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Biomedical subjects

J S Davis

Publications and source records attributed to J S Davis.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Derivation of temporary emergency exposure limits (TEELs).

Short-term chemical concentration limits are used in a variety of applications, including emergency planning and response, hazard assessment and safety analysis. Development of emergency response planning guidelines (ERPGs) and acute exposure guidance levels (AEGLs) are predicated on this need. Unfortunately, the development of peer-reviewed community exposure limits for emergency planning cannot be done rapidly (relatively few ERPGs or AEGLs are published each year). To be protective of Department of Energy (DOE) workers, on-site personnel and the adjacent general public, the DOE Subcommittee on Consequence Assessment and Protective Actions (SCAPA) has developed a methodology for deriving temporary emergency exposure limits (TEELs) to serve as temporary guidance until ERPGs or AEGLs can be developed. These TEELs are approximations to ERPGs to be used until peer-reviewed toxicology-based ERPGs, AEGL or equivalents can be developed. Originally, the TEEL method used only hierarchies of published concentration limits (e.g. PEL- or TLV-TWAs, -STELs or -Cs, and IDLHs) to provide estimated values approximating ERPGs. Published toxicity data (e.g. lc(50), lc(LO), ld(50) and ld(LO) for TEEL-3, and tc(LO) and td(LO) for TEEL-2) are included in the expanded method for deriving TEELs presented in this paper. The addition here of published toxicity data (in addition to the exposure limit hierarchy) enables TEELs to be developed for a much wider range of chemicals than before. Hierarchy-based values take precedence over toxicity-based values, and human toxicity data are used in preference to animal toxicity data. Subsequently, default assumptions based on statistical correlations of ERPGs at different levels (e.g. ratios of ERPG-3s to ERPG-2s) are used to calculate TEELs where there are gaps in the data. Most required input data are available in the literature and on CD ROMs, so the required TEELs for a new chemical can be developed quickly. The new TEEL hierarchy/toxicity methodology has been used to develop community exposure limits for over 1200 chemicals to date. The new TEEL methodology enables emergency planners to develop useful approximations to peer-reviewed community exposure limits (such as the ERPGs) with a high degree of confidence. For definitions and acronyms, see Appendix.

Animals↗
PubMedDate not supplied

Direct evidence for circulating DNA/anti-DNA complexes in systemic lupus erythematosus.

Fifteen serum cryoprecipitates from 28 patients with systemic lupus erythematosus (SLE) contained DNA demonstrable by counterimmunoelectrophoresis after exhaustive digestion of cryoimmunoglobulin with pronase. The majority of these cryoprecipitates also exhibited increased DNA binding activity in a modified Farr assay. Both DNA and anti-DNA antibody were enriched in the cryoprecipitates relative to the supernatant serum level. These data provide direct evidence for the presence of DNA/anti-DNA complexes in the circulation of patients with SLE.

Antigen-Antibody Complex↗
PubMedDate not supplied

Infantile exotropia.

BACKGROUND: Exotropia is uncommon in healthy children between 6 months and 1 year old. METHODS: The charts of patients treated in our practice between January 1980 and August 1994 were reviewed for a diagnosis of infantile exotropia. All of them had an exodeviation during the first year of life. Children with neurologic defects, prematurity, trauma, craniofacial syndromes, or orbital abnormalities or ocular defects that would reduce vision were eliminated. RESULTS: Sixty-six healthy patients with normal eyes had an exodeviation of 15 prism diopters (delta) or more that persisted through the first year of life. Fifty-four were eliminated because the diagnosis had not been confirmed by a pediatric ophthalmologist before they were 1 year old or they had not been followed for more than 4 years. The 12 remaining patients were followed for at least 4 years (mean, 7.9 years). The mean age at the first examination was 7.8 months (range, 4 to 12 months). On early evaluation, exotropia was intermittent in four and constant in eight. Three had amblyopia. Ten required surgical correction. Exotropia was corrected with one operation in six patients; four required additional procedures, mostly to correct oblique muscle overaction and dissociated vertical deviation (DVD). At the most recent visit, all 12 patients had equal visual acuity in both eyes and satisfactory ocular alignment. Five had fusion at distance and near, but only two had stereo acuity of 100 seconds of arc or better. CONCLUSION: Infantile exotropia is rare. But, like patients with infantile esotropia, those with exotropia can be expected to have good visual acuity but unstable ocular alignment. Also, as with early-onset esotropia, although surgical intervention is usually required, high levels of binocular function develop in some patients with exotropia. Oblique muscle overaction and DVD are common, often becoming manifest by the first year of age. Unlike infantile esotropia, nystagmus is rare.

Depth Perception↗
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Osteomalacia and weakness complicating jejunoileal bypass.

Five years following jejunoileal intestinal bypass surgery for obesity, a patient developed debilitating weakness and muscle pain. Osteomalacia was suspected clinically by radiographic and laboratory abnormalities and confirmed by bone biopsy. Malabsorption was documented as well as secondary hyperparathyroidism. Successful treatment of this syndrome with vitamin D and calcium identified a medically reversible disorder which obviated the need for surgical reanastomosis.

Adult↗
PubMedDate not supplied

Cardiac damage produced by transchest damped sine wave shocks.

High-energy transchest damped wave sine defibrillation shocks have been shown to produce cardiac damage when applied in rapid sequence. However, there are no reports as to whether single, threshold-intensity shocks produce damage. In this study, nonfibrillating dogs were subjected either to a single, threshold-intensity (1 A/kg) shock, or to a series of 6 shocks with high intensity (3 to 4.8 A/kg). Electrodes of 8 cm diameter were used to apply the shock through the chest wall. Dogs receiving shocks of adequate (but not excessive) strength to defibrillate showed no cardiac damage, although they exhibited transient ventricular arrhythmias after the shock was applied. All dogs receiving the higher intensity, multiple shocks showed gross and microscopic evidence of cardiac damage. Ventricular lesions were observed in both right and left ventricular free walls and were sometimes transmural in extent. ECG analysis of the records from the dogs receiving multiple, high-intensity shocks showed second and third degree A-V block, ventricular ectopic beats, ventricular tachycardia, S-T segment changes, and T-wave inversion. Although multiple, high-energy, high-current defibrillation shocks produce permanent cardiac damage in dogs, threshold shocks do not produce morphologic changes.

Animals↗
PubMedDate not supplied

Immune complexes in progressive systemic sclerosis and mixed connective tissue disease.

Sera from patients with progressive systemic sclerosis (PSS) and mixed connective tissue disease (MCTD) were studied for the presence of circulating immune complexes (CICs) by Clq precipitins, cryoglobulins and the Raji cell and Clq radioimmunoassays. The Raji cell assay was the most sensitive, detecting ICs in 82% of patients with MCTD and in 55% with PSS. However, the median value in MCTD was significantly higher than in PSS (79 vs 20 microgram equivalent AHG/ml serum), and in MCTD, unlike PSS, the CIC levels appeared to parallel disease activity. Ribonucleoprotein (RNP) antigen could not be demonstrated in the Raji cell bound complexes.

Adult↗