Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 45-55).

Thesis (M.Sc.)--Acadia University, 2007. / Includes bibliographical references (leaves 81-92). Also available on the Internet via the World Wide Web.

Background: Street-involved youth are known to be at a greatly increased risk of HIV and sexually transmitted infections (STIs); however, the role that environmental and structural factors play in driving disease transmission risk among this population has not been thoroughly examined. Methods: The At Risk Youth Study (ARYS) is a prospective cohort of homeless and street-involved youth between the ages of 14 and 26. From September 2005 to October 2006, participants completed a baseline questionnaire which elicited information regarding sexual activity, injection and non-injection drug use, addiction treatment experience, encounters with police and security guards, and health service utilization. Environmental and structural correlates of number of recent sex partners were identified using quasi-Poisson regression. Factors independently associated with consistent condom use were also examined using logistic regression. Results: Among 529 participants, 415 (78.4%) were sexually active during the past six months, of whom 253 (61.0%) reported multiple sex partners and 288 (69.6%) reported inconsistent condom use during this time period. In multivariate logistic regression, homelessness and self-reported structural barriers to accessing health services were inversely associated with consistent condom use. In multivariate analysis, living in a shelter, hostel, or single room occupancy hotel was positively associated with greater numbers of recent sex partners. Structural factors that were associated with number of sex partners included having a warrant or area restriction that affects access to health services, and for males, being accosted by the police. Conclusions: Unstable housing, homelessness, and structural factors related to the criminalization and displacement of street-involved youth were associated with an increased risk of HIV and STI transmission, even after extensive adjustment for sociodemographic and individual level characteristics. These findings suggest that both environmental and structural factors influence the spread of HIV and STIs, and point to the need for environmental-structural interventions to reduce the burden of these diseases among this population.

Clinical and epidemiological studies have provided a large body of evidence supporting a link between HIV and other sexually transmitted co-infections. Co-infections have been associated with promoting HIV transmission and acquisition. One of the closest studied interactions is the co-infection with N. gonorrhoeae, the etiological agent of gonorrhea, yet a clear understanding of this relationship is still elusive. Studies aimed at deciphering how N. gonorrhoeae mediates these effects have provided mixed results with some suggesting co-infection promotes HIV replication, and others suggesting the opposite. The aim of this thesis is to uncover molecular mechanisms that explain these results through in vitro co-infection studies using a combination of mixed peripheral mononuclear blood cells (PBMCs) and isolated human cell types. The results presented here demonstrate that gonococcal co-infection profoundly inhibits HIV replication in co-infected PBMCs. This inhibition is due to both the release of anti-HIV IFN via TLR9-mediated activation of plasmacytoid dendritic cells (pDCs), and the activation of  T cells. In addition, I show that responses between CD4+ T cell lines, such as the Jurkat cell line, and primary CD4+ T cells can differ, which may explain some of the contrasting results seen in published literature. The results in this thesis have implications for understanding the relationship between gonococci and HIV, providing new insight into molecular and immunological interactions that influence viral transmission, and reveal new opportunities to combat HIV.

Research shows miners can be exposed to foot-transmitted vibration (FTV) when operating various pieces of underground mining equipment, and case reports suggest workers are experiencing symptoms similar to those of hand-arm vibration syndrome in their feet. A field study was conducted to measure and document FTV exposure associated with operating underground mining equipment, and probable health risks were determined based on both ISO 2631-1 (1997) for WBV and ISO 5349-1 (2004) for HAV. Seventeen participating operator’s also reported musculoskeletal discomfort. Seventeen male participants ranging between 24-61 years of age, with an average height and mass of 175.0cm and 88.2kg volunteered for the study. Seventeen pieces of equipment were tested; 1 locomotive, 1 crusher, 9 bolter drills (4 scissor platforms, 2 Maclean, 2 Boart/basket, and 1 RDH), and 6 jumbo drills. Including all seventeen pieces of underground mining equipment, the vibration acceleration ranged from 0.13-1.35m/s2 with dominant frequencies between 1.25-250Hz according to ISO 2631-1. According to ISO 5349-1 vibration acceleration ranged from 0.14-3.61m/s2 with dominant frequencies between 6.3-250Hz. Furthermore, the magnitude of FTV measured on the jumbo drills with grated platforms (#5 and #6) was less than FTV measured from the jumbo drills with, solid metal surfaces. Additionally, twelve of the seventeen equipment operators indicated a complaint of discomfort in their lower body (specifically at the level of the knee or lower). The health risk analysis based on ISO 2631-1 indicated that one operator (bolter drill #9) was exposed to vibration above the criterion value, while the health risk analysis based on ISO 5349-1 indicated iv that two operators (jumbo drill #1 and bolter drill #1) were exposed to vibration above the criterion value. Operators reported very severe or severe discomfort; however, the same operators were not the operators of the equipment with FTV exposure levels above the ISO standards, leaving evidence to suggest that the standards are not properly assessing injury risk to vibration exposure via the feet. Future research is needed to develop a standard specific for FTV and to determine the link between early musculoskeletal injury reporting and the onset of vibration white foot. To do so, a better understanding of the biodynamic response of the foot to FTV is needed. A laboratory study was conducted to 1) measure and document transmissibility of FTV from (a) floor-to-ankle (lateral malleolus), and (b) floor-to-metatarsal, during exposure to six levels of vibration (25Hz, 30Hz, 35Hz, 40Hz, 45Hz, and 50Hz) while standing, and 2) to determine whether independent variables (vibration exposure frequency, mass, arch type) influence transmissibility (dependent variable) through the foot. A two-way repeated measures analysis of variance (ANOVA) was conducted. There was a significant interaction between transmissibility location and exposure frequency (λ = 0.246, F (5,25) = 15.365, p = 0.0001). There were significant differences in mean transmissibility between the ankle and metatarsal at 40Hz [t(29) = 4.116, p = 0.00029], 45Hz [t(29) = 6.599, p = 0.00000031], and 50Hz [t(29) = 8.828, p = 0.000000001]. The greatest transmissibility at the metatarsal occurred at 50Hz and at the ankle (lateral malleolus) transmissibility was highest from 25-30Hz, indicating the formation of a local resonance at each location. v Future research should focus on identifying resonance frequencies at different locations on the feet. This information is needed to develop an exposure guideline to help protect workers from exposure to FTV, and to develop personal protective equipment capable of attenuating harmful FTV exposure frequencies.

HIV-1 is the most prevalent and notorious sexually transmitted pathogen locally, and constantly challenges our foundation of knowledge regarding the classical STIs. The ultimate objective of the syndromic management strategy was to reduce the load of sexually transmitted infections, and hence HIV transmission. This strategy is multifaceted and not only includes the recognition of symptoms by the patient and an effective treatment regime that comprehensively covers the possible aetiological agents for a defined syndrome, but also appropriate health seeking behaviour of infected individuals, recognition of syndromes by the health care worker, partner management (notification and treatment), behavioural counselling and condom promotion. Understanding the complexity of sexual networking and transmission dynamics is part of such a strategy. So, although the rationale and design of syndromic case management appears simplistic, it is by no means easy to implement / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2002.

During the period January 1985 to December 1985, 537 consultations were undertaken at the Special Clinic at Addington Hospital, 483 of these were specifically for venereal disease. The male to female ratio was 2.2:1. The majority of the patients treated were Coloureds. Most of the patients were in the age group of 20-35 years. The majority of the patients were unemployed. Gonorrhoea was diagnosed in 25.13% of the patients, followed by latent syphilis 19.52%. Chancroid was the commonest cause of genital ulceration and was diagnosed in 10.4% of the study population. N. Gonorrhoea was isolated in 42 patients; 40.5% of the isolates were resistant to penicillin, 66.6% to cotrimaxozole and 30.9% to ampicillin. The organism was sensitive to chloromycetin, erythromycin and tetracycline in most cases. All the penicillin resistant strains were sensitive to spectinomycin. / Thesis (M.Prax.Med.)-University of Natal, Durban, 1986.

Treponema pallidum is the causative agent of the sexually transmitted disease, syphilis. The organism can not be cultured in vitro, which has inhibited the understanding of the pathogenesis of syphilis. There has been no evidence of a treponemal toxin but adherence of large numbers of treponemes is able to destroy cell monolayers of different cell types (Fitzgerald et al, 1982). Non-pathogenic treponemes failed to adhere to cultured cells and this suggests that adherence is associated with virulence of T. pallidum (Fitzgerald et al, 1977). In this study we explored the interaction of T. pallidum with HaCaT cells which are immortalized human keratinocytes with characteristics equivalent to their natural counterpart. The adhesion assay confirmed binding of the organism to HaCaT cell monolayers. Migration assays and electron microscopy revealed that T. pallidum migrates through a confluent keratinocyte layer and western blotting experiments that differentiate between soluble and insoluble occludin confirmed that T. pallidum does not loosen the tight junctions. It is concluded that T. pallidum passes through the keratinocyte layer by trans-cellular rather than inter-cellular migration. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2010.

Background: The purpose of this secondary data analysis was to determine the prevalence of sexually transmitted and blood-borne infections (STBBI) and to examine the role of survival sex in sexual risk among street-involved youth in Winnipeg, Manitoba. Methods: Between 1999 and 2003, 743 Winnipeg street youth were interviewed in three separate cohorts as part of a national multi-centred study by the Public Health Agency of Canada. Results: Among the 673 Winnipeg street youth who responded to questions relating to survival sex, 26.3% reported they had engaged in survival sex. Females and Aboriginal youth were at greatest risk for sex trade involvement. Youth engaged in survival sex were diagnosed with significantly higher rates of STBBI; experienced greater amounts of abuse; and were at greater risk for participating in high risk sexual behaviours compared to their non-sex trade counterparts. Conclusion: Gender specific, culturally appropriate, and youth oriented prevention and intervention strategies are urgently required to reduce the prevalence of STBBI and survival sex among this at-risk population.

Clinical and epidemiological studies have provided a large body of evidence supporting a link between HIV and other sexually transmitted co-infections. Co-infections have been associated with promoting HIV transmission and acquisition. One of the closest studied interactions is the co-infection with N. gonorrhoeae, the etiological agent of gonorrhea, yet a clear understanding of this relationship is still elusive. Studies aimed at deciphering how N. gonorrhoeae mediates these effects have provided mixed results with some suggesting co-infection promotes HIV replication, and others suggesting the opposite. The aim of this thesis is to uncover molecular mechanisms that explain these results through in vitro co-infection studies using a combination of mixed peripheral mononuclear blood cells (PBMCs) and isolated human cell types. The results presented here demonstrate that gonococcal co-infection profoundly inhibits HIV replication in co-infected PBMCs. This inhibition is due to both the release of anti-HIV IFN via TLR9-mediated activation of plasmacytoid dendritic cells (pDCs), and the activation of  T cells. In addition, I show that responses between CD4+ T cell lines, such as the Jurkat cell line, and primary CD4+ T cells can differ, which may explain some of the contrasting results seen in published literature. The results in this thesis have implications for understanding the relationship between gonococci and HIV, providing new insight into molecular and immunological interactions that influence viral transmission, and reveal new opportunities to combat HIV.