Characterization of deposits on double J stents

We have characterized the types of encrustations that form on ureteral stents. The deposit that generates blocks is composed of hydroxyapatite/magnesium ammonium phosphate (44%). Calcium oxalate dihydrate was also detected at a high degree of encrustation (13%). Hydroxyapatite deposits, also of high degree of encrustation (13%) are generated due to their formation as a consequence of persistently high urinary pH values. The formation of large uric acid deposits (31%) must be attributed to the persistence of urinary $\mathrm{pH} < 5.5$. To avoid development of encrustations of ureteral stents, urinary calcium levels and urinary pH control should be carried out, avoiding urinary infections

Characterization of deposits on double J stents

We have characterized the types of encrustations that form on ureteral stents. The deposit that generates blocks is composed of hydroxyapatite/magnesium ammonium phosphate (44%). Calcium oxalate dihydrate was also detected at a high degree of encrustation (13%). Hydroxyapatite deposits, also of high degree of encrustation (13%) are generated due to their formation as a consequence of persistently high urinary pH values. The formation of large uric acid deposits (31%) must be attributed to the persistence of urinary $\mathrm{pH} < 5.5$. To avoid development of encrustations of ureteral stents, urinary calcium levels and urinary pH control should be carried out, avoiding urinary infections

Methods to Identify Linear Network Models: A Review

In many contexts we may be interested in understanding whether direct connections between agents, such as declared friendships in a classroom or family links in a rural village, affect their outcomes. In this paper we review the literature studying econometric methods for the analysis of linear models of social effects, a class that includes the ‘linear-in-means’ local average model, the local aggregate model, and models where network statistics affect outcomes. We provide an overview of the underlying theoretical models, before discussing conditions for identification using observational and experimental/quasi-experimental data

En tumores de estroma gastrointestinal ¿resulta ventajosa la terapia molecular frente a la quimioterapia convencional?

[spa] El tumor de estroma gastrointestinal (GIST) representa la neoplasia mesenquimal más común del tracto gastrointestinal. Los GISTs son conocidos por ser resistentes tanto a la quimioterapia como a la radioterapia, por lo que hasta hace poco la cirugía era el único tratamiento efectivo. El reciente descubrimiento de su evento patológico central mostró que se encuentra causado por una mutación activadora en el proto-oncogen c-KIT que da lugar a un receptor constitutivamente activado, y consecuentemente, una señalización intracelular que da paso a una mayor proliferación y crecimiento celular. La aplicación del fármaco imatinib mesilato representa un importante cambio de paradigma en la terapia contra el cáncer al tratarse de una molécula inhibidora de los receptores tirosina quinasa y, por tanto, capaz de actuar selectivamente contra el receptor KIT de los pacientes con GIST, representando una nueva esperanza en el tratamiento de este tipo de tumores. El objetivo de este trabajo fue comparar la efectividad entre los fármacos de quimioterapia convencional y el fármaco imatinib mesilato, de terapia molecular dirigida, contra los GIST avanzados y/o con metástasis. Para ello se llevó a cabo una búsqueda bibliográfica de datos sobre la efectividad de los fármacos en la base de datos Pubmed/MEDLINE. Así, se observó que la respuesta al imatinib mesilato fue significativamente mayor que las respuestas totales obtenidas del conjunto de fármacos de quimioterapia convencional, confirmándose que la terapia de diana molecular resulta más ventajosa al presentar una efectividad significativamente mayor.[eng] Gastrointestinal stromal tumor (GIST) represent the most common mesenchymal neoplasms of the gastrointestinal tract. GISTs are known to be resistant to both chemotherapy and radiation therapy, so until recently surgery was the only effective treatment. The recent discovery of the central pathological event of this type of tumor showed that it is caused by an activating mutation in the proto-oncogene c-kit that gives rise to a constitutively activated receptor, and consequently, an intracellular signaling that leads to a greater proliferation and cell growth. The application of the drug imatinib mesylate represents an important paradigm shift in cancer therapy as it is an inhibitor molecule of the receptors tyrosine kinase and, therefore, capable of acting selectively against the KIT receptor of patients with GIST, representing a new hope in the treatment of this family of tumors. The aim of this study was to compare the effectiveness between conventional chemotherapy drugs and imatinib mesylate, a drug used in targeted molecular therapy, against advanced and/or metastases GISTs. To attain these objectives, a bibliographic search of data on the effectiveness of drugs in the database Pubmed/MEDLINE was conducted. Thus, it was observed that the response to imatinib mesylate was significantly greater than the total responses obtained from the conventional chemotherapy drug set, confirming that molecular targeting therapy is more advantageous, presenting a significant greater effectiveness

Desarrollo de una metodología para evaluar el riesgo de cristalización de ácido úrico en orina humana (RCAU). Estudio de los efectos del consumo de distintos productos derivados del cacao en el riesgo de cristalización del ácido úrico en orina de voluntarios sanos

[spa] Objetivos: Desarrollar una metodología para evaluar el riesgo de cristalización de ácido úrico (RCAU) en orina humana que permita valorar los efectos del consumo de cacao sobre la cristalización de ácido úrico. Por otro lado, llevar a cabo la evaluación de la capacidad de inhibición de la cristalización del ácido úrico por parte de productos derivados del cacao ricos en teobromina (cacao soluble, chocolate negro y chocolate con leche) tras su ingesta por parte de individuos sanos voluntarios. Esto permitirá evaluar la utilidad de la teobromina en la prevención de la litiasis úrica. Materiales y métodos: Los efectos del consumo de derivados del cacao se valoraron con una metodología que determina la mayor o menor tendencia de una orina a formar cristales de ácido úrico, o lo que es lo mismo, el riesgo de cristalización del ácido úrico (RCAU). El estudio se realizó con 20 voluntarios sanos, que junto con el consumo de 40 g de derivados del cacao (20 g en el desayuno y 20 g en la cena), debían seguir una dieta libre, aunque controlada, con las mismas cantidades de productos tomados el día de la recogida de la muestra para que la orina presentara una composición similar durante cada una de las recogidas. Las variables principales fueron el RCAU y la concentración urinaria de teobromina, aunque también se determinaron el pH, ácido úrico, oxalato, creatinina y diuresis. Resultados: El consumo de derivados de cacao se traduce en un aumento tanto de la excreción como de la concentración urinaria de teobromina, así como en una disminución del RCAU para el consumo de cacao soluble y chocolate negro. El consumo de chocolate con leche no supone disminución del RCAU, lo que se corresponde con unas concentraciones de teobromina por debajo de 10 mg/L. No se observan diferencias significativas en los otros parámetros estudiados. Conclusión: La administración de complementos de teobromina puede ser útil en el tratamiento de la litiasis úrica

Effect of Consumption of Cocoa-Derived Products on Uric Acid Crystallization in Urine of Healthy Volunteers

The purpose of this study was to determine the effects of consumption of different cocoa-derived products on uric acid crystallization in urine of 20 healthy volunteers. Participants were requested to select the specific diet that they wished to follow during the 12 h prior to collection of urine. The only restriction was that the diet could not include any product with cocoa, coffee, or caffeine. On the first day, each volunteer followed their selected diet, and an overnight 12 h urine sample was collected as the baseline urine. After seven days on an unrestricted diet, each volunteer repeated the same diet with 20 g of milk chocolate, chocolate powder, or dark chocolate during breakfast and another 20 g during dinner. Overnight 12 h urine samples were then collected. Urine volume, pH, oxalate, creatinine, uric acid, theobromine, and a uric acid crystallization test were determined for each sample. The results for all 20 patients show that uric acid crystallization was significantly lower following the consumption of chocolate powder or dark chocolate relative to baseline or following the consumption of milk chocolate. The results indicated that increased concentrations of urinary theobromine reduced the risk of uric acid crystallization

Comparison of Two Dietary Supplements for Treatment of Uric Acid Renal Lithiasis: Citrate vs. Citrate + Theobromine

[eng] Background. Uric acid (UA) renal lithiasis has a high rate of recurrence and a prevalence ranging from 10% and 15%, depending on the population. The most important etiological factor is persistence of urinary pH below 5.5 and one of the most common treatments is alkalization with citrate. Recent studies demonstrated that theobromine, which is abundant in chocolate and cocoa, is a potent inhibitor of UA crystallization. Aim. The aim was to compare the efficacy of citrate versus citrate + theobromine as treatment for UA lithiasis. Methods. This randomized cross-over trial investigated the efficacy of two treatments in 47 patients with UA renal lithiasis. Urine volume, pH, UA excretion, theobromine excretion, and risk of UA crystallization (RUAC) at baseline and at the end of each intervention period were measured. Results. Each treatment significantly reduced the risk of UA crystallization compared to basal values. The RUAC after citrate + theobromine was lower than the RUAC after citrate, although this difference was not statistically significant. Conclusion. The combined consumption of citrate and theobromine may be a promising strategy for the prevention of UA kidney stones

Phytate Dephosphorylation Products Also Act as Potent Inhibitors of Calcium Oxalate Crystallization

Phytate has been classified as an anti-nutrient, but there are no adverse effects from the consumption of a balanced diet with 1 to 2 g of daily phytate (inositol-hexaphosphate, InsP6) as a calcium magnesium salt, the form naturally present in grains. Furthermore, recent research has shown that phytate consumption may prevent pathological calcifications, such as kidney stones and cardiovascular calcifications. However, many endogenous and exogenous enzymes can hydrolyze phytate to lower inositol phosphates (InsPs) that also have biological activity. We performed a controlled hydrolysis of phytate and identified the products (InsPs) using tandem mass spectrometry (MS/MS). The total level of all InsPs was measured using a non-specific methodology. In addition, we evaluated the effects of the InsP6 hydrolysates on calcium oxalate crystallization using scanning electron microscopy and measuring the time needed for the induction of crystallization. Our results indicate that InsP6 and its hydrolysis products functioned as effective inhibitors of calcium oxalate crystallization. Thus, even though InsP6 is hydrolyzed after consumption, the enzymatic products also have the potential to reduce pathological calcifications. Finally, although it is useful to measure the overall level of InsPs in biological fluids, such as urine, there is a need to develop simple analytical methods to quantify the level of individual InsPs