Developmental expression of the muscle-specific isozyme of phosphoglycerate mutase in human muscle cultured in monolayer and innervated by fetal rat spinal cord.

The electrophoretic pattern of phosphoglycerate mutase of adult innervated normal human muscle is composed predominantly of the muscle-specific isozyme, whereas the electrophoretic pattern of aneurally cultured human muscle is composed only of the brain-specific isozyme. We studied the transition of the isozymes (phosphogluterate mutase) in human muscle cultured in monolayer and innervated for 20 to 83 days by rat embryo spinal cord explants. In this culture system, regions of innervated muscle fibers in close proximity to the ventral part of the spinal cord explant continuously contracted and the contractions were reversibly blocked by 1 mM d-tubocurarine. In those innervated cultured human muscle fibers, the total activity of phosphoglycerate mutase was increased and the muscle-specific isozyme was expressed. The amount of muscle-specific isozyme directly correlated with the duration of innervation. This study demonstrated that expression of the gene for the muscle-specific isozyme of phosphoglycerate mutase in human muscle cultured in monolayer is influenced by de novo innervation.

Familial postpartum transient hyperthyroidism.

Postpartum painless thyroiditis with transient hyperthyroidism is being recognized with increasing frequency. Evidence tends to support an autoimmune cause. We treated a 33-year-old woman who experienced typical postpartum painless thyroiditis. Her sister had had a similar episode 13 years previously, and their mother had had postpartum hyperthyroidism 42 years earlier. We believe that this familial association provides further support for autoimmunity in postpartum thyroiditis.

The aminoglycoside panel: a new approach to monitoring aminoglycoside therapy.

The aminoglycoside antibiotics gentamicin and tobramycin have been monitored traditionally by measuring peak and trough drug levels in serum. We found interpretation of these data to be hazardous, due to variations in the drug administration-specimen collection process and routine medical events and practices. We describe an aminoglycoside panel consisting of three serum levels drawn across one dosage interval. Gentamicin and tobramycin were measured by an enzyme immunoassay. 430 panels (1,290 samples) were evaluated by determining each panel's conformity to a classical monoexponential decay curve. Panels were then categorized by pattern of fit to this model. Sixty-two percent of the panels fell within acceptable limits of the model, while 13% displayed obvious errors. The percentage of acceptable panels on nursing units given an intensive educational program on the proper protocol for drug administration-specimen collection procedures was increased compared with the rest of the hospital. We propose the adoption of the aminoglycoside panel for the routine monitoring of these antibiotics as a means of gauging specimen and data quality.

Aluminum concentrations in serum of hemodialysis patients.

Aluminum has been implicated in the etiology of the progressive dialytic encephalopathy. Data are presented on samples taken from patients on maintenance hemodialysis, during treatment. Aluminum was determined by electrothermal atomic absorption spectroscopy. Hemodialysis had no significant effect on serum aluminum concentrations, which ranged from 27 to 254 micrograms of Al per liter (1.00 to 9.42 mumol/L). Isolated ultrafiltration removed part of the serum aluminum, but most remained bound to a nonfiltrable component. These results are evaluated in the light of present knowledge concerning dialysis dementia.

Metabolic balance of aluminum studied in six men.

The metabolism of aluminum was followed in patients who were receiving strictly controlled diets, either unaltered or supplemented with aluminum-containing antacids. Aluminum was determined by atomic absorption spectrophotometry with a graphite furnace. All food, water, and medications were analyzed, as were aliquots of urine and stool collected throughout six-day periods. Patients were usually studied for five consecutive six-day periods on the same diet and aluminum intake. This study included six patients who were studied for seven to 21 such six-day periods. During control periods, when the patients were receiving less than 5 mg of aluminum per day, the balance was usually slightly negative, but when the diet was supplemented with antacids to contain 1--3 g of aluminum per day, an average positive balance of 23 to 313 mg of aluminum per day was observed for the total time on the same intake. Consecutive six-day periods while a subject was receiving antacids might show either positive or negative balances, but the average retention for 18--84 days on antacids was always positive. Thus the potential effects of the storage of aluminum in the tissues must be considered in the chronic administration of antacids.

Determination of aluminum in biological samples by atomic absorption spectrophotometry with a graphite furnace.

Aluminum, generally considered non-essential and non-toxic, may accumulate in toxic amounts in the brain in cases of chronic renal failure. We describe a procedure for its analysis in biological fluids by atomic absorption spectrophotometry with a graphite furnace. No sample preparation is required and the procedure is sensitive at the appropriate concentrations. A sample of serum or urine is pipetted into the interior of the graphite tube, where it is sequentially dried, charred, and atomized. Precautions for sample handling are discussed and instrument settings are defined. Precision and accuracy of the method are evaluated, as are the effects of salts, protein content of serum, and specific gravity of urine. Serum of 23 persons who were not consuming aluminum-containing antacids contained 28 +/- 9 (SD) microgram of Al per liter (1.02 +/- 0.33 mumol/liter).