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Biomedical subjects

L Yuan

Publications and source records attributed to L Yuan.

At least 235 records · Page 13Linked to original sources
PubMed1980

Kinetics of peritoneal fluid absorption in patients with chronic renal failure.

Previous measurements of fluid absorption from the peritoneal cavity were made after a single injection of a protein-bound marker by following changes in the concentration of the marker with time. Absorption of the marker substance itself had to be estimated. The present study measured absorption of peritoneal fluid by more direct methods. 1.5 to 2.1 L of 0.9% saline, along with 10 muCi of RISA were infused into the abdomens of nine chronic renal failure patients through peritoneal dialysis catheters. Initial paritoneal fluid volumes were determined by dilution. After 7 hr, a second dose of RISA (5 muCi) was infused, and volumes in the peritoneal cavity were again determinted by dilution of the increment dose. At 8 hr, an attempt was made to recover the RISA remaining in the peritoneal cavity by draining and repeatedly flushing that space. The amount of RISA recovered was used to calculate independently the amounts of RISA and fluid which had been absorbed during the 8 hr period. There was good agreement between peritoneal fluid volumes calculated at 7 and 8 hr by these and other techniques. By 7 hr, 23.8% +/- 10.9 S.D. of the initial peritoneal fluid volume ahd been absorbed. The amount of RISA absorbed during the same period was 17.3% +/- 4.9 of the initially administered dose. At 7 hr, only 23.7% +/- 6.3 of the absorbed RISA was in the plasma. The proposed techniques of volume measurement are valid and point to great variation among patients in the rate of fluid absorption from the peritoneal cavity.

Absorption↗
PubMed1973

Evidence for an amino-terminal extension in high-molecular-weight collagens from mature bovine skin.

Insoluble, mature collagen fibers from bovine skin have been partially solubilized by mild, denaturing, but nonhydrolytic means. The soluble denatured collagen was fractionated by alcohol coacervation, and a fraction rich in high-molecular-weight alpha-chains was obtained. The heavy alpha-chains were isolated by carboxymethylcellulose chromatography. Renaturation, followed by measurements of optical rotation at 365 nm, showed that stable, in-register renaturation was more readily accomplished in mixtures of heavy alpha-chains than in alpha1-beta(11)-chain mixtures. Renatured heavy alpha-chain preparations were precipitated in SLS form, negatively stained, and examined by electron microscopy. The SLS precipitates were compared with SLS segments from native soluble collagen and were found to match in band pattern and spacing along their entire length from the COOH-terminal region, except for an NH(2)-terminal extension of 170 +/- 30 A in the heavy alpha-chain SLS. The heavy alpha-chains correspond chromatographically with those previously reported to be intermediates in the conversion of procollagen to collagen, on the basis of their molecular weight and of labeling studies. The presence of NH(2)-terminal extensions, and their existence in mature insoluble collagen, suggest that these intermediates may have a special role in fibril formation.

Adenosine Triphosphate↗