Human Intestinal Amino Acid Absorption and the Role of a Local RAS

Study Overview
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Brief Summary
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This study is to find out what role a local intestinal RAS (renin angiotensin system) plays in the context of amino acid absorption in the human intestinal tract and how this RAS and thus the amino acid absorption is influenced by the RAS-active drugs (angiotensin II AT1 receptor blockers (sartans) or ACE inhibitors).

Official Title
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Human Intestinal Amino Acid Absorption and the Role of a Local (Renin)-Angiotensin System (RAS)

Conditions
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Renin-Angiotensin Aldosterone System (RAS)

Intervention / Treatment
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* Other: biopsy of intestinal tissue
* Other: blood draw
* Other: urine collection


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Body Mass Index (BMI): 18-35 kg/m2 cohort 1: therapy with an angiotensin II AT1 antagonist or ACE Inhibitor cohort 2: no therapy with an angiotensin II AT1 antagonist or ACE Inhibitor Carrying out a diagnostic gastroscopy, colonoscopy or a combined gastroscopy / colonoscopy Existence of written consent after detailed information about the study Exclusion Criteria: Severe pathological changes in the gastrointestinal tract (e.g. sprue, stomach ulcers, malignancies); (reflux esophagitis and gastritis are not Exclusion criteria) History of gastrointestinal tract surgery (except for appendectomy and inguinal hernia surgery) History of malignancy Severe acute and chronic organ diseases requiring treatment (e.g. kidney replacement therapy) Patients with an increased risk of bleeding (e.g. oral anticoagulation, coagulation disorders) Drug or alcohol abuse Mental impairment limiting the ability to meet all study requirements

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| RAS- active medication<br>Patients taking RAS- active medication (ACE- Inhibitor, Angiotensin II AT1 Antagonist (Sartan)) on a daily Basis for at least 6 months for medical reasons | Other: biopsy of intestinal tissue<br>* 4 intestinal tissue biopsies taken from descending Duodenum, 2 intestinal tissue biopsies taken from Ileum, 2 intestinal tissue biopsies taken from ascending colon (additional to routine biopsies taken for gastrointestinal diagnostic)<br>Other: blood draw<br>* 40 ml blood draw (in Heparin blood tubes) (additional to routine blood draw taken for gastrointestinal diagnostic)<br>Other: urine collection<br>* Midstream Urine collection<br>|
| no RAS- active medication<br>Patients not taking RAS- active medication | Other: biopsy of intestinal tissue<br>* 4 intestinal tissue biopsies taken from descending Duodenum, 2 intestinal tissue biopsies taken from Ileum, 2 intestinal tissue biopsies taken from ascending colon (additional to routine biopsies taken for gastrointestinal diagnostic)<br>Other: blood draw<br>* 40 ml blood draw (in Heparin blood tubes) (additional to routine blood draw taken for gastrointestinal diagnostic)<br>Other: urine collection<br>* Midstream Urine collection<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| messenger ribonucleic acid (mRNA) quantification in intestinal tissue biopsy | mRNA quantification in intestinal tissue biopsy: mRNA content coding for regulatory RAS protein is measured relative to the mRNA content, which codes for the structural protein villin. | single time-point at baseline | 
| amino acid concentration in blood sample | amino acid concentration in blood sample by High Performance Liquid Chromatography (HPLC) | single time-point at baseline | 
| amino acid concentration in urine sample | amino acid concentration in urine sample by HPLC (High Performance Liquid Chromatography) | single time-point at baseline | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Renin Angiotensin System, Angiotensin Converting Enzyme 2 (ACE2), Angiotensin II AT1 Receptor Blocker, ACE inhibitors, intestinal amino acid absorption