A reply to "Relevant factors in the eutrophication of the Uruguay River and the Río Negro".

A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophication is not one of the main causes for cyanobacterial blooms in rivers and artificial reservoirs. By combining rivers of markedly different hydrological characteristics e.g., presence/absence and number of dams, river discharge and geological setting, the study speculates about the role of nutrients for modulating phytoplankton chlorophyll-a. Here, we identified serious flaws, from erratic and inaccurate data manipulation. The study did not define how erroneous original dataset values were treated, how the variables below the detection/quantification limit were numerically introduced, lack of mandatory variables for river studies such as flow and rainfall, arbitrary removal of pH > 7.5 values (which were not outliers), and finally how extreme values of other environmental variables were included. In addition, we identified conceptual and procedural mistakes such as biased construction/evaluation of model prediction capability. The study trained the model using pooled data from a short restricted lotic section of the (large) Uruguay River and from both lotic and reservoir domains of the Negro River, but then tested predictability within the (small) Cuareim River. Besides these methodological considerations, the article shows misinterpretations of the statistical correlation of cause and effect neglecting basic limnological knowledge of the ecology of harmful algal blooms (HABs) and international research on land use effects on freshwater quality. The argument that pH is a predictor variable for HABs neglects overwhelming basic paradigms of carbon fluxes and change in pH because of primary productivity. As a result, the article introduces the notion that HABs formation are not related to agricultural land use and water residence time and generate a great risk for the management of surface waterbodies. This reply also emphasizes the need for good practices of open data management, especially for public databases in view of external reproducibility.

[A new methodology for the preoperative localization of occult insulinomas]. / Nueva metodología para la localizacion preoperatoria de insulinomas ocultos.

UNLABELLED: In patients with hypoglycemic syndrome, preoperative localization of the insulinoma highly contributes to surgical removal. When the ultrasonography, computed tomography, magnetic resonance and pancreatic angiography fail to visualize the tumor, they are called occult insulinomas (OI). In this paper we describe the results of a new diagnostic method to localize OI, performed in 5 patients with hypoglycemic syndrome secondary to endogenous hyperinsulinism. In four out of five patients, computed tomography, magnetic resonance and angiography failed to show any tumor. In just one single case, these imaging methods showed the pancreatic tumor. All patients were studied by selective intraarterial pancreatic stimulation (SIPS): a) infusion of calcium gluconate (0.025 mEq/kg) in each artery that supplies the pancreas: gastroduodenal, superior mesenteric and splenic arteries as well as the hepatic artery; b) insulin venous sampling in the right supra-hepatic vein at 30 and 60 seconds after arterial stimulation (in one patient an additional sample at 90 seconds was obtained). The study was considered pathologic when the gradient (basal vs post-stimulus) increased at least 100%. RESULTS: In all five patients a pathological gradient was found. The suspected preoperative localization of the tumor was confirmed at surgery in four cases. The anatomopathologic examination revealed insulinoma in four cases and malignant insulinoma in the remaining. It is concluded that the results of this preliminary experience show the usefulness of SIPS in the preoperative localization of occult insulinomas.

Efecto del hábito de fumar sobre las lipoproteínas plasmáticas / Effedt of smoking on the plasmas lipoproteins

Las lipoproteínas plasmáticas han sido objeto de estudios tendientes a poner de mainfiesto al tabaquismo como un factor de riesgo en el desarrollo de la aterosclerosis. Con tal fin en este trabajo se estudian las LP en dos poblaciones cuya única diferencia manifiesta es que una de ellas está compuesta por fumadores de más de 20 cigarrillos por día por más de 3 años. Los resultados muestran un aumento de las LP aterogénicas, de la familia LP B y una disminución de las LP antiaterogénicas de la familia LP A1, con un descenso significativo de los índices de riesgo aterogénico. En suma, esto revela un aumento del poder aterogénico metabólico del plasma de los fumadores. Se concluye que las variaciones producidas en un factor de riesgo aterogénico, las LP, por un factor de riesgo coronario, el tabaquismo, llevan a una alteración metabólica de las mismas que acelera el proceso aterosclerótico en los fumadores. Se plantean los posibles mecanismos actuantes

Efecto del hábito de fumar sobre las lipoproteínas plasmáticas / Effedt of smoking on the plasmas lipoproteins

Las lipoproteínas plasmáticas han sido objeto de estudios tendientes a poner de mainfiesto al tabaquismo como un factor de riesgo en el desarrollo de la aterosclerosis. Con tal fin en este trabajo se estudian las LP en dos poblaciones cuya única diferencia manifiesta es que una de ellas está compuesta por fumadores de más de 20 cigarrillos por día por más de 3 años. Los resultados muestran un aumento de las LP aterogénicas, de la familia LP B y una disminución de las LP antiaterogénicas de la familia LP A1, con un descenso significativo de los índices de riesgo aterogénico. En suma, esto revela un aumento del poder aterogénico metabólico del plasma de los fumadores. Se concluye que las variaciones producidas en un factor de riesgo aterogénico, las LP, por un factor de riesgo coronario, el tabaquismo, llevan a una alteración metabólica de las mismas que acelera el proceso aterosclerótico en los fumadores. Se plantean los posibles mecanismos actuantes (AU)