Cerebral Blood Flow Changes in People With Obesity After Glucose Consumption

Study Overview
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Brief Summary
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This study evaluates the hypothesis that a meal constituted of only glucose produces differences in the brain blood flow in people with obesity that are not observed in people without obesity. These changes, at least in part, could explain the mechanisms involved in maintenance or development of obesity.

Official Title
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Cerebral Perfusion Changes in Obese Subjects After Administration of 75 Grams of Glucose. A SPECT, Controlled, Blinded and Randomized Study.

Conditions
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Obesity

Intervention / Treatment
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* Other: 75 grams of glucose plus water solution
* Other: Pure water


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Live in Ribeirão Preto, São Paulo - Brazil. Age between 18 and 40 years old. Female gender. Regular menses. Weight inferior than 120 Kg and body mass index (BMI) between 30 and 40 kg/m2, for the group with obesity. BMI between 18,5 and 24,9 kg/m2, for the group without obesity. Exclusion Criteria: High blood pressure, diabetes, glucose intolerance or impaired fasting glycemia, metabolic syndrome, hypothyroidism and any kidney, liver, heart or neurologic disease. Psychiatric disorders, alcoholism, smoking or illicit drug abuse. Pregnancy or desire to be pregnant Use of medications, excluding contraceptives. Contraindication for magnetic resonance imaging. Be in treatment for obesity.

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

Sexes Eligible for Study
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Female

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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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 75 grams of glucose plus water solution<br>In the group with 10 volunteers with obesity, some of them are submitted first to the 75 grams of glucose plus water solution (meal challenge) and in another time to only water. Also, in the group with 10 volunteers without obesity, some of them are submitted first to the 75 grams of glucose plus water solution (meal challenge) and in another time to only water. | Other: 75 grams of glucose plus water solution<br>* A solution composed by 75 grams of glucose and water at ambient temperature is administered to each volunteer, being of the with obesity group or the without obesity group, as follow: 300 mL final volume of the solution. Time of oral ingestion inferior than 2 minutes. 30 minutes before the radiopharmaceutical injection. 12 hours fasting minimum.<br>Other: Pure water<br>* Pure water at ambient temperature is administered to each volunteer, being of the with obesity group or the without obesity group, as follow: 300 mL final volume of the solution. Time of oral ingestion inferior than 2 minutes. 30 minutes before the radiopharmaceutical injection. 12 hours fasting minimum.<br>|
| Placebo Comparator: Pure water.<br>In the same group with 10 volunteers with obesity, some of them are submitted first to only water (control) and in another time to the 75 grams of glucose plus water solution (meal challenge). Also, in the same group with 10 volunteers without obesity, some of them are submitted first to only water (control) and in another time to the 75 grams of glucose plus water solution (meal challenge). | Other: 75 grams of glucose plus water solution<br>* A solution composed by 75 grams of glucose and water at ambient temperature is administered to each volunteer, being of the with obesity group or the without obesity group, as follow: 300 mL final volume of the solution. Time of oral ingestion inferior than 2 minutes. 30 minutes before the radiopharmaceutical injection. 12 hours fasting minimum.<br>Other: Pure water<br>* Pure water at ambient temperature is administered to each volunteer, being of the with obesity group or the without obesity group, as follow: 300 mL final volume of the solution. Time of oral ingestion inferior than 2 minutes. 30 minutes before the radiopharmaceutical injection. 12 hours fasting minimum.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Regional cerebral blood flow (rCBF) changes after a meal challenge, measured by Single Single-photon emission computed tomography (SPECT) and statistical parametric mapping. | Using 99m technetium ecd radiopharmaceutical, this study aims to detect rCBF differences between SPECT images performed after a meal challenge composed by 75 grams of glucose and water and also after a challenge constituted by only water (control), both ingested orally. This approach is performed in a group of 10 people with obesity and also in 10 people without obesity. | 30 minutes after a meal challenge (time of radiopharmaceutical injection) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood levels mean differences within both groups, with and without obesity and across these groups, of hormones and metabolites by multiplexed assay using luminex technology and spectrophotometry, respectively. | This study looks for mean differences of blood levels within and across groups with and without obesity. The metabolites and hormones/cytokines measured are, respectively: glucose (measured by spectrophotometry), insulin, leptin, amylin, interleukin 6 (IL-6), tumor necrosis factor alpha, active ghrelin, peptide yy (PYY) and pancreatic polypeptide (PP) (multiplexed assay using luminex). | 30 minutes before, at the time and 30, 60 and 90 minutes after the radiopharmaceutical injection. | 
| Resting energy expenditure (REE) and body composition measurements by indirect calorimetry and electrical bioimpedance, respectively. | This study also aims to measure and compare the REE by indirect calorimetry with a Quark (Cosmed, Italy) calorimeter and the body composition by Byodinamics 450 (Biodynamics Corp., United States) within the two groups and across them. | 6 hours before SPECT acquisition. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obesity, Single Photon Emission Computed Tomography, Functional Neuroimaging