Leveraging Pyrazolium Ylide Reactivity to Access Indolizine and 1,2-Dihydropyrimidine Derivatives

N-Heterocyclic ylides are important synthetic precursors to rapidly build molecular complexity. Pyrazolium ylides have largely been unexplored, and we demonstrate their diverse utility in this report. We show that these readily accessible building blocks can be used to construct different heterocyclic skeletons by varying the coupling partner. Indolizines can be formed via an N-deletion type mechanism when reacting pyrazolium salts with electron deficient alkynes. 1,2-Dihydropyrimidines can be formed via a rearrangement mechanism when reacting pyrazolium ylides with isocyanates. These reactions enable access to valuable heteroarenes without the need for transition metal catalysis, high temperatures, or strong bases.

Utilising the intrinsic fluorescence of pomalidomide for imaging applications

Optimisation of protein degraders requires balancing multiple factors including potency, cell permeability and solubility. Here we show that the fluorescence of pomalidomide can be used in high-throughput screening assays to rapidly assess cellular penetration of degrader candidates. In addition, this technique can be paired with endocytosis inhibitors to gain insight into potential mechanisms of candidates entering a target cell. A model library of pomalidomide conjugates was synthesised and evaluated using high-throughput fluorescence microscopy. This technique based on intrinsic fluorescence can be used to guide rational design of pomalidomide conjugates without the need for additional labels or tags.

macroH2A2 antagonizes epigenetic programs of stemness in glioblastoma

Self-renewal is a crucial property of glioblastoma cells that is enabled by the choreographed functions of chromatin regulators and transcription factors. Identifying targetable epigenetic mechanisms of self-renewal could therefore represent an important step toward developing effective treatments for this universally lethal cancer. Here we uncover an epigenetic axis of self-renewal mediated by the histone variant macroH2A2. With omics and functional assays deploying patient-derived in vitro and in vivo models, we show that macroH2A2 shapes chromatin accessibility at enhancer elements to antagonize transcriptional programs of self-renewal. macroH2A2 also sensitizes cells to small molecule-mediated cell death via activation of a viral mimicry response. Consistent with these results, our analyses of clinical cohorts indicate that high transcriptional levels of this histone variant are associated with better prognosis of high-grade glioma patients. Our results reveal a targetable epigenetic mechanism of self-renewal controlled by macroH2A2 and suggest additional treatment approaches for glioblastoma patients.

Identification of ligand linkage vectors for the development of p300/CBP degraders

To develop new degrader molecules from an existing protein ligand a linkage vector must be identified and then joined with a suitable E3 ligase without disrupting binding to the respective...

Regioselective Synthesis of C3-Hydroxyarylated Pyrazoles

Pyrazoles are ubiquitous structures in medicinal chemistry. We report the first regioselective route to C3-hydroxyarylated pyrazoles obtained through reaction of pyrazole N-oxides with arynes using mild conditions. Importantly, this method does not require the C4 and C5 positions of the pyrazole to be functionalized to observe regioselectivity. Using this method, we completed the synthesis of a recently reported JAK 1/2 inhibitor. Our synthesis produces the desired product in 4 steps from commercially available starting materials.

Metformin Prevents Hyperglycemia-Associated, Oxidative Stress-Induced Vascular Endothelial Dysfunction: Essential Role for the Orphan Nuclear Receptor Human Nuclear Receptor 4A1 (Nur77)

Vascular pathology is increased in diabetes because of reactive-oxygen-species (ROS)-induced endothelial cell damage. We found that in vitro and in a streptozotocin diabetes model in vivo, metformin at diabetes-therapeutic concentrations (1-50 µM) protects tissue-intact and cultured vascular endothelial cells from hyperglycemia/ROS-induced dysfunction typified by reduced agonist-stimulated endothelium-dependent, nitric oxide-mediated vasorelaxation in response to muscarinic or proteinase-activated-receptor 2 agonists. Metformin not only attenuated hyperglycemia-induced ROS production in aorta-derived endothelial cell cultures but also prevented hyperglycemia-induced endothelial mitochondrial dysfunction (reduced oxygen consumption rate). These endothelium-protective effects of metformin were absent in orphan-nuclear-receptor Nr4a1-null murine aorta tissues in accord with our observing a direct metformin-Nr4a1 interaction. Using in silico modeling of metformin-NR4A1 interactions, Nr4a1-mutagenesis, and a transfected human embryonic kidney 293T cell functional assay for metformin-activated Nr4a1, we identified two Nr4a1 prolines, P505/P549 (mouse sequences corresponding to human P501/P546), as key residues for enabling metformin to affect mitochondrial function. Our data indicate a critical role for Nr4a1 in metformin's endothelial-protective effects observed at micromolar concentrations, which activate AMPKinase but do not affect mitochondrial complex-I or complex-III oxygen consumption rates, as does 0.5 mM metformin. Thus, therapeutic metformin concentrations requiring the expression of Nr4a1 protect the vasculature from hyperglycemia-induced dysfunction in addition to metformin's action to enhance insulin action in patients with diabetes. SIGNIFICANCE STATEMENT: Metformin improves diabetic vasodilator function, having cardioprotective effects beyond glycemic control, but its mechanism to do so is unknown. We found that metformin at therapeutic concentrations (1-50µM) prevents hyperglycemia-induced endothelial dysfunction by attenuating reactive oxygen species-induced damage, whereas high metformin (>250 µM) impairs vascular function. However, metformin's action requires the expression of the orphan nuclear receptor NR4A1/Nur77. Our data reveal a novel mechanism whereby metformin preserves diabetic vascular endothelial function, with implications for developing new metformin-related therapeutic agents.

Rapid synthesis of pomalidomide-conjugates for the development of protein degrader libraries

Current methods for the preparation of heterobifunctional pomalidomide-conjugates rely on methods that are often low yielding and produce intractable byproducts. Herein we describe our strategy for the reliable and succinct preparation of pomalidomide-linkers which is essential to the formation of these conjugates. We present the preparation of 18 pomalidomide-linkers in high yield compared to current literature methods. Our findings show that secondary amines consistently afford greater yields than their primary counterparts, a trend that we were able to exploit in the synthesis of several new pomalidomide homo-dimers in enhanced yields compared to similar literature syntheses. This trend was further utilised to develop the first one-pot synthesis of JQ1-pomalidomide conjugates in yields up to 62%, providing a method that is suited to rapid preparation of conjugate libraries as is frequently required for the development of new protein degraders.

Current methods for the preparation of heterobifunctional pomalidomide-conjugates rely on methods that are often low yielding and produce intractable byproducts. Herein we describe our strategy for the succinct preparation of pomalidomide-linkers.

Pannexin 1 Channels as a Therapeutic Target: Structure, Inhibition, and Outlook

Pannexin 1 (Panx1) channels are transmembrane proteins that release adenosine triphosphate and play an important role in intercellular communication. They are widely expressed in somatic and nervous system tissues, and their activity has been associated with many pathologies such as stroke, epilepsy, inflammation, and chronic pain. While there are a variety of small molecules known to inhibit Panx1, currently little is known about the mechanism of channel inhibition, and there is a dearth of sufficiently potent and selective drugs targeting Panx1. Herein we provide a review of the current literature on Panx1 structural biology and known pharmacological agents that will help provide a basis for rational development of Panx1 chemical modulators.

Beyond geminal diesters: increasing the scope of metal-mediated vinylcyclopropane annulations while decreasing pre-activation

This review covers the transition metal mediated annulation chemistry of vinylcyclopropanes with an emphasis on non-donor–acceptor examples, and where pertinent, examples of natural product syntheses are shown.

Divergent Photocyclization/1,4-Sigmatropic Rearrangements for the Synthesis of Sesquiterpenoid Derivatives

Combined experimental and computational efforts have demonstrated the utility of divergent photocyclization/1,4-sigmatropic rearrangement reactions for developing a general strategy toward the synthesis of cubebane-, spiroaxane-, and guaiane-type sesquiterpenes and related analogues. The configuration of the bridgehead substituent, the choice of solvent, and the wavelength of irradiation all impact diastereoselectivity in this tandem reaction process.

Generation of Benzyne Species from Diphenylphosphoryl Derivatives: Simultaneous Exchange of Three Functional Groups

Interaction of (2-diphenylphosphoryl-3-iodo-4-methoxy-phenyl) methanol with NaH in DMF at ambient temperature results in the generation of benzyne intermediates that can be trapped by furan or DMF. Trapping with DMF forms 3-(dimethylaminomethyl)-2-hydroxy-6-methoxybenzaldehyde demonstrating the simultaneous exchange of three functionalities in a single step. The presence of the alkoxy substituent adjacent to iodine is critical for high regioselectivity addition of DMF. The corresponding bromide or triflate can be used in place of the iodide with equal efficiency. This methodology was used to synthesize the reported structure of gigasol and leading to a structural reassignment of this biscoumarin natural product.

Natural-Product-Derived Transient Receptor Potential Melastatin 8 (TRPM8) Channel Modulators

A library of novel structural hybrids of menthol and cubebol was tested for each derivative's ability to interact with the transient receptor potential subfamily melastatin member 8 (TRPM8) channel. This structure-activity relationship study revealed three potent modulators of the TRPM8 ion channel: a novel agonist (4) with an EC50 value of 11 ± 1 μM, an antagonist (15) with an IC50 value of 2 ± 1 μM, and an allosteric modulator (21) that minimized channel desensitization toward menthol. Each of these novel exocyclic olefin analogues of menthol is readily accessible by synthesis and was tested using Ca(2+) assays and electrophysiology.

Thiaporphyrin-mediated photocatalysis using red light

Thiophene-containing porphyrin compounds are capable of catalytic, photo-reductive dehalogenation on an array of α-halo ketone model substrates with low catalyst loadings (0.1 mol%), in the presence of low energy, red light (>645 nm).

Elucidating absolute configuration of unsaturated alcohols via enantioselective acylation reactions

Enantioselective nucleophilic acylation catalysis provides a simple method of determining absolute configuration for unsaturated alcohols. Extension of this technique to natural products and synthetic compounds, as well as current limitations of this approach, are also described.

Structure function relationship of inducer peptide pheromones involved in bacteriocin production in Carnobacterium maltaromaticum and Enterococcus faecium

The production of several bacteriocins in lactic acid bacteria is regulated by inducer peptide pheromones that specifically interact with their cognate bacterial receptor. These peptide pheromones are between 19 and 27 aa long and contain a conserved (V/I)-X-X-X-F sequence followed by positively charged residues in the C-terminal domain. CbaX and EntF are peptide pheromones that share similarity and are involved in the production of carnobacteriocin A in Carnobacterium maltaromaticum LV17A and enterocins A and B in Enterococcus faecium CTC492, respectively. CbaX, EntF and two hybrids, CbaX::EntF and EntF::CbaX, were tested for pheromone activity in LV17A and CTC492. EntF and EntF::CbaX only induced bacteriocin production in CTC492, whereas CbaX and CbaX::EntF induced carnobacteriocin A production in LV17A and, at high concentrations, also cross-induced enterocin production in CTC492. Various peptide fragments of CbaX and EntF were made for further structure-function analysis. The C-terminal fragments, but not the N-terminal fragments, were able to effect bacteriocin induction. The 10-mer EntF(16-25), derived from the C-terminal domain of EntF, showed pheromone activity in LV17A. In contrast, the C-terminal 9-mer of CbaX, CbaX(16-24), inhibited pheromone activity in both LV17A and CTC492. EntF(16-25) and CbaX(16-24) differ by two amino acids. Changing either one of these abolished pheromone activity as well as the ability to inhibit pheromone activity. These results indicate that the C-terminal domain of these peptide pheromones interacts relatively non-specifically with the receptor, and that induction is greatly facilitated by the N-terminal domain that recognizes specifically its cognate receptor.

Antimicrobial leucocin analogues with a disulfide bridge replaced by a carbocycle or by noncovalent interactions of allyl glycine residues

The type IIa bacteriocins are antimicrobial peptides isolated from lactic acid bacteria that act as food preservation agents and have nanomolar activity against pathogens such as Listeria monocytogenes. Previous reports with mutant bacteriocins indicate that the conserved disulfide bridge between cysteine residues 9 and 14 in bacteriocins such as leucocin A (1) is critical for antibiotic properties, which are mediated by target membrane receptor proteins belonging to the mannose phosphotransferase (mpt) system. To examine whether the disulfide can be replaced by an olefin moiety, [9,14]-dicarba leucocin A (4) was made by on-resin ring closing metathesis of allyl glycine residues using a new protocol suitable for larger hydrophobic peptides. Carbocyclic analogue 4 still displays nanomolar activity but is about 10-fold less potent than 1. Surprisingly, the acyclic [9,14]-diallyl leucocin A (5) displays even higher antibiotic activity than 4 and is as effective as the parent, leucocin A (1). We attribute this activity to hydrophobic intermolecular interactions of the diallyl side chains of the acyclic bacteriocin 5 that assist realization of the correct conformation at the receptor active site. Such substitutions in other systems may allow linear acyclic peptides to mimic the biological activity of natural disulfide ring-containing parents.

Multiple On-Resin Olefin Metathesis to Form Ring-Expanded Analogues of the Lantibiotic Peptide, Lacticin 3147 A2

Chemical synthesis of lantibiotic analogues wherein monosulfide bridges are replaced with other groups can shed light on structure-activity relationships and generate variants that are resistant to aerobic oxidation and have better metabolic stability. This work describes the first complete synthesis of a carbocyclic lantibiotic analogue 2, using sequential on-resin ring-closing olefin metathesis and solution-phase peptide synthesis. The methodology described should find wide application for the preparation of rigidified peptidomimetics containing multiple carbocyclic rings. [structure: see text].

Production of piscicolin 126 by Carnobacterium maltaromaticum UAL26 is controlled by temperature and induction peptide concentration

Carnobacterium maltaromaticum UAL26 produces the antimicrobial peptides (bacteriocins) piscicolin 126, first isolated from C. maltaromaticum JG126, and carnobacteriocin BM1, first isolated from C. maltaromaticum LV17. C. maltaromaticum UAL26 is especially inhibitory to strains of Listeria monocytogenes. Bacteriocin activity is not observable in the supernatant of cultures of UAL26 grown in liquid media at 25 degrees C, but at temperatures less than 19 degrees C bacteriocin activity can be detected. In contrast to JG126, the piscicolin 126 operon is downregulated in UAL26 at higher temperature, and piscicolin 126 mRNA is not detected when UAL26 is grown at 25 degrees C. Bacteriocin production in UAL26 grown at 15 degrees C can be induced by addition of 10(-10) M of chemically synthesized piscicolin 126 induction peptide (PisN). However, induction of bacteriocin production in UAL26 grown at 25 degrees C requires 10(-7) M of PisN. The sequence of the piscicolin 126 operon in UAL26 contains 34 single nucleotide differences compared with the piscicolin 126 operon in JG126, including single nucleotide differences in the immunity, histidine kinase, dedicated ABC-transporter and accessory genes, as well as a single nucleotide deletion in the transport accessory gene. This deletion causes a frameshift, resulting in truncation of the PisE transport accessory protein in UAL26.

Photolysis of diacyl peroxides: a radical-based approach for the synthesis of functionalized amino acids

[reaction: see text] Photolysis of the amino acid derived symmetrical and unsymmetrical diacyl peroxides at 254 nm at low temperature (-78 to -196 degrees C) generates various bis(amino acids) in a concise manner and with orthogonal protection. The methodology was applied to the synthesis of (4R)-5-propyl-L-leucine (PrLeu), a component of HUN-7293.

Academic models for practice relief, recruitment, and retention at the University of New Mexico Medical Center and East Carolina University School of Medicine

Locum tenens programs were independently developed by the University of New Mexico Health Sciences Center and East Carolina University School of Medicine to address health care needs within their states. The programs represent distinct models to provide locum tenens services for practices in rural and medically underserved regions through collaboration with stage government representatives and agencies. Differences between programs include years of operation, days of coverage provided, types of learners and providers involved, sources of funding, costs of the programs, and extent of institutional support. Common beneficial outcomes of the programs include coverage for struggling practices, training in rural medicine for locum tenens providers, recruitment of physicians to rural practice sites, and improved relationships with program partners. Adequate funding and institutional support are essential for success of locum tenens programs.

Emergency department use by family practice patients in an academic health center

BACKGROUND AND OBJECTIVES

With the proliferation of managed care, efforts are being made to reduce emergency department (ED) use after hours and eliminate unnecessary ambulatory visits during office hours. This study characterized the after-hours ED use by a family practice residency patient population and determined differences in appropriate ED use by patients calling ahead versus those arriving at the ED without calling first. American College of Emergency Physicians guidelines were used to define appropriateness of visit.

METHODS

A retrospective ED chart and on-call log review were used to obtain data.

RESULTS

A random sampling of family practice patients from January 1993 to December 1994 (n = 332) showed that, overall, 62% of patients did not call prior to their ED visit. Calling ahead was not associated with more appropriate ED use. Of those who called ahead, 63% had an appropriate ED visit, compared with 61% of those who did not call ahead. Men were more likely to appropriately use the ED than women. Patients age > 64 were more likely to have appropriate ED visits than other age groups.

CONCLUSIONS

We found no relationship between calling ahead and appropriate ED use. Possible explanations include that resident physicians are inexperienced and may be uncomfortable with telephone triage due to a lack of formal telephone management training. Patients may misrepresent the severity of their illness. Further, a patient who wants to be seen after hours must be seen for medical legal reasons. Interestingly, privately insured or Medicare recipients were more likely to use the ED appropriately. This association may suggest that fiscal accountability contributes to appropriate utilization, a scenario likely to change as managed care organizes Medicaid and indigent patients.

Children and the influence of the media

Violence, increased sexual activity, and antisocial behaviors involving children and adolescents are being blamed on the media. American children and adolescents spend 21 to 23 hours per week viewing television. Children will see 200,000 violent acts on television by age 18 and view over 14,000 sexual situations and innuendoes per year. The primary care physician can play a crucial role in reducing the potential negative influence of the media on children.

A rural emergency department

The appropriate use of emergency departments is of growing concern. By knowing which patients are more likely to make inappropriate visits to these departments, efforts can be directed to encourage more suitable care. Our study was done in a rural county hospital in eastern New Mexico. Data were collected from all emergency department visits over a 4-week period. Patient and physician questionnaires were administered to assess aspects of emergency department use, including appropriateness based on published criteria, physicians' opinion of appropriateness, groups who made inappropriate visits, and the perception of the need for and the urgency of a visit. We found that 32% of visits were inappropriate based on published criteria and 24% were considered inappropriate by physician opinion. Two groups with a high rate of inappropriate visits were Hispanics and Medicaid recipients. Patients and physicians have differing opinions of the urgency of a visit and of how soon medical treatment is required. To decrease the frequency of inappropriate use of emergency departments, educational efforts should be focused on the subgroups with high rates of such use.

Benign conditions of the external genitalia

Benign mass lesions of the scrotum include spermatocele, hydrocele, varicocele, sperm granuloma after vasectomy, tuberculous masses, and epididymitis. A careful history and physical examination are paramount in making the diagnosis of a scrotal mass. Referral to a urologist is indicated for masses that do not transilluminate, are solid or fixed to the testicle, or for epididymitis that does not respond to antibiotics. Hydroceles associated with significant symptoms or with hernia and varicoceles with symptoms or associated infertility are also reasons for referral. After a sexual history is obtained, lesions of the anogenital area should be carefully inspected. Male partners of women with cervical dysplasia should be examined for evidence of human papillomavirus infection. Treatment of anogenital lesions resulting from a sexually transmitted disease involves both partners.