Modulation of cytoskeletal organization and cytosolic granule distribution by verapamil in amphibian urinary epithelia

cGMP abolishes agonist-induced [Ca(2+)](i) oscillations in human bladder epithelial cells

Cytosolic calcium oscillations may permit cells to respond to information provided by increases in intracellular Ca(2+) concentration ([Ca(2+)](i) ) while avoiding prolonged exposure to constantly elevated [Ca(2+)](i). In this study, we demonstrated that agonists could induce Ca(2+) oscillations in human bladder epithelial cells. Application of 10 microM acetylcholine or 200 nM bradykinin triggered an initial Ca(2+) transient that was followed by periodic [Ca(2+)](i) oscillations. The oscillations did not depend on extracellular Ca(2+). 8-Bromoguanosine 3',5'-cyclic monophosphate abolished acetylcholine- or bradykinin-induced oscillations. Elevation of cellular cGMP by dipyridamole, an inhibitor of cGMP-specific phosphodiesterase, also terminated the [Ca(2+)](i) oscillations. The inhibitory effect of cGMP could be reversed by KT-5823, a highly specific inhibitor of protein kinase G (PKG), suggesting that the action of cGMP was mediated by PKG. Comparison of the effect of cGMP with that of xestospongin C, an inhibitor of the inositol 1,4,5-trisphosphate (IP(3)) receptor, revealed similarities between the action of cGMP and xestospongin C. Therefore, it is likely that cGMP and PKG may target a signal transduction step(s) linked to IP(3) receptor-mediated Ca(2+) release.

S-phase fraction and nuclear size in long term prognosis of patients with breast cancer

BACKGROUND

S-phase fraction (SPF) predicts the prognosis of patients with breast cancer independently of tumor size, axillary metastasis, estrogen receptor (ER) and progesterone receptor (PgR), and patient age. Whether SPF is best measured by DNA labeling index (SPF-LI) or by flow cytometry (SPF-Flow) and what is the relative efficacy of SPF versus histopathologic characteristics for prognosis have remained unanswered questions.

METHODS

The authors studied 845 women with Stages I-II disease classification for years 1975-1990 with end results data, who were treated surgically with axillary lymph node dissection by an in vitro DNA labeling index protocol with tritiated thymidine or 5-bromo-2'-deoxyuridine and whose SPF was measured microscopically. Nuclear size was estimated with a calibrated optical grid as less than 11 microns, 11-14 microns, or greater than 14 microns. DNA flow cytometry was performed on fresh or paraffin embedded tissue; ER and PgR were performed by cytosol assay. Kaplan-Meier survival plots and multivariate analysis were used for comparisons.

RESULTS

Tumor size, axillary lymph nodal status, SPF-LI, nuclear size, and ER all related strongly to breast cancer specific survival and relapse free survival. PgR was less effective. Lymph node status and tumor size predicted long term survival; differences for other variables largely disappeared by 10 years. By multivariate analysis, axillary lymph node status, tumor size, and ER were independently prognostic for disease specific, relapse free survival. A strong trend was found for nuclear size. PgR, DNA ploidy, and SPF did not contribute to prognosis independently. Nuclear size was the strongest independent predictor in patients with negative axillary lymph nodes.

CONCLUSIONS

The number of positive axillary lymph nodes, tumor size, ER, and nuclear size were the strongest predictors of prognosis for patients with breast cancer. Only tumor size and lymph node status predicted the long term risk of metastasis.

Distribution and morphology of sacral spinal cord neurons innervating pelvic structures in Xenopus laevis

Relatively little is known about the organization of neural input to pelvic viscera in amphibia. In this study, sacral spinal efferent neurons were labeled in Xenopus laevis frogs by application of horseradish peroxidase (HRP) to the tenth spinal nerve, to pelvic musculature, or to the pelvic nerve. DiI was applied to the pelvic nerve with similar results. Labeled spinal neurons were located in the intermediate gray or in the ventral horn. Neurons in the tenth dorsal root ganglion, but not in the spinal cord, were labeled after application of HRP or DiI to the pudendal nerve. The labeled neurons in the spinal cord intermediate gray were in a position comparable to that of the mammalian sacral parasympathetic nucleus (SPN). Two apparent subdivisions included 1) a medial cluster of cells with mediolaterally oriented dendrites and 2) a lateral group with dorsoventrally oriented dendrites. An intermediate group, not clearly classed with the other two, was also identifiable. In some cases, labeled tenth nerve primary afferents were seen in contact with efferent neurons of the intermediate gray. Labeled neurons in the ventral horn medial to the lateral motor column were small, with dendrites oriented mediolaterally, in a position comparable to that of the mammalian Onuf's nucleus. The peripheral targets of DiI-labeled pelvic nerve axons were the compressor cloaca muscle, cloaca, and bladder. DiI-labeled pudendal nerve axons distributed peripherally to cloacal lip and medial thigh integument. These data suggest that the pudendal nerve in amphibians is purely sensory and that both somatic and autonomic motor axons traverse the pelvic nerve.

Surface membrane remodeling following removal of vasopressin in toad urinary bladder

Vasopressin (ADH) increases transepithelial water flow in renal epithelia by a process that involves the insertion of water channels into the apical membrane. The objective of the present study was to examine membrane surface remodeling under conditions that promote the recovery of water channels. Hemibladders were set up as sacs with an imposed osmotic gradient. The control sacs received no hormone treatment, whereas the other sacs were stimulated with 100 mU/ml ADH for 10 or 15 min to induce exocytosis and enhanced water flow. ADH was then washed from the tissues with fresh buffer rinses to abolish the hormone actions. These tissues were then allowed to recover for 15, 30 and 60 min. During this time water channels are recovered intracellularly by a process of endocytosis. This time period was called the retrieval period. At specified time intervals, tissues were fixed and processed for SEM or embedded in epon for ultrathin sectioning for TEM studies. Control tissues, regardless of the length of time, showed little or no sign of surface remodeling that was indicative of endocytosis during pre- or post-buffer washes, whereas the ADH-treated tissues showed a time-dependent remodeling of the apical membrane during activation and following removal of the hormone during the retrieval period. At the 10 min retrieval period, greater than 47% of the granular cells showed extensive surface remodeling. By 30 and 60 min posthormone treatment during recovery, fewer than 23% of granular cells showed signs of surface membrane changes. During retrieval the apical membrane undergoes a transition with a loss of both microridges and microvilli prior to membrane restoration. These observations suggest that apical membrane remodeling is crucial for the restoration of membrane permeability following hormone activation and termination.

Bromodeoxyuridine labeling for S-phase measurement in breast carcinoma

BACKGROUND

The S-phase fraction relates to proliferation, an important determinant of tumor behavior, and has been measured most accurately with the DNA precursor tritiated thymidine (TT). The TT labeling index (LI) is a strong stage-independent prognostic indicator for breast carcinoma. The thymidine analogue 5-bromodeoxyuridine (BrdU) is also incorporated into DNA and has the advantage over TT of immunohistochemical detectability rather than requiring autoradiography, but it is less well studied in breast carcinoma. This report demonstrates the equivalence of TT and BrdU LI and explores the relationships between LI and other biologic measurements.

METHODS

The LI of 234 consecutive breast carcinomas were measured with TT as was a subsequent series of 450 cases with BrdU, both by incubation in vitro.

RESULTS

The mean BrdU LI was 6.4 +/- 0.3% in comparison with 6.9 +/- 0.4% in the prior TT series. LI was unaffected by storage for 24 hours at 4 degrees C before labeling with BrdU. The BrdU and TT LI both correlated: (1) positively with tumor size, histologic type, nuclear size, the number of axillary metastases, the level of DNA ploidy, and the percent S-phase by flow cytometry and (2) negatively with the age of the patient and the levels of estrogen receptor and progesterone receptor measured either by ligand binding or by immunohistochemistry.

CONCLUSIONS

BrdU labeling in vitro was an advantageous method for measuring S-phase fraction in breast carcinoma that produced results comparable to those from TT labeling. It should be equally effective for breast cancer kinetic classification and prognosis and is a suitable standard to evaluate newer methods for measuring cellular proliferation.