METHODS: Sprague Dawley rats were intravitreally injected with ET1. MgAT and TAU were administered as pre-, co-, or posttreatment. Subsequently, the expression of NOS isoforms was detected in retina by immunohistochemistry, retinal nitrotyrosine level was estimated using ELISA, and retinal cell apoptosis was detected by TUNEL staining.
RESULTS: Intravitreal ET1 caused a significant increase in the expressions of nNOS and iNOS while eNOS expression was significantly reduced compared to vehicle treated group. Administration of both MgAT and TAU restored the altered levels of NOS isoform expression, reduced retinal nitrosative stress and retinal cell apoptosis. The effect of MgAT, however, was greater than that of TAU alone.
CONCLUSIONS: MgAT and TAU prevent ET1-induced retinal cell apoptosis by reducing retinal nitrosative stress in Sprague Dawley rats. Addition of TAU to Mg seems to enhance the efficacy of TAU compared to when given alone. Moreover, the pretreatment with MgAT/TAU showed higher efficacy compared to co- or posttreatment.
MATERIALS AND METHODS: A total of 60 subjects were selected for this study. 40 subjects presented with periodontitis, which included 20 snuff users (SP) and 20 nonsnuff users (NS). 20 periodontally healthy patients formed the controls (healthy control: HC). The clinical parameters recorded were gingival index (GI), plaque index, calculus index, bleeding on probing (BOP), probing depth (PD), recession (RC), and clinical attachment level (CAL). The IL-1 β and IL-8 levels were assessed through enzyme-linked immunosorbent assay (Quantikine(®)). Analysis of variance (ANOVA), post-hoc Tukey's, Kruskal-Walli's ANOVA and Mann-Whitney test was used for comparison among groups and P > 0.05 was considered statistically significant.
RESULTS: No significant difference was seen in levels of IL-1 β and IL-8 between SP and NS groups (P = 0.16, 0.97). However, both the periodontitis groups (SP and NS) had increased IL-β levels when compared to HC group (P = 0.01, 0.001). The snuff users showed significant increase in GI, BOP, RC, and CAL when compared with NS (P = 0.002, 0.001, 0.012, 0.002) whereas NS group had significant increase in PD (P = 0.003).
CONCLUSION: Within the limitations of this study, use of snuff does not affect the host inflammatory response associated with periodontitis and leads to RC and increased CAL due to local irritant effect.
AREAS COVERED: Herein, the authors discuss the various factors that contribute to the quality of studies using animal models based on the evaluation of studies published in 2022. The factors affecting the quality of studies using animal models, such as the animal species, age, and sex, are discussed, along with various methods and outcomes of studies involving different animal models of glaucoma.
EXPERT OPINION: Translating animal research data to clinical applications remains challenging. Our observations in this review clearly indicate that many studies lack scientific robustness not only in their experiment conduct but also in data analysis, interpretation, and presentation. In this context, ensuring the internal validity of animal studies is the first step in quality assurance. External validity, however, is more challenging, and steps should be taken to satisfy external validity at least to some extent.