ABSTRACT
Hemin dissociation occurs much faster from fish methemoglobin (metHb) compared to mammalian metHb yet the mechanism remains poorly understood. This may involve enhanced solvent access to His(E7) of fish metHbs by a protonation mechanism. Plasma induced modification of biomolecules (PLIMB) produces free radicals that covalently modify solvent accessible residues of proteins, and so can provide insight regarding accessibility of hydronium ions to protonate His(E7). PLIMB-induced modifications to heme crevice sites of trout IV and bovine metHb were determined using tandem mass spectrometry after generating peptides with Trypsin/Lys-C. αHis(CE3) was more modified in trout attributable to the more dynamic nature of bovine αHis(CE3) from available crystal structures. Although His(E7) was not found to be more modified in trout, aspects of trout peptides containing His(E7) hampered modification determinations. An existing computational structure-based approach was also used to estimate protonation tendencies, suggesting His(E7) of metHbs with low hemin affinity are more protonatable.
Subject(s)
Fish Proteins , Hemin , Methemoglobin , Animals , Hemin/chemistry , Cattle , Fish Proteins/chemistry , Methemoglobin/chemistry , Trout/metabolism , Tandem Mass SpectrometryABSTRACT
Fascin-1-mediated actin-bundling activity is central to the generation of plasma membrane protrusions required for cell migration. Dysregulated formation of cellular protrusions is observed in metastatic cancers, where they are required for increased invasiveness, and is often correlated with increased Fascin-1 abundance. Therefore, there is interest in generating therapeutic Fascin-1 inhibitors. We present the identification of Nb 3E11, a nanobody inhibitor of Fascin-1 actin-bundling activity and filopodia formation. The crystal structure of the Fascin-1/Nb 3E11 complex reveals the structural mechanism of inhibition. Nb 3E11 occludes an actin-binding site on the third ß-trefoil domain of Fascin-1 that is currently not targeted by chemical inhibitors. Binding of Nb 3E11 to Fascin-1 induces a conformational change in the adjacent domains to stabilize Fascin-1 in an inhibitory state similar to that adopted in the presence of small-molecule inhibitors. Nb 3E11 could be used as a tool inhibitor molecule to aid in the development of Fascin-1 targeted therapeutics.
Subject(s)
Actins , Carrier Proteins , Microfilament Proteins , Pseudopodia , Actins/metabolism , Pseudopodia/metabolism , Protein Binding , Cell MovementABSTRACT
Although Mn(III) complexes with organic ligands have been previously identified, the information about their stability and reactivity is scarce. In the present study, we analyzed the formation and stability of three different complexes: Mn(III)-citrate, Mn(III)-tartrate, and Mn(III)-humic acid (HA), as well as their reactivity toward an element of high environmental concern, lead (Pb).Our results indicate that the stability of studied complexes is highly dependent on pH. The Mn(III) complexes with citrate and tartrate degrade below pH 8, due to the electron transfer reaction between Mn(III) and the ligand, while the Mn(III)-HA complex's degradation is slower and less sensitive to pH. At pH 4, less than 40% of the initial Mn(III)-HA was found to be stable.The reactivity of the complexes was different depending on the ligand and its concentration. The Mn(III)-citrate and Mn(III)-tartrate complexes effectively reduced PbO2 and releases aqueous Pb2+, although significant differences were found with increasing ligand concentration. There was no evidence of the reduction of PbO2 by Mn(III) when it forms a complex with HA. This is likely due to the large size of HA moieties that prevent the Mn(III) component of the complex from getting close enough to the PbO2 surface to initiate electron transfer and lead to the reduction of Pb(IV) by HA itself.
Subject(s)
Humic Substances , Tartrates , Oxidation-Reduction , Ligands , Lead , Molecular Weight , CitratesABSTRACT
Melioidosis is a disease that is difficult to treat due to the causative organism, Burkholderia pseudomallei being inherently antibiotic resistant and it having the ability to invade, survive, and replicate in an intracellular environment. Combination therapy approaches are routinely being evaluated in animal models with the aim of improving the level of protection and clearance of colonizing bacteria detected. In this study, a subunit vaccine layered with the antibiotic finafloxacin was evaluated in vivo against an inhalational infection with B. pseudomallei in Balb/c mice. Groups of mice vaccinated, infected, and euthanized at antibiotic initiation had a reduced bacterial load compared to those that had not been immunized. In addition, the subunit vaccine provided a synergistic effect when it was delivered with a CpG ODN and finafloxacin was initiated at 48 h post-challenge. Vaccination was also shown to improve the outcome, in a composite measure of survival and clearance. In summary, layering a subunit vaccine with the antibiotic finafloxacin is a promising therapeutic alternative for use in the treatment of B. pseudomallei infections.
Subject(s)
Burkholderia pseudomallei , Melioidosis , Animals , Mice , Mice, Inbred BALB C , Melioidosis/drug therapy , Melioidosis/prevention & control , Anti-Bacterial Agents/therapeutic use , Vaccination , Vaccines, Subunit , Disease Models, AnimalABSTRACT
The endothelial junction component vascular endothelial (VE)-cadherin governs junctional dynamics in the blood and lymphatic vasculature. Here, we explored how lymphatic junction stability is modulated by elevated VEGFA signaling to facilitate metastasis to sentinel lymph nodes. Zippering of VE-cadherin junctions was established in dermal initial lymphatic vessels after VEGFA injection and in tumor-proximal lymphatics in mice. Shape analysis of pan-cellular VE-cadherin fragments revealed that junctional zippering was accompanied by accumulation of small round-shaped VE-cadherin fragments in the lymphatic endothelium. In mice expressing a mutant VEGFR2 lacking the Y949 phosphosite (Vegfr2 Y949F/Y949F ) required for activation of Src family kinases, zippering of lymphatic junctions persisted, whereas accumulation of small VE-cadherin fragments was suppressed. Moreover, tumor cell entry into initial lymphatic vessels and subsequent metastatic spread to lymph nodes was reduced in mutant mice compared with WT, after challenge with B16F10 melanoma or EO771 breast cancer. We conclude that VEGFA mediates zippering of VE-cadherin junctions in initial lymphatics. Zippering is accompanied by increased VE-cadherin fragmentation through VEGFA-induced Src kinase activation, correlating with tumor dissemination to sentinel lymph nodes.
Subject(s)
Endothelial Cells , Lymphatic Vessels , Mice , Animals , Lymphatic Metastasis , Cadherins/genetics , src-Family Kinases/geneticsABSTRACT
Meleagris gallopavo (turkey) coexpresses distinct hemoglobin (Hb) isoforms, Hb α2Aß2 (HbA) and α2Dß2 (HbD), at a ratio of â¼3:1 (HbA:HbD). Herein, the reactivities of HbA and HbD were investigated in their native and free fatty acid (FFA)-modified states. Results indicated that HbD displays elevated autoxidation (kox) and an increased propensity to oxidize lipids in its reduced (oxy) and oxidized (met) forms. Interestingly, metHbD displayed less heme-globin cross-linking compared to HbA. Regarding FFA-modified Hb, we found that an FFA mixture and linoleic acid (LA) produced a bis-histidyl ferric (Bis-His) Hb species, decreasing the ability of Hb to oxidize lipids. Using molecular docking, we found LA to hydrogen bond with ß Arg C6, found at the α1ß2 interface, but the extent of Bis-His formation differs between HbA and HbD. Our findings suggest HbA displays elevated oxidative stability compared to HbD and that FFA may act as allosteric effectors of metHb.
Subject(s)
Fatty Acids , Hemoglobin A , Hemoglobin A/chemistry , Molecular Docking Simulation , Hemoglobins/chemistry , Protein IsoformsABSTRACT
Cardiovascular diseases are responsible for almost 10,000 deaths annually in Aotearoa New Zealand. Almost a quarter of these are avoidable, increasing to half of all cardiovascular deaths for Maori and Pacific people. Health system reforms are an opportunity to set clear ambitious goals for improved heart health. This has been done for smoking, a cancer plan, mental health and diabetes among other health conditions. Given the scale of avoidable heart disease and avoidable heart health inequity, much of it due to people simply not accessing existing treatment options, there is no excuse not to deliver a national heart health action plan and we urge health policy makers to put it on the agenda.
Subject(s)
Cardiovascular Diseases , Heart Diseases , Humans , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/prevention & control , Maori People , New Zealand/epidemiology , Pacific Island PeopleABSTRACT
The existence of a thin, weak asthenospheric layer beneath Earth's lithospheric plates is consistent with existing geological and geophysical constraints, including Pleistocene glacio-isostatic adjustment, modeling of gravity anomalies, studies of seismic anisotropy, and post-seismic rebound. Mantle convection models suggest that a pronounced weak zone beneath the upper thermal boundary layer (lithosphere) may be essential to the plate tectonic style of convection found on Earth. The asthenosphere is likely related to partial melting and the presence of water in the sub-lithospheric mantle, further implying that the long-term evolution of the Earth may be controlled by thermal regulation and volatile recycling that maintain a geotherm that approaches the wet mantle solidus at asthenospheric depths.
ABSTRACT
AIMS: Heart rate score (HRSc), the per cent of atrial paced and sensed event in the largest 10â b.p.m. rate histogram bin of a pacemaker, predicts survival in patients with cardiac devices. No correlation between HRSc and development of atrial fibrillation (AF) has been reported. In this study, we evaluated the relationship between pacemaker post-implantation HRSc and the incidence of newly developed atrial tachyarrhythmias (ATAs). METHODS AND RESULTS: Patients with dual-chamber pacemakers, implanted 2013-17, with the LATITUDE remote monitoring data with ≥600 000 beats of histogram data collected at baseline were included (N = 34 543). Heart rate score was determined from the initial 3-month post-implantation histogram data. Patients were excluded if they had ATAs, defined as atrial high-rate episodes >5â min or >1% of right atrial beats >170â b.p.m. during the initial 3 months post-implantation. New ATAs, after the baseline period, were defined by each of the following: >1, >10, or >25% of atrial beats >170â b.p.m. or atrial tachycardia response (ATR) events >24â h. Patients were followed a median of 2.8 (1.0-4.0) years. The incidence of ATAs increased in proportion to HRSc (log-rank P-value <0.001), and the initial HRSc ≥70% was associated with increased ATAs by all definitions. Patients with initial HRSc ≥70% were older, had a higher percentage of right atrium pacing (%RA pacing), had a lower percentage of right ventricular pacing (%RV pacing), and were more likely programmed with rate-response vs. subjects with HRSc <70%. Initial HRSc (hazard ratio: 1.07, 95% confidence interval: 1.05-1.09; P < 0.0001) independently predicted ATAs after adjusting for age, gender, %RV pacing, and rate-response programming. The %RA pacing and initial HRSc were correlated. CONCLUSION: Heart rate score independently predicts any subsequent duration of ATAs in pacemaker patients.
Subject(s)
Atrial Fibrillation , Pacemaker, Artificial , Humans , Heart Rate/physiology , Pacemaker, Artificial/adverse effects , Atrial Fibrillation/diagnosis , Atrial Fibrillation/epidemiology , Atrial Fibrillation/etiology , Heart Atria , Tachycardia/diagnosis , Tachycardia/epidemiology , Cardiac Pacing, Artificial/adverse effects , Cardiac Pacing, Artificial/methodsABSTRACT
Endothelial phospholipase Cγ (PLCγ) is essential for vascular development; however, its role in healthy, mature, or pathological vessels is unexplored. Here, we show that PLCγ was prominently expressed in vessels of several human cancer forms, notably in renal cell carcinoma (RCC). High PLCγ expression in clear cell RCC correlated with angiogenic activity and poor prognosis, while low expression correlated with immune cell activation. PLCγ was induced downstream of vascular endothelial growth factor receptor 2 (VEGFR2) phosphosite Y1173 (pY1173). Heterozygous Vegfr2Y1173F/+ mice or mice lacking endothelial PLCγ (Plcg1iECKO) exhibited a stabilized endothelial barrier and diminished vascular leakage. Barrier stabilization was accompanied by decreased expression of immunosuppressive cytokines, reduced infiltration of B cells, helper T cells and regulatory T cells, and improved response to chemo- and immunotherapy. Mechanistically, pY1173/PLCγ signaling induced Ca2+/protein kinase C-dependent activation of endothelial nitric oxide synthase (eNOS), required for tyrosine nitration and activation of Src. Src-induced phosphorylation of VE-cadherin at Y685 was accompanied by disintegration of endothelial junctions. This pY1173/PLCγ/eNOS/Src pathway was detected in both healthy and tumor vessels in Vegfr2Y1173F/+ mice, which displayed decreased activation of PLCγ and eNOS and suppressed vascular leakage. Thus, we believe that we have identified a clinically relevant endothelial PLCγ pathway downstream of VEGFR2 pY1173, which destabilizes the endothelial barrier and results in loss of antitumor immunity.
Subject(s)
Capillary Permeability , Carcinoma, Renal Cell , Kidney Neoplasms , Animals , Humans , Mice , Capillary Permeability/genetics , Carcinoma, Renal Cell/immunology , Kidney Neoplasms/immunology , Nitric Oxide Synthase Type III/genetics , Nitric Oxide Synthase Type III/metabolism , Phospholipase C gamma/genetics , Phospholipase C gamma/metabolism , Phosphorylation , Vascular Endothelial Growth Factor A/metabolism , Vascular Endothelial Growth Factor Receptor-2/genetics , Vascular Endothelial Growth Factor Receptor-2/metabolism , CSK Tyrosine-Protein Kinase/metabolismABSTRACT
OBJECTIVES: To describe gender and geographical inequalities in invitations to review and the response to these invitations and to assess whether inequalities increased during the covid-19 pandemic. DESIGN: Retrospective cohort study. SETTING: 19 specialist medical journals and two large general medical journals from BMJ Publishing Group. POPULATION: Reviewers invited to review manuscripts submitted between 1 January 2018 and 31 May 2021. The cohort was followed up to 28 February 2022. MAIN OUTCOME MEASURES: Reviewer's agreement to review. RESULTS: A total of 257 025 reviewers were invited (38.6% (88 454/228 869) women), and 90 467 (35.2%) agreed to review. Invited reviewers were mainly (217 682; 84.7%) affiliated with high income countries: Europe (122 414; 47.6%), North America (66 931; 26.0%), Africa (25 735; 10.0%), Asia (22 693; 8.8%), Oceania (16 175; 6.3%), and South America (3076; 1.2%). Independent factors associated with agreement to review were gender (odds ratio 0.89, 95% confidence interval 0.87 to 0.92, for women compared with men), geographical affiliation (2.89, 2.73 to 3.06, for Asia; 3.32, 2.94 to 3.75 for South America; 1.35, 1.27 to 1.43, for Oceania; and 0.35, 0.33 to 0.37, for Africa compared with Europe), and country income (0.47, 0.45 to 0.49, for upper middle income; 5.12, 4.67 to 5.61, for lower middle income; and 4.66, 3.79 to 5.73, for low income compared with high income country). Agreement was also independently associated with editor's gender (0.96, 0.93 to 0.99, for women compared with men), last author's geographical affiliation (0.80, 0.78 to 0.83, for Asia; 0.89, 0.85 to 0.94, for Oceania compared with Europe), impact factor (1.78, 1.27 to 2.50, for >10 compared with <5), and type of peer review process (0.52, 0.35 to 0.77, for open compared with anonymised). During the first and second phases of the pandemic, agreement was lower than in the pre-pandemic period (P<0.001). The interaction between time periods and covid-19 related topic and reviewer's gender was non-significant. However, significant interaction was found between time periods and covid-19 related topic and reviewer's geographical affiliation. CONCLUSIONS: To reduce bias and improve diversity, editors need to identify and implement effective strategies and continually evaluate progress against these to ensure that more women and researchers from upper middle income and low income countries are involved in review.
Subject(s)
COVID-19 , Periodicals as Topic , Male , Humans , Female , COVID-19/epidemiology , Cohort Studies , Pandemics , Retrospective StudiesABSTRACT
Background: In heart failure (HF), symptoms and health-related quality of life (HRQoL) are known to vary among different HF subgroups, but evidence on the association between changing HRQoL and outcomes has not been evaluated. Objectives: The authors sought to investigate the relationship between changing symptoms, signs, and HRQoL and outcomes by sex, ethnicity, and socioeconomic status (SES). Methods: Using the ASIAN-HF (Asian Sudden Cardiac Death in Heart Failure) Registry, we investigated associations between the 6-month change in a "global" symptoms and signs score (GSSS), Kansas City Cardiomyopathy Questionnaire overall score (KCCQ-OS), and visual analogue scale (VAS) and 1-year mortality or HF hospitalization. Results: In 6,549 patients (mean age: 62 ± 13 years], 29% female, 27% HF with preserved ejection fraction), women and those in low SES groups had higher symptom burden but lower signs and similar KCCQ-OS to their respective counterparts. Malay patients had the highest GSSS (3.9) and lowest KCCQ-OS (58.5), and Thai/Filipino/others (2.6) and Chinese patients (2.7) had the lowest GSSS scores and the highest KCCQ-OS (73.1 and 74.6, respectively). Compared to no change, worsening of GSSS (>1-point increase), KCCQ-OS (≥10-point decrease) and VAS (>1-point decrease) were associated with higher risk of HF admission/death (adjusted HR: 2.95 [95% CI: 2.14-4.06], 1.93 [95% CI: 1.26-2.94], and 2.30 [95% CI: 1.51-3.52], respectively). Conversely, the same degrees of improvement in GSSS, KCCQ-OS, and VAS were associated with reduced rates (HR: 0.35 [95% CI: 0.25-0.49], 0.25 [95% CI: 0.16-0.40], and 0.64 [95% CI: 0.40-1.00], respectively). Results were consistent across all sex, ethnicity, and SES groups (interaction P > 0.05). Conclusions: Serial measures of patient-reported symptoms and HRQoL are significant and consistent predictors of outcomes among different groups with HF and provide the potential for a patient-centered and pragmatic approach to risk stratification.
ABSTRACT
Antimicrobial resistance is a global issue, and the investigation of alternative therapies that are not traditional antibiotics are warranted. Novel bacterial type II topoisomerase inhibitors (NBTIs) have recently emerged as a novel class of antibiotics with reduced potential for cross-resistance to fluoroquinolones due to their novel mechanism of action. This study investigated the in vitro activity of a series of cyclohexyl-oxazolidinone bacterial topoisomerase inhibitors against type strains of Francisella tularensis and Burkholderia pseudomallei. Broth microdilution, time-kill, and cell infection assays were performed to determine activity against these biothreat pathogens. Two candidates were identified that demonstrated in vitro activity in multiple assays that in some instances was equivalent to ciprofloxacin and doxycycline. These data warrant the further evaluation of these novel NBTIs and future iterations in vitro and in vivo.
ABSTRACT
AIMS: In bradycardia patients treated with dual-chamber pacing, we aimed to evaluate whether pacing with atrioventricular (AV) delay management [AV hysteresis (AVH)], compared with standard pacing with fixed AV delays, reduces unnecessary ventricular pacing percentage (VPP) and is associated with better clinical outcomes. Main study endpoints were the incidence of heart failure hospitalizations (HFH), persistent atrial fibrillation (AF), and cardiac death. METHODS AND RESULTS: Data from two identical prospective observational studies, BRADYCARE I in the USA and BRADYCARE II in Europe, Africa, and Asia, were pooled. Overall, 2592 patients (75 ± 10 years, 45.1% female, 50% with AVH) had complete clinical and device data at 1-year follow-up and were analysed. Primary pacing indication was sinus node disease (SND) in 1177 (45.4%), AV block (AVB) in 974 (37.6%), and other indications in 441 (17.0%) patients. Pacing with AVH, compared with standard pacing, was associated with a lower 1-year incidence of HFH [1.3% vs. 3.1%, relative risk reduction (RRR) 57.5%, P = 0.002] and of persistent AF (5.3% vs. 7.7%, RRR = 31.1%, P = 0.028). Cardiac mortality was not different between groups (1.0% vs. 1.4%, RRR = 27.8%, P = 0.366). Pacing with AVH, compared with standard pacing, was associated with a lower (P < 0.001) median VPP in all patients (7% vs. 75%), in SND (3% vs. 44%), in AVB (25% vs. 98%), and in patients with other pacing indications (3% vs. 47%). CONCLUSION: Cardiac pacing with AV delay management via AVH is associated with reduced 1-year incidence of HFH and persistent AF, most likely due to a reduction in VPP compared to standard pacing.
Subject(s)
Atrial Fibrillation , Heart Failure , Pacemaker, Artificial , Humans , Female , Male , Atrial Fibrillation/diagnosis , Atrial Fibrillation/epidemiology , Atrial Fibrillation/prevention & control , Cardiac Pacing, Artificial/methods , Incidence , Treatment Outcome , Pacemaker, Artificial/adverse effects , Sick Sinus Syndrome/therapy , Heart Failure/diagnosis , Heart Failure/epidemiology , Heart Failure/prevention & control , HospitalizationABSTRACT
Lentil, an important pulse crop in Australia, is sown soon after the onset of autumn rains and grows mainly under rainfed conditions. This study examined lentil phenological development, growth and grain yield under different sowing dates and environments in New South Wales (NSW). Eight lentil varieties were phenotyped over two years and four sowing times in southern NSW (Leeton, Wagga Wagga and Yanco (one year)) and central western NSW (Trangie). Time of sowing affected important agronomic traits, with a delay in sowing decreasing time to flowering and podding, biomass accumulation, plant height and position of bottom pod. Sowing earlier or later than optimum decreased grain yield. Yield was mainly determined by the number of pods and seeds per plant, with minimal impact from seed weight. Overall, yields were higher in favorable environments such Leeton experiment which received more water compared to the other sites which received less water. Averaged across sowing dates, the slower maturing PBA Greenfield was lower yielding whilst fast maturing varieties such as PBA Bolt and PBA Blitz yielded higher. PBA Jumbo2 is less sensitive to environmental interaction and thus broadly adapted to the diverse environments. Optimum sowing time was identified as the end of April to mid-May.
ABSTRACT
The objective of this study was to elucidate the effect of phospholipase A2 (PLA2) and a PLA2 antibody (aPLA2) on phospholipid (PL) hydrolysis in beef and to understand how the altered PL composition may affect lipid oxidation and antioxidant capacity of beef in an in vitro system. Various combinations of PLA2 and aPLA2 were introduced to a beef liposome model system and exposed to a retail display. The PL and free fatty acid (FFA) profiles, antioxidant capacity and lipid oxidation were measured for the liposome system. Key PL classes were reduced and the release of polyunsaturated FFAs was increased with the inclusion of PLA2 in the treatments (P < 0.05). There was no inhibition of PL hydrolysis with the addition of aPLA2. PLA2 showed strong antioxidant capacity in the liposome system (P < 0.01), but lipid oxidation still increased in samples treated with PLA2 throughout the retail display (P < 0.01). Finally, aPLA2 treatments demonstrated potential to decrease lipid oxidation (P < 0.01).
Subject(s)
Antioxidants , Liposomes , Animals , Cattle , Phospholipases A2 , Phospholipids , Hydrolysis , Fatty Acids, NonesterifiedABSTRACT
Despite the wide adoption of insertable cardiac monitors (ICMs), high false-positive rates, suboptimal signal quality, limited ability to detect atrial flutter, and lack of remote programming remain challenging. The LUX-Dx PERFORM study was designed to evaluate novel technologies engineered to address these issues. Here, we present preliminary results from the trial focusing on the safety of ICM insertion, remote monitoring rates, and the feasibility of remote programming. LUX-Dx PERFORM is a multicenter, prospective, single-arm, post-market, observational study with planned enrollment of up to 827 patients from 35 sites in North America. A preliminary cohort consisting of the first 369 patients who were enrolled between March and October 2021 was selected for analysis. Three hundred sixty-three (363) patients had ICM insertions across inpatient and outpatient settings. The mean time followed was 103.4 ± 61.8 days per patient. The total infection rate was 0.8% (3/363). Interim results show high levels of remote monitoring with a median 94% of days with data transmission (interquartile range: 82-99). Thirteen (13) in-clinic and 24 remote programming sessions were reported in 34 subjects. Reprogramming examples are presented to highlight signal quality, the ability to detect atrial flutter, and the positive impact of remote programming on patient management. Interim results from LUX-Dx PERFORM study demonstrate the safety of insertion, high data transmission rates, the ability to detect atrial flutter, and the feasibility of remote programming to optimize arrhythmia detection and improve clinical workflow. Future results from LUX-Dx PERFORM will further characterize improvements in signal quality and arrhythmia detection.
Subject(s)
Atrial Fibrillation , Atrial Flutter , Humans , Atrial Fibrillation/diagnosis , Electrocardiography, Ambulatory/methods , Prospective Studies , OutpatientsABSTRACT
Burkholderia mallei, the causative agent of glanders, is principally a disease of equines, although it can also infect humans and is categorized by the U.S. Centers for Disease Control and Prevention as a category B biological agent. Human cases of glanders are rare and thus there is limited information on treatment. It is therefore recommended that cases are treated with the same therapies as used for melioidosis, which for prophylaxis, is co-trimoxazole (trimethoprim/sulfamethoxazole) or co-amoxiclav (amoxicillin/clavulanic acid). In this study, the fluoroquinolone finafloxacin was compared to co-trimoxazole as a post-exposure prophylactic in a murine model of inhalational glanders. BALB/c mice were exposed to an aerosol of B. mallei followed by treatment with co-trimoxazole or finafloxacin initiated at 24 h post-challenge and continued for 14 days. Survival at the end of the study was 55% or 70% for mice treated with finafloxacin or co-trimoxazole, respectively, however, this difference was not significant. However, finafloxacin was more effective than co-trimoxazole in controlling bacterial load within tissues and demonstrating clearance in the liver, lung and spleen following 14 days of therapy. In summary, finafloxacin should be considered as a promising alternative treatment following exposure to B. mallei.
ABSTRACT
Burkholderia pseudomallei is the causative agent of melioidosis, a multifaceted disease. A proportion of the mortality and morbidity reported as a result of infection with this organism may be due to the premature cessation of antibiotic therapy typically lasting for several months. The progression of re-emergent disease was characterised in Balb/c mice following cessation of a 14 day treatment course of co-trimoxazole or finafloxacin, delivered at a human equivalent dose. Mice were culled weekly and the infection characterised in terms of bacterial load in tissues, weight loss, clinical signs of infection, cytokine levels and immunological cell counts. Following cessation of treatment, the infection re-established in some animals. Finafloxacin prevented the re-establishment of the infection for longer than co-trimoxazole, and it is apparent based on the protection offered, the development of clinical signs of disease, bodyweight loss and bacterial load, that finafloxacin was more effective at controlling infection when compared to co-trimoxazole.