Type IA topoisomerases as targets for infectious disease treatments

Infectious diseases are one of the main causes of death all over the world, with antimicrobial resistance presenting a great challenge. New antibiotics need to be developed to provide therapeutic treatment options, requiring novel drug targets to be identified and pursued. DNA topoisomerases control the topology of DNA via DNA cleavage–rejoining coupled to DNA strand passage. The change in DNA topological features must be controlled in vital processes including DNA replication, transcription, and DNA repair. Type IIA topoisomerases are well established targets for antibiotics. In this review, type IA topoisomerases in bacteria are discussed as potential targets for new antibiotics. In certain bacterial pathogens, topoisomerase I is the only type IA topoisomerase present, which makes it a valuable antibiotic target. This review will summarize recent attempts that have been made to identify inhibitors of bacterial topoisomerase I as potential leads for antibiotics and use of these inhibitors as molecular probes in cellular studies. Crystal structures of inhibitor–enzyme complexes and more in-depth knowledge of their mechanisms of actions will help to establish the structure–activity relationship of potential drug leads and develop potent and selective therapeutics that can aid in combating the drug resistant bacterial infections that threaten public health

Type IA Topoisomerases as Targets for Infectious Disease Treatments

Infectious diseases are one of the main causes of death all over the world, with antimicrobial resistance presenting a great challenge. New antibiotics need to be developed to provide therapeutic treatment options, requiring novel drug targets to be identified and pursued. DNA topoisomerases control the topology of DNA via DNA cleavage-rejoining coupled to DNA strand passage. The change in DNA topological features must be controlled in vital processes including DNA replication, transcription, and DNA repair. Type IIA topoisomerases are well established targets for antibiotics. In this review, type IA topoisomerases in bacteria are discussed as potential targets for new antibiotics. In certain bacterial pathogens, topoisomerase I is the only type IA topoisomerase present, which makes it a valuable antibiotic target. This review will summarize recent attempts that have been made to identify inhibitors of bacterial topoisomerase I as potential leads for antibiotics and use of these inhibitors as molecular probes in cellular studies. Crystal structures of inhibitor-enzyme complexes and more in-depth knowledge of their mechanisms of actions will help to establish the structure-activity relationship of potential drug leads and develop potent and selective therapeutics that can aid in combating the drug resistant bacterial infections that threaten public health

Deep segmentation of the liver and the hepatic tumors from abdomen tomography images

A pipelined framework is proposed for accurate, automated, simultaneous segmentation of the liver as well as the hepatic tumors from computed tomography (CT) images. The introduced framework composed of three pipelined levels. First, two different transfers deep convolutional neural networks (CNN) are applied to get high-level compact features of CT images. Second, a pixel-wise classifier is used to obtain two output-classified maps for each CNN model. Finally, a fusion neural network (FNN) is used to integrate the two maps. Experimentations performed on the MICCAI’2017 database of the liver tumor segmentation (LITS) challenge, result in a dice similarity coefficient (DSC) of 93.5% for the segmentation of the liver and of 74.40% for the segmentation of the lesion, using a 5-fold cross-validation scheme. Comparative results with the state-of-the-art techniques on the same data show the competing performance of the proposed framework for simultaneous liver and tumor segmentation

Covalent Complex of DNA and Bacterial Topoisomerase: Implications in Antibacterial Drug Development

A topoisomerase-DNA transient covalent complex can be a druggable target for novel topoisomerase poison inhibitors that represent a new class of antibacterial or anticancer drugs. Herein, we have investigated molecular features of the functionally important Escherichia coli topoisomerase I (EctopoI)-DNA covalent complex (EctopoIcc) for molecular simulations, which is very useful in the development of new antibacterial drugs. To demonstrate the usefulness of our approach, we used a model small molecule (SM), NSC76027, obtained from virtual screening. We examined the direct binding of NSC76027 to EctopoI as well as inhibition of EctopoI relaxation activity of this SM via experimental techniques. We then performed molecular dynamics (MD) simulations to investigate the dynamics and stability of EctopoIcc and EctopoI-NSC76027-DNA ternary complex. Our simulation results show that NSC76027 forms a stable ternary complex with EctopoIcc. EctopoI investigated here also serves as a model system for investigating a complex of topoisomerase and DNA in which DNA is covalently attached to the protein

An in vitro evaluation of the inhibitory effects of an aqueous extract of Acacia nilotica on Eimeria tenella.

Eimeria tenella is one of the most important species of Eimeria that infect domestic fowl, causing coccidiosis in the poultry industry associated with drastic economic loss. Alternative treatment options are often necessary since anticoccidial drugs are prohibitively expensive, have serious side effects, or develop resistance. The role that herbal therapy plays in basic healthcare has been rediscovered worldwide. Consequently, our research assessed the in vitro inhibitory effect of escalated concentrations (6.25 mg, 12.5 mg, 25 mg, 50 mg, and 100 mg/ml) of Acacia nilotica aqueous extract (ANAE) on Eimeria tenella sporulation. Statistical analysis revealed that ANAE decreased the percentage of oocyst sporulation in a dose-dependent manner. Furthermore, ANAE showed abnormal sporulation and morphological deterioration of E. tenella oocytes. Area Under the Curve (AUC) calculation was used to determine the efficacy of ANAE and revealed that ANAE concentrations significantly reduced the coccidial score index. At 100 mg/ml, ANAE completely suppressed the sporulation of E. tenella oocysts, with obvious changes to their morphology and size. The phytochemical analysis of ANAE has shown that ANAE contains several active principles that possess anthelmintic activities. These compounds include tannins, saponins, flavonoids, terpenoids, and alkaloids, which can be attributed to the anticoccidial activity of ANAE. Considering our findings, we recommend that ANAE be used to prevent and control Eimeria

Phytotherapeutic effects of Echinacea purpurea in gamma-irradiated mice

Echinacea (E.) purpurea herb is commonly known as the purple coneflower, red sunflower and rudbeckia. In this paper, we report the curative efficacy of an Echinacea extract in γ-irradiated mice. E. purpurea was given to male mice that were divided into five groups (control, treated, irradiated, treated before irradiation & treated after irradiation) at a dose of 30 mg/kg body weight for 2 weeks before and after irradiation with 3 Gy of γ-rays. The results reflected the detrimental reduction effects of γ-rays on peripheral blood hemoglobin and the levels of red blood cells, differential white blood cells, and bone marrow cells. The thiobarbituric acid-reactive substances (TBARs) level, Superoxide dismutase (SOD) and glutathione peroxidase (GSPx) activities and DNA fragmentation were also investigated. FT-Raman spectroscopy was used to explore the structural changes in liver tissues. Significant changes were observed in the microenvironment of the major constituents, including tyrosine and protein secondary structures. E. purpurea administration significantly ameliorated all estimated parameters. The radio-protection effectiveness was similar to the radio-recovery curativeness in comparison to the control group in most of the tested parameters. The radio-protection efficiency was greater than the radio-recovery in hemoglobin level during the first two weeks, in lymphoid cell count and TBARs level at the fourth week and in SOD activity during the first two weeks, as compared to the levels of these parameters in the control group

Interruption of bile acid uptake by hepatocytes after acetaminophen overdose ameliorates hepatotoxicity.

Background & aimsAcetaminophen (APAP) overdose remains a frequent cause of acute liver failure, which is generally accompanied by increased levels of serum bile acids (BAs). However, the pathophysiological role of BAs remains elusive. Herein, we investigated the role of BAs in APAP-induced hepatotoxicity.MethodsWe performed intravital imaging to investigate BA transport in mice, quantified endogenous BA concentrations in the serum of mice and patients with APAP overdose, analyzed liver tissue and bile by mass spectrometry and MALDI-mass spectrometry imaging, assessed the integrity of the blood-bile barrier and the role of oxidative stress by immunostaining of tight junction proteins and intravital imaging of fluorescent markers, identified the intracellular cytotoxic concentrations of BAs, and performed interventions to block BA uptake from blood into hepatocytes.ResultsPrior to the onset of cell death, APAP overdose causes massive oxidative stress in the pericentral lobular zone, which coincided with a breach of the blood-bile barrier. Consequently, BAs leak from the bile canaliculi into the sinusoidal blood, which is then followed by their uptake into hepatocytes via the basolateral membrane, their secretion into canaliculi and repeated cycling. This, what we termed 'futile cycling' of BAs, led to increased intracellular BA concentrations that were high enough to cause hepatocyte death. Importantly, however, the interruption of BA re-uptake by pharmacological NTCP blockage using Myrcludex B and Oatp knockout strongly reduced APAP-induced hepatotoxicity.ConclusionsAPAP overdose induces a breach of the blood-bile barrier which leads to futile BA cycling that causes hepatocyte death. Prevention of BA cycling may represent a therapeutic option after APAP intoxication.Lay summaryOnly one drug, N-acetylcysteine, is approved for the treatment of acetaminophen overdose and it is only effective when given within ∼8 hours after ingestion. We identified a mechanism by which acetaminophen overdose causes an increase in bile acid concentrations (to above toxic thresholds) in hepatocytes. Blocking this mechanism prevented acetaminophen-induced hepatotoxicity in mice and evidence from patients suggests that this therapy may be effective for longer periods after ingestion compared to N-acetylcysteine

Type I Topoisomerases As Potential Targets For Therapeutics

DNA topoisomerases are universal enzymes that control the topological features of DNA in all forms of life. This study aims to find potential inhibitors of some of the DNA topoisomerases in bacteria and humans that can be developed into potential therapeutics. The first aim of this study is to find potential inhibitors of bacterial topoisomerase I that can be developed into antibiotics. There is an urgent need to develop novel antibiotics to overcome the world-wide health crisis of antimicrobial resistance. Virtual screening and biochemical assays were combined to screen thousands of compounds for potential inhibitors of bacterial topoisomerase I. NSC76027 inhibits the topoisomerase I of Mycobacterium tuberculosis and Escherichia coli with IC50 values of 2-3 µM, and MIC values for growth inhibition of several mycobacteria including M. tuberculosis at 12.5 – 50 µM. The mechanism of action of this compound depends on the presence of the C-terminal region of the target enzyme. Structurally similar compounds were studied to understand the Structure-Activity-Relationship that governs the antibacterial activity of this compound. The second aim of this study is to find potential inhibitors of human topoisomerase IIIβ, which is hijacked by positive-sense ssRNA viruses including SARS-CoV-2 for viral replication. In this study, several drugs that had been previously approved for other uses were identified as potential drug repurposing candidates against this enzyme. The anticancer agents venetoclax, dactinomycin, and Bemcentinib showed inhibition of this enzyme. Moreover, some polyamines belonging to the Torrey Pines Institute combinatorial libraries were found to inhibit HTOP3β. These drugs and molecules are candidates for evaluation of antiviral activity in follow up studies. The third aim of this study is to find catalytic inhibitors of human topoisomerase I that can be useful in sepsis treatment. This enzyme facilitates the expression of the genes responsible for sepsis. A novel yeast-based screening system was developed and successfully used in this study to achieve this goal. NSC76028 was found to be a catalytic inhibitor of HTOP1 that can avoid the cytotoxic effect of poison inhibitors. Further investigations are required to determine the exact mechanism of action of NSC76028 and its impacts on human cells

Type IA Topoisomerases as Targets for Infectious Disease Treatments

Infectious diseases are one of the main causes of death all over the world, with antimicrobial resistance presenting a great challenge. New antibiotics need to be developed to provide therapeutic treatment options, requiring novel drug targets to be identified and pursued. DNA topoisomerases control the topology of DNA via DNA cleavage–rejoining coupled to DNA strand passage. The change in DNA topological features must be controlled in vital processes including DNA replication, transcription, and DNA repair. Type IIA topoisomerases are well established targets for antibiotics. In this review, type IA topoisomerases in bacteria are discussed as potential targets for new antibiotics. In certain bacterial pathogens, topoisomerase I is the only type IA topoisomerase present, which makes it a valuable antibiotic target. This review will summarize recent attempts that have been made to identify inhibitors of bacterial topoisomerase I as potential leads for antibiotics and use of these inhibitors as molecular probes in cellular studies. Crystal structures of inhibitor–enzyme complexes and more in-depth knowledge of their mechanisms of actions will help to establish the structure–activity relationship of potential drug leads and develop potent and selective therapeutics that can aid in combating the drug resistant bacterial infections that threaten public health

Investigating the Critical Success Factors of Excellence Model Implementation in the Public Sector “Egypt Government Excellence Award”

The purpose of this paper is to outline the structure of the Egypt Government Excellence Award, as well as to investigate the role of adopting an excellence framework in developing public sector work nature and improving public services, as well as to attempt to identify and propose solutions to the practical problems and challenges posed by excellence awards.The paper will highlight and investigate critical success factors (CSFs) that influence the success of the excellence model's implementation and adoption in the Egyptian public sector. A qualitative method will be used to build a model for CSF.The paper has summarized potential CSF that has been analyzed in previous literature that developed different models with different methodologies according to industry context. The majority of literature has discussed and analyzed CSF regarding TQM principles, with very little literature having discovered CSF of Excellence Models.The paper uses a qualitative narrative approach for an exploratory purpose. The data has been collected and analyzed using human interactive data sources by using unstructured interviews with experts in excellence from Egypt and other countries that have a similar context to EGEA.The results have shown that the main top five CSF, which are considered the main factors that will help any public organization in Egypt to successfully implement excellence models, are leadership, human assets, culture, excellence model, and performance management system