A new method for chlorhexidine (CHX) determination: CHX release after application of differently concentrated CHX-containing preparations on artificial fissures

Aims of the study were (1) to establish a method for quantification of chlorhexidine (CHX) in small volumes and (2) to determine CHX release from differently concentrated CHX-containing preparations, varnishes, and a CHX gel applied on artificial fissures. CHX determination was conducted in a microplate reader using polystyrene wells. The reduced intensity of fluorescence of the microplates was used for CHX quantification. For verification of the technique, intra- and inter-assay coefficients of variation were calculated for graded series of CHX concentrations, and the lower limit of quantification (LLOQ) was determined. Additionally, artificial fissures were prepared in 50 bovine enamel samples, divided into five groups (A–E, n = 10) and stored in distilled water (7 days); A: CHX-varnish EC40; B: CHX-varnish Cervitec; C: CHX-gel Chlorhexamed; D: negative control, no CHX application; and E: CXH-diacetate standard (E1, n = 5) or CHX-digluconate (E2, n = 5) in the solution. The specimens were brushed daily, and CHX in the solution was measured. The method showed intra- and inter-assay coefficients of variation of <10 and <20%, respectively; LLOQ was 0.91–1.22 nmol/well. The cumulative CHX release (mean ± SD) during the 7 days was: EC40 (217.2 ± 41.8 nmol), CHX-gel (31.3 ± 8.5 nmol), Cervitec (18.6 ± 1.7 nmol). Groups A–C revealed a significantly higher CHX release than group D and a continuous CHX-release with the highest increase from day 0 to 7 for EC40 and the lowest for Chlorhexamed. The new method is a reliable tool to quantify CHX in small volumes. Both tested varnishes demonstrate prolonged and higher CHX release from artificial fissures than the CHX-gel tested

Expression of the plasma membrane Ca2+-ATPase in myogenic cells.

To study the physiological function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in intact cells, L6 myogenic cell lines stably overexpressing the human PMCA isoform 4CI (= human PMCA isoform 4b) were generated. Several independent L6 clones and controls stably transfected with the empty expression vector were analyzed in detail. The resting cytosolic calcium level in hPMCA4CI-overexpressing muscle cells (measured by the Fura-2 method) was significantly reduced by 20-30% compared with controls. This was shown in a cytosolic window of 1322 single cells (p < 0.01). Furthermore, the differentiation process of these cells was remarkably accelerated compared with control myoblasts and parental nontransfected L6 cells as assessed by multinucleated myotube formation and creatine phosphokinase activity elevation. After 4 and 6 days of differentiation, PMCA-overexpressing L6 cells from four independent clones displayed a 3- and 4-fold higher creatine phosphokinase activity compared with controls (n = 5, p < 0.02). These results may extend the concept of the function of the PMCA from simple prevention of calcium overload to an active involvement in intracellular calcium regulation with potentially important consequences for cellular functions

Short-term anti-plaque effect of two chlorhexidine varnishes

Background: Chlorhexidine (CHX) varnishes have been mainly used for the prevention of caries in high-risk populations. Reports regarding their anti-plaque effect on a clinical level are limited to non-existing as opposed to their microbiological impact on plaque formation. Aim: The aim of this preliminary investigation was to evaluate the anti-plaque effect of two CHX varnishes applied on sound enamel in relation to a positive control, a negative control and to one another. Methods: Sixteen healthy subjects volunteered for this randomized-controlled, single-blind, four-treatment-four-period crossover-designed clinical trial. A 3-day plaque re-growth model was used to determine de novo plaque accumulation following CHX rinsing, Cervitec (R) application, EC40 (R) application and no therapy. The amount of plaque was measured using the Quigley and Hein plaque index and "automatic image analysis'' (AIA). Results and Conclusions: Varnish treatment resulted in significantly higher plaque levels than CHX rinsing irrespective of the varnish that was used (p <= 0.002), implying that the latter is likely to remain the gold standard as an anti-plaque agent. However, highly significant differences were also found in favour of both varnish systems when compared with no therapy (p < 0.001), which indicates that varnish treatment is an effective means of inhibiting plaque formation in a short time span. Cervitec (R) exhibited slightly, yet significantly, higher plaque levels in comparison with EC40 (R) as determined by AIA (p=0.006). Large-scale trials with a longer observation period are necessary to substantiate these results