We propose a two-step approach to functionalize gold nanoparticles prepared by reducing tetrachloroauric acid by trisodium citrate in water. The chloride and citrate physisorbed on the gold nanoparticles are first displaced by thioctic acid (TA), which is then exchanged by thiols containing the desired functionality during the second step. TA bears a carboxylate group and disulfide; at high pH, the negative charge of the former stabilizes gold nanoparticles and the disulfide develops two S−Au bonds, retarding the desorption kinetics upon further functionalization. The slow kinetics of TA desorption is crucial to establishing sufficient steric stabilization for the gold core while losing electrostatic stabilization. Successful attachment of carboxylate, crown ether, cyclodextrin, pyridine, and amino functionalities is verified by surface sensitive techniques. In most cases, ca. 80% of the TA molecules are displaced. The nanoparticles are stable under solution pH where the surface group is ionized. Although at certain solution acidities, the gold sols have difficulty carrying charges and appear flocculated, the nanoparticles become dispersive after being centrifuged and redissolved in suitable buffer solutions, which indicates the successful protection of the gold cores by steric stabilization.

Retinitis pigmentosa (RP) encompasses a diverse group of Mendelian disorders leading to progressive degeneration of rods and then cones. For reasons that remain unclear, diseased RP photoreceptors begin to deteriorate, eventually leading to cell death and, consequently, loss of vision. Here, we have hypothesized that RP associated with mutations in phosphodiesterase-6 (PDE6) provokes a metabolic aberration in rod cells that promotes the pathological consequences of elevated cGMP and Ca 2+, which are induced by the Pde6 mutation. Inhibition of sirtuin 6 (SIRT6), a histone deacetylase repressor of glycolytic flux, reprogrammed rods into perpetual glycolysis, thereby driving the accumulation of biosynthetic intermediates, improving outer segment (OS) length, enhancing photoreceptor survival, and preserving vision. In mouse retinae lacking Sirt6, effectors of glycolytic flux were dramatically increased, leading to upregulation of key intermediates in glycolysis, TCA cycle, and glutaminolysis. Both transgenic and AAV2/8 gene therapy-mediated ablation of Sirt6 in rods provided electrophysiological and anatomic rescue of both rod and cone photoreceptors in a preclinical model of RP. Due to the extensive network of downstream effectors of Sirt6, this study motivates further research into the role that these pathways play in retinal degeneration. Because reprogramming metabolism by enhancing glycolysis is not gene specific, this strategy may be applicable to a wide range of neurodegenerative disorders.Reprogramming metabolism by targeting sirtuin 6 attenuates retinal degeneration , were challenging to interpret because of negative effects on synaptic transmission (45). We therefore altered our approach to limit ablation of Sirt6 to rod photoreceptors with an inducible gene disruption strategy. Using this model, we tested whether upregulation of glycolytic flux through Sirt6 knockout can preserve both rod and cone photoreceptors in a preclinical, Pde6-associated RP model. The Journal of Clinical Investigation R E S E A R C H A R T I C L E ResultsGeneration of experimental and control groups. The third most common cause of autosomal recessive RP is deficiency in the PDE6 enzyme, which controls the depolarization state of rods by regulating cGMP levels (9, 46-48). An established preclinical model for RP involves a homozygous point mutation (H620Q) in the gene months by increasing glucose uptake and utilization for NADPH production in 4 different mouse models of RP (11,12). In our report, we propose a similar strategy that improves both survival and function of degenerating rods and cones. We hypothesized that Pde6-associated RP provokes a metabolic aberration in the rod cells that forces them to succumb to the consequences of elevated cGMP and Ca 2+ via cyclic nucleotide-gated (CNG) channels and Na + /Ca 2+ -K + exchangers (36-39). The histone deacetylase sirtuin 6 (SIRT6) is a transcriptional repressor of glycolytic enzymes that has been extensively studied in the context of metabolism and cancer biology (40). Normally, S...

While the past decade has seen great progress in mapping loci for common diseases, studying how these risk alleles lead to pathology remains a challenge. Age-related macular degeneration (AMD) affects 9 million older Americans, and is characterized by the loss of the retinal pigment epithelium (RPE). Although the closely linked genome-wide association studies ARMS2/HTRA1 genes, located at the chromosome 10q26 locus, are strongly associated with the risk of AMD, their downstream targets are unknown. Low population frequencies of risk alleles in tissue banks make it impractical to study their function in cells derived from autopsied tissue. Moreover, autopsy eyes from end-stage AMD patients, where age-related RPE atrophy and fibrosis are already present, cannot be used to determine how abnormal ARMS2/HTRA1 expression can initiate RPE pathology. Instead, induced pluripotent stem (iPS) cell-derived RPE from patients provides us with earlier stage AMD patient-specific cells and allows us to analyze the underlying mechanisms at this critical time point. An unbiased proteome screen of A2E-aged patient-specific iPS-derived RPE cell lines identified superoxide dismutase 2 (SOD2)-mediated antioxidative defense in the genetic allele's susceptibility of AMD. The AMD-associated risk haplotype (T-in/del-A) impairs the ability of the RPE to defend against aging-related oxidative stress. SOD2 defense is impaired in RPE homozygous for the risk haplotype (T-in/del-A; T-in/del-A), while the effect was less pronounced in RPE homozygous for the protective haplotype (G-Wt-G; G-Wt-G). ARMS2/HTRA1 risk alleles decrease SOD2 defense, making RPE more susceptible to oxidative damage and thereby contributing to AMD pathogenesis.

No abstract

Standard-of-care infliximab dosing regimens were developed prior to the routine use of therapeutic drug monitoring and identification of target concentrations. Not surprisingly, subtherapeutic infliximab concentrations in pediatric Crohn's disease (CD) are common. The primary aim was to conduct a real-world pharmacokinetic (PK) evaluation to discover blood biomarkers of rapid clearance, identify exposure targets, and a secondary aim to translate PK modeling to the clinic. In a multicenter observational study, 671 peak and trough infliximab concentrations from 78 patients with CD were analyzed with a drug-tolerant assay (Esoterix; LabCorp, Calabasas, CA). Individual area under the curve (AUC) estimates were generated as a measure of drug exposure over time. Population PK modeling (nonlinear mixed-effect modeling) identified serum albumin, antibody to infliximab, erythrocyte sedimentation rate (ESR), and neutrophil CD64 as biomarkers for drug clearance. Week 14 and week 52 biochemical remitters (fecal calprotectin < 250 µg/g) had higher infliximab exposure (AUC) throughout induction. The optimal infliximab AUC target during induction for week 14 biochemical remission was 79,348 µg*h/mL (area under the receiver operating characteristic curve (AUROC) 0.77, [0.63-0.90], 85.7% sensitive, and 64.3% specific) with those exceeding the AUC target more likely to achieve a surgery-free week 52 biochemical remission (OR 4.3,). Pretreatment predictors for subtherapeutic week 14 AUC included neutrophil CD64 > 6 (OR 4.5,), ESR > 30 mm/h (OR 3.8,), age < 10 years old (OR 4.2,), and weight < 30 kg (OR 6.6,). We created a decisionsupport PK dashboard with an iterative process and embedded the modeling program within the electronic health record. Model-informed precision dosing guided by real-world PKs is now available at the bedside in real-time.