Test Dataset 3

Test dataset to evaluate feasibility of uploading DICOM - raw and zipped 

TEST ABSTRACT

Background: Methods to quantify the activity of the tissue renin-angiotensin system (RAS) are needed.

Objective: To estimate RAS enzyme activity in postmortem myocardial and renal tissues and to evaluate enzyme stability by repeating enzyme activity assessment on samples where freezing was delayed.

Animals: Convenience sample of fifteen purpose-bred laboratory dogs with experimental heartworm infection (Group 1) euthanized as part of an unrelated study and twenty-two client-owned dogs who died or were euthanized for any reason (Group 2).

Methods: Myocardial and renal tissue samples were frozen within 20 minutes of euthanasia (Group 1) or during routine necropsy exam (Group 2).  Homogenized tissues were incubated with spiked angiotensin I (AngI) or II (AngII) under control and inhibitor conditions to assess relative enzyme contributions to AngII or angiotensin 1-7 (Ang1-7) formation.  In both groups, freezing was delayed in paired samples, to evaluate the effect of time to freezing on RAS enzyme activity.

Results: RAS enzymes remained active for hours postmortem.  Angiotensin converting enzyme (ACE) was responsible for most AngII formation in all tissues in both groups.  The 90% confidence limits of the geometric mean of the ratio of the 0-hour and delayed freezing sample in 10/14 (Group 1; 2-hour delay) and 16/19 (Group 2; 7-hour delay) experiments met the equivalence requirement of a lower bound >0.8 and upper bound <1.2. 

Conclusions and Clinical Importance: Renin-angiotensin system enzymes remain active in canine myocardial and renal tissues for hours postmortem and provide an opportunity to study tissue RAS regulation in clinical patients.