Effect of immune system status on Decompression Sickness resistance
1 Purpose
The goal of the experiment is to investigate the impact of immuno-preconditioning on Decompression Sickness (DCS) resistance among rats. Decompression Sickness is a complex systemic pathology encountered by divers when submitted to high pressure differentials. New insights gain from molecular biology studies showed recently that the immune system seems to play a major role as a triggering factor of Decompression Sickness. This experiment aims at highlighting this central role within controlled settings, with a well described animal model widely used in hyperbaric research.
2 Distress
Animals will be subjected to a simulated air dive known to trigger around 67% DCS among rats. Therefore, a significant distress is expected. DCS symptoms among rats include dyspnea, paresthesia, paralysis and death. All animals showing any sign of distress after the dive will be immediately euthanized.
3 Expected benefit
Expected benefits are a better understanding of the role of the immune system and inflammatory processes in DCS occurrence. This could lead to new preconditioning methods before diving, and new protocols during the clinical care for divers that developed DCS symptoms.
4 Number of animals, and what kind
A pilot study is planned with 3 experimental groups and 6 rats per group, 18 rats total. This is done to better pinpoint how many animals are required to reach statistical significance within the usual power to detect parameters (alpha 0.05, beta 0.8).
Without the pilot study, power to detect calculations highlight a need for 52 rats for each group, 156 total for a difference of around 25% DCS occurrence between groups.
5 How to adhere to 3R
Unfortunately, the use of an animal model in this study is mandatory. We do not have the possibility to use any in silico studies, as DCS complexity is still poorly understood.
However, it is possible to accurately pinpoint the correct number of animals to use in this experiment with the help of the pilot study and the aforementioned power to detect calculations. Using the correct number of animals is critical to ensure that the experiment will be statistically strong enough to detect potential differences between groups without using too many animals.
Since the diving protocol is quite severe, specific endpoints will be used. After the diving protocol, each animal will be observed for one hour for any sign of DCS. Any sign of pain will result in immediate anesthesia, followed by blood sampling and euthanasia.
The goal of the experiment is to investigate the impact of immuno-preconditioning on Decompression Sickness (DCS) resistance among rats. Decompression Sickness is a complex systemic pathology encountered by divers when submitted to high pressure differentials. New insights gain from molecular biology studies showed recently that the immune system seems to play a major role as a triggering factor of Decompression Sickness. This experiment aims at highlighting this central role within controlled settings, with a well described animal model widely used in hyperbaric research.
2 Distress
Animals will be subjected to a simulated air dive known to trigger around 67% DCS among rats. Therefore, a significant distress is expected. DCS symptoms among rats include dyspnea, paresthesia, paralysis and death. All animals showing any sign of distress after the dive will be immediately euthanized.
3 Expected benefit
Expected benefits are a better understanding of the role of the immune system and inflammatory processes in DCS occurrence. This could lead to new preconditioning methods before diving, and new protocols during the clinical care for divers that developed DCS symptoms.
4 Number of animals, and what kind
A pilot study is planned with 3 experimental groups and 6 rats per group, 18 rats total. This is done to better pinpoint how many animals are required to reach statistical significance within the usual power to detect parameters (alpha 0.05, beta 0.8).
Without the pilot study, power to detect calculations highlight a need for 52 rats for each group, 156 total for a difference of around 25% DCS occurrence between groups.
5 How to adhere to 3R
Unfortunately, the use of an animal model in this study is mandatory. We do not have the possibility to use any in silico studies, as DCS complexity is still poorly understood.
However, it is possible to accurately pinpoint the correct number of animals to use in this experiment with the help of the pilot study and the aforementioned power to detect calculations. Using the correct number of animals is critical to ensure that the experiment will be statistically strong enough to detect potential differences between groups without using too many animals.
Since the diving protocol is quite severe, specific endpoints will be used. After the diving protocol, each animal will be observed for one hour for any sign of DCS. Any sign of pain will result in immediate anesthesia, followed by blood sampling and euthanasia.
Etterevaluering
The simulated dive will trigger DCS in some of the rats, with the possibility of severe distress.
The Norwegian Food Safety Authority must retrospectively assess all severe experiments.
The Norwegian Food Safety Authority must retrospectively assess all severe experiments.
Begrunnelse for etterevalueringen
The dive (the severe protocol) was not performed because the responsible researcher decided that the experiment would not yield results statistically relevant to justify using the animals without the main chemical, LPS.
Lipopolysaccharide, or LPS, was not delivered in time by the supplier. The experimenters were informed too late that the supplier had discontinued their production because of the pandemic.
Only 6 animals out of 18 were used. These 6 animals were part of the immunosuppressed group, which had to begin their treatment before the LPS group. The LPS supplier warned the experimenters only after they began treating the immunosuppressed group. The animals were given immunosuppressive drugs per os, and not subjected to the actual experiment.
The severity of the experiment is classified as low for the 6 animals.
There are no results from the experiment, and the project can not be evaluated with regards to possible 3R improvements.
All the animals used were euthanized according to the initial protocol with careful monitoring of their anesthesia and analgesia.
The 12 others that were part of the LPS and Control groups were not used, but were given to the animal facility where they will be used for student training, as agreed with the leader of the facility.
Lipopolysaccharide, or LPS, was not delivered in time by the supplier. The experimenters were informed too late that the supplier had discontinued their production because of the pandemic.
Only 6 animals out of 18 were used. These 6 animals were part of the immunosuppressed group, which had to begin their treatment before the LPS group. The LPS supplier warned the experimenters only after they began treating the immunosuppressed group. The animals were given immunosuppressive drugs per os, and not subjected to the actual experiment.
The severity of the experiment is classified as low for the 6 animals.
There are no results from the experiment, and the project can not be evaluated with regards to possible 3R improvements.
All the animals used were euthanized according to the initial protocol with careful monitoring of their anesthesia and analgesia.
The 12 others that were part of the LPS and Control groups were not used, but were given to the animal facility where they will be used for student training, as agreed with the leader of the facility.