RESUMEN

A3 adenosine receptor (A3AR) positive allosteric modulators (PAMs) (2,4-disubstituted-1H-imidazo[4,5-c]quinolin-4-amines) allosterically increase the Emax of A3AR agonists, but not potency, due to concurrent orthosteric antagonism. Following mutagenesis/homology modeling of the proposed lipid-exposed allosteric binding site on the cytosolic side, we functionalized the scaffold, including heteroatom substitutions and exocyclic phenylamine extensions, to increase allosteric binding. Strategically appended linear alkyl-alkynyl chains with terminal amino/guanidino groups improved allosteric effects at both human and mouse A3ARs. The chain length, functionality, and attachment position were varied to modulate A3AR PAM activity. For example, 26 (MRS8247, p-alkyne-linked 8 methylenes) and homologues increased agonist Cl-IB-MECA's Emax and potency ([35S]GTPγS binding). The putative mechanism involves a flexible, terminally cationic chain penetrating the lipid environment for stable electrostatic anchoring to cytosolic phospholipid head groups, suggesting "lipid trolling", supported by molecular dynamic simulation of the active-state model. Thus, we have improved A3AR PAM activity through rational design based on an extrahelical, lipidic binding site.

Asunto(s)

Agonistas del Receptor de Adenosina A3 , Receptor de Adenosina A3 , Humanos , Regulación Alostérica/efectos de los fármacos , Animales , Receptor de Adenosina A3/metabolismo , Receptor de Adenosina A3/química , Ratones , Agonistas del Receptor de Adenosina A3/farmacología , Agonistas del Receptor de Adenosina A3/química , Relación Estructura-Actividad , Lípidos/química , Cricetulus , Sitio Alostérico , Quinolinas/química , Quinolinas/farmacología , Quinolinas/síntesis química , Células CHO

RESUMEN

This article presents findings from a community-based cross-sectional study conducted in Attappadi, Kerala, India, aimed at assessing the prevalence of the triple burden of malnutrition among indigenous children aged 0-19 years. Historically, the indigenous population in Attappadi has faced significant developmental challenges, including high rates of malnutrition, infant mortality, and neonatal mortality. This study revealed alarming rates of undernutrition among children aged 0-59 months, with 40.9% experiencing stunting, 27.4% wasting, and 48.3% being underweight. Adolescent girls also suffered from undernutrition, with 21% classified as underweight and 43.3% experiencing stunting. Surprisingly, overweight or obesity was identified as a nutritional problem, affecting 1.4% of children aged 0-59 months, 4.2% of children aged 5-9 years, and 10.5% of adolescent girls. Additionally, a distressing proportion of young children aged 12-59 months (91.2%) were anaemic, with 50% diagnosed specifically with iron deficiency anaemia (IDA). Nearly all adolescent girls (96.6%) were reportedly suffering from anaemia. Deficiencies in vitamin B12, vitamin D, folate, and vitamin-A were prevalent among 35%, 20%, 16%, and 12% of children aged 12-59 months, respectively. The study underscores the urgent need for comprehensive interventions to address this triple burden of malnutrition. Recommendations include promoting culturally appropriate local food-based solutions, establishing participatory and community-led systems for health and nutrition information dissemination, and strengthening the nutrition surveillance system through village-level health and nutrition workers. By adopting a holistic approach, these interventions can help improve the nutritional status and well-being of the indigenous tribal children in Attappadi.

Asunto(s)

Anemia , Desnutrición , Lactante , Recién Nacido , Femenino , Adolescente , Humanos , Niño , Preescolar , Estado Nutricional , Desnutrición/epidemiología , Delgadez , Estudios Transversales , Anemia/epidemiología , Encuestas Nutricionales , Trastornos del Crecimiento/epidemiología , Vitaminas , India/epidemiología , Prevalencia

RESUMEN

Background: COVID-19 emerged as a global pandemic in 2020, spreading rapidly to most parts of the world. The proportion of infected individuals in a population can be reliably estimated via serosurveillance, making it a valuable tool for planning control measures. Our serosurvey study aimed to investigate SARS-CoV-2 seroprevalence in the urban population of Hyderabad at the end of the first wave of infections. Methods: This cross-sectional survey, conducted in January 2021 and including males and females aged 10 years and above, used multi-stage random sampling. 9363 samples were collected from 30 wards distributed over six zones of Hyderabad, and tested for antibodies against SARS-CoV-2 nucleocapsid antigen. Results: Overall seropositivity was 54.2%, ranging from 50% to 60% in most wards. Highest exposure appeared to be among those aged 30-39 and 50-59 years, with women showing greater seropositivity. Seropositivity increased with family size, with only marginal differences among people with varying levels of education. Seroprevalence was significantly lower among smokers. Only 11% of the survey subjects reported any COVID-19 symptoms, while 17% had appeared for COVID-19 testing. Conclusion: Over half the city's population was infected within a year of onset of the pandemic. However, ∼ 46% of people remained susceptible, contributing to subsequent waves of infection.

RESUMEN

Accumulating evidence supports a therapeutic role of purinergic signaling in cardiac diseases. Previously, efficacy of systemically infused MRS2339, a charged methanocarba derivative of 2-Cl-adenosine monophosphate, was demonstrated in animal models of heart failure. We now test the hypothesis that an uncharged adenine nucleoside phosphonate, suitable as an oral agent with a hydrolysis-resistant phospho moiety, can prevent the development of cardiac dysfunction in a post-infarction ischemic or pressure overload-induced heart failure model in mice. The diester-masked uncharged phosphonate MRS2978 was efficacious in preventing cardiac dysfunction with improved left ventricular (LV) fractional shortening when administered orally at the onset of ischemic or pressure overload-induced heart failure. MRS2925, the charged, unmasked MRS2978 analog, prevented heart dysfunction when infused subcutaneously but not by oral gavage. When administered orally or systemically, MRS2978 but not MRS2925 could also rescue established cardiac dysfunction in both ischemic and pressure overload heart failure models. The diester-masked phosphate MRS4074 was highly efficacious at preventing the development of dysfunction as well as in rescuing pressure overload-induced and ischemic heart failure. MRS2978 was orally bioavailable (57-75%) giving rise to MRS2925 as a minor metabolite in vivo, tested in rats. The data are consistent with a novel therapeutic role of adenine nucleoside phosphonates in systolic heart failure.

Asunto(s)

Adenosina Monofosfato/farmacología , Insuficiencia Cardíaca , Agonistas del Receptor Purinérgico P2X/farmacología , Adenosina Monofosfato/síntesis química , Adenosina Monofosfato/química , Animales , Ratones , Agonistas del Receptor Purinérgico P2X/síntesis química , Agonistas del Receptor Purinérgico P2X/química

RESUMEN

We have developed an assay for single strand DNA and RNA detection which is based on novel pyrene-perylene FRET pairs attached to short LNA/DNA probes. The assay is based on ratiometric emission upon binding of target DNA/RNA by three combinations of fluorescent LNA/DNA reporter strands. Specific geometry of the pyrene fluorophore attached to the 2'-amino group of 2'-amino-LNA in position 4 allows for the first time to efficiently utilize dipole-dipole orientation parameter for sensing of single-nucleotide polymorphisms (SNPs) in nucleic acid targets by FRET. Using novel probes, SNP detection is achieved with advantages of large Stokes shift (115 nm), high fluorescence quantum yields and low limit of target detection values (< 5 nM). Rapid and accurate genotyping of highly polymorphic HIV Pol cDNA and RNA fragments performed herein proves the possibility for broad application of the novel pyrene-perylene FRET pairs, e.g., in imaging and clinical diagnostics.

Asunto(s)

Colorantes Fluorescentes/química , Técnicas de Genotipaje , Oligonucleótidos/genética , Perileno/química , Pirenos/química , Secuencia de Bases , Sondas de ADN/química , Sondas de ADN/genética , Transferencia Resonante de Energía de Fluorescencia , Genotipo , Humanos , Límite de Detección , Oligonucleótidos/química , Polimorfismo de Nucleótido Simple

RESUMEN

The development of synthetic agents that recognize double-stranded DNA (dsDNA) is a long-standing goal that is inspired by the promise for tools that detect, regulate, and modify genes. Progress has been made with triplex-forming oligonucleotides, peptide nucleic acids, and polyamides, but substantial efforts are currently devoted to the development of alternative strategies that overcome the limitations observed with the classic approaches. In 2005, we introduced Invader locked nucleic acids (LNAs), i.e., double-stranded probes that are activated for mixed-sequence recognition of dsDNA through modification with "+1 interstrand zippers" of 2'-N-(pyren-1-yl)methyl-2'-amino-α-l-LNA monomers. Despite promising preliminary results, progress has been slow because of the synthetic complexity of the building blocks. Here we describe a study that led to the identification of two simpler classes of Invader monomers. We compare the thermal denaturation characteristics of double-stranded probes featuring different interstrand zippers of pyrene-functionalized monomers based on 2'-amino-α-l-LNA, 2'-N-methyl-2'-amino-DNA, and RNA scaffolds. Insights from fluorescence spectroscopy, molecular modeling, and NMR spectroscopy are used to elucidate the structural factors that govern probe activation. We demonstrate that probes with +1 zippers of 2'-O-(pyren-1-yl)methyl-RNA or 2'-N-methyl-2'-N-(pyren-1-yl)methyl-2'-amino-DNA monomers recognize DNA hairpins with similar efficiency as original Invader LNAs. Access to synthetically simple monomers will accelerate the use of Invader-mediated dsDNA recognition for applications in molecular biology and nucleic acid diagnostics.

Asunto(s)

ADN/química , Pirenos/química , Timidina Monofosfato/análogos & derivados , Espectroscopía de Resonancia Magnética , Modelos Químicos , Conformación de Ácido Nucleico , Oligonucleótidos , Espectrometría de Fluorescencia , Timidina Monofosfato/química

RESUMEN

The molecular interaction between adenosine A2A and dopamine D2 receptors (A2ARs and D2Rs, respectively) within an oligomeric complex has been postulated to play a pivotal role in the adenosine-dopamine interplay in the central nervous system, in both normal and pathological conditions (e.g. Parkinson's disease). While the effects of A2AR challenge on D2R functioning have been largely studied, the reverse condition is still unexplored, a fact that might have impact in therapeutics. Here, we aimed to examine in a real-time mode the D2R-mediated allosteric modulation of A2AR binding when an A2AR/D2R oligomer is established. Thus, we synthesized fluorescent A2AR agonists and evaluated, by means of a flow cytometry homogeneous no-wash assay and a real-time fluorescence resonance energy transfer (FRET)-based approach, the effects on A2AR binding of distinct antiparkinsonian drugs in current clinical use (i.e. pramipexole, rotigotine and apomorphine). Our results provided evidence for the existence of a differential D2R-mediated negative allosteric modulation on A2AR agonist binding that was oligomer-formation dependent, and with apomorphine being the best antiparkinsonian drug attenuating A2AR agonist binding. Overall, the here-developed methods were found valid to explore the ability of drugs acting on D2Rs to modulate A2AR binding, thus serving to facilitate the preliminary selection of D2R-like candidate drugs in the management of Parkinson's disease.

Asunto(s)

Agonistas del Receptor de Adenosina A2/metabolismo , Biopolímeros/metabolismo , Receptor de Adenosina A2A/metabolismo , Receptores de Dopamina D2/fisiología , Citometría de Flujo , Transferencia Resonante de Energía de Fluorescencia , Células HEK293 , Humanos , Unión Proteica , Receptores de Dopamina D2/metabolismo

RESUMEN

Activation of a cardiac myocyte P2X4 receptor protects against heart failure. 5'-Phosphonate and 5'-phosphate analogues of AMP containing a (N)-methanocarba (bicyclo[3.1.0]hexane) system could protect from heart failure by potentially activating this cardioprotective channel. Phosphoesters and phosphonodiesters were synthesized and administered in vivo via a miniosmotic pump in a mouse ischemic heart failure model and most significantly increased intact heart contractile function (echocardiography) compared to vehicle infusion. Several new thio and deuterated phosphate derivatives were protective in a calsequestrin (CSQ) overexpressing heart failure model. Diethyl (7, MRS4084) and diisopropyl (8, MRS4074) phosphotriesters were highly protective in the ischemic model. Substitution of 2-Cl with iodo reduced protection in the CSQ model. Diisopropyl ester 16 (MRS2978) of (1'S,2'R,3'S,4'R,5'S)-4'-(6-amino-2-chloropurin-9-yl)-2',3'-(dihydroxy)-1'-(phosphonoethylene)bicyclo[3.1.0]hexane was highly efficacious (CSQ), while lower homologue 1'-phosphonomethylene derivative 14 was inactive. Thus, we identified uncharged carbocyclic nucleotide analogues that represent potential candidates for the treatment of heart failure, suggesting this as a viable and structurally broad approach.

Asunto(s)

Adenosina/análogos & derivados , Cardiotónicos/farmacología , Organofosfonatos/química , Fosfatos/química , Adenosina/química , Adenosina/farmacología , Animales , Cromatografía Líquida de Alta Presión , Modelos Animales de Enfermedad , Ésteres , Espectroscopía de Resonancia Magnética , Ratones , Isquemia Miocárdica/prevención & control , Espectrometría de Masa por Ionización de Electrospray

RESUMEN

Novel pyrene-perylene α-L-LNA FRET pairs described herein effectively detect assembly of 2- and 3-way branched DNA nanostructures prepared by postsynthetic microwave-assisted CuAAC click chemistry. The fluorescent signalling of assembly by internally positioned FRET pairs is achieved with low to no fluorescence background signal, remarkably low limit of target detection values and stabilization of the resulting nanostructures.

Asunto(s)

ADN/química , Nanoestructuras/química , Oligonucleótidos/química , Pirenos/química , Química Clic , ADN/síntesis química , Transferencia Resonante de Energía de Fluorescencia , Microondas

RESUMEN

Gold nanoparticles (AuNPs) allow the tuning of pharmacokinetic and pharmacodynamic properties by active or passive targeting of drugs for cancer and other diseases. We have functionalized gold nanoparticles by tethering specific ligands, agonists and antagonists, of adenosine receptors (ARs) to the gold surface as models for cell surface interactions with G protein-coupled receptors (GPCRs). The AuNP conjugates with chain-extended AR ligands alone (PEGylated nucleosides and nonnucleosides, anchored to the Au via thioctic acid) were found to be insoluble in water due to hydrophobic entities in the ligand. Therefore, we added a second, biologically inactive pendant moiety to increase the water solubility, consisting of a PEGylated chain terminating in a carboxylic or phosphate group. The purity and stability of the immobilized biologically active ligand were examined by ultrafiltration and HPLC. Pharmacological receptor binding studies on these GPCR ligand-derivatized AuNPs (2-5 nm in diameter), performed using membranes of mammalian cells stably expressing human A1, A2A, and A3ARs, showed that the desired selectivity was retained with K(i) values (nanomolar) of A3AR agonist 21b and A2AAR antagonists 24 and 26a of 14 (A3), 34 (A2A), and 69 (A2A), respectively. The corresponding monomers displayed K i values of 37, 61, and 1,420 nM, respectively. In conclusion, we have synthesized stable, water-soluble AuNP derivatives of tethered A3 and A2AAR ligands that retain the biological properties of their monomeric ligands and are intended for therapeutic and imaging applications. This is the first prototypical application to gold carriers of small molecule (nonpeptide) GPCR ligands, which are under investigation for treatment of cancer and inflammatory diseases.

Asunto(s)

Oro , Nanopartículas del Metal , Agonistas del Receptor Purinérgico P1/síntesis química , Antagonistas de Receptores Purinérgicos P1/síntesis química , Receptores Acoplados a Proteínas G , Animales , Células CHO , Cricetinae , Cricetulus , Oro/farmacocinética , Oro/farmacología , Células HEK293 , Humanos , Agonistas del Receptor Purinérgico P1/farmacocinética , Agonistas del Receptor Purinérgico P1/farmacología , Antagonistas de Receptores Purinérgicos P1/farmacocinética , Antagonistas de Receptores Purinérgicos P1/farmacología

RESUMEN

The physiological role of the A(3) adenosine receptor (AR) was explored in cardiac ischaemia, inflammatory diseases and cancer. We report a new fluorophore-conjugated human (h) A(3)AR antagonist for application to cell-based assays in ligand discovery and for receptor imaging. Fluorescent pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ylamine (pyrazolo-triazolo-pyrimidine, PTP) and triazolo[1,5-c]quinazolin-5-yl)amine (triazolo-quinazoline, TQ) AR antagonists were compared. A chain-extended and click-conjugated Alexa Fluor-488 TQ derivative (MRS5449) displayed a radioligand binding K(i) value of 6.4±2.5nM in hA(3)AR-expressing CHO cell membranes. MRS5449 antagonized hA(3)AR agonist-induced inhibition of cyclic AMP accumulation in a concentration-dependent manner (K(B)=4.8nM). Using flow cytometry (FCM), MRS5449 saturated hA(3)ARs with very high specific-to-nonspecific binding ratio with an equilibrium binding constant 5.15nM, comparable to the K(d) value of 6.65nM calculated from kinetic experiments. K(i) values of known AR antagonists in inhibition of MRS5449 binding in whole cell FCM were consistent with radioligand binding in membranes, but agonist binding was 5-20 fold weaker than obtained with agonist radioligand [(125)I]I-AB-MECA. Further binding analysis of MRS5549 suggested multiple agonist binding states of the A(3)AR. Molecular docking predicted binding modes of these fluorescent antagonists. Thus, MRS5449 is a useful tool for hA(3)AR characterization.

Asunto(s)

Antagonistas del Receptor de Adenosina A3/química , Antagonistas del Receptor de Adenosina A3/farmacología , Citometría de Flujo , Pirazoles/química , Pirazoles/farmacología , Piridinas/química , Piridinas/farmacología , Quinazolinas/química , Quinazolinas/farmacología , Receptor de Adenosina A3/fisiología , Triazoles/química , Triazoles/farmacología , Animales , Células CHO , Cricetinae , Fluorescencia , Modelos Químicos , Modelos Moleculares , Estructura Molecular , Unión Proteica/fisiología , Conformación Proteica , Relación Estructura-Actividad

RESUMEN

Molecular modeling of agonist binding to the human A(2A) adenosine receptor (AR) was assessed and extended in light of crystallographic structures. Heterocyclic adenine nitrogens of cocrystallized agonist overlaid corresponding positions of the heterocyclic base of a bound triazolotriazine antagonist, and ribose moiety was coordinated in a hydrophilic region, as previously predicted based on modeling using the inactive receptor. Automatic agonist docking of 20 known potent nucleoside agonists to agonist-bound A(2A)AR crystallographic structures predicted new stabilizing protein interactions to provide a structural basis for previous empirical structure activity relationships consistent with previous mutagenesis results. We predicted binding of novel C2 terminal amino acid conjugates of A(2A)AR agonist CGS21680 and used these models to interpret effects on binding affinity of newly synthesized agonists. d-Amino acid conjugates were generally more potent than l-stereoisomers and free terminal carboxylates more potent than corresponding methyl esters. Amino acid moieties were coordinated close to extracellular loops 2 and 3. Thus, molecular modeling is useful in probing ligand recognition and rational design of GPCR-targeting compounds with specific pharmacological profiles.

Asunto(s)

Agonistas del Receptor de Adenosina A2/química , Adenosina/análogos & derivados , Modelos Moleculares , Nucleósidos/química , Fenetilaminas/química , Receptor de Adenosina A2A/química , Adenosina/síntesis química , Adenosina/química , Adenosina/farmacología , Agonistas del Receptor de Adenosina A2/síntesis química , Agonistas del Receptor de Adenosina A2/farmacología , Aminoácidos/química , Animales , Sitios de Unión , Células CHO , Cricetinae , Cricetulus , Cristalografía por Rayos X , Células HEK293 , Humanos , Ligandos , Fenetilaminas/síntesis química , Fenetilaminas/farmacología , Conformación Proteica , Ensayo de Unión Radioligante , Receptor de Adenosina A2A/metabolismo , Estereoisomerismo , Relación Estructura-Actividad , Termodinámica

RESUMEN

Although a majority of persons with epilepsy in developing countries are diagnosed, treated, and followed up by primary care doctors, few efforts have been made to examine their understanding with respect to epilepsy management. Through a questionnaire survey, we gathered information about the epilepsy management behavior of 500 primary care doctors distributed across the south Indian state of Kerala. Very few of them ever had diagnosed focal seizures, and the majority of them overutilize EEGs, prescribe continuous antiepileptic drug (AED) prophylaxis for febrile convulsions, use relatively expensive AEDs often in combination and in suboptimal doses, and did not know about alternate management options for AED-resistant epilepsies. A substantial proportion of the current large treatment gap in epilepsy in developing countries could be minimized by educating the primary care physicians about the diagnosis of epileptic seizures, cost-effective AED treatment, and need-based referral for specialized care.

Asunto(s)

Anticonvulsivantes/uso terapéutico , Epilepsia/tratamiento farmacológico , Médicos de Atención Primaria/psicología , Médicos de Atención Primaria/estadística & datos numéricos , Anticonvulsivantes/normas , Epilepsia/diagnóstico , Epilepsia/epidemiología , Conocimientos, Actitudes y Práctica en Salud , Encuestas Epidemiológicas , Humanos , India/epidemiología , Pautas de la Práctica en Medicina/estadística & datos numéricos , Características de la Residencia , Encuestas y Cuestionarios

RESUMEN

Pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine derivatives such as SCH 442416 display high affinity and selectivity as antagonists for the human A(2A) adenosine receptor (AR). We extended ether-linked chain substituents at the p-position of the phenyl group using optimized O-alkylation. The conjugates included an ester, carboxylic acid and amines (for amide condensation), an alkyne (for click chemistry), a fluoropropyl group (for (18)F incorporation), and fluorophore reporter groups (e.g., BODIPY conjugate 14, K(i) 15 nM). The potent and A(2A)AR-selective N-aminoethylacetamide 7 and N-[2-(2-aminoethyl)-aminoethyl]acetamide 8 congeners were coupled to polyamidoamine (PAMAM) G3.5 dendrimers, and the multivalent conjugates displayed high A(2A)AR affinity. Theoretical docking of an AlexaFluor conjugate to the receptor X-ray structure highlighted the key interactions between the heterocyclic core and the binding pocket of the A(2A)AR as well as the distal anchoring of the fluorophore. In conclusion, we have synthesized a family of high affinity functionalized congeners as pharmacological probes for studying the A(2A)AR.

Asunto(s)

Antagonistas del Receptor de Adenosina A2 , Diseño de Fármacos , Pirazoles/síntesis química , Pirimidinas/síntesis química , Humanos , Modelos Moleculares , Sondas Moleculares/síntesis química , Sondas Moleculares/química , Estructura Molecular , Pirazoles/química , Pirazoles/farmacología , Pirimidinas/química , Pirimidinas/farmacología

RESUMEN

Hereby we report an efficient synthesis of LNA thymine and LNA 5-methylcytosine 5'-phosphoramidites, allowing incorporation of LNA thymine and LNA 5-methylcytosine into oligonucleotides synthesized in the 5'→3' direction. Key steps include regioselective enzymatic benzoylation of the 5'-hydroxy group of unprotected LNA thymine, and subsequent 4,4'-dimethoxytritylation of the 3'-hydroxy group of the O5'-benzoylated LNA thymine nucleoside.

Asunto(s)

5-Metilcitosina/química , Oligonucleótidos/química , Compuestos Organofosforados/química , Timina/química , 5-Metilcitosina/metabolismo , Candida/enzimología , Proteínas Fúngicas , Lipasa/metabolismo , Estructura Molecular , Oligonucleótidos/metabolismo , Compuestos Organofosforados/metabolismo , Estereoisomerismo , Timina/metabolismo

RESUMEN

Movement disorders such as Parkinson's disease and Huntington's disease are serious life-limiting and debilitating movement disorders. Their onset typically occurs from mid-life to late in life, and effective diagnostic techniques for detecting and following the disease course are lacking. Our goal is to develop receptor imaging agents for positron emission tomography (PET) that selectively target the most relevant subtype of adenosine receptors (AR) that are highly expressed in the striatum, that is, the A(2A) AR. To further this goal, we have synthesized and characterized pharmacologically a family of high affinity A(2A) AR ligands, based on the known antagonist, SCH 442416 (R=-Me), which have structural variability on the terminus (R=-Et, -i-Pr, -allyl, and others). A O-fluoroethyl analogue suitable for use as a PET tracer had a K(i) value of 12.4 nM and was highly selective for the A(2A) AR in comparison to the A(1) and A(3) ARs.

Asunto(s)

Antagonistas del Receptor de Adenosina A2/síntesis química , Medios de Contraste/síntesis química , Pirimidinas/química , Receptor de Adenosina A2A/química , Triazoles/química , Antagonistas del Receptor de Adenosina A2/química , Antagonistas del Receptor de Adenosina A2/farmacología , Sitios de Unión , Línea Celular , Simulación por Computador , Medios de Contraste/química , Radioisótopos de Flúor/química , Humanos , Tomografía de Emisión de Positrones , Estructura Terciaria de Proteína , Pirazoles/química , Pirimidinas/síntesis química , Receptor de Adenosina A2A/metabolismo

RESUMEN

Fluorescence polarization (FP) assay has many advantages over the traditional radioreceptor binding studies. We developed an A(2A) adenosine receptor (AR) FP assay using a newly synthesized fluorescent antagonist of the A(2A)AR (MRS5346), a pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine derivative conjugated to the fluorescent dye Alexa Fluor-488. MRS5346 displayed a K(i) value of 111+/-16nM in radioligand binding using [(3)H]CGS21680 and membranes prepared from HEK293 cells stably expressing the human A(2A)AR. In a cyclic AMP functional assay, MRS5346 was shown to be an A(2A)AR antagonist. MRS5346 did not show any effect on A(1) and A(3) ARs in binding or the A(2B)AR in a cyclic AMP assay at 10microM. Its suitability as a fluorescent tracer was indicated in an initial observation of an FP signal following A(2A)AR binding. The FP signal was optimal with 20nM MRS5346 and 150microg protein/mL HEK293 membranes. The association and dissociation kinetic parameters were readily determined using this FP assay. The K(d) value of MRS5346 calculated from kinetic parameters was 16.5+/-4.7nM. In FP competition binding experiments using MRS5346 as a tracer, K(i) values of known AR agonists and antagonists consistently agreed with K(i) values from radioligand binding. Thus, this FP assay, which eliminates using radioisotopes, appears to be appropriate for both routine receptor binding and high-throughput screening with respect to speed of analysis, displaceable signal and precision. The approach used in the present study could be generally applicable to other GPCRs.

Asunto(s)

Antagonistas del Receptor de Adenosina A2 , Adenosina/análogos & derivados , Animales , Células CHO , Células Cultivadas , Técnicas de Laboratorio Clínico , Cricetinae , Cricetulus , Relación Dosis-Respuesta a Droga , Colorantes Fluorescentes/química , Humanos , Antagonistas de Receptores Purinérgicos P1 , Receptor de Adenosina A3

RESUMEN

Despite progress with triplex-forming oligonucleotides or helix-invading peptide nucleic acids (PNAs), there remains a need for probes facilitating sequence-unrestricted targeting of double stranded DNA (dsDNA) at physiologically relevant conditions. Invader LNA probes, i.e., DNA duplexes with "+1 interstrand zipper arrangements" of intercalator-functionalized 2'-amino-alpha-l-LNA monomers, are demonstrated herein to recognize short mixed sequence dsDNA targets. This approach, like pseudo-complementary PNA (pcPNA), relies on relative differences in stability between probe duplexes and the corresponding probe:target duplexes for generation of a favourable thermodynamic gradient. Unlike pcPNA, Invader LNA probes take advantage of the "nearest neighbour exclusion principle", i.e., intercalating units of Invader LNA monomers are poorly accommodated in probe duplexes but extraordinarily well tolerated in probe-target duplexes (DeltaT(m)/modification up to +11.5 degrees C). Recognition of isosequential dsDNA-targets occurs: a) at experimental temperatures much lower than the thermal denaturation temperatures (T(m)'s) of Invader LNAs or dsDNA-targets, b) at a wide range of ionic strengths, and c) with good mismatch discrimination. Recognition of dsDNA is monitored in real-time using inherent pyrene-pyrene excimer signals of Invader LNA probes, which provides insights into reaction kinetics and enables rational design of probes. These properties render Invader LNAs as promising probes for biomedical applications entailing sequence-unrestricted recognition of dsDNA.

Asunto(s)

ADN/química , Sondas de Oligonucleótidos/química , Oligonucleótidos/química , Cinética , Conformación de Ácido Nucleico , Desnaturalización de Ácido Nucleico , Temperatura , Termodinámica

RESUMEN

Evidence is accumulating to support a potentially important role for purinergic (P2X) receptors in heart failure (HF). We tested the hypothesis that a hydrolysis-resistant nucleotide analog with agonist activity at myocardial P2X receptors (P2XRs) improves the systolic HF phenotype in mouse and dog models. We developed a hydrolysis-resistant adenosine monophosphate derivative, (1'S,2R,3S,4'R,5'S)-4-(6-amino-2-chloro-9H-purin-9-yl)-1-[phosphoryloxymethyl] bicycle[3.1.0]hexane-2,3-diol) (MRS2339), with agonist activity at native cardiac P2XRs. Chronic MRS2339 infusion in postinfarct and calsequestrin (CSQ) mice with HF resulted in higher rates of pressure change (+dP/dt), left ventricle (LV)-developed pressure, and cardiac output in an in vitro working heart model. Heart function in vivo, as determined by echocardiography-derived fractional shortening, was also improved in MRS2339-infused mice. The beneficial effect of MRS2339 was dose-dependent and was identical to that produced by cardiac myocyte-specific overexpression of the P2X(4) receptor. The HF improvement was associated with the preservation of LV wall thickness in both systole and diastole in postinfarct and CSQ mice. In dogs with pacing-induced HF, MRS2339 infusion reduced left ventricular end-diastolic pressure, improved arterial oxygenation, and increased +dP/dt. MRS2339 treatment also decreased LV chamber size in mice and dogs with HF. In murine and canine models of systolic HF, in vivo administration of a P2X nucleotide agonist improved contractile function and cardiac performance. These actions were associated with preserved LV wall thickness and decreased LV remodeling. The data are consistent with a role of cardiac P2XRs in mediating the beneficial effect of this agonist.

Asunto(s)

Adenosina Monofosfato/análogos & derivados , Adenosina Monofosfato/uso terapéutico , Insuficiencia Cardíaca/tratamiento farmacológico , Corazón/efectos de los fármacos , Receptores Purinérgicos P2/efectos de los fármacos , Animales , Estimulación Cardíaca Artificial , Cardiomiopatía Dilatada/tratamiento farmacológico , Perros , Insuficiencia Cardíaca/diagnóstico por imagen , Pruebas de Función Cardíaca , Hemodinámica/efectos de los fármacos , Infusiones Intravenosas , Masculino , Ratones , Ratones Transgénicos , Contracción Miocárdica/efectos de los fármacos , Miocardio/metabolismo , Receptores Purinérgicos P2/biosíntesis , Receptores Purinérgicos P2/genética , Taquicardia/tratamiento farmacológico , Ultrasonografía , Función Ventricular Izquierda/efectos de los fármacos

RESUMEN

P2X receptor activation protects in heart failure models. MRS2339 3, a 2-chloro-AMP derivative containing a (N)-methanocarba (bicyclo[3.1.0]hexane) system, activates this cardioprotective channel. Michaelis-Arbuzov and Wittig reactions provided phosphonate analogues of 3, expected to be stable in vivo due to the C-P bond. After chronic administration via a mini-osmotic pump (Alzet), some analogues significantly increased intact heart contractile function in calsequestrin-overexpressing mice (genetic model of heart failure) compared to vehicle-infused mice (all inactive at the vasodilatory P2Y(1) receptor). Two phosphonates, (1'S,2'R,3'S,4'R,5'S)-4'-(6-amino-2-chloropurin-9-yl)-2',3'-(dihydroxy)-1'-(phosphonomethylene)-bicyclo[3.1.0]hexane, 4 (MRS2775), and its homologue 9 (MRS2935), both 5'-saturated, containing a 2-Cl substitution, improved echocardiography-derived fractional shortening (20.25% and 19.26%, respectively, versus 13.78% in controls), while unsaturated 5'-extended phosphonates, all 2-H analogues, and a CH(3)-phosphonate were inactive. Thus, chronic administration of nucleotidase-resistant phosphonates conferred a beneficial effect, likely via cardiac P2X receptor activation. Thus, we have greatly expanded the range of carbocyclic nucleotide analogues that represent potential candidates for the treatment of heart failure.

Asunto(s)

Adenosina Monofosfato/farmacología , Cardiotónicos/farmacología , Organofosfonatos/farmacología , Agonistas del Receptor Purinérgico P2 , Adenosina Monofosfato/administración & dosificación , Adenosina Monofosfato/análogos & derivados , Adenosina Monofosfato/química , Animales , Calcio/metabolismo , Cardiotónicos/administración & dosificación , Cardiotónicos/síntesis química , Línea Celular Tumoral , Ecocardiografía , Femenino , Corazón/efectos de los fármacos , Corazón/fisiopatología , Humanos , Bombas de Infusión , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Masculino , Ratones , Modelos Químicos , Estructura Molecular , Miocardio/metabolismo , Miocardio/patología , Organofosfonatos/administración & dosificación , Organofosfonatos/química , Receptores Purinérgicos P2/metabolismo , Receptores Purinérgicos P2X , Receptores Purinérgicos P2Y1 , Relación Estructura-Actividad