Kidney stone matrix proteins: Role in stone formation.

Stone formation is induced by an increased level of urine crystallization promoters and reduced levels of its inhibitors. Crystallization inhibitors include citrate, magnesium, zinc, and organic compounds such as glycosaminoglycans. In the urine, there are various proteins, such as uromodulin (Tamm-Horsfall protein), calgranulin, osteopontin, bikunin, and nephrocalcin, that are present in the stone matrix. The presence of several carboxyl groups in these macromolecules reduces calcium oxalate monohydrate crystal adhesion to the urinary epithelium and could potentially protect against lithiasis. Proteins are the most abundant component of kidney stone matrix, and their presence may reflect the process of stone formation. Many recent studies have explored the proteomics of urinary stones. Among the stone matrix proteins, the most frequently identified were uromodulin, S100 proteins (calgranulins A and B), osteopontin, and several other proteins typically engaged in inflammation and immune response. The normal level and structure of these macromolecules may constitute protection against calcium salt formation. Paradoxically, most of them may act as both promoters and inhibitors depending on circumstances. Many of these proteins have other functions in modulating oxidative stress, immune function, and inflammation that could also influence stone formation. Yet, the role of these kidney stone matrix proteins needs to be established through more studies comparing urinary stone proteomics between stone formers and non-stone formers.

Nuevas estrategias terapéuticas para tratar la hiperfosfatemia en la IRC: foco en la absorción intestinal / New therapeutic strategies to treat hyperphosphatemia in CRF: focus on intestinal absorption

RESUMEN El manejo de la hiperfosfatemia de los pacientes con insuficiencia renal crónica en diálisis permanece como un desafío. A pesar de utilizar un enfoque multifacético que incluye la restricción dietética, la remoción de fósforo por la diálisis y el uso de quelantes de fósforo, esta estrategia múltiple no logra reducir los niveles de fósforo en más de 2 mg/dl. El control de fósforo de los pacientes en diálisis es fundamental en razón de la relación monotónica entre los niveles séricos de fosfato y el incremento del riesgo cardiovascular. Por lo tanto, hay una necesidad de explorar nuevas estrategias para reducir los niveles séricos de fosfato a niveles normales. Recientes avances en nuestra compresión de los mecanismos que subyacen a la homeostasis del fósforo sugieren que el transporte gastrointestinal del fósforo podría ser un objetivo. Recientemente se han desarrollado inhibidores de los cotransportadores sodio fosfato del intestino y se ha revalorizado el uso de la nicotinamida, en su formulación de liberación prolongada, que también actuaria por ese mecanismo. También se han drogas como el tenapanor, que inhibiendo el intercambiador sodio/hidrogeno isoforma 3 del enterocito, disminuyen la absorción paracelular de fósforo.

ABSTRACT Management of hyperphosphatemia in patients with chronic renal failure on dialysis remains challenging. Despite using a multifaceted approach that includes dietary restriction, phosphorus removal by dialysis, and phosphate binders, these multiple strategies fail to reduce phosphorus levels by more than 2 mg/dL. Phosphorus control in dialysis patients is essential due to the monotonic relationship between serum phosphate levels and increased cardiovascular risk. Therefore, there is a need to explore new strategies to reduce serum phosphate levels to normal levels. Recent advances in understanding the mechanisms underlying phosphorus homeostasis suggest that the gastrointestinal transport of phosphorus could be a target. Inhibitors of intestinal sodium phosphate cotransporters recently developed, and using of nicotinamide, in its prolonged release formulation, which would also act by this mechanism, has been revalued. There have also been drugs such as tenapanor, which, by inhibiting the isoform three sodium/hydrogen exchanger of the enterocyte, decreases the paracellular absorption of phosphorus.

Role of prolyl hydroxylase/HIF-1 signaling in vascular calcification.

Morbidity and mortality of chronic kidney disease (CKD) patients are largely associated with vascular calcification, an actively regulated process in which vascular smooth muscle cells (VSMCs) change into cells similar to osteocytes/chondrocytes, known as trans-differentiation. Cellular and systemic response to low oxygen (hypoxia) is regulated by the prolyl hydroxylase/hypoxia-inducible factor (HIF)-1 pathway. Recent studies highlighted that hypoxia-mediated activation of HIF-1 induces trans-differentiation of VSMCs into bone-forming type through an increase in osteo-/chondrogenic genes. Inhibition of the HIF-1 pathway abolished osteochondrogenic differentiation of VSMCs. Hypoxia strongly enhanced elevated phosphate-induced VSMC osteogenic trans-differentiation and calcification. HIF-1 was shown to be essential for phosphate enhanced VSMC calcification. O2-dependent degradation HIF-1 is triggered by the prolyl hydroxylase domain proteins (PHD). Prolyl hydroxylase inhibitors, daprodustat and roxadustat, increase high phosphate-induced VC in VSMCs, stabilizing HIF-1α and activating the HIF-1 pathway in these cells. Whether the use of these PHD inhibitors to treat anemia in CKD patients will favor the development and progression of vascular calcification remains to be explored.

Echocardiogram in Critically ill Patients with COVID-19: ECOVID Study

Abstract Background Literature is scarce on echocardiographic characteristics of COVID-19 patients admitted to the intensive care unit (ICU). Objectives To describe echocardiographic characteristics of ICU COVID-19 patients and associate them with clinical signals/symptoms, laboratory findings and outcomes. Methods Patients with RT-PCR-confirmed COVID-19, admitted to the ICU, who underwent echocardiography were included. Clinical characteristics associated with an abnormal echocardiogram (systolic ventricular dysfunction of any degree — left and/or right ventricle — and/or high filling pressures and/or moderate to severe pericardial effusion) were analyzed. Groups were compared using the Student's t-test, chi-square, and logistic regression. A p < 0.05 was considered statistically significant. Results A total of 140 patients met inclusion criteria, and 74 (52.9%) had an abnormal echocardiogram. A low number of left and right ventricular systolic dysfunction was observed, and 35% of the population had a normal diastolic function. In the univariate analysis, characteristics associated with abnormal echocardiogram were age, chronic kidney disease, elevated troponin, previous heart failure, and simplified acute physiology score 3 (SAPS 3). In the regression model, troponin and SAPS3 score were independent markers of abnormal echocardiogram. An abnormal echocardiogram was associated with a higher prevalence of in-hospital death (RR 2.10; 95% CI 1.04-4.24) and orotracheal intubation (RR 2.3; 95% CI 1.14-4.78). Conclusions COVID-19 has little effect on ventricular function, but it is common to find increased filling pressures. Elevated serum troponin level and SAPS3 score were the independent markers of an abnormal echocardiogram. In addition, the prevalence of in-hospital death and need for mechanical ventilation were higher in patients with abnormal echocardiogram.

New Complex of Cryptic Species Discovered in Genus Biblis (Papilionoidea: Nymphalidae: Biblidinae) in Mexico.

Our research focuses on demonstrating the existence of cryptic species named under Biblis aganisa Boisduval. We used COI sequences to delimit Biblis species for Mexico using species delimitation analyses and examined phylogenetic relationships with sequences from Mexico, Costa Rica, Argentina, USA, and Guana Island using a Bayesian inference tree. We performed a discriminant analysis with quantitative traits using female and male wing and genitalia, and a tree of maximum parsimony based on 39 qualitative characters of wings, head, and male genitalia. The results were congruent in the three analyses. Three groups were formed based on DNA, ECO 01 + DHJ02, ECO 02 + DHJ01, and ECO 03. The characters that contributed over 50% separation were for wings: wing length, anal margin length, and distance from the band to the outer margin; for male genitalia, angle of the integument, uncus, and the length of the hypandrium, while for females, it was the angle of the anteapophysis and the length of the abdomen. For the analysis of qualitative characters, a tree of maximum parsimony was obtained where 20 characters were informative. We confirmed the existence of three cryptic Biblis species in Mexico, two not yet described, and one corresponding to B. aganisa (ECO 02), which is sympatric in Oaxaca and Sinaloa (ECO 03) and in the Yucatan Peninsula (ECO 01).

Role of claudins in idiopathic hypercalciuria and renal lithiasis.

Paracellular transport in the kidney is mediated by a family of proteins located in the tight junctions called claudins which confers its ionic selectivity. Claudin-2 is highly expressed in the proximal tubule and descending limb of Henle and mediate paracellular reabsorption of sodium and calcium cations. In the thick ascending limb of Henle (TALH) calcium is reabsorbed by a paracellular channel formed by Claudin-16 and-19. Claudin-16 mediates cationic permeability while Claudin-19 increases the cationic selectivity of Claudin-16 by blocking anionic permeability. On the other hand, Claudin 14, that is also located in TALH, inhibits the paracellular permeability of Claudin-16 to calcium. Recent wide genomic association analysis studies have detected four common synonymous variants (genetic polymorphisms of a single nucleotide, SNPs) at the locus of Claudin-14 gene that were significantly associated with the presence of renal lithiasis. Another study of wide genomic association and nephrolithiasis was carried out in the general population but including chromosome X, where claudin-2 gene is located. They detected nine SNPs that had a significant association with renal lithiasis risk. A greater knowledge of the paracellular pathway controlled by claudins and its regulation will allow us to develop future new treatments for idiopathic hypercalciuria and renal lithiasis.

Hyponatremia, Inflammation at Admission, and Mortality in Hospitalized COVID-19 Patients: A Prospective Cohort Study.

Background: Systemic inflammation has been associated with severe coronavirus disease 2019 (COVID-19) disease and mortality. Hyponatremia can result from inflammation due to non-osmotic stimuli for vasopressin production. Methods: We prospectively studied 799 patients hospitalized with COVID-19 between March 7 and November 7, 2020, at Hospital Posadas in Buenos Aires, Argentina in order to evaluate the association between hyponatremia, inflammation, and its impact on clinical outcomes. Admission biochemistries, high-sensitivity C-reactive protein (hsCRP), ferritin, patient demographics, and outcome data were recorded. Outcomes (within 30 days after symptoms) evaluated included ICU admission, mechanical ventilation, dialysis-requiring acute kidney injury (AKI), and in-hospital mortality. Length of hospital stay (in days) were evaluated using comprehensive data from the EHR. Results: Hyponatremia (median Na = 133 mmol/L) was present on admission in 366 (45.8%). Hyponatremic patients had higher hsCRP (median 10.3 [IR 4.8-18.4] mg/dl vs. 6.6 [IR 1.6-14.0] mg/dl, p < 0.01) and ferritin levels (median 649 [IQR 492-1,168] ng/dl vs. 393 [IQR 156-1,440] ng/dl, p = 0.02) than normonatremic patients. Hyponatremia was associated with higher odds of an abnormal hsCRP (unadjusted OR 5.03, 95%CI: 2.52-10.03), and remained significant after adjustment for potential confounders (adjusted OR 4.70 [95%CI: 2.33-9.49], p < 0.01). Hyponatremic patients had increased mortality on unadjusted (HR 3.05, 95%CI: 2.14-4.34) and adjusted (HR 2.76, 95%CI:1.88-4.06) in Cox proportional hazard models. Crude 30-day survival was lower for patients with hyponatremia at admission (mean [SD] survival 22.1 [0.70] days) compared with patients who were normonatremic (mean [SD] survival 27.2 [0.40] days, p < 0.01). Conclusion: Mild hyponatremia on admission is common, is associated with systemic inflammation and is an independent risk factor for hospital mortality. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT04493268.

An intensive follow-up in subjects with cardiometabolic high-risk.

BACKGROUND AND AIM: Addressing chronic problems requires a model of care that promotes self-management of the disease and facilitates adherence to treatment. This project was designed to enhance patient's clinical and functional outcomes through a Comprehensive Model to be implemented in our health system and to evaluate the results. METHODS AND RESULTS: Different population stratification tools were tested and designed to classify subjects according to different variables. We have developed a program to detect and screen cardiometabolic risk by integrating most of the Chronic Care Model recommendations through in-house developed management software (MoviHealth®). From the results, 1317 subjects were evaluated (27% of the whole population) during the first year of follow-up which significantly improved for all variables along the follow-up period. The blood pressure of the hypertensive population in 2010 and 2015 showed the importance of enrollment of subjects and the optimization of the blood pressure control. The result of HbA1c observed in 2010 decreased progressively to 7.1 ± 1.4% in 2015, and dyslipidemia levels improved gradually. The number of cardiovascular events requiring hospitalization decreased significantly (48%), from 1.9 events per 100 subjects in 2011 to 0.98 in 2015. CONCLUSION: Our program has combined strategies for the prevention and control of non-communicable diseases, incorporating interventions to control risk factors and to reduce morbidity and mortality. It also had improvements in life quality, accessibility to health-care services, and the promotion of self-care.

Sarcopenia in hemodialysis patients from Buenos Aires, Argentina.

OBJECTIVES: Sarcopenia is the loss of skeletal muscle mass and function that occurs with aging that can lead to greater morbidity and mortality. Chronic kidney disease and hemodialysis (HD) favors the development of sarcopenia. We studied the prevalence of sarcopenia and its components using European Working Group on Sarcopenia in Elderly People 2 proposed criteria and risk factors for its development in HD patients. METHODS: In 100 adult HD patients, we evaluated: hand grip strength (HGS), muscle mass by dual energy X-ray absorptiometry and physical performance (gait-speed and sit-stand test). RESULTS: Sixty patients were male and 40 were female; mean age 55.6 years. Prevalence of sarcopenia was 16% (11.1% in males and 25% in females; P = 0.05); 7% had severe sarcopenia. Prevalence of low HGS was 33% in males and 28% in females; low muscle mass was 30% in males but 70% in females and low physical performance 23% in males and 45% in females. Falls were reported by 23 patients. Patients with lower HGS had a higher prevalence of falls in the last year (40% two or more falls; P = 0.03). Only females with sarcopenia had lower bone mineral content. Neither age, body mass index, time on dialysis, or prevalence of diabetes predicted sarcopenia. CONCLUSIONS: A significant proportion of dialysis patients had sarcopenia, more frequent in females. Low HGS was associated with a higher prevalence of falls. Only females with sarcopenia had lower bone mineral content.

Sarcopenia in hemodialysis patients from Buenos Aires, Argentina

Objectives@#Sarcopenia is the loss of skeletal muscle mass and function that occurs with aging that can lead to greater morbidity and mortality. Chronic kidney disease and hemodialysis (HD) favors the development of sarcopenia. We studied the prevalence of sarcopenia and its components using European Working Group on Sarcopenia in Elderly People 2 proposed criteria and risk factors for its development in HD patients. @*Methods@#In 100 adult HD patients, we evaluated: hand grip strength (HGS), muscle mass by dual energy X-ray absorptiometry and physical performance (gait-speed and sit-stand test). @*Results@#Sixty patients were male and 40 were female; mean age 55.6 years. Prevalence of sarcopenia was 16% (11.1% in males and 25% in females; P ¼ 0.05); 7% had severe sarcopenia. Prevalence of low HGS was 33% in males and 28% in females; low muscle mass was 30% in males but 70% in females and low physical performance 23% in males and 45% in females. Falls were reported by 23 patients. Patients with lower HGS had a higher prevalence of falls in the last year (40% two or more falls; P ¼ 0.03). Only females with sarcopenia had lower bone mineral content. Neither age, body mass index, time on dialysis, or prevalence of diabetes predicted sarcopenia. @*Conclusions@#A significant proportion of dialysis patients had sarcopenia, more frequent in females. Low HGS was associated with a higher prevalence of falls. Only females with sarcopenia had lower bone mineral content.