Participación de la proteína quinasa dependiente de AMP cíclico (PKA) en la formación de la memoria de largo término en Chasmagnathus

Las hipótesis para el estudio de las bases neurobiológicas del aprendizaje y la memoria consideran que la información es almacenada por el sistema nervioso como cambios en las conexiones entre neuronas. Estos cambios son el resultado de un proceso de transformación inducido por la experiencia y dirigido en cada neurona por la activación de las vías de transducción, que por medio de la accion de quinasas, regulan cambios de corto término y la expresión de genes responsables de los cambios perdurables que subyacen la memoria de largo término. En la presente tesis se estudió la participación de la proteína quinasa dependiente de AMP-cíclico (PKA) en la formación de una memoria de largo término y aspectos de su activación fueron estudiados en estrecha relación con la experiencia y el tipo de memoria inducido. Con este objetivo se utilizó el paradigma de memoria contexto-señal del cangrejo Chasmagnathus granulatus, en el cual el animal aprende a reconocer la inocuidad de un estímulo inicialmente peligroso. Ante la falta de conocimiento previo sobre esta vía de transducción en crustáceos, se estudió la distribución de la actividad basal y total de PKA en sistema nervioso de cangrejo y se identificó y caracterizó a las isoformas I y II de la misma. Mediante la administración de un inhibidor de PKA, a distintos tiempo respecto del entrenamiento, se determinó la existencia de dos períodos en los cuales la actividad de PKA es fundamental para la consolidación. El primero durante el entrenamiento y el segundo en una ventana temporal entre 4 y 8 horas después del mismo. La medición de la actividad de PKA durante la consolidación permitió comprobar que la activación de PKA es parte de los mecanismos de la consolidación directamente inducidos por la experiencia. Se determinó que durante el segundo período de dependencia de PKA para la consolidación existe un aumento de la isoforma de PKA más sensibles al AMPc, PKA I, que estaría involucrado en el aumento de actividad de PKA necesario durante esa etapa de la consolidación. Finalmente, se estudió que aspectos temporales y mecanísticos de la activación de PKA son función específica de la activación inducida por distintas experiencias. La participación diferencial de isoformas de PKA es sugerida.Current hypothesis for the study of neurobiological basis of learning and memory consider that information provided by experience is encoded as changes in the connections between neurons. These changes are consequence of a transformation process initiated by the experience and directed by coordinate action- of signal transduction pathways. Through phosphorylation, kinases regulate short-term synaptic changes and the expression of genes involved in the plastic changes that underlie the long-term memory. Works at this thesis were aimed at studying the role of cyclic AMP-dependent protein kinase (PKA) on long-term memory formation and specific aspects of its activation were studied in relation with the kind of experience and the memory induced. The experimental model used was the context-signal learning paradigm of Chasmagnathus granulatus crab. The lack of previous information about the CAMP pathway in crustaceans prompted us first to characterize PKA from crab neural tissues. Basal and total PKA activity distribution was studied in the crab neural system and we also identified and characterized PKA isoforms I and 11. Using in vivo administration of a PKA inhibitor at different times from training, two periods of PKA dependence were determined for memory consolidation. The first of them during training session and a second one in a time window from 4 to 8 hours after training. PKA activity was measured in neural ganglia after training revealing that PKA activation is part of mechanisms directly induced by experience and involved in consolidation. Coincidently with the second PKA dependence period, an increase in the more sensible isoform, PKA I, was found. This increase could be responsible for the PKA activity necessary during this period. Finally, temporal and mechanistic aspects of PKA activation were found to be specific functions of the activation induced by different experiences that induce different memories. Differential PKA isoform participation is also suggested.Fil:Locatelli, Fernando F.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

An in-line clean system for the solid-phase extraction of emerging contaminants in natural waters

A solid-phase in-line extraction system for water samples containing low levels of emerging contaminants is described. The system was specially developed for large volume samples (up to 4 L) using commercial solid-phase extraction (SPE) cartridges. Four sets containing PTFE-made connectors, brass adapters and ball valves were used to fit SPE cartridges and sample bottles to a 4-port manifold attached to a 20 L carboy. A lab-made vacuum device was connected to the manifold cap. The apparatus is robust and less expensive than the typical available system. Its also provides less experimental handling, avoiding cross contamination and sample losses.21621

Ten years-snapshot of the occurrence of emerging contaminants in drinking, surface and ground waters and wastewaters from São Paulo state, Brazil

Emerging contaminants have been considered one of the main concerns for ensuring the quality of water around the world. This work presents the results of 10 years of analyses carried out in the state of São Paulo (Brazil) that has the high population density and intense agricultural and industrial activities. In this work 58 compounds (9 hormones, 14 pharmaceuticals and personal care products, 8 industrial compounds, 17 pesticides and 10 illicit drugs) were determined from 2006 to 2015 in 708 samples including raw and treated sewage, surface and ground and drinking waters. A preliminary risk assessment for aquatic life protection identified potential risks for caffeine, paracetamol, diclofenac, 17α-ethynylestradiol, 17β-estradiol, estriol, estrone, testosterone, triclosan, 4-n-nonylphenol, bisphenol A, atrazine, azoxystrobin, carbendazim, fipronil, imidacloprid, malathion and tebuconazole. Drinking water criteria were available only for 22 compounds and for them no adverse effects were expected at the concentrations found, except for 17β-estradiol

Maintenance treatment of renal anaemia in haemodialysis patients with methoxy polyethylene glycol-epoetin beta versus darbepoetin alfa administered monthly: a randomized comparative trial

Background. Several studies with erythropoiesis-stimulating agents claim that maintenance therapy of renal anaemia may be possible at extended dosing intervals; however, few studies were randomized, results varied, and comparisons between agents were absent. We report results of a multi-national, randomized, prospective trial comparing haemoglobin maintenance with methoxy polyethylene glycol-epoetin beta and darbepoetin alfa administered once monthly

Acute Treatment Effects on GFR in Randomized Clinical Trials of Kidney Disease Progression

Background: Acute changes in GFR can occur after initiation of interventions targeting progression of CKD. These acute changes complicate the interpretation of long-term treatment effects. Methods: To assess the magnitude and consistency of acute effects in randomized clinical trials and explore factors that might affect them, we performed a meta-analysis of 53 randomized clinical trials for CKD progression, enrolling 56,413 participants with at least one estimated GFR measurement by 6 months after randomization. We defined acute treatment effects as the mean difference in GFR slope from baseline to 3 months between randomized groups. We performed univariable and multivariable metaregression to assess the effect of intervention type, disease state, baseline GFR, and albuminuria on the magnitude of acute effects. Results: The mean acute effect across all studies was 20.21 ml/min per 1.73 m2 (95% confidence interval, 20.63 to 0.22) over 3 months, with substantial heterogeneity across interventions (95% coverage interval across studies, 22.50 to 12.08 ml/min per 1.73 m2). We observed negative average acute effects in renin angiotensin system blockade, BP lowering, and sodium-glucose cotransporter 2 inhibitor trials, and positive acute effects in trials of immunosuppressive agents. Larger negative acute effects were observed in trials with a higher mean baseline GFR. Conclusion: The magnitude and consistency of acute GFR effects vary across different interventions, and are larger at higher baseline GFR. Understanding the nature and magnitude of acute effects can help inform the optimal design of randomized clinical trials evaluating disease progression in CKD

Regeneration of myelin sheaths of normal length and thickness in the zebrafish CNS correlates with growth of axons in caliber

Demyelination is observed in numerous diseases of the central nervous system, including multiple sclerosis (MS). However, the endogenous regenerative process of remyelination can replace myelin lost in disease, and in various animal models. Unfortunately, the process of remyelination often fails, particularly with ageing. Even when remyelination occurs, it is characterised by the regeneration of myelin sheaths that are abnormally thin and short. This imperfect remyelination is likely to have implications for the restoration of normal circuit function and possibly the optimal metabolic support of axons. Here we describe a larval zebrafish model of demyelination and remyelination. We employ a drug-inducible cell ablation system with which we can consistently ablate 2/3rds of oligodendrocytes in the larval zebrafish spinal cord. This leads to a concomitant demyelination of 2/3rds of axons in the spinal cord, and an innate immune response over the same time period. We find restoration of the normal number of oligodendrocytes and robust remyelination approximately two weeks after induction of cell ablation, whereby myelinated axon number is restored to control levels. Remarkably, we find that myelin sheaths of normal length and thickness are regenerated during this time. Interestingly, we find that axons grow significantly in caliber during this period of remyelination. This suggests the possibility that the active growth of axons may stimulate the regeneration of myelin sheaths of normal dimensions

Gain modulation and odor concentration invariance in early olfactory networks.

The broad receptive field of the olfactory receptors constitutes the basis of a combinatorial code that allows animals to detect and discriminate many more odorants than the actual number of receptor types that they express. One drawback is that high odor concentrations recruit lower affinity receptors which can lead to the perception of qualitatively different odors. Here we addressed the contribution that signal-processing in the antennal lobe makes to reduce concentration dependence in odor representation. By means of calcium imaging and pharmacological approach we describe the contribution that GABA receptors play in terms of the amplitude and temporal profiles of the signals that convey odor information from the antennal lobes to higher brain centers. We found that GABA reduces the amplitude of odor elicited signals and the number of glomeruli that are recruited in an odor-concentration-dependent manner. Blocking GABA receptors decreases the correlation among glomerular activity patterns elicited by different concentrations of the same odor. In addition, we built a realistic mathematical model of the antennal lobe that was used to test the viability of the proposed mechanisms and to evaluate the processing properties of the AL network under conditions that cannot be achieved in physiology experiments. Interestingly, even though based on a rather simple topology and cell interactions solely mediated by GABAergic lateral inhibitions, the AL model reproduced key features of the AL response upon different odor concentrations and provides plausible solutions for concentration invariant recognition of odors by artificial sensors

Sistema limpo em linha para extração em fase sólida de contaminantes emergentes em águas naturais

A solid-phase in-line extraction system for water samples containing low levels of emerging contaminants is described. The system was specially developed for large volume samples (up to 4 L) using commercial solid-phase extraction (SPE) cartridges. Four sets containing PTFE-made connectors, brass adapters and ball valves were used to fit SPE cartridges and sample bottles to a 4-port manifold attached to a 20 L carboy. A lab-made vacuum device was connected to the manifold cap. The apparatus is robust and less expensive than the typical available system. Its also provides less experimental handling, avoiding cross contamination and sample losses

Odor-elicited calcium signals in uPNs and modulation by GABA.

A: scheme of the honey bee brain and dye injection site. Blue arrows indicate sensory input through the antennal nerves (AN). l-APT (green) lateral Antenno-Protocerebral-Tract, and m-APT (brown) median Antenno-Protocerebral-Tract correspond to uPNs connecting the AL with the mushroom bodies calyces (CX) and the lateral horns (LH). α-L indicates the vertical output lobes of the mushroom bodies that provide visual reference for dye injection. Calcium imaging was performed on glomeruli at the rostro-ventral side of the ALs. B: Pseudo-color image showing a representative odor-elicited activity pattern 1 second after odor onset. White squares denote areas integrated as glomeruli. Color-scale represents the Delta of the ratio 340/380 (see methods; imaging analysis). AL schema indicates the glomeruli that were identified in all bees and were used for analysis throughout the study. Glomeruli were identified based on basal fluorescence after FURA-dextran staining (380nm excitation/510nm emission) and aid by neighbors-pixels correlation images (see methods). C. Representative calcium imaging traces in identified glomeruli. Numbers on top of each trace indicate glomerulus identification [48] (. Black bars at the bottom of each trace indicate stimulus duration. Odor-elicited calcium signals were measured twice in each animal. The first measurement was obtained under perfusion with physiological saline solution (black traces) and the second measurement was obtained under perfusion of picrotoxin (red), CGP54626 (blue) or a cocktail of both (purple). All traces were normalized by setting to 1 the maximum activity measured for each glomerulus in saline conditions. D. Temporal dynamic of GABAergic inhibition. The traces were calculated by subtracting frame-to-frame the trace obtained under perfusion with saline from the trace obtained under perfusion with the blockers for each glomerulus in each animal. The figure shows the average of all glomeruli measured in 9 saline-PTX treated bees; 8 saline-CGP54626 treated bees (blue) and 7 saline-cocktail treated bees. In all traces in which the highest point (peak) of disinhibition caused by the blocker was 0.2 or higher, we recorded the time of the frame in which we measured that peak. Inset: median, 25–75% quartiles, and min/max values of the time to the peak since odor onset. PTX (637 traces) median peak = 375ms (25%-75% = 375-500ms); CGP (275 traces) median peak = 1375ms (25%-75% = 1000-2250ms); PTX+CGP (394 traces) median peak = 675ms (25%-75% = 500-875ms). Kruskal-Wallis test: H (2, N = 1306) = 445,5 p = 0,0001; multiple comparisons: p<0.001 in all cases (*). Note that these times are locked to our acquisition rate, which was one frame every 125 ms. The true peaks of disinhibition may have occurred in the time between frames.</p