Brown, Brenna

ABSTRACT The coexistence of obesity and insulin resistance is associated with elevated plasma amino acid concentrations. However, it remains unclear whether adiposity or insulin resistance is the stronger determinant of plasma amino acid dysregulation in this setting. Twenty-two adults (10 women, 12 men) spanning a broad range of body mass index (BMI) and insulin resistance underwent a 75-g oral glucose tolerance test (OGTT) after an overnight fast. Plasma glucose, insulin, and amino acid concentrations were measured serially, and insulin resistance/sensitivity was estimated from OGTT-derived glucose and insulin responses, using the homeostasis model assessment of insulin resistance (HOMA-IR) and the Matsuda insulin sensitivity index (Matsuda-ISI). Principal component analysis (PCA) of fasting plasma amino acid concentrations showed no clear separation by obesity or insulin resistance classifications. In contrast, PCA of OGTT-stimulated plasma amino acid concentrations revealed clearer clustering by BMI, fat mass, and waist circumference, whereas separation by HOMA-IR and Matsuda-ISI was less distinct. Importantly, regression analyses showed that BMI, fat mass, and waist circumference were significant predictors of OGTT-stimulated, but not fasting, amino acid responses, with waist circumference accounting for the greatest proportion of the variance in branched-chain amino acid responses during the OGTT (R 2 = 0.54). In conclusion, measures of adiposity, particularly total fat mass and waist circumference, accounted for a greater proportion of the variance in plasma amino acid responses under physiologically stimulated conditions than indices of insulin resistance. These findings support the view that plasma amino acid concentrations reflect adiposity-related metabolic alterations more strongly than insulin resistance.

INTRODUCTION: Ongoing surveillance after successful endoscopic eradication therapy for Barrett's esophagus (BE)-related neoplasia is essential to detect and manage recurrence. Despite established surveillance interval recommendations after complete eradication of intestinal metaplasia (CE-IM), patient compliance with repeat endoscopy is frequently suboptimal. Understanding patient drivers to adherence is essential to inform interventions that address the high rates of overdue surveillance and loss to follow-up. METHODS: Patients with BE-related neoplasia who achieved CE-IM were eligible for inclusion and classified as delayed or on-time for endoscopic surveillance. Patients were prospectively enrolled and participated in structured virtual interviews designed to explore barriers and facilitators to on-time care. A rapid qualitative analysis approach was applied, continuing until thematic saturation was reached. RESULTS: Thirty-nine patients were interviewed: 22 (56.4%) were delayed, and 17 (43.6%) were on-time for surveillance. Patients in the delayed group had longer mean BE segment lengths and a higher prevalence of tobacco use. Geographic distance from the treatment center was the most frequently cited barrier to follow-up (n = 17; 43.5%). Other common barriers were access limitations, financial concerns, misunderstanding of disease course, and test-related anxiety. DISCUSSION: Patient-related drivers of delay in postendoscopic eradication therapy surveillance are largely logistical, socioeconomical, and psychological in nature. Solutions to reduce the significant burden on the patient and achieve timely surveillance may include transitioning patients back to their local endoscopists after CE-IM or incorporating nonendoscopic surveillance methods through patient centered approaches.

AbstractWe investigated how obesity impacts the response of circulating insulin‐like growth factor‐1 (IGF‐1) to a single bout of endurance exercise in humans with and without obesity. Blood samples were collected before exercise, at 15 and 40 min during a 45‐min cycling session at 65% of heart rate reserve, and 15 min post‐exercise. Serum levels of total IGF‐1, free IGF‐1, IGF binding proteins 1 (IGFBP‐1) and 3 (IGFBP‐3), growth hormone, and insulin were measured. Both total IGF‐1 and IGFBP‐3 serum concentrations increased significantly (p < 0.05) during exercise in the study participants without obesity but not in those with obesity, returning to basal levels immediately after exercise. There was a statistically significant main effect on the growth hormone response, with circulating levels being higher in participants without obesity (p < 0.05). No significant effects were observed for either free IGF‐1 or IGFBP‐1 serum concentrations in response to exercise in either group (p > 0.05). We conclude that humans with obesity have blunted serum total IGF‐1 response during exercise. However, a concurrent attenuation in serum IGFBP‐3 response, which regulates free (i.e., biologically active) IGF‐1 in circulation, results in no change in circulating free IGF‐1 levels during endurance exercise in individuals with obesity.

Abstract The growing prevalence of obesity, a risk factor for disorders such as Alzheimer’s Disease (AD), raises concerns about the effects on cognitive health. AD currently impacts 6.9 million Americans aged 65 and older and is characterized by the presence of amyloid beta (Aβ) plaques, neurofibrillary tau tangles, and neuroinflammation, all of which contribute to cognitive impairment. Insulin resistance, common in both obesity and AD, disrupts brain glucose metabolism and accelerates neurodegeneration. Understanding the factors that link these conditions could lead to new strategies for combating disease. Notably, the B-like vitamin choline is necessary for fat metabolism and has been shown to help reduce obesity incidence. However, ∼90% of Americans are deficient, and decreases in this nutrient have been associated with cognitive decline. Here, we examined circulating choline levels, inflammation, and metabolic dysfunction in human participants with obesity (BMI > 30) compared to normal BMIs (18.5–24.9), as well as in 3xTg-AD mice, an AD model, fed a choline-deficient diet throughout adulthood. Our results revealed that obese participants exhibited significantly lower circulating choline levels compared to those with a healthy BMI. Lower choline levels correlated with higher %Body fat and increased markers of insulin resistance. Elevated inflammatory cytokines in obese participants were also seen in 3xTg-AD mice on a choline-deficient diet, which exhibited significant weight gain and metabolic dysfunction. AD-like pathology was also exacerbated in choline deficient 3xTg-AD mice. These findings underscore the relationship between low choline levels, obesity, insulin resistance, and cognitive decline risk. Adequate choline intake may mitigate the risk of obesity, potentially preventing cognitive decline and associated diseases. Highlights Obesity is linked to increased insulin resistance (IR) and systemic inflammation, both of which are recognized risk factors for Alzheimer’s disease (AD). Women exhibit lower circulating choline levels compared to men, and obese individuals display significantly lower choline levels than those with a healthy BMI. Lower circulating choline levels are linked to a higher body fat percentage, increased markers of IR and liver dysfunction, as well as heightened systemic inflammation. 3xTg-AD mice on a choline-deficient diet experience considerable weight gain, metabolic dysfunction, heightened systemic inflammation, and AD-like pathology, resembling the conditions observed in obese human participants.