Germinal center responses to SARS-CoV-2 mRNA vaccines in healthy and immunocompromised individuals.

Vaccine-mediated immunity often relies on the generation of protective antibodies and memory B cells, which commonly stem from germinal center (GC) reactions. An in-depth comparison of the GC responses elicited by SARS-CoV-2 mRNA vaccines in healthy and immunocompromised individuals has not yet been performed due to the challenge of directly probing human lymph nodes. Herein, through a fine-needle aspiration-based approach, we profiled the immune responses to SARS-CoV-2 mRNA vaccines in lymph nodes of healthy individuals and kidney transplant recipients (KTXs). We found that, unlike healthy subjects, KTXs presented deeply blunted SARS-CoV-2-specific GC B cell responses coupled with severely hindered T follicular helper cell, SARS-CoV-2 receptor binding domain-specific memory B cell, and neutralizing antibody responses. KTXs also displayed reduced SARS-CoV-2-specific CD4 and CD8 T cell frequencies. Broadly, these data indicate impaired GC-derived immunity in immunocompromised individuals and suggest a GC origin for certain humoral and memory B cell responses following mRNA vaccination.

Revealing *OOH key intermediates and regulating H2O2 photoactivation by surface relaxation of Fenton-like catalysts.

Hydrogen peroxide (H2O2) molecules play important roles in many green chemical reactions. However, the high activation energy limits their application efficiency, and there is still huge controversy about the activation path of H2O2 molecules over the presence of *OOH intermediates. Here, we confirmed the formation of the key species *OOH in the heterogeneous system, via in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), isotope labeling, and theoretical calculation. In addition, we found that compared with *H2O2, *OOH was more conducive to the charge transfer behavior with the catalyst and the activation of an O-O bond. Furthermore, we proposed to improve the local coordination structure and electronic density of the YFeO3 catalyst by regulating the surface relaxation with Ti modification so as to reduce the activation barrier of H2O2 and to improve the production efficiency of •OH. As a result, the kinetics rates of the Fenton-like (photo-Fenton) reaction had been significantly increased several times. The •OH free radical activity mechanism and molecular transformation pathways of 4-chloro phenol (4-CP) were also revealed. This may provide a clearer vision for the further study of H2O2 activation and suggest a means of designing catalysts for efficient H2O2 activation.

Stem cell-based therapy in cardiac repair after myocardial infarction: Promise, challenges, and future directions.

Stem cells represent an attractive resource for cardiac regeneration. However, the survival and function of transplanted stem cells is poor and remains a major challenge for the development of effective therapies. As two main cell types currently under investigation in heart repair, mesenchymal stromal cells (MSCs) indirectly support endogenous regenerative capacities after transplantation, while induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) functionally integrate into the damaged myocardium and directly contribute to the restoration of its pump function. These two cell types are exposed to a common microenvironment with many stressors in ischemic heart tissue. This review summarizes the research progress on the mechanisms and challenges of MSCs and iPSC-CMs in post-MI heart repair, introduces several randomized clinical trials with 3D-mapping-guided cell therapy, and outlines recent findings related to the factors that affect the survival and function of stem cells. We also discuss the future directions for optimization such as biomaterial utilization, cell combinations, and intravenous injection of engineered nucleus-free MSCs.

LncRNA MEG3 regulates ferroptosis of lens epithelial cells via PTBP1/GPX4 axis to participate in age-related cataract.

Age-related cataract (ARC) is regarded as the principal cause of vision impairment among the aged. The regulatory role of long noncoding RNAs (LncRNAs) in ARC remains unclear. The lncRNA maternally expressed gene 3 (MEG3) has been reported to promote ARC progression, and the underlying mechanism was further investigated in this study. Lens epithelium samples were collected to verify the expression of MEG3. Lens epithelial cells (LECs) were treated with H2O2 to mimic microenvironment of ARC in vitro. Cell viability, reactive oxygen species, and ferroptosis were evaluated during the in viro experiments. In the present work, lncRNA MEG3 was highly expressed in ARC group, compared with normal group. MEG3 was induced, cell viability and glutathione peroxidase 4 (GPX4) level were inhibited, and ferroptosis was promoted in H2O2 treated LECs. LncRNA MEG3 silence reversed the effects of H2O2 on viability and ferroptosis in LECs. Thereafter, lncRNA MEG3 was found to bind to PTBP1 for GPX4 degradation. Silencing of GPX4 reversed the regulation of lncRNA MEG3 inhibition in H2O2-treated LECs. To sum up, lncRNA MEG3 exhibited high expression in ARC. In H2O2-induced LECs, inhibition of lncRNA MEG3 accelerated cell viability and repressed ferroptosis by interaction with PTBP1 for GPX4 messenger RNA decay. Targeting lncRNA MEG3 may be a novel treatment of ARC.

Selective Access to Silacyclopentanes and Homoallylsilanes by La-Catalyzed Hydrosilylations of 1-Aryl Methylenecyclopropanes.

Methylenecyclopropanes (MCPs) have emerged as versatile building blocks in synthetic chemistry because of their unique reactivity. However, metal-catalyzed hydrosilylation of MCPs has met with very limited successes. In this paper, catalytic selective hydrosilylations of MCPs with some primary silanes using an ene-diamido lanthanum ate complex as the catalyst were described. The catalytic reactions resulted in the selective formation of silacyclopentanes and (E)-homoallylsilanes, respectively, depending on the substituents on MCPs. The formation of silacyclopentanes via a catalytic cascade inter- and intramolecular hydrosilylation mechanism is strongly supported by the control and deuteration-labeling experiments and DFT calculations. The unique reactivity and selectivity could be attributed to the large lanthanum ion and ate structure of the catalyst.

RabbitKSSD: accelerating genome distance estimation on modern multi-core architectures.

SUMMARY: We propose RabbitKSSD, a high-speed genome distance estimation tool. Specifically, we leverage load-balanced task partitioning, fast I/O, efficient intermediate result accesses, and high-performance data structures to improve overall efficiency. Our performance evaluation demonstrates that RabbitKSSD achieves speedups ranging from 5.7× to 19.8× over Kssd for the time-consuming sketch generation and distance computation on commonly used workstations. In addition, it significantly outperforms Mash, BinDash, and Dashing2. Moreover, RabbitKSSD can efficiently perform all-vs-all distance computation for all RefSeq complete bacterial genomes (455 GB in FASTA format) in just 2 min on a 64-core workstation. AVAILABILITY AND IMPLEMENTATION: RabbitKSSD is available at https://github.com/RabbitBio/RabbitKSSD.

Antiviral therapy response in patients with chronic hepatitis B and fatty liver: A systematic review and meta-analysis.

The impact of concurrent fatty liver (FL) on response to antiviral therapy in chronic hepatitis B (CHB) patients has not been well characterized. We aimed to systematically review and analyse antiviral treatment response in CHB patients with and without FL. We searched PubMed, Embase, Web of Science and the Cochrane Library databases from inception to 31 May 2023 for relevant studies. Biochemical response (BR), complete viral suppression (CVS) and hepatitis B e antigen (HBeAg) seroconversion in CHB patients with FL (CHB-FL) and without FL (non-FL CHB) were compared. In an initial pool of 2101 citations, a total of 10 studies involving 2108 patients were included. After 12 weeks of treatment, CHB-FL patients as compared with non-FL CHB patients had lower BR rate (48.37% [108/227] vs. 72.98% [126/174], p = .04) but similar trend for CVS (36.86% [80/227] vs. 68.81% [114/174], p = .05) and similar rates of HBeAg seroconversion (6.59% [7/103] vs. 7.40% [7/110], p = .89). However, at week 48, there were no statistically significant differences between CHB-FL and non-FL CHB patients in any of the outcomes, including BR (60.03% [213/471] vs. 69.37% [314/717], p = .67), CVS (65.63% [459/746] vs. 73.81% [743/1132], p = .27) and HBeAg seroconversion (10.01% [30/275] vs. 14.06% [65/453], p = .58) with similar findings for week 96. BR rate was lower in CHB-FL patients after 12 weeks of antiviral treatment. However, after a longer follow-up of either 48 or 96 weeks, no statistically significant differences were observed in BR, CVS or HBeAg seroconversion rates between CHB patients with and without FL.

Different minimal alcohol consumption in male and female individuals with metabolic dysfunction-associated fatty liver disease.

BACKGROUND AND AIMS: The relationship between moderate alcohol intake and health outcomes among individuals with metabolic dysfunction-associated fatty liver disease (MAFLD) is complex. Our aim was to investigate the association of minimal alcohol consumption with all-cause and cause-specific mortality among MAFLD individuals of different genders. METHODS: Our study included 2630 MAFLD individuals from the Third National Health and Nutrition Examination Survey. Cox regression analysis was performed to assess the association between alcohol use measures and all-cause and cause-specific mortality. Restricted cubic spline curves were used to evaluate the relationship between alcohol consumption per week and all-cause mortality. RESULTS: In the entire MAFLD cohort, we observed significant disparities in clinical characteristics between male and female individuals with MAFLD. Higher weekly alcohol consumption was significantly associated with all-cause and cause-specific mortality (male, hazard ratios [HRs]: 1.009, 95% CIs: 1.004-1.014; female, HRs: 1.032, 95% CIs: 1.022-1.042). In males with MAFLD, a linear association with all-cause mortality was observed for weekly alcohol consumption (p for non-linearity = .21). Conversely, in females with MAFLD, the risk of all-cause mortality remained relatively stable until 2 drinks per week, after which it rapidly increased with each additional drink consumed, and the increase in mortality risk was higher than that observed in males (p for non-linearity < .05). CONCLUSIONS: Our findings indicate that any increase in weekly alcohol consumption was associated with increased all-cause mortality in men with MAFLD. Conversely, consuming less than 2 drinks per week had minimal impact on the risk of mortality among female.

Development of an Accelerated Rotator-based Drug Release Method for the Evaluation of Bupivacaine Multivesicular Liposomes.

PURPOSE: A multivesicular liposome (MVL) is a liposomal vehicle designed to achieve sustained release characteristics for drugs with short half-lives. For example, a commercial MVL formulation of bupivacaine has been approved by the U.S. Food and Drug Administration for local and regional analgesia. For complex formulations like those containing MVLs, challenges in developing an in vitro release testing (IVRT) method may hinder generic development and regulatory approval. In this study, we developed an accelerated rotator-based IVRT method with the ability to discriminate bupivacaine MVLs with different quality attributes. METHODS: Three IVRT experimental setups including mesh tube, horizontal shaker, and vertical rotator were screened to ensure that at least 50% of bupivacaine can release from MVLs in 24 h. Sample dilution factors, incubation temperature, and the release media pH were optimized for the IVRT. The reproducibility of the developed IVRT method was validated with commercial bupivacaine MVLs. The discriminative capacity was assessed via comparing commercial and compromised bupivacaine MVL formulations. RESULTS: The rotator-based release setup was chosen due to the capability to obtain 70% of drug release within 24 h. The optimized testing conditions were chosen with a 50-fold dilution factor, a temperature of 37ºC, and a media pH of 7.4. CONCLUSIONS: An accelerated rotator-based IVRT method for bupivacaine MVLs was developed in this study, with the discriminatory ability to distinguish between formulations of different qualities. The developed IVRT method was a robust tool for generic development of MVL based formulations.

Macrophages Promote Atherosclerosis Development by Inhibiting CD8T Cell Apoptosis.

Background: Atherosclerosis is an inflammatory cardiovascular disease. However, whether the association of immune cells in plaques promotes the progression of this disease has not yet been completely elucidated. Materials and Methods: Thus, this study aimed to investigate the relationship between C1q+ macrophages and CD8T cells through scRNA-seq data reanalysis, quantitative real-time PCR, and flow cytometry. Chromatin immunoprecipitation-quantitative polymerase chain reaction, western blot, and antibody-blocking experiments were performed to investigate the role of macrophage-CD8T interaction in atherosclerosis. An atherosclerotic mouse model was developed to confirm our findings. Results: Mechanistically, Spi1 expression induced by granulocyte-macrophage colony-stimulating factor promoted C1q expression in the macrophages. Moreover, C1q+ macrophages suppressed CD8T cell apoptosis by upregulating Slc7a7 expression to enhance the L-arginine uptake of CD8T cells. CD8T-derived interferon-γ promoted macrophage activation to induce atherosclerosis. Blockade of the C1q-C1qbp axis attenuated atherosclerosis. Conclusion: In conclusion, macrophages interacting with CD8T promote atherosclerosis development via the C1q-C1qbp axis.

Timing outweighs magnitude of rainfall in shaping population dynamics of a small mammal species in steppe grassland.

Climate change-induced shifts in species phenology differ widely across trophic levels, which may lead to consumer-resource mismatches with cascading population and ecosystem consequences. Here, we examined the effects of different rainfall patterns (i.e., timing and amount) on the phenological asynchrony of population of a generalist herbivore and their food sources in semiarid steppe grassland in Inner Mongolia. We conducted a 10-y (2010 to 2019) rainfall manipulation experiment in 12 0.48-ha field enclosures and found that moderate rainfall increases during the early rather than late growing season advanced the timing of peak reproduction and drove marked increases in population size through increasing the biomass of preferred plant species. By contrast, greatly increased rainfall produced no further increases in vole population growth due to the potential negative effect of the flooding of burrows. The increases in vole population size were more coupled with increased reproduction of overwintered voles and increased body mass of young-of-year than with better survival. Our results provide experimental evidence for the fitness consequences of phenological mismatches at the population level and highlight the importance of rainfall timing on the population dynamics of small herbivores in the steppe grassland environment.

Design of a Compact Circularly Polarized Implantable Antenna for Capsule Endoscopy Systems.

This research proposes a miniature circular polarization antenna used in a wireless capsule endoscopy system at 2.45 GHz for industrial, scientific, and medical bands. We propose a method of cutting a chamfer rectangular slot on a circular radiation patch and introducing a curved radiation structure into the centerline position of the chamfer rectangular slot, while a short-circuit probe is added to achieve miniaturization. Therefore, we significantly reduced the size of the antenna and made it exhibit circularly polarized radiation characteristics. A cross-slot is cut in the GND to enable the antenna to better cover the operating band while being able to meet the complex human environment. The effective axis ratio bandwidth is 120 MHz (2.38-2.50 GHz). Its size is π × 0.032λ02 × 0.007λ0 (where λ0 is the free-space wavelength of at 2.4 GHz). In addition, the effect of different organs such as muscle, stomach, small intestine, and big intestine on the antenna when it was embedded into the wireless capsule endoscopy (WCE) system was further discussed, and the results proved that the WCE system has better robustness in different organs. The antenna's specific absorption rate can follow the IEEE Standard Safety Guidelines (IEEE C95.1-1999). A prototype is fabricated and measured. The experimental results are consistent with the simulation results.

Chlorogenic Acid Enhances the Intestinal Health of Weaned Piglets by Inhibiting the TLR4/NF-κB Pathway and Activating the Nrf2 Pathway.

Chlorogenic acid (CGA) is a natural polyphenol with potent antioxidant and anti-inflammatory activities. However, the exact role of it in regulating intestinal health under oxidative stress is not fully understood. This study aims to investigate the effects of dietary CGA supplementation on the intestinal health of weaned piglets under oxidative stress, and to explore its regulatory mechanism. Twenty-four piglets were randomly divided into two groups and fed either a basal diet (CON) or a basal diet supplemented with 200 mg/kg CGA (CGA). CGA reduced the diarrhea rate, increased the villus height in the jejunum, and decreased the crypt depth in the duodenum, jejunum, and ileum of the weaned piglets (p < 0.05). Moreover, CGA increased the protein abundance of Claudin-1, Occludin, and zonula occludens (ZO)-1 in the jejunum and ileum (p < 0.05). In addition, CGA increased the mRNA expression of pBD2 in the jejunum, and pBD1 and pBD2 in the ileum (p < 0.05). The results of 16S rRNA sequencing showed that CGA altered the ileal microbiota composition and increased the relative abundance of Lactobacillus reuteri and Lactobacillus pontis (p < 0.05). Consistently, the findings suggested that the enhancement of the intestinal barrier in piglets was associated with increased concentrations of T-AOC, IL-22, and sIgA in the serum and T-AOC, T-SOD, and sIgA in the jejunum, as well as T-AOC and CAT in the ileum caused by CGA (p < 0.05). Meanwhile, CGA decreased the concentrations of MDA, IL-1ß, IL-6, and TNF-α in the serum and jejunum and IL-1ß and IL-6 in the ileum (p < 0.05). Importantly, this study found that CGA alleviated intestinal inflammation and oxidative stress in the piglets by inhibiting the TLR4/NF-κB signaling pathway and activating the Nrf2 signaling pathway. These findings showed that CGA enhances the intestinal health of weaned piglets by inhibiting the TLR4/NF-κB pathway and activating the Nrf2 pathway.

Evaluation of in vitro Skin Permeation of Clascoterone From Clascoterone Topical Cream, 1% (w/w).

Winlevi® (clascoterone) topical cream (1%, w/w) was approved by the U.S. FDA for the treatment of acne vulgaris in patients 12 years of age and older. The active ingredient, clascoterone, is not stable in physiological solutions and can hydrolyze to cortexolone at body temperature. Instability of clascoterone poses a significant challenge in accurately assessing the rate and extent of clascoterone permeation in vitro. Therefore, the purpose of this study was to develop an in vitro skin permeation test (IVPT) method, and a robust analytical method, that can minimize hydrolyzation of clascoterone during the study for quantification of clascoterone. Two IVPT methods, using either vertical diffusion cells or flow-through cells, were developed and compared to evaluate in vitro permeation of clascoterone from Winlevi. A liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed to monitor the level of clascoterone and cortexolone in the IVPT samples. The analytical method features a 2-min high-throughput analysis with good linearity, selectivity, and showed a lower limit of quantitation (LLOQ) of 0.5 ng/mL for both clascoterone and cortexolone. The in vitro skin permeation of clascoterone and cortexolone was observed as early as 2 h in both IVPT methods. A substantive amount of clascoterone was found to hydrolyze to cortexolone when using the vertical static diffusion cells with aliquot sampling. Conversely, degradation of clascoterone was significantly minimized when using the flow-through diffusion cells with fractional sampling. The data enhanced our understanding of in vitro permeation of clascoterone following topical application of the Winlevi topical cream, 1% and underscores the importance of IVPT method development and optimization during product development.

Study on the anti-atherosclerosis mechanisms of Tanyu Tongzhi formula based on network pharmacology, Mendelian randomization, and experimental verification.

CONTEXT: Tanyu Tongzhi Formula (TTF) exhibits potential against atherosclerosis; however, its mechanisms remain unclear. OBJECTIVE: This study explores the pharmacological mechanisms of TTF in treating atherosclerosis. MATERIALS AND METHODS: Network pharmacology, molecular docking, mendelian randomization (MR), and liquid chromatography-mass spectrometry (LC-MS) analyses were utilized to reveal potential targets and compounds of TTF against atherosclerosis. After exploring the appropriate concentration of TTF to treat HCAECs using Cell Counting Kit-8 (CCK-8), the HCAECs were divided into three groups: control, oxidized low-density lipoprotein (ox-LDL, 50 µg/mL), and ox-LDL (50 µg/mL) + TTF (1 mg/mL). After 24-h incubation, the efficacy of TTF was verified by CCK-8, Oil red O staining, and ELISA. The expression of key targets was detected by real-time polymerase chain reaction (qPCR) and western blotting. RESULTS: A total of 137 active compounds and 127 potential TTF targets against atherosclerosis were identified. MR identified ALB, TNF, PPARα, and PPARγ as key targets. Molecular docking indicated that baicalin, naringenin, and curcumin exhibited suitable binding activities to these targets, further confirming by LC-MS analysis. The IC50 of TTF in HCAECs was 18.25 mg/mL. TTF treatment significantly improved atherosclerosis by enhancing cell viability, reducing lipid accumulation, and inhibiting inflammation factors (IL6, IL1B and TNF-α) in ox-LDL-treated HCAECs. Moreover, qPCR or western blotting indicated that TTF could up-regulate PPARα and PPARγ while down-regulate TNF expression. DISCUSSION AND CONCLUSIONS: Our results revealed active compounds, key pathways, and core targets of TTF against atherosclerosis, providing experimental support for its application in treating of atherosclerosis.

Full-Spectrum Responsive Naphthalimide/Perylene Diimide with a Giant Internal Electric Field for Photocatalytic Overall Water Splitting.

The co-assembly naphthalimide/perylene diimide (NDINH/PDINH) supramolecular photocatalysts were successfully synthesized via a rapid solution dispersion method. A giant internal electric field (IEF) in co-assembly structure was built by the larger local dipole. NDINH coated on PDINH could reduce the reflected electric field over PDINH to improve its responsive activity to ultraviolet light. Resultantly, an efficient full-spectrum photocatalytic overall water splitting activity with H2 and O2 evolution rate of 317.2 and 154.8 µmol g-1 h-1 for NDINH/PDINH together with optimized O2 evolution rate with 2.61 mmol g-1 h-1 using AgNO3 as a sacrificial reagent were achieved. Meanwhile, its solar-to-hydrogen efficiency was enhanced to 0.13 %. The enhanced photocatalytic activity was primarily attributed to the IEF between NDINH and PDINH, significantly accelerating transfer and separation of photogenerated carriers. Additionally, a direct Z-Scheme pathway of carriers contributed to a high redox potential. The strategy provided a new perspective for the design of supramolecular photocatalysts.

Lattice Oxygen in Photocatalytic Gas-Solid Reactions: Participator vs. Dominator.

Lattice-oxygen activation has emerged as a popular strategy for optimizing the performance and selectivity of oxide-based thermocatalysis and electrolysis. However, the significance of lattice oxygen in oxide photocatalysts has been ignored, particularly in gas-solid reactions. Here, using methane oxidation over a Ru1@ZnO single-atom photocatalyst as the prototypical reaction and via 18O isotope labelling techniques, we found that lattice oxygen can directly participate in gas-solid reactions. Lattice oxygen played a dominant role in the photocatalytic reaction, as determined by estimating the kinetic constants in the initial stage. Furthermore, we discovered that dynamic diffusion between O2 and lattice oxygen proceeded even in the absence of targeted reactants. Finally, single-atom Ru can facilitate the activation of adsorbed O2 and the subsequent regeneration of consumed lattice oxygen, thus ensuring high catalyst activity and stability. The results provide guidance for next-generation oxide photocatalysts with improved activities and selectivities.

Ultrafast and Ultralarge Lithium-Ion Storage Enabled by Fluorine-Nitrogen Co-Implanted Carbon Tubes.

As a holy grail in electrochemistry, both high-power and high-energy electrochemical energy storage system (EES) has always been a pursued dream. To simultaneously achieve the "both-high" EES, a rational design of structure and composition for storage materials with characteristics of battery-type and capacitor-type storage is crucial. Herein, fluorine-nitrogen co-implanted carbon tubes (FNCT) have been designed, in which plentiful active sites and expanded interlayer space have been created benefiting from the heteroatom engineering and the fluorine-nitrogen synergistic effect, thus the above two-type storage mechanism can get an optimal balance in the FNCT. The implanted fluorine heteroatoms can not only amplify interlayer spacing, but also induce the transformation of nitrogen configuration from pyrrole nitrogen to pyridine nitrogen, further promoting the activity of the carbon matrix. The extraordinary electrochemical performance as results can be witnessed for FNCT, which exhibit fast lithium-ion storage capability with a high energy density of 119.4 Wh kg-1 at an ultrahigh power density of 107.5 kW kg-1 .

RabbitV: fast detection of viruses and microorganisms in sequencing data on multi-core architectures.

MOTIVATION: Detection and identification of viruses and microorganisms in sequencing data plays an important role in pathogen diagnosis and research. However, existing tools for this problem often suffer from high runtimes and memory consumption. RESULTS: We present RabbitV, a tool for rapid detection of viruses and microorganisms in Illumina sequencing datasets based on fast identification of unique k-mers. It can exploit the power of modern multi-core CPUs by using multi-threading, vectorization and fast data parsing. Experiments show that RabbitV outperforms fastv by a factor of at least 42.5 and 14.4 in unique k-mer generation (RabbitUniq) and pathogen identification (RabbitV), respectively. Furthermore, RabbitV is able to detect COVID-19 from 40 samples of sequencing data (255 GB in FASTQ format) in only 320 s. AVAILABILITY AND IMPLEMENTATION: RabbitUniq and RabbitV are available at https://github.com/RabbitBio/RabbitUniq and https://github.com/RabbitBio/RabbitV. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Role of PLGA Variability in Controlled Drug Release from Dexamethasone Intravitreal Implants.

Long-acting injectable formulations based on poly(lactide-co-glycolide) (PLGA) have been commercialized for over 30 years in at least 20 FDA-approved products. These formulations offer several advantages, including reduced dosing frequency, improved patient compliance, and maintenance of therapeutic levels of drug. Despite extensive studies, the inherent complexity of the PLGA copolymer still poses significant challenges associated with the development of generic formulations having drug release profiles equivalent to those of the reference listed drugs. In addition, small changes to PLGA physicochemical properties or the drug product manufacturing process can have a major impact on the drug release profile of these long-acting formulations. This work seeks to better understand how variability in the physicochemical properties of similar PLGAs affects drug release from PLGA solid implants using Ozurdex (dexamethasone intravitreal implant) as the model system. Four 50:50, acid-terminated PLGAs of similar molecular weights were used to prepare four dexamethasone intravitreal implants structurally equivalent to Ozurdex. The PLGAs were extensively characterized by using a variety of analytical techniques prior to implant manufacture using a continuous, hot-melt extrusion process. In vitro release testing of the four structurally equivalent implants was performed in both normal saline and phosphate-buffered saline (PBS), yielding drastically different results between the two methods. In normal saline, no differences in the release profiles were observed. In PBS, the drug release profiles were sensitive to small changes in the residual monomer content, carboxylic acid end group content, and blockiness of the polymers. This finding further underscores the need for a physiologically relevant in vitro release testing method as part of a robust quality control strategy for PLGA-based solid implant formulations.