Chlamydia trachomatis is a common sexually transmitted infection that is associated with a range of serious reproductive tract sequelae including in women Pelvic Inflammatory Disease (PID), tubal ...factor infertility, and ectopic pregnancy. Ascension of the pathogen beyond the cervix and into the upper reproductive tract is thought to be necessary for these pathologies. However, Chlamydia trachomatis does not encode a mechanism for movement on its genome, and so the processes that facilitate ascension have not been elucidated. Here, we evaluate the factors that may influence chlamydial ascension in women. We constructed a mathematical model based on a set of stochastic dynamics to elucidate the moderating factors that might influence ascension of infections in the first month of an infection. In the simulations conducted from the stochastic model, 36% of infections ascended, but only 9% had more than 1000 bacteria ascend. The results of the simulations indicated that infectious load and the peristaltic contractions moderate ascension and are inter-related in impact. Smaller initial loads were much more likely to ascend. Ascension was found to be dependent on the neutrophil response. Overall, our results indicate that infectious load, menstrual cycle timing, and the neutrophil response are critical factors in chlamydial ascension in women.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, we consider two species competing for a limiting substrate such that each species impedes the growth of the other one (Mutual inhibition) in presence of a virus inhibiting one ...bacterial species. A system of ordinary differential equations is proposed as a mathematical model for this competition. A detailed local qualitative analysis of the system is carried out. We proved that for a general nonlinear growth rates, the Competitive Exclusion Principle still valid, that at least one species goes extinct. For some cases where we have two locally stable equilibrium points, initial species concentrations are important in determining which is the winning species. Obtained results were confirmed by some numerical simulations using Matlab software.
Summary
Naturally occurring populations of bacteria and archaea are vital to life on the earth and are of enormous practical significance in medicine, engineering and agriculture. However, the rules ...governing the formation of such communities are still poorly understood, and there is a need for a usable mathematical description of this process. Typically, microbial community structure is thought to be shaped mainly by deterministic factors such as competition and niche differentiation. Here we show, for a wide range of prokaryotic communities, that the relative abundance and frequency with which different taxa are observed in samples can be explained by a neutral community model (NCM). The NCM, which is a stochastic, birth–death immigration process, does not explicitly represent the deterministic factors and therefore cannot be a complete or literal description of community assembly. However, its success suggests that chance and immigration are important forces in shaping the patterns seen in prokaryotic communities.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this paper, we propose a six-dimensional nonlinear system of differential equations for the human immunodeficiency virus (HIV) including the B-cell functions with a general nonlinear incidence ...rate. The compartment of infected cells was subdivided into three classes representing the latently infected cells, the short-lived productively infected cells, and the long-lived productively infected cells. The basic reproduction number was established, and the local and global stability of the equilibria of the model were studied. A sensitivity analysis with respect to the model parameters was undertaken. Based on this study, an optimal strategy is proposed to decrease the number of infected cells. Finally, some numerical simulations are presented to illustrate the theoretical findings.
Dinoflagellates of the family Symbiodiniaceae form mutualistic symbioses with marine invertebrates such as reef‐building corals, but also inhabit reef environments as free‐living cells. Most coral ...species acquire Symbiodiniaceae horizontally from the surrounding environment during the larval and/or recruitment phase, however the phylogenetic diversity and ecology of free‐living Symbiodiniaceae on coral reefs is largely unknown. We coupled environmental DNA sequencing and genus‐specific qPCR to resolve the community structure and cell abundances of free‐living Symbiodiniaceae in the water column, sediment, and macroalgae and compared these to coral symbionts. Sampling was conducted at two time points, one of which coincided with the annual coral spawning event when recombination between hosts and free‐living Symbiodiniaceae is assumed to be critical. Amplicons of the internal transcribed spacer (ITS2) region were assigned to 12 of the 15 Symbiodiniaceae genera or genera‐equivalent lineages. Community compositions were separated by habitat, with water samples containing a high proportion of sequences corresponding to coral symbionts of the genus Cladocopium, potentially as a result of cell expulsion from in hospite populations. Sediment‐associated Symbiodiniaceae communities were distinct, potentially due to the presence of exclusively free‐living species. Intriguingly, macroalgal surfaces displayed the highest cell abundances of Symbiodiniaceae, suggesting a key role for macroalgae in ensuring the ecological success of corals through maintenance of a continuum between environmental and symbiotic populations of Symbiodiniaceae.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this article, we examine the dynamics of a Chikungunya virus (CHIKV) infection model with two routes of infection. The model uses four categories, namely, uninfected cells, infected cells, the ...CHIKV virus, and antibodies. The equilibrium points of the model, which consist of the free point for the CHIKV and CHIKV endemic point, are first analytically determined. Next, the local stability of the equilibrium points is studied, based on the basic reproduction number (R0) obtained by the next-generation matrix. From the analysis, it is found that the disease-free point is locally asymptotically stable if R0≤1, and the CHIKV endemic point is locally asymptotically stable if R0>1. Using the Lyapunov method, the global stability analysis of the steady-states confirms the local stability results. We then describe our design of an optimal recruitment strategy to minimize the number of infected cells, as well as a nonlinear optimal control problem. Some numerical simulations are provided to visualize the analytical results obtained.
Chronic rhinosinusitis (CRS) is an inflammatory condition that affects up to 12% of the human population in developed countries. Previous studies examining the potential role of the sinus bacterial ...microbiota within CRS infections have found inconsistent results, possibly because of inconsistencies in sampling strategies. The aim of this study was to determine whether the sinus microbiome is altered in CRS and additionally if the middle meatus is a suitable representative site for sampling the sinus microbiome. Swab samples were collected from 12 healthy controls and 21 CRS patients, including all eight sinuses for CRS patients and between one and five sinuses for control subjects. The left and right middle meatus and nostril swabs were also collected. Significant differences in the sinus microbiomes between CRS and control samples were revealed using high-throughput 16S rRNA gene sequencing. The genus
was over-represented in CRS sinuses, and associations between control patients and
and
were also identified. Comparisons of the middle meatuses between groups did not reflect these differences, and the abundance of the genus
was significantly lower at this location. Additionally, intra-patient variation was lower between sinuses than between sinus and middle meatus, which together with the above results suggests that the middle meatus is not an effective representative sampling site.
India has the highest burden of both tuberculosis (TB) and multidrug-resistant TB (MDR-TB) based on the WHO Global TB Report 2019. Although the available data suggest that the total TB incidence has ...declined, the absolute number of new cases is still increasing. The number of reported TB cases in India in 2018 was 2.2 million, which was 1.5 million in 2009. About 47% increment in TB case notification in India within a decade shows a persistent public health problem. India contributes about 22% of the World's TB burden. Indian National Strategic Plan 2017–2025, sets out the government plans to eliminate TB by 2025. However, the milestone seems unrealistic to achieve the TB eradication goal by 2025. We developed a five-dimensional mathematical model to understand the TB dynamics in India and investigate the possibility of the earliest TB eradication time frame. The model stratifies the entire TB class into three different classes as drug-sensitive (DS), MDR, and isolated classes. The effective reproduction number, equilibrium points, and stability analysis of the model were carried out. This model predicts the total estimated cases of DS-TB and MDR-TB from 2018 to 2035 through numerical simulation and suggests that TB may be eliminated by 2035 in India if the treatment success rate could be achieved to 95%, by contact tracing and isolating at least 50% of MDR-TB.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Oxygen (O2) availability is essential for healthy coral reef functioning, yet how continued loss of dissolved O2 via ocean deoxygenation impacts performance of reef building corals remains unclear. ...Here, we examine how intra‐colony spatial geometry of important Great Barrier Reef (GBR) coral species Acropora may influence variation in hypoxic thresholds for upregulation, to better understand capacity to tolerate future reductions in O2 availability. We first evaluate the application of more streamlined models used to parameterise Hypoxia Response Curve data, models that have been used historically to identify variable oxyregulatory capacity. Using closed‐system respirometry to analyse O2 drawdown rate, we show that a two‐parameter model returns similar outputs as previous 12th‐order models for descriptive statistics such as the average oxyregulation capacity (Tpos) and the ambient O2 level at which the coral exerts maximum regulation effort (Pcmax), for diverse Acropora species. Following an experiment to evaluate whether stress induced by coral fragmentation for respirometry affected O2 drawdown rate, we subsequently identify differences in hypoxic response for the interior and exterior colony locations for the species Acropora abrotanoides, Acropora cf. microphthalma and Acropora elseyi. Average regulation capacity across species was greater (0.78–1.03 ± SE 0.08) at the colony interior compared with exterior (0.60–0.85 ± SE 0.08). Moreover, Pcmax occurred at relatively low pO2 of <30% (±1.24; SE) air saturation for all species, across the colony. When compared against ambient O2 availability, these factors corresponded to differences in mean intra‐colony oxyregulation, suggesting that lower variation in dissolved O2 corresponds with higher capacity for oxyregulation. Collectively, our data show that intra‐colony spatial variation affects coral oxyregulation hypoxic thresholds, potentially driving differences in Acropora oxyregulatory capacity.
We examine how intra‐colony spatial variance impacts coral hypoxic thresholds for common reef‐building Acropora species, providing new insights into coral hypoxia response curve analysis and oxyregulation capacity under ocean deoxygenation.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
BAFF (BLyS, TALL-1, THANK, zTNF4) is a member of the TNF superfamily that specifically regulates B lymphocyte proliferation and survival. Mice transgenic (Tg) for BAFF develop an autoimmune condition ...similar to systemic lupus erythematosus. We now demonstrate that BAFF Tg mice, as they age, develop a secondary pathology reminiscent of Sjögren's syndrome (SS), which is manifested by severe sialadenitis, decreased saliva production, and destruction of submaxillary glands. In humans, SS also correlates with elevated levels of circulating BAFF, as well as a dramatic upregulation of BAFF expression in inflamed salivary glands. A likely explanation for disease in BAFF Tg mice is excessive survival signals to autoreactive B cells, possibly as they pass through a critical tolerance checkpoint while maturing in the spleen. The marginal zone (MZ) B cell compartment, one of the enlarged B cell subsets in the spleen of BAFF Tg mice, is a potential reservoir of autoreactive B cells. Interestingly, B cells with an MZ-like phenotype infiltrate the salivary glands of BAFF Tg mice, suggesting that cells of this compartment potentially participate in tissue damage in SS and possibly other autoimmune diseases. We conclude that altered B cell differentiation and tolerance induced by excess BAFF may be central to SS pathogenesis.
PDF
