A Novel Oral GyrB/ParE Dual Binding Inhibitor Effective against Multidrug-Resistant Neisseria gonorrhoeae and Other High-Threat Pathogens.

Drug-resistant Neisseria gonorrhoeae is a serious global health concern. New drugs are needed that can overcome existing drug resistance and limit the development of new resistances. Here, we describe the small molecule tricyclic pyrimidoindole JSF-2414 [8-(6-fluoro-8-(methylamino)-2-((2-methylpyrimidin-5-yl)oxy)-9H-pyrimido[4,5-b]indol-4-yl)-2-oxa-8-azaspiro[4.5]decan-3-yl)methanol], which was developed to target both ATP-binding regions of DNA gyrase (GyrB) and topoisomerase (ParE). JSF-2414 displays potent activity against N. gonorrhoeae, including drug-resistant strains. A phosphate pro-drug, JSF-2659, was developed to facilitate oral dosing. In two different animal models of Neisseria gonorrhoeae vaginal infection, JSF-2659 was highly efficacious in reducing microbial burdens to the limit of detection. The parent molecule also showed potent in vitro activity against high-threat Gram-positive organisms, and JSF-2659 was shown in a deep tissue model of vancomycin-resistant Staphylococcus aureus (VRSA) and a model of Clostridioides difficile-induced colitis to be highly efficacious and protective. JSF-2659 is a novel preclinical drug candidate against high-threat multidrug resistant organisms with low potential to develop new resistance.

Dynamic compression locking system versus multiple cannulated compression screw for the treatment of femoral neck fractures: a comparative study.

BACKGROUND: Femoral neck fractures are one of the problems in clinical treatment. The prognosis is uncertain. Currently, No internal fixation method is superior to other internal fixation methods in the treatment of femoral neck fractures. Therefore, the internal fixation system needs to be further explored. The aim of this study was to compare clinical outcomes of femoral neck dynamic compression locking system (DCLS) and multiple cannulated compression screws(MCCS) in the treatment of femoral neck fractures. METHODS: A prospective analysis of 54 cases of femoral neck fractures treated with either a DCLS (n = 28) or MCCS (n = 26) was conducted between December 2015 and November 2017 in authors' hospitals. The perioperative and postoperative parameters of the two groups were recorded and evaluated. RESULTS: Fifty-four patients were followed up for 24-47 months. The etiology was caused by a fall. There was no significant difference in follow-up time, operation time, incision length, surgical blood loss, the incidence of perioperative and postoperative healing complications, and mobility in the two groups (all P > 0.05). The Harris score, fracture healing time, femoral neck shortening, partial weight-bearing time and complete weight-bearing time were significantly better in the DCLS group than in the MCCS group (all P < 0.05). The fracture healing rate in the DCLS group was higher than that in the MCCS group. CONCLUSIONS: The DCLS and MCCS might be equally effective in terms of operation time, incision length, surgical blood loss, the incidence of perioperative and postoperative healing complications, and mobility in the treatment of femoral neck fractures. However, the DCLS is superior to the MCCS in Harris score, fracture healing time, femoral neck shortening, weight-bearing time and fracture healing rate. So, DCLS deserves further study.

Non-classical transpeptidases yield insight into new antibacterials.

Bacterial survival requires an intact peptidoglycan layer, a three-dimensional exoskeleton that encapsulates the cytoplasmic membrane. Historically, the final steps of peptidoglycan synthesis are known to be carried out by D,D-transpeptidases, enzymes that are inhibited by the ß-lactams, which constitute >50% of all antibacterials in clinical use. Here, we show that the carbapenem subclass of ß-lactams are distinctly effective not only because they inhibit D,D-transpeptidases and are poor substrates for ß-lactamases, but primarily because they also inhibit non-classical transpeptidases, namely the L,D-transpeptidases, which generate the majority of linkages in the peptidoglycan of mycobacteria. We have characterized the molecular mechanisms responsible for inhibition of L,D-transpeptidases of Mycobacterium tuberculosis and a range of bacteria including ESKAPE pathogens, and used this information to design, synthesize and test simplified carbapenems with potent antibacterial activity.

Mycobacterium abscessus l,d-Transpeptidases Are Susceptible to Inactivation by Carbapenems and Cephalosporins but Not Penicillins.

As a growing number of clinical isolates of Mycobacterium abscessus are resistant to most antibiotics, new treatment options that are effective against these drug-resistant strains are desperately needed. The majority of the linkages in the cell wall peptidoglycan of M. abscessus are synthesized by nonclassical transpeptidases, namely, the l,d-transpeptidases. Emerging evidence suggests that these enzymes represent a new molecular vulnerability in this pathogen. Recent studies have demonstrated that inhibition of these enzymes by the carbapenem class of ß-lactams determines their activity against Mycobacterium tuberculosis Here, we studied the interactions of ß-lactams with two l,d-transpeptidases in M. abscessus, namely, LdtMab1 and LdtMab2, and found that both the carbapenem and cephalosporin, but not penicillin, subclasses of ß-lactams inhibit these enzymes. Contrary to the commonly held belief that combination therapy with ß-lactams is redundant, doripenem and cefdinir exhibit synergy against both pansusceptible M. abscessus and clinical isolates that are resistant to most antibiotics, which suggests that dual-ß-lactam therapy has potential for the treatment of M. abscessus Finally, we solved the first crystal structure of an M. abscessus l,d-transpeptidase, LdtMab2, and using substitutions of critical amino acids in the catalytic site and computational simulations, we describe the key molecular interactions between this enzyme and ß-lactams, which provide an insight into the molecular basis for the relative efficacy of different ß-lactams against M. abscessus.

A virtual screen discovers novel, fragment-sized inhibitors of Mycobacterium tuberculosis InhA.

Isoniazid (INH) is usually administered to treat latent Mycobacterium tuberculosis (Mtb) infections and is used in combination therapy to treat active tuberculosis (TB). Unfortunately, resistance to this drug is hampering its clinical effectiveness. INH is a prodrug that must be activated by Mtb catalase-peroxidase (KatG) before it can inhibit InhA (Mtb enoyl-acyl-carrier-protein reductase). Isoniazid-resistant cases of TB found in clinical settings usually involve mutations in or deletion of katG, which abrogate INH activation. Compounds that inhibit InhA without requiring prior activation by KatG would not be affected by this resistance mechanism and hence would display continued potency against these drug-resistant isolates of Mtb. Virtual screening experiments versus InhA in the GO Fight Against Malaria (GO FAM) project were designed to discover new scaffolds that display base-stacking interactions with the NAD cofactor. GO FAM experiments included targets from other pathogens, including Mtb, when they had structural similarity to a malaria target. Eight of the 16 soluble compounds identified by docking against InhA plus visual inspection were modest inhibitors and did not require prior activation by KatG. The best two inhibitors discovered are both fragment-sized compounds and displayed Ki values of 54 and 59 µM, respectively. Importantly, the novel inhibitors discovered have low structural similarity to known InhA inhibitors and thus help expand the number of chemotypes on which future medicinal chemistry efforts can be focused. These new fragment hits could eventually help advance the fight against INH-resistant Mtb strains, which pose a significant global health threat.

Evolution of a thienopyrimidine antitubercular relying on medicinal chemistry and metabolomics insights.

The metabolic instability of an antitubercular small molecule CD117 was addressed through iterative alteration of a key sulfide substituent and interrogation of the effect on growth inhibition of cultured Mycobacterium tuberculosis. This process was informed by studies of the intramycobacterial metabolism of CD117 and its inactive carboxylic acid derivative. Isoxazole 4e and thiazole 4m demonstrated significant gains in mouse liver microsomal stability with slight losses in whole-cell activity. This work illustrates the challenges of antitubercular hit evolution, requiring a balance of chemical and biological insights.

A Preclinical Candidate Targeting Mycobacterium tuberculosis KasA.

Published Mycobacterium tuberculosis ß-ketoacyl-ACP synthase KasA inhibitors lack sufficient potency and/or pharmacokinetic properties. A structure-based approach was used to optimize existing KasA inhibitor DG167. This afforded indazole JSF-3285 with a 30-fold increase in mouse plasma exposure. Biochemical, genetic, and X-ray studies confirmed JSF-3285 targets KasA. JSF-3285 offers substantial activity in an acute mouse model of infection and in the corresponding chronic infection model, with efficacious reductions in colony-forming units at doses as low as 5 mg/kg once daily orally and improvement of the efficacy of front-line drugs isoniazid or rifampicin. JSF-3285 is a promising preclinical candidate for tuberculosis.

Antitubercular Triazines: Optimization and Intrabacterial Metabolism.

The triazine antitubercular JSF-2019 was of interest due to its in vitro efficacy and the nitro group shared with the clinically relevant delamanid and pretomanid. JSF-2019 undergoes activation requiring F420H2 and one or more nitroreductases in addition to Ddn. An intrabacterial drug metabolism (IBDM) platform was leveraged to demonstrate the system kinetics, evidencing formation of NO⋅ and a des-nitro metabolite. Structure-activity relationship studies focused on improving the solubility and mouse pharmacokinetic profile of JSF-2019 and culminated in JSF-2513, relying on the key introduction of a morpholine. Mechanistic studies with JSF-2019, JSF-2513, and other triazines stressed the significance of achieving potent in vitro efficacy via release of intrabacterial NO⋅ along with inhibition of InhA and, more generally, the FAS-II pathway. This study highlights the importance of probing IBDM and its potential to clarify mechanism of action, which in this case is a combination of NO⋅ release and InhA inhibition.

Intrabacterial Metabolism Obscures the Successful Prediction of an InhA Inhibitor of Mycobacterium tuberculosis.

Tuberculosis, caused by Mycobacterium tuberculosis (M. tuberculosis), kills 1.6 million people annually. To bridge the gap between structure- and cell-based drug discovery strategies, we are pioneering a computer-aided discovery paradigm that merges structure-based virtual screening with ligand-based, machine learning methods trained with cell-based data. This approach successfully identified N-(3-methoxyphenyl)-7-nitrobenzo[c][1,2,5]oxadiazol-4-amine (JSF-2164) as an inhibitor of purified InhA with whole-cell efficacy versus in vitro cultured M. tuberculosis. When the intrabacterial drug metabolism (IBDM) platform was leveraged, mechanistic studies demonstrated that JSF-2164 underwent a rapid F420H2-dependent biotransformation within M. tuberculosis to afford intrabacterial nitric oxide and two amines, identified as JSF-3616 and JSF-3617. Thus, metabolism of JSF-2164 obscured the InhA inhibition phenotype within cultured M. tuberculosis. This study demonstrates a new docking/Bayesian computational strategy to combine cell- and target-based drug screening and the need to probe intrabacterial metabolism when clarifying the antitubercular mechanism of action.

The clinical application of a novel method of internal fixation for femoral neck fractures-dynamic locking compression system.

BACKGROUND: Femoral neck fractures are the commonly encountered injury in orthopedic practice and result in significant morbidity and mortality. Currently, how to treat femoral neck fractures safely and effectively is still a challenge. The objective of this study is to evaluate the efficiency of dynamic compression locking system for femoral neck fractures. METHODS: This is a retrospective study conducted from May 2015 to October 2016. The study included 36 patients suffering from femoral neck fractures who underwent closed reduction and were fixed using dynamic compression locking system. All surgeries were performed by the same surgeon. The study was conducted by telephone and on-site follow-up. The Garden classification and anatomical site classification were categorized for all patients. We assessed radiographic outcomes of union, femoral neck shortening, screw back-out, and femoral head avascular necrosis. We also evaluated functional outcome using the Harris hip score. Other outcomes included the length of surgery, duration of hospital stay, injury to surgery time, intraoperative hemorrhage, time to clinical bone union, and other fracture complications. RESULTS: All patients were followed up 12 to 29 months with an average of 21.58 ± 5.41 months. All cases were caused by falls including 17 males and 19 females with an average age of 65.33 ± 9.30 years old ranging from 53 to 82 years old. Among them, injury to surgery time ranged between 1 and 4 days with an average of 2.58 ± 1.05 days. Duration of hospital stay was 8 to 21 days with an average of 15.33 ± 3.71 days. Intraoperative hemorrhage was 40 to 80 ml with an average of 61.67 ± 12.31 ml. Operation time was from 35 to 80 min with average of 50.25 ± 11.77 min. According to Garden classification, 9 cases (25%) were type II and 27 cases (75%) were type III. According to the anatomical site classification, 8 cases (22.2%) were subcapital femoral neck fractures, 19 cases (52.8%) trans-cervical, and 9 cases (25%) basi-cervical. At present, the follow-up has not found the fracture complications of femoral head avascular necrosis, fracture nonunion, and re-fracture. All patients achieved solid bone union. The mean time of clinical bone union was 3 to 4 months. Among all patients, there were only 3 cases of femoral neck shortening < 5 mm and 1 case of screw back-out = 4 mm. For Harris scoring, average Harris scale at the end of the follow-up was 93.42 ± 3.95 ranging from 85 to 98. There were 32 cases of excellent function scores on the Harris scale and 4 cases of good function scores on the Harris scale. Therefore, the excellent and good rate of Harris hip scores was 100%. CONCLUSIONS: Femoral neck dynamic compression locking system for femoral neck fractures in elderly patients can provide effective stability and reduce complications and revision rates.

Diagnosis related group grouping study of senile cataract patients based on E-CHAID algorithm.

AIM: To figure out the contributed factors of the hospitalization expenses of senile cataract patients (HECP) and build up an area-specified senile cataract diagnosis related group (DRG) of Shanghai thereby formulating the reference range of HECP and providing scientific basis for the fair use and supervision of the health care insurance fund. METHODS: The data was collected from the first page of the medical records of 22 097 hospitalized patients from tertiary hospitals in Shanghai from 2010 to 2012 whose major diagnosis were senile cataract. Firstly, we analyzed the influence factors of HECP using univariate and multivariate analysis. DRG grouping was conducted according to the exhaustive Chi-squared automatic interaction detector (E-CHAID) model, using HECP as target variable. Finally we evaluated the grouping results using non-parametric test such as Kruskal-Wallis H test, RIV, CV, etc. RESULTS: The 6 DRGs were established as well as criterion of HECP, using age, sex, type of surgery and whether complications/comorbidities occurred as the key variables of classification node of senile cataract cases. CONCLUSION: The grouping of senile cataract cases based on E-CHAID algorithm is reasonable. And the criterion of HECP based on DRG can provide a feasible way of management in the fair use and supervision of medical insurance fund.

Synergistic Lethality of a Binary Inhibitor of Mycobacterium tuberculosis KasA.

We report GSK3011724A (DG167) as a binary inhibitor of ß-ketoacyl-ACP synthase (KasA) in Mycobacterium tuberculosis Genetic and biochemical studies established KasA as the primary target. The X-ray crystal structure of the KasA-DG167 complex refined to 2.0-Å resolution revealed two interacting DG167 molecules occupying nonidentical sites in the substrate-binding channel of KasA. The binding affinities of KasA to DG167 and its analog, 5g, which binds only once in the substrate-binding channel, were determined, along with the KasA-5g X-ray crystal structure. DG167 strongly augmented the in vitro activity of isoniazid (INH), leading to synergistic lethality, and also synergized in an acute mouse model of M. tuberculosis infection. Synergistic lethality correlated with a unique transcriptional signature, including upregulation of oxidoreductases and downregulation of molecular chaperones. The lead structure-activity relationships (SAR), pharmacokinetic profile, and detailed interactions with the KasA protein that we describe may be applied to evolve a next-generation therapeutic strategy for tuberculosis (TB).IMPORTANCE Cell wall biosynthesis inhibitors have proven highly effective for treating tuberculosis (TB). We discovered and validated members of the indazole sulfonamide class of small molecules as inhibitors of Mycobacterium tuberculosis KasA-a key component for biosynthesis of the mycolic acid layer of the bacterium's cell wall and the same pathway as that inhibited by the first-line antitubercular drug isoniazid (INH). One lead compound, DG167, demonstrated synergistic lethality in combination with INH and a transcriptional pattern consistent with bactericidality and loss of persisters. Our results also detail a novel dual-binding mechanism for this compound as well as substantial structure-activity relationships (SAR) that may help in lead optimization activities. Together, these results suggest that KasA inhibition, specifically, that shown by the DG167 series, may be developed into a potent therapy that can synergize with existing antituberculars.

[An epidemiological survey on paragonimiasis in Jin Miaopu township in Shanxi province].

OBJECTIVE: To investigate the epidemiological factors and tendency of paragonimiasis in Jin Miaopu township in Zezhou county of Shanxi Province, and to understand the current status of public awareness for providing references to paragonimiasis education and prevention. METHODS: A questionnaire survey was conducted among 2172 villagers probing awareness of paragonimiasis and their experiences of eating crabs; Infection screening and antibody test were also performed by means of ELISA. RESULTS: The paragonimiasis knowledge coverage rate was zero, and 67.7% (1471/2172) of the respondents claimed their histories of crab eating and 96.7% (29/30) of crabs were infected with metacercaria of paragonimus. Of all the study subjects, 11% (241/2172) of them were infected with the positive rate of 4.1% (89/270). CONCLUSION: The incidence of paragonimiasis is closely related to dietetic habit in local residents. It is extremely necessary to increase the public awareness of paragonimiasis prevention and control and to improve the living conditions and dietetic habits.

Addressing the Metabolic Stability of Antituberculars through Machine Learning.

We present the first prospective application of our mouse liver microsomal (MLM) stability Bayesian model. CD117, an antitubercular thienopyrimidine tool compound that suffers from metabolic instability (MLM t1/2 < 1 min), was utilized to assess the predictive power of our new MLM stability model. The S-substituent was removed, a set of commercial reagents was utilized to construct a virtual library of 411 analogues, and our MLM stability model was applied to prioritize 13 analogues for synthesis and biological profiling. In MLM stability assays, all 13 analogues had superior metabolic stability to the parent compound, and six new analogues had acceptable MLM t1/2 values greater than or equal to 60 min. It is noteworthy that whole-cell efficacy and lack of relative mammalian cell cytotoxicity could not be predicted simultaneously. These results support the utility of our new MLM stability model in chemical tool and drug discovery optimization efforts.

A Novel Small-Molecule Inhibitor of the Mycobacterium tuberculosis Demethylmenaquinone Methyltransferase MenG Is Bactericidal to Both Growing and Nutritionally Deprived Persister Cells.

Active tuberculosis (TB) and latent Mycobacterium tuberculosis infection both require lengthy treatments to achieve durable cures. This problem has partly been attributable to the existence of nonreplicating M. tuberculosis "persisters" that are difficult to kill using conventional anti-TB treatments. Compounds that target the respiratory pathway have the potential to kill both replicating and persistent M. tuberculosis and shorten TB treatment, as this pathway is essential in both metabolic states. We developed a novel respiratory pathway-specific whole-cell screen to identify new respiration inhibitors. This screen identified the biphenyl amide GSK1733953A (DG70) as a likely respiration inhibitor. DG70 inhibited both clinical drug-susceptible and drug-resistant M. tuberculosis strains. Whole-genome sequencing of DG70-resistant colonies identified mutations in menG (rv0558), which is responsible for the final step in menaquinone biosynthesis and required for respiration. Overexpression of menG from wild-type and DG70-resistant isolates increased the DG70 MIC by 4× and 8× to 30×, respectively. Radiolabeling and high-resolution mass spectrometry studies confirmed that DG70 inhibited the final step in menaquinone biosynthesis. DG70 also inhibited oxygen utilization and ATP biosynthesis, which was reversed by external menaquinone supplementation. DG70 was bactericidal in actively replicating cultures and in a nutritionally deprived persistence model. DG70 was synergistic with the first-line TB drugs isoniazid, rifampin, and the respiratory inhibitor bedaquiline. The combination of DG70 and isoniazid completely sterilized cultures in the persistence model by day 10. These results suggest that MenG is a good therapeutic target and that compounds targeting MenG along with standard TB therapy have the potential to shorten TB treatment duration.IMPORTANCE This study shows that MenG, which is responsible for the last enzymatic step in menaquinone biosynthesis, may be a good drug target for improving TB treatments. We describe the first small-molecule inhibitor (DG70) of Mycobacterium tuberculosis MenG and show that DG70 has characteristics that are highly desirable for a new antitubercular agent, including bactericidality against both actively growing and nonreplicating mycobacteria and synergy with several first-line drugs that are currently used to treat TB.

A Novel Allyl Transfer Coupled with a Grob Fragmentation.

A novel acid-promoted rearrangement is disclosed. In the previously unknown transformation, an allyl group migrated to an in situ formed carbocation stabilized by an electron-rich aryl or heteroaryl group, resulting in a stereoselective intramolecular Grob fragmentation. The outcome of the rearrangement observed with an array of substrates can be satisfactorily rationalized using a working hypothesis with the aid of a six-membered transition state similar to those proposed for the anionic oxy-Cope or oxonia-Cope rearrangements, but involving only one instead of two double bonds.

A High Throughput Screening Assay for Anti-Mycobacterial Small Molecules Based on Adenylate Kinase Release as a Reporter of Cell Lysis.

Mycobacterium tuberculosis (Mtb) is well-established to be one of the most important bacterial pathogens for which new antimicrobial therapies are needed. Herein, we describe the development of a high throughput screening assay for the identification of molecules that are bactericidal against Mycobacteria. The assay utilizes the release of the intracellular enzyme adenylate kinase into the culture medium as a reporter of mycobacterial cell death. We demonstrate that the assay is selective for mycobactericidal molecules and detects anti-mycobacterial activity at concentrations below the minimum inhibitory concentration of many molecules. Thus, the AK assay is more sensitive than traditional growth assays. We have validated the AK assay in the HTS setting using the Mtb surrogate organism M. smegmatis and libraries of FDA approved drugs as well as a commercially available Diversity set. The screen of the FDA-approved library demonstrated that the AK assay is able to identify the vast majority of drugs with known mycobactericidal activity. Importantly, our screen of the Diversity set revealed that the increased sensitivity of the AK assay increases the ability of M. smegmatis-based screens to detect molecules with relatively poor activity against M. smegmatis but good to excellent activity against Mtb.

Combining Metabolite-Based Pharmacophores with Bayesian Machine Learning Models for Mycobacterium tuberculosis Drug Discovery.

Integrated computational approaches for Mycobacterium tuberculosis (Mtb) are useful to identify new molecules that could lead to future tuberculosis (TB) drugs. Our approach uses information derived from the TBCyc pathway and genome database, the Collaborative Drug Discovery TB database combined with 3D pharmacophores and dual event Bayesian models of whole-cell activity and lack of cytotoxicity. We have prioritized a large number of molecules that may act as mimics of substrates and metabolites in the TB metabolome. We computationally searched over 200,000 commercial molecules using 66 pharmacophores based on substrates and metabolites from Mtb and further filtering with Bayesian models. We ultimately tested 110 compounds in vitro that resulted in two compounds of interest, BAS 04912643 and BAS 00623753 (MIC of 2.5 and 5 µg/mL, respectively). These molecules were used as a starting point for hit-to-lead optimization. The most promising class proved to be the quinoxaline di-N-oxides, evidenced by transcriptional profiling to induce mRNA level perturbations most closely resembling known protonophores. One of these, SRI58 exhibited an MIC = 1.25 µg/mL versus Mtb and a CC50 in Vero cells of >40 µg/mL, while featuring fair Caco-2 A-B permeability (2.3 x 10-6 cm/s), kinetic solubility (125 µM at pH 7.4 in PBS) and mouse metabolic stability (63.6% remaining after 1 h incubation with mouse liver microsomes). Despite demonstration of how a combined bioinformatics/cheminformatics approach afforded a small molecule with promising in vitro profiles, we found that SRI58 did not exhibit quantifiable blood levels in mice.