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Biomedical subjects

W T Chen

Publications and source records attributed to W T Chen.

155 records · Page 9Linked to original sources
PubMed1977

Determination of plasticizer levels in serum of hemodialysis patients.

Serum DEHP levels were measured on 27 hemodialysis patients at various time intervals. The following results were obtained: 1) Predialysis levels of DEHP occurred in only one of 22 samples. 2) Postdialysis serum levels reached a mean of 751 nGm DEHP/ml serum. 3) Samples from patients with less than 50 hemodialysis treatments gave a mean of 558 nGm/ml, while those with more than 50 treatments gave a mean of 973 nGM/ml. These numbers were found to be significantly different at a 95% confidence level. 4) No difference in DEHP levels were found for males and females. 5) The appearance of DEHP during dialysis and its disappearance after dialysis were found to be biphasic. 6) No correlation was found between serum DEHP and triglyceride levels in postdialysis serum samples.

Female↗
PubMed1975

Direct effects of hypoosmolality on vascular resistance and myocardial contractile force (38587).

Hemodialysis was used to study the direct effects of acute hypoosmolality upon the resistance to blood flow through the gracilis and coronary vascular beds and upon left ventricular contractile force in the dog. When sodium chloride was removed from the blood perfusing the gracilis vascular bed, resistance increased linearly over the range 300-225 mOsm/kg. A 10% decrease in osmolality produces a 20% increase in resistance. When the removed sodium dhloride was replaced with mannitol such that plasma osmolality did not change, resistance rose slightly but failed to regularly return to the control value. Hypoosmolality also raised coronary vascular resistance and this was associated with an increase in left ventricular force. Thus direct effects of hypoosmolality on peripheral vascular beds and perhaps myocardium may participate in the compensatory mechanisms that tend to stabilize blood pressure during hypoosmotic states such as acute salt depletion.

Animals↗
PubMedDate not supplied

Local degradation of fibronectin at sites of expression of the transforming gene product pp60src.

Local degradation of extracellular fibronectin, a major extracellular adhesive protein, is believed to play an important part in the migration of cells through the extracellular matrix during tumour invasion, morphogenetic movement and trophoblast implantation. Fibronectin is lost from the cell surface after transformation with Rous sarcoma virus (RSV). By using fluorescent and radiolabelled probes covalently coupled to the surface of substrata, we have recently identified a proteolytic activity that is expressed in RSV-transformed cells and is involved in the local degradation of fibronectin at cell-substratum contact sites. Here, we extend the relevance of these findings and gain some insight into the cellular functions of pp60src, the transforming gene product of RSV. We show that newly expressed viral pp60src is localized at the cytoplasmic surface of the cell membrane, corresponding to the cell contact sites where degradation of extracellular fibronectin occurs.

Animals↗
PubMedDate not supplied

Effect of hemodialysis on blood volume distribution and cardiac output.

Effects of hemodialysis on extracellular fluid volume distribution, left ventricular volumes, and cardiac output were determined in patients with end-stage renal disease (n = 19). Distribution of extracellular fluid loss from hemodialysis differed widely among patients, so that weight change correlated weakly with contraction of total blood volume (index of determination 29%, p less than 0.05). End-diastolic volume (EDV) decreased from 150 +/- 49 ml (mean +/- SD) to 118 +/- 42 ml, p less than 0.001; stroke volume (SV) decreased from 108 +/- 36 to 86 +/- 33 ml (p less than 0.001) without change in ejection fraction (from 0.73 +/- 0.09 to 0.74 +/- 0.11). A significant correlation was found between total blood volume (TBV) and EDV before (r = 0.66, p less than 0.005) and after dialysis (r = 0.61, p less than 0.001). The correlation between TBV and SV was highly significant before (r = 0.78, p less than 0.001) and after dialysis (r = 0.66, p less than 0.005), but there was no correlation between change in TBV and change in EDV or in SV. The ratio of EDV to TBV (EDV/TBV x 100) was reduced significantly from 3.49 +/- 0.92 to 3.06 +/- 0.97, p less than 0.001). There results suggest that, although intravascular volume was the major determinant of cardiac output in dialyzed patients, the postdialysis reduction in cardiac output might be related more to the relocation of blood volume than to the absolute degree of blood volume contraction.

Blood Volume↗
PubMedDate not supplied

Blood pressure response to hemodialysis.

Blood pressure response to hemodialysis was investigated in 15 patients with end-stage kidney disease; mean arterial pressure was unchanged in five (Group 1) and reduced 10 mm Hg in 10 (Group 2). The two groups did not differ significantly with regard to either biochemical values or hemodynamic indices before dialysis, and both sustained comparable reduction in body weight, total blood volume, and cardiac output following dialysis. Heart rate remained unchanged in both. The only significant difference between the two was the response of total peripheral resistance (TPR) to fluid depletion. TPR rose adequately in Group 1 but was unchanged in Group 2 (7.5 +/- 2.2 (SE) vs 0.7 +/- 1.1 units, p less than 0.025) despite equal fall in cardiac output in both (881 +/- 212 vs 890 +/- 173 ml/m, p less than 0.10). Thus, differences in arterial pressure response to fluid loss by hemodialysis could be due to impaired autonomic control of resistance vessels; this abnormality might not be revealed by tests of baroreceptor activity that depend only on heart rate responses to blood pressure variations.

Adult↗