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Objective: To characterize the clinical presentation and outcomes of Kawasaki disease (KD) in infants <6 months of age as compared to those ≥6 months in Latin America. Methods: We evaluated 36 infants <6 months old and 940 infants ≥6 months old diagnosed with KD in Latin America. We compared differences in laboratory data, clinical presentation, treatment response, and coronary artery outcomes between the two cohorts. Results: The majority (78.1%) of infants and children ≥6 months of age were initially diagnosed with KD, as compared to only 38.2% of infants <6 months. Clinical features of KD were more commonly observed in the older cohort: oral changes (92 vs. 75%, P = 0.0023), extremity changes (74.6 vs. 57.1%, P = 0.029), and cervical lymphadenopathy (67.6 vs. 37.1%, P = 0.0004). Whether treated in the first 10 days of illness or after the 10th day, infants <6 months were at greater risk of developing a coronary artery aneurysm compared to KD patients ≥6 months treated at the same point in the course of illness [ ≤ 10 days (53.8 vs. 9.4%, P = 0.00012); >10 days (50 vs. 7.4%, P = 0.043)]. Conclusion: Our data show that despite treatment in the first 10 days of illness, infants <6 months of age in Latin America have a higher risk of developing a coronary artery aneurysm. Delay in the diagnosis leads to larger coronary artery aneurysms disproportionately in these infants. Thus, suspicion for KD should be high in this vulnerable population., (Copyright © 2020 Moreno, Garcia, Bainto, Salgado, Parish, Rosellini, Ulloa-Gutierrez, Garrido-Garcia, Dueñas, Estripeaut, Luciani, Rodríguez-Quiroz, del Aguila, Camacho-Moreno, Gómez, Viviani, Alvarez-Olmos, de Souza Marques, Faugier-Fuentes, Saltigeral-Simental, López-Medina, Miño-León, Beltrán, Martínez-Medina, Pirez, Cofré, Tremoulet and the REKAMLATINA-2 Study Group Investigators.)

Inadequate solid waste management leads to contamination of the soil and surface and underground water; the emergence of antibiotic-resistant superbacteria due to the inadequate disposal of medicines in toilets or in household rubbish; and the emission of persistent organic pollutants, such as flame retardants, present in some electrical/electronic equipment. In Brazil, the principles that underpin the National Solid Waste Policy (PNRS) are consistent with those used by developed countries, namely, the polluter-payer and protector-receiver; cooperation among the different spheres of government, the business sector, and other societal segments; and the shared product life-cycle responsibility (Brasil, 2010a; Novi et al., 2013; Santos et al., 2019). In the latter, selective collection and reverse logistics systems are the primary instruments (Zhang et al., 2011). Thus, the general objective of this work is to compare the technical and economic feasibility of four different sectorial agreements for reverse logistics implemented in Brazil. The specific objective is to describe the possible conflicts of interest of the multistakeholders. The sources of evidence used in this multi-case study were interviews, observations, and documentary research in the period from 2016 to 2018. The first result demonstrated that the economic viability of reverse logistics systems are obtained when the wastes have a commercial value after consumption (packaging and consumer electronics) or when industries organize to charge a fee that covers the costs of recycling and transport (lamps and medicines). The second result shows that there are many stakeholders involved in this process: manufacturers and importers, consumers, private waste and recycling companies, and government represented by municipalities, the Ministry of the Environment (MMA), and state environmental agencies (OEMAs). Each one has different interests and responsibilities: government has to preserve the environment and comply with international agreements on climate change, thus creating laws that ultimately burden companies and cities; profit-maximizing companies evaluate these rules as additional costs in their operations, whereas cities, in which operations are conducted, have low financial and managerial capacity. The stakeholder map reveals that there are overlapping roles among agents, with some being the same for all chains, and the constructed power and level of interest matrix indicates the importance of the process to be conducted by the state to align economic and social-environmental interests., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objectives: To characterize the clinical presentation and outcome in infants <6 months of age with Kawasaki disease (KD) and to describe the use of newer anti-inflammatory therapies in this young population., Study Design: We evaluated 88 infants?<6 months old and 632??6 months old treated for KD. We compared differences in laboratory data, response to treatment, and coronary artery outcomes between the 2 cohorts. Fisher exact test was used to analyze categorical variables, whereas the Wilcoxon rank sum test was used for continuous variables., Results: The majority of children in both cohorts were diagnosed and treated within the first 10 days of illness (median illness day 6 in both cohorts). For patients treated within the first 10 days after fever onset, a larger proportion of infants <6 months old had a dilated or aneurysmal coronary artery on the initial echocardiogram compared with those ?6 months old (43.4% vs 19.5%). Furthermore, 18.6% of infants?<6 months old who had a normal echocardiogram at diagnosis, developed a dilated or aneurysmal coronary artery on a subsequent echocardiogram within 8 weeks of diagnosis. Twenty-eight infants?<6 months old received a single dose of infliximab without any untoward effects., Conclusions: Despite treatment in the first 10 days, infants?<6 months old with acute KD are more likely to develop coronary artery abnormalities. Thus, the development of adjunctive therapies to reduce coronary artery damage should target this population., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Leprosy is a chronic infectious disease that remains a major challenge to public health in endemic countries. Increasing evidence has highlighted the importance of microbiota for human general health and, as such, the study of skin microbiota is of interest. But while studies are continuously revealing the complexity of human skin microbiota, the microbiota of leprous cutaneous lesions has not yet been characterized. Here we used Sanger and massively parallel small sub-unit rRNA (SSU) rRNA gene sequencing to characterize the microbiota of leprous lesions, and studied how it differs from the bacterial skin composition of healthy individuals previously described in the literature. Taxonomic analysis of leprous lesions revealed main four phyla: Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, with Proteobacteria presenting the highest diversity. There were considerable differences in the distribution of Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria, with the first two phyla enriched and the other markedly diminished in the leprous lesions, when compared with healthy skin. Propionibacterium, Corynebacterium and Staphylococcus, resident and abundant in healthy skin, were underrepresented in skin from leprous lesions. Most of the taxa found in skin from leprous lesions are not typical in human skin and potentially pathogenic, with the Burkholderia, Pseudomonas and Bacillus genera being overrepresented. Our data suggest significant shifts of the microbiota with emergence and competitive advantage of potentially pathogenic bacteria over skin resident taxa.

Kawasaki disease (KD) is the leading cause of acquired cardiac disease in children in developed countries and Asia. However, there is a paucity of data available from Latin America. In response to the gap in knowledge about KD in Latin America, a group of pediatric infectious disease researchers from the Kawasaki Disease Research Center at the University of California San Diego and the Sociedad Latinoamericana de Infectología Pediátrica joined efforts during the last decade to address this problem. The Red de Enfermedad de Kawasaki en América Latina (Latin American Kawasaki Disease Network) was launched in 2013 to study the epidemiology of KD among children from the major pediatric tertiary referral hospitals in Latin America. This multinational multicenter network is primarily composed of pediatric infectious diseases, cardiology, rheumatology, and immunology subspecialists and pediatricians from 20 countries, and it is one of the world's largest networks to study the general epidemiology of KD. The first 2 prospective and retrospective multinational multicenter studies looking at the epidemiology of KD in the region were initiated in 2014. Future plans for the network include establishing collaborative research alliances and projects with other centers around the world. To date [ 1], there have been no published studies describing the overall incidence and prevalence of KD in Latin American children. The most important and recent epidemiological study addressing this issue, related to Chile, was published in 2012 [ 2]. Of these, the most recent relevant study addressed the seasonality of KD in different parts of the globe, including some Latin American and Caribbean countries [ 4]. In this document, we briefly summarize relevant available information from Latin America. Although there have been other publications from individual countries that are outside the scope of this communication, the majority of these reports are single case reports, or case series that have been published predominantly in local journals that are not indexed in PubMed and instead are in regional Spanish, Portuguese, and English databases., (© The Author 2014. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The Neutron Low Scattering Laboratory in Brazil has been completely rebuilt. Evaluation of air attenuation parameters and neutron component scattering in the room was done using Monte Carlo simulation code. Neutron fields produced by referenced neutron source were used to calculate neutron scattering and air attenuation., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The Brazilian Metrology Laboratory of Ionizing Radiations (LNMRI) standard thermal neutron flux facility was designed to provide uniform neutron fluence for calibration of small neutron detectors and individual dosemeters. This fluence is obtained by neutron moderation from four (241)Am-Be sources, each with 596 GBq, in a facility built with blocks of graphite/paraffin compound and high-purity carbon graphite. This study was carried out in two steps. In the first step, simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The quality of the resulting neutron fluence in terms of spectrum, cadmium ratio and gamma-neutron ratio was evaluated. In the second step, the system was assembled based on the results obtained on the simulations, and new measurements are being made. These measurements will validate the system, and other intercomparisons will ensure traceability to the International System of Units., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Recombinant influenza viruses are promising viral platforms to be used as antigen delivery vectors. To this aim, one of the most promising approaches consists of generating recombinant viruses harboring partially truncated neuraminidase (NA) segments. To date, all studies have pointed to safety and usefulness of this viral platform. However, some aspects of the inflammatory and immune responses triggered by those recombinant viruses and their safety to immunocompromised hosts remained to be elucidated. In the present study, we generated a recombinant influenza virus harboring a truncated NA segment (vNA-Δ) and evaluated the innate and inflammatory responses and the safety of this recombinant virus in wild type or knock-out (KO) mice with impaired innate (Myd88 -/-) or acquired (RAG -/-) immune responses. Infection using truncated neuraminidase influenza virus was harmless regarding lung and systemic inflammatory response in wild type mice and was highly attenuated in KO mice. We also demonstrated that vNA-Δ infection does not induce unbalanced cytokine production that strongly contributes to lung damage in infected mice. In addition, the recombinant influenza virus was able to trigger both local and systemic virus-specific humoral and CD8+ T cellular immune responses which protected immunized mice against the challenge with a lethal dose of homologous A/PR8/34 influenza virus. Taken together, our findings suggest and reinforce the safety of using NA deleted influenza viruses as antigen delivery vectors against human or veterinary pathogens.

Interfering with cellular signal transduction pathways is a common strategy used by many viruses to create a propitious intracellular environment for an efficient replication. Our group has been studying cellular signalling pathways activated by the orthopoxviruses Vaccinia (VACV) and Cowpox (CPXV) and their significance to viral replication. In the present study our aim was to investigate whether the GTPase Rac1 was an upstream signal that led to the activation of MEK/ERK1/2, JNK1/2 or Akt pathways upon VACV or CPXV' infections. Therefore, we generated stable murine fibroblasts exhibiting negative dominance to Rac1-N17 to evaluate viral growth and the phosphorylation status of ERK1/2, JNK1/2 and Akt. Our results demonstrated that VACV replication, but not CPXV, was affected in dominant-negative (DN) Rac1-N17 cell lines in which viral yield was reduced in about 10-fold. Viral late gene expression, but not early, was also reduced. Furthermore, our data showed that Akt phosphorylation was diminished upon VACV infection in DN Rac1-N17 cells, suggesting that Rac1 participates in the phosphoinositide-3 kinase pathway leading to the activation of Akt. In conclusion, our results indicate that while Rac1 indeed plays a role in VACV biology, perhaps another GTPase may be involved in CPXV replication.

Immunological adjuvants that induce T cell-mediate immunity (TCMI) with the least side effects are needed for the development of human vaccines. Glycoinositolphospholipids (GIPL) and CpGs oligodeoxynucleotides (CpG ODNs) derived from the protozoa parasite Trypanosoma cruzi induce potent pro-inflammatory reaction through activation of Toll-Like Receptor (TLR)4 and TLR9, respectively. Here, using mouse models, we tested the T. cruzi derived TLR agonists as immunological adjuvants in an antitumor vaccine. For comparison, we used well-established TLR agonists, such as the bacterial derived monophosphoryl lipid A (MPL), lipopeptide (Pam3Cys), and CpG ODN. All tested TLR agonists were comparable to induce antibody responses, whereas significant differences were noticed in their ability to elicit CD4(+) T and CD8(+) T cell responses. In particular, both GIPLs (GTH, and GY) and CpG ODNs (B344, B297 and B128) derived from T. cruzi elicited interferon-gamma (IFN-γ) production by CD4(+) T cells. On the other hand, the parasite derived CpG ODNs, but not GIPLs, elicited a potent IFN-γ response by CD8(+) T lymphocytes. The side effects were also evaluated by local pain (hypernociception). The intensity of hypernociception induced by vaccination was alleviated by administration of an analgesic drug without affecting protective immunity. Finally, the level of protective immunity against the NY-ESO-1 expressing melanoma was associated with the magnitude of both CD4(+) T and CD8(+) T cell responses elicited by a specific immunological adjuvant.

Influenza A virus causes annual epidemics which affect millions of people worldwide. A recent Influenza pandemic brought new awareness over the health impact of the disease. It is thought that a severe inflammatory response against the virus contributes to disease severity and death. Therefore, modulating the effects of inflammatory mediators may represent a new therapy against Influenza infection. Platelet activating factor (PAF) receptor (PAFR) deficient mice were used to evaluate the role of the gene in a model of experimental infection with Influenza A/WSN/33 H1N1 or a reassortant Influenza A H3N1 subtype. The following parameters were evaluated: lethality, cell recruitment to the airways, lung pathology, viral titers and cytokine levels in lungs. The PAFR antagonist PCA4248 was also used after the onset of flu symptoms. Absence or antagonism of PAFR caused significant protection against flu-associated lethality and lung injury. Protection was correlated with decreased neutrophil recruitment, lung edema, vascular permeability and injury. There was no increase of viral load and greater recruitment of NK1.1(+) cells. Antibody responses were similar in WT and PAFR-deficient mice and animals were protected from re-infection. Influenza infection induces the enzyme that synthesizes PAF, lyso-PAF acetyltransferase, an effect linked to activation of TLR7/8. Therefore, it is suggested that PAFR is a disease-associated gene and plays an important role in driving neutrophil influx and lung damage after infection of mice with two subtypes of Influenza A. Further studies should investigate whether targeting PAFR may be useful to reduce lung pathology associated with Influenza A virus infection in humans.

Guanine-nucleotide exchange factors (GEFs) stimulate the intrinsic GDP/GTP exchange activity of Ras and promote the formation of active Ras-GTP, which in turn controls diverse signalling networks important for the regulation of cell proliferation, survival, differentiation, vesicular trafficking, and gene expression. RasGEF1b is a GEF, whose expression is induced in macrophages on stimulation with toll-like receptor (TLR) agonists. Here, we showed that in vitro RasGEF1b expression by macrophages is mostly induced by TLR3 (poly I:C) and TLR4 (lipopolysaccharyde) through the MyD88-independent pathway. In vivo infection with the protozoan parasites Trypanosoma cruzi and Plasmodium chabaudi induced RasGEF1b in an MyD88-, TRIF-, and IFN-gamma-dependent manner. Ectopically expressed RasGEF1b was found, mostly, in the heavy membrane fraction of HEK 293T, and by confocal microscopy, it was found to be located at early endosomes. Computational modelling of the RasGEF1b-Ras interaction revealed that RasGEF1b interacts with the binding domain site of Ras, a critical region for interacting with GEFs involved in the activation of Ras-Raf-MEK-ERK pathway. More important, RasGEF1b was found to be closely associated with Ras in live cells and to trigger Ras activity. Altogether, these results indicate that on TLR activation, RasGEF1b may trigger Ras-like proteins and regulate specific biological activities described for this subtype of GTPases.

In this work, we explored an original vaccination protocol using recombinant influenza and adenovirus. We constructed recombinant influenza viruses harboring dicistronic NA segments containing the surface antigen 2 (SAG2) from Toxoplasma gondii under control of the duplicated 3' promoter. Recombinant influenza viruses were able to drive the expression of the foreign SAG2 sequence in cell culture and to replicate efficiently both in cell culture and in lungs of infected mice. In addition, mice primed with recombinant influenza virus and boosted with a recombinant adenovirus encoding SAG2 elicited both humoral and cellular immune responses specific for SAG2. Moreover, when immunized animals were challenged with the cystogenic P-Br strain of T. gondii, they displayed up to 85% of reduction in parasite burden. These results demonstrate the potential use of recombinant influenza vectors harboring the dicistronic segments in the development of vaccines against infectious diseases., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Objective: The purpose of the study is to compare the personality traits assessed with the Temperament and Character Inventory (TCI) between patients with panic disorder (PD) and a control group in a Brazilian sample., Methods: One hundred thirty-five patients with PD paired according to sex and age with 135 controls without any psychiatric disorders were assessed with the Mini International Neuropsychiatric Interview (MINI), a structured interview. Temperament and character were assessed with the TCI., Results: Consistently, patients with PD presented higher scores on the harm avoidance (HA) temperament scale (23.20 +/- 5.41 vs 15.21 +/- 4.92; P < .001) and lower scores on the self-directedness (SD) (27.81 +/- 7.25 vs 35.16 +/- 5.47; P < .001) if compared to the control group and has been associated independently from other TCI scales and confounders with PD. The multivariate logistic model containing HA and SD explains 38.6% to 51.4% of the differences between PD and controls., Conclusions: Harm avoidance could be a good candidate to be heritable because it appears to be a consistent finding across current literature in anxious and depressed patients independent of their cultural context. Also, SD seems to be a key character characteristic of PD patients. The dimensional assessment is an interesting alternative for understanding the relationship between the psychobiologic bases of temperament and character and is highly related to the development of psychiatric syndromes.

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)(50) was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC(50)/24 h = 175 microg/ml) and also induced trypomastigote lysis (IC(50)/24 h = 115 microg/ml). Thyme essential oil presented IC(50)/24 h values of 77 microg/ml for epimastigotes and 38 mug/ml for trypomastigotes, while treatment with thymol resulted in an IC(50)/24 h of 62 microg/ml for epimastigotes and 53 microg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.

The PKC1 gene in the yeast Saccharomyces cerevisiae encodes for protein kinase C which is known to control a MAP kinase cascade consisting of different kinases: Bck1, Mkk1 and Mkk2, and Mpk1. This cascade affects the cell wall integrity but the phenotype of pkc1Delta mutants suggests additional targets that have not yet been identified [Heinisch et al., Mol. Microbiol. 32 (1999) 671-680]. The pkc1Delta mutant, as opposed to other mutants in the MAP kinase cascade, displays defects in the control of carbon metabolism. One of them occurs in the derepression of SUC2 gene after exhaustion of glucose from the medium, suggesting an involvement of Pkc1p in the derepression process that is not shared by the downstream MAP kinase cascade. In this work, we demonstrate that Pkc1p is required for the increase of the activity of enzymatic systems during the derepression process. We observed that Pkc1p is involved in the derepression of invertase and alcohol dehydrogenase activities. On the other hand, it seems not to be necessary for the derepression of the enzymes of the GAL system. Our results suggest that Pkc1p is acting through the main glucose repression pathway, since introduction of an additional mutation in the PKC1 gene in yeast strains already presenting mutations in the HXKII or MIG1 genes does not interfere with the typical derepressed phenotype observed in these single mutants. Moreover, our data indicate that Pkc1p participates in this process through the control of the cellular localization of the Mig1 transcriptional factor.

Although isolated rat islets are widely used to study in vitro insulin secretion and the underlying metabolic and ionic processes, knowledge on the properties of glucose-induced electrical activity (GIEA), a key step in glucose-response coupling, has been gathered almost exclusively from microdissected mouse islets. Using a modified intracellular recording technique, we have now compared the patterns of GIEA in collagenase-isolated rat and mouse islets. Resting membrane potentials of rat and mouse beta-cells were approximately -50 and -60 mV, respectively. Both rat and mouse beta-cells displayed prompt membrane depolarizations in response to glucose. However, whereas the latter exhibited a bursting pattern consisting of alternating hyperpolarized and depolarized active phases, rat beta-cells fired action potentials from a nonoscillating membrane potential at all glucose concentrations (8.4-22.0 mmol/l). This was mirrored by changes in the intracellular Ca2+ concentration ([Ca2+]i), which was oscillatory in mouse and nonoscillatory in rat islets. Stimulated rat beta-cells were strongly hyperpolarized by diazoxide, an activator of ATP-dependent K+ channels. Glucose evoked dose-dependent depolarizations and [Ca2+]i increases in both rat (EC50 5.9-6.9 mmol/l) and mouse islets (EC50 8.3-9.5 mmol/l), although it did not affect the burst plateau potential in the latter case. We conclude that there are important differences between beta-cells from both species with respect to early steps in the stimulus-secretion coupling cascade based on the following findings: 1) mouse beta-cells have a larger resting K+ conductance in 2 mmol/l glucose, 2) rat beta-cells lack the compensatory mechanism responsible for generating membrane potential oscillations and holding the depolarized plateau potential in mouse beta-cells, and 3) the electrical and [Ca2+]i dose-response curves in rat beta-cells are shifted toward lower glucose concentrations. Exploring the molecular basis of these differences may clarify several a priori assumptions on the electrophysiological properties of rat beta-cells, which could foster the development of new working models of pancreatic beta-cell function.

Using clonal insulin-secreting BRIN-BD11 cells, we have assessed whether the graded response of the whole cell population to glucose can be accounted for by a dose-dependent recruitment of individual cells, an amplification of the response of the recruited cells or both. Cytosolic free Ca(2+) concentration ([Ca(2+)](i)) is an established index of beta-cell function. We used fura-2 microfluorescence techniques to assess the [Ca(2+)](i) responsiveness of single BRIN-BD11 cells to glucose and other secretagogues. Glucose (1-16.7 mM) evoked oscillatory [Ca(2+)](i) rises in these cells resembling those found in parental rat pancreatic beta-cells. The percentage of glucose-responsive cells was 11% at 1 mM and increased to 40-70% at 3-16.7 mM glucose, as assessed by a single-stimulation protocol. This profile was unrelated to possible differences in the cell cycle, as inferred from experiments where the cultured cells were synchronized by a double thymidine block protocol. Individual cells exhibited variable sensitivities to glucose (threshold range: 1-5 mM) and a variable dose-dependent amplification of the [Ca(2+)](i) responses (EC(50) range: 2-10 mM), as assessed by a multiple-stimulation protocol. Glyceraldehyde and alpha-ketoisocaproic acid had glucose-like effects on [Ca(2+)](i). The data support a mixed model for the activation of insulin-secreting cells. Specifically, the graded secretory response of the whole cell population is likely to reflect both a recruitment of individual cells with different sensitivities to glucose and a dose-dependent amplification of the response of the recruited cells.

Nutrient stimulation of pancreatic beta-cells increases the cellular reduced pyridine nucleotide content, but the specific role of cytosolic redox state in glucose-induced insulin release (GIIR) remains undetermined. The role of cytosolic redox state has been assessed (as reflected by the lactate/pyruvate ratio) in nutrient- and non-nutrient-induced insulin release using a recently established glucose-sensitive clonal beta-cell line (BRIN-BD11). Long-term exposure to the NAD+ precursor vitamin nicotinic acid (NA, 100 microM) was used to promote a more oxidized state in the cytosol. Glucose (2-16 mM) evoked a dose-dependent rise in the cytosolic NADH/NAD+ ratio which was linearly related to the extent of GIIR. NA suppressed the glucose-induced rise in the NADH/NAD+ ratio and concomitantly reduced GIIR by 44%. It also inhibited, by 47%, the average glucose-induced rise in cytosolic free Ca2+ concentration ([Ca2+]i, assessed by fura-2 microfluorometry from single cells). The latter effect was not accounted for by a reduction in the activity of voltage-sensitive Ca2+ channels, inasmuch as both high K+- and tolbutamide-induced [Ca2+]i rises remained insensitive to NA exposure. NA did not affect insulin release evoked by any of the depolarizing agents, indicating that steps in the stimulus-secretion coupling cascade distal to Ca2+ influx are insensitive to changes in the cytosolic redox state. It is concluded that GIIR is partially controlled by the cytosolic redox state. Moreover, the impairment in GIIR, caused by a shift toward a more oxidized state in the cytosol, originates from an attenuated [Ca2+]i response. The latter is likely mediated by the influence of cytosolic redox state on specific metabolic pathways (NADH shuttle systems and/or the malonyl-CoA pathway), leading ultimately to enhancement of the activity of ATP-sensitive K+ channels.

The study of the influence of intracellular pH (pHi) changes on the mechanism underlying pancreatic beta-cell bursting has been hampered by concomitant effects on the activity of background ATP-dependent K+ (K-ATP) channels. beta-cells were made to burst in the absence of active K-ATP channels by raising external Ca2+ in the presence of 11 mM glucose and tolbutamide. An alkalinizing pHi shift (exposure to 20 mM NH4Cl) increased the burst active phase duration. Conversely, an acidifying shift (NH4Cl withdrawal) suppressed the electrical activity. This is the mirror image of the effects recorded in the absence of tolbutamide. Glibenclamide and quinine suppressed the alkalinization-evoked hyperpolarization. This study emphasizes the differential sensitivity of different beta-cell ion channels to pHi and the prevalent role of K-ATP channels as electrical transducers of cytoplasmic pH changes under regular physiological conditions.