Implicaciones de la tirosina cinasa p125FAK en procesos de secreción pancreática

La estimulación de células acinares pancreáticas con CCK-8 o carbacol, un agonista colinérgico, induce la fosforilación en residuos de tirosina de la proteína tirosina cinasa p125FAK y su sustrato, paxilina. Este fenómeno, en el que participan la fosfolipasa C y el citoesqueleto de actina, no parece ser un requisito necesario para el inicio y mantenimiento de la secreción enzimática de dichas células.Stimulation of pancreatic acinar cells with CCK-8 or the cholinergic agonist, carbachol, induces tyrosine phosphorylation of the tyrosine kinase p125FAK and its substrate, paxillin. This event, which involves the activation of phospholipase C and the integrity of the actin cytoskeleton, is not essential for the secretory process of pancreatic acinar cells.Minsiterio de Educación y Cultura (PB94-1416-C02-02; Beca AP94 28942443

Confirmation of symmetrical distributions of clinical attachment loss and tooth loss in a homogeneous Mexican adult male population

Background/purpose To ascertain whether or not clinical attachment loss and tooth loss are present with similar severity and prevalence across the two sides of the mouth in a homogeneous sample of urban male adults. Materials and methods A cross-sectional study was carried out on 161 policemen (a largely homogeneous group in terms of ethnic background, socioeconomic status, sex, occupation, and medical/dental insurance) in Campeche, Mexico. Periodontal examinations were undertaken using the Florida Probe System in a dental chair by one trained and standardized examiner (kappa ≥ 0.60) to determine clinical attachment loss and tooth loss. We examined six sites in all teeth present in the mouth (a maximum of 168 sites, no third molars). Because of correlated data between observations, McNemar (for tooth loss) and Wilcoxon (for attachment loss) signed-rank tests were used to compare right and left sites within the same patient. Results The mean age was 38.4 ± 11.0 years. The mean number of teeth present was 24.4 ± 4.6; the mean number of periodontal sites/person was 146.7 ± 27.8. All P values were ≥ 0.05 (except for attachment loss in the upper first premolars), suggesting that there were no statistically significant differences between the right and left sides for the frequency of presentation of these two conditions. Conclusion Tooth loss and attachment loss measurements largely resemble each other on both sides of the mouth

FKBP52 is involved in the regulation of SOCE channels in the human platelets and MEG 01 cells

AbstractImmunophilins are FK506-binding proteins that have been involved in the regulation of calcium homeostasis, either by modulating Ca2+ channels located in the plasma membrane or in the rough endoplasmic reticulum (RE). We have investigated whether immunophilins would participate in the regulation of stored-operated Ca2+ entry (SOCE) in human platelets and MEG 01. Both cell types were loaded with fura-2 for determining cytosolic calcium concentration changes ([Ca2+]c), or stimulated and fixed to evaluate the protein interaction profile by performing immunoprecipitation and western blotting. We have found that incubation of platelets with FK506 increases Ca2+ mobilization. Thapsigargin (TG)-evoked, Thr-evoked SOCE and TG-evoked Mn2+ entry resulted in significant reduction by treatment of platelets with immunophilin antagonists. We confirmed by immunoprecipitation that immunophilins interact with transient receptor potential channel 1 (TRPC1) and Orai1 in human platelets. FK506 and rapamycin reduced the association between TRPC1 and Orai1 with FK506 binding protein (52) (FKBP52) in human platelets, and between TRPC1 and the type II IP3R, which association is known to be crucial for the maintenance of SOCE in human platelets. FKBP52 role in SOCE activation was confirmed by silencing FKBP52 using SiRNA FKBP52 in MEG 01 as demonstrated by single cell configuration imaging technique. TRPC1 silencing and depletion of cell of TRPC1 and FKBP52 simultaneously, impair activation of SOCE evoked by TG in MEG 01. Finally, in MEG 01 incubated with FK506 we observed a reduction in TRPC1/FKBP52 coupling, and similarly, FKBP52 silencing reduced the association between IP3R type II and TRPC1 during SOCE. All together, these results demonstrate that immunophilins participate in the regulation of SOCE in human platelets

Two-pore channel 2 (TPC2) modulates store-operated Ca2+ entry

AbstractTwo-pore channels (TPCs) are NAADP-sensitive receptor channels that conduct Ca2+ efflux from the intracellular stores. Discharge of the internal Ca2+ pools results in the activation of store-operated Ca2+ entry (SOCE); however, the role of TPCs in the modulation of SOCE remains unexplored. Mammalian cells express three TPCs: TPC1, TPC2 and TPC3, a pseudogene in humans. Here we report that MEG01 and HEK293 cells endogenously express TPC1 and TPC2. Silencing TPC2 expression results in attenuation of the rate and extent of thapsigargin (TG)-evoked SOCE both in MEG01 and HEK293 cells, without having any effect on the ability of cells to accumulate Ca2+ into the TG-sensitive stores. Similarly, silencing of native TPC2 expression reduced thrombin-induced Ca2+ entry in MEG01 cells. In contrast, silencing of TPC1 expression was without effect either on TG or thrombin-stimulated Ca2+ entry both in MEG01 and HEK293 cells. Biotinylation analysis revealed that TPC1 and TPC2 are expressed in internal membranes. Finally, co-immunoprecipitation experiments indicated that endogenously expressed TPC2, but not TPC1, associates with STIM1 and Orai1, but not with TRPC1, in MEG01 cells with depleted intracellular Ca2+ stores, but not in resting cells. These results provide strong evidence for the modulation of SOCE by TPC2 involving de novo association between TPC2 and STIM1, as well as Orai1, in human cells

TRPC Channels: Dysregulation and Ca2+ Mishandling in Ischemic Heart Disease

Transient receptor potential canonical (TRPC) channels are ubiquitously expressed in excitable and non-excitable cardiac cells where they sense and respond to a wide variety of physical and chemical stimuli. As other TRP channels, TRPC channels may form homo or heterotetramericion channels, and they can associate with other membrane receptors and ion channels to regulate intracellular calcium concentration. Dysfunctions of TRPC channels are involved in many types of cardiovascular diseases. Significant increase in the expression of different TRPC isoforms was observed in different animal models of heart infarcts and in vitro experimental models of ischemia and reperfusion. TRPC channel-mediated increase of the intracellular Ca2+ concentration seems to be required for the activation of the signaling pathway that plays minor roles in the healthy heart, but they are more relevant for cardiac responses to ischemia, such as the activation of different factors of transcription and cardiac hypertrophy, fibrosis, and angiogenesis. In this review, we highlight the current knowledge regarding TRPC implication in different cellular processes related to ischemia and reperfusion and to heart infarction

Analysis of spatial and temporal evolution of regularity maps during ventricular fibrillation

The analysis of cardiac mapping allows investigating the structure of ventricular fibrillation (VF). This work analyzes regions of interest (ROI) on cardiac maps obtained from the regularity analysis of VF records, providing information about signal regularity at each time instant and its spatial distribution. Cardiac registers were obtained using a 240- electrodes matrix located on left ventricle of isolated rabbit heart. A Langendorff system was used to maintain the heart perfusion. VF was induced by increased frequencies. Two groups of records were considered: control (G1: without physical training, N=10), and trained (G2, N=9). Records were processed in consecutive 4-second segments. Regularity index (RI) was obtained for every segment and channel. RI is a measure of similarity degree among local activation waves for every channel. A map with the RI value of each channel was computed for the 82 register segments. To analyze the spatial distribution of RI, a threshold value was determined experimentally and applied to the map in order to obtain the ROI. Two parameters were calculated: ROI spatial number (ROIsn, a measure of spatial fragmentation), and ROI spatial area (ROIsa, the percentage of area map occupied by ROI). In case of the time course of ROI, two additional parameters were computed: the number of electrodes which value had changed respect to the threshold in two consecutive maps (ROIen, which is related with the change size), and the cumulative absolute differences of RI values for the electrodes which are changed (ROIed). Obtained results for spatial analysis show that the number of ROI is lower for trained rabbits (ROIsn; G1: 4.465±1.120; G2: 2.,227±0.623; p<0.001), but ROI spatial area is greater than the control group (ROIsa; G1: 76.235±5.355%; G2: 88.163±2.885%; p<0.001). Time-course analysis shows that more electrodes change between consecutive maps in the control group (ROIen, G1: 22.455±6.702; G2: 13.877±2.485; p<0.001). No significant differences were found for ROIed (G1: 18.509±6.932; G2: 18.619±4.196; n.s.). To conclude, ROI analysis on RI maps applied to trained and no trained rabbits groups shows that VF cardiac response is more irregular and spatially fragmented in no trained group. In addition, regularity maps are more stable with time in trained group

Relación entre el espectro y la regularidad en la señal de fibrilación ventricular modificada por el ejercicio físico

El presente trabajo estudia las modificaciones intrínsecas que el ejercicio físico produce en la respuesta cardíaca durante la FV. Se han calculado dos parámetros relacionados con el espectro de la señal (FD: frecuencia dominante, y EN: energía normalizada), y otro relacionado con la regularidad de las OAL (IR: índice de regularidad), Se ha realizado un análisis de correlación entre los tres parámetros para valorar su grado de complementariedad. Se consideraron dos grupos de conejos: control (G1: sin entrenamiento, N=10) y entrenados (G2, N=9). Se utilizó un electrodo matricial de 240 canales localizado en ventrículo izquierdo de corazón aislado de conejo perfundido mediante un sistema de Langendorff. La FV se indujo por estimulación a frecuencias crecientes. Los resultados muestran que el grupo entrenado presenta una mayor regularidad de la señal (IR: G1: 0,757+-0,091; G2: 0,845+-0,084; p<0.001), así como menor FD (G1: 18.23±2.96Hz; G2: 14.13+-1.73Hz; p<0.001) y dispersión espectral (EN: G1: 0,138+-0.105; G2: 0,293+-0,176; p<0.001). El análisis de las relaciones entre parámetros muestra correlaciones significativas entre los parámetros para todos los casos excepto para IR y FD en G2, por lo que estos parámetros proporcionan información complementaria, ya que analizan aspectos diferentes de la señal como la morfología de las ondas de activación y su frecuencia. La existencia de correlación entre ambas para G1 puede ser debida a otras causas, tales como las modificaciones en ambos factores inducidas por la presencia de reentradas o colisiones entre frentes de activación.. Como conclusión, los resultados obtenidos sugieren que el entrenamiento físico produce una respuesta cardíaca más estable ante FV, debida a modificaciones intrínsecas en las características electrofisiológicas cardíacas

Structure of Portland Cement Pastes Blended with Sonicated Silica Fume

[EN] Application of power ultrasound to enhance dispersion of commercial densified silica fume leads to increased compressive strengths and refinement of the pore structure in mortars, compared with those that are untreated. This was attributed to the enhanced pozzolanic reactivity achieved by particle dispersion through sonication, leading to higher consumption of portlandite during curing, and formation of a calcium silicate hydrate gel with a higher degree of cross-linking than is identified in specimens with densified silica fume. This suggests that with the use of sonicated silica fume, it is possible to reduce the required quantity of admixture in blended cements to achieve specified performance, with the additional advantage of the formation of a highly densified structure and refined pore network, contributing to potential improvements in durability.This study was sponsored by the Ministerio de Ciencia e Innovacion of Spain (Project SILISONIC BIA-2007-63252 and research scholarships BES-2008-002440 and EEBB-2011-43847), the European regional development fund (FEDER), and the Universitat Politecnica de Valencia (Spain). Participation of SAB and JLP was funded by the Australian Research Council (ARC), including partial funding through the Particulate Fluids Processing Centre, a Special Research Centre of the ARC. The authors thank Dr. John Gehman for support in conducting the NMR experiments at the Bio21 Institute, University of Melbourne, Australia.Rodriguez Martinez, ED.; Bernal, SA.; Provis, JL.; Paya Bernabeu, JJ.; Monzó Balbuena, JM.; Borrachero Rosado, MV. (2012). Structure of Portland Cement Pastes Blended with Sonicated Silica Fume. Journal of Materials in Civil Engineering. 24:1295-1304. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000502S129513042

Modifications on regularity and spectrum of ventricular fibrillation signal induced by physical training

The objective of this work is to study the modifications on cardiac response during ventricular fibrillation (VF) induced by physical training. The analysis was performed in the frequency domain of VF, and the regularity of the signal was also considered. Two sets of records were acquired: control (G1: without physical training, N=10), and trained (G2, N=9). Cardiac registers were obtained using a 240-electrodes matrix located on left ventricle of isolated rabbit heart. A Langendorff system was used to maintain the heart perfusion. VF was induced by increased frequencies. To analyze the time course of VF, records were processed in 4-second segments. For every segment and channel, Welch periodogram with Hanning window, two non-overlapped sections and zero padding, was computed. Parameters considered in frequency domain are: dominant frequency (DF) and normalized energy (NE: spectral energy in the window DF±1Hz, normalized by spectral energy in 5-35Hz band). For every segment and channel, a regularity analysis of VF was performed, obtaining the regularity index (RI), which is a measure of similarity among local activation waves present in every channel. Mean values for the parameters (DF, NE and RI) of the whole set of electrodes were computed for every segment. Obtained results show that DF is lower for trained rabbits (G1: 18.234±1, 241Hz; G2: 14.370±0, 866Hz; p<0.001). NE is greater for this group (G1: 0.140±0.006; G2: 0.263±0.017; p<0.001), suggesting a greater spectral concentration around DF. Finally, a greater regularity has been observed in the fibrillation signal for trained group (IR, G1: 0.756±0.026; G2: 0.834±0.014; p<0.001). As a summary, the results suggest that both spectral characteristics and regularity of VF signal are clearly different for G1 and G2 groups. The trained group (G2) shows greater regularity, lower DF and spectral dispersion. These factors should be interpreted as a more stable cardiac response to V

Analysis of the influence of parasympathetic postganglionic neurons on cardiac response in ventricular fibrillation

Physical training modifies the sympathetic-vagal balance of autonomic nervous system. Previous studies have shown that such training also produces intrinsic modifications of cardiac electrophysiological properties in isolated heart during Ventricular Fibrillation (VF). Ten NZW trained rabbits were studied to test if the modifications are related to the activity of postganglionic parasympathetic neurons. Two records per subject were acquired during VF: before (G1) and after (G2) the infusion of atropine to inhibit the activity of neurons. Mapping records were obtained using a 240-channel electrode array located in the left ventricle of isolated heart (perfused by Langendorff system). VF was induced by stimulation at increasing frequencies. To analyze the time course of fibrillation, the records were processed in 4-second consecutive segments. For each channel and segment, the following parameters were computed: 1) Dominant Frequency (DF), obtained by the Welch periodogram b) Normalized Energy (NE) in a frequency band centered at the DF; c) Regularity Index (RI), which analyzes the similarity of local activation waves in every segment and channel; d) Coefficients of Variance of DF (CVDF), NE (CVNE) and RI (CVRI). For each segment, we obtained the average value of each of the parameters analyzed for all electrodes. The results are: a) DF (G1: 13.671 ± 0.509 Hz, G2: 14.783 ± 0.455 Hz), b) NE (G1: 0.398 ± 0.014; G2: 0.380 ± 0.013); c) RI (G1: 0.855 ± 0.017; G2: 0.865 ± 0.015), d) CVDF (G1: 0.109 ± 0.009; G2: 0.098 ± 0.008), e) CVNE (G1: 0.398 ± 0.014; G2: 0.380 ± 0.013 ) f) CVRI (G1: 0.084 ± 0.009; G2: 0.078 ± 0.008). None of these parameters showed significant differences between groups. Thus, the parasympathetic postganglionic neurons seem to have no effect on the cardiac response in VF due to physical training