Post-acute sequelae of COVID-19 and longitudinal antibody levels in a community-based cohort.

Background: Coronavirus disease 2019 (COVID-19) infection invokes variable immune responses and poses a risk of post-acute sequelae SARS-CoV-2 infection (PASC) symptoms; however, most data on natural history are derived from patients with severe infection. Further data are needed among patients with mild infection, who comprise most cases.

Methods: The Dallas Fort-Worth (DFW) COVID-19 Prevalence Study included 21,597 community-dwelling adults (ages 18-89) who underwent COVID-19 PCR and anti-nucleocapsid antibody testing between July 2020 and March 2021.

Persistent low prevalence of hepatitis B vaccination among people with HIV: Time for a change?

Hepatitis B virus (HBV) infection is one of the leading causes of hepatocellular carcinoma and mortality among people living with HIV (PLWH). HBV vaccination provides protection from infection; however, vaccination rates are low. We conducted a retrospective analysis at three HIV centres in Texas to determine the proportion of PLWH who received the recommended 3 doses of hepatitis B vaccine within 1 year.

Toxicity evaluation of ConvitVax breast cancer immunotherapy.

ConvitVax is a personalized vaccine for the treatment of breast cancer, composed of autologous tumor cells, bacillus Calmette-Guérin (BCG) and low concentrations of formalin. Previous pre-clinical studies show that this therapy induces a potent activation of the immune system and achieves an effective response against tumor cells, reducing the size of the tumor and decreasing the percentage of immunosuppressive cells. In the present study, we evaluate the toxicity of ConvitVax in healthy BALB/c mice to determine potential adverse effects related to the vaccine and each of its components.

Fungicidal Potency and Mechanisms of θ-Defensins against Multidrug-Resistant Candida Species.

Systemic candidiasis is a growing health care concern that is becoming even more challenging due to the growing frequency of infections caused by multidrug-resistant (MDR) species. Thus, there is an urgent need for new therapeutic approaches to candidiasis, including strategies bioinspired by insights into natural host defense against fungal pathogens. The antifungal properties of θ-defensins, macrocyclic peptides expressed in tissues of Old World monkeys, were investigated against a panel of drug-sensitive and drug-resistant clinical isolates of and non- species.

Participation of alkoxy groups in reactions of acetals: violation of the reactivity/selectivity principle in a Curtin-Hammett kinetic scenario.

Nucleophilic substitution reactions of acetals having benzyloxy groups four carbon atoms away can be highly diastereoselective. The selectivity in several cases increased as the reactivity of the nucleophile increased, in violation of the reactivity/selectivity principle. The increase in selectivity with reactivity suggests that multiple conformational isomers of reactive intermediates can give rise to the products.

Influence of alkoxy groups on rates of acetal hydrolysis and tosylate solvolysis: electrostatic stabilization of developing oxocarbenium ion intermediates and neighboring-group participation to form oxonium ions.

The hydrolysis of 4-alkoxy-substituted acetals was accelerated by about 20-fold compared to that of sterically comparable substrates that do not have an alkoxy group. Rate accelerations are largest when the two functional groups are linked by a flexible cyclic tether. When controlled for the inductive destabilization, an alkoxy group can accelerate acetal hydrolysis by up to 200-fold.

Acceleration of acetal hydrolysis by remote alkoxy groups: evidence for electrostatic effects on the formation of oxocarbenium ions.

In contrast to observations with carbohydrates, experiments with 4-alkoxy-substituted acetals indicate that an alkoxy group can accelerate acetal hydrolysis by up to 20-fold compared to substrates without an alkoxy group. The acceleration of ionization in more flexible acetals can be up to 200-fold when compensated for inductive effects.

Recombinant production of rhesus θ-defensin-1 (RTD-1) using a bacterial expression system.

Defensins are antimicrobial peptides that are important in the innate immune defense of mammals. In contrast to mammalian α- and β-defensins, rhesus θ-defensin-1 (RTD-1) comprises only 18 amino acids stabilized by three disulfide bonds and an unusual backbone cyclic topology. In this work we report for the first time the recombinant expression of the fully folded θ-defensin RTD-1 using a bacterial expression system.

Biosynthesis and antimicrobial evaluation of backbone-cyclized α-defensins.

Defensins are antimicrobial peptides that are important in the innate immune defense of mammals. Upon stimulation by bacterial antigens, enteric α-defensins are secreted into the intestinal lumen where they have potent microbicidal activities. Cryptdin-4 (Crp4) is an α-defensin expressed in Paneth cells of the mouse small intestine and the most bactericidal of the known cryptdin isoforms.

Criterion for amino acid composition of defensins and antimicrobial peptides based on geometry of membrane destabilization.

Defensins comprise a potent class of membrane disruptive antimicrobial peptides (AMPs) with well-characterized broad spectrum and selective microbicidal effects. By using high-resolution synchrotron small-angle X-ray scattering to investigate interactions between heterogeneous membranes and members of the defensin subfamilies, α-defensins (Crp-4), β-defensins (HBD-2, HBD-3), and θ-defensins (RTD-1, BTD-7), we show how these peptides all permeabilize model bacterial membranes but not model eukaryotic membranes: defensins selectively generate saddle-splay ("negative Gaussian") membrane curvature in model membranes rich in negative curvature lipids such as those with phosphoethanolamine (PE) headgroups. These results are shown to be consistent with vesicle leakage assays.

Protein microarrays: novel developments and applications.

Protein microarray technology possesses some of the greatest potential for providing direct information on protein function and potential drug targets. For example, functional protein microarrays are ideal tools suited for the mapping of biological pathways. They can be used to study most major types of interactions and enzymatic activities that take place in biochemical pathways and have been used for the analysis of simultaneous multiple biomolecular interactions involving protein-protein, protein-lipid, protein-DNA and protein-small molecule interactions.

Biological activities of natural and engineered cyclotides, a novel molecular scaffold for peptide-based therapeutics.

Cyclotides are a growing family of large plant-derived backbone-cyclized polypeptides (≈30 amino acids long) that share a disulfide-stabilized core characterized by an unusual knotted structure. Their unique circular backbone topology and knotted arrangement of three disulfide bonds makes them exceptionally stable to thermal, chemical, and enzymatic degradation compared to other peptides of similar size. Currently more than 100 sequences of different cyclotides have been characterized and the number is expected to increase dramatically in the coming years.

Dual induction of TREM2 and tolerance-related transcript, Tmem176b, in amyloid transgenic mice: implications for vaccine-based therapies for Alzheimer's disease.

Vaccine-based autoimmune (anti-amyloid) treatments are currently being examined for their therapeutic potential in Alzheimer's disease. In the present study we examined, in a transgenic model of amyloid pathology, the expression of two molecules previously implicated in decreasing the severity of autoimmune responses: TREM2 (triggering receptor expressed on myeloid cells 2) and the intracellular tolerance-associated transcript, Tmem176b (transmembrane domain protein 176b). In situ hybridization analysis revealed that both molecules were highly expressed in plaque-associated microglia, but their expression defined two different zones of plaque-associated activation.

P2X4 receptors in activated C8-B4 cells of cerebellar microglial origin.

We investigated the properties and regulation of P2X receptors in immortalized C8-B4 cells of cerebellar microglial origin. Resting C8-B4 cells expressed virtually no functional P2X receptors, but largely increased functional expression of P2X4 receptors within 2-6 h of entering the activated state. Using real-time polymerase chain reaction, we found that P2X4 transcripts were increased during the activated state by 2.

Thermal isomerization of cannabinoid analogues.

Thermal isomerization of CBC(an) to THC(an) [nonaromatic analogues of plant cannabinoids cannabichromene (CBC) and Delta(1)-tetrahydrocannabinol (THC), respectively] is predicted in silico and demonstrated experimentally. Density functional theory calculations support a similar isomerization mechanism for the corresponding plant cannabinoids. Docking studies suggest that THC(an), although nonaromatic, has a CB(1) receptor binding affinity similar to that of natural THC.

Isolation, synthesis, and antimicrobial activities of naturally occurring theta-defensin isoforms from baboon leukocytes.

Theta-defensins are macrocyclic antimicrobial peptides that were previously isolated from leukocytes of a single species, the rhesus macaque. We now report the characterization of baboon theta-defensins (BTDs) expressed in bone marrow and peripheral blood leukocytes. Four cDNAs encoding theta-defensin precursors were characterized, allowing for the prediction of 10 theoretical theta-defensins (BTD-1 to BTD-10) produced by binary, head-to-tail splicing of nonapeptides excised from paired precursors.