Jessica Patel, Kaitlin Barton, Gargi Patel
Focus of Study: Assessing the Effect of Ciprofloxacin on the Heart Rate of Chick Embryos at Day 7 on Incubation
Antibiotics are commonly prescribed medicine, even during pregnancy. However, the specific type of antibiotic and the prescribed dosage will vary amongst pregnant women and the general population. Each antibiotic is different and its usage depends on factors such as the type of antibiotic, how far along the pregnancy is, how long is it being prescribed, what the dosage is, and the possible effects it could have on the pregnancy (Beedie, 2016). Ciprofloxacin is an antibiotic used to treat bacterial infection as it works to stop the growth by blocking bacterial cell wall production, thus leading to the breakdown of cells, and eventually bacterial death (Kubin, 1993). It is a commonly prescribed antibiotic for the treatment of bacterial infection such as pneumonia, and can be prescribed to pregnant women. While ciprofloxacin is assumed to be safe when taken during pregnancy, it does have the potential to transfer from the bloodstream of the mother and into the placenta (Kubin, 1993). Therefore, it is important to understand and identify the potential risks associated with the use of ciprofloxacin while taken during pregnancy.
The chicken embryo model serves as a suitable alternative animal model for drug-distribution studies. It is fairly accessible due to its high reproducibility in a short amount of time and low cost (Winter, 2013). It is important to understand the effect of varying concentrations at different developmental stages with different drugs in order to correctly and efficiently execute planning and interpretation of neurodevelopmental toxicity studies. After an extensive literature review, we found there to be little to no pathological studies on embryos injected with ciprofloxacin and the development of their heart and vascular system has been conducted. Therefore, the influence of ciprofloxacin on the development of embryos and their cardiovascular system should be deeply and more thoroughly understood.
The main objective of this study is to establish the dosages at which ciprofloxacin serves to be detrimental on chicken embryos, clarify the pathological changes in the ciprofloxacin-exposed embryos and the cardiovascular system, and lay a foundation for further studies on the mechanism of ciprofloxacin in embryonic toxicity. The teratogenic effects of varying concentrations of ciprofloxacin on cardiac development were studied in chick embryos of days 6 and 7 of incubation.We specifically chose to see how ciprofloxacin affects the development of the chicken embryo after a 6-7 days of incubation because this is where the embryo is more developed. In this stage, the embryo has started growing and looks more like a chicken to the human eye.
Fertilized eggs from the UGA Poultry Research Center, located in Athens, Georgia, were incubated inset on their long axis in a humidified incubator (name of product) set at 37 degrees Celsius. The injection protocol was adapted from methods found in previous publications (Winter et al., 2012).
After 72 hours of incubation (Embryonic Day 3; HH19), the eggs were first weighed before injecting them. They were then eggs were sanitized with 70 % ethanol, and 1.0 mL of either a low, medium, high, and controlled dosage of ciprofloxacin. This was followed by sealing the hole made in the egg with medical tape, in order to avoid contamination or dehydration.
Chicken embryos were randomly assigned various concentrations of ciprofloxacin, 0 ug/m, 1 ug/ mL, 0.8 ug/mL, and 0.5 ug/mL, on the third day of incubation. The an embryo that was injected with distilled water served as the baseline control for comparison. On Day 7 of incubation, they were taken out of the egg and observed for any abnormalities.
The embryonic heart rate in vivo and embryonic survival rate five days after microinjection was monitored and observed. The beating heart was removed by cutting it from above the conotruncus and below the sinus node or atrium. The excised heart was then transferred into a Bioptechs EDU Series Culture Dish Control System, which maintains contents at 41°C, under a dissecting microscope. We used an iPhone to video record the heart rate for intervals of 15 seconds each. The heartbeat was analyzed through playback of a video recording.
The difference in heart rate pre-injection on day 2 of incubation, and post-injection on day 7 of incubation among various concentrations of ciprofloxacin for each trial, along with the average from all of the trials for each treatment group.
Heart rate of 7-day old embryos exposed to various concentrations of ciprofloxacin for each trial, along with the average from all of the trials for each treatment group.
One limitation we found was while measuring the heart rate. In our study, we used the biotechs edu culture control dish to keep the heart rate going. We allowed the embryo to sit there for 30 seconds and then started the video recording to record the heart rate. A lot of the embryos started with a consistent heartbeat and then the heart stopped during the recording. This made it difficult to get an accurate assessment of the embryo's heart rate. We suggest finding an alternative method that would be more reliable across measuring the heart rate of each embryo. We would also like to point out that a small sample size could affect the significance of the results. A larger sample size reduces the likelihood of making a type 1 error. It helps to increase the external validity or generalizability of the results. It provides a more representative sample of the population, and the results are more likely to be applicable to the larger population
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