No abstract

Ni, Cu, Zn, and Pb were measured by atomic absorption spectrometry in sweat samples obtained by the arm-bag technique from 48 healthy adult subjects (33 ♂, 15 ♀ ) during sauna bathing (15 min at 93 °C, dry heat). The men sweated more profusely than the women (volume, in milliliters, of sweat collected: mean, SD, and range: 23 ± 12 (3-55) and 7 ± 3 (2-13), respectively. The concentrations, in µg/liter, (mean, SD, and range) of trace metals in sweat of men and women, respectively, were: nickel, 52 ± 36 (7-180) and 131 ± 65 (39-270); copper, 550 ± 350 (30-1440) and 1480 ± 610 (590-2280); zinc, 500 ± 480 (130-1460) and 1250 ± 770 (530-2620); and lead, 51 ± 42 (8-184) and 118 ± 72 (49-283). In sweat samples from 11 women on oral contraceptives, concentrations of Ni, Cu, Zn, and Pb did not differ significantly from the values in the 15 control women. Sweating is a demonstrably significant route for excretion of trace metals, and sweating may play a role in trace-metal homeostasis. Essential trace metals could conceivably be depleted during prolonged exposure to heat; conversely, sauna bathing might provide a therapeutic method to increase elimination of toxic trace metals.

Background: The Laboratory Advisory System (LAS) is an expert system interface that works interactively with clinicians to assist them with test selection and result interpretation throughout the laboratory investigation of a patient. Methods: To study the influence of the LAS on laboratory investigations, a repeated-measures experiment using clinical vignettes was conducted. To collect baseline data on how laboratory investigations are currently conducted, clinicians investigated one-half of the vignettes using a conventional (noncomputer) approach. To determine the influence of the LAS on clinicians’ behavior, the other half of the vignettes were investigated using the LAS. Results: Clinicians using the LAS (compared with conventional practice) ordered fewer laboratory tests during the diagnostic process (mean, 17.8 vs 32.7), completed the diagnostic workup with fewer sample collections (mean, 5.8 vs 7.5), generated lower laboratory costs (mean, $194 vs $232), shortened the time required to reach a diagnosis (mean, 1 day vs 3.2 days), showed closer adherence to established clinical practice guidelines, and exhibited a more uniform and diagnostically successful investigation. Conclusion: The LAS enhances the outcome of the investigation and improves laboratory utilization.

Twenty patients with malignant disease and Bence Jones (BJ) proteins were studied to determine the optimum urine collections for the detection and monitoring of light chain proteinuria. A 24-hour urine protein collection was followed by individual collections of each sequentially voided specimen over the same time interval. Samples were analyzed quantitatively for protein, and protein electrophoresis was performed on each specimen. Only one patient had BJ protein nondetectable by protein electrophoresis in the early morning specimen. Six patients had one or more random specimens (excluding the early morning specimens) absent for BJ protein on protein electrophoresis. Three patients had nondetectable protein on electrophoresis of the 24-hour specimen despite having some random specimens positive. All random specimens with protein values exceeding 0.20 g/L had BJ protein visibly detectable on electrophoresis. Thirteen specimens with protein less than 0.05 g/L still had BJ protein detected by electrophoresis. There was a linear relationship between the early morning protein concentration and the total 24-hour urinary protein production. The authors conclude that early morning specimens or 24-hour urine collections are preferable for the detection and monitoring of light chain proteinuria. These collection methods are not mutually exclusive because there are individual patients who will be negative in one collection but positive in the other.

Nickel was measured, by atomic absorption spectrometry, in serum and urine specimens from: (a) healthy hospital employees (age 19-62) who had resided >1 year in Sudbury, Ontario, and (b) healthy hospital employees (age 18-62) who had resided >1 year in Hartford, Connecticut. Subjects in groups a and b were matched according to age and sex. None of the subjects had occupational exposure to nickel. Nickel was analyzed in duplicate on a "blind" basis with specimens from groups a and b interspersed within each run. In population a, serum nickel concentrations averaged 4.6 ± 1.4 µg/liter (n = 25), urine nickel excretion 7.9 ± 3.7 µg/day (n = 19). In population b, serum nickel concentrations averaged 2.6 ± 1.0 µg/liter (n = 26), urine nickel excretion 2.5 ± 1.4 µg/ day (n = 20). These population means were all significantly different (P <0.001, t test). Serum and urinary nickel concentrations were not significantly influenced by age or sex, nor were they correlated with length of residence in either location. Nickel concentrations in municipal tap water averaged 200 ± 43 µg/liter in Sudbury (seven sites), and 1.1 ± 0.3 µg/liter in Hartford (five sites). Measurements of nickel in serum and urine are valid biological indices of environmental exposure to nickel.