Brown Adipose Tissue and Body Mass Index

Study Overview
=================
Brief Summary
-----------------
In this study the investigators aim to investigate whether the sympathetic stimulation of BAT, as assessed with a 123I-metaiodobenzylguanidine single-photon emission computed tomography computed tomography scan, differs between lean and obese individuals, as an explanation for the diminished metabolic brown adipose tissue activity in obese subjects. The investigators hypothesis is that sympathetic nervous system activity in the obese is diminished as compared to their leaner counterparts as an explanation for the diminished metabolic brown adipose tissue activity in the obese.

Detailed Description
-----------------
The sympathetic nervous system is the primary activator of Brown Adipose Tissue. Obese humans are known to have less metabolically active brown adipose tissue as compared to their leaner counterparts. The reason for this diminished metabolic brown adipose tissue activity is unknown. However, a lower sympathetic nervous system activation to brown adipose tissue in the obese might explain a diminished metabolic brown adipose tissue. Therefore, in this study, both the sympathetic nervous system activation to brown adipose tissue and the metabolic activity will be measured in lean and obese subjects. sympathetic nervous system activity will be measured using 123I-metaiodobenzylguanidine single-photon emission computed tomography scans, metabolic activity will be measured using 18F- fluorodeoxyglucose positron emission tomography CT scans.

Official Title
-----------------
Activation of Brown Adipose Tissue in Lean and Obese Men

Conditions
-----------------
Obesity, Type 2 Diabetes Mellitus

Intervention / Treatment
-----------------
* Other: 18F- fluorodeoxyglucose-positron emission tomography Computed Tomography scan and 123I-metaiodobenzylguanidine-single-photon emission computed tomography scan


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Male Caucasian origin Subjects should be able and willing to give informed consent 18-40 years old BMI range of 19-25 kg/m2 (lean study subjects) or 28-40 kg/m2 (obese study subjects) Exclusion Criteria: Renal failure (creatinine>135mmol/l) Daily use of prescription medication

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
-----------------
Male

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Lean subjects<br>Lean, young, healthy, Caucasian, male subjects | Other: 18F- fluorodeoxyglucose-positron emission tomography Computed Tomography scan and 123I-metaiodobenzylguanidine-single-photon emission computed tomography scan<br> <br> |
| Other: Obese subjects<br>Obese, Young, Healthy, Caucasian, male subjects | Other: 18F- fluorodeoxyglucose-positron emission tomography Computed Tomography scan and 123I-metaiodobenzylguanidine-single-photon emission computed tomography scan<br> <br> |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in sympathetic stimulation to BAT between lean and obese individuals |  | Participants will be followed for a mean duration of 2 weeks (the maximal time period between the two scans) The outcome measurements will be assessed when the last subject has been scanned approximately one year after starting the trial | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in correlation between sympathetic stimulation of BAT as assessed with 123I-MIBG SPECT scans and metabolic BAT activity as assessed with 18F-Fluorodeoxyglucose(FDG)- positron emission tomography(PET)-CT scan in lean and obese individuals | The difference in correlation between sympathetic stimulation of BAT and metabolic BAT activity between lean and obese individuals. | Participants will be followed for a mean duration of 2 weeks (the maximal time period between the two scans) The outcome measurements will be assessed when the last subject has been scanned approximately one year after starting the trial. | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Brown Adipose Tissue, Weight, Sympathetic Nervous System