Prevalencia de osteopenia del prematuro antes y después de la implementación de una estrategia temprana de manejo fosfocálcico / Prevalence of osteopenia of prematurity before and after implementing an early strategy with the use of calcium and phosphate

Introducción. Con el uso de la nutrición parenteral agresiva en recién nacidos de muy bajo peso, se detectaron alteraciones del metabolismo fosfocálcico. En 2016 se implementó una estrategia de prevención a través del monitoreo fosfocálcico y su suplementación temprana. El objetivo fue estudiar si esta estrategia disminuye la prevalencia de osteopenia e identificar factores de riesgo asociados. Población y métodos. Estudio cuasiexperimental que comparó la prevalencia de osteopenia entre dos grupos: uno después de implementar la estrategia de monitoreo y suplementación fosfocálcica (01/01/2017-31/12/2019), y otro previo a dicha intervención (01/01/2013-31/12/2015). Resultados. Se incluyeron 226 pacientes: 133 pertenecen al período preintervención y 93 al posintervención. La prevalencia de osteopenia global fue del 26,1 % (IC95% 20,5-32,3) y disminuyó del 29,3 % (IC95% 21,7-37,8) en el período preintervención al 21,5 % (IC95% 13,6-31,2) en el posintervención, sin significancia estadística (p = 0,19). En el análisis multivariado, el puntaje NEOCOSUR de riesgo de muerte al nacer, recibir corticoides posnatales y el período de intervención se asociaron de manera independiente a osteopenia. Haber nacido luego de la intervención disminuyó un 71 % la probabilidad de presentar fosfatasa alcalina >500 UI/L independientemente de las restantes variables incluidas en el modelo. Conclusión. La monitorización y suplementación fosfocálcica precoz constituye un factor protector para el desarrollo de osteopenia en recién nacidos con muy bajo peso al nacer.

Introduction. With the use of aggressive parenteral nutrition in very low birth weight infants, alterations in calcium and phosphate metabolism were detected. In 2016, a prevention strategy was implemented through calcium phosphate monitoring and early supplementation. Our objective was to study whether this strategy reduces the prevalence of osteopenia and to identify associated risk factors. Population and methods. Quasi-experiment comparing the prevalence of osteopenia between two groups: one after implementing the calcium phosphate monitoring and supplementation strategy (01/01/2017­12/31/2019) and another prior to such intervention (01/01/2013­12/31/2015). Results. A total of 226 patients were included: 133 in the pre-intervention period and 93 in the post-intervention period. The overall prevalence of osteopenia was 26.1% (95% CI: 20.5­32.3) and it was reduced from 29.3% (95% CI: 21.7­37.8) in the pre-intervention period to 21.5% (95% CI: 13.6­31.2) in the post-intervention period, with no statistical significance (p = 0.19). In the multivariate analysis, the NEOCOSUR score for risk of death at birth, use of postnatal corticosteroids, and the intervention period were independently associated with osteopenia. Being born after the intervention reduced the probability of alkaline phosphatase > 500 IU/L by 71%, regardless of the other variables included in the model. Conclusion. Calcium phosphate monitoring and early supplementation is a protective factor against the development of osteopenia in very low birth weight infants.

A multidisciplinary challenge: Therapy with phosphorus-32 for locally advanced pancreatic cancer.

Pancreatic cancer is a disease with a poor prognosis, and overall survival has improved the least in the last 40 years of all cancers. Locally advanced pancreatic adenocarcinoma, without distant metastasis but with limiting vascular involvement, constitutes almost one third of these patients. This group is the focus of most research efforts to introduce treatments to increase surgical salvage rates and/or survival, with two main objectives: local control and prevention of systemic progression. Intratumoural treatment with phosphorus-32 microparticles, guided by echoendoscopy and combined with standard chemotherapy may have significant and clinically relevant benefits in these patients, and therefore a valuable treatment option in a disease where there is an urgent need to develop new therapies to help improve outcomes.

Educación alimentaria en pacientes en dialisis / Nutritional education in dialysis patients

La enfermedad renal crónica terminal aumenta el riesgo cardiovascular y puede ocasionar defectos en la mineralización ósea. Para prevenir esto, se debe mantener el fósforo plasmático normal, que depende de la diálisis, los quelantes y la ingesta de fósforo, principalmente de origen inorgánico, incorporado mediante aditivos alimentarios. Las intervenciones nutricionales son pilares en el tratamiento de estos pacientes. El objetivo es facilitar estrategias alimentarias a un grupo de pacientes pediátricos en diálisis, mediante educación alimentaria nutricional, para aumentar el consumo de alimentos naturales, disminuyendo la ingesta de fósforo inorgánico especialmente de los productos cárnicos procesados. Materiales y métodos: se estudió una población pediátrica en diálisis. Se preparó un programa educativo con atención personalizada, instrucción alimentaria y seguimiento mensual, seguido de un taller. Resultados: n: 17 pacientes, edad decimal media de 12,3, 53% sexo masculino, 88% en hemodiálisis. Previo a la intervención el 64,7% consumía productos cárnicos procesados. Luego del taller el 58,8% disminuyó su consumo, el 41,2% aumentó la ingesta de preparaciones caseras, el 53% incorporó nuevos condimentos, de los cuales el 89% presentó al incorporarlos, mejor aceptación a las preparaciones. Conclusiones: la hiperfosfatemia está presente en alrededor del 50% de los pacientes en diálisis asociándose a un incremento entre 20% al 40% del riesgo de mortalidad. La presencia de fósforo oculto en los alimentos y la falta de adherencia hacen prioritario trabajar en programas educativos que favorezcan el aprendizaje colaborativo, centralizados en prácticas culinarias, para brindar herramientas que faciliten una alimentación natural, disminuyendo el consumo de ultraprocesados (AU)

Chronic end-stage renal disease increases the risk of cardiovascular disease and may lead to defects in bone mineralization. In order to prevent these risks, normal plasma phosphorus levels should be maintained. Achieving this goal depends on dialysis, chelators, and phosphorus intake, mainly of inorganic origin, incorporated through food supplements. Nutritional interventions are crucial in the treatment of these patients. The objective is to facilitate nutritional strategies to a group of pediatric dialysis patients, through food education, to increase the consumption of natural foods, decreasing the intake of inorganic phosphorus, especially from processed meat products. Materials and methods: a pediatric population undergoing dialysis was studied. An educational program was prepared with personalized care, nutritional instruction, and monthly follow-up visits, followed by a workshop. Results: n: 17 patients, mean age 12.3 years, 53% male, 88% on hemodialysis. Prior to the intervention, 64.7% consumed processed meat products. After the workshop, 58.8% decreased their consumption, 41.2% increased the intake of homemade food, 53% incorporated new seasonings, of whom 89% reported better acceptance of the preparations when they were incorporated. Conclusions: hyperphosphatemia is observed in around 50% of patients undergoing dialysis and is associated with a 20% to 40% increased risk of mortality. The presence of hidden phosphorus in food and the lack of adherence point to the need for the development of educational programs that promote collaborative learning, focusing on food-preparation practices. These programs should provide tools that facilitate a natural diet, reducing the consumption of ultra-processed food (AU)

The 'Phosphorus Week': involvement of Spanish nephrologists in the control of phosphorus blood levels.

BACKGROUND: The adequate control of phosphorus levels is a major concern for professionals involved in the care of patients with chronic kidney disease (CKD), since high phosphorus levels are directly related to an increase in mortality. OBJECTIVES: To know the perception and involvement of Spanish nephrologists on the control of phosphorus levels, the so-called 'Phosphorus Week' was organized (November 13-17, 2017). METHODS: All members of the Spanish Society of Nephrology were invited to participate in an online survey, which included questions on aspects related to phosphorus control in patients with advanced CKD (aCKD) (glomerular filtration rate <30 ml/min/1, 73 m2) and in the different modalities of renal replacement therapies [peritoneal dialysis (PD), hemodialysis (HD) and renal transplantation (KT)]. RESULTS: 72 data entries were obtained in the survey with an inclusion of 7463 patients. Of them, 35.4% were on HD, 34.8% were KT, 24.2% had aCKD and 5.5% were on PD. The serum phosphorus level target for the four groups of patients was 4.5 mg/dl, with minimal variations depending on the area of ​​the national territory. The patients with better control of phosphataemia were patients with KT (93.3% had phosphorus values ​​<4.5 mg/dl), followed by patients with aCKD (65.6% with phosphorus <4.5 mg/dl). Only 53.6% of the patients on HD and 39.4% of those on PD reached the phosphorus goal <4.5 mg/dl. The group of patients on dialysis was the one in whom phosphorus binders prescribed the most (73.5% and 75.6% in HD and PD, respectively), being less frequent in patients with patients with aCKD (39.9%) and only 4.5 % in KT. CONCLUSIONS: The objectives of the Spanish nephrologists are in line with those recommended by the national and international clinical guidelines; however, there is still a wide room for improvement to achieve these goals, especially in HD and PD patients.

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM).

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).

[Vitamin D and its positive effect on the PTH/vitamin D/calcium-FGF23/klotho/phosphorus axis in kidney transplant recipients]. / Vitamina D y su efecto positivo sobre el eje PTH/vitamina D/calcio-FGF23/klotho/fósforo en pacientes con trasplante renal.

Introduction: Background: hypovitaminosis D is frequent in kidney transplant recipient (KTR) patients and is associated with deleterious effects both at the bone and extraosseous levels. Treatment with cholecalciferol is effective for the normalization of 25(OH)D, demonstrating a beneficial effect on the calcium-tropic axis in other populations; however, its effect on the PTH/vitamin D/calcium and FGF23/klotho/phosphorus axis in RTR has not been reported. The aim of this study was to evaluate the effect of normalization of serum 25(OH)D concentrations on the PTH/vitamin D/calcium-FGF23/klotho/phosphorus axis in KTR treated with cholecalciferol, as well as the association between the components of this axis. Methods: a prospective study in 23 KTR with hypovitaminosis D, with evolution from 1 to 12 months post-transplantation, an estimated glomerular filtration rate > 60 mL/min/1.73 m2 and a history of primary nephropathy treated with cholecalciferol, in whom the PTH/vitamin D/calcium and FGF23/klotho/phosphorus axis was evaluated during the state of hypovitaminosis D and at normalization of 25(OH)D. Results: at the normalization of 25(OH)D, a reduction in PTH [103 (58.5-123.9) vs 45.6 (30.1-65.1) pg/mL; p = 0.002] and an increase in serum phosphorus [3.1 (2.3-3.5) vs 3.3 (3-3.6) mg/dL; p = 0.01] were evident, with no differences in calcium, klotho and FGF23 concentrations. The time to achieve normalization of 25(OH)D was 12 weeks (RIC, 4-12), with a dose of 5000 IU/day (RIC, 4000-6000). A positive association between klotho and PTH was corroborated (r = 0.54; p = 0.008; linear regression, ß = 0.421; B = 0.004; 95 % CI, 0.003-0.007; p = 0.045). Conclusions: treatment with cholecalciferol is effective for the normalization of 25(OH)D, with a beneficial effect on calcium-phosphotropic metabolism characterized by a reduction in PTH concentration, without significant changes in calcemia or calciuria, as well as an increase in phosphatemia, without modifications in FGF23 or klotho concentrations.

Introducción: Introducción: la hipovitaminosis D es frecuente en los receptores de trasplante renal (RTR) y se asocia con efectos deletéreos tanto a nivel óseo como extraóseo. El tratamiento con colecalciferol es eficaz para la normalización de la 25(OH)D, demostrándose un efecto benéfico sobre el eje calciotrópico; sin embargo, su efecto sobre el eje fosfotrópico no se ha reportado. El objetivo de este estudio fue evaluar el efecto de la normalización de las concentraciones séricas de 25(OH)D sobre el eje PTH/vitamina D/calcio-FGF23/klotho/fósforo en RTR tratados con colecalciferol, así como la asociación entre sus componentes. Métodos: estudio prospectivo en 23 RTR con hipovitaminosis D y antecedente de nefropatía primaria tratados con colecalciferol, en quienes se evaluó el eje PTH/vitamina D/calcio y FGF23/klotho/fósforo durante el estado de hipovitaminosis D y a la normalización de la 25(OH)D. Resultados: a la normalización de la 25(OH)D se evidenció una reducción de la PTH [103 (58,5-123,9) vs. 45,6 (30,1-65,1) pg/mL; p = 0,002] y un aumento del fósforo sérico [3,1 (2,3-3,5) vs. 3,3 (3-3,6) mg/dL; p = 0,01], sin diferencias en las concentraciones de calcio, klotho y FGF23. El tiempo para lograr la normalización de la 25(OH)D fue de 12 semanas (4-12), con una dosis de 5000 UI/día (4000-6000). Se corroboró una asociación positiva entre klotho y PTH (r = 0,54; p = 0,008; regresión lineal, ß = 0,421; IC 95 %: 0,003-0,007; p = 0,045). Conclusiones: el tratamiento con colecalciferol es eficaz para la normalización de la 25(OH)D con un efecto benéfico sobre el metabolismo calcio-fosfotrópico caracterizado por una reducción de la PTH y un incremento de la fosfatemia, sin modificaciones de calcemia, calciuria, FGF23 o klotho.

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.

Nitrogen and phosphorus recovery from hemodialysis wastewater to use as an agricultural fertilizer.

INTRODUCTION: Hemodialysis wastewater contains high concentrations of ammonia nitrogen and phosphorus. Recovery of these nutrients as soil fertilizers represents an interesting opportunity to ensure a sustainable fertilizer supply. METHODS: In this paper, a simple method for recovering phosphorous and nitrogen as crystalline struvite [MgNH4PO4·6H2O] is presented. An integrated cost model is also presented in order to create a positive business case. RESULTS: Recovery rates in form of struvite of 95% of PO43--P and 23% of NH4+-N were achieved with a profit. CONCLUSION: To the best of our knowledge, this paper is the first to study the recovery of these naturally occurring minerals from hemodialysis wastewater. This offers great potential for the valorization of this type of wastewater.

Influência do tipo de agente espessante e da suplementação de cálcio e fósforo no efeito desmineralizante de géis clareadores a base de peróxido de hidrogênio / Influence of the type of thickening agent and supplementation of calcium and phosphate on the demineralizing effect of bleaching gels based on hydrogen peroxide

O estudo avaliou o efeito da adição de cálcio (Ca) e fósforo (P), em quantidade correspondente ao ponto de saturação (PS) e ao coeficiente de solubilidade (CS), a géis clareadores contendo diferentes agentes espessantes na desmineralização do esmalte dentário. Foram manipulados géis clareadores contendo peróxido de hidrogênio (PH) a 35% e utilizados os espessantes carbopol 980 (CB); aerosil 200 (SP); poloxamer 407 (PX); goma guar (GG) e hidroxietilcelulose (HEC). Foram realizadas leituras iniciais da microdureza Knoop do esmalte empregando um microdurômetro, da rugosidade superficial em um perfilômetro de contato e da cor utilizando espectrofotômetro colorimétrico de reflectância. Os espécimes foram divididos em 5 grupos experimentais de acordo com o tipo de espessante. Cada grupo foi dividido em três subgrupos (n=20), de acordo com a suplementação mineral (0- nenhuma suplementação; PS ­ adição de Ca e P de acordo com o PS calculado para aquele espessante; CS ­ adição da quantidade máxima de Ca e P de acordo com o CS). Além disso, três grupos controles (n=20) foram preparados, sendo eles: CN (controle negativo ­água ultrapura); CP (controle positivo ­ PH a 35% sem a adição de qualquer mineral); CC (controle positivo comercial - gel comercial Whiteness HP). Sobre cada espécime foram aplicados 0,050 g dos respectivos géis clareadores, durante 45 min. Os dados dos grupos experimentais foram analisados estatisticamente com ANOVA a 2 fatores (TIPO DE ESPESSANTE x ADIÇÃO DE SAIS DE CA E P) e teste de Tukey. A comparação com os grupos controle foi realizada com o teste de Dunnett ( = 5%). Para todas as mensurações realizadas, a ANOVA mostrou diferenças significativas para os dois fatores (p<0,05). Para a alteração da microdureza, os resultados do teste de Tukey foram: TIPO DE ESPESSANTE (p=0,0001): HEC ­ 15,40(6,97)a, GG - 10,31(5,78)b, CB - 7,49(2,87)c, PX - 4,60(4,96)d, SP - 0,57(2,43)e; ADIÇÃO (p=0,0001): 0 - 12,34(7,22)a, S -10,31(5,76)b, CS -7,49(6,09)c. Para a alteração da rugosidade (p=0,0001), os resultados foram: TIPO DE ESPESSANTE (p=0,0001): SP - 5,19(23,36), GG - 9,70(17,75)ab, PX - 15,95(20,79)b, HEC - 53,58(71,82)c, CB - 55,49(63,69)c; ADIÇÃO (p=0,0001): 0 - 79,62(58,70)a, S - 3,23(12,08)a, CS - 1,09(9,44)b. Para a mudança de cor (ΔE), os resultados foram: TIPO DE ESPESSANTE (p=0,0001): SP - 5,40(2,92)a, GG - 3,13(1,83)a, PX - 3,18(2,57)ab, HEC - 3,82(2,05)bc, CB - 4,79(3,26)c. ADIÇÃO (p=0,2853): 0 - 4,37(2,60)a, S - 4,04(3,07)a, CS - 3,79(2,42)a. Os resultados para o teste de Dunnett para a microdureza: os grupos SP, SP-S e SP-CS não demonstraram diferenças com o grupo CN, e apenas os grupos GG e HEC-S não demostraram diferenças com o grupo CP e o grupo HEC-S para o CPC. Para a rugosidade, os grupos CB-CS, SP, PX-S, PX-CS, GG-S e GG-CS não demonstraram diferenças em relação ao grupo CN e todos os grupos apresentaram diferenças significativas para os grupos CP e CPC. Mediante os resultados desse estudo, podemos concluir que: A adição de cálcio e/ou fósforo em quantidades correspondente ao PS ou ao CS apenas do grupo SP impediu a queda da dureza e o aumento da rugosidade. Os demais grupos apresentaram alterações, porém sem afetar o tratamento clareador. (AU)

The aim of the study was to evaluate the effect of adding calcium (Ca) and phosphorus (P), in amounts corresponding to the saturation concentration (SC) and the solubility limit (SL), to bleaching gels containing different thickening agents on the demineralization of tooth enamel. Bleaching gels containing 35% hydrogen peroxide (PH) were manipulated and the thickeners were used: carbopol 980 (CB); aerosil 200 (SP); poloxamer 407 (PX); guar gum (GG) and hydroxyethylcellulose (HEC). The baseline readings of Knoop microhardness of the enamel using a microhardness, surface roughness using a contact profilometer and color using a colorimetric reflectance spectrophotometer were taken. The specimens were divided into 5 experimental groups according to the type of thickener. Each group was divided into three subgroups (n=20), according to mineral supplementation (0 - no supplementation; SC - addition of Ca and P according to the SC calculated for that thickener; SL - addition of the maximum amount of Ca and P according to SL). In addition, three control groups (n=20) were prepared, namely: NC (negative control ­ ultra pure water); PC (positive control ­ 35% pH without the addition of any mineral); CC (commercial positive control - commercial Whiteness HP gel). Were applied 0.050 g of the respective bleaching gels to each specimen for 45 min. The microhardness and surface roughness of the samples were measured immediately after bleaching. All samples were then immersed in artificial saliva for 7 days and the final color evaluated. Data from the experimental groups were statistically analyzed with 2-way ANOVA (THICKENER TYPE x MINERAL SUPPLEMENTATION) and Tukey test. Comparison with control groups was performed using Dunnett's test ( = 5%). For all measurements performed, ANOVA showed significant differences for the two factors (p<0.05). For microhardness change, the Tukey test results were: THICKENER TYPE (p=0.0001): HEC - 15.40(6.97)a, GG - 10.31(5.78)b, CB - 7.49(2.87)c, PX - 4 .60(4.96)d, SP - 0.57(2.43)e; ADDITION (p=0.0001): 0 - 12.34(7.22)a, SC -10.31(5.76)b, SL -7.49(6.09)c. For roughness change (p=0.0001), the results were: TYPE OF THICKENER (p=0.0001): SP - 5.19(23.36), GG - 9.70(17.75)ab, PX - 15.95(20.79)b, HEC - 53.58(71.82)c, CB - 55.49(63.69)c; ADDITION (p=0.0001): 0 - 79.62(58.70)a, SC - 3.23(12.08)a, SL - 1.09(9.44)b. For the color change (ΔE), the results were: TYPE OF THICKENER (p=0.0001): SP - 5.40(2.92)a, GG - 3.13(1.83)a, PX - 3.18(2.57)ab, HEC - 3.82(2.05)bc, CB - 4.79(3.26)c. ADDITION (p=0.2853): 0 - 4.37(2.60)a, SC - 4.04(3.07)a, SL - 3.79(2.42)a. The results for the Dunnett test for microhardness were: the SP, SP-S and SP-CS groups did not show differences with the CN group, and only the GG and HEC-S groups did not show differences with the CP group and the HEC-S for the CPC. For roughness, the CB-CS, SP, PX-S, PX-CS, GG-S and GG-CS groups did not show differences in relation to the CN group and all groups showed significant differences for the CP and CPC groups. By the results of this study, we can conclude that: The addition of calcium and/or phosphorus in amounts corresponding to the SC or to the SL of the aerosil group only prevented the drop in hardness and the increase in roughness. (AU)

Can dark septate endophytic fungi (DSE) mobilize selectively inorganic soil phosphorus thereby promoting sorghum growth? A preliminary study / ¿Los hongos endófitos septados oscuros (DSE) pueden movilizar selectivamente el fósforo inorgánico y promover así el crecimiento del sorgo? Un estudio preliminar

Abstract Phosphate fertilizers tend to precipitate with soil components, affecting fertilization efficiency and causing negative environmental effects. Soil microorganisms have been used to solve this problem. However, the ability of dark septate endophytic fungi (DSE) to dissolve phosphates and increase crop yield are not well known. The activity of DSE fungi capable of solubilizing reagent grade phosphates was studied in a Typic Hapludoll (Hapludol típico). The effect of the fungi on the inorganic phosphorus fractions was evaluated and an experiment was conducted in pots with sorghum as a crop. No fungal structures were found in the roots. Curvularia sp. aerial biomass and root length increased; however, P concentration was not affected. Although the results are not conclusive, they represent an advance in the potential use of DSE fungi as P solubilizers to treat crop nutrition.

Resumen Los fertilizantes fosfatados tienden a precipitar con componentes del suelo, lo que afecta la eficiencia de la fertilización y causa efectos negativos. Para resolver este problema se han utilizado microorganismos del suelo. Sin embargo, no se conoce bien la capacidad de los hongos endófitos septados oscuros (ESO) para disolver fosfatos y aumentar el rendimiento de los cultivos. Se estudió en un hapludol típico (typic hapludoll) la actividad de hongos ESO capaces de solubilizar fosfatos de grado reactivo. Se evaluó el efecto de los hongos sobre las fracciones de fósforo inorgánico y se realizó un experimento en macetas con sorgo como cultivo. No se encontraron estructuras fúngicas en las raíces. Curvularia sp. aumentó la biomasa aérea y la longitud radical, pero la concentración de fósforo no se vio afectada. Aunque los resultados no son concluyentes, representan un avance en el uso potencial de hongos ESO como solubilizadores de fósforo para tratar la nutrición de cultivos.

Iron, calcium and phosphorus mineral profile in chronic renal patients on hemodialysis

The main goal of this study was to verify the association between serum and dietary concentrations of calcium, phosphorus and iron, and to determinate whether patients with kidney disease undergoing hemodialysis had inadequacy in dietary intake. We conducted a descriptive cross-sectional study that evaluated 40 patients undergoing hemodialysis. Food consumption was determined by the 24-hour recall. The optical technology method was used to obtain hemoglobin and hematocrit concentrations. Serum levels of iron, calcium and phosphorus were determined by dry chemistry. We observed insufficient consumption of energy, macronutrients and minerals. Energy intake of patients with longer hemodialysis was higher. The sample presented hypocalcemia, hyperphosphatemia (except in the group ≥8 years of hemodialysis), higher iron concentrations and lower hemoglobin and hematocrit values. The serum levels of minerals were not affected by dietary intake. There was a significant correlation between dietary phosphorus and calcium in patients undergoing hemodialysis for more than 8 years, those over 60 years old and, between calcium and phosphorus normal levels in patients over 60 years old. Hemoglobin, hematocrit and mineral serum levels were similar regardless of age and hemodialysis time. It was concluded that inadequacies of minerals reflected deregulation among metabolism and the pathophysiological changes inherent to Chronic Kidney Disease.

El objetivo principal de este estudio fue verificar la asociación entre las concentraciones séricas y dietéticas de calcio, fósforo y hierro, y determinar su ingesta dietética inadecuada en pacientes con enfermedad renal sometidos a hemodiálisis. Se trató de un estudio descriptivo transversal que evaluó a 40 pacientes en hemodiálisis. El consumo de alimentos se determinó mediante el recordatorio de 24 horas. Se utilizó el método de tecnología óptica para obtener concentraciones de hemoglobina y hematocrito. Los niveles séricos de hierro, calcio y fósforo se determinaron mediante química seca. El estudio mostró un consumo insuficiente de energía, macronutrientes y minerales. La ingesta energética de los pacientes con hemodiálisis más prolongada fue mayor. La muestra presentó hipocalcemia, hiperfosfatemia (excepto en el grupo ≥8 años de hemodiálisis), mayor concentración de hierro y menores valores de hemoglobina y hematocrito. Los niveles séricos de minerales no se vieron afectados por su ingesta dietética. Hubo una correlación significativa entre el fósforo dietético y el calcio en los pacientes en hemodiálisis durante más de 8 años y los mayores de 60 años y, también, entre los niveles normales de calcio y fósforo en los pacientes mayores de 60 años. Los niveles séricos de hemoglobina, hematocrito y minerales fueron similares independientemente de la edad y el tiempo de hemodiálisis. Se concluyó que las deficiencias de los minerales parecen reflejarse en la desregulación de su metabolismo y los cambios fisiopatológicos inherentes a la Enfermedad Renal Crónica.

Estandarización de un procedimiento espectrofotométrico para la cuantificación de polisacárido capsular de Neisseria meningitidis serogrupo X / Standardization of a spectrophotometric procedure for the quantification of Neisseria meningitidis serogroup X capsular polysaccharide

En el presente trabajo se realiza la estandarización del procedimiento espectrofotométrico de determinación de polisacárido capsular e intermedios de Neisseria meningitidis serogrupo X, mediante la determinación de los grupos fosfodiéster presentes en su estructura, por el método de Chen. Se realizó un análisis de los siguientes criterios para la estandarización: linealidad, precisión (repetibilidad y precisión intermedia) y exactitud. Se demostró mediante el diseño experimental y los procedimientos estadísticos empleados que el método es lineal (r > 0,99), el coeficiente de variación del factor respuesta < 5 por ciento, la desviación estándar relativa de la pendiente < 2 por ciento, no existiendo diferencia estadísticamente significativa entre el intercepto de la ecuación con respecto a cero; exacto, porque no existe diferencia estadísticamente significativa entre la concentración determinada en un material de trabajo y su concentración nominal; también demostró ser repetible, pues el coeficiente de variación de las concentraciones de la muestra evaluada (2,44; 2,43; 0,88 por ciento para las concentraciones bajas, medias y altas, respectivamente) es inferior al 3 por ciento y no existen diferencias estadísticamente significativas entre las medias de los resultados obtenidos por dos analistas, evaluados durante cuatro días a tres niveles de concentración. La precisión intermedia es satisfactoria(AU)

The present work comprises the standardization a spectrophotometric procedure for assessing Neisseria meningitidis, serogroup X capsular polysaccharide and their intermediates of modification, the phosphodiesters groups present in its structure, based on Chen method. An analysis of the following standardization criteria was performed: linearity, precision (repeatability and intermediate precision) and accuracy. It was demonstrated through the experimental design and the statistical procedures used that the method is linear (r > 0.99), the coefficient of variation of the response factor < 5 percent, the relative standard deviation of the slope < 2 percent, with no statistically significant difference between the intercept of the equation with respect to zero; exact, because there is no statistically significant difference between the concentration determined in a work material and its nominal concentration; it also proved to be repeatable, because the coefficient of variation of the concentrations of the sample (2.44; 2.43; 0.88 percent for low, medium and high concentrations respectively) is less than 3 percent and there is no statistically significant difference between the means of the results obtained by two analysts, evaluated for four days at three concentration levels. Its intermediate precision was satisfactory(AU)

Can dark septate endophytic fungi (DSE) mobilize selectively inorganic soil phosphorus thereby promoting sorghum growth? A preliminary study.

Phosphate fertilizers tend to precipitate with soil components, affecting fertilization efficiency and causing negative environmental effects. Soil microorganisms have been used to solve this problem. However, the ability of dark septate endophytic fungi (DSE) to dissolve phosphates and increase crop yield are not well known. The activity of DSE fungi capable of solubilizing reagent grade phosphates was studied in a Typic Hapludoll (Hapludol típico). The effect of the fungi on the inorganic phosphorus fractions was evaluated and an experiment was conducted in pots with sorghum as a crop. No fungal structures were found in the roots. Curvularia sp. aerial biomass and root length increased; however, P concentration was not affected. Although the results are not conclusive, they represent an advance in the potential use of DSE fungi as P solubilizers to treat crop nutrition.

Biodisponibilidad de fósforo en alimentos y su efecto en la enfermedad renal crónica / Bioavailability of phosphorus in food and its effect in chronic kidney disease

Resumen Introducción: el objetivo del presente trabajo se centra en reconocer la importancia de las investigaciones que relacionan la biodisponibilidad de fósforo en diferentes grupos de alimentos de origen animal, vegetal e industrial y su efecto en la progresión de la enfermedad renal crónica (ERC). Metodología: la revisión se sustentó en la búsqueda literaria en páginas web como PUBMED, Redalyc, SciELO, SCIHUB y Google Academic. Se seleccionó cada estudio, descartando aquellos que no fueran cuantitativos u originales, estuvieran incompletos, sin metodología clara, realizados en mamíferos o si los resultados no se especificaban en porcentajes. La lectura puso especial énfasis en el índice de biodisponibilidad de fósforo derivado del consumo de distintos productos alimenticios. Se elaboraron tres matrices de acuerdo con el origen del comestible y la biodisponibilidad de fósforo que absorbe el organismo. Resultados: se encontró que los alimentos industrializados y los aditivos muestran una biodisponibilidad de fósforo del 90 % al 100 %, los de origen animal del 40 % al 80 % y los de origen vegetal del 30 %. Conclusiones: los aditivos de los alimentos industrializados promueven la hiperfosfatemia y, con ello, aceleran la progresión de la enfermedad renal crónica, a diferencia de los de origen animal y vegetal, menos perjudiciales para la salud. Esto da pauta a la formación del sector salud para ampliar su conocimiento sobre el tratamiento nutricional del paciente.

Abstract Introduction: to know the importance of the investigations that relate the bioavailability of phosphorus in different groups of foods of animal, vegetable and industrialized origin and its effect on the progression in patients with Chronic Kidney Disease (CKD). Methodology: the review is based on a literary search that was carried out on web pages such as: PUBMED, Redalyc, SciELO, SCIHUB and Google Academic. Each of the studies was selected discarding those that were not quantitative, original, complete, with clear methodology, carried out in mammals, and that in their results specified the bioavailability of phosphorus in percentages. All the studies were read, placing main emphasis and interest on the percentage of phosphorus bioavailability when consuming different food groups. Three matrices were made according to the origin of the food and the bioavailability of phosphorus that is absorbed in the body; grouping them into foods of animal, vegetable and industrialized origin and additives. Results: it was found that industrialized foods and additives show a phosphorus bioavailability of 90-100%, those of animal origin 40-80%, those of plant origin 30%. Conclusions: The additives used in industrialized foods promote hyperphosphatemia and thus accelerate the progression of chronic kidney disease, unlike foods of animal and vegetable origin that are less harmful to health. This guides the training of the health sector, expanding its knowledge in the nutritional treatment of the patient.

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.

Safety and effectiveness of sucroferric oxyhydroxide in Spanish patients on dialysis: sub-analysis of the VERIFIE study.

BACKGROUND AND AIMS: In this study, we show the results of the subset of Spanish patients of the VERIFIE study, the first post-marketing study assessing the long-term safety and effectiveness of sucroferric oxyhydroxide (SFOH) in patients with hyperphosphatemia undergoing dialysis during clinical practice. PATIENTS AND METHODS: Patients undergoing hemodialysis and peritoneal dialysis with indication of SFOH treatment were included. Follow-up duration was 12-36 months after SFOH initiation. Primary safety variables were the incidence of adverse drug reactions (ADRs), medical events of special interest (MESIs), and variations in iron-related parameters. SFOH effectiveness was evaluated by the change in serum phosphorus levels. RESULTS: A total of 286 patients were recruited and data from 282 were analyzed. Among those 282 patients, 161 (57.1%) withdrew the study prematurely and 52.5% received concomitant treatment with other phosphate binders. ADRs were observed in 35.1% of patients, the most common of which were gastrointestinal disorders (77.1%) and mild/moderate in severity (83.7%). MESIs were reported in 14.2% of patients, and 93.7% were mild/moderate. An increase in ferritin (386.66ng/mL vs 447.55ng/mL; p=0.0013) and transferrin saturation (28.07% vs 30.34%; p=0.043) was observed from baseline to the last visit (p=0.0013). Serum phosphorus levels progressively decreased from 5.69mg/dL at baseline to 4.84mg/dL at the last visit (p<0.0001), increasing by 32.2% the proportion of patients who achieved serum phosphorus levels ≤5.5mg/dL, with a mean daily SFOH dose of 1.98 pills/day. CONCLUSIONS: SFOH showed a favorable effectiveness profile, a similar safety profile to that observed in the international study with most adverse events of mild/moderate severity, and a low daily pill burden in Spanish patients in dialysis.

Effects of nitrogen and phosphorus availability on the early growth of two congeneric pairs of savanna and forest species / Efeitos da disponibilidade de nitrogênio e fósforo no crescimento inicial de dois pares congenéricos de espécies de savana e floresta

In the tropical region, savannas and seasonal forests, both highly diverse biomes, occur side by side, under the same climate. If so, that mosaic cannot be explained solely by climatic variables, but also by fire, water availability and soil status. Nutrient availability in the soil, especially nitrogen and phosphorus, has been postulated to explain the abrupt transitions between savannas and seasonal forests in tropical regions. Plants from these two biomes may present different nutritional strategies to cope with nitrogen and phosphorus limitation. We used two congeneric pairs of trees - each pair with a species from the savanna and another from the neighboring seasonal forest - to test whether savanna and forest species presented different nutritional strategies during their early development. We cultivated 56 individuals from each of these species in a hydroponics system with four treatments: (1) complete Hoagland solution, (2) Hoagland solution without nitrogen, (3) Hoagland solution without phosphorus, and (4) Hoagland solution without nitrogen and phosphorus. After 45 days, we harvested the plants and measured total biomass, root to shoot ratio, height, leaf area, and specific leaf area. Overall, savanna species were lighter, shorter, with smaller leaves, higher specific leaf areas, and higher root to shoot ratios when compared to the forest species. Nitrogen increased the performance of species from both biomes. Phosphorus improved the performance of the forest species and caused toxicity symptoms in the savanna species. Hence, savanna and forest species presented different demands and were partially distinct already as seedlings concerning their nutritional strategies.

Em regiões tropicais, savanas e florestas estacionais, biomas altamente diversos, ocorrem lado a lado, sob o mesmo clima. Sendo assim, esse mosaico não pode ser explicado somente por variáveis climáticas, devendo ser considerada a frequência e intensidade de incêndios, disponibilidade de água e status do solo. A disponibilidade de nutrientes no solo, especialmente nitrogênio e fósforo, tem sido postulada para explicar as transições abruptas entre savanas e florestas estacionais nos trópicos. Espécies vegetais desses dois biomas podem apresentar estratégias nutricionais diferentes para lidar com a limitação tanto de nitrogênio como de fósforo. Utilizamos dois pares de árvores congenéricas - cada par com uma espécie típica de savana e outra de floresta estacional vizinha - para testar se as espécies da savana e da floresta apresentaram estratégias nutricionais diferentes durante seu desenvolvimento inicial. Cultivamos 56 indivíduos de cada uma dessas espécies em um sistema hidropônico com quatro tratamentos: (1) solução Hoagland completa, (2) solução Hoagland sem nitrogênio, (3) solução Hoagland sem fósforo e (4) solução Hoagland sem nitrogênio e fósforo. Após 45 dias, colhemos as plantas e medimos a biomassa total, a relação raiz / parte aérea, altura, área foliar e área foliar específica. No geral, as espécies savânicas foram mais leves, menores em altura, área foliar e área foliar específica e apresentaram maiores razões entre biomassa radicular por biomassa aérea quando comparadas às espécies florestais. A oferta de nitrogênio aumentou o desempenho das espécies de ambos biomas. O fósforo melhorou o desempenho das espécies florestais e causou sintomas de toxicidade nas espécies savânicas. Concluímos que, já como mudas, espécies congenéricas de savana e floresta apresentaram demandas distintas e foram parcialmente diferentes em relação a suas estratégias nutricionais.

Particle size of oyster shell meal and calcium: phosphorus ratios in broiler diets / Efeito do tamanho de partícula da farinha de ostras e relações cálcio: fósforo em dietas para frangos de corte

The effects of Ca:P total ratio and particle size of oyster shell meal (OSM) were evaluated in broiler diets. In Experiment 1, 800 broilers (22-42 days old) were distributed in a 2×2 factorial design, with two Ca:P ratios (1.7 and 2.0:1) and two OSM particle sizes (coarse = 1,354 µm and fine = 428 µm), totaling four treatments with 10 repetitions with 20 broilers. Feed intake, weight gain, and feed conversion ratio were calculated. In Experiment 2, 1,280 broilers were distributed in a 2×2×2 factorial design (1.7 and 2.0:1 Ca:P ratios; coarse and fine OSM; male and female broilers), with eight treatments and 16 repetitions with 10 broilers. Apparent metabolizability of dry matter, Ca, P, and apparent metabolizable energy (AME), as well as bone resistance, bone weight, ash, Ca, and P content in the tibia were assessed. Growth performance was not affected (P > 0.05). Coarse OSM increased tibia Ca content in male broilers (P < 0.001), and higher Ca:P ratio improved bone ash and bone resistance in both sexes (P < 0.001), but reduced P content in male broilers (P < 0.05); male broilers displayed heavier bones with higher ash content than females (P < 0.05). Metabolizability of Ca was improved with coarse OSM (P < 0.05); whereas metabolizability of DM, P, and AME was not affected (P > 0.05). In conclusion, diets with a Ca:P total ratio of 2.0:1 containing coarser OSM improved bone mineral composition, particularly in male broilers, and coarse OSM improved the metabolizability of Ca in broilers regardless of the Ca:P total ratio or broiler sex.

Dois experimentos foram conduzidos para avaliar os efeitos do tamanho de partícula da farinha de ostras (FO) e relação Ca:P total em dietas para frangos de corte. No primeiro experimento, 800 frangos (22 a 42 dias) foram distribuídos em um delineamento fatorial 2x2: 2 relações Ca:P (1,7 e 2,0:1) e dois tamanhos de partícula da FO (grossa = 1354 µm e fina = 428 µm), totalizando quatro tratamentos com 10 repetições de 20 aves. O consumo de ração, o ganho de peso e a conversão alimentar foram calculados. No segundo experimento, 1.280 frangos foram distribuídos em um fatorial 2x2x2 (relações Ca:P 1,7 e 2,0:1; FO grossa e fina; aves machos e fêmeas) com oito tratamentos e 16 repetições de 10 aves. Foram avaliados: metabolizabilidade aparente da matéria seca, Ca e P, energia metabolizável aparente (EMA), peso e resistência óssea, conteúdo de cinzas, Ca e P na tíbia. As variáveis de desempenho não foram afetadas (P > 0,05). O uso de FO grossa aumentou o conteúdo de Ca na tíbia de frangos machos (P < 0,001), e a relação Ca:P de 2,0:1 aumentou o conteúdo de cinzas e aprimorou resistência óssea em ambos os sexos (P < 0,001), porém reduziu P na tíbia dos machos (P < 0,05); frangos machos também tiveram ossos mais pesados e maior conteúdo de cinzas do que fêmeas (P < 0,05). A metabolizabilidade de Ca foi melhorada com FO grossa, enquanto a metabolizabilidade da matéria seca, P, e EMA não foram afetadas (P > 0,05). Conclui-se que as dietas com relação Ca:P de 2,0:1 e com FO grossa resultaram em melhor composição mineral óssea - particularmente em frangos machos - e a FO grossa melhorou a metabolizabilidade de Ca independentemente da relação Ca:P ou do gênero das aves.

Effects of nitrogen and phosphorus availability on the early growth of two congeneric pairs of savanna and forest species / Efeitos da disponibilidade de nitrogênio e fósforo no crescimento inicial de dois pares congenéricos de espécies de savana e floresta

In the tropical region, savannas and seasonal forests, both highly diverse biomes, occur side by side, under the same climate. If so, that mosaic cannot be explained solely by climatic variables, but also by fire, water availability and soil status. Nutrient availability in the soil, especially nitrogen and phosphorus, has been postulated to explain the abrupt transitions between savannas and seasonal forests in tropical regions. Plants from these two biomes may present different nutritional strategies to cope with nitrogen and phosphorus limitation. We used two congeneric pairs of trees — each pair with a species from the savanna and another from the neighboring seasonal forest — to test whether savanna and forest species presented different nutritional strategies during their early development. We cultivated 56 individuals from each of these species in a hydroponics system with four treatments: (1) complete Hoagland solution, (2) Hoagland solution without nitrogen, (3) Hoagland solution without phosphorus, and (4) Hoagland solution without nitrogen and phosphorus. After 45 days, we harvested the plants and measured total biomass, root to shoot ratio, height, leaf area, and specific leaf area. Overall, savanna species were lighter, shorter, with smaller leaves, higher specific leaf areas, and higher root to shoot ratios when compared to the forest species. Nitrogen increased the performance of species from both biomes. Phosphorus improved the performance of the forest species and caused toxicity symptoms in the savanna species. Hence, savanna and forest species presented different demands and were partially distinct already as seedlings concerning their nutritional strategies.

Em regiões tropicais, savanas e florestas estacionais, biomas altamente diversos, ocorrem lado a lado, sob o mesmo clima. Sendo assim, esse mosaico não pode ser explicado somente por variáveis climáticas, devendo ser considerada a frequência e intensidade de incêndios, disponibilidade de água e status do solo. A disponibilidade de nutrientes no solo, especialmente nitrogênio e fósforo, tem sido postulada para explicar as transições abruptas entre savanas e florestas estacionais nos trópicos. Espécies vegetais desses dois biomas podem apresentar estratégias nutricionais diferentes para lidar com a limitação tanto de nitrogênio como de fósforo. Utilizamos dois pares de árvores congenéricas — cada par com uma espécie típica de savana e outra de floresta estacional vizinha — para testar se as espécies da savana e da floresta apresentaram estratégias nutricionais diferentes durante seu desenvolvimento inicial. Cultivamos 56 indivíduos de cada uma dessas espécies em um sistema hidropônico com quatro tratamentos: (1) solução Hoagland completa, (2) solução Hoagland sem nitrogênio, (3) solução Hoagland sem fósforo e (4) solução Hoagland sem nitrogênio e fósforo. Após 45 dias, colhemos as plantas e medimos a biomassa total, a relação raiz / parte aérea, altura, área foliar e área foliar específica. No geral, as espécies savânicas foram mais leves, menores em altura, área foliar e área foliar específica e apresentaram maiores razões entre biomassa radicular por biomassa aérea quando comparadas às espécies florestais. A oferta de nitrogênio aumentou o desempenho das espécies de ambos biomas. O fósforo melhorou o desempenho das espécies florestais e causou sintomas de toxicidade nas espécies savânicas. Concluímos que, já como mudas, espécies congenéricas de savana e floresta apresentaram demandas distintas e foram parcialmente diferentes em relação a suas estratégias nutricionais.

Effects of nitrogen and phosphorus availability on the early growth of two congeneric pairs of savanna and forest species

Abstract In the tropical region, savannas and seasonal forests, both highly diverse biomes, occur side by side, under the same climate. If so, that mosaic cannot be explained solely by climatic variables, but also by fire, water availability and soil status. Nutrient availability in the soil, especially nitrogen and phosphorus, has been postulated to explain the abrupt transitions between savannas and seasonal forests in tropical regions. Plants from these two biomes may present different nutritional strategies to cope with nitrogen and phosphorus limitation. We used two congeneric pairs of trees each pair with a species from the savanna and another from the neighboring seasonal forest to test whether savanna and forest species presented different nutritional strategies during their early development. We cultivated 56 individuals from each of these species in a hydroponics system with four treatments: (1) complete Hoagland solution, (2) Hoagland solution without nitrogen, (3) Hoagland solution without phosphorus, and (4) Hoagland solution without nitrogen and phosphorus. After 45 days, we harvested the plants and measured total biomass, root to shoot ratio, height, leaf area, and specific leaf area. Overall, savanna species were lighter, shorter, with smaller leaves, higher specific leaf areas, and higher root to shoot ratios when compared to the forest species. Nitrogen increased the performance of species from both biomes. Phosphorus improved the performance of the forest species and caused toxicity symptoms in the savanna species. Hence, savanna and forest species presented different demands and were partially distinct already as seedlings concerning their nutritional strategies.

Resumo Em regiões tropicais, savanas e florestas estacionais, biomas altamente diversos, ocorrem lado a lado, sob o mesmo clima. Sendo assim, esse mosaico não pode ser explicado somente por variáveis climáticas, devendo ser considerada a frequência e intensidade de incêndios, disponibilidade de água e status do solo. A disponibilidade de nutrientes no solo, especialmente nitrogênio e fósforo, tem sido postulada para explicar as transições abruptas entre savanas e florestas estacionais nos trópicos. Espécies vegetais desses dois biomas podem apresentar estratégias nutricionais diferentes para lidar com a limitação tanto de nitrogênio como de fósforo. Utilizamos dois pares de árvores congenéricas cada par com uma espécie típica de savana e outra de floresta estacional vizinha para testar se as espécies da savana e da floresta apresentaram estratégias nutricionais diferentes durante seu desenvolvimento inicial. Cultivamos 56 indivíduos de cada uma dessas espécies em um sistema hidropônico com quatro tratamentos: (1) solução Hoagland completa, (2) solução Hoagland sem nitrogênio, (3) solução Hoagland sem fósforo e (4) solução Hoagland sem nitrogênio e fósforo. Após 45 dias, colhemos as plantas e medimos a biomassa total, a relação raiz / parte aérea, altura, área foliar e área foliar específica. No geral, as espécies savânicas foram mais leves, menores em altura, área foliar e área foliar específica e apresentaram maiores razões entre biomassa radicular por biomassa aérea quando comparadas às espécies florestais. A oferta de nitrogênio aumentou o desempenho das espécies de ambos biomas. O fósforo melhorou o desempenho das espécies florestais e causou sintomas de toxicidade nas espécies savânicas. Concluímos que, já como mudas, espécies congenéricas de savana e floresta apresentaram demandas distintas e foram parcialmente diferentes em relação a suas estratégias nutricionais.