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Biomedical subjects

S Chien

Publications and source records attributed to S Chien.

At least 307 records · Page 17Linked to original sources
PubMed1978

Hyperviscosity syndrome attributable to hyperglobulinemia in chronic active hepatitis.

A young women with clinical and histological features of chronic active hepatitis was noted to have extremely high levels of immunoglobulin (14.6 g per dl). This was associated with the hyperviscosity syndrome, diffuse coagulation abnormalities, and renal insufficiency in the absence of severe liver disease. Correction of these features occurred with plasmapheresis before corticosteroid therapy was begun. A similar group of persons with very high gamma-globulin levels, described previously under the heading of "plasma cell hepatitis," may form a distinct and rare subgroup of chronic active hepatitis patients.

Adolescent↗
PubMed1977

Changes in blood viscosity and plasma proteins in carcinoma.

Blood viscosity and plasma protein concentrations were measured in 31 patients with a variety of visceral carcinomas. The mean whole blood viscosity was not elevated over normal controls because of a significantly lowered mean hematocrit. However, when hematocrit was eliminated as a variable by adjusting the hematocrit to 45%, the mean whole blood viscosity was significantly elevated in the group with carcinoma. Both the plasma viscosity and the tendency for red cell aggregation were significantly elevated. Since blood is a non-Newtonian fluid, and its viscosity increases markedly at low shear rates, these rheological abnormalities would be most important at the low shear rates characteristic of the venous circulation. It is suggested that these abnormalities in blood viscosity and red cell aggregation may be contributing to the high incidence of venous thromboembolism seen in patients with neoplastic.

Alpha-Globulins↗
PubMed1977

Effect of hematocrit variations on coronary hemodynamics and oxygen utilization.

Twenty-five closed-chest pentobarbitalized dogs were used for studying coronary flow dynamics and myocardial oxygen utilization following variations of hematocrit (Hct) by isovolumetric exchange of blood with plasma or packed red cells. Coronary blood flow (133Xe washout) and cardiac output varied inversely with Hct. Coronary systemic, and pulmonary flow resistances varied in the same direction with Hct. Blood viscosity played a significant role in determining the flow resistances in these three regions. Analysis of vascular hindrance (vascular resistance/blood viscosity) suggested that coronary vasodilation occurred following Hct changes beyond the range of 20-60%. In systemic and pulmonary circulations, however, there was vasoconstriction following hemodilution. The range of optimum Hct for maximum O2 transport (blood flow X arterial O2 content) was much wider in coronary (20-60% Hct) than in systemic circulation (40-60% Hct). The O2 consumptions in total body and in myocardium were essentially constant over a wide range of Hct (20-60%). The maintenance of total body O2 consumption over the Hct range of 20-40% was attributable to an increase in A-V O2 extraction. The O2 extraction ratio in the coronary circulation was constant over the entire range of Hct studied, suggesting that the myocardial O2 consumption was primarily determined by the coronary O2 transport.

Animals↗
PubMed1977

Plasma volume, red cell volume, and thoracic duct lymph flow in hypothermia.

The effects of hypothermia on plasma volume (125I-albumin), red blood cell volume (51 Cr-RBC), and capillary permeability (thoracic duct lymph flow and protein concentration) were determined on dogs anesthetized with pentobarbital, paralyzed with succinylcholine, and mechanically ventilated. Red blood cell volume and plasma protein concentration did not change significantly after cooling. Reductions in plasma volume and total plasma proteins indicate that whole plasma was excluded from the effective circulating blood volume. Except for a lesser increase in hematocrit, chronically splenectomized dogs showed essentially the same changes as normal dogs in response to hypothermia. Following application of ice bags, there was a biphasic response in lymph flow. The early increase in lymph flow accompanying a slight decrease in plasma volume was attributable to transcapillary fluid loss into interstitial space, probably due to cold-induced sympathetic activity. The later decrease in lymph flow in hypothermia resulted from a decrease of lymph production secondary to a decrease in available capillary diffusion area. This decrease in lymph flows and the continued reduction in plasma volume suggest an intravascular sequestration of whole plasma.

Animals↗
PubMed1977

Partition of xenon and iodoantipyrine among erythrocytes, plasma, and myocardium.

A new method was developed for determining directly the distribution of 133Xe between red cells and plasma in vitro without an air-fluid interface; the partitioning of 133Xe and 133-i-iodantipyrine between blood and myocardium was investigated in the dog in situ. The red cell-plasma partition coefficient for 133Xe (lambdacpX, unit: ml/ml) at 37 degrees C was 2.27 +/- 0.07 (mean +/- SD) for human blood and 3.31 +/- 0.06 for dog blood. The red cell-plasma partition coefficient for 131I-iodantipyrine (lambdacpI, ml/ml) was 0.75 +/- 0.04 for human blood and 0.97 +/- 0.03 for dog blood. lambdacpX and lambdacpI did not change significantly after the intravenous administration of sodium pentobarbital (30 mg/kg) into the dog. lambdacpX of dog blood varied inversely with temperature, whereas lambdacpI showed very little change with temperature. The blood-left ventricle partition coefficient for 133Xe (lambda'btX, corrected for trapped blood) varied directly with directly with red cell volume fraction (H): lambda'btX = 1.32 + 2.00 H. Blood-left ventricle partition coefficient for 131I-iodoanitpyrine did not vary significantly with H. The results support the concept of a three-compartment partition of the indicator among erythrocytes, plasma, and myocardium. The mean values (+/- SD) of the hematocrit-independent plasma-tissue partition coefficient in the left ventricle for 133Xe and 131I-iodoantipyrine were 1.08 +/- 0.16 and 1.54 +/- 0.20 g/ml, respectively.

Anesthesia, Intravenous↗
PubMed1977

Effect of hematocrit on the washout of xenon and iodantipyrine from dog myocardium.

The rates of washout of 133Xe and 131I-iodoantipyrine from the myocardium into the coronary sinus blood were determined over a wide range of hematocrits after simultaneous injection of the isotopes into the left anterior descending coronary artery of dogs. The ratio of the monoexponential disappearance constants (kX/kI), which is a measure of the ratio of the dynamic blood-tissue partition coefficients (lambdabIX/lambdabtI), increases linearly with hematocrit. This dynamic lambdabt ratio has almost the same relationship to hematocrit as the static lambdabt ratio. By the use of appropriate hemotocrit-specific lambdabt values, we found that simultaneous blood flows calculated from the two indicators with different disappearance constants showed excellent agreement. If this hematocrit-dependent alteration in indicator partitioning is neglected, blood flow measurement in the dog with 133Xe washout may introduce an error of approximately 1.15% per unit hematocrit deviation from the normal value (taken as 45%), whereas blood flow measurements with 131I-iodanatipyrine washout had negligible errors.

Animals↗
PubMed1977

Clinical rheology in cardiovascular disease.

A protocol has been designed to evaluate the role of each of 4 determinants of blood viscosity. Studies on cardiovascular diseases showed that abnormal blood rheology may play a role in hemodynamic derangements. Investigations on clinical rheology not only help to elucidate the pathophysiological basis of the disease process, but also serve to improve our understanding of the fundamental mechanisms of regulation of blood viscosity.

Anemia, Sickle Cell↗
PubMed1976

Significance of macrorheology and microrheology in atherogenesis.

Atheromatous lesions represent a disturbance of homeostasis in the arterial wall, where the rates of uptake and production of atherogenic materials exceed the rates of egress and metabolic removal. The pressure and flow in the arterial system generate circumferential stress in the wall and shear stress on the wall. The magnitude and distribution of these stresses are affected by local vascular geometry and microrheologic behavior of blood. Circumferential stress is borne primarily by the media and adventitia, and shear stress has a greater influence on the endothelial cells, which form the principal barrier to transport of macromolecules into the arterial wall. Shear stress, turbulence, and longitudinal stretch cause an increase of macromolecular uptake by arterial wall, especially when the mechanical disturbances are periodic. These effects may be explained by an enhanced diffusion of plasmalemmal vesicles in the endothelial cells. Such short-term effects of rheologic factors should be considered together with their long-term influences on the structure and function of the arterial wall in order to elucidate the role of rheology in atherogenesis.

Arteries↗
PubMed1975

Blood viscosity, plasma proteins, and Raynaud syndrome.

The rheology of the blood was studied in 20 patients with Raynaud syndrome. Sixteen patients had scleroderma, two had nonspecific angiitis, one had systemic lupus erythematosus, and one had Raynaud disease. Viscosity measurements were performed on whole blood, plasma, and suspensions of 45% red blood cells (RBCs). In autologous plasma, over a wide range of shear rates. The relative viscosity, an index of RBC aggregation, was obtained by dividing the RBC viscosity in autologous plasma (at a hematocrit value of 45%) by the plasma viscosity. Concentrations of the plasma globulins and fibrinogen were also measured. The mean plasma viscosity was significantly (P less than .01) elevated over established normal controls. The mean RBC viscosity and the relative viscosity were significantly (P less than .01) elevated over normal controls, as were fibrinogen and the globulins. These studies demonstrate increased blood viscosity and red blood cell aggregation, which may constitute an important hindrance to flow.

Adolescent↗
PubMed1975

Longitudinal measurements of blood volume and essential body mass in human subjects.

Repeated determinations of blood volume and body density were made on 34 Chinese subjects (28 men and 6 women) in Taiwan over a period of 12 yr, as the mean age increased from 31 to 43 yr. Essential body mass calculated from body density and body weight showed no significant change over the 12-yr period. Changes in body weight (mean gain equals 6.0 kg) were attributable to alterations in adipose tissue weight, the density of which was found to be 0.948 g/cm3. In two-thirds of the subjects the second blood volume increased by more than 5% over the first determination, and the mean blood volume for all subjects increased by 7.5% (P less than 0.01). Correlation of the blood volume data with the findings on essential body mass and adipose tissue mass suggests that blood content per unit tissue mass increased in the second determination. This interpretation is supported by the increase in nutrient availability in Taiwan over the 12-yr period, and it may explain the lack of blood volume increase in an earlier longitudinal study on American subjects with stable nutrient availability.

Adult↗
PubMed1975

Longitudinal studies on adipose tissue and its distribution in human subjects.

On 27 men and 6 women, total body density and 10 skinfolds were measured 12 yr apart, with the mean age increasing from 31 to 43 yr. The increase in skinfold thickness was found to be related to the increase in total body adiposity, calculated from hydrostatic weighing. The external adipose tissue was calculated from the mean skinfold thickness and body surface area. Variations in total adiposity among the population studied as well as changes in total adiposity with age showed a characteristic distribution with approximately two-thirds on the surface and one-third in the interior. The essential body mass or total adipose mass determined by hydrostatic weighing was compared with the values obtained by water-immersion volumetry, total body potassium counting, and skinfold measurements. Teh volumetric and skinfold determinations gave better estimates of these parameters than total body potassium counting.

Adipose Tissue↗
PubMed1975

Correlation of blood rheology with vascular resistance in critically ill patients.

Blood rheologic measurements together with peripheral resistance determinations in vivo were made in 27 critically ill patients. Eighteen of these patients (group I) suffered from violent trauma or operative injury and the other 9 (group II) were patients with generalized sepsis. As a result of fluid therapy all patients underwent hemodilution, resulting in a decrease in blood viscosity. This drop in blood viscosity was counteracted to some extent by an increased plasma viscosity due to elevated fibrinogen levels and a decreased red cell deformability associated with massive transfusions of stored blood. The correlation of vivo hemodynamics with blood rheological data made it possible to separate the relative roles of vascular dimensions and blood viscosity in affecting the total peripheral resistance. This approach permitted us to distinguish varying degrees of vasoconstriction in nonseptic patients in low flow states (group I) and varying degrees of vasodilation in septic patients (group II). This type of analysis serves to elucidate the pathophysiology of hemodynamic alterations in disease and provides a rational basis for devising an effective therapeutic program.

Acute Disease↗