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Softening of thermoplastic polyurethanes (TPU) in a simulated body environment (37 degrees C n-saline) was studied as a function of composition, structure and resultant morphology of these (AB)n type block copolymers. The structural variations were attempted by changing chemical composition and molecular weight of both hard A and soft B segments and their weight ratio in the polymer. In addition, the influence of bulk and/or surface modifiers, such as "reacted-in" polysiloxanes and fluorinated polyalkylether glycols, was also investigated. The degree of softening, expressed as a percentage decrease of the elastic modulus (5% tensile modulus) upon two hours exposure to the testing environment, is significant, reversible and depends on the ratio of hard to soft segment and the extent of microphase separation. Since these parameters can be selected during the polymer synthesis and processing into desirable shapes, the degree of softening can thus be controlled. This softening at body temperature represents one of the most notable performance advantages of these biomaterials.

Deoxyribonucleic acid flow cytometry was performed on aspirated prostatic cells from 198 patients who had benign cytological or histological findings. Unsatisfactory acellular histograms were obtained from 10.6 per cent of the cases. Three-fourths of the satisfactory samples (more than 5,000 cells after subtracting debris) showed the expected single peak deoxyribonucleic acid diploid to near diploid histograms. Unexpectedly, the remaining samples were deoxyribonucleic acid aneuploid, most having 2 peridiploid peaks (deoxyribonucleic acid index 0.82 to 1.31). Usually, proliferation was low with less than 20 per cent hyperdiploid cells and with 2.5 +/- 1.5 per cent G2 cells. In 10 per cent of the single peak histograms there was evidence of inflammation, identified as an increase in hyperdiploid cells without an increased percentage of G2 cells but with a tail of high channel values. The aforementioned histogram features were considered to be benign findings. Seven per cent of the samples had deoxyribonucleic acid histograms suggestive of prostate cancer. Of these samples 7 had diploid or peridiploid aneuploid histograms with high proliferation (more than 20 per cent hyperdiploid cells with 8.5 +/- 3.8 per cent G2 cells), while 5 had histograms with deoxyribonucleic acid aneuploidy other than peridiploidy.

The levels of the low-molecular weight keratin 18 appearing in the voided urine of 130 healthy volunteers was studied using a new immunoradiometric assay for keratin 18 (IRMAK-18). Keratin 18 was detected in 79 urines with an average level of 2.5 +/- 4.7 ng./ml. The assay does not detect complex epidermal keratins or non-keratin intermediate filaments. Only 50% of the purified keratin added to urine could be recovered. The recovered keratin had the same molecular weight as the input molecules, implying that substances in the urine physically inhibited the assay rather than destroyed the keratin. The independent variables of cell count, dead cells, and protein concentration were not found to be important in evaluating the results. However, the urine concentration, as measured by creatinine, might be an important consideration for assessing the levels of keratin detected.

Deoxyribonucleic acid flow cytometry of bladder washings has proved to be a valuable procedure for the diagnosis and followup of patients with transitional cell carcinoma. However, for this procedure to gain maximal acceptance, it should be possible to use voided urine specimens instead of bladder washings. To evaluate this possibility we compared histogram findings for 114 bladder washings and 122 concomitantly obtained urine samples (voided and catheterized) from 89 consecutive patients who had active or a history of transitional cell carcinoma. Unsatisfactory histograms were obtained in 4 per cent of the urine samples and in 2.6 per cent of the bladder washing samples. The satisfactory rate for voided or catheterized urine samples was the same. We conclude that in this patient population satisfactory deoxyribonucleic acid histograms can be obtained from samples of voided urine.