[Evaluation of the effect of three different Iranian industrial fruit juices on plaque PH]

Evaluation of cariogenic city of fruit juices as healthy snacks has special importance. The aim of this study was to evaluate the effect of 3 different Iranian industrial fruit juices on plaque pH. In this randomized clinical trial, 10 healthy dental students were selected based on the inclusion criteria namely the amount of streptococcus mutans and lactobacillus in the saliva, salivary secretion rate, buffering capacity of saliva, absence of active dental caries, absence of systemic disease and etc. Dental plaque pH in certain areas of the 4 mouth quadrants was measured by omega Metrohm microelectrode and digital pH meter before and 2 to 60 minutes after the consumption of Children orange juice, orange nectar with pulp, pineapple nectar and 10% sucrose solution. The pH curve at different time points was then drawn for each product. Data were analyzed statistically by repeated measures ANOVA [P<0.05]. The maximum drop in plaque pH occurred 2 minutes after consumption. The time spent below the critical pH was the longest for orange nectar with pulp [10.75 +/- 2.24] and shortest for pineapple nectar [3.46 +/- 1.14] .At final minutes of study, plaque pH returned to its baseline value after consumption of all fruit juices except for orange nectar with pulp]. After consumption of orange nectar with pulp, the mean plaque pH was significantly lower in comparison to other juices and the time spent under the critical plaque pH was the longest

[Comparing deproteinization methods for serum nitric oxide assay by Greiss reaction]

Nitric oxide [NO] is involved in numerous physiologic and phathophysiologic processes. Recently, further investigators have focused on serum NO determination. In our previous study, we validated a simple, cheap and rapid method for serum NO determination based on the Greiss reaction. Deproteinization is a necessary step for this reaction, thus, the present study was designed to assess different deproteinization methods for serum NO determination. Ten common protein precipitating chemicals including methanol, ethanol, zinc sulfate, methanol/diethyl ether, acetonitrile, TCA, PCA, sodium tangstate, ammonium sulfate and filter were used for deproteinization of 42 human sera, while results were compared to filter separation as a reference. Serum NO levels were determined in 60 sera of adult human. Data showed that correlation coefficient of precipitating agents: methanol, ethanol, zinc sulfate, methanol-diethylether, acetonitrile, TCA, PCA, sodium tangstate, ammonium sulfate against filter separation method were 0.84, 0.92, 0.91, 0.79, 0.88, 0.85, 0.93, 0.53, and 0.78, respectively [p < 0.001]. Methanol, ethanol and methanol/diethylether caused overestimation, while TCA, PCA, sodium tangstate, and ammonium sulfate caused underestimation of serum NO results. Serum NO level had normal distribution with mean +/- SE of 33 +/- 1.3 micromol/L. Although different chemical protein precipitants are used for serum NO determination, our study revealed that zinc sulfate is the best choice for this purpose