Application of Outlier Robust Nonlinear Mixed Effect Estimation in Examining the Effect of Phenylephrine in Rat Corpus Cavernosum

Abstract Ignoring two main characteristics of the concentration-response data, correlation between observations and presence of outliers, may lead to misleading results. Therefore, the special method should be considered. The present study was designed to apply the outlier robust nonlinear mixed estimation for effects of phenylephrine on rat corpus cavernosum strips. In this study, eight different doses of phenylephrine in eight experimental groups were used. Each group consisted of eight rats. The concentration-response curves to phenylephrine (0.1µM to 300µM) were obtained by the cumulative addition of phenylephrine to the chamber. Because of the existence of an outlier to achieve robust estimations, M-estimation method and Huber function as a dispersion function were used. Cumulative administration of phenylephrine (0.1µM -300µM) caused concentration-dependent contractions in strips of rat corpus cavernosum (-Log EC 50 was 5 ± 0.31, 95% CI= 5.92 to 4.21). The contraction of corpus cavernosum started in the concentration of 0.3 μM and then gradually increased in a dose-dependent manner till it reached a plateau in 100 μM. To consider the clustering feature of concentration-response data, the 4pl regression with a random term has been used. To estimate parameters, because of existence of an outlier in dataset, the robust procedure has been applied. The contraction of corpus cavernosum started in the concentration of 0.3 μM and then gradually increased in a dose-dependent manner till it reached a plateau in 100 μM

Application of Outlier Robust Nonlinear Mixed Effect Estimation in Examining the Effect of Phenylephrine in Rat Corpus Cavernosum: Outlier Robust Nonlinear Mixed Effect Estimation in Examining the Effect of Phenylephrine

Ignoring two main characteristics of the concentration-response data, correlation between observations and presence of outliers, may lead to misleading results. Therefore, the special method should be considered. The present study was designed to apply the outlier robust nonlinear mixed estimation for effects of phenylephrine on rat corpus cavernosum strips. In this study, eight different doses of phenylephrine in eight experimental groups were used. Each group consisted of eight rats. The concentration–response curves to phenylephrine (0.1μM to 300μM) were obtained by the cumulative addition of phenylephrine to the chamber. Because of the existence of an outlier to achieve robust estimations, M-estimation method and Huber function as a dispersion function were used. Cumulative administration of phenylephrine (0.1μM - 300μM) caused concentration-dependent contractions in strips of rat corpus cavernosum (-Log EC50 was 5 ± 0.31, 95% CI= 5.92 to 4.21). The contraction of corpus cavernosum started in the concentration of 0.3 μM and then gradually increased in a dose-dependent manner till it reached a plateau in 100 μM. To consider the clustering feature of concentration-response data, the 4pl regression with a random term has been used. To estimate parameters, because of existence of an outlier in dataset, the robust procedure has been applied. The contraction of corpus cavernosum started in the concentration of 0.3 μM and then gradually increased in a dose-dependent manner till it reached a plateau in 100 μM

Effects of Flaxseed oil supplementation on renal dysfunction due to ischemia/reperfusion in rat

Introduction: This study was designed to evaluate the effects of treatment with flaxseed oil (FSO) on renal ischemia-reperfusion (RIR) injuries in rats. Materials and methods: In this study, 32 Wistar rats were randomly studied in four groups: Co+NS (Control group with normal saline administration), Sh+NS (sham group with normal saline administration), RIR+NS and RIR+FSO. FSO (0.2 ml) was administered orally (gavage) for 14 days (~ 800 mg/kg body weight).  Blood samples were collected for the detection of blood urea nitrogen (BUN) and creatinine levels.  Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were evaluated in the renal tissue. Tubular damages were examined using histopathological studies. Results: Significantly elevated MDA (P<0.05) and depressed SOD levels (P<0.05) Comparison between RIR+NS group and Control+NS and Sh+NS groups revealed in the condition of RIR. Treatment with FSO, however, significantly lowered the MDA (P<0.05) and enhanced SOD levels (P<0.05) after RIR injury. Histopathological results confirmed the biochemical studies and tubular necrosis score was reduced in the RIR+FSO group. Conclusion: This study therefore suggests that the aqueous flaxseed oil may be useful agents for the prevention of renal ischemia-reperfusion (RIR)-induced oxidative injury in rats