Efficient separation of organic anions in beverages using aminosilane-functionalized capillary electrophoresis with contactless conductivity detection.

BACKGROUND: Capillary electrophoresis (CE) has the advantage of rapid anion analysis, when employing a reverse electroosmotic flow (EOF). The conventional CE method utilizes dynamic coatings with surfactants like cetyltrimethylammonium bromide (CTAB) in the run buffer to reverse the EOF. However, this method suffers from very slow equilibration leading to drifting effective migration times of the analyte anions, which adversely affects the identification and quantification of peaks. Permanent coating of the capillary surface may obviate this problem but has been relatively little explored. Thus, permanent capillary surface modification by the covalent binding of 3-aminopropyltriethoxysilane (APTES) was studied as an alternative. RESULTS: This study investigates the effect of APTES concentration for surface functionalization on EOF mobility, separation efficiency, and reproducibility of anion separation. The performance data was complemented by X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The XPS measurements showed that the coverage with APTES was dependent on its concentration in the coating solution. The XPS measurements correlated well with the EOF values determined for the capillaries tested. A standard mixture of 21 anions could be baseline separated within 10 min in the capillaries with lower EOF, but not in the capillary with the highest EOF as the residence time of the analytes was too short in this case. Compared to conventional dynamic coating with CTAB, APTES-functionalized capillaries provide faster equilibration and long-term EOF stability. The application of APTES-functionalized capillaries in analyzing different beverages demonstrates the precision, reliability, and specificity in determining organic anions, providing valuable insights of their compositions. SIGNIFICANCE: APTES coating on capillaries provides a facile approach to achieve a permanent reversal of the stable EOF to determine anions. The control of the coverage via the concentration of the reagent solution allows the tailoring of the EOF to different needs, a faster EOF for less complex samples where resolution is not challenging, while a lower EOF for higher complex samples where the focus is on separation efficiency. This enhancement in efficiency and sensitivity has been applied to analyzing organic acids in several beverages.

A novel molecular assay conducted on the BD Max system to facilitate reflex testing for vanA and vanB in clinical isolates of enterococci.

Infections caused by vancomycin-resistant enterococci (VRE) are common. Real-time PCR assays targeting vanA and vanB facilitate screening of patients in healthcare settings to limit the risk of dissemination, especially amongst those at high-risk of infection or with limited treatment options. Such assays are commonly performed as reflex testing procedures where they augment phenotypic techniques and shorten turnaround time to benefit timely clinical management. 'Random access' and 'sample-to-result' real-time PCR platforms are suited for this application as they are of low complexity and less technically demanding. Modelled on these attributes, we configured a real-time PCR assay (VRE BD) for detection of vanA/B in clinical isolates of enterococci, adapted for the BD Max System (Becton Dickinson). We applied an unconventional approach by testing suspensions of microorganisms in water to circumvent the traditional pre-analytical genomic extraction process. Our objective of this study was to assess the performance of this assay for detection of VRE in cultures by validating against a traditional real-time PCR assay based on the LightCycler 2.0 platform (Roche, VRE RO). A high level of analytical sensitivity and specificity (≥99.0%) for both genes was obtained when testing suspensions derived from blood agar. Results for suspensions obtained from chromID VRE (Edwards Group) showed a similar level of performance for vanA detection (100%), but not for the vanB target (≥90.9%) where a lesser number of isolates were available for testing. However, our results for VRE detection in isolates from these media were repeatable and reproducible, and equated to positive and negative predictive values of ≥95.2% and ≥97.8%, respectively. Furthermore, the VRE BD assay was also able to accurately detect VRE in clinical and spiked BacT/ALERT (bioMérieux) blood cultures. Thus, the technical simplicity, short turnaround time and robustness of this high performing assay for VRE is suitable for reflex testing. In addition, the format developed for the BD Max platform has potential application for reflex testing other molecular targets of clinical importance.

Safety of a Novel Upper Esophageal Sphincter Balloon Dilator.

OBJECTIVE: The shape of esophageal dilators has not changed in over 350 years. Clinical and animal research suggests that the upper esophageal sphincter (UES) is not round but approximates a kidney shape and that cylindrical dilators may be suboptimal. The Infinity UES Dilation System has been developed specifically for the anatomic configuration of the UES. This study evaluates the safety of the UES-specific Infinity Dilation System. METHODS: All patients undergoing dilation of the UES between January 1, 2022 and September 1, 2023 were included. Demographics, procedure indication, dilator type, minor adverse events, and major complications were abstracted. Minor adverse events, complications, and maximum dilation dimension (mm) were compared between groups. RESULTS: A total of 477 patients were included. Eight hundred and seventy-three total UES dilations were performed. The primary indications for UES dilation were cricopharyngeus muscle dysfunction (43%) and stenosis from radiation toxicity (40%). Twenty-three percent (202/873) of dilations were performed with an Infinity balloon, 31% (270/873) were performed using two conventional balloons placed side by side, and 46% (401/873) were performed with one singleton conventional balloon. The average maximum dilation dimension was 33 (±4.7) mm for Infinity balloons, 32 (±3.8) mm for two side-by-side balloons, and 18 (±3.4) mm for singleton balloons. There were three major complications with conventional balloons and none with Infinity balloons. There were no significant differences in minor adverse events between groups. CONCLUSIONS: A UES-specific esophageal dilator provides a greater maximum dilation dimension and appears to be at least as safe as dilation with a single cylindrical balloon designed to dilate the esophagus. LEVEL OF EVIDENCE: Level 3 Laryngoscope, 2024.

Timing of follow-up visits after hospital discharge for COPD: Application of a new method.

RATIONALE: A common strategy to reduce COPD readmissions is to encourage patient follow-up with a physician within 1 to 2 weeks of discharge, yet evidence confirming its benefit is lacking. We used a new study design called target randomized trial emulation to determine the impact of follow-up visit timing on patient outcomes. METHODS: All Ontario residents aged 35 or older discharged from a COPD hospitalization were identified using health administrative data and randomly assigned to those who received and did not receive physician visit follow-up by within seven days. They were followed to all-cause emergency department visits, readmissions or death. Targeted randomized trial emulation was used to adjust for differences between the groups. COPD emergency department visits, readmissions or death was also considered. RESULTS: There were 94,034 patients hospitalized with COPD, of whom 73.5% had a physician visit within 30 days of discharge. Adjusted hazard ratio for all-cause readmission, emergency department visits or death for people with a visit within seven days post discharge was 1.03 (95% Confidence Interval [CI]: 1.01-1.05) and remained around 1 for subsequent days; adjusted hazard ratio for the composite COPD events was 0.97 (95% CI 0.95-1.00) and remained significantly lower than 1 for subsequent days. CONCLUSION: While a physician visit after discharge was found to reduce COPD events, a specific time period when a physician visit was most beneficial was not found. This suggests that follow-up visits should not occur at a predetermined time but be based on factors such as anticipated medical need.

Discovery of a Series of Orally Bioavailable Androgen Receptor Degraders for the Treatment of Prostate Cancer.

Androgen receptor (AR) signaling plays a key role in the progression of prostate cancer. This study describes the discovery and optimization of a novel series of AR PROTAC degraders that recruit the Cereblon (CRBN) E3 ligase. Having identified a series of AR ligands based on 4-(4-phenyl-1-piperidyl)-2-(trifluoromethyl)benzonitrile, our PROTAC optimization strategy focused on linker connectivity and CRBN ligand SAR to deliver potent degradation of AR in LNCaP cells. This work culminated in compounds 11 and 16 which demonstrated good rodent oral bioavailability. Subsequent SAR around the AR binding region brought in an additional desirable feature, degradation of the important treatment resistance mutation L702H. Compound 22 (AZ'3137) possessed an attractive profile showing degradation of AR and L702H mutant AR with good oral bioavailability across species. The compound also inhibited AR signaling in vitro and tumor growth in vivo in a mouse prostate cancer xenograft model.

Dysregulation of cholesterol homeostasis is an early signal of beta cell proteotoxicity characteristic of type 2 diabetes.

Type 2 diabetes (T2D) is a common metabolic disease due to insufficient insulin secretion by pancreatic beta cells in the context of insulin resistance. Islet molecular pathology reveals a role for protein misfolding in beta cell dysfunction and loss with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein co-expressed and co-secreted with insulin. The most toxic form of misfolded IAPP is intracellular membrane disruptive toxic oligomers present in beta cells in T2D and in beta cells of mice transgenic for human IAPP (hIAPP). Prior work revealed a high degree of overlap of transcriptional changes in islets from T2D and pre-diabetic 9-10-week-old mice transgenic for hIAPP with most changes being pro-survival adaptations and therefore of limited therapeutic guidance. Here we investigated islets from hIAPP transgenic mice at an earlier age (6 weeks) to screen for potential mediators of hIAPP toxicity that precede predominance of pro-survival signaling. We identified early suppression of cholesterol synthesis and trafficking along with aberrant intra-beta cell cholesterol and lipid deposits, and impaired cholesterol trafficking to cell membranes. These findings align with comparable lipid deposits present in beta cells in T2D and increased vulnerability to develop T2D in individuals taking medications that suppress cholesterol synthesis.

The Rheumatoid Arthritis Impact of Disease (RAID) Score in Telemedicine Management of Rheumatoid Arthritis.

The sudden and unanticipated emergence of SARS-Cov-2 at the beginning of the present decade, associated with high morbidity and mortality among people infected, prompted the rapid emergence of telemedicine approaches for the management of patients with rheumatoid arthritis (RA). The rationale was to limit the likelihood for viral contagion in a hospital outpatient setting for people rendered potentially more vulnerable by the immunosuppressive nature of many of the pharmacological interventions in the treatment armamentarium.

Advanced diffusion imaging reveals microstructural characteristics of primary CNS lymphoma, allowing differentiation from glioblastoma.

Background: Primary CNS lymphoma (PCNSL) and glioblastoma (GBM) both represent frequent intracranial malignancies with differing clinical management. However, distinguishing PCNSL from GBM with conventional MRI can be challenging when atypical imaging features are present. We employed advanced dMRI for noninvasive characterization of the microstructure of PCNSL and differentiation from GBM as the most frequent primary brain malignancy. Methods: Multiple dMRI metrics including Diffusion Tensor Imaging, Neurite Orientation Dispersion and Density Imaging, and Diffusion Microstructure Imaging were extracted from the contrast-enhancing tumor component in 10 PCNSL and 10 age-matched GBM on 3T MRI. Imaging findings were correlated with cell density and axonal markers obtained from histopathology. Results: We found significantly increased intra-axonal volume fractions (V-intra and intracellular volume fraction) and microFA in PCNSL compared to GBM (all P < .001). In contrast, mean diffusivity (MD), axial diffusivity (aD), and microADC (all P < .001), and also free water fractions (V-CSF and V-ISO) were significantly lower in PCNSL (all P < .01). Receiver-operating characteristic analysis revealed high predictive values regarding the presence of a PCNSL for MD, aD, microADC, V-intra, ICVF, microFA, V-CSF, and V-ISO (area under the curve [AUC] in all >0.840, highest for MD and ICVF with an AUC of 0.960). Comparative histopathology between PCNSL and GBM revealed a significantly increased cell density in PCNSL and the presence of axonal remnants in a higher proportion of samples. Conclusions: Advanced diffusion imaging enables the characterization of the microstructure of PCNSL and reliably distinguishes PCNSL from GBM. Both imaging and histopathology revealed a relatively increased cell density and a preserved axonal microstructure in PCNSL.

Putting the usability of wearable technology in forensic psychiatry to the test: a randomized crossover trial.

Introduction: Forensic psychiatric patients receive treatment to address their violent and aggressive behavior with the aim of facilitating their safe reintegration into society. On average, these treatments are effective, but the magnitude of effect sizes tends to be small, even when considering more recent advancements in digital mental health innovations. Recent research indicates that wearable technology has positive effects on the physical and mental health of the general population, and may thus also be of use in forensic psychiatry, both for patients and staff members. Several applications and use cases of wearable technology hold promise, particularly for patients with mild intellectual disability or borderline intellectual functioning, as these devices are thought to be user-friendly and provide continuous daily feedback. Method: In the current randomized crossover trial, we addressed several limitations from previous research and compared the (continuous) usability and acceptance of four selected wearable devices. Each device was worn for one week by staff members and patients, amounting to a total of four weeks. Two of the devices were general purpose fitness trackers, while the other two devices used custom made applications designed for bio-cueing and for providing insights into physiological reactivity to daily stressors and events. Results: Our findings indicated significant differences in usability, acceptance and continuous use between devices. The highest usability scores were obtained for the two fitness trackers (Fitbit and Garmin) compared to the two devices employing custom made applications (Sense-IT and E4 dashboard). The results showed similar outcomes for patients and staff members. Discussion: None of the devices obtained usability scores that would justify recommendation for future use considering international standards; a finding that raises concerns about the adaptation and uptake of wearable technology in the context of forensic psychiatry. We suggest that improvements in gamification and motivational aspects of wearable technology might be helpful to tackle several challenges related to wearable technology.

Delayed recruitment of activity-dependent bulk endocytosis in Fmr1 knockout neurons.

The presynapse performs an essential role in brain communication via the activity-dependent release of neurotransmitters. However, the sequence of events through which a presynapse acquires functionality is relatively poorly understood, which is surprising, since mutations in genes essential for its operation are heavily implicated in neurodevelopmental disorders. We addressed this gap in knowledge by determining the developmental trajectory of synaptic vesicle (SV) recycling pathways in primary cultures of rat hippocampal neurons. Exploiting a series of optical and morphological assays, we revealed that the majority of nerve terminals displayed activity-dependent calcium influx from 3 days in vitro (DIV), immediately followed by functional evoked exocytosis and endocytosis, although the number of responsive nerve terminals continued to increase until the second week in vitro. However, the most intriguing discovery was that activity-dependent bulk endocytosis (ADBE) was only observed from DIV 14 onwards. Importantly, optimal ADBE recruitment was delayed until DIV 21 in Fmr1 knockout neurons, which model Fragile X Syndrome (FXS). This implicates the delayed recruitment of ADBE as a potential contributing factor in the development of circuit dysfunction in FXS, and potentially other neurodevelopmental disorders.

What is the Utilization and Impact of Advanced Imaging for Tibial Tubercle Fractures? An Analysis of 598 Patients From the Tibial Tubercle Study (TITUS) Group.

BACKGROUND: Given the rare nature of tibial tubercle fractures, previous studies are mostly limited to small, single-center series. This results in practice variation. Previous research has shown poor surgeon agreement on utilization of advanced imaging, but improved evidence-based indications may help balance clinical utility with resource utilization. The purpose of this study is to quantify diagnostic practices for tibial tubercle fractures in a large, multicenter cohort, with attention to the usage and impact of advanced imaging. METHODS: This is a retrospective series of pediatric tibial tubercle fractures from 7 centers between 2007 and 2022. Exclusion criteria were age above 18 years, missing demographic and pretreatment data, closed proximal tibial physis and tubercle apophysis, or a proximal tibia fracture not involving the tubercle. Demographic and injury data were collected. Fracture classifications were derived from radiographic evaluation. The utilization of advanced imaging was recorded as well as the presence of findings not identified on radiographs. Standard descriptive statistics were reported, and χ2 tests were performed (means reported±SD). RESULTS: A total of 598 patients satisfied the inclusion criteria, of which 88.6% (530/598) were male with a mean age of 13.8±1.9 years. Internal oblique x-rays were obtained in 267 patients (44.6%), computed tomography (CT) in 158 (26.4%), and magnetic resonance imaging (MRI) in 64 (10.7%). There were significant differences in the frequency at which CT (7.2% to 79.4%, P<0.001) and MRI were obtained (1.5% to 54.8%, P<0.001). CT was obtained most frequently for Ogden type IV fractures (50/99, 50.5%), and resulted in novel findings that were not visualized on radiographs in a total of 37/158 patients (23.4%). The most common finding on CT was intra-articular fracture extension (25/37). MRI was obtained most frequently for Ogden type V fractures (13/35, 37.1%), and resulted in novel findings in a total of 31/64 patients (48.4%). The most common finding was patellar tendon injury (11/64), but only 3 of these patients required tendon repair. CONCLUSIONS: Substantial variation exists in the diagnostic evaluation of tibial tubercle fractures. CT was most helpful in clarifying intra-articular involvement, while MRI can identify patellar tendon injury, periosteal sleeve avulsion, or a nondisplaced fracture. This study quantifies variation in diagnostic practices for tibial tubercle fractures, highlighting the need for evidence-based indications for advanced imaging. LEVEL OF EVIDENCE: Level III.

Why are nH-perfluoroalkanoate ions more mobile than expected? Implications for identifying an emerging environmental pollutant.

nH-Perfluoroalkyl carboxylic acids (nH-PFCAs) are emerging pollutants. Their identification by ion mobility is frustrated by the nH-PFCAs having unexpectedly small collision cross sections (CCS). Theory and experiment agree that this is because nH-PFCA ions undergo internal hydrogen bridging, and this insight will help guide the creation of more accurate methods for pollutant identification.

The Global Experience of Laryngeal Transplantation: Series of Eleven Patients in Three Continents.

BACKGROUND: The loss of laryngeal function affects breathing, swallowing, and voice, thus severely compromises quality of life. Laryngeal transplantation has long been suggested as a solution for selected highly affected patients with complete laryngeal function loss. OBJECTIVE: To obtain insights regarding the advantages, weaknesses, and limitations of this procedure and facilitate future advances, we collected uniform data from all known laryngeal transplants reported internationally. METHODOLOGY: A case series. Patients were enrolled retrospectively by each institutional hospital or clinic. Eleven patients with complete loss of laryngeal function undergoing total laryngeal transplantation between 1998 and 2018 were recruited. RESULTS: After a minimum of 24 months follow-up, three patients had died (27%), and there were two graft explants in survivors, one total and one partial, due to chronic rejection. In the remaining cases, voice was functional in 62.5% and 50% achieved decannulation. Swallowing was initially restricted, but only one patient was gastrostomy-dependent by 6 months and all had normal or near-normal swallowing by the end of year two after transplantation. Median follow-up was 73 months. Functional (voice, swallowing, airway) recovery peaked between 12 and 24 months. CONCLUSIONS: Laryngeal transplantation is a complex procedure with significant morbidity. Significant improvements in quality of life are possible for highly selected individuals with end-stage laryngeal disorders, including laryngeal neoplasia, but further technical and pharmacological developments are required if the technique is to be more widely applicable. An international registry should be created to provide better quality pooled data for analysis of outcomes of any future laryngeal transplants. LEVEL OF EVIDENCE: IV Laryngoscope, 2024.

Patients with High Baseline Neutrophil-to-Lymphocyte Ratio Exhibit Better Response to Filgotinib as Treatment for Rheumatoid Arthritis.

INTRODUCTION: High baseline neutrophil-to-lymphocyte ratio (NLR) in rheumatoid arthritis (RA) has been associated with positive responses to biologic tumor necrosis factor inhibition and negative responses to conventional synthetic disease-modifying antirheumatic drug (csDMARD) triple therapy. Datasets from three randomized clinical trials in patients with RA were used to test the hypothesis that baseline NLR is associated with improved clinical response to filgotinib in methotrexate (MTX)-naïve or MTX-experienced RA populations. METHODS: Patients from FINCH 1 (inadequate response to MTX, MTX-IR; NCT02889796), FINCH 2 (inadequate response to biologic DMARDs; NCT02873936), and FINCH 3 (MTX-naïve; NCT02886728) were classified as baseline NLR-High or baseline NLR-Low based on a previously published cut point of 2.7. In total, 3365 patients were included across the three studies. Differences in clinical outcomes and patient-reported outcomes (PROs) were determined using linear-regression models. RESULTS: Control-arm patients (placebo + MTX/placebo + csDMARD) classified as NLR-High exhibited worse continuous clinical and PRO responses at week 12 across clinical trials compared to NLR-Low patients. In contrast, NLR-High patients who received FIL 200 mg + MTX/csDMARD exhibited consistently better responses after 12 weeks compared to NLR-Low patients across clinical trials, clinical endpoints, and PROs. These trends were most prominent among the MTX-IR population. CONCLUSION: The 2.7 baseline NLR cut point could be used to enrich for patients most likely to benefit from the addition of filgotinib to background MTX/csDMARD. Use of baseline NLR as part of therapeutic decision-making would not require additional diagnostics and could contribute to improved outcomes for patients with RA. TRIAL REGISTRATION: Clinicaltrials.gov: NCT02889796; NCT02873936; NCT02886728.

Rheumatoid arthritis is a disease that results in swollen and painful joints. There is currently no method to determine which treatment will work best for an individual patient. However, there may be identifying markers found in the blood that could indicate how a patient will respond to treatment. One of these possible markers is a ratio of two types of white blood cells, neutrophils and lymphocytes, which are part of the body's immune system and help the body detect and fight infection and other diseases. This ratio is referred to as the neutrophil-to-lymphocyte ratio. The current study evaluated whether the neutrophil-to-lymphocyte ratio at the beginning of treatment was associated with rheumatoid arthritis treatment outcomes. Blood test results were used from 3365 patients receiving filgotinib (a medicine used to treat rheumatoid arthritis) or other therapies as part of the FINCH clinical trials. Patients were classified as having a high or low neutrophil-to-lymphocyte ratio at the start of treatment. Patients receiving filgotinib over 24 weeks who had a high neutrophil-to-lymphocyte ratio showed less disease activity than patients whose ratio was low. This study provides support for the use of the neutrophil-to-lymphocyte ratio as a way to help determine whether a patient would benefit from filgotinib as part of their rheumatoid arthritis treatment and may help improve rheumatoid arthritis treatment outcomes.

The F-box protein FBXL-5 governs vitellogenesis and lipid homeostasis in C. elegans.

The molecular mechanisms that govern the metabolic commitment to reproduction, which often occurs at the expense of somatic reserves, remain poorly understood. We identified the Caenorhabditis elegans F-box protein FBXL-5 as a negative regulator of maternal provisioning of vitellogenin lipoproteins, which mediate the transfer of intestinal lipids to the germline. Mutations in fbxl-5 partially suppress the vitellogenesis defects observed in the heterochronic mutants lin-4 and lin-29, both of which ectopically express fbxl-5 at the adult developmental stage. FBXL-5 functions in the intestine to negatively regulate expression of the vitellogenin genes; and consistently, intestine-specific over-expression of FBXL-5 is sufficient to inhibit vitellogenesis, restrict lipid accumulation, and shorten lifespan. Our epistasis analyses suggest that fbxl-5 functions in concert with cul-6, a cullin gene, and the Skp1-related gene skr-3 to regulate vitellogenesis. Additionally, fbxl-5 acts genetically upstream of rict-1, which encodes the core mTORC2 protein Rictor, to govern vitellogenesis. Together, our results reveal an unexpected role for a SCF ubiquitin-ligase complex in controlling intestinal lipid homeostasis by engaging mTORC2 signaling.

Using de novo transcriptomes to decipher the relationships in cutthroat trout subspecies (Oncorhynchus clarkii).

For almost 200 years, the taxonomy of cutthroat trout (Oncorhynchus clarkii), a salmonid native to Western North America, has been in flux as ichthyologists and fisheries biologists have tried to describe the diversity within these fishes. Starting in the 1950s, Robert Behnke reexamined the cutthroat trout and identified 14 subspecies based on morphological traits, Pleistocene events, and modern geographic ranges. His designations became instrumental in recognizing and preserving the remaining diversity of cutthroat trout. Over time, molecular techniques (i.e. karyotypes, allozymes, mitochondrial DNA, SNPs, and microsatellite arrays) have largely reinforced Behnke's phylogenies, but have also revealed that some relationships are consistently weakly supported. To further resolve these relationships, we generated de novo transcriptomes for nine cutthroat subspecies, as well as a Bear River Bonneville form and two Colorado River lineages (blue and green). We present phylogenies of these subspecies generated from multiple sets of orthologous genes extracted from our transcriptomes. We confirm many of the relationships identified in previous morphological and molecular studies, as well as discuss the importance of significant differences apparent in our phylogenies from these studies within a geological perspective. Specific findings include three distinct clades: (1) Bear River Bonneville form and Yellowstone cutthroat trout; (2) Bonneville cutthroat trout (n = 2); and (3) Greenback and Rio Grande cutthroat trout. We also identify potential gene transfer between Bonneville cutthroat trout and a population of Colorado River green lineage cutthroat trout. Using these findings, it appears that additional groups warrant species-level consideration if other recent species elevations are retained.

tRNA modification profiling reveals epitranscriptome regulatory networks in Pseudomonas aeruginosa.

Transfer RNA (tRNA) modifications have emerged as critical posttranscriptional regulators of gene expression affecting diverse biological and disease processes. While there is extensive knowledge about the enzymes installing the dozens of post-transcriptional tRNA modifications - the tRNA epitranscriptome - very little is known about how metabolic, signaling, and other networks integrate to regulate tRNA modification levels. Here we took a comprehensive first step at understanding epitranscriptome regulatory networks by developing a high-throughput tRNA isolation and mass spectrometry-based modification profiling platform and applying it to a Pseudomonas aeruginosa transposon insertion mutant library comprising 5,746 strains. Analysis of >200,000 tRNA modification data points validated the annotations of predicted tRNA modification genes, uncovered novel tRNA-modifying enzymes, and revealed tRNA modification regulatory networks in P. aeruginosa . Platform adaptation for RNA-seq library preparation would complement epitranscriptome studies, while application to human cell and mouse tissue demonstrates its utility for biomarker and drug discovery and development.