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1.  Ocular Tonometry and Sporadic Creutzfeldt - Jakob Disease (sCJD): A Confirmatory Case-Control Study 
Aims
To evaluate the hypothesis that sporadic Creutzfeldt-Jakob disease (sCJD) may be transmitted through ocular tonometry.
Background
The infectious agent of sCJD may be present in the cornea prior to clinical symptoms. Cornea infectiousness has been documented by cornea transplants in guinea pigs and humans. sCJD is resistant to complete inactivity by conventional sterilization techniques. Thus contact tonometry equipment is not disinfected sufficiently to kill sCJD. We previously hypothesized that contact tonometry is a sCJD risk factor.
Study Design
Population-based case-control study.
Place and Duration of Study
Department of Neurology, School of Medicine, Loma Linda University, Loma Linda, CA, USA; 4 years.
Methodology
An 11-state case-control study of pathologically confirmed definite sCJD cases, individually matched controls, and a sample of control surrogates was conducted. Ocular tonometry histories were obtained from case-surrogates, controls, and a sample of control-surrogates.
Results
The odds ratio (OR) for ever vs never having had an ocular tonometry test was statistically significant for matched and unmatched analyses for 15 through 3 years prior to disease onset, using both control self-responses and control surrogates: ORs were ∞ and 19.4 with 1-sided P-values <0.0001 and 0.003 and ORs=∞ and 11.1 with 1-sided P-values <0.003 and 0.02, respectively. ORs increased as the number of tonometry tests increased during this age period: trend test, 2-sided P-value < 0.0001. For ≥5 vs <5 tonometry tests, the OR was 5.8 (unmatched) and 3.7 (matched), 2-sided P-value<0.00005. Respondents generally could not specify the type of tonometry. There was no indication of increased tonometry testing among cases within 2 years of disease onset.
Conclusions
The a priori hypothesis was supported. Contact tonometry, preferred by ophthalmologists, may be capable of transmitting sCJD. Consideration should be given to using disposable instrument covers after each use. The use the disposable covers or non-contact tonometry is preferable in the absence of effective disinfectant processes at this time.
doi:10.9734/BJMMR/2014/7247
PMCID: PMC4115807  PMID: 25089261
Sporadic Creutzfeldt-Jakob disease (sCJD); prion diseases; intraocular pressure (IOP) test; risk factors; iatrogenic transmission; eyes; ophthalmology; case-control study; neuroepidemiology
2.  Dietary Risk Factors for Sporadic Creutzfeldt-Jakob Disease: A Confirmatory Case-Control Study 
Aims
This study’s primary purpose was to determine whether earlier findings suggesting an association between sporadic Creutzfeldt-Jakob disease (sCJD), a transmissible spongiform encephalopathy of humans and specific dietary components could be replicated. The a priori hypotheses were that consumption of (i) foods likely to contain organ tissue and (ii) raw/rare meat are associated with increased sCJD risk.
Study Design
Population-based case-control study.
Place and Duration of Study
Department of Neurology, School of Medicine, Loma Linda University, Loma Linda, CA, USA; 4 years.
Methodology
An 11-state case-control study of pathologically confirmed, definite sCJD cases, matched controls, and a sample of control-surrogates was conducted. Ninety-six percent (106/110) of the case data was obtained in 1991-1993, prior to variant CJD publicity.
Results
Using control self-responses, consumption of hot dogs, sausage, pepperoni, kielbasa, “other” canned meat, poultry liver, any stomach/intestine, beef stomach/intestine, any organ tissue, and beef organ tissue was individually associated with increased sCJD risk; odds ratios (OR) ranged from 2.4 to 7.2 (0.003
Conclusions
The a priori hypotheses were supported. Consumption of various meat products may be one method of transmission of the infectious agent for sCJD.
doi:10.9734/BJMMR/2014/7209
PMCID: PMC4070593  PMID: 24977122
Sporadic Creutzfeldt-Jakob disease; dietary risk factors; confirmatory case-control study; prion diseases; neuroepidemiology
Aims
This report is the first study of the possible relationship between extremely low frequency (50–60 Hz, ELF) magnetic field (MF) exposure and severe cognitive dysfunction. Earlier studies investigated the relationships between MF occupational exposure and Alzheimer’s disease (AD) or dementia. These studies had mixed results, depending upon whether the diagnosis of AD or dementia was performed by experts and upon the methodology used to classify MF exposure.
Study Design
Population-based case-control.
Place and Duration of Study
Neurology and Preventive Medicine, Keck School of Medicine, University of Southern California, 2 years.
Methodology
The study population consisted of 3050 Mexican Americans, aged 65+, enrolled in Phase 1 of the Hispanic Established Population for the Epidemiologic Study of the Elderly (H-EPESE) study. Mini-Mental State Exam (MMSE) results, primary occupational history, and other data were collected. Severe cognitive dysfunction was defined as an MMSE score below 10. The MF exposure methodology developed and used in earlier studies was used.
Results
Univariate odds ratios (OR) were 3.4 (P< .03; 95% CI: 1.3–8.9) for high and 1.7 (P=.27; 95% CI: 0.7–4.1) for medium or high (M/H) MF occupations. In multivariate main effects models, the results were similar. When interaction terms were allowed in the models, the interactions between M/H or high occupational MF exposure and smoking history or age group were statistically significant, depending upon whether two (65–74, 75+) or three (65–74, 75–84, 85+) age groups were considered, respectively. When the analyses were limited to subjects aged 75+, the interactions between M/H or high MF occupations and a positive smoking history were statistically significant.
Conclusion
The results of this study indicate that working in an occupation with high or M/H MF exposure may increase the risk of severe cognitive dysfunction. Smoking and older age may increase the deleterious effect of MF exposure.
doi:10.9734/BJMMR/2014/7317
PMCID: PMC4020120  PMID: 24839595
Severe Cognitive Dysfunction; Dementia; Occupational Exposure; Extremely Low Frequency Magnetic Fields; Elderly Mexican Americans; Hispanic Established Population for the Epidemiologic Study of the Elderly (H-EPESE); Mini-Mental State Exam
Background
A significant body of literature indicates that melatonin, a hormone primarily produced nocturnally by the pineal gland, is an important scavenger of hydroxyl radicals and other reactive oxygen species. Melatonin may also lower the rate of DNA base damage resulting from hydroxyl radical attack and increase the rate of repair of that damage. This paper reports the results of a study relating the level of overnight melatonin production to the overnight excretion of the two primary urinary metabolites of the repair of oxidatively damaged guanine in DNA.
Methods
Mother-father-daughter(s) families (n = 55) were recruited and provided complete overnight urine samples. Total overnight creatinine-adjusted 6-sulphatoxymelatonin (aMT6s/Cr) has been shown to be highly correlated with total overnight melatonin production. Urinary 8-oxo-7,8-dihydro-guanine (8-oxoGua) results from the repair of DNA or RNA guanine via the nucleobase excision repair pathway, while urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) may possibly result from the repair of DNA guanine via the nucleotide excision repair pathway. Total overnight urinary levels of 8-oxodG and 8-oxoGua are therefore a measure of total overnight guanine DNA damage. 8-oxodG and 8-oxoGua were measured using a high-performance liquid chromatography-electrospray ionization tandem mass spectrometry assay. The mother, father, and oldest sampled daughter were used for these analyses. Comparisons between the mothers, fathers, and daughters were calculated for aMT6s/Cr, 8-oxodG, and 8-oxoGua. Regression analyses of 8-oxodG and 8-oxoGua on aMT6s/Cr were conducted for mothers, fathers, and daughters separately, adjusting for age and BMI (or weight).
Results
Among the mothers, age range 42-80, lower melatonin production (as measured by aMT6s/CR) was associated with significantly higher levels of 8-oxodG (p < 0.05), but not with 8-oxoGua. Among the fathers, age range 46-80, lower melatonin production was associated with marginally higher levels of 8-oxoGua (p < 0.07), but not with 8-oxodG. Among the daughters, no relationship was found between melatonin levels and either 8-oxodG or 8-oxoGua levels. When the mother and father data were further analyzed using only subjects older than the oldest daughter, the associations became somewhat stronger.
Conclusion
Low levels of endogenous melatonin production among older individuals may lead to higher levels of oxidatively damaged guanine in DNA, thereby possibly increasing the risk of developing cancer. The possible different effects of melatonin in the rates of utilization of pathways for repair of oxidatively damaged guanine in DNA identified between older women and older men are intriguing.
doi:10.1186/1472-6823-9-22
PMCID: PMC2771025  PMID: 19835624
BMC Neurology  2007;7:13.
Background
A few studies have investigated a possible relationship between Alzheimer's disease (AD) and occupations with extremely low frequency magnetic field (MF) exposure. The purpose of this study was to further evaluate this possible association in a large patient population with expert diagnoses.
Methods
Subjects came from the 8 of the 9 California Alzheimer's Disease Diagnostic and Treatment Centers not previously used in an earlier study. Cases had probable or definite AD; controls primarily had a dementia-related problem other than vascular dementia (VaD) and some were not demented upon expert examination. Occupations were classified as having low, medium or high MF exposure, based upon previous research, replicating the exposure methodology used in our previous published studies.
Results
Occupational information was available for 98.6% of the 1527 cases and 98.5% of the 404 controls with age-at-initial examination known to be at least 65. Among cases, 2.1% and 5.4% had high and medium occupational MF exposure, respectively, while among controls the percentages were 0.8% and 3.0%. In univariate analyses, the odds ratio (OR) for subjects with medium or high MF exposures combined was 2.1 (p < 0.01), while for high exposure alone the OR was 2.9 (p < 0.08). Two models were used in multivariate analyses, with gender, stroke, and either age-at-onset or age-at-initial examination as covariates. The ORs for MF exposure varied little between the two models: 2.2 (p < 0.02) and 1.9 (p < 0.03) for medium or high exposure; 2.7 (p < 0.11) and 3.2 (p < 0.12) for high exposure. OR estimates for females were higher than for males, but not significantly higher. There were no material differences between the ORs resulting from univariate and multivariate analyses.
Conclusion
Elevated occupational MF exposure was associated with an increased risk of AD. Based on previous published studies, the results likely pertain to the general population.
doi:10.1186/1471-2377-7-13
PMCID: PMC1906833  PMID: 17559686

Results 1-5 (5)