Publications by authors named "M F Nicol"

Despite advancements in existing antiretroviral-based prevention strategies, including daily oral, locally acting, and injectable options, there is a pressing need for more inclusive and flexible event-driven pre-exposure prophylaxis (PrEP) strategies for all. Event-driven or intermittent dosing of PrEP in populations beyond cisgender men who have sex with men would offer a promising alternative by fitting prevention into the diverse lifestyles of affected populations and thereby advancing health equity. Evidence from PrEP clinical trials, pharmacokinetic studies, modelling studies, and real-world observational research suggests that event-driven PrEP could be a flexible and inclusive option, yet optimal dosing has not been established across sex and gender spectrums.

View Article and Find Full Text PDF

Background: Centrifuge-free processing methods support stool Xpert Ultra testing for childhood tuberculosis (TB), but there are limited data on their accuracy, acceptability and usability.

Methods: We conducted a prospective evaluation of stool Xpert Ultra in India, South Africa, and Uganda with three methods: Stool Processing Kit (SPK), Simple One-Step (SOS), and Optimized Sucrose Flotation (OSF). Children <15 years old with presumptive TB had respiratory specimen testing with Xpert Ultra and culture.

View Article and Find Full Text PDF

Little is understood about the roles of mitochondria in pregnancy-related adaptations. Therefore, we evaluated associations of maternal early-to-mid pregnancy mitochondrial DNA copy number (mtDNAcn) and mtDNA methylation with birth size and gestational length. Michigan women ( = 396) provided venous bloodspots at median 11 weeks gestation to quantify mtDNAcn marker NADH-ubiquinone oxidoreductase chain 1 () using real-time quantitative PCR and mtDNA methylation at several regions within four mitochondria-specific genes using pyrosequencing: (mitochondrially encoded tRNA phenylalanine), (D-loop promoter region, heavy strand), (cytochrome b), and (D-loop promoter region, light strand).

View Article and Find Full Text PDF

We derive a numerical model representing the emergence and evolution of SARS-CoV-2 variants, informed by data from in-vitro passaging experiments in Vero B4 cells. We compare our numerical simulation results against probabilistic derivations of the expected probability of and time until the fittest variant becomes fixed in the population. Contrary to literature surrounding DNA viruses and eukaryotes where probabilities of fitness extremes are often modelled by exponential decaying tail, we show that above wildtype fitness differences for SARS-CoV-2 are actually best modelled by a heavy-tailed Fréchet distribution.

View Article and Find Full Text PDF
Article Synopsis
  • Children have shown strong immune responses to SARS-CoV-2 during various pandemic waves, with a significant increase in seropositivity from 34.2% after the first wave to 99.2% after the fifth wave, despite experiencing minimal severe illness.
  • The study found that IgG antibodies developed through natural exposure were effective in protecting children from future infections, with varying levels of effectiveness against different variants, showing the highest protection against the Beta variant and the least against Omicron.
  • Maternal seropositivity was linked to higher child seropositivity, indicating that the immune status of mothers plays a crucial role in the immune response of their children against COVID-19.
View Article and Find Full Text PDF