378 research outputs found
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
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
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
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
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