SARS-CoV-2 Omicron Variant Binds to Human Cells More Strongly than the Wild Type: Evidence from Molecular Dynamics Simulation

The emergence of the variant of concern Omicron (B.1.1.529) of the severe acute respiratory syndrome coronavirus 2 has aggravated the Covid-19 pandemic due to its very contagious ability. The high infection rate may be due to the high binding affinity of Omicron to human cells, but both experimental and computational studies have yielded conflicting results on this issue. Some studies have shown that the Omicron variant binds to human angiotensin-converting enzyme 2 (hACE2) more strongly than the wild type (WT), but other studies have reported comparable binding affinities. To shed light on this open problem, in this work, we calculated the binding free energy of the receptor binding domain (RBD) of the WT and Omicron spike protein to hACE2 using all-atom molecular dynamics simulation and the molecular mechanics Poisson-Boltzmann surface area method. We showed that Omicron binds to human cells more strongly than the WT due to increased RBD charge, which enhances electrostatic interaction with negatively charged hACE2. N440K, T478K, E484A, Q493R, and Q498R mutations in the RBD have been found to play a critical role in the stability of the RBD-hACE2 complex. The effect of homogeneous and heterogeneous models of glycans coating the viral RBD and the peptidyl domain of hACE2 was examined. Although the total binding free energy is not sensitive to the glycan model, the distribution of per-residue interaction energies depends on it. In addition, glycans have a little effect on the binding affinity of the WT RBD to hACE2.

Molecular Dynamics Simulations of the Tau Amyloid Fibril Core Dimer at the Surface of a Lipid Bilayer Model: I. In Alzheimer's Disease

A tau R3-R4 domain spanning residues 306-378 was shown to form an amyloid fibril core of a full-length tau in the brain of patients with Alzheimer's disease. Recently, we studied the dynamics of a tau R3-R4 monomer at the surface of a lipid bilayer model and revealed deep insertion of the amino acids spanning the PHF6 motif (residues 306-311) and its flanking residues. Here, we explore the membrane-associated conformational ensemble of a tau R3-R4 dimer by means of atomistic molecular dynamics. Similar to the monomer simulation, the R3-R4 dimer has the propensity to form β-hairpin-like conformation. Unlike the monomer, the dimer shows insertion of the C-terminal R4 region and transient adsorption of the PHF6 motif. Taken together, these results reveal the multiplicity of adsorption and insertion modes of tau into membranes depending on its oligomer size.

Molecular Dynamics Simulations of the Tau R3-R4 Domain Monomer in the Bulk Solution and at the Surface of a Lipid Bilayer Model

The aggregation of the tau protein plays a significant role in Alzheimer's disease, and the tau R3-R4 domain spanning residues 306-378 was shown to form the amyloid fibril core of a full-length tau. The conformations of the tau R3-R4 monomer in the bulk solution and at the surface of membranes are unknown. In this study, we address these questions by means of atomistic molecular dynamics. The simulations in the bulk solution show a very heterogeneous ensemble of conformations with low β and helical contents. The tau R3-R4 monomer has the propensity to form transient β-hairpins within the R3 repeat and between the R3 and R4 repeats and parallel β-sheets spanning the R3 and R4 repeats. The simulations also show that the surface of the membrane does not induce β-sheet insertion and leads to an ensemble of structures very different from those in the bulk solution. They also reveal the dynamical properties of the membrane-bound state of the tau R3-R4 monomer, enabling insertion of the residues 306-318 and 376-378.

Gaps in the implementation and uptake of maternal nutrition interventions in antenatal care services in Bangladesh, Burkina Faso, Ethiopia and India

Antenatal care (ANC) is the largest health platform globally for delivering maternal nutrition interventions (MNIs) to pregnant women. Yet, large missed opportunities remain in nutrition service delivery. This paper examines how well evidence‐based MNIs were incorporated in national policies and programs in Bangladesh, Burkina Faso, Ethiopia and India. We compared the nutrition content of ANC protocols against global recommendations. We used survey data to elucidate the coverage of micronutrient supplementation, weight gain monitoring, dietary and breastfeeding counselling. We reviewed literature, formative research and program assessments to identify barriers and enabling factors of service provision and maternal nutrition practices. Nutrition information in national policies and protocols was often fragmented, incomplete and did not consistently follow global recommendations. Nationally representative data on MNIs in ANC was inadequate, except for iron and folic acid supplementation. Coverage data from subnational surveys showed similar patterns of strengths and weaknesses. MNI coverage was consistently lower than ANC coverage with the lowest coverage of weight gain monitoring and variable coverage of dietary and breastfeeding counselling. Key common factors associated with coverage were micronutrient supply disruptions; suboptimal counselling on maternal diet, weight gain, and breastfeeding; and limited or no record keeping. Adherence of women to micronutrient supplementation and dietary recommendations was low and associated with late and too few ANC contacts, poor maternal knowledge and self‐efficacy, and insufficient family and community support. Models of comprehensive nutrition protocols and health systems that deliver maternal nutrition services in ANC are urgently needed along with national data systems to track progress.

Delivering nutrition services to all pregnant women is essential for maternal and child health outcomes but remains a challenge.

Nutrition gaps in antenatal care (ANC) include lack of specificity in national guidelines and protocols, bottlenecks in micronutrient supplies, low ANC provider knowledge and skills, inadequate supervision to reinforce counseling, and not engaging families to encourage key practices.

National protocols for ANC should be more specific for the four nutrition interventions (micronutrient supplements, weight gain monitoring, counseling on diets and counseling on breastfeeding) and assign accountability for coverage and quality.

Country models are needed for improving provision and utilisation of nutrition interventions through ANC that are based on comprehensive policy frameworks.

Small Oligomers of Aβ42 Protein in the Bulk Solution with AlphaFold2

Aggregation of amyloid-β (Aβ42) protein is one hallmark of Alzheimer's disease, and the conformations of the smallest Aβ42 oligomers are largely unknown. Here, we explore the application of the deep learning AlphaFold2 method to the structure determination of Aβ42 monomers up to hexamers. The results shed light on the early Aβ42 aggregation steps in the bulk solution.

Elastic moduli of normal and cancer cell membranes revealed by molecular dynamics simulations

Recent studies indicate that there are mechanical differences between normal cells and cancer cells. Because the cell membrane takes part in a variety of vital processes, we test the hypothesis of whether or not two fundamental alterations in the cell membrane, i.e., the overexpression of phosphatidylserine lipids in the outer leaflet and a reduction in cholesterol concentration, could cause the softening in cancer cells. Adopting ten models of normal and cancer cell membranes, we carry out 1 μs all-atom molecular dynamics simulations to compare the structural properties and elasticity properties of two membrane types. We find that the overexpression of the phosphatidylserine lipids in the outer leaflet does not significantly alter the area per lipid, the membrane thickness, the lipid order parameters and the elasticity moduli of the cancer membranes. However, a reduction in the cholesterol concentration leads to clear changes in those quantities, especially decreases in the bending, tilt and twist moduli. This implies that the reduction of cholesterol concentration in the cancer membranes could contribute to the softening of cancer cells.

Effect of Cholesterol Molecules on Aβ1-42 Wild-Type and Mutants Trimers

Alzheimer’s disease displays aggregates of the amyloid-beta (Aβ) peptide in the brain, and there is increasing evidence that cholesterol may contribute to the pathogenesis of the disease. Though many experimental and theoretical studies have focused on the interactions of Aβ oligomers with membrane models containing cholesterol, an understanding of the effect of free cholesterol on small Aβ42 oligomers is not fully established. To address this question, we report on replica exchange with a solute tempering simulation of an Aβ42 trimer with cholesterol and compare it with a previous replica exchange molecular dynamics simulation. We show that the binding hot spots of cholesterol are rather complex, involving hydrophobic residues L17–F20 and L30–M35 with a non-negligible contribution of loop residues D22–K28 and N-terminus residues. We also examine the effects of cholesterol on the trimers of the disease-causing A21G and disease-protective A2T mutations by molecular dynamics simulations. We show that these two mutations moderately impact cholesterol-binding modes. In our REST2 simulations, we find that cholesterol is rarely inserted into aggregates but rather attached as dimers and trimers at the surface of Aβ42 oligomers. We propose that cholesterol acts as a glue to speed up the formation of larger aggregates; this provides a mechanistic link between cholesterol and Alzheimer’s disease.

Changes in anemia and anthropometry during adolescence predict learning outcomes: findings from a 3-year longitudinal study in India

BACKGROUND

Anemia and poor physical growth during adolescence have far-ranging consequences, but limited longitudinal evidence exists on how changes in these factors relate to changes in learning skills as adolescents mature.

OBJECTIVES

We examined the association between changes in anemia and physical growth during adolescence and learning outcomes.

METHODS

We used longitudinal data from the Understanding the Lives of Adolescents and Young Adults (UDAYA) project, which surveyed adolescents aged 10-19 y in northern India in 2015-2016 and 2018-2019 (n = 5963). We used multilevel mixed-effects logistic regression models to examine associations between changes in anemia/thinness/stunting status (4 groups: never, improved, new, and persistent) and reading (ability to read a story) and math proficiency (ability to solve division problems) at follow-up.

RESULTS

Persistent anemia and stunting were higher among girls than among boys (46% compared with 8% and 37% compared with 14%, respectively), but persistent thinness was lower (7% compared with 16%). Improvement in anemia, thinness, and stunting was 1.4-1.7 times higher among boys than among girls. Boys who were anemic in both waves were 74% [adjusted odds ratio (AOR): 0.26; 95% CI: 0.12, 0.59] and 65% (AOR: 0.35; 95% CI: 0.16, 0.76) less likely to be able to read a story and solve division problems, respectively, than boys who were nonanemic in both waves. Persistent thinness in boys was negatively associated with both reading (AOR: 0.37; 95% CI: 0.21, 0.66) and math proficiency (AOR: 0.27; 95% CI: 0.16, 0.46). Persistent stunting contributed to lower reading and math proficiency in boys and girls (AORs: 0.29-0.46). Boys whose anemia or thinness status improved and girls whose stunting status improved had similar learning skills at follow-up as those who were never anemic/thin/stunted.

CONCLUSIONS

Persistent anemia, thinness, and short stature during adolescence were associated with poor learning. Programs targeted at adolescents should contribute to nurturing environments that foster healthy growth and learning.

Computer Simulations Aimed at Exploring Protein Aggregation and Dissociation

Protein aggregation can lead to well-defined structures that are functional, but is also the cause of the death of neuron cells in many neurodegenerative diseases. The complexity of the molecular events involved in the aggregation kinetics of amyloid proteins and the transient and heterogeneous characters of all oligomers prevent high-resolution structural experiments. As a result, computer simulations have been used to determine the atomic structures of amyloid proteins at different association stages as well as to understand fibril dissociation. In this chapter, we first review the current computer simulation methods used for aggregation with some atomistic and coarse-grained results aimed at better characterizing the early formed oligomers and amyloid fibril formation. Then we present the applications of non-equilibrium molecular dynamics simulations to comprehend the dissociation of protein assemblies.

Specificity Matters: Unpacking Impact Pathways of Individual Interventions within Bundled Packages Helps Interpret the Limited Impacts of a Maternal Nutrition Intervention in India

BACKGROUND

To address gaps in coverage and quality of nutrition services, Alive & Thrive (A&T) strengthened the delivery of maternal nutrition interventions through government antenatal care (ANC) services in Uttar Pradesh, India. The impact evaluation of the A&T interventions compared intensive ANC (I-ANC) with standard ANC (S-ANC) areas and found modest impacts on micronutrient supplementation, dietary diversity, and weight-gain monitoring.

OBJECTIVES

This study examined intervention-specific program impact pathways (PIPs) and identified reasons for limited impacts of the A&T maternal nutrition intervention package.

METHODS

We used mixed methods: frontline worker (FLW) surveys (n = ∼500), counseling observations (n = 407), and qualitative in-depth interviews with FLWs, supervisors, and block-level staff (n = 59). We assessed 7 PIP domains: training and materials, knowledge, supportive supervision, supply chains, data use, service delivery, and counseling.

RESULTS

Exposure to training improved in both I-ANC and S-ANC areas with more job aids used in I-ANC compared with S-ANC (90% compared with 70%), but gaps remained for training content and refresher trainings. FLWs' knowledge improvement was higher in I-ANC than S-ANC (22-36 percentage points), but knowledge of micronutrient supplement benefits and recommended foods was insufficient (<50%). Most FLWs received supervision (>90%), but supportive supervision was limited by staff vacancies and competing work priorities. Supplies of iron-folic acid and calcium supplements were low in both areas (30-50% stock-outs). Use of monitoring data during review meetings was higher in I-ANC than S-ANC (52% compared with 36%) but was constrained by time, understanding, and data quality. Service provision improved in both I-ANC and S-ANC areas, but counseling on supplement benefits and weight-gain monitoring was low (30-40%).

CONCLUSIONS

Systems-strengthening efforts improved maternal nutrition interventions in ANC, but gaps remained. Taking an intervention-specific perspective to the PIP analysis in this package of services was critical to understand how common and specific barriers influenced overall program impact.

Findings from a tandem clinician leadership intervention for emergency department cardiac arrest care during the COVID-19 pandemic

Introduction

Cardiopulmonary arrest (CPA) care in the Emergency Department (ED) has had to be modified during the coronavirus disease (COVID-19) pandemic. Scarce literature exists on comfort of clinicians (defined as physicians, nurses & advanced practice providers-APP's) in these new roles and their perceived understanding of new algorithms.

Methods

Routine CPA care in our ED was modified during the COVID-19 pandemic. This involved clinicians in shared leadership roles alongside COVID-19 specific changes to CPA algorithms. The new protocol was operationalized through a two-step educational intervention involving didactic education and in-situ simulations. Univariate analyses using student's t-test assessed effectiveness of this educational intervention with clinician comfort as team leaders and perceived knowledge as primary outcomes on a scale of 1 (strongly disagree) to 5 (strongly agree). Subgroup analysis across physicians (attending & resident), nurses & APP's were also undertaken with an alpha of 0.05, and p values <0.05 were considered statistically significant. Secondary outcomes of task saturation, procedural safety and error prevention were also analyzed.

Results

Across 83 of 95 total participants, our primary outcome of clinician comfort in the team leader role improved from a mean value of 3.41 (SD: 1.23) pre-intervention to 4.11 (SD: 0.88) with a p-value <0.001 post intervention. Similar and statistically significant findings in clinician comfort were noted across all subgroups except attending physicians and APP's. Perceived knowledge increased from a mean value of 3.54 (SD: 1.06) pre-intervention to a mean value of 4.24 (SD: 0.67) with a p-value <0.001 post intervention. Similar and statistically significant findings in perceived knowledge were noted across all subgroups except APP's. Responses were registered in either the strongly agree or agree category with regards to task saturation (89%), procedural safety (93%) and error prevention (71%) across all clinicians post intervention.

Conclusion

Our pilot investigation of the effectiveness of an educational intervention of a novel CPA protocol in the ED during the COVID-19 pandemic reached statistical significance with regards to clinician comfort in shared leadership roles and perceived knowledge. These findings suggest that the protocol is rapidly teachable, usable and can be efficiently disseminated across ED clinicians of varying experience, especially in pandemic settings. Further work regarding effectiveness of this new protocol in real life cardiac arrest scenarios is warranted.

COVID-19 Disrupted Provision and Utilization of Health and Nutrition Services in Uttar Pradesh, India: Insights from Service Providers, Household Phone Surveys, and Administrative Data

BACKGROUND

The coronavirus (COVID-19) pandemic may substantially affect health systems, but little primary evidence is available on disruption of health and nutrition services.

OBJECTIVES

This study aimed to 1) determine the extent of disruption in provision and utilization of health and nutrition services induced by the pandemic in Uttar Pradesh, India; and 2) identify how adaptations were made to restore service provision in response to the pandemic.

METHODS

We conducted longitudinal surveys with frontline workers (FLWs, n = 313) and mothers of children <2 y old (n = 659) in December 2019 (in-person) and July 2020 (by phone). We also interviewed block-level managers and obtained administrative data. We examined changes in service provision and utilization using Wilcoxon matched-pairs signed-rank tests.

RESULTS

Compared with prepandemic, service provision reduced substantially during lockdown (83-98 percentage points, pp), except for home visits and take-home rations (∼30%). Most FLWs (68%-90%) restored service provision in July 2020, except for immunization and hot cooked meals (<10%). Administrative data showed similar patterns of disruption and restoration. FLW fears, increased workload, inadequate personal protective equipment (PPE), and manpower shortages challenged service provision. Key adaptations made to provide services were delivering services to beneficiary homes (∼40%-90%), social distancing (80%), and using PPE (40%-50%) and telephones for communication (∼20%). On the demand side, service utilization reduced substantially (40-80 pp) during the lockdown, but about half of mothers received home visits and food supplementation. Utilization for most services did not improve after the lockdown, bearing the challenges of limited travel (30%), nonavailability of services (26%), and fear of catching the virus when leaving the house (22%) or meeting service providers (14%).

CONCLUSIONS

COVID-19 disrupted the provision and use of health and nutrition services in Uttar Pradesh, India, despite adaptations to restore services. Strengthening logistical support, capacity enhancement, performance management, and demand creation are needed to improve service provision and utilization during and post-COVID-19.

Molecular Mechanism of Ultrasound-Induced Structural Defects in Liposomes: A Nonequilibrium Molecular Dynamics Simulation Study

The use of ultrasound in combination with liposomes is a promising approach to improve drug delivery. To achieve an optimal drug release rate, it is important to understand how ultrasound induces pathways on the liposome surface where drugs can be released from the liposome. To this end, we carry out large-scale ultrasound-induced molecular dynamics simulations for three single lipid component liposomes formed from the commonly used phospholipids: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dipalmitoylphosphatidylcholine (DPPC), or phosphatidylcholine (POPC). The results show that ultrasound induces the detachment of two leaflets of the DOPC surface, suggesting that the drug release pathway may be through the low lipid packing areas on the stretched surface. In contrast, ultrasound induces pore formation on the surface of DPPC and DOPC, where drugs could escape from the liposomes. While the leaflet detachment and transient pore formation are the mechanisms of DOPC and DPPC, respectively, in both liquid-ordered and liquid-disordered phases, the leaflet detachment mechanism is switched to the transient pore formation mechanism on going from the liquid-ordered phase to the liquid-disordered phase in the POPC liposome. By adding 30% mol cholesterol, the leaflet detachment mechanism is observed in all liposomes. We found that the molecular origin that determines a mechanism is the competition between the intraleaflet and interleaflet interacting energy of lipids. The connection to experimental and theoretical modeling is discussed in some detail.

The role of the state government, civil society and programmes across sectors in stunting reduction in Chhattisgarh, India, 2006-2016

Introduction

Childhood stunting has declined in India between 2006 and 2016, but not uniformly across all states. Little is known about what helped some states accelerate progress while others did not. Insights on subnational drivers of progress are useful not just for India but for other decentralised policy contexts. Thus, we aimed to identify the factors that contributed to declines in childhood stunting (from 52.9% to 37.6%) between 2006 and 2016 in the state of Chhattisgarh, a subnational success story in stunting reduction in India.

Methods

We examined time trends in determinants of stunting using descriptive and regression decomposition analysis of National Family Health Survey data from 2005 to 2006 and 2015–2016. We reviewed nutrition-relevant policies and programmes associated with the drivers of change to construct a policy timeline. Finally, we interviewed multiple stakeholders in the state to understand the changes in the drivers of undernutrition.

Results

The regression decomposition analysis shows that multiple factors explain 66% of the change in stunting between 2006 and 2016. Improvements in three key drivers—health and nutrition services, household assets, and sanitation and hygiene—explained 47% of the change in stunting. A shared vision for impact, political stability and capable bureaucracy, state-level innovations, support from development partners and civil society, and community mobilisation were found to contribute to improvements in programmes for health, poverty and sanitation.

Conclusion

Change in multiple sectors is important for stunting reduction and can be achieved in subnational contexts. More work lies ahead to close gaps in various determinants of stunting.

Understanding Implementation and Improving Nutrition Interventions: Barriers and Facilitators of Using Data Strategically to Inform the Implementation of Maternal Nutrition in Uttar Pradesh, India

BACKGROUND

In response to the high levels of maternal nutrition in Uttar Pradesh, Alive & Thrive (A&T) aimed to strengthen the delivery of nutrition interventions through the government antenatal care platform, including leveraging ongoing data collection to improve program delivery and reach (registered at clinicaltrials.gov as NCT03378141). However, we have a limited understanding of providers' experiences and challenges in collecting and using data for decision making.

OBJECTIVE

The aim was to identify barriers and facilitators to the 1) collection of data and 2) use of data for decision making.

METHODS

In-depth interviews (n = 35) were conducted among block-level government staff, frontline worker (FLW) supervisors, and A&T staff in 2 districts in Uttar Pradesh. Systematic coding of verbatim transcripts and detailed summaries were undertaken to elucidate themes related to data collection and use. FLW supervisors (n = 103) were surveyed to assess data use experiences.

RESULTS

Data were used to understand the reach of maternal nutrition services, estimate the demand for supplements, and guide identification of areas of low FLW performance. About half of supervisors reported using data to identify areas of improvement; however, only 23% reported using data to inform decision making. Facilitators of data collection and use included collaboration between health department officials, perceived importance of block ranking, and monthly review meetings with staff and supervisors to review and discuss data. Barriers to data collection and use included human resource gaps, inadequate technology infrastructure, FLW educational level, political structure, and lack of cooperation between FLWs and supervisors.

CONCLUSIONS

The use of data for decision making is critical for supporting intervention planning and providing targeted supervision and support for FLWs. Despite intensive data-collection efforts, the use of data to inform decision making remains limited. Collaboration facilitated data collection and use, but structural barriers such as staff vacancies need to be addressed to improve the implementation of maternal nutrition interventions.

Strengthening Nutrition Interventions in Antenatal Care Services Affects Dietary Intake, Micronutrient Intake, Gestational Weight Gain, and Breastfeeding in Uttar Pradesh, India: Results of a Cluster-Randomized Program Evaluation

BACKGROUND

Maternal nutrition interventions are inadequately integrated into antenatal care (ANC). Alive & Thrive aimed to strengthen delivery of micronutrient supplements and intensify interpersonal counseling and community mobilization through government ANC services.

OBJECTIVES

We compared nutrition-intensified ANC (I-ANC) with standard ANC (S-ANC) on coverage of nutrition interventions and maternal nutrition practices.

METHODS

We used a cluster-randomized design with cross-sectional baseline (2017) and endline (2019) surveys (n ∼660 pregnant and 1800 recently delivered women per survey) and a repeated-measures longitudinal study in 2018-2019 (n = 400). We derived difference-in-difference effect estimates (DIDs) for diet diversity, consumption of micronutrient supplements, weight monitoring, and early breastfeeding practices.

RESULTS

Despite substantial secular improvements in service coverage from India's national nutrition program, women in the I-ANC arm received more home visits [DID: 7-14 percentage points (pp)] and counseling on core nutrition messages (DID: 10-23 pp) than in the S-ANC arm. One-third of women got ≥3 home visits and one-fourth received ≥4 ANC check-ups in the I-ANC arm. Improvements were greater in the I-ANC arm than in the S-ANC arm for any receipt and consumption of iron-folic acid (DID: 7.5 pp and 9.5 pp, respectively) and calcium supplements (DID: 14.1 pp and 11.5 pp, respectively). Exclusive breastfeeding improved (DID: 7.5 pp) but early initiation of breastfeeding did not. Maternal food group consumption (∼4 food groups) and probability of adequacy of micronutrients (∼20%) remained low in both arms. Repeated-measures longitudinal analyses showed similar results, with additional impact on consumption of vitamin A-rich foods (10 pp, 11 g/d), other vegetables and fruits (22-29 g/d), and gestational weight gain (0.4 kg).

CONCLUSIONS

Intensifying nutrition in government ANC services improved maternal nutrition practices even with strong secular trends in service coverage. Dietary diversity, supplement consumption, and breastfeeding practices remained suboptimal. Achieving greater behavior changes will require strengthening the delivery and use of maternal nutrition services integrated into ANC services in the health system. This trial was registered at clinicaltrials.gov as NCT03378141.

Preconception micronutrient supplementation positively affects child intellectual functioning at 6 y of age: A randomized controlled trial in Vietnam

BACKGROUND

Although there is growing evidence on the role of preconception nutrition for birth outcomes, very few studies have evaluated the long-term effects of nutrition interventions during the preconception period on offspring cognitive outcomes.

OBJECTIVE

We evaluate the impact of preconception weekly multiple micronutrients (MMs) or iron and folic acid (IFA) supplementation compared with folic acid (FA) alone on offspring intellectual functioning at age 6-7 y.

METHODS

We followed 1599 offspring born to women who participated in a double-blinded randomized controlled trial of preconception supplementation in Vietnam. Women received weekly supplements containing either 2800 μg FA only, 60 mg iron and 2800 μg FA, or MMs (15 micronutrients including IFA) from baseline until conception, followed by daily prenatal IFA supplements until delivery. We used the Wechsler Intelligence Scale for Children to measure full-scale IQ (FSIQ) and 4 related domains of intellectual functioning [Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), and Processing Speed Index (PSI) scores] at 6-7 y. Group comparisons were done using ANOVA tests for all children and the subgroup born to women who consumed the supplements ≥26 wk before conception (per-protocol analyses).

RESULTS

The final sample with data at 6-7 y (n = 1321) was similar for baseline maternal and offspring birth characteristics and age at follow-up by treatment group. Compared with the offspring in the FA group, those in the MM group had higher FSIQ (β = 1.7; 95% CI: 0.1, 3.3), WMI (β = 1.7; 95% CI: 0.2, 3.2), and PSI (β = 2.5; 95% CI: 0.9, 4.1). Similar findings were observed in the per-protocol analyses. There were no significant differences by treatment group for VCI and PRI.

CONCLUSIONS

Preconception supplementation with MMs improved certain domains of intellectual functioning at age 6-7 y compared with FA. These findings suggest the potential for preconception micronutrient interventions to have long-term benefits for offspring cognition.

Impact of the Rat R5G, Y10F, and H13R Mutations on Tetrameric Aβ42 β-Barrel in a Lipid Bilayer Membrane Model

Three amino acid substitutions distinguish rat and human Aβ42 peptides and contribute to the difference in toxicity properties. Indeed, aged rodents rarely develop the characteristic lesions of Alzheimer's disease in contrast to humans. Both peptides form, however, amyloid fibrils in buffer solution, but their affinities to the membrane vary. In particular, there is experimental evidence that the rat Aβ42 peptide does not induce Ca²⁺ fluxes in cells. We recently designed a tetrameric β-barrel structure and showed that this model is severely destabilized for Aβ40 human compared to its Aβ42 human counterpart, explaining the absence of ionic currents of Aβ40 in planar lipid bilayers. In this study, we asked whether our model is destabilized for the rat Aβ42 peptide by using extensive replica exchange molecular dynamics simulation in a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer membrane. Our results show that the much lower propensity of aged rodents to develop Alzheimer's disease symptoms might be correlated to its tetrameric β-barrel stability in the cell membrane.

Molecular mechanism of ultrasound interaction with a blood brain barrier model

The brain is strictly protected by the blood brain barrier preventing the crossing of therapeutics to treat brain diseases. The high and low intensity focused ultrasound methods have been used to temporarily open the blood brain barrier, facilitating the transport of drugs. The methods are very promising because the opening is transient, localized, and noninvasive. However, the molecular mechanism of the opening is unknown, and this limits the development and application of these methods. With this in mind, we carry out a molecular dynamics simulation study to understand the interaction of ultrasound with the cell membrane and the tight junction. Our minimal blood brain barrier model is composed of two lipid bilayers, mimicking two portions of neighboring cells, connected together by a tight junction formed by a pair of two cis-dimers of the claudin-5 protein. Using an experimental ultrasound frequency of 50 MHz, simulations show that at low intensities, ultrasound does not impact the structure of the cell membranes and tight junction, implying that the direct interaction of ultrasound with the blood brain barrier is not responsible for the experimentally observed opening. At high intensities, the ultrasound pulls the monolayers of individual cell membrane lipid bilayers apart, creating air compartments inside the bilayers. This reduces the free energy barrier for the translocation of drugs across the lipid bilayer and enhances drug permeability. At very high intensities, the two monolayers are largely separated, resulting in cell damage and implying that the blood brain barrier is primarily opened at the experimentally observed damaged areas.

Cholesterol Molecules Alter the Energy Landscape of Small Aβ1-42 Oligomers

Small amyloid-β (Aβ) oligomers are believed to be key pathogenic species in Alzheimer's disease (AD). One suggested toxicity mechanism is the detergent model where oligomers remove lipid molecules from the bilayer. Senile plaques of AD patients also accumulate a 1:1 ratio of cholesterol/Aβ. What are the dominant structures of small Aβ42 oligomers with cholesterol molecules in aqueous solution? Here, we answer this question by performing atomistic replica exchange molecular dynamics simulations of Aβ42 dimers and trimers. Our simulations demonstrate that the interactions with cholesterol molecules change completely the energy landscape of small Aβ42 oligomers. This result shows that simulations in the bulk solution cannot recapitulate aggregation in the brain extracellular space.

Amyloid Oligomers: A Joint Experimental/Computational Perspective on Alzheimer's Disease, Parkinson's Disease, Type II Diabetes, and Amyotrophic Lateral Sclerosis

Protein misfolding and aggregation is observed in many amyloidogenic diseases affecting either the central nervous system or a variety of peripheral tissues. Structural and dynamic characterization of all species along the pathways from monomers to fibrils is challenging by experimental and computational means because they involve intrinsically disordered proteins in most diseases. Yet understanding how amyloid species become toxic is the challenge in developing a treatment for these diseases. Here we review what computer, in vitro, in vivo, and pharmacological experiments tell us about the accumulation and deposition of the oligomers of the (Aβ, tau), α-synuclein, IAPP, and superoxide dismutase 1 proteins, which have been the mainstream concept underlying Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes (T2D), and amyotrophic lateral sclerosis (ALS) research, respectively, for many years.

Nonequilibrium molecular dynamics simulations of infrared laser-induced dissociation of a tetrameric Aβ42 β-barrel in a neuronal membrane model

Experimental studies have reported that the amyloid-β proteins can form pores in cell membranes, and this could be one possible source of toxicity in Alzheimer's disease. Dissociation of these pores could therefore be a potential therapeutic approach. It is known that high photon density free-electron laser experiments and laser-induced nonequilibrium molecular dynamics simulations (NEMD) can dissociate amyloid fibrils at specific frequencies in vitro. Our question is whether NEMD simulations can dissociate amyloid pores in a bilayer mimicking a neuronal membrane, and as an example, we select a tetrameric Aβ42 β-barrel. Our simulations shows that the resonance between the laser field and the amide I vibrational mode of the barrel destabilises all intramolecular and intermolecular hydrogen bonds of Aβ42 and converts the β-barrel to a random/coil disordered oligomer. Starting from this disordered oligomer, extensive standard MD simulations shows sampling of disordered Aβ42 states without any increase of β-sheet and reports that the orientational order of lipids is minimally disturbed. Interestingly, the frequency to be employed to dissociate this beta-barrel is specific to the amino acid sequence. Taken together with our previous simulation results, this study indicates that infrared laser irradiation can dissociate amyloid fibrils and oligomers in bulk solution and in a membrane environment without affecting the surrounding molecules, offering therefore a promising way to retard the progression of AD.

Features of the Energy Spectrum of Cosmic Rays above 2.5×10^{18} eV Using the Pierre Auger Observatory

We report a measurement of the energy spectrum of cosmic rays above 2.5×10^{18}  eV based on 215 030 events. New results are presented: at about 1.3×10^{19}  eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×10^{19}  eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×10^{18}  eV is [5.66±0.03(stat)±1.40(syst)]×10^{53}  erg Mpc^{-3}.

Nutrient Adequacy Is Low among Both Self-Declared Lacto-Vegetarian and Non-Vegetarian Pregnant Women in Uttar Pradesh

Poor dietary intake during pregnancy remains a significant public health concern, affecting the health of the mother and fetus. This study examines the adequacy of energy, macronutrient, and micronutrient intakes among self-declared lacto-vegetarian and non-vegetarian pregnant women. We analyzed dietary data from 627 pregnant women in Uttar Pradesh, India, using a multiple-pass 24 h diet recall. Compared to non-vegetarians, lacto-vegetarians (~46%) were less likely to report excessive carbohydrate (78% vs. 63%) and inadequate fat intakes (70% vs. 52%). In unadjusted analyses, lacto-vegetarians had a slightly higher mean PA for micronutrients (20% vs. 17%), but these differences were no longer significant after controlling for caste, education, and other demographic characteristics. In both groups, the median intake of 9 out of 11 micronutrients was below the Estimated Average Requirement. In conclusion, the energy and micronutrient intakes were inadequate, and the macronutrient intakes were imbalanced, regardless of stated dietary preferences. Since diets are poor across the board, a range of policies and interventions that address the household food environment, nutrition counseling, behavior change, and supplementation are needed in order to achieve adequate nutrient intake for pregnant women in this population.

Infrared Laser-Induced Amyloid Fibril Dissociation: A Joint Experimental/Theoretical Study on the GNNQQNY Peptide

Neurodegenerative diseases are usually characterized by plaques made of well-ordered aggregates of distinct amyloid proteins. Dissociating these very stable amyloid plaques is a critical clinical issue. In this study, we present a joint mid-infrared free electron laser experiment/nonequilibrium molecular dynamics simulation to understand the dissociation process of a representative example GNNQQNY fibril. By tuning the laser frequency to the amide I band of the fibril, the resonance takes place and dissociation is occurred. With the calculated and observed wide-angle X-ray scattering profiles and secondary structures before and after laser irradiation being identical, we can propose a dissociation mechanism with high confidence from our simulations. We find that dissociation starts in the core of the fibrils by fragmenting the intermolecular hydrogen bonds and separating the peptides and then propagates to the fibril extremities leading to the formation of unstructured expanded oligomers. We suggest that this should be a generic mechanism of the laser-induced dissociation of amyloid fibrils.