John C. Houck

Lymphocyte DNA Synthesis Inhibition

A specific endogenous inhibitor for lymphocyte DNA synthesis that can be isolated from the lymphoid system and which is probably cell specific is described. The inhibitor is thermolabile, is destroyed by trypsin, and has a mass of about 30,000 to 50,000 daltons.

Induction of collagenolytic and proteolytic activities by anti-inflammatory drugs in the skin and fibroblast

Abstract The administration of cortisol, oxyphenylbutazone and indomethacin to rats results in a marked and abrupt loss of cutaneous collagen from these animals. This collagen loss was associated with the appearance of both collagenolytic and proteolytic activities in the extracellular, extrafibrillar compartment of the skin. Cycloheximide and 5,5-diphenylhydantoin pretreatment inhibited both the cutaneous collagen losses and the appearance of these enzyme activities in the skin. Kinetic studies have shown that within 4 hr after anti-inflammatory drug administration, peak concentrations of both collagenolytic and proteolytic activities were reached in the skin. These enzymatic activities were profoundly depressed by simultaneous administration of puromycin, cycloheximide and actinomycin-D. Monolayers of cultured strain-L fibroblasts neither contained nor released either proteolytic or collagenolytic activities. Within 4 hr after administration of cortisol, idomethacin or oxyphenylbutazone, both types of enzymatic activities appeared within these cell cultures.

Induction of collagenolytic and proteolytic activities in rat and human fibroblasts by anti-inflammatory drugs.

Confluent monolayers of either mouse or diploid human fibroblasts contained no measurable amounts of either collagenolytic (pH 5.5) or proteolytic (pH 7.5) activities. Within a few hours after exposure of these cells to antiinflammatory drugs, significant amounts of these enzymatic activities were demonstrable extracellularly. These activities were profoundly decreased in cultures simultaneously treated with the anti-inflammatory drugs and cycloheximide or actinomycin D.

The biological properties of peptides derived from fibrinogen

Abstract The action of thrombin on fibrinogen results in the release of two acidic peptides and fibrin monomers. Fibrin monomer, under proper conditions of salt concentration, pH, etc., can then aggregate to an insoluble macromolecule, the fibrin clot. The release of acidic peptides, called A and B, is mandatory prior to clot formation. A study in vivo and in vitro has shown that certain of these peptides have potent biological activities in the stimulation of smooth muscle contraction. The injection of anti-inflammatory drugs into rats induces in the skin an enzyme(s) capable of converting fibrinogen to fibrin via a different mechanism. This enzyme(s) has been shown ‘not’ to be thrombin, and only one peptide is released from the fibrinogen. The physiological activity of this peptide has also been evaluated.

Rabbit thyroid metabolism in tissue and organ culture.

Summary and conclusions 1. Organ cultured rabbit thyroid glands are able to concentrate I-131 from culture media and can incorporate the iodide into MIT, DIT, and T4. 2. TSH accelerates all of these processes in organ cultured rabbit thyroid glands. 3. No evidence for the incorporation of C14 tyrosine or C14 phenylalanine into MIT, DIT, and T4 could be found in histologically normal and apparently metabolically normal organ cultured thyroid glands. 4. The most probable explanation for this lack of incorporation of C14 phenylalanine and C14 tyrosine is that only a small proportion of tyrosine incorporation into thyroid protein is found as residues of thyroglobulin appropriate for iodination and generation into thyroid hormones. Thus the specific activity of the radioactive tyrosine in MIT, DIT, and T4 would be too low to measure in spite of culturing in tyrosine-free media.

Metabolism of 1-131 by Human Thyroid Tissue in Organ Culture.

Summary The incubation of human thyroid tissue in tissue culture medium containsing I-131 by an organ culture technique is described. The histology of the gland was preserved up to 7 days. Labeled MIT, DIT, and T4 were present following papain hydrolysis of the tissue. Addition of TSH to the culture medium apparently accelerated the conversion of MIT to DIT as well as the rate of coupling of DIT to form T4 and released T4 from the thyroid tissue into the medium. No labeled amino acids were detected in the culture medium when TSH was not added.