One Health and antimicrobial resistance, a United States perspective.

Antimicrobial drugs are a precious resource, responsible for saving millions of lives since their discovery. Unfortunately, some antimicrobials are rapidly losing their effectiveness due to the development and spread of antimicrobial resistance (AMR), a multi-faceted and complex problem affecting humans, animals, plants and the environment. While AMR is a global problem, in this paper, the authors briefly highlight some ongoing efforts in the United States of America aimed at integrating a One Health approach into policies and programmes that address this important health threat.

Les antibiotiques sont des ressources de grande valeur qui ont sauvé des millions de vies depuis leur découverte. Malheureusement, certains agents antimicrobiens perdent rapidement leur efficacité en raison de l'apparition et propagation des résistances à ces agents, phénomène complexe et multidimensionnel qui affecte l'homme, les animaux, les plantes et l'environnement. La résistance aux agents antimicrobiens est un problème mondial ; dans cet article, les auteurs décrivent certaines initiatives actuellement mises en oeuvre aux États-Unis d'Amérique pour intégrer l'approche Une seule santé dans les politiques et les programmes conçus pour lutter contre cette menace sanitaire majeure.

Los fármacos antimicrobianos son un recurso valiosísimo, cuyo uso ha salvado millones de vidas desde que fueron descubiertos. Lamentablemente, algunos de ellos están perdiendo rápidamente eficacia debido a la aparición y propagación de resistencias, lo que plantea un problema tan complejo como poliédrico, que afecta a personas, animales, plantas y ecosistemas. Aunque la dimensión del problema es planetaria, los autores destacan aquí brevemente algunas de las iniciativas en curso en los Estados Unidos de América que tienen por objetivo integrar los planteamientos de Una sola salud en el conjunto de políticas y programas desde los cuales se aborda esta importante amenaza sanitaria.

Intermittent plasticity in individual grains: A study using high energy x-ray diffraction.

Long-standing evidence suggests that plasticity in metals may proceed in an intermittent fashion. While the documentation of intermittency in plastically deforming materials has been achieved in several experimental settings, efforts to draw connections from dislocation motion and structure development to stress relaxation have been limited, especially in the bulk of deforming polycrystals. This work uses high energy x-ray diffraction measurements to build these links by characterizing plastic deformation events inside individual deforming grains in both the titanium alloy, Ti-7Al, and the magnesium alloy, AZ31. This analysis is performed by combining macroscopic stress relaxation data, complete grain stress states found using far-field high energy diffraction microscopy, and rapid x-ray diffraction spot measurements made using a Mixed-Mode Pixel Array Detector. Changes in the dislocation content within the deforming grains are monitored using the evolution of the full 3-D shapes of the diffraction spot intensity distributions in reciprocal space. The results for the Ti-7Al alloy show the presence of large stress fluctuations in contrast to AZ31, which shows a lesser degree of intermittent plastic flow.

Forensic analysis of latent fingermarks by silver-assisted LDI imaging MS on nonconductive surfaces.

Silver-assisted laser desorption ionization (AgLDI) imaging mass spectrometry (IMS) has been demonstrated to be a useful technology for fingermark analysis allowing for the detection of several classes of endogenous as well as exogenous compounds. Ideally, in IMS analyses, the fingermarks are deposited under controlled conditions on metallized conductive target slides. However, in forensic investigations, fingermarks are often found on a variety of nonconductive surfaces. A sputtered silver layer renders the target surface conductive, which allows the analyses of insulating surfaces by time-of-flight IMS. Ultimately, the major consideration when developing analytical methods for the analysis of latent fingermarks is their capability to be incorporated within forensic standard operational procedures. To demonstrate the potential of AgLDI IMS for forensic applications, fingermarks deposited on nonconductive surfaces commonly found during an investigation, including paper, cardboard, plastic bags and lifting tape, were first revealed by the Sûreté du Québec by using forensic enhancement techniques prior to the IMS analyses. Numerous endogenous compounds including fatty acids, cholesterol, squalene, wax esters, triglycerides and several exogenous substances were detected and imaged. Here, we show that silver sputtering can provide visual enhancements of fingerprint patterns after FET procedures through different scenarios in which AgLDI IMS can contribute to forensic investigations. Copyright © 2017 John Wiley & Sons, Ltd.

Impact of oxaliplatin-induced neuropathy in patients with colorectal cancer: a prospective evaluation at a single institution.

Oxaliplatin plays a major role in the treatment of colorectal cancer (crc), but is associated with the development of neuropathies. The main objective of the present prospective study was to estimate the proportion of participants with grade 1, 2, 3, or 4 peripheral sensory neuropathies according to the U.S. National Cancer Institute's Common Terminology Criteria for Adverse Events (version 4) among crc patients treated with oxaliplatin (adjuvant or metastatic, folfox or xelox regimens) at the Centre hospitalier universitaire de Sherbrooke. Among the 57 patients so treated between May 2012 and April 2013, about 60% reported grade 2 neuropathy, at maximum, during treatment. About 25% of patients had to stop treatment because of neuropathies. In a subset of patients contacted approximately 22 months after treatment cessation, neuropathies persisted in 70%. Oxaliplatin-induced neuropathy affects a significant number of crc patients and can influence the course of treatment and outcomes.

Palliative chemotherapy for patients 70 years of age and older with metastatic colorectal cancer: a single-centre experience.

BACKGROUND: Metastatic colorectal cancer (mcrc) commonly affects elderly people, an understudied subset of patients. We analyzed the survival impact of the first and subsequent lines of chemotherapy in eligible non-trial patients 70 years of age and older with mcrc treated between 2004 and 2012. METHODS: This single-centre retrospective analysis estimated overall survival (os) and progression-free survival (pfs) using the Kaplan-Meier method. Multivariate analysis was used to adjust for age, sex, Eastern Cooperative Oncology Group performance status, score on the Charlson comorbidity index, dependency in activities of daily living, and exposure to 1 or more chemotherapy doublets, capecitabine alone, or best supportive care (bsc). RESULTS: Of 109 patients identified, 29 elected bsc, and 80 received chemotherapy. In multivariate analysis, age was not associated with os [hazard ratio (hr): 0.99; 95% confidence interval (ci): 0.92 to 1.05], but a performance status of 2 or higher was associated with a decreased likelihood of survival (hr: 3.12; 95% ci: 1.87 to 5.76), and exposure to 1 or more doublets was associated with improved survival (hr: 0.33; 95% ci: 0.17 to 0.66). In univariate analysis, a trend toward improved os was observed for first-line doublet chemotherapy compared with capecitabine (hr: 0.66; 95% ci: 0.41 to 1.07), and pfs was superior (hr: 0.46; 95% ci: 0.26 to 0.84). Compared with exposure to 1 doublet, exposure to the 3 potential cytotoxic chemotherapies was not associated with improved os (hr: 0.77; 95% ci: 0.41 to 1.43). The incidence of neutropenia with first-line folfiri was 40%; the incidences of bevacizumab-related arterial and venous thrombosis were both 8%. CONCLUSIONS: Exposure to 1 or more doublet chemotherapies for mcrc was associated with better outcomes in non-trial patients 70 years of age and older. Elderly patients treated with palliative chemotherapy and bevacizumab should be monitored carefully for arterial and venous thrombotic events.

COMT polymorphism modulates the resting-state EEG alpha oscillatory response to acute nicotine in male non-smokers.

Performance improvements in cognitive tasks requiring executive functions are evident with nicotinic acetylcholine receptor (nAChR) agonists, and activation of the underlying neural circuitry supporting these cognitive effects is thought to involve dopamine neurotransmission. As individual difference in response to nicotine may be related to a functional polymorphism in the gene encoding catechol-O-methyltransferase (COMT), an enzyme that strongly influences cortical dopamine metabolism, this study examined the modulatory effects of the COMT Val158Met polymorphism on the neural response to acute nicotine as measured with resting-state electroencephalographic (EEG) oscillations. In a sample of 62 healthy non-smoking adult males, a single dose (6 mg) of nicotine gum administered in a randomized, double-blind, placebo-controlled design was shown to affect α oscillatory activity, increasing power of upper α oscillations in frontocentral regions of Met/Met homozygotes and in parietal/occipital regions of Val/Met heterozygotes. Peak α frequency was also found to be faster with nicotine (vs. placebo) treatment in Val/Met heterozygotes, who exhibited a slower α frequency compared to Val/Val homozygotes. The data tentatively suggest that interindividual differences in brain α oscillations and their response to nicotinic agonist treatment are influenced by genetic mechanisms involving COMT.

Risk factors for exposure to influenza a viruses, including subtype H5 viruses, in Thai free-grazing ducks.

Free-grazing ducks (FGD) have been associated with highly pathogenic avian influenza (HPAI) H5N1 outbreaks and may be a viral reservoir. In July-August 2010, we assessed influenza exposure of Thai FGD and risk factors thereof. Serum from 6254 ducks was analysed with enzyme-linked immunosorbent assay (ELISA) to detect antibodies to influenza A nucleoprotein (NP), and haemagglutinin H5 protein. Eighty-five per cent (5305 ducks) were seropositive for influenza A. Of the NP-seropositive sera tested with H5 assays (n = 1423), 553 (39%) were H5 ELISA positive and 57 (4%) suspect. Twelve per cent (74 of 610) of H5 ELISA-positive/suspect ducks had H5 titres ≥ 1 : 20 by haemagglutination inhibition. Risk factors for influenza A seropositivity include older age, poultry contact, flock visitors and older purchase age. Study flocks had H5 virus exposure as recently as March 2010, but no HPAI H5N1 outbreaks have been identified in Thailand since 2008, highlighting a need for rigorous FGD surveillance.

Management of winter weeds affects Frankliniella fusca (Thysanoptera: Thripidae) dispersal.

Frankliniella fusca (Hinds) naturally disperses from winter weeds to crops in spring, causing direct and indirect damage. Field preparation before planting includes use of herbicides or cultivation to kill unwanted vegetation, which adversely affects F. fusca host plants and potentially influences F. fusca dispersal. Common chickweed, Stellaria media (L.), infested with F. fusca, was used as a model to study effects of timing and type of vegetation management on adult dispersal. Infested weeds were caged and F. fusca weekly dispersal was monitored using sticky traps. Weed management treatments performed at an early (14 April-11 May) or late (2 wk after early treatment) date consisted of glyphosate, paraquat, disking, hoeing, or untreated control. Late glyphosate and hoeing treatments resulted in cumulative dispersal statistically similar to or greater than from control plots. Compared with the control, significantly more F. fusca dispersed from the glyphosate and hoeing plots during the 3 wk after treatment. More thrips dispersed from the late paraquat treatment 1 wk post-application than from the control. Dispersal from the disked treatment and early paraquat treatment was similar to that of the control 1- to 3-wk post-treatment. Early treatments resulted in significantly smaller cumulative dispersal than the control in all but one instance. Late disking and paraquat treatments resulted in cumulative F. fusca captures that were statistically similar or less than that in the control. Winter weed management type and timing affect F. fusca dispersal magnitude and duration.

Use of personal protective measures by Thai households in areas with avian influenza outbreaks.

Thailand has had multiple poultry outbreaks of highly pathogenic avian influenza (HPAI) H5N1 since its first emergence in 2004. Twenty-five human cases of HPAI H5N1 avian influenza have been reported in the country, including 17 fatalities, and contact with infected dead or dying poultry has been identified as a risk factor for human infection. This study assessed the use of protective equipment and hand hygiene measures by Thai poultry-owning households during activities involving poultry contact. Surveys conducted in 2008 included questions regarding poultry-related activities and protective measures used during an HPAI outbreak (2005) and 3 years after the study location's last reported outbreak (2008). For both time periods, poultry owners reported limited use of personal protective equipment (PPE) during all activities and inconsistent hand washing practices after carrying poultry and gathering eggs. This is the first time that PPE use in Thailand has been quantified for a large study group. These data are important for ongoing characterization of HPAI risk and for the crafting of educational messages.

Characterization of influenza a outbreaks in Minnesota swine herds and measures taken to reduce the risk of zoonotic transmission.

Influenza A virus infections commonly cause respiratory disease in swine and can be transmitted between people and pigs, with potentially novel strains introduced into herds and spilling back into the human population. The goals of this study were to characterize influenza infections in Minnesota pigs and assess biosecurity measures used by swine workers. Veterinarians submitting influenza-positive swine samples to the University of Minnesota Veterinary Diagnostic Laboratory between October 2007 and April 2009 were surveyed regarding disease-related information and biosecurity procedures at each farm. Influenza-positive samples were submitted year-round, peaking in spring and fall. H1N1 was the most commonly detected subtype (56%), followed by H3N2 (14%) and H1N2 (12%). Most positive submissions were associated with illness in growing pigs (median age 8.8 weeks, IQR 5-15). Median morbidity and mortality were 25% (IQR 10-48) and 2% (IQR 0.5-3.5), respectively. Vaccination of sows and growing pigs was conducted at 71% and 7.9% of the swine farms, respectively. Specialized footwear was reported as the most common form of protective equipment used by workers. Employee vaccination for seasonal influenza was 19%. The sow vaccination rate in this study is consistent with national data, although growing pig vaccination is lower than the national average. Seasonal and age trends identified here may provide diagnostic guidance when growing pigs experience respiratory disease. Inconsistent use of protective equipment and employee vaccination at swine farms indicates the need for further discussion and research of approaches to minimize interspecies influenza transmission on swine farms.

The Impact of type 2 diabetes on mortality in end-stage renal disease patients differs between genders.

BACKGROUND/AIMS: In diabetics with end-stage renal disease (ESRD), risk of death has been reported to be non-constant after the first dialysis, and different outcomes have been observed between genders. We assessed the impact of type 2 diabetes (T2DM) on mortality in dialysis regarding its differential effect by gender using time-dependent analyses. METHODS: All T2DM and non-diabetic (no-DM) patients who started dialysis in two renal units in Lyon, France, between January 1, 1995, and December 31, 2007, were included. In multivariate analyses, the Cox model and Shoenfeld residual approach were used to assess the effect of T2DM on dialysis mortality by gender. RESULTS: We included 235 T2DM (males: 57.9%) and 480 no-DM (males: 65.6%) patients. In males, the adjusted hazard ratio (aHR) for death in T2DM versus no-DM was 0.83 (p = 0.20) and was constant over time after the first renal replacement therapy (RRT) (p = 0.88). In females, aHR for death in T2DM versus no-DM patients was not constant over time (p = 0.002). It was 0.64 (p = 0.13) within the first year after the first RRT and 2.10 (p = 0.002) after the first year. Evolutions with time of these aHR by gender were significantly different (p = 0.009). CONCLUSIONS: T2DM was associated with death only in females. This association was not constant over time after the first dialysis.

Bell and banana pepper exhibit mature-plant resistance to tomato spotted wilt Tospovirus transmitted by Frankliniella fusca (Thysanoptera: Thripidae).

Tomato spotted wilt virus (family Bunyaviridae, genus Tospovirus, TSWV) causes annual economic losses in pepper, Capsicum annuum L., across the southern United States and is transmitted by several species of thrips, including the tobacco thrips, Frankliniella fusca (Hinds). Reduced virus transmission and symptom severity as plant age increases is known as mature-plant resistance. TSWV transmission to pepper plants was examined in three and four age classes in field and greenhouse trials, respectively. In the field trial, 'Camelot' bell pepper plants were exposed to potentially viruliferous F. fusca 37, 51, or 65 d postsowing. Two greenhouse trials of Camelot bell and one trial each of 'Bounty' and 'Pageant' banana pepper plants were exposed to potentially viruliferous F. fusca, 43, 57, 71, or 85; 48, 62, 75, or 90; 42, 56, 70, or 84; and 43, 57, 71, or 85 d postsowing, respectively. Linear and hyperbolic regressions of percentage of infected plants per block on days postsowing indicated mature-plant resistance in all trials. All models were significant, but hyperbolic curves better fit the data than linear models. Hyperbolic models were used to calculate the number of days posttransplant at which a 50% decrease from the predicted percentage of infected plants at transplant age (42 d postsowing) was expected. This was referred to as days posttransplant-50 (DPT50). DPRT50 occurred within 9 days posttransplant age for all trials, indicating that early TSWV management in pepper is critical.

Effects of size on the dynamics of dislocations in ice single crystals.

Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the plastic strain rate increases with time. In a cylindrical sample, the size of the radius affects this response. The smaller the radius of the sample becomes while keeping constant the average shear stress across a section, the softer the response. The size-dependent behavior is interpreted by using a field dislocation theory, in terms of the coupled dynamics of excess screw dislocations gliding in basal planes and statistical dislocations developed through cross slip occurring in prismatic planes. The differences in the results caused by sample height effects and variations in the initial dislocation microstructure are discussed.

Characterization of the NTPDase activities in the mesentery pre- and post-capillary circuits of the guinea pig.

NTPDase is one of the principal enzymes involved in the sequential hydrolysis of ATP. In the present study, the presence and functionality of NTPDase in the mesenteric vein and artery were examined. Adenosine triphosphate (ATP) (0.01-1000 pmol) induces a dose-dependent vasodilation in the isolated arterial and venous mesenteric vasculatures of the guinea pig. Adenosine diphosphate (ADP) (0.01-1000 pmol) but not adenosine monophosphate (AMP) (0.01-1000 pmol) induces a similar response in the mesenteric vascular circuit. L-NAME, a nitric oxide synthase inhibitor (200 microM, 30 min), significantly reduces the arterial dilatory effect of ATP and abolishes the responses to ADP and AMP. Complete removal of the endothelium with 3-[(3-cholamidopropyl) dimethylammonio]-1-propansulfonate (CHAPS) (20 mM, 2 x 45 s) abolishes ATP-induced responses. Infusion of ATP in the vascular circuit generated detectable amounts of ADP and AMP, as measured by HPLC. CHAPS treatment significantly reduced the level of ATP and the production of AMP in the arterial mesenteric circuit. In contrast to the arterial mesenteric vasculature, endothelium removal in the venous circuit triggered a marked potentiation of ADP release and, interestingly, a marked reduction in the release of AMP. Moreover, a specific inhibitor of NTP diphosphohydrolase, 1-hydroxynaphthlene-3,6-disulfonic acid BGO 136 (10 mM for 20 min), significatively reduced AMP production in both vascular preparations. These results confirm that the endothelium contributes to the vasoactive properties of ATP, ADP, and AMP. Our data also demonstrated a significant role of endothelium in NTPDase activity on ADP and AMP production prior to exogenous administration of ATP. The activity of this particular enzyme appears to be different from the reaction products viewpoint (i.e., the production of ADP) in the pre- and post-mesenteric circuits, suggesting two different isoforms with different substrate specificities.

Purine signaling and potential new therapeutic approach: possible outcomes of NTPDase inhibition.

Interest for extracellular nucleotides has increased since the pioneer work of Burnstock in the early seventies. Research on cellular functions modulated by purines and pyrimidines has led to the identification and characterization of the different components of purine signaling, namely purinoceptors and ecto-nucleotidases. Receptors for tri- and diphosphonucleosides, known as P2 nucleotide receptors, are designated either P2Y receptors, for those coupled to G-proteins, or P2X for those which are ligand gated-ion channels. Ecto-nucleoside triphosphate diphosphohydrolase (NTPDase; EC 3.6.1.5), previously identified as ecto-ATPase, ecto-ATPDase or CD39, is now considered as the main ecto-nucleotidase responsible for the sequential hydrolysis of beta and gamma phosphates of tri- and diphosphonucleosides. More recently, research has been focused on the development of specific agonists and antagonists to P2 purinoceptors. The need to develop specific inhibitors for NTPDase to understand the role of this enzyme has clearly emerged. This paper covers the development of specific molecules targeting purinergic signaling, more specifically the inhibition of NTPDase and their impact on the different physiological systems.

Ca(2+)-channel blockers and nucleoside triphosphate diphosphohydrolase (NTPDase) influence of diltiazem, nifedipine, and verapamil.

The nucleoside triphosphate diphosphohydrolases (NTPDase; EC 3.6.1. 5) are a family of ectonucleotidases associated with vascular endothelial and smooth muscle cells. These ectonucleotidases are involved in the control of vascular tone by regulating the level of circulating ATP. Ca(2+)-channel blocking agents are currently used for the treatment of hypertension. Considering the external localization of the NTPDase catalytic site and its Ca(2+) requirement for enzyme activity, a possible interference of calcium antagonists (nifedipine, verapamil-HCl, and diltiazem-HCl and some of its metabolites) could be anticipated. To test that hypothesis, an NTPDase-enriched particulate fraction was used. Our results show that verapamil, diltiazem, and its metabolites all produced a concentration-dependent inhibition of NTPDase, at concentrations greater or equal to 0.1 mM with verapamil and to 0.5 mM with diltiazem and its metabolites, whereas no significant effect was observed with nifedipine. Kinetic studies, carried out to define the mode of action of these drugs, showed a mixed type of inhibition. Based on their respective K(i) values (in parentheses, in mM), inhibitory potencies of these molecules were in the following order: desacetyl-N-desmethyldiltiazem (M(2)-HCl; 0.6) > verapamil (0.76) > N-desmethyldiltiazem (M(A;) 0.9) > diltiazem (2.4) > desacetyl-O-desmethyldiltiazem (M(4)-HCl; 3.5) > desacetyl N, O-desmethyldiltiazem (M(6)-HCl; 3.9). Hence, these calcium antagonists can be considered as weak NTPDase inhibitors. Moreover, based on these K(i) values and the range of concentrations found in the blood, NTPDase would not be inhibited significantly in vivo.

Characterization and immunohistochemical localization of nucleoside triphosphate diphosphohydrolase (NTPDase) in pig adrenal glands (presence of a non-sedimentable isoform).

Considering that adrenal glands possess a variety of purinoceptors associated with various cell types and that some of these cells (chromaffin cells) secrete large amounts of adenine nucleotides, it was of interest to localize nucleoside triphosphate diphosphohydrolase (NTPDase) in these glands and to define the biochemical characteristics of this ectonucleotidase. Immunolocalization produced a moderate reaction in capsula and medulla, with no signal in zona glomerulosa and zona reticularis. In contrast, a very strong reaction was found in zona fasciculata. Biochemical analysis of particulate fractions isolated from whole glands revealed high levels of ATPase and ADPase activities. This appeared to be attributable to the NTPDase since the level of ADPase was as high as ATPase. Both ATPase and ADPase activities were similarly inhibited by sodium azide. Additionally electrophoretograms with these two substrates showed comparable patterns. Western blots with 'Ringo', an antibody that recognizes the different isoforms of mammalian NTPDases, showed the presence of isoforms of NTPDases at 54 and 78 kDa, respectively. Interestingly, the 54 kDa isoform remains in the supernatant of a chromaffin granule lysate after ultracentrifugation. Up until now little interest has been given to the relationship between adrenal medulla and cortex. Presence of purinoceptors and ectonucleotidases in both these regions together with the effects of ATP in vivo and in vitro in different species indicate that purines play a significant role in adrenal glands.

Synthesis, mechanism and fluorescence properties of 8-(aryl)-3-beta-D-ribofuranosylimidazo[2,1-i]purine 5'-phosphate derivatives.

The synthesis of new fluorescent nucleotides is described. This synthesis comprises two parallel reactions, the Kornblum oxidation and imidazole formation, which lead to 8-(aryl)-3-beta-D-ribofuranosylimidazo[2,1-i]purine 5'-phosphates 2 from AMP or ATP. A detailed mechanism is proposed based on monitoring the reaction by 1H- and 13C-NMR spectroscopy, MS, FAB, HPLC, and pH meter. The spectral and fluorescent properties of the new derivatives at various pH values are described. Excitation and emission maxima for 3 were observed at 290 and 420 nm, respectively, in both basic and neutral media. In acidic media, the emission maximum shifted to 410 nm, however, the fluorescence intensity increased 1.5-fold. ATP analogues 2b and 3b exhibited relative stability regarding hydrolysis by type II ATPDase. Compound 3b is relatively chemically stable at pH 10.4 and 7.4.

2-Thioether-5'-O-(1-thiotriphosphate)-adenosine derivatives: new insulin secretagogues acting through P2Y-receptors.

P2-receptors (P2-Rs) represent significant targets for novel drug development. P2-Rs were identified also on pancreatic B cells and are involved in insulin secretion. The aim of our study was to synthesize and evaluate pharmacologically the novel P2Y-R ligands, 2-thioether-5'-O-phosphorothioate adenosine derivatives, as potential insulin secretagogues. An efficient synthesis of these nucleosides and a facile method for separation of the chiral products is described. The enzymatic stability of the compounds towards pig-pancreas NTPDase was evaluated. The rate of hydrolysis of 2-hexylthio-5'-O-(1-thiotriphosphate)-adenosine (2-hexylthio-ATP-alpha-S) isomers by NTPDase was 28% that of ATP. The apparent affinity of the compounds to P2Y1-R was determined by measurement of P2Y-receptor-promoted phospholipase C activity in turkey erythrocyte membranes. 2-RS-ATP-alpha-S derivatives were agonists, stimulating the production of inositol phosphates with K0.5 values in the nM range. 2-RS-AMP-S derivatives were full agonists although 2 orders of magnitude less potent. All the compounds were more potent than ATP. The effect on insulin secretion and pancreatic flow rate was evaluated on isolated and perfused rat pancreas. A high increase, up to 500%, in glucose-induced insulin secretion was due to addition of 2-hexylthio-ATP-alpha-S in the nM concentration range, which represents 100-fold enhancement of activity relative to ATP. 2-Hexylthio-AMP-S was 2.5 orders of magnitude less effective. A high chemical hydrolytic stability was observed for 2-hexylthio-ATP-alpha-S. Hydrolysis of the phosphoester bond, which was the only detectable degrading reaction under the investigation conditions (pH 7.4, 37 degrees C), was slow, with a half-life of 264 hours. Moreover, even at gastric juice conditions (pH 1.4, 37 degrees C), hydrolysis of the terminal phosphate was the only detectable reaction, with a half-life of 17.5 hours. 2-Hexylthio-ATP-alpha-S isomers are enzymatically and chemically stable. These isomers are highly potent and effective insulin secretagogues, increasing, however, pancreatic vascular resistance.