Open Air Scholar

Design:

A retrospective cohort study analyzed 470 candidemia cases (229 pre-pandemic, 241 pandemic) from two tertiary hospitals. Data included patient demographics, clinical characteristics, antifungal susceptibility test results, treatment regimens, and 30-day mortality. Comparisons were made using incidence rate ratios (IRR) and multivariate logistic regression.

Procedures:

Clinical data were extracted from electronic medical records. Antifungal susceptibility was tested via broth microdilution. Statistical analyses assessed changes in species distribution, resistance rates, treatment trends, and mortality. Risk factors for mortality were identified using multivariate analysis.

Primary Findings:

The overall candidemia incidence remained stable (IRR 1.15; p=0.13), but ICU-associated cases increased significantly (IRR 1.50; p<0.01). Candida albicans remained the most common species (39.7% vs. 47.7%), followed by C. glabrata (17.2% vs. 20.3%). Fluconazole non-susceptibility in C. albicans dropped sharply (10.0% to 0.9%; p<0.01), while caspofungin non-susceptibility in C. glabrata rose from 0% to 22.4% (p<0.01). Echinocandin use as initial therapy increased (21.8% to 34.4%), while fluconazole use declined (48.0% to 32.8%). Mortality remained high (57.2% vs. 60.2%; p=0.57).

Secondary Findings:

Multivariate analysis identified mechanical ventilation and parenteral nutrition as risk factors for 30-day mortality. Protective factors included recent surgery, C. parapsilosis infection, and fluconazole treatment. Global trends from supplementary studies highlighted pandemic-driven increases in fluconazole-resistant species, higher medical costs, and elevated mortality in co-infected patients.

Interpretation:

The pandemic’s surge in ICU admissions likely drove the rise in ICU-associated candidemia. Reduced fluconazole resistance in C. albicans may reflect decreased azole exposure due to altered prescribing practices, while increased caspofungin resistance in C. glabrata underscores emerging echinocandin tolerance. Persistent high mortality suggests challenges in early diagnosis and treatment optimization. Global findings emphasize pandemic-related disruptions in infection control and therapeutic strategies.

Strengths:

The longitudinal design and large sample size provided robust comparisons. Multivariate analysis identified clinically relevant risk factors, enhancing predictive accuracy.

Limitations:

Single-center data may limit generalizability. Confounding variables, such as comorbidities or regional practices, were not fully accounted for. Resistance trends in non-Candida species were not explored.

Design:

The study combines experimental and analytical approaches to characterize EVs during L. maculans infection. Key components include: (1) apoplastic fluid (AF) collection from infected B. napus cotyledons and leaves using vacuum infiltration; (2) EV isolation via differential centrifugation and validation through SDS-PAGE, immunoblotting, and transmission electron microscopy (TEM); (3) nanoparticle tracking analysis (NTA) for EV size distribution; and (4) proteomic analysis of EV cargoes using mass spectrometry. Comparative analyses with EV databases (e.g., EVpedia) and virulence factor databases (PHI-base) were performed to contextualize findings.

Procedures:

AFs were extracted from B. napus cotyledons and leaves at 7 days post-inoculation, with uninfected samples as controls. EVs were isolated via sequential centrifugation (2,000–100,000 × g) to remove cellular debris. TEM and NTA confirmed EV morphology (cup-shaped vesicles, 41–432 nm) and size heterogeneity. Proteomic analysis identified proteins in EVs from infected plant tissues and fungal culture filtrates, focusing on virulence factors and unconventional secretion pathways. Statistical validation included comparisons between compatible (susceptible host) and incompatible (resistant host) interactions, and functional annotations using Gene Ontology (GO) and protein-protein interaction networks.

Primary Findings:

Key findings include: (1) Detection of ribulose-bisphosphate carboxylase (RuBisCO) in AFs from infected cotyledons at 7 days post-inoculation, coinciding with the biotrophic-to-necrotrophic transition, suggesting host cell death contributes to RuBisCO release. (2) EVs isolated from L. maculans culture filtrates contained 103 proteins, including glucanases, chitinases, catalases, and peptidases, with 60% annotated as virulence factors in PHI-base. (3) EVs exhibited a size range of 41–432 nm (median ~100 nm) and cup-shaped morphologies via TEM. (4) Over 50% of fungal EV proteins lacked classical signal peptides, indicating unconventional secretion mechanisms. Comparative analyses revealed overlaps with virulence proteins from Cryptococcus neoformans and Fusarium species, such as glucanases and catalases.

Secondary Findings:

No significant differences in RuBisCO levels were observed between compatible and incompatible host interactions, implying necrosis alone does not drive EV release. EVs from fungal cultures shared functional similarities with other phytopathogens, including proteins involved in carbohydrate metabolism and stress response. Challenges in AF extraction from leaves due to cuticular barriers were addressed using Triton X-100. Gene ontology enrichment highlighted glucosyl hydrolases, peptidase activity, and chitin binding as dominant functional categories, while protein networks revealed interconnected clusters of enzymes critical for pathogen adaptation.

Interpretation:

EVs likely serve as multifunctional mediators in L. maculans pathogenesis, delivering virulence factors to degrade host cell walls and suppress immunity. The presence of RuBisCO in infected AFs suggests EVs may also carry host-derived molecules, though its absence in resistant hosts indicates additional regulatory mechanisms. The lack of RuBisCO differences between host interactions implies necrosis is not the sole driver of EV release, possibly involving effector-triggered immunity or host signaling pathways. Comparative proteomics underscores EVs as conserved vectors for pathogen adaptation, while unconventional secretion mechanisms highlight novel routes for protein trafficking in fungi.

Strengths:

The study pioneers the use of B. napus-L. maculans as a model for interkingdom EV research, employing rigorous validation methods (TEM, NTA, proteomics) and standardized protocols. The integration of PHI-base annotations and comparative analyses strengthens functional interpretations of EV cargoes.

Limitations:

AF extraction from leaves remained challenging, potentially biasing results toward cotyledon data. EV isolation methods may not fully exclude contaminating particles, necessitating adherence to MISEV2023 guidelines. Functional validation of identified proteins (e.g., Nep1-like proteins) remains incomplete, limiting causal conclusions about their roles in virulence.

Design:

The study employed a parallel-group, single-blind RCT design with a 12-month recruitment period and six-month follow-up. Participants were adults with CMP (e.g., chronic low back pain) excluding those with severe mental health disorders, terminal illnesses, or shift work. The SCIP group (n=15) received comprehensive sleep disorder assessments via polysomnography (PSG) and tailored interventions (e.g., CPAP for OSA, non-benzodiazepine therapies for insomnia) alongside standard pain management (e.g., NSAIDs, physical therapy). The control group (n=26) received standard pain care without sleep-focused interventions. Baseline and follow-up assessments included demographic data, anthropometrics, pain characteristics, and medication use.

Procedures:

Key measures included the Numerical Rating Scale (NRS) for pain intensity, SF-36 and EQ-5D-5L for QoL, Hospital Anxiety and Depression Scale (HADS) for psychological distress, and sleep-specific tools (PSQI, ISI, ESS, RLS criteria). PSG identified sleep disorders in SCIP participants. Statistical analyses used mixed-effects models to compare outcomes between groups, with opioid consumption modeled via gamma distribution and psychological scores via Gaussian/beta distributions. McNemar tests and paired t-tests assessed pre-post changes within the SCIP group.

Primary Findings:

SCIP participants had higher baseline opioid use (75.1 mg/day vs. 37.5 mg/day in controls) but no significant reduction at follow-up (p=0.652). However, SCIP demonstrated marked improvements in psychological outcomes: anxiety risk decreased from 73.3% to 46.7% (vs. 29.2% in controls), and depression dropped from 53.3% to 33.3% (vs. 29.2%). The HADS anxiety subscale improved by 26.6% in SCIP versus 10.8% in controls, while depression improved by 20% vs. 4.1%. The Pain Anxiety Symptoms Scale-20 (PASS-20) showed significant reductions in pain-related anxiety, particularly cognitive anxiety and avoidance behaviors. PSG revealed high sleep disorder prevalence in SCIP: 50% had RLS, 60% moderate/severe insomnia, and 62.5% OSA.

Secondary Findings:

Pain intensity (NRS) decreased modestly in both groups (p=0.001), with baseline scores strongly predicting outcomes. QoL metrics showed mixed results: EQ-5D-5L utility improved slightly (p=0.001), driven by baseline values, while SF-36 total scores declined (p<0.001). The Functional Outcomes of Sleep Questionnaire (FOSQ) indicated greater gains in SCIP for sleep-related productivity and intimacy. Opioid dose changes correlated with baseline doses (p=0.005), suggesting higher initial use may limit reduction potential. Attrition occurred in SCIP (three dropouts, including one death), potentially affecting results.

Interpretation:

SCIP effectively reduced anxiety and depression but did not significantly lower pain intensity or opioid use. The psychological improvements likely stemmed from addressing sleep disorders (e.g., OSA, RLS) and providing circadian rhythm education. While pain scores decreased similarly in both groups, SCIP’s focus on sleep may have enhanced coping mechanisms rather than directly reducing pain. The study underscores the critical role of undiagnosed sleep disorders in CMP management, as treating these conditions reduced psychological distress and improved functional outcomes. The lack of opioid reduction may reflect high baseline doses in SCIP or insufficient follow-up time.

Strengths:

The study’s strengths include rigorous PSG assessments, validated outcome measures (e.g., HADS, EQ-5D-5L), and a focus on bidirectional sleep-pain interactions. It provides novel insights into integrating sleep interventions into chronic pain care.

Limitations:

Key limitations include a small sample size (n=49), short follow-up (six months), and baseline imbalances (e.g., higher opioid use in SCIP). Attrition in SCIP may have introduced bias, and the single-blind design could have influenced self-reported outcomes. The complexity of SCIP may have contributed to adherence challenges, as noted in dropout rates.

Design:

An observational, population-based study using GBD 2021 data to analyze COPD trends in adults aged ≥70 years. The study employed a comparative, longitudinal design to assess changes in prevalence, incidence, mortality, and DALYs across 204 countries and territories. Data were stratified by SDI quintiles and analyzed using age-standardized rates and annualized percentage changes (EAPC).

Procedures:

Key metrics included age-standardized prevalence, incidence, death, and DALY rates. Risk factors were quantified using the GBD framework, which identified seven contributors: particulate matter pollution, smoking, occupational particulate matter, low temperature, household air pollution, ambient ozone pollution, and secondhand smoke. Statistical models accounted for population growth, aging demographics, and regional variations. Results were validated against supplementary tables and visualized in figures from the GBD repository.

Primary Findings:

Globally, COPD prevalence increased by 162.2% and incidence by 157.4% since 1990, driven by population aging and rising life expectancy. Age-standardized prevalence and incidence rates rose slightly (EAPC 0.31 and 0.17, respectively), while mortality and DALY rates declined (EAPC -1.33 and -1.41). High-SDI regions (e.g., Western Europe, North America) had the highest prevalence rates, but low-SDI regions (e.g., South Asia, Oceania) experienced the steepest increases in incidence. The U.S. had the highest prevalence in 2021, while Iran saw the fastest growth. Conversely, COPD-related deaths and DALYs increased in absolute numbers due to population growth but declined proportionally. Nepal and Papua New Guinea had the highest death and DALY rates in 2021.

Secondary Findings:

Ambient ozone pollution emerged as the leading risk factor for COPD mortality in low-SDI regions, with its contribution rising since 1990. Smoking and particulate matter pollution were dominant in high- and high-middle SDI regions. Gender trends revealed that females aged 70–74 now exceed males in prevalence and case numbers, reversing historical male dominance. China, India, and the U.S. contributed the most to global COPD burden, while countries like Belarus and Singapore saw significant declines in DALY rates.

Interpretation:

The study reveals a paradoxical rise in COPD prevalence despite declining mortality, attributed to aging populations and improved screening. Disparities between regions reflect healthcare access and environmental exposures. High-SDI regions benefit from better management, while low-SDI areas face higher mortality due to limited resources and worsening air quality. The gender shift in prevalence underscores evolving risk exposures and diagnostic practices. Rising ozone pollution in low-SDI regions signals an urgent environmental health concern.

Strengths:

The study leverages the GBD's robust methodology, providing a comprehensive global analysis. Its longitudinal design captures long-term trends, and stratification by SDI and country highlights actionable disparities. The inclusion of risk factors offers actionable targets for public health interventions.

Limitations:

Modeled data may underestimate burden in low-income regions with sparse reporting. Comorbidity overlaps in older adults could inflate COPD prevalence estimates. Underdiagnosis in low-resource settings may skew regional comparisons, and pandemic impacts on COPD management remain understudied.

Design:

WCWH employs a community-based, longitudinal cohort design with a socio-ecological framework, emphasizing participatory research. The study follows 154 families (40% Chicano/Latino primary caregivers, 25% multiracial, 30% with less than a high school education) over five years. Data collection spans 12 months per cohort, with staggered timelines to reduce participant burden. The Plan-Do-Study-Act (PDSA) model guides iterative protocol adjustments, while a Community Strategy Team (CST) and 'ambassador families' ensure cultural responsiveness and community alignment.

Procedures:

Data collection integrates: (1) Biological measures (e.g., stress biomarkers via saliva samples), (2) Environmental sensors (air/water quality, noise pollution), (3) Wearable devices (Fitbit for activity/sleep, LENA recorders for language development), and (4) Behavioral assessments via the Hornsense app, which facilitates monthly surveys (1–1.5 hours), Ecological Momentary Assessments (EMAs), and real-time stress reporting. The study also employs focus groups, feedback surveys, and bilingual materials to address systemic barriers like healthcare access and environmental hazards (e.g., airport construction impacts). Statistical analyses examine causal links between exposures (e.g., air pollution and asthma) and child development outcomes.

Primary Findings:

Key outcomes include: (1) High retention rates (92% after two years, 87% after one year), attributed to flexible scheduling, monthly compensation ($40–$60), and culturally competent staff; (2) Environmental impacts on health, such as associations between air quality and respiratory issues in children; and (3) Community-driven insights, including prioritization of grocery access and transparency in data use. The Hornsense app achieved 99% engagement, with only 1% attrition due to time constraints.

Secondary Findings:

Secondary results highlight challenges like device calibration issues (e.g., air sensors) and delayed data report distribution. Focus groups revealed participant motivations (e.g., curiosity about health outcomes) and frustrations (e.g., app glitches). The study also identified disparities in conversational turns among toddlers linked to socioeconomic factors, measured via LENA recorders.

Interpretation:

WCWH demonstrates that participatory, longitudinal research in marginalized communities can yield high retention and actionable insights. Findings underscore the interplay between environmental exposures (e.g., pollution) and psychosocial factors (e.g., family connectedness) on child health. The PDSA model and community feedback loops were critical in refining protocols, such as shortening surveys and rotating high-cost devices.

Strengths:

Strengths include interdisciplinary collaboration, high retention through culturally tailored strategies, and the use of real-time data tools like Hornsense. The study’s focus on co-creating knowledge with participants ensures relevance to local priorities, such as addressing airport-related environmental stressors.

Limitations:

Limitations include logistical challenges in scaling device distribution, reliance on self-reported data, and potential selection bias due to enrollment incentives. Technical issues with sensors and delays in data sharing also posed barriers.

Design:

The study employed a preclinical experimental design, combining molecular biology, virology, and immunology approaches. Key components included: (1) genetic engineering of SMERS to enhance expression and stability, (2) evaluation of surface display on NDV particles, and (3) immunogenicity testing in mice. The research utilized mammalian and chicken cell lines for codon optimization, embryonated chicken eggs for virus propagation, and BALB/c mice for in vivo studies.

Procedures:

SMERS was codon-optimized for mammalian and chicken cells to improve expression. Genetic constructs were engineered with mutations at critical cleavage sites (S1/S2, S2’, and 2P) to prevent premature proteolytic cleavage. Transmission electron microscopy (TEM) and ELISA were used to confirm surface expression. Immunogenicity was assessed via anti-SMERS IgG titers, plaque virus neutralization tests (PVNT-50), and interferon-γ (IFN-γ) ELISPOT assays for cellular immunity. Stability was tested through five serial passages in chicken eggs.

Primary Findings:

Codon-optimized SMERS sequences (mammalian- and chicken-optimized) significantly enhanced protein expression compared to the native sequence, as shown by Western blot analysis. The S1/S2 and S2’ mutations were critical for surface display, with the SMERS-S2’ variant demonstrating detectable expression via TEM and ELISA. The 2P mutation stabilized the prefusion conformation, increasing surface expression fivefold. In mice, both inactivated and live NDV-SMERS-S2’ formulations induced robust anti-SMERS IgG titers (comparable to recombinant protein controls) and neutralizing antibodies (PVNT-50 >1:1000 for high-dose groups). Live NDV outperformed inactivated formulations in cellular immunity, with double the IFN-γ-secreting splenocytes. The SMERS gene remained intact after five egg passages, confirming vector stability.

Secondary Findings:

Mutations targeting additional putative cleavage sites (PCM1 and PCM2) reduced SMERS expression, with PCM2 nearly abolishing detectable protein. TEM images confirmed consistent S1 immunogold labeling on NDV surfaces. Neutralizing antibody levels (PVNT50 ~3×10⁴) exceeded previous NDV-based MERS vaccine candidates. Adjuvants were critical for optimal immune responses in inactivated formulations.

Interpretation:

The study demonstrates that codon optimization and strategic mutations (S1/S2, S2’, and 2P) are essential for functional SMERS expression and stability on NDV. The 2P mutation’s role in maintaining prefusion conformation underscores the importance of structural engineering for antigen presentation. The live NDV platform’s superior cellular immune response highlights its potential for broader immune activation. The vector’s stability over multiple passages ensures scalability for vaccine production. These findings validate NDV as a promising platform for coronavirus vaccines, leveraging its safety and ease of use in egg-based systems.

Strengths:

The study integrated molecular engineering, immunology, and virology to address key challenges in MERS vaccine development. The use of NDV, a well-characterized vector with a favorable safety profile, strengthens translational potential. Stability testing confirmed the vector’s reliability for large-scale production.

Limitations:

The study lacked direct protective efficacy testing in MERS-CoV challenge models. The impact of pre-existing NDV immunity in human populations remains unexplored. While PCM mutations reduced expression, their exact mechanisms require further investigation.

Design:

The study employed a multidisciplinary approach, combining computational modeling, synthetic chemistry, in vitro enzymatic assays, and in vivo animal testing. A total of 16 hybrid compounds were synthesized, with compound I-1 selected as the lead candidate based on computational predictions. In vivo experiments involved alloxan-induced diabetic rats divided into control, acarbose-treated, and three test groups (IV, V, VI) administered 10, 20, and 30 mg/kg of I-1, respectively. The study adhered to ethical guidelines for animal handling and utilized standardized biochemical analysis kits (Crest Biosystems) for reproducibility.

Procedures:

Synthesis of I-1 involved six steps: (1) condensation of thiazolidinedione with 4-methoxybenzaldehyde to form a benzylidene intermediate, (2) propargylation with propargyl bromide, (3) alkylation of 7-hydroxycoumarin with dibromoethane, (4) azidation of the coumarin derivative, and (5) CuSO₄-mediated click chemistry to form the triazole bridge. Structural integrity was confirmed via ¹H/¹³C NMR and mass spectrometry. Molecular docking studies using LeadIT software evaluated binding affinity for α-glucosidase, dipeptidyl peptidase-4 (DPP-4), PPAR-γ, and α-amylase. ADMET analysis (SwissADME) assessed pharmacokinetic and safety profiles. Density functional theory (DFT) calculations at the B3LYP/6-31G** level determined electronic properties, including HOMO-LUMO gaps. Molecular dynamics (MD) simulations over 100 ns analyzed compound stability and enzyme interactions. In vivo efficacy was measured via fasting blood glucose, body weight, insulin levels, and biochemical parameters (ALT, AST, urea, creatinine, lipid profiles). Acute toxicity was tested at 2000 mg/kg, and statistical analysis followed established protocols.

Primary Findings:

Compound I-1 demonstrated exceptional α-glucosidase inhibitory activity with an IC₅₀ of 1.49 µg/mL, significantly surpassing acarbose’s IC₅₀ of 15.084 µg/mL. Molecular docking revealed a binding affinity of -22.546 kcal/mol for α-glucosidase, compared to acarbose’s -6.582 kcal/mol. Key interactions included hydrogen bonds with Arg624 and π-sulfur interactions with Met565. In vivo studies showed blood glucose reductions of 94.15 mg/dL (10 mg/kg) and 74.60 mg/dL (30 mg/kg) in diabetic rats, nearing acarbose’s 80.44 mg/dL. Insulin levels increased by 40% at 30 mg/kg, and lipid profiles improved with reductions in total cholesterol (28.7%), triglycerides (34.5%), and LDL (41.2%), alongside a 22% rise in HDL. Liver and kidney biomarkers (ALT, AST, urea, creatinine) normalized, indicating organ protection. Acute toxicity testing at 2000 mg/kg showed no mortality or adverse effects, classifying I-1 as non-toxic (Class IV).

Secondary Findings:

ADMET analysis indicated I-1 complied with most Lipinski’s rule of five criteria except molecular weight (504.51 g/mol), which slightly exceeded the 500 g/mol threshold. It displayed low gastrointestinal absorption (borderline), no blood-brain barrier penetration, and potential inhibition of CYP2C19, CYP2C9, and CYP3A4. DFT calculations revealed a smaller HOMO-LUMO gap (2.89 eV) for I-1 compared to rosiglitazone (4.47 eV), suggesting enhanced reactivity and stability. SAR studies showed that methoxy groups at the 3-position of benzaldehyde improved α-glucosidase inhibition, while meta/para substitutions influenced α-amylase activity. MD simulations confirmed stable interactions with α-glucosidase, DPP-4, and PPAR-γ, with RMSD values <3 Å and π-π stacking contributing to binding affinity. Antioxidant activity via DPPH assay yielded an IC₅₀ of 2.73 µg/mL, outperforming ascorbic acid.

Interpretation:

The hybrid structure of I-1 synergizes the pharmacological properties of its components: thiazolidinedione’s PPAR-γ agonism, coumarin’s antioxidant effects, and triazole’s stability. Its high α-glucosidase binding affinity and in vitro/in vivo efficacy suggest superior glucose-lowering potential over acarbose. The dual mechanism—direct enzyme inhibition and PPAR-γ modulation—likely contributes to insulin sensitization and organ protection observed in vivo. The smaller HOMO-LUMO gap implies greater electronic reactivity, optimizing interactions with target enzymes. The normalization of liver and kidney markers indicates reduced oxidative stress and metabolic dysfunction, aligning with coumarin’s antioxidant role. ADMET results highlight the need for molecular weight optimization to fully meet Lipinski’s criteria, though its non-toxic profile and CYP inhibition potential warrant further safety evaluation.

Strengths:

The study’s strengths include a rigorous, multidisciplinary approach integrating computational predictions with experimental validation. The synthesis of I-1 followed a logical, stepwise process with confirmed structural integrity. In vivo testing over 28 days provided longitudinal data on efficacy and safety, while acute toxicity assessments reinforced its tolerability. The use of standardized biochemical kits ensured reproducibility, and the inclusion of multiple endpoints (glucose, insulin, lipid profiles, organ biomarkers) offers a holistic view of therapeutic potential.

Limitations:

Key limitations include I-1’s molecular weight exceeding Lipinski’s rule of five, which may affect drug absorption and distribution. While acute toxicity was favorable, long-term safety and pharmacokinetic studies are needed. The in vivo model used alloxan-induced diabetes, which may not fully replicate human Type 2 DM pathophysiology. Additionally, α-amylase inhibition was weaker than α-glucosidase, suggesting limited impact on starch digestion. The CYP inhibition potential identified in ADMET requires further investigation to assess drug-drug interaction risks.

Design:

The study employed fluorescence recovery after photobleaching (FRAP) and confocal microscopy to measure diffusion coefficients (Dconfocal) and fractional recovery of drugs in live HeLa cells. Researchers tested weakly basic drugs (e.g., SB216763, quinacrine, primaquine) alongside neutral or negatively charged compounds (e.g., fluorescein, BODIPY-NHAc). Experiments compared drug behavior in aqueous solutions, live cells, and cell extracts, with lysosomal sequestration assessed via colocalization with LysoTracker-633. Chemical modifications (e.g., N-acetylation) and lysosomal acidification inhibitors (Bafilomycin A1, sodium azide) were used to isolate the effects of protonation and organelle trapping.

Procedures:

Key techniques included Line-FRAP (800 Hz imaging) for high-speed diffusion measurements and microinjection to bypass membrane permeability barriers. Drugs were bleached using a 635 nm laser, with recovery curves analyzed via double exponential models. NMR and HRMS validated synthesized compounds like N-acetylated primaquine (PrimAc) and BODIPY derivatives. Statistical analyses (one-way ANOVA, Dunnett’s test) compared treatments across 20–30 cells per condition. Colocalization studies ruled out interactions with lipid droplets, endoplasmic reticulum, or nucleic acids.

Primary Findings:

Weakly basic drugs exhibited drastically reduced mobility in the cytoplasm compared to aqueous solutions. For example, SB216763 (pKa 7.0) and quinacrine (pKa 9.08) had Dconfocal values of 0.61 and 2.5 µm²/s (40- and 17-fold slower than in buffer), with only 80% recovery. Neutral fluorescein (pKa ~3) diffused rapidly (38.5 µm²/s) with near-complete recovery. Protonation-driven lysosomal sequestration was confirmed via colocalization, but lysosomal acidification inhibitors only modestly improved diffusion, indicating cytoplasmic interactions as the primary barrier. N-acetylation neutralized drug charges, restoring near-aqueous diffusion (e.g., BODIPY-NHAc: 10 µm²/s vs. 1 µm²/s for its protonatable form).

Secondary Findings:

A strong correlation emerged between pKa and diffusion rates: higher pKa drugs (e.g., quinacrine) showed slower diffusion. Molecular weight and logP had no significant impact. Sodium azide reduced lysosomal accumulation but further slowed diffusion, suggesting cytoplasmic crowding exacerbates mobility issues. Primaquine-NHAc modifications increased Dconfocal from 0.27 to 0.6 µm²/s and recovery from 0.2 to 0.5. Fluorescein derivatives demonstrated that even minor charge differences (e.g., 5-amino fluorescein, pKa ~9) caused lysosomal trapping and slower diffusion.

Interpretation:

Protonation-induced charge increases nonspecific binding to cytoplasmic components, drastically reducing drug mobility. While lysosomal sequestration contributes to reduced recovery, cytoplasmic interactions are the dominant factor. The findings challenge the assumption that membrane permeability alone dictates drug distribution, highlighting the need to consider post-entry diffusion barriers. Neutralizing drug charges via modifications like N-acetylation could enhance bioavailability but may require balancing against potential effects on pharmacokinetics or target binding.

Strengths:

The study employed advanced Line-FRAP for high-resolution diffusion measurements and rigorously validated synthesized compounds via NMR/HRMS. Direct comparisons between protonated and neutral analogs, alongside lysosomal inhibition experiments, strengthened causal inferences about protonation effects.

Limitations:

The focus on HeLa cells limits generalizability to other cell types. Fluorescent tags may alter drug behavior, and long-term effects of modifications (e.g., N-acetylation) on pharmacology remain unexplored. Cytoplasmic crowding’s exact contribution to hindered diffusion requires further mechanistic study.

Design:

The study employed a longitudinal observational and experimental design involving 46 lambs born to 33 ewes across 20 pens. Ewes were classified as chronic carriers (consistent nasal detection via PCR), non-carriers (no detection), or intermittent carriers (variable detection). Exposed pens contained at least one chronic carrier, while non-exposed pens had only non-carriers. Uncertain pens included intermittent carriers. Lamb outcomes were tracked for survival, clinical signs, and cause of death. Crossover experiments tested the impact of placing non-carrier ewes in exposed pens.

Procedures:

Key methods included biannual nasal swab PCR testing (cycle threshold ≤36 for detection), multi-locus sequence typing (MLST) for strain identification, and clinical scoring of lambs for respiratory symptoms. Necropsies confirmed pneumonia as the cause of death. Biosecurity measures minimized cross-contamination. The study also analyzed strain dynamics over time, including shifts following a 2015 epizootic at SDSU that introduced a new strain (BHS-055/DS-096).

Primary Findings:

Exposed-pen lambs (n=30) had a 77% mortality rate from pneumonia (23 deaths), while non-exposed lambs (n=11) had 0% mortality. Surviving exposed lambs exhibited severe respiratory signs (e.g., nasal discharge, coughing), whereas non-exposed lambs showed no symptoms. Crossover experiments revealed that non-carrier ewes in exposed pens had 57% lamb survival, contrasting with 100% survival in non-exposed pens. M. ovipneumoniae-specific antibodies were detected in 89% of exposed lambs but none in non-exposed lambs. Surviving lambs cleared infection by 1–2 years of age.

Secondary Findings:

Strain dynamics showed stable carriage of original strains (e.g., BHS-024 in WSU ewes) but shifts at SDSU post-2015 epizootic. The new strain BHS-055/DS-096 spread to non-carrier ewes, altering their status. Multiple strains coexisted in some ewes (e.g., SHMT.W91 and SHMT.Y28 at SDSU). A 2014-associated strain (BHS-137) reappeared in a 2018 lamb, indicating long-term strain survival. Chronic carrier ewes transmitting to lambs had a 95% pneumonia mortality rate, versus 57% survival when non-lambing.

Interpretation:

Chronic carrier ewes are central to sustaining M. ovipneumoniae outbreaks, with direct transmission to lambs during early life driving high mortality. Strain-specific immune responses and cross-strain infections complicate disease management, as new strains can destabilize established carriage patterns. The study confirms M. ovipneumoniae as the primary pathogen initiating pneumonia, rather than secondary bacteria like Pasteurellaceae. Lamb-to-lamb transmission likely follows ewe-to-lamb spread, though this was not directly tested.

Strengths:

The crossover design and longitudinal strain tracking provided robust evidence for the carrier hypothesis. Necropsy confirmation of pneumonia and MLST strain analysis strengthened causal links between ewe carriage and lamb mortality.

Limitations:

Small sample sizes limited statistical power, and MLST could not detect minority strains, potentially underestimating multiple strain carriage. Ethical constraints restricted experimental manipulation of wild populations.