Gut microbiome in hemodialysis patients treated with calcium acetate or treated with sucroferric oxyhydroxide: a pilot study

Purpose It has been proved that the gut microbiome is altered in patients with chronic kidney disease. This contributes to chronic inflammation and increases cardiovascular risk and mortality, especially in those undergoing hemodialysis. Phosphate binders may potentially induce changes in their microbiome. This trial aimed to compare the changes in the gut microbiome of hemodialysis patients treated with calcium acetate to those treated with sucroferric oxyhydroxide. Methods Twelve hemodialysis patients were distributed to receive calcium acetate or sucroferric oxyhydroxide for 5 months. Blood samples (for biochemical analysis) and stool samples (for microbiome analysis) were collected at baseline, 4, 12, and 20 weeks after treatment initiation. Fecal DNA was extracted and a 16S rRNA sequencing library was constructed targeting the V3 and V4 hypervariable regions. Results Regarding clinical variables and laboratory parameters, no statistically significant differences were observed between calcium acetate or sucroferric oxyhydroxide groups. When analyzing stool samples, we found that all patients were different (p = 0.001) among themselves and these differences were kept along the 20 weeks of treatment. The clustering analysis in microbial profiles grouped the samples of the same patient independently of the treatment followed and the stage of the treatment. Conclusion These results suggest that a 5-month treatment with either calcium acetate or sucroferric oxyhydroxide did not modify baseline diversity or baseline bacterial composition in hemodialysis patients, also about the high-variability profiles of the gut microbiome found among these patients.

Influence of Calcium Acetate Concentration in Electrolyte on Tribocorrosion Behaviour of MAO Treated Titanium

Ti-based materials are widely used for dental and orthopaedic implant applications due to their adequate mechanical properties, corrosion behaviour and biocompatibility. However, these materials are biologically inert and display poor wear resistance. In one of the most studied processes that aims to overcome these drawbacks, Ti surfaces are often covered by anodic oxide films with the incorporation of bioactive agents such as Ca and P. Although there are several works on the tribocorrosion behaviour of MAO-treated Ti surfaces, the influence of electrolyte composition on the corrosion kinetics under sliding is yet to be fully understood. In the present work, anodic oxide films were produced on cp-Ti surfaces with different calcium acetate concentrations in the electrolyte. Tribocorrosion behaviour was investigated by reciprocating sliding tests performed in 8 g/L NaCl solution at body temperature, under potentiostatic conditions. The results showed that higher concentrations of calcium acetate had a detrimental effect on tribocorrosion kinetics, however, they resulted in less mechanical damage due to alterations in the topography and structure of the MAO layer.

"Ideal" PTH in ESA-Resistant Anemia

Background: Anemia is a nearly universal complication of End Stage Renal Disease (ESRD). Erythropoiesis-stimulating agents (ESAs) have greatly decreased transfusion dependence in the anemia of ESRD. In some cases, ESAs are not effective, indicating ESA-resistance. ESA-resistant anemia is not well characterized and can be difficult to manage. Among the most frequent causes of ESA-resistant anemia is secondary hyperparathyroidism (SHP), which can induce bone marrow remodeling and fibrosis. Treatment protocols in SHP are centered on goal calcium, phosphorus and parathyroid hormone (PTH) levels and not the biologic consequences of high PTH. The hematologic insults secondary to SHP are rarely addressed. Instead, it is common to simply increase ESA dosing, rather than address the cause of ESA-resistance. In this retrospective review, we describe a cohort of patients with ESRD and SHP and highlight in detail one patient with reversible bone marrow changes and transfusion-dependent anemia, as well as descriptive and laboratory findings of bone marrow changes in patients with anemia and ESRD referred to our center. Methods: Using the EMR, the patient's data including demographics, progress notes, laboratory values, and bone marrow findings were extracted. Subsequently, the EMR was interrogated to reveal all patients with anemia and ESRD, who had undergone a bone marrow biopsy at out center over a ten year period from 2010 to 2020, revealing 64 patients. Data including demographics, laboratory values, bone marrow findings, and medications were extracted. Data was presented descriptively. Results: A 67-year-old male with ESRD secondary to hypertension and type 2 diabetes was referred to our Hematology clinic for anemia of ESRD. He was receiving Epoetin 20,000 IU three times weekly but was still transfusion-dependent to maintain a hemoglobin of 6.3 g/dL, with a concomitant PTH of 400.5 pg/mL. Calcium and phosphorus were normal and thus his SHP was not aggressively managed. Bone marrow biopsy revealed focal areas of bone marrow remodeling and reticulin fibrosis. Fluorescence in situ hybridization studies for myelodysplastic syndrome were negative, as were thyroid studies, serum protein electrophoresis, and free light chain ratio. In conjunction with his nephrologist, treatment of his SHP was optimized. His initial regimen was calcitriol 0.25 mcg once daily and calcium acetate 667 mg three times daily. Subsequently, cinacalcet 30 mg twice daily was added and calcium acetate was replaced with sevelamer 1600 mg three times daily. Following these changes, his hemoglobin remained stable in the range of 8-9 g/dL. He was no longer transfusion-dependent, despite only a modest reduction in PTH to 311.2 pg/mL. Repeat bone marrow biopsy revealed no bone marrow remodeling or reticulin fibrosis. Bone marrow findings for all patients referred to our clinic with ESRD and anemia are summarized in Table 1. The range of PTH for patients with bony remodeling was 183-16161.9 pg/mL versus 90.8-3283 pg/mL for those without bony remodeling. The range of PTH for patients with fibrotic changes was 183-2487 pg/mL versus 90.8-16161.9 pg/mL for those without fibrotic changes. ESA dosing varied among the patients. Conclusion: SHP is an increasingly identifiable cause of ESA-resistant anemia, as demonstrated by the reversal of transfusion dependence in our patient once SHP was more adequately treated. The degree of reversible ESA-resistant anemia and transfusion dependence in the setting of a PTH elevation to 400.5 in this case is surprising. The great variability in PTH levels of patients both with and without bone marrow changes presented here indicates the relationship between SHP and anemia is intricate. A single target level for the whole dialysis population is not appropriate; neither is targeting only and the same goal calcium, phosphorus, and PTH levels for the whole dialysis population either. Based on the findings of our institutional cohort, we suggest that it is justified to deviate from "on-size-fits-all" protocols and attempt a trial of aggressive management of SHP in patients with difficult to manage ESA-resistant anemia with what is considered only modest PTH elevation. Figure 1 Figure 1. Disclosures Moe: Allena Pharmaceutical: Consultancy; Janssen: Consultancy; Alnylum: Consultancy; DIcerna: Consultancy; Tricida: Consultancy.

Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Soil P testing has been widely used to predict crop yields, P uptake, and fertilizer demands in agriculture. Diffusive gradients in thin films (DGT) provides a zero-sink soil P test which mimics diffusion-controlled plant uptake and has previously been found to predict P availability to crops better than conventional quantity-based P tests in highly weathered Australian, though not in European soils. Here we tested the performance of DGT and the Austrian and German standard P quantity test calcium acetate lactate (CAL) to explain the variation of crop yield and P uptake response of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) in long-term P fertilization experiments at four different sites in eastern Austria. Phosphorus extracted with DGT (P-DGT) and CAL (P-CAL) correlated well in similar soils but not across sites with large variation in soil and site properties such as carbonate equivalent and water availability. The predictive power of DGT for barley (R2 = 0.42) and wheat grain yield (R2 = 0.32), and P uptake in wheat grains (R2 = 0.36) was clearly superior to that of the CAL, and less dependent on soil properties. The better performance of DGT compared to the quantity test is consistent with diffusion-limited P uptake in the water-limited cultivated soils of eastern Austria. The critical values of P deficiency derived from the Mitscherlich-type fits for barley and wheat at 80% relative yield are 64.9 and 26.2 µg L−1, respectively, consistent with differential P demands of the crops.

Simple and Rapid Synthesis of Calcium Acetate from Scallop Shells to Reduce Environmental Issues

The search for sustainable resources remains a subject of global interest. Calcium acetate used in many fields was prepared using waste scallop shell as a raw material, and its physicochemical properties were investigated. The waste scallop shells were transformed to calcium acetate compounds by reactions with four acetic acid concentrations at ambient temperature until the completely dried powder is obtained. The maximum yield of 87% with short reaction time at a low temperature was observed in the reaction of 60%w/w acetic acid with scallop shells. Thermal transformation reactions of all prepared calcium acetate samples revealed temperature conditions for heating to produce other advanced materials. FTIR and XRD results confirmed the purity and solid phase of all prepared calcium acetate samples, and they were compared with those of literatures and found to be well consistent. The obtained timber-like particles have different sizes depending on the acetic acid concentration. This work reports an easy and low-cost method with no environmental effect to produce cheap calcium products to be used in the industry.