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Biomedical subjects

T Kawara

Publications and source records attributed to T Kawara.

At least 91 records · Page 5Linked to original sources
PubMed1992

Congenital quadricuspid aortic valve associated with aortic regurgitation.

A case of quadricuspid aortic valve is described. The aortic valve consisted of 3 equal-sized and 1 smaller cusps, and a supernumerary cusp located between the right and noncoronary cusps. A right coronary ostium was close to the accessory commissure, and in a lower position. Three fenestrations were found at the supernumerary commissure. Aortic valve replacement was performed successfully with a St. Jude Medical prosthetic valve. On histological examination, the resected cusps showed fibrotic thickening with calcification and no sign of previous inflammatory disease. Quadricuspid aortic valve must be considered a malformation capable of leading to severe valve failure in later life.

Aortic Valve↗
PubMed1992

[Clinical evaluation of bone marrow fibrosis in non-Hodgkin's lymphomas].

A study was performed in 62 patients with non-Hodgkin's lymphoma (ATL included) who were hospitalized between 1985 and 1991 and who underwent bone marrow aspiration and biopsy before or after treatment or at the time of recurrence. The relationships between the extent of bone marrow fibrosis and other prognostic factors as well as the effects of chemotherapy and bone marrow fibrositic prognosis were examined. The results were as follows: 1) The periods of survival in patients with high degree of fibrosis in bone marrow were significantly shortened. 2) The extent of bone marrow fibrosis significantly correlated with the presence or general symptoms, bone marrow invasion, and blood levels of LDH and Ca on blood biochemical examinations. 3) Effective therapy reduced collagen fibers as well as reticulin fibers in bone marrow. 4) Sixty-four percent of relapsing cases showed increase of bone marrow fibrosis. These results suggest that understanding the state of bone marrow fibrosis over the clinical course may give a good guide of indication the prognosis of malignant lymphoma.

Bone Marrow↗
PubMed1992

[Progress in clinical electrophysiologic study (EPS): recent tendency].

About twenty years have passed since the clinical introduction of electrophysiologic study (EPS). The mechanism of arrhythmias can be understood by EPS, and EPS-guided therapy is available theoretically. Of course, not all arrhythmia needs EPS, because other non-invasive tests are available. Clinically, reentry is the most frequently observed mechanism. Therefore, EPS is most suitable for the reentrant arrhythmias which can be repeatedly initiated and terminated by programmed stimulation. In many tachyarrhythmias, slow conduction pathway or area essential for reentry are demonstrated. On the other hand, triggered activity and abnormal automatism have been less frequently observed clinically. Today, application of EPS has been extended to catheter ablation for which precise mapping is required.

Arrhythmias, Cardiac↗
PubMed1991

Luminance-unbalanced pattern onset-offset electroretinogram and visual evoked cortical potential.

The effects of a luminance-unbalanced pattern onset-offset mode of stimulation on electroretinograms and visual evoked cortical potentials were investigated. With the use of originally devised software, only offset luminance was varied from 14.7 to 62.3 cd/m2. A vertical grating pattern (1.5 c/deg, 38.8 cd/m2 mean luminance, 0.95 contrast) was presented for 260 ms and was absent for 260 ms to normal subjects. With an increase in the luminance level of the offset pattern from the lowest level, the amplitude of the onset electroretinogram increased by degrees, while that of the offset electroretinogram gradually decreased. Conversely, onset visual evoked cortical potential responses decreased gradually, and offset visual evoked cortical potentials increased correspondingly. Furthermore, the spatial tuning of the onset pattern electroretinogram was already ambiguous, even when there was only a 4-cd/m2 difference between onset and offset pattern luminances. Thus, luminance control is indispensable for pattern onset-offset stimulation.

Adult↗
PubMed1991

Pathological aspects of radiofrequency catheter ablation of the canine atrioventricular node and bundle of His. With special reference to chronic incomplete atrioventricular block.

Radiofrequency catheter ablation of the atrioventricular (AV) node or bundle of His was performed in 12 adult mongrel dogs. The aim was to create chronic incomplete AV block (first- and second-degree AV block) and to examine the histopathology of the ablated lesions. However, the late electrophysiological results (2-4 weeks follow-up) were various: normal in 2 dogs, mild PR prolongation (less than 50%) in 2 dogs, first-degree AV block (PR prolongation greater than or equal to 50%) in 2 dogs, second-degree AV block in 2 dogs, complete AV block in 4 dogs. The maximally ablated area (%) of the atrioventricular conduction system in serial histologic sections from dogs with these conditions was 69%, 75%, 89.5%, 95% and 99.5%, respectively. The number of intact conduction cells at the maximally ablated site varied from 6 to 30 in the four cases of incomplete AV block. The mean ablated volume (%) of either the AV node or penetrating His bundle correlated roughly with the degree of AV block. The ablated lesions were well demarcated and almost replaced by dense fibrous tissue at 4 weeks. Interruption (3 dogs) or thinning (1 dog) of the endocardial elastic lamellae was detected, in association with endocardial thickening (mean 913 microns). Endocardial thrombi were found in 3 dogs (2 fresh, 1 organized). We conclude that radiofrequency catheter ablation does not cause severe complicated lesions. Several possible conditions for creating chronic incomplete AV block are discussed.

Animals↗
PubMed1991

Demonstration of right and left atrial dissociation by atrial rapid pacing or extrastimulation during fast-slow (uncommon) form of atrioventricular nodal reentrant tachycardia.

Some recent works suggest that extranodal atrial fibers may form part of the reentry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.

Adult↗
PubMed1991

Reoperation following total repair of congenital heart disease.

For the past 25 years we have performed 61 reoperations in 58 patients with congenital heart disease who previously underwent total correction for the diagnosed ventricular septal defect, tetralogy of Fallot, atrioventricular septal defect, atrial septal defect, total anomalous pulmonary venous connection (TAPVC), and other involvement for 27, 11, 5, 4, 4, and 7 patients, respectively. Causes of reoperation included 43 events of valvular lesion, 29 of residual septal defect, 5 of conduit failure, 5 of venous obstruction, 3 of hemolysis, 3 of infective endocarditis, and 2 of prosthetic valve dysfunction. Although 5 early and 4 late deaths were encountered, the remaining 49 patients (3 in New York Heart Association (NYHA) Class II and 46 in NYHA class I or II) survived the reoperation. The patients were followed up by echocardiography and chest X-ray examination, and reoperation was indicated under the following conditions: moderate to severe valvular insufficiency; residual defect causing the shunt ratio to be over 30% or a systolic pulmonary pressure over 50 mmHg; or a high pressure gradient over 50 mmHg across the right ventricular outflow tract. Early timing for reoperation seemed to be important in patients with pulmonary venous obstruction, prosthetic dysfunction, severe hemolysis and infective endocarditis.

Adolescent↗
PubMed1989

Rearrangement of T-cell receptor delta chain gene as a marker of lineage and clonality in T-cell lymphoproliferative disorders.

We analyzed the rearrangement of T-cell receptor (TcR) delta chain gene in 88 cases of lymphoproliferative disorders; 31 acute lymphoblastic leukemias/lymphoblastic lymphomas (ALL/LBL); 27 adult T-cell leukemias/lymphomas, 9 angioimmunoblastic lymphoadenopathies (AILD); 10 T-cell lymphomas (non-Hodgkin's lymphoma); and 11 Hodgkin's disease. All of 9 T-ALL/LBL cases, of which 4 cases have neither beta nor gamma gene rearrangement, had a new rearranged band of TcR delta locus. Ten of 16 B-lineage ALL/LBL had rearranged band(s) or deletion of TcR delta locus. The rearranged bands were recognized in 2 cases of AILD and 1 case of T-cell lymphoma. All cases of adult T-cell leukemias/lymphomas, 4 of AILD, 4 of T-cell lymphoma, and 8 of Hodgkin's disease had deleted TcR delta locus. Heterogeneous findings of TcR delta locus analysis were observed in AILD, T-cell lymphoma, and Hodgkin's disease. In 16 cases with TcR delta rearrangement, the J delta 1 region was frequently used and the J delta 2 region was rearranged in one AILD. It is suspected that J delta 3 was used in one T-ALL/LBL. There was no correlation between the phenotypic pattern of CD3, CD4, CD8 in T-cell disorders and the rearrangement of the TcR delta gene. These findings suggest that the newly identified TcR delta chain gene rearranges at a very early stage of T-cell ontogeny; prior to the other TcR genes and perhaps at almost the same stage with CD7 expression. The TcR delta gene is useful in assessing clonality for the most immature T-cell neoplasms not showing rearrangement of the other TcR genes. This gene is not lineage specific; however, when used in conjunction with immunoglobulin heavy chain gene, it may be a useful tool to distinguish lymphoid lineage of ALL/LBL.

Gene Rearrangement, T-Lymphocyte↗
PubMed1989

Human visual spatio-temporal frequency performance as a function of age.

Deterioration of human spatial frequency contrast sensitivity with increasing age was measured, for both stationary and drifting gratings, by producing interference fringes directly on the subject's retinas. There were losses at high spatial frequency up to 40 years of age, and losses at all spatial frequencies thereafter. Older subjects exhibited better than expected performance for drifting low spatial frequency gratings. These results are consistent with the differential effects of aging on different populations of visual neurons.

Adult↗
PubMed1989

Electrophysiological demonstration of anterograde concealed conduction in accessory atrioventricular pathways capable only of retrograde conduction.

Anterograde concealed conduction into the concealed accessory atrioventricular (AV) pathway has been postulated to be one of the factors preventing the reciprocating process via the accessory pathway in patients with the concealed Wolff-Parkinson-White(WPW) syndrome but its presence has not been documented. To demonstrate the occurrence of anterograde concealment, 12 patients with the concealed WPW syndrome were selected for study. A pacing protocol was designed in which the retrograde conduction of the ventricular extrastimulus over the accessory pathway was assessed during ventricular pacing alone (conventional method) and during the AV simultaneous pacing (simultaneous method); the results were then compared. When the high right atrium was simultaneously paced, the effective refractory period of the concealed accessory pathway shortened as compared with the conventional method in five of 12 patients (from 341.7 +/- 110.8 to 312.5 +/- 108.2 msec, n = 12), whereas, it decreased in all patients studied when the coronary sinus near the accessory pathway was simultaneously paced (from 375.7 +/- 135.0 to 287.1 +/- 116.1 msec, n = 7). These results demonstrate that the AV simultaneous pacing frequently shortens the refractoriness of the concealed accessory AV pathway and such facilitation seems to be well explained by the probable anterograde concealment in it and peeling back of the refractory barrier.

Atrioventricular Node↗
PubMed1989

[Secondary leukemia (AML) with TcR beta rearrangement].

A 60-year-old female with fever and general lymphadenopathy was admitted to our hospital in 1979. By histological examination of cervical lymph node, she was diagnosed as B-cell malignant lymphoma, diffuse, large, stage IV B (Ann Arbor classification). In 1984, the complete remission of malignant lymphoma was observed after MOPP, COPP and VAPP chemotherapies. After 3 years, she was readmitted because of leukocytosis in which 64% immature abnormal cells were detected. By conventional cytological and cytochemical evaluations, the immature abnormal cells were identified as secondary AML cells with M 2 type (FAB), peroxidase (+), My 7 (+) and chromosomal abnormality; 48, X, -X, +4, -9, +21, del (1) (p 34), i (17 q), + M 1, + M 2. Analysis of Ig and TcR genes showed TcR-beta rearrangement. It has been reported that secondary leukemia frequently causes chromosomal abnormalities and therapy resistance. Ig gene and TcR gene analysis of secondary leukemia combined with chromosome examination, which has reported little, may be useful in predicting prognosis and therapy resistance.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Changes in lymphocyte subsets, mitogen responsiveness, and interleukin-2 production after cardiac operations.

We studied 104 patients after cardiac operations to search for changes in peripheral blood lymphocyte subsets, mitogen responsiveness, and interleukin-2 production. Mononuclear cells obtained from 10 patients with cholecystectomy were examined as control samples. Cultures for phytohemagglutinin and interleukin-2 production were incubated in microtiter plates for 24 hours with cells labeled with tritium thymidine used as target cells. Lymphocyte subsets were measured by using monoclonal antibodies. The results obtained with preoperative blood samples were compared with those from the first, third, and seventh days after operation. In patients having cardiac operations, mitogen responsiveness was low on both the first and the seventh days after operation and interleukin-2 production was markedly depressed (greater than 90% depressed) on the first postoperative day. However, in control samples from patients having cholecystectomy, lymphocyte subsets, mitogen responsiveness, and interleukin-2 production showed no significant changes. Improvement in interleukin-2 production occurred immediately in patients without blood transfusion from random donors and reached normal levels by postoperative day 3. However, interleukin-2 production remained depressed on day 3 in all patients with transfusion from random donors and remained significantly diminished even on day 7 in such patients in New York Heart Association classes III and IV. We conclude that heart operations for which cardiopulmonary bypass is used are associated with depression of cellular immunity, including interleukin-2 production. Furthermore, it appears that both blood transfusion from random donors and the general preoperative condition of the patients contribute to suppression of measures of cell-mediated immunity.

Adult↗
PubMed1987

Topographical study of stereo-related potentials.

In order to estimate objectively binocular vision and especially stereopsis, random dot stereograms generated by a personal computer were used. Brain activity during stereopsis was topographically studied by visually evoked potentials (VEPs). The potentials evoked by binocular viewing of patterns without disparity, e.g. correlogram, were very similar to the potentials evoked from patterns with disparity, i.e. stereogram, as many authors have already indicated. To derive the stereo-related potentials from the VEP elicited by stereograms, the potentials evoked by correlograms were subtracted from the potentials evoked by stereograms, and the differences of topographical distribution between normal and stereoblind subjects were investigated.

Adult↗