Prediction of spontaneous ureteral calculous passage by an artificial neural network.

PURPOSE: Although a consensus exists that small stones presenting in the distal ureter have a good probability of spontaneous passage, it is difficult to predict in individuals whether a particular ureteral stone would pass or require intervention. If an accurate judgment were made at presentation on the likelihood of stone passage, patients would receive immediate intervention for the stone or be notified of a more appropriate time at which to expect passage. We used an artificial neural network to evaluate data in patients with ureteral calculi to predict whether a stone would pass spontaneously or require intervention. MATERIALS AND METHODS: Data were collected from the records of 181 patients presenting with colic due to a ureteral calculus. Patient input factors included age, sex, race, marital status, insurance, stone side, level and size, hydronephrosis and obstruction grades, duration of symptoms before presentation, serum creatinine, history of stone passage or intervention and nausea, vomiting or fever. Outcomes evaluated were stone passage or intervention. Data were entered into a neural network created using commercially available computer software. RESULTS: A set of 125 patients from the database was used for training the network. The network correctly predicted outcome in 38 of the remaining 55 patients (76%) used for testing. In the 25 cases in which stones passed spontaneously sensitivity was 100%. Duration of symptoms before presentation was the most influential factor in network ability to predict accurately stone passage, followed by hydronephrosis grade. CONCLUSIONS: An artificial neural network may be used to predict accurately the probability of spontaneous ureteral stone passage. Using such a model at presentation may help to determine whether a patient should receive early intervention for a stone or expect a lengthy interval before stone passage.

In vivo and in vitro iron deficiency reduces protein kinase C activity and translocation in murine splenic and purified T cells.

We investigated the effects of iron deficiency anemia, iron repletion, and iron chelation by deferoxamine on protein kinase C (PKC) activity, an enzyme that plays a crucial role on T lymphocyte proliferation. The study involved 23 control (C), 18 pairfed (PF), and 24 iron deficient (ID) mice or ID mice that were repleted for 3 (n = 14), 7 (n = 17), or 14 (n = 14) days. The low iron (0.09 mmol iron/kg) and iron-supplemented (0.9 mmol iron/kg) diets were fed to mice for 53 days. Mean hemoglobin, hematocrit, and liver iron stores of ID mice were one third of those of C mice. Lymphocyte proliferation was reduced (P < 0.05) in spleen and purified T cells in ID but not PF mice. In concanavalin A, phytohemagglutinin, and anti-CD3 antibody-treated and untreated cells that were incubated in serum-free and serum-containing medium, PKC activity was significantly (P < 0.05) reduced in ID but not PF mice and returned to normal before correction of anemia. In mitogen-treated cells, while the ratios of membrane-bound to cytosol activity increased nearly seven-fold (from 0.4-0.63 in resting cells to 1.43-7.23) in spleen cells from C, PF, and repleted mice and 11-fold in T cells (P < 0.005), they remained below 1 in ID mice suggesting reduced translocation. In vitro iron chelation by deferoxamine for 120 min prior to cell activation reduced (P < 0.05) PKC activity by 46-60% in C and PF and 28-53% in ID mice. The data suggest that: 1) it is iron-deficiency but not anemia or differences in the proportion of immunocompetent T cells that reduced PKC activity in cells from ID mice; 2) reduced PKC translocation may play an important role on altered lymphocyte proliferation and associated functions in iron-deficient individuals.

BFU-E colony growth in response to hydroxyurea: correlation between in vitro and in vivo fetal hemoglobin induction.

Patients with sickle-cell anemia treated with hydroxyurea may have significant reduction in frequency and severity of pain episodes. However, previous clinical trials show a variable response to hydroxyurea. Criteria which can be used to select patients who are likely to respond to hydroxyurea treatment would be useful. Our laboratory has previously demonstrated an inverse linear relationship between the total number of burst-forming unit-erythroid (BFU-E) colonies and fetal hemoglobin levels in sickle-cell patients treated with hydroxyurea. In the present report, an in vitro cell culture system was established to evaluate the effects of hydroxyurea on BFU-E colony growth and induction of fetal hemoglobin production. Five Hb SS patients who were not previously treated with hydroxyurea and three Hb SS patients who failed to respond to hydroxyurea treatment were included in the study. The results show that the number of BFU-E colonies is decreased from 153.7 to 7.2 per 3 x 10(5) mononuclear cells, whereas fetal hemoglobin levels were increased from 5.1 to 19.4% in the presence of hydroxyurea in vitro in cultured erythroid progenitors, which were derived from 5 patients before treatment. The number of BFU-E colonies decreased from 153.7 to 2.0 per 3 x 10(5) mononuclear cells in the in vitro cultures obtained from serial peripheral blood samples over a 9- to 20-week period of oral hydroxyurea therapy. A simultaneous rise in fetal hemoglobin level from 10.2 to 28.6% in the peripheral blood over the same period of hydroxyurea therapy was also observed. Our results demonstrate that the increase in fetal hemoglobin levels in cells treated with hydroxyurea in vitro is comparable to the rise of fetal hemoglobin production following hydroxyurea therapy in these patients. On the contrary, these findings were not observed in three previously non-responsive sickle-cell patients. These results suggest that the changes in number of BFU-E colonies and fetal hemoglobin levels after in vitro exposure to hydroxyurea may be a useful approach to select sickle-cell patients who will respond to hydroxyurea therapy.

Embryonic stem cells express neuronal properties in vitro.

Mouse embryonic stem (ES) cells cultured as aggregates and exposed to retinoic acid are induced to express multiple phenotypes normally associated with neurons. A large percentage of treated aggregates produce a rich neuritic outgrowth. Dissociating the induced aggregates with trypsin and plating the cells as a monolayer results in cultures in which a sizable percentage of the cells have a neuronal appearance. These neuron-like cells express class III beta-tubulin and the neurofilament M subunit. Induced cultures express transcripts for neural-associated genes including the neurofilament L subunit, glutamate receptor subunits, the transcription factor Brn-3, and GFAP. Levels of neurofilament L and GAD67 and GAD65 transcripts rise dramatically upon induction. Physiological studies show that the neuron-like cells generate action potentials and express TTX-sensitive sodium channels, as well as voltage-gated potassium channels and calcium channels. We conclude that a complex system of neuronal gene expression can be activated in cultured ES cells. This system should be favorable for investigating some of the mechanisms that regulate neuronal differentiation.

FGF and EGF are mitogens for immortalized neural progenitors.

Individual neural progenitors, derived from the external germinal layer of neonatal murine cerebellum, were previously immortalized by the retrovirus-mediated transduction of avian myc (v-myc). C17-2 is one of those clonal multipotent progenitor cell lines (Snyder et al., 1992, Cell 68: 33-51; Ryder et al., 1990, J. Neurobiol. 21:356-375). When transplanted into newborn mouse cerebellum (CB), the cells participate in normal CB development; they engraft in a cytoarchitecturally appropriate, nontumorigenic manner and differentiate into multiple CB cell types (neuronal and glial) similar to endogenous progenitors (Snyder et al., 1992, as above). They also appear to engraft and participate in the development of multiple other structures along the neural axis and at multiple other stages (Snyder et al., 1993, Soc. Neurosci. Abstr. 19). Thus conclusions regarding these immortalized progenitors may be applicable to endogenous neural progenitors in vivo. To help identify and analyze factors that promote differentiation of endogenous progenitors, we first investigated the ability to maintain C17-2 cells in a defined, serum-free medium (N2). The cells survive in vitro in N2 but undergo mitosis at a very low rate. Addition of epidermal growth factor (EGF), however, either from mouse submaxillary gland or the human recombinant protein, appreciably stimulates thymidine incorporation and cell division approximately threefold. Basic fibroblast growth factor (bFGF) is an even more potent mitogen, promoting thymidine incorporation, cell division, and a net increase in cell number equal to that in serum. Both EGF and bFGF are active at very low nanomolar concentrations, suggesting that they interact with their respective receptors rather than a homologous receptor system. The findings demonstrate that C17-2 cells can be maintained and propagated in a fully defined medium, providing the basis for analysis of other growth and differentiation factors. That EGF and particularly bFGF are mitogenic for these cells is in accord with recent observations on primary neural tissue (Reynolds and Weiss, 1992, Science 255:1707-1710; Kilpatrick and Bartlett, 1993, Neuron 10:255-265; Ray et al., 1993, Proc. Natl. Acad. Sci. USA 90:3602-3606) suggesting that bFGF and EGF responsiveness may be fundamental properties of neural progenitors.

Zinc blocks apical membrane anion exchange in gallbladder epithelium.

The effect of Zn2+ on Cl- transport across the apical membrane of Necturus gallbladder epithelium was studied with intracellular conventional and Cl(-)-selective microelectrodes and measurements of apparent base secretion. Most studies were done on tissues incubated in HEPES-buffered solutions; intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were elevated by adding to the serosal bathing medium either theophylline or dibutyryl cAMP. Under these conditions, Zn2+ (added to mucosal solution) had no effect on membrane voltages, apparent cell membrane resistance ratio, or rapid depolarization induced by reducing mucosal solution [Cl-]. However, Zn2+ reduced the rate of cell membrane repolarization during exposure to the low-Cl- solution and decreased significantly the rate of fall of intracellular Cl- activity (alpha Cli) elicited by lowering mucosal solution [Cl-]. Both effects were time dependent, became significant after 10 min, and were slowly reversible. In tissues not stimulated by cAMP and incubated in a HCO3-CO2-buffered solution, Zn2+ also reduced the rate of fall of alpha Cli on lowering mucosal solution [Cl-]. Base secretion from cells to mucosal solution was assessed from changes in mucosal pH on stopping superfusion with a poorly buffered (1 mM HEPES) medium in the presence of 1 mM amiloride or a Na(+)-free medium, without cAMP stimulation. Exposure to Zn2+ reduced the alkalinization observed with both protocols. We conclude that Zn2+ has no effect on apical membrane Cl- conductance stimulated by cAMP and inhibits Cl(-)-HCO3- exchange. The slow onset and reversal of the effects suggests slow binding of Zn2+, a covalent modification of the exchanger, or an effect requiring Zn2+ transport to the cell interior.