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Pervanadate and permolybdate are irreversible protein-tyrosine phosphatase inhibitors, with IC50 values of 0.3 and 20 microM, respectively, in intact cells. Maximal inhibition was obtained within 1 min at higher concentrations of the compounds. They induced prominent changes in the phosphorylation status of the gap junction protein, connexin43. These effects were utilized as model systems to assess the stability and inactivation of the compounds. Although the concentrated stock solutions were relatively stable, the diluted compounds were unstable. The biological activity had decreased to 20-30% after 6 h of incubation in a phosphate buffer, 1 h in phosphate buffer with 10% fetal calf serum, and 1-3 minutes in culture medium. Thiols reacted rapidly with the compounds and inactivated them (initial reaction rates with cysteine: permolybdate > pervanadate > H2O2). Catalase inactivated the compounds, and permolybdate was the more sensitive. The cells inactivated permolybdate faster than pervanadate. Cellular inactivation of permolybdate, and to a lesser degree pervanadate, appeared to be partly dependent on catalase and thiols. However, a general decrease in cellular thiols was not the mediator of the biological effects of pervanadate or permolybdate. Mathematical modeling of the thiol reactivity suggested that monoperoxovanadate at maximum could possess 20% of the biological activity of diperoxovanadate.

Fourteen patients with known muscle invasive bladder carcinoma were examined with computed tomography (CT) before and five to seven days after diagnostic transurethral resection (TUR). The CT examinations included pre- and postcontrast series. In order to standardize the technique, we examined on a distended bladder. No significant changes occurred for the whole group after TUR. Individual changes were seen. In six patients the largest measured area of the bladder tumor increased after resection and in four the largest measured thickness increased, and this should be borne in mind when CT is used to evaluate tumor response to treatment. Perivesical changes occurred only after extensive diathermy or perforation. They did not show contrast enhancement and could therefore not be mistaken for tumor growth.

Computed tomography (CT) scans of the urinary bladder were taken before and in combination with intravenous contrast medium injection in 30 patients with invasive bladder carcinoma. Three different ways of injecting the same amount of intravenous contrast material were used in three groups, each consisting of ten patients. In the first group the contrast medium was given during 90 seconds, in the second group during 40 seconds and in the third one, the first half during 20 seconds and the second half during 90 seconds. The attenuation in the tumors and in the bladder wall was measured in Hounsfield units. Independent of injection method, all tumors showed significantly higher contrast enhancement than the bladder wall when the injection was terminated. The difference in contrast enhancement was greatest in the group where the shortest injection time was used and greatest immediately after the conclusion of the injection. The difference in contrast enhancement between tumor and bladder wall was visible on the monitor in all cases.

A review of the literature of time-dose relationships of liposarcoma is given. The radiotherapeutic data on 15 measurable liposarcoma sites, together with 45 sites collected from the literature, are subjected to a Strandqvist plot analysis using the modified Ellis' formula TSD = D.T-a. The recovery coefficient a is thought to be rather high, of the order a = 0.5. This suggests that the use of a few large fractions in therapy may be beneficial.