Simultaneous detection of seven drugs of abuse by the Triage panel for drugs of abuse.

This novel, competitive immunoassay simultaneously detects seven drugs of abuse in urine. A urine sample is placed in contact with lyophilized reagents, the reaction mixture is allowed to come to equilibrium (10 min), and then the whole mixture is applied to a solid phase that contains various immobilized antibodies in discrete drug-class-specific zones. After a washing step, the operator visually examines each zone for the presence of a red bar. The method incorporates present threshold concentrations that are independent for each drug. In the absence of drug or in the presence of drug in quantities less than the threshold concentration, no colored bar is visible. Samples containing drug(s) at or above the threshold concentration cause a red bar to appear for the appropriate drug(s). Positive and negative procedural control zones are incorporated into each determination. The performance of the assay methodology matches that of instrumented immunoassay systems.

The growth of cultured rabbit articular chondrocytes is stimulated by pituitary growth factors but not by purified human growth hormone or ovine prolactin.

Recent reports describing a direct stimulation by GH of bone and cartilage growth led us to compare the in vitro mitogenic effects of highly purified human GH and PRL and two pituitary-derived growth factors in rabbit articular chondrocytes. These preparations were tested for their ability to promote [3H]thymidine incorporation into growth-arrested monolayer chondrocyte cultures and were also assayed in cell growth experiments. The factors tested included 22,000-dalton and 20,000-dalton human GH ovine PRL, glycosylated ovine PRL, bovine pituitary fibroblast growth factor (bpFGF), and a partially purified pituitary growth factor distinct from bpFGF. We found that no significant mitogenic effect was produced by either of the human GH or PRL preparations. Both of the pituitary-derived growth factors were potent mitogens, with bpFGF active at a final medium concentration of 10 pg/ml. These studies support the large body of evidence that GH has no significant direct in vitro effect on chondrocyte growth. The very potent effects of the pituitary-derived growth factors raise the possibility that their presence in GH preparations may be responsible for the in vitro mitogenic effects attributed to these preparations.

Epidermal growth factor inhibits growth while increasing the expression of an ecto-Ca2+-ATPase of a human hepatoma cell line.

We have obtained a cloned cell line (Li-7A) from primary cultures of a human hepatoma xenograft (Li-7). Li-7A was able to grow in the absence of serum. Growth was stimulated 0-3 fold by addition of newborn calf serum, but was inhibited in DME/F12 media containing nine growth factors. The ectoMg2+-ATPase was 1.5-2 fold higher than the ectoCa2+-ATPase activity in cells grown in media with or without serum. In cells grown in media supplemented with the nine factors, the ectoCa2+-ATPase activity exceeded the ectoMg2+-ATPase, and there was also a 5-10 fold increase in its specific activity. Inhibition of growth was due to epidermal growth factor alone. The increased expression of the ectoCa2+-ATPase was absolutely dependent on EGF, but also required hydrocortisone and cholera toxin. The characteristics of Li-7A cells make it a suitable system for studying both the mechanism of action of EGF and plasma membrane ATPases.

A leukemia virus-related protein in the murine pancreas.

A protein that has been detected in the granules of islet cells in the murine pancreas is similar but not identical to the endogenous murine leukemia virus envelope protein gp70. The pancreatic protein was detected by several immunological methods using both polyclonal and monoclonal anti-murine gp70. On purification by affinity chromatography, it was shown to be different from murine gp70 in its subcellular location and its molecular size and the size of its precursor and by the effect of various reagents on its immunological activity as determined by the ELISA assay.

Serum stimulates Na entry and the Na-K pump in quiescent cultures of epithelial cells (MDCK).

The growth of an epithelial canine kidney line (MDCK) was reversibly arrested by gradually lowering the serum concentration in the medium over a 3-day period. The cells were demonstrably quiescent by autoradiography after an additional 24 hours in serum-free media. Addition of fresh serum produced DNA synthesis after an 18-hour lag period. The quiescent cells then grew to confluency retaining their transport capacities as seen by the formation of "domes." This system allows for measurement of monovalent ion fluxes and its relationship to growth regulation. The addition of fresh serum to quiescent MDCK cells increased the uptake of 86Rb, a measure of Na-K pump activity. This stimulation was mediated by increased uptake of Na into the cells. Serum-stimulated DNA synthesis was blocked by the addition of ouabain in concentrations that inhibit the Na-K pump. Serum appears to stimulate growth in epithelial cells by increasing the amount of intracellular Na available to the Na-K pump. Monovalent ion transport may play a role in the regulation of epithelial cell proliferation.