An experimental model which permits independent changes in ureteral peristalic frequency and bolus volume was employed to explore the effects of autonomic agonists on ureteral bolus volume, peristaltic frequency, intraluminal pressure and flow volume in the dog. Norepinephrine caused an increase in ureteral peristaltic frequency, an elevation in intraureteral baseline and contractile pressure and a decrease in bolus volume, with a resultant decrease in the rate of fluid transport. Isoproterenol caused a decrease in ureteral peristaltic frequency, and a fall in intraureteral baseline and contractile pressure, or it completely abolished peristalsis and bolus formation. These changes were accompanied by an increase in the rate of fluid transport. Acetylcholine caused an increase in ureteral peristaltic frequency, an elevation of intraureteral baseline pressure but no change in contractile pressure, and a small decrease in bolus volume with a resultant small decrease in the rate of fluid transport. These data suggest that the autonomic nervous system may affect urine transport through the ureter by not only regulating peristaltic frequency but also by influencing bolus volume.

The p16sxuRe cyclin-dependent kinase (Cdk) inhibitor is now recognized as a major tumor suppressor that is inactivated by a variety of mechanisms in a wide range of human cancers. It is also implicated in the mechanisms underlying replicative senescence since p16sxuRe RNA and protein accumulate as cells approach their proscribed limit of population doublings in tissue culture. To obtain further evidence of its role in senescence, we have sought ways of overexpressing p16 sxuRe in primary human diploid fibroblasts (HDF). To circumvent the low transfection efficiency of primary cells we have exploited a recombinant form of the full-length p16sxuRe protein fused to a 16 amino acid peptide from the Drosophila antennapedia protein. This peptide has the capacity to cross both cytoplasmic and nuclear membranes allowing the direct introduction of the active protein to primary cells. Here, we show that antennapediatagged wild-type p16 sxuRe protein, but not a functionally compromised tumor-specific variant, causes G1 arrest in early passage HDFs by inhibiting the phosphorylation of the retinoblastoma protein. Significantly, the arrested cells display several phenotypic features that are considered characteristic of senescent cells. These data support a role for p16 sxuRe in replicative senescence and raise the possibility of using the antennapedia-tagged protein therapeutically.z 1998 Federation of European Biochemical Societies.

Topoisomerase II (Topo II) that decatenates newly synthesized DNA is targeted by many anticancer drugs. Some of these drugs stabilize intermediate complexes of DNA with Topo II and others act as catalytic inhibitors of Topo II. Simultaneous depletion of Topo IIα and Topo IIβ, the two isoforms of mammalian Topo II, prevents cell growth and normal mitosis, but the role of Topo II in other phases of mammalian cell cycle has not yet been elucidated. We have developed a derivative of p53-suppressed human cells with constitutive depletion of Topo IIβ and doxycycline-regulated conditional depletion of Topo IIα. The effects of Topo II depletion on cell cycle progression were analyzed by time-lapse video microscopy, pulse-chase flow cytometry and mitotic morphology. Topo II depletion increased the duration of the cell cycle and mitosis, interfered with chromosome condensation and sister chromatid segregation and led to frequent failure of cell division, ending in either cell death or restitution of polyploid cells. Topo II depletion did not change the rate of DNA replication but increased the duration of G 2. These results define the effects of decreased Topo II activity, rather than intermediate complex stabilization, on the mammalian cell cycle.

Experiments were carried out in the dog by the use of experimental procedure which permits to assess independently changes in uretheral peristaltic frequency, bolus volume and intraluminal pressure and flow volume in order to characterize a-adrenoceptor subtypes involved in regulation of ureteral urine transport. Norepinephrine caused an increase in ureteral peristaltic fregency, an elevation in intraureteral baseline and contractile pressure and a decrease in bolus volume, with a resultant decrease in the rate of fluid transport. Phenylephrine (al-agonist) and clonidine (a2-agonist) caused the effects similar to those of norepinephrine on peristaltic frequency, intraureteral baseline and contractile pressure, and bolus volume. Phentolamine (non-selective a-antagonist) and prazosin (a,-antagonist) caused a decrease in ureteral peristaltic frequency, and a fall in intraureteral baseline and contractile pressure, and yohimbine (a2-antagonist) abolished peristalsis and bolus formation. These changes were accompanied by an increase in the rate of fluid transport. These data suggest that the ureteral urine transport is controlled by activation of both al-and a2-adrenoceptors through regulation of peristaltic frequency and bolus volume, ureteral urine transport ; a-adrenoceptor subtypes