Multiple forms of prostate-specific antigen in serum: differences in immunorecognition by monoclonal and polyclonal assays.

Prostate-specific antigen (PSA) in serum is primarily complexed with alpha 1-antichymotrypsin (alpha 1-ACT). However, 12-15% of prostate cancer (PCa) patients present with the predominant form being uncomplexed (free) PSA (Lilja et al., Clin Chem 1991;37:1618-24). We report that commercial immunoassays demonstrate variations in reactivity, especially to the uncomplexed form. We fractionated and analyzed commercial controls, PSA complexes prepared in vitro, and sera from patients with PCa or benign prostatic hyperplasia, using molecular sieve chromatography and Hybritech Tandem-R, Abbott IMx, and Ciba Corning ACS PSA assays. Peak integration of PCa samples demonstrated ACS:Tandem-R ratios of 1-1.3 for PSA/alpha 1-ACT complex. In contrast, ratios of uncomplexed peaks ranged from 2 to 4, suggesting a greater reactivity of the uncomplexed form in the ACS PSA assay. Discrepancies between assays, when PSA was measured in unfractionated sera, correlated directly with the percentage of the uncomplexed form. In controls, fractionation revealed the presence of uncomplexed PSA only, with ratios of ACS:Tandem-R and IMx:Tandem-R of 3:1 and 1.8:1, respectively. Immunoblots of PCa sera detected uncomplexed PSA (approximately 30 kDa) and PSA complexes of approximately 95 kDa (PSA/alpha 1-ACT) and > 200 kDa, indicative of alpha 2-macroglobulin. Maximal recognition of all forms of PSA may be important for early detection of disease progression.

Cadmium disposition and metallothionein induction in mice: strain-, sex-, age- and dose-dependent differences.

The strain- and sex-related differences in tissue cadmium (Cd) and metallothionein (MT) levels were examined in young adult (4-6 months old) C3H/HeJ, DBA/2J, 129/J, CD-1 and A/J mice, 24 h after a subcutaneous (s.c.) injection of 5-30 mumol CdCl2/kg. In many cases the tissue Cd concentrations were inversely related to the tissue weights. Also, the strain and sex differences were more obvious at 20-30-mumol dose levels. At such doses the hepatosensitive C3H males had as much as 30% higher hepatic Cd concentrations as the resistant DBA males, but similar concentrations to the resistant A/J and CD-1 males. This observation suggests that tissue Cd level is not the only determinant of strain differences in hepatotoxicity in males. Among the females, the A/J had 30-47% higher hepatic Cd concentration than the other strains. Livers of male C3H, CD-1 and 129/J mice had 17-57% higher Cd concentrations than those of the females; the greatest difference was in the C3H strain in which only the males exhibited hepatotoxicity at the 30 mumol dose. In all animals the hepatic MT concentration increased with the increasing Cd concentration. However, the 129/J males and all the females reached a plateau in MT concentration at Cd concentrations of 20-30 micrograms/g liver. Even at the highest Cd concentration, the C3H males had MT concentrations similar to some of the hepatoresistant males, suggesting that their sensitivity to Cd was not due to compromised MT levels. The renal Cd concentration was similar in males of most strains but not in females. For example, at the 30-mumol dose 129/J females had a Cd concentration which was 70% higher than in the DBA females. Also, at this dose level the A/J, C3H and 129/J females had 30-50% more Cd than the males. The DBA and C3H males had approximately twice the MT concentration of the A/J and 129/J males at 10 micrograms Cd/g kidney. At similar Cd concentration, the DBA females also had 1.6-2.0 times the MT concentration of the other females. The renal MT levels in females were 1.4-2.9 times higher than in males. Strains susceptible to the testicular toxicity of Cd had up to three times greater testicular Cd accumulation than the resistant strains. However, there was no increase in testicular MT in any strain. The effect of age on Cd and MT levels was studied in 19-month-old A/J and DBA mice at the 25-mumol dose.(ABSTRACT TRUNCATED AT 400 WORDS)

Similarities between metallothionein and low molecular weight testicular cadmium-binding protein.

The incorporation of 35S-cysteine and 3H-glutamic acid was studied in mouse hepatic and renal metallothionein and in testicular cadmium-binding protein of similar molecular weight. Preferential incorporation of 35S-cysteine over 3H-glutamic acid was observed not only in hepatic and renal metallothionein, but also in testicular cadmium-binding protein. When the antigenic reactivity of these proteins was compared, all three proteins reacted with the metallothionein antibody. These similarities suggest that the low molecular weight testicular cadmium-binding protein is apparently metallothionein.

Influence of glibenclamide on the efficacy of calcium trisodium pentetat as an antidote for cadmium toxicity.

Cadmium causes hyperglycemia, activation of hepatic and renal gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-diphosphatase, increases hepatic and renal zinc, renal copper and decreases hepatic and renal iron levels in rats. Glibenclamide, a hypoglycemic agent, significantly reversed most of the Cd effects, enhanced fecal excretion of Cd and potentiated urinary and fecal elimination of Cd by calcium trisodium diethylenetriaminepentaacetate (CaNa3DTPA), a commonly used metal chelator. However, the restoration of Cd-induced alterations in carbohydrate metabolism was not related to elimination of Cd from the tissues.

Distribution of cadmium in body organs and hepatic metallothionein content following chelation therapy.

1. Calcium trisodium diethylene triamine penta-acetate (CaNa3DTPA), sodium 1,2 diaminocyclohexane tetra-acetate (Na2CDTA), triethylenetetramine hydrochloride (TETA.HCl) and sodium diethyldithiocarbamate (NaDDC) were investigated for their efficacy to mobilize cadmium (Cd) from various tissues and hepatic metallothionein (MT) in Cd-exposed rats. 2. All chelating agents reduced the hepatic Cd burden but did not elicit any influence on other tissues, except that TETA.HCl lowered pancreas Cd and NaDDC increased brain Cd. 3. Cadmium-induced hepatic MT was lowered upon treatment with CaNa3DTPA while it increased further following treatment with NaDDC. 4. The chelating agents, in split doses, are capable of reducing the hepatic burden of Cd and altering the hepatic MT level. 5. While all the chelating agents decreased Cu content of hepatic MT, only CaNa3DTPA decreased its Zn content and TETA.HCl mobilized MT-bound Cd. 6. The administration of chelating agents alone in normal animals showed that NaDDC induced greater hepatic MT synthesis and increased MT-bound Zn than other chelating agents.

Influence of copper and iron on subacute cadmium intoxication in protein-malnourished rats.

Male albino rats maintained on low-protein (9%) diets were dosed intraperitoneally with 0.75 mg Cd/kg, as cadmium chloride, for 20 days. Groups of these animals were provided with diets supplemented with 40 ppm Cu, 400 ppm Fe or a combination of both during the exposure period. Hepatic and renal distribution of Cd, Zn, Cu, and Fe along with activity of acid and alkaline phosphatases and ribonuclease and glutathione content were studied. Uptake of Cd both in liver and in kidney was significant and was accompanied by increased Zn and depletion of Fe concentration. The Cu level remained unaltered. Dietary supplementation of Cu or Fe interacted effectively and influenced the metal distribution. Acid and alkaline phosphatases in both liver and kidney were inhibited by Cd exposure. However, Cu and/or Fe supplements could to a varying degree offset the Cd-induced inhibition. Cadmium exposure did not, however, elicit any effect on hepatic and renal ribonuclease activity of low-protein-fed animals. The glutathione concentration registered profound increase on Cd exposure, possibly to act as a defence mechanism.