Our study on the effects of autoclaving rodent diets on the progression of chronic #kidney disease and mineral and bone disorder is out in @AmJNephrol with a nice #visualabstract by @aakashshingada cc: @HillGallantKM @matthewrallenIU @nutsci ... (a thread) 1/ https://twitter.com/NephroKarger/status/1252946254721462272

2/ Some of you may know, but ALL of my research experience pre-postdoc was clinical. Since I joined Dr. Moe's lab, I've been working with an experimental model of CKD-MBD, the Cy/+ rat https://www.ncbi.nlm.nih.gov/pubmed/18800026 

3/ This is a model of progressive CKD, that develops the 3 characteristics of CKD-MBD: biochemical and bone abnormalities and aortic calcification; and *usually* around 35wks they have end-stage kidney disease

4/ However, around the time that I joined Sharon's lab (~2yrs ago), the CKD rats were progressing waaaay faster

5/ The only thing that changed in the months prior was that our animal facility started using *autoclaved* standard (chow) diet d/t a Parvovirus outbreak the year prior to try to limit infections (this is recommended by the American Association for Laboratory Animal Science)

6/ Curious, do you know if your animal facility uses autoclaved or irradiated diets?

7/ Well, just as baking/grilling at high temperatures, autoclaving the rodent diet increases the advanced glycation end products (AGEs) (we measured carboxylmethyllysine and methylglyoxal in collaboration with @lowage)

8/ Indeed, these AGEs were increased 2-3x and the amount depended on where they were in the autoclave (closer to the heat source > AGEs); therefore, the amount the animals get is highly variable and impossible to control

9/ Our standard of practice was to give the standard diet for 25 weeks and then the final 10 weeks give a purified diet (casein-based) with higher bioavailable phosphorus because the rats developed a consistent CKD-MBD phenotype (also, giving the casein diet for ~35wks is $$$)

10/ So we decided to assess kidney function, CKD-MBD, and intestinal gene expression in rats that were studied concurrently, that were given the 1) autoclaved diet, 2) autoclaved diet and then casein (standard of practice) or 3) non-autoclaved diet and then casein.

11/ NOTE: This may be a bit confusing, but these analyses were done post hoc and the study was not really designed a priori to test the effects of autoclaved diets, but could help us generate hypothesis for future studies

12/ Long story short, the animals that were fed the *autoclaved* standard diet alone or switched to casein had worse kidney function, markers of CKD-MBD, oxidative stress, and expression of the main receptor of AGEs (RAGE) and NADPH-oxidases in the intestine

13/ Some may say "who cares?". But to me, this is important because a variable that some researchers may not pay too much attention may be altering their experimental animal's phenotype, just like in our case... so just FYI.

14/ If you read all the way through here, thank you for your attention!