A Case Series on Serotonin Syndrome from Concomitant use of linezolid With Methadone, Buprenorphine, and/or Dextroamphetamine.

BACKGROUND AND OBJECTIVES: The risk of serotonin syndrome (SS), especially when linezolid is used concomitantly with methadone, buprenorphine, and/or dextroamphetamine, remains widely unstudied and may limit the options for antimicrobial therapy in these patient populations. METHODS: We reviewed all adult encounters on linezolid with concomitant methadone, buprenorphine, and/or dextroamphetamine from April 2016 to June 2022. The primary outcomes included characterizing prescribing preferences and prevalence of confirmed and possible serotonin syndrome using ICD-10 diagnosis codes, cyproheptadine administration, and electronic medical record chart review using the Hunter Serotonin Toxicity Criteria. RESULTS: Overall, 194 encounters were evaluated. 16.5%, 17.8%, and 7.1% were on high dose methadone, buprenorphine, and dextroamphetamine, respectively. Mean duration of overlap with linezolid was 4.6, 3.3, and 7 days respectively. One confirmed and two possible cases of serotonin syndrome were identified. CONCLUSION: Linezolid may be considered in patients who are concomitantly on methadone, buprenorphine, and/or dextroamphetamine. In our analysis of 194 encounters, one definitive case and two possible cases of SS were identified. Additional real-world studies are necessary to identify if exposure and/or duration may be correlated with an increased risk of serotonin syndrome.

If you don't test, they will not treat: Impact of stopping preoperative screening for asymptomatic bacteriuria.

Objective: Screening for asymptomatic bacteriuria (ASB) is not recommended outside of patients undergoing invasive urological procedures and during pregnancy. Despite national guidelines recommending against screening for ASB, this practice is prevalent. We present outcomes from a quality-improvement intervention targeting patients undergoing cardiac artery bypass grafting surgery (CABG) at Massachusetts General Hospital, a tertiary-care hospital in Boston, Massachusetts, where preoperative testing checklists were modified to remove routine urinalysis and urine culture. This was a before-and-after intervention study. Methods: Prior to the intervention, screening for ASB was included in the preoperative check list for all patients undergoing CABG. We assessed the proportion of patients undergoing screening for ASB in the 6 months prior to and after the intervention. We estimated cost savings from averted laboratory analyses, and we evaluated changes in antibiotic prescriptions. We additionally examined the incidence of postoperative surgical-site infections (SSIs), central-line-associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTIs) and Clostridioides difficile infections (CDIs). Results: Comparing the pre- and postintervention periods, urinalyses decreased by 76.5% and urine cultures decreased by 87.0%, with an estimated cost savings of $8,090.38. There were 50% fewer antibiotic prescriptions for bacteriuria after the intervention. Conclusions: Removal of urinalysis and urine culture from preoperative checklists for cardiac surgery led to a statistically significant decrease in testing without an increase in SSIs, CLABSIs, CAUTIs, or CDI. Challenges identified included persistence of checklists in templated order sets in the electronic health record.

Doing More With Less: Pragmatic Implementation of Vancomycin Area-Under-the-Curve (AUC) Monitoring.

Universal area-under-the-curve (AUC) guided vancomycin therapeutic drug monitoring (TDM) is resource-intensive, cost-prohibitive, and presents a paradigm shift that leaves institutions with the quandary of defining the preferred and most practical method for TDM. We report a step-by-step quality improvement process using 4 plan-do-study-act (PDSA) cycles to provide a framework for development of a hybrid model of trough and AUC-based vancomycin monitoring. We found trough-based monitoring a pragmatic strategy as a first-tier approach when anticipated use is short-term. AUC-guided monitoring was most impactful and cost-effective when reserved for patients with high-risk for nephrotoxicity. We encourage others to consider quality improvement tools to locally adopt AUC-based monitoring.

Finding the path of least resistance: Locally adapting the MITIGATE toolkit in emergency departments and urgent care centers.

The MITIGATE toolkit was developed to assist urgent care and emergency departments in the development of antimicrobial stewardship programs. At the University of Washington, we adopted the MITIGATE toolkit in 10 urgent care centers, 9 primary care clinics, and 1 emergency department. We encountered and overcame challenges: a complex data build, choosing feasible outcomes to measure, issues with accurate coding, and maintaining positive stewardship relationships. Herein, we discuss solutions to challenges we encountered to provide guidance for those considering using this toolkit.

Tocilizumab in hospitalized patients with COVID-19: Clinical outcomes, inflammatory marker kinetics, and safety.

Coronavirus disease 2019 (COVID-19) due to infection with severe acute respiratory syndrome coronavirus 2 causes substantial morbidity. Tocilizumab, an interleukin-6 receptor antagonist, might improve outcomes by mitigating inflammation. We conducted a retrospective study of patients admitted to the University of Washington Hospital system with COVID-19 and requiring supplemental oxygen. Outcomes included clinical improvement, defined as a two-point reduction in severity on a six-point ordinal scale or discharge, and mortality within 28 days. We used Cox proportional-hazards models with propensity score inverse probability weighting to compare outcomes in patients who did and did not receive tocilizumab. We evaluated 43 patients who received tocilizumab and 45 who did not. Patients receiving tocilizumab were younger with fewer comorbidities but higher baseline oxygen requirements. Tocilizumab treatment was associated with reduced C-reactive protein, fibrinogen, and temperature, but there were no meaningful differences in time to clinical improvement (adjusted hazard ratio [aHR], 0.92; 95% confidence interval [CI], 0.38-2.22) or mortality (aHR, 0.57; 95% CI, 0.21-1.52). A numerically higher proportion of tocilizumab-treated patients had subsequent infections, transaminitis, and cytopenias. Tocilizumab did not improve outcomes in hospitalized patients with COVID-19. However, this study was not powered to detect small differences, and there remains the possibility for a survival benefit.

Epigallocatechin gallate inhibits leukotoxin release by Aggregatibacter actinomycetemcomitans by promoting association with the bacterial membrane.

The oral pathogen, Aggregatibacter actinomycetemcomitans, produces a number of virulence factors, including a leukotoxin (LtxA), which specifically kills human white blood cells, to provide a colonization advantage to the bacterium. Strains of A. actinomycetemcomitans that produce more LtxA have been more closely linked to disease, indicating that this toxin plays a key role in pathogenesis of the bacterium. Disruption of the activity of LtxA thus represents a promising approach to reducing the pathogenicity of the bacterium. Catechins are polyphenolic molecules derived from plants, which have shown potent antibacterial and antitoxin activities. We have previously shown that galloylated catechins are able to prevent LtxA delivery to host cells by altering the toxin's secondary structure and preventing binding to cholesterol on the host cell membrane. Here, we have investigated how one particular galloylated catechin, epigallocatechin gallate (EGCg), affects A. actinomycetemcomitans growth and toxin secretion. Our results demonstrate that EGCg, at micromolar concentrations, inhibits A. actinomycetemcomitans growth, as has been reported for other bacterial species. At subinhibitory concentrations, EGCg promotes LtxA production, but the toxicity of the bacterial supernatant against human immune cells is reduced. The results of our biophysical studies indicate that this seemingly contradictory result is caused by an EGCg-mediated enhancement of LtxA affinity for the bacterial cell surface. Together, these results demonstrate the potential of EGCg in the treatment of virulent A. actinomycetemcomitans infections.

Catechin-mediated restructuring of a bacterial toxin inhibits activity.

BACKGROUND: Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans, as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown. METHODS: In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance. RESULTS: We found that all the catechins except (-)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin. CONCLUSIONS: These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface. GENERAL SIGNIFICANCE: Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface.

Up-regulation of Intracellular Calcium Handling Underlies the Recovery of Endotoxemic Cardiomyopathy in Mice.

BACKGROUND: In surviving patients, sepsis-induced cardiomyopathy is spontaneously reversible. In the absence of any experimental data, it is generally thought that cardiac recovery in sepsis simply follows the remission of systemic inflammation. Here the authors aimed to identify the myocardial mechanisms underlying cardiac recovery in endotoxemic mice. METHODS: Male C57BL/6 mice were challenged with lipopolysaccharide (7 µg/g, intraperitoneally) and followed for 12 days. The authors assessed survival, cardiac function by echocardiography, sarcomere shortening, and calcium transients (with fura-2-acetoxymethyl ester) in electrically paced cardiomyocytes (5 Hz, 37°C) and myocardial protein expression by immunoblotting. RESULTS: Left ventricular ejection fraction, cardiomyocyte sarcomere shortening, and calcium transients were depressed 12 h after lipopolysaccharide challenge, started to recover by 24 h (day 1), and were back to baseline at day 3. The recovery of calcium transients at day 3 was associated with the up-regulation of the sarcoplasmic reticulum calcium pump to 139 ± 19% (mean ± SD) of baseline and phospholamban down-regulation to 35 ± 20% of baseline. At day 6, calcium transients were increased to 123 ± 31% of baseline, associated with increased sarcoplasmic reticulum calcium load (to 126 ± 32% of baseline, as measured with caffeine) and inhibition of sodium/calcium exchange (to 48 ± 12% of baseline). CONCLUSIONS: In mice surviving lipopolysaccharide challenge, the natural recovery of cardiac contractility was associated with the up-regulation of cardiomyocyte calcium handling above baseline levels, indicating the presence of an active myocardial recovery process, which included sarcoplasmic reticulum calcium pump activation, the down-regulation of phospholamban, and sodium/calcium exchange inhibition.

Unbiased Metabolite Profiling of Schizophrenia Fibroblasts under Stressful Perturbations Reveals Dysregulation of Plasmalogens and Phosphatidylcholines.

We undertook an unbiased metabolite profiling of fibroblasts from schizophrenia patients and healthy controls to identify metabolites and pathways that are dysregulated in disease, seeking to gain new insights into the disease biology of schizophrenia and to discover potential disease-related biomarkers. We measured polar and nonpolar metabolites in the fibroblasts under normal conditions and under two stressful physiological perturbations: growth in low-glucose media and exposure to the steroid hormone dexamethasone. We found that metabolites that were significantly different between schizophrenia and control subjects showed separation of the two groups by partial least-squares discriminant analysis methods. This separation between schizophrenia and healthy controls was more robust with metabolites identified under the perturbation conditions. The most significant individual metabolite differences were also found in the perturbation experiments. Metabolites that were significantly different between schizophrenia and healthy controls included a number of plasmalogens and phosphatidylcholines. We present these results in the context of previous reports of metabolic profiling of brain tissue and plasma in schizophrenia. These results show the applicability of metabolite profiling under stressful perturbations to reveal cellular pathways that may be involved in disease biology.

Perturbational Profiling of Metabolites in Patient Fibroblasts Implicates α-Aminoadipate as a Potential Biomarker for Bipolar Disorder.

Many studies suggest the presence of aberrations in cellular metabolism in bipolar disorder. We studied the metabolome in bipolar disorder to gain insight into cellular pathways that may be dysregulated in bipolar disorder and to discover evidence of novel biomarkers. We measured polar and nonpolar metabolites in fibroblasts from subjects with bipolar I disorder and matched healthy control subjects, under normal conditions and with two physiologic perturbations: low-glucose media and exposure to the stress-mediating hormone dexamethasone. Metabolites that were significantly different between bipolar and control subjects showed distinct separation by principal components analysis methods. The most statistically significant findings were observed in the perturbation experiments. The metabolite with the lowest p value in both the low-glucose and dexamethasone experiments was α-aminoadipate, whose intracellular level was consistently lower in bipolar subjects. Our study implicates α-aminoadipate as a possible biomarker in bipolar disorder that manifests under cellular stress. This is an intriguing finding given the known role of α-aminoadipate in the modulation of kynurenic acid in the brain, especially as abnormal kynurenic acid levels have been implicated in bipolar disorder.

Disease signatures for schizophrenia and bipolar disorder using patient-derived induced pluripotent stem cells.

Schizophrenia and bipolar disorder are complex psychiatric disorders that present unique challenges in the study of disease biology. There are no objective biological phenotypes for these disorders, which are characterized by complex genetics and prominent roles for gene-environment interactions. The study of the neurobiology underlying these severe psychiatric disorders has been hindered by the lack of access to the tissue of interest - neurons from patients. The advent of reprogramming methods that enable generation of induced pluripotent stem cells (iPSCs) from patient fibroblasts and peripheral blood mononuclear cells has opened possibilities for new approaches to study relevant disease biology using iPSC-derived neurons. While early studies with patient iPSCs have led to promising and intriguing leads, significant hurdles remain in our attempts to capture the complexity of these disorders in vitro. We present here an overview of studies to date of schizophrenia and bipolar disorder using iPSC-derived neuronal cells and discuss potential future directions that can result in the identification of robust and valid cellular phenotypes that in turn can lay the groundwork for meaningful clinical advances.

HDAC6 inhibitors modulate Lys49 acetylation and membrane localization of ß-catenin in human iPSC-derived neuronal cells.

We examined the effects of isoform-specific histone deacetylase (HDAC) inhibitors on ß-catenin posttranslational modifications in neural progenitor cells (NPCs) derived from human induced pluripotent stem cells (iPSCs). ß-catenin is a multifunctional protein with important roles in the developing and adult central nervous system. Activation of the Wnt pathway results in stabilization and nuclear translocation of ß-catenin, resulting in activation of multiple target genes. In addition, ß-catenin forms a complex with cadherins at the plasma membrane as part of the adherens junctions. The N-terminus of ß-catenin has phosphorylation, ubiquitination, and acetylation sites that regulate its stability and signaling. In the absence of a Wnt signal, Ser33, Ser37, and Thr41 are constitutively phosphorylated by glycogen synthase kinase 3ß (GSK3ß). ß-Catenin phosphorylated at these sites is recognized by ß-transducin repeat-containing protein (ßTrCP), which results in ubiquitination and degradation by the ubiquitin-proteasome pathway. The N-terminal regulatory domain of ß-catenin also includes Ser45, a phosphorylation site for Casein Kinase 1α (CK1α) and Lys49, which is acetylated by the acetyltransferase p300/CBP-associated factor (PCAF). The relevance of Lys49 acetylation and Ser45 phosphorylation to the function of ß-catenin is an active area of investigation. We find that HDAC6 inhibitors increase Lys49 acetylation and Ser45 phosphorylation but do not affect Ser33, Ser37, and Thr41 phosphorylation. Lys49 acetylation results in decreased ubiquitination of ß-catenin in the presence of proteasome inhibition. While increased Lys49 acetylation does not affect total levels of ß-catenin, it results in increased membrane localization of ß-catenin.

Micropatterned cell-cell interactions enable functional encapsulation of primary hepatocytes in hydrogel microtissues.

Drug-induced liver injury is a major cause of drug development failures and postmarket withdrawals. In vitro models that incorporate primary hepatocytes have been shown to be more predictive than model systems which rely on liver microsomes or hepatocellular carcinoma cell lines. Methods to phenotypically stabilize primary hepatocytes ex vivo often rely on mimicry of hepatic microenvironmental cues such as cell-cell interactions and cell-matrix interactions. In this work, we sought to incorporate phenotypically stable hepatocytes into three-dimensional (3D) microtissues, which, in turn, could be deployed in drug-screening platforms such as multiwell plates and diverse organ-on-a-chip devices. We first utilize micropatterning on collagen I to specify cell-cell interactions in two-dimensions, followed by collagenase digestion to produce well-controlled aggregates for 3D encapsulation in polyethylene glycol (PEG) diacrylate. Using this approach, we examined the influence of homotypic hepatocyte interactions and composition of the encapsulating hydrogel, and achieved the maintenance of liver-specific function for over 50 days. Optimally preaggregated structures were subsequently encapsulated using a microfluidic droplet-generator to produce 3D microtissues. Interactions of engineered hepatic microtissues with drugs was characterized by flow cytometry, and yielded both induction of P450 enzymes in response to prototypic small molecules and drug-drug interactions that give rise to hepatotoxicity. Collectively, this study establishes a pipeline for the manufacturing of 3D hepatic microtissues that exhibit stabilized liver-specific functions and can be incorporated into a wide array of emerging drug development platforms.

Flow-based pipeline for systematic modulation and analysis of 3D tumor microenvironments.

The cancer microenvironment, which incorporates interactions with stromal cells, extracellular matrix (ECM), and other tumor cells in a 3-dimensional (3D) context, has been implicated in every stage of cancer development, including growth of the primary tumor, metastatic spread, and response to treatment. Our understanding of the tumor microenvironment and our ability to develop new therapies would greatly benefit from tools that allow us to systematically probe microenvironmental cues within a 3D context. Here, we leveraged recent advances in microfluidic technology to develop a platform for high-throughput fabrication of tunable cellular microniches ("microtissues") that allow us to probe tumor cell response to a range of microenvironmental cues, including ECM, soluble factors, and stromal cells, all in 3D. We further combine this tunable microniche platform with rapid, flow-based population level analysis (n > 500), which permits analysis and sorting of microtissue populations both pre- and post-culture by a range of parameters, including proliferation and homotypic or heterotypic cell density. We used this platform to demonstrate differential responses of lung adenocarcinoma cells to a selection of ECM molecules and soluble factors. The cells exhibited enhanced or reduced proliferation when encapsulated in fibronectin- or collagen-1-containing microtissues, respectively, and they showed reduced proliferation in the presence of TGF-ß, an effect that we did not observe in monolayer culture. We also measured tumor cell response to a panel of drug targets and found, in contrast to monolayer culture, specific sensitivity of tumor cells to TGFßR2 inhibitors, implying that TGF-ß has an anti-proliferative affect that is unique to the 3D context and that this effect is mediated by TGFßR2. These findings highlight the importance of the microenvironmental context in therapeutic development and that the platform we present here allows the high-throughput study of tumor response to drugs as well as basic tumor biology in well-defined microenvironmental niches.

Genetic determinants of phosphate response in Drosophila.

Phosphate is required for many important cellular processes and having too little phosphate or too much can cause disease and reduce life span in humans. However, the mechanisms underlying homeostatic control of extracellular phosphate levels and cellular effects of phosphate are poorly understood. Here, we establish Drosophila melanogaster as a model system for the study of phosphate effects. We found that Drosophila larval development depends on the availability of phosphate in the medium. Conversely, life span is reduced when adult flies are cultured on high phosphate medium or when hemolymph phosphate is increased in flies with impaired malpighian tubules. In addition, RNAi-mediated inhibition of MAPK-signaling by knockdown of Ras85D, phl/D-Raf or Dsor1/MEK affects larval development, adult life span and hemolymph phosphate, suggesting that some in vivo effects involve activation of this signaling pathway by phosphate. To identify novel genetic determinants of phosphate responses, we used Drosophila hemocyte-like cultured cells (S2R+) to perform a genome-wide RNAi screen using MAPK activation as the readout. We identified a number of candidate genes potentially important for the cellular response to phosphate. Evaluation of 51 genes in live flies revealed some that affect larval development, adult life span and hemolymph phosphate levels.

Rapid deamidation of recombinant protective antigen when adsorbed on aluminum hydroxide gel correlates with reduced potency of vaccine.

Deamidation of the recombinant protective antigen (rPA) correlates with decreased effectiveness of the vaccine in protecting against infection by Bacillus anthracis. We present data demonstrating dramatic deamidation of amino acid positions 713 and 719 of rPA adsorbed onto aluminum hydroxide gel, an adjuvant, relative to rPA stored in solution without adjuvant. Although deamidation did not impact total levels of rPA-specific antibodies in a mouse model, it did correlate with a decrease in toxin-neutralizing antibodies. On the basis of these data, we hypothesize that interactions of rPA with aluminum hydroxide gel are destabilizing and are the direct cause of reduced vaccine efficacy.

Roles of major facilitator superfamily transporters in phosphate response in Drosophila.

The major facilitator superfamily (MFS) transporter Pho84 and the type III transporter Pho89 are responsible for metabolic effects of inorganic phosphate in yeast. While the Pho89 ortholog Pit1 was also shown to be involved in phosphate-activated MAPK in mammalian cells, it is currently unknown, whether orthologs of Pho84 have a role in phosphate-sensing in metazoan species. We show here that the activation of MAPK by phosphate observed in mammals is conserved in Drosophila cells, and used this assay to characterize the roles of putative phosphate transporters. Surprisingly, while we found that RNAi-mediated knockdown of the fly Pho89 ortholog dPit had little effect on the activation of MAPK in Drosophila S2R+ cells by phosphate, two Pho84/SLC17A1-9 MFS orthologs (MFS10 and MFS13) specifically inhibited this response. Further, using a Xenopus oocyte assay, we show that MSF13 mediates uptake of [(33)P]-orthophosphate in a sodium-dependent fashion. Consistent with a role in phosphate physiology, MSF13 is expressed highest in the Drosophila crop, midgut, Malpighian tubule, and hindgut. Altogether, our findings provide the first evidence that Pho84 orthologs mediate cellular effects of phosphate in metazoan cells. Finally, while phosphate is essential for Drosophila larval development, loss of MFS13 activity is compatible with viability indicating redundancy at the levels of the transporters.

Protective immunity in mice achieved with dry powder formulation and alternative delivery of plague F1-V vaccine.

The potential use of Yersinia pestis as a bioterror agent is a great concern. Development of a stable powder vaccine against Y. pestis and administration of the vaccine by minimally invasive methods could provide an alternative to the traditional liquid formulation and intramuscular injection. We evaluated a spray-freeze-dried powder vaccine containing a recombinant F1-V fusion protein of Y. pestis for vaccination against plaque in a mouse model. Mice were immunized with reconstituted spray-freeze-dried F1-V powder via intramuscular injection, microneedle-based intradermal delivery, or noninvasive intranasal administration. By intramuscular injection, the reconstituted powder induced serum antibody responses and provided protection against lethal subcutaneous challenge with 1,000 50% lethal doses of Y. pestis at levels equivalent to those elicited by unprocessed liquid formulations (70 to 90% protection). The feasibility of intradermal and intranasal delivery of reconstituted powder F1-V vaccine was also demonstrated. Overall, microneedle-based intradermal delivery was shown to be similar in efficacy to intramuscular injection, while intranasal administration required an extra dose of vaccine to achieve similar protection. In addition, the results suggest that seroconversion against F1 may be a better predictor of protection against Y. pestis challenge than seroconversion against either F1-V or V. In summary, we demonstrate the preclinical feasibility of using a reconstituted powder F1-V formulation and microneedle-based intradermal delivery to provide protective immunity against plague in a mouse model. Intranasal delivery, while feasible, was less effective than injection in this study. The potential use of these alternative delivery methods and a powder vaccine formulation may result in substantial health and economic benefits.