Tetracycline use in treating osteoarthritis: a systematic review

Inflammation Research - The purpose of the review was to synthesize the current literature regarding tetracyclines in the treatment of osteoarthritis. Using multiple databases, a systematic review...     

Nasal interferon responses to community rhinovirus infections are similar in controls and children with asthma

BackgroundRhinovirus (RV) is the main cause of asthma exacerbations in children. Some studies reported that persons with asthma have attenuated interferon (IFN) responses to experimental RV infection compared with healthy individuals. However, responses to community-acquired RV infections in controls and children with asthma have not been compared.ObjectiveTo evaluate nasal cytokine responses after natural RV infections in people with asthma and healthy children.MethodsWe compared nasal cytokine expression among controls and children with asthma during healthy, virus-negative surveillance weeks and self-reported RV-positive sick weeks. A total of 14 controls and 21 patients with asthma were studied. Asthma disease severity was based on symptoms and medication use. Viral genome was detected by multiplex polymerase chain reaction. Nasal cytokine protein levels were determined by multiplex assays.ResultsTwo out of 47 surveillance weeks tested positive for RV, illustrating an asymptomatic infection rate of 5%. A total of 38 of 47 sick weeks (81%) tested positive for the respiratory virus. Of these, 33 (87%) were positive for RV. During well weeks, nasal interleukin 8 (IL-8), IL-12, and IL-1β levels were higher in children with asthma than controls. Compared with healthy virus-negative surveillance weeks, IL-8, IL-13, and interferon beta increased during colds only in patients with asthma. In both controls and children with asthma, the nasal levels of interferon gamma, interferon lambda-1, IL-1β, IL-8, and IL-10 increased during RV-positive sick weeks. During RV infection, IL-8, IL-1β, and tumor necrosis factor-α levels were strongly correlated.ConclusionIn both controls and patients with asthma, natural RV infection results in robust type II and III IFN responses.     

Low rates of anti-recipient isohemagglutinins in ABO incompatible hematopoietic stem cell transplants

IntroductionIsohemagglutinins occur naturally and form in an 'opposite' (antigen-negative) pattern to a patient’s ABO blood type. Patients undergoing minor and bidirectional ABO incompatible hematopoietic stem cell transplantation (HSCT) may demonstrate detectable antibodies against their native blood type. In this study, we sought to characterize the rates of such antibody formation and evaluate the clinical significance of our findings.Materials and MethodsAn internal database of HSCT patients at an academic medical center was queried for ABO incompatible transplant patients from 2009-2019. Serum typing results, clinical histories, and laboratory data were compiled and reviewed.ResultsA total of 182 minor and bidirectional ABO incompatible HSCT patients were identified. Anti-recipient isohemagglutinins were found in 9% (16/182) of the HSCT patients. The rate was higher in patients with minor incompatibility (12%: 15/127) versus bidirectional ABO incompatibility (2%: 1/55) (p = 0.04). No anti-recipient isohemagglutinins were identified in umbilical cord HSCT patients (0%: 0/7). Serologic agglutination reactions of recipient isohemagglutinins were overall mostly weak (13/16 weak + to 1+). There was a trend towards a higher rate of acute graft-versus-host-disease in patients with anti-recipient isohemagglutinins compared to those without (75% vs. 53%; p = 0.12), though not statistically significant. Rates of alloimmunization to minor red cell antigens were similar between the two groups. Few patients showed laboratory evidence of hemolysis at 12 months follow up.Discussion and conclusionsAnti-recipient isohemagglutinins occur at low rates in ABO incompatible HSCT and are significantly more common in minor ABO incompatible transplant compared to bidirectional transplants. Larger cohort studies are needed to better understand the relationship between anti-recipient isohemagglutinins and HSCT outcomes.     

Meta‐Analysis of Risk Factors for Secondary Traumatic Stress in Therapeutic Work With Trauma Victims

Revisions to the posttraumatic stress disorder (PTSD) diagnostic criteria in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM‐5; American Psychiatric Association, 2013) clarify that secondary exposure can lead to the development of impairing symptoms requiring treatment. Historically known as secondary traumatic stress (STS), this reaction occurs through repeatedly hearing the details of traumatic events experienced by others. Professionals who work therapeutically with trauma victims may be at particular risk for this exposure. This meta‐analysis of 38 published studies examines 17 risk factors for STS among professionals indirectly exposed to trauma through their therapeutic work with trauma victims. Small significant effect sizes were found for trauma caseload volume (r = .16), caseload frequency (r = .12), caseload ratio (r = .19), and having a personal trauma history (r = .19). Small negative effect sizes were found for work support (r = ?.17) and social support (r = ?.26). Demographic variables appear to be less implicated although more work is needed that examines the role of gender in the context of particular personal traumas. Caseload frequency and personal trauma effect sizes were moderated by year of publication. Future work should examine the measurement of STS and associated impairment, understudied risk factors, and effective interventions.     

Stratification of the Impact of Inappropriate Empirical Antimicrobial Therapy for Gram-Negative Bloodstream Infections by Predicted Prognosis

The bloodstream infection mortality risk score (BSIMRS) predicts the outcome of patients with Gram-negative bloodstream infections (BSI) with high discrimination. This retrospective cohort study examined the impact of inappropriate antimicrobial therapy on mortality in adult patients with Gram-negative BSI admitted to Palmetto Health Hospitals in Columbia, SC, USA, from 1 January 2011 to 31 December 2012 after stratification by predicted prognosis at initial presentation using BSIMRS. A multivariate Cox regression model was used to identify independent risk factors for 28-day mortality overall and within each predefined BSIMRS category (<5, 5 to 9, and ≥10). Relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT) were calculated from a predictive logistic regression model of mortality. Overall, 390 unique patients with first episodes of Gram-negative BSI were identified. The median age was 66 years, and 229 (59%) were women. There was significant association between inappropriate antimicrobial therapy and mortality in patients with BSIMRS of 5 to 9 (adjusted hazard ratio [aHR], 3.55; 95% confidence intervals [CI], 1.22 to 8.31; P = 0.02) and BSIMRS of ≥10 (aHR, 4.99; 95% CI, 1.09 to 22.87; P = 0.04) but not in those with BSIMRS of <5 (aHR, 3.34; 95% CI, 0.17 to 22.77; P = 0.34). RRR, ARR, and NNT were 0.25, 0.02, and 63 for BSIMRS of <5; 0.56, 0.32, and 3 for BSIMRS of 5 to 9; and 0.39, 0.39, and 3 for BSIMRS of ≥10, respectively. There is a significant benefit from appropriate antimicrobial therapy in patients with Gram-negative BSI with guarded (BSIMRS of 5 to 9) and poor (BSIMRS of ≥10) predicted prognosis. Survival difference remains unclear among those with good predicted prognosis (BSIMRS of <5) at initial presentation.     

Rewiring yeast sugar transporter preference through modifying a conserved protein motif

Utilization of exogenous sugars found in lignocellulosic biomass hydrolysates, such as xylose, must be improved before yeast can serve as an efficient biofuel and biochemical production platform. In particular, the first step in this process, the molecular transport of xylose into the cell, can serve as a significant flux bottleneck and is highly inhibited by other sugars. Here we demonstrate that sugar transport preference and kinetics can be rewired through the programming of a sequence motif of the general form G-G/F-XXX-G found in the first transmembrane span. By evaluating 46 different heterologously expressed transporters, we find that this motif is conserved among functional transporters and highly enriched in transporters that confer growth on xylose. Through saturation mutagenesis and subsequent rational mutagenesis, four transporter mutants unable to confer growth on glucose but able to sustain growth on xylose were engineered. Specifically, Candida intermedia gxs1 Phe³⁸Ile³⁹Met⁴⁰, Scheffersomyces stipitis rgt2 Phe³⁸ and Met⁴⁰, and Saccharomyces cerevisiae hxt7 Ile³⁹Met⁴⁰Met³⁴⁰ all exhibit this phenotype. In these cases, primary hexose transporters were rewired into xylose transporters. These xylose transporters nevertheless remained inhibited by glucose. Furthermore, in the course of identifying this motif, novel wild-type transporters with superior monosaccharide growth profiles were discovered, namely S. stipitis RGT2 and Debaryomyces hansenii 2D01474. These findings build toward the engineering of efficient pentose utilization in yeast and provide a blueprint for reprogramming transporter properties.Molecular transporter proteins facilitate monosaccharide uptake and serve as the first step in catabolic metabolism. In this capacity, the preferences, regulation, and kinetics of these transporters ultimately dictate total carbon flux (1–3); and optimization of intracellular catabolic pathways only increases the degree to which transport exerts control over metabolic flux (4, 5). Thus, monosaccharide transport profiles and rates are important design criteria and a driving force to enable metabolic engineering advances, ultimately resulting in a biorefinery concept whereby biomass is converted via microbes into a diverse set of molecules (6–10). Among possible host organisms, Saccharomyces cerevisiae is an emerging industrial organism with well-developed genetic tools and established industrial processes and track record (11–16). However, S. cerevisiae lacks an endogenous xylose catabolic pathway and thus is unable to natively use the second most abundant sugar in lignocellulosic biomass. Decades of research have been focused on improving xylose catabolic pathways in recombinant S. cerevisiae (17–22), but less work has been focused on the first committed step of the process—xylose transport, an outstanding limitation in the efficient conversion of lignocellulosic sugars (23, 24).In S. cerevisiae, monosaccharide uptake is mediated by transporters belonging to the major facilitator superfamily (MFS) (25, 26), a ubiquitous group of proteins found across species (27). The predominant transporters in yeast are members of the HXT family (28) and are marked by efficient hexose transport (29) with lower affinities to xylose thus contributing to diauxic growth and flux limitation when attempting pentose utilization in recombinant S. cerevisiae (30). Previous efforts have attempted to identify heterologous transporters with a higher affinity for xylose over glucose (31–36). However, the vast majority of these transporters are either nonfunctional, not efficient, or not xylose specific (24, 37). Furthermore, nearly all known wild-type transporters that enable growth on xylose in yeast confer higher growth rates on glucose than on xylose (24, 37). As an alternative to bioprospecting, we have previously reported that xylose affinity and exponential growth rates on xylose can be improved via directed evolution of Candida intermedia glucose-xylose symporter 1 (GXS1) and Scheffersomyces stipitis xylose uptake 3 (XUT3) (38). These results demonstrated that mutations at specific residues (e.g., Phe⁴⁰ in C. intermedia GXS1) can have a significant impact on the carbohydrate selectivity of these MFS transporters. The fact that single amino acid substitutions can have such a significant impact on transport phenotype (38–40) indicates how simple homology based searches can be ineffective at identifying efficient xylose transporters (35, 36). However, evidence of natural xylose exclusivity is seen in the Escherichia coli xylE transporter that has recently been crystallized (41). The sequence-function flexibility of MFS transporters potentiates the capability to rewire hexose transporters from being glucose favoring, xylose permissive into being xylose-exclusive transporters.In this work, we report on the discovery of a conserved Gly³⁶-Gly³⁷-Val³⁸-Leu³⁹-Phe⁴⁰-Gly⁴¹ motif surrounding the previously identified Phe⁴⁰ residue of C. intermedia GXS1 that controls transporter efficiency and selectivity. By evaluating 46 different heterologously expressed transporters, we find that this motif is conserved among functional transporters and highly enriched in transporters that confer growth on xylose, taking the general form G-G/F-XXX-G. We conduct saturation mutagenesis on Val³⁸, Leu³⁹, and Phe⁴⁰ within the variable region of this motif in C. intermedia GXS1 to demonstrate control of sugar selectivity. Next, we combine xylose-favoring mutations to create a unique mutant version of gxs1 that transports xylose, but not glucose. Finally, we demonstrate the importance of this motif in the capacity to rewire the sugar preference of other hexose transporters including S. cerevisiae hexose transporter 7 (HXT7) and S. stipitis glucose transporter/sensor (RGT2, similar to S. cerevisiae RGT2). This work serves to increase our understanding of the structure–function relationships for molecular transporter engineering and demonstrates complete rewiring of hexose transporters into transporters that prefer xylose as a substrate.