Custom essays on Statistical analysis of cues causing dive reflex and effects of changes caused by Drug X

Data Set 1.

The aim of this research is to study human dive reflex via measuring heart rate, and analyze the cues simulating the dive response basing on the following measurements of heart rate: resting, simulated dive, breath hold in air, snorkel + dive, snorkel in air, cold gel pack applied when breathing, cold gel pack applied while holding breath, RT gel pack when breathing, RT gel pack while holding breath. For this task it is reasonable to use ANOVA (ordinary analysis) with resting heart rate measurement chosen as control group (Dunnett post test). Significance level was defined as p<0.05 (p<0.01 will be considered as very significant and denoted by **).

Table 1 shows the summary of statistical analysis and indicates the groups where significant difference of means was proven compared to control group. Dunnett multiple comparisons test q value greater than 2.678 indicates that p is less than 0.05. Statistical representation of means of the measurements is shown on Fig. 1.

Table 1. Cues causing dive reflex

Fig. 1. Comparison of heart rate measurement at different conditions. Data expressed as mean ±SEM

First of all, simulated dive itself makes a significant difference compared to resting (in heart rate measurement). There is also significant statistical difference in heart rates for snorkeling while diving (compared to resting) and for applying cold gel pack (both when breathing and when breath is hold). No statistical difference between the means was found when RT gel pack was applied (both when breathing and when breath is hold), and when heart rate was measured in air (while breath is hold and while snorkeling). Thus, it is possible to conclude that water submersion and cold temperature are the components simulating the dive reflex.

Data Set 2.

The aim of this research is to study the effect of drug X on the level of reactive oxygen species (via measuring DCF fluorescence) and on caspace-3 activity. Analysis of different concentrations of Drug X on DCF fluorescence and caspace-3 activity was performed using ordinary ANOVA, suggesting that all values were sampled from Gaussian distribution. P-value of the whole data set is <0.0001, considered extremely significant.

Concentration of 0 uM was taken as control group, and post-tests were made by comparing all groups versus control group – Dunnett post test (Deep, 2006). Significance level chosen – p<0.05. Table 2 shows statistical significance of the groups (q<2.7 implies p<0.05), and Fig. 2. illustrates groups where the difference between means is statistically significant. It is possible to determine that concentration of drug X of 0.4uM and more results in statistically significant difference of the means, and thus proven the effect of this drug, when concentration is greater than 0.4uM.

Table 2. Impact of Drug X on DCF fluorescence

Fig. 2. Comparison of means for different drug X concentration

(statistical significance, i.e. p<0.05, denoted by *)

Table 3 and Fig. 3 correspondingly illustrate results of statistical analysis of drug X impact on caspace-3 activity (different concentrations of drug X compared as in previous example). Analysis was done using ordinary ANOVA, with Dunnett post-test. P-value of the whole data set is <0.0001; thus, drug X has an effect on caspace-3 activity. ANOVA shows that all concentrations but 0.1uM has a statistically different mean from control group, and thus, drug X has effect for concentration greater than 0.1 uM (0.1, 0.2, 0.4, 2, 5 uM).

Table 3. Impact of Drug X on caspace-3 activity

Fig. 3. Comparison of means for different drug X concentration

(statistical significance, i.e. p<0.05, denoted by +)

Finally, analysis of ROS changes on caspace-3 activity made by comparing the effect of drug X alone to drug X effect plus NAC (illustrated by Fig. 4) showed that statistical difference between the means is not significant. Two-tailed unpaired t-test was used (Motulsky, 2010), with significance level p<0.05. P = 0.0885, considered not quite significant.

Fig. 4. Comparison of drug X effect to Drug X + NAC on caspace-3 activity (no statistical significance found)

Thus, statistical analysis shows that drug X has effect both on ROS changes (starting from concentration of 0.4 uM) and on caspace-3 activity (starting from concentration of 0.2 uM). Also, it has been found that ROS changes do not affect caspace-3 activity significantly; consequently, measured changes in caspace-3 activity are the effect of drug X – which proves its efficiency for the above-mentioned concentrations.

Sources

Deep, Ronald. (2006). Probability and statistics with integrated software routines. Academic Press.

Motulsky, Harvey. (2010). Intuitive Biostatistics: A Nonmathematical Guide to Statistical Thinking.OxfordUniversityPress US.