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Biomedical subjects

O Yamada

Publications and source records attributed to O Yamada.

At least 181 records · Page 10Linked to original sources
PubMed1989

[Evaluation of left ventricular function in the patients with aortic regurgitation following aortic valve replacement by radionuclide cardiography].

Twenty patients undergoing AVR were subjected to this study and divided into the early and the late groups. 6 healthy adults were dealt as the control group. The EF, PER, 1/3 EF, TPE were compared among these three groups both at rest and during exercise. The detailed responses to the exercise were measured by %delta between at rest and during exercise. Furthermore, the LV function in the filling period were examined by the 1/3 FF and RFR at rest. This study suggests that although the left ventricular function and contractile reserve to the exercise remained insufficient in the early postoperative phase, nearly complete recovery of the reserve could be obtained in the later phase, while the left ventricular function in the rapid filling period was significantly decreased in both early and late postoperative phase.

Adolescent↗
PubMed1989

[Long-term results of cardiac valve replacement: a 10- to 25-year retrospective study].

A total of 149 patients who underwent cardiac valve replacement between January, 1964 and June, 1979 in our institution have been survived more than 10 years postoperatively. The prosthetic valves primary employed in this series were both mechanical valve such as Starr-Edwards, Smeloff-Cutter, Wada-Cutter, Lillehei-Kaster valves and biological valve such as Hancock valve. Of these, 69 patients (46%) implanted with Starr-Edwards or Wada-Cutter valve were not anticoagulated postoperatively, and 52 (53%) underwent reoperation mainly for valve-related complications or aggravated other valve lesions during the follow-up period. One hundred and thirteen patients were confirmed to be alive at the end of June, 1989, with the follow-up period of 10 to 25 years. Of these, 98 patients (87%) are in the NYHA I or II at the present time. Other twenty-two patients were dead and fourteen were lost to follow-up over 10 years after operation. Although cardiac valve replacement may improve the longevity and the quality of life, available prosthetic valves were not ideal both in material and design. The increased risk of thrombogenesis of mechanical valve and the limited durability of biological valve necessitated re-replacement in the long-term period. Therefore, in addition to selection of the appropriate valve prosthesis, and optimal prevention of valve-related complications, early diagnosis and treatment of these complications are important to improve the long-term results of cardiac valve replacement.

Adolescent↗
PubMed1988

An improved method for the detection of HIV antigen in the blood of carriers.

The measurement of HIV antigen levels in sera or plasma of HIV-infected individuals is critical for determining the existence of antigen or infectious virus before seroconversion and for prognosis. Pretreatment of sera or plasma of HIV carriers by heating at 70 degrees C for 10 min at an acidic pH enabled us to estimate antigens efficiently in immune complexes. This procedure will also be useful in determining antigen levels in HIV carriers more precisely.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Inhibition of growth of HIV by human natural interferon in vitro.

The effect of human natural interferons (IFN) alpha, beta, and gamma on the replication of human immunodeficiency virus (HIV) strain LAV in T cell lines TALL-1 and CCRF-CEM and peripheral blood lymphocytes (PBL) was studied. The growth of TALL-1 was moderately sensitive to these IFN, whereas that of CCRF-CEM was resistant to them. The progeny virus yield of LAV in TALL-1 at the time of its peak was reduced to 10% of the control level at IFN-alpha, beta, and gamma concentrations of 3, 11, and 23 IU/ml, respectively. These concentrations of IFN-alpha, beta, and gamma did not affect the cell growth. In CCRF-CEM, IFN-alpha, beta, and gamma at the concentration of 50, 60, and 76 IU/ml reduced the progeny virus to 10% of the control level. The virus growth in PBL was more sensitive to IFN than that in CCRF-CEM. The progeny virus yield was reduced to 10% of the control level by IFN-alpha and beta concentrations of 5 IU/ml and less than 5 IU/ml, respectively.

Cell Division↗
PubMed1988

Hyperkinesis without the Frank-Starling mechanism in a nonischemic region of acutely ischemic excised canine heart.

To determine the essential mechanism of increased systolic wall motion, i.e., hyperkinesis, in a nonischemic region (NIR) during acute ischemia, we simultaneously evaluated global and regional function of the excised, cross-circulated canine left ventricle connected to a volume servo pump before and after coronary occlusion. Regional areas were determined with pairs of orthogonal subendocardial sonomicrometers in the ischemic region (IR) and NIR. After coronary occlusion with left ventricular end-diastolic and stroke volumes kept constant, the amount of systolic area shrinkage (delta A) in NIR increased by 33 +/- 41% (p less than .05), despite a decrease in end-diastolic regional area by 3 +/- 4% (p less than .05). Regional work obtained from the wall tension-regional area (T-A) loop in NIR decreased by 50 +/- 24% due to a similar decrease in afterload despite the presence of hyperkinesis, indicating regional systolic unloading. When left ventricular end-diastolic volume was subsequently increased with a constant stroke volume, delta A in NIR increased at the expense of a further decrease in delta A in IR. The end-systolic T-A relationship in NIR remained unchanged, whereas that in IR markedly shifted rightward, suggesting that the contractile state of NIR was constant. These results indicate that hyperkinesis in NIR during acute ischemia can occur without a utilization of the Frank-Starling mechanism or an enhancement of regional contractile state, and that the essential mechanism of this phenomenon is regional afterload reduction due to an intraventricular mechanical interaction between IR and NIR.

Animals↗
PubMed1988

[AIDS and human lymphocytes].

HIV infection is no doubt the primary cause of AIDS. But the relationship between HIV and its host lymphocytes is fairly complicated. It has become clear that the host range of the viruses varies according to the clinical stage of the patients from whom viruses were isolated. Besides, the cause or mechanism of cell killing by HIV infection is not well-known. The density of CD4 molecules on the cell surface can not simply explain the phenomena, such as the level of virus growth, killing mechanisms of lymphocytes and host range of the virus. It is quite interesting to analyse which gene of the virus determines the characteristics of the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Characterization of neural cell adhesion molecules (NCAM) expressed by Ewing and neuroblastoma cell lines.

The status of the neural cell adhesion molecule NCAM gene which is mapped to human chromosome 11q23-24 has been investigated in Ewing-tumor-derived cell lines which present the t(11;22)(q23-24;q12) translocation characteristic of this malignancy. No rearrangement was detected when 2 different non-overlapping probes to mouse NCAM were used. The expression of the NCAM gene was analysed at both the protein and messenger levels in material extracted from Ewing cell lines, human neuroblastoma cell line and fetal mouse brain. Immune blot and immunoprecipitation studies showed that the neuroblastoma cell line contained more NCAM material than the Ewing lines. In neuroblastoma but not in Ewing, the NCAM material had the electrophoretic characteristics of molecules with long polysialic acid chains. After treatment with endosialidase, the diffusely migrating neuroblastoma material was resolved into 3 discrete bands of 120, 140 and 180 kDa. In Ewing extract, high-molecular-weight NCAM species were also detected with a 3-band pattern more reminiscent of mature brain. Endoglycosidase F treatment of Ewing NCAM indicated that all 3 species were largely N-glycosylated. Northern blot analysis confirmed that NCAM was expressed more abundantly in neuroblastoma than in Ewing cell lines. Among the 4 NCAM messengers (7.0, 6.5, 4.3 and 4.1 kb) detected in the neuroblastoma, the 6.5 kb species was largely predominant. The Ewing messenger RNA pattern was clearly different as the largest 7.0-kb species was virtually absent and the other bands were of similar intensities.

Animals↗
PubMed1987

Transient vs. steady end-systolic pressure-volume relation in dog left ventricle.

We compared transient slope of end-systolic pressure-volume line (T-Emax) with steady Emax (S-Emax) in isolated cross-circulated canine left ventricles. T-Emax is the slope of the end-systolic pressure-volume line (ESPVL) determined from the last steady-state ejecting contraction (SEC) and the first transient isovolumic contraction produced by end-diastolic volume clamp. S-Emax is the slope of ESPVL determined from five steady-state contractions by linear regression analysis. We obtained three T-Emax values in the same contractile state by changing ejection fraction (EF) of SEC to three levels (range 14-58%) from the same end-diastolic volume. T-Emax variably increased with EF in any contractile state. The ratios of the three T-Emax values to the same S-Emax value was 1.08 +/- 0.04 (11 ventricles, means +/- SE) for high EF, 0.87 +/- 0.06 for middle EF, and 0.69 +/- 0.07 for low EF in control contractile state. These ratios decreased under epinephrine and increased under propranolol. We conclude that T-Emax depends not only on EF but also on contractile state in isolated dog left ventricles.

Animals↗
PubMed1987

Left ventricular O2 consumption and pressure-volume area in puppies.

We studied the relation between O2 consumption (VO2) and systolic pressure-volume (PV) area (PVA) in the left ventricles of eight puppies (2-4 mo old). PVA is the area circumscribed by the end-systolic and end-diastolic PV curves and systolic PV trajectory. We assumed PVA to represent the total mechanical energy generated by ventricular contraction. We produced isovolumic contractions at different volumes in the left ventricles isolated and cross-circulated with adult dogs. VO2 closely correlated with PVA in each of control contractile state, an enhanced contractile state with epinephrine, and a depressed contractile state with propranolol in each heart. The slope of the regression line of VO2 on PVA was not significantly affected by epinephrine and propranolol. The regression line shifted upward with epinephrine and downward with propranolol. These characteristics of the puppy's VO2-PVA relation were comparable to those of the adult dog. These results suggest that similar relations hold between myocardial mechanics and energetics in both the puppy and adult dog despite the differences in the heart size and contractile properties.

Animals↗
PubMed1987

[Univentricular heart and pulmonary stenosis with a right-to-left shunt between the innominate and pulmonary veins after Glenn operation: a case report].

A 12-year-old girl with a univentricular heart and pulmonary stenosis, who had undergone Glenn operation at two years of age and Fontan operation at 11 years of age, had a right-to-left shunt via collaterals between the innominate and pulmonary veins. This right-to-left shunt was detected by two-dimensional contrast echocardiography. The contrast material was injected into the left antecubital vein appeared in the left atrium, and this was confirmed by innominate venography. The contrast material injected into the left innominate vein passed via the collaterals into the pulmonary veins bilaterally. No such cases have so far been reported. In our experience, in four of six cases after Glenn operation, including the present case, the abnormal collateral circulation from the superior vena cava to the atrium was detected by two-dimensional contrast echocardiography. This case is interesting embryologically and suggests that the connection between the pulmonary and systemic veins which is present in early fetal life, and subsequently disappears, was present after birth.

Adolescent↗
PubMed1987

[A case of aneurysmal dilatation of a saphenous vein graft for subclavian aneurysm in a patient with Behçet disease].

The autogenous saphenous vein is the preferred conduit for repair of occluded arteries in the limb and coronary arteries. The aneurysmal dilatation of the vein graft is a unusual complication in the long-term period. A case of aneurysmal formation of the vein graft for the subclavian aneurysm 5 years after grafting with classic Behçet disease was reported. The etiology of this rare complication and the special surgical problem were also discussed.

Adult↗
PubMed1986

Cardiac oxygen consumption and systolic pressure volume area.

Since we found that the total mechanical energy generated by ventricular contraction could be represented by a specific area (PVA) in the pressure-volume diagram, we have been studying the correlation between myocardial oxygen consumption (VO2) per beat and PVA in dog left ventricles. VO2 was found to be closely and linearly correlated with PVA under a variety of loading, heart rate, and contractile conditions. The regression of VO2 on PVA was given by VO2 = A X PVA + B.A was 1.8 X 10(-5) ml O2/(mm Hg ml) on the average and was relatively constant despite the changes in loading, heart rate, and contractile conditions. B was 0.02 ml O2/beat/100 g on the average in control contractile state and was relatively constant despite the changes in loading and heart rate conditions. However, B increased by 50-80% with 70-80% increases in Emax by epinephrine or calcium infused into the coronary circulation. After both VO2 and PVA were expressed in J/beat/100 g, the inverse of the slope coefficient A indicated that the energy conversion efficiency of PVA from the excess VO2 above the VO2 of the mechanically unloaded contraction was relatively constant at 40%, independent of the loading, heart rate, and contractile conditions.

Animals↗