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Verteilung von Vitamin A und Retinol-Bindungs-Protein (RBP) in verschiedenen Geweben von Caniden
(1997)
Vitamin A excreted in the urine of canines is associated with a Tamm-Horsfall-like Glycoprotein
(1998)
Background: Patients with severe forms of cancer are reported to have reduced concentrations of micronutrients in plasma due to the chronic reduction of food intake and an increased metabolism of these components. The purpose of this study was to evaluate if an accumulation of carotenoids, alpha-tocopherol and retinol in malignant ascitic fluid in women with ovarian cancer might contribute to a loss of these components from plasma. Methods: Blood and ascitic fluid samples obtained from 21 women with ovarian carcinomas and 17 healthy controls were analyzed for retinol, retinol- binding protein (RBP), alpha-tocopherol and carotenoids. Results: Plasma concentrations of all micronutrients were lower in cancer patients compared to controls. Ascitic fluid concentration of all investigated components was comparable (73- 110%) to plasma. While the mean concentration of retinol in malignant ascites represented 73% of that in plasma, the concentration of RBP was less than 10% resulting in an increased mean molar ratio of retinol to RBP from 1.18 to 10.5. Conclusions: The results suggest that lower plasma concentrations of micronutrients in women suffering from ovarian carcinoma are not only caused by a cachexia-induced decrease of food intake and a higher rate of metabolic utilization, but also by a substantial yet not considered transfer from plasma into ascitic fluid possibly associated with plasma lipoproteins. This raises questions with regard to the protective function of these plasma components in ascitic fluid, the consequences of paracentesis on an additional supplementation and finally the possibility to use one or a combination of these components as an additional marker to discriminate between benign and malignant ascites. Copyright (C) 2004 S. Karger AG, Basel
Measurement of total urinary proteins in individuals that tested positive by urinary dipstick is a typical method for assessing the presence of potentially serious renal disorders. In the absence of such overt proteinuria, however, measurement of specific urinary proteins may be useful in the diagnosis of nephropathies and may provide greater insight into the pathogenesis. The urine of 28 dogs (16 with renal disease and 12 healthy) was evaluated to determine whether specific low-molecular-weight proteins or the pattern of protein excretion could also be used as a marker of tubular dysfunction in dogs. Specific proteins were assessed by immunological methods, whereas protein profiles were determined by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (MS). In particular, changes in the excretion of retinol-binding protein (RBP) and Tamm-Horsfall protein (THP) appear to be of clinical relevance in the diagnosis of canine kidney diseases. The pattern of urinary protein and peptides revealed specific changes in abundance in dogs with renal disease at molecular masses (kD) of 11.58, 12.41, 12.60, 14.58, 20.95 (RBP), 27.85, and 65.69 (albumin). In conclusion, comparable proteins as in humans might be used as urinary markers for proximal (RBP) and distal (THP) tubular dysfunction in dogs. Surface-enhanced laser desorption/ionization time-of-flight MS is a promising tool for the study of kidney physiology and pathophysiology and might aid in the discovery of new biomarkers of renal disease
Fasting dogs do transport vitamin A (VA) in plasma not only as retinol but predominantly as retinyl esters. Contrary to retinol, nothing is known concerning the effects of athletic performance on plasma retinyl ester concentrations. The aim of this study was therefore to examine whether physical stress because of exercise and modification of the oxidative stress by supplementation of alpha-tocopherol influences the concentrations of retinol and retinyl esters in plasma of sled dogs. The study was carried out on 41 trained adult sled dogs, which were randomly assigned into two groups. One group (19 dogs) was daily substituted with 50 mg DL-alpha-tocopheryl acetate per kilogram body weight and the control group (22 dogs) was maintained on a basal diet during 3 months prior to exercise. The plasma concentrations of retinol, retinyl esters, alpha-tocopherol and triglycerides were measured immediately before, directly after and 24 h after exercise. The supplementation of alpha-tocopheryl acetate had no effect on plasma retinol and retinyl ester concentrations at any measurement time point. However, retinyl ester levels doubled in the non- supplemented group immediately after the race (p < 0.001), whereas in the supplemented group similar high levels were observed not until 24 h post-racing (p < 0.001). The high levels of retinyl esters were paralleled to some extent by an increase in plasma triglyceride concentrations, which were significantly higher 24 h post-racing than immediately before (p < 0.001) and after exercise (p < 0.001) in both groups. The increase in retinyl ester concentrations might be indicative of their mobilization from liver and adipose tissue. Whether plasma retinyl esters can be used as an indicator for the extent of nutrient mobilization during and post-exercise in sled dogs remains to be elucidated
Background/Aims: The renal function, including the excretion of low-molecular-weight proteins, changes during pregnancy and may cause a urinary excretion of retinol-binding protein (RBP). Whether it is accompanied by a substantial loss of vitamin A ( retinol) has not been established yet. We therefore determined the excretion of retinol and RBP in urine of pregnant women. Methods: The study involved analyses of urine samples from 40 healthy pregnant women and 29 women with pregnancy complications during the third trimester. Analyses of plasma and urine of 7 healthy women and 5 women with pregnancy complications were also carried out 6 weeks antepartum, at time of delivery and 1 week postpartum. Results: Urinary retinol was higher in women who suffered from pregnancy disorders with an influence on maternal metabolism ( p < 0.01). RBP was excreted at substantial concentrations in the urine of all 69 women, but there were no differences between the groups. Women with a concomitant excretion of retinol had higher levels of urinary RBP than those without a retinol excretion ( p < 0.05). Differences in plasma retinol and RBP were not significant. Conclusion: The excretion of urinary retinol may increase significantly during pregnancy complications, which needs further clarification to which extent this condition may negatively affect the vitamin A status in such women. Copyright (C) 2004 S. Karger AG, Basel