Free Radicals, Mitochondrial Dysfunction and Sepsis-induced Organ Dysfunction: A Mechanistic Insight

Sepsis is a complex clinical condition and a leading cause of death worldwide. During Sepsis, there is a derailment in the host response to infection, which can progress to severe sepsis and multiple organ dysfunction or failure, which leads to death. Free radicals, including reactive oxygen species (ROS) generated predominantly in mitochondria, are one of the key players in impairing normal organ function in sepsis. ROS contributing to oxidative stress has been reported to be the main culprit in the injury of the lung, heart, liver, kidney, gastrointestinal, and other organs. Here in the present review, we describe the generation, and essential properties of various types of ROS, their effect on macromolecules, and their role in mitochondrial dysfunction. Furthermore, the mechanism involved in the ROS-mediated pathogenesis of sepsis-induced organ dysfunction has also been discussed.

Entamoeba histolytica induced NETosis and the dual role of NETs in amoebiasis

Entamoeba histolytica (Eh), a microaerophilic parasite, causes deadly enteric infections that result in Amoebiasis. Every year, the count of invasive infections reaches 50 million approximately and 40,000 to 1,00,000 deaths occurring due to amoebiasis are reported globally. Profound inflammation is the hallmark of severe amoebiasis which is facilitated by immune first defenders, neutrophils. Due to size incompatibility, neutrophils are unable to phagocytose Eh and thus, came up with the miraculous antiparasitic mechanism of neutrophil extracellular traps (NETs). This review provides an in-depth analysis of NETosis induced by Eh including the antigens involved in the recognition of Eh and the biochemistry of NET formation. Additionally, it underscores its novelty by describing the dual role of NETs in amoebiasis where it acts as a double-edged sword in terms of both clearing and exacerbating amoebiasis. It also provides a comprehensive account of the virulence factors discovered to date that are implicated directly and indirectly in the pathophysiology of Eh infections through the lens of NETs and can be interesting drug targets.

Lunar lenses - Acquired lens colobomas

Acquired lens colobomas secondary to ocular surgeries are scarcely described in the literature. We describe two cases of acquired lens coloboma in two infants with glaucoma who underwent ocular surgery. The coloboma in the first case was likely because of direct trauma to the lens zonules during an optical iridectomy with a vitrectomy cutter, resulting in localized loss of zonules and consequently localized lens coloboma. The coloboma in the second case was noticed during examination under anesthesia after scleral buckling and cryopexy for retinal detachment. The cause for coloboma development in this case could be disruption of the lens zonules because of stretching of the globe after scleral buckle surgery or because of injury to zonules during scleral buckling and the cryopexy procedure.

Unravelling the Differential Host Immuno-Inflammatory Responses to Staphylococcus aureus and Escherichia coli Infections in Sepsis

Previous reports from our lab have documented dysregulated host inflammatory reactions in response to bacterial infections in sepsis. Both Gram-negative bacteria (GNB) and Gram-positive bacteria (GPB) play a significant role in the development and progression of sepsis by releasing several virulence factors. During sepsis, host cells produce a range of inflammatory responses including inducible nitric oxide synthase (iNOS) expression, nitrite generation, neutrophil extracellular traps (NETs) release, and pro-inflammatory cytokines production. The current study was conducted to discern the differences in host inflammatory reactions in response to both Escherichia coli and Staphylococcus aureus along with the organ dysfunction parameters in patients of sepsis. We examined 60 ICU sepsis patients identified based on the Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA II) scores. Pathogen identification was carried out using culture-based methods and gene-specific primers by real-time polymerase chain reaction (RT-PCR). Samples of blood from healthy volunteers were spiked with E. coli (GNB) and S. aureus (GPB). The incidence of NETs formation, iNOS expression, total nitrite content, and pro-inflammatory cytokine level was estimated. Prevalence of E. coli, A. baumannii (both GNB), S. aureus, and Enterococcus faecalis (both GPB) was found in sepsis patients. Augmented levels of inflammatory mediators including iNOS expression, total nitrite, the incidence of NETs, and proinflammatory cytokines, during spiking, were found in response to S. aureus infections in comparison with E. coli infections. These inflammatory mediators were found to be positively correlated with organ dysfunction in both GN and GP infections in sepsis patients. Augmented host inflammatory response was generated in S. aureus infections as compared with E. coli.

Understanding factors associated with continuation of use of injectable contraceptives in Karnataka and Maharashtra, India: a cross-sectional household study

The Government of India has worked to expand access to injectable contraceptives through the introduction of a three-monthly injectable contraceptive MPA under the ‘Antara’ program in 2017. However, the uptake of injectable contraceptives has remained low, and few studies have investigated the experiences of public health facility injectable clients in India. We examined factors associated with continuing, discontinuing, and switching methods among injectable users obtaining services from public health facilities in the Indian states of Karnataka and Maharashtra. The study team recruited respondents (N=1009) that had received their first injectable dose from in public sector facilities between February – May 2019 and conducted a follow-up visit at their residence in December 2020. We used multivariate logistic regression to study the association of the demographic characteristics, service quality, satisfaction with services, follow-up visits, and decision-making on injectable continuation and switching to other family planning methods. Injectable usage rates declined significantly, with 44% of clients receiving a second dose and only 16% receiving a third dose. Over half of women (54%) cited problems related to periods as the reason for discontinuing injectable use after the first dose. Respondents were more likely to continue their method at third dose if they were older (25-35 years) (OR:1.68, p<0.05) and had received a reminder for a follow-up dose (OR: 2.41, p Our results also highlight the importance of addressing side-effects experience by women, which may be better managed by community-based follow-up visits and high-quality counselling services.

Exploring the molecular interaction of Pheniramine with Enterococcus faecalis Homoserine Kinase: In-silico and in vitro studies

Infections caused by the bacteria Enterococcus faecalis (also known as E. faecalis) are common in hospitals. This bacterium is resistant to a wide range of medicines and causes a variety of nosocomial infections. An increase in the number of infections caused by multidrug-resistant (MDR) bacteria is causing substantial economic and health issues around the world. Consequently, new therapeutic techniques to tackle the growing threat of E. faecalis infections must be developed as soon as possible. In this regard, we have targeted a protein that is regarded to be critical for the survival of bacteria in this experiment. Homoserine kinase (HSK) is a threonine metabolism enzyme that belongs to the GHMP kinase superfamily. It is a crucial enzyme in threonine metabolism. This enzyme is responsible for a critical step in the threonine biosynthesis pathway. Given the important function that E. faecalis Homoserine Kinase (ESK) plays in bacterial metabolism, we proposed that E. faecalis HSK be cloned, overexpressed, purified, and subjected to structural analyses using homology modelling. In addition, we have reported on the model's molecular docking and Molecular Dynamic Stimulation (MD Stimulation) investigations to validate the results of the docking experiments. The results were promising. In silico investigations came up with the conclusion: pheniramine has good binding affinity for the E. faecalis HSK.

Deciphering the Role of S-adenosyl Homocysteine Nucleosidase in Quorum Sensing Mediated Biofilm Formation

Abstract:

S-adenosylhomocysteine nucleosidase (MTAN) is a protein that plays a crucial role in several pathways of bacteria that are essential for its survival and pathogenesis. In addition to the role of MTAN in methyl-transfer reactions, methionine biosynthesis, and polyamine synthesis, MTAN is also involved in bacterial quorum sensing (QS). In QS, chemical signaling autoinducer (AI) secreted by bacteria assists cell to cell communication and is regulated in a cell density-dependent manner. They play a significant role in the formation of bacterial biofilm. MTAN plays a major role in the synthesis of these autoinducers. Signaling molecules secreted by bacteria, i.e., AI-1 are recognized as acylated homoserine lactones (AHL) that function as signaling molecules within bacteria. QS enables bacteria to establish physical interactions leading to biofilm formation. The formation of biofilm is a primary reason for the development of multidrug-resistant properties in pathogenic bacteria like Enterococcus faecalis (E. faecalis). In this regard, inhibition of E. faecalis MTAN (EfMTAN) will block the QS and alter the bacterial biofilm formation. In addition to this, it will also block methionine biosynthesis and many other critical metabolic processes. It should also be noted that inhibition of EfMTAN will not have any effect on human beings as this enzyme is not present in humans. This review provides a comprehensive overview of the structural-functional relationship of MTAN. We have also highlighted the current status, enigmas that warrant further studies, and the prospects for identifying potential inhibitors of EfMTAN for the treatment of E. faecalis infections. In addition to this, we have also reported structural studies of EfMTAN using homology modeling and highlighted the putative binding sites of the protein.

Identification of Protein Drug Targets of Biofilm Formation and Quorum Sensing in Multidrug Resistant Enterococcus faecalis

Abstract:

Enterococcus faecalis (E. faecalis) is an opportunistic multidrug-resistant (MDR) pathogen found in the guts of humans and farmed animals. Due to the occurrence of (MDR) strain there is an urgent need to look for an alternative treatment approach. E. faecalis is a Gram-positive bacterium, which is among the most prevalent multidrug resistant hospital pathogens. Its ability to develop quorum sensing (QS) mediated biofilm formation further exacerbates the pathogenicity and triggers lifethreatening infections. Therefore, developing a suitable remedy for curing E. faecalis mediated enterococcal infections is an arduous task. Several putative virulence factors and proteins are involved in the development of biofilms in E. faecalis. Such proteins often play important roles in virulence, disease, and colonization by pathogens. The elucidation of the structure-function relationship of such protein drug targets and the interacting compounds could provide an attractive paradigm towards developing structure-based drugs against E. faecalis. This review provides a comprehensive overview of the current status, enigmas that warrant further studies, and the prospects toward alleviating the antibiotic resistance in E. faecalis. Specifically, the role of biofilm and quorum sensing (QS) in the emergence of MDR strains had been elaborated along with the importance of the protein drug targets involved in both the processes.

Post-trabeculectomy early bleb localization mimicking a 'ring of steel'

A 54-year-old-man underwent trabeculectomy with mitomycin-C (0.02%). At 4-week follow-up, there was an elevated, well-circumscribed bleb with raised intra-ocular pressure (IOP) of 32-mmHg, with a classic “ring of steel” appearance, typically seen in a tenon's cyst. A sub-tenon needle revision re-established aqueous flow. Two weeks later, the IOP was 8-mmHg without any anti-glaucoma medications. A diffuse well formed bleb was noted. Careful ocular examination helps to identify early post-operative localized bleb that may appear like a “ring of steel” but can be managed by needling, unlike a tenon's cyst, which would require more extensive intervention.

The flip side of reactive oxygen species in the tropical disease-Amoebiasis

Entamoeba histolytica is the conductive agent of amoebiasis. Upon the parasite's infection, macrophages and neutrophils are activated by interferon γ, IL-13 and tumour necrosis factor. These immune cells then carry out the amoebicidal activity by releasing nitric oxide synthase and reactive oxygen species (ROS). This review talks about the protective and destructive role of ROS in Eh. E. histolytica has defence strategies against oxidative stress which is a result of excess ROS production. They possess antioxidants for their defence such as L-Cysteine, flavodiiron proteins, peroxiredoxin and trichostatin A, which contribute to the parasite's virulence. The ROS are harmful to the host cells as excess ROS production stimulates cell death by mechanisms like apoptosis and necroptosis. NADPH oxidase (NOX) is a key source of ROS in mammalian cells and causes apoptosis of host cells via the protein kinase transduction pathway. This review provides insights into why NOX inhibitors that could be a potent antiparasitic drug, is not effective for in vivo purposes. This paper also gives an insight into a solution that could be a potent source in generating new treatment and vaccines for amoebiasis by targeting parasite development.

Understanding factors associated with continuation of intrauterine device use in Gujarat and Rajasthan, India: a cross-sectional household study

The Government of India has promoted the expansion of access to and uptake of intrauterine devices (IUDs), during both the interval (IIUD) and postpartum (PPIUD) periods, as part of its Family Planning 2020 initiative. This study, conducted by EngenderHealth as part of the Expanding Access to IUD Services in India project, examines IIUD and PPIUD continuation rates over time and investigates factors associated with IUD continuation. We recruited respondents (N = 5024) through a repeated cross-sectional household study between February and December 2019. We identified respondents using IUD client data from public health facility registers in 20 districts of Gujarat and Rajasthan. We compared continuation rates for IIUD and PPIUD adopters and used regression analyses to measure the association between continuation and demographic, quality of care, and counselling variables. IIUD continuation rates decreased from 85.6% to 78.3% and PPIUD rates decreased from 78.5% to 70.7% between month 3 and month 12. Clients experiencing side effects or other problems were 15 times more likely to discontinue IUD use than clients who did not. Clients who received IUD counselling prior to insertion were more likely to continue than those who did not. IUD continuation increased significantly in cases where both partners jointly selected the method compared to situations where women decided alone. Several sociodemographic factors were associated with continuation. Our study demonstrates the value and benefits of programmes offering IUD services emphasising quality counselling and client-centred care to increase access, uptake, and continuation.

Neonatal sepsis at point of care

Sepsis, which includes infection followed by inflammation, is one of the leading causes of death among neonates worldwide. The major attribute of this disease process is dysregulated host response to infection leading to organ dysfunction and potentially death. A comprehensive understanding of the host response as well as the pathogen itself are important factors contributing to outcome. Early diagnosis is paramount, as it leads to accurate assessment and improved clinical management. Accordingly, a number of diagnostic platforms have been introduced to assess the presence of blood stream pathogens in septic neonates. Unfortunately, current point-of-care (POC) methods rely on a single parameter/biomarker and thus lack a comprehensive evaluation. The emerging field of biosensing has, however, resulted in the development of a wide range of analytical devices that may be useful at POC. This review discusses currently available methods to screen the inflammatory process in neonatal sepsis. We describe POC sensor-based methods for single platform multi-analyte detection and highlight the latest advances in this evolving technology. Finally, we critically evaluate the applicability of these POC devices clinically for early diagnosis of sepsis in neonates.

Cysteine proteases: Battling pathogenic parasitic protozoans with omnipresent enzymes

Millions of people worldwide lie at the risk of parasitic protozoic infections that kill over a million people each year. The rising inefficacy of conventional therapeutics to combat these diseases, mainly due to the development of drug resistance to a handful of available licensed options contributes substantially to the rising burden of these ailments. Cysteine proteases are omnipresent enzymes that are critically implicated in the pathogenesis of protozoic infections. Despite their significance and druggability, cysteine proteases as therapeutic targets have not yet been translated into the clinic. The review presents the significance of cysteine proteases of members of the genera Plasmodium, Entamoeba, and Leishmania, known to cause Malaria, Amoebiasis, and Leishmaniasis, respectively, the protozoic diseases with the highest morbidity and mortality. Further, projecting them as targets for molecular tools like the CRISPR-Cas technology for favorable manipulation, exploration of obscure genomes, and achieving a better insight into protozoic functioning. Overcoming the hurdles that prevent us from gaining a better insight into the functioning of these enzymes in protozoic systems is a necessity. Managing the burden of parasitic protozoic infections pivotally depends upon the betterment of molecular tools and therapeutic concepts that will pave the path to an array of diagnostic and therapeutic applications.

In silico prediction, molecular docking and binding studies of acetaminophen and dexamethasone to Enterococcus faecalis diaminopimelate epimerase

Enterococcus faecalis (E. faecalis) is a Gram-positive coccoid, non-sporulating, facultative anaerobic, multidrug resistance bacterium responsible for almost 65% to 80% of all enterococcal nosocomial infections. It usually causes infective endocarditis, urinary tract and surgical wound infections. The increase in E. faecalis resistance to conventionally available antibiotic has rekindled intense interest in developing useful antibacterial drugs. In E. faecalis, diaminopimelate epimerase (DapF) is involved in the lysine biosynthetic pathway. The product of this pathway is precursors of peptidoglycan synthesis, which is a component of bacterial cell wall. Also, because mammals lack this enzyme, consequently E. faecalis diaminopimelate epimerase (EfDapF) represents a potential target for developing novel class of antibiotics. In this regard, we have successfully cloned, overexpressed the gene encoding DapF in BL-21(DE3) and purified with Ni-NTA Agarose resin. In addition to this, binding studies were performed using fluorescence spectroscopy in order to confirm the bindings of the identified lead compounds (acetaminophen and dexamethasone) with EfDapF. Docking studies revealed that acetaminophen found to make hydrogen bonds with Asn72 and Asn13 while dexamethasone interacted by forming hydrogen bonds with Asn205 and Glu223. Thus, biochemical studies indicated acetaminophen and dexamethasone, as potential inhibitors of EfDapF and eventually can reduce the catalytic activity of EfDapF.

Chaperone-mediated autophagy sustains haematopoietic stem-cell function

The activation of mostly quiescent haematopoietic stem cells (HSCs) is a prerequisite for life-long production of blood cells¹. This process requires major molecular adaptations to allow HSCs to meet the regulatory and metabolic requirements for cell division^2-4. The mechanisms that govern cellular reprograming upon stem-cell activation, and the subsequent return of stem cells to quiescence, have not been fully characterized. Here we show that chaperone-mediated autophagy (CMA)⁵, a selective form of lysosomal protein degradation, is involved in sustaining HSC function in adult mice. CMA is required for protein quality control in stem cells and for the upregulation of fatty acid metabolism upon HSC activation. We find that CMA activity in HSCs decreases with age and show that genetic or pharmacological activation of CMA can restore the functionality of old mouse and human HSCs. Together, our findings provide mechanistic insights into a role for CMA in sustaining quality control, appropriate energetics and overall long-term HSC function. Our work suggests that CMA may be a promising therapeutic target for enhancing HSC function in conditions such as ageing or stem-cell transplantation.

Functional role of iNOS-Rac2 interaction in neutrophil extracellular traps (NETs) induced cytotoxicity in sepsis

BACKGROUND

Recent reports from this lab have demonstrated a higher incidence of NETs, nitrosative, as well as oxidative stress, and have a direct correlation with the severity of sepsis and organ damage. However, the mechanistic perspective of NETs induced organ damage has not been understood at the cellular and molecular level. Interaction of inducible nitric oxide synthase (iNOS) with Rac2 in regulating reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation and its implications in microbial killing has been reported. This study was, therefore, undertaken in neutrophils of sepsis patients to investigate the functional importance of iNOS-Rac2 interaction in ROS/ RNS, peroxynitrite generation, NETs generation, and NETs mediated cell death.

METHODS

The study was conducted on 100 patients with sepsis and 50 healthy volunteers. Interaction between iNOS and Rac2 was performed using co-immunoprecipitation and co-immunolabeling assay. Free radicals involving ROS and RNS were evaluated using cytochrome c reduction assay. NETs formation was evaluated by fluorescence microscopy. The cytotoxic effect of NETs was assessed on lung carcinoma cell line (A549) using colorimetric Alamar blue assay.

RESULTS

Enhanced interaction between iNOS and Rac2 was found in sepsis neutrophils in comparison with control. This was accompanied by an increased level of superoxide (O2.-), nitric oxide (NO), and peroxynitrite (ONOO-) which were decreased in the presence of NAC, DPI, and 1400 W, signifying the role of iNOS-Rac2 interaction. Enhanced NETs release from activated sepsis neutrophils were abrogated in the presence of DPI. NETs from sepsis neutrophils exert a cytotoxic effect on lung epithelial cells (A549) in a concentration-dependent manner.

CONCLUSION

Our findings exhibit the functional role of iNOS-Rac2 interaction in ROS/RNS, peroxynitrite generation, NETs generation, and NETs mediated cell death.

Prospecting Potential Inhibitors of Sortase A from Enterococcus faecalis: A Multidrug Resistant Bacteria, through In-silico and In-vitro Approaches

Background:

Enterococcus faecalis (Ef) infections are becoming dreadfully common in hospital environments. Infections caused by Ef are difficult to treat because of its acquired resistance to different class of antibiotics, making it a multidrug resistant bacteria. Key pathogenic factor of Ef includes its ability to form biofilm on the surface of diagnostic and other medical devices. Sortase A (SrtA) is a cysteine transpeptidase which plays a pivotal role in the formation of biofilm in Ef, hence, it is considered as an important enzyme for the pathogenesis of Ef. Thus, inhibition of (SrtA) will affect biofilm formation, which will reduce its virulence and eventually Ef infection will be abridged.

Objective:

To find potential inhibitors of Enterococcus faecalis Sortase A (EfSrtA) through insilico and in-vitro methods.

Methods:

Gene coding for EfSrtA was cloned, expressed and purified. Three-dimensional model of EfSrtA was created using Swiss-Model workspace. In-silico docking studies using Autodock vina and molecular dynamics simulations of the modelled structures using Gromacs platform were performed to explore potential lead compounds against EfSrtA. In-vitro binding experiments using spectrofluorometric technique was carried out to confirm and validate the study.

Results:

In-silico docking and in-vitro binding experiments revealed that curcumin, berberine and myricetin bound to EfSrtA at nanomolar concentrations with high affinity.

Conclusion:

This is a first structural report of EfSrtA with curcumin, berberine and myricetin. Taking in account the herbal nature of these compounds, the use of these compounds as inhibitors will be advantageous. This study validated curcumin, berberine and myricetin as potential inhibitors of EfSrtA.

Averting transmission: A pivotal target to manage amoebiasis

Amoebiasis is a parasitic infectious disease caused by the enteric protozoan Entamoeba histolytica, a leading basis of deaths accounted to parasites, succeeding malaria and schistosomiasis. Conventional treatment methodologies used to deal with amoebiasis mainly rely on the administration of anti-amoebic compounds and vaccines but are often linked with substantial side-effects on the patient. Besides, cases of development of drug resistance in protozoans have been recorded, contributing further to the reduction in the efficiency of the treatment. Loopholes in the efficacious management of the disease call for the development of novel methodologies to manage amoebiasis. A way to achieve this is by targeting the essential metabolic processes of 'encystation' and 'excystation', and the associated biomolecules, thus interrupting the biphasic life cycle of the parasite. Technologies like the CRISPR-Cas9 system can efficiently be exploited to discover novel and essential molecules that regulate the protozoan's metabolism, while efficiently manipulating and managing the known drug targets, leading to an effective halt and forestall to the enteric infection. This review presents a perspective on these essential metabolic processes and the associated molecules that can be targeted efficaciously to prevent the transmission of amoebiasis, thus managing the disease and proving to be a fruitful endeavour.

Chiral terahertz wave emission from the Weyl semimetal TaAs

Weyl semimetals host chiral fermions with distinct chiralities and spin textures. Optical excitations involving those chiral fermions can induce exotic carrier responses, and in turn lead to novel optical phenomena. Here, we discover strong coherent terahertz emission from Weyl semimetal TaAs, which is demonstrated as a unique broadband source of the chiral terahertz wave. The polarization control of the THz emission is achieved by tuning photoexcitation of ultrafast photocurrents via the photogalvanic effect. In the near-infrared regime, the photon-energy dependent nonthermal current due to the predominant circular photogalvanic effect can be attributed to the radical change of the band velocities when the chiral Weyl fermions are excited during selective optical transitions between the tilted anisotropic Weyl cones and the massive bulk bands. Our findings provide a design concept for creating chiral photon sources using quantum materials and open up new opportunities for developing ultrafast opto-electronics using Weyl physics.

Study of Dosimetric Properties of Flattening Filter Free Photon Beam Passing through Cadmium Free Compensator Alloy

BACKGROUND

This study aims to investigate radiation beam geometry of Cyberknife beam and change in dosimetric characteristics of six megavoltage (6MV) flattening filter free (FFF) beam after passing through high density cadmium free compensator alloy.

MATERIAL AND METHODS

In this experimental study, changes in FFF beam dosimetric characteristics after passing through compensator alloy was measured. Transmitted intensity of FFF beam was measured in air by an ion chamber at a source to detector distance (SDD) of 800mm. Extended SDD measurement also has been performed at a distance of 1270mm to analyze scattering due to compensator. Linear attenuation coefficient (µ_eff) was measured for cadmium free compensator alloy using simple exponential attenuation model. Percentage depth doses (PDDs) have been measured by a radiation field analyzer with compensator material to observe the beam hardening and change in surface doses and depth doses.

RESULTS

Linear attenuation coefficient of compensator alloy was measured 0.042 (Standard Deviation ±0.00099) mm^-1 and it was found that there is no change with increase in collimator size. Even after increasing distance source from detector, µ_eff has no change. PDDs were found to increase with thickness of compensator. PDD from a 60mm collimator size increased by 5% and 6% at a depth of 100mm and 200mm, respectively in water. PDD also increased with collimator size less significantly. Surface dose was found to decrease with increase in compensator thickness.

CONCLUSION

Cyberknife beam has been found to be narrow beam geometry. FFF beam contains lesser scattered photons. Presence of high density compensator filters out the soft x-ray photon causes significant dosimetric changes.

A comparative in silico analysis of Rab5 proteins from pathogenic species to find its role in the pathogenesis

The enteric protozoan parasite, Entamoeba histolytica (Eh), is the causative agent of amoebic dysentery and liver abscess in humans. It infects around 50 million people worldwide, which is a third general cause of death from parasitic diseases after malaria and schistosomiasis. The other prevalent form of the disease is Visceral leishmaniasis caused by Leishmania donovani which is a human blood parasite. On the other hand, the Toxoplasma gondii is an obligate intracellular protozoan parasite; it causes serious opportunistic infections in HIV-positive persons. The biological processes in all living organisms are mostly mediated by the proteins, and recognizing new target proteins and finding their function in pathogenesis will help in choosing better diagnostic markers. In eukaryotes, Rab protein plays a major role in pathogenesis. Rabs represent the largest branch in the Ras superfamily of GTPases. Among them, the Rab5 is important in the endocytosis and thus involved in pathogenesis. In this paper, we discussed the physiochemical profiling, modelling, and docking of the Rab5 protein from pathogenic species that is Entamoeba histolytica, Leishmania donovani, and Toxoplasma gondii. The modeled structures from this study and the key residues identified would give a better understanding of the three-dimensional structure and functional insights into these proteins and help in developing new drug targets.

Identification and evaluation of quercetin as a potential inhibitor of naphthoate synthase from Enterococcus faecalis

Enterococcus faecalis is a gram-positive, rod-shape bacteria responsible for around 65% to 80% of all enterococcal nosocomial infections. It is multidrug resistant (MDR) bacterium resistant to most of the first-line antibiotics. Due to the emergence of MDR strains, there is an urgent need to find novel targets to develop new antibacterial drugs against E. faecalis. In this regard, we have identified naphthoate synthase (1,4-dihydroxy-2-naphthoyl-CoA synthase, EC: 4.1.3.36; DHNS) as an anti-E. faecalis target, as it is an essential enzyme for menaquinone (vitamin K₂ ) synthetic pathway in the bacterium. Thus, inhibiting naphtholate synthase may consequently inhibit the bacteria's growth. In this regard, we report here cloning, expression, purification, and preliminary structural studies of naphthoate synthase along with in silico modeling, molecular dynamic simulation of the model and docking studies of naphthoate synthase with quercetin, a plant alkaloid. Biochemical studies have indicated quercetin, a plant flavonoid as the potential lead compound to inhibit catalytic activity of EfDHNS. Quercetin binding has also been validated by spectrofluorimetric studies in order to confirm the bindings of the ligand compound with EfDHNS at ultralow concentrations. Reported studies may provide a base for structure-based drug development of antimicrobial compounds against E. faecalis.

In search of novel protein drug targets for treatment of Enterococcus faecalis infections

Enterococcus faecalis (Ef) is one of the major pathogens involved in hospital-acquired infections. It can cause nosocomial bacteremia, surgical wound infection, and urinary tract infection. It is important to mention here that Ef is developing resistance against many commonly occurring antibiotics. The occurrence of multidrug resistance (MDR) and extensive-drug resistance (XDR) is now posing a major challenge to the medical community. In this regard, to combat the infections caused by Ef, we have to look for an alternative. Rational structure-based drug design exploits the three-dimensional structure of the target protein, which can be unraveled by various techniques such as X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. In this review, we have discussed the complete picture of Ef infections, the possible treatment available at present, and the alternative treatment options to be explored. This study will help in better understanding of novel biological targets against Ef and the compounds, which are likely to bind with these targets. Using these detailed structural informations, rational structure-based drug design is achievable and tight inhibitors against Ef can be prepared.

Quantification of NETs formation in neutrophil and its correlation with the severity of sepsis and organ dysfunction

BACKGROUND

Previous study from this lab has discerned oxidative, nitrosative stress and their relationship with cytokines contributing to the severity of sepsis and organ dysfunction. Cytokines are known to induce neutrophil extracellular traps (NETs) formation via free radicals generation. Hyper-activation of neutrophil leads to the increased NETs formation or ineffective clearance of NETs would likely increase the risk of auto-antibody generation against NETs components and being partly responsible for the sepsis severity and organ dysfunction. The present study was undertaken to further assess the status of NETs formation and their correlation with severity of sepsis, with the cytokines and organ dysfunction.

METHODS

The level of NETs formation, DNA release, elastase release, and inflammatory cytokines was determined in 80 sepsis patients and 45 healthy volunteers. Their linearity with organ parameters and associations with sepsis severity were also assessed.

RESULTS

NETs formation experiment was carried out and it was significantly higher in sepsis (70%) compared to control (30%). NETs % were positively correlated with severity of sepsis and organ dysfunction. Pearson's correlation coefficient demonstrated a direct relation between NETs components and organ parameters with Sepsis severity scores.

CONCLUSION

NETs formation is significantly higher due to which it is contributing to the sepsis severity and organ failure.

The potential application of genome editing by using CRISPR/Cas9, and its engineered and ortholog variants for studying the transcription factors involved in the maintenance of phosphate homeostasis in model plants

Phosphorus (P), an essential macronutrient, is pivotal for growth and development of plants. Availability of phosphate (Pi), the only assimilable P, is often suboptimal in rhizospheres. Pi deficiency triggers an array of spatiotemporal adaptive responses including the differential regulation of several transcription factors (TFs). Studies on MYB TF PHR1 in Arabidopsis thaliana (Arabidopsis) and its orthologs OsPHRs in Oryza sativa (rice) have provided empirical evidence of their significant roles in the maintenance of Pi homeostasis. Since the functional characterization of PHR1 in 2001, several other TFs have now been identified in these model plants. This raised a pertinent question whether there are any likely interactions across these TFs. Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system has provided an attractive paradigm for editing genome in plants. Here, we review the applications and challenges of this technique for genome editing of the TFs for deciphering the function and plausible interactions across them. This technology could thus provide a much-needed fillip towards engineering TFs for generating Pi use efficient plants for sustainable agriculture. Furthermore, we contemplate whether this technology could be a viable alternative to the controversial genetically modified (GM) rice or it may also eventually embroil into a limbo.

Detection of Wolbachia Phage (WO) in Indian Lac Insect [Kerria lacca (Kerr.)] and Its Implications

Wolbachia, a maternally inherited bacterium induces reproductive alterations in its hosts such as feminization of males, male killing and parthenogenesis. It is the most diverse endosymbiont infecting more than 70% of the insects ranging from pests to pollinators. Kerria lacca-a hemipteran is a sedentary, oriental insect known to produce lac-the only resin of animal origin. The present study was conducted to screen the presence of Wolbachia and its associated phages in the two infrasubspecific forms (four insect lines) of K. lacca viz. kusmi and rengeeni differing from each other on the basis of host preference. Wolbachia and its associated phage were found to be prevalent in all the insect lines analyzed. We, hereby, report the presence of WO-phage (Wolbachia phage) for the first time in K. lacca. Further, phylogenetic data differentiated the kusmi and rengeeni infrasubspecific forms into two different groups on the basis of WO-phage sequences.

Bio-fabrication of silver nanoparticles by Pseudomonas aeruginosa: optimisation and antibacterial activity against selected waterborne human pathogens

Multiple drug resistance and treatment of contaminated water has become a serious issue in past years. Silver nanoparticles (AgNPs), being bactericidal, non-toxic, cheap and environment friendly behaviour, have drawn attention to overcome these problems. This study has been designed to synthesise AgNPs from Pseudomonas aeruginosa. AgNPs formation was confirmed by colour change and UV-vis spectroscopy. Furthermore, Fourier transform infrared spectroscopy peaks demonstrated the presence of capped proteins as reducing and stabilising agent. Transmission electron microscopy micrograph revealed spherical shape AgNPs with the size ranging between 10 and 20 nm. Antibacterial activity of AgNPs was evaluated against the most prevalent waterborne pathogens enterohaemorrhagic Escherichia coli and Salmonellae typhimurium. Moreover, the antibacterial activity of AgNPs was tested for the treatment of contaminated water which showed attenuation in bacterial load within 8 h as demonstrated by growth kinetics data. Furthermore, AgNPs did not exhibit haemolytic effects on human red blood cells (RBCs) even at 100 mg L-1 concentration of AgNPs. The results herein suggest that AgNPs synthesised by P. aeruginosa under optimised conditions exhibit microbicidal property against waterborne pathogens and having no toxic effect on human RBCs. These AgNPs could be employed for treatment of contaminated water after process optimisation.

Adrenocortical Suppression in Children with Nephrotic Syndrome Treated with Low-Dose Alternate Day Corticosteroids

Corticosteroids form the mainstay of therapy for all forms of nephrotic syndrome. The long-term use of this medication is associated with serious side effects including adrenocortical suppression. The primary objective of this study was to identify adrenocortical suppression (assessed by single morning serum cortisol levels) in children with nephrotic syndrome on treatment with low-dose alternate day steroids. This cross-sectional study was conducted in the Department of Pediatrics in a tertiary care hospital from January 2014 to January 2015. Seventy children (1–18 years) with nephrotic syndrome (steroid sensitive and resistant) who were in remission and on low-dose alternate day steroids for at least 8 weeks or had received steroids of 2 mg/kg/d for at least 2 weeks in the last 1 year (infrequent relapsers) were enrolled. Relevant history was taken, clinical examination was done and blood samples were drawn for serum cortisol, lipid profile, kidney function tests, fasting blood sugar, glycated hemoglobin (HbA_1c), and serum albumin. Forty percent (28/70) children had adrenocortical suppression as assessed by low morning serum cortisol levels. The mean serum cortisol levels were 188 nmol/L and were significantly lower in frequently relapsing individuals (85.9 nmol/L) as compared to other types of nephrotic syndrome (P = 0.05). The prevalence of adrenocortical suppression was higher in steroid-resistant patients (57%) as compared to 28% in frequently relapsing and 11% in steroid-dependent patients. Fifty-seven percent of patients with adrenocortical suppression had short stature while 50% had obesity. All individuals had normal serum HbA_1c levels. The cumulative steroid doses and total duration of corticosteroid therapy were significantly higher in patients with adrenocortical suppression. Children with nephrotic syndrome treated with low-dose alternate day steroids have a high prevalence of adrenocortical suppression on screening with single morning cortisol sample. Those with frequently relapsing or steroid-resistant diseases are at a higher risk of suppression.

Neutrophil Extracellular Traps: Formation and Involvement in Disease Progression

Neutrophils are the forerunner in innate immunity by defending the host organisms against infectious pathogens. During such process, neutrophils reach the site of inflammation/infection and eliminate the pathogens by phagocytosis as well as by forming the neutrophil extracellular traps (NETs). NETs trap and eradicate a number of microbes including bacteria, fungi, protozoa, viruses. NETs consist of DNA which is decorated with histones and granular proteins such as neutrophil elastase (NE), gelatinase, myeloperoxidase. NETosis (a process of NETs formation) is also involved in many inflammatory and autoimmune disorders with a major contribution to acute respiratory distress syndrome, sepsis, cystic fibrosis, periodontitis. Hyper NETosis or ineffective clearance of NETs would likely increase the risk of auto-antibody generation against NETs components and contribution in auto-inflammatory diseases. The purpose of this review is intended to highlight the molecular mechanisms of NETosis and its antimicrobial effect. Furthermore, a current status of NETosis in the pathogenesis of inflammatory and autoimmune disorders has been reviewed for better understanding.

Evaluation of oxidative stress and antioxidant status: Correlation with the severity of sepsis

Sepsis is a condition caused by infection followed by unregulated inflammatory response which may lead to the organ dysfunction. During such condition, over-production of oxidants is one of the factors which contribute cellular toxicity and ultimately organ failure and mortality. Antioxidants having free radicals scavenging activity exert protective role in various diseases. This study has been designed to evaluate the levels of oxidative and antioxidative activity in sepsis patients and their correlation with the severity of the sepsis. A total of 100 sepsis patients and 50 healthy controls subjects were enrolled in this study from the period October 2016 to June 2017. The investigation included measurements of oxidative enzyme, myeloperoxidase (MPO), antioxidant enzymes including superoxide dismutase activity (SOD) and catalase activity (CAT) and cytokines (TNF-α, IL-8 and IFN-γ). Furthermore, the level of these activities was correlated with severity of sepsis. Augmented levels of oxidants were found in sepsis as demonstrated by DMPO nitrone adduct formation and plasma MPO level activity (1.37 ± 0.51 in sepsis vs 0.405 ± 0.16 in control subjects). Cytokines were also found to be increased in sepsis patients. However, plasma SOD and CAT activities were significantly attenuated (P < .001) in the sepsis patients compared with controls subjects. Moreover, inverse relation between antioxidant enzymes (SOD and CAT) and organ failure assessment (SOFA), physiological score (APACHE II), organ toxicity specific markers have been observed as demonstrated by Pearson's correlation coefficient. This study suggests that imbalance between oxidant and antioxidant plays key role in the severity of sepsis.

Antibacterial Synergy of Silver Nanoparticles with Gentamicin and Chloramphenicol against Enterococcus faecalis

Background:

Enterococcus faecalis (Ef) is a multidrug-resistant pathogenic bacteria associated with hospital-acquired infections. Ef is involved in a number of infectious diseases. It generally infects patients with the weekend immune system, i.e. a person mostly acquires Ef infections in the hospital, especially in intensive care units and thus, is more likely to be resistant to many antibiotics. Development of resistance against various antibiotics and emergence of drug-resistant strains is a growing global concern.

Objective:

Due to the unselective use of antibiotics for a long time multidrug resistant bacteria and extensively drug-resistant, which is now posing a new challenge to the medical community. To treat infections caused by Ef, the synergistic effect of different antibiotics with silver nanoparticles (AgNPs) was tested against Ef.

Materials and Methods:

In the present study, synthesis of AgNPs was carried out from the cell-free supernatant of Klebsiella pneumoniae. AgNPs were characterized using various techniques, namely, ultraviolet-visible spectrophotometry, transmission electron microscopy, and Fourier transform infrared spectroscopy. Moreover, process optimization was done for enhanced production of AgNPs. In addition, antimicrobial activity of the nanoparticles was also tested. Furthermore, the nanoparticles were evaluated for their antimicrobial activities in combination with gentamicin and chloramphenicol, against Ef.

Results:

The results showed that the combination of gentamicin and chloramphenicol with AgNPs has a better antibacterial effect. To add to this, hemolytic activity of AgNPs was evaluated against human red blood corpuscles (RBCs). AgNPs were found to be nontoxic to RBCs.

Conclusion:

The collective effect of AgNps with Gentamicin and Chloramphenicol was more as compared to AgNps alone which indicate the synergistic effect of these components. These observations show the potential of AgNPs in combination with above-stated antibiotics against Ef infections.

SUMMARY

Enterococcus faecalis (Ef) is a multidrug-resistant bacteria with is resistant to wide range of antibiotics

Due to this increasing resistance, there is a need to find a new approach to overcome the infections caused by Ef

The combined effect of silver nanoparticles (AgNPs) with gentamicin and chloramphenicol was notably seen against Ef

Furthermore, the AgNPs were nontoxic to the human red blood corpuscles which confirm its nontoxic nature.

Abbreviations used: Ef: Enterococcus faecalis, MDR: Multidrug resistance, AgNPs: Silver nanoparticles, Kp: Klebsiella pneumoniae, RBCs: Red blood corpuscles, ENPs: Engineered nanoparticles, FTIR: Fourier transform infrared spectroscopy, TEM: Transmission electron microscopy, AgNO₃: Silver nitrate, EDTA: Ethylenediaminetetraacetic acid, PBS: Phosphate-buffered saline.