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Biomedical subjects

S Chien

Publications and source records attributed to S Chien.

401 records · Page 23Linked to original sources
PubMedDate not supplied

Spontaneous activation of circulating granulocytes in patients with acute myocardial and cerebral diseases.

Recent animal studies have suggested that there exists an activated subpopulation of circulating granulocytes which plays an important part in microvascular sequestration and tissue injury during shock and ischemia. In this respect, spontaneous granulocyte activation in form of pseudopod formation, a manifestation of actin polymerization, is a high risk for microvascular entrapment. The present investigation was carried out to determine if there is a significant difference in pseudopod formation in vitro between granulocytes obtained from healthy volunteers without symptoms and patients with acute cardiovascular illnesses. Blood samples from 25 healthy volunteers, 12 patients with acute myocardial infarction (AMI) and 12 patients with acute cerebral infarction (ACI) to determine spontaneous pseudopod formation in granulocytes with a high resolution light microscope over a period of several hours. The results revealed that the mean percentage of cells with pseudopod formation in the control group was below 10% in the first 3 hours, and increased to about 50% at 12 hours. In AMI patients, the level of activation within the first hour was not significantly different from the controls, but it rose rapidly to 90% in 4 to 5 hours. Patients with cerebral infarction, however, showed no significant difference from the control group. When the granulocytes of healthy subjects were incubated in plasma of AMI, the cells were activated similar to AMI granulocytes in their own plasma. When AMI plasma was serially diluted with Ringer's solution, the activation curve fell successively. These results indicate that AMI patients' blood contains plasma factor(s) which can activate granulocytes at a more rapid rate than controls.

Cells, Cultured↗
PubMedDate not supplied

A fractal model for erythrocyte sedimentation.

The erythrocyte sedimentation test is a useful tool for studying the biophysical properties of red blood cells (RBCs) and the interactions between RBCs and bridging macromolecules in the suspending fluid. In our previous model of erythrocyte sedimentation formulated on the basis of a logistic growth equation of population dynamics (Kuo et al., 1989), the sedimentation rate constant, r, was assumed to be an intrinsic constant characteristic of the interaction between RBCs and bridging macromolecules in the suspending fluid. By analyzing the time dependence of r in that model, however, it was found that r depends on the sedimentation time, t. There is a power law relation between r(t) and t; the rate "constant" is therefore an effective kinetic rate constant rather than a true constant. The realization that r is an effective kinetic rate constant allowed the introduction of a power law function r(t) into the formalism of erythrocyte sedimentation. Doing so yielded a new model with the following capacities: (a) The skew-symmetric sedimentation curves can be modeled; (b) the experimental data can be fitted better with the new sedimentation equations; (c) a fractal dimension, D, and a new rate constant, k, can be defined; (d) the tendency for a certain amount of plasma to be trapped inside the rouleau network, xi, can be accounted for. The D, k, xi, and other parameters can be used in the analysis of RBC interactions mediated by bridging macromolecules.

Blood Sedimentation↗
PubMedDate not supplied

Two step cardiomyoplasty with vascular delay: effect of stimulation of latissimus dorsi muscle on diastolic function.

A common concern in cardiomyoplasty is whether latissimus dorsi muscle (LDM) stimulation impairs diastolic function. This study determined the time course of left ventricular (LV) contraction and relaxation and their relationship to the diastolic function. Ten mongrel dogs underwent vascular delay of the left latissimus dorsi muscle 2 weeks before cardiomyoplasty. Fourteen to 18 days later, the effects of LDM stimulation were evaluated. Our study demonstrated that LDM stimulation significantly increased peak LV systolic pressure (131.3 +/- 7.5 to 152.0 +/- 7.5* mm Hg), +dP/dt (1585 +/- 151 to 2088 +/- 176 x mm Hg/s), stroke volume (10.8 +/- 1.5 to 13.8 +/- 1.9* ml), stroke work (17.2 +/- 2.7 to 25.6 +/- 3.8* gm x m), and peak aortic flow (4751 +/- 698 to 6712 +/- 926* ml/min), and significantly decreased the pre-ejection time (113.9 +/- 12.6 to 92.3 +/- 7.8* ms) and total systolic time (366.0 +/- 26.9 to 333.6 +/- 21.3* ms) (*p < 0.05). As for diastolic function, LDM stimulation decreased -dP/dt (-1462 +/- 116 to -1781 +/-116* mm Hg/s) and tau (64.0 +/- 6.1 to 52.1 +/- 2.9* ms). The diastolic filling time (Tdf) was significantly longer (177.9 +/- 17.6 to 213.7 +/- 18.7* ms) during the beat immediately after LDM stimulation. These changes reflected an overall stronger contraction and faster relaxation. Our results imply that with vascular delay, stimulation of LDM not only assists systolic function but also improves diastolic function in cardiomyoplasty.

Animals↗