Application of Physiologically Based Pharmacokinetic Modeling to Characterize the Effects of Age and Obesity on the Disposition of Levetiracetam in the Pediatric Population.

BACKGROUND: Levetiracetam is an antiseizure medication used for several seizure types in adults and children aged 1 month and older; however, due to a lack of data, pharmacokinetic (PK) variability of levetiracetam is not adequately characterized in certain populations, particularly neonates, children younger than 2 years of age, and children older than 2 years of age with obesity. OBJECTIVE: This study aimed to address the gap by leveraging PK data from two prospective standard-of-care pediatric trials (n = 88) covering an age range from 1 month to 19 years, including those with obesity (64%), and applying a physiologically based PK (PBPK) modeling framework. METHODS: A published PBPK model of levetiracetam for children aged 2 years and older was extended to pediatric patients younger than 2 years of age and patients older than 2 years of age with obesity by accounting for the obesity and age-related changes in PK using PK-Sim® software. The prospective pediatric data, along with the literature data for neonates and children younger than 2 years of age, were used to evaluate the extended PBPK models. RESULTS: Overall, 82.4% of data fell within the 90% interval of model-predicted concentrations, with an average fold error within twofold of the accepted criteria. PBPK modeling revealed that children with obesity had lower weight-normalized clearances (0.053 L/h/kg) on average than children without obesity (0.063 L/h/kg). The effect of maturation was well-characterized, resulting in comparable PBPK-simulated, weight-normalized clearances for neonates and children younger than 2 years of age reported from the literature. CONCLUSIONS: PBPK modeling simulations revealed that the current US FDA-labeled pediatric dosing regimen listed in the prescribing information can produce the required exposure of levetiracetam in these target populations with dose adjustments for children with obesity aged 4 years to younger than 16 years.

Using Real-World Data to Externally Evaluate Population Pharmacokinetic Models of Dexmedetomidine in Children and Infants.

Dexmedetomidine is a sedative used in both adults and off-label in children with considerable reported pharmacokinetic (PK) interindividual variability affecting drug exposure across populations. Several published models describe the population PKs of dexmedetomidine in neonates, infants, children, and adolescents, though very few have been externally evaluated. A prospective PK dataset of dexmedetomidine plasma concentrations in children and young adults aged 0.01-19.9 years was collected as part of a multicenter opportunistic PK study. A PubMed search of studies reporting dexmedetomidine PK identified five population PK models developed with data from demographically similar children that were selected for external validation. A total of 168 plasma concentrations from 102 children were compared with both population (PRED) and individualized (IPRED) predicted values from each of the five published models by quantitative and visual analyses using NONMEM (v7.3) and R (v4.1.3). Mean percent prediction errors from observed values ranged from -1% to 120% for PRED, and -24% to 60% for IPRED. The model by James et al, which was developed using similar "real-world" data, nearly met the generalizability criteria from IPRED predictions. Other models developed using clinical trial data may have been limited by inclusion/exclusion criteria and a less racially diverse population than this study's opportunistic dataset. The James model may represent a useful, but limited tool for model-informed dosing of hospitalized children.

Envisioning Better Healthcare Systems: A Unique and Innovative Journey From Community Hospital to Academic Medical Center.

The transformation from a community hospital to an academic medical center (AMC) presents a unique set of challenges and opportunities. This editorial provides an in-depth analysis of the barriers encountered and solutions developed within a large community hospital in Florida as it embarked on this transition, with a focus on the global relevance of issues experienced such as competition with major markets, the ongoing COVID-19 pandemic, the development of multiple Accreditation Council for Graduate Medical Education (ACGME) programs and balancing the complexities of the United States healthcare system. In alignment with the call for submissions, this editorial highlights the personal experiences of healthcare providers, researchers, and policymakers involved in this transition and explores how the lessons learned can inform the development of better healthcare systems worldwide.

Population Pharmacokinetics of Posaconazole in Immune-Compromised Children and Assessment of Target Attainment in Invasive Fungal Disease.

BACKGROUND AND OBJECTIVE: Posaconazole (PSZ) is a triazole antifungal for the management of invasive fungal disease (IFD) in adults and children. Although PSZ is available as an intravenous (IV) solution, oral suspension (OS) and delayed-release tablets (DRTs), OS is the preferred formulation for pediatric use because of potential safety concerns associated with an excipient in the IV formulation and difficulty in swallowing intact tablets by children. However, poor biopharmaceutical characteristics of the OS formulation leads to an unpredictable dose-exposure profile of PSZ in children, potentially risking therapeutic failure. The goal of this study was to characterize the population pharmacokinetics (PK) of PSZ in immunocompromised children and assess therapeutic target attainment. METHODS: Serum concentrations of PSZ were collected retrospectively from records of hospitalized patients. A population PK analysis was performed in a nonlinear mixed-effects modeling framework with NONMEM (v7.4). The PK parameters were scaled to body weight, then potential covariate effects were assessed. The final PK model was used to evaluate recommended dosing schemes through simulation of target attainment (as a percentage of the population having steady-state trough concentrations above the recommended target) using Simulx (v2021R1). RESULTS: Repeated measurement data of 202 serum concentrations of total PSZ were acquired from 47 immunocompromised patients between 1 and 21 years of age receiving PSZ either intravenously or orally, or both. A one-compartment PK model with first-order absorption and linear elimination best fit the data. The estimated absolute bioavailability (95% confidence interval) for suspension (Fs) was 16% (8-27%), which was significantly lower than the reported tablet bioavailability (Ft) [67%]. Fs was reduced by 62% and 75% upon concomitant administration with pantoprazole (PAN) and omeprazole (OME), respectively. Famotidine resulted in a reduction of Fs by only 22%. Both fixed dosing and weight-based adaptive dosing provided adequate target attainment when PAN or OME were not coadministered with the suspension. CONCLUSIONS: The results of this study revealed that both fixed and weight-based adaptive dosing schemes can be appropriate for target attainment across all PSZ formulations, including suspension. Additionally, covariate analysis suggests that concomitant proton pump inhibitors should be contraindicated during PSZ suspension dosing.

Pediatric Toxicology: An Updated Review.

Pediatricians should be familiar with principles of medical toxicology given that intentional and unintentional ingestions are commonly encountered in different medical settings. Most exploratory ingestions are well tolerated and do not cause significant health effects, but a few noteworthy exceptions can lead to serious illness and death. This article reviews common medications and household products likely to cause significant toxicity in pediatric patients, even in small, exploratory ingestions. Increasing cannabis exposures among children and adolescents are also reviewed. Additionally, indications for gastric decontamination with activated charcoal are reviewed. Finally, poisoning prevention strategies are reviewed. [Pediatr Ann. 2023;52(4):e139-e145.].

Rat Burn Model to Study Full-Thickness Cutaneous Thermal Burn and Infection.

Burn induction methodologies are inconsistently described in rat models. A uniform burn wound model, which represents the clinical scenario, is necessary to perform reproducible burn research. The present protocol describes a simple and reproducible method to create ~20% total body surface area (TBSA) full-thickness burns in rats. Here, a 22.89 cm2 (5.4 cm diameter) copper rod heated at 97 °C in a water bath was applied to the rat skin surface to induce the burn injury. A copper rod with a high thermal conductivity was able to dissipate the heat deeper in the skin tissue to create a full-thickness burn. Histology analysis shows attenuated epidermis with coagulative damage to the full-thickness extent of the dermis and the subcutaneous tissue. Additionally, this model is representative of the clinical situations observed in hospitalized burn patients following burn injury such as immune dysregulation and bacterial infections. The model can recapitulate the systemic bacterial infection by both Gram-positive and Gram-negative bacteria. In conclusion, this paper presents an easy-to-learn and robust rat burn model that mimics the clinical situations, including immune dysregulation and bacterial infections, which is of considerable utility for the development of new topical antibiotic drugs for burn wound and infections.

Analysis of Streptomyces Volatilomes Using Global Molecular Networking Reveals the Presence of Metabolites with Diverse Biological Activities.

Streptomyces species produce a wide variety of specialized metabolites, some of which are used for communication or competition for resources in their natural environments. In addition, many natural products used in medicine and industry are derived from Streptomyces, and there has been interest in their capacity to produce volatile organic compounds (VOCs) for different industrial and agricultural applications. Recently, a machine-learning workflow called MSHub/GNPS was developed, which enables auto-deconvolution of gas chromatography-mass spectrometry (GC-MS) data, molecular networking, and library search capabilities, but it has not been applied to Streptomyces volatilomes. In this study, 131 Streptomyces isolates from the island of Newfoundland were phylogenetically typed, and 37 were selected based on their phylogeny and growth characteristics for VOC analysis using both a user-guided (conventional) and an MSHub/GNPS-based approach. More VOCs were annotated by MSHub/GNPS than by the conventional method. The number of unknown VOCs detected by the two methods was higher than those annotated, suggesting that many novel compounds remain to be identified. The molecular network generated by GNPS can be used to guide the annotation of such unknown VOCs in future studies. However, the number of overlapping VOCs annotated by the two methods is relatively small, suggesting that a combination of analysis methods might be required for robust volatilome analysis. More than half of the VOCs annotated with high confidence by the two approaches are plant-associated, many with reported bioactivities such as insect behavior modulation. Details regarding the properties and reported functions of such VOCs are described. IMPORTANCE This study represents the first detailed analysis of Streptomyces volatilomes using MSHub/GNPS, which in combination with a routinely used conventional method led to many annotations. More VOCs could be annotated using MSHub/GNPS as compared to the conventional method, many of which have known antimicrobial, anticancer, and insect behavior-modulating activities. The identification of numerous plant-associated VOCs by both approaches in the current study suggests that their production could be a more widespread phenomenon by members of the genus, highlighting opportunities for their large-scale production using Streptomyces. Plant-associated VOCs with antimicrobial activities, such as 1-octen-3-ol, octanol, and phenylethyl alcohol, have potential applications as fumigants. Furthermore, many of the annotated VOCs are reported to influence insect behavior, alluding to a possible explanation for their production based on the functions of other recently described Streptomyces VOCs in dispersal and nutrient acquisition.

Rising incidence and high mortality in intentional sodium nitrite exposures reported to US poison centers.

INTRODUCTION: Sodium nitrite is an oxidizing agent capable of producing profound methemoglobinemia. Large quantities of sodium nitrite can be purchased online, and recent literature has identified several cases of intentional self-poisoning, including multiple cases of mortality. This has raised concern that intentional sodium nitrite poisoning and resultant severe methemoglobinemia may be increasing in incidence and could represent a substantial public health threat. MATERIALS AND METHODS: This study used data obtained from the National Poison Data System (NPDS) to evaluate the incidence and mortality rate of intentional sodium nitrite poisoning of suicidal intent reported to US poison centers over a five-year period. Patient demographics, exposure characteristics, treatments administered, and patient outcomes were analyzed. Temporal patterns in exposure were also investigated. RESULTS: Forty-seven cases were identified in the NPDS database, of which three were excluded due to lack of outcome data. Median patient age was 23 years, 52% of patients were female and 86% of exposures occurred at the patient's residence. Serious outcomes were observed in 84% of cases, 77% of patients included were treated with methylene blue and 30% of patients died. No intentional sodium nitrite exposures were reported in the first two years studied, but we observed an increase in the incidence of exposures reported through the remainder of the investigation period. DISCUSSION/CONCLUSIONS: The incidence of intentional self-poisoning with sodium nitrite has been increasing since 2017. Many of these exposures result in toxicity requiring antidotal therapy, and a high mortality rate was observed. Recent literature indicates that this trend may be the result of ready access to this poison through online vendors combined with recommendations shared in online communities that sodium nitrite be used as an effective method of suicide. Further study is needed to better characterize this phenomenon and develop public health interventions to prevent future morbidity and mortality.

Phenotypically supervised single-cell sequencing parses within-cell-type heterogeneity.

To better understand cellular communication driving diverse behaviors, we need to uncover the molecular mechanisms of within-cell-type functional heterogeneity. While single-cell RNA sequencing (scRNAseq) has advanced our understanding of cell heterogeneity, linking individual cell phenotypes to transcriptomic data remains challenging. Here, we used a phenotypic cell sorting technique to ask whether phenotypically supervised scRNAseq analysis (pheno-scRNAseq) can provide more insight into heterogeneous cell behaviors than unsupervised scRNAseq. Using a simple 3D in vitro breast cancer (BRCA) model, we conducted pheno-scRNAseq on invasive and non-invasive cells and compared the results to phenotype-agnostic scRNAseq analysis. Pheno-scRNAseq identified unique and more selective differentially expressed genes than unsupervised scRNAseq analysis. Functional studies validated the utility of pheno-scRNAseq in understanding within-cell-type functional heterogeneity and revealed that migration phenotypes were coordinated with specific metabolic, proliferation, stress, and immune phenotypes. This approach lends new insight into the molecular systems underlying BRCA cell phenotypic heterogeneity.

Production of Plant-Associated Volatiles by Select Model and Industrially Important Streptomyces spp.

The Streptomyces produce a great diversity of specialized metabolites, including highly volatile compounds with potential biological activities. Volatile organic compounds (VOCs) produced by nine Streptomyces spp., some of which are of industrial importance, were collected and identified using gas chromatography-mass spectrometry (GC-MS). Biosynthetic gene clusters (BGCs) present in the genomes of the respective Streptomyces spp. were also predicted to match them with the VOCs detected. Overall, 33 specific VOCs were identified, of which the production of 16 has not been previously reported in the Streptomyces. Among chemical classes, the most abundant VOCs were terpenes, which is consistent with predicted biosynthetic capabilities. In addition, 27 of the identified VOCs were plant-associated, demonstrating that some Streptomyces spp. can also produce such molecules. It is possible that some of the VOCs detected in the current study have roles in the interaction of Streptomyces with plants and other higher organisms, which might provide opportunities for their application in agriculture or industry.

A Novel Redox Modulator Induces a GPX4-Mediated Cell Death That Is Dependent on Iron and Reactive Oxygen Species.

Redox modulators have been developed as an attractive approach to treat cancer. Herein, we report the synthesis, identification, and biological evaluation of a quinazolinedione reactive oxygen species (ROS) inducer, QD394, with significant cytotoxicity in pancreatic cancer cells. QD394 shows a transcriptomic profile remarkably similar to napabucasin, a cancer stemness inhibitor. Both small molecules inhibit STAT3 phosphorylation, increase cellular ROS, and decrease the GSH/GSSG ratio. Moreover, QD394 causes an iron- and ROS-dependent, GPX4 mediated cell death, suggesting ferroptosis as a major mechanism. Importantly, QD394 decreases the expression of LRPPRC and PNPT1, two proteins involved in mitochondrial RNA catabolic processes and both negatively correlated with the overall survival of pancreatic cancer patients. Pharmacokinetics-guided lead optimization resulted in the derivative QD394-Me, which showed improved plasma stability and reduced toxicity in mice compared to QD394. Overall, QD394 and QD394-Me represent novel ROS-inducing drug-like compounds warranting further development for the treatment of pancreatic cancer.

Black widows as plastic wallflowers: female choosiness increases with indicators of high mate availability in a natural population.

Female choice is an important driver of sexual selection, but can be costly, particularly when choosy females risk remaining unmated or experience delays to reproduction. Thus, females should reduce choosiness when mate encounter rates are low. We asked whether choosiness is affected by social context, which may provide reliable information about the local availability of mates. This has been demonstrated in the lab, but rarely under natural conditions. We studied western black widow spiders (Latrodectus hesperus) in the field, placing experimental final-instar immature females so they were either 'isolated' or 'clustered' near naturally occurring conspecifics (≥10 m or ≤1 m, respectively, from a microhabitat occupied by at least one other female). Upon maturity, females in both treatments were visited by similar numbers of males, but clustered females were visited by males earlier and in more rapid succession than isolated females, confirming that proximity to conspecifics reduces the risk of remaining unmated. As predicted, isolated females were less choosy in staged mating trials, neither rejecting males nor engaging in pre-copulatory cannibalism, in contrast to clustered females. These results demonstrate that exposure of females to natural variation in demography in the field can alter choosiness of adults. Thus, female behaviour in response to cues of local population density can affect the intensity of sexual selection on males in the wild.

Male black widows parasitize mate-searching effort of rivals to find females faster.

Mate-searching success is a critical precursor to mating, but there is a dearth of research on traits and tactics that confer a competitive advantage in finding potential mates. Theory and available empirical evidence suggest that males locate mates using mate-attraction signals produced by receptive females (personal information) and avoid inadvertently produced cues from rival males (social information) that indicate a female has probably already mated. Here, we show that western black widow males use both kinds of information to find females efficiently, parasitizing the searching effort of rivals in a way that guarantees competition over mating after reaching a female's web. This tactic may be adaptive because female receptivity is transient, and we show that (i) mate searching is risky (88% mortality) and (ii) a strongly male-biased operational sex ratio (from 1.2 : 1 to more than 10 : 1) makes competition inevitable. Males with access to rivals' silk trails moved at higher speeds than those with only personal information, and located females even when personal information was unreliable or absent. We show that following rivals can increase the potential for sexual selection on females as well as males and argue it may be more widespread in nature than is currently realized.

Evidence for a Nest Defense Pheromone in Bald-Faced Hornets, Dolichovespula Maculata, and Identification of Components.

In eusocial insects like Bald-faced hornets, Dolichovespula maculata, nest defense is essential because nests contain a large number of protein-rich larvae and pupae, and thus are attractive to nest predators. Our objectives were to investigate whether D. maculata exhibit pheromone-mediated nest defense, and to identify and field test any pheromone components. We tested for pheromone-mediated nest defense behavior of D. maculata by placing a paired box-apparatus near the entrance of D. maculata nests, and treating both boxes with a solvent control, or one of the two boxes with a solvent control and the other with either venom sac extract, the putative source of nest defense pheromone, or synthetic pheromone. The sound impulses caused by nest mates attempting to sting or strike the boxes were recorded for 3 min. Compared to the double-control treatment, the number of strikes increased 27-fold when one of the two boxes was treated with venom sac extract, providing evidence for an alarm response. The box treated with venom sac extract also induced a significantly greater proportion of strikes than the corresponding control box, providing evidence for a target-oriented response. Analyzing venom sac extract by gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometry resulted in the identification of seven candidate pheromone components: (a) dimethylaminoethanol, (b) dimethylamino ethyl acetate, (c) 2,5-dimethylpyrazine, (d) N-3-methylbutylacetamide, (e) 2-heptadecanone, (f) (Z)-8-heptadecen-2-one, and (g) (Z)-10-nonadecen-2-one. Testing in paired-box bioassays blends of the nitrogen-containing volatile components a-d, the less volatile ketones e-g, or both (a-g), indicated that a-d primarily have an alarm function. The ketones e-g, in contrast, induced target-oriented responses, possibly marking the box, or potential nest predators, for guided and concerted attacks, or enhancing the alarm-inducing effect of the volatile pheromone components, as shown in honey bees. Comparing the behavioral effects of venom sac extract, blends a-d, e-g, and a-g, venom sac extract was most effective in triggering the full complement of alarm and target-oriented responses. These comparisons further suggested that a component is missing in the group of components that triggers the alarm rather than the target-oriented response.

N-3-Methylbutanoyl-O-methylpropanoyl-L-serine Methyl Ester - Pheromone Component of Western Black Widow Females.

Chemical communication is common in spiders but few pheromones have been identified. Female widow spiders in the genus Latrodectus spin webs that disseminate an attractive sex pheromone, and a contact pheromone on the silk elicits courtship behavior by males. The methyl ester of N-3-methylbutanoyl-O-(S)-2-methylbutanoyl-L-serine is a contact pheromone of the Australian redback spider Latrodectus hasselti. We hypothesized that the contact pheromone of congeneric L. hesperus resembles that of L. hasselti. The silk of virgin L. hesperus females was extracted with methanol, and analyses by gas chromatography-mass spectrometry (GC/MS) provided evidence for the presence of N-3-methylbutanoyl-O-methylpropanoyl-L-serine methyl ester (MB-MP-S), a lower homologue of the L. hasselti contact pheromone. Behavioral responses of L. hesperus males to test stimuli were assayed on T-shaped rods with the end sections of the horizontal arm enveloped in filter paper. Males spent 40 % longer in contact with paper bearing female silk than with blank paper, and 39 % longer in contact with paper treated with silk extract than with solvent controls. Contact with silk and silk extract induced courtship behavior by 96 % and 80 % of males, respectively, indicating that there was a methanol-soluble courtship-eliciting contact pheromone on the silk. Males responded less strongly to synthetic MB-MP-S than to silk or silk extract. Paper impregnated with synthetic MB-MP-S (10 or 100 µg) induced courtship behavior in 3-16 % of males, and prompted males to stay 10-16 % longer than on control paper. Our data support the conclusion that MB-MP-S is part of a multi-component contact pheromone of L. hesperus.

(R)-Desmolactone is a sex pheromone or sex attractant for the endangered valley elderberry longhorn beetle Desmocerus californicus dimorphus and several congeners (Cerambycidae: Lepturinae).

We report here that (4R,9Z)-hexadec-9-en-4-olide [(R)-desmolactone] is a sex attractant or sex pheromone for multiple species and subspecies in the cerambycid genus Desmocerus. This compound was previously identified as a female-produced sex attractant pheromone of Desmocerus californicus californicus. Headspace volatiles from female Desmocerus aureipennis aureipennis contained (R)-desmolactone, and the antennae of adult males of two species responded strongly to synthetic (R)-desmolactone in coupled gas chromatography-electroantennogram analyses. In field bioassays in California, Oregon, and British Columbia, traps baited with synthetic (R)-desmolactone captured males of several Desmocerus species and subspecies. Only male beetles were captured, indicating that this compound acts as a sex-specific attractant, rather than as a signal for aggregation. In targeted field bioassays, males of the US federally threatened subspecies Desmocerus californicus dimorphus responded to the synthetic attractant in a dose dependent manner. Our results represent the first example of a "generic" sex pheromone used by multiple species in the subfamily Lepturinae, and demonstrate that pheromone-baited traps may be a sensitive and efficient method of monitoring the threatened species Desmocerus californicus dimorphus, commonly known as the valley elderberry longhorn beetle.

Strike fast, strike hard: the red-throated caracara exploits absconding behavior of social wasps during nest predation.

Red-throated Caracaras Ibycter americanus (Falconidae) are specialist predators of social wasps in the Neotropics. It had been proposed that these caracaras possess chemical repellents that allow them to take the brood of wasp nests without being attacked by worker wasps. To determine how caracaras exploit nests of social wasps and whether chemical repellents facilitate predation, we: (1) video recorded the birds attacking wasp nests; (2) analyzed surface extracts of the birds' faces, feet, and feathers for potential chemical repellents; and (3) inflicted mechanical damage on wasp nests to determine the defensive behavior of wasps in response to varying levels of disturbance. During caracara predation events, two species of large-bodied wasps mounted stinging attacks on caracaras, whereas three smaller-bodied wasp species did not. The "hit-and-run" predation tactic of caracaras when they attacked nests of large and aggressive wasps reduced the risk of getting stung. Our data reveal that the predation strategy of caracaras is based on mechanical disturbance of, and damage to, target wasp nests. Caracara attacks and severe experimental disturbance of nests invariably caused wasps to abscond (abandon their nests). Two compounds in caracara foot extracts [sulcatone and iridodial] elicited electrophysiological responses from wasp antennae, and were also present in defensive secretions of sympatric arboreal-nesting Azteca ants. These compounds appear not to be wasp repellents but to be acquired coincidentally by caracaras when they perch on trees inhabited with Azteca ants. We conclude that caracara predation success does not depend on wasp repellents but relies on the absconding response that is typical of swarm-founding polistine wasps. Our study highlights the potential importance of vertebrate predators in the ecology and evolution of social wasps.