Inhibition of protein cross-linking in Ca2+-enriched human erythrocytes and activated platelets.

Treatment of human erythrocytes with Ca2+, in the presence of ionophore A23187, causes the formation of high molecular weight (greater than 10(6)) membrane protein polymers. This phenomenon, known to involve cross-linking of essentially all of the band 4.1 and 2.

Characteristics of separated epithelial and stromal subfractions of prostate: I. Rat ventral prostate.

These studies were initiated with the objective of isolating epithelial and stromal cells of human prostatic tissue in undamaged state, in order to study the cellular distribution of steroid receptors in benign prostatic hyperplasia (BPH) relative to normal prostate. Initial experiments showed that when BPH tissue immersed in tissue culture media was progressively fragmented by various cutting procedures, epithelial elements were selectively released as clumps of variable size and individual cells, but that a large percentage of these cells were damaged, as evidenced by their failure to exclude trypan blue (TB). These observations suggested that if tissue fragmentation were carried out under defined conditions that minimize cell damage, BPH subfractions might be obtained containing a large percentage of undamaged cells.

Characteristics of separated epithelial and stromal subfractions of prostate: II. Human prostate.

Surgical samples of human benign prostatic hyperplasia tissue (BPH) were fractionated into epithelial clumps and stromal fractions, using the "optimal" tissue dissociation procedure developed for rat prostate described in the preceding report. The separated cellular fractions were compared to control unfractionated tissue (wherein extracellular secretory products had been removed) with respect to the concentrations of androgen receptor and enzyme markers on a DNA basis; cell damage was also evaluated by light and electron microscopy (EM). EM revealed extensive cell damage in epithelial clumps and stromal fractions, which had appeared normal when examined by light microscopy.

Androgen and estrogen receptors in rat ventral prostate epithelium and stroma.

Estrogen and androgen receptors have been investigated in rat ventral prostate epithelium and stoma. High speed supernatants were prepared from unfractionated or fractionated prostates. Cytosols from intact rats were incubated with 2 nM 3H-estradiol (E2) in presence of 80 nM dihydrotestosterone (DHT), and cytosols from 1 day castrated rats were incubated with 2 nM 3H-DHT, at 0 C for 4 h.

Ca2+-dependent cross-linking processes in human platelets.

When platelet cytoplasmic Ca2+ is increased by the ionophore A23187 in the presence of the protease inhibitor leupeptin, there is the coincident appearance of a cross-linked polymer and the partial disappearance of monomeric protein and glycoprotein units. In the absence of leupeptin only 30% of the polymer was formed. The disappearance of monomeric protein bands, as detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis, is prevented by histamine, which as a pseudodonor amine is a known inhibitor of transglutaminase-catalyzed cross-linking [14C]Histamine, at a tracer concentration, is incorporated into the polymer as well as into myosin, glycoproteins IIb and III, actin and tropomyosin.