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Microbial Cell Factories

Springer Science and Business Media LLC

Preprints posted in the last 7 days, ranked by how well they match Microbial Cell Factories's content profile, based on 27 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Structural mechanism defining product specificity in glycoside hydrolase family 66 cycloisomaltotetraose glucanotransferase

Yasukochi, R.; Kashima, T.; Mori, T.; Kawauchi, Y.; Miyanaga, A.; Watanabe, H.; Fushinobu, S.

2026-09-01 biochemistry 10.64898/2026.08.30.748175 medRxiv
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Cyclic oligosaccharides possess industrial advantages, including molecular encapsulation capability and high physicochemical stability, owing to the absence of a reducing end. Recently, a novel cyclic tetrasaccharide, cycloisomaltotetraose (CI4), consisting of four -1,6-linked glucose units, and the enzymes responsible for its synthesis, cycloisomaltotetraose glucanotransferases (CI4Tases), were discovered. Unlike known cycloisomaltooligosaccharide glucanotransferases (CITases) that yield a wide distribution of cyclic products with a degree of polymerization (DP) of 7 or higher, CI4Tases strictly produce CI4. To elucidate the molecular mechanism underlying this strict DP4 specificity, we determined the crystal structures of CI4Tase from Agreia sp. D1110, in its ligand-free form, as well as in complex with the linear hydrolysis product isomaltotetraose (IG4) and with CI4. Structural comparisons revealed that a loop (M247 to R251) blocks the region corresponding to the -5 subsite of typical CITases, narrowing the substrate-binding pocket. This "molecular ruler" mechanism ensures that only a glycan chain of exactly four glucose units is accommodated for cyclization. Among mutants of the residue positioned at the center of bound CI4, the formation of by-products other than CI4 was significantly suppressed in F245L, F245A, and F245W. While the cyclization activity of all F245 mutants decreased, the CI4 hydrolysis activity of these three mutants was also significantly reduced, resulting in an increased specificity for cyclic sugar production. These findings elucidate the strict size-control mechanism of CI4Tase and provide a structural foundation for engineering cycloisomaltooligosaccharide-producing enzymes with optimized transglycosylation efficiency and specificity for industrial applications.

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Burden of fatigue in compensated chronic liver disease: findings from the multinational a:GAP Study

Choudhuri, G.; Akhundova-Unadkat, G.; Naidoo, N.; Morales-Castillo, M.; Guillaume, X.; Duijnhoven, R. G.; Safaei, A.; Swain, M. G.

2026-09-02 gastroenterology 10.64898/2026.08.28.26361618 medRxiv
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Background & Aims: Fatigue is a central symptom of chronic liver disease (CLD), substantially impacting health-related quality of life (HRQoL). This study aimed to further understand CLD symptomatology, including fatigue, and its impact on HRQoL from a patient perspective. Methods: Abbott Global Assessment of Patients unmet needs (aGAP) was a multinational, cross-sectional survey in adults with compensated CLD in China, India and Mexico, conducted between July and November 2024. Adult participants who self-reported that they had physician-diagnosed CLD and were experiencing fatigue completed a quantitative survey to assess symptom burden and included three HRQoL patient-reported outcome (PRO) questionnaires (Patient-Reported Outcomes Measurement Information System [PROMIS]-29+2, Work Productivity and Activity Impairment - Specific Health Problem version 2.0 [WPAI: SHP], Multidimensional Fatigue Inventory [MFI]). Results: Overall, 505 participants (China: 200; Mexico: 105; India: 200) completed the study. Participants reported that their CLD-related fatigue sometimes, often or always affected their self-esteem/confidence (45.1%) and ability to maintain or acquire new employment (38.6%). Most participants reported moderate (51.3%) or serious (26.9%) fatigue, with 33.5% experiencing fatigue every day or almost every day. Many participants felt their social life was negatively impacted by their fatigue (47.3%) and that there were related financial difficulties (53.9%). Use of validated PRO tools demonstrated severe fatigue (MFI: overall mean [SD] 13.9 [3.4] general fatigue and 13.4 [3.6] physical fatigue) as well as substantial levels of work and activity impairment (WPAI: SHP overall mean [SD] 53.0 [26.4]) and high levels of anxiety, pain interference, depression and sleep interference (PROMIS T-scores [≥]54). Conclusions: Fatigue has a substantial impact on HRQoL among adults with CLD across several countries, highlighting a global unmet need for targeted interventions to effectively identify and manage the condition.

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Combined production of Non-Hemolytic Enterotoxin and Sphingomyelinase as a marker of diarrheal food poisoning strains in the Bacillus cereus group

de Freitas Cardoso, P.; Gilois, N.; Trinidade Vilas-Boas, G.; Lereclus, D.; Gohar, M.; Perchat, S.; Slamti, L.

2026-08-31 microbiology 10.64898/2026.08.27.747690 medRxiv
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The Bacillus cereus group comprises bacteria of biotechnological interest, but also raises health concerns. Some bacteria in this group are opportunistic human pathogens, mainly causing foodborne gastrointestinal infections. As of today, the presence, sequence variability, or expression of genes encoding toxins or other virulence factors are insufficient to predict the potential of a given isolate to cause the diarrheal form of the disease. To address this limitation, we developed a sandwich ELISA to quantify the NheA and Sphingomyelinase (SMase) proteins in culture supernatants to test them as markers of pathogenic potential. Application of the assay to a collection of B. cereus group isolates revealed that strains associated with food poisoning outbreaks produce significantly more NheA and SMase than those isolated from the environment or from commercial products. Statistical analyses show that the combined quantification of NheA and SMase provides robust discrimination between pathogenic and non-pathogenic (environmental and commercial) profiles. These results demonstrate that the quantitative assessment of both NheA and SMase production can serve as a reliable biomarker for distinguishing diarrheic food poisoning isolates from harmless strains.

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Receptor-binding domain 2 of Clostridioides difficile binary toxin as a promising vaccine component against C. difficile infection

Wang, S.; Heuler, J. S.; Nakanishi, Y.; Kim, H. B.; Sun, X.

2026-08-31 microbiology 10.64898/2026.08.30.748174 medRxiv
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Symptoms of Clostridioides difficile infection (CDI) are primarily caused by two major protein toxins, toxin A (TcdA) and toxin B (TcdB). In addition, approximately 5-30% of C. dif[fi]cile strains produce a third toxin, C. difficile binary toxin (CDT), which is has been associated with enhanced virulence and severe disease. CDT consists of an enzymatic component CDTa, and a binding and translocation component CDTb, which mediates the delivery of CDTa into host cells. CDTb contains two receptor-binding domains, RBD1 and RBD2. Recent structural studies suggest that RBD2 plays a critical role in the formation and stabilization of the di-heptameric CDTb assembly required for efficient intoxication of host cells. In this study, we evaluated the immunogenicity and protective potential of RBD1 and RBD2 using in silico, in vitro and in vivo approaches. Sequence analysis demonstrated that RBD2 is highly conserved among diverse CDT-producing C. difficile ribotypes and toxinotypes. Immunization of mice with RBD2, but not RBD1 conferred effective protection against direct CDT challenge. Moreover, RBD2 immunization protected hamsters against infection with a CDT-only-producing C. difficile strain (DSM 101085; TcdA-TcdB-CDT). Mechanistically, anti-RBD2 serum, but not anti-RBD1 serum, effectively neutralized CDT-mediated cytotoxicity, as demonstrated by inhibition of cell rounding in Vero cells. Collectively, these findings identify RBD2 as a promising vaccine antigen targeting CDT and provide functional evidence supporting its critical role in CDT-mediated host-cell intoxication. Incorporation of RBD2 into multivalent C. difficile vaccines may broaden protection against hypervirulent, CDT-producing strains.

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Two methylthio-alkane reductases are functionally distinct in the purple nonsulfur bacterium Rhodopseudomonas palustris

Marquez Reyes, N. L.; Arroyo-Carriedo, A. A.; North, J. A.; Fixen, K. R.

2026-08-31 microbiology 10.64898/2026.08.20.746119 medRxiv
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Organosulfur compounds are the predominant sulfur source in terrestrial environments, requiring bacteria to use enzymes for their assimilation. Most described organosulfur-assimilating enzymes require oxygen, and enzymes that function under anoxic conditions remain poorly understood. Recently, methylthio-alkane reductase (Mar), a nitrogenase-like enzyme that reduces the volatile organic sulfur compounds (VOSCs) methylthio ethanol (MT-EtOH), dimethyl sulfide (DMS), and ethyl methyl sulfide (EMS) under anoxic conditions, was identified in the purple nonsulfur bacterium Rhodospirillum rubrum. However, another purple nonsulfur bacterium, Rhodopseudomonas palustris, has three loci of nitrogen fixation-like (NFL) genes with high sequence similarity to Mar, suggesting additional Mar-like enzymes with distinct roles. Here, we tested whether these NFL genes are required for VOSC assimilation in R. palustris. RNA-seq analysis revealed that all three NFL loci are upregulated under sulfur limitation, supporting a role in sulfur assimilation. Only disruption of the NFL genes encoded by RPA2634-37, renamed marBHDK1, caused fitness defects with EMS, DMS, and dimethylsulfoniopropionate (DMSP) as sulfur sources, indicating a functional Mar enzyme. The NFL genes RPA2347-48 and RPA2353-54, renamed marKD2 and marHB2, were required for activity with MT-EtOH or ethanethiol but not DMS, EMS, or DMSP. No activity was observed for the third locus, RPA2363-64, renamed nflDK. Overall, two Mar homologs in R. palustris are capable of VOSC reduction, one specialized for simple VOSCs and the other preferring a substrate with an additional functional group.

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Site Specific Fluorescent Labeling via SpyTag SpyCatcher for Rapid Hybridoma Screening in Semi-Solid Medium

Guo, A.; Wei, M.; Wu, J.; Li, X.; Jiang, B.

2026-08-31 immunology 10.64898/2026.08.21.746134 medRxiv
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Hybridoma screening in semi-solid medium typically employs antigens labeled with visible fluorophores (e.g., FITC, AF488) to enable single-step identification of antibody-secreting clones. However, conventional chemical conjugation via NHS-esters or isothiocyanate groups frequently modifies lysine residues located within epitopes, potentially abrogating antibody recognition of these critical regions. Here, we describe a SpyTag SpyCatcher-based site-specific labeling strategy that circumvents epitope damage during semi-solid medium screening. A 16-amino-acid SpyTag was genetically fused to the C-terminus of the target antigen, enabling covalent conjugation to an sfGFP SpyCatcher fluorescent probe. In semi-solid medium supplemented with SpyTag-antigen and sfGFPSpyCatcher, positive hybridoma clones were readily identified by distinct fluorescent halos, whereas negative clones showed no detectable signal. Notably, the site-specific method yielded a significantly higher frequency of fluorescence-positive clones compared to the conventional AF488-labeled antigen method, suggesting that epitope preservation enhances screening recovery. Furthermore, this approach did not impair hybridoma growth or final clone positivity, offering a simple, rapid, and epitope-compatible method for monoclonal antibody screening.

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Biochemical and Binding Characterization of a Riboflavin Analogue Tethered to Biotin

Marincean, S.; Smith, S. R.; Branscum, T.; Ratajczak, A.; Benore, M. A.

2026-08-31 biochemistry 10.64898/2026.08.29.748002 medRxiv
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The binding affinities of a chimeric analog of a riboflavin derivative linked to biotin, (6- (7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)hexyl 5-((3aS,4S,6aR)-2- oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl)pentanoate), referred to as C6-Rf-biotin-tag, to the riboflavin binding retain or streptavidin are in the M range, 1.29 {+/-} 0.277 and 3.00 {+/-} 0.459, respectively. These values suggest that C6-Rf-biotin-tag has potential applications in diagnostic assay and labelling target flavin binding proteins. The C6-Rf-biotin-tag which was characterized with respect to physical and biochemical properties retains UV/Vis spectroscopic and fluorescence behavior similar to riboflavin.

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Effect of Mushroom-Bacteria Co-culture on Mushroom Growth and Antimicrobial Properties

Wang, E.; Cavanaugh, N. T.; He, Y.; Chai, Y.

2026-08-31 microbiology 10.64898/2026.08.30.747672 medRxiv
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Edible mushrooms have been reported to have antimicrobial properties and other health benefits. This study aims to test the antimicrobial activities of several edible mushrooms from markets and test if co-culturing them with bacteria could induce stronger anti-bacterial properties. Commercial mushrooms, Hericium erinaceus (lions mane), Pleurotus ostreatus (oyster mushroom), Lentinula edodes (Shiitake) and Agaricus bisporus (button mushroom), were grown from strictly controlled/sterile substrates. Ethanol and water extracts from the mushrooms were prepared and tested against the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, and the fungus Candida albicans for antimicrobial activities. Shiitake water extract (SWE) showed strong antibacterial effects against all tested bacterial species, inhibitory effects on their biofilms, and antifungal activity. The antimicrobials in SWE seem to damage the cell wall and cell membrane of the bacteria, prefer weak acidic conditions, and are heat labile. Some antimicrobials are likely proteins and polysaccharides. In contrast, 3 other mushrooms displayed only weak antimicrobial effects. The fast-growing lions mane and oyster mushroom were co-cultured with different bacteria. The co-cultivation promoted the fruiting body development of lions mane. Co-culturing with S. aureus increased the anti-bacterial effects of lions mane against S. aureus, E. coli and particularly B. subtilis. Co-culturing the oyster mushroom with bacteria, especially B. subtilis and P. aeruginosa, boosted the mushroom growth. All tested bacteria, especially S. aureus, increased oyster mushroom anti-bacterial effect against E. coli and B. subtilis. The findings indicate that mushroom-bacteria co-culturing could have benefits both agriculturally and medicinally.

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Defining the role of aerobic respiration in the metabolism and bioenergetics of Enterococcus faecalis

Paxie, O.; Nijagal, B.; Todd Rose, F. O.; Gastrell, S.; Su, S.; Saleh, A.; Grimshaw, J. W.; Rhee, K.; Strahl, H.; Cook, G. M.; Darnell, R. L.

2026-08-31 microbiology 10.64898/2026.08.30.748090 medRxiv
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Enterococcus faecalis is an opportunistic pathogen and facultative anaerobe that primarily relies on fermentative metabolism to colonize a wide range of aerobic and anaerobic environments. In the presence of exogenous heme, E. faecalis can assemble a minimal electron transport chain consisting of membrane-associated primary dehydrogenases, demethylmenaquinone, and the terminal cytochrome bd oxidase (CydAB). This respiratory chain is thought to generate a proton motive force to drive ATP synthesis via the F-type ATP synthase, thereby improving energy conservation under aerobic conditions. However, a cytosolic NADH oxidase (Nox) also consumes NADH and oxygen, potentially competing with the electron transport chain for reducing equivalents and terminal electron acceptors; but the relative physiological contributions of these two oxygen-reducing pathways remain poorly understood. To define the roles of CydAB and Nox under normoxic and hypoxic conditions, we constructed {Delta}cydAB and {Delta}nox mutants. Real-time, in situ measurements revealed {Delta}cydAB had no significant effect on oxygen utilization while in the {Delta}nox it was significantly reduced; revealing Nox as the major consumer of oxygen. Semi-untargeted metabolomic analysis further revealed oxidase-specific alterations in central metabolism with the {Delta}nox causing pronounced shifts in the ATP and NADH ratios; highlighting Nox as a key determinant of intracellular redox and energy homeostasis. Finally, single-cell fluorescence microscopy showed that membrane potential, a component of proton motive force, was substantially diminished only in the absence of both CydAB and Nox, or the F-type ATP synthase. These findings indicate that the F-type ATP synthase is a major generator of proton motive force, even upon aerobic growth, and demonstrate a complementary role for the electron transport chain and Nox in the bioenergetics of E. faecalis.

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Contrasting evolutionary trajectories of nitrate assimilation across Brettanomyces bruxellensis lineages

Vigna, A.; Harrouard, J.; Miot-Sertier, C.; Loegler, V.; Marullo, P.; Friedrich, A.; Schacherer, J.; Peltier, E.; Albertin, W.

2026-08-31 microbiology 10.64898/2026.08.31.748220 medRxiv
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Brettanomyces bruxellensis is a yeast species associated with diverse fermentation environments and characterized by extensive genetic diversity, including diploid, autotriploid, and allotriploid lineages resulting from independent hybridization events. These lineages are associated with distinct ecological niches and provide a framework for studying metabolic trait evolution in complex genomes. Nitrate assimilation is a relatively uncommon trait among yeasts and has been reported in B. bruxellensis, but its distribution and evolutionary history within the species remain poorly understood. Here, we combined phenotypic characterization of 151 strains with genomic analyses of 946 whole-genome sequences to investigate nitrate assimilation. Growth assays revealed that nitrate assimilation is widespread but unevenly distributed across genetic lineages, with some populations largely retaining the trait whereas others have frequently lost it. Genomic analyses identified extensive variation affecting the nitrate assimilation gene cluster composed of YNR1, YNI1, and YNT1. Nitrate assimilation was strongly associated with both gene copy number and predicted gene functionality, with nitrate-assimilating strains generally carrying more functional copies of the cluster. Leveraging the complex genomic architecture of the species, we independently analyzed primary and acquired genomes in allotriploid lineages and uncovered contrasting evolutionary trajectories following hybridization. While nitrate assimilation genes were generally maintained in primary genomes, acquired genomes showed a higher prevalence of gene loss and predicted loss-of-function variants, revealing asymmetric dynamics between subgenomes. Altogether, our results suggest that nitrate assimilation represents an ancestral trait that has been differentially maintained across B. bruxellensis lineages through a combination of copy number variation, gene degeneration, and genome-specific evolutionary dynamics. These findings provide new insights into how genome architecture and polyploid evolution shape the maintenance and loss of metabolic traits in an industrially relevant yeast species.

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Epidemiology, Temporal and Seasonal Trends, and Geographic Distribution of Leptospirosis in the Dominican Republic, 2012 to 2026

Alcantara, L. V.; Sanchez, J. J.; De Luna, D.; Aleuy, O. A.; Miller, B.; Mace, C.; Scott, H.; Smejkal, L.; Cruz Raposo, J. L.; Hennekens, C.; Dye, T. D. V.

2026-09-04 infectious diseases 10.64898/2026.09.02.26362038 medRxiv
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Leptospirosis is a widespread zoonotic infection and a growing public health concern in tropical, resource-limited settings, yet remains underrecognized and underreported where diagnostic and surveillance infrastructure is limited. We conducted an analytical cross-sectional study of national surveillance data from the Dominican Republic (2012-June 2026), integrating geospatial meteorological data to characterize disease burden, trends, seasonality, and clinical risk factors. Of 8,425 records, 5,412 met case-definition criteria (3,441 suspected, 1,448 probable, 523 confirmed), yielding a cumulative incidence of 3.55 per 100,000 person-years (2012-2025). Laboratory confirmation rose markedly, from 9.7% overall to half of 2025 cases and over half in 2026. Overall incidence remained stable across all years (p = 0.15), though with three distinct periods: declining infection pre-COVID, low infection during COVID, and increasing infection post-COVID. Cases clustered in the rainy/hurricane season (61.1%, May-November; p< 0.001), with a marginal rainfall correlation (r= 0.553, p= 0.062). Rural provinces bore disproportionate risk, led by Hermanas Mirabal (16.43/100,000 person-years), while large urban and coastal provinces had rates 80% lower. Men had 2.73-fold higher incidence than women (95% CI 2.56-2.90), peaking at younger ages 10-29. Comorbidity was the strongest predictor of complications (OR 2.84, 95% CI 2.01-4.02, p< 0.001). Limited diagnostic confirmation remains the central obstacle to characterizing leptospirosis burden in the Dominican Republic, with confirmation rates exceeding 40% only from 2023 onward. This first multi-decade national analysis identifies high-risk provinces, demographic groups, and seasonal windows for targeted surveillance, highlighting expanded diagnostic capacity as a priority for burden estimation and case management.

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Validation of the Brief-Cope Questionnaire in a Seropositive Rheumatoid Arthritis Population

Iliadis, I.; Heitland, I.; Hoeper, K.; Witte, T.; Kahl, K. G.; Stapel, B.; Meyer-Olson, D.

2026-09-02 rheumatology 10.64898/2026.08.28.26361589 medRxiv
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Objective: The Brief-cope questionnaire explore coping behavior. However, the underlying factor structure remains a subject of ongoing debate. Exploratory factor analyses (EFA) conducted across different populations have identified factor solutions ranging from two to fourteen factors. As of yet, the underlying factor structure of the Brief-cope has not been investigated in patients with seropositive rheumatoid arthritis (RA). Therefore, the aim of this study was to explore the underlying factor structure of the Brief-cope in a German population of seropositive RA. Methods: 216 outpatients with seropositive RA completed the Brief-cope. An EFA with principal axis factoring and Promax rotation was conducted. Results: EFA indicated a five-factor solution. The five-factor solution explained 51.95% of variance. The identified factors were: (1) problem-focused coping (Cronbach's = .851), (2) emotion-focused coping ( = .754), (3) maladaptive coping ( = .747), (4) religious coping ( = .851), and (5) substance-use coping ( = .869). Conclusion: A five-factor solution provided the most appropriate representation of the underlying factor structure of the Brief-cope in patients with seropositive RA. This factor structure may serve as a suitable basis for future analyses of Brief-cope data in comparable RA populations.

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GLP-1/GIP Uptake, Indication, and Access Pathways Among US Adults in the Understanding America Study

Chaturvedi, R. R.; Gracner, T.; Perez-Arce, F.; Suen, S.-c.; Jin, J.; Orriens, B.; Pacula, R. L.; Sexton Ward, A.; Haile, R.; Kapteyn, A.

2026-09-02 endocrinology 10.64898/2026.08.28.26361368 medRxiv
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Importance: Evidence on GLP-1/GIP therapies is largely derived from trials enrolling selected populations or medical records that miss utilization outside healthcare channels. No nationally representative cohort has characterized real-world uptake, indications, and access. Objective: To characterize GLP-1/GIP prevalence, indication, clinical profile, and access. Design: Prospective cohort study with three GLP-1/GIP surveillance waves (March 2024, December 2024, October 2025). Setting: The Understanding America Study, an address-based, nationally representative panel of approximately 15,000 US adults aged 18+ years initiated in 2014. Participants: UAS participants responding to at least one surveillance wave (n=9150). Exposures: GLP-1/GIP use status (never vs any use, comprising current and former use), self-reported primary indication (diabetes, weight loss, or other), and access pathway (traditional vs non-traditional). Main Outcomes and Measures: Survey-weighted prevalence of GLP-1/GIP use, overall and by indication and access pathway; sociodemographic, cardiometabolic, treatment, and access characteristics; and smartwatch-derived resting heart rate, heart rate variability, maximum activity heart rate, step count, and sleep duration and variability. Results: Among n=9150 adults (1274 with any use; 60.9% female; median age 53 years), weighted prevalence increased 46%, from 8.2% (March 2024) to 12.0% (October 2025) representing 32 million. Weight-loss indications grew, reaching nearly half of use (4.1% to 5.6%); diabetes-indicated use was stable (5.3% to 5.4%). Users carried high cardiometabolic burden (obesity, 68.2%; diabetes, 53.6%) but diverged by indication: diabetes-indicated users were older (median, 59 vs 49 years), whereas weight-loss-indicated users were more often female (69.9% vs 51.3%) and healthier. One in three users (~9 million) had non-traditional access, especially in weight-loss-indicated users, of whom 33% had no conventional prescription; 41% used compounding, online, or foreign pharmacies; and, 43% lacked coverage. Non-traditional users were five times as likely to report an unlisted, likely compounded formulation (19.8% vs 4.1%). All p<0.05. Conclusions and Relevance: Real-world GLP-1/GIP use has grown rapidly and diversified substantially in indication, access, and population profile. One in 3 users obtained treatment through nontraditional channels largely invisible to claims data, raising long-term safety, efficacy, and coverage questions. GLIMMER provides a public, nationally representative longitudinal evidence base for future payer and provider decisions.

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An interpretable, formally verified point-of-care ultrasound risk equation for difficult videolaryngoscopy: development and internal validation

Oyarzun-Silva, R. A.; Hernandez-Hernandez, P.; Fernandez-Vaquero, M. A.; De Luis-Cabezon, N.

2026-09-02 anesthesia 10.64898/2026.08.28.26361621 medRxiv
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Background. Videolaryngoscopy still requires adjuncts or hyperangulated rescue in a clinically important minority, and bedside screening discriminates modestly. Point-of-care ultrasound (POCUS) of the anterior airway is a promising alternative, but existing prediction models are opaque or assume a pre-specified functional form. We developed and internally validated a parsimonious, fully disclosed POCUS risk equation whose form is recovered from data and whose structural properties are machine-checked by formal proof - to our knowledge the first formally verified clinical risk predictor - following TRIPOD+AI 2024. Methods. In a prospective single-centre, single-operator cohort of 259 adults undergoing elective videolaryngoscopy (no-Easy airway 68/259, 26.3%), Sequentially Thresholded Least Squares with bootstrap stability selection (B=300) screened a 71-term library of nine POCUS features and retained a seven-term logistic equation; a two-term bootstrap-stable model was pre-specified as robustness analysis. Internal validation used 5x10 repeated cross-validation plus temporal and device hold-outs, with pre-specified overfitting and optimism assessments. Five behavioural properties of the deployed equation were machine-checked in Lean 4. Results. Two interactions met the |c|/sigma_c>2 stability criterion: skin-to-epiglottis x skin-to-hyoid-bone distance and tongue volume x sagittal tongue area. The seven-term equation reached a 5x10 cross-validated C-statistic of 0.966 (optimism-corrected 0.968) and held across temporal and device hold-outs (0.94-0.97). Calibration-in-the-large matched prevalence, with cross-validated slope 0.90 attenuating to 0.625 out-of-time; standard recalibration restored 0.92 without loss of discrimination. The pre-specified two-term robustness model reproduced this performance (C-statistic 0.964-0.968; events-per-parameter 34; shrinkage 0.99), confirming the result is not an artefact of the screening stage. Net benefit over a clinical baseline was positive across 10-50% thresholds. All five Lean 4 theorems compiled without sorry. Conclusions. A sparse, formally verified POCUS equation predicts difficult videolaryngoscopy with high internally validated discrimination and quantified, modest overfitting. Because the equation was developed in a single-operator cohort and its inputs are operator-dependent, external validation requires prior harmonisation of the measurement protocol and operator credentialing.

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Glaucoma and Diabetes Mellitus: A Comparative Evaluation of Comorbid Effect on Tear Quantity among Patients in Owerri, Imo State, Nigeria.

Chukwuoha, C. M.; Ovenseri-Ogbomo, G.; Azuamah, Y. C.; Odimegwu, N. E.; Obioma-Elemba, J. E.; Ugwoke, G.; Nkeremuzor, E. C.; Eronini, Y.; Ikoro, N. C.; Esenwah, E. C.

2026-09-02 ophthalmology 10.64898/2026.08.30.26361782 medRxiv
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Abstract Objective: Glaucoma is a chronic disorder that impairs ocular health and may exacerbate ocular surface disease leading to tear film instability, dry eye symptoms and decreased quality of life. This study compared changes in tear quantity among glaucoma subjects living with and without diabetes mellitus, attending an eye clinic in Nigeria. Methods: A comparative cross sectional research design was used. 157 subjects which comprised 74 glaucoma subjects living with diabetes mellitus and 83 glaucoma subjects living without diabetes mellitus participated in the study. Tear quantity assessment included the Schirmer I test and tear meniscus height (TMH) measurement. Descriptive statistics, independent samples t-test and Chi-square test were used to examine the data at 0.05 level of significance. Results: Glaucoma subjects living with diabetes mellitus showed substantially decreased tear production (11.4 +/- 6.8 mm) compared with glaucoma subjects living without diabetes mellitus (19.6 +/- 9.6 mm; p < 0.001). Tear meniscus height in glaucoma subjects living with diabetes mellitus (0.8 +/- 0.3 mm) was significantly greater than in subjects living without diabetes mellitus (0.7 +/- 0.3 mm; p = 0.034). Conclusion: Diabetes mellitus dramatically deteriorates the ocular surface function in glaucoma subjects by decreasing tear production, altering the tear meniscus height and increasing the severity of ocular surface symptoms. Routine glaucoma care, especially in patients with diabetes mellitus, should include a full ocular surface evaluation including Schirmer I test, TBUT, TMH, and OSDI assessment to allow early detection and management of ocular surface disease, better treatment adherence, and improved visual outcomes. Keywords: Glaucoma, Diabetes Mellitus, Tear production, Tear Meniscus Height, Ocular Surface Disease.

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Very low-calorie diet reduces hepatic steatosis and remodels circulating metabolite-microRNAs networks in metabolic dysfunction-associated steatotic liver disease: A pilot study

Deb, P.; Bagar, D.; Kumar, P.; Sun, L.; Chen, E.; Gaddam, R. R.; Ferretto, L. F.; Shelsky, C. R.; Sanchez, A. J.; Thakkar, H.; Chaurasia, B.; Vikram, A.; Correia, M. L. D.

2026-09-04 endocrinology 10.64898/2026.09.01.26361664 medRxiv
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Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major cause of chronic liver disease, with weight loss as the pivotal therapeutic strategy. However, the metabolic and molecular adaptations underlying rapid weight loss remain incompletely defined. In this pilot study, women with obesity and MASLD but without diabetes consumed a very low-calorie diet (VLCD) for 8 weeks. Clinical parameters, hepatic steatosis measured by controlled attenuation parameter (CAP), circulating metabolites, and microRNAs (miRs) were assessed before and after the dietary intervention. Integrated correlation and hierarchical clustering analyses were performed to identify molecular networks associated with clinical improvement. VLCD was well tolerated, resulting in significant weight loss (~11%) with ~80% adherence. Significant improvements in metabolic parameters were observed, including fat mass, waist circumference, blood pressure, insulinemia, HOMA-IR, HbA1c, and triglycerides, with unchanged liver enzymes. Hepatic steatosis decreased markedly, as indicated by a reduction in CAP, while stiffness remained unchanged. Metabolomic profiling revealed elevated ketone bodies and broad reductions in amino acid levels, consistent with enhanced fatty acid oxidation and a catabolic metabolic state. Correlation analysis identified distinct metabolite signatures associated with hepatic steatosis, with changes in CAP positively associated with changes in amino acids and inversely associated with changes in ketone bodies and tricarboxylic acid cycle intermediates. Circulating miRs underwent selective rather than global remodeling, with only a limited subset showing strong associations with clinical parameters, including CAP and HOMA-IR. Specifically, VLCD altered the circulating levels of miR-148a-3p, miR-140-3p, miR-10b-5p, and miR-345-5p. Integration of metabolomic and miR datasets identified coordinated metabolite-miR modules involving glucose metabolism, branched-chain amino acid catabolism, mitochondrial metabolism, purine metabolism, microbial metabolites, and cellular redox pathways. These findings demonstrate that improvement in hepatic steatosis during VLCD-induced weight loss is accompanied by coordinated remodeling of circulating metabolite-miR networks. Integrated multi-omics analysis identifies candidate molecular signatures associated with metabolic adaptation and highlights circulating miR-metabolite modules as potential biomarkers of therapeutic response in MASLD.

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Non-inferior survival and enhanced longevity with initial low-dose versus full-dose enzalutamide: a single-centre real-world prostate cancer study

Gorobets, O.; Vinh-Hung, V.

2026-09-02 oncology 10.64898/2026.08.28.26361616 medRxiv
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Background: Prostate cancer enzalutamide treatment is approved at a standard dose of 160 mg daily. Concerns for real-world patients -- older and more fragile than those enrolled in clinical trials -- have prompted consideration of initiating treatment with lower doses, but the long-term efficacy of this approach remains unknown. We evaluate the long-term survival and longevity in patients treated with standard versus upfront low-dose enzalutamide. Methods: Retrospective analysis of 151 patients treated with enzalutamide (102 receiving 160 mg; 49 receiving [&le;]80 mg) between 2014--2021 at the Centre Hospitalier Universitaire de Martinique, with complete follow-up through end of life (98.7% completeness of follow-up). Primary outcomes were overall survival (OS), progression-free survival (PFS), and longevity (attained age). Results: Doses [&le;]80 mg were associated with longer median OS (36.3 vs. 20.7 months), improved restricted mean OS (difference of 0.7 years, p=0.05), and enhanced longevity (median 82.5 vs. 78.3 years, p=0.004). PSA response rate at 12 weeks was higher with lower-dose (71.4% vs. 48.8%, p=0.016). In multivariable models adjusted for prognostic factors, [&le;]40 mg compared with 160 mg was non-inferior regarding OS (HR=0.61, 95% CI 0.36--1.06), superior regarding PFS (HR=0.59, 95% CI 0.35--0.99), and superior regarding longevity (HR=0.48, 95% CI 0.28--0.84). Bone metastasis, poor performance status, PSA response, time to PSA nadir, and disease duration were independent predictors of outcomes. A post-hoc analysis revealed a strong association between dose and physician-prescribing profiles, ranging from "endorse-lowest-dose" to "never-deviate-from-full-dose". Conclusions: Lower doses of enzalutamide were non-inferior to full-dose. Dose-adapted strategies warrant further investigation.

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Maternal cell-free RNA versus combined screening for first-trimester prediction of early-onset preeclampsia: a nested case-control study

Satorres-Perez, E.; Castillo-Marco, N.; Igual, M.; Cordero, T.; Munoz-Blat, I.; Monfort-Ortiz, R.; Marcos-Puig, B.; Simon, C.; Garrido-Gomez, T.; Perales-Marin, A.

2026-09-02 obstetrics and gynecology 10.64898/2026.08.28.26361628 medRxiv
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Background. In Europe, first-trimester combined screening with the Fetal Medicine Foundation (FMF) algorithm identifies women at increased risk of preeclampsia who may benefit from personalized aspirin prophylaxis. However, a substantial proportion of early-onset preeclampsia (EOPE) remains undetected at clinically acceptable specificity. Objective. To evaluate the first-trimester performance of MaiRa for early-onset preeclampsia (EOPE) risk stratification by benchmarking it against FMF screening in the same women, characterizing discordant patient-level classification profiles and exploring potential implementation strategies. Study Design. This secondary case-control analysis was nested within the prospective, multicentre PREMOM cohort [NCT04990141], which enrolled women with singleton pregnancies across 14 tertiary hospitals in Spain. First-trimester MaiRa and FMF risk estimates were evaluated in the same 126 pregnant women, comprising 99 uncomplicated controls and 27 EOPE cases, defined by disease onset before 34 weeks. Discrimination was compared using a stratified paired bootstrap analysis of the areas under the receiver-operating-characteristic curves. Performance was assessed at prespecified clinical thresholds, and detection rates were evaluated at fixed false-positive rates. Universal and contingent MaiRa implementation strategies were also evaluated. Results. MaiRa showed greater first-trimester discrimination for EOPE than FMF combined screening (AUC, 0.974 vs 0.900; P=.040) and consistently achieved higher detection rates across fixed false-positive rates. At false-positive rates of 5% and 10%, MaiRa detected 85.2% and 92.6% of EOPE cases, compared with 44.4% and 70.4% for FMF, respectively. Patient-level analysis demonstrated that MaiRa identified 12 of 27 EOPE cases (44.4%) classified as low risk by FMF; these pregnancies generally exhibited less abnormal conventional first-trimester profiles, including fewer maternal risk factors, lower mean arterial pressure and lower uterine artery pulsatility index, yet 8 of 12 (66.7%) subsequently developed severe EOPE. Exploratory implementation analyses showed that universal MaiRa screening achieved the highest EOPE detection, whereas a contingent strategy using FMF for triage and reflex MaiRa testing reduced molecular testing to 35.7% of pregnancies while maintaining 77.8% sensitivity and 97.0% specificity. Conclusion. MaiRa provided greater first-trimester discrimination for EOPE than conventional combined screening and detected additional pregnancies that later developed severe disease despite less abnormal conventional screening profiles. The findings suggest that maternal plasma cfRNA profiling captures biological alterations not fully reflected by combined first-trimester screening and support further prospective evaluation in an independent, unselected obstetric population. Key words: early-onset preeclampsia; first-trimester screening; cell-free RNA; liquid biopsy; Fetal Medicine Foundation algorithm; combined screening; risk stratification; aspirin prophylaxis.

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Measuring Positive Stress Appraisal Among Nursing Students: Development and Psychometric Evaluation of the Nursing Student Positive Stress Scale (NSPSS)

Yan, H.; O'Brien, A. J.; Yoon, S. H.; Shaw, V.; vakavosaki, k.

2026-09-02 nursing 10.64898/2026.08.30.26361779 medRxiv
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Background: Stress research in nursing education has largely focused on distress, stressors, and negative outcomes, although challenging experiences may also support motivation, confidence, learning, and growth when appraised positively. Objective: To develop and evaluate the psychometric properties of the Nursing Student Positive Stress Scale (NSPSS). Design: A methodological instrument development and psychometric evaluation study. Methods: The NSPSS was developed using a deductive, theory-driven approach informed by the transactional theory of stress and coping and positive psychology perspectives. Content validity was assessed by an international nursing expert panel. Psychometric evaluation used national survey data from nursing students in New Zealand. Of 539 responses, 507 were analysed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were conducted using separate subsamples. Internal consistency was assessed using Cronbach's alpha and McDonald's omega, and convergent validity through correlation with Perceived Stress Scale-10 scores. Results: Content validity was strong (I-CVI = .88-1.00; S-CVI/Ave = .975; S-CVI/UA = .800). EFA identified a dominant factor explaining 41.38% of variance (loadings = .528-.735). CFA supported a two-context Academic and Clinical Positive Stress model with correlated residuals between five parallel item pairs, chi-square(29) = 60.49, CFI = .970, TLI = .954, RMSEA = .063, SRMR = .065. Internal consistency was good (alpha = .839; omega = .843). NSPSS scores correlated negatively with PSS-10 scores (r = -.298, p < .001). Conclusion: The NSPSS demonstrated strong content validity, preliminary evidence of structural and convergent validity, and good internal consistency reliability for assessing positive stress appraisal among nursing students. Further validation in independent samples is warranted.

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Cross-System Meta-Analysis of Machine Learning Predictors Identifies Value-Specific Risk Drivers and Interactions Underlying Acute Kidney Injury

Chan, H. Y.; Li, D.; Yu, A. S. L.; Kellum, J. A.; Fuhrman, D. Y.; Xu, Q.; Chrischilles, E. A.; Cowell, L. G.; Chandaka, S.; Anzalone, A. J.; Kean, J.; McTigue, K. M.; Mosa, A. S. M.; Taylor, B.; Syed, M.; Waitman, L. R.; Hu, Y.; Liu, M.

2026-09-02 nephrology 10.64898/2026.08.31.26361849 medRxiv
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Background: Current understanding of acute kidney injury (AKI) risk factors remains largely descriptive, offering limited precision into how specific biomarker values or physiologic thresholds influence susceptibility. We aimed to synthesize knowledge from machine learning models trained across multiple health systems to identify generalizable, value-specific risk drivers and biomarker interactions contributing to AKI risk. Methods: We analyzed electronic health records (EHRs) from 785,497 adult inpatients between 2010 and 2019 across nine U.S. academic medical centers within PCORnet. Interpretable gradient boosting machine models were independently developed at each health system to quantify predictor-outcome associations. Meta-regression was applied to integrate these site-level results, characterize nonlinear value-risk relationships, and identify bivariate interactions between predictors. Results: Meta-analysis revealed consistent, value-specific risk drivers across health systems. An increase in glucose from 100 mg/dL to 140 mg/dL was associated with a 1.46-fold higher risk of AKI. Chloride and anion gap also demonstrated elevated AKI risk with risk increases overlapping portions of their reference ranges, with anion gap showing a 1.14-fold increase across 4-12 mmol/L and chloride a 1.28-fold increase across 96-100 mEq/L. Electrolytes including potassium, calcium, and sodium showed quadratic associations with AKI risk. Bivariate meta-regression identified interactions between key predictors, highlighting pathways that jointly modulate AKI risk. Conclusion: This cross-system meta-analysis synthesizes machine learning-derived evidence into clinically interpretable knowledge, revealing how specific biomarker ranges and interactions modulate AKI risk. By moving beyond surface-level associations to quantitative, generalizable physiologic thresholds, these findings provide actionable insights to enhance risk stratification and personalized prevention in hospital care.