Renal pathology and urinary protein excretion in a 14-month-old Bernese mountain dog with chronic renal failure

The renal pathology and urinary protein pattern of a 14-month-old female Bernese mountain dog with chronic renal failure was investigated. Sodium dodecyl sulphate-polyacrylamid gel electrophoresis and subsequent Western blot analysis of urine showed the presence of heavy and light chains of immunoglobulin, transferrin, albumin, vitamin D-binding protein, transthyretin and retinol-binding protein (RBP), but no excretion of Tamm-Horsfall protein (THP). Histopathological examinations of the kidneys revealed severe membranous glomerulonephritis accompanied by tubular dilatation, tubular atrophy and interstitial fibrosis. The renal expression of megalin, the main endocytic receptor for the re-uptake of proteins in proximal tubules, RBP and THP was reduced or completely absent, indicating severe tubular dysfunction. The identified urinary proteins may be of interest as additional markers for the diagnosis of juvenile nephropathy in Bernese mountain dogs.     

Levels of retinol and retinyl esters in plasma and urine of dogs with urolithiasis

Vitamin A (VA) deficiency and Tamm-Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol-binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone-forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.     

Content of retinol and retinyl esters in blood plasma,liver, kidney and reproductive organs of Japanese quails

Due to its importance in many physiological processes such as cell proliferation and differentiation, vitamin A plays a key role in reproduction. The present study examines the content and distribution of retinol and retinyl esters in the blood plasma, liver, kidney, ovary and oviduct (infundibulum, magnum, isthmus and uterus) of the laying Japanese quail. (1) The results show that the stage of egg laying had no influence on the level of vitamin A (retinol or retinyl esters) in plasma, kidney and liver. (2) The results further indicate that in the oviduct there are quantitative and qualitative differences in the concentration of retinol and retinyl esters, but that these differences are not altered by the stage of egg formation. (3) The highest levels of vitamin A in the isthmus and uterus were associated with a predominance of retinyl esters (palmitate and stearate); sections with lower total levels of vitamin A (infundibulum, magnum) had retinol as the more dominant form of vitamin A. (4) Changes in the ratio of retinol to retinyl esters in the various sections of the avian oviduct might point to metabolic differences. The storage of vitamin A might therefore be the predominant function of the uterus and isthmus; in the infundibulum and magnum, where vitamin A is predominantly present as retinol, vitamin A serves rather as a precursor for the modulation of the cellular metabolism of these structures.     

The distribution of vitamin A and retinol-binding protein in the blood plasma, urine, liver and kidneys of carnivores

The contents of retinol and retinyl esters as well as retinol-binding protein (RBP) in the plasma, urine, liver and kidneys of dogs, raccoon dogs and silver foxes were investigated. In the plasma and urine of all three species, vitamin A was present as retinol and retinyl esters. Vitamin A levels (1376+/-669 microg x g(-1)) were significantly higher in the livers of dogs than in the kidneys (200+/-217 microg x g(-1), P < 0.001 ). However, vitamin A levels in the kidneys of raccoon dogs (291+/-146 microg x g(-1)) and silver foxes (474+/-200 microg x g(-1)) were significantly higher than in the liver (67+/-58 microg x g(-1) and 4.3+/-2.4 microg x g(-1), respectively, both P < 0.001). RBP was immunologically detected in the blood plasma of all species, but never in the urine. In the liver, immunoreactive RBP was found in hepatocytes. In the kidneys of all species, RBP was observed in the cells of the proximal convoluted tubules. The levels of vitamin A in the livers of raccoon dogs and silver foxes were extremely low, which would be interpreted as a sign of great deficiency in humans. This observation might indicate that the liver status cannot be used as an indicator of vitamin A deficiency in canines. The high levels of vitamin A in the kidneys in all three species may indicate a specific function of the kidney in the vitamin A metabolism of canines.     

THE FREE TRYPTOPHANE CONTENT OF HUMAN URINE

The amount of 1-tryptophane excreted per day by 9 different normal male subjects was determined by a microbiological method with L. arabinosus as the test organism. From 12-30 mg per day were excreted as contrasted to an average value of 281 mg per day reported by Albanese and Frankston. A negligible amount of indole in the urine could be demonstrated. Satisfactory values and recoveries of 1-tryptophane were obtained at different levels of the test sample.     

Characterisation of transthyretin and retinol-binding protein in plasma and cerebrospinal fluid of dogs

The aim of this study was to investigate differences in concentrations of vitamin A, transthyretin (TTR) and retinol-binding protein (RBP) between plasma and cerebrospinal fluid (CSF) in dogs. RBP was detected using ELISA, and both RBP and TTR by Western blot analysis after separation on SDS-PAGE. Vitamin A was determined by high performance liquid chromatography. RBP and TTR as well as vitamin A were detected in all samples but at substantially lower concentrations in CSF compared to plasma. RBP in dog plasma showed a similar molecular mass to that of humans, whereas canine TTR had a lower molecular mass. Comparison between plasma and CSF showed that both RBP and TTR were of lower molecular mass in CSF. In CSF, RBP and retinol were present at 10-100-fold lower concentrations compared to plasma. Retinyl esters were present only in minute amounts in 5/17 samples. In conclusion, the CSF of dogs compared to humans is significantly different in terms of both quality and quantity of transport proteins for vitamin A.     

Effect of parturition on levels of vitamins A and E and of beta-carotene in plasma and milk of mares.

The objective of this study was to investigate in mares the effect of parturition on plasma and milk levels of retinol, beta-carotene, alpha-tocopherol and cholesterol over 12 weeks around parturition. In blood plasma of horses around parturition an increase of all these components was observed. This increase was most impressive in beta-carotene (P<0.05) and less pronounced for vitamin E, vitamin A and cholesterol. The magnitude of increase around parturition corresponded well with the magnitude of accumulation in colostrum; levels of beta-carotene in colostrum were 65 times higher compared to mature milk while vitamin A, vitamin E and cholesterol were only 3 to 8 times higher. Beta-carotene concentrations in colostrum were positively correlated with corresponding plasma levels (r = 0.9; P<0.001). Reasons for the increase in plasma beta-carotene around parturition may include an improved absorption of carotene and/or reduced conversion into vitamin A as well as mobilisation from tissue storages or a reduced uptake in tissues other than the mammary gland. In conclusion, the results may point to possible component- and species-specific differences involved in the transfer of fat-soluble vitamins, beta-carotene and cholesterol from blood plasma into colostrum.     

No easy solution for the fractionation of faecal nitrogen in captive wild herbivores: results of a pilot study

Faecal nitrogen (FN) concentration is used as a marker for habitat quality and digestive efficiency in free‐ranging herbivores. In herbivores, FN can be separated into undigested plant N (analysed as the N concentration of the neutral detergent residue) and metabolic faecal N (MFN). It has been suggested that by differential analysis of the faecal fibre‐bound N, the MFN fraction can be further split into a bacterial N and an endogenous N fraction [Hesta et al., Br. J. Nutr. 90 (2003) 1007]. We applied these methods to 96 faecal samples of 48 mammalian herbivore species from zoos. Species were grouped into coprophageous and non‐coprophageous hindgut fermenters and ruminating and non‐ruminating foregut fermenters. Diet was not controlled. The FN decreased with body mass, possibly reflecting higher proportions of concentrates in diets of smaller animals. The proportion of MFN increased with FN, indicating that higher quality food might enhance the gastrointestinal bacterial flora. The only outlier to this pattern was the lesser panda (Ailurus fulgens), confirming the low relevance of fermentative digestion in this herbivorous ‘carnivore’. No relevant differences between the four digestion types were noted. The proportion of endogenous faecal N (32–80% of FN) was always higher than that of bacterial faecal N (7–30%), which contradicts basal understanding of herbivore digestive physiology. Thus, the method of Hesta et al. (2003) does not appear applicable to herbivores. While the results do not exclude the possibility that detailed differences might occur between digestion types, they indicate a high degree of similarity between herbivores that rely on bacterial fermentation, regardless of their digestion type, with respect to metabolic faecal losses.