Vitamin D Supplementation and the Incidence of Fractures in the Elderly Healthy Population: A Meta-analysis of Randomized Controlled Trials.

INTRODUCTION: Although a well-established component of bone metabolism, the efficacy and safety of vitamin D supplementation for the prevention of fractures in elderly healthy individuals is still unclear. PURPOSE: To perform a meta-analysis comparing vitamin D supplementation with placebo and its contributions on fracture incidence. METHODS: This meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO), under protocol CRD42023484979. We systematically searched PubMed, Embase, and Cochrane Central databases from inception to November 2023 for randomized controlled trials (RCTs) comparing vitamin D supplementation versus placebo in individuals with 60 years of age or more and without bone related medical conditions such as cancer and osteoporosis. RESULTS: Seven RCTs with 71,899 patients were included, of whom 36,822 (51.2%) were women. There was no significant difference in total fracture incidence (RR 1.03; 95% CI 0.93-1.14; p = 0.56; I2 = 58%) between groups or subgroups. However, women had an increased risk for hip fractures (164 vs. 121 events; RR 1.34; 95% CI 1.06-1.70; p = 0.01; I2 = 0%). There was no significant difference in non-vertebral fractures, osteoporotic fractures development, or falls (RR 1.02; 95% CI 0.94-1.12; p = 0.6; I2 = 47%; RR 0.97; 95% CI 0.87-1.08; p = 0.63; I2 = 0%; RR 1.01; 95% CI 0.97-1.04; p = 0.66; I2 = 55%, respectively). CONCLUSION: Vitamin D supplementation does not reduce the total fracture development rate in the elderly healthy population, and it may increase the incidence of hip fractures among elderly healthy women. This finding suggests refraining from prescribing high intermittent doses of vitamin D, without calcium, to individuals aged 60 or older with unknown vitamin D serum concentration or osteoporosis status and inadequate calcium intake.

Resistance Training with Instability Does Not Hamper Total Training Volume and Muscle Strength Gains in Older Adults: a Secondary Analysis from REI Study.

Background: Resistance training with instability (REI) emerged as a promising training modality for older adults aiming to counteract age-related changes. Objectives: We compared the effects of 12 weeks of REI and traditional resistance exercise (RE) on muscle strength in older adults with cognitive impairment. We further explored if total training volume (TTV) significantly differs among training groups. Methods: This is a secondary analysis of the REI study. Participants were randomly assigned to REI (n=22) or RE (n=23). RE protocol involved moderate-intensity, free-weight, and machines-based resistance exercises (3 sets, 10-15 repetitions). REI received a similar training protocol, in which exercises were simultaneously performed with instability/unstable devices (e.g., squat exercise under a foam pad or Bosu® ball). Maximal isometric strength and isokinetic parameters were assessed at baseline and after completion of a 12-week intervention through a hydraulic handgrip and isokinetic dynamometer, respectively. TTV (sets × repetitions × load) was computed based on external training load over the 12 weeks. Results: No differences were observed between groups (p=.35) after the intervention. Over 12 weeks, REI and RE improved isometric handgrip strength (p<.001) and isokinetic performance (p=.04). We also did not find differences in the TTV between training groups (p=.28). Conclusion: We demonstrated that both REI and RE training induced similar gains in muscle strength. Combining unstable surfaces/instability devices did not hamper TTV, which may have clinical applications in the context of exercise for older adults.

Structure-Metabolism Relationships of benzimidazole derivatives with anti-Trypanosoma cruzi activity for Chagas disease.

This study introduces further insights from the hit-to-lead optimization process involving a series of benzimidazole derivatives acting as inhibitors of the cruzain enzyme, which targets Trypanosoma cruzi, the causative parasite of Chagas disease. Here, we present the design, synthesis and biological evaluation of 30 new compounds as a third generation of benzimidazole analogues with trypanocidal activity, aiming to enhance our understanding of their pharmacokinetic profiles and establish a structure-metabolism relationships within the series. The design of these new analogues was guided by the analysis of previous pharmacokinetic results, considering identified metabolic sites and biotransformation studies. This optimization resulted in the discovery of two compounds (42e and 49b) exhibiting enhanced metabolic stability, anti-Trypanosoma cruzi activity compared to benznidazole (the reference drug for Chagas disease), as well as being non-cruzain inhibitors, and demonstrating a satisfactory in vitro pharmacokinetic profile. These findings unveil a new subclass of aminobenzimidazole and rigid compounds, which offer potential for further exploration in the quest for discovering novel classes of antichagasic compounds.

Exploring botulinum toxin's impact on masseter hypertrophy: a randomized, triple-blinded clinical trial.

The present study aimed to assess the effectiveness and functional adverse effects of a single and multiple injections of botulinum toxin A (BoNT-A) for masseter hypertrophy (MH). Twenty-six women complaining about lower third facial enlargement due to MH, received 75 U of BoNT-A (abobotulinum toxin) in each masseter muscles. After 3 months, patients were randomly assigned to receive a second treatment session of Saline Solution: (G1; n = 11) or BoNT-A: (G2; n = 12). Muscle thickness (ultrasound), electrical activity (electromyography; EMG), masticatory performance, and subjective perception of MH were evaluated. Follow-up was performed at 1, 3 and 6 months. Muscle thickness, EMG activity, and masticatory performance were analyzed using ANOVA two-way and Sidak test as post-hoc. Masticatory performance was analyzed by the Friedman's test and Mann-Whitney test. Regarding inter-groups comparisons, there was a significant decrease in the left masseter muscle thickness in the G2 group at the 6 month follow-up (p < 0.02). For EMG, significant differences were evident at the 6 month assessment, with higher masseter activity for G1 (p < 0.05). For masticatory performance, no significant differences were observed throughout the study (p > 0.05) and a higher improvement in subjective perception of MH was observed in the 1 month follow-up for G2 (p < 0.05). In conclusion, BoNT-A is effective for MH, however multiple injections cause functional adverse effects in masseter muscle.

Botulinum Toxin-A for the Treatment of Myogenous Temporomandibular Disorders: An Umbrella Review of Systematic Reviews.

OBJECTIVE: Temporomandibular disorders (TMDs) encompass several conditions that cause pain and impair function of the masticatory muscles (M-TMDs) and temporomandibular joints. There is a large interest among clinicians and researchers in the use of botulinum toxin-A (BoNT-A) as a treatment for M-TMD. However, due to the lack of consistent evidence regarding the efficacy as well as adverse events of BoNT-A, clinical decision making is challenging. Therefore, this umbrella review aimed to systematically assess systematic reviews (SRs) evaluating BoNT-A treatment effects on pain intensity, mandibular movements, and adverse events in patients with M-TMDs. METHOD: An electronic search was undertaken in the databases MEDLINE, EMBASE, CINAHL, Cochrane Central Registry of Controlled Trials (CENTRAL), Web of Science, Epistemonikos, ClinicalTrials.gov, and ICTRP to identify SRs investigating BoNT-A effects on M-TMDs, published from the inception of each database until 6 December 2023. The quality of evidence was rated according to the critical appraisal checklist developed by the umbrella review methodology working group. Only high-quality SRs were included. RESULTS: In total, 18 SRs were included. BoNT-A was shown to be more effective than placebo to reduce pain intensity, but not compared to standard treatments. Additionally, BoNT-A was not superior to placebo or standard treatments regarding improvement of mandibular movements. BoNT-A was considered to have a higher risk for adverse events on muscle and bony tissue compared with other treatments. CONCLUSION: The synthesis in this umbrella review provides the highest level of evidence present. Taken together, there are indications of effectiveness of BoNT-A for treatment of M-TMDs, supported by moderate evidence. However, considering the risk of causing serious adverse events, treatment with BoNT-A is recommended to be the last treatment alternative.

Temporalis Muscle Changes Following Botulinum Toxin A Injections in Masseter Hypertrophy Patients: A Randomized Triple-Blinded Trial.

BACKGROUND: This study aimed to elucidate the effects of botulinum toxin A (BoNT-A) treatment for patients diagnosed with masseter hypertrophy on the temporalis muscle, with a particular focus on assessing alterations in muscle thickness, electromyographic (EMG) activity, and the development of muscle pain. METHODS: The present randomized triple-blinded clinical trial enrolled 26 female participants aged between 25 and 50 years complaining about masseter hypertrophy. Participants received 75U of BoNT-A (abobotulinumtoxinA) in both masseter muscles and after three months were randomized to receive a second treatment session of saline solution (S-BoNT-A) or BoNT-A (M-BoNT-A). Longitudinal assessments included temporalis muscle thickness through ultrasound, EMG activity, subjective pain, and masseter prominence severity after one, three, and six months of the first injection session. Muscle thickness, EMG, and subjective pain were analysed using two-way ANOVA with repeated measures and post hoc Sidak test, and for masseter prominence severity, Friedman and Mann-Whitney tests were used. RESULTS: Regarding inter-group comparisons, a higher muscle thickness (p < 0.02) and a higher EMG activity (p < 0.01) were found in the M-BoNT-A group at the 6-month follow-up. For subjective pain assessments, inter-group comparisons showed a higher prevalence of painful regions in M-BoNT-A group at the 6-month follow-up (p < 0.02). No significant differences were found in masseter prominence severity at the 6 months assessment between groups. CONCLUSION: BoNT-A treatment for masseter hypertrophy lead to structural and functional changes in the temporalis muscle, presenting higher changes after multiple injections of this treatment. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Unveiling ochratoxin A and ochratoxigenic fungi in Brazilian artisanal Cheeses: Insights from production to consumption.

Ochratoxin A (OTA) is a toxin produced by several Aspergillus species, mainly those belonging to section Circumdati and section Nigri. The presence of OTA in cheese has been reported recently in cave cheese in Italy. As artisanal cheese production in Brazil has increased, the aim of this study was to investigate the presence of ochratoxin A and related fungi in artisanal cheese consumed in Brazil. A total of 130 samples of artisanal cheeses with natural moldy rind at different periods of maturation were collected. Of this total, 79 samples were collected from 6 producers from Canastra region in the state of Minas Gerais, since this is the largest artisanal cheese producer region; 13 samples from one producer in the Amparo region in the state of São Paulo and 36 samples from markets located in these 2 states. Aspergillus section Circumdati occurred in samples of three producers and some samples from the markets. A. section Circumdati colony counts varied from 102 to 106 CFU/g. Molecular analysis revealed Aspergillus westerdijkiae (67 %) as the most frequent species, followed by Aspergillus ostianus (22 %), and Aspergillus steynii (11 %). All of these isolates of A. section Circumdati were able to produce OTA in Yeast Extract Sucrose Agar (YESA) at 25 °C/7 days. OTA was found in 22 % of the artisanal cheese samples, ranging from 1.0 to above 1000 µg/kg, but only five samples had OTA higher than 1000 µg/kg. These findings emphasize the significance of ongoing monitoring and quality control in the artisanal cheese production process to minimize potential health risks linked to OTA contamination.

New drug discovery strategies for the treatment of benznidazole-resistance in Trypanosoma cruzi, the causative agent of Chagas disease.

INTRODUCTION: Benznidazole, the drug of choice for treating Chagas Disease (CD), has significant limitations, such as poor cure efficacy, mainly in the chronic phase of CD, association with side effects, and parasite resistance. Understanding parasite resistance to benznidazole is crucial for developing new drugs to treat CD. AREAS COVERED: Here, the authors review the current understanding of the molecular basis of benznidazole resistance. Furthermore, they discuss the state-of-the-art methods and critical outcomes employed to evaluate the efficacy of potential drugs against T. cruzi, aiming to select better compounds likely to succeed in the clinic. Finally, the authors describe the different strategies employed to overcome resistance to benznidazole and find effective new treatments for CD. EXPERT OPINION: Resistance to benznidazole is a complex phenomenon that occurs naturally among T. cruzi strains. The combination of compounds that inhibit different metabolic pathways of the parasite is an important strategy for developing a new chemotherapeutic protocol.

Tight Versus Liberal Blood Glucose Control in Patients With Diabetes in the ICU: A Meta-Analysis of Randomized Controlled Trials.

Introduction: Glycemia is an important factor among critically ill patients in the intensive care unit (ICU). There is conflicting evidence on the preferred strategy of blood glucose control among patients with diabetes in the ICU. We aimed to conduct a meta-analysis comparing tight with liberal blood glucose in critically ill patients with diabetes in the ICU. Methods: We systematically searched PubMed, Embase, and Cochrane Central for randomized controlled trials (RCTs) comparing tight versus liberal blood glucose control in critically ill patients with diabetes from inception to December 2023. We pooled odds-ratios (OR) and 95% confidence intervals (CI) with a random-effects model for binary endpoints. We used the Review Manager 5.17 and R version 4.3.2 for statistical analyses. Risk of bias assessment was performed with the Cochrane tool for randomized trials (RoB2). Results: Eight RCTs with 4474 patients were included. There was no statistically significant difference in all-cause mortality (OR 1.11; 95% CI 0.95-1.28; P = .18; I² = 0%) between a tight and liberal blood glucose control. RoB2 identified all studies at low risk of bias and funnel plot suggested no evidence of publication bias. Conclusion: In patients with diabetes in the ICU, there was no statistically significant difference in all-cause mortality between a tight and liberal blood glucose control. PROSPERO registration: CRD42023485032.

Impact of PVC microplastics in photodynamic inactivation of Staphylococcus aureus and MRSA.

Photodynamic processes have found widespread application in therapies. These processes involve photosensitizers (PSs) that, when excited by specific light wavelengths and in the presence of molecular oxygen, generate reactive oxygen species (ROS), that target cells leading to inactivation. Photodynamic action has gained notable attention in environmental applications, particularly against pathogens and antibiotic-resistant bacteria (ARB) that pose a significant challenge to public health. However, environmental matrices frequently encompass additional contaminants and interferents, including microplastics (MPs), which are pollutants of current concern. Their presence in water and effluents has been extensively documented, highlighting their impact on conventional treatment methods, but this information remains scarce in the context of photodynamic inactivation (PDI) setups. Here, we described the effects of polyvinyl chloride (PVC) microparticles in PDI targeting Staphylococcus aureus and its methicillin-resistant strain (MRSA), using curcumin as a PS under blue light. The presence of PVC microparticles does not hinder ROS formation; however, depending on its concentration, it can impact bacterial inactivation. Our results underscore that PDI remains a potent method for reducing bacterial concentrations in water and wastewater containing ARB, even in highly contaminated scenarios with MPs.

Recurrent community-acquired pneumococcal meningitis in adults with and without identified predisposing factors.

Bacterial meningitis is still a significant public health concern, with high morbidity and mortality rates. Despite this, it is still a rare event that requires the bacterial invasion of the meninges. However, some predisposing factors can trigger recurrent episodes of meningitis. This study is aimed at determining the clinical characteristics and the molecular epidemiology of episodes of recurrent community-acquired meningitis with and without predisposing factors. For this purpose, we performed a retrospective study of our laboratory database during the period of 2010 to 2020. Additionally, using molecular tools developed in our previous works, the epidemiology of the pathogens causing these episodes was analyzed using cerebrospinal fluid samples, especially in the absence of isolated strains. We observed a total of 1,779 meningitis cases and 230 were caused by Streptococcus pneumoniae. Of those, 16 were recurrent meningitis episodes (16/1,779; 0.9%) from seven patients. Pneumococcus was the main agent responsible in these recurrent episodes and only two episodes were caused by Haemophilus influenzae. The mean age of these patients was 20 years old and three had predisposing factors which could have led to contracting meningitis. The samples presented different pneumococcal serotypes. Most of them were non-vaccine-covered serotypes and antibiotic susceptible strains. Therefore, it was demonstrated how the practical employment of molecular tools, developed for research, when applied in the routine of diagnosis, can provide important information for epidemiological surveillance. Furthermore, it was shown how pneumococcus was the leading cause of recurrent community-acquired meningitis without predisposing factors, suggesting that pneumococcal vaccination may be necessary, even in those groups of individuals considered to be less susceptible.

BMP6 and VDR gene polymorphisms are associated with osteonecrosis in a sickle cell anaemia cohort.

The occurrence and severity of osteonecrosis in sickle cell anaemia (SCA) vary due to risk factors, including genetic modifiers. Bone morphogenetic proteins (BMPs), particularly BMP6, and the vitamin D receptor (VDR) play key roles in cartilage and bone metabolism, making them potential contributors to orthopaedic outcomes in SCA. Here, we evaluated the association of polymorphisms in BMP6 (rs3812163, rs270393 and rs449853) and VDR (FokI rs2228570 and Cdx2 rs11568820) genes with osteonecrosis risk in a Brazilian SCA cohort. A total of 177 unrelated SCA patients were selected. The AA genotype of BMP6 rs3812163 was independently associated with a lower osteonecrosis risk (p = 0.015; odds ratio (OR): 0.38; 95% confidence interval (CI): 0.18-0.83) and with the long-term cumulative incidence of osteonecrosis (p = 0.029; hazard ratio: 0.56, 95% CI: 0.34-0.94). The VDR rs2228570 TT genotype was independently associated with a lower osteonecrosis risk (p = 0.039; OR: 0.14; 95% CI: 0.02-0.90). In summary, our results provide evidence that BMP6 rs3812163 and the VDR rs2228570 might be implicated in osteonecrosis pathophysiology in SCA and might help identify individuals at high risk.

Sociodemographic Profile: A Forgotten Factor in Temporomandibular Disorders? A Scoping Review.

The literature on Temporomandibular Disorders (TMD) incidence commonly reports sociodemographic factors such as gender and age. However, the role and prevalence of other sociodemographic factors in TMD are not well defined. Therefore, this scoping review aimed to report the prevalence of sociodemographic factors in TMD patients. A systematic search was conducted in the PubMed and Web of Science databases to identify clinical trials in adult populations, using the Research Diagnostic Criteria for TMD (RDC/TMD) or the Diagnostic Criteria for TMD (DC/TMD) and reporting sociodemographic data in TMD patients. Twenty-seven studies meeting the criteria were included in this review. The most commonly reported sociodemographic factors assessed in the included studies were age, race, education, job, income, and marital status. TMD prevalence was observed to be higher among younger and divorced individuals among the included studies. However, conflicting results were found for education level, and employment was not considered a risk factor for TMD. Although this review has methodological limitations, it suggests an association between TMD incidence and certain sociodemographic factors; nevertheless, further studies are needed to establish this relationship more conclusively.

Benefits of the combination of digital and analogic tools as a strategy to control possible awake bruxism: A randomised clinical trial.

BACKGROUND: Awake Bruxism (AB) management includes cognitive and behavioural changes. Digital and analogic tools can be used to remind the individual to control/avoid AB behaviours. However, no study addressed both tools together. OBJECTIVE: To compare the efficacy of the combination of digital (smartphone application) and analogic (adhesive reminders) tools versus digital tool alone for AB management. METHODS: Seventy-two individuals diagnosed with probable AB were divided into 3 groups: Group 1 (n = 24), used both digital and analogic tools during 30 days; Group 2 (n = 24), used only a digital tool during 30 days and Group 3 (n = 24), used only a digital tool for the first 15 days and then added the analogic tool for 15 days. The AB frequency was measured in real-time with a smartphone app, which sent alerts asking the individuals if they were doing any AB behaviours (bracing, teeth contact, clenching or grinding). Groups were compared using one-way ANOVA and before-after adding an analogic tool (group 3) by paired t-test, considering α = 0.05. RESULTS: All groups showed a decrease in AB behaviours at the end of the evaluation period. Group 1 (digital and analogic tools) showed the lowest average of AB behaviours among all groups; however, statistically significant differences were found only for the comparison between groups 1 and 2. In group 3, a significantly greater reduction in AB behaviours was found after combining both approaches. CONCLUSION: The combination of digital and analogic tools showed the greatest reduction of AB frequency and can be recommended for AB control.

Structure-Activity Relationship of a Pyrrole Based Series of PfPKG Inhibitors as Anti-Malarials.

Controlling malaria requires new drugs against Plasmodium falciparum. The P. falciparum cGMP-dependent protein kinase (PfPKG) is a validated target whose inhibitors could block multiple steps of the parasite's life cycle. We defined the structure-activity relationship (SAR) of a pyrrole series for PfPKG inhibition. Key pharmacophores were modified to enable full exploration of chemical diversity and to gain knowledge about an ideal core scaffold. In vitro potency against recombinant PfPKG and human PKG were used to determine compound selectivity for the parasite enzyme. P. berghei sporozoites and P. falciparum asexual blood stages were used to assay multistage antiparasitic activity. Cellular specificity of compounds was evaluated using transgenic parasites expressing PfPKG carrying a substituted "gatekeeper" residue. The structure of PfPKG bound to an inhibitor was solved, and modeling using this structure together with computational tools was utilized to understand SAR and establish a rational strategy for subsequent lead optimization.

Influence of temperature combined with photodynamic inactivation on the development of Aedes aegypti.

To reduce the speed of selection of populations resistant to chemical insecticides, photodynamic inactivation (PDI) against Aedes aegypti is a hot-topic and promising alternative technique to vector control. Temperature is an important factor in the survival of Ae. aegypti larvae and mosquitoes as it influences physiology, behavior, and ecology. This work aimed to evaluate parameters of the biological cycle of Ae. aegypti such as: hatching rate, larval development, adult mosquito longevity, sex ratio, weight, and lethal concentration of larval mortality (LC) through the combination of PDI with different temperatures. The number of larvae found after 48 h suggests that temperature affects hatching rate. Additionally, results showed a delay in development of surviving larvae after PDI when compared to control groups, and there was a reduction in the longevity of mosquitoes that undertook photodynamic action. PDI also led to a predominance of male insects, and observed weight indicates that the inactivation method may have also interfered in mosquito size. The results point to a satisfactory performance of PDI at all tested temperatures. Experimental conditions that were not lethal to all larvae implied that PDI impacts the mosquitoes' biological cycle. Though metabolism and development are improved at higher temperatures, so is PDI action, thus maintaining the net benefit. Therefore, it is assumed that the proposed photolarvicide can be useful in reducing arbovirus transmission, and results invite for future research in different abiotic conditions.

Structure-activity relationships of novel N-imidazoylpiperazines with potent anti-Trypanosoma cruzi activity.

Background: Chagas disease is caused by the parasite Trypanosoma cruzi, and the lack of effective and safe treatments makes identifying new classes of compounds with anti-T. cruzi activity of paramount importance. Methods: Hit-to-lead exploration of a metabolically stable N-imidazoylpiperazine was performed. Results: Compound 2, a piperazine derivative active against T. cruzi, was selected to perform the hit-to-lead exploration, which involved the design, synthesis and biological evaluation of 39 new derivatives. Conclusion: Compounds 6e and 10a were identified as optimized compounds with low micromolar in vitro activity, low cytotoxicity and suitable preliminary absorption, distribution, metabolism and excretion and physicochemical properties. Both compounds reduced parasitemia in mouse models of Chagas disease, providing a promising opportunity for further exploration of new antichagasic compounds.

Discovery of Potent Antimalarial Type II Kinase Inhibitors with Selectivity over Human Kinases.

While progress has been made in the effort to eradicate malaria, the disease remains a significant threat to global health. Acquired resistance to frontline treatments is emerging in Africa, urging a need for the development of novel antimalarial agents. Repurposing human kinase inhibitors provides a potential expedited route given the availability of a diverse array of kinase-targeting drugs that are approved or in clinical trials. Phenotypic screening of a library of type II human kinase inhibitors identified compound 1 as a lead antimalarial, which was initially developed to target human ephrin type A receptor 2 (EphA2). Here, we report a structure-activity relationship study and lead optimization of compound 1, which led to compound 33, with improved antimalarial activity and selectivity.

Reaction hijacking inhibition of Plasmodium falciparum asparagine tRNA synthetase.

Malaria poses an enormous threat to human health. With ever increasing resistance to currently deployed drugs, breakthrough compounds with novel mechanisms of action are urgently needed. Here, we explore pyrimidine-based sulfonamides as a new low molecular weight inhibitor class with drug-like physical parameters and a synthetically accessible scaffold. We show that the exemplar, OSM-S-106, has potent activity against parasite cultures, low mammalian cell toxicity and low propensity for resistance development. In vitro evolution of resistance using a slow ramp-up approach pointed to the Plasmodium falciparum cytoplasmic asparaginyl-tRNA synthetase (PfAsnRS) as the target, consistent with our finding that OSM-S-106 inhibits protein translation and activates the amino acid starvation response. Targeted mass spectrometry confirms that OSM-S-106 is a pro-inhibitor and that inhibition of PfAsnRS occurs via enzyme-mediated production of an Asn-OSM-S-106 adduct. Human AsnRS is much less susceptible to this reaction hijacking mechanism. X-ray crystallographic studies of human AsnRS in complex with inhibitor adducts and docking of pro-inhibitors into a model of Asn-tRNA-bound PfAsnRS provide insights into the structure-activity relationship and the selectivity mechanism.