Is racecadotril effective for acute diarrhea in children? -First update. / ¿Es efectivo el racecadotrilo como tratamiento para la diarrea aguda en niños? -Primera actualización.

This article updates the December 2015 Living FRISBEE (Living FRISBEE: Living FRIendly Summary of the Body of Evidence using Epistemonikos), based on the detection of two systematic reviews not identified in the previous version. Gastroenteritis or acute watery diarrhea is usually a self-limited disease, but it is still associated to substantial healthcare costs and remains a frequent demand for medical care. Racecadotril, an intestinal enkephalinase inhibitor, has been used as treatment because it would decrease the duration of acute diarrhea and fluid loss. However there is still no evidence supporting its routine use. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified five systematic reviews including nine randomized trials relevant for our question. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded racecadotril probably reduces the duration of acute diarrhea in pediatric patients, without increasing adverse effects.

Este resumen Epistemonikos (Living FRISBEE: Living FRIendly Summary of the Body of Evidence using Epistemonikos) es una actualización del resumen publicado en Diciembre de 2015, basado en la detección de dos nuevas revisiones sistemáticas que no habían sido identificadas en la versión anterior. La gastroenteritis o diarrea aguda es una enfermedad habitualmente autolimitada, pero que consume recursos sanitarios y constituye un motivo de consulta frecuente en pediatría. El racecadotrilo, un inhibidor de la encefalinasa intestinal, se ha usado como tratamiento porque disminuiría la duración de la diarrea y la pérdida de líquidos, pero no hay evidencia que justifique su uso rutinario. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en 30 bases de datos, identificamos cinco revisiones sistemáticas que en conjunto incluyen nueve estudios aleatorizados relevantes para nuestra pregunta. Realizamos un metanálisis y tablas de resumen de los resultados utilizando el método GRADE. Concluimos que el uso de racecadotrilo probablemente disminuye la duración del cuadro de diarrea aguda en población pediátrica y que no se asociaría a mayor tasa de eventos adversos.

[des-Arg(1)]-Proctolin: A novel NEP-like enzyme inhibitor identified in Tityus serrulatus venom.

The scorpion Tityus serrulatus venom comprises a complex mixture of molecules that paralyzes and kills preys, especially insects. However, venom components also interact with molecules in humans, causing clinic envenomation. This cross-interaction may result from homologous molecular targets in mammalians and insects, such as (NEP)-like enzymes. In face of these similarities, we searched for peptides in Tityus serrulatus venom using human NEP as a screening tool. We found a NEP-inhibiting peptide with the primary sequence YLPT, which is very similar to that of the insect neuropeptide proctolin (RYLPT). Thus, we named the new peptide [des-Arg(1)]-proctolin. Comparative NEP activity assays using natural substrates demonstrated that [des-Arg(1)]-proctolin has high specificity for NEP and better inhibitory activity than proctolin. To test the initial hypothesis that molecular homologies allow Tityus serrulatus venom to act on both mammal and insect targets, we investigated the presence of a NEP-like in cockroaches, the main scorpion prey, that could be likewise inhibited by [des-Arg(1)]-proctolin. Indeed, we detected a possible NEP-like in a homogenate of cockroach heads whose activity was blocked by thiorphan and also by [des-Arg(1)]-proctolin. Western blot analysis using a human NEP monoclonal antibody suggested a NEP-like enzyme in the homogenate of cockroach heads. Our study describes for the first time a proctolin-like peptide, named [des-Arg(1)]-proctolin, isolated from Tityus serrulatus venom. The tetrapeptide inhibits human NEP activity and a NEP-like activity in a cockroach head homogenate, thus it may play a role in human envenomation as well as in the paralysis and death of scorpion preys.

A scrutiny of the biochemical pathways from Ang II to Ang-(3-4) in renal basolateral membranes.

In a previous paper we demonstrated that Ang-(3-4) counteracts inhibition of the Ca(2+)-ATPase by Ang II in the basolateral membranes of kidney proximal tubules cells (BLM). We have now investigated the enzymatic routs by which Ang II is converted to Ang-(3-4). Membrane-bound angiotensin converting enzyme, aminopeptidases and neprilysin were identified using fluorescent substrates. HPLC showed that Plummer's inhibitor but not Z-pro-prolinal blocks Ang II metabolism, suggesting that carboxypeptidase N catalyzes the conversion Ang II--> Ang-(1-7). Different combinations of bestatin, thiorphan, Plummer's inhibitor, Ang II and Ang-(1-5), and use of short proteolysis times, indicate that Ang-(1-7)--> Ang-(1-5)--> Ang-(1-4)--> Ang-(3-4) is a major route. When Ang III was combined with the same inhibitors, the following pathway was demonstrated: Ang III--> Ang IV--> Ang-(3-4). Ca(2+)-ATPase assays with different Ang II concentrations and different peptidase inhibitors confirm the existence of these pathways in BLM and show that a prolyl-carboxypeptidase may be an alternative catalyst for converting Ang II to Ang-(1-7). Overall, we demonstrated that BLM have all the peptidase machinery required to produce Ang-(3-4) in the vicinity of the Ca(2+)-ATPase, enabling a local RAS axis to effect rapid modulation of active Ca(2+) fluxes.

Further evidence on the anxiogenic-like effect of substance P evaluated in the elevated plus-maze in rats.

Substance P (SP) and its preferred NK1 receptor are widely expressed throughout the fear-processing pathways of the brain and its role in the modulation of experimental anxiety has been demonstrated. SP, like other peptides, are cleaved by peptidases in two fragments: C-terminal (SP 6-11) and N-terminal (SP 1-7) that could be responsible for its anxiogenic-like response. In this study we investigate the effects of i.c.v. micro-injections of SP free acid (SPfa), which is resistant to enzymatic cleavage, the influence of the pretreatment with peptidase inhibitors (PIs), thiorphan and/or phosphoramidon, as well as the effects of SP 6-11 and SP 1-7 and the participation of NK1 and NK2 receptors on their behavioral effects. Adult male Wistar rats were treated with 10 pmol solutions of SP 6-11, SP 1-7 or 1 and 10 pmol of SPfa and evaluated in the elevated plus maze (EPM) test. Other experimental groups received thiorphan 0.2 pmol, phosphoramidon 2 pmol or both PIs 30 min prior SP 1-11, 10 pmol i.c.v. The C-terminal fragment (SP 6-11, 10 pmol) and SPfa (1 pmol) promoted an anxiogenic-like profile of action similar to 10 pmol of SP 1-11, i.e., a decrease of entries and time spent on the open arms, whereas the N-terminal fragment (SP 1-7) was inactive at the EPM. The effect of SP 6-11 was inhibited by pretreatment (100 pmol) with NK1 (FK 888) and NK2 (SR 48968) antagonists. Moreover, both PIs enhanced the SP effect when used alone, but their combination produced an apparent reversion of anxiogenic-like effect produced by SP. Altogether, our results give further support to the SP role in the modulation of experimental anxiety in rats.

Capsaicin-induced release of VIP-like immunoreactivity: modulation by enzyme inhibitors.

Vasoactive intestinal peptide (VIP) is a potent bronchial smooth muscle relaxant. In the present study we measured the release of VIP-like immunoreactivity (VIP-LI) after tracheal infusion of capsaicin, histamine, and methacholine in isolated guinea pig lungs superfused through the trachea. We also studied if inhibition of VIP enzymatic cleavage using a combination of an inhibitor of neutral endopeptidase [thiorphan (Thio)] and an inhibitor of serine proteases [soybean trypsin inhibitor (STI)] influenced the airway effects of capsaicin. Infusion of capsaicin resulted in a significant increase in VIP-LI in the perfusate (12.32 +/- 4.80 to 33.52 +/- 8.46 fmol/5 min fraction; P < 0.001). There was no increase in VIP-LI after infusion of methacholine or histamine. Maximal changes in airway opening pressure (Pao) observed 0-10 min after tracheal infusion of capsaicin were significantly greater in the Thio group than the control group and the groups of lungs that received STI or STI + Thio (P < 0.005). In addition, recovery of VIP-LI in the superfusate after infusion of capsaicin was significantly greater in the group of lungs that was superfused with Thio + STI compared with STI, Thio, and control groups. Our results suggest that a bronchodilator peptide with the profile of enzymatic cleavage of VIP also modulates capsaicin effects, since the increase in Pao in the presence of Thio + STI was significantly lower than Thio alone.