Amyloid-β (Aβ) and tau are major pathological hallmarks of Alzheimer's disease (AD). Several studies have revealed that Aβ accelerates pathological tau transition and spreading during the disease progression, and that reducing tau can mitigate pathological features of AD. However, molecular links between Aβ and tau pathologies remain elusive. Here, we suggest a novel role for the plexin-A4 as an Aβ receptor that induces aggregated tau pathology. Plexin-A4, previously known as proteins involved in regulating axon guidance and synaptic plasticity, can bound to Aβ with co-receptor, neuropilin-2. Genetic downregulation of plexin-A4 in neurons was sufficient to prevent Aβ-induced activation of CDK5 and reduce tau hyperphosphorylation and aggregation, even in the presence of Aβ. In an AD mouse model that manifests both Aβ and tau pathologies, genetic downregulation of plexin-A4 in the hippocampus reduced tau pathology and ameliorated spatial memory impairment. Collectively, these results indicate that the plexin-A4 is capable of mediating Aβ-induced tau pathology in AD pathogenesis.Micronization by air jet milling is often used to produce drug substance particles of acceptable respirable size for use in dry powder inhaler formulations. The energy from this process often induces surface disordered sites on the micronized particles with potential consequences for the long-term stability of the drug substance. In this study, two lots of the same drug substance were qualitatively determined to have different extents of disordered surface using dynamic vapor sorption and scanning electron microscopy. These differences led to observable divergences in particle size and morphology between lots of drug substances on long-term and accelerated stability. The studies investigate the contribution of temperature and humidity, morphology prior to milling, and stability behavior post-micronization.  https://www.selleckchem.com/products/jhu-083.html  The results highlight the importance of controlling the crystallization solvents upstream of micronization and their contribution to a material's susceptibility to milling-induced disorder on long-term physical stability. Furthermore, this work proposes an accelerated technique useful in predicting stability behavior of micronized drug substances in days rather than months, especially in cases where small differences cannot be detected by standard solid-state techniques.HPMCAS-HF, HPMCAS-MF and HPMCAS-LF were used as carriers to prepare the amorphous solid dispersions (ASDs) of quercetin (Que) by co-precipitation. The Que ASD based on PVP K30 was prepared by solvent evaporation method. The ability of polymer to inhibit Que crystallization was evaluated. The study found the order of the ability of polymer to inhibit Que nucleation to be HF > MF > LF > K30, and that to maintain Que supersaturation to be HF > K30 > MF > LF. The prepared solid dispersions were characterized by IR, DSC and PXRD. Although HF was the most effective crystallization inhibitor, the release of the Que/HF ASD was poor and assigned to the carrier-controlled dissolution for the strong interactions between Que and HF. The Que/MF ASD exhibited better dissolution behavior compared to the Que/K30 ASD. The dissolution behavior of the Que ASD depended on the polymer-Que interactions and the ability of crystallization inhibition of the polymer.Monoclonal antibody (mAb)-based drugs are often prone to unfavorable solution behaviors including high viscosity, opalescence, phase separation, and aggregation at the high concentrations needed to enable patient-centric subcutaneous dosage forms. Given that these can have a detrimental impact on manufacturability, stability, and delivery, approaches to identifying, monitoring, and controlling these behaviors during drug development are critical. Opalescence presents a significant challenge due to its relationship to liquid-liquid phase separation. Quantitative characterization of opalescence via turbidimetry is often restrictive due to large volume requirements (>2 mL) and alternative microscale approaches based on light transmittance (Eckhardt et al., J Pharm Sci Technol. 1994, 48 64-70) may pose challenging with respect to accuracy. To address the need for accurate and quantitative microscale opalescence measurements, we have evaluated the use of a 'de-tuned' static light scattering detector which requires less then 10 μL sample per measurement. We show that tuning of the laser power to a range far below that of traditional light scattering measurements results in a stable detector response that can be accurately calibrated to the nephelometric turbidity unit (NTU) scale using appropriate standards. The calibrated detector signal yields NTU values for mAbs and other protein solutions that are comparable to a commercial turbidimeter. We used this microscale approach to characterize the opalescence of 48 commercial mAb drug products and found that the majority have opalescence below 15 NTU. However, in products with mAb concentrations greater than 75 mg/mL, a broad range of opalescence was observed, in a few cases greater than 20 NTU. These measurements as well as nephelometric characterization of several IgG1 and IgG4 mAbs across a broad pH range highlight subclass-specific tendencies toward opalescence in high concentration solutions.
  Loss of serum HBsAg is a hallmark of spontaneous and therapy induced resolution of HBV infection, since it generally reflects a profound decrease in viral replication. However, integrated HBV DNA can contribute to HBsAg expression independent of viral replication. The relative contributions of these sources of HBsAg are not well understood. Specifically, it is not known whether actively transcribed HBV integration could spread throughout the entire liver.
 
  The relative distribution of HBsAg and HBV RNA in liver biopsy tissue from HBeAg-negative (HBe
  ) patients was analyzed by immunohistochemistry and in situ hybridization (ISH), respectively. Frozen biopsy tissue was used for molecular analysis of intrahepatic viral RNA, virus-host chimeric transcripts and viral DNA.
 
  Immunohistochemistry and ISH analysis revealed HBsAg and HBV RNA positivity in virtually all hepatocytes in the liver of some HBe
  patients despite very low viremia. Reverse transcription quantitative PCR and RNA-sequencing analysis confirmed high expression levels of HBV envelope-encoding RNAs.