Niche theory for within-host parasite dynamics: Analogies to food web modules via feedback loops.

Why do parasites exhibit a wide dynamical range within their hosts? For instance, why does infecting dose either lead to infection or immune clearance? Why do some parasites exhibit boom-bust, oscillatory dynamics? What maintains parasite diversity, that is coinfection v single infection due to exclusion or priority effects? For insights on parasite dose, dynamics and diversity governing within-host infection, we turn to niche models. An omnivory food web model (IGP) blueprints one parasite competing with immune cells for host energy (PIE). Similarly, a competition model (keystone predation, KP) mirrors a new coinfection model (2PIE). We then drew analogies between models using feedback loops. The following three points arise: first, like in IGP, parasites oscillate when longer loops through parasites, immune cells and resource regulate parasite growth. Shorter, self-limitation loops (involving resources and enemies) stabilise those oscillations. Second, IGP can produce priority effects that resemble immune clearance. But, despite comparable loop structure, PIE cannot due to constraints imposed by production of immune cells. Third, despite somewhat different loop structure, KP and 2PIE share apparent and resource competition mechanisms that produce coexistence (coinfection) or priority effects of prey or parasites. Together, this mechanistic niche framework for within-host dynamics offers new perspective to improve individual health.

Zygoma Implant-based Rehabilitation of Three Patients with Primary Failure of Eruption of Teeth - A 5-year Follow-up.

Primary failure of eruption (PFE) is a rare non-syndromic condition in which non-ankylosed teeth fail to erupt fully or partially due to malfunction of the eruption mechanism. 3 young patients are presented in this article with features consistent with a diagnosis of primary failure of eruption. The features of this condition are described together with different modalities of treatment planning for such patients. Zygoma implants as a new approach in the treatment of patients with primary failure of eruption requiring full mouth rehabilitation is discussed.