Biomedical subjects

M Handa

Publications and source records attributed to M Handa.

274 records · Page 16Linked to original sources

PubMedDate not supplied

Functional and histopathologic studies of primate pulmonary allografts preserved for 24 hours with a form of modified extracellular solution.

BACKGROUND: The purpose of this investigation was to evaluate the efficacy of a solution (Ep4) for long-term hypothermic pulmonary allograft preservation in a primate model using both functional and histopathologic criteria. METHODS: Twenty-seven Japanese monkeys were divided into donor group and three study groups. The animals in group I underwent acute left lung transplantation (n = 5). Group II consisted of animals which received left pulmonary allografts preserved for 24 hours by simple hypothermic immersion in Ep4 solution (n = 6). The temporary contralateral (right) pulmonary artery occlusion test was performed immediately after transplantation and on postoperative day 7 to assess lung function in the allografts. This test was also performed in the control group (group III, n = 5). The recipient animals in groups I and II were also subjected to serial open lung biopsies and bronchoscopic assessments after transplantation. RESULTS: Temporary right pulmonary artery occlusion did not show any significant differences in gas exchange capacity and pulmonary hemodynamics between groups I and II. Histopathologic examination did not show significant differences in the pulmonary allografts between groups I and II for a period of 4 weeks after transplantation. Serial bronchoscopic and histologic examinations also showed no significant differences in bronchial healing between these two groups. CONCLUSIONS: Long-term hypothermic pulmonary allograft preservation with Ep4 solution does not impair pulmonary function immediately after transplantation. The results of this study indicate that extracellular electrolyte composition solutions such as Ep4 should be subjected to clinical trials.

Animals↗

PubMedDate not supplied

Thrombocytopenia responsive to warfarin in a patient with systemic sclerosis--systemic lupus erythematosus overlap.

We report a patient with overlapping systemic sclerosis-systemic lupus erythematosus who developed refractory thrombocytopenia and recurrent thromboses. Coagulation and platelet labeling studies revealed that platelets were being consumed by the thrombus formation, and anticoagulation with warfarin dramatically increased the platelet count. This case report suggests that platelet consumption due to thrombus formation is one of the causes of thrombocytopenia in patients with rheumatic disease.

Blood Platelets↗

PubMedDate not supplied

[Low concentrations of epinephrine can augment shear stress-induced platelet aggregation].

Platelet aggregation induced by shear stress is distinct from that induced by an agonist such as ADP or collagen. The physiological significance of shear-induced platelet aggregation was investigated by measuring the effects of the presence of physiological concentrations of epinephrine. Blood samples were taken from 10 normal volunteers who had received no drugs known to interfere with platelet functions for 1 month preceding the study. Blood was mixed with 1/10 volume of 3.1% sodium citrate solution. Platelet-rich plasma and platelet-poor plasma were prepared by centrifugation at 100 g for 15 min and 2,000 g for 15 min, respectively. The platelet count of platelet-rich plasma was adjusted to 3 x 10(5)/microliters. Shear-induced platelet aggregation in platelet-rich plasma was determined using a modified cone and plate viscometer controlled by a personal computer system. The intensity of light transmission was continuously recorded. The percent platelet aggregation was calculated according to the Lambert-Beer equation. Platelet aggregation occurred under both low (12 dyn/cm2) and high (108 dyn/cm2) shear stress. More significant aggregation was observed under high shear stress. The maximum percent platelet aggregation was 44.7 +/- 13.4%, which increased to 53.3 +/- 10.0% in the presence of 10 pg/ml epinephrine. With 100 pg/ml of epinephrine, shear-induced platelet aggregation induced by 12 dyn/cm2 shear significantly increased, but the effects on shear-induced platelet aggregation of 108 dyn/cm2 shear were not uniform. Shear-induced platelet aggregation is enhanced by physiological concentrations of epinephrine, which may be a cause of arterial thrombotic occlusion in sympathomimetic states.

Adult↗

PubMedDate not supplied

A new method for continuous measurement of platelet adhesion under flow conditions.

Platelet adhesion to the subendothelial tissue or biomaterial surface is an initial step in the formation of the hemostatic plug or thrombus. To clarify the mechanism of platelet adhesion in vivo, a simple and reproducible method for quantitation of platelet adhesion under flow conditions is required. In this study, a mechanical device for continuous recording of platelet adhesion under flow conditions using a quartz crystal microbalance was developed, an extremely sensitive sensor capable of measuring mass changes in the nanogram range. The relationship between surface mass change (delta W) and resonant frequency change (delta f) for pie-zoelectric crystals is given by the Sauerbrey equation: delta f = -fo2 delta W/NA pi (fo; fundamental frequency (5MHz) A; the area of quartz plate undergoing oscillation N; frequency constant for AT-cut quartz crystal pi; density of quartz crystal). Although the perfusion of buffer solution alone or addition of washed red cell suspension (Ht 30%) and formaldehyde-fixed platelets have no effect on delta f, addition of washed platelets in the presence of red cells caused an increase in delta f. To confirm that the increase in delta f results from platelet adhesion to the material surface, adherent and subsequently aggregated platelets were visualized by fluorescence microscopy using fluorescein-isothiocyanate labeled antiplatelet membrane glycoprotein Ib monoclonal antibody. There was a good correlation between the increase in delta f and the extent of platelet adhesion and subsequent aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗