Pulsed-Interleaved-Excitation Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy.

We report on pulsed-interleaved-excitation two-dimensional fluorescence lifetime correlation spectroscopy (PIE 2D FLCS) to study biomolecular structural dynamics with high sensitivity and high time resolution using Förster resonance energy transfer (FRET). PIE 2D FLCS is an extension of 2D FLCS, which is a unique single-molecule fluorescence method that uses fluorescence lifetime information to distinguish different fluorescence species in equilibrium and resolves their interconversion dynamics with a submicrosecond time resolution. Because 2D FLCS has used only a single-color excitation so far, it was difficult to distinguish a very low-FRET (or zero-FRET) species from only donor-labeled species.

A Toxicogenic Interaction between Intracellular Amyloid-β and Apolipoprotein-E.

Alzheimer's disease (AD) is associated with the aggregation of amyloid β (Aβ) and tau proteins. Why ApoE variants are significant genetic risk factors remains a major unsolved puzzle in understanding AD, although intracellular interactions with ApoE are suspected to play a role. Here, we show that specific changes in the fluorescence lifetime of fluorescently tagged small Aβ oligomers in rat brain cells correlate with the cellular ApoE content.

Single-photon smFRET. III. Application to pulsed illumination.

Förster resonance energy transfer (FRET) using pulsed illumination has been pivotal in leveraging lifetime information in FRET analysis. However, there remain major challenges in quantitative single-photon, single-molecule FRET (smFRET) data analysis under pulsed illumination including 1) simultaneously deducing kinetics and number of system states; 2) providing uncertainties over estimates, particularly uncertainty over the number of system states; and 3) taking into account detector noise sources such as cross talk and the instrument response function contributing to uncertainty; in addition to 4) other experimental noise sources such as background. Here, we implement the Bayesian nonparametric framework described in the first companion article that addresses all aforementioned issues in smFRET data analysis specialized for the case of pulsed illumination.

Microsecond Folding of preQ Riboswitch and Its Biological Significance Revealed by Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy.

Riboswitches are regulatory elements of bacterial mRNA which function with conformational switching upon binding of specific cellular metabolites. In particular, transcriptional riboswitches regulate gene expression kinetically through the conformational change of the aptamer domain. In this study, we investigate the conformational dynamics and ligand binding mechanisms of the aptamer domain of a transcriptional prequeuosine (preQ) riboswitch from using two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS) with microsecond time resolution.

Closing the gap on institutional delivery in northern India: a case study of how integrated machine learning approaches can enable precision public health.

Introduction: Meeting ambitious global health goals with limited resources requires a precision public health (PxPH) approach. Here we describe how integrating data collection optimisation, traditional analytics and causal artificial intelligence/machine learning (ML) can be used in a use case for increasing hospital deliveries of newborns in Uttar Pradesh, India.

Methods: Using a systematic behavioural framework we designed a large-scale survey on perceptual, interpersonal and structural drivers of women's behaviour around childbirth (n=5613).

Microsecond Conformational Dynamics of Biopolymers Revealed by Dynamic-Quenching Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy with Single Dye Labeling.

The single-molecule Förster resonance energy transfer (smFRET) technique is widely used for studying conformational dynamics of biopolymers. However, smFRET requires double dye labeling and is usually utilized for detecting dynamics on slow time scales (≳ milliseconds). In this Letter, we report dynamic-quenching two-dimensional fluorescence lifetime correlation spectroscopy (DQ 2D FLCS) that can elucidate the microsecond conformational dynamics of biopolymers with only single dye labeling.

Fluorogenic Detection of Monoamine Neurotransmitters in Live Cells.

Monoamine neurotransmission is key to neuromodulation, but imaging monoamines in live neurons has remained a challenge. Here we show that externally added ortho-phthalaldehyde (OPA) can permeate live cells and form bright fluorogenic adducts with intracellular monoamines (e.g.

Effectiveness of a brief community outreach tobacco cessation intervention in India: a cluster-randomised controlled trial (the BABEX Trial).

Background: Tobacco use kills half a million people every month, most in low-middle income countries (LMICs). There is an urgent need to identify potentially low-cost, scalable tobacco cessation interventions for these countries.

Objective: To evaluate a brief community outreach intervention delivered by health workers to promote tobacco cessation in India.

The Social Gradient in Tobacco Use Does Not Generalize to Low-Income Urban Communities in India: Findings From a Census Survey.

Introduction: The existence of a social gradient in tobacco use has been clearly established in a number of countries with people with lower socioeconomic status being more likely to use tobacco. It is not clear how far this gradient is evident within severely deprived communities. This study assessed the association between occupation as a marker of socioeconomic status and use of smoked and smokeless tobacco within "slum" areas of Delhi, India.

Cardiac Rehabilitation Delivery Model for Low-Resource Settings: An International Council of Cardiovascular Prevention and Rehabilitation Consensus Statement.

Cardiovascular disease (CVD) is a global epidemic, which is largely preventable. Cardiac rehabilitation (CR) is demonstrated to be efficacious and cost-effective for secondary prevention in high-income countries. Given its affordability, CR should be more broadly implemented in middle-income countries as well.

Cardiac rehabilitation delivery model for low-resource settings.

Objective: Cardiovascular disease is a global epidemic, which is largely preventable. Cardiac rehabilitation (CR) is demonstrated to be cost-effective and efficacious in high-income countries. CR could represent an important approach to mitigate the epidemic of cardiovascular disease in lower-resource settings.

Steric Crowding of the Turn Region Alters the Tertiary Fold of Amyloid-β18-35 and Makes It Soluble.

Aβ self-assembles into parallel cross-β fibrillar aggregates, which is associated with Alzheimer's disease pathology. A central hairpin turn around residues 23-29 is a defining characteristic of Aβ in its aggregated state. Major biophysical properties of Aβ, including this turn, remain unaltered in the central fragment Aβ18-35.

Cross-sectional serologic assessment of immunity to poliovirus infection in high-risk areas of northern India.

Introduction: The objectives of this survey were to assess the seroprevalence of antibodies to poliovirus types 1 and 3 and the impact of bivalent (types 1 and 3) oral poliovirus vaccine (bOPV) use in immunization campaigns in northern India.

Methods: In August 2010, a 2-stage stratified cluster sampling method identified infants aged 6-7 months in high-risk blocks for wild poliovirus infection. Vaccination history, weight and length, and serum were collected to test for neutralizing antibodies to poliovirus types 1, 2, and 3.

An acute flaccid paralysis surveillance-based serosurvey of poliovirus antibodies in Western Uttar Pradesh, India.

Background: Despite intensified use of monovalent oral poliovirus type 1 vaccine and improved coverage of immunization campaigns, wild poliovirus type 1 persisted in Indian states of Uttar Pradesh and Bihar during 2006 to 2009.

Methods: A serosurvey was conducted among cases of acute flaccid paralysis in the 25 high-polio-incidence districts of western Uttar Pradesh. Children were recruited by age group (6-11 months, 12-24 months, and 25-69 months) from among cases reported through the acute flaccid paralysis surveillance system between November 2008 and August 2009.

Assessing population immunity in a persistently high-risk area for wild poliovirus transmission in India: a serological study in Moradabad, Western Uttar Pradesh.

Background: Moradabad district in Uttar Pradesh reported the highest number of paralytic polio cases in India during 2001-2007. We conducted a study in Moradabad in 2007 to assess seroprevalence against poliovirus types 1, 2, and 3 in children 6-12 and 36-59 months of age to guide future strategies to interrupt wild poliovirus transmission in high-risk areas.

Methods: Children attending 10 health facilities for minor illnesses who met criteria for study inclusion were eligible for enrollment.

Significant structural differences between transient amyloid-β oligomers and less-toxic fibrils in regions known to harbor familial Alzheimer's mutations.

Small oligomers of the amyloid β (Aβ) peptide, rather than the monomers or the fibrils, are suspected to initiate Alzheimer's disease (AD). However, their low concentration and transient nature under physiological conditions have made structural investigations difficult. A method for addressing such problems has been developed by combining rapid fluorescence techniques with slower two-dimensional solid-state NMR methods.

Label-free dopamine imaging in live rat brain slices.

Dopaminergic neurotransmission has been investigated extensively, yet direct optical probing of dopamine has not been possible in live cells. Here we image intracellular dopamine with sub-micrometer three-dimensional resolution by harnessing its intrinsic mid-ultraviolet (UV) autofluorescence. Two-photon excitation with visible light (540 nm) in conjunction with a non-epifluorescent detection scheme is used to circumvent the UV toxicity and the UV transmission problems.

Curcumin alters the salt bridge-containing turn region in amyloid β(1-42) aggregates.

Amyloid β (Aβ) fibrillar deposits in the brain are a hallmark of Alzheimer disease (AD). Curcumin, a common ingredient of Asian spices, is known to disrupt Aβ fibril formation and to reduce AD pathology in mouse models. Understanding the structural changes induced by curcumin can potentially lead to AD pharmaceutical agents with inherent bio-compatibility.

Perception and practices of physicians in addressing the smokeless tobacco epidemic: findings from two States in India.

Background: Smokeless tobacco use in South Asia is believed to be a significant contributor to morbidity and mortality. In India, only a few studies involving health educational intervention by health care providers have demonstrated reduction in smokeless tobacco usage. In the present study we assessed the cessation efforts towards smokeless tobacco by physicians in two high tobacco prevalence states of India.

A cluster randomized controlled trial of a brief tobacco cessation intervention for low-income communities in India: study protocol.

Background: India has 275 million adult tobacco users and tobacco use is estimated to contribute to more than a million deaths in the country each year. There is an urgent need to develop and evaluate affordable, practicable and scalable interventions to promote cessation of tobacco use. Because tobacco use is so harmful, an increase of as little as 1 percentage point in long-term quit success rates can have an important public health impact.

Tobacco use and quit behaviour assessment in the Global Adult Tobacco Survey (GATS): invalid responses and implications.

Background: Tobacco use and quit attempts are two key indicators of the Global Adult Tobacco Survey (GATS) that assess quit attempts among current as well as former tobacco users. The relevant data have inherent policy implications for tobacco cessation programme evaluation. This study aimed to review the concepts of quit attempt assessment and quantifying invalid responses considering GATS-India data.

A folding transition underlies the emergence of membrane affinity in amyloid-β.

Small amyloid-β (Aβ) oligomers have much higher membrane affinity compared to the monomers, but the structural origin of this functional change is not understood. We show that as monomers assemble into small n-mers (n < 10), Aβ acquires a tertiary fold that is consistent with the mature fibrils. This is an early and defining transition for the aggregating peptide, and possibly underpins its altered bioactivity.

A Highly Selective Reaction-Based Two-Photon Probe for Copper(I) in Aqueous Media.

Out of the blue: A reaction-based two-photon probe XanCu is reported for the selective detection of Cu in reducing aqueous environments. Copper(I)-mediated oxidative benzylic ether (CO) bond cleavage offers "switch-on" detection of the metal ion.