Consumer e-health education in HIV/AIDS: a pilot study of a web-based video workshop

BACKGROUND: Members of the HIV/AIDS community are known to use web-based tools to support learning about treatment issues. Initial research indicated components such as message forums or web-based documentation were effectively used by persons with HIV/AIDS. Video has also shown promise as a technology to aid consumer health education. However, no research has been published thus far investigating the impact of web-based environments combining these components in an educational workshop format. METHODS: In this qualitative study HIV/AIDS community members provided feedback on an integrated web-based consumer health education environment. Participants were recruited through organizations that serve the HIV/AIDS community located in Toronto, Canada. Demographics, data on Internet use, including messages exchanged in the study environment were collected. A group interview provided feedback on usability of the study environment, preferences for information formats, use of the message forum, and other sources for learning about treatment information. RESULTS: In this pilot study analysis of the posted messages did not demonstrate use for learning of the workshop content. Participants did not generally find the environment of value for learning about treatment information. However, participants did share how they were meeting these needs. It was indicated that a combination of resources are being used to find and discuss treatment information, including in-person sources. CONCLUSION: More research on the ways in which treatment information needs are being met by HIV/AIDS community members and how technology fits in this process is necessary before investing large amounts of money into web-based interventions. Although this study had a limited number of participants, the findings were unexpected and, therefore, of interest to those who intend to implement online consumer health education initiatives or interventions

Source and Action of Pituitary Adenylate Cyclase-Activating Polypeptide in Guinea Pig Intrinsic Cardiac Ganglia

AbstractThe mammalian parasympathetic cardiac ganglia form a complex intrinsic cardiac nervous system presumed to contain multiple neuron types and are innervated by extrinsic fibers from multiple sources, each containing specific neurotransmitters and neuropeptides. In the guinea pig, the preganglionic parasympathetic cholinergic fibers contain the neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), and essentially all cardiac neurons express the PACAP selective PAC1 receptor. Application of exogenous PACAP depolarizes and enhances the excitability of guinea pig cardiac neurons. The mechanism by which PACAP enhances excitability is not established. However, Ca2+ influx through PACAP-activated nonselective cation channels is required for the PACAP-induced increase in excitability of guinea pig cardiac neurons. In addition, a PACAP-induced shift in the voltage dependence of activation of the cyclic nucleotidegated, hyperpolarization-activated current, Ih, most likely participates in the peptide-induced increase in neuronal excitability. The release of endogenous PACAP by repetitive stimulation of preganglionic fibers in vitro contributes to the generation of a slow excitatory postsynaptic potential and also can enhance cardiac neuron excitability. We hypothesize that PACAP released during ongoing vagal activity may regulate cardiac neuron excitability in vivo. [Tzu Chi Med J 2008;20(1):11–18

Ca\u3csup\u3e2+\u3c/sup\u3e influx, but not Ca\u3csup\u3e2+\u3c/sup\u3e release from internal stores, is required for the PACAP-induced increase in excitability in guinea pig intracardiac neurons

Mechanisms modulating the pituitary adenylate cyclase activating polypeptide (PACAP)-induced increase in excitability have been studied using dissociated guinea pig intrinsic cardiac neurons and intact ganglion preparations. Measurements of intracellular calcium (Ca ) with the fluorescent Ca indicator dye fluo-3 indicated that neither PACAP nor vasoactive intestinal polypeptide (VIP) at either 100 nM or 1 μM produced a discernible elevation of intracellular Ca in dissociated intracardiac neurons. For neurons in ganglion whole mount preparations kept in control bath solution, local application of PACAP significantly increased excitability, as indicated by the number of action potentials generated by long depolarizing current pulses. However, in a Ca -deficient solution in which external Ca was replaced by Mg or when cells were bathed in control solution containing 200 μM Cd , PACAP did not enhance action potential firing. In contrast, in a Ca -deficient solution with Ca replaced by strontium (Sr ), PACAP increased excitability. PACAP increased excitability in cells treated with a combination of 20 μM ryanodine and 10 mM caffeine to interrupt release of Ca from internal stores. Experiments using fluo-3 showed that ryanodine/caffeine pretreatment eliminated subsequent caffeine-induced Ca release from intracellular stores, whereas exposure to the Ca -deficient solution did not. In dissociated intracardiac neurons voltage clamped with the perforated patch recording technique, 100 nM PACAP decreased the voltage-dependent barium current (I ). These results show that, in the guinea pig intracardiac neurons, the PACAP-induced increase in excitability apparently requires Ca influx through Cd -sensitive calcium permeable channels other than voltage-dependent Ca channels, but not Ca release from internal stores. Copyright © 2006 The American Physiological Society. 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ 2+ B

Calcium influx through channels other than voltage-dependent calcium channels is critical to the pituitary adenylate cyclase-activating polypeptide-induced increase in excitability in guinea pig cardiac neurons

Pituitary adenylate cyclase-activating polypeptide (PACAP) effects on intracellular calcium ([Ca ] ) and excitability have been studied in adult guinea pig intracardiac neurons. PACAP increased excitability, but did not elicit Ca release from intracellular stores. Exposure to a Ca -deficient solution did not deplete [Ca ] stores but did eliminate the PACAP-induced increase in excitability. We postulate that Ca influx is required for the PACAP-induced increase in excitability. © 2006 New York Academy of Sciences. 2+ 2+ 2+ 2+ 2+ i

Somatic ATP release from guinea pig sympathetic neurons does not require calcium-induced calcium release from internal stores

Prior studies indicated that a Ca2+-dependent release of ATP can be initiated from the soma of sympathetic neurons dissociated from guinea pig stellate ganglia. Previous studies also indicated that Ca2+-induced Ca2+ release (CICR) can modulate membrane excitability in these same neurons. As Ca2+ release from internal stores is thought to support somatodendritic transmitter release in other neurons, the present study investigated whether CICR is essential for somatic ATP release from dissociated sympathetic neurons. Caffeine increased intracellular Ca2+ and activated two inward currents: a slow inward current (SIC) in 85% of cells, and multiple faster inward currents [asynchronous transient inward currents (ASTICs)] in 40% of cells voltage-clamped to negative potentials. Caffeine evoked both currents when cells were bathed in a Ca2+-deficient solution, indicating that both were initiated by Ca2+ release from ryanodine-sensitive stores in the endoplasmic reticulum. Sodium influx contributed to generation of both SICs and ASTICs, but only ASTICs were inhibited by the presence of the P2X receptor blocker PPADs. Thus ASTICs, but not SICs, resulted from an ATP activation of P2X receptors. Ionomycin induced ASTICs in a Ca2+-containing solution, but not when it was applied in a Ca2+-deficient solution, demonstrating the key requirement for external Ca2+ in initiating ASTICs by ionomycin. Pretreatment with drugs to deplete the internal stores of Ca2+ did not block the ability of ionomycin or long depolarizing voltage steps to initiate ASTICs. Although a caffeine-induced release of Ca2+ from internal stores can elicit both SICs and ASTICs in dissociated sympathetic neurons, CICR is not required for the somatic release of ATP

Pituitary adenylate cyclase 1 receptor internalization and endosomal signaling mediate the pituitary adenylate cyclase activating polypeptide-induced increase in guinea pig cardiac neuron excitability

After G-protein-coupled receptor activation and signaling at the plasma membrane, the receptor complex is often rapidly internalized via endocytic vesicles for trafficking into various intracellular compartments and pathways. The formation of signaling endosomes is recognized as a mechanism that produces sustained intracellular signals that may be distinct from those generated at the cell surface for cellular responses including growth, differentiation, and survival. Pituitary adenylate cyclase activating polypeptide (PACAP; Adcyapl) is a potent neurotransmitter/neurotrophic peptide and mediates its diverse cellular functions in part through internalization of its cognate G-protein-coupled PAC1 receptor (PAC1R; Adcyaplrl). In the present study, we examined whether PAC1R endocytosis participates in the regulation of neuronal excitability. Although PACAP increased excitability in 90% of guinea pig cardiac neurons, pretreatment with Pitstop 2 or dynasore to inhibit clathrin and dynamin I/II, respectively, suppressed the PACAP effect. Subsequent addition of inhibitor after the PACAP-induced increase in excitability developed gradually attenuated excitability with no changes in action potential properties. Likewise, the PACAP-induced increase in excitability was markedly decreased at ambient temperature. Receptor trafficking studies with GFP-PAC1 cell lines demonstrated the efficacy of Pitstop 2, dynasore, and low temperatures at suppressing PAC1R endocytosis. In contrast, brefeldin A pretreatments to disrupt Golgi vesicle trafficking did not blunt the PACAP effect, and PACAP/PACIR signaling still increased neuronal cAMP production even with endocytic blockade. Our results demonstrate that PACAP/PAC1R complex endocytosis is a key step for the PACAP modulation of cardiac neuron excitability. © 2013 the authors

Activation of MEK/ERK signaling contributes to the PACAP-induced increase in Guinea pig cardiac neuron excitability

Pituitary adenylate cyclase (PAC)-activating polypeptide (PACAP) peptides (Adcyap1) signaling at the selective PAC1 receptor (Adcyap1r1) participate in multiple homeostatic and stress-related responses, yet the cellular mechanisms underlying PACAP actions remain to be completely elucidated. PACAP/PAC receptor signaling increases excitability of neurons within the guinea pig cardiac ganglia, and as these neurons are readily accessible, this neuronal system is particularly amenable to study of PACAP modulation of ionic conductances. The present study investigated how PACAP activation of MEK/ERK signaling contributed to the peptide-induced increase in cardiac neuron excitability. Treatment with the MEK inhibitor PD 98059 blocked PACAP-stimulated phosphorylated ERK and, in parallel, suppressed the increase in cardiac neuron excitability. However, PD 98059 did not blunt the ability of PACAP to enhance two inward ionic currents, one flowing through hyperpolarization-activated nonselective cationic channels (I ) and another flowing through low-voltage-activated calcium channels (I ), which support the peptide-induced increase in excitability. Thus a PACAP-and MEK/ERK-sensitive, voltage-dependent conductance(s), in addition to I and I , modulates neuronal excitability. Despite prior work implicating PACAP downregulation of the K 4.2 potassium channel in modulation of excitability in other cells, treatment with the K 4.2 current blocker 4-aminopyridine did not replicate the PACAP-induced increase in excitability in cardiac neurons. However, cardiac neurons express the ERK target, the Na 1.7 sodium channel, and treatment with the selective Na 1.7 channel inhibitor PF-04856264 decreased the PACAP modulation of excitability. From these results, PACAP/PAC1 activation of MEK/ ERK signaling may phosphorylate the Na 1.7 channel, enhancing sodium currents near the threshold, an action contributing to repetitive firing of the cardiac neurons exposed to PACAP. 1 h T h T V V V V