Vascular calcification in peritoneal dialysis patients and its association with bone-derived molecules and bone histomorphometry / Calcificación vascular en pacientes en diálisis peritoneal y su asociación con moléculas derivadas de hueso e histomorfometría ósea

Introduction: Data regarding vascular calcification (VC) in contemporary peritoneal dialysis (PD) patients is scarce. Bone–vascular axis has been demonstrated in hemodialysis (HD). However, studies showing the link between bone disease and VC in PD patients are lacking. The role of sclerostin, dickkopf-related protein 1 (DKK-1), receptor activator for nuclear factor kB ligand and osteoprotegerin (OPG) in VC in PD remains to clarify. Materials and methods: Bone biopsy was performed in 47 prevalent PD patients with histomorphometric analysis. Patients were submitted to pelvis and hands X-ray to evaluate VC using the Adragão score (AS). Relevant clinical and biochemical data was collected. Results: Thirteen patients (27.7%) had positive AS (AS≥1). Patients with VC were significantly older (58.9 vs. 50.4 years, p=0.011), had a lower dialysis dose (KT/V 2.0 vs. 2.4, p=0.025) and a higher glycosylated hemoglobin (7.2 vs. 5.4%, p=0.001). There was not any laboratorial parameter of mineral and bone disease used in clinical practice different between patients with or without VC. All diabetic patients had VC but only 8.1% of non-diabetic had VC (p<0.001). Patients with VC showed significantly higher erythrocyte sedimentation rate (ESR) (91.1 vs. 60.0mm/h, p=0.001), sclerostin (2250.0 vs. 1745.8pg/mL, p=0.035), DKK-1 (1451.6 vs. 1042.9pg/mL, p=0.041) and OPG levels (2904.9 vs. 1518.2pg/mL, p=0.002). On multivariate analysis, only ESR remained statistically significant (OR 1.07; 95% CI 1.01–1.14; p=0.022). Bone histomorphometric findings were not different in patients with VC. There was no correlation between bone formation rate and AS (r=−0.039; p=0.796). Conclusion: The presence of VC was not associated with bone turnover and volume evaluated by bone histomorphometry. Inflammation and diabetes seem to play a more relevant role in VC in PD. (AU)

Introducción Los datos sobre calcificación vascular (CV) en pacientes contemporáneos en diálisis peritoneal (DP) son escasos. En pacientes en hemodiálisis, se ha demostrado la existencia de una conexión entre hueso y sistema vascular; sin embargo, faltan estudios que muestren el vínculo entre la enfermedad ósea y la CV en pacientes en DP. Si la esclerostina, la proteína relacionada con Dickkopf 1 (DKK-1), el ligando del receptor activador para el factor nuclear κB (RANKL) y la osteoprotegerina (OPG) tienen un papel en la CV en pacientes en DP aún no está claro. Materiales y métodos Se realizó biopsia ósea en 47 pacientes prevalentes en DP y se analizó mediante histomorfometría. También se tomaron radiografías de pelvis y manos a los pacientes para evaluar la CV mediante el Índice de Adragão (IA). Además, se analizaron datos clínicos y bioquímicos relevantes. Resultados: Trece pacientes (27,7%) tuvieron IA positivo (IA ≥ 1). Los pacientes con CV eran significativamente mayores (58,9 vs 50,4 años, p=0,011) tenían menor dosis de diálisis (KT/V 2,0 vs 2,4, p=0,025) y niveles más elevados de hemoglobina glicosilada (7,2 vs 5,4%, p=0,001). No hubo ningún parámetro de laboratorio de enfermedad mineral y ósea utilizado en la práctica clínica diferente entre pacientes con o sin CV. Todos los pacientes diabéticos mostraron CV, sin embargo, solo el 8,1% de los no diabéticos tenían CV (p <0,001). Además, los pacientes con CV mostraron una velocidad de sedimentación globular más elevada (VSG) (91,1 vs. 60,0mm/h, p=0,001) y mayores concentraciones séricas de esclerostina (2.250,0 vs. 1.745,8 pg/ml, p=0,035), DKK-1 (1451,6 vs 1042,9 pg/ml, p=0,041) y OPG (2.904,9 vs. 1.518,2 pg/ml, p=0,002). En el análisis multivariante, solo la VSG fue estadísticamente significativa (OR 1,07; IC del 95%: 1,01-1,14; p=0,022)... (AU)

Qualidade de vida na pessoa com insuficiência renal crónica em programa regular de hemodiálise / Quality of life of people with chronic kidney disease undergoing regular hemodialysis / Calidad de vida en personas con insuficiencia renal crónica en programa regular de hemodiálisis

Resumo Enquadramento: Ao longo da última década observou-se um aumento no número de pessoas que sofrem de doença renal crónica em programa de hemodiálise, imergindo a necessidade de aferir a qualidade de vida destes doentes. Objetivo: Avaliar a qualidade de vida dos doentes renais crónicos em programa regular de hemodiálise. Metodologia: Estudo de abordagem quantitativa, descritivo transversal utilizando o KDQOL-SF. Amostra não probabilística de conveniência, com 268 doentes em programa regular de hemodiálise com idades entre 25 e 90 anos, em sete clínicas de Portugal. Resultados: O encorajamento do pessoal da diálise (82,46) e o apoio social (77,49) foram as dimensões com melhores scores. Os indivíduos do sexo masculino apresentam melhores pontuações na qualidade de vida, nas dimensões: função física (p = 0,023), dor (p = 0,011) e bem-estar emocional (p = 0,020). A análise do SF-36 demostrou que todos os domínios apresentavam pior score e com significado estatístico quando comparados com a população portuguesa. Conclusão: É fundamental arranjar estratégias que possam melhorar qualidade de vida da pessoa com insuficiência renal.

Abstract Background: The number of people suffering from chronic kidney disease undergoing hemodialysis in Portugal has been increasing over the last decade, highlighting the need to assess the quality of life of these patients. Objective: To assess the quality of life of patients with chronic kidney disease undergoing regular hemodialysis. Methodology: A quantitative, cross-sectional descriptive study was conducted using the Kidney Disease Quality of Life Instrument (KDQOL-SF Version 1.3). The non-probability convenience sample consists of 268 patients aged 25 to 90 years undergoing regular hemodialysis in seven clinics in Portugal. Results: The Dialysis staff encouragement (82.46) and social support (77.49) dimensions had the highest scores. Male patients had higher scores in the physical functioning (p = 0.023),bodily pain (p = 0.011), and emotional well-being (p = 0.020) dimensions. This sample had statistically significant lower scores in all domains of the 36-Item Health Survey (SF-36) than the general Portuguese population. Conclusion: It is essential to develop strategies to improve the quality of life of patients with chronic kidney disease.

Resumen Marco contextual: En la última década ha aumentado el número de personas con insuficiencia renal crónica que se someten a un programa de hemodiálisis, lo que plantea la necesidad de evaluar la calidad de vida de estos pacientes. Objetivo: Evaluar la calidad de vida de los pacientes renales crónicos en programa regular de hemodiálisis. Metodología: Se trata de un estudio cuantitativo, transversal y descriptivo que utiliza el KDQOL-SF. Muestra de conveniencia no probabilística, con 268 pacientes en programa regular de hemodiálisis con edades comprendidas entre los 25 y los 90 años, en siete clínicas de Portugal. Resultados: La motivación del personal de diálisis (82,46) y el apoyo social (77,49) fueron las dimensiones con las mejores puntuaciones. Los individuos del sexo masculino presentan mejores puntuaciones en calidad de vida, en las dimensiones: función física (p = 0,023), dolor (p = 0,011) y bienestar emocional (p = 0,020). El análisis del SF-36 demostró que todos los dominios presentaban una puntuación peor y con significación estadística en comparación con la población portuguesa. Conclusión: Es esencial idear estrategias que puedan mejorar la calidad de vida de las personas con insuficiencia renal.

Open-source tool for real-time and automated analysis of droplet-based microfluidic.

Droplet-based microfluidic technology is a powerful tool for generating large numbers of monodispersed nanoliter-sized droplets for ultra-high throughput screening of molecules or single cells. Yet further progress in the development of methods for the real-time detection and measurement of passing droplets is needed for achieving fully automated systems and ultimately scalability. Existing droplet monitoring technologies are either difficult to implement by non-experts or require complex experimentation setups. Moreover, commercially available monitoring equipment is expensive and therefore limited to a few laboratories worldwide. In this work, we validated for the first time an easy-to-use, open-source Bonsai visual programming language to accurately measure in real-time droplets generated in a microfluidic device. With this method, droplets are found and characterized from bright-field images with high processing speed. We used off-the-shelf components to achieve an optical system that allows sensitive image-based, label-free, and cost-effective monitoring. As a test of its use we present the results, in terms of droplet radius, circulation speed and production frequency, of our method and compared its performance with that of the widely-used ImageJ software. Moreover, we show that similar results are obtained regardless of the degree of expertise. Finally, our goal is to provide a robust, simple to integrate, and user-friendly tool for monitoring droplets, capable of helping researchers to get started in the laboratory immediately, even without programming experience, enabling analysis and reporting of droplet data in real-time and closed-loop experiments.

Vascular calcification in peritoneal dialysis patients and its association with bone-derived molecules and bone histomorphometry.

INTRODUCTION: Data regarding vascular calcification (VC) in contemporary peritoneal dialysis (PD) patients is scarce. Bone-vascular axis has been demonstrated in hemodialysis (HD). However, studies showing the link between bone disease and VC in PD patients are lacking. The role of sclerostin, dickkopf-related protein 1 (DKK-1), receptor activator for nuclear factor kB ligand and osteoprotegerin (OPG) in VC in PD remains to clarify. MATERIALS AND METHODS: Bone biopsy was performed in 47 prevalent PD patients with histomorphometric analysis. Patients were submitted to pelvis and hands X-ray to evaluate VC using the Adragão score (AS). Relevant clinical and biochemical data was collected. RESULTS: Thirteen patients (27.7%) had positive AS (AS≥1). Patients with VC were significantly older (58.9 vs. 50.4 years, p=0.011), had a lower dialysis dose (KT/V 2.0 vs. 2.4, p=0.025) and a higher glycosylated hemoglobin (7.2 vs. 5.4%, p=0.001). There was not any laboratorial parameter of mineral and bone disease used in clinical practice different between patients with or without VC. All diabetic patients had VC but only 8.1% of non-diabetic had VC (p<0.001). Patients with VC showed significantly higher erythrocyte sedimentation rate (ESR) (91.1 vs. 60.0mm/h, p=0.001), sclerostin (2250.0 vs. 1745.8pg/mL, p=0.035), DKK-1 (1451.6 vs. 1042.9pg/mL, p=0.041) and OPG levels (2904.9 vs. 1518.2pg/mL, p=0.002). On multivariate analysis, only ESR remained statistically significant (OR 1.07; 95% CI 1.01-1.14; p=0.022). Bone histomorphometric findings were not different in patients with VC. There was no correlation between bone formation rate and AS (r=-0.039; p=0.796). CONCLUSION: The presence of VC was not associated with bone turnover and volume evaluated by bone histomorphometry. Inflammation and diabetes seem to play a more relevant role in VC in PD.

Etelcalcetide controls secondary hyperparathyroidism and raises sclerostin levels in hemodialysis patients previously uncontrolled with cinacalcet / Etelcalcetida controla el hiperparatiroidismo secundario y eleva los niveles de esclerostina en pacientes en hemodiálisis previamente no controlados con cinacalcet

Introduction: There is scarce clinical experience with etelcalcetide in patients with secondary hyperparathyroidism uncontrolled with cinacalcet. The effect of etelcalcetide on serum sclerostin levels remains to be clarified. Materials and methods: Prospective cohort study in prevalent hemodialysis patients with uncontrolled sHPT under cinacalcet for at least 3 months, mean parathyroid hormone (PTH)>800pg/mL and calcium (Ca)>8.3mg/dL. Etelcalcetide 5mg IV/HD was initiated after cinacalcet washout. Levels of PTH, Ca, and phosphorus (Pi) followed monthly for 6 months. Plasma sclerostin levels measured before etelcalcetide treatment and after 6 months. Results: Thirty-four patients were enrolled, 19 (55.9%) male gender. Mean age 60.7 (± 12.3) years; median time on HD 82.5 (7–296) months and median cinacalcet dose was 180mg/week (Interquartile Range: 180–270). Serum Ca, Pi and PTH levels showed a significant reduction after etelcalcetide treatment from 8.8mg/dL, 5.4mg/dL and 1005pg/mL to 8.1mg/dL (p=0.08), 4.9mg/dL (p=0.01) and 702pg/mL (p<0.001), respectively. Median etelcalcetide dose remained at 5mg/HD. Plasma sclerostin concentration increased from 35.66pmol/L (IQR11.94–54.58) to 71.05pmol/L (IQR54.43–84.91) (p<0.0001). Conclusion: Etelcalcetide improved sHPT control in this group of patients, previously under cinacalcet treatment, and significantly increased plasma sclerostin concentration. The impact of etelcalcetide treatment on sclerostin levels is a novel finding. (AU)

Introducción: Existe escasa experiencia clínica sobre el uso de etelcalcetida en pacientes con hiperparatiroidismo secundario no controlado con cinacalcet. Asimismo, el efecto de la etelcalcetida sobre los niveles de esclerostina aún no ha sido aclarado. Materiales y métodos: Realizamos un estudio de cohorte prospectivo en pacientes en hemodiálisis (HD) con hiperparatiroidismo secundario no controlado con cinacalcet durante al menos 3 meses, hormona paratiroidea media> 800 pg/ml y calcio (Ca)> 8,3mg/dl. Tras un periodo de lavado, se inició administración intravenosa de etelcalcetida 5mg/HD y se realizó un seguimiento mensual de los niveles de hormona paratiroidea, Ca y fósforo (Pi) durante 6 meses. Además, los niveles de esclerostina plasmática fueron medidos antes del tratamiento con etelcalcetida y después de 6 meses. Resultados: Se incluyeron 34 pacientes, 19 (55,9%) de sexo masculino. Edad media 60,7±12,3 años; la mediana de tiempo en HD fue 82,5 (7-296) meses y la mediana de la dosis de cinacalcet fue de 180mg/semana (rango intercuartílico 180-270). Los niveles séricos de Ca, Pi y hormona paratiroidea mostraron una reducción significativa después del tratamiento con etelcalcetida desde 8,8mg/dl, 5,4mg/dl y 1005 pg/ml hasta 8,1mg/dl (p=0,08), 4,9mg/dl (p=0,01) y 702 pg/mL (p<0,001) respectivamente. La dosis media de etelcalcetida se mantuvo en 5mg/HD. La concentración de esclerostina plasmática aumentó de 35,66pmol/L (rango intercuartílico 11,94-54,58) a 71,05pmol/L (rango intercuartílico 54,43-84,91; p <0,0001). Conclusión: En este grupo de pacientes previamente en tratamiento con cinacalcet, la etelcalcetida mejoró el control de hiperparatiroidismo secundario y resultó en un aumento de la concentración plasmática de esclerostina. El efecto del tratamiento con etelcalcetida sobre los niveles de esclerostina es un hallazgo novedoso. (AU)

Lessons from Four Decades of Systemic Amyloidosis with Renal Involvement.

BACKGROUND: Apart from ATTR amyloidosis, the epidemiology and outcomes of the most common subtypes of systemic amyloidosis in Portugal remain primarily unknown. METHODS: This retrospective cohort study evaluated patients with renal biopsy-proven amyloidosis, diagnosed from January 1978 to December 2019. Follow-up started at kidney disease presentation and ended at death or August 2020. Clinical presentation, survival, and prognostic factors were analysed. RESULTS: Of 123 patients with amyloid nephropathy, 111 had definite amyloid typing and were analysed. AA amyloidosis was the most frequent type (56.1%) and was related mainly to chronic infection (47.8%) and chronic inflammatory arthritis (29.0%). AL amyloidosis was present in 25.2% of patients and hereditary forms in 6.5% (4.1% AFibE526V, 2.4% ATTRV30M). During follow-up, 73.9% of AA and 54.8% of AL patients progressed to end-stage renal disease, and 79.7% of AA and 77.4% of AL died; median overall survival was 66.0 (95% CI, 33.0-99.0) and 18.0 (95% CI, 9.3-26.7) months (p = 0.025), respectively. There were no significant differences in renal outcome and survival on dialysis between these two types. In multivariate analysis, cardiac involvement at presentation (HR 6.26 [95% CI, 2.89-13.56]) and estimated glomerular filtration rate <30 mL/min/1.73 m2 (HR 2.05 [95% CI, 1.06-3.99]) independently influenced AA and AL amyloidosis survival. Cardiac involvement at presentation was an independent predictor of death (HR 9.65 [95% CI, 2.91-31.95]) and early mortality in AL amyloidosis. CONCLUSIONS: In Portugal, AA amyloidosis and related chronic infections are still relevant. Regarding AL amyloidosis, the low incidence and advanced disease at presentation result from missed and erroneous diagnoses, leading to delayed referrals and poor outcomes in these patients.

Etelcalcetide controls secondary hyperparathyroidism and raises sclerostin levels in hemodialysis patients previously uncontrolled with cinacalcet.

INTRODUCTION: There is scarce clinical experience with etelcalcetide in patients with secondary hyperparathyroidism uncontrolled with cinacalcet. The effect of etelcalcetide on serum sclerostin levels remains to be clarified. MATERIALS AND METHODS: Prospective cohort study in prevalent hemodialysis patients with uncontrolled sHPT under cinacalcet for at least 3 months, mean parathyroid hormone (PTH)>800pg/mL and calcium (Ca)>8.3mg/dL. Etelcalcetide 5mg IV/HD was initiated after cinacalcet washout. Levels of PTH, Ca, and phosphorus (Pi) followed monthly for 6 months. Plasma sclerostin levels measured before etelcalcetide treatment and after 6 months. RESULTS: Thirty-four patients were enrolled, 19 (55.9%) male gender. Mean age 60.7 (± 12.3) years; median time on HD 82.5 (7-296) months and median cinacalcet dose was 180mg/week (Interquartile Range: 180-270). Serum Ca, Pi and PTH levels showed a significant reduction after etelcalcetide treatment from 8.8mg/dL, 5.4mg/dL and 1005pg/mL to 8.1mg/dL (p=0.08), 4.9mg/dL (p=0.01) and 702pg/mL (p<0.001), respectively. Median etelcalcetide dose remained at 5mg/HD. Plasma sclerostin concentration increased from 35.66pmol/L (IQR11.94-54.58) to 71.05pmol/L (IQR54.43-84.91) (p<0.0001). CONCLUSION: Etelcalcetide improved sHPT control in this group of patients, previously under cinacalcet treatment, and significantly increased plasma sclerostin concentration. The impact of etelcalcetide treatment on sclerostin levels is a novel finding.

Bodas de plata: 25 años de la primera demostración del efecto directo del fósforo en la célula paratiroidea / Silver jubilee: 25 years of the first demonstration of the direct effect of phosphate on the parathyroid cell

Aunque el fósforo es un elemento indispensable para la vida, en la naturaleza no se encuentra en estado nativo sino combinado en forma de fosfatos inorgánicos (PO43−), con niveles plasmáticos estrechamente regulados que se asocian a efectos deletéreos y mortalidad cuando estos se encuentran fuera de la normalidad. El interés creciente sobre el acúmulo de PO43− en la fisiopatología humana se originó en el papel que se le atribuyó en la patogenia del hiperparatiroidismo secundario a la enfermedad renal crónica. En este artículo revisamos los mecanismos por los cuales se justificaba dicho efecto y conmemoramos la importante contribución de un grupo español liderado por el Dr. M. Rodríguez, ahora hace justo 25 años, cuando demostraron por primera vez el efecto directo del PO43− sobre la regulación de la síntesis y secreción de hormona paratiroidea (manteniendo la integridad estructural de las glándulas paratiroides en su nuevo modelo experimental. Además de demostrar la importancia del ácido araquidónico (AA) y la vía de la fosfolipasa A2-AA como mediadora de respuestas en la glándula paratiroidea, estos hallazgos fueron predecesores de la reciente descripción del importante papel del PO43− sobre la actividad del receptor-sensor de calcio y alimentaron asimismo diversas líneas de investigación sobre la importancia de la sobrecarga de PO43−, no solo en la fisiopatología del hiperparatiroidismo secundario sino también en su papel patogénico sistémico. (AU)

Although phosphorus is an essential element for life, it is not found in nature in its native state but rather combined in the form of inorganic phosphates (PO43−), with tightly regulated plasma levels that are associated with deleterious effects and mortality when these are out of bounds. The growing interest in the accumulation of PO43− in human pathophysiology originated in its attributed role in the pathogenesis of secondary hyperparathyroidism in chronic kidney disease. In this article, we review the mechanisms by which this effect was justified and we commemorate the important contribution of a Spanish group led by Dr. M. Rodríguez, just 25 years ago, when they first demonstrated the direct effect of PO43− on the regulation of the synthesis and secretion of parathyroid hormone by maintaining the structural integrity of the parathyroid glands in their original experimental model. In addition to demonstrating the importance of arachidonic acid (AA) and the phospholipase A2-AA pathway as a mediator of parathyroid gland response, these findings were predecessors of the recent description of the important role of PO43− on the activity of the calcium sensor-receptor, and also fueled various lines of research on the importance of PO43− overload not only for the pathophysiology of secondary hyperparathyroidism but also of its systemic pathogenic role. (AU)

Shepherd: accurate clustering for correcting DNA barcode errors.

MOTIVATION: DNA barcodes are short, random nucleotide sequences introduced into cell populations to track the relative counts of hundreds of thousands of individual lineages over time. Lineage tracking is widely applied, e.g. to understand evolutionary dynamics in microbial populations and the progression of breast cancer in humans. Barcode sequences are unknown upon insertion and must be identified using next-generation sequencing technology, which is error prone. In this study, we frame the barcode error correction task as a clustering problem with the aim to identify true barcode sequences from noisy sequencing data. We present Shepherd, a novel clustering method that is based on an indexing system of barcode sequences using k-mers, and a Bayesian statistical test incorporating a substitution error rate to distinguish true from error sequences. RESULTS: When benchmarking with synthetic data, Shepherd provides barcode count estimates that are significantly more accurate than state-of-the-art methods, producing 10-150 times fewer spurious lineages. For empirical data, Shepherd produces results that are consistent with the improvements seen on synthetic data. These improvements enable higher resolution lineage tracking and more accurate estimates of biologically relevant quantities, e.g. the detection of small effect mutations. AVAILABILITY AND IMPLEMENTATION: A Python implementation of Shepherd is freely available at: https://www.github.com/Nik-Tavakolian/Shepherd. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Evaluation of Renal Osteodystrophy and Serum Bone-Related Biomarkers in a Peritoneal Dialysis Population.

The spectrum of renal osteodystrophy (ROD) in peritoneal dialysis (PD) patients remains to be clarified. Ideal intact parathormone (iPTH) levels range is still not defined. The role of sclerostin, dickkopf-related protein 1, osteoprotegerin, and receptor activator for nuclear factor κB ligand for the diagnosis of ROD needs to be elucidated. In this cross-sectional study, tetracycline double-labeled bone biopsy was performed in 49 patients with histomorphometric analysis according Kidney Disease Improving Global Outcomes (KDIGO) guidelines. All patients were treated with biocompatible PD solutions, with calcium concentration of 1.25 mmol/L. Adynamic bone was the most frequent diagnosed pattern (42.9%) followed by hyperparathyroid-related bone disease (28.6%). Twenty-two percent of patients had normal bone. In patients with iPTH within the KDIGO recommended range for dialysis patients, adynamic bone was found in 59% of cases. Median (range) iPTH in patients with adynamic bone was 312 (60-631) pg/mL. Median (range) levels of sclerostin varied from 1511.64 (458.84-6387.70) pg/mL in patients with hyperparathyroid bone disease to 2433.1 (1049.59-11354.52) pg/mL in patients with adynamic bone. Sclerostin/iPTH ratio was the best marker of low turnover disease but iPTH performed best in the diagnosis of high turnover disease. Calcium mass transfer was positive in patients with low bone volume. Adynamic bone is the most frequent ROD pattern in contemporary PD. Our results suggest the need to review the iPTH target range for this population. The sclerostin/iPTH ratio showed improved performance compared to iPTH for the diagnosis of low turnover bone. © 2022 American Society for Bone and Mineral Research (ASBMR).

Evaluating Root Mechanosensing Response in Rice.

Unable to move, plants are physically restrained to the place where they grow. Remarkably, plants have developed a myriad of mechanisms to perceive the surrounding environment in order to maximize growth and survival. One of those mechanisms is the ability to perceive mechanical stimulus such as touch (thigmomorphogenesis), in order to adjust growth patterns (in different organs) to either attach to or surround an object. Roots are able to perceive several mechanical forces (e.g., gravity, touch). However, being the "hidden part" of a plant, it is difficult to assess their response to mechanical stimulation. In this chapter, our team presents a simple method to evaluate rice (Oryza sativa L.) root mechanosensing response that can be used to test different conditions (e.g., hormones) affecting rice root response to touch stimulus. This method is affordable to any lab and can be upgraded with a fully automated image recording system. We provide a detailed protocol with several notes for a more comprehensive application.

Effect of vitamin D sterols on bone histology in pre-dialysis patients: A prospective controlled study.

BACKGROUND: Abnormalities related to mineral and bone metabolism are a common finding in chronic kidney disease (CKD). Vitamin D compounds are often prescribed to CKD patients with the purpose to control secondary hyperparathyroidism and reduce the risk of high-turnover bone disease. However, data on the effect of vitamin D sterols on bone histology in non-dialysis CKD is limited. MATERIALS AND METHODS: A prospective controlled study was conducted on a cohort of 56 patients with CKD stages 3 and 4. 19 patients on calcitriol and 12 patients on cholecalciferol were compared to a group of 25 age- and sex-matched controls. Participants underwent a tetracycline double-labelled transiliac bone biopsy before starting therapy and again 12 months later. Changes from baseline in circulating biomarkers and bone histomorphometric parameters were analyzed. RESULTS: Low-turnover bone disease was the most common pattern of renal osteodystrophy on the initial biopsy. There was no difference in biochemical or histomorphometric values between the three study groups at baseline. Serum intact parathormone (iPTH) and bone formation rate decreased significantly in calcitriol-treated patients, with prevalence of low-turnover bone disease doubling from baseline. In contrast, no significant changes were noted in cholecalciferol-treated and control subjects. CONCLUSION: Calcitriol was effective in preventing secondary hyperparathyroidism and high-turnover bone disease. However, it was associated with an increased risk of developing or aggravating low-turnover bone disease. In the absence of a bone biopsy, calcitriol use in pre-dialysis CKD should be reserved for patients with a progressive rise in iPTH levels, in whom high-turnover bone disease is suspected.

Could Bone Biomarkers Predict Bone Turnover after Kidney Transplantation?-A Proof-of-Concept Study.

AIM: Bone disease after kidney transplant (KT) results from multiple factors, including previous bone and mineral metabolism disturbances and effects of transplant-related medications. New biomolecules have been recently associated with the development and progression of the chronic kidney disease-associated bone and mineral disorder (CKD-MBD). These include sclerostin and the soluble receptor activator of nuclear factor-kB ligand (sRANKL). METHODS: To better understand the role of biomarkers in post-transplant bone disease, this study was designed to prospectively evaluate and correlate results from the histomorphometric analysis of bone biopsies after KT with emerging serum biomarkers of the CKD-MBD: sclerostin, Dickkopf-related protein 1 (Dkk-1), sRANKL and osteo-protegerin (OPG). RESULTS: Our data shows a significant increase in plasma levels of bioactive sclerostin after KT accompanied by a significant reduction in plasma levels of Dkk-1, suggesting a promotion of the inhibition of bone formation by osteoblasts through the activation of these inhibitors of the Wnt signaling pathway. In addition, we found a significant increase in plasma levels of free sRANKL after KT accompanied by a significant reduction in plasma levels of its decoy receptor OPG, suggesting an enhanced bone resorption by osteoclasts mediated by this mechanism. CONCLUSIONS: Taken together, these results suggest that the loss of bone volume observed after KT could be explain mainly by the inhibition of bone formation mediated by sclerostin accompanied by an enhanced bone resorption mediated by sRANKL.

Silver jubilee: 25 years of the first demonstration of the direct effect of phosphate on the parathyroid cell.

Although phosphorus is an essential element for life, it is not found in nature in its native state but rather combined in the form of inorganic phosphates (PO43-), with tightly regulated plasma levels that are associated with deleterious effects and mortality when these are out of bounds. The growing interest in the accumulation of PO43- in human pathophysiology originated in its attributed role in the pathogenesis of secondary hyperparathyroidism (SHPT) in chronic kidney disease. In this article, we review the mechanisms by which this effect was justified and we commemorate the important contribution of a Spanish group led by Dr. M. Rodríguez, just 25 years ago, when they first demonstrated the direct effect of PO43- on the regulation of the synthesis and secretion of parathyroid hormone by maintaining the structural integrity of the parathyroid glands in their original experimental model. In addition to demonstrating the importance of arachidonic acid (AA) and the phospholipase A2-AA pathway as a mediator of parathyroid gland response, these findings were predecessors of the recent description of the important role of PO43- on the activity of the calcium sensor-receptor, and also fueled various lines of research on the importance of PO43- overload not only for the pathophysiology of SHPT but also in its systemic pathogenic role.

Saccharomyces yeast hybrids on the rise.

Saccharomyces hybrid yeasts are receiving increasing attention as a powerful model system to understand adaptation to environmental stress and speciation mechanisms, using experimental evolution and omics techniques. We compiled all genomic resources available from public repositories of the eight recognized Saccharomyces species and their interspecific hybrids. We present the newest numbers on genomes sequenced, assemblies, annotations, and sequencing runs, and an updated species phylogeny using orthogroup inference. While genomic resources are highly skewed towards Saccharomyces cerevisiae, there is a noticeable movement to use wild, recently discovered yeast species in recent years. To illustrate the degree and potential causes of reproductive isolation, we reanalyzed published data on hybrid spore viabilities across the entire genus and tested for the role of genetic, geographic, and ecological divergence within and between species (28 cross types and 371 independent crosses). Hybrid viability generally decreased with parental genetic distance likely due to antirecombination and negative epistasis, but notable exceptions emphasize the importance of strain-specific structural variation and ploidy differences. Surprisingly, the viability of crosses within species varied widely, from near reproductive isolation to near-perfect viability. Geographic and ecological origins of the parents predicted cross viability to an extent, but with certain caveats. Finally, we highlight publication trends in the field and point out areas of special interest, where hybrid yeasts are particularly promising for innovation through research and development, and experimental evolution and fermentation.

Sclerostin and DKK1 circulating levels associate with low bone turnover in patients with chronic kidney disease Stages 3 and 4.

BACKGROUND: Disordered mineral and bone metabolism is a common complication of chronic kidney disease (CKD). Bone biopsy remains the gold standard tool for evaluating renal osteodystrophy (ROD), but it is an invasive procedure. Despite a growing interest in the ability of newer bone biomarkers to discriminate between different forms of ROD, data on pre-dialysis patients are scarce. METHODS: A cross-sectional study was conducted in a cohort of 56 patients with CKD Stages 3 and 4. Participants underwent a transiliac bone biopsy after a course of double tetracycline labelling. Circulating levels of Wnt signalling inhibitors sclerostin and Dickkopf-1 (DKK1), soluble receptor activator of nuclear factor-κB ligand (sRANKL) and osteoprotegerin were measured and correlated with histomorphometric analysis results. RESULTS: Most patients had abnormal bone histology and low-turnover bone disease was the predominant form of ROD. Characteristics associated with high bone turnover were worse renal function, lower serum calcium and higher intact parathyroid hormone and fibroblast growth factor-23 levels. Patients with low bone turnover, on the other hand, presented with higher sclerostin along with lower DKK1 and sRANKL levels. In the multivariable logistic regression analysis, sclerostin and DKK1 levels were independently associated with low-turnover bone disease. CONCLUSIONS: Our results suggest that circulating levels of Wnt signalling inhibitors sclerostin and DKK1 are predictive of low-turnover bone disease in patients not yet on dialysis. Further research is needed to assess the performance of these bone turnover biomarkers, compared with histomorphometric analysis, in the diagnosis and treatment monitoring of ROD.

Low bone turnover is associated with plain X-ray vascular calcification in predialysis patients.

BACKGROUND: Vascular calcification (VC) is a common finding in chronic kidney disease (CKD) patients and predicts subsequent cardiovascular morbidity and mortality in this population. Vascular calcification is linked to disordered mineral metabolism and has been associated with bone histomorphometry changes in CKD. However, data on predialysis patients is scarce. METHODS: A cross-sectional study was conducted on a cohort of 56 CKD patients not yet on dialysis, who underwent a transiliac bone biopsy for histomorphometric evaluation after double tetracycline labeling. Patients had no previous exposure to calcium salts, vitamin D agents, steroids or bisphosphonates. Vascular calcification was assessed at the time of biopsy, using Kauppila (plain X-ray of the lateral lumbar spine) and Adragão (plain X-ray of the pelvis and hands) scores. RESULTS: Vascular calcification was seen in two-thirds of the cohort. Subjects with VC were more likely to be male and have diabetes, and had significantly higher sclerostin and osteoprotegerin circulating levels than those without VC. The histomorphometric analysis showed that bone formation rate was significantly lower in VC compared to non-VC patients. In the multivariable logistic regression analysis, bone formation rate was independently associated with the presence of VC. CONCLUSIONS: Vascular calcification is highly prevalent in predialysis patients, especially in those with diabetes. The independent association between bone formation rate and VC provides evidence of an important interaction between bone and vessel in CKD. Our results suggest that low bone turnover is a non-traditional risk factor for cardiovascular disease in predialysis patients.

Improvements in six aspects of quality of care of incident hemodialysis patients - a real-world experience.

BACKGROUND: The transition from chronic kidney disease stage 5 to initiation of hemodialysis has gained increased attention in recent years as this period is one of high risk for patients with an annual mortality rate exceeding 20%. Morbidity and mortality in incident hemodialysis patients are partially attributed to failure to attain guideline-based targets. This study focuses on improvements in six aspects of quality of dialysis care (adequacy, anemia, nutrition, chronic kidney disease-mineral bone disorder (CKD-MBD), blood pressure and vascular access) aligning with KDIGO guidelines, during the first 6 months of hemodialysis. METHODS: We analyzed patient demographics, practice patterns and laboratory data in all 3 462 patients (mean age 65.9 years, 41% females) on hemodialysis (incident <90 days on hemodialysis, n=603, prevalent ≥90 days on hemodialysis, mean 55 months, n=2 859) from all 56 DaVita centers in Poland (51 centers) and Portugal (5 centers). 80% of patients had hemodialysis and 20% hemodiafiltration. Statistical analyses included unpaired and paired Students t-test, Chi-2 analyses, McNemar test and logistic regression analysis. RESULTS: Incident patients had lower Kt/V (1.4 vs 1.7, p<0.001), lower serum albumin (37 vs 40 g/l, p=0.001), lower Hb (9.9 vs 11.0 g/dl, p<0.001), lower TSAT (26 vs 31%, p<0.001), lower iPTH (372 vs 496 pg/ml, p<0.001), more often a central venous catheter (68 vs 26%, p<0.001), less often an AV fistula (34 vs 70 %, p<0.001) compared with all prevalent patients. Significantly more prevalent patients achieved international treatment targets. Improvements in quality of care was also analyzed in a subgroup of 258 incident patients who were followed prospectively for 6 months. We observed significant improvements in Kt/V (p<0.001), albumin (p<0.001), Hb (p<0.001) transferrin saturation (TSAT, p<0.001), iPTH (p=0.005) and an increased use of AV fistula (p<0.001). Furthermore, logistic regression analyses identified treatment time and TSAT as major factors influencing the attainment of adequacy and anemia treatment targets. CONCLUSION: This large real-world European multicenter analysis of representative incident hemodialysis patients indicates that the use of medical protocols and medical targets assures significant improvements in quality of care, which may correspond to better outcomes. A selection bias of survivors with less comorbidities in prevalent patients may have influenced the results.

Efficacy and safety of calcium carbonate in normophosphataemic patients with chronic kidney disease Stages 3 and 4.

BACKGROUND: Disordered bone and mineral metabolism are a common complication of chronic kidney disease (CKD). Phosphate binders are often prescribed in advanced CKD, when hyperphosphataemia develops. Little is known about the role of these drugs in earlier stages, when serum phosphorus levels are kept in the normal range by increased urinary excretion. METHODS: A retrospective, controlled observational study was conducted on a cohort of 78 pre-dialysis patients. Subjects had CKD Stage 3 or 4, normal serum phosphorus levels and increased urinary fractional excretion of phosphate. Thirty-eight patients receiving calcium carbonate for 24 months were compared with 40 patients under no phosphate binders, regarding mineral metabolism parameters and vascular calcification scores. RESULTS: Calcium carbonate decreased mean urinary fractional excretion of phosphate and median 24-h urine phosphorus, whereas no significant change was seen in the control group. Mean serum phosphorus and median serum intact parathyroid hormone (iPTH) remained stable in treated patients but increased in the control group. Vascular calcification, assessed by Kauppila and Adragão scores, worsened under calcium carbonate with no significant change in the control group. CONCLUSIONS: Calcium carbonate reduced urinary phosphate excretion and prevented the rise in phosphorus and iPTH serum levels in a cohort of normophosphataemic pre-dialysis patients. However, treatment was associated with increased vascular calcification, suggesting that calcium-based phosphate binders are not a safe option for CKD patients.

Management of RAASi-associated hyperkalemia in patients with cardiovascular disease.

Renin-angiotensin-aldosterone system inhibitors (RAASi) reduce morbidity and mortality in heart failure (HF) with reduced ejection fraction in a dose-dependent manner. They also have a positive impact in other cardiovascular diseases (CVDs). However, RAASi may induce hyperkalemia, a potentially life-threatening disorder. This risk is further increased in those with concomitant chronic kidney disease, diabetes mellitus, and/or in patients with hypertension. Current treatment guidelines recommend maximal RAASi dosing to improve clinical outcomes; however, this is often limited by the development of hyperkalemia. When this occurs, current guidelines recommend RAASi down-titration/interruption, which, while improving short-term prognosis, is associated with a negative long-term prognostic impact. At present, the European Society of Cardiology suggests the consideration of novel potassium binders (patiromer and sodium zirconium cyclosilicate) for the management of RAASi-associated hyperkalemia. Both drugs can reduce serum potassium levels and prevent recurrent hyperkalemia. Additionally, patiromer showed enabling of RAASi optimization in high-risk patients. Nevertheless, precise recommendations on the use of these drugs are lacking. Building upon current HF guideline recommendations, a multidisciplinary expert panel convened to design an algorithm providing practical guidance on the use of novel potassium binders/patiromer in patients with HF and/or other CVD. As a result of that effort, we present an evidence-based treatment algorithm for the management of hyperkalemia with novel potassium binders/patiromer in patients with HF and/or other CVD receiving RAASi, including the necessary monitoring to avoid induction of hypokalemia. This algorithm aims to maintain or up-titrate RAASi to optimized doses, while maintaining normokalemia, improved clinical outcomes, and long-term prognosis.