Membrane potassium channels and human bladder tumor cells: II. Growth properties.

These experiments were done to determine the effect of glibenclamide and diazoxide on the growth of human bladder carcinoma (HTB-9) cells in vitro. Cell growth was assayed by cell counts, protein accumulation, and 3H-thymidine uptake. Glibenclamide added at 75 and 150 microM for 48 hr reduced cell proliferation. Dose-inhibition curves showed that glibenclamide added for 48 hr reduced cell growth at concentrations as low as 1 microM (IC50 = 73 microM) when growth was assayed in the absence of added serum. This microM-effect on cell growth was in agreement with the dose range in which glibenclamide decreased open probability of membrane KATP channels. Addition of glibenclamide for 48 hr also altered the distribution of cells within stages of the cell cycle as determined by flow cytometry using 10(-5) M bromodeoxyuridine. Glibenclamide (100 microM) increased the percentage of cells in G0/G1 from 33.6% (vehicle control) to 38.3% (P < 0.05), and it reduced the percentage of cells in S phase from 38.3% to 30.6%. On the other hand, diazoxide, which opens membrane KATP channels in HTB-9 cells, stimulated growth measured by protein accumulation, but it did not increase the cell number. We conclude that the sulfonylurea receptor and the corresponding membrane KATP channel are involved in mechanisms controlling HTB-9 cell growth. However, KATP is not rate-limiting among the signaling mechanisms or molecular switches that regulate the cell cycle.

[Studies of facilities with increased abortion rates in cattle]. / Untersuchungen in Betrieben mit gehäuftem Verwerfen beim Rind.

Cases of abortions in cattle were investigated using several different laboratory procedures. The purpose was to collect information on an individual animal and on a herd basis that would allow a correct etiological diagnosis and also the institution of prophylactic measures. The cause of the abortion was diagnosed in 30% of the cases and in 16.3% of the herds. Due to the complexity of the problem, there is no routine diagnostic procedure that can universally be recommended and applied. There was no association between the number of tests performed or the number of herd mates included in the diagnostic work-up and the diagnostic success rate. In order to make a more efficient use of the diagnostic procedures, a better understanding of the mechanisms leading to abortion, on an individual animal basis and on a herd basis, is required.