Long-Term Survival of Subcutaneous Biosimilar Tumor Necrosis Factor Inhibitors Compared to Originators: Results From a Multicenter Prospective Registry.

OBJECTIVE: To analyze the long-term survival of subcutaneous biosimilar tumor necrosis factor inhibitors compared to the originator molecules in patients with rheumatic diseases, as well as the factors associated with drug discontinuation. METHODS: Retrospective analysis of BIOBADASER, the Spanish multicenter prospective registry of patients with rheumatic disease receiving biologic and targeted disease-modifying antirheumatic drugs. Patients who started etanercept (ETN) or adalimumab (ADA) from January 2016 to October 2023 were included. The survival probabilities of biosimilars and originators were compared using Kaplan-Meier estimating curves. To identify factors associated with differences in the retention rates, hazard ratios (HR) were estimated using Cox regression models for all and specific causes (inefficacy or adverse events [AEs]) of discontinuation. RESULTS: A total of 4162 patients received 4723 treatment courses (2991 courses of ADA and 1732 courses of ETN), of which 722 (15.29%) were with originator molecules and 4001 (84.71%) were with biosimilars. The originators were more frequently discontinued than biosimilars (53.32% vs 33.37%, respectively). The main reason for discontinuation was inefficacy (60.35% of the treatments). The risk of overall discontinuation was lower for biosimilars (adjusted HR 0.84, 95% CI 0.75-0.95). Female sex, obesity, and second or later treatment lines increased the risk of discontinuation, whereas disease duration and the use of concomitant methotrexate were associated with a greater survival. When assessing cause-specific reasons of discontinuation, excluding nonmedical switching, the results from the crude and adjusted analyses showed no significant differences in the retention rate between biosimilars and originators. CONCLUSION: No significant differences were found between treatments in long-term survival due to inefficacy or AEs.

Medicine, Religion, and the Humanitarian Ethos: Walter B. Cannon, Unitarianism, and the Care of Spanish Republican Refugees in France.

Biographies of Walter B. Cannon (1871-1945) usually present two sides of his life: one, where he was an outstanding man of science in the United States during the so-called "Golden Age of Medicine," and the other, where he was a leading humanitarian activist engaged in myriad causes, notably in the defense of Spanish democracy during the Civil War (1936-1939). However, these biographies fail to take into account that the apparent link between these two sides of his life was his religious conviction. This study summarizes the aims and accomplishments of the American Medical Bureau to Aid the Spanish Democracy (AMBASD) of which Cannon was chair between 1937 and 1939. Then, it examines Cannon's inspirational role on the international relief work with Spanish Republican refugees in France, through the case of the Varsovie Hospital of Toulouse that between 1945 and 1949 was jointly managed by the Unitarian Service Committee (USC) and the Joint Anti-Fascist Refugee Committee (JAFRC), and renamed Varsovie Hospital/Walter B. Cannon Memorial in recognition of the Spanish Republicans' debt for his extraordinary contribution during the Spanish Civil War and beyond. Finally, the article investigates the Unitarian roots of Cannon's humanitarian ethos by exploring the historical relations of this religious movement with science and with many major actors at Harvard University as well as the links of Cannon's relatives to Unitarianism. The analysis reveals Unitarianism's influence on Cannon's views about science, democracy, and liberty, as well as on his remarkable involvement in the medical solidarity movement with the Second Spanish Republic and other similar commitments. In sum, it shows how important is to branch out in our studies of medical and scientific practice to include practitioners' broader social and religious communities in order to understand their motivations, achievements, and behavior.

Identification of adjuvants in plant protection products applying a suspect screening workflow based on orthogonal techniques.

In this study, the identification of adjuvants (surfactants and solvents) in quizalofop-p-ethyl plant protection products (PPPs) was carried out by applying nuclear magnetic resonance (NMR), ultra-high-performance liquid chromatography (UHPLC) and gas chromatography (GC), both coupled to high-resolution mass spectrometry (HRMS), and using a suspect analysis approach. NMR provided a rapid and global overview of the composition of the studied samples and supported the tentative identification of the glycol ether family, commonly employed as surfactants, and 2-ethyl-1-butanol. UHPLC-HRMS was used for characterization of the glycol polymer surfactants, while GC-HRMS was used to obtain information about volatile organic compounds (benzene or naphthalene derivates) present in the PPPs. A total of nine adjuvants were characterized in the tested PPPs, belonging to naphthalene, benzene, sulphate and fatty acid esters of glycerol families. In addition, the estimation of compound concentrations was carried out using GC(LC)-HRMS, and finally, these concentration levels were related to their toxicity values.

The powers of masculinization in humanitarian storytelling: the case of the surgeon María Gómez Álvarez in the Varsovia Hospital (Toulouse, 1944-1950).

This contribution is focused on analysing the power of 'masculinization' through which traditional humanitarian storytelling has been shaped. Strongly marked by a patriarchal vision, humanitarian accounts have traditionally hidden the work of women while stressing that performed by men, who appeared represented as true protagonists and, even, as heroes. In particular, this article analyses the professional career of a Spanish female surgeon named María Gómez (1914-1975) between 1944 and 1950, when she worked in a small charitable hospital based in Toulouse (France) for improving the health-care conditions of Spanish Republican refugees. Known as Hospital Varsovia or as Walter B. Cannon Memorial Hospital in the United States, it was supported by several humanitarian agencies, such as the Unitarian Service Committee (USC) and the Joint Anti-Fascist Refugee Committee (JAFRC). In order to get funds, both entities filmed a propaganda documentary in 1946, Spain in Exile, which deliberately ignored Gómez's work as a surgeon in this hospital. By examining this visual record, this article attempts to reconstruct the life and the professional career of this female physician, which was at the crossroads of the Spanish Civil War, the Second World War and the ideological polarization emerging in the Cold War period.

Pushing the frontiers: boron-11 NMR as a method for quantitative boron analysis and its application to determine boric acid in commercial biocides.

Quantitative boron-11 NMR (11B qNMR) spectroscopy has been introduced for the first time as a method to determine boric acid content in commercial biocides. Validation of the method affords a limit of detection of 0.02% w/w and a limit of quantification of 0.04% w/w, which are low enough to determine boric acid in commercial biocides. Other figures of merit such as linearity (R2 > 0.99), recovery (93.6%-106.2%), intra- and inter-day precision (from 0.7 to 2.0%), uncertainty (3.7 to 4.4%) and matrix effects were also evaluated. This method was successfully applied to determine boric acid in five different commercial biocides in a wide range of concentrations (<0.05 to 10% w/w) providing excellent results when they were compared with those obtained using inductively coupled plasma-mass spectrometry (ICP-MS). The suitability of this method for a fast and reliable quantification of boric acid in commercial biocide preparations has been demonstrated. The absence of the matrix effect allows the application of this validated method for the determination of boric acid in other matrices of diverse composition.

Simultaneous analysis of tropane alkaloids in teas and herbal teas by liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap).

A new method has been developed for the simultaneous determination of 13 tropane alkaloids in tea and herbal teas using high-performance liquid chromatography coupled to an Exactive-Orbitrap analyzer. A mixture of methanol, water, and formic acid was used for the extraction of the target compounds followed by a solid-phase extraction step. The validated method provided recoveries from 75 to 128% with intra- and interday precision lower than or equal to 24% (except for apoatropine). Limits of quantification ranged from 5 to 20 µg/kg. Eleven tea and herbal tea samples and two contaminated samples with Datura stramonium seeds were analyzed. Tropane alkaloids were detected in six samples with concentrations from 5 (apoatropine) to 4340 µg/kg (sum of physoperuvine, pseudotropine, and tropine), whereas concentrations from 5 (apoatropine) to 1725 µg/kg (sum of physoperuvine, pseudotropine, and tropine) were found in the contaminated samples.

Behavior of quizalofop-p and its commercial products in water by liquid chromatography coupled to high resolution mass spectrometry.

A degradation study of quizalofop-p and its commercial products (quizalofop-p-ethyl, quizalofop-p-tefuryl and propaquizafop) in water samples has been performed using ultra high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). CHHQ (dihydroxychloroquinoxalin), CHQ (6-chloroquinoxalin-2-ol) and PPA ((R)-2-(4-hydroxyphenoxy)propionicacid) were the main metabolites of this active substance (quizalofop-p) in water. The degradation of the parent compound has been monitored in distilled water. Several commercial products (Panarex®, Master-D® and Dixon®) were used to evaluate the degradation of the target compounds into their metabolites. The concentration of the main active substances (quizalofop-p-tefuryl, quizalofop-p-ethyl and propaquizafop) decreased during the degradation studies, whereas the concentration of quizalofop-p increased. DT50 of the main active substances ranged from 10 days to 70 days for most of the analytes, so it can be concluded that compounds are medium-high persistent in this matrix. Metabolites, such as PPA, CHHQ and CHQ, were detected in water samples after 7 days of the application of the commercial products at concentrations higher than their limits of quantification (> 0.1 µg/L). CHQ was detected at 1400 µg/L after 75 days of the application of quizalofop-p-ethyl commercial product. CHHQ and CHQ were found at the highest concentrations at 7-45 days after the application of quizalofop-p-tefuryl, whereas PPA was detected at higher concentrations (up to 5.37 µg/L) in propaquizafop samples.

QuEChERS approach for the determination of biopesticides in organic and nonorganic vegetables and fruits by ultra-performance liquid chromatography/tandem mass spectrometry.

A method for the determination of 14 biopesticides and piperonyl butoxide (PBO), often applied in organic farming, in vegetables and fruits has been developed. Extraction was performed using the Quick, Easy, Cheap, Effective, Rugged, and Safe method, and the determination was carried out by ultra-performance LC/MS/MS in 9 min. Several different food commodities were evaluated as representative matrixes, namely, cucumber, tomato, pepper (high water content), and strawberry and orange (high acid and water content). Biopesticides were quantified using matrix-matched calibration, and the optimized method was validated at three concentration levels, i.e., 10, 50, and 100 microg/kg, for all the compounds, yielding recoveries in the range 70-112%, 71-112%, and 70-109%, respectively, with RSDs <28%. LOQs were <3 microg/kg for all biopesticides. The validated procedure was applied to the analysis of vegetables and fruits, including products from organic farming; PBO was detected in one sample at 8 microg/kg.

Determination of quaternary ammonium compounds in oranges and cucumbers using QuEChERS extraction and ultra-performance liquid chromatography/tandem mass spectrometry.

A simple and fast method has been developed for determining relevant quaternary ammonium compounds in cucumber and orange samples. The target compounds were benzoalkonium chloride (BAC-10, BAC-12, BAC-14, and BAC-16), didecyldimethylammonium chloride, and benzethonium chloride, all frequently used biocides in the agrifood industry. An extraction based on the buffered Quick, Easy, Cheap, Effective, Rugged, and Safe method and determination by ultra-performance LC/MS/MS that eluted the biocides in less than 5 min were used. The method was fully validated and implemented in a UNE-EN-ISO/IEC 17025 accredited laboratory for its application to the analysis of real samples. Performance characteristics of the method are reported, including an estimation of measurement uncertainty. Calibration curves were set between 0.01 and 0.150 mg/kg, LOD values were always between 0.4 and 1.0 microg/kg, LOQ values were in the range 1-4 microg/kg, recovery was between 81 and 115%, intraday and interday precision were always lower than 17% (expressed as RSD), and expanded uncertainty was always lower than 40%. The validation was accomplished for the two studied matrixes at spiking concentrations of 0.011 and 0.050 mg/kg. The method has been applied to the analysis of 30 cucumber and orange samples that were found to contain concentrations of BAC-12 that ranged between 0.015 and 0.210 mg/kg and of BAC-14 between 0.018 and 0.081 mg/kg.

Determination of several families of phytochemicals in different pre-cooked convenience vegetables: effect of lifetime and cooking.

Phytochemicals content, including several families such as phenolic acids, isoflavones, flavones, flavonols, isothiocyanates, and glucosinolates, was determined in pre-cooked convenience vegetables by ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). It was observed that there is not a common behavior of the individual concentration of phytochemicals during the lifetime and cooking of the matrix, and compounds change their concentration without a specific trend. It was observed that neither lifetime nor cooking process have significant effects on the total content of phytochemicals except in broccoli, although some changes in the individual content of the target compounds were observed, suggesting that interconversion processes could be performed during the lifetime and/or cooking process of the product.

Osteoporosis in psoriatic arthritis: Risk factors, insufficiency fractures and its association with the disease activity.

OBJECTIVE: The prevalence of osteoporosis (OP) and insufficiency fractures in psoriatic arthritis (PsA) remains controversial. The aim of this study was to describe the prevalence of OP and insufficiency fractures in a representative cohort of patients with PsA, and to analyse its association with general risk factors and characteristics of the psoriatic disease in our geographical area. METHODS: Multi-centric, descriptive study of patients with PsA. We recorded clinical characteristics, as well as protective and risk factors for OP and insufficiency fractures. Hip and lumbar densitometry and lateral X-ray of the spine were evaluated. Descriptive statistics for OP and risk factors were calculated. The patients with OP were compared to those without by univariate analyses, and results were adjusted by age and sex. The association of OP and fractures with clinical characteristics was analysed by logistic regression. RESULTS: 166 patients (50 men; 116 women) were included. OP was present in 26.5%, and it was more frequent in women and patients above 50 years old. Insufficiency fractures occurred in 5.4% of the total sample. In the logistic regression, OP was associated with age over 50 [OR 3.7; 95% CI (1.2-11.6); p=.02]. No association with clinical parameters was found. The most frequent risk factors among patients with OP were vitamin D insufficiency, sedentary behaviour, low calcium intake, and active smoking. In the logistic regression, OP was associated with early menopause [OR 11.7; 95% CI (1.29-106.0); p=.029] and sedentary behaviour [OR 2.3; 95% CI (1.0-5.2); p=.049]. CONCLUSIONS: In patients with PsA, OP is more frequent in women and patients over 50 years old. A sedentary lifestyle and early menopause may add extra risk for OP. Type, duration disease, and treatments are not associated with OP or insufficiency fractures.

Topographic modification of the extracellular matrix precedes the onset of bladder cancer.

Background: Non-muscle invasive bladder cancer (NMIBC) patients are affected by a high risk of recurrence. The topography of collagen fibers represents a hallmark of the neoplastic extracellular microenvironment. Objective: Assess the topographic change associated with different stages of bladder cancer (from neoplastic lesions to bona fide tumor) and whether those changes favour the development of NMIBC. Design Setting and Participants: Seventy-one clinical samples of urothelial carcinoma at different stages were used. Topographic changes preceding tumor onset and progression were evaluated in the rat bladder cancer model induced by nitrosamine (BBN), a bladder-specific carcinogen. The preclinical model of actinic cystitis was also used in combination with BBN. Validated hematoxylin-eosin sections were used to assess the topography of collagen fibrils associated with pre-tumoral steps, NMIBC, and MIBC. Findings: Linearization of collagen fibers was higher in Cis and Ta vs. dysplastic urothelium, further increased in T1 and greatest in T2 tumors. In the BBN preclinical model, an increase in the linearization of collagen fibers was established since the beginning of inflammation, such as the onset of atypia of a non-univocal nature and dysplasia, and further increased in the presence of the tumor. Linearization of collagen fibers in the model of actinic cystitis was associated with earlier onset of BBN-induced tumor. Conclusions: The topographic modification of the extracellular microenvironment occurs during the inflammatory processes preceding and favoring the onset of bladder cancer. The topographic reconfiguration of the stroma could represent a marker for identifying and treating the non-neoplastic tissue susceptible to tumor recurrence.

Progressive alteration of murine bladder elasticity in actinic cystitis detected by Brillouin microscopy.

Bladder mechanical properties are critical for organ function and tissue homeostasis. Therefore, alterations of tissue mechanics are linked to disease onset and progression. This study aims to characterize the tissue elasticity of the murine bladder wall considering its different anatomical components, both in healthy conditions and in actinic cystitis, a state characterized by tissue fibrosis. Here, we exploit Brillouin microscopy, an emerging technique in the mechanobiology field that allows mapping tissue mechanics at the microscale, in non-contact mode and free of labeling. We show that Brillouin imaging of bladder tissues is able to recognize the different anatomical components of the bladder wall, confirmed by histopathological analysis, showing different tissue mechanical properties of the physiological bladder, as well as a significant alteration in the presence of tissue fibrosis. Our results point out the potential use of Brillouin imaging on clinically relevant samples as a complementary technique to histopathological analysis, deciphering complex mechanical alteration of each tissue layer of an organ that strongly relies on mechanical properties to perform its function.

Sex-specific impact of inflammation on traditional cardiovascular risk factors and atherosclerosis in axial spondyloarthritis. A multicentre study of 913 patients.

INTRODUCTION: The nature of the relationship between inflammation, cardiovascular (CV) risk factors and atherosclerosis in axial spondyloarthritis (axSpA) remains largely unknown and sex differences in this regard are yet to be assessed. METHODS: Study including 611 men and 302 women from the Spanish multicentre AtheSpAin cohort to assess CV disease in axSpA. Data on CV disease risk factors were collected both at disease diagnosis and at enrolment, and data on disease activity, functional indices and carotid ultrasonography only at enrolment. RESULTS: After a median disease duration of 9 years, patients of both sexes who at disease diagnosis had elevated acute phase reactants (APRs), more frequently had hypertension and obesity. The same occurred with dyslipidaemia in men and with diabetes mellitus in women. At enrolment, CV risk factors were independently associated with APR and with activity and functional indices, with various sex differences. C reactive protein (CRP) values were inversely associated with HDL-cholesterol in men (ß coefficient: -1.2 (95% CI: -0.3 to -0.07) mg/dL, p=0.001), while erythrocyte sedimentation rate values were positively associated with triglycerides in women (ß coefficient: 0.6 (95% CI: 0.04 to 1) mg/dL, p=0.035). Furthermore, only women showed an independent relationship between insulin resistance parameters and APR or disease activity. Both men and women with high-very high CV risk according to the Systematic Assessment of Coronary Risk Evaluation 2 and CRP levels higher than 3 mg/L at diagnosis of the disease presented carotid plaques significantly more frequently than those with normal CRP levels at disease diagnosis. CONCLUSION: Inflammation is associated with atherosclerosis and CV disease in axSpA. A gender-driven effect is observed in this relationship.

Childhood-Onset Non-Infectious Uveitis in the "Biologic Era". Results From Spanish Multicenter Multidisciplinary Real-World Clinical Settings.

OBJECTIVE: To characterize and describe clinical experience with childhood-onset non-infectious uveitis. STUDY DESIGN: A multicenter retrospective multidisciplinary national web-based registry of 507 patients from 21 hospitals was analyzed. Cases were grouped as immune disease-associated (IMDu), idiopathic (IDIu) or ophthalmologically distinct. Characteristics of juvenile idiopathic arthritis-associated (non-HLA-B27-related) uveitis (JIAu), IDIu, and pars planitis (PP) were compared. RESULTS: IMDu (62.3%) and JIAu (51.9%) predominated in young females; and IDIu (22.7%) and PP (13.6%) in older children, without sex imbalance. Ocular complications occurred in 45.3% of cases (posterior synechiae [28%], cataracts [16%], band keratopathy [14%], ocular hypertension [11%] and cystoid macular edema [10%]) and were associated with synthetic (86%) and biologic (65%) disease-modifying antirheumatic drug (DMARD) use. Subgroups were significantly associated (p < 0.05) with different characteristics. JIAu was typically anterior (98%), insidious (75%), in ANA-positive (69%), young females (82%) with fewer complications (31%), better visual outcomes, and later use of uveitis-effective biologics. In contrast, IDIu was characteristically anterior (87%) or panuveitic (12.1%), with acute onset (60%) and more complications at onset (59%: synechiae [31%] and cataracts [9.6%]) and less DMARD use, while PP is intermediate, and was mostly bilateral (72.5%), persistent (86.5%) and chronic (86.8%), with more complications (70%; mainly posterior segment and cataracts at last visit), impaired visual acuity at onset, and greater systemic (81.2%), subtenon (29.1%) and intravitreal (10.1%) steroid use. CONCLUSION: Prognosis of childhood uveitis has improved in the "biologic era," particularly in JIAu. Early referral and DMARD therapy may reduce steroid use and improve outcomes, especially in PP and IDIu.

Quality of life after transoral laser microresection of laryngeal cancer: a longitudinal study.

BACKGROUND AND METHODS: In the treatment of early to moderate laryngeal carcinoma, both, transoral laser surgery and radiation-based protocols have demonstrated good survival and preservation rates. In this scenario, quality of life (QOL) may become an important tool for treatment planning. We aimed to evaluate QOL changes after transoral laser microsurgery (TLM). Prospective longitudinal study. Ninety-three consecutive disease-free patients were evaluated using UW-QOL v4 and SF-12, before and 12 months after treatment. Changes over time were assessed according to age, gender, location, tumor size, and adjuvant treatment. RESULTS: UW-QOL improved from 1,051.5 ± 133.7 to 1,121.7 ± 92.1 (P = 0.000), suggesting that the impact of the treatment was favorable in most of the patients. Voice quality significantly improved after TLM, but speech was still the most important variable for 46% of the patients. Tumor location (P = 0.002) was an independent factor for preoperative total score of UW-QOL, whereas adjuvant radiation (P = 0.03) and neck dissection (P = 0.02), were the only postoperative negative factors. CONCLUSION: One year after TLM patients present a very good QOL. Relevant voice impairment is detected especially in locally advanced tumors, reinforcing the necessity of preoperative counseling and postoperative rehabilitation. Adjuvant radiotherapy and neck dissection negatively influenced disease-specific QOL.

Wide-scope analysis of veterinary drug and pesticide residues in animal feed by liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry.

A fast and generic method has been developed for the simultaneous monitoring of >250 pesticides and veterinary drugs (VDs) in animal feed. A 'dilute-and-shoot' extraction with water and acetonitrile (1% formic acid) followed by a clean-up step with Florisil cartridges was applied. The extracts were analysed by ultra-high performance liquid chromatography coupled to hybrid analyser quadrupole-time-of-flight mass spectrometry using both positive and negative electrospray ionisation. The detection of the residues was accomplished by retention time and accurate mass using an in-house database. The identification of the detected compounds was carried out by searching of fragment ions for each compound and isotopic pattern. The optimised method was validated and recoveries ranged from 60% to 120% at three concentrations (10, 50 and 100 µg kg(-1)) for 30%, 68% and 80% of compounds, respectively, included in the database (364) in chicken feed. Document SANCO 12495/2011 and Directive 2002/657/CE were used as guidelines for method validation. Intra-day and inter-day precisions, expressed as relative standard deviations, were lower than 20% for more than 90% of compounds. The limits of quantification ranged from 4 to 200 µg kg(-1) for most analytes, which are sufficient to verify compliance of products with legal tolerances. The applicability of the procedure was further tested on different types of feed (chicken, hen, rabbit and horse feed), evaluating recoveries and repeatability. Finally, the method was applied to the analysis of 18 feed samples, detecting some VDs (sulfadiazine, trimethoprim, robenidin and monensin Na) and only one pesticide (chlorpyrifos).

Analysis of veterinary drug residues in cheese by ultra-high-performance LC coupled to triple quadrupole MS/MS.

A simple, reliable, and fast multiresidue method has been developed for the determination of 17 veterinary drugs belonging to several families (macrolides, sulfonamides, and anthelmintics) in cheese at trace levels. Ultra-high-performance LC coupled to MS/MS has been used for the analysis of these compounds in less than 9 min. Veterinary drug residues have been extracted from cheese samples using a QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based extraction procedure without applying any further clean-up step. Matrix-matched calibration was used for quantification and recoveries were calculated at three concentration levels (10, 50, and 100 µg/kg). The obtained values ranged from 70 to 110% for the selected compounds except for tylosin and josamycin at 100 µg/kg (111.7 and 112.7%, respectively). Intra- and interday precision were also evaluated and RSDs were lower than 25% in all the cases. LOQs ranged from 0.3 µg/kg (for thiabendazole, oxfendazole, mebendazole, josamycin, and fenbendazole) to 10.5 µg/kg (abamectin), whereas decision limit and detection capability ranged from 2.3 (thiabendazole) to 11.3 (abamectin) and 4.2 (thiabendazole) to 14.3 µg/kg (abamectin), respectively. Finally, 13 samples were analyzed and traces of thiabendazole were detected in two different cheeses.

PepSeq: a fully in vitro platform for highly multiplexed serology using customizable DNA-barcoded peptide libraries.

PepSeq is an in vitro platform for building and conducting highly multiplexed proteomic assays against customizable targets by using DNA-barcoded peptides. Starting with a pool of DNA oligonucleotides encoding peptides of interest, this protocol outlines a fully in vitro and massively parallel procedure for synthesizing the encoded peptides and covalently linking each to a corresponding cDNA tag. The resulting libraries of peptide/DNA conjugates can be used for highly multiplexed assays that leverage high-throughput sequencing to profile the binding or enzymatic specificities of proteins of interest. Here, we describe the implementation of PepSeq for fast and cost-effective epitope-level analysis of antibody reactivity across hundreds of thousands of peptides from <1 µl of serum or plasma input. This protocol includes the design of the DNA oligonucleotide library, synthesis of DNA-barcoded peptide constructs, binding of constructs to sample, preparation for sequencing and data analysis. Implemented in this way, PepSeq can be used for a number of applications, including fine-scale mapping of antibody epitopes and determining a subject's pathogen exposure history. The protocol is divided into two main sections: (i) design and synthesis of DNA-barcoded peptide libraries and (ii) use of libraries for highly multiplexed serology. Once oligonucleotide templates are in hand, library synthesis takes 1-2 weeks and can provide enough material for hundreds to thousands of assays. Serological assays can be conducted in 96-well plates and generate sequencing data within a further ~4 d. A suite of software tools, including the PepSIRF package, are made available to facilitate the design of PepSeq libraries and analysis of assay data.