Link updating strategies influence consensus decisions as a function of the direction of communication.

Consensus decision-making in social groups strongly depends on communication links that determine to whom individuals send, and from whom they receive, information. Here, we ask how consensus decisions are affected by strategic updating of links and how this effect varies with the direction of communication. We quantified the coevolution of link and opinion dynamics in a large population with binary opinions using mean-field numerical simulations of two voter-like models of opinion dynamics: an incoming model (IM) (where individuals choose who to receive opinions from) and an outgoing model (OM) (where individuals choose who to send opinions to). We show that individuals can bias group-level outcomes in their favour by breaking disagreeing links while receiving opinions (IM) and retaining disagreeing links while sending opinions (OM). Importantly, these biases can help the population avoid stalemates and achieve consensus. However, the role of disagreement avoidance is diluted in the presence of strong preferences-highly stubborn individuals can shape decisions to favour their preferences, giving rise to non-consensus outcomes. We conclude that collectively changing communication structures can bias consensus decisions, as a function of the strength of preferences and the direction of communication.

Lifetime of actin-dependent protein nanoclusters.

Protein nanoclusters (PNCs) are dynamic collections of a few proteins that spatially organize in nanometer-length clusters. PNCs are one of the principal forms of spatial organization of membrane proteins, and they have been shown or hypothesized to be important in various cellular processes, including cell signaling. PNCs show remarkable diversity in size, shape, and lifetime. In particular, the lifetime of PNCs can vary over a wide range of timescales. The diversity in size and shape can be explained by the interaction of the clustering proteins with the actin cytoskeleton or the lipid membrane, but very little is known about the processes that determine the lifetime of the nanoclusters. In this paper, using mathematical modeling of the cluster dynamics, we model the biophysical processes that determine the lifetime of actin-dependent PNCs. In particular, we investigated the role of actin aster fragmentation, which had been suggested to be a key determinant of the PNC lifetime, and we found that it is important only for a small class of PNCs. A simple extension of our model allowed us to investigate the kinetics of protein-ligand interaction near PNCs. We found an anomalous increase in the lifetime of ligands near PNCs, which agrees remarkably well with experimental data on RAS-RAF kinetics. In particular, analysis of the RAS-RAF data through our model provides falsifiable predictions and novel hypotheses that will not only shed light on the role of RAS-RAF kinetics in various cancers, but also will be useful in studying membrane protein clustering in general.

Genetic aetiology of Down syndrome birth: novel variants of maternal DNMT3B and RFC1 genes increase risk of meiosis II nondisjunction in the oocyte.

The aim of the present work was to explore the intriguing association of maternal folate regulator gene polymorphisms and mutations with the incidence of chromosome 21 nondisjunction and Down syndrome birth. We tested polymorphisms/mutations of DNMT3B and RFC1 genes for their association with meiotic errors in oocyte among the 1215 Down syndrome child-bearing women and 900 controls. We observed that 23 out of 31 variants of DNMT3B and RFC1 exhibited an association with meiosis II nondisjunction in maternal age-independent manner. Additionally, we have reported 17 novel mutations and 1 novel polymorphic variant that are unique to the Indian Bengali speaking cohort and increased odds in favour of meiosis II nondisjunction. We hypothesize that the risk variants and mutations of DNMT3B and RFC1 genes may cause reduction in two or more recombination events and also cause peri-centromeric single exchange that increases the risk of nondisjunction at any age of women. In silico analyses predicted the probable damages of the transcripts or proteins from the respective genes owing to the said polymorphisms. These findings from the largest population sample tested ever revealed that mutations/polymorphisms of the genes DNMT3B and RFC1 impair recombination that leads to chromosome 21 nondisjunction in the oocyte at meiosis II stage and bring us a significant step closer towards understanding the aetiology of chromosome 21 nondisjunction and birth of a child with Down syndrome to women at any age.

Machine learning-driven multiscale modeling reveals lipid-dependent dynamics of RAS signaling proteins.

RAS is a signaling protein associated with the cell membrane that is mutated in up to 30% of human cancers. RAS signaling has been proposed to be regulated by dynamic heterogeneity of the cell membrane. Investigating such a mechanism requires near-atomistic detail at macroscopic temporal and spatial scales, which is not possible with conventional computational or experimental techniques. We demonstrate here a multiscale simulation infrastructure that uses machine learning to create a scale-bridging ensemble of over 100,000 simulations of active wild-type KRAS on a complex, asymmetric membrane. Initialized and validated with experimental data (including a new structure of active wild-type KRAS), these simulations represent a substantial advance in the ability to characterize RAS-membrane biology. We report distinctive patterns of local lipid composition that correlate with interfacially promiscuous RAS multimerization. These lipid fingerprints are coupled to RAS dynamics, predicted to influence effector binding, and therefore may be a mechanism for regulating cell signaling cascades.

Evaluation of vitamin D profile in juvenile idiopathic arthritis.

OBJECTIVE: To observe the association between serum vitamin D level and disease activity in juvenile idiopathic arthritis (JIA). METHODS: The observational study was conducted at a tertiary care hospital during 2017-2019. Patients suffered from JIA were recruited through purposive sampling which was stratified by the disease activity based on the Juvenile Arthritis Disease Activity Score 27 (JADAS27) criteria. Serum vitamin D was estimated alongside other laboratory parameters. The numerical and categorical variables were analysed with appropriate statistical tests. RESULTS: 40 subjects were studied where inactive disease was observed in nine subjects (22.5%), five subjects (12.5%) were found to be in low disease activity and moderate disease activity groups each, and twenty-one subjects (52.5%) had high disease activity. Considering the total sample size of the study, the mean (SD) JADAS27 score and serum vitamin D level were observed to be 12.02 (11.31) and 23.10 (5.93) respectively. A negative correlation was found between the JADAS27 score and serum vitamin D (r= -0.67). The corrected Chi-square test had revealed significant association between the status of serum vitamin-D and disease activity groups (=16.28; p < .001). CONCLUSIONS: In JIA, higher grade of disease activity was found to be significantly associated with lower serum vitamin D.

Understanding etiology of chromosome 21 nondisjunction from gene × environment models.

Maternal risk factors and their interactions with each other that associate chromosome 21 nondisjunction are intriguing and need incisive study to be resolved. We determined recombination profile of nondisjoined chromosome 21 and maternal genotypes for four selected polymorphic variants from the folate regulators genes stratifying the women according to the origin of segregation error and age at conception. We conducted association study for genotype and maternal addiction to smokeless chewing tobacco, usually chopped tobacco leaves or paste of tobacco leaves with the incidence of Down syndrome birth. Additionally, we designed various logistic regression models to explore the effects of maternal genotype, maternal habit of smokeless chewing tobacco, maternal age at conception and all possible interactions among them on chromosome 21 nondisjunction. We found folate regulator gene mutations are associated with maternal meiosis II error. Regression models revealed smokeless chewing tobacco and folate polymorphic/mutant risk genotype interact with each other to increase the risk of reduced and single peri-centromeric recombination events on chromosome 21 that nondisjoined at meiosis II in the oocytes and the effect is maternal age independent. We inferred maternal folate polymorphic/mutant risk genotypes and habit of smokeless chewing tobacco interact with each other and increase the risk of meiosis II error in oocytes in maternal age-independent manner.

Genetic and acquired blistering disorders of pediatric age group: An experience from Eastern India.

INTRODUCTION: Blistering or vesiculobullous disorders in pediatric population are either immunobullous or mechanobullous. Spectrum was analyzed using demographic details, clinical features, histopathology, direct immunofluorescence (DIF) and Immunofluorescence mapping (IFM). METHODOLOGY: This was a single institution based observational study in children below 18 years. The demographic details were collected using proforma containing particulars of the patient, history, complaints, and other parameters. Punch biopsy of the skin lesion was done. Biopsy samples were examined under light microscope followed by DIF using fluorescent conjugated polyclonal antibody against immunoglobulins IgG, IgM, IgA, and complement C3. The salt-split technique was also used in particular cases. IFM was done using anticytokeratin (CK) 5 & 14, antilaminin 332, anticollagen VII, and anticollagen IV antibodies. RESULTS: Out of total 50 cases, linear IgA bullous dermatosis (LABD) was the commonest. The average concordance between clinical and final diagnosis (histopathological examination + DIF) was 87.5% and discordance was 12.5%. The agreement between histopathological examination and DIF was found to be substantially significant (κ = 0.6892). IFM depicted epidermolysis bullosa simplex with reduced CK 14 expression, dystrophic epidermolysis bullosa with reduced Collagen VII expression and junctional epidermolysis bullosa with absent laminin 5 expression. CONCLUSION: The spectrum of bullous lesions in childhood was properly delineated and subcategorization of EB was done. Histopathological examination showed the hallmarks that were conclusive in most of the cases except in LABD and EB. DIF and IFM proved indispensable in those cases. Thus, DIF is not a substitute for histopathology but complementary to it.

The etiology of Down syndrome: Maternal MCM9 polymorphisms increase risk of reduced recombination and nondisjunction of chromosome 21 during meiosis I within oocyte.

Altered patterns of recombination on 21q have long been associated with the nondisjunction chromosome 21 within oocytes and the increased risk of having a child with Down syndrome. Unfortunately the genetic etiology of these altered patterns of recombination have yet to be elucidated. We for the first time genotyped the gene MCM9, a candidate gene for recombination regulation and DNA repair in mothers with or without children with Down syndrome. In our approach, we identified the location of recombination on the maternal chromosome 21 using short tandem repeat markers, then stratified our population by the origin of meiotic error and age at conception. We observed that twenty-five out of forty-one single nucleotide polymorphic sites within MCM9 exhibited an association with meiosis I error (N = 700), but not with meiosis II error (N = 125). This association was maternal age-independent. Several variants exhibited aprotective association with MI error, some were neutral. Maternal age stratified characterization of cases revealed that MCM9 risk variants were associated with an increased chance of reduced recombination on 21q within oocytes. The spatial distribution of single observed recombination events revealed no significant change in the location of recombination among women harbouring MCM9 risk, protective, or neutral variant. Additionally, we identified a total of six novel polymorphic variants and two novel alleles that were either risk imparting or protective against meiosis I nondisjunction. In silico analyses using five different programs suggest the risk variants either cause a change in protein function or may alter the splicing pattern of transcripts and disrupt the proportion of different isoforms of MCM9 products within oocytes. These observations bring us a significant step closer to understanding the molecular basis of recombination errors in chromosome 21 nondisjunction within oocytes that leads to birth of child with Down syndrome.

Immunogenicity and safety of the first indigenously developed Indian tetravalent influenza vaccine (split virion) in healthy children (6 months to 17 years of age): a randomized, multicenter, phase III clinical trial.

This phase III clinical trial was conducted to evaluate the immunogenicity and safety of the Tetravalent Influenza Vaccine (Split virion) I.P. (TetIV), containing two strains each of influenza A and B, developed indigenously in the country for the first time by M/s Cadila Healthcare Limited, India for use in the pediatric population (6 months -17 years of age), and compare it to that of a licensed seasonal Trivalent Influenza Vaccine (TriIV) of Sanofi Pasteur India Private Limited, containing two influenza A and one influenza B strains. Three hundred six subjects of either sex, 6 months to 17 years of age, were randomized in a 1:1 ratio to receive either TetIV or TriIV. Immunogenicity assessments (antibodies against A/H1N1, A/H3N2, B/Phuket, and B/Brisbane) were performed using the hemagglutination inhibition assay at baseline and 28 days after the last vaccination. TetIV was found to fulfill the criteria set by the United States Food and Drug Administration on the requirements of clinical data for licensure of seasonal inactivated influenza vaccines for the pediatric population. The seroconversion rates with TetIV were 94.6% for A/H1N1, 93.9% for A/H3N2, 91.2% for B/Brisbane, and 87.2% for B/Phuket strains. TetIV showed non-inferiority and superiority in immune response, as compared to TriIV, against the shared strains and an additional B strain, respectively. Both the vaccines were tolerated well by all the study participants, and an addition of the fourth strain in TetIV did not compromise the safety as compared to that of TriIV. The most common adverse event reported in both groups was fever.

How Anionic Lipids Affect Spatiotemporal Properties of KRAS4B on Model Membranes.

RAS proteins are small membrane-anchored GTPases that regulate key cellular signaling networks. It has been recently shown that different anionic lipid types can affect the spatiotemporal properties of RAS through dimerization/clustering and signaling fidelity. To understand the effects of anionic lipids on key spatiotemporal properties of RAS, we dissected 1 ms of data from all-atom molecular dynamics simulations for KRAS4B on two model anionic lipid membranes that have 30% of POPS mixed with neutral POPC and 8% of PIP2 mixed with POPC. We unveiled the orientation space of KRAS4B, whose kinetics were slower and more distinguishable on the membrane containing PIP2 than the membrane containing POPS. Particularly, the PIP2-mixed membrane can differentiate a third kinetic orientation state from the other two known orientation states. We observed that each orientation state may yield different binding modes with an RAF kinase, which is required for activating the MAPK/ERK signaling pathway. However, an overall occluded probability, for which RAF kinases cannot bind KRAS4B, remains unchanged on the two different membranes. We identified rare fast diffusion modes of KRAS4B that appear coupled with orientations exposed to cytosolic RAF. Particularly, on the membrane having PIP2, we found nonlinear correlations between the orientation states and the conformations of the cationic farnesylated hypervariable region, which acts as an anchor in the membrane. Using diffusion coefficients estimated from the all-atom simulations, we quantified the effect of PIP2 and POPS on the KRAS4B dimerization via Green's function reaction dynamics simulations, in which the averaged dimerization rate is 12.5% slower on PIP2-mixed membranes.

Presence or Absence of Ras Dimerization Shows Distinct Kinetic Signature in Ras-Raf Interaction.

Initiations of cell signaling pathways often occur through the formation of multiprotein complexes that form through protein-protein interactions. Therefore, detecting their presence is central to understanding the function of a cell signaling pathway, aberration of which often leads to fatal diseases, including cancers. However, the multiprotein complexes are often difficult to detect using microscopes due to their small sizes. Therefore, currently, their presence can be only detected through indirect means. In this article, we propose to investigate the presence or absence of protein complexes through some easily measurable kinetic parameters, such as activation rates. As a proof of concept, we investigate the Ras-Raf system, a well-characterized cell signaling system. It has been hypothesized that Ras dimerization is necessary to create activated Raf dimers. Although there are circumstantial evidences supporting the Ras dimerization hypothesis, direct proof of Ras dimerization is still inconclusive. In the absence of conclusive direct experimental proof, this hypothesis can only be examined through indirect evidences of Ras dimerization. In this article, using a multiscale simulation technique, we provide multiple criteria that distinguishes an activation mechanism involving Ras dimerization from another mechanism that does not involve Ras dimerization. The provided criteria will be useful in the investigation of not only Ras-Raf interaction but also other two-protein interactions.

Design of conditions for self-replication.

A "self-replicator" is usually understood to be an object of definite form that promotes the conversion of materials in its environment into a nearly identical copy of itself. The challenge of engineering novel, micro- or nanoscale self-replicators has attracted keen interest in recent years, both because exponential amplification is an attractive method for generating high yields of specific products and, also, because self-reproducing entities have the potential to be optimized or adapted through rounds of iterative selection. Substantial steps forward have been achieved both in the engineering of particular self-replicating molecules and in the characterization of the physical basis for possible mechanisms of self-replication. At present, however, there is a need for a theoretical treatment of what physical conditions are most conducive to the emergence of novel self-replicating structures from a reservoir of building blocks on a desired time scale. Here we report progress in addressing this need. By analyzing the kinetics of a toy chemical model, we demonstrate that the emergence of self-replication can be controlled by coarse, tunable features of the chemical system, such as the fraction of fast reactions and the width of the rate constant distribution. We also find that the typical mechanism is dominated by the cooperation of multiple interconnected reaction cycles as opposed to a single isolated cycle. The quantitative treatment presented here may prove useful for designing novel self-replicating chemical systems.

Clinical Profile and Therapeutic Response of Scrub Typhus in Children: A Recent Trend from Eastern India.

OBJECTIVE: The aim of this study was to assess the clinico-laboratory parameters, complications and therapeutic responses in children with scrub typhus in Eastern India. MATERIALS AND METHODS: In this prospective, observational study, all children (age, <12 years) with suspected scrub typhus with a compatible clinical scenario were enrolled consecutively over six months. Cases confirmed by means of a positive IgM serology or a positive Weil-Felix reaction (OXK = 1/80 or above) were administered enteral doxycycline (4.5 mg/kg/day). RESULTS: Out of 94 recruited children, 61 had confirmed scrub typhus (mean age = 6.1 years, M:F = 1.1:1) with or without complications and having a considerably higher incidence of neurological presentation (meningoencephalistis n = 21, 34.4%). The most frequent manifestations included vomiting (n = 39, 63.9%), abdominal pain (n = 33, 54.1%), lymphadenopathy (n = 36, 59%), hepatosplenomegaly (n = 32, 52.5%), pedal edema (n = 32, 52.5%) and eschar formation (n = 30, 49.2%). Low hemoglobin levels, leukocytosis, thrombocytopenia, hypoalbuminemia, hyponatremia, increased liver enzymes and increased C-reactive protein were associated with delayed defervescence (>48 h). CONCLUSION: Scrub meningoencephalitis, with a notably higher incidence, showed favorable therapeutic response. Prompt and empiric doxycycline therapy could be lifesaving.

Risk of Down syndrome birth: Consanguineous marriage is associated with maternal meiosis-II nondisjunction at younger age and without any detectable recombination error.

Consanguineous marriage was examined as a risk factor for Down syndrome birth. We genotyped Down syndrome family trios using short tandem repeat markers on 21q-to interpret the parental and meiotic stage of origin of errors as well as to record recombination profile along long arm of chromosome 21. We then compared nonconsanguineous (N = 811) group with-the consanguineous (N =157) marriages. We report for the first time that consanguineous marriage is associated with an increased risk for nondisjunction of chromosome 21 in oocytes-during the second meiotic division. We observed the absence of recombination more frequently in younger mothers in nonconsanguineous meiosis I cases. This was in contrast to an equal distribution of nonrecombinant cases across the age categories in the meiosis I consanguineous group. Moreover, the non-consanguineous group exhibited preferential telomeric recombination in meiosis I error among younger women and centromeric recombination in meiosis II errors in older women. In contrast, the consanguineous group exhibited medially placed recombination events in both meiosis I and meiosis II nondisjunction errors. Additionally, we recorded reduced maternal age at conception in the-consanguineous group. These findings suggest novel risk factors associated that increase the risk of chromosome 21 nondisjunction in the families with consanguinity.

Van Wyk-Grumbach syndrome with hemangioma in an infant.

Background Van Wyk-Grumbach syndrome (VWGS) is characterized by juvenile primary hypothyroidism, delayed bone age and isosexual incomplete precocious puberty with reversal to the prepubertal state following thyroid hormone replacement. Case presentation In this case, an 18-month-old girl presented with premature menarche since 9 months of age, delayed bone age and enlarged bilateral multicystic ovaries along with a superficial infantile hemangioma over the upper anterior chest. VWGS was diagnosed based on the clinical features. High serum thyroid stimulating hormone and low free thyroxine with the absence of any carpal bones in the wrist X-ray were suggestive of congenital hypothyroidism. Interestingly, the coexisting hemangioma could also play a role in the etiology of the hypothyroidism through "consumptive hypothyroidism". Thyroid hormone replacement resulted in the complete resolution of signs and symptoms. Conclusions Untreated congenital hypothyroidism of short duration, onset of symptoms in infancy and association of an infantile hemangioma in VWGS were the unique features in our case.

BCG-induced Disseminated Mycobacterial Infection of Skin and Bone in an Otherwise Immunocompetent Child.

One 2-year-old undernourished girl presented to our outpatient with large erythematous scaly plaques in arm along with multiple bony swellings over nose, fingers, left foot, and back for the past 1 year. Apart from skin and bone lesions the girl was also had intermittent fever, pallor, irritability, and malnourishment. Her parents gave a history of incomplete healing at the BCG vaccination site. The case was diagnosed to be case of disseminated mycobacterial infection skin and bone with the help of histopathology, radiological examination, and DNA polymerase chain reaction (PCR). DNA PCR from the skin lesion came positive for mycobacteria tuberculosis complex. The girl was treated with 6 months of standard antitubercular drug treatment with very good improvement not only of her cutaneous and bone changes but also of her general health and growth. We report the case because paucity of similar infection in literature and for greater recognition of potential epidemiological threat.