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S Seidel

Publications and source records attributed to S Seidel.

28 records · Page 2Linked to original sources
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Risk of vertebral insufficiency fractures in relation to compressive strength predicted by quantitative computed tomography.

Vertebral insufficiency fractures may result from excessive loading of normal and routine loading of osteoporotic spines. Fracture occurs when the mechanical load exceeds the vertebral compressive strength, i.e., the maximum load a vertebra can tolerate. Vertebral compressive strength is determined by trabecular bone density and the size of endplate area. Both parameters can be measured non-invasively by quantitative computed tomography (QCT). In 75 patients compressive strength (i.e., trabecular bone density and endplate area) of the vertebra L3 was determined using QCT. In addition, conventional radiographs of the spines were analysed for the prevalence of insufficiency fractures in each case. By relating fracture prevalence to strength, three fracture risk groups were found: a high-risk group with strength values of L3 less than 3 kN (kilo Newton) and a fracture risk of 100%, an intermediate group with strength values from 3 to 5 kN and a steeply increasing risk with decreasing strength, and a low-risk group with strength values greater than 5 kN and a fracture risk near 0%. Biomechanical measurements and model calculations indicate that spinal loads of 3 to 4 kN at L3/4 will be common in everyday activities. These data and the results described above suggest that spines with strength values of L3 less than 3 kN are at an extremely high risk of insufficiency fractures in daily life. Advantages of fracture risk assessment by strength determination over risk estimation based on clinically used trabecular bone density measurements are discussed.

Adult↗
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Community Health Nursing↗
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Pesticide exposures to children from California's Central Valley: results of a pilot study.

In response to concerns about pesticide use and evidence that contaminants may accumulate in house dust, the California Department of Health Services (DHS) conducted a pilot study of pesticide contamination in rural children's home environments. House dust samples for pesticide analysis were collected from eleven homes, five of which had at least one farmworker (FW) resident. Handwipe samples were collected from one child at each residence (ages 1-3 years). Ten of 33 pesticides tested in house dust were detected. Excluding non-detects, concentrations for diazinon ranged from 0.7-169 ppm in four FW homes and 0.2-2.5 ppm in three non-farmworker (NFW) homes (overall median = 1 ppm), suggesting a difference between FW and NFW homes. Chlorpyrifos ranged from 0.2-33 ppm in three FW homes and < 1 ppm in two NFW homes (overall median < 0.5 ppm). All other pesticides were detected at < 2 ppm at four or fewer homes. The sources of these compounds could not be determined. Co-located samples were considerably different in concentration and loading, indicating intra-household variation. Of nine compounds tested, diazinon and chlorpyrifos were found on the hands of two or three FW children (20-220 ng/hand). Dust ingestion scenarios show child exposures could exceed the United States Environmental Protection Agency Office of Pesticide Program diazinon chronic reference dose (9 x 10(5) mg/kg/day). The results suggested that pesticide residues are present in the home environment of some California children and are likely to contribute to exposures. Additional research is feasible and needed to assess the magnitude and distribution of these risks.

Administration, Oral↗