4.6%. During this period, modifications of the surgical technique were devised to minimize intra- and postoperative problems, such as bleeding, kinking of the coronary arteries, aortic regurgitation and pulmonary stenosis. The surgical refinements that evolved include (1) a more distal division of the ascending aorta, (2) a punch technique for reimplantation of the coronary arteries in a medially rotated position, approximating the commissure, and superior to the upper border of the sinus of Valsalva, and (3) removal of left coronary ostia by incision down from the transected site to include a button of aortic wall, avoiding the free margin of the aorta and patch enlargement of the neopulmonary artery. Since instituting these refinements: (1) the time consumed for hemostasis after termination of the bypass considerably decreased from 111 +/- 59 to 87 +/- 51 minutes (p less than 0.05), (2) the incidence of kinking of the coronary arteries decreased from 29% (4/14) to 7% (6/88) (p less than 0.05), and (3) the occurrence of aortic insufficiency 1 year after correction was reduced from 36% (5/14) to 8% (5/66) (p less than 0.02). However, the occurrence of pulmonary stenosis with a pressure gradient greater than 30 mmHg did not decrease significantly despite aggressive modifications of surgical techniques, and its incidence in the most recent series of 32 patients was still a high 19%.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Effect of perfusion rate on the local disposition of cefixime in liver perfusion system based on two-compartment dispersion model.

The effect of perfusion flow rate upon the estimated parameters in the two-compartment (non-equilibrium) dispersion model, such as dispersion coefficient, volume of the blood space, partition ratio, and irreversible transfer (or elimination) rate constant, was evaluated in the rat liver perfusion system, using cefixime as a test drug. The rats were divided into five groups and the perfusion experiments were performed at various perfusion rates (Q = 6.4, 11.3, 14.1, 16.3, and 19.6 ml/min/liver). The two-compartment dispersion model was fitted to the outflow cefixime concentration profiles after bolus input into the portal vein using the nonlinear least squares program MULTI(FILT). Results of curve fitting suggested that the corrected dispersion coefficient (DC) and the volume of blood space (VB) increased with increase in flow rate. In contrast, the partition ratio (k'), which is a measure of the extent of drug partition between the blood and the hepatic tissues, decreased when flow rate increased. The single-pass extraction ratio of cefixime is small, and the irreversible transfer rate constant (ke) was independent of flow rate. These parameters were correlated to the moment characteristics such as the recovery ratio (FH), the mean hepatic transit time (tH), and the relative variance of the transit time (sigma 2/tH2). FH and sigma 2/tH2 were independent of the flow rate, whereas tH decreased and the apparent distribution volume (VH) increased with increase in perfusion rate.

Animals↗
PubMedDate not supplied

Primary repair for complete atrioventricular canal: recommendation for early primary repair.

Forty patients with complete atrioventricular canal (CAVC) underwent primary repair at Fukuoka Children's Hospital in Fukuoka, Japan, between August 1, 1981 and July 31, 1989. The age at repair ranged from 2 months to 6 years (mean 19 months); weight ranged from 2.3 to 22 kg. The surgical mortality was 2.5%. Justification for early primary repair was examined. Eleven patients underwent repair before 6 months of age (Group 1), 12 patients, between 7 and 11 months of age (Group 2), and 17 patients, after 12 months of age (Group 3). Degenerative changes in the atrioventricular valve increased significantly as age at repair increased (p less than 0.05 Group 1 versus Group 3). The incidence of residual mitral regurgitation tended to increase in the order of Group 1, 2 and 3, though the degree ranged from trivial to mild. Study of the left atrium/aorta ratio by echocardiography revealed that stable values of around 1.1 in Groups 1 and 2 and around 1.3 in Group 3 continued during the follow-up period of 3 years. Assessment of the diameter of the repaired mitral valve in the mean interval of 26 months in groups 1 and 2 revealed normal growth of the mitral valve annulus. The angle between the repaired mitral valve and ventricular septum, which can be affected by the growth of the ventricular septum, converged to normal range in the mean interval of 26 months. Postoperative pulmonary vascular resistance in Groups 2 and 3 was higher at 4.4 +/- 2.3 and 6.3 +/- 2.2, respectively, than in Group 1 at 3.3 +/- 2.2 (p less than 0.01 versus Group 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗