The impact of host immunity on oscillating rates of syphilis when gender and race are considered

The rates of syphilis in the United States have increased since the all time low in 2000. In 2003, the rates of syphilis in the United States were 2.5 cases per 100,000. There were 178 reported cases of primary and secondary syphilis (8.9 cases per 100,000) in Houston, Texas, which was a 58.9% increase from 2002. While syphilis can be completely treated now, unlike in times past, it is still a public health concern. The purpose of this study is to examine the possibility of modeling the impact of an immune response in primary and secondary syphilis in 63 major cities across the United States, stratified by gender and racial-ethnic groups. A Fourier analysis will be performed by SAS. Subsequently, this study will compare the results to a similar study of syphilis in 68 US cities, that focused on immune response, however, did not stratified by race and gender. This study will help determine if the oscillating rates of syphilis are due to biological factors of the disease or to behavioral changes in the population. This study will use surveillance data from 63 major cities across the United States. The data will be provided by the Centers of Disease Control. Ultimately, this study will expand the knowledge of the effect of immunity on endemics.^

The effect of ultraviolet radiation on the pathogenesis of {\it Candida albicans} in mice

Ultraviolet (UV) radiation produces immunological alterations in both humans and animals that include a decrease in the delayed type hypersensitivity (DTH) response to complex antigens, and to the induction of the suppressor T cell pathway. Cell-mediated immunity of the type that is altered by UV radiation has been shown to be important in host resistance against microorganisms. My dissertation addresses questions concerning the effects of UV radiation on the pathogenesis of opportunistic fungal pathogens such as Candida albicans.^ The (DTH) response of C3H mice exposed to ultraviolet (UV) radiation before (afferent arm of DTH) or after (efferent arm of DTH) infection with Candida albicans was markedly and systemically suppressed. Although suppression of both the afferent and efferent phases of DTH were caused by similar wavebands within the ultraviolet region, the dose of UV radiation that suppressed the efferent arm of DTH was 10-fold higher than the dose that suppressed the afferent arm of the DTH reaction.^ The DTH response of C57BL/6 mice was also suppressed by UV radiation; however the suppression was accomplished by exposure to significantly lower doses UV radiation compared to C3H mice. In C57BL/6 mice, the dose of UV radiation that suppressed the afferent phase of DTH was 5-fold higher than the dose that suppressed the efferent phase.^ Exposure of C3H mice to UV radiation before sensitization induced splenic suppressor T cells that upon transfer to normal recipients, impaired the induction of DTH to Candida. In contrast, the suppression caused by UV irradiation of mice after sensitization was not transferable. Spleen cells from sensitized mice exhibited altered homing patterns in animals that were exposed to UV radiation shortly before receiving cells, suggesting that UV-induced suppression of the efferent arm of DTH could result from an alteration in the distribution of effector cells.^ UV radiation decreased the survival of Candida-infected mice; however, no correlation was found between suppression of the DTH response and the course of lethal infection. This suggested that DTH was not protective against lethal disease with this organism. UV radiation also changed the persistence of the organism in the internal organs. UV-irradiated, infected animals had increased numbers of Candida in their kidneys compared to non-irradiated mice. Sensitization prior to UV irradiation aided clearance of the organism from the kidneys of UV-irradiated mice.^ These data show that UV radiation suppresses cell-mediated immunity to Candida albicans in mice and increases mortality of Candida-infected mice. Moreover, the data suggest that an increase in environmental UV radiation could increase the severity of pathogenic infections. ^

Parental demographic risk factors and occupational exposure to ionizing radiation for achondroplasia, thanatophoric and autosomal deletions in Texas, 1996--2002

Little is known about the etiology of Achondroplasia (AC), Thanatophoric Dwarfism (TD), and autosomal deletions (CD). These syndromes are due to fully penetrate genetic mutations, yet arise de novo, instead of being inherited. We examined the association between parental demographic characteristics and parental occupations with exposure to ionizing radiation and these birth defects. ^ We conducted a cross-sectional study and two case-control studies using a large database that was created by linking records from Texas Birth Defects Registry, Texas birth certificates and Texas fetal death certificates from 1996 to 2002. The first case-control study was matched on paternal age and examined 73 cases of AC and 43 cases of TD. The second case-control study was unmatched and examined 343 cases of autosomal deletion syndromes. ^ We used a job exposure matrix (JEM) to measure exposures to ionizing radiation in the workplace. This gives an estimate of the intensity and probability of exposure to ionizing radiation for each occupation and industry. ^ The prevalence rate of Achondroplasia, Thanatophoric Dwarfism and autosomal deletions was 0.36 per 10,000, 0.21 per 10,000, and 1.68 per 10,000 births respectively in Texas 1996–2002. ^ Older fathers had a strong increase in the risk of having offspring with AC or TD and a modest increase in the risk of CD. Fathers who were Black or Hispanic were less likely to have infants with AC or TD compared to Whites (adjusted POR=0.61; 95% CI 0.30, 1.26 and 0.44; 95% CI 0.27, 0.88, respectively). Black fathers and Hispanic mothers were also less likely to have infants with CD (adjusted POR=0.54; 95% CI 0.22, 1.35 and 0.62; 95% CI 0.39, 0.97). ^ After adjusting for other parental demographic factors, there was no significant relation between fathers exposure to ionizing radiation in the work place and AC or TD (adjusted OR=0.48; 95% CI 0.19, 1.25) and no significant relation between parental exposure to ionizing radiation in the work place and CD (adjusted OR=1.16; 95% CI 0.73, 1.85). ^ This is the first study to find an association between father's age and TD and CD and paternal race and AC or CD. Parental exposure to radiation for therapeutic or diagnostic indications was not measured, thus it can not be excluded as a cause of these birth defects. ^

Quantitative comparison of late effects following photon versus proton external-beam radiation therapies: Toward an evidence-based approach to selecting a treatment modality

Radiation therapy has been used as an effective treatment for malignancies in pediatric patients. However, in many cases, the side effects of radiation diminish these patients’ quality of life. In order to develop strategies to minimize radiogenic complications, one must first quantitatively estimate pediatric patients’ relative risk for radiogenic late effects, which has not become feasible till recently because of the calculational complexity. The goals of this work were to calculate the dose delivered to tissues and organs in pediatric patients during contemporary photon and proton radiotherapies; to estimate the corresponding risk of radiogenic second cancer and cardiac toxicity based on the calculated doses and on dose-risk models from the literature; to test for the statistical significance of the difference between predicted risks after photon versus proton radiotherapies; and to provide a prototype of an evidence-based approach to selecting treatment modalities for pediatric patients, taking second cancer and cardiac toxicity into account. The results showed that proton therapy confers a lower predicted risk of radiogenic second cancer, and lower risks of radiogenic cardiac toxicities, compared to photon therapy. An uncertainty analysis revealed that the qualitative findings of this study are insensitive to changes in a wide variety of host and treatment related factors.

A nested case-control study of radiation exposure and brain cancer incidence in the United States Air Force

A nested case-control study design was used to investigate the relationship between radiation exposure and brain cancer risk in the United States Air Force (USAF). The cohort consisted of approximately 880,000 men with at least 1 year of service between 1970 and 1989. Two hundred and thirty cases were identified from hospital discharge records with a diagnosis of primary malignant brain tumor (International Classification of Diseases, 9th revision, code 191). Four controls were exactly matched with each case on year of age and race using incidence density sampling. Potential career summary extremely low frequency (ELF) and microwave-radiofrequency (MWRF) radiation exposures were based upon the duration in each occupation and an intensity score assigned by an expert panel. Ionizing radiation (IR) exposures were obtained from personal dosimetry records.^ Relative to the unexposed, the overall age-race adjusted odds ratio (OR) for ELF exposure was 1.39, 95 percent confidence interval (CI) 1.03-1.88. A dose-response was not evident. The same was true for MWRF, although the OR = 1.59, with 95 percent CI 1.18-2.16. Excess risk was not found for IR exposure (OR = 0.66, 45 percent CI 0.26-1.72).^ Increasing socioeconomic status (SES), as identified by military pay grade, was associated with elevated brain tumor risk (officer vs. enlisted personnel age-race adjusted OR = 2.11, 95 percent CI 1.98-3.01, and senior officers vs. all others age-race adjusted OR = 3.30, 95 percent CI 2.0-5.46). SES proved to be an important confounder of the brain tumor risk associated with ELF and MWRF exposure. For ELF, the age-race-SES adjusted OR = 1.28, 95 percent CI 0.94-1.74, and for MWRF, the age-race-SES adjusted OR = 1.39, 95 percent CI 1.01-1.90.^ These results indicate that employment in Air Force occupations with potential electromagnetic field exposures is weakly, though not significantly, associated with increased risk for brain tumors. SES appeared to be the most consistent brain tumor risk factor in the USAF cohort. Other investigators have suggested that an association between brain tumor risk and SES may arise from differential access to medical care. However, in the USAF cohort health care is universally available. This study suggests that some factor other than access to medical care must underlie the association between SES and brain tumor risk. ^