Slow spontaneous [Ca2+] i oscillations reflect nucleotide release from renal epithelia.

Renal epithelia can be provoked mechanically to release nucleotides, which subsequently increases the intracellular Ca(2+) concentration [Ca(2+)](i) through activation of purinergic (P2) receptors. Cultured cells often show spontaneous [Ca(2+)](i) oscillations, a feature suggested to involve nucleotide signalling. In this study, fluo-4 loaded Madin-Darby canine kidney (MDCK) cells are used as a model for quantification and characterisation of spontaneous [Ca(2+)](i) increases in renal epithelia. Spontaneous [Ca(2+)](i) increases occurred randomly as single cell events. During an observation period of 1 min, 10.9 +/- 6.7% (n = 23) of the cells showed spontaneous [Ca(2+)](i) increases. Spontaneous adenosine triphosphate (ATP) release from MDCK cells was detected directly by luciferin/luciferase. Scavenging of ATP by apyrase or hexokinase markedly reduced the [Ca(2+)](i) oscillatory activity, whereas inhibition of ecto-ATPases (ARL67156) enhanced the [Ca(2+)](i) oscillatory activity. The association between spontaneous [Ca(2+)](i) increases and nucleotide signalling was further tested in 132-1N1 cells lacking P2 receptors. These cells hardly showed any spontaneous [Ca(2+)](i) increases. Transfection with either hP2Y(6) or hP2Y(2) receptors revealed a striking degree of oscillations. Similar spontaneous [Ca(2+)](i) increases were observed in freshly isolated, perfused mouse medullary thick ascending limb (mTAL). The oscillatory activity was reduced by basolateral apyrase and substantially lower in mTAL from P2Y(2) knock out mice (0.050 +/- 0.020 events per second, n = 8) compared to the wild type (0.147 +/- 0.018 events per second, n = 9). These findings indicate that renal epithelia spontaneously release nucleotides leading to P2-receptor-dependent [Ca(2+)](i) oscillations. Thus, tonic nucleotide release is likely to modify steady state renal function.

Effect of spreader and accessory cone size on density of obturation using conventional or mechanical lateral condensation.

A simulated curved root canal in a resin block was enlarged to size 40 and used to compare the depth of accessory cone penetration and weight of obturation occurring with the use of different obturation techniques and spreader-accessory cone combinations. Twelve groups, each consisting of 10 obturations, were created. A conventional lateral condensation technique was used in six groups and a mechanical lateral condensation (MLC) technique was used in six matched groups. The six spreader-accessory cone combinations were either Fine-Medium or Fine nickel-titanium finger spreaders with either Fine, Medium-Fine, or size 25 accessory cones. Seven accessory cones were placed in every obturation. The depth of each accessory cone penetration into the canal was measured. After each obturation the gutta-percha was removed, sectioned, and the resulting mass was weighed. The means for each variable were determined and compared. MLC fills were significantly heavier and had greater depth of penetration on average than conventional lateral condensation. The best combination for heavy fills was MLC, Fine-Medium spreaders, and Fine accessory cones. The greatest mean accessory cone depth occurred with MLC, Fine-Medium spreaders, and size 25 accessory cones.

A description of an alternative method of lateral condensation and a comparison of the ability to obturate canals using mechanical or traditional lateral condensation.

A modification of the lateral condensation of gutta-percha technique is described. After master cone adaptation is completed a nickel-titanium finger spreader placed in a reciprocating-action handpiece is used to laterally displace cold gutta-percha, creating space for accessory cones. The technique produces a compacted mass of gutta-percha in the canal, which can usually be removed in toto if corrections are required. This technique was compared with lateral condensation by obturating curved or straight canals in acrylic blocks, then removing, sectioning, and weighing the gutta-percha mass. Two different operators were also compared. Results were analyzed using a factorial ANOVA test. The experimental obturations were significantly heavier on average than were lateral condensation fills (p < 0.001). One operator's obturations were consistently heavier than the others (p < 0.001). There was no significant difference between the weight of fills in straight and curved canals.

An investigation of the cognitive and perceptual dynamics of a colour-digit synaesthete.

L, a 47-year-old female of Choctaw descent, was first identified as a potential synaesthetic++ on the basis of self-report data regarding digit-colour associations. Upon completion of the identification procedures typified in the literature, it was concluded that L met the classic memory-performance criteria used to identify synaesthetic ability. A series of Stroop-type tasks were then performed to identify the dynamics of her synaesthetic experiences. The results of these analyses provided three findings of note. First, the clear pattern of response-time differences between L and the control group suggests that tasks designed to produce involuntary divisions of attention can be an effective means by which to demonstrate that synaesthetic experiences are involuntary but elicited. Second, the significantly slower performance by L on a negative-priming Stroop list shaped around her colour-digit associations indicates the presence of a lexical component in her synaesthetic experience. Third, the use of a manual colour-classification task for which a verbal response was not employed served to confirm the presence of a lexical component in L's synaesthetic experiences. The implications of these results for current synaesthetic theories are then discussed. Finally, a clustering solution of a portion of L's colour-digit experiences is presented, along with the ramifications of its results on the nature of L's perceptual experience.