Browsing by Author "John, Chandy"

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    Characterization of a Novel Fis1 Interactor Required for Peripheral Distribution of the Mitochondrion of Toxoplasma Gondii
    (2021-02) Jacobs, Kylie; Arrizabalaga, Gustavo; Gilk, Stacey; Graham, Brett; John, Chandy; Yang, Frank
    Toxoplasma’s singular mitochondrion is extremely dynamic and undergoes morphological changes throughout the parasite’s life cycle. While intracellular‚ the mitochondrion is maintained in a lasso shape that stretches around the parasite periphery and is in close proximity to the pellicle‚ suggesting the presence of membrane contact sites. Upon egress‚ these contact sites disappear‚ and the mitochondrion retracts and collapses towards the apical end of the parasite. Once reinvaded‚ the lasso shape is quickly reformed‚ indicating that dynamic membrane contact sites regulate the positioning of the mitochondrion. We discovered a novel protein (TgGT1_265180) that associates with the mitochondrion via interactions with the fission related protein Fis1. Knockout of TgGT1_265180‚ which we have dubbed LMF1 for Lasso Maintenance Factor 1‚ results in a complete disruption of the normal mitochondrial morphology. In intracellular LMF1 knockout parasites, the mitochondrial lasso shape is disrupted‚ and instead it is collapsed as normally only seen in extracellular parasites. Additionally, proper mitochondrial segregation is disrupted‚ resulting in parasites with no mitochondrion and extra mitochondrial material outside of the parasites. These gross morphological changes are associated with a significant reduction of parasite propagation and can be rescued by reintroduction of a wildtype copy of LMF1. Co-immunoprecipitations and Yeast Two-Hybrid predict interactions with the parasite pellicle. Therefore, we hypothesize that LMF1 mediates contact between the mitochondrion and the pellicle in a regulatable fashion‚ and that the LMF1-dependent morphodynamics are critical for parasite propagation. Current studies are focused on characterizing the consequences of mitochondrial collapse and identifying proteins that interact with LMF1 to position the mitochondrion to the periphery of the parasite.
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    Inhaled nitric oxide as adjunctive therapy for severe malaria: a randomized controlled trial
    (BioMed Central, 2015-10-29) Hawkes, Michael T.; Conroy, Andrea L.; Opoka, Robert O.; Hermann, Laura; Thorpe, Kevin E.; McDonald, Chloe; Kim, Hani; Higgins, Sarah; Namasopo, Sophie; John, Chandy; Miller, Chris; Liles, W. Conrad; Kain, Kevin C.; Department of Pediatrics, School of Medicine
    Background Severe malaria remains a major cause of childhood mortality globally. Decreased endothelial nitric oxide is associated with severe and fatal malaria. The hypothesis was that adjunctive inhaled nitric oxide (iNO) would improve outcomes in African children with severe malaria. Methods A randomized, blinded, placebo-controlled trial of iNO at 80 ppm by non-rebreather mask versus room air placebo as adjunctive treatment to artesunate in children with severe malaria was conducted. The primary outcome was the longitudinal course of angiopoietin-2 (Ang-2), an endothelial biomarker of malaria severity and clinical outcome. Results One hundred and eighty children were enrolled; 88 were assigned to iNO and 92 to placebo (all received IV artesunate). Ang-2 levels measured over the first 72 h of hospitalization were not significantly different between groups. The mortality at 48 h was similar between groups [6/87 (6.9 %) in the iNO group vs 8/92 (8.7 %) in the placebo group; OR 0.78, 95 % CI 0.26–2.3; p = 0.65]. Clinical recovery times and parasite clearance kinetics were similar (p > 0.05). Methaemoglobinaemia >7 % occurred in 25 % of patients receiving iNO and resolved without sequelae. The incidence of neurologic deficits (<14 days), acute kidney injury, hypoglycaemia, anaemia, and haemoglobinuria was similar between groups (p > 0.05). Conclusions iNO at 80 ppm administered by non-rebreather mask was safe but did not affect circulating levels of Ang-2. Alternative methods of enhancing endothelial NO bioavailability may be necessary to achieve a biological effect and improve clinical outcome.
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    Investigating Differences in Nutritional Parameters in Ugandan Children with Plasmodium falciparum Severe Malaria
    (2020-07) Brown, Lucy; Co, Katrina; Bond, Caitlin; Opoka, Robert; Datta, Dibya; John, Chandy
    Background: The past two decades have witnessed a 60% decline in global malaria mortality. However, two thirds of all malaria deaths continue to occur among children <5 years, with a majority in the WHO African Region. Malnutrition is an important risk factor for malaria. Wasting, Stunting and Underweight are crucial indicators of malnutrition, and are associated with increased mortality in children <5. Annually, 14 million children <5 are classified as wasted and 59 million children are classified as stunted. Objective: The objective of this study is to look at nutritional parameters, weight-for-age (WAZ), height-for-age (HAZ), and weight-for-height (WHZ), and how they differ over time in children <5 with severe malaria (SM) from the Ugandan cities Mulago and Jinja and the outcomes of mortality and nutritional parameters, underweight, stunting, and wasting. Methods: We defined underweight, stunting, and wasting as 2SD below the WAZ, HAZ, and WHZ means. We evaluated Z-scores and mortality status from children <5 years enrolled in a prospective cohort study (NDI, Neurodevelopmental Impairment in Children with Severe Malaria) at enrollment and 12-month follow-up between two sites. Results: WAZ, HAZ and WHZ at baseline were significantly lower among SM groups than in CC (p<0.01), and the SM group maintained significantly lower WHZ (p<0.01) and HAZ (p<0.001) at 12-month follow-up. Among the children who died, there were no significant differences of nutritional markers in Mulago, but in Jinja there was found to be a significant association between mortality and low WAZ (p<0.05) and underweight (p<0.05). Of children classified as underweight in Jinja, 37.5% of them died compared to 15.9% who survived; additionally, the odds ratio for decreased WAZ and mortality was 0.58 (p<0.05). Conclusion: Underweight, stunting, and wasting may be risk factors for SM, and underweight may exacerbate poor mortality outcomes in rural areas like Jinja. While underweight is worsened among children with SM at 1 month and normalizes by 12 months, stunting remains persistently low at 12 months. Nutritional interventions must be aimed at maintaining linear growth throughout the first year of SM in children <5 to reduce the risk factor of underweight on poor mortality outcomes.
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    The Role of PfEMP1 Expression and Immunity in Ugandian Children with Severe Malaria
    (2022-05) Fernander, Elizabeth M.; John, Chandy; Bauer, Margaret; Gilk, Stacey; Tran, Tuan
    Severe malaria, primarily caused by Plasmodium falciparum infection, is among the leading causes of childhood mortality globally. A key virulence factor and source of antigenic variation and immune evasion during infection is P. falciparum erythrocyte membrane protein 1 (PfEMP1). Encoded for by approximately 60 var genes, this complex protein mediates cytoadherence of infected erythrocytes to the host endothelium and is a prominent immune target for the anti-malarial immune response in children. During severe malaria, specific domains of PfEMP1 that bind to endothelial protein C receptor (EPCR) and intercellular adhesion molecule-1 (ICAM-1) on host endothelial cells, are more prevalently expressed. The interaction of these proteins and infected erythrocytes mediates the sequestration of infected erythrocytes and plays a role in severe malaria pathogenesis. Antibodies to these domains develop over time with exposure to the parasite and are thought to contribute to immunity against severe malaria in children. In this study, whole blood samples from children with different forms of severe malaria, enrolled in two observational prospective cohort studies were used to quantify the expression of PfEMP1 domains using RT-qPCR and to measure the antibody response to PfEMP1 domains via a bead-based multiplex immunoassay. Using these samples, we demonstrated that although the expression of var transcripts encoding PfEMP1 domains was generally similar across children with different forms of severe malaria, the expression of variants encoding specific EPCR-binding domains was associated with thrombocytopenia and severe anemia. The antibody response to PfEMP1 domains in children with severe malaria was highest in children with SMA and children with asymptomatic parasitemia, but not associated with decreased risk of additional malaria episodes. Overall, the results of this study suggest that PfEMP1 is acting similarly across different forms of severe malaria but that it can be related to pathogenesis and severe malaria immunity.
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    Systems Thinking for Public Health: A Case Study Using U.S. Public Education
    (National Academy of Sciences, 2023-11-07) Ashby, Elizabeth; Minicucci, Charlie; Liao, Julie; Buonsenso, Danilo; González-Dambrauskas, Sebastián; Obregón, Rafael; Zahn, Matt; Hallman, William; John, Chandy; Pediatrics, School of Medicine
    The initial response to the COVID-19 pandemic in the United States largely focused on addressing the immediate health consequences from the emergent pathogen. This initial focus often ignored the related impacts from the pandemic and from mitigation measures, including how existing social determinants of health compounded physical, social, and economic impacts on individuals who have historically been marginalized. The consequences of decisions around closing and reopening primary and secondary (K—12 in the United States) public schools exemplify the complex impacts of pandemic mitigation measures. Ongoing COVID-19 mitigation and recovery efforts have gradually begun addressing indirect consequences, but these efforts were slow to be identified and adopted through much of the acute phase of the pandemic, mirroring the decades-long neglect of contributors to the overall health and well-being of populations that have been made to be vulnerable. A systems approach for decision making and problem solving holistically considers the effects of complex interacting factors. Taking a systems approach at the start of the next health emergency could encourage response strategies that consider various competing public health needs throughout different sectors of society, account for existing disparities, and preempt undesirable consequences before and during response implementation. There is a need to understand how a systems approach can be better integrated into decision making to improve future responses to public health emergencies. A wide range of stakeholders should contribute expertise to these models, and these partnerships should be formed in advance of a public health emergency.
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    Underweight is Associated with Mortality Among Ugandan Children with Plasmodium falciparum Severe Malaria
    (2021-08) Brown, Lucy; Co, Katrina; Bond, Caitlin; Datta, Dibya; John, Chandy; Opoka, Robert
    Background: The past two decades have witnessed a 60% decline in global malaria mortality. However, two thirds of all malaria deaths continue to occur among children <5 years, with a majority in the WHO African Region. Malnutrition is an important risk factor for malaria. Globally, wasting, stunting and being underweight are crucial indicators of malnutrition, and are associated with increased mortality in children <5. Those most vulnerable to malaria and malnutrition are children <5 living in Sub-Saharan Africa, particularly in rural areas often facing a higher burden of disease.Objective: The objective of this study was to assess the prevalence and persistence of nutritional abnormalities causing children to be underweight, stunted, or show signs of wasting, and the association of these abnormalities with in-hospital and post-discharge mortality, risk of repeat illness and long-term sequelae in Ugandan children with 5 different forms of severe malaria (SM) compared to community children (CC).Methods: We conducted a prospective observational study investigating neurocognitive outcomes at 12-months after severe malaria episode in 600 children with SM and 120 CC, aged 0.5-4 years, between 2014-2017 at 2 hospitals (Kampala and Jinja) in Uganda. Using age-adjusted scores from healthy CC, we calculated z-scores for weight-for-age (WAZ), height-for-age (HAZ), and weight-for-height (WHZ). We defined underweight, stunting, and wasting as 2SD below the WAZ, HAZ, and WHZ means. Results: At baseline, children with SM had significantly lower mean WAZ and HAZ compared to CC (-1.1 [1.1 SD] vs. -0.47 [1.1], p<0.001; -0.68 [1.1] vs. 0.30 [1.0], p<0.001, respectively), with no difference by site. By 12-month follow-up there were no significant differences in nutritional markers between SM and CC. During admission, 44 (7.3%) children with SM died. Higher baseline WAZ was associated with decreased risk of in-hospital death in children with SM across the two sites (OR [95% CI] = 0.70 [0.51, 0.95], p=0.02), with no significant interaction between WAZ and site. Baseline HAZ and WHZ were not significantly associated with in-hospital mortality (OR [95% CI]) = 0.84 [0.66, 1.06] and 0.77 [0.57, 1.02], respectively). During the post-discharge period, 23 (4.4%) children with SM and 1 (0.9%) CC died prior to 12-month follow-up. Nutritional marker z-scores were not significantly associated with risk of post-discharge mortality in children with SM, overall and by site. However, children in Kampala who were underweight had increased odds of post-discharge mortality compared to those who were normal weight (OR [95% CI] = 4.18 [1.36, 12.84], p=0.01). Among those who survived in Kampala, higher WAZ was associated with increased risk of returning to clinic for any cause within 12-month follow-up (HR [95% CI] = 1.16 [1.06, 1.28], p=0.002), but was not significant for malaria sick visits or readmission. HAZ and WHZ in Kampala and all nutritional markers in Jinja were not significantly associated with return sick visits or readmission. Conclusion: Underweight and stunting were worse in both sites among children with SM versus the controls at 1 month, and both of these nutritional parameters normalized by 12 months. In Kampala, low WAZ was associated with worse mortality outcomes after discharge, while high WAZ was associated with repeat clinic visits. In both sites, high WAZ was protective against in-hospital mortality. Chronic malnutrition and SM remain severe risk factors for mortality in Uganda. Weight status was found to have the most significant impact on mortality outcomes. The high incidence of mortality among children <5 with SM requires urgent intervention, and nutrition programs should be aimed at increasing weight, especially in the early months of disease.