C-reactive protein concentrations in serum of dogs with naturally occurring renal disease

The current study was undertaken to investigate the relation between serum C-reactive protein (CRP) concentrations and parameters of renal function in dogs with naturally occurring renal disease. Dogs were assigned to groups according to plasma creatinine concentration, urinary protein-to-creatinine ratio (UP/UC), and exogenous plasma creatinine clearance (P-Cl(Cr)) rates. Group A (healthy control dogs; n = 8): non-azotemic (plasma creatinine <125 µmol/l) and nonproteinuric (UP/UC 90 ml/min/m(2); group B (n = 11): non-azotemic, nonproteinuric dogs with reduced P-Cl(Cr) rates (50-89 ml/min/m(2)); group C (n = 7): azotemic, borderline proteinuric dogs (P-Cl(Cr) rates: 22-67 ml/min/m(2)); and group D (n = 6): uremic, proteinuric dogs (not tested for P-Cl(Cr)). The serum CRP concentrations were measured via commercial enzyme-linked immunosorbent assay. The CRP concentrations in the clinically healthy dogs (group A) ranged from 2.09 mg/l to 8.60 mg/l (median: 3.21 mg/l). In comparison with dogs of group A, median CRP concentrations were significantly (P < 0.01) elevated in dogs of group B (17.6 mg/l, range: 17.0-19.2 mg/l), group C (24.8 mg/l, range: 18.0-32.5 mg/l), and group D (59.7 mg/l, range: 17.7-123 mg/l). Serum CRP was significantly related to P-Cl(Cr) (r = -0.83; P < 0.001), plasma creatinine (r = 0.81; P < 0.001), UP/UC (r = 0.70; P < 0.001), and leukocytes (r = 0.49; P < 0.01). The significant relations between serum CRP concentrations and biochemical parameters of kidney function in plasma and urine suggest that a stimulation of the acute phase response is implicated in the pathogenesis of canine renal disease

Characterization of the microheterogeneity of transthyretin in plasma and urine using SELDI-TOF-MS immunoassay

BACKGROUND: It has been shown that transthyretin (TTR) exists in different molecular variants. Besides point mutations associated with different diseases such as amyloidosis, other posttranslational modifications occur that might be of diagnostic interest. RESULTS: TTR levels as determined by ELISA in plasma and urine of healthy individuals were 489 ± 155 μg/ml plasma and 46 ± 24 ng/g creatinine, respectively. Average levels in urine of pregnant women were 45 ± 65 μg/g creatinine. The molecular heterogeneity of TTR was analyzed using a high-throughput mass spectrometric immunoassay system. TTR was extracted from plasma or urine onto an antibody-coated (via protein A) affinity chip surface (PS20) using the surface-enhanced laser desorption/ionization (SELDI) technique. Subsequently samples were subjected to time-of-flight mass spectrometry (TOF-MS). In healthy individuals, TTR in plasma occurred rather consistently in two variants of 13732 ± 12 and 13851 ± 9 Da for the native and S-cysteinylated forms and at a smaller signal of 14043 ± 17 Da for the S-glutathionylated form. In urine of pregnant women, various signals were observed with a dominant signal at 13736 ± 10 Da and a varying number of smaller immunoreactive fragments. These fragments are possibly the consequence of metabolism in plasma or kidney. CONCLUSION: This chip-based approach represents a rapid and accurate method to characterize the molecular variants of TTR including protein or peptide fragments which are either related to TTR or have resulted from its catabolism. These molecular variants may be of diagnostic importance as alternative or novel biomarkers due to their predominant relation to the TTR metabolism both in healthy and diseased individuals

Microalbuminuria is a major determinant of elevated plasma retinol-binding protein 4 in type 2 diabetic patients

Plasma retinol-binding protein 4 (RBP4) may be a new adipokine linked to obesity-induced insulin resistance and type 2 diabetes. The impact of diabetic nephropathy on plasma RBP4 levels, however, is not known. We tested the hypothesis that microalbuminuria is associated with elevated plasma concentrations of RBP4 in type 2 diabetic subjects. Retinol, its binding protein and transthyretin (TTR) were measured in the plasma and urine of 62 type 2 diabetic subjects, 26 of whom had microalbuminuria. The results were compared to 35 healthy control subjects. Despite no differences in plasma retinol, concentrations of the RBP4 were significantly elevated in plasma of diabetic patients and significantly higher in those with microalbuminuria. The higher plasma levels of the binding protein in subjects with microalbuminuria were accompanied by both significantly elevated plasma TTR and increased urinary levels of RBP4. There were no correlations of plasma-binding protein levels and parameters of insulin resistance. Our study suggests that plasma RBP4 levels in type 2 diabetic patients are affected by incipient nephropathy. Therefore, further studies evaluating RBP4 as a regulator of systemic insulin resistance and type 2 diabetes will need to take renal function into consideration

A systemic review of existing serological possibilities to diagnose canine osteoarthritis with a particular focus on extracellular matrix proteoglycans and protein

Extra-cellular matrix (ECM) components are important and their stabilization is significant in maintaining normal healthy joint environment. In osteoarthritis (OA), ECM components are altered and indicate disease progression. The joint ECM is composed of proteoglycans (aggrecan, perlecan, inter a-trypsin inhibitor), glycoproteins (fibronectin, lubricin, COMP) and collagen types (most abundantly collagen type II) which represent structural and functional transformation during disease advancement. ECM investigation revealed significant biomarkers of OA that could be used as a diagnostic and therapeutic tool in different canine orthopedic diseases. This review deliberates our current findings of how the components of ECM change at the molecular level during disease progression in canine OA

Safety evaluation of vitamin A in growing dogs

The safe upper limit for inclusion of vitamin A in complete diets for growing dogs is uncertain, with the result that current recommendations range from 5.24 to 104.80 μmol retinol (5000 to 100 000 IU vitamin A)/4184 kJ (1000 kcal) metabolisable energy (ME). The aim of the present study was to determine the effect of feeding four concentrations of vitamin A to puppies from weaning until 1 year of age. A total of forty-nine puppies, of two breeds, Labrador Retriever and Miniature Schnauzer, were randomly assigned to one of four treatment groups. Following weaning at 8 weeks of age, puppies were fed a complete food supplemented with retinyl acetate diluted in vegetable oil and fed at 1 ml oil/100 g diet to achieve an intake of 5·24, 13·10, 78·60 and 104·80 μmol retinol (5000, 12 500, 75 000 and 100 000 IU vitamin A)/4184 kJ (1000 kcal) ME. Fasted blood and urine samples were collected at 8, 10, 12, 14, 16, 20, 26, 36 and 52 weeks of age and analysed for markers of vitamin A metabolism and markers of safety including haematological and biochemical variables, bone-specific alkaline phosphatase, cross-linked carboxyterminal telopeptides of type I collagen and dual-energy X-ray absorptiometry. Clinical examinations were conducted every 4 weeks. Data were analysed by means of a mixed model analysis with Bonferroni corrections for multiple endpoints. There was no effect of vitamin A concentration on any of the parameters, with the exception of total serum retinyl esters, and no effect of dose on the number, type and duration of adverse events. We therefore propose that 104·80 μmol retinol (100 000 IU vitamin A)/4184 kJ (1000 kcal) is a suitable safe upper limit for use in the formulation of diets designed for puppy growth

Impact of Increasing Dietary Calcium Levels on Calcium Excretion and Vitamin D Metabolites in the Blood of Healthy Adult Cats

Background Dietary calcium (Ca) concentrations might affect regulatory pathways within the Ca and vitamin D metabolism and consequently excretory mechanisms. Considering large variations in Ca concentrations of feline diets, the physiological impact on Ca homeostasis has not been evaluated to date. In the present study, diets with increasing concentrations of dicalcium phosphate were offered to ten healthy adult cats (Ca/phosphorus (P): 6.23/6.02, 7.77/7.56, 15.0/12.7, 19.0/17.3, 22.2/19.9, 24.3/21.6 g/kg dry matter). Each feeding period was divided into a 10-day adaptation and an 8-day sampling period in order to collect urine and faeces. On the last day of each feeding period, blood samples were taken. Results Urinary Ca concentrations remained unaffected, but faecal Ca concentrations increased (P < 0.001) with increasing dietary Ca levels. No effect on whole and intact parathyroid hormone levels, fibroblast growth factor 23 and calcitriol concentrations in the blood of the cats were observed. However, the calcitriol precursors 25(OH)D2 and 25(OH)D3, which are considered the most useful indicators for the vitamin D status, decreased with higher dietary Ca levels (P = 0.013 and P = 0.033). Increasing dietary levels of dicalcium phosphate revealed an acidifying effect on urinary fasting pH (6.02) and postprandial pH (6.01) (P < 0.001), possibly mediated by an increase of urinary phosphorus (P) concentrations (P < 0.001). Conclusions In conclusion, calcitriol precursors were linearly affected by increasing dietary Ca concentrations. The increase in faecal Ca excretion indicates that Ca homeostasis of cats is mainly regulated in the intestine and not by the kidneys. Long-term studies should investigate the physiological relevance of the acidifying effect observed when feeding diets high in Ca and P

Impact of vitamin A on clinical outcomes in haemodialysis patients

Background. Patients on maintenance haemodialysis treatment experience an excessive risk of cardiovascular disease and mortality. The vitamin A concentration is known to be higher in these patients compared to the general population where elevated vitamin A concentrations are associated with adverse outcome. The impact of vitamin A on morbidity and mortality in end-stage renal disease patients is controversial and is the topic of this study. Methods. We analysed plasma retinol and retinol-binding protein 4 (RBP4) in 1177 diabetic haemodialysis patients, who participated in the German Diabetes and Dialysis Study (median follow-up 4 years). By Cox regression analyses hazard ratios (HRs) were determined for pre-specified, adjudicated end points according to baseline concentrations. Results. Patients had a mean age of 66 ± 8 years, mean retinol and RBP4 concentrations of 3.28 (0.71-7.44) and 4.02 (1.28-10.1) μmol/L, respectively. Patients with retinol concentrations in the first quartile (3.9 μmol/L; HR 1.81, 95% confidence interval (CI) 1.43-2.30]. There was a strong association between low retinol and the risk of sudden cardiac death (SCD, HR 2.22, 95% CI 1.41-3.50) and fatal infection (HR 2.19, 95% CI 1.26-3.82). Patients with RBP4 concentrations in the lowest quartile (<3.0 μmol/L) were more likely to die of any cause (HR 1.43, 95% CI 1.14-1.80), experience SCD (HR 1.97, 95% CI 1.28-3.03) and cardiovascular events (HR 1.43, 95% CI 1.10-1.85). Conclusion. This large cohort study shows a strong association of low retinol and RBP4 concentrations with SCD and all-cause mortality in diabetic haemodialysis patient

Alteration of Transthyretin Microheterogeneity in Serum of Multiple Trauma Patients

Transthyretin (TTR) which exists in various isoforms, is a valid marker for acute phase response and subclinical malnutrition. The aim of the study was to investigate the relationship between inflammation, oxidative stress and the occurrence of changes in microheterogeneity of TTR

Isoforms of Retinol binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver

<p>Abstract</p> <p>Background</p> <p>The levels of retinol-binding protein 4 (RBP4) – the carrier protein for Vitamin A in plasma – are tightly regulated under healthy circumstances. The kidney, the main site of RBP4 catabolism, contributes to an elevation of RBP4 levels during chronic kidney disease (CKD) whereas during chronic liver disease (CLD) RBP4 levels decrease. Little is known about RBP4 isoforms including apo-RBP4, holo-RBP4 as well as RBP4 truncated at the C-terminus (RBP4-L and RBP4-LL) except that RBP4 isoforms have been reported to be increased in hemodialysis patients. Since it is not known whether CLD influence RBP4 isoforms, we investigated RBP4 levels, apo- and holo-RBP4 as well as RBP4-L and RBP4-LL in plasma of 36 patients suffering from CKD, in 55 CLD patients and in 50 control subjects. RBP4 was determined by ELISA and apo- and holo-RBP4 by native polyacrylamide gel electrophoresis (PAGE). RBP4-L and RBP4-LL were analyzed after immunoprecipitation by mass spectrometry (MALDI-TOF-MS).</p> <p>Results</p> <p>RBP4 isoforms and levels were highly increased in CKD patients compared to controls (P < 0.05) whereas in CLD patients RBP4 isoforms were not different from controls. In addition, in hepatic dysfunction RBP4 levels were decreased whereas the amount of isoforms was not affected.</p> <p>Conclusion</p> <p>The occurrence of RBP4 isoforms is not influenced by liver function but seems to be strongly related to kidney function and may therefore be important in investigating kidney function and related disorders.</p