Development of Trypanosoma cruzi in vitro assays to identify compounds suitable for progression in Chagas’ disease drug discovery

Chagas' disease is responsible for significant mortality and morbidity in Latin America. Current treatments display variable efficacy and have adverse side effects, hence more effective, better tolerated drugs are needed. However, recent efforts have proved unsuccessful with failure of the ergosterol biosynthesis inhibitor posaconazole in phase II clinical trials despite promising in vitro and in vivo studies. The lack of translation between laboratory experiments and clinical outcome is a major issue for further drug discovery efforts. Our goal was to identify cell-based assays that could differentiate current nitro-aromatic drugs nifurtimox and benznidazole from posaconazole. Using a panel of T. cruzi strains including the six major lineages (TcI-VI), we found that strain PAH179 (TcV) was markedly less susceptible to posaconazole in vitro. Determination of parasite doubling and cycling times as well as EdU labelling experiments all indicate that this lack of sensitivity is due to the slow doubling and cycling time of strain PAH179. This is in accordance with ergosterol biosynthesis inhibition by posaconazole leading to critically low ergosterol levels only after multiple rounds of division, and is further supported by the lack of effect of posaconazole on the non-replicative trypomastigote form. A washout experiment with prolonged posaconazole treatment showed that, even for more rapidly replicating strains, this compound cannot clear all parasites, indicative of a heterogeneous parasite population in vitro and potentially the presence of quiescent parasites. Benznidazole in contrast was able to kill all parasites. The work presented here shows clear differentiation between the nitro-aromatic drugs and posaconazole in several assays, and suggests that in vitro there may be clinically relevant heterogeneity in the parasite population that can be revealed in long-term washout experiments. Based on these findings we have adjusted our in vitro screening cascade so that only the most promising compounds are progressed to in vivo experiments

Changes in the socio-demographic patterning of late adolescent health risk behaviours during the 1990s: analysis of two West of Scotland cohort studies

Background: Substance use and sexual risk behaviour affect young people's current and future health and wellbeing in many high-income countries. Our understanding of time-trends in adolescent health-risk behaviour is largely based on routinely collected survey data in school-aged adolescents (aged 15 years or less). Less is known about changes in these behaviours among older adolescents. Methods: We compared two cohorts from the same geographical area (West of Scotland), surveyed in 1990 and 2003, to: describe time-trends in measures of smoking, drinking, illicit drug use, early sexual initiation, number of opposite sex sexual partners and experience of pregnancy at age 18-19 years, both overall and stratified by gender and socioeconomic status (SES); and examine the effect of time-trends on the patterning of behaviours by gender and SES. Our analyses adjust for slight between-cohort age differences since age was positively associated with illicit drug use and pregnancy. Results: Rates of drinking, illicit drug use, early sexual initiation and experience of greater numbers of sexual partners all increased significantly between 1990 and 2003, especially among females, leading to attenuation and, for early sexual initiation, elimination, of gender differences. Most rates increased to a similar extent regardless of SES. However, rates of current smoking decreased only among those from higher SES groups. In addition, increases in 'cannabis-only' were greater among higher SES groups while use of illicit drugs other than cannabis increased more in lower SES groups. Conclusion: Marked increases in female substance use and sexual risk behaviours have implications for the long-term health and wellbeing of young women. More effective preventive measures are needed to reduce risk behaviour uptake throughout adolescence and into early adulthood. Public health strategies should reflect both the widespread prevalence of risk behaviour in young people as well as the particular vulnerability to certain risk behaviours among those from lower SES groups

Interoception across Modalities: On the Relationship between Cardiac Awareness and the Sensitivity for Gastric Functions

The individual sensitivity for ones internal bodily signals (“interoceptive awareness”) has been shown to be of relevance for a broad range of cognitive and affective functions. Interoceptive awareness has been primarily assessed via measuring the sensitivity for ones cardiac signals (“cardiac awareness”) which can be non-invasively measured by heartbeat perception tasks. It is an open question whether cardiac awareness is related to the sensitivity for other bodily, visceral functions. This study investigated the relationship between cardiac awareness and the sensitivity for gastric functions in healthy female persons by using non-invasive methods. Heartbeat perception as a measure for cardiac awareness was assessed by a heartbeat tracking task and gastric sensitivity was assessed by a water load test. Gastric myoelectrical activity was measured by electrogastrography (EGG) and subjective feelings of fullness, valence, arousal and nausea were assessed. The results show that cardiac awareness was inversely correlated with ingested water volume and with normogastric activity after water load. However, persons with good and poor cardiac awareness did not differ in their subjective ratings of fullness, nausea and affective feelings after drinking. This suggests that good heartbeat perceivers ingested less water because they subjectively felt more intense signals of fullness during this lower amount of water intake compared to poor heartbeat perceivers who ingested more water until feeling the same signs of fullness. These findings demonstrate that cardiac awareness is related to greater sensitivity for gastric functions, suggesting that there is a general sensitivity for interoceptive processes across the gastric and cardiac modality

Substance use and dietary practices among students attending alternative high schools: results from a pilot study

<p>Abstract</p> <p>Background</p> <p>Substance use and poor dietary practices are prevalent among adolescents. The purpose of this study was to examine frequency of substance use and associations between cigarette, alcohol and marijuana use and selected dietary practices, such as sugar-sweetened beverages, high-fat foods, fruits and vegetables, and frequency of fast food restaurant use among alternative high school students. Associations between multi-substance use and the same dietary practices were also examined.</p> <p>Methods</p> <p>A convenience sample of adolescents (n = 145; 61% minority, 52% male) attending six alternative high schools in the St Paul/Minneapolis metropolitan area completed baseline surveys. Students were participants in the Team COOL (Controlling Overweight and Obesity for Life) pilot study, a group randomized obesity prevention pilot trial. Mixed model multivariate analyses procedures were used to assess associations of interest.</p> <p>Results</p> <p>Daily cigarette smoking was reported by 36% of students. Cigarette smoking was positively associated with consumption of regular soda (p = 0.019), high-fat foods (p = 0.037), and fast food restaurant use (p = 0.002). Alcohol (p = 0.005) and marijuana use (p = 0.035) were positively associated with high-fat food intake. With increasing numbers of substances, a positive trend was observed in high-fat food intake (p = 0.0003). There were no significant associations between substance use and fruit and vegetable intake.</p> <p>Conclusions</p> <p>Alternative high school students who use individual substances as well as multiple substances may be at high risk of unhealthful dietary practices. Comprehensive health interventions in alternative high schools have the potential of reducing health-compromising behaviors that are prevalent among this group of students. This study adds to the limited research examining substance use and diet among at-risk youth.</p> <p>Trial registration number</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01315743">NCT01315743</a></p

Dietary behaviors related to cancer prevention among pre-adolescents and adolescents: the gap between recommendations and reality

<p>Abstract</p> <p>Background</p> <p>Diet is thought to play an important role in cancer risk. This paper summarizes dietary recommendations for cancer prevention and compares these recommendations to the dietary behaviors of U.S. youth ages 8-18.</p> <p>Methods</p> <p>We identified cancer prevention-related dietary recommendations from key health organizations and assessed dietary consumption patterns among youth using published statistics from the National Health and Nutrition Examination Survey, the national Youth Risk Behavior Survey, and other supplemental sources.</p> <p>Results</p> <p>Cancer prevention guidelines recommend a diet rich in fruits, vegetables, and whole grains, recommend limiting sugary foods and beverages, red and processed meats, sodium, and alcohol, and recommend avoiding foods contaminated with carcinogens. However, youth typically do not meet the daily recommendations for fruit, vegetable, or whole grain consumption and are over-consuming energy-dense, sugary and salty foods.</p> <p>Conclusions</p> <p>A large discrepancy exists between expert recommendations about diet and cancer and actual dietary practices among young people and points to the need for more research to better promote the translation of science into practice. Future research should focus on developing and evaluating policies and interventions at the community, state and national levels for aligning the diets of youth with the evolving scientific evidence regarding cancer prevention.</p

Profile of Central and Effector Memory T Cells in the Progression of Chronic Human Chagas Disease

Chagas disease is a parasitic infection caused by protozoan Trypanosoma cruzi that affects approximately 11 million people in Latin America. The involvement of the host's immune response on the development of severe forms of Chagas disease has not been fully elucidated. Studies on the immune response against T. cruzi infection show that the immunoregulatory mechanisms are necessary to prevent the deleterious effect of excessive immune response stimulation and consequently the fatal outcome of the disease. A recall response against parasite antigens observed in in vitro peripheral blood cell culture clearly demonstrates that memory response is generated during infection. Memory T cells are heterogeneous and differ in both the ability to migrate and exert their effector function. This heterogeneity is reflected in the definition of central (TCM) and effector memory (TEM) T cells. Our results suggest that a balance between regulatory and effectors T cells may be important for the progression and development of the disease. Furthermore, the high percentage of central memory CD4+ T cells in indeterminate patients after stimulation suggests that these cells may modulate host's inflammatory response by controlling cell migration to tissues and their effector role during chronic phase of the disease

Specific Humoral Immunity versus Polyclonal B Cell Activation in Trypanosoma cruzi Infection of Susceptible and Resistant Mice

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects 10–12 million people in Latin America. Patent parasitemia develops during acute disease. During this phase, polyclonal B cell activation has been reported to generate high levels of serum antibody with low parasite specificity, and delayed protective humoral immunity, which is necessary to prevent the host from succumbing to infection. In this manuscript, data show that relatively resistant mice have improved parasite-specific humoral immunity and decreased polyclonal B cell activation compared to susceptible mice. Parasite-specific humoral immunity was associated with differential expansion of B cell subsets and T cells in the spleen, as well as with increased Th1 and decreased Th2 cytokine production. These data suggest that host susceptibility/genetic biases impact the development of humoral responses to infection. Th2 cytokines are generally associated with improved antibody responses. In the context of T. cruzi infection of susceptible mice, Th2 cytokines were associated with increased total antibody production concomitant with delayed pathogen-specific humoral immunity. This study highlights the need to consider the effect of host biases when investigating humoral immunity to any pathogen that has reported polyclonal B cell activation during infection