Antigenic variation in vector-borne pathogens.

Several pathogens of humans and domestic animals depend on hematophagous arthropods to transmit them from one vertebrate reservoir host to another and maintain them in an environment. These pathogens use antigenic variation to prolong their circulation in the blood and thus increase the likelihood of transmission. By convergent evolution, bacterial and protozoal vector-borne pathogens have acquired similar genetic mechanisms for successful antigenic variation. Borrelia spp. and Anaplasma marginale (among bacteria) and African trypanosomes, Plasmodium falciparum, and Babesia bovis (among parasites) are examples of pathogens using these mechanisms. Antigenic variation poses a challenge in the development of vaccines against vector-borne pathogens

Forced and self-excited oscillations of an optomechanical cavity

We experimentally study forced and self oscillations of an optomechanical cavity which is formed between a fiber Bragg grating that serves as a static mirror and between a freely suspended metallic mechanical resonator that serves as a moving mirror. In the domain of small amplitude mechanical oscillations, we find that the optomechanical coupling is manifested as changes in the effective resonance frequency, damping rate and cubic nonlinearity of the mechanical resonator. Moreover, self oscillations of the micromechanical mirror are observed above a certain optical power threshold. A comparison between the experimental results and a theoretical model that we have recently presented yields a good agreement. The comparison also indicates that the dominant optomechanical coupling mechanism is the heating of the metallic mirror due to optical absorption.Comment: 11 pages, 6 figure

The Impact of Aging on the Lung Alveolar Environment, Predetermining Susceptibility to Respiratory Infections

Respiratory infections are one of the top causes of death in the elderly population, displaying susceptibility factors with increasing age that are potentially amenable to interventions. We posit that with increasing age there are predictable tissue-specific changes that prevent the immune system from working effectively in the lung. This mini-review highlights recent evidence for altered local tissue environment factors as we age focusing on increased tissue oxidative stress with associated immune cell changes, likely driven by the byproducts of age-associated inflammatory disease. Potential intervention points are presented

The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet’s Perturbations

Potentially habitable planets within the habitable zone of M dwarfs are affected by tidal interaction. We studied tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of dynamical evolution, focusing on the effects of a rheological treatment, different compositions and the inclusion of orbital perturbations on the spin-down time and the probability of becoming trapped in a low spin-orbit resonance. The composition has a noticeable effect on the spin-down time, which changes, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time required to reach a low resonance value (3:2) for a configuration of six planets. Capture probabilities are affected when assuming different compositions and eccentricity variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and no effect on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.Facultad de Ciencias Astronómicas y Geofísica

COVID-19 and chronic diabetes: The perfect storm for reactivation TB?

Background: The Coronavirus disease 2019 (COVID-19) pandemic is predicted to have a net negative effect on tuberculosis (TB) control, with an estimated excess of 6.3 million tuberculosis cases and 1.4 million deaths by 2025. Programmatic issues like the lockdown of TB services affect all patients, while biosocial factors have a differential impact on an individual’s risk for TB or adverse TB outcomes. Case presentation: We report three cases of incident TB after resolution of COVID-19 episodes.Coincidently, all cases shared a common risk factor: a chronic history poorly-controlled diabetes. Conclusions: Our findings alert to the threat posed by the synergy between COVID-19 and diabetes, on TB reactivation. In medium- to high-risk settings for TB, we recommend implementation of routine screening for latent TB infection in these cases, and preventive TB treatment in those who are positive. Published version of this presentation: Aguillón-Durán, G.P., Prieto-Martínez, E., Ayala, D. et al. COVID-19 and chronic diabetes: the perfect storm for reactivation tuberculosis?: a case series. J Med Case Reports 15, 621 (2021). https://doi.org/10.1186/s13256-021-03193-

Performance of color plates for M. tuberculosis detection and drug resistance screening in Mexican TB clinics across the Texas border

Purpose: Populations along the U.S.-Mexico border have a high prevalence of risk factors for TB such as low socioeconomic status, overcrowding and migration, and consequently, higher TB incidence (up to 12 and 44/100,000) when compared to their corresponding national averages in each country. TB control in border regions is further challenged by limited access to cost-effective tests to diagnose TB and assess drug resistance (DR). We evaluated the performance of a novel, simple and low-cost culture plate technology for isolation and DR testing of Mtb in TB clinics on the Mexican border with Texas. Methods: We conducted an observational study using sputum from 85 subjects with possible TB identified in TB clinics in Reynosa and Matamoros, Mexico. Their fresh sputa were prospectively digested and decontaminated using standard NaOH-NALC and evaluated for acid-fast bacilli (AFB) in smears or Mtb growth in LJ slants (routine). For the experimental arm we inoculated 1st , 2nd or 3rd generation plates (1, 2 or 3G plates) with thawed leftover sputa already treated with NaOH-NALC or fresh sputa treated with a described mix of salts for digestion and decontamination. The performance of both culture methods was compared for Mtb isolation. The 1G plates were previously validated for assessment of drug resistance, and hence, used here to identify resistance to isoniazid (INH) or rifampicin (RIF). Results: The plates had a 100% sensitivity and \u3e90% PPV when compared to AFB smears or LJ cultures. Contamination was 1.4% for plates and 12.7% for LJ cultures. Median time-to-positive was 17 days for plates and 63 days for LJ. Resistance per 1G plates was 17.6% to any drug, 14.9% to INH, 9.5% to RIF, and 6.8% to both combined (multi-drug resistant TB). Conclusions. The plates were as sensitive as reference methods, had less contamination and shorter times for Mtb growth detection. The 1G plate costs less than $5US and provides DR results for three drugs, when compared to local costs of$100 for single RIF-resistance testing with GeneXpert. DR is likely underestimated in the Mexican border clinics where official estimates are ~6% and our findings suggest 3-fold higher rates. Implementation studies for the plates are warranted in Mexican border clinics and other TB endemic regions worldwide where resources are limited

Tuberculosis Phenotypic and Genotypic Drug Susceptibility Testing and Immunodiagnostics: A Review

Tuberculosis (TB), considered an ancient disease, is still killing one person every 21 seconds. Diagnosis of Mycobacterium tuberculosis (M.tb) still has many challenges, especially in low and middle-income countries with high burden disease rates. Over the last two decades, the amount of drug-resistant (DR)-TB cases has been increasing, from mono-resistant (mainly for isoniazid or rifampicin resistance) to extremely drug resistant TB. DR-TB is problematic to diagnose and treat, and thus, needs more resources to manage it. Together with+ TB clinical symptoms, phenotypic and genotypic diagnosis of TB includes a series of tests that can be used on different specimens to determine if a person has TB, as well as if the M.tb strain+ causing the disease is drug susceptible or resistant. Here, we review and discuss advantages and disadvantages of phenotypic vs. genotypic drug susceptibility testing for DR-TB, advances in TB immunodiagnostics, and propose a call to improve deployable and low-cost TB diagnostic tests to control the DR-TB burden, especially in light of the increase of the global burden of bacterial antimicrobial resistance, and the potentially long term impact of the coronavirus disease 2019 (COVID-19) disruption on TB programs

Diabetes screen during tuberculosis contact investigations highlights opportunity for new diabetes diagnosis and reveals metabolic differences between ethnic groups

Type 2 diabetes (T2D) is a prevalent risk factor for tuberculosis (TB), but most studies on TB-T2D have focused on TB patients, been limited to one community, and shown a variable impact of T2D on TB risk or treatment outcomes. We conducted a cross-sectional assessment of sociodemographic and metabolic factors in adult TB contacts with T2D (versus no T2D), from the Texas-Mexico border to study Hispanics, and in Cape Town to study South African Coloured ethnicities. The prevalence of T2D was 30.2% in Texas-Mexico and 17.4% in South Africa, with new diagnosis in 34.4% and 43.9%, respectively. Contacts with T2D differed between ethnicities, with higher smoking, hormonal contraceptive use and cholesterol levels in South Africa, and higher obesity in Texas-Mexico (p \u3c 0.05). PCA analysis revealed striking differences between ethnicities in the relationships between factors defining T2D and dyslipidemias. Our findings suggest that screening for new T2D in adult TB contacts is effective to identify new T2D patients at risk for TB. Furthermore, studies aimed at predicting individual TB risk in T2D patients, should take into account the heterogeneity in dyslipidemias that are likely to modify the estimates of TB risk or adverse treatment outcomes that are generally attributed to T2D alone

Effects Of Length, Complexity, And Grammatical Correctness On Stuttering In Spanish-Speaking Preschool Children

Purpose: To explore the effects of utterance length, syntactic complexity, and grammatical correctness on stuttering in the spontaneous speech of young, monolingual Spanish-speaking children. Method: Spontaneous speech samples of 11 monolingual Spanish-speaking children who stuttered, ages 35 to 70 months, were examined. Mean number of syllables, total number of clauses, utterance complexity (i.e., containing no clauses, simple clauses, or subordinate and/or conjoined clauses), and grammatical correctness (i.e., the presence or absence of morphological and syntactical errors) in stuttered and fluent utterances were compared. Results: Findings revealed that stuttered utterances in Spanish tended to be longer and more often grammatically incorrect, and contain more clauses, including more subordinate and/or conjoined clauses. However, when controlling for the interrelatedness of syllable number and clause number and complexity, only utterance length and grammatical incorrectness were significant predictors of stuttering in the spontaneous speech of these Spanish-speaking children. Use of complex utterances did not appear to contribute to the prediction of stuttering when controlling for utterance length. Conclusions: Results from the present study were consistent with many earlier reports of English-speaking children. Both length and grammatical factors appear to affect stuttering in Spanish-speaking children. Grammatical errors, however, served as the greatest predictor of stuttering.Communication Sciences and Disorder

Network centrality: an introduction

Centrality is a key property of complex networks that influences the behavior of dynamical processes, like synchronization and epidemic spreading, and can bring important information about the organization of complex systems, like our brain and society. There are many metrics to quantify the node centrality in networks. Here, we review the main centrality measures and discuss their main features and limitations. The influence of network centrality on epidemic spreading and synchronization is also pointed out in this chapter. Moreover, we present the application of centrality measures to understand the function of complex systems, including biological and cortical networks. Finally, we discuss some perspectives and challenges to generalize centrality measures for multilayer and temporal networks.Comment: Book Chapter in "From nonlinear dynamics to complex systems: A Mathematical modeling approach" by Springe