Title: As Coronavirus Fears Surge, Keep Cleaning Products Away From Children
Category: Health News
Created: 4/27/2020 12:00:00 AM
Last Editorial Review: 4/27/2020 12:00:00 AM

Title: As Demand for Hand Sanitizer Soars, FDA Warns of Makers' Bogus Claims
Category: Health News
Created: 4/27/2020 12:00:00 AM
Last Editorial Review: 4/28/2020 12:00:00 AM

Title: Blood Count May Offer Clues to Treatment of COVID-19: Study
Category: Health News
Created: 5/1/2020 12:00:00 AM
Last Editorial Review: 5/1/2020 12:00:00 AM

Title: Workers With Cluster Headaches Take Twice as Many Sick Days
Category: Health News
Created: 2/6/2020 12:00:00 AM
Last Editorial Review: 2/6/2020 12:00:00 AM

Title: During Droughts, Many Poor Americans Will Lack Clean Tap Water: Study
Category: Health News
Created: 4/30/2020 12:00:00 AM
Last Editorial Review: 5/1/2020 12:00:00 AM

Title: Pangolins Hold Clues to How COVID-19 Began -- and Might End
Category: Health News
Created: 5/8/2020 12:00:00 AM
Last Editorial Review: 5/8/2020 12:00:00 AM

Title: Trump Says Obamacare Must Go as U.S. Coronavirus Cases Climb Past 1.2 Million
Category: Health News
Created: 5/7/2020 12:00:00 AM
Last Editorial Review: 5/8/2020 12:00:00 AM

Learning more about this evolutionary advantage in pangolins may suggest possible treatments for coronavirus in humans, the team said.

Reports of new and unusual symptoms associated with COVID-19 resulted in this week's top trending clinical topic.

Title: Americans' Cholesterol Levels Decline: Study
Category: Health News
Created: 11/12/2019 12:00:00 AM
Last Editorial Review: 11/13/2019 12:00:00 AM

PMC is pleased to announce the first of what we hope will be an annual series of conferences for users of the Journal Article Tag Suite, that is, for users of any of the “NLM DTDs”. The Journal Article Tag Suite Conference (JATS-Con) is a peer-reviewed conference that will feature a broad range of content on the Tag Suite—from the technical components to publishing theory—as well as the latest news on the Tag Suite. The conference will be hosted by the National Center for Biotechnology Information (NCBI) at the National Library of Medicine on the NIH campus in Bethesda, Maryland on November 1 & 2, 2010.

For more information on the conference, see https://jats.nlm.nih.gov/jats-con.

Note: There is no charge for the conference; however, space is limited so preregistration is required.

You can now search for Open Access articles that have certain types of licenses, by using special filters in both PMC and PubMed. These filters are based on license information that is provided to PMC by publishers and other content providers, as encoded by machine-readable identifiers in the source XML of each article. For more information, see our updated Open Access Subset page.

As of February 21, 2014, PMC became home to three million articles! As listed on our home page, the content has been provided in part by 1441 full participation journals, 277 NIH Portfolio journals and 2470 selective deposit journals. For related information on PMC milestones, see these announcements from 2007 and 2010, respectively.

In order to facilitate text and data mining for articles in the Open Access Subset, we are now providing plain text files for those articles on our FTP site. These files contain the full text of the article, extracted either from the XML source files, or (for those articles that don't have XML) the PDF files. Users are directly and solely responsible for compliance with copyright restrictions and are expected to adhere to the terms and conditions defined by the copyright holder (see the PMC Copyright Notice).

These text files are bundled in gzipped archives. Note that these files are quite large (each greater than one gigabyte). They are available for download as:

• ftp://ftp.ncbi.nlm.nih.gov/pub/pmc/articles.txt.0-9A-B.tar.gz
• ftp://ftp.ncbi.nlm.nih.gov/pub/pmc/articles.txt.C-H.tar.gz
• ftp://ftp.ncbi.nlm.nih.gov/pub/pmc/articles.txt.I-N.tar.gz
• ftp://ftp.ncbi.nlm.nih.gov/pub/pmc/articles.txt.O-Z.tar.gz

These files are updated every week, on Saturday.

For more information, see the Bulk Packages of OA Articles section of our FTP Service page.

In collaboration with Europe PMC, PMC has rolled out several updates to our article display in order to enhance the transparency and readability of the content.

Navigating from the PMC record to the PubMed record has been made easier by the addition of hyperlinked PubMed IDs (PMIDs) in the upper right-hand corner of article records. Clicking the PMID link will take you to the corresponding citation record in PubMed.

The PMC Disclaimer link has also been moved out of the Copyright and License information section for easier discovery and access. This page describes what content is included in PMC as well as other important NCBI and NLM disclaimer information.

Additionally, two changes have been implemented to improve the functionality of author names. Users can now click on an author name to view the author’s affiliation(s). Users also have the option of running a quick author name search in PMC by clicking the linked author name in “Find articles by [author name]”. In the example pictured above, the search would be for “Sawyer SL”[Author].

And finally, figures and tables have been moved inline in the article display. By moving away from the thumbnail display, PMC hopes to make it easier for users to view figure and table data as they read articles. Users may still click on the figure/table title or “Open in separate window” (as available) link for a closer look.

We hope these updates improve the overall user experience in PMC and look forward to hearing your feedback.

References

Screenshots from:

Qiao, Y., Yang, J., Liu, L., Zeng, Y., Ma, J., Jia, J., … Wang, Y. (2018). Successful treatment with pazopanib plus PD-1 inhibitor and RAK cells for advanced primary hepatic angiosarcoma: a case report. BMC Cancer, 18, 212. http://doi.org/10.1186/s12885-018-3996-3

Stabell, A. C., Meyerson, N. R., Gullberg, R. C., Gilchrist, A. R., Webb, K. J., Old, W. M., … Sawyer, S. L. (2018). Dengue viruses cleave STING in humans but not in nonhuman primates, their presumed natural reservoir. eLife, 7, e31919. http://doi.org/10.7554/eLife.31919

Both articles made available under a CC-BY license.

Machine-readability of scholarly outputs is critical to supporting large-scale analysis of the scientific literature. To that end, PMC’s Tagging Guidelines and internal processes have been updated to support the JATS4R recommendations for tagging clinical trial information. NLM encourages PMC-participating publishers, journals, and data providers to review this guidance. Please contact us at pubmedcentral@ncbi.nlm.nih.gov if you have any questions.

On March 18, 2019, PMC will no longer provide bulk packages of Open Access (OA) Subset text and XML at the top level directory of the FTP Service. These files were superseded in August 2016 by the Commercial Use and Non-Commercial Use bulk packages located in the oa_bulk subdirectory. One set comprises articles that may be used for commercial purposes (the Commercial Use Collection); the other contains articles that can be used only for non-commercial purposes. Anyone planning to use OA subset content for non-commercial purposes will need to download both “non_comm_use.*.tar.gz” and “comm_use.*.tar.gz” to access the complete collection. See the Open Access Subset page for additional details. Questions should be directed to pubmedcentral@ncbi.nlm.nih.gov.

Title: Heart Attacks, Strokes Are Declining Among People With Diabetes
Category: Health News
Created: 5/1/2020 12:00:00 AM
Last Editorial Review: 5/4/2020 12:00:00 AM

Title: Xiaflex (collagenase clostridium histolyticum)
Category: Medications
Created: 3/3/2020 12:00:00 AM
Last Editorial Review: 3/3/2020 12:00:00 AM

Title: How Common Are STDs? Most People Have No Clue
Category: Health News
Created: 2/25/2020 12:00:00 AM
Last Editorial Review: 2/25/2020 12:00:00 AM

Title: AHA News: Estrogen Therapy in Early Menopause May Help Keep Arteries Clear
Category: Health News
Created: 3/3/2020 12:00:00 AM
Last Editorial Review: 3/4/2020 12:00:00 AM

Title: Could the Weather Swings of Climate Change Make Flu Seasons Worse?
Category: Health News
Created: 2/20/2020 12:00:00 AM
Last Editorial Review: 2/21/2020 12:00:00 AM

Title: When Booze Labels Carry Health Warnings, Drinking Declines: Study
Category: Health News
Created: 5/4/2020 12:00:00 AM
Last Editorial Review: 5/4/2020 12:00:00 AM

Title: Kisqali (ribociclib)
Category: Medications
Created: 4/22/2020 12:00:00 AM
Last Editorial Review: 4/22/2020 12:00:00 AM

Title: U.S. Issues Highest Travel Alert for China as WHO Declares Health Emergency
Category: Health News
Created: 1/31/2020 12:00:00 AM
Last Editorial Review: 2/3/2020 12:00:00 AM

Title: Get Ready for Clocks to 'Spring Ahead'
Category: Health News
Created: 3/6/2020 12:00:00 AM
Last Editorial Review: 3/6/2020 12:00:00 AM

Dental students’ ability to critique team performance in dental school team clinics is a key component of dental education. The aim of this study was to determine if students’ perceptions of their team leaders’ openness of communication, cooperative decision making, and well-defined goals were positively related to the students’ improvement-oriented voice behavior and willingness to raise concerns in the clinical environment. This study used a voluntary 12-question survey, distributed via email to all 311 students at the University of Nevada, Las Vegas School of Dental Medicine after completion of the spring 2017 semester. Eighty-seven students responded, for a response rate of 28%. Responses were stratified by team, class year, and gender, and the quantitative distribution of answers to each question was correlated with each other. Team leader collaborative qualities, which included openness for communication, cooperative decision making, and well-defined goals, were found to have a significant positive relationship with students’ willingness to both raise concerns and make suggestions. Additionally, when measured by class year and gender, team differences in voice behavior assessment by students across the teams were found to be independent of class year, and no significant differences were found by gender. These results suggested that, to maintain high levels of communication, proper reporting of concerns, and a high standard of care, dental schools should encourage team leaders to enhance their capacity to present active collaborative behaviors in the school’s clinic. The study also highlighted potential opportunities for further study of faculty traits and development in the dental school team model.

Clinical teaching is a cornerstone of health sciences education; it is also the most challenging aspect. The University of Pittsburgh Schools of Dental Medicine, Nursing, and Pharmacy developed a new evidence-based interprofessional course framed as a faculty learning community (FLC) around the principles of learning in a clinical environment. The aim of this study was to assess the overall effectiveness of this two-semester FLC at four health professions schools in academic year 2014-15. The assessment included anonymous participant surveys in each session and an anonymous end-of-course survey. Thirty-five faculty members from dental, health and rehabilitation sciences, nursing, and pharmacy enrolled in the FLC, with six to 32 enrollees attending each session. All attendees at each session completed the session evaluation surveys, but the attendance rate at each session ranged from 17.1% to 91.4%. Sixteen participants (46%) completed the end-of-course survey. The results showed overall positive responses to the FLC and changes in the participants’ self-reported knowledge. Session surveys showed that the participants found the FLC topics helpful and appreciated the opportunity to learn from each other and the interprofessional nature of the FLC. Responses to the end-of-course survey were in alignment with the individual session surveys and cited specific benefits as being the content, teaching materials, and structured discussions. In additional feedback, participants reported interest to continue as a cohort and to extend the peer-support system beyond the FLC. This outcomes assessment of the first round of the FLC confirmed that this cohort-based faculty development in an interprofessional setting was well received by its participants. Their feedback provided valuable insights for changes to future offerings.

The number of citations an article receives is an important indicator to quantify its influence in its field. The aim of this study was to identify and analyze the characteristics of the 50 top-cited articles addressing dental education published in two journals dedicated to dental education (European Journal of Dental Education and Journal of Dental Education). The Web of Science database was searched to retrieve the 50 most-cited articles from the two journals in December 2018. The top-cited articles were analyzed for journal of publication, number of citations, institution and country of origin, year of publication, study type, keywords, theme and subtheme, and international collaborations. The results showed the 50 top-cited articles were cited between 24 and 146 times each. The majority of these top-cited articles (n=34) were published in the Journal of Dental Education. Half (n=25) of the articles were by authors in the U.S. The most common study types were surveys (n=26) and reviews (n=10). The main themes of these top-cited articles were curriculum and learner characteristics. This bibliometric analysis can serve as a reference for recognizing studies with the most impact in the scholarship of dental education.

Purpose: The purpose of this study was to determine strength of muscles involved with instrumentation (scaling) by dental hygienists and the additive effects of cellular (mobile) phone usage, as indicated by measurements of muscular force generation.Methods: A convenience sample of licensed dental hygienists currently in clinical practice (n=16) and an equal number of individuals not currently using devices/tools repetitively for work (n=16), agreed to participate in this pilot study. All participants completed a modified cell phone usage questionnaire to determine their use pattern and frequency. Upon completion of the questionnaire, participants' force production in six muscle groups was measured using a hand-held dynamometer. Descriptive statistics were used to analyze the data.Results: A total of 16 licensed dental hygienists (n=16) and 16 participants with no history of using tools/devices repetitively for work (n=16), comprised the experimental and control groups, repectively. The control group generated greater muscle force than the experimental group for the abductor pollicis longus (p=0.045). Significant differences were identified when comparing the low mobile phone users in the experimental group to the control group for the flexor pollicis brevis (p=0.031), abductor pollicis longus (p=0.031), and flexor digitorum (p=0.006), with the control group demonstrating higher muscle force. Years in clinical practice and mobile phone use was shown to have a significant effect on muscular force generation for the flexor pollicis brevis (F=3.645, df=3, p=0.020) and flexor digitorum (F=3.560, df=3, p=0.022); subjects who practiced dental hygiene the longest produced the least amount of muscle force.Conclusion: Results from this pilot study indicate there are no significant additive effects of cell phone use and dental hygiene practice on finger muscles used for instrumentation. However, results indicate that dental hygiene practice demonstrated significant effects on muscular strength as compared to individuals who do not use tools/devices repetitively for work. The small sample size may have impacted results and the study should be repeated with a larger sample.

Membrane-bound proteins have been proposed to mediate the transport of long-chain FA (LCFA) transport through the plasma membrane (PM). These proposals are based largely on reports that PM transport of LCFAs can be blocked by a number of enzymes and purported inhibitors of LCFA transport. Here, using the ratiometric pH indicator (2',7'-bis-(2-carboxyethyl)-5-(and-6-)-carboxyfluorescein and acrylodated intestinal FA-binding protein-based dual fluorescence assays, we investigated the effects of nine inhibitors of the putative FA transporter protein CD36 on the binding and transmembrane movement of LCFAs. We particularly focused on sulfosuccinimidyl oleate (SSO), reported to be a competitive inhibitor of CD36-mediated LCFA transport. Using these assays in adipocytes and inhibitor-treated protein-free lipid vesicles, we demonstrate that rapid LCFA transport across model and biological membranes remains unchanged in the presence of these purported inhibitors. We have previously shown in live cells that CD36 does not accelerate the transport of unesterified LCFAs across the PM. Our present experiments indicated disruption of LCFA metabolism inside the cell within minutes upon treatment with many of the "inhibitors" previously assumed to inhibit LCFA transport across the PM. Furthermore, using confocal microscopy and a specific anti-SSO antibody, we found that numerous intracellular and PM-bound proteins are SSO-modified in addition to CD36. Our results support the hypothesis that LCFAs diffuse rapidly across biological membranes and do not require an active protein transporter for their transmembrane movement.

Geranylgeranoic acid (GGA) originally was identified in some animals and has been developed as an agent for preventing second primary hepatoma. We previously have also identified GGA as an acyclic diterpenoid in some medicinal herbs. Recently, we reported that in human hepatoma-derived HuH-7 cells, GGA is metabolically labeled from ¹³C-mevalonate. Several cell-free experiments have demonstrated that GGA is synthesized through geranylgeranial by oxygen-dependent oxidation of geranylgeraniol (GGOH), but the exact biochemical events giving rise to GGA in hepatoma cells remain unclear. Monoamine oxidase B (MOAB) has been suggested to be involved in GGOH oxidation. Here, using two human hepatoma cell lines, we investigated whether MAOB contributes to GGA biosynthesis. Using either HuH-7 cell lysates or recombinant human MAOB, we found that: 1) the MAO inhibitor tranylcypromine dose-dependently downregulates endogenous GGA levels in HuH-7 cells; and 2) siRNA-mediated MAOB silencing reduces intracellular GGA levels in HuH-7 and Hep3B cells. Unexpectedly, however, CRISPR/Cas9-generated MAOB-KO human hepatoma Hep3B cells had GGA levels similar to those in MAOB-WT cells. A sensitivity of GGA levels to siRNA-mediated MAOB downregulation was recovered when the MAOB-KO cells were transfected with a MAOB-expression plasmid, suggesting that MAOB is the enzyme primarily responsible for GGOH oxidation and that some other latent metabolic pathways may maintain endogenous GGA levels in the MAOB-KO hepatoma cells. Along with the previous findings, these results provide critical insights into the biological roles of human MAOB and provide evidence that hepatic MAOB is involved in endogenous GGA biosynthesis via GGOH oxidation.

Many clinical studies and epidemiological investigations have clearly demonstrated that women are twice as likely to develop cholesterol gallstones as men, and oral contraceptives and other estrogen therapies dramatically increase that risk. Further, animal studies have revealed that estrogen promotes cholesterol gallstone formation through the estrogen receptor (ER) α, but not ERβ, pathway. More importantly, some genetic and pathophysiological studies have found that G protein-coupled estrogen receptor (GPER) 1 is a new gallstone gene, Lith18, on chromosome 5 in mice and produces additional lithogenic actions, working independently of ERα, to markedly increase cholelithogenesis in female mice. Based on computational modeling of GPER, a novel series of GPER-selective antagonists were designed, synthesized, and subsequently assessed for their therapeutic effects via calcium mobilization, cAMP, and ERα and ERβ fluorescence polarization binding assays. From this series of compounds, one new compound, 2-cyclohexyl-4-isopropyl-N-(4-methoxybenzyl)aniline (CIMBA), exhibits superior antagonism and selectivity exclusively for GPER. Furthermore, CIMBA reduces the formation of 17β-estradiol-induced gallstones in a dose-dependent manner in ovariectomized mice fed a lithogenic diet for 8 weeks. At 32 μg/day/kg CIMBA, no gallstones are found, even in ovariectomized ERα (^–/–) mice treated with 6 μg/day 17β-estradiol and fed the lithogenic diet for 8 weeks. In conclusion, CIMBA treatment protects against the formation of estrogen-induced cholesterol gallstones by inhibiting the GPER signaling pathway in female mice. CIMBA may thus be a new agent for effectively treating cholesterol gallstone disease in women.­

The formation and properties of liquid-ordered (Lo) lipid domains (rafts) in the plasma membrane are still poorly understood. This limits our ability to manipulate ordered lipid domain-dependent biological functions. Giant plasma membrane vesicles (GPMVs) undergo large-scale phase separations into coexisting Lo and liquid-disordered lipid domains. However, large-scale phase separation in GPMVs detected by light microscopy is observed only at low temperatures. Comparing Förster resonance energy transfer-detected versus light microscopy-detected domain formation, we found that nanodomains, domains of nanometer size, persist at temperatures up to 20°C higher than large-scale phases, up to physiologic temperature. The persistence of nanodomains at higher temperatures is consistent with previously reported theoretical calculations. To investigate the sensitivity of nanodomains to lipid composition, GPMVs were prepared from mammalian cells in which sterol, phospholipid, or sphingolipid composition in the plasma membrane outer leaflet had been altered by cyclodextrin-catalyzed lipid exchange. Lipid substitutions that stabilize or destabilize ordered domain formation in artificial lipid vesicles had a similar effect on the thermal stability of nanodomains and large-scale phase separation in GPMVs, with nanodomains persisting at higher temperatures than large-scale phases for a wide range of lipid compositions. This indicates that it is likely that plasma membrane nanodomains can form under physiologic conditions more readily than large-scale phase separation. We also conclude that membrane lipid substitutions carried out in intact cells are able to modulate the propensity of plasma membranes to form ordered domains. This implies lipid substitutions can be used to alter biological processes dependent upon ordered domains.

The autosomal dominant disorder Schnyder corneal dystrophy (SCD) is caused by mutations in UbiA prenyltransferase domain-containing protein-1 (UBIAD1), which uses geranylgeranyl pyrophosphate (GGpp) to synthesize the vitamin K₂ subtype menaquinone-4 (MK-4). SCD is characterized by opacification of the cornea, owing to aberrant build-up of cholesterol in the tissue. We previously discovered that sterols stimulate association of UBIAD1 with ER-localized HMG-CoA reductase, which catalyzes a rate-limiting step in the synthesis of cholesterol and nonsterol isoprenoids, including GGpp. Binding to UBIAD1 inhibits sterol-accelerated ER-associated degradation (ERAD) of reductase and permits continued synthesis of GGpp in cholesterol-replete cells. GGpp disrupts UBIAD1-reductase binding and thereby allows for maximal ERAD of reductase as well as ER-to-Golgi translocation of UBIAD1. SCD-associated UBIAD1 is refractory to GGpp-mediated dissociation from reductase and remains sequestered in the ER to inhibit ERAD. Here, we report development of a biochemical assay for UBIAD1-mediated synthesis of MK-4 in isolated membranes and intact cells. Using this assay, we compared enzymatic activity of WT UBIAD1 with that of SCD-associated variants. Our studies revealed that SCD-associated UBIAD1 exhibited reduced MK-4 synthetic activity, which may result from its reduced affinity for GGpp. Sequestration in the ER protects SCD-associated UBIAD1 from autophagy and allows intracellular accumulation of the mutant protein, which amplifies the inhibitory effect on reductase ERAD. These findings have important implications not only for the understanding of SCD etiology but also for the efficacy of cholesterol-lowering statin therapy, which becomes limited, in part, because of UBIAD1-mediated inhibition of reductase ERAD.

Adipocytes take up long chain FAs through diffusion and protein-mediated transport, whereas FA efflux is considered to occur by diffusion. To identify potential membrane proteins that are involved in regulating FA flux in adipocytes, the expression levels of 55 membrane transporters without known function were screened in subcutaneous adipose samples from obese patients before and after bariatric surgery using branched DNA methodology. Among the 33 solute carrier (SLC) transporter family members screened, the expression of 14 members showed significant changes before and after bariatric surgery. One of them, Slc43a3, increased about 2.5-fold after bariatric surgery. Further investigation demonstrated that Slc43a3 is highly expressed in murine adipose tissue and induced during adipocyte differentiation in primary preadipocytes and in OP9 cells. Knockdown of Slc43a3 with siRNA in differentiated OP9 adipocytes reduced both basal and forskolin-stimulated FA efflux, while also increasing FA uptake and lipid droplet accumulation. In contrast, overexpression of Slc43a3 decreased FA uptake in differentiated OP9 cells and resulted in decreased lipid droplet accumulation. Therefore, Slc43a3 seems to regulate FA flux in adipocytes, functioning as a positive regulator of FA efflux and as a negative regulator of FA uptake.

Acne is one of the most common dermatological conditions, but the details of its pathology are unclear, and current management regimens often have adverse effects. Cutibacterium acnes is known as a major acne-associated bacterium that derives energy from lipase-mediated sebum lipid degradation. C. acnes is commensal, but lipase activity has been observed to differ among C. acnes types. For example, higher populations of the type IA strains are present in acne lesions with higher lipase activity. In the present study, we examined a conserved lipase in types IB and II that was truncated in type IA C. acnes strains. Closed, blocked, and open structures of C. acnes ATCC11828 lipases were elucidated by X-ray crystallography at 1.6–2.4 Å. The closed crystal structure, which is the most common form in aqueous solution, revealed that a hydrophobic lid domain shields the active site. By comparing closed, blocked, and open structures, we found that the lid domain-opening mechanisms of C. acnes lipases (_CAlipases) involve the lid-opening residues, Phe-179 and Phe-211. To the best of our knowledge, this is the first structure-function study of _CAlipases, which may help to shed light on the mechanisms involved in acne development and may aid in future drug design.

Fatty liver involves ectopic lipid accumulation and dysregulated hepatic oxidative metabolism, which can progress to a state of elevated inflammation and fibrosis referred to as nonalcoholic steatohepatitis (NASH). The factors that control progression from simple steatosis to NASH are not fully known. Here, we tested the hypothesis that dietary vitamin E (VitE) supplementation would prevent NASH progression and associated metabolic alterations induced by a Western diet (WD). Hyperphagic melanocortin-4 receptor-deficient (MC4R^–/–) mice were fed chow, chow+VitE, WD, or WD+VitE starting at 8 or 20 weeks of age. All groups exhibited extensive hepatic steatosis by the end of the study (28 weeks of age). WD feeding exacerbated liver disease severity without inducing proportional changes in liver triglycerides. Eight weeks of WD accelerated liver pyruvate cycling, and 20 weeks of WD extensively upregulated liver glucose and oxidative metabolism assessed by ²H/¹³C flux analysis. VitE supplementation failed to reduce the histological features of NASH. Rather, WD+VitE increased the abundance and saturation of liver ceramides and accelerated metabolic flux dysregulation compared with 8 weeks of WD alone. In summary, VitE did not limit NASH pathogenesis in genetically obese mice, but instead increased some indicators of metabolic dysfunction.

The pregnane X receptor (PXR) is a nuclear receptor that can be activated by numerous drugs and xenobiotic chemicals. PXR thereby functions as a xenobiotic sensor to coordinately regulate host responses to xenobiotics by transcriptionally regulating many genes involved in xenobiotic metabolism. We have previously reported that PXR has pro-atherogenic effects in animal models, but how PXR contributes to atherosclerosis development in different tissues or cell types remains elusive. In this study, we generated an LDL receptor-deficient mouse model with myeloid-specific PXR deficiency (PXR^MyeLDLR^–/–) to elucidate the role of macrophage PXR signaling in atherogenesis. The myeloid PXR deficiency did not affect metabolic phenotypes and plasma lipid profiles, but PXR^MyeLDLR^–/– mice had significantly decreased atherosclerosis at both aortic root and brachiocephalic arteries compared with control littermates. Interestingly, the PXR deletion did not affect macrophage adhesion and migration properties, but reduced lipid accumulation and foam cell formation in the macrophages. PXR deficiency also led to decreased expression of the scavenger receptor CD36 and impaired lipid uptake in macrophages of the PXR^MyeLDLR^–/– mice. Further, RNA-Seq analysis indicated that treatment with a prototypical PXR ligand affects the expression of many atherosclerosis-related genes in macrophages in vitro. These findings reveal a pivotal role of myeloid PXR signaling in atherosclerosis development and suggest that PXR may be a potential therapeutic target in atherosclerosis management.

Cellular membranes are not homogenous mixtures of proteins; rather, they are segregated into microdomains on the basis of preferential association between specific lipids and proteins. These microdomains, called lipid rafts, are well known for their role in receptor signaling on the plasma membrane (PM) and are essential to such cellular functions as signal transduction and spatial organization of the PM. A number of disease states, including atherosclerosis and other cardiovascular disorders, may be caused by dysfunctional maintenance of lipid rafts. Lipid rafts do not occur only in the PM but also have been found in intracellular membranes and extracellular vesicles (EVs). Here, we focus on discussing newly discovered functions of lipid rafts and microdomains in intracellular membranes, including lipid and protein trafficking from the ER, Golgi bodies, and endosomes to the PM, and we examine lipid raft involvement in the production and composition of EVs. Because lipid rafts are small and transient, visualization remains challenging. Future work with advanced techniques will continue to expand our knowledge about the roles of lipid rafts in cellular functioning.

ABSTRACT

Transporters belonging to the chromosomally encoded resistance-nodulation-division (RND) superfamily mediate multidrug resistance in Gram-negative bacteria. However, the cotransfer of large gene clusters encoding RND-type pumps from the chromosome to a plasmid appears infrequent, and no plasmid-mediated RND efflux pump gene cluster has yet been found to confer resistance to tigecycline. Here, we identified a novel RND efflux pump gene cluster, designated tmexCD1-toprJ1, on plasmids from five pandrug-resistant Klebsiella pneumoniae isolates of animal origin. TMexCD1-TOprJ1 increased (by 4- to 32-fold) the MICs of tetracyclines (including tigecycline and eravacycline), quinolones, cephalosporins, and aminoglycosides for K. pneumoniae, Escherichia coli, and Salmonella. TMexCD1-TOprJ1 is closely related (64.5% to 77.8% amino acid identity) to the MexCD-OprJ efflux pump encoded on the chromosome of Pseudomonas aeruginosa. In an IncFIA plasmid, pHNAH8I, the tmexCD1-toprJ1 gene cluster lies adjacent to two genes encoding site-specific integrases, which may have been responsible for its acquisition. Expression of TMexCD1-TOprJ1 in E. coli resulted in increased tigecycline efflux and in K. pneumoniae negated the efficacy of tigecycline in an in vivo infection model. Expression of TMexCD1-TOprJ1 reduced the growth of E. coli and Salmonella but not K. pneumoniae. tmexCD1-toprJ1-positive Enterobacteriaceae isolates were rare in humans (0.08%) but more common in chicken fecal (14.3%) and retail meat (3.4%) samples. Plasmid-borne tmexCD1-toprJ1-like gene clusters were identified in sequences in GenBank from Enterobacteriaceae and Pseudomonas strains from multiple continents. The possibility of further global dissemination of the tmexCD1-toprJ1 gene cluster and its analogues in Enterobacteriaceae via plasmids may be an important consideration for public health planning.

IMPORTANCE In an era of increasing concerns about antimicrobial resistance, tigecycline is likely to have a critically important role in the treatment of carbapenem-resistant Enterobacteriaceae, the most problematic pathogens in human clinical settings—especially carbapenem-resistant K. pneumoniae. Here, we identified a new plasmid-borne RND-type tigecycline resistance determinant, TMexCD1-TOprJ1, which is widespread among K. pneumoniae isolates from food animals. tmexCD1-toprJ1 appears to have originated from the chromosome of a Pseudomonas species and may have been transferred onto plasmids by adjacent site-specific integrases. Although tmexCD1-toprJ1 still appears to be rare in human clinical isolates, considering the transferability of the tmexCD1-toprJ1 gene cluster and the broad substrate spectrum of TMexCD1-TOprJ1, further dissemination of this mobile tigecycline resistance determinant is possible. Therefore, from a "One Health" perspective, measures are urgently needed to monitor and control its further spread. The current low prevalence in human clinical isolates provides a precious time window to design and implement measures to tackle this.

ABSTRACT

The cell cycle is a critical component of cellular proliferation, differentiation, and response to stress, yet its role in the regulation of intracellular symbioses is not well understood. To explore host-symbiont cell cycle coordination in a marine symbiosis, we employed a model for coral-dinoflagellate associations: the tropical sea anemone Aiptasia (Exaiptasia pallida) and its native microalgal photosymbionts (Breviolum minutum and Breviolum psygmophilum). Using fluorescent labeling and spatial point-pattern image analyses to characterize cell population distributions in both partners, we developed protocols that are tailored to the three-dimensional cellular landscape of a symbiotic sea anemone tentacle. Introducing cultured symbiont cells to symbiont-free adult hosts increased overall host cell proliferation rates. The acceleration occurred predominantly in the symbiont-containing gastrodermis near clusters of symbionts but was also observed in symbiont-free epidermal tissue layers, indicating that the presence of symbionts contributes to elevated proliferation rates in the entire host during colonization. Symbiont cell cycle progression differed between cultured algae and those residing within hosts; the endosymbiotic state resulted in increased S-phase but decreased G₂/M-phase symbiont populations. These phenotypes and the deceleration of cell cycle progression varied with symbiont identity and host nutritional status. These results demonstrate that host and symbiont cells have substantial and species-specific effects on the proliferation rates of their mutualistic partners. This is the first empirical evidence to support species-specific regulation of the symbiont cell cycle within a single cnidarian-dinoflagellate association; similar regulatory mechanisms likely govern interpartner coordination in other coral-algal symbioses and shape their ecophysiological responses to a changing climate.

IMPORTANCE Biomass regulation is critical to the overall health of cnidarian-dinoflagellate symbioses. Despite the central role of the cell cycle in the growth and proliferation of cnidarian host cells and dinoflagellate symbionts, there are few studies that have examined the potential for host-symbiont coregulation. This study provides evidence for the acceleration of host cell proliferation when in local proximity to clusters of symbionts within cnidarian tentacles. The findings suggest that symbionts augment the cell cycle of not only their enveloping host cells but also neighboring cells in the epidermis and gastrodermis. This provides a possible mechanism for rapid colonization of cnidarian tissues. In addition, the cell cycles of symbionts differed depending on nutritional regime, symbiotic state, and species identity. The responses of cell cycle profiles to these different factors implicate a role for species-specific regulation of symbiont cell cycles within host cnidarian tissues.

ABSTRACT

Frequent and excessive use of antibiotics primes patients to Clostridioides difficile infection (CDI), which leads to fatal pseudomembranous colitis, with limited treatment options. In earlier reports, we used a drug repurposing strategy and identified amoxapine (an antidepressant), doxapram (a breathing stimulant), and trifluoperazine (an antipsychotic), which provided significant protection to mice against lethal infections with several pathogens, including C. difficile. However, the mechanisms of action of these drugs were not known. Here, we provide evidence that all three drugs offered protection against experimental CDI by reducing bacterial burden and toxin levels, although the drugs were neither bacteriostatic nor bactericidal in nature and had minimal impact on the composition of the microbiota. Drug-mediated protection was dependent on the presence of the microbiota, implicating its role in evoking host defenses that promoted protective immunity. By utilizing transcriptome sequencing (RNA-seq), we identified that each drug increased expression of several innate immune response-related genes, including those involved in the recruitment of neutrophils, the production of interleukin 33 (IL-33), and the IL-22 signaling pathway. The RNA-seq data on selected genes were confirmed by quantitative real-time PCR (qRT-PCR) and protein assays. Focusing on amoxapine, which had the best anti-CDI outcome, we demonstrated that neutralization of IL-33 or depletion of neutrophils resulted in loss of drug efficacy. Overall, our lead drugs promote disease alleviation and survival in the murine model through activation of IL-33 and by clearing the pathogen through host defense mechanisms that critically include an early influx of neutrophils.

IMPORTANCE Clostridioides difficile is a spore-forming anaerobic bacterium and the leading cause of antibiotic-associated colitis. With few therapeutic options and high rates of disease recurrence, the need to develop new treatment options is urgent. Prior studies utilizing a repurposing approach identified three nonantibiotic Food and Drug Administration-approved drugs, amoxapine, doxapram, and trifluoperazine, with efficacy against a broad range of human pathogens; however, the protective mechanisms remained unknown. Here, we identified mechanisms leading to drug efficacy in a murine model of lethal C. difficile infection (CDI), advancing our understanding of the role of these drugs in infectious disease pathogenesis that center on host immune responses to C. difficile. Overall, these studies highlight the crucial involvement of innate immune responses, as well as the importance of immunomodulation as a potential therapeutic option to combat CDI.

ABSTRACT

Clostridioides difficile is an important nosocomial pathogen that causes approximately 500,000 cases of C. difficile infection (CDI) and 29,000 deaths annually in the United States. Antibiotic use is a major risk factor for CDI because broad-spectrum antimicrobials disrupt the indigenous gut microbiota, decreasing colonization resistance against C. difficile. Vancomycin is the standard of care for the treatment of CDI, likely contributing to the high recurrence rates due to the continued disruption of the gut microbiota. Thus, there is an urgent need for the development of novel therapeutics that can prevent and treat CDI and precisely target the pathogen without disrupting the gut microbiota. Here, we show that the endogenous type I-B CRISPR-Cas system in C. difficile can be repurposed as an antimicrobial agent by the expression of a self-targeting CRISPR that redirects endogenous CRISPR-Cas3 activity against the bacterial chromosome. We demonstrate that a recombinant bacteriophage expressing bacterial genome-targeting CRISPR RNAs is significantly more effective than its wild-type parent bacteriophage at killing C. difficile both in vitro and in a mouse model of CDI. We also report that conversion of the phage from temperate to obligately lytic is feasible and contributes to the therapeutic suitability of intrinsic C. difficile phages, despite the specific challenges encountered in the disease phenotypes of phage-treated animals. Our findings suggest that phage-delivered programmable CRISPR therapeutics have the potential to leverage the specificity and apparent safety of phage therapies and improve their potency and reliability for eradicating specific bacterial species within complex communities, offering a novel mechanism to treat pathogenic and/or multidrug-resistant organisms.

IMPORTANCE Clostridioides difficile is a bacterial pathogen responsible for significant morbidity and mortality across the globe. Current therapies based on broad-spectrum antibiotics have some clinical success, but approximately 30% of patients have relapses, presumably due to the continued perturbation to the gut microbiota. Here, we show that phages can be engineered with type I CRISPR-Cas systems and modified to reduce lysogeny and to enable the specific and efficient targeting and killing of C. difficile in vitro and in vivo. Additional genetic engineering to disrupt phage modulation of toxin expression by lysogeny or other mechanisms would be required to advance a CRISPR-enhanced phage antimicrobial for C. difficile toward clinical application. These findings provide evidence into how phage can be combined with CRISPR-based targeting to develop novel therapies and modulate microbiomes associated with health and disease.

ABSTRACT

Bacillus subtilis contains two known cyclic di-GMP (c-di-GMP)-dependent receptors, YdaK and DgrA, as well as three diguanylate cyclases (DGCs): soluble DgcP and membrane-integral DgcK and DgcW. DgrA regulates motility, while YdaK is responsible for the formation of a putative exopolysaccharide, dependent on the activity of DgcK. Using single-molecule tracking, we show that a majority of DgcK molecules are statically positioned in the cell membrane but significantly less so in the absence of YdaK but more so upon overproduction of YdaK. The soluble domains of DgcK and of YdaK show a direct interaction in vitro, which depends on an intact I-site within the degenerated GGDEF domain of YdaK. These experiments suggest a direct handover of a second messenger at a single subcellular site. Interestingly, all three DGC proteins contribute toward downregulation of motility via the PilZ protein DgrA. Deletion of dgrA also affects the mobility of DgcK within the membrane and also that of DgcP, which arrests less often at the membrane in the absence of DgrA. Both, DgcK and DgcP interact with DgrA in vitro, showing that divergent as well as convergent direct connections exist between cyclases and their effector proteins. Automated determination of molecule numbers in live cells revealed that DgcK and DgcP are present at very low copy numbers of 6 or 25 per cell, respectively, such that for DgcK, a part of the cell population does not contain any DgcK molecule, rendering signaling via c-di-GMP extremely efficient.

IMPORTANCE Second messengers are free to diffuse through the cells and to activate all responsive elements. Cyclic di-GMP (c-di-GMP) signaling plays an important role in the determination of the life style transition between motility and sessility/biofilm formation but involves numerous distinct synthetases (diguanylate cyclases [DGCs]) or receptor pathways that appear to act in an independent manner. Using Bacillus subtilis as a model organism, we show that for two c-di-GMP pathways, DGCs and receptor molecules operate via direct interactions, where a synthesized dinucleotide appears to be directly used for the protein-protein interaction. We show that very few DGC molecules exist within cells; in the case of exopolysaccharide (EPS) formation via membrane protein DgcK, the DGC molecules act at a single site, setting up a single signaling pool within the cell membrane. Using single-molecule tracking, we show that the soluble DGC DgcP arrests at the cell membrane, interacting with its receptor, DgrA, which slows down motility. DgrA also directly binds to DgcK, showing that divergent as well as convergent modules exist in B. subtilis. Thus, local-pool signal transduction operates extremely efficiently and specifically.

ABSTRACT

While there is no effective vaccine against Chlamydia trachomatis infection, previous work has demonstrated the importance of C. trachomatis-specific CD4⁺ T cells (NR1 T cells) in pathogen clearance. Specifically, NR1 T cells have been shown to be protective in mice, and this protection depends on the host’s ability to sense the cytokine gamma interferon (IFN-). However, it is unclear what role NR1 production or sensing of IFN- plays in T cell homing to the genital tract or T cell-mediated protection against C. trachomatis. Using two-photon microscopy and flow cytometry, we found that naive wild-type (WT), IFN-^–/–, and IFN-R^–/– NR1 T cells specifically home to sections in the genital tract that contain C. trachomatis. We also determined that protection against infection requires production of IFN- from either NR1 T cells or endogenous cells, further highlighting the importance of IFN- in clearing C. trachomatis infection.

IMPORTANCE Chlamydia trachomatis is an important mucosal pathogen that is the leading cause of sexually transmitted bacterial infections in the United States. Despite this, there is no vaccine currently available. In order to develop such a vaccine, it is necessary to understand the components of the immune response that can lead to protection against this pathogen. It is well known that antigen-specific CD4⁺ T cells are critical for Chlamydia clearance, but the contexts in which they are protective or not protective are unknown. Here, we aimed to characterize the importance of gamma interferon production and sensing by T cells and the effects on the immune response to C. trachomatis. Our work here helps to define the contexts in which antigen-specific T cells can be protective, which is critical to our ability to design an effective and protective vaccine against C. trachomatis.