Utilization of NMR surface coil techniques to study muscle fatigue
Notice bibliographique
Résumé
Skeletal muscle has a greater biochemical dynamic range than any other tissue. Upon strenuous exercise its oxidative demands may increase a hundredfold, and its glycolytic rate, a thousandfold. It is particularly for this tissue that the distinction between conditioning and disease becomes blurred, since poor conditioning may produce more functional compromise in muscle than many diseases produce in other target organs. Muscle, which amounts to about 40% of the body mass, is thus a prime candidate for functional or metabolic diseases. Therefore, muscle provides a convenient biochemical "window" for early detection of potentially life-threatening diseases. In this thesis a modified Chance/Radda method was used to investigate the use of P-31 NMR Spectroscopy (NMRS or MRS) to monitor patients with muscle diseases. The work described is divided into two parts: (a) design and evaluation of NMR surface coils of various configurations, and assessment of a preliminary clinical protocol, (b) optimization of the technique by normalizing the results with respect to the cross-sectional area of the human upper arm, and to the various parameters which influence the mechanical output of the appropriate muscles. The highlight of the work presented in this thesis has involved the development, improvement, characterization, and experimental implementation of a novel design of surface coil, namely the spiral resonator surface coil gantry, as well as the delineation, refinement, and clinical execution of a tractable protocol to study muscle fatigue. Assessment of the role of P-31 NMRS as a screening and diagnostic modality indicates that it can serve as an adjunctive tool. The P-31 NMR spectrum can provide information regarding the composition and level of the phosphate metabolites and thus can characterize cellular energetic state. It can also be used to determine the intracellular pH. The specific exercise protocol outlined in this thesis improves both the sensitivity and the selectivity of the diagnosis of mitochondrial disease, even when little or no muscle symptoms are present. It is also a useful technique to monitor drug therapy of patients with mitochondrial myopathy. The most important feature of the spiral resonator surface coil, developed during the course of our clinical investigation, is its flexibility with respect to the location where it can operate. Its stability and improved sensitivity are added advantages. Potential extension of the spiral resonator surface coil design to observe other nuclei of biological interest, such as C-13, as well as the adaptation of our clinical protocol to study the effect on muscular function of patients with Acquired Immune Deficiency Syndrome (AIDS) during anti-HIV drug therapy (AZT or DDI) have been explored and experimentally demonstrated. At the time when this work was initiated, only the research groups of Britton Chance in Philadelphia, George Radda in Oxford, plus a few others were active in the use of P-31 NMRS to study intact muscle weakness. Since then, worldwide interest has increased; it is our hope that the technique developed at UBC with limited resources will be easily implemented in many other NMR facilities.
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 | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| 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) | 0,001 | 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 ».