Automated Synthesis of 3‘-Metalated Oligonucleotides

We report the first synthesis of a metallonucleoside bound to a solid support and subsequent oligonucleotide synthesis with this precursor. Large-scale syntheses of metal-containing oligonucleotides are achieved using a solid support modified with [Ru(bpy)_2(impy‘)]^(2+) (bpy is 2,2‘-bipyridine; impy‘ is 2‘-iminomethylpyridyl-2‘-deoxyuridine). A duplex formed with the metal-containing oligonucleotide exhibits superior thermal stability when compared to the corresponding unmetalated duplex (Tm = 50 °C vs T_m = 48 °C). Electrochemical (E_(1/2) = 1.3 V vs NHE), absorption (λ_(max) = 480 nm), and emission (λ_(max) = 720 nm, τ = 44 ns, Φ = 0.11 × 10^(-3)) data for the ruthenium-modified oligonucleotides indicate that the presence of the oligonucleotide does not perturb the electronic properties of the ruthenium complex. The absence of any change in the emission properties upon duplex formation suggests that the [Ru(bpy)_2(impy)]^(2+) chromophore will be a valuable probe for DNA-mediated electron-transfer studies. Despite the relatively high Ru(III/II) reduction potential, oxidative quenching of photoexcited [Ru(bpy)_2(impy)]^(2+) does not lead to oxidative damage of guanine or other DNA bases

Synthesis and Characterization of Ruthenium and Rhenium Nucleosides

We report the synthesis and characterization of new ruthenium and rhenium nucleosides [Ru(tolyl-acac)_2(IMPy)-T] (tolyl-acac = di(p-methylbenzonatemethane), IMPy = 2‘-iminomethylpyridine, T = thymidine) (5) and [Re(CO)_3(IMPy)-T]Cl (9), respectively. Structural analysis of 9 shows that the incorporation of this metal complex causes minimal perturbation to the sugar backbone and the nucleobase. Eletrochemical (5, E_(1/2) = 0.265 V vs NHE; 9, E_(1/2) = 1.67 V vs NHE), absorption (5, λ_(max) = 600, 486 nm; 9, λ_(max) = 388 nm), and emission (9, λ_(max) = 770 nm, π = 17 ns) data indicate that 5 and 9 are suitable probes for DNA-mediated ground-state electron-transfer studies. The separation and characterization of diastereoisomers of 5 and bipyridyl-based ruthenium nucleoside [Ru(bpy)_2(IMPy)-T]^(2+) (7) are reported

Synthesis, Crystal Structure, Magnetic, and Electron Paramagnetic Resonance Properties of a Spiroconjugated Biradical. Evidence for Spiroconjugation Exchange Pathway

A spiroconjugated nitronyl nitroxide biradical, 6,6‘-(4,4,5,5-tetramethylimidazolidine-3-oxide-1-oxyl)-3,3,3‘,3‘-tetramethyl-1,1‘-spirobisindane (1), has been prepared by functionalization of a 3,3,3‘,3‘-tetramethyl-1,1‘-spirobisindane framework followed by Ullman condensation and subsequent oxidation. The biradical crystallizes in the monoclinic space group C2/c with four molecules in the unit cell of dimensions a = 24.861(10) Å, b = 12.129(3) Å, and c = 12.258(6) Å. X-ray analysis of a blue-plate single crystal has revealed dihedral angles of 28° between the nitronyl nitroxide moiety and aromatic ring with intramolecular through space radical−radical distances of 8.25 and 10.11 Å. In the solid state, the temperature dependence of the molar magnetic susceptibility reveals antiferromagnetic interactions. These interactions are best fit using a pair model, affording the value J = −4.0 cm^(-1) where J is the interaction parameter appearing in the spin Hamiltonian H = −JS_1·S_2. The field dependence of the magnetization measured at 2 K is consistent with a pair model. Frozen matrix EPR spectra of biradical 1 in CH_2Cl_2 at 100 K shows a half field transition at 1700 G. Temperature dependence of the half field transition intensity has been found to be consistent with a ground singlet state and thermally accessible triplet state. The magnetic interaction observed in the solid state is also observed in solution. Thus, room-temperature solution spectra display a nine-line pattern, with hyperfine coupling to four “equivalent” nitrogen atoms and a hyperfine coupling constant a_N = 3.8 G. Temperature dependence of the solution EPR spectra of biradical 1 displays alternating line width effects caused by conformational dynamics in solution. This behavior has been attributed to modulation of exchange and hyperfine interactions most likely caused by rotational motion about the nitronyl nitroxide−phenyl bond. Biradical 1 therefore exists as a ground-state singlet with a thermally accessible triplet at ca. 4 cm^(-1) higher in energy with a conformational dependence of intramolecular exchange in solution. This coupling may present evidence for spiroconjugation as an exchange pathway. Density functional calculations (B3/6-311G(D)) have been performed to investigate this possibility

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions

5‘ Modification of Duplex DNA with a Ruthenium Electron Donor−Acceptor Pair Using Solid-Phase DNA Synthesis

Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor−acceptor pair of 5‘ metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5‘ modified phosporamidites containing [Ru(acac)_2(IMPy)]^(2+) (acac is acetylacetonato; IMPy is 2‘-iminomethylpyridyl-2‘-deoxyuridine) (3) and [Ru(bpy)_2(IMPy)]^(2+) (bpy is 2,2‘-bipyridine; IMPy is 2‘-iminomethylpyridyl-2‘-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T_m of modified duplex = 49 °C vs T_m of unmodified duplex = 47 °C). Electrochemical (3, E_(1/2) = −0.04 V vs NHE; 4, E_(1/2) = 1.12 V vs NHE), absorption (3, λ_(max) = 568, 369 nm; 4, λ_(max) = 480 nm), and emission (4, λ_(max) = 720 nm, τ = 55 ns, Φ = 1.2 × 10-4) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the [Ru(bpy)_2(IMPy)]^(2+)[Ru(acac)_2(IMPy)]^(2+) pair will provide a valuable probe for DNA-mediated electron-transfer studies

Modulating Short Wavelength Fluorescence with Long Wavelength Light

Two molecules in which the intensity of shorter-wavelength fluorescence from a strong fluorophore is modulated by longer-wavelength irradiation of an attached merocyanine-spirooxazine reverse photochromic moiety have been synthesized and studied. This unusual fluorescence behavior is the result of quenching of fluorophore fluorescence by the thermally stable, open, zwitterionic form of the spirooxazine, whereas the photogenerated closed, spirocyclic form has no effect on the fluorophore excited state. The population ratio of the closed and open forms of the spirooxazine is controlled by the intensity of the longer-wavelength modulated light. Both square wave and sine wave modulation were investigated. Because the merocyanine-spirooxazine is an unusual reverse photochrome with a thermally stable long-wavelength absorbing form and a short-wavelength absorbing photogenerated isomer with a very short lifetime, this phenomenon does not require irradiation of the molecules with potentially damaging ultraviolet light, and rapid modulation of fluorescence is possible. Molecules demonstrating these properties may be useful in fluorescent probes, as their use can discriminate between probe fluorescence and various types of adventitious autofluorescence from other molecules in the system being studied