Elucidating the abilities of MDM2, MDMX and p21 to regulate ferroptosis

In this thesis, I have explored the role of three genes related to p53, namely p21, MDM2 and MDMX, in regulating ferroptosis, a form of non-apoptotic cell death. Ferroptosis, an iron-dependent mechanism that leads to cell death due to lipid peroxidation, has a large potential to be used as a cancer therapy. My results indicate that p21, the effector of p53-mediated cell cycle arrest, can suppress ferroptosis possibly through its interaction with CDKs. Further, that MDM2 and MDMX, the negative regulators of p53, can act as pro-ferroptosis agents and that this role is independent of p53. Using various approaches to alter their activity, I found that MDM2 and MDMX, likely working in part as a complex, normally facilitate ferroptotic death. They were found to alter the cellular lipid profile to prevent the cells from mounting an adequate defense against lipid peroxidation. For example, inhibition of MDM2 or MDMX lead to increased levels of FSP1 protein and a consequent increase in the levels of coenzyme Q₁₀, an endogenous lipophilic antioxidant. Moreover, I found that PPARα activity is essential for MDM2 and MDMX to promote ferroptosis. My findings also suggest that MDM2-MDMX inhibition might be useful for preventing degenerative diseases involving ferroptosis. Further, that MDM2/MDMX amplification may predict sensitivity of some cancers to ferroptosis inducers. Therefore, I believe that this thesis project has successfully identified several new regulators of ferroptosis and this knowledge can aid better design of therapies centered around ferroptosis

Evolution of vesicular transport in kinetoplastids: dynamics and novel gene products

The membrane trafficking system mediates delivery of macromolecules and metabolites to discrete intracellular compartments from their site of uptake or synthesis. For many pathogens the trafficking system has a special relevance as it is responsible for maintaining the host-pathogen interface, i.e., the cell surface. Both the surface and the underlying trafficking apparatus are intimately connected with immune evasion in many parasites including those belonging to the highly divergent order Kinetoplastida. Kinetoplastid parasites are etiological agents of several neglected tropical diseases such as African sleeping sickness, Chagas disease, and Leishmaniasis. Newly available sequences of many kinetoplastid genomes were used to reconstruct evolution of trafficking across this lineage, using three central paralogous trafficking families: Rabs, SNAREs and Rab-GAPs, which have defined roles in specific trafficking events. Further, proteomics was used to analyse a representative SNARE complex to explore compositional conservation between kinetoplastids and Opistokhonts. Overall there is little evidence for large scale expansions or contractions of these protein families, excluding a direct association with parasitism or changes to host range, host immunosophistication or transmission mechanisms. The data indicate a stepwise sculpting of the trafficking system where the large repertoire of the basal bodonids is mainly retained by the cruzi group, while extensive lossses characterise other lineages, particularly the African trypanosomes and phytomonads. Kinetoplastids possess several lineage-specific Rabs but all retain a core canonical Rab set; by contrast there is little novelty within the SNARE family even though certain canonical endosomal SNAREs appear to show a considerable degree of sequence divergence. Proteomics suggests that SNARE complex composition is largely conserved. The major changes in Rab and SNARE repertoires are associated with endosomal and late exocytic pathways, which is consistent with the considerable evolution of surface proteomes. Therefore, despite the absence of a transition per se associated with parasitism, adaptation of membrane trafficking is likely under active selection where it meets the host environment.The Gates Cambridge Scholarship Lundgren Research Award Philosophical Society Research Studentship Research - Wellcome Trus

HERBAL DRUG SWIETENIA MAHAGONI JACQ. -A REVIEW

ABSTRACT The dire need for such a review arises as the plant is included in the list of endangered species due to its high exploitation for timber utilization

A STUDY ON THE CONSUMER BEHAVIOUR DURING FESTIVE SEASON IN MALLS

The aim of the study is to find out how the customers behave during festive seasons Christmas, Diwali and New Year in malls. In today’s world there are a lot of promotions and strategies to attract customers. The buying pattern of customers, generally, changes during festive seasons. This study focuses on finding how the customer’s buying pattern varies from normal days to festive days. The conclusion is that further importance has to be given towards improvement of quality of service during festival seasons

Nature of carrier injection in metal/2D semiconductor interface and its implications to the limits of contact resistance

Monolayers of transition metal dichalcogenides (TMDCs) exhibit excellent electronic and optical properties. However, the performance of these two-dimensional (2D) devices are often limited by the large resistance offered by the metal contact interface. Till date, the carrier injection mechanism from metal to 2D TMDC layers remains unclear, with widely varying reports of Schottky barrier height (SBH) and contact resistance (Rc), particularly in the monolayer limit. In this work, we use a combination of theory and experiments in Au and Ni contacted monolayer MoS2 device to conclude the following points: (i) the carriers are injected at the source contact through a cascade of two potential barriers - the barrier heights being determined by the degree of interaction between the metal and the TMDC layer; (ii) the conventional Richardson equation becomes invalid due to the multi-dimensional nature of the injection barriers, and using Bardeen-Tersoff theory, we derive the appropriate form of the Richardson equation that describes such composite barrier; (iii) we propose a novel transfer length method (TLM) based SBH extraction methodology, to reliably extract SBH by eliminating any confounding effect of temperature dependent channel resistance variation; (iv) we derive the Landauer limit of the contact resistance achievable in such devices. A comparison of the limits with the experimentally achieved contact resistance reveals plenty of room for technological improvements.Comment: Accepted in Physical Review

Avian Influenza Viruses in Wild Birds: Virus Evolution in a Multihost Ecosystem.

Wild ducks and gulls are the major reservoirs for avian influenza A viruses (AIVs). The mechanisms that drive AIV evolution are complex at sites where various duck and gull species from multiple flyways breed, winter, or stage. The Republic of Georgia is located at the intersection of three migratory flyways: the Central Asian flyway, the East Africa/West Asia flyway, and the Black Sea/Mediterranean flyway. For six complete study years (2010 to 2016), we collected AIV samples from various duck and gull species that breed, migrate, and overwinter in Georgia. We found a substantial subtype diversity of viruses that varied in prevalence from year to year. Low-pathogenic AIV (LPAIV) subtypes included H1N1, H2N3, H2N5, H2N7, H3N8, H4N2, H6N2, H7N3, H7N7, H9N1, H9N3, H10N4, H10N7, H11N1, H13N2, H13N6, H13N8, and H16N3, and two highly pathogenic AIVs (HPAIVs) belonging to clade 2.3.4.4, H5N5 and H5N8, were found. Whole-genome phylogenetic trees showed significant host species lineage restriction for nearly all gene segments and significant differences in observed reassortment rates, as defined by quantification of phylogenetic incongruence, and in nucleotide sequence diversity for LPAIVs among different host species. Hemagglutinin clade 2.3.4.4 H5N8 viruses, which circulated in Eurasia during 2014 and 2015, did not reassort, but analysis after their subsequent dissemination during 2016 and 2017 revealed reassortment in all gene segments except NP and NS. Some virus lineages appeared to be unrelated to AIVs in wild bird populations in other regions, with maintenance of local AIVs in Georgia, whereas other lineages showed considerable genetic interrelationships with viruses circulating in other parts of Eurasia and Africa, despite relative undersampling in the area.IMPORTANCE Waterbirds (e.g., gulls and ducks) are natural reservoirs of avian influenza viruses (AIVs) and have been shown to mediate the dispersal of AIVs at intercontinental scales during seasonal migration. The segmented genome of influenza viruses enables viral RNA from different lineages to mix or reassort when two viruses infect the same host. Such reassortant viruses have been identified in most major human influenza pandemics and several poultry outbreaks. Despite their importance, we have only recently begun to understand AIV evolution and reassortment in their natural host reservoirs. This comprehensive study illustrates AIV evolutionary dynamics within a multihost ecosystem at a stopover site where three major migratory flyways intersect. Our analysis of this ecosystem over a 6-year period provides a snapshot of how these viruses are linked to global AIV populations. Understanding the evolution of AIVs in the natural host is imperative to mitigating both the risk of incursion into domestic poultry and the potential risk to mammalian hosts, including humans

Comparison of 2016–17 and Previous Epizootics of Highly Pathogenic Avian Influenza H5 Guangdong Lineage in Europe

We analyzed the highly pathogenic avian influenza (HPAI) H5 epizootic of 2016–17 in Europe by epidemiologic and genetic characteristics and compared it with 2 previous epizootics caused by the same H5 Guangdong lineage. The 2016–17 epizootic was the largest in Europe by number of countries and farms affected and greatest diversity of wild birds infected. We observed significant differences among the 3 epizootics regarding region affected, epidemic curve, seasonality, and outbreak duration, making it difficult to predict future HPAI epizootics. However, we know that in 2005–06 and 2016–17 the initial peak of wild bird detections preceded the peak of poultry outbreaks within Europe. Phylogenetic analysis of 2016–17 viruses indicates 2 main pathways into Europe. Our findings highlight the need for global surveillance of viral changes to inform disease preparedness, detection, and control

Comparison of 2016–17 and Previous Epizootics of Highly Pathogenic Avian Influenza H5 Guangdong Lineage in Europe

We analyzed the highly pathogenic avian influenza (HPAI) H5 epizootic of 2016–17 in Europe by epidemiologic and genetic characteristics and compared it with 2 previous epizootics caused by the same H5 Guangdong lineage. The 2016–17 epizootic was the largest in Europe by number of countries and farms affected and greatest diversity of wild birds infected. We observed significant differences among the 3 epizootics regarding region affected, epidemic curve, seasonality, and outbreak duration, making it difficult to predict future HPAI epizootics. However, we know that in 2005–06 and 2016–17 the initial peak of wild bird detections preceded the peak of poultry outbreaks within Europe. Phylogenetic analysis of 2016–17 viruses indicates 2 main pathways into Europe. Our findings highlight the need for global surveillance of viral changes to inform disease preparedness, detection, and control

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707