Prevention and rescue of cardiac dysfunction by methanocarba adenosine monophosphonate derivatives.

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.

Lipid Trolling to Optimize A3 Adenosine Receptor-Positive Allosteric Modulators (PAMs).

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.

Identification and characterization of second-generation invader locked nucleic acids (LNAs) for mixed-sequence recognition of double-stranded DNA.

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.

Modulation of G protein-coupled adenosine receptors by strategically functionalized agonists and antagonists immobilized on gold nanoparticles.

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.

Examining the Triple Burden of Malnutrition: Insights from a Community-Based Comprehensive Nutrition Survey among Indigenous Tribal Children (0-19 Years) in the Western Ghats Hills of India.

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.

SARS-CoV-2 seroprevalence in the city of Hyderabad, India in early 2021.

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.

Molecular probes for the A2A adenosine receptor based on a pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine scaffold.

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.

Primary care doctors' management behavior with respect to epilepsy in Kerala, southern India.

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.

Treatment of heart failure by a methanocarba derivative of adenosine monophosphate: implication for a role of cardiac purinergic P2X receptors.

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.

Synthesis and evaluation of 1,2,4-triazolo[1,5-c]pyrimidine derivatives as A2A receptor-selective antagonists.

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.

LNA 5'-phosphoramidites for 5'→3'-oligonucleotide synthesis.

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.

Invader LNA: efficient targeting of short double stranded DNA.

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.

Functionalized 2'-amino-alpha-L-LNA: directed positioning of intercalators for DNA targeting.

Chemically modified oligonucleotides are increasingly applied in nucleic acid based therapeutics and diagnostics. LNA (locked nucleic acid) and its diastereomer alpha-L-LNA are two promising examples thereof that exhibit increased thermal and enzymatic stability. Herein, the synthesis, biophysical characterization, and molecular modeling of N2'-functionalized 2'-amino-alpha-L-LNA is described. Chemoselective N2'-functionalization of protected amino alcohol 1 followed by phosphitylation afforded a structurally varied set of target phosphoramidites, which were incorporated into oligodeoxyribonucleotides. Incorporation of pyrene-functionalized building blocks such as 2'-N-(pyren-1-yl)carbonyl-2'-amino-alpha-L-LNA (monomer X) led to extraordinary increases in thermal affinity of up to +19.5 degrees C per modification against DNA targets in particular. In contrast, incorporation of building blocks with small nonaromatic N2'-functionalities such as 2'-N-acetyl-2'-amino-alpha-L-LNA (monomer V) had detrimental effects on thermal affinity toward DNA/RNA complements with decreases of as much as -16.5 degrees C per modification. Extensive thermal DNA selectivity, favorable entropic contributions upon duplex formation, hybridization-induced bathochromic shifts of pyrene absorption maxima and increases in circular dichroism signal intensity, and molecular modeling studies suggest that pyrene-functionalized 2'-amino-alpha-L-LNA monomers W-Y having short linkers between the bicyclic skeleton and the pyrene moiety allow high-affinity hybridization with DNA complements and precise positioning of intercalators in nucleic acid duplexes. This rigorous positional control has been utilized for the development of probes for emerging therapeutic and diagnostic applications focusing on DNA targeting.

Parallel RNA-strand recognition by 2'-amino-beta-L-LNA.

A short synthetic route to the first beta-l-ribo configured locked nucleic acid (LNA), that is, 2'-amino-beta-l-LNA thymine phosphoramidite 6, has been developed from bicyclic nucleoside 1. Incorporation of 2'-amino-beta-l-LNA thymine monomers into alpha-DNA strands results in probes forming stable duplexes with complementary RNA in parallel orientation.

Oral health status and practices of dentate Bhil adult tribes of southern Rajasthan, India.

AIMS: To assess the oral health status of the Bhil tribal population of Southern Rajasthan and to investigate the association of age, oral hygiene and dental visiting practices with oral health status. DESIGN: A cross sectional study of Bhil tribal adults chosen by a multi stage stratified random sampling procedure. PARTICIPANTS: The total sample size was 1590 male tribal dentate subjects aged 15-54 years. METHODS: Clinical recordings of oral hygiene status (OHI-S), caries status (DMFT and DMFS) and treatment needs, and periodontal status (CPI). The Chi square test was applied to discrete data and one way ANOVA for continuous data. Multivariate analyses were carried out to test the association of age, frequency of cleaning teeth, material used for cleaning teeth and dental visiting habits with caries and periodontal status. RESULTS: Debris, calculus and oral hygiene index scores increased with age. The overall mean DMFT and DMFS scores were 5.34 +/- 6.48 and 18.94 +/- 35.87 respectively. Extraction was the most required treatment (1.74 +/- 3.66 teeth) followed by one surface fillings (1.34 +/- 1.65 teeth). Shallow periodontal pockets were prevalent (40%) among the 35-44 years age group whereas deep pockets were most common (11.6%) in the oldest age group. More than half the sextants (3.15) were excluded amongst the oldest study group. All the independent variables namely age, frequency of cleaning teeth, substance used for cleaning teeth and visiting habits were statistically significantly related to caries and periodontal status. CONCLUSIONS: The study population was characterised by a lack of previous dental care, high treatment needs, high prevalence of periodontal disease and poor oral hygiene. Under these circumstances, the implementation of a basic oral health care programme for the Bhil population is a high priority.

Nucleic acid structural engineering using pyrene-functionalized 2'-amino-alpha-L-LNA monomers and abasic sites.

Oligonucleotides (ONs) modified with a 2'-N-(pyren-1-yl)acetyl-2'-amino-alpha-L-LNA thymine monomer Y flanked on the 3'-side by an abasic site Phi (i.e., YPhi-unit) exhibit unprecedented increases in thermal affinity (DeltaT(m) values) toward target strands containing abasic sites (DeltaT(m) per YPhi unit >+33.0 degrees C in 9-mer duplexes relative to unmodified ONs). Biophysical studies along with force field calculations suggest that the conformationally locked 2-oxo-5-azabicyclo[2.2.1]heptane skeleton of monomer Y, in concert with the short rigid acetyl linker, efficiently forces the thymine and pyrene moieties to adopt an interplanar distance of approximately 3.4 A. This precisely positions the pyrene moiety in the duplex core void formed by abasic sites (Phi:Phi pair) for optimal pi-pi overlap. Duplexes with multiple YPhi: APhi units separated by one base pair are tolerated extraordinarily well, as exemplified by a 13-mer duplex containing four separated YPhi: APhi units (8 abasic sites distributed over 13 "base pairs"), which exhibit a thermal denaturation temperature of 60.5 degrees C. The YPhi probes display up to 16-fold increases in fluorescence intensity at 380 nm upon hybridization with abasic target strands, whereby self-assembly of these complex architectures can be easily monitored. This study underlines the potential of N2'-functionalized 2'-amino-alpha-L-LNA as building blocks in nucleic acid based diagnostics and nanomaterial engineering.

Dental caries experience and treatment needs of green marble mine laborers in Udaipur district, Rajasthan, India.

BACKGROUND AND OBJECTIVES: The study was undertaken at Kesariyaji, located in Udaipur district of Rajasthan. There are about 3 million workers who marble mine at Rajasthan. Living conditions of these workers are substandard and most of them are immigrant workers living in tiny shacks. Majority of them belong to lower socioeconomic status with poor educational background. The present study was carried out to estimate dental caries prevalence and treatment needs of laborers working in the green marble mines of Udaipur district. BASIC RESEARCH DESIGN: The data was collected using the methods and standards recommended by the WHO. Dentition status and treatment needs along with decayed, missing, and filled teeth (DMFT) index, and decayed, missing, and filled surfaces score were recorded. Standard error of mean was calculated for all the mean values of treatment needs. There were three examiners, who were trained before the survey for inter-examiner variability, and the reliability was tested by means of weighted kappa statistics, which was 90%. PARTICIPANTS: The study population comprised 513 men in four age groups of 18-25, 26-34, 35-44, and 45-54 years, respectively. RESULTS: The mean DMFT for all age groups was 3.13 with highest mean of 4.0 for the age group of 45-54 years. Mean decayed teeth were 2.60, 3.33, 1.46, and 1.5 for the age groups 15-24, 25-34, 35-44, and 45-54 years, respectively. Filled component was nil for all age groups. Most of the subjects required one surface filling with a very less proportion needing pulp care. CONCLUSIONS: The missing component constituted the major part of DMFT index in the 45-54 years age group and the absence of filled component in the whole study population implies that the treatment needs of the study population are unmet. Thus, intervention in the form of oral health promotion and curative services are the need of the hour.

Pyrene-functionalized 2'-amino-alpha-L-LNA as potential diagnostic probes.

Oligodeoxyribonucleotides (ONs) containing two incorporations of 2'-N-(pyren-1-yl)acetyl-2'-amino-alpha-L-LNA monomer Y are sensitive probes for detection of single nucleotide polymorphisms (SNP) in DNA. In addition, the ability of ONs containing pyrene-functionalized 2'-amino-alpha-L-LNA monomers (W-Z) to stabilize duplexes with an abasic site is demonstrated.

Synthesis and biophysical studies of N2'-functionalized 2'-amino-alpha-L-LNA.

A synthetic route towards a selected set of N-acylated and N-alkylated derivatives of 2'-amino-alpha-L-LNA phosphoramidite building blocks has been developed. Biophysical studies suggest that the 2-oxo-5-azabicyclo[2.2.1]heptane skeleton of 2'-amino-alpha-L-LNA allows precise positioning of intercalators in the core of nucleic acid duplexes.

Synthesis, nucleic acid hybridization properties and molecular modelling studies of conformationally restricted 3'-O,4'-C-methylene-linked alpha-L-ribonucleotides.

Nucleotides with conformationally restricted carbohydrate rings such as locked nucleic acid (LNA), alpha-L-LNA or 2',5'-linked 3'-O,4'-C-methyleribonucleotides exhibit significant potential as building blocks for antigene and antisense strategies. 2',5'-Linked alpha-L-ribo configured monomer X (termed alpha-L-ONA) was designed as a potential structural mimic of alpha-L-LNA. The corresponding phosphoramidite building block of monomer X was obtained in five steps (10% overall yield) from the easily obtainable thymine derivative 1. Incorporation of monomer X into oligodeoxyribonucleotides (ONs) results in dramatically decreased thermal stabilities with DNA/RNA complements (DeltaTm/mod=-11.5 to -17.0 degrees C) compared to unmodified reference ONs. Less pronounced decreases (DeltaTm/mod=-4.5 to -8.5 degrees C) are observed when monomer X is incorporated into triplex forming ONs and targeted against double-stranded DNA (parallel orientation, pyrimidine motif). This biophysical data, together with modelling studies, suggest that 2',5'-linked alpha-L-ONA is a poor structural mimic of alpha-L-LNA.