Theoretical And Experimental Studies On The Instability Of Charged Liquid Drops

To be able to properly predict the breakup of highly charged liquid droplets, a complete understanding of their behavior at the Rayleigh limit is necessary. An analytical model has been developed for a conductive spherical drop charged to its Rayleigh limit which predicts the final state just after the breakup for both single and multi-sibling disintegrations. The numerical analysis of this model involves scanning all the possible radii of the sibling droplets and ensuring that the solutions satisfy the conservation of energy and Rayleigh limit criteria. For a drop unaffected by any external force, the results of this model show that the most probable disintegration satisfies the single sibling breakup. The sibling, under such conditions, carries about 25% of the initial mass and 40% of the initial charge. The results also show that the difference between the final energy, calculated at different sibling mass ratios, and the minimum final energy is very small for a very wide range of sibling mass ratios (0.1 to 0.9) and thus can be easily affected by any external force to produce a multi-sibling disintegration. For the multi-sibling case, the model assumes tree-like secondary breakups which lead to a residual drop and n siblings of different sizes and charges. The results of this model show good agreement with the experimental observations of many other investigators. The numerical results also show that the single sibling exists for all the values of sibling mass ratios greater than 11.1%. For all the values less than this, the multi-sibling disintegration is favoured. This has been verified experimentally by collecting water droplets after their breakup on water sensitive paper and then examining their traces with a microscope.;Since the Rayleigh limit is only valid for spherical droplets unaffected by any external force, general equations describing the drop stability have been derived for both prolate and oblate spheroidal shapes. From the analytical evaluation of these equations, it was concluded that the Rayleigh limit is only valid for small droplet sizes (R {dollar}\u3c{dollar} 50 {dollar}\mu{dollar}m) and for very low levels of external forces. (Abstract shortened with permission of author.

Characterising the senescence-like phenotype induced by the typhoid toxin of Salmonella Typhi

Cellular senescence is an innate physiological mechanism crucial in development, wound healing and tumour suppression. It is characterised by an irreversible cell cycle arrest, resistance to apoptosis, and an inflammatory secretome that remodels bystander cells, referred to as senescence-associated secretory phenotype (SASP). SASP acts in an autocrine or paracrine manner to reinforce senescence, transmit senescence to naive cells and activate immunosurveillance to remove cells of pathological potential. In ageing organisms, senescent cells accumulate, resulting in SASP-driven chronic inflammation, aberrant tissue homeostasis and immune functions, and age-related pathologies such as cancer. Ageing also comes with an increased susceptibility to infectious diseases but the cellular basis for this is unclear. Salmonella Typhi causes more than 11 million cases of drug-resistant typhoid fever cases each year that are spreading intercontinentally, making it a global health concern. The typhoid toxin of Salmonella Typhi causes DNA damage, cell cycle arrest and cell distension, which are indicative of senescence. Toxin-induced DNA damage is associated with mortality, typhoid fever symptoms and chronic Salmonella carriage in animal models, which aids in pathogen shedding and disease transmission. Therefore, dissecting the typhoid toxin virulence mechanism is of utmost importance. Using molecular and cellular biology, this thesis substantiates evidence that the typhoid toxin induces senescence in vitro marked by persistent DNA damage responses, increased senescence associated β-galactosidase, p21 activity, diminished lamin B1, and paracrine senescence via toxin-induced SASP (toxSASP). Interestingly, previous work in our lab demonstrated that toxSASP uniquely promoted Salmonella infection, while aphidicolin (APH), i.e. another senescence inducer, did not. This finding indicates that factors in the host secretome increase the susceptibility of bystander cells to Salmonella infection but the identity of the SASP factors are unknown. Using unbiased LC-MS/MS and GeneChip microarray transcriptomics, this thesis reveals toxSASP constituents which were divergent from other senescence inducers, namely APHSASP and ETPSASP. Additionally, in vitro experiments implicate potential crosstalk between TGFβ and Wnt5a signalling pathway in toxin-induced senescence phenotypes. Indeed, purified Activin A, a TGFβ ligand, and Wnt5A contributed to toxSASP paracrine senescence. Furthermore, TGFβ receptors knockdown via siRNAs ameliorated Salmonella invasion induced by toxSASP. In conclusion, this study reveals the first proteomic characterisation of a SASP induced by a bacterial toxin. The study represents a Salmonella hijacking mechanism via the TGFβ signalling pathway, which represents a novel host-pathogen interaction that may be of significance to invasive infections underlying typhoid fever and chronic carriage. This thesis is of broad significance as it reveals a way by which bacterial pathogens can reprogramme multicellular infection niches by hijacking the host secretome through DNA damage responses

Typhoid toxin exhausts the RPA response to DNA replication stress driving senescence and Salmonella infection.

Salmonella Typhi activates the host DNA damage response through the typhoid toxin, facilitating typhoid symptoms and chronic infections. Here we reveal a non-canonical DNA damage response, which we call RING (response induced by a genotoxin), characterized by accumulation of phosphorylated histone H2AX (γH2AX) at the nuclear periphery. RING is the result of persistent DNA damage mediated by toxin nuclease activity and is characterized by hyperphosphorylation of RPA, a sensor of single-stranded DNA (ssDNA) and DNA replication stress. The toxin overloads the RPA pathway with ssDNA substrate, causing RPA exhaustion and senescence. Senescence is also induced by canonical γΗ2ΑΧ foci revealing distinct mechanisms. Senescence is transmitted to non-intoxicated bystander cells by an unidentified senescence-associated secreted factor that enhances Salmonella infections. Thus, our work uncovers a mechanism by which genotoxic Salmonella exhausts the RPA response by inducing ssDNA formation, driving host cell senescence and facilitating infection

Implementation of breast cancer continuum of care in low- and middle-income countries during the COVID-19 pandemic

Breast cancer is the most common malignancy among women worldwide. The current COVID-19 pandemic represents an unprecedented challenge leading to care disruption, which is more severe in low- and middle-income countries (LMIC) due to existing economic obstacles. This review presents the global perspective and preparedness plans for breast cancer continuum of care amid the COVID-19 outbreak and discusses challenges faced by LMIC in implementing these strategies. Prioritization and triage of breast cancer patients in a multidisciplinary team setting are of paramount importance. Deescalation of systemic and radiation therapy can be utilized safely in selected clinical scenarios. The presence of a framework and resource-adapted recommendations exploiting available evidence-based data with judicious personalized use of current resources is essential for breast cancer care in LMIC during the COVID-19 pandemic

Efficacy and safety of Elagolix in the treatment of endometriosis associated pain: a systematic review and network meta-analysis

Background: Endometriosis commonly presents with dysmenorrhea, non-menstrual pelvic pain, and infertility. Elagolix is an oral, short-acting, gonadotropin-releasing hormone antagonist acting through complete estrogen suppression. Objective: To evaluate the evidence from published randomized controlled trials (RCTs) about the efficacy and safety of Elagolix in the treatment of endometriosis associated pain. Search strategy: Electronic databases containing articles published between January 2000 and February 2020 were searched using the MeSH terms (Elagolix OR gonadotropin-releasing hormone antagonist OR GnRH antagonist OR antigonadotropin) AND (endometriosis) AND (pelvic pain). Selection criteria: All RCTs assessing the efficacy of Elagolix in the treatment of pain associated with endometriosis were considered for this network meta-analysis, where five studies were deemed eligible for this review. Data collection and analysis: The mean difference (MD) and confidence intervals (95% CI) for continuous outcomes including analgesic use, dysmenorrhea, non-menstrual pelvic pain, and quality of life were calculated. Main results: Elagolix 250 mg reduced dysmenorrhea significantly, as compared to placebo, (MD = -0.41, 95% CI [-0.7, -0.13]) at 12 weeks, while Elagolix 200 mg reduced dysmenorrhea significantly (MD= -1.2, 95% CI [-1.9, -0.57]) compared to placebo after 24 weeks of treatment. Conclusions: Elagolix 200 mg seems to be an effective drug with fewer side effects when used to reduce dysmenorrhea and non-menstrual pelvic pain after 24 weeks of treatment in patients with endometriosis

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P < 0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P = 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P = 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Burden of tracheal, bronchus, and lung cancer in North Africa and Middle East countries, 1990 to 2019: Results from the GBD study 2019

ObjectiveTo provide estimates on the regional and national burden of tracheal, bronchus, and lung (TBL) cancer and its attributable risk factors from 1990 to 2019 in the North Africa and Middle East (NAME) region.Methods and materialsThe Global Burden of Disease (GBD) 2019 data were used. Disability-adjusted life years (DALYs), death, incidence, and prevalence rates were categorized by sex and age groups in the NAME region, in 21 countries, from 1990 to 2019. Decomposition analysis was performed to calculate the proportion of responsible factors in the emergence of new cases. Data are presented as point estimates with their 95% uncertainty intervals (UIs).ResultsIn the NAME region, TBL cancer caused 15,396 and 57,114 deaths in women and men, respectively, in 2019. The age-standardized incidence rate (ASIR) increased by 0.7% (95% UI -20.6 to 24.1) and reached 16.8 per 100,000 (14.9 to 19.0) in 2019. All the age-standardized indices had a decreasing trend in men and an increasing trend in women from 1990 to 2019. Turkey (34.9 per 100,000 [27.6 to 43.5]) and Sudan (8.0 per 100,000 [5.2 to 12.5]) had the highest and lowest age-standardized prevalence rates (ASPRs) in 2019, respectively. The highest and lowest absolute slopes of change in ASPR, from 1990 to 2019, were seen in Bahrain (-50.0% (-63.6 to -31.7)) and the United Arab Emirates (-1.2% (-34.1 to 53.8)), respectively. The number of deaths attributable to risk factors was 58,816 (51,709 to 67,323) in 2019 and increased by 136.5%. Decomposition analysis showed that population growth and age structure change positively contributed to new incident cases. More than 80% of DALYs could be decreased by controlling risk factors, particularly tobacco use.ConclusionThe incidence, prevalence, and DALY rates of TBL cancer increased, and the death rate remained unchanged from 1990 to 2019. All the indices and contribution of risk factors decreased in men but increased in women. Tobacco is still the leading risk factor. Early diagnosis and tobacco cessation policies should be improved

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030