Browsing by Subject "Adherence"

Children and adolescents with sickle cell disease (SCD) are at high risk for medical complications, neuropsychological sequelae, and lower overall quality of life. One target of intervention that can positively impact these outcomes is treatment adherence. Despite the known benefits of treatment adherence for health outcomes, children with SCD encounter several barriers that result in low overall levels of adherence and reduction of treatment benefits. Furthermore, little is known regarding the relationship between adherence and quality of life for this pediatric population. As such, two studies were conducted in order to (a) examine the relationship between treatment adherence and quality of life among youth with SCD, and (b) examine the feasibility, acceptability, and preliminary efficacy of a novel mobile health intervention to improve adherence among youth with SCD. For the first study, 46 children and adolescents with SCD and a caregiver were recruited. Results indicated that participants with good adherence had significantly higher parent-reported quality of life than participants with poor adherence. In contrast, based on child self-report, participants did not differ across quality of life domains. Subsequently, 43 participants were recruited to participate in the pilot intervention study, the Intensive Training Program (ITP). The intervention was conducted in two phases: Phase I recruited participants receiving iron chelation therapy to reduce the risk of iron overload associated with chronic red blood transfusions (n=11); Phase II broadened the scope of participants to those prescribed hydroxyurea (HU; n=32), a once daily oral medication. Results indicated that patients and their caregivers endorsed high levels of acceptance, ease of use, and satisfaction with mobile health technology. In addition, participants encountered several technological issues that limited access and resulted in poor compliance with the ITP for some participants early on in the study. Despite this, participants demonstrated significant increases in medication possession ratio (MPR) based on pharmacy refill as well as sustained improvements in disease knowledge. Adherent participants demonstrated significant decreases in outcomes related to caregiver burden as well as significantly lower pain impact when compared to non-adherent youth. In addition, children who were adherent reported quality of life and overall SCD-related functioning at a clinically-significant higher level when compared to those who were non-adherent. Implications for future research and application to clinical care are discussed.

Kingella kingae is an emerging bacterial pathogen that is being recognized increasingly as an important etiology of septic arthritis, osteomyelitis, and bacteremia, especially in young children. The pathogenesis of K. kingae disease begins with bacterial adherence to respiratory epithelium in the posterior pharynx. Previous work identified type IV pili as a critical factor for adherence to human epithelial cells. However, the finding that a significant percentage of pharyngeal isolates are non-piliated suggests that K. kingae expresses additional surface factors that modulate interactions with host cells and likely play key roles in the pathogenesis of K. kingae disease. The purpose of this work was to increase our understanding of K. kingae virulence determinants, specifically focused on defining the surface factors and the mechanism involved in K. kingae adhesive interactions with epithelial cells. Additionally, this work aimed to further characterize components of the K. kingae type IV pilus system, namely the PilC proteins and PilA2.

We first set out to identify non-pilus factors that influence K. kingae interactions with human epithelial cells. Using targeted genetic approaches, we found that insertional inactivation of the gene encoding a predicted trimeric autotransporter protein called Knh (Kingella NhhA homolog) resulted in reduced adherence to human epithelial cells. In addition, using a variety of techniques, including morphological analysis, cationic ferritin staining, and thin section transmission electron microscopy, we established that K. kingae elaborates a surface-associated polysaccharide capsule that requires a predicted ABC-type transporter export operon called ctrABCD for surface presentation. Furthermore, using quantitative human epithelial cell adherence assays, we discovered that the presence of surface capsule interferes with Knh-mediated adherence by non-piliated organisms and that maximal adherence in the presence of capsule requires the predicted type IV pilus retraction machinery, PilT/PilU. Based on the data presented here, we propose a novel adherence mechanism that allows K. kingae to adhere efficiently to human epithelial cells while remaining encapsulated and more resistant to immune clearance.

Having established that K. kingae produces a capsule, a large-scale polysaccharide purification technique was developed for capsule analysis of strain 269-492. Biochemical assays determined that the purified material contained thiobarbituric and phenol-sulfuric acid reactive glycosyl residues. In collaboration with the University of Georgia Complex Carbohydrate Research Center (CCRC), mass spectrometry identified galactose, N-acetyl-galactosamine, and Kdo as the major glycosyl components of the polysaccharide preparation. NMR spectroscopy revealed that the purified material contained two distinct polysaccharides with the structures of →5)–β–Galf–(1→ and →3)–β–GalNAcp–(1→5)–β–Kdop–(2→. Further characterization of the polysaccharides expressed by K. kingae may have implications for disease prevention strategies.

Previous work in our lab found that two PilC-like proteins called PilC1 and PilC2 influence type IV pili expression and pilus-mediated adherence. Production of either PilC1 or PilC2 is necessary for K. kingae piliation and bacterial adherence. We set out to further investigate the role of PilC1 and PilC2 in type IV pilus-associated phenotypes. We found that PilC1 contains a functional nine amino acid calcium-binding (Ca-binding) site with homology to the Pseudomonas aeruginosa PilY1 Ca-binding site and that PilC2 contains a functional 12 amino acid Ca-binding site with homology to the human calmodulin Ca-binding site. Using targeted mutagenesis to disrupt the Ca-binding sites, we demonstrated that the PilC1 and PilC2 Ca-binding sites are dispensable for piliation. Interestingly, we show that the PilC1 site is necessary for twitching motility and adherence to Chang epithelial cells, while the PilC2 site has only a minor influence on twitching motility and no influence on adherence. These findings establish key differences in PilC1 and PilC2 function in K. kingae and provide insights into the biology of the PilC-like family of proteins.

Lastly, we set out to define the role of the PilA2 minor pilin in K. kingae strain 269-492. While previous studies indicated that PilA2 is not essential for pilus expression or adherence to epithelial cells, analysis of the pilin locus in a diverse set of clinical isolates revealed that the pilA2 gene sequence is highly conserved, suggesting it serves an important function. Using targeted mutagenesis we showed that PilA2 is not essential for twitching motility and may or may not be involved in natural competence. Western blot analysis was unable to detect PilA2 in wild type pilus preparations, indicating that it is expressed at a level beneath the assay detection limit or does not localize to the pilus. Additionally, site-directed mutagenesis was used to place pilA2 under control of the highly active pilA1 promoter and showed that PilA2 is able to be assembled into fibers that mediate intermediate adherence to epithelial cells.

Taken together, this work expands our knowledge of the K. kingae surface factor repertoire and provides insights into the roles of type IV pilus components. The mechanism of K. kingae adherence to epithelial cells is beginning to emerge. These contributions may lead to novel strategies for the prevention of invasive K. kingae disease in young children.

Background: Spirituality and religious practices can motivate proactive health behavior. Although beliefs and practices may lead to different health behaviors, it is important to recognize the contribution of both to allopathic and complementary and alternative health system utilization. There is a lack of empirical research in this area, especially in Honduras, containing a culture rich in spirituality and religious affiliation.

Methods: Ethical review boards at Duke University and the National Autonomous University of Honduras approved the study protocol. A cross-sectional questionnaire survey was administered in urban Tegucigalpa, Honduras, and a final sample of 600 respondents was obtained. The primary independent measures were self-rated spirituality, religious affiliation, church attendance, and private devotion time. The primary outcome measures were: 1) hypothetical health system use, 2) an estimate of actual preventive health system use, 3) an estimate of actual curative health system use, and 4) an estimate of the relative risk of non-adherent behavior using the Medication Adherence Report Scale (MARS).

Results: Among the 600 respondents of the final sample, 499 (83.2%) had seen a physician in the previous year, either for routine check-up or for "sick use" and received some form of medication. Fewer (430/600, 72.0%) had used a complementary and alternative medical system or treatment (excluding prayer used for health reasons). The majority of respondents believed that natural medicine has no side effects (70.2%) and does not interfere with medicine from the physician (62.8%). Nearly all (93.2%) of the respondents felt that prayer was "very important" in curing sickness. Respondents were significantly more likely to prioritize the physician first, compared to natural medicine, if they were older than 25, had less than secondary education, were not a student, knew that natural medicine has harmful side effects, and knew natural medicine can interfere with medicine from a physician. Respondents were significantly more likely to use a combination first if they were 18-24 years old, had at least a secondary education, were unemployed, were students, and thought natural medicine does not interfere with medicine from the physician.

Self-rated spirituality, religious affiliation, church attendance, and private devotion time had significant crude associations with some, but not all, of the outcome measures. There were no significant associations with hypothetical health system use. Nearly two-thirds (65.9%) of those who associated with a specific religion went to a physician for a routine check-up last year compared to 43.0% of those who did not (p<0.001). Among those who attended church, 67.3% went for a routine check-up compared to 44.0% of those who did not attend (p<0.001). In addition, 64.9% of respondents who had a private devotion time, compared to 40.3% of those who did not, had a routine check-up (p<0.001). Self-rated spirituality had only a mild association with having a routine check-up (p<0.05) and using non-prayer complementary and alternative medicine (p<0.05). Those who associated with a religion were more likely to have received some form of medicine from an allopathic physician last year (80.7% vs. 61.3%, p<0.001). Likewise, 82.0% percent of churchgoers compared to 62.7% of those that did not go to church received medicine (p<0.001). Finally, 58.9% of those with a daily private devotion time, compared to 44.2% of those without one, reported adherent behavior (p<0.01).

Conclusion: Self-rated spirituality and religious involvement are significantly associated with the utilization of the preventive and curative allopathic health systems and adherence to medication in Tegucigalpa, Honduras. These findings deserve further consideration and have implications in both health policy and patient care in Honduras, a country with a thriving spiritual and religious culture.

Fungal cells sense the amount and quality of external nutrients through multiple interconnected signaling networks, which allow them to adjust their metabolism, transcriptional profiles and developmental programs to adapt readily and appropriately to changing nutritional states. In organisms ranging from yeasts to humans, the Tor signaling pathway responds to nutrient-derived signals and orchestrates cell growth. While in the baker's yeast Saccharomyces cerevisiae Tor responds to nutrient-derived signals and orchestrates cell growth and proliferation, in Schizosaccharomyces pombe Tor signaling modulates sexual differentiation in response to nutritional cues. Thus, these differences provide a framework to consider the roles of Tor in other fungal organisms, in particular those that are pathogens of humans.

In this dissertation, I demonstrate that in the human fungal pathogen Candida albicans, Tor signaling also functions to promote growth. This study also uncovered a novel role for the Tor molecular pathway in promoting hyphal growth of C. albicans on semi-solid surfaces and in controlling cell-cell adherence. Gene expression analysis and genetic manipulations identified several transcriptional regulators (Bcr1, Efg1, Nrg1, and Tup1) that together with Tor compose a regulatory network governing adhesin gene expression and cellular adhesion. While the Tor kinases are broadly conserved, these studies further demonstrate the contrasting strategies employed by fungal organism in utilizing the Tor signaling cascade.

While extensive studies have focused on elucidating functions for the Tor signaling cascades among ascomycetes, little is known about the pathway in basal fungal lineages, in particular among zygomycetes and chytrids. Moreover, given that the Tor pathway is the target of several small molecule inhibitors including rapamycin, a versatile pharmacological drug used in medicine, there is considerable interest in Tor signaling pathways and their function. Capitalizing on emerging genome sequences now available for several basal fungal species, we show a remarkable pattern of conservation, duplication, and loss of the Tor signaling cascade among basal fungal lineages. Targeting the pathway with rapamycin results in growth arrest of several zygomycete species, indicating a conserved role for this pathway in regulating fungal growth. In addition, we show a potential therapeutic advantage of using rapamycin in a heterologous model of zygomycosis. Taken together, the Tor signaling cascade and its inhibitors provide robust platforms from which to develop novel antimicrobial therapies, which may include less immunosuppressive rapamycin analogs.