Hydrologic Transport of Dissolved Inorganic Carbon and Its Control on Chemical Weathering

Chemical weathering is one of the major processes interacting with climate and tectonics to form clays, supply nutrients to soil microorganisms and plants, and sequester atmospheric CO2. Hydrology and dissolution kinetics have been emphasized as factors controlling chemical weathering rates. However, the interaction between hydrology and transport of dissolved inorganic carbon (DIC) in controlling weathering has received less attention. In this paper, we present an analytical model that couples subsurface water and chemical molar balance equations to analyze the roles of hydrology and DIC transport on chemical weathering. The balance equations form a dynamical system that fully determines the dynamics of the weathering zone chemistry as forced by the transport of DIC. The model is formulated specifically for the silicate mineral albite, but it can be extended to other minerals, and is studied as a function of percolation rate and water transit time. Three weathering regimes are elucidated. For very small or large values of transit time, the weathering is limited by reaction kinetics or transport, respectively. For intermediate values, the system is transport controlled and is sensitive to transit time. We apply the model to a series of watersheds for which we estimate transit times and identify the type of weathering regime. The results suggest that hydrologic transport of DIC may be as important as reaction kinetics and dilution in determining chemical weathering rates

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Weathering of evaporites: natural versus anthropogenic signature on the composition of river waters

Weathering of evaporites strongly influences the chemistry of continental runoff, making surface waters poorly exploitable for civil uses. In south-central Sicily, this phenomenon is worsened by the occurrence of abandoned landfills of old sulphur and salt mines. The industrial evolution of the Bosco-S. Cataldo mining site leaved two landfills from the early exploitation of a sulphur mine followed by that of a kainite deposit. In particular, the weathering of these landfills leads the dissolved salt (TDS) values up to about 200 g l−1 in the Stincone–Salito Stream waters. This process induces the V, Cr and Fe desorption from sediments and particulates in the aqueous phase under reducing conditions. At the same time, the weathering of salt minerals releases Rb and Cs, originally contained in halite. The overall processes lead to the V, Cr, Fe, Rb and Cs enrichment of waters from the Stincone–Salito Stream system accompanied by a sharp growth of As content, up to about 13 µg l−1, caused by As release from Fe-bearing solids due to the high salinity. Therefore, the scenario of the weathering of Bosco-S. Cataldo mine landfills depicts an environment strongly influenced by effects of the growing salinity and euxinic water conditions where the attained TDS, Eh and pH conditions reduce the natural scavenging capability of the interested river system, favouring a growth of residence time of toxic elements in river waters

Permanent Pancreatic Duct Occlusion With Neoprene-based Glue Injection After Pancreatoduodenectomy at High Risk of Pancreatic Fistula : A Prospective Clinical Study

OBJECTIVE: The aim of this study was to assess safety and efficacy of pancreatic duct occlusion (PDO) with neoprene-based glue in selected patients undergoing pancreatoduodenectomy (PD) at high risk of postoperative pancreatic fistula (POPF). BACKGROUND DATA: PD is the reference standard approach for tumors of the pancreaticoduodenal region. POPF is the most relevant complication after PD. PDO has been proposed as an alternative to anastomosis to manage the pancreatic stump. METHODS: A single-center, prospective, nonrandomized trial enrolled 100 consecutive PD for cancer. Patients at high risk for POPF according to Fistula Risk Score (FRS) >15% ( 656 points) were treated with PDO using neoprene glue (study cohort); patients with FRS 6415% ( 645 points) received pancreaticojejunal anastomosis (PJA: control cohort). Primary endpoint was complication rate grade 653 according to Dindo-Clavien Classification (DCC). Other postoperative outcomes were monitored (ClinicalTrials.gov NCT03738787). RESULTS: Fifty-one patients underwent PDO and 49 PJA. DCC 653, postoperative mortality, and POPF grade B-C were 25.5% versus 24.5% (P = 0.91), 5.9% versus 2% (P = 0.62), and 11.8% versus 16.3% (P = 0.51) in the study versus control cohort, respectively. At 1 and 3 years, new-onset diabetes was diagnosed in 13.7% and 36.7% of the study cohort versu 4.2% and 12.2% in controls (P = 0.007). CONCLUSIONS: PDO with neoprene-based glue is a safe technique that equalizes early outcome of selected patients at high risk of POPF to those at low risk undergoing PJA. Neoprene-based PDO, however, triples the risk of diabetes at 1 and 3 years

The role of SGLT2i in attenuating residual cardiovascular risk through blood pressure-lowering: mechanistic insights and perspectives

Sodium glucose cotransporter 2 inhibitors (SGLT2) have been increasingly pursued as a promising target for addressing residual cardiovascular risk. Prior trials demonstrated that SGLT2i not only promotes glucose-lowering, but also improves endothelial dysfunction, adiposity, fluid overload, and insulin sensitivity thus contributing to hemodynamic changes implicated in its cardiorenal benefits. The mechanisms in the effect of SGLT2i on blood pressure and their potential role in preventing cardiovascular events are hereby revised

Amyloid‐beta induces different expression pattern of tissue transglutaminase and its isoforms on olfactory ensheathing cells: Modulatory effect of indicaxanthin

Herein, we assessed the effect of full native peptide of amyloid‐beta (Aβ) (1‐42) and its fragments (25‐35 and 35‐25) on tissue transglutaminase (TG2) and its isoforms (TG2‐Long and TG2‐ Short) expression levels on olfactory ensheathing cells (OECs). Vimentin and glial fibrillary acid protein (GFAP) were also studied. The effect of the pre‐treatment with indicaxanthin from Opuntia ficus‐indica fruit on TG2 expression levels and its isoforms, cell viability, total reactive oxygen species (ROS), superoxide anion (O2−), and apoptotic pathway activation was assessed. The levels of Nestin and cyclin D1 were also evaluated. Our findings highlight that OECs exposure to Aβ(1‐ 42) and its fragments induced an increase in TG2 expression levels and a different expression pattern of its isoforms. Indicaxanthin pre‐treatment reduced TG2 overexpression, modulating the expression of TG2 isoforms. It reduced total ROS and O2− production, GFAP and Vimentin levels, inhibiting apoptotic pathway activation. It also induced an increase in the Nestin and cyclin D1 expression levels. Our data demonstrated that indicaxanthin pre‐treatment stimulated OECs self-renewal through the reparative activity played by TG2. They also suggest that Aβ might modify TG2 conformation in OECs and that indicaxanthin pre‐treatment might modulate TG2 conformation, stimulating neural regeneration in Alzheimer’s disease

Central role of obesity in endothelial cell dysfunction and cardiovascular risk

Atherosclerosis is the leading cause of mortality in the contemporary world. The critical role of the endothelial cells (EC) in vascular homeostasis, the metabolic changes that take place when the cell is activated, and the elements involved in these processes have been widely explored over the past years. Obesity and its impact, promoting a rise in blood levels of free fatty acids (FAs) are often associated with atherosclerosis and cardiovascular mortality. However, the mechanisms that promote cardiovascular structural changes and adaptive changes in the ECs, particularly in the context of obesity, are little known. Here, we reviewed studies that assessed the metabolic adaptations of healthy and dysfunctional ECs during exposure to FAs, as well as the epidemiological perspectives of cardiovascular structural changes in obesity. Finally, we explored the role of new agents - sphingolipids, dietary unsaturated fatty acids and sodium-glucose cotransporter-2 inhibitors (iSGLT2) - in atherosclerosis and their relationship with obesity.651879