Prospective international validation of the predisposition, infection, response and organ dysfunction (PIRO) clinical staging system among intensive care and general ward patients.

BACKGROUND: Stratifying patients with sepsis was the basis of the predisposition, infection, response and organ dysfunction (PIRO) concept, an attempt to resolve the heterogeneity in treatment response. The purpose of this study is to perform an independent validation of the PIRO staging system in an international cohort and explore its utility in the identification of patients in whom time to antibiotic treatment is particularly important. METHODS: Prospective international cohort study, conducted over a 6-month period in five Portuguese hospitals and one Australian institution. All consecutive adult patients admitted to selected wards or the intensive care, with infections that met the CDC criteria for lower respiratory tract, urinary, intra-abdominal and bloodstream infections were included. RESULTS: There were 1638 patients included in the study. Patients who died in hospital presented with a higher PIRO score (10 ± 3 vs 8 ± 4, p < 0.001). The observed mortality was 3%, 15%, 24% and 34% in stage I, II, III and IV, respectively, which was within the predicted intervals of the original model, except for stage IV patients that presented a lower mortality. The hospital survival rate was 84%. The application of the PIRO staging system to the validation cohort resulted in a positive predictive value of 97% for stage I, 91% for stage II, 85% for stage III and 66% for stage IV. The area under the receiver operating characteristics curve (AUROC) was 0.75 for the all cohort and 0.70 if only patients with bacteremia were considered. Patients in stage III and IV who did not have antibiotic therapy administered within the desired time frame had higher mortality rate than those who have timely administration of antibiotic. CONCLUSIONS: To our knowledge, this is the first external validation of this PIRO staging system and it performed well on different patient wards within the hospital and in different types of hospitals. Future studies could apply the PIRO system to decision-making about specific therapeutic interventions and enrollment in clinical trials based on disease stage.

Influence of cognitive impairment on the freezing of gait in non demented people with Parkinson's disease. / Influencia del deterioro cognitivo en la congelacion de la marcha en pacientes con enfermedad de Parkinson sin demencia.

INTRODUCTION: Freezing of gait (FOG) is a motor disturbance usually appearing in advanced Parkinson's disease (PD). Cognitive and executive function seems to play an important role in this phenomenon. AIM: To investigate if cognitive and kinematic parameters correlate with FOG in PD patients without dementia. PATIENTS AND METHODS: We conducted an observational cross-sectional study. Participants were classified in two groups: freezers and non-freezers. Clinical information was obtained by Hoehn and Yahr scale, Unified Parkinson's Disease Rating Scale and balance test of Short Physical Performance Battery. Cognitive function was evaluated using Minimental Examination and the Fuld Object Memory Evaluation; executive function was assessed with the Frontal Assessment Battery test. Battery kinematic parameters were assessed by means of gait speed, cadence, stride length and stride time. RESULTS: Twenty-five participants with PD without dementia completed the evaluation. Statistical significant differences between freezers and non-freezers were found in global cognition (p = 0,02), memory (p = 0,04), executive function (p = 0,04), cadence (p = 0,02), stride length (p = 0,04) and stride time (p = 0,01). CONCLUSION: Cognitive parameters may have an important contribution to the manifestation of freezing of gait in PD. These results may have important clinical implications for developing future non-pharmacological and cognitive interventions strategies targeted to PD patients with FOG.

TITLE: Influencia del deterioro cognitivo en la congelacion de la marcha en pacientes con enfermedad de Parkinson sin demencia.Introduccion. La congelacion de la marcha (CDM) es una alteracion motora que suele aparecer en estadios avanzados de la enfermedad de Parkinson (EP). Las funciones cognitivas y ejecutivas parecen tener un papel importante en la aparicion de este fenomeno. Objetivo. Investigar si los parametros cognitivos y cinematicos se correlacionan con la CDM en pacientes con EP sin demencia. Pacientes y metodos. Estudio observacional y transversal. Los participantes se clasificaron en dos grupos: con y sin CDM. La informacion clinica se obtuvo mediante la escala de Hoehn y Yahr, la Unified Parkinson's Disease Rating Scale y la prueba de equilibrio de la Short Physical Performance Battery. La funcion cognitiva se valoro con el miniexamen cognitivo y la Fuld Object Memory Evaluation, y la funcion ejecutiva, con la Frontal Assessment Battery. Los parametros cinematicos se valoraron mediante la velocidad de la marcha, la cadencia, la longitud del paso y el tiempo del paso. Resultados. Veinticinco participantes con EP sin demencia completaron el programa. Se encontraron diferencias estadisticamente significativas entre individuos con y sin CDM en cognicion global (p = 0,02), memoria (p = 0,04), funcion ejecutiva (p = 0,04), cadencia (p = 0,02), longitud del paso (p = 0,04) y tiempo del paso (p = 0,01). Conclusion. Diversos parametros cognitivos pueden contribuir de forma importante en la aparicion de la CDM en la EP. Estos resultados pueden tener implicaciones clinicas relevantes para el desarrollo de estrategias e intervenciones no farmacologicas y cognitivas dirigidas a pacientes con EP y con CDM.

The influence of winter and summer seasons on physical fitness in aged population.

Epidemiological studies have described the association between physical fitness and health. Few have reported the impact of seasonal variation on fitness determinants, in elderly. We investigated the effects of summer and winter environmental conditions on physical fitness, in both exercise and non-exercise elders. 371 non-institutionalized older adults (74.1% female; 78.4 ±â€¯5.3 years) randomly recruited from a total sample of 1338 subjects from north of Portugal, were prospectively followed during 1 year and 3 assessments were performed - April (baseline), October (summer season) and April (winter season). Four groups were defined, according to reported habits of exercising: Exercise (EG); Winter Exercise (WG); and Summer Exercise (SG); non-Exercise (nEG). Muscle strength was assessed with handgrip and isometric knee extension test, and aerobic capacity with the 6 min walking test. Repeated measures ANOVA with two between-subjects factors were run for independent variables, considering a three Time points. Significance set at p < .05. Findings show that: (1) men were fitter than women; (2) EG showed better results than nEG (p = .000), but not different than WG or SG, (3) nEG physical fitness was not significantly different from WG and SG; (4) SG and WG showed similar results; (5) there was significant group-by-time interaction for all variables in study. Among elderly, the regular physical exercise determined better cardiorespiratory fitness and levels of strength compared to individuals that were not exercising, however, no season impact was observed. Independently of exercising mode, regular, seasonal or not exercising, the pattern of changes in physical fitness throughout the year was similar.

Effect of initial periodontal therapy on gingival crevicular fluid cytokine profile in subjects with chronic periodontitis.

Cytokines are thought to play an important role in the pathogenesis of periodontal disease. Because periodontal disease is known for its inhomogeneous distribution within the dentition, it is unclear to what extent the detection of various cytokines at different sites correlates with presence of disease. We evaluated whether levels of 12 cytokines in gingival crevicular fluid (GCF) discriminated periodontally diseased sites from healthy ones, or periodontally diseased persons from healthy ones, and assessed the impact of nonsurgical periodontal therapy on these readings. This study included 20 periodontally healthy persons (H) and 24 patients with chronic periodontitis (P). In every participant, we measured the plaque index, gingival index, probing pocket depth (PD), bleeding on probing, and recession at six sites of every tooth. GCF was collected with Durapore® filter strips from two healthy sites (PD<4 mm; HH) in group H, and from two periodontally diseased sites (PD≥5 mm; PP) and two periodontally healthy sites (PD≤3 mm; PH) in group P. The periodontally diseased participants underwent comprehensive nonsurgical periodontal therapy including deep scaling and root planing under local anesthesia. In these participants, GCF samples were again collected at the same sites 1 and 3 months after therapy. Twelve cytokines (il-1ß, il-1ra, il-6, il-8, il-17, b-fgf, g-csf, gm-csf, ifn-γ, mip-1ß, vegf, and tnf-α) were assessed using the Bio-Plex suspension array system. Mean plaque index, gingival index, bleeding on probing, PD, and recession were significantly different between groups H and P. Differences between PP and PH sites were not significant for any of the cytokines. Il-1ra, il-6, il-17, b-fgf, gm-csf, mip-1ß, and tnf-α differed significantly between HH sites and both PH and PP sites, whereas il-8 was significantly higher only at PP sites. Periodontal treatment increased gm-csf and decreased il-1ra levels in PP sites. Il-1ra, il-6, il-8, il-17, b-fgf, gm-csf, mip-1ß, and tnf-α identified patients with chronic periodontitis, rather than diseased sites, suggesting a generalized inflammatory state that is not limited to clinically diseased sites only.

Lack of GSK3ß activation and modulation of synaptic plasticity by dopamine in 5-HT1A-receptor KO mice.

Psychiatric disorders are associated with excitation-inhibition (E-I) balance impairment in the prefrontal cortex. However, how the E-I balance is regulated is poorly known. The E-I balance of neuronal networks is linked to the action of numerous neuromodulators such as dopamine and 5-HT. We investigated the role of D2-receptors in tuning the E-I balance in a mouse model of anxiety, the 5-HT1A-receptor KO mice. We focused on synaptic plasticity of excitation and inhibition on layer 5 pyramidal neurons. We show that D2-receptor activation decreases the excitation and favors HFS-induced LTD of excitatory synapses via the activation of GSK3ß. This effect is absent in 5-HT1A-receptor KO mice. Our data show that the fine control of excitatory transmission by GSK3ß requires recruitment of D2-receptors and depends on the presence of 5-HT1A-receptors. In psychiatric disorders in which the number of 5-HT1A-receptors decreased, therapies should reconsider how serotonin and dopamine receptors interact and control neuronal network activity.

Influence of cognitive impairment on fall risk among elderly nursing home residents.

BACKGROUND: Information relating the severity of cognitive decline to the fall risk in institutionalized older adults is still scarce. This study aims to identify potential fall risk factors (medications, behavior, motor function, and neuropsychological disturbances) depending on the severity of cognitive impairment in nursing home residents. METHODS: A total of 1,167 nursing home residents (mean age 81.44 ± 8.26 years; 66.4% women) participated in the study. According to the MEC, (the Spanish version of the Mini-Mental State Examination) three levels of cognitive impairment were established: mild (20-24) "MCI", moderate (14-19) "MOCI", and severe (≤14) "SCI". Scores above 24 points indicated the absence cognitive impairment (NCI). Information regarding fall history and fall risk during the previous year was collected using standardized questionnaires and tests. RESULTS: Sixty falls (34%) were registered among NCI participants and 417 (43%) among people with cognitive impairment (MCI: 35%; MOCI: 40%; SCI: 50%). A different fall risk model was observed for MCI, MOCI, SCI, and NCI patients. The results imply that the higher the level of cognitive impairment, the greater the number of falls (F1,481 = 113.852; Sig = 0.015), although the level of significance was not maintained when MOCI and SCI participants were compared. Depression, neuropsychiatric disturbances, autonomy constraints in daily life activity performance, and low functional mobility were factors closely associated with fall risk. CONCLUSION: This study provides evidence indicating that fall risk factors do not hold a direct correlation with the level of cognitive impairment among elderly nursing home care residents.

Systemic Biomarkers in 2-Phase Antibiotic Periodontal Treatment: A Randomized Clinical Trial.

Accumulating evidence suggests that periodontal infections may have an impact on systemic health. In patients with untreated periodontitis, very high values for several inflammatory markers in serum are expressed simultaneously. We investigated to what extent these peak values change after nonsurgical and surgical periodontal treatment, with adjunctive antibiotics administered during the first or the second treatment phase. In a single-center, randomized, placebo-controlled, and double-masked clinical trial, 80 patients with chronic or aggressive periodontitis were randomized into 2 treatment groups: group A, receiving systemic amoxicillin and metronidazole during the first, nonsurgical phase of periodontal therapy (phase 1), and group B, receiving the antibiotics during the second, surgical phase (phase 2). Serum samples were obtained at baseline (BL), 3 mo after phase 1 (M3), and 6 and 12 mo after phase 2 (M6, M12). Samples were evaluated for 15 cytokines and 9 acute-phase proteins using the Bio-Plex bead array multianalyte detection system. For each analyte, peak values were defined as greater than mean +2 SD of measurements found in 40 periodontally healthy persons. Sixty-six patients showed a peak value of at least 1 analyte at BL. At M12, the number of these patients was only 36 (P = 0.0002). This decrease was stronger in group A (BL: 35, M12: 19, P = 0.0009) than in group B (BL: 31, M12: 17, P = 0.14). Twenty patients displayed peak values of at least 4 biomarkers at BL. The nonsurgical therapy delivered in the first phase reduced most of these peaks (group A, BL: 9, M3: 4, P = 0.17; group B, BL: 11, M3: 2, P = 0.01), irrespective of adjunctive antibiotics. The reductions obtained at M3 were maintained until M12 in both groups. Initial, nonsurgical periodontal therapy reduced the incidence of peak levels of inflammatory markers. Antibiotics and further surgical therapy did not enhance the effect (Clinicaltrials.gov NCT02197260).

Effects of two different exercise programs on gait parameters in individuals with Parkinson's disease: a pilot study.

To date, little attempt has been made to compare or evaluate the effects of different physical exercise programs on gait disorders in people with Parkinson's disease (PD). This pilot study is aimed at obtaining preliminary data of the effects of two different exercise programs on gait parameters in people with PD by means of a biomechanical three-dimensional motion analysis. Twenty-five individuals with idiopathic PD participated either in a land-based (LB) or in a LB plus water-based (LWB) exercise program for 16 weeks. The efficacy of both exercise programs was quantified by means of a biomechanical gait analysis from which spatiotemporal and sagittal plane kinetic (gait speed, stride length, cadence, stride time, simple support time, double support time) and kinematic (angles of the hip, knee, and ankle joints) variables were recorded. Once the intervention ended, significant changes were observed in stride length and single/double support time variables in all the patients. The intergroup analysis revealed the existence of significant differences only in the gait Speed and hip Angle parameters. Few significant improvements in the amplitude of lower limb joints were found. These results suggest that land-based and land-plus-water-based exercise programs can be considered as a useful physical rehabilitation alternative, both equally capable of improving gait impairment on Parkinson's disease.

Mejora del equilibrio en los enfermos de Parkinson mediante el ejercicio calisténico-recreativo: un estudio piloto / Improvement of balance in Parkinson's disease patients using calisthenics and recreational physical exercise: a pilot study

Introducción. La enfermedad de Parkinson (EP), presenta unos síntomas característicos que afectan al movimiento voluntario, y entre los que destaca una reducida capacidad de equilibrio. El propósito de este estudio piloto fue determinar los efectos que sobre la misma tiene la realización de un programa de ejercicio calisténico-recreativo de corta duración. Material y métodos. Un total de 23 pacientes con una edad media de 73±8,4 años y un nivel de afectación de 2,17±0,7 (Hoehn & Yahr Staging Scale), desarrollaron un programa de ejercicio calisténico-recreativo, a razón de 2 sesiones de una hora semanales, durante 7 semanas. La prueba de equilibrio de la batería Short Physical Performance (compuesto por las pruebas Side by Side; Semitandem Stand y Tandem Stand), fue realizada para determinar los efectos de la intervención sobre esta capacidad. Resultados. Todos los participantes finalizaron el estudio, desarrollándose un total de 14 sesiones. No se observaron diferencias significativas en la capacidad de equilibrio a juzgar por la diferencia entre la puntuación inicial y final obtenida en la puntuación total de las pruebas realizadas (de 2,9 a 3,1 puntos). Al comparar el tiempo total alcanzado en cada prueba por separado, se pudo apreciar que los participantes incrementaron su nivel de equilibrio en cada una de las mismas, si bien las diferencias solo se mostraron significativas para la prueba Tandem Stand (p=0,011). Conclusión. Un programa de ejercicio calisténico-recreativo de corta duración, es bien tolerado por los pacientes con Parkinson, aunque sus efectos sobre el equilibrio parecen no ser de gran magnitud (AU)

Introduction. Parkinson's disease (PD) has some characteristic symptoms that affect voluntary movement. Standing out among them is reduced balance capacity. This pilot study aimed to describe the effects on balance capacity of persons with PD of a short calisthenics and recreational physical exercise program. Material and methods. Twenty-three patients (Hoehn & Yahr Staging Scale) with a mean age of 73±8.4 years and 2.17±0.7 severity of involvement participated in a two weekly, one hour session program. The program was based on the performance of calisthenics and recreational exercises. The program included two sessions per week of one hour each, over a seven week period. The balance test included in the «Short Physical Performance Battery» (composed of the «Side by Side» test; «Semitandem Stand» and «Tandem Stand») was performed to assess the effects of the intervention on the participant's balance capacity. Results. All the participants finished the study, participating in a total of 14 sessions. Considering the difference between the initial and final score obtained in the total score of the tests performed (from 2.9 to 3.1 points), no significant differences were observed. When total time reached in each test was compared separately, it could be seen that the participants increased their balance level in each one of them. However, the differences were only significant for the «Tandem Stand» test (P=.011). Conclusion. A short calisthenics-recreational exercise training program is well-tolerated by patients with Parkinson's Disease. However, its effects on their balance capacity do not seem to be very great (AU)

Influence of the cognitive impairment level on the performance of the Timed "Up & Go" Test (TUG) in elderly institutionalized people.

The purpose of this study was to determine clinical variables influence (comorbid medical condition, functional independence, depressive and neuropsychiatric symptoms) on the performance of the TUG, taking into account the level of cognitive impairment in elderly institutionalized people. A cross-sectional analysis of 405 sedentary older adults living in rural home care facilities was carried out. All the participants performed the TUG and the Mini Mental State Examination (MMSE). Those who were screened positive for cognitive impairment carried out a battery of specific test aimed to assess their functional independence (Katz Index (KI)), memory function (Fuld Object Memory Evaluation (FOME)), depressive symptoms (Cornell Scale) and neuropsychiatric disturbances (Neuropsychiatric Inventory (NPI)). Applying multiple linear regression, TUG was associated with age (ß=0.161, p<0.001), MMSE (ß=-0.013, p<0.001) and KI (ß=0.621, p<0.001). According to the defined regression model, it was noticed that the higher the level of cognitive impairment, the lower the adjustment of the model (R(2)=0.593; R(2)=0.493; R(2)=0.478). In conclusion, it seems that the performance of the TUG in institutionalized elderly people who screened positive for dementia, is mainly influenced by their functional independence and their age. Comorbid medical condition, depressive and neuropsychiatric symptoms do not seem to show any association, regardless of the level of cognitive impairment.

The Senior Fitness Test as a functional measure in Parkinson's disease: a pilot study.

OBJECTIVE: This pilot study aimed to determine if the Senior Fitness Test (SFT) battery can be applied to subjects with Parkinson's disease (PD) and whether its results can be reliable indicators of disease severity. METHODS: Thirty people with mild to moderate PD performed the SFT and completed the Parkinson's Disease Questionnaire (PDQ-39) and the Unified Parkinson's Disease Rating Scale (UPDRS). To compare the metric properties of the SFT battery with the UPDRS and the PDQ-39, a SFT sum-score was created. RESULTS: The tests that compose the SFT were successfully completed by the patients, except for the "Two-Minute Step Test" (2MST), which had to be shortened. We observed a strong correlation among the SFT's sum-score and the total scores of the PDQ-39 and the UPDRS. Some correlation was also found among the SFT's sum-score and the analyzed subscales, except for those assessing mental and cognitive levels. CONCLUSION: The SFT appears to be a useful tool to assess functional fitness in people with PD: it can be carried out in the clinical setting albeit with some minor modifications. However, its validity as an indicator of disease severity remains to be confirmed.

Assessment of Bradykinesia in Parkinson's disease patients through a multi-parametric system.

The aim of this paper is to describe and present the results of the automatic detection and assessment of bradykinesia in motor disease patients using wireless, wearable accelerometers. The current work is related to a module of the PERFORM system, a FP7 project from the European Commission, that aims at providing an innovative and reliable tool, able to evaluate, monitor and manage patients suffering from Parkinson's disease. The assessment procedure was carried out through a developed C# library that detects the activities of the patient using an activity recognition algorithm and classifies the data using a Support Vector Machine trained with data coming from previous test phases. The accuracy between the output of the automatic detection and the evaluation of the clinician both expressed with the Unified Parkinson's disease Rating Scale, presents an average value of [68.3 ± 8.9]%. A meta-analysis algorithm is used in order to improve the accuracy to an average value of [74.4 ± 14.9]%. Future work will include a personalized training of the classifiers in order to achieve a higher level of accuracy.

Gait assessment in Parkinson's disease patients through a network of wearable accelerometers in unsupervised environments.

Parkinson's disease (PD) predominantly alters the motor performance of the affected individuals. In particular, the loss of dopaminergic neurons compromises the speed, the automaticity and fluidity of movements. As the disease evolves, PD patient's motion becomes slower and tremoric and the response to medication fluctuates along the day. In addition, the presence of involuntary movements deteriorates voluntary movement in advanced state of the disease. These changes in the motion can be detected by studying the variation of the signals recorded by accelerometers attached in the limbs and belt of the patients. The analysis of the most significant changes in these signals make possible to build an individualized motor profile of the disease, allowing doctors to personalize the medication intakes and consequently improving the response of the patient to the treatment. Several works have been done in a laboratory and supervised environments providing solid results; this work focused on the design of unsupervised method for the assessment of gait in PD patients. The development of a reliable quantitative tool for long-term monitoring of PD symptoms would allow the accurate detection of the clinical status during the different PD stages and the evaluation of motor complications. Besides, it would be very useful both for routine clinical care as well as for novel therapies testing.

A comprehensive motor symptom monitoring and management system: the bradykinesia case.

The current work describes a methodology to automatically detect the severity of bradykinesia in motor disease patients using wireless, wearable accelerometers. This methodology was tested with cross validation through a sample of 20 Parkinson's disease patients. The assessment of methodology was carried out through some daily living activities which were detected using an activity recognition algorithm. The Unified Parkinson's Disease Rating Scale (UPDRS) severity classification of the algorithm coincides between 70 and 86% from that of a trained neurologist depending on the classifier used. These severities were calculated for 5 second segments of the signal with 50% of overlap. A bradykinesia profiler is also presented in this work. This profiler removes the overlap of the segments and calculates the confidence of the resulting events. It also calculates average severity, duration and symmetry values for those events. The profiler has been tested with a bogus dataset. Future work includes better training for the severity classifier with a larger sample and testing the profiler with real, longterm patient data in a projected pilot phase in three European hospitals.

Nucleoplasmic reticulum is not essential in nuclear calcium signalling mediated by cyclic ADPribose in primary neurons.

Nuclear calcium regulation is essential for controlling nuclear processes such as gene expression. Recent studies, mostly performed on immortalized or transformed cell lines, reported the presence of a nucleoplasmic reticulum (NR). It has been suggested that NR acts as a storage organelle having an important role in nuclear Ca2+ signalling. However, whether NR is present and necessary in primary neurons for generation of nuclear Ca2+ signalling has never been investigated. Here, we show, by confocal microscopy and by electronic microscopy, that nuclei in intact neurons or isolated nuclei are not endowed with NR. Finally, our experiments performed on isolated nuclei from Aplysia giant neurons show that the nuclear envelope acts as a functional Ca2+ store which can be mobilized by the second messenger cyclic ADPribose to elicit a nucleoplasmic Ca2+ elevation. Our study provides evidence that nuclear Ca2+ signals can be independent of the presence of NR in neurons.

Islet-cell-to-cell communication as basis for normal insulin secretion.

The emergence of pancreatic islets has necessitated the development of a signalling system for the intra- and inter-islet coordination of beta cells. With evolution, this system has evolved into a complex regulatory network of partially cross-talking pathways, whereby individual cells sense the state of activity of their neighbours and, accordingly, regulate their own level of functioning. A consistent feature of this network in vertebrates is the expression of connexin (Cx)-36-made cell-to-cell channels, which cluster at gap junction domains of the cell membrane, and which adjacent beta cells use to share cytoplasmic ions and small metabolites within individual islets. This chapter reviews what is known about Cx36, and the mechanism whereby this beta-cell connexin significantly regulates insulin secretion. It further outlines other less established functions of the protein and evaluates its potential relevance for the development of novel therapeutic approaches to diabetes.

Beta cells preferentially exchange cationic molecules via connexin 36 gap junction channels.

AIMS/HYPOTHESIS: Pancreatic beta cells are connected by gap junction channels made of connexin 36 (Cx36), which permit intercellular exchanges of current-carrying ions (ionic coupling) and other molecules (metabolic coupling). Previous studies have suggested that ionic coupling may extend to larger regions of pancreatic islets than metabolic coupling. The aim of the present study was to investigate whether this apparent discrepancy reflects a difference in the sensitivity of the techniques used to evaluate beta cell communication or a specific characteristic of the Cx36 channels themselves. METHODS: We microinjected several gap junction tracers, differing in size and charge, into individual insulin-producing cells and evaluated their intercellular exchange either within intact islets of control, knockout and transgenic mice featuring beta cells with various levels of Cx36, or in cultures of wild-type and Cx36-transfected MIN6 cells. RESULTS: We found that (1) Cx36 channels favour the exchange of cations and larger positively charged molecules between beta cells at the expense of anionic molecules; (2) this exchange occurs across sizable portions of pancreatic islets; and (3) during glibenclamide (known as glyburide in the USA and Canada) stimulation beta cell coupling increases to an extent that varies for different gap junction-permeant molecules. CONCLUSIONS/INTERPRETATION: The data show that beta cells are extensively coupled within pancreatic islets via exchanges of mostly positively charged molecules across Cx36 channels. These exchanges selectively increase during stimulation of insulin secretion. The identification of this permselectivity is expected to facilitate the identification of endogenous permeant molecules and of the mechanism whereby Cx36 signalling significantly contributes to the modulation of insulin secretion.

Specific Ca2+ signaling evoked by cholecystokinin and acetylcholine: the roles of NAADP, cADPR, and IP3.

In order to control cell functions, hormones and neurotransmitters generate an amazing diversity of Ca2+ signals such as local and global Ca2+ elevations and also Ca2+ oscillations. In pancreatic acinar cells, cholecystokinin (CCK) stimulates secretion of digestive enzyme and promotes cell growth, whereas acetylcholine (ACh) essentially triggers enzyme secretion. Pancreatic acinar cells are a classic model for the study of CCK- and ACh-evoked specific Ca2+ signals. In addition to inositol 1,4,5 trisphosphate (IP3), recent studies have shown that cyclic ADPribose (cADPr) and nicotinic acid adenine dinucleotide phosphate (NAADP) release Ca2+ in pancreatic acinar cells. Moreover, it has also been shown that both ACh and CCK trigger Ca2+ spikes by co-activation of IP3 and ryanodine receptors but by different means. ACh uses IP3 and Ca2+, whereas CCK uses cADPr and NAADP. In addition, CCK activates phospholipase A2 and D. The concept emerging from these studies is that agonist-specific Ca2+ signals in a single target cell are generated by combination of different intracellular messengers.

Bombesin-induced cytosolic Ca2+ spiking in pancreatic acinar cells depends on cyclic ADP-ribose and ryanodine receptors.

Different hormones and neurotransmitters, using Ca2+ as their intracellular messenger, can generate specific cytosolic Ca2+ signals in different parts of a cell. In mouse pancreatic acinar cells, cytosolic Ca2+ oscillations are triggered by activation of acetylcholine (ACh), cholecystokinin (CCK) and bombesin receptors. Low concentrations of these three agonists all induce local Ca(2+)spikes, but in the case of bombesin and CCK these spikes can also trigger global Ca2+ signals. Here we monitor cytosolic Ca2+ oscillations induced by low (2-5 pM) concentrations of bombesin and show that, like ACh- and CCK-induced oscillations, the bombesin-elicited responses are inhibited by ryanodine(50 microM). We then demonstrate that, like CCK- but unlike ACh-induced oscillations, the responses to bombesin are abolished by intracellular infusion of the cyclic ADP ribose (cADPr) antagonist 8-NH2-cADPr (20 microM). We conclude that in mouse pancreatic acinar cells, bombesin, CCK and ACh all produce local Ca2+ spikes by recruiting common oscillator units composed of ryanodine and inositol trisphosphate receptors. However, bombesin and CCK also recruit cADPr receptors, which may account for the global Ca2+ signals that can be evoked by these two agonists. Our new results indicate that each Ca2+ -mobilizing agonist, acting on mouse pancreatic acinar cells, recruits a unique combination of intracellular Ca2+ channels.

Two different but converging messenger pathways to intracellular Ca(2+) release: the roles of nicotinic acid adenine dinucleotide phosphate, cyclic ADP-ribose and inositol trisphosphate.

Hormones and neurotransmitters mobilize Ca(2+) from the endoplasmic reticulum via inositol trisphosphate (IP(3)) receptors, but how a single target cell encodes different extracellular signals to generate specific cytosolic Ca(2+) responses is unknown. In pancreatic acinar cells, acetylcholine evokes local Ca(2+) spiking in the apical granular pole, whereas cholecystokinin elicits a mixture of local and global cytosolic Ca(2+) signals. We show that IP(3), cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate (NAADP) evoke cytosolic Ca(2+) spiking by activating common oscillator units composed of IP(3) and ryanodine receptors. Acetylcholine activation of these common oscillator units is triggered via IP(3) receptors, whereas cholecystokinin responses are triggered via a different but converging pathway with NAADP and cyclic ADP-ribose receptors. Cholecystokinin potentiates the response to acetylcholine, making it global rather than local, an effect mediated specifically by cyclic ADP-ribose receptors. In the apical pole there is a common early activation site for Ca(2+) release, indicating that the three types of Ca(2+) release channels are clustered together and that the appropriate receptors are selected at the earliest step of signal generation.