Chemical scaffold recycling: Structure-guided conversion of an HIV integrase inhibitor into a potent influenza virus RNA-dependent RNA polymerase inhibitor designed to minimize resistance potential.

Influenza is one of the leading causes of disease-related mortalities worldwide. Several strategies have been implemented during the past decades to hinder the replication cycle of influenza viruses, all of which have resulted in the emergence of resistant virus strains. The most recent example is baloxavir marboxil, where a single mutation in the active site of the target endonuclease domain of the RNA-dependent-RNA polymerase renders the recent FDA approved compound ∼1000-fold less effective. Raltegravir is a first-in-class HIV inhibitor that shows modest activity to the endonuclease. Here, we have used structure-guided approaches to create rationally designed derivative molecules that efficiently engage the endonuclease active site. The design strategy was driven by our previously published structures of endonuclease-substrate complexes, which allowed us to target functionally conserved residues and reduce the likelihood of resistance mutations. We succeeded in developing low nanomolar equipotent inhibitors of both wild-type and baloxavir-resistant endonuclease. We also developed macrocyclic versions of these inhibitors that engage the active site in the same manner as their 'open' counterparts but with reduced affinity. Structural analyses provide clear avenues for how to increase the affinity of these cyclic compounds.

The Predictive Value of the Residency AOBFP In-Service Exam, Produced and Administered by ACOFP.

BACKGROUND AND OBJECTIVES: Board certification is acknowledged as the mainstay for ensuring quality physician-delivered health care within medical specialties. The American College of Osteopathic Family Physicians (ACOFP) administers the American Osteopathic Board of Family Physicians' (AOBFP) In-Service Examination (ISE) to provide residents and program directors with a formative examination to assess competency and preparation for successful completion of the AOBFP certifying examination (CE). Unique assessment processes are integral to monitoring development of the osteopathic family physician throughout training and into practice, and to verify their competency for the safety and protection of the public. This study sought to investigate whether performance on the AOBFP ISE predicted performance on the AOBFP CE, and thereby successfully equipped residents to safely enter medical practice. METHODS: In 2020, data from 1,893 PGY-1 through PGY-3 residents (2016-2018), whose ISE scores could be matched with scores on the AOBFP initial board CE, were analyzed for this study. RESULTS: Correlations among ISE administrations across 3 years of postgraduate medical education were in the mid-to-high .6 range; the ISE scores correlated with CE scores in the mid .4 to high .5 range. Less reliable measures of positive predictive value were 0.99, and sensitivity was 0.91. CONCLUSIONS: Results suggest that ISE administrations during residency training are effective in developing remediation strategies for subsequent successful CE performance. The inclusion of osteopathic principles in the AOBFP CE necessitates inclusion of osteopathic content in resident training exams like ISE.

Targeting KDM4 for treating PAX3-FOXO1-driven alveolar rhabdomyosarcoma.

Chimeric transcription factors drive lineage-specific oncogenesis but are notoriously difficult to target. Alveolar rhabdomyosarcoma (RMS) is an aggressive childhood soft tissue sarcoma transformed by the pathognomonic Paired Box 3-Forkhead Box O1 (PAX3-FOXO1) fusion protein, which governs a core regulatory circuitry transcription factor network. Here, we show that the histone lysine demethylase 4B (KDM4B) is a therapeutic vulnerability for PAX3-FOXO1+ RMS. Genetic and pharmacologic inhibition of KDM4B substantially delayed tumor growth. Suppression of KDM4 proteins inhibited the expression of core oncogenic transcription factors and caused epigenetic alterations of PAX3-FOXO1-governed superenhancers. Combining KDM4 inhibition with cytotoxic chemotherapy led to tumor regression in preclinical PAX3-FOXO1+ RMS subcutaneous xenograft models. In summary, we identified a targetable mechanism required for maintenance of the PAX3-FOXO1-related transcription factor network, which may translate to a therapeutic approach for fusion-positive RMS.

Post-concussive syndrome to primary central nervous system lymphoma: An insidious presentation.

Primary central nervous system lymphoma (PCNSL) and central neurogenic hyperventilation (CNH) are both rare occurrences, especially when associated with Epstein-Barr Virus (EBV). We report a case of an immunocompetent individual who presented to the emergency department (ED) with vague neurological symptoms found to have an EBV-associated PCNSL complicated by CNH. This rare occurrence had an insidious presentation initially mistaken for "post-concussive syndrome" at an outside ED. Insidious neurological malignancies, posterior strokes, intracranial hematomas, and other life-threatening pathologies should always be on the differential in patients presenting to the ED with falls with associated neurological symptoms, especially with unexplained blood gas abnormalities.

Gastrogastric intussusception in the setting of a small bowel obstruction.

Adult patients comprise 5% of all intussusceptions with 2 to 3 cases per million per year. Of those, only 10% of adult intussusceptions involve the stomach. Gastrogastric intussusceptions are most often associated with lead points caused by gastric neoplasms, with a few caused by hiatal hernias or ascites. Unlike children, adult intussusceptions are rarely idiopathic. Herein, a case is presented of a 65-year-old male who was found to have a gastrogastric intussusception in the setting of a small bowel obstruction with no evidence of neoplasm confirmed by biopsy. The patient initially presented to the emergency department with nausea, emesis, and epigastric pain. Given that almost all reported cases have been associated with gastric neoplasms, this case shows an unusual phenomenon of gastrogastric intussusception that has not reported before. Furthermore, our case offers a different etiology of gastrogastric intussusception in adults other than being due to a gastric neoplasm.

17-DMAG dually inhibits Hsp90 and histone lysine demethylases in alveolar rhabdomyosarcoma.

Histone lysine demethylases (KDMs) play critical roles in oncogenesis and therefore may be effective targets for anticancer therapy. Using a time-resolved fluorescence resonance energy transfer demethylation screen assay, in combination with multiple orthogonal validation approaches, we identified geldanamycin and its analog 17-DMAG as KDM inhibitors. In addition, we found that these Hsp90 inhibitors increase degradation of the alveolar rhabdomyosarcoma (aRMS) driver oncoprotein PAX3-FOXO1 and induce the repressive epigenetic mark H3K9me3 and H3K36me3 at genomic loci of PAX3-FOXO1 targets. We found that as monotherapy 17-DMAG significantly inhibits expression of PAX3-FOXO1 target genes and multiple oncogenic pathways, induces a muscle differentiation signature, delays tumor growth and extends survival in aRMS xenograft mouse models. The combination of 17-DMAG with conventional chemotherapy significantly enhances therapeutic efficacy, indicating that targeting KDM in combination with chemotherapy may serve as a therapeutic approach to PAX3-FOXO1-positive aRMS.

Potent, Irreversible Inhibition of Human Carboxylesterases by Tanshinone Anhydrides Isolated from Salvia miltiorrhiza ("Danshen").

The roots of Salvia miltiorrhiza ("Danshen") have been used in Chinese herbal medicine for centuries for a host of different conditions. While the exact nature of the active components of this material are unknown, large amounts of tanshinones are present in extracts derived from these samples. Recently, the tanshinones have been demonstrated to be potent human carboxylesterase (CE) inhibitors, with the ability to modulate the biological activity of esterified drugs. During the course of these studies, we also identified more active, irreversible inhibitors of these enzymes. We have purified, identified, and synthesized these molecules and confirmed them to be the anhydride derivatives of the tanshinones. These compounds are exceptionally potent inhibitors ( Ki < 1 nM) and can inactivate human CEs both in vitro and in cell culture systems and can modulate the metabolism of the esterified drug oseltamivir. Therefore, the coadministration of Danshen extracts with drugs that contain the ester chemotype should be minimized since, not only is transient inhibition of CEs observed with the tanshinones, but also prolonged irreversible inhibition arises via interaction with the anhydrides.

Competence Revisited in a Rural Context.

BACKGROUND AND OBJECTIVES: General competencies developed in undergraduate and graduate medical education are sometimes promoted as applicable in any practice context. However, rural practice presents challenges and opportunities that may require unique training. The objectives of this national survey of both undergraduate and graduate medical educators and practicing physicians were to further develop a previously published list of competency domains for working in rural communities and to assess their relative importance in education and practice. METHODS: Using six rural competency domains first refined with a national group at the Society of Teachers of Family Medicine Annual Meeting in Baltimore in 2008, the authors employed a snowball strategy to survey medical educators and physicians regarding the importance and relevance of this list and to solicit additional domains and competencies. RESULTS: All six domains were considered important, with average responses for each domain ranging from 4.16 to 4.78 on a 5-point Likert scale (1-not important; 5-extremely important). Unique relevance to rural practice was more varied, with average responses for domains ranging from 2.36 to 3.6 (1-not at all unique; 5-extremely unique). Analysis of free text responses identified two important new domains-Comprehensiveness and Agency/Courage-and provided clarification of some competencies within existing domains. CONCLUSIONS: This study validates and further elaborates dimensions of competence believed to be important in rural practice. The authors propose these domains as a common language and framework for addressing the unique challenges and opportunities that training and practicing in a rural setting present.

Selective Inhibitors of Human Liver Carboxylesterase Based on a ß-Lapachone Scaffold: Novel Reagents for Reaction Profiling.

Carboxylesterases (CEs) are ubiquitous enzymes that are responsible for the metabolism of xenobiotics, including drugs such as irinotecan and oseltamivir. Inhibition of CEs significantly modulates the efficacy of such agents. We report here that ß-lapachone is a potent, reversible CE inhibitor with Ki values in the nanomolar range. A series of amino and phenoxy analogues have been synthesized, and although the former are very poor inhibitors, the latter compounds are highly effective in modulating CE activity. Our data demonstrate that tautomerism of the amino derivatives to the imino forms likely accounts for their loss in biological activity. A series of N-methylated amino derivatives, which are unable to undergo such tautomerism, were equal in potency to the phenoxy analogues and demonstrated selectivity for the liver enzyme hCE1. These specific inhibitors, which are active in cell culture models, will be exceptionally useful reagents for reaction profiling of esterified drugs in complex biological samples.

Rebaudiosides T and U, minor C-19 xylopyranosyl and arabinopyranosyl steviol glycoside derivatives from Stevia rebaudiana (Bertoni) Bertoni.

Two diterpene glycosides were isolated from a commercial Stevia rebaudiana leaf extract. One was found to be 13-[(2-O-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(2-O-ß-d-xylopyranosyl-3-O-ß-d-glucopyranosyl- ß-d-glucopyranosyl) ester (rebaudioside T), whereas the other was determined to be 13-[(2-O-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(6-O-α-l-arabinopyranosyl-ß-d-glucopyranosyl) ester (rebaudioside U). In addition, five C-19 sugar free derivatives were prepared and identified as follows: 13-[(2-O-α-l-rhamnopyranosyl-ß-d-glucopyranosyl)]oxy]kaur-16-en-19-oic acid (dulcoside A1); 13-[(2-O-ß-d-xylopyranosy-3-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]kaur-16-en-19-oic acid; 13-[(2-O-ß-d-xylopyranosyl-ß-d-glucopyranosyl-)oxy]kaur-16-en-19-oic acid; 13-[(2-O-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-xylopyranosyl-)oxy]kaur-16-en-19-oic acid (rebaudioside R1) and 13-[(2-O-6-deoxy-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]kaur-16-en-19-oic acid, respectively. Chemical structures were determined by NMR experiments. HPLC analyses were also useful to differentiate different steviol-C13 sugar substituent patterns by elution position.

SB-224289 Antagonizes the Antifungal Mechanism of the Marine Depsipeptide Papuamide A.

In order to expand the repertoire of antifungal compounds a novel, high-throughput phenotypic drug screen targeting fungal phosphatidylserine (PS) synthase (Cho1p) was developed based on antagonism of the toxin papuamide A (Pap-A). Pap-A is a cyclic depsipeptide that binds to PS in the membrane of wild-type Candida albicans, and permeabilizes its plasma membrane, ultimately causing cell death. Organisms with a homozygous deletion of the CHO1 gene (cho1ΔΔ) do not produce PS and are able to survive in the presence of Pap-A. Using this phenotype (i.e. resistance to Pap-A) as an indicator of Cho1p inhibition, we screened over 5,600 small molecules for Pap-A resistance and identified SB-224289 as a positive hit. SB-224289, previously reported as a selective human 5-HT1B receptor antagonist, also confers resistance to the similar toxin theopapuamide (TPap-A), but not to other cytotoxic depsipeptides tested. Structurally similar molecules and truncated variants of SB-224289 do not confer resistance to Pap-A, suggesting that the toxin-blocking ability of SB-224289 is very specific. Further biochemical characterization revealed that SB-224289 does not inhibit Cho1p, indicating that Pap-A resistance is conferred by another undetermined mechanism. Although the mode of resistance is unclear, interaction between SB-224289 and Pap-A or TPap-A suggests this screening assay could be adapted for discovering other compounds which could antagonize the effects of other environmentally- or medically-relevant depsipeptide toxins.

Diversity-oriented natural product platform identifies plant constituents targeting Plasmodium falciparum.

BACKGROUND: A diverse library of pre-fractionated plant extracts, generated by an automated high-throughput system, was tested using an in vitro anti-malarial screening platform to identify known or new natural products for lead development. The platform identifies hits on the basis of in vitro growth inhibition of Plasmodium falciparum and counter-screens for cytotoxicity to human foreskin fibroblast or embryonic kidney cell lines. The physical library was supplemented by early-stage collection of analytical data for each fraction to aid rapid identification of the active components within each screening hit. RESULTS: A total of 16,177 fractions from 1300 plants were screened, identifying several P. falciparum inhibitory fractions from 35 plants. Although individual fractions were screened for bioactivity to ensure adequate signal in the analytical characterizations, fractions containing less than 2.0 mg of dry weight were combined to produce combined fractions (COMBIs). Fractions of active COMBIs had EC50 values of 0.21-50.28 and 0.08-20.04 µg/mL against chloroquine-sensitive and -resistant strains, respectively. In Berberis thunbergii, eight known alkaloids were dereplicated quickly from its COMBIs, but berberine was the most-active constituent against P. falciparum. The triterpenoids α-betulinic acid and ß-betulinic acid of Eugenia rigida were also isolated as hits. Validation of the anti-malarial discovery platform was confirmed by these scaled isolations from B. thunbergii and E. rigida. CONCLUSIONS: These results demonstrate the value of curating and exploring a library of natural products for small molecule drug discovery. Attention given to the diversity of plant species represented in the library, focus on practical analytical data collection, and the use of counter-screens all facilitate the identification of anti-malarial compounds for lead development or new tools for chemical biology.

Rebaudiosides R and S, Minor Diterpene Glycosides from the Leaves of Stevia rebaudiana.

Two new diterpene glycosides have been isolated from a commercial extract of the leaves of Stevia rebaudiana. Compound 1 was shown to be 13-[(2-O-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-xylopyranosyl)oxy]ent-kaur-16-en-19-oic acid ß-d-glucopyranosyl ester (rebaudioside R), while compound 2 was determined to be 13-[(2-O-α-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid 2-O-α-l-rhamnopyranosyl-ß-d-glucopyranosyl ester (rebaudioside S). Six additional known compounds were identified, dulcoside B, 13-[(2-O-ß-d-xylopyranosyl-ß-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid ß-d-glucopyranosyl ester, eugenol diglucoside, rebaudioside G, 13-[(2-O-6-deoxy-ß-d-glucopyranosyl-3-O-ß-d-glucopyranosyl-ß-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid ß-d-glucopyranosyl ester, and rebaudioside D (3), respectively. The structures of 1 and 2 were determined based on comprehensive 1D and 2D NMR (COSY, HSQC, and HMBC) studies. A high-quality crystal of compound 3 allowed confirmation of its structure by X-ray diffraction.

A Brief Report Describing the Union of Medical Training and Agricultural Health.

This brief report describes a mutually beneficial partnership forged to extend agricultural medicine training to physicians, nurses, veterinarians, public health workers, health care professionals, medical residents, and students. Agricultural Medicine: Occupational and Environmental Health for Rural Health Professionals originated at the University of Iowa, Iowa's Center for Agricultural Safety and Health, and the Great Plains Center for Agricultural Health. Through a National Institute for Occupational Safety and Health (NIOSH)-funded Training Project Grant, The University of Texas Health Northeast worked with the University of Iowa and regional experts to adapt the agricultural medicine content for the southwestern United States. Further partnerships were developed with the Southwest Center for Agricultural Health, Injury Prevention and Education, The University of North Texas Health Science Center College of Osteopathic Medicine, and the Texas Rural Health Association to extend the reach of this training to other important stakeholders. Each of the collaborators offered unique resources to the coordination of the agricultural medicine course. Likewise, each organization benefited from extending regionally relevant agricultural medicine training to current and future health care providers. The long-term goal for the partnership is to train a broad array of health care providers with the basics of anticipation, recognition, diagnosis, treatment, and the prevention of occupational and environmental illnesses and injuries within rural and agricultural communities, customized to the Southwest Region. This brief descriptive report highlights the process by which strategic partners collaborated to conduct a regional agricultural medicine course, such that other organizations interested in offering a similar training might gain insight to best practices from our experience.

Evolution of AOA specialty board certification.

The launch of Osteopathic Continuous Certification (OCC) signifes the next stage of the osteopathic board certification process. The OCC process replaces the old recertification system for all osteopathic physicians who earned time-limited certificates from American Osteopathic Association (AOA) certifying boards. All 18 AOA certifying boards are now engaged in the continuous certification process. With the advent of any new system, many questions and concerns will arise. The AOA Bureau of Osteopathic Specialists continues to evaluate its new certification system and prepare for modifcations in response to this feedback.