Brown Adipose Tissue Volume and Distribution in Premenopausal and Postmenopausal Women
Notice bibliographique
Résumé
Introduction The loss of ovarian function and the accompanying decrease in estradiol during menopause has an impact on the metabolic activity of many tissues and organs, resulting in a reduction in resting energy expenditure. In rodents, ovariectomy or the absence of the estrogen receptor α suppresses brown adipose tissue (BAT) thermogenesis. It is therefore hypothesized that a reduction in BAT volume and thermogenesis may contribute to the reduction in resting energy expenditure in postmenopausal women. Objective The primary aim was to investigate the impact of estrogen on BAT volume and its distribution across the various depots in pre‐ and postmenopausal women. Methods A cohort of 22 premenopausal (33 years, 95% CI: 29 to 37 years) and 22 postmenopausal women (63 years, 95% CI: 60 to 67 years) took part in a 3‐hr cold exposure using a liquid‐conditioned suit perfused with 18°C water. During cold exposure, an i.v. bolus of [ 11 C]‐acetate and [ 18 F]FDG were given sequentially, with each injection followed by a 30 min list‐mode dynamic PET acquisition to quantify BAT oxidative metabolism and glucose uptake, respectively. Finally, a whole‐body static PET acquisition was performed to quantify the whole‐body biodistribution of glucose and estimate BAT volume and the distribution of this BAT volume across the various depots. BAT volume was determined according to the following criteria: [ 18 F]FDG ≥ 2 SUV mean and a radiodensity between ‐10 and ‐250 HU. Results There was significant variability in BAT volume and its distribution in both pre‐ and postmenopausal women. Premenopausal women had greater total BAT volume (53 mL, 95% CI: 34 to 72 mL) compared to postmenopausal women (21 mL, 95% CI: 8 to 34 mL, P = 0.006), although both groups included individuals with undetectable BAT. In premenopausal women, 65% of BAT was localized in the supraclavicular depot (95% CI: 57 to 73%) and 9% in the paravertebral depot (95% CI: 5 to 13%), with the remaining depots ( e.g. cervical, axillary, mediastinal, and perirenal) accounting for 25% (95% CI: 16 to 34%). In postmenopausal women, 45% of BAT was localized in the supraclavicular depot (95% CI: 24 to 66%) while the paravertebral depot represented 32% (95% CI: 12 to 52%) of total BAT. The remaining 23% (95% CI: 5 to 41 %) was distributed among the other depots. Thus, in postmenopausal women, there was a 20% reduction in the relative contribution of supraclavicular depots to the total volume and a 23% increase in the relative contribution of paravertebral depots to the total BAT volume compared to premenopausal women. Conclusion Here we show that total BAT volume is lower in postmenopausal women and results in a redistribution of BAT. However, there was tremendous variability in both BAT volume and distribution in both premenopausal and postmenopausal women. Further, it is difficult to distinguish the effects of estrogen from the effect of age or adiposity in the observed differences between our two cohorts.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».