The druggable antimalarial target PfDXR : overproduction strategies and kinetic characterization

Plasmodium falciparum 1–deoxy–D–xylulose–5–phosphate reductoisomerase (PfDXR) is a key enzyme in the synthesis of isoprenoids in the malaria parasite, using a pathway that is absent in the human host. This enzyme is receiving attention as it has been validated as a promising drug target. However, an impediment to the characterisation of this enzyme has been the inability to obtain sufficient quantities of the enzyme in a soluble and functional form. The expression of PfDXR from the codon harmonised coding region, under conditions of strongly controlled transcription and induction, resulted in a yield of 2 – 4 mg/L of enzyme, which is 8 to 10–fold higher than previously reported yields. The kinetic parameters Km, Vmax and kcat were determined for PfDXR using an NADPH–dependent assay. Residues K295 and K297, unique to species of Plasmodium and located in the catalytic hatch region; and residues V114 and N115, essential for NADPH binding, were mutated to resemble those found in E. coli DXR. Interestingly, these mutations decreased the substrate affinity of PfDXR to values resembling that of E. coli DXR. PfDXR-K295N, K297S and PfDXR-V114A, N115G demonstrated a decreased ability to turnover substrate by 4–fold and 2-fold respectively in comparison to PfDXR. This study indicates a difference in the role of the catalytic hatch in capturing substrate by species of Plasmodium. The results of this study could contribute to the development of inhibitors of PfDXR.National Research Foundation Grant awarded to AB (Thuthuka Programme) and a SAMI Grant awarded to GLB. LSS was awarded a post–doctoral bursary by the South African Malaria Initiative programme; JG was awarded a PhD bursary by SAMI and National Research Foundation and HJ was awarded an Honours bursary by Rhodes University.http://www.eurekaselect.com/628/journal/protein-amp-peptide-lettershb201

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

In Silico analysis of malaria parasite databanks for specific genes and motifs associated with immune evasion

In Silica analysis of available biological data is a powerful tool for not only the identification of new genes, but also to study evolutionary relationships and regulatory mechanisms. In this study, a number of bioinformatic tools and techniques were applied on the available sequence data of the malaria parasite, Plasmodium falciparum. In Silica techniques were used for the identification of a genomic sequence tag (GST) matching the facilitated glucose transporter family as assessed by BLAST. The open reading frame encoding the fUll-length glucose transporter gene was subsequently assembled from contig sequences of chromosome 2 of the malaria parasite. The frequency of occurrence of di-, tri- and tetranucleotide sequences in both the coding and non-coding regions of chromosome 2 of P. falciparum was also exhaustively analysed. The relative abundance (observed, compared to expected values) of these oligonucleotide sequences, normalised for the nucleotide base composition, was calculated as an odds ratio and compared to those of other organisms. These relative abundancies are referred to as the organism's genomic signature. The CC•GG and CG-dinucleotides exhibited the highest and the lowest odds ratios, respectively. These genome signatures were shown to be constrained by the codon preference and amino acid abundancies. A number of genes with genomic signatures differing significantly from the average signature were also identified and were deduced to be acquired by lateral transfer from unidentified sources. A definite association between interspaced TGCA tetranucleotides and polymorphic traits of the FC27 allele of merozoite surface antigen 2 (MSA-2) was shown. The observed switching and deletion of a limited number of identical nucleotide sequences of several alleles interspersed between direct repeats, provided clues to potential mechanisms employed by the parasite to affect antigenic polymorphism. The identification of a number of motifs for intragenic (homologous) recombination led us to propose a mechanism by which the parasite achieves antigenic variation in single copy genes. These results have profound implications for the design of candidate anti-malarial vaccines, microsatellite typing and characterisation of proteins mediating these recombination events.Dissertation (MSc (Biochemistry))--University of Pretoria, 2001.Biochemistryunrestricte

Profile of rape victims referred by the court to the Free State Psychiatric Complex, 2003 - 2009

Background. The psychological evaluation of rape victims to determine their competency to testify in court and whether they are capable of consenting to sexual intercourse is challenging, especially when the rape victim is mentally retarded. Objective. To describe the profile of mentally retarded rape victims referred to the Free State Psychiatric Complex (FSPC) in Bloemfontein from 2003 to 2009. Methods. A descriptive retrospective study was conducted. The study consisted of 137 rape victims referred by the court to the FSPC for psychological evaluation from 2003 to 2009. Patient files were used to obtain information. Results. The majority of individuals (n=129; 94.2%) in the cohort were female. The mean age of the participants was 19 years (range 3 - 52). The number of victims evaluated increased from four in 2003 to 36 in 2009. Most participants were diagnosed with moderate (67.2%), followed by severe (18.3%) and mild (14.6%) mental retardation. Only two of the victims were able to give legal consent to sexual intercourse. Only one participant was able to testify in a court of law. A noteworthy finding was that in only 25 (18.2%) cases, a clinical psychologist was subpoenaed to testify in court. Conclusion. The vast majority of mentally retarded rape victims in our cohort, regardless of their level of intellectual functioning, were not able to testify in court and were not able to give informed consent to sexual intercourse

The Druggable Antimalarial Target PfDXR: Overproduction Strategies and Kinetic Characterization

Plasmodium falciparum 1–deoxy–D–xylulose–5–phosphate reductoisomerase (PfDXR) is a key enzyme in the synthesis of isoprenoids in the malaria parasite, using a pathway that is absent in the human host. This enzyme is receiving attention as it has been validated as a promising drug target. However, an impediment to the characterisation of this enzyme has been the inability to obtain sufficient quantities of the enzyme in a soluble and functional form. The expression of PfDXR from the codon harmonised coding region, under conditions of strongly controlled transcription and induction, resulted in a yield of 2 – 4 mg/L of enzyme, which is 8 to 10–fold higher than previously reported yields. The kinetic parameters Km, Vmax and kcat were determined for PfDXR using an NADPH–dependent assay. Residues K295 and K297, unique to species of Plasmodium and located in the catalytic hatch region; and residues V114 and N115, essential for NADPH binding, were mutated to resemble those found in E. coli DXR. Interestingly, these mutations decreased the substrate affinity of PfDXR to values resembling that of E. coli DXR. PfDXR-K295N, K297S and PfDXR-V114A, N115G demonstrated a decreased ability to turnover substrate by 4–fold and 2-fold respectively in comparison to PfDXR. This study indicates a difference in the role of the catalytic hatch in capturing substrate by species of Plasmodium. The results of this study could contribute to the development of inhibitors of PfDXR.National Research Foundation Grant awarded to AB (Thuthuka Programme) and a SAMI Grant awarded to GLB. LSS was awarded a post–doctoral bursary by the South African Malaria Initiative programme; JG was awarded a PhD bursary by SAMI and National Research Foundation and HJ was awarded an Honours bursary by Rhodes University.http://www.eurekaselect.com/628/journal/protein-amp-peptide-lettershb201

Theology and higher education: The place of a Faculty of Theology at a South African university

In 2017, the Faculty of Theology celebrates its centenary at the University of Pretoria. Celebrating a centennial is as much as looking back as looking forward. In a changing world with changing paradigms how does one remain relevant? Different challenges and expectations presented to tertiary institutions of education in a new dispensation puts all concerned with higher education in South Africa under pressure. The question addressed in this article is how will a Faculty of Theology (in this case at the University of Pretoria) remain relevant to such an extent that it is continued to be viewed as desirable to have such a faculty present at a university, participating in the academic process and simultaneously continues to contribute to the well-being of the South African society. The author suggests the following guidelines for consideration. In order to remain relevant for the next couple of hundred years the Faculty of Theology should engage contextually with society, practise interdisciplinary Theology, engage in interreligious dialogue while still remaining connected to faith communities. A paradigm of post-foundationalism enables Theology to exercise Theology in a relevant and meaningful manner

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background: Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods: We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5-19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For school-aged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings: From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation: The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity. Funding: UK Medical Research Council, UK Research and Innovation (Research England), UK Research and Innovation (Innovate UK), and European Union