Biomedical subjects

James T Walker

Publications and source records attributed to James T Walker.

5 recordsLinked to original sources

PubMed2006

Methods to minimize the risks of Creutzfeldt-Jakob disease transmission by surgical procedures: where to set the standard?

New prion-related disorders have emerged over the past 20 years, of which the most notable in the human context is variant Creutzfeldt-Jakob disease (CJD). This disorder is a challenge to medical and public health professionals seeking early detection and diagnosis, provision of therapy, and support for persons affected and a better understanding of transmission risks. The risk of iatrogenic transmission of the disease remains a significant threat, given the well documented cases of CJD transmission via surgery, organ transplantation, and blood transfusion. This review discusses our current understanding of the prevalence of variant CJD, the distribution of tissue infectivity, and new methods for the decontamination of surgical instruments. A comparison of emerging technologies is provided on the basis of our current perception of surgical risk to identify methods that are likely to provide sufficient safety margins and to stimulate debate about the standards needed to protect against variant CJD and CJD transmission.

Blood Transfusion↗

PubMed2005

Potential occupational risks for neurodegenerative diseases.

BACKGROUND: Associations between occupations and neurodegenerative diseases (NDD) may be discernable in death certificate data. METHODS: Hypotheses generated from 1982 to 1991 study were tested in data from 22 states for the years 1992-1998. Specific occupations and exposures to pesticides, solvents, oxidative stressors, magnetic fields, and welding fumes were evaluated. RESULTS: About one third (26/87) of the occupations hypothesized with neurodegenerative associations had statistically significant elevated mortality odds ratios (MOR) for the same outcome. Occupations with the largest MORs were (a) for presenile dementia (PSD)-dentists, graders/sorters (non-agricultural), and clergy; (b) for Alzheimer's disease (AD)-bank tellers, clergy, aircraft mechanics, and hairdressers; (c) for Parkinson's disease (PD)-biological scientists, clergy, religious workers, and post-secondary teachers; and (d) for motor neuron disease (MND)-veterinarians, hairdressers, and graders and sorters (non-agricultural). Teachers had significantly elevated MORs for all four diseases, and hairdressers for three of the four. Non-horticultural farmers below age 65 had elevated PD (MOR = 2.23, 95% CI = 1.47-3.26), PSD (MOR = 2.22, 95% CI = 1.10-4.05), and AD (MOR = 1.76, 95% CI = 1.04-2.81). Sixty hertz magnetic fields exhibited significant exposure-response for AD and, below age 65, for PD (MOR = 1.87, 95% CI = 1.14-2.98) and MND (MOR = 1.63, 95% CI = 1.10-2.39). Welding had elevated PD mortality below age 65 (MOR = 1.77, 95% CI = 1.08-2.75). CONCLUSIONS: Support was observed for hypothesized excess neurodegenerative disease associated with a variety of occupations, 60 Hz magnetic fields and welding.

Adult↗

PubMed2003

Deaths due to injuries among employed adults: the effects of socioeconomic class.

BACKGROUND: Few studies have investigated socioeconomic status (SES) and external causes of death (ie, deaths attributable to injuries). These deaths are of particular interest because they are potentially preventable and they represent the second leading cause of years of life lost under age 75. METHODS: We studied 261,723 deaths from external causes in 27 states from 1984 to 1997 among employed persons age 20-64. Numerator data came from occupation on the death certificate. Occupation-specific denominator data came from the U.S. Census. A Nam-Powers SES score was assigned to each occupation based on its relative income and education in the U.S. Census. RESULTS: After adjusting for age, sex, year and race, SES was strongly associated with mortality from all external causes combined for men (rate ratios = 2.9, 2.3, 1.5, and 1.0 by ascending SES quartile), and to a lesser extent for women (rate ratios = 1.6, 1.0, 1.1, and 1.0). A similar pattern was seen for each of the specific external causes (motor vehicle deaths, suicide, homicide, injuries other than by motor vehicle, and medical complications). CONCLUSIONS: We estimate 41% of deaths from external causes are attributable to having a SES below the top quartile (both sexes combined).

Accidents, Occupational↗

PubMed2003

Antimicrobial effects of a novel Triclosan/zinc citrate dentifrice against mixed culture oral biofilms.

AIM: To compare the antimicrobial efficacy in vitro of a new fluoride system containing 0.3% Triclosan and 2.0% zinc citrate with a standard fluoride toothpaste against bacteria commonly isolated from dental plaque. METHOD: Mature biofilms of fixed depth containing ten oral bacterial species were developed in a model system and then exposed to the formulations both in situ and ex situ. RESULTS: The standard fluoride toothpaste had limited activity against the Gram positive species following 1 and 5 minutes ex situ exposure (p = 0.004 and p = 0.02, respectively) but none against the Gram negative species; also, no overall effect following repeated pulsing in situ was observed. In contrast, viable counts of Gram positive and Gram negative species were markedly reduced following ex situ exposure for 1 and 5 minutes to the new formulation (Gram positive: p = 0.0007 and p = 0.04; Gram negative: p = 0.04 and p = 0.00001, respectively). Counts of Gram positive bacteria were reduced by 99.9% over a 4-day in situ pulsing period, while no Gram negative species were recoverable from the biofilm by day 4. CONCLUSION: The new toothpaste formulation had a broad spectrum of antimicrobial activity against biofilm consortia containing bacteria associated with both dental caries and periodontal diseases.

Anti-Infective Agents, Local↗

PubMed2002

Heritable non-lethal damage to cultured human cells irradiated with heavy ions.

UNLABELLED: During interplanetary flights the nuclei of all of a crew member's cells could be traversed by at least one high-LET (Linear Energy Transfer) cosmic-ray particle. In mammalian cells irradiated in vitro about 1 in 10,000 of the surviving cells traversed by heavy particles is transformed to malignancy or mutated. What, if anything, happens to the remaining >99% of surviving cells? A retrospective analysis of archived data and samples from heavy-ion irradiation experiments with cultured human cells in vitro indicated that heavy ions caused a dose- and LET-dependent reduction in growth rates of progeny of irradiated cells, based on colony-size distributions. The maximum action cross section for this effect is between 100 and 300 microm2, at least as large as the cell nuclear area and up to 3 times the cross section for cell killing. Thus, heritable slow growth is the most prevalent effect of high-LET radiations on cultured animal cells, which may have implications for crew health during deep space travel. DISCLAIMER: The views expressed in this article are those of the author(s) and do not necessarily reflect the views or policies of the USEPA.

Cells↗