Every 3 mo for a 2-yr period, two weaned Holstein steer calves (94.5 kg) were randomly assigned to each of four slaughter age groups (3, 6, 9, and 12 mo). Urea dilution was performed before slaughter, and urea space (US) was calculated as total volume and as a percentage of body weight (BW) and empty body weight (EBW). The relationships between US (kg, % EBW and % BW), BW, and EBW and carcass soft tissue composition (protein, fat, moisture, and ash) were studied. One- and two-pool models were fitted using the urea dilution data and the coefficients of those equations (zero time, A + B), and the intercepts of compartments A and B were used to estimate body volume. Body weight and EBW effectively predicted the amount of water, fat, and protein in the carcass soft tissue. Equations expressed in kilograms were more accurate than those expressed as percentages. Urea space overestimated body water, probably because of the fast rate of urea disappearance in plasma. Correlation coefficients between US and carcass soft tissue water (kg) based on the pooled data ranged from .74 at 6 min to .48 at 42 min after infusion. The biexponential models coefficients explained more of the variation of carcass soft tissue composition than US; correlation coefficients using volume B and the soft tissue composition (in kg) with pooled data were .78 (water), .68 (fat), .69 (ash), and .76 (protein). The relationships between A and soft tissue composition were weaker (water .59, fat .51, ash .58 and protein .59). The highest correlation coefficients were obtained when A + B was used for water, fat, ash, and protein (.83, .70, .74 and .81, respectively). Equations combining BW, EBW, and two-model coefficients (A, B, A + B) explained much of the variation of soft tissue composition. No significant benefit was found in using the urea space at various times after infusion over BW or EBW alone to estimate carcass soft tissue composition in Holstein steers.

No abstract

The hypothesis that the hepatic receptor for asialoglycoproteins would mediate turnover of glycoproteins in blood (after their desialylation by neuraminidase located on cell surfaces) was tested in rats by measuring clearance of intact 125I-labeled glycoproteins in the presence or absence of enough unlabeled asialoglycoproteins to saturate the asialoglycoprotein receptor. Via an indwelling venous catheter, a mixture of 125I-orosomucoid (obtained from rat serum) and a bolus of unlabeled asialofetuin (bovine) was injected, and infusion of an asialofetuin solution sustained. Total radioactivity and trichloroacetic acid-precipitable radioactivity were measured in blood samples taken at frequent intervals from an arterial catheter. Clearance was computer analyzed by using a two-component model. Nondestructiveness of radiolabeling and desialylation methods and interchangeability of rat and bovine (asialo)glycoproteins were demonstrated in control experiments. The infusion trials showed that independent clearance processes exist for intact and asialoglycoproteins. Apparently, the asialoglycoprotein receptor has no function in the turnover of intact plasma glycoproteins.

The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.