👤 B Novak

Generation of specific antibodies against peptides by immunization requires their covalent conjugation to protein carriers to override their inherently weak immunogenicity. The vast majority of bioconjugation approaches to achieve peptide-protein constructs rely on thiol-maleimide chemistry and capitalize on a wide array of commercial maleimide-functionalized protein carriers. Disulfide-rich peptides (DRPs) possess a rigid, constrained structure that makes them ideal for designing synthetic mimics of protein regions/domains. For bioconjugation purposes, the introduction of a single spare thiol moiety into a linear peptide antigen is straightforward, while DRPs' disulfide bonds are prone to intramolecular thiophilic attack by the reactive thiolate. This unintended reactivity competes with the desired Michael addition to the maleimide moiety, ultimately disrupting the native disulfide bridging framework. As a result, DRP's tertiary structure will be altered, affording an immunogen that is a poor mimic of the native target. Although a few studies have explored the late-stage introduction of thiol-containing cross-linkers into DRP antigens for their conjugation onto protein carriers, the stability of DRPs' disulfide pattern in the presence of an extra thiol has never been examined. In this study, we systematically evaluated the influence of different spacers in "DRP-spacer-thiol" constructs under thiol-maleimide reaction conditions. Our results highlight how both linker length and flexibility are key to maintaining DRP disulfides unaltered, providing a general approach to achieve DRP bioconjugation by thiol-maleimide chemistry. We have applied our approach to a small DRP predicted to closely mimic a surface-accessible epitope of the full LINGO-1 protein and obtained a very specific antibody response upon immunization; the resulting polyclonal IgG was able to selectively bind the full-length protein in a cellular context, with stringent selectivity across its four homologs. Show less

This study employs latent profile analysis (LPA) to identify distinct profiles of positive youth development (PYD) based on the 5C model (connection, competence, confidence, character, and caring). While extensive research has established associations between PYD indicators and adolescent mental health, well-being, and behavioral outcomes, a person-centered approach allows for a deeper exploration of how different patterns of PYD characteristics are related to these distal outcomes. Unlike previous studies, this research uses 15 PYD indicators, capturing all subdimensions of each of the four Cs, with caring treated as a unidimensional construct. The study was conducted on a national cross-sectional sample of 3,559 first-year high school students (aged 15.1 years). Latent profiles were identified via maximum likelihood estimation, and model fit was evaluated through multiple fit indices. The BCH method was used to assess profile associations with distal outcomes. Six distinct profiles were identified along with their relationships with distal outcomes (Vulnerable Youth: Distressed and Risk Behaving, Caring but Struggling: Distressed but Reserved, Balanced Achievers: Resilient Contributors, Self-Centred Underachievers: Risk Behaving, Confident but Detached: High-Performing Rebels, and Thriving Stars: Thriving and Contributing). The results highlight how strengths in one area (e.g., confidence, competence, and caring) can coexist with significant risks (e.g., binge drinking, antisocial behaviour, and mental health), whereas adolescents with poor mental health or risk behaviour may possess very different internal and external resources. Among the below-average PYD groups, students with very low levels of character and caring but preserved confidence are prone to risk behaviors while being somewhat protected from mental health issues. Others, characterized by high diversity and caring but very low confidence, show vulnerability to mental health challenges without risk behaviors. Additionally, high-risk behaviors can either cooccur with mental health issues in extremely low-PYD students or emerge independently in confident, competent adolescents lacking character, caring, and school connections. By revealing unique developmental pathways, this study enhances the understanding of youth development diversity, emphasizing the necessity of examining both observable behaviors and underlying developmental traits for developing targeted interventions that support strengths and address challenges within distinct adolescent subgroups. Show less

This study examined dark microglia-a state linked to central nervous system pathology and neurodegeneration-during postnatal development in the mouse ventral hippocampus, finding that dark microglia interact with blood vessels and synapses and perform trogocytosis of pre-synaptic axon terminals. Furthermore, we found that dark microglia in development notably expressed C-type lectin domain family 7 member A (CLEC7a), lipoprotein lipase (LPL) and triggering receptor expressed on myeloid cells 2 (TREM2) and required TREM2, differently from other microglia, suggesting a link between their role in remodeling during development and central nervous system pathology. Together, these results point towards a previously under-appreciated role for dark microglia in synaptic pruning and plasticity during normal postnatal development. Show less

We have previously identified predator odor as a potent stimulus activating thermogenesis in skeletal muscle in rats. As this may prove relevant for energy balance and weight loss, the current study investigated whether skeletal muscle thermogenesis was altered with negative energy balance, obesity propensity seen in association with low intrinsic aerobic fitness, and monogenic obesity. First, weight loss subsequent to 3 wk of 50% calorie restriction suppressed the muscle thermogenic response to predator odor. Next, we compared rats bred based on artificial selection for intrinsic aerobic fitness - high- and low-capacity runners (HCR, LCR) - that display robust leanness and obesity propensity, respectively. Aerobically fit HCR showed enhanced predator odor-induced muscle thermogenesis relative to the less-fit LCR. This contrasted with the profound monogenic obesity displayed by rats homozygous for a loss of function mutation in Show less

Atabecestat, a potent brain penetrable BACE1 inhibitor that reduces CSF amyloid beta (Aβ), was developed as an oral treatment for Alzheimer's disease (AD). Elevated liver enzyme adverse events were reported in three studies although only one case met Hy's law criteria to predict serious hepatotoxicity. We performed a case-control genome-wide association study (GWAS) to identify genetic risk variants associated with liver enzyme elevation using 42 cases with alanine transaminase (ALT) above three times the upper limit of normal (ULN) and 141 controls below ULN. Additionally, we performed a GWAS using continuous maximal ALT/ULN (expressed as times the ULN) upon exposure to atabecestat as the outcome measure (n = 285). No variant passed the genome-wide significance threshold (p = 5 × 10 The suggestive GWAS signals in the case-control GWAS analysis suggest the potential role of inflammation in atabecestat-induced liver enzyme elevation. Show less

Whole genome scan studies have recently identified the NRXN1 and NRXN3 genes as potential contributing factors in the risk for nicotine addiction. We have genotyped 15 single nucleotide polymorphisms (SNPs) spanning the NRXN1 and NRXN3 genes in 195 unrelated patients with schizophrenia for whom information about their smoking status and number of cigarettes smoked per day (CPD) was obtained. The NRXN3 marker rs1004212 was significantly associated with quantity of tobacco smoked. Individuals homozygous for the C allele of rs1004212 smoked more cigarettes per day than heterozygous individuals. We found no significant association of markers within the NRXN1 gene with the risk of smoking or the quantity of tobacco smoked. Because of the relatively small sample size, this is a preliminary study. However, this candidate gene study supports the observations of molecular studies implicating the NRXN genes in drug addiction and suggests that variants in the NRXN3 gene could contribute to the degree of nicotine dependence in patients with schizophrenia. Show less

The molecular machinery of cell cycle control is known in more detail for budding yeast, Saccharomyces cerevisiae, than for any other eukaryotic organism. In recent years, many elegant experiments on budding yeast have dissected the roles of cyclin molecules (Cln1-3 and Clb1-6) in coordinating the events of DNA synthesis, bud emergence, spindle formation, nuclear division, and cell separation. These experimental clues suggest a mechanism for the principal molecular interactions controlling cyclin synthesis and degradation. Using standard techniques of biochemical kinetics, we convert the mechanism into a set of differential equations, which describe the time courses of three major classes of cyclin-dependent kinase activities. Model in hand, we examine the molecular events controlling "Start" (the commitment step to a new round of chromosome replication, bud formation, and mitosis) and "Finish" (the transition from metaphase to anaphase, when sister chromatids are pulled apart and the bud separates from the mother cell) in wild-type cells and 50 mutants. The model accounts for many details of the physiology, biochemistry, and genetics of cell cycle control in budding yeast. Show less