Metaphyseal Fracture Displacement is Predictive of Intra-articular Diastasis in Adolescent Triplane Ankle Fractures.

BACKGROUND: Triplane fractures are rare enough that large homogeneous series to support management decisions are lacking. During initial evaluation, the addition of computed tomography (CT) to conventional X-rays (XR) does not always alter the patient's clinical course. Therefore, routine use of CT is controversial. This study aims to: (1) clarify quantitative relationships between articular displacement measured on XR versus CT and (2) identify whether metaphyseal displacement on the lateral XR predicts clinically relevant articular displacement on a CT scan. METHODS: A 10-year retrospective review of consecutive triplane fractures was performed at a level 1 pediatric trauma center. Maximum articular and metaphyseal displacement were recorded from XR and CT. Quantitative relationships between XR and CT measurements were compared among imaging modalities and radiographically operative versus nonoperative fractures. RESULTS: Eighty-seven patients met the inclusion criteria. XR underestimated articular displacement by 229% in the sagittal plane (1 mm on XR vs 3.3 mm on CT; P < 0.05) and 17% in the coronal plane (2.3 mm on XR vs 2.7 mm on CT; P < 0.05). XR underestimated articular step-off by 184% in the coronal plane and 177% in the sagittal plane ( P < 0.05). CT measurements more often differentiated patients who did or did not undergo surgery at our institution. Metaphyseal displacement was significantly higher in patients with traditionally operative articular displacement (≥2.5 mm on CT) versus those with articular displacement below traditionally operative thresholds (2.4 vs 0.9 mm, P = 0.001). Sixty patients had metaphyseal displacement >1 mm on the lateral XR, of whom 56 had surgical-magnitude articular displacement (≥2.5 mm) on CT (positive predictive value = 94%). CONCLUSIONS: Conventional radiographs underestimate the true articular displacement of triplane fractures. Surgical-magnitude articular step-off is rare, and the largest articular gap is usually visualized on the axial CT image. Metaphyseal displacement >1 mm, which is easily measured on a lateral XR, is strongly predictive of clinically relevant articular displacement on CT. This radiographic finding should prompt advanced imaging before proceeding with nonoperative management. LEVEL OF EVIDENCE: Level III.

The first reported case of Blaptica dubia cockroach allergy.

BACKGROUND: Periplaneta americana and Blattella germanica cockroaches are widespread, and risk of sensitization increases in urban environments where these roaches thrive as household pests. There are no prior reports of Blaptica dubia cockroach allergy, though human exposure to B. dubia is increasing through commercial breeding as feeder insects. CASE PRESENTATION: A 50-year-old B. dubia cockroach breeder presented with progressively worsening upper and lower respiratory symptoms in recent years. Symptoms were worse with exposure to her B. dubia roach colony. Skin prick testing (SPT) to B. dubia cast skin, internal organs, and feces was performed in both the subject and a human control. Testing for P. americana and B. germanica sensitization was also performed in the subject. SDS-Polyacrylamide gel electrophoresis (PAGE), immunoblots, and enzyme-linked immunosorbent assays (ELISA) studies were performed using the subject and control serums to explore for specific IgE binding to B. dubia as well as P. americana. Our results showed SPT was positive to B. dubia internal organs in the subject and negative in the control. In the subject, SPT was negative to P. americana though intradermal (ID) testing was positive and serum specific IgE (sIgE) testing was negative to B. germanica. Immunoblotting of the subject's serum to B. dubia internal organ extract showed several distinct bands of IgE binding at 47 kilodaltons (kD), 68 kD, 74 kD, 83 kD, and 118 kD. The strongest band was at 118 kD on B. dubia immunoblotting, which was absent in P. americana on SDS-PAGE. ELISA studies showed an increased IgE response to both B. dubia and P. americana in the subject versus the control. CONCLUSIONS: This case confirmed the first reported allergy to B. dubia cockroaches. There may be cross-reactivity between B. dubia and P. americana, though our case suggests SPT and sIgE testing using P. americana and B. germanica extract has potential to miss a B. dubia cockroach allergy. This allergy is likely underreported, and further study is needed to explore the natural history of B. dubia cockroach allergy.

iciHHV-6 in a Patient With Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is a serious, sometimes life-threatening late complication of coronavirus disease 2019 (COVID-19) with multiorgan involvement and evidence of immune activation. The pathogenesis of MIS-C is not known, nor is the pathogenesis of the severe organ damage that is the hallmark of MIS-C. Human herpesvirus 6 (HHV-6), the virus responsible for roseola, is a ubiquitous herpesvirus that causes close to universal infection by the age of 3 years. HHV-6 remains latent for life and can be activated during inflammatory states, by other viruses, and by host cell apoptosis. HHV-6 has been associated with end-organ diseases, including hepatitis, carditis, and encephalitis. In addition, ∼1% of people have inherited chromosomally integrated human herpesvirus 6 (iciHHV-6), which is HHV-6 that has been integrated into chromosomal telomeric regions and is transmitted through the germ line. iciHHV-6 can be reactivated and has been associated with altered immune responses. We report here a case of MIS-C in which an initial high HHV-6 DNA polymerase chain reaction viral load assay prompted testing for iciHHV-6, which yielded a positive result. Additional research may be warranted to determine if iciHHV-6 is commonly observed in patients with MIS-C and, if so, whether it may play a part in MIS-C pathogenesis.

Discovery of [11C]MK-6884: A Positron Emission Tomography (PET) Imaging Agent for the Study of M4Muscarinic Receptor Positive Allosteric Modulators (PAMs) in Neurodegenerative Diseases.

The measurement of receptor occupancy (RO) using positron emission tomography (PET) has been instrumental in guiding discovery and development of CNS directed therapeutics. We and others have investigated muscarinic acetylcholine receptor 4 (M4) positive allosteric modulators (PAMs) for the treatment of symptoms associated with neuropsychiatric disorders. In this article, we describe the synthesis, in vitro, and in vivo characterization of a series of central pyridine-related M4 PAMs that can be conveniently radiolabeled with carbon-11 as PET tracers for the in vivo imaging of an allosteric binding site of the M4 receptor. We first demonstrated its feasibility by mapping the receptor distribution in mouse brain and confirming that a lead molecule 1 binds selectively to the receptor only in the presence of the orthosteric agonist carbachol. Through a competitive binding affinity assay and a number of physiochemical properties filters, several related compounds were identified as candidates for in vivo evaluation. These candidates were then radiolabeled with 11C and studied in vivo in rhesus monkeys. This research eventually led to the discovery of the clinical radiotracer candidate [11C]MK-6884.

Latex content in adult vaccines.

INTRODUCTION: Hypersensitivity reactions to natural rubber latex are well-characterized occupational concerns for health care personnel. Health care providers are at increased risk for exposure and possibly transmission of vaccine preventable diseases. Therefore, many health care facilities require providers to be vaccinated against these diseases to maintain employment. Mandatory vaccination for these health care providers presents potential challenges and safety concerns. MATERIALS AND METHODS: Using a commercial Latex Allergen ELISA Assay kit for Hev b 1, we evaluated the latex content of HAVRIX, ENGERIX-B, TWINRIX, and BOOSTRIX all manufactured by GlaxoSmithKline. RESULTS: These data demonstrate undetectable Hev b 1 content among all of the vaccines tested. This study provides the first known data regarding natural rubber latex content in adult vaccines. CONCLUSIONS: Our study revealed undetectable levels of Hev b 1 natural rubber latex content in the tested adult vaccines. These data provide evidence for prospective studies into the safety of vaccinating latex allergic patients.

Discovery, Optimization, and Biological Characterization of 2,3,6-Trisubstituted Pyridine-Containing M4 Positive Allosteric Modulators.

Herein we describe the discovery and optimization of a new series of 2,3-disubstituted and 2,3,6-trisubstituted muscarinic acetylcholine receptor 4 (M4 ) positive allosteric modulators (PAMs). Iterative libraries enabled rapid exploration of one-dimensional structure-activity relationships (SAR) and identification of potency-enhancing heterocycle and N-alkyl pyrazole substituents. Further optimization led to identification of the potent, receptor-subtype-selective, brain-penetrant tool compound 24 (7-[3-[1-[(1-fluorocyclopentyl)methyl]pyrazol-4-yl]-6-methyl-2-pyridyl]-3-methoxycinnoline). It is efficacious in preclinical assays that are predictive of antipsychotic effects, producing dose-dependent reversal of amphetamine-induced hyperlocomotion in rats and mice, but not in M4 knockout mice. Cholinergic-related adverse effects observed in rats treated with 24 at unbound plasma concentrations more than 3-fold higher than an efficacious dose in the hyperlocomotion assay were fewer and less severe than those observed in rats treated with the nonselective M4 agonist xanomeline, suggesting a receptor-subtype-selective PAM has the potential for an improved safety profile.

Discovery of selective, orally bioavailable, N-linked arylsulfonamide Nav1.7 inhibitors with pain efficacy in mice.

The voltage-gated sodium channel Nav1.7 is a genetically validated target for the treatment of pain with gain-of-function mutations in man eliciting a variety of painful disorders and loss-of-function mutations affording insensitivity to pain. Unfortunately, drugs thought to garner efficacy via Nav1 inhibition have undesirable side effect profiles due to their lack of selectivity over channel isoforms. Herein we report the discovery of a novel series of orally bioavailable arylsulfonamide Nav1.7 inhibitors with high levels of selectivity over Nav1.5, the Nav isoform responsible for cardiovascular side effects, through judicious use of parallel medicinal chemistry and physicochemical property optimization. This effort produced inhibitors such as compound 5 with excellent potency, selectivity, behavioral efficacy in a rodent pain model, and efficacy in a mouse itch model suggestive of target modulation.

Mechanism based neurotoxicity of mGlu5 positive allosteric modulators--development challenges for a promising novel antipsychotic target.

Previous work has suggested that activation of mGlu5 receptor augments NMDA receptor function and thereby may constitute a rational approach addressing glutamate hypofunction in schizophrenia and a target for novel antipsychotic drug development. Here, we report the in vitro activity, in vivo efficacy and safety profile of 5PAM523 (4-Fluorophenyl){(2R,5S)-5-[5-(5-fluoropyridin-2-yl)-1,2,4-oxadiazol-3-yl]-2-methylpiperidin-1-yl}methanone), a structurally novel positive allosteric modulator selective of mGlu5. In cells expressing human mGlu5 receptor, 5PAM523 potentiated threshold responses to glutamate in fluorometric calcium assays, but does not have any intrinsic agonist activity. 5PAM523 acts as an allosteric modulator as suggested by the binding studies showing that 5PAM523 did not displace the binding of the orthosteric ligand quisqualic acid, but did partially compete with the negative allosteric modulator, MPyEP. In vivo, 5PAM523 reversed amphetamine-induced locomotor activity in rats. Therefore, both the in vitro and in vivo data demonstrate that 5PAM523 acts as a selective mGlu5 PAM and exhibits anti-psychotic like activity. To study the potential for adverse effects and particularly neurotoxicity, brain histopathological exams were performed in rats treated for 4 days with 5PAM523 or vehicle. The brain exam revealed moderate to severe neuronal necrosis in the rats treated with the doses of 30 and 50 mg/kg, particularly in the auditory cortex and hippocampus. To investigate whether this neurotoxicity is mechanism specific to 5PAM523, similar safety studies were carried out with three other structurally distinct selective mGlu5 PAMs. Results revealed a comparable pattern of neuronal cell death. Finally, 5PAM523 was tested in mGlu5 knock-out (KO) and wild type (WT) mice. mGlu5 WT mice treated with 5PAM523 for 4 days at 100 mg/kg presented significant neuronal death in the auditory cortex and hippocampus. Conversely, mGlu5 KO mice did not show any neuronal loss by histopathology, suggesting that enhancement of mGlu5 function is responsible for the toxicity of 5PAM523. This study reveals for the first time that augmentation of mGlu5 function with selective allosteric modulators results in neurotoxicity.

A side-by-side comparison of Rotorod and Burkard pollen and spore collections.

BACKGROUND: The Rotorod sampler and Burkard spore trap are 2 devices commonly used to quantify airborne particles. OBJECTIVE: To evaluate the differences in collections between the 2 devices for a wide range of plant pollens and fungal spores. METHODS: Pollens and spores were collected simultaneously with each device on 167 days during a 1-year period. RESULTS: The Burkard yielded significantly higher total and individual mold spore counts. It yielded statistically higher total grass, total weed, and Urticaceae daily pollen counts, although the absolute differences were small. Daily counts were positively correlated between the 2 devices for the most abundant pollens and mold spores. CONCLUSION: The Burkard spore trap collects many more mold spores than the Rotorod over a wide variety of species. The Burkard also yielded higher total grass, total weed, and Urticaceae daily pollen counts. Despite these differences, however, either device can be used to follow trends in the most abundant pollen and mold spores.

Antiviral activity and in vitro mutation development pathways of MK-6186, a novel nonnucleoside reverse transcriptase inhibitor.

MK-6186 is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) which displays subnanomolar potency against wild-type (WT) virus and the two most prevalent NNRTI-resistant RT mutants (K103N and Y181C) in biochemical assays. In addition, it showed excellent antiviral potency against K103N and Y181C mutant viruses, with fold changes (FCs) of less than 2 and 5, respectively. When a panel of 12 common NNRTI-associated mutant viruses was tested with MK-6186, only 2 relatively rare mutants (Y188L and V106I/Y188L) were highly resistant, with FCs of >100, and the remaining viruses showed FCs of <10. Furthermore, a panel of 96 clinical virus isolates with NNRTI resistance mutations was evaluated for susceptibility to NNRTIs. The majority (70%) of viruses tested displayed resistance to efavirenz (EFV), with FCs of >10, whereas only 29% of the mutant viruses displayed greater than 10-fold resistance to MK-6186. To determine whether MK-6186 selects for novel resistance mutations, in vitro resistance selections were conducted with one isolate each from subtypes A, B, and C under low-multiplicity-of-infection (MOI) conditions. The results showed a unique mutation development pattern in which L234I was the first mutation to emerge in the majority of the experiments. In resistance selection under high-MOI conditions with subtype B virus, V106A was the dominant mutation detected in the breakthrough viruses. More importantly, mutant viruses selected by MK-6186 showed FCs of <10 against EFV or etravirine (ETR), and the mutant viruses containing mutations selected by EFV or ETR were sensitive to MK-6186 (FCs of <10).