Endothelial CaSR is involved in the induction of atherosclerosis by promoting cell adhesion and local inflammation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Humboldt foundation

Background

Calcium-Sensing Receptor (CaSR) is a cell surface G-protein coupled receptor that senses calcium in the extracellular environment. This receptor is widely studied in mineral homeostasis due to its presence in varied calcitropic tissues. However, CaSR is also present on the surface of vascular and hematopoietic cells and recent studies suggest that this receptor can also have pathological consequences related to cardiovascular diseases, like atherosclerosis. Since endothelial cells are crucial players in atherogenesis, we aimed to investigate which role endothelial CaSR plays in the development and progression of atherosclerosis.

Methods

We cross-bred CaSRflox/flox Apoe-/- mice with BmxCreERT2 Apoe-/- (endothelial cell specific Cre driver) mice to obtain tamoxifen-inducible mice which have an endothelial cell specific deletion of CaSR. The mice were then fed with a high fat diet (HFD) for 4 or 12 weeks, reflecting early and late atherosclerosis, respectively. We used histological and immuno-fluorescent stainings to analyse the atherosclerotic lesion size and its cellular and acellular composition. Systemic effects on leukocytes were evaluated using flow-cytometry, while intra-vital microscopy was used to study leukocyte adhesion to activated endothelium in-vivo. Further mechanistic studies were performed in human coronary artery endothelial cells (HCAECs) in-vitro.

Results

Endothelial CaSR deficiency in mice resulted in significantly smaller lesion size in early atherosclerotic stages (4 weeks HFD), whereas late atherosclerotic lesions (12 weeks HFD) were not affected by the lack of endothelial CaSR. Moreover, the phenotype of atherosclerotic plaques, characterized by macrophage, smooth muscle cell, collagen and necrotic core content remained unaltered between wild-type and endothelial cell specific CaSR knockout mice. Interestingly, leukocyte adhesion in-vivo, especially neutrophil adhesion, was significantly reduced in endothelial cell CaSR deficient mice. In line with this, overexpression of CaSR in HCAECs in-vitro increased the production of inflammatory cytokines and expression of adhesion molecules ICAM and VCAM.

Conclusion

Our results indicate that while endothelial cell specific CaSR is involved in the induction of atherosclerosis, it does not play a major role in its progression. CaSR has a major influence on endothelium-leukocyte interaction and endothelial inflammation. The increased expression of ICAM/VCAM suggest that CaSR mainly mediates such adhesive effects by modulating integrin expression. Thereby this study highlights that CaSR plays a crucial role in atherosclerosis development, rendering it a novel, so far unexplored therapeutic target.

Reduction of protein-bound uraemic toxins in plasma of chronic renal failure patients: A systematic review

BACKGROUND

Protein-bound uraemic toxins (PBUTs) accumulate in patients with chronic kidney disease and impose detrimental effects on the vascular system. However, a unanimous consensus on the most optimum approach for the reduction of plasma PBUTs is still lacking.

METHODS

In this systematic review, we aimed to identify the most efficient clinically available plasma PBUT reduction method reported in the literature between 1980 and 2020. The literature was screened for clinical studies describing approaches to reduce the plasma concentration of known uraemic toxins. There were no limits on the number of patients studied or on the duration or design of the studies.

RESULTS

Out of 1274 identified publications, 101 studies describing therapeutic options aiming at the reduction of PBUTs in CKD patients were included in this review. We stratified the studies by the PBUTs and the duration of the analysis into acute (data from a single procedure) and longitudinal (several treatment interventions) trials. Reduction ratio (RR) was used as the measure of plasma PBUTs lowering efficiency. For indoxyl sulphate and p-cresyl sulphate, the highest RR in the acute studies was demonstrated for fractionated plasma separation, adsorption and dialysis system. In the longitudinal trials, supplementation of haemodialysis patients with AST-120 (Kremezin®) adsorbent showed the highest RR. However, no superior method for the reduction of all types of PBUTs was identified based on the published studies.

CONCLUSIONS

Our study shows that there is presently no technique universally suitable for optimum reduction of all PBUTs. There is a clear need for further research in this field.

Thoracic osteophyte as a cause of symptomatic greater splanchnic nerve compression. Case report

Thoracic osteophytes are a common feature of degenerative spine disease. However, it is rare that osteophytes overgrowth on the anterior surface of thoracic spine results in the compression of vital structures and causes symptoms. A 39-year old man with a two-year history of thoracic and upper abdominal pain was admitted to the neurosurgery ward after having been seen by several specialists. Thoracic spine MRI and CT scans were analyzed. Osteophytes were identified on the anterolateral right side at level T8-T9 and were indicated as a possible cause of the symptoms. After obtaining patient consent, surgery was performed with transthoracic access to the anterolateral surface of the spine. Intraoperatively, the greater splanchnic nerve was released by osteophyte removal. The patient reported improvement of the preoperative symptoms at the six-month and two-year follow-up visit. Postoperative MRI indicated complete osteophyte excision. To the best of our knowledge, this is the first report of symptomatic sympathetic trunk branch compression by thoracic osteophytes.

The effect of different dietary ratios of lysine, arginine and methionine on protein nitration and oxidation reactions in turkey tissues and DNA

An assumption was made in the study that the optimal inclusion levels and ratios of lysine (Lys), arginine (Arg) and methionine (Met) in diets with Lys content consistent with National Research Council (NRC) recommendations (1994) contribute to stimulate the antioxidant defense system and prevent disorders resulting from the oxidation and nitration of biologically important molecules. The experiment was carried out on 864 one-day-old Hybrid Converter turkeys divided into six experimental groups (8 replicates per group and 18 birds per replicate) receiving different levels of Arg and Met. Chickens from group Arg₉₀Met₃₀ received 90% Arg and 30% Met relative to Lys; Arg₉₀Met₄₅ - 90% Arg and 45% Met relative to Lys; Arg₁₀₀Met₃₀ - 100% Arg and 30% Met relative to Lys; Arg₁₀₀Met₄₅ - 100% Arg and 45% Met relative to Lys; Arg₁₁₀Met₃₀ - 110% Arg and 30% Met relative to Lys and Arg₁₁₀Met₄₅ - 110% Arg level and 45% Met level relative to the content of dietary Lys. In comparison with turkeys fed diets with moderate Arg content (100% of Lys content), a decrease in dietary Arg level (90% of Lys content) led to a decrease in plasma 3-nitrotyrosine (3-NT) concentration (163.6 vs. 141.0), whereas an increase in dietary Arg level (110% of Lys content) led to an increase in plasma 3-NT concentration (163.6 vs. 202.6). In comparison with turkeys fed diets with moderate Arg content (100% of Lys content), the lowest dietary Arg level (90% of Lys content) decreased superoxide dismutase (SOD) activity in the intestinal wall (19.68 vs. 17.41) and in the liver (11.51 vs. 7.94), increased SOD activity in the blood (507.6 vs. 961.4) and in breast muscles (6.26 vs. 7.43) and increased the concentration of malondiadehyde in breast muscles (1.10 vs. 1.50). An increase in dietary Met content from 30 to 45% of Lys content caused a decrease in plasma protein carbonyl concentration (4.33 vs. 3.8) and catalase activity in breast muscles (54.70 vs. 49.66), and an increase in SOD activity in the liver (8.90 vs. 10.41). The highest dietary Arg level (110% of Lys content) did not induce the oxidation of lipids, proteins or DNA, but it increased the risk of protein nitration. The lowest dietary Arg level (90% of Lys content) deteriorated the antioxidant status of turkeys. Regardless of dietary Arg levels, an increase in Met content from 30 to 45% of Lys content stimulated the antioxidant defense system of turkeys.

Fibrotic remodeling of left ventricle in the murine remnant kidney model of chronic kidney disease is independent of arterial hypertension

Background

Cardiac fibrosis and arterial hypertension are common in patients with chronic kidney disease (CKD). We studied the mechanisms of cardiac fibrogenesis and the role of blood pressure in mice with CKD.

Methods and results

10-week-old male C57/BL6N (BL6) and SV129 wildtype (WT) mice were underwent 5/6 nephrectomy (remnant kidney model, RKM) or sham operation for 10 weeks. RKM significantly elevated plasma creatinine and urea. RKM elicited both interstitial and replacement renal and left ventricular (LV) (BL6: SHAM 5.6±0.4%, RKM 7.3±0.7%, p=0.04; SV129: SHAM 6.0±0.5%, RKM 14±2%, p=0.001) fibrosis as assessed by picrosirius red staining. In parallel, the number of cardiac fibroblasts per mm2 (BL6: SHAM 36±4, RKM 85±13, p=0.001; SV129: SHAM 82±11, RKM 200±34, p=0.006) was increased in RKM mice. With regard to possible mechanisms, cardiac oxidative stress as shown by co-immunostaining for intracellular fibronectin and 8-hydroxyguanosine (BL6: SHAM 44±14%, RKM 60±24%, p=0.03; SV129: SHAM 51±6%, RKM 70±7%, p=0.04) and the percentage of CXCR4+ fibroblasts in the myocardium (BL6: SHAM 47±5%, RKM 62±4%, p=0.04; SV129: SHAM 63±5%, RKM 81±3%, p=0.005) were increased. Furthermore, the number of circulating CD45+ / collagen I+ fibrocytes (FACS) in the peripheral blood was increased by RKM in BL6 (SHAM 100±23%, RKM 443±252%, p=0.04) and diminished in SV129 (SHAM 100±19%, RKM 43±11%, p=0.01), while an opposite regulation was seen in the bone marrow. To further confirm the role of bone-marrow derived fibroblasts in renal and cardiac remodeling 10-week-old WT BL6 mice were subjected to transplantation of bone marrow from 10-week-old WT BL6 mice expressing green fluorescent protein (GFP)+ ubiquitously. 28 days later, RKM or SHAM-operation was performed. RKM significantly increased the number of GFP+ fibroblasts in kidney and LV-myocardium. CKD significantly decreased myocardial capillarization assessed by immunostaining for podocalyxin in both mouse lines. In parallel, myocardial protein expression of fibrosis regulators fibronectin, collagen I, CTGF and Hif1a were up-regulated and expression of the active form of eNOS (phospho-S1177) was reduced.

As a possible confounder, tail-cuff blood pressure was moderately enhanced (Ø 30mmHg) 9 weeks after nephrectomy. In a control experiment using the vasodilator hydralazine (250 mg/L/day), peripheral blood pressure was equalized in all 4 experimental groups, but the extent of LV fibrosis and expression of the above-mentioned fibrosis markers remained unchanged.

Conclusions

Chronic kidney disease in the RKM model elicits left ventricle fibrosis by increasing myocardial protein expression of fibrosis regulators, reduction of myocardial capillarization and mobilization / recruitment of circulating fibroblasts, independently of blood pressure.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Deutsche Forschungsgemeinschaft

The effect of raw and fermented rapeseed cake on growth performance, carcass traits, and breast meat quality in turkey

The objective of this study was to determine the effect of including 15% of raw or fermented rapeseed cake (RRC or FRC) in turkey diets on growth performance, carcass traits, and breast meat characteristics. A total of 1,350 day-old female Hybrid Converter turkeys were allocated to 3 dietary treatments (9 replicates per treatment and 50 birds each) and fed complete isocaloric and isonitrogenous diets. In the control group, soybean meal was the main source of dietary protein, whereas the experimental groups were fed diets containing 15% of RRC or FRC. The fermentation of rapeseed cake reduced the content of glucosinolates and phytate-phosphorus. In comparison with RRC, turkeys receiving FRC achieved significantly higher final BW, comparable with that noted in the control group. The experimental factor had no effect on carcass dressing percentage or carcass fat content, whereas turkeys fed diets containing rapeseed cake were characterized by lower relative weight of breast muscles and higher relative gizzard weight. The muscles of birds from groups RRC and FRC had also significantly lower cholesterol concentration. In comparison with control diet, diets RRC and FRC contributed to a significant decrease in the levels of saturated fatty acids and an increase in the share of n-6 polyunsaturated fatty acids in the total fatty acid pool in breast meat. The highest concentrations of n-3 polyunsaturated fatty acids and the most desirable n-6/n-3 polyunsaturated fatty acid ratio were noted in the breast muscles of RRC group turkeys. Both RRC and FRC reduced catalase and superoxide dismutase activity, and decreased the malondialdehyde content of muscle tissue. In conclusion, the replacement of RRC with FRC in diets led to an increase in the final BW of turkeys, but it had no influence on carcass quality and the majority of meat quality traits. The inclusion of rapeseed products in turkey diets positively affected meat quality, improving the fatty acid profile and antioxidant status, but it also decreased the yield of breast muscles.

Differential expression of cell-cell junction proteins in the testis, epididymis, and ductus deferens of domestic turkeys (Meleagris gallopavo) with white and yellow semen

Tight, adherens, and gap junctions are involved in the regulation of reproductive tissue function in male mammals. In birds, including domestic turkeys, intercellular interactions performed by junctional networks have not yet been studied. Furthermore, the cellular and molecular basis of yellow semen syndrome (YSS) in the turkey population remains poorly understood. Thus, the aim of the present study was 2-fold: first, to provide new information on the localization and expression of cell-cell junction proteins in the testis, epididymis, and ductus deferens of domestic turkeys and second, to compare expression of junctional protein genes between 2 turkey population, one that produces white normal semen (WNS) and the other that produces yellow abnormal semen. Expression of occludin, zonula occludens-1 (ZO-1), connexin 43 (Cx43), N- and E-cadherin, and β-catenin genes were investigated using 3 complementary techniques: quantitative real-time PCR, western blot, and immunohistochemistry. Compared to WNS testis, epididymis, and ductus deferens, YSS tissues exhibited downregulation of occludin and β-catenin mRNA (P < 0.05) and protein (P < 0.05 and P < 0.01, respectively) and upregulation of N- and E-cadherin mRNA (P < 0.001, P < 0.05, P < 0.01, respectively) and protein (P < 0.01, P < 0.05, and P < 0.05, respectively). In contrast, ZO-1 and Cx43 mRNA and protein were upregulated in YSS testis (P < 0.05 and P < 0.001, respectively) but not in epididymis and ductus deferens; both mRNAs and proteins were downregulated (P < 0.05) compared to the respective WNS epididymis and ductus deferens. Altered staining intensity of immunoreactive proteins in YSS vs. WNS reproductive tissue sections confirmed the gene expression results. The present study is the first to demonstrate altered levels of junctional protein gene expression in reproductive tissues of male YSS turkeys. These findings may suggest that subtle changes in junctional protein expression affect the microenvironment in which spermatozoa develop and mature and thus may have an impact on the appearance of yellow semen in domestic turkeys.

Metabolic parameters in young turkeys fed diets with different inclusion levels of copper nanoparticles

The aim of this study was to verify the hypothesis postulating that the supplementation of turkey diets with Cu nanoparticles can lower dietary inclusion levels of Cu without compromising the growth rate and antioxidant status of turkeys. The experiment was carried out on 648 one-day-old Hybrid Converter turkeys divided into 6 groups with 6 replicates per group, in a two-factorial design with 3 dietary inclusion levels of Cu (20, 10 and 2 mg/kg) and 2 dietary sources of Cu - copper sulfate (Cu-SUL) and Cu nanoparticles (Cu-NP). At 42 days of age, blood samples were collected from 2 birds per replicate (12 birds per group), after slaughter livers were collected for analyses. Blood and liver samples were assayed for: Cu, Zn, Ca, P, Mg, GLU, TP, ALB, UREA, TAG, TC, UA, ALT, AST, ALT, GGT, ALP, SOD, GPx, CAT, VIT C, FRAP, GSH+GSSG, LOOH, MDA. The results of this experiment demonstrate that a decrease in the dietary inclusion levels of Cu from 10 mg/kg to 2 mg/kg does not compromise the growth performance of turkeys, but weakens antioxidant defense mechanisms. A Cu dose of 20 mg/kg induces oxidation reactions and has a much more inhibitory effect on the antioxidant defense system than dietary Cu content of 2 mg/kg. In turkeys, dietary supplementation with Cu-NP has a more beneficial effect on carbohydrate metabolism and antioxidant status compared with Cu-SUL. The results of analyses examining the antioxidant and metabolic status of young turkeys indicate that 10 mg/kg is the optimal dietary inclusion level of Cu.

Differences in aromatase expression and steroid hormone concentrations in the reproductive tissues of male domestic turkeys (Meleagris gallopavo) with white and yellow semen

1. To show hormonal differences between male turkeys with yellow semen syndrome (YSS) and white, normal semen (WNS), the expression of aromatase, oestrogen receptor α (ERα), and oestrogen receptor β (ERβ) as well as testosterone and oestradiol concentrations in YSS and WNS testes, epididymis, and ductus deferens were examined. 2. To measure gene expression levels of aromatase and oestrogen receptors (ERs), three complementary techniques (real-time PCR, Western blot, and immunohistochemistry) were used, whereas steroid hormone levels were determined radio-immunologically. 3. Upregulation of aromatase and ERα mRNAs in YSS testes (P < 0.05; P < 0.01), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.05; P < 0.01) compared to those of WNS tissues was detected. Significant increases in the levels of aromatase and ERα proteins were detected in YSS testes (P < 0.001; P < 0.05), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.001; P < 0.05). The expression of ERβ mRNA and protein level was upregulated in the testes (P < 0.05; P < 0.01) and epididymis (P < 0.001; P < 0.01) but not in ductus deferens where it was downregulated (P < 0.01; P < 0.01). Increased intensity of immunoreactive proteins in YSS versus WNS reproductive tissues corroborated gene expression results. 4. Testosterone concentration diminished in YSS epididymis (P < 0.05) and ductus deferens (P < 0.05), but not in the testes, remaining at high level (P < 0.05) compared to WNS values. Concomitantly, increased oestradiol concentration was found in YSS testes (P < 0.05) and epididymis (P < 0.05) but decreased in the ductus deferens (P < 0.05). 5. From the published literature, this study is the first to demonstrate the ability for androgen aromatisation in the turkey reproductive tissues and to show the cellular targets for locally produced oestrogens. The data suggested that the androgen/oestrogen ratio is a mechanistic basis for amplification of differences between turkeys with white and yellow semen and that these results can have a relevance in applied sciences to widen the knowledge on domestic bird reproduction.

The effect of DL-, L-isomers and DL-hydroxy analog administered at 2 levels as dietary sources of methionine on the metabolic and antioxidant parameters and growth performance of turkeys

A hypothesis was verified that dietary methionine (Met) improves the growth and antioxidant status of turkeys, and that its effects depend on dietary inclusion levels and sources. A total of 816 female Hybrid Converter turkeys was fed wheat-soybean meal-based diets supplemented with 3 sources of Met: DL-, L-isomers and DL-hydroxy analog (DLM, LM, and MHA, respectively). In 4 4-week periods (from one to 16 wk of age), dietary Met content corresponded to NRC (1994) recommendations or was increased by approximately 50% (in one to 8 wk by 44 to 46% and in 9 to 16 wk by 55 to 56% vs. the NRC guidelines) to match the recommendations of some breeding companies. Increased Met content resulted in higher final body weights of turkeys (P = 0.002), an improved feed conversion ratio (P = 0.049), increased total glutathione concentration and ferric reducing ability of plasma (FRAP) values, and decreased malondialdehyde (MDA) concentration (all P < 0.001) in the blood plasma of turkeys. In comparison with DLM, LM and MHA contributed to an increase in plasma glutathione concentration (P = 0.001), a decrease in plasma triacylglycerol (P = 0.003) and uric acid (P = 0.001) concentrations, and a decrease in liver MDA (P = 0.001) levels. A decrease in plasma MDA (vs. DLM) and lipid peroxides (LOOH) (vs. DLM and LM) concentrations as well as a decrease in plasma superoxide dismutase (SOD) activity (vs. DLM and LM) also were noted in the MHA treatment (P = 0.016, P = 0.001 and P = 0.011, respectively). In conclusion, the results of the study indicate that the antioxidant status of turkeys could be affected by dietary Met levels and sources. The dietary Met content increased by 50% relative to NRC recommendations, improved the growth performance of turkeys, and strengthened their antioxidant defense system. In comparison with DLM, LM and MHA could be considered positive nutritional factors as manifested by a beneficial decrease in plasma and hepatic MDA concentrations as well as an increase in plasma glutathione levels, and the effect of MHA was more pronounced.

Proteomic identification of turkey (Meleagris gallopavo) seminal plasma proteins

SDS-PAGE combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and 2-dimensional electrophoresis (2DE) combined with matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (MALDI TOF/TOF) were applied to characterize the turkey seminal plasma proteome. LC-MS/MS led to the identification of 175 proteins, which were classified according to their function and to corresponding biochemical pathways. Using 2DE and MALDI TOF/TOF, 34 different turkey seminal plasma proteins could be identified, of which 20 were found in more than one spot, indicating different proteoforms of these proteins. For validation, antibodies against turkey albumin and ovoinhibitor as well as sperm acrosin were used in 2DE Western blots experiments. The bioinformatic analysis of the results indicates that turkey seminal plasma proteins may be involved in regulation of lipid metabolism [liver X receptor/retinoid X receptor (LXR/RXR) activation and farnesoid X receptor/retinoid X receptor (FXR/RXR) activation pathways)], endocytic entry of proteins and lipids at the plasma membrane (clathrin-mediated endocytosis pathway), and defense against pathogens (acute phase response signaling pathway) and energy production (glycolysis and gluconeogenesis). Moreover, a comparative meta-analysis of seminal plasma proteomes from other species indicated the presence of proteins specific for avian reproduction, but distinct differences between turkey and chicken seminal plasma proteomes were detected. The results of our study provide basic knowledge of the protein composition of turkey seminal plasma highlighting important physiological pathways which may play crucial roles in the sperm environment after ejaculation. This knowledge can be the basis to further develop procedures improving the reproduction of farmed turkeys.

The effect of dietary faba bean and non-starch polysaccharide degrading enzymes on the growth performance and gut physiology of young turkeys

The aim of this study was to investigate the effect of dietary replacement of soya bean meal (SBM) with faba bean (FB) and a blend of non-starch polysaccharide (NSP) degrading enzymes on the gastrointestinal function, growth performance and welfare of young turkeys (1 to 56 days of age). An experiment with a 2×2 factorial design was performed to compare the efficacy of four diets: a SBM-based diet and a diet containing FB, with and without enzyme supplementation (C, FB, CE and FBE, respectively). In comparison with groups C, higher dry matter content and lower viscosity of the small intestinal digesta were noted in groups FB. The content of short-chain fatty acids (SCFAs) in the small intestinal digesta was higher in groups FB, but SCFA concentrations in the caecal digesta were comparable in groups C and FB. In comparison with control groups, similar BW gains, higher feed conversion ratio (FCR), higher dry matter content of excreta and milder symptoms of footpad dermatitis (FPD) were noted in groups FB. Enzyme supplementation increased the concentrations of acetate, butyrate and total SCFAs, but it did not increase the SCFA pool in the caecal digesta. The enzymatic preparation significantly improved FCR, reduced excreta hydration and the severity of FPD in turkeys. It can be concluded that in comparison with the SBM-based diet, the diet containing 30% of FB enables to achieve comparable BW gains accompanied by lower feed efficiency during the first 8 weeks of rearing. Non-starch polysaccharide-degrading enzymes can be used to improve the nutritional value of diets for young turkeys, but more desirable results of enzyme supplementation were noted in the SBM-based diet than in the FB-based diet.

Back-calculating baseline creatinine overestimates prevalence of acute kidney injury with poor sensitivity

AIM

Acute kidney injury (AKI) is diagnosed by a 50% increase in creatinine. For patients without a baseline creatinine measurement, guidelines suggest estimating baseline creatinine by back-calculation. The aim of this study was to evaluate different glomerular filtration rate (GFR) equations and different GFR assumptions for back-calculating baseline creatinine as well as the effect on the diagnosis of AKI.

METHODS

The Modification of Diet in Renal Disease, the Chronic Kidney Disease Epidemiology (CKD-EPI) and the Mayo quadratic (MQ) equation were evaluated to estimate baseline creatinine, each under the assumption of either a fixed GFR of 75 mL min^-1  1.73 m^-2 or an age-adjusted GFR. Estimated baseline creatinine, diagnoses and severity stages of AKI based on estimated baseline creatinine were compared to measured baseline creatinine and corresponding diagnoses and severity stages of AKI.

RESULTS

The data of 34 690 surgical patients were analysed. Estimating baseline creatinine overestimated baseline creatinine. Diagnosing AKI based on estimated baseline creatinine had only substantial agreement with AKI diagnoses based on measured baseline creatinine [Cohen's κ ranging from 0.66 (95% CI 0.65-0.68) to 0.77 (95% CI 0.76-0.79)] and overestimated AKI prevalence with fair sensitivity [ranging from 74.3% (95% CI 72.3-76.2) to 90.1% (95% CI 88.6-92.1)]. Staging AKI severity based on estimated baseline creatinine had moderate agreement with AKI severity based on measured baseline creatinine [Cohen's κ ranging from 0.43 (95% CI 0.42-0.44) to 0.53 (95% CI 0.51-0.55)].

CONCLUSION

Diagnosing AKI and staging AKI severity on the basis of estimated baseline creatinine in surgical patients is not feasible. Patients at risk for post-operative AKI should have a pre-operative creatinine measurement to adequately assess post-operative AKI.

Haemodiafiltration at increased plasma ionic strength for improved protein-bound toxin removal

AIM

Protein-bound uraemic toxin accumulation causes uraemia-associated cardiovascular morbidity. Enhancing the plasma ionic strength releases toxins from protein binding and makes them available for removal during dialysis. This concept was implemented through high sodium concentrations ([Na⁺ ]) in the substituate of pre-dilution haemodiafiltration at increased plasma ionic strength (HDF-IPIS).

METHODS

Ex vivo HDF-IPIS with blood tested increasing [Na⁺ ] to demonstrate efficacy and haemocompatibility. Haemocompatibility was further assessed in sheep using two different HDF-IPIS set-ups and [Na⁺ ] between 350 and 600 mmol L^-1 . Safety and efficacy of para-cresyl sulphate (pCS) and indoxyl sulphate (IS) removal was further investigated in a randomized clinical pilot trial comparing HDF-IPIS to HD and HDF.

RESULTS

Compared to [Na⁺ ] of 150 mmol L^-1 , ex vivo HDF-IPIS at 500 mmol L^-1 demonstrated up to 50% higher IS removal. Haemolysis in sheep was low even at [Na⁺ ] of 600 mmol L^-1 (free Hb 0.016 ± 0.001 g dL^-1 ). In patients, compared to HD, a [Na⁺ ] of 240 mmol L^-1 in HDF-IPIS resulted in 40% greater reduction (48.7 ± 23.6 vs. 67.8 ± 7.9%; P = 0.013) in free IS. Compared to HD and HDF (23.0 ± 14.8 and 25.4 ± 10.5 mL min^-1 ), the dialytic clearance of free IS was 31.6 ± 12.8 mL min^-1 (P = 0.017) in HDF-IPIS, but [Na⁺ ] in arterial blood increased from 132 ± 2 to 136 ± 3 mmol L^-1 (0 vs. 240 min; P < 0.001).

CONCLUSION

HDF-IPIS is technically and clinically feasible. More effective HDF-IPIS requires higher temporary plasma [Na⁺ ], but dialysate [Na⁺ ] has to be appropriately adapted to avoid sodium accumulation.

Antioxidant status of blood and liver of turkeys fed diets enriched with polyunsaturated fatty acids and fruit pomaces as a source of polyphenols

It was hypothesized that dietary polyphenol-rich fruit pomaces can improve the antioxidant status of both diets and the tissues of turkeys fed such diets. Turkeys were fed diets containing a cellulose preparation (C) or 5% dried apple pomace (AP), blackcurrant pomace (BCP), strawberry pomace (SP) and seedless strawberry pomace (SSP). Blood and liver biochemical parameters were determined in 7 birds from each experimental group slaughtered at 15 weeks of age, after 5 weeks of feeding diets containing soybean oil and linseed oil (approx. 1:1 ratio). Dietary linseed oil added to diets at 2.5% lowered the n-6/n-3 PUFA ratio from approx. 7:1 to below 2:1, thus reducing the antioxidant properties of diets measured using DPPH, ABTS and photo-chemiluminescence assays, compared with diets containing only soybean oil and administered to birds in the first phase of feeding. Fruit pomaces, in particular SSP with the highest polyphenol content (32.81 g/kg) and the highest antioxidant activity (256.4 μM Trolox/g), increased the antioxidant capacity of turkey diets. In comparison with the control group, the dietary treatments with fruit pomaces improved blood antioxidant parameters, including catalase activity (groups AP and BCP), the total antioxidant capacity of hydrophilic (group AP) and lipophilic (groups AP, SP, and SSP) compounds, peroxide levels (groups AP and SSP) and antioxidant capacity measured by the FRAP (ferric reducing antioxidant power of plasma) assay (groups AP, BCP and SSP). Significantly lower concentrations of both vitamin E and thiobarbituric acid reactive substances (TBARS) were noted in the livers of turkeys fed all diets with dried fruit pomaces.

Biochemical and immunological responses of young turkeys to vaccination against Ornithobacterium rhinotraheale and different levels of dietary methionine

The objective of this study was to verify the hypothesis that increasing levels of dietary methionine can stimulate the mechanisms of cell-mediated and humoral immunity in young turkeys. The blood and organs involved in cell-mediated and humoral immune responses were analyzed in 8-week-old turkeys that had been vaccinated against Ornithobacterium rhinotraheale (ORT) infection (on days 17 and 48). The birds were fed diets with a low (LM), medium (MM) and high (HM) methionine content (0.45 and 0.40%, 0.60 and 0.51%, 0.71 and 0.57% in weeks 1 - 4 and 5 - 8, respectively). Dietary methionine supplementation led to a significant increase in body weights of turkeys at 56 days of age, from 3532 g in group LM to 3720 g in group MM and 3760 g in group HM (p=0.001). A significant increase in vaccine-induced antibody titers against ORT was noted in group HM relative to group LM (p=0.006). Increasing levels of methionine had no significant effect on total serum IgG nor IgM levels and most serum biochemical parameters, TP, ALB, GLOB, GLU, AST, ALP, P and Ca. In comparison with group LM, group HM turkeys were characterized by a lower percentage of IgM⁺ B cell subpopulation in the blood and bursa of Fabricius. The percentages of CD4⁺ and CD8⁺ T cell subpopulations in the bursa of Fabricius in group HM were significantly different from those found in groups LM and MM. The highest percentages of CD4⁺ T cells and CD8⁺ T cells in the spleen were observed in groups LM (p<0.001) and HM (p=0.04), respectively. The differences were statistically significant relative to the remaining groups. Turkeys of group LM were characterized by a lower CD4⁺ T cell percentage in the thymus (p<0.001) and a lower CD8⁺ T cell percentage in the cecal tonsils (CTs) (p<0.01). Vaccination against ORT resulted in a significant increase in the percentage of CD4⁺CD8⁺ T cell subpopulation and a decrease in the percentage of CD8⁺ T cell subset in the spleen.

The effects of dietary dried fruit pomaces on growth performance and gastrointestinal biochemistry of turkey poults

One-day-old female turkeys were randomly assigned to five dietary treatments and were fed for 15 weeks diets containing 5% of cellulose (control, C) or 5% of dried fruit pomaces (apple, black currant, strawberry, seedless strawberry; AP, BCP, SP, SSP respectively). In weeks 11-15 of feeding, all diets were supplemented with 2.5% of linseed oil. The crude fibre content of fruit pomaces ranged from 56.5% in AP to 62.9% in SP. In comparison with AP, berry fruit pomaces (BCP, SP and SSP) were characterised by a higher content of neutral detergent fibre - NDF (41.2% vs. 52.7-59.3%) and lignin (13.24% vs. 21.80-25.56%). A monomer analysis revealed that cellulose was the main non-starch polysaccharide (NSP) in fruit pomaces, whereas their pectin content was low. Polyphenol content was determined at below 6 g/kg in AP, at approximately 12 g/kg in BCP and SP, and at 32.8 g/kg in SSP. There were no significant differences (p > 0.05) in final body weight of birds. After 15 weeks of feeding fruit pomaces to turkeys, the relative weight of the small intestine with digesta was higher in group AP, and lower in group SSP, as compared to controls. Dietary fruit pomaces decreased the dry matter (DM) concentration and lowered the pH of the small intestinal digesta, except the AP and SSP treatments respectively. In the caeca, significantly reduced concentrations of ammonia or putrefactive short-chain fatty acids (SCFA) upon dietary fruit pomaces were observed. Fruit pomaces did not influence the concentrations or the total pool of short-chain fatty acids, but led to a significant increase in butyric proportion in the SCFA profile at the expense propionate.

Guanidinylations of albumin decreased binding capacity of hydrophobic metabolites

AIM

As post-translational modifications of proteins may have an impact on the pathogenesis of diseases such as atherosclerosis, diabetes mellitus and chronic kidney disease (CKD), post-translational modifications are currently gaining increasing interest. In this study, a comprehensive method for analysis of these post-translational modifications is established for the clinical diagnostic routine.

METHODS

Here, we analysed albumin - the most abundant plasma protein in human - isolated from patients with CKD and healthy controls by chromatographic steps and identified by MALDI mass spectrometry. Post-translational modifications of albumin were identified after digestion by analysing mass signal shifts of albumin peptides using pertinent mass databases.

RESULTS

Albumin isolated from plasma of patients with CKD but not from healthy control subjects was specifically post-translationally modified by guanidinylation of lysines at positions 249, 468, 548, 565 and 588. After identification of guanidinylations as post-translational modifications of albumin isolated from patients with CKD, these modifications were quantified by mass spectrometry demonstrating a significant increase in the corresponding mass signal intensities in patients with CKD compared to healthy controls. The relative amount of guanidinylation of lysine at position 468 in patients with CKD was determined as 63 ± 32% (N = 3). Subsequently, we characterized the pathophysiological impact of the post-translational guanidinylation on the binding capacity of albumin for representative hydrophobic metabolic waste products. In vitro guanidinylation of albumin from healthy control subjects caused a decreased binding capacity of albumin in a time-dependent manner. Binding of indoxyl sulphate (protein-bound fraction) decreased from 82 ± 1% of not post-translationally modified albumin to 56 ± 1% after in vitro guanidinylation (P < 0.01), whereas the binding of tryptophan decreased from 20 to 4%. These results are in accordance with the binding of indoxyl sulphate to albumin from healthy control subjects and patients with CKD (88 ± 3 vs. 74 ± 10, P < 0.01). Thus, in vitro post-translational guanidinylation of albumin had a direct effect on the binding capacity of hydrophobic metabolites such as indoxyl sulphate and tryptophan.

CONCLUSION

We used a mass spectrometry-based method for the characterization of post-translational modification and demonstrated the pathophysiological impact of a representative post-translational modification of plasma albumin. The data described in this study may help to elucidate the pathophysiological role of protein modifications.

In ovo injection of prebiotics and synbiotics affects the digestive potency of the pancreas in growing chickens

The purpose of the study was to examine the effect of 2 prebiotics and 2 synbiotics on the digestive potency of pancreas in 1-, 3-, 7-, 14-, 21-, and 34-day-old cockerels. Prebiotics (inulin and Bi²tos) and synbiotics (inulin + Lactococcus lactis subsp. lactis and Bi²tos + Lactococcus lactis subsp. cremoris) were injected in ovo into the air cell on the 12th d embryonic development. Their application increased the activity of amylase, lipase, and trypsin in the pancreas. The most pronounced changes were observed at the end of the investigated rearing period (d 34). The strongest stimulative effects on amylase were shown by both synbiotics, on lipase synbiotic Bi²tos + Lactococcus lactis subsp. cremoris, and on trypsin all the used prebiotics and synbiotics. Simultaneously, neither the absolute nor the relative mass of the pancreas in comparison to control group were changed. Also, the injected in ovo compounds did not cause a deterioration in the posthatching condition of the chicken liver, as determined by measurement of the activity of marker enzymes in the blood (alanine aminotransferase and aspartate aminotransferase). Treatment with the prebiotics and synbiotics did not change the feed conversion ratio but Bi²tos (galacto-oligosaccharide) and inulin (fructan) + Lactococcus lactis subsp. lactis significantly increased final BW.

Concentrations of the adrenocorticotropic hormone, corticosterone and sex steroid hormones and the expression of the androgen receptor in the pituitary and adrenal glands of male turkeys (Meleagris gallopavo) during growth and development

Androgens take part in the regulation of puberty and promote growth and development. They play their biological role by binding to a specific androgen receptor (AR). The aim of this study was to evaluate the expression of AR mRNA and protein in the pituitary and adrenal glands, to localize AR protein in luteinizing hormone (LH)-producing pituitary and adrenocortical cells, to determine plasma concentrations of adrenocorticotropic hormone (ACTH) and corticosterone and the concentrations of corticosterone, testosterone (T), androstenedione (A4) and oestradiol (E2) in the adrenal glands of male turkeys at the age of 4, 8, 12, 16, 20, 24 and 28weeks. The concentrations of hormones and the expression of AR varied during development. The expression of AR mRNA and protein in pituitary increased during the growth. The increase of AR mRNA levels in pituitary occurred earlier than increase of AR protein. The percentage of pituitary cells expressing ARs in the population of LH-secreting cells increased in week 20. It suggests that AR expression in LH-producing pituitary cells is determined by the phase of development. The drop in adrenal AR mRNA and protein expression was accompanied by an increase in the concentrations of adrenal androgens. Those results could point to the presence of a compensatory mechanism that enables turkeys to avoid the potentially detrimental effects of high androgen concentrations. Our results will expand our knowledge of the role of steroids in the development of the reproductive system of turkeys from the first month of age until maturity.

Expression of the androgen receptor in the testes and the concentrations of gonadotropins and sex steroid hormones in male turkeys (Meleagris gallopavo) during growth and development

Androgens, including testosterone (T) and androstenedione (A4), are essential for puberty, fertility and sexual functions. The biological activity of those hormones is mediated via the androgen receptor (AR). The regulation of androgen action in birds is poorly understood. Therefore, the present study analysed mRNA and protein expression of AR in the testes, plasma concentrations of the luteinizing hormone (LH), follicle-stimulating hormone (FSH), T, A4 and oestradiol (E2), as well as the levels of T, A4 and E2 in testicular homogenates of male turkeys (Meleagris gallopavo) at the age of 4, 8, 12, 16, 20, 24 and 28weeks. Plasma concentrations of LH and FSH, as well as plasma and testicular levels of T and A4 began to increase at 20weeks of age. The lowest plasma levels of E2 were noted at 20weeks relative to other growth stages. The 20th week of life seems to be the key phase in the development of the reproductive system of turkeys. The AR protein was found in the nuclei of testicular cells in all examined growth stages. Higher expression of AR protein in the testes beginning at 20weeks of age was accompanied by high plasma concentrations of LH and high plasma and testicular levels of androgens. This relationship seems to be necessary to regulate male sexual function.

Diadenosine pentaphosphate modulates glomerular arteriolar tone and glomerular filtration rate

INTRODUCTION

Mechanisms and participating substances involved in the reduction of glomerular filtration (GFR) in contrast-induced acute kidney injury (CI-AKI) are still matter of debate. We hypothesized that diadenosine polyphosphates are released by the action of contrast media on tubular cells and may act on glomerular arterioles and reduce GFR.

METHODS

Freshly isolated rat tubules were treated with the contrast medium iodixanol (47 mg iodine per mL) at 37 °C for 20 min. The content of Apn A (n = 3-6) in the supernatant of treated tubules and in the plasma of healthy persons and patients with AKI was analysed using reversed-phase chromatography, affinity chromatography and mass spectrometry. GFR was obtained in conscious mice by inulin clearance. Concentration response curves for Apn A (n = 3-6, 10(-12) -10(-5)  mol L(-1) ) were measured in isolated perfused glomerular arterioles.

RESULTS

Iodixanol treatment of tubules significantly increased the concentration of Apn A (n = 3-5) in the supernatant. Ap6 A was below the detection limit. AKI patient shows higher concentrations of Apn A compared to healthy. Application of Ap5 A significantly reduced the GFR in conscious mice. Ap5 A reduced afferent arteriolar diameters, but did not influence efferent arterioles. The constrictor effect on afferent arterioles was strong immediately after application, but weakened with time. Then, non-selective P2 inhibitor suramin blocked the Ap5 A-induced constriction.

CONCLUSION

The data suggest that Ap5 A plays a role in the pathophysiology of CI-AKI. We show a contrast media-induced release of Ap5 A from tubules, which might increase afferent arteriolar resistance and reduce the GFR.

Effects of increased stocking density and heat stress on growth, performance, carcase characteristics and skeletal properties in turkeys

Effects of increased stocking density and heat stress on growth, feed conversion, carcase characteristics and skeletal system properties in turkeys were determined. One-day-old males (n=1674) were divided into two weight-matched groups exposed to different environmental conditions. Controls were reared at a stocking density of 2.8 birds/m(2) and at thermo-neutral temperature (TnT group), while the experimental group was exposed to heat-stress (HSID group) and reared at a stocking density of 3.4 birds/m(2) and ambient temperature increased by 5°C. At 28 days of age, 27 birds from each group were sacrificed, while at 126 days of age, 54 birds from each group were slaughtered. Increased stocking density and ambient temperature during the first four weeks of life increased the body weight (BW) of turkeys and weight, length, volume, vertical internal and horizontal external diameters of the tibia in the HSID group compared with the TnT group (P<0.05). In turkeys older than four weeks, increased stocking density and ambient temperature significantly decreased daily feed intake, final BW and relative weight of drumstick muscle by 4.7 per cent, 4.0 per cent and 3.3 per cent, respectively (P<0.05). The weight, length, volume, vertical and horizontal diameters, cross-sectional area, second moment of inertia, volumetric bone mineral density, maximum elastic strength and ultimate strength of bones were significantly lower in turkeys in the HSID group (P<0.05) at 126 days compared with turkeys in the TnT group at the same age. These results indicate that, up to four weeks of age, turkeys tolerate increased stocking density and heat stress better than birds between 5 and 18 weeks of age.