Papers by Jonathan Stiles
International Journal of Environmental Research and Public Health
The Research Centers in Minority Institutions (RCMI) Program was congressionally mandated in 1985... more The Research Centers in Minority Institutions (RCMI) Program was congressionally mandated in 1985 to build research capacity at institutions that currently and historically recruit, train, and award doctorate degrees in the health professions and health-related sciences, primarily to individuals from underrepresented and minority populations. RCMI grantees share similar infrastructure needs and institutional goals. Of particular importance is the professional development of multidisciplinary teams of academic and community scholars (the “workforce”) and the harnessing of the heterogeneity of thought (the “thinkforce”) to reduce health disparities. The purpose of this report is to summarize the presentations and discussion at the RCMI Investigator Development Core (IDC) Workshop, held in conjunction with the RCMI Program National Conference in Bethesda, Maryland, in December 2019. The RCMI IDC Directors provided information about their professional development activities and Pilot Pr...
The American Journal of Tropical Medicine and Hygiene
In malaria endemic countries, anemia in pregnant women occurs as a result of erythrocyte destruct... more In malaria endemic countries, anemia in pregnant women occurs as a result of erythrocyte destruction by Plasmodium infections and other causes including malnutrition. Iron supplementation is recommended as treatment of iron-deficiency anemia. Erythrocyte destruction results in increased release of cytotoxic free heme that is scavenged by haptoglobin (Hp), hemopexin (Hx) and heme oxygenase-1 (HO-1). Paradoxically, iron supplementation in pregnant women has been reported to enhance parasitemia and increase levels of free heme. The relationship between free heme, heme scavengers, and birth outcomes has not been investigated, especially in women who are on iron supplementation. We hypothesized that parasite-infected pregnant women on routine iron supplementation have elevated heme and altered expression of heme scavengers. A cross-sectional study was conducted to determine the association between plasma levels of free heme, HO-1, Hp, Hx, and malaria status in pregnant women who received...
Blood
BACKGROUND: Vasculogenesis is critically important to restoring and maintaining vascular homeosta... more BACKGROUND: Vasculogenesis is critically important to restoring and maintaining vascular homeostasis in patients who have sickle cell disease. Emerging evidence indicates vasculo-angiogenesis is a complex process involving recruitment of endothelial progenitor cells (EPCs) from the bone marrow and homing of EPCs to sites of vascular injury. Both recruitment and homing of EPCs are intimately regulated by cytokines and growth factors that are released in response to vascular insult. Hitherto, the phenotype of growth factors and cytokines intimately involved in EPC recruitment and homing in patients who have sickle cell disease remains poorly understood. METHODS: A total of 50 children aged 6–18 years were studied, 30 with Hemoglobin SS, including 11 on chronic red blood cell transfusions, and 20 with normal hemoglobin. We measured plasma concentrations of angiogenesis growth factors/cytokines using a multiplex assay, which permitted analysis of nine factors concurrently, and determine...
Frontiers in Genetics
Background: Cerebral malaria (CM) is characterized by the sequestration of Plasmodium-infected er... more Background: Cerebral malaria (CM) is characterized by the sequestration of Plasmodium-infected erythrocytes (pRBCs) to host brain microvasculature beds via P. falciparum erythrocyte membrane protein 1 (PfEMP1). Under normal conditions, activated protein C (APC) bound to endothelial protein C receptor (EPCR) has cytoprotective properties via the activation of protease-activated receptor 1 (PAR1). During malaria infection, pRBCs transports PfEMP1 to the membranes to bind EPCR in the same region as APC. As a result, APC is less capable of inducing cytoprotective effects via PAR1. Two studies involving adult malaria patients revealed that EPCR rs867186-GG allele is associated with protection against severe malaria, while three other studies involving child malaria patients could not show association between EPCR rs867186-GG genotype and severe malaria or increased mortality among children with CM. Methods: We examined the association between the EPCR rs867186-GG genotype and the protection against cerebral malaria. Peripheral blood samples were collected from 47 malaria patients and 34 healthy individuals from a study conducted from 2004 to 2007 at the NSCB Medical College Hospital in India. CM and malaria-associated complications were defined based on WHO criteria. Genomic DNA was isolated from the peripheral blood mononuclear cells. Primer sequences were designed to contain rs867186 of the PROCR gene (NM 006404) and were used to amplify a 660 bp product as described before. PCR products were purified, and DNA sequences were determined by Sanger Sequencing (Genewiz, NJ). Nonparametric tests were used to compare the groups. To analyze differences in allele frequencies, we used chi-squared or Fisher's exact tests for categorical variables if the expected values were less than 5. P-value <0.05 was considered statistically significant. Results: Our results showed significantly higher rates of AG and GG genotypes in CM patients compared to mild malaria (P = 0.0034). Conclusion: Our results indicate that rs867186-GG or rs867186-AG genotypes are not associated with protection against HCM.
Blood
In Africa, the natural history of SCD is often assumed to be same to the African Diaspora in the ... more In Africa, the natural history of SCD is often assumed to be same to the African Diaspora in the US, Jamaica, Europe or Latin America. Yet the environment can be different, including different pathogen exposure, such as malaria. To help better understand this, over 2000 references were identified using the names of all current or past names of African continent countries and the truncated word sickl$, followed by secondary nested and cross reference searches. Six cases series describing causes of death were identified, representing 182 children (Ndugwa, 1973, Athale, 1994, Koko, 1998, Diagne, 2000, Rahimy, 2003, Van-Dunem, 2007). Gender was reported in 172, 73 were female (42%). Age was reported in 118, 52 were < 5 years (44%). Four studies described some impediment to care or arrival for care in extremis in1/4 to over ½ of patients that died. In Uganda, 9/12 (75%) patient died at home. In Gabon 6/23 (26%) patients died within 4 hours of reaching the hospital and 11/23 (48%) with...
Blood
2123 Little is known about the relative rate of pubertal development among children with differen... more 2123 Little is known about the relative rate of pubertal development among children with different phenotypes of sickle cell disease (SCD). This study proposes, for the first time, to compare the influence of SCD phenotypes on pubertal development (PD) and body mass. We hypothesized that differences in pubertal development and body mass index (BMI) are modulated by SCD phenotype and treatment modality. We therefore conducted a cross-sectional study of SCD children and adolescents aged 8 – 18 years old (yo) to determine the impact of SCD phenotype and treatments on pubertal development (according to sexual maturity rating by Tanner stages, TS) and BMI. Participants were recruited from…
BMJ Global Health
BackgroundMalaria mortality is associated with exaggerated host responses to inflammatory factors... more BackgroundMalaria mortality is associated with exaggerated host responses to inflammatory factors such as C-X-C motif chemokine 10 (CXCL10) and host biomarkers such as angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2). The aim of this study was to determine saliva levels of CXCL10, Ang-1 and Ang-2 and compare with plasma levels regarding their potential as biomarkers of malaria, which may be useful for further development of highly efficient non-invasive malaria detection methods.MethodsCase control study involving 213 subjects (119 with and 94 without malaria) aged 1–16 years. Haematological determination was done using Haematology Analyser. Plasmodium Lactate Dehydrogenase/Histidine Rich Protein-2 (pLDH/HRP-2) Antigen rapid diagnostic test (RDT) were performed. Plasma and saliva levels of CXCL10, Ang-1 and Ang-2 were measured using Elisa kit. Data was presented as mean ±standard error or median and interquartile range (IQR). A p-value<0.001 was considered statistically signific...
The American Journal of Tropical Medicine and Hygiene
Capacity building in low-and middle-income country (LMIC) institutions hinges on the delivery of ... more Capacity building in low-and middle-income country (LMIC) institutions hinges on the delivery of effective mentorship. This study presents an overview of mentorship toolkits applicable to LMIC institutions identified through a scoping review. A scoping review approach was used to 1) map the extent, range, and nature of mentorship resources and tools available and 2) to identify knowledge gaps in the current literature. To identify toolkits, we collected and analyzed data provided online that met the following criteria: written in English and from organizations and individuals involved in global health mentoring. We searched electronic databases, including PubMed, Web of Science, and Google Scholar, and Google search engine. Once toolkits were identified, we extracted the available tools and mapped them to preidentified global health competencies. Only three of the 18 identified toolkits were developed specifically for the LMIC context. Most toolkits focused on individual mentor-mentee relationships. Most focused on the domains of communication and professional development. Fewer toolkits focused on ethics, overcoming resource limitations, and fostering institutional change. No toolkits discussed strategies for group mentoring or how to adapt existing tools to a local context. There is a paucity of mentoring resources specifically designed for LMIC settings. We identified several toolkits that focus on aspects of individual mentor-mentee relationships that could be adapted to local contexts. Future work should focus on adaptation and the development of tools to support institutional change and capacity building for mentoring.
International Journal of Environmental Research and Public Health
Junior investigators often have limited access to networks of scientific experts and resources th... more Junior investigators often have limited access to networks of scientific experts and resources that facilitate competitive grant submissions. Since environments in which scientists are trained are critically important for long-term success, we built and tested a virtual environment for early-stage investigators (ESIs) working on grant proposals. The aim of this study was to evaluate the virtual community’s influence on grant submission patterns among participants from underrepresented groups. As part of a grant writing coaching model, junior investigators were recruited into a professional development program designed to develop competitive grantsmanship skills. Designed by the Research Resources and Outreach Core (RROC) of the National Research Mentoring Network (NRMN), the Health Equity Learning Collaboratory (EQ-Collaboratory) provided a virtual community for social support, accountability, constructive feedback, and access to peer networks to help investigators overcome barriers...
Journal of neuroinflammation, Jan 10, 2018
Human cerebral malaria (HCM) is a severe form of malaria characterized by sequestration of infect... more Human cerebral malaria (HCM) is a severe form of malaria characterized by sequestration of infected erythrocytes (IRBCs) in brain microvessels, increased levels of circulating free heme and pro-inflammatory cytokines and chemokines, brain swelling, vascular dysfunction, coma, and increased mortality. Neuregulin-1β (NRG-1) encoded by the gene NRG1, is a member of a family of polypeptide growth factors required for normal development of the nervous system and the heart. Utilizing an experimental cerebral malaria (ECM) model (Plasmodium berghei ANKA in C57BL/6), we reported that NRG-1 played a cytoprotective role in ECM and that circulating levels were inversely correlated with ECM severity. Intravenous infusion of NRG-1 reduced ECM mortality in mice by promoting a robust anti-inflammatory response coupled with reduction in accumulation of IRBCs in microvessels and reduced tissue damage. In the current study, we examined how NRG-1 treatment attenuates pathogenesis and mortality associa...
BMC proceedings, 2017
Effective mentorship is critical to the success of early stage investigators, and has been linked... more Effective mentorship is critical to the success of early stage investigators, and has been linked to enhanced mentee productivity, self-efficacy, and career satisfaction. The mission of the National Research Mentoring Network (NRMN) is to provide all trainees across the biomedical, behavioral, clinical, and social sciences with evidence-based mentorship and professional development programming that emphasizes the benefits and challenges of diversity, inclusivity, and culture within mentoring relationships, and more broadly the research workforce. The purpose of this paper is to describe the structure and activities of NRMN. NRMN serves as a national training hub for mentors and mentees striving to improve their relationships by better aligning expectations, promoting professional development, maintaining effective communication, addressing equity and inclusion, assessing understanding, fostering independence, and cultivating ethical behavior. Training is offered in-person at institu...
PeerJ, 2017
Chronic inflammation is a characteristic of sickle cell disease (SCD), and is invariably associat... more Chronic inflammation is a characteristic of sickle cell disease (SCD), and is invariably associated with vascular endothelial injury. Hydroxyurea (HU), a naturally cytotoxic chemotherapeutic agent, is the only FDA drug approved for SCD, and is therefore naturally cytotoxic. Quercetin (QCT) is a dietary flavonoid found ubiquitously in plants and foods that have anti-oxidative and anti-inflammatory characteristics. Our hypothesis is that dietary QCT will decrease cytotoxic effects of lipopolysaccharide (LPS) and HU induced vascular cell damage. Lipopolysaccharide (LPS) was used to induce inflammation in immortalized mouse aortic endothelial cells (iMAECs), providing an in vitro model of inflamed endothelial cells. The cells were exposed to LPS throughout the entire experiment. Interventions included treating the LPS exposed cells with QCT, HU, or QCT + HU over 50 hours. The 50-hour period included 24 hours of varying treatments, followed by two hours of hypoxic exposure and then 24 ho...
SOJ microbiology & infectious diseases, 2016
Iron supplementation is recommended for pregnant women to meet their iron requirement for a healt... more Iron supplementation is recommended for pregnant women to meet their iron requirement for a healthy pregnancy. The benefits and risks of universal iron supplementation during pregnancy in malaria endemic countries are currently being debated. As part of a broader study that focused on the effect of heme/HO-1 on pregnancy outcomes in malaria in pregnancy, we determined the association between iron supplementation and free heme levels in blood of pregnant women with and without malaria in Ghana. We hypothesized that pregnant women with malaria who took iron supplements will have higher levels of Heme/HO-1 than those who did not take iron supplements. A total of 337 women were recruited for this study. Blood samples were collected for malaria diagnosis and heme/HO-1 measurement. Quantification of heme was done using a heme colorimetric assay kit and HO-1 levels were performed using Enzyme-Linked Immunosorbent Assay (ELISA) on plasma samples. Malaria positive iron supplemented women, in...
Scientific Reports, 2016
Placental malaria (PM) is a complication associated with malaria infection during pregnancy that ... more Placental malaria (PM) is a complication associated with malaria infection during pregnancy that often leads to abortion, premature delivery, intrauterine growth restriction and low birth weight. Increased levels of circulating free heme, a by-product of Plasmodium-damaged erythrocytes, is a major contributor to inflammation, tissue damage and loss of blood brain barrier integrity associated with fatal experimental cerebral malaria. However, the role of heme in PM remains unknown. Proliferation and apoptosis of trophoblasts and fusion of the mononucleated state to the syncytial state are of major importance to a successful pregnancy. In the present study, we examined the effects of heme on the viability and fusion of a trophoblast-derived cell line (BeWo). Results indicate that heme induces apoptosis in BeWo cells by activation of the STAT3/caspase-3/PARP signaling pathway. In the presence of forskolin, which triggers trophoblast fusion, heme inhibits BeWo cell fusion through activation of STAT3. Understanding the effects of free plasma heme in pregnant women either due to malaria, sickle cell disease or other hemolytic diseases, will enable identification of high-risk women and may lead to discovery of new drug targets against associated adverse pregnancy outcome.
The American Journal of Tropical Medicine and Hygiene, May 1, 2008
Journal of tropical pediatrics, Dec 17, 2016
Scarce studies have addressed hematological differences of malaria in urban and rural regions. Fu... more Scarce studies have addressed hematological differences of malaria in urban and rural regions. Full or complete blood cell counts from 46 and 75 individuals (age range from < 1 to 92 years) with uncomplicated malaria infection living in urban (Accra) and rural (Dodowa) Ghana, respectively, were assessed. Sickle cell trait and patients were excluded from the study. Between overall groups, patients from Accra had significantly lower parasite count (p < 0.0001) and granulocyte number (p = 0.026). Children in Accra had a significantly lower parasitemia (p = 0.0013), hemoglobin (p = 0.0254), platelet count (p = 0.0148) and red blood cell levels (p = 0.0080) when compared with the children of Dodowa. In adults, mean cell hemoglobin (p = 0.0086) and parasite count (p < 0.0001) were significantly higher in Dodowa. These results indicate that children living in urban setting may experience a greater anemic effect to malaria as compared with those living in a rural setting.
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Papers by Jonathan Stiles