Studies in the processing of a carbonaceous gold ore

Imperial Users onl

Mathematical modeling of bone marrow – peripheral blood dynamics in the disease state based on current emerging paradigms, part II

The cancer stem cell hypothesis has gained currency in recent times but concerns remain about its scientific foundations because of significant gaps that exist between research findings and comprehensive knowledge about cancer stem cells (CSCs). In this light, a mathematical model that considers hematopoietic dynamics in the diseased state of the bone marrow and peripheral blood is proposed and used to address findings about CSCs. The ensuing model, resulting from a modification and refinement of a recent model, develops out of the position that mathematical models of CSC development, that are few at this time, are needed to provide insightful underpinnings for biomedical findings about CSCs as the CSC idea gains traction. Accordingly, the mathematical challenges brought on by the model that mirror general challenges in dealing with nonlinear phenomena are discussed and placed in context. The proposed model describes the logical occurrence of discrete time delays, that by themselves present mathematical challenges, in the evolving cell populations under consideration. Under the challenging circumstances, the steady state properties of the model system of delay differential equations are obtained, analyzed, and the resulting mathematical predictions arising therefrom are interpreted and placed within the framework of findings regarding CSCs. Simulations of the model are carried out by considering various parameter scenarios that reflect different experimental situations involving disease evolution in human hosts. Model analyses and simulations suggest that the emergence of the cancer stem cell population alongside other malignant cells engenders higher dimensions of complexity in the evolution of malignancy in the bone marrow and peripheral blood at the expense of healthy hematopoietic development. The model predicts the evolution of an aberrant environment in which the malignant population particularly in the bone marrow shows tendencies of reaching an uncontrollable equilibrium state. Essentially, the model shows that a structural relationship exists between CSCs and non-stem malignant cells that confers on CSCs the role of temporally enhancing and stimulating the expansion of non-stem malignant cells while also benefitting from increases in their own population and these CSCs may be the main protagonists that drive the ultimate evolution of the uncontrollable equilibrium state of such malignant cells and these may have implications for treatment.Evans Afenya is thankful to Elmhurst College for summer research support. Rachid Ouifki would like to thank the DST/NRF SARChI Chair in Mathematical Models and Methods in Bioengineering and Biosciences for its financial support.http://www.elsevier.com/locate/yjtbi2020-01-07hj2018Mathematics and Applied Mathematic

Co-infections of SARS-CoV-2 with respiratory syncytial virus and human influenza A in patients with symptoms of COVID-19 in Ghana: A retrospective study

Background During the COVID-19 pandemic the aetiology of respiratory illnesses were narrowed to SARS-CoV-2. This prevented diagnosis of other pathogens and patients were not notified of the accurate diagnosis of their illnesses when SARS-CoV-2 was absent. It is therefore important to look back and determine what else was present but was missed. Objective This retrospective study sought to gain insights into prevalence of respiratory syncytial virus (RSV) and influenza A alongside SARS-CoV-2 in patients who reported with clinical symptoms of respiratory illnesses. Methods Samples from patients who had reported of respiratory symptoms were selected at random from a pool. RNA was extracted and RT-PCR was performed for SARS-CoV-2, RSV and Influenza A in parallel. Data on the clinical symptoms was extracted from case-base forms and analysed. Results Of the 400 symptomatic samples tested, prevalence of SARS-CoV-2, influenza A and RSV was 20.3 %, 2.0 % and 0.5 % respectively. Only one sample tested positive for SARS-CoV-2 and influenza A. About 77 % of the symptomatic cases did not test positive for any of the three agents. Cough (79 %) was the most common symptom followed by fever and chills, headache, sore throat and runny nose. Conclusion The large proportion of symptomatic cases that tested negative for all three respiratory viruses raises a flag and a need for more investigations into the actual burden of respiratory aetiologic agents during the pandemic. With the low levels of co-infections, parallel testing may not be needed however, a strong case for multiplex tests for respiratory agents exists

The Impact of Audit Committee Characteristics on Audit Report Time Lag: Evidence From Ghana

The study examines the impact of audit committee characteristics on audit reporting time lag of Ghanaian publicly traded companies. We used the size of the audit committee, gender diversity, and financial expertise  to measure the characteristics of the audit committee as against the number of days between financial year-end date and audit report completion. The study predicted and found a negative relationship between audit committee gender diversity and audit report time lag. Also, a negative association between the audit committee financial expertise and audit report time lag was established. Furthermore,  a negative association was affirmed between audit report time lag and gender diversity of the committee. The study therefore concluded that the audit committee  characteristics leads to audit efficiency indicating that audit committee promotes the prompt delivery of the audit report. As a result, the study suggests that companies consider variegating their audit committee board on these characteristics. Keywords: Audit Committee, Audit report time lag, Board size, financial expertise, Gender diversity. DOI: 10.7176/RJFA/13-4-01 Publication date: February 28th 2022

Hematologic Disorders and Bone Marrow–Peripheral Blood Dynamics

Hematologic disorders such as the myelodysplastic syndromes (MDS) are discussed. The lingering controversies related to various diseases are highlighted. A simple biomathematical model of bone marrow - peripheral blood dynamics in the normal state is proposed and used to investigate cell behavior in normal hematopoiesis from a mathematical viewpoint. Analysis of the steady state and properties of the model are used to make postulations about the phenomenon of massive apoptosis in MDS. Simulations of the model show situations in which homeostatic equilibrium can be achieved and maintained. Consequently, it is postulated that hematopoietic growth factors may possess the capabilities of preventing oscillatory dynamics and enhancing faster evolution towards homeostatic equilibrium

Modelling abnormal granulocytopoiesis and its chemotherapy.

Modelling abnormal granulocytopoiesis and its chemotherapy