Characterization of the In Vivo Deuteration of Native Phospholipids by Mass Spectrometry Yields Guidelines for Their Regiospecific Customization.

Customization of deuterated biomolecules is vital for many advanced biological experiments including neutron scattering. However, because it is challenging to control the proportion and regiospecificity of deuterium incorporation in live systems, often only two or three synthetic lipids are mixed together to form simplistic model membranes. This limits the applicability and biological accuracy of the results generated with these synthetic membranes. Despite some limited prior examination of deuterating Escherichia coli lipids in vivo, this approach has not been widely implemented. Here, an extensive mass spectrometry-based profiling of E. coli phospholipid deuteration states with several different growth media was performed, and a computational method to describe deuterium distributions with a one-number summary is introduced. The deuteration states of 36 lipid species were quantitatively profiled in 15 different growth conditions, and tandem mass spectrometry was used to reveal deuterium localization. Regressions were employed to enable the prediction of lipid deuteration for untested conditions. Small-angle neutron scattering was performed on select deuterated lipid samples, which validated the deuteration states calculated from the mass spectral data. Based on these experiments, guidelines for the design of specifically deuterated phospholipids are described. This unlocks even greater capabilities from neutron-based techniques, enabling experiments that were formerly impossible.

Development of 225Ac-doped biocompatible nanoparticles for targeted alpha therapy.

Targeted alpha therapy (TAT) relies on chemical affinity or active targeting using radioimmunoconjugates as strategies to deliver α-emitting radionuclides to cancerous tissue. These strategies can be affected by transmetalation of the parent radionuclide by competing ions in vivo and the bond-breaking recoil energy of decay daughters. The retention of α-emitting radionuclides and the dose delivered to cancer cells are influenced by these processes. Encapsulating α-emitting radionuclides within nanoparticles can help overcome many of these challenges. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles are a biodegradable and biocompatible delivery platform that has been used for drug delivery. In this study, PLGA nanoparticles are utilized for encapsulation and retention of actinium-225 ([225Ac]Ac3+). Encapsulation of [225Ac]Ac3+ within PLGA nanoparticles (Zave = 155.3 nm) was achieved by adapting a double-emulsion solvent evaporation method. The encapsulation efficiency was affected by both the solvent conditions and the chelation of [225Ac]Ac3+. Chelation of [225Ac]Ac3+ to a lipophilic 2,9-bis-lactam-1,10-phenanthroline ligand ([225Ac]AcBLPhen) significantly decreased its release (< 2%) and that of its decay daughters (< 50%) from PLGA nanoparticles. PLGA nanoparticles encapsulating [225Ac]AcBLPhen significantly increased the delivery of [225Ac]Ac3+ to murine (E0771) and human (MCF-7 and MDA-MB-231) breast cancer cells with a concomitant increase in cell death over free [225Ac]Ac3+ in solution. These results demonstrate that PLGA nanoparticles have potential as radionuclide delivery platforms for TAT to advance precision radiotherapy for cancer. In addition, this technology offers an alternative use for ligands with poor aqueous solubility, low stability, or low affinity, allowing them to be repurposed for TAT by encapsulation within PLGA nanoparticles.

Ventricular tachycardia after naloxone administration in an adolescent.

Naloxone is a medication with a largely benign safety profile that is frequently administered in the emergency department to patients presenting with altered mental status. Ventricular tachycardia has been reported after naloxone administration in adult patients with prior use of opiate or sympathomimetic medications. However, no such reports exist in the pediatric population or in patients who have no known history of opiate or sympathomimetic medication use. We describe a case of ventricular tachycardia after naloxone administration in a 17-year-old male with no known prior use of opiate or sympathomimetic agents who presented to the emergency department with altered mental status of unknown etiology. Emergency physicians may wish to prepare for prompt treatment of ventricular arrythmias when administering naloxone to pediatric patients presenting with altered mental status.

Office-Based Anesthesia: Safety and Outcomes in Pediatric Dental Patients.

The number of children with caries requiring general anesthesia to achieve comprehensive dental care and the demand for dentist anesthesiologists to provide ambulatory anesthesia for these patients is increasing. No current published studies examine the safety and outcomes of ambulatory anesthesia performed by dentist anesthesiologists for dental procedures in pediatric patients, and there is no national requirement for reporting outcomes of these procedures. In 2010, the Society for Ambulatory Anesthesia Clinical Outcomes Registry was developed. This Web-based database allows providers of ambulatory anesthesia to track patient demographics and various outcomes of procedures. Our study is a secondary analysis of data collected in the registry over a 4-year period, 2010-2014. Of the 7041 cases reviewed, no cases resulted in serious complications, including death, anaphylaxis, aspiration, cardiovascular adverse events, or neurologic adverse events. Of the 7041 cases reviewed, 196 (3.0%) resulted in a predischarge or postdischarge adverse event. The predischarge adverse event occurring with the highest frequency was laryngospasm, occurring in 35 cases (0.50%). The postdischarge adverse event occurring with the highest frequency was nausea, reported by 99 patients (5.0%). This study provides strong clinical outcomes data to support the safety of office-based anesthesia as performed by dentist anesthesiologists in the treatment of pediatric dental patients.

Overview and new insights into the thiol reactivity of coordinated NO in {MNO}(6/7/8) (M = Fe, Co) complexes.

The reactivity of free NO (NO(+), NO(•), and NO(-)) with thiols (RSH) is relatively well understood, and the oxidation state of the NO moiety generally determines the outcome of the reaction. However, NO/RSH interactions are often mediated at metal centers, and the fate of these species when bound to a first-row transition metal (e.g., Fe, Co) deserves further investigation. Some metal-bound NO moieties (particularly NO(+), yielding S-nitrosothiols) have been more thoroughly studied, yet the fate of these species remains highly condition-dependent and, for M-NO(-), an unexplored field. Herein, we present an overview of thiol reactions with metal nitrosyls that result in N-O bond activation, ligand substitution on {MNO} fragments, and/or redox chemistry. We also present our results pertaining to the thiol reactivity of nonheme {FeNO}(7/8) complexes [Fe(LN4(pr))(NO)](-/0) (1 and 2) and the noncorrin {CoNO}(8) complex [Co(LN4(pr))(NO)] (3), an isoelectronic analogue of the {FeNO}(8) complex 1. Among other products, the reaction of 1 with p-ClPhSH affords [Fe2(µ-SPh-p-Cl)2(NO)4](-) (anion of 6), a reduced Roussin's red ester (rRRE), which was characterized by Fourier transform infrared (FTIR), UV-vis, electron paramagnetic resonance (EPR), and X-ray diffraction. Similarly, the reaction of 1 with glutathione in buffer affords the corresponding rRRE, which has also been spectroscopically characterized by EPR and UV-vis. The oxidation states of the metals and nitrosyls both contribute to the complex nature of these interactions, and as such, we discuss the varying product distribution accordingly. These studies shed insight into the products that may form through MNO/RSH interactions that lead to NOx activation and {MNO} redox.

Reliability of the penetration aspiration scale with flexible endoscopic evaluation of swallowing.

OBJECTIVES: The Penetration Aspiration Scale (PAS), although designed for videofluoroscopy, has been utilized with flexible endoscopic evaluation of swallowing (FEES) in both research and clinical practice. The purpose of this investigation was to determine inter- and intrarater reliability of the PAS with FEES as a function of clinician FEES experience and retest interval. METHODS: Three groups of 3 clinicians (N=9) with varying FEES experience (beginning, intermediate, and advanced) assigned PAS scores to 35 swallows. Initial ratings were repeated following short-term (ie, 1 day) and long-term (ie, 1 week) retest intervals. RESULTS: Intraclass correlation coefficients were calculated to assess interrater reliability on the first rating for each group. The coefficients were .91, .82, and .89 for the beginning, intermediate, and advanced clinicians, respectively. Overall interrater reliability across all 9 clinicians, irrespective of experience, was .85. Intraclass correlation coefficients were also calculated to assess intrarater reliability. The intrarater reliability for short- and long-term ratings was .90, .94, and .96 and .96, .97, and .94 for the beginning, intermediate, and advanced clinicians, respectively. Overall intrarater reliability across all 9 clinicians and all 3 ratings was .94. CONCLUSIONS: Excellent inter- and intrarater reliability was evidenced with the application of the PAS for FEES regardless of clinician experience and retest interval.

NO2(-) activation and reduction to NO by a nonheme Fe(NO2)2 complex.

The selective reduction of nitrite (NO2(-)) to nitric oxide (NO) is a fundamentally important chemical transformation related to environmental remediation of NOx and mammalian blood flow. We report the synthesis and characterization of two nonheme Fe complexes, [Fe(LN4(Im))(MeCN)2](BF4)2 (1(MeCN)) and [Fe(LN4(Im))(NO2)2] (2), geared toward understanding the NO2(-) to NO conversion. Complex 2 represents the first structurally characterized Fe(II) complex with two axial NO2(-) ligands that functions as a nitrite reduction catalyst.

The effect of intraoral suction on oxygen-enriched surgical environments: a mechanism for reducing the risk of surgical fires.

In this study, a mechanical model was applied in order to replicate potential surgical fire conditions in an oxygen-enriched environment with and without high-volume suction typical for dental surgical applications. During 41 trials, 3 combustion events were measured: an audible pop, a visible flash of light, and full ignition. In at least 11 of 21 trials without suction, all 3 conditions were observed, sometimes with an extent of fire that required early termination of the experimental trial. By contrast, in 18 of 20 with-suction trials, ignition did not occur at all, and in the 2 cases where ignition did occur, the fire was qualitatively a much smaller, candle-like flame. Statistically comparing these 3 combustion events in the no-suction versus with-suction trials, ignition (P = .0005), audible pop (P = .0211), and flash (P = .0092) were all significantly more likely in the no-suction condition. These results suggest a possible significant and new element to be added to existing surgical fire safety protocols toward making surgical fires the "never-events" they should be.

Factors involved in dental surgery fires: a review of the literature.

Surgical fires are well-characterized, readily preventable, potentially devastating operating room catastrophes that continue to occur from 20 to 100 times per year or, by one estimate, up to 600 times per year in US operating rooms, sometimes with fatal results. The most significant risk factors for surgical fires involve (a) the use of an ignition source, such as laser or electrocautery equipment, in or around an oxygen-enriched environment in the head, neck, and upper torso area and (b) the concurrent delivery of supplemental oxygen, especially via nasal cannula. Nonetheless, while these 2 conditions occur very commonly in dental surgery, especially in pediatric dental surgery where sedation and anesthesia are regularly indicated, there is a general absence of documented dental surgical fires in the literature. Barring the possibility of underreporting for fear of litigation, this may suggest that there is another mechanism or mechanisms present in dental or pediatric dental surgery that mitigates this worst-case risk of surgical fires. Some possible explanations for this include: greater fire safety awareness by dental practitioners, incidental ventilation of oxygen-enriched environments in patient oral cavities due to breathing, or suction used by dental practitioners during procedures. This review of the literature provides a background to suggest that the practice of using intraoral suction in conjunction with the use of supplemental oxygen during dental procedures may alter the conditions needed for the initiation of intraoral fires. To date, there appear to be no published studies describing the ability of intraoral suctioning devices to alter the ambient oxygen concentration in an intraoral environment. In vivo models that would allow examination of intraoral suction on the ambient oxygen concentration in a simulated intraoral environment may then provide a valuable foundation for evaluating the safety of current clinical dental surgical practices, particularly in regard to the treatment of children.

Fluoride content of infant foods.

Excessive fluoride consumption during the first 2 years of life is associated with an increased risk of dental fluorosis. Estimates of fluoride intake from various sources may aid in determining a child's risk for developing fluorosis. This study sought to assess the fluoride content of commercially available foods for infants, and to guide dentists who are advising parents of young children about fluoride intake. Three samples each of 20 different foods (including fruits and vegetables, as well as chicken, turkey, beef/ham, and vegetarian dinners) from 3 manufacturers were analyzed (in duplicate) for their fluoride content. Among the 360 samples tested, fluoride concentration ranged from 0.007-4.13 µg fluoride/g food. All foods tested had detectable amounts of fluoride. Chicken products had the highest mean levels of fluoride, followed by turkey products. Consuming >1 serving per day of the high fluoride concentration products in this study would place children over the recommended daily fluoride intake. Fluoride from infant foods should be taken into account when determining total daily fluoride intake.

Quantifying platinum binding on protein-functionalized magnetic microparticles using single particle-ICP-TOF-MS.

This work describes an analytical procedure, single particle-inductively coupled plasma-time-of-flight-mass spectrometry (SP-ICP-TOF-MS), that was developed to determine the platinum binding efficiency of protein-coated magnetic microparticles. SP-ICP-TOF-MS is advantageous due to its ability to quasi-simultaneously detect all nuclides (7Li-242Pu), allowing for both platinum and iron (composition of magnetic microparticles) to be measured concurrently. This method subsequently allows for the differentiation between bound and unbound platinum. The 1 µm magnetic microparticles were fully characterized for their iron concentration, particle concentration, and trace element composition by bulk digestion-ICP-MS and SP-ICP-TOF-MS. The results of both approaches agreed with the certificate values. Using the single particle methodology the platinum loading was quantified to be to 0.18 ± 0.02 fg per particle and 0.32 ± 0.02 fg per particle, for the streptavidin-coated and azurin-coated microparticles, respectively. Both streptavidin-coated and the azurin-coated microparticles had a particle-platinum association of >65%. Platinum bound samples were also analyzed via bulk digestion-based ICP-MS. The bulk ICP-MS results overestimated platinum loading due to free platinum in the samples. This highlights the importance of single particle analysis for a closer inspection of platinum binding performance. The SP-ICP-TOF-MS approach offers advantages over typical bulk digestion methods by eliminating laborious sample preparation, enabling differentiation between bound/unbound platinum in a solution, and quantification of platinum on a particle-by-particle basis. The procedure presented here enables quantification of metal content per particle, which could be broadly implemented for other single particle applications.

Longitudinal Follow-up Comparing Future Care of Primary Teeth Treated with Silver Diammine Fluoride: A Private Dental Claims Review.

Purpose: The purpose of this study was to longitudinally evaluate follow-up treatment on primary teeth initially treated with silver diammine fluoride (SDF). Methods: This retrospective cohort evaluated private insurance (not Medicaid) claims data from 2018 to 2019 for children no older than 12 years with at least one primary tooth initially treated with SDF. Additional treatment per tooth was recorded over a follow-up of at least 24 months. Results: The mean and standard deviation (±SD) age of 46,884 patients was 5.7±2.3 and for SDF-treated teeth per patient was 2.6±2.1. Forty percent (95 percent confidence interval [95% CI] equals 39 to 40.7 percent) of teeth initially treated with SDF received additional treatment. The odds of SDF-treated teeth receiving future treatment significantly decreased with patient age by 22 percent per year (odds ratio equals 0.78; 95% CI equals 0.077 to 0.79; P<0.001). Pediatric dentists had only slightly lower odds than general dentists for providing additional treatment (0.91, P<0.001). Posterior teeth and teeth expected to exfoliate in two or more years had significantly higher odds of receiving additional treatment (2.47 and 1.27, respectively, P<0.001). Conclusions: Beginning at age four, patient age at placement of silver diammine fluoride was inversely proportional to future treatment provided. Posterior teeth and teeth expected to exfoliate in two or more years were more likely to receive additional treatment.

Evaluation of Claim Reports for Potential Impact of COVID-19 on Pediatric Dental Procedures.

PURPOSE: To evaluate whether the postponement of dental elective procedures at the start of the COVID-19 pandemic was associated with an increased number of simple dental extractions, and/or decreased restorative procedures by analyzing data obtained from state-funded insurance dental claims. METHODS: Paid dental claims collected from March 2019 to December 2019 and from March 2020 to December 2020 for children ages two to 13 years old were analyzed. Dental procedures were selected based on Current Dental Terminology (CDT) codes for simple dental extractions and restorative procedures. Statistical analyses were performed to compare the rates of procedure types between 2019 and 2020. RESULTS: No differences in dental extractions but full-coverage restoration procedure rates per month and child were significantly lower than pre-pandemic (P=0.016). CONCLUSION: Further study required to determine the impact of COVID-19 on pediatric restorative procedures and access to pediatric dental care in the surgical setting.

Potent and selective covalent inhibition of the papain-like protease from SARS-CoV-2.

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we design a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibits PLpro with kinact/KI = 9,600 M-1 s-1, achieves sub-µM EC50 values against three SARS-CoV-2 variants in mammalian cell lines, and does not inhibit a panel of human deubiquitinases (DUBs) at >30 µM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validates our design strategy and establishes the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

Demand in pediatric dentistry for sedation and general anesthesia by dentist anesthesiologists: a survey of directors of dentist anesthesiologist and pediatric dentistry residencies.

This study describes what training programs in pediatric dentistry and dental anesthesiology are doing to meet future needs for deep sedation/general anesthesia services required for pediatric dentistry. Residency directors from 10 dental anesthesiology training programs in North America and 79 directors from pediatric dentistry training programs in North America were asked to answer an 18-item and 22-item online survey, respectively, through an online survey tool. The response rate for the 10 anesthesiology training program directors was 9 of 10 or 90%. The response rate for the 79 pediatric dentistry training program directors was 46 of 79 or 58%. Thirty-seven percent of pediatric dentistry programs use clinic-based deep sedation/general anesthesia for dental treatment in addition to hospital-based deep sedation/general anesthesia. Eighty-eight percent of those programs use dentist anesthesiologists for administration of deep sedation/general anesthesia in a clinic-based setting. Pediatric dentistry residency directors perceive a future change in the need for deep sedation/general anesthesia services provided by dentist anesthesiologists to pediatric dentists: 64% anticipate an increase in need for dentist anesthesiologist services, while 36% anticipate no change. Dental anesthesiology directors compared to 2, 5, and 10 years ago have seen an increase in the requests for dentist anesthesiologist services by pediatric dentists reported by 56% of respondents (past 2 years), 63% of respondents (past 5 years), and 88% of respondents (past 10 years), respectively. Predicting the future need of dentist anesthesiologists is an uncertain task, but these results show pediatric dentistry directors and dental anesthesiology directors are considering the need, and they recognize a trend of increased need for dentist anesthesiologist services over the past decade.

The use of office-based sedation and general anesthesia by board certified pediatric dentists practicing in the United States.

The purpose of this study is to explore the use of office-based sedation by board-certified pediatric dentists practicing in the United States. Pediatric dentists have traditionally relied upon self-administered sedation techniques to provide office-based sedation. The use of dentist anesthesiologists to provide office-based sedation is an emerging trend. This study examines and compares these two models of office-based sedations. A survey evaluating office-based sedation of diplomates of the American Board of Pediatric Dentistry (ABPD) based on gender, age, years in practice, practice types, regions, and years as a diplomate of the ABPD was completed by 494 active members. The results were summarized using frequencies and percentages. Relationships of dentist age, gender, and number of years in practice with the use of intravenous (IV) sedation was completed using two-way contingency tables and Mantel-Haenszel tests for ordered categorical data. Relationships of office-based sedation use and the type of one's practice were examined using Pearson chi-square tests. Of the 1917 surveys e-mailed, 494 completed the survey for a response rate of 26%. Over 70% of board-certified US pediatric dentists use some form of sedation in their offices. Less than 20% administer IV sedation, 20 to 40% use a dentist anesthesiologist, and 60 to 70% would use dentist anesthesiologists if one were available.

Developmental changes in lignin composition are driven by both monolignol supply and laccase specificity.

The factors controlling lignin composition remain unclear. Catechyl (C)-lignin is a homopolymer of caffeyl alcohol with unique properties as a biomaterial and precursor of industrial chemicals. The lignin synthesized in the seed coat of Cleome hassleriana switches from guaiacyl (G)- to C-lignin at around 12 to 14 days after pollination (DAP), associated with a rerouting of the monolignol pathway. Lack of synthesis of caffeyl alcohol limits C-lignin formation before around 12 DAP, but coniferyl alcohol is still synthesized and highly accumulated after 14 DAP. We propose a model in which, during C-lignin biosynthesis, caffeyl alcohol noncompetitively inhibits oxidation of coniferyl alcohol by cell wall laccases, a process that might limit movement of coniferyl alcohol to the apoplast. Developmental changes in both substrate availability and laccase specificity together account for the metabolic fates of G- and C-monolignols in the Cleome seed coat.

Potent and Selective Covalent Inhibition of the Papain-like Protease from SARS-CoV-2.

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein (ISG15) from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we have designed a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibited PLpro with k inact /K I = 10,000 M - 1 s - 1 , achieved sub-µM EC 50 values against three SARS-CoV-2 variants in mammalian cell lines, and did not inhibit a panel of human deubiquitinases at > 30 µM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validated our design strategy and established the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

Potent and Selective Covalent Inhibition of the Papain-like Protease from SARS-CoV-2.

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein (ISG15) from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we have designed a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibited PLpro with kinact/KI = 10,000 M- 1 s- 1, achieved sub-µM EC50 values against three SARS-CoV-2 variants in mammalian cell lines, and did not inhibit a panel of human deubiquitinases at > 30 µM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validated our design strategy and established the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

Metal-free sequential [3 + 2]-dipolar cycloadditions using cyclooctynes and 1,3-dipoles of different reactivity.

Although metal-free cycloadditions of cyclooctynes and azides to give stable 1,2,3-triazoles have found wide utility in chemical biology and material sciences, there is an urgent need for faster and more versatile bioorthogonal reactions. We have found that nitrile oxides and diazocarbonyl derivatives undergo facile 1,3-dipolar cycloadditions with cyclooctynes. Cycloadditions with diazocarbonyl derivatives exhibited similar kinetics as compared to azides, whereas the reaction rates of cycloadditions with nitrile oxides were much faster. Nitrile oxides could conveniently be prepared by direct oxidation of the corresponding oximes with BAIB, and these conditions made it possible to perform oxime formation, oxidation, and cycloaddition as a one-pot procedure. The methodology was employed to functionalize the anomeric center of carbohydrates with various tags. Furthermore, oximes and azides provide an orthogonal pair of functional groups for sequential metal-free click reactions, and this feature makes it possible to multifunctionalize biomolecules and materials by a simple synthetic procedure that does not require toxic metal catalysts.