Single-injection method for evaluation of renal function with 3H-inulin and 14C-tetraethylammonium bromide in conscious unrestrained Sprague-Dawley rats

A single-injection, double-isotope method for simultaneously determining glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in conscious, unrestrained rats was evaluated. 3H-inulin and 14C-tetraethylammonium bromide were used to determine GFR and ERPF, respectively. Using a modified, single exponential, 1-compartment, mathematical model, solute clearance was estimated, using a plasma radioactivity disappearance curve constructed from samples collected during a 60-minute period. In 12 healthy, conscious, adult male Sprague-Dawley rats, the mean (+/- SEM) GFR, ERPF, and filtration fraction were 5.65 +/- 0.40 ml/min/kg, 13.92 +/- 0.82 ml/min/kg, and 0.41 +/- 0.03, respectively. In 7 adult male Sprague-Dawley rats that had undergone a three-quarter nephrectomy 6 weeks prior to study, the mean GFR, ERPF, and filtration fraction were 2.69 +/- 0.36 ml/min/kg, 7.02 +/- 0.90 ml/min/kg, and 0.39 +/- 0.03, respectively. In 37 adult male rats in various stages of renal disease, the mean GFR and ERPF correlated significantly (r = 0.85, P less than 0.001 and r = 0.83, P less than 0.001, respectively) with the reciprocal of plasma creatinine. The single-injection, double-isotope technique yielded functional values similar to those reported for healthy rats in which other clearance methods were used. Using this technique, we were able to detect alterations associated with various degrees of renal functional loss. The technique enabled us to evaluate conscious, unrestrained rats, eliminated the need to collect urine, and required short blood collection times (60 min) and small volumes (0.1 ml) of plasma.     

Vitamin D-dependent rickets type 2 with characteristic radiographic changes in a 4-month-old kitten

This report describes the presenting signs, biochemical abnormalities, and radiographic changes in a 4-month-old kitten with vitamin D-dependent rickets type 2. Details of therapy are described and possible reasons for treatment failure are discussed.     

Effects of Processing Conditions on Nanoclay Dispersion in Starch‐Clay Nanocomposites

Wheat starch samples containing Cloisite Na+ and 30B nanoclays were extruded from a twin‐screw extruder. Moisture content, temperature, and screw speed were varied to determine their effect on nanoclay dispersion. X‐ray diffraction and transmission electron microscopy (TEM) were used to examine nanoclay intercalation and exfoliation. Moisture content had the largest effect on Cloisite Na+ dispersion, with the highest moisture sample containing exfoliated nanoclays. Meanwhile, temperature and screw speed had little effect on Cloisite Na+ dispersion. For Cloisite 30B samples, only an increase in temperature produced slight intercalation of nanoclays. This was due to the incompatibility of starch with the more hydrophobic Cloisite 30B. Also, Cloisite Na+ and 30B intercalation did not depend on specific mechanical energy. In addition, water absorbance tests indicated the Cloisite Na+ sample containing the most well‐dispersed nanoclays had the lowest water uptake.     

Factors affecting longevity in maternal Duroc swine lines

A competing risks approach was used to evaluate the influence of several pre-farrowing factors on risk of culling due to different causes in Duroc swine, these having low fertility, low productivity, lameness and mortality. Culling due to low fertility increased for average daily gains during the growth test lower than 585 g/day, whereas culling due to low productivity and mortality increased with low levels of backfat thickness at the end of the growth test. Lesser loin depths at first farrowing reduced culling due to low productivity but increased culling due to lameness. Furthermore, a higher average daily gain from the end of the growth test to first mating increased culling by all causes. A complementary analysis was carried out to evaluate the influence of these factors on risk of culling without taking into account the specific reason of failure. In this second analysis, the factors were included as time-dependent covariates whose relative importance changed throughout the sows' productive life. Expected survival functions and replacement rates have been calculated in different hypothetical situations in order to determine the optimal animal body type at first farrowing to maximise longevity, which under our production conditions is independent of average daily gain from birth until the end of the growth test, but from the end of the growth test to first mating average daily gain should not be over 485 g/day; backfat thickness should be more than 16 mm at the end of the growth test and maintain this level until the first parturition without exceeding 19 mm; loin depth should be kept below 45 mm at first farrowing.