Novel Methodology to Measure Protein Accumulation

Study Overview
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Brief Summary
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Accumulation of damaged proteins is thought to underlie many degenerative conditions, including aging, diabetes, Alzheimer's disease, cataracts, and others. Over time, proteins can be irreversibly damaged by a variety of factors, such as reactive oxygen species, and without timely degradation they can accumulate and aggregate. We believe this can contribute to the development of chronic degenerative disorders. The purpose of this study is to develop a novel methodology for measuring protein accumulation and test it in two groups of people: young (18-30 years) and old (≥65 years). This methodology will require that people drink a solution of essential amino acids that includes isotopically labeled L[ring-13C6]phenylalanine. We will then collect blood and muscle samples, to isolate plasma and skeletal muscle proteins. Participants will return to the study center four more times on a weekly interval. We hypothesize that older proteins, which persisted in circulation and accumulated over time, will have a higher degree of post-translational oxidative damage than newly synthesized proteins.

Official Title
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Novel Methodology to Measure Protein Accumulation

Conditions
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Aging

Intervention / Treatment
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* Other: L[ring-13C6]phenylalanine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-30 years Age greater than 65 years Exclusion Criteria: Active or uncontrolled cardiovascular disease Chronic kidney disease with serum creatinine ≥ 1.4 mg/dL for women and ≥ 1.5 mg/dL for men Chronic liver disease (elevation in serum transaminases ≥ 3 times the upper limit of normal) Any debilitating chronic illness, including malignancy Significant malabsorptive state, including prior gastric bypass surgery or inflammatory bowel disease Diabetes mellitus (types 1 or 2) or glucose ≥ 110 mg/dL. Obesity (BMI ≥ 31 kg/m2) Anticoagulant therapy (warfarin or heparin) or bleeding disorder that increases risk of bleeding during a muscle biopsy. Anemia (hemoglobin ≤ 11 g/dL) Use of medications known to modulate protein synthesis, mitochondrial function, and/or glucose homeostasis (including β-blockers and corticosteroids). Participation in another study where the 13CPhe was administered during the past 6 months. Moderate or high level of structured exercise (on average, ≥ 30 minutes per day and ≥ 2 days per week) Pregnancy Daily use of tobacco products (smoking or chewing); or smoking ≥7 cigarettes per week, on average. Abstinence from tobacco for ≥3 months is required before enrollment in the study.

Ages Eligible for Study
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Minimum Age: 18 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 |
| --- | --- |
| Young<br>Healthy adults 18-30 years old | Other: L[ring-13C6]phenylalanine<br>* Oral drink composed of essential amino acids including L[ring-13C6]phenylalanine<br>|
| Elderly<br>Healthy adults greater than 65 years old | Other: L[ring-13C6]phenylalanine<br>* Oral drink composed of essential amino acids including L[ring-13C6]phenylalanine<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Isotopic enrichment of plasma and skeletal muscle proteins achieved by oral ingestion of [13C6]-phenylalanine | Administration of an oral amino acid mixture containing isotopically-labeled [13C6]-phenylalanine (13C-Phe) will result in 13C-Phe incorporation into newly synthesized proteins. Measuring isotopic enrichment (IE) of 13C-Phe immediately after administration and weekly for 3 consecutive weeks will allow for estimation of protein accumulation. | 3 weeks | 
| Degree of post-translational modifications in plasma and muscle proteins | The abundance of post-translational modifications of plasma and muscle proteins will be measured using mass spectrometry. | 3 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assess differences in protein accumulation as a function of age | Use the newly developed methodology to assess whether otherwise healthy older adults (≥65 years old) have greater accumulation of plasma and muscle proteins compared to healthy young adults (18-30 years old). | 3 weeks | 
| Assess differences in protein modification/damage as a function of age | The abundance of post-translational modification/damage of plasma and muscle proteins will be measured using mass spectrometry in young (18-30 years old)and older (>65 years old) adults. | 3 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Aging, Protein accumulation, Protein damage