Parathyroid hormone-mediated aluminum deposition and egress in the rat.

Exogenous PTH significantly enhances tissue aluminum concentration in normal rats fed an aluminum-supplemented diet. In this study, we examined the effect of PTH withdrawal on brain and whole carcass aluminum concentrations. Four groups of rats were fed an aluminum diet while receiving injections of PTH for 5 days. On day 5, one group of rats was sacrificed, and the treatment regimen of the remaining groups altered. PTH, the aluminum diet, or PTH and the aluminum diet were withdrawn respectively for an additional 5 days. An additional group of rats was fed the aluminum diet for 10 days. PTH dramatically increased the concentration of aluminum in both brain and carcass above that found in tissues of rats given aluminum alone. Brain and whole carcass aluminum concentrations remained elevated in rats continued on PTH even in the absence of continued supplemental dietary aluminum. In contrast, following PTH withdrawal, brain and whole carcass aluminum concentrations were significantly lower and independent of dietary aluminum. Thus, PTH may be an important mediator of specific tissue aluminum burdens.

Prevalence of hepatitis B in 27 Michigan hemodialysis centers.

A large epidemiological survey of inhospital chronic hemodialysis patients was conducted in 27 (93%) of the 29 dialysis centers in Michigan. Serum was collected from 699 patients on chronic maintenance hemodialysis for periods from one month to eight years. Hepatitis B surface antigen (HBsAg) was determined in all patients by radioimmunoassay and positive samples were confirmed by specific neutralization. Antibody against HBsAg (anti-HBs) was determined by radioimmunoassay in 110 HBsAg negative patients from six dialysis units with a high prevalence of hepatitis B. HBsAg was detected in 80 (11.4%) patients distributed among 21 (78%) of 27 dialysis units and anti-HBs in 34 (31%) patients from the selected dialysis units. The prevalence of HBsAg was related to duration of dialysis, number of blood transfusions, and to a history of bilateral nephrectomy, but not to age, sex, race, nor the underlying renal disease. Twenty-one (26%) of the 80 HBsAg positive patients had not been previously identified by the clinical laboratories of their institutions. Since preventive measures were not taken in the care of these inapparent carriers of HBsAg, they represent an unrecognized risk.

Hepatitis B surface antigen in urine of hemodialysis patients.

As part of an extensive epidemiological survey of chronic hemodialysis patients in Michigan, hepatitis B surface antigen (HBsAg) was identified in the sera of 79 of 701 (11%) patients. Of these patients, 59 were carriers of HBsAg for three or more months. Urine samples were collected from 36 of 39 HBsAg carriers having urinary output. Of these samples, 19 (52%) were positive for HBsAg by radioimmunoassay; this was confirmed by specific antibody neutralization. The HBsAg was not identified in the urine of seven hemodialysis patients who were lacking serum HBsAg or in urine samples from three HBsAg sero-carriers who had normal renal function. Patients undergoing maintenance hemodialysis appear to constitute a large reservoir of HBsAg chronic carriers. This study indicates that a minimum of 50% of persistent HBsAg carriers who are producing urine have detectable HBsAg in single, randomly timed, unconcentrated urine specimen. These data suggest that urine may represent a potential vehicle for transmission in nonparenterally acquired hepatitis B.