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The on- and off-transient (i.e. phase II) responses of pulmonary oxygen uptake (V(O(2))) to moderate-intensity exercise (i.e. below the lactate threshold, theta;(L)) in humans has been shown to conform to both mono-exponentiality and 'on-off' symmetry, consistent with a system manifesting linear control dynamics. However above theta;(L) the V(O(2)) kinetics(More)
Cell growth (accumulation of mass) needs to be coordinated with metabolic processes that are required for the synthesis of macromolecules. The PI3-kinase/Akt signaling pathway induces cell growth via activation of complex 1 of the target of rapamycin (TORC1). Here we show that Akt-dependent lipogenesis requires mTORC1 activity. Furthermore, nuclear(More)
1. A prior bout of high-intensity square-wave exercise can increase the temporal adaptation of pulmonary oxygen uptake (.V(O2)) to a subsequent bout of high-intensity exercise. The mechanisms controlling this adaptation, however, are poorly understood. 2. We therefore determined the dynamics of intramuscular [phosphocreatine] ([PCr]) simultaneously with(More)
Proton spectroscopy can noninvasively provide useful information on brain tumor type and grade. Short- (30 ms) and long- (136 ms) echo time (TE) (1)H spectra were acquired from normal white matter (NWM), meningiomas, grade II astrocytomas, anaplastic astrocytomas, glioblastomas, and metastases. Very low myo-Inositol ([mI]) and creatine ([Cr]) were(More)
For more than half a century it has been generally believed that cancer cells are more acidic than normal cells. This dogma arose from the studies of Warburg and co-workers (Warburg, 1930) who showed that tumour cells preferentially convert glucose and other substrates to lactic acid, even under aerobic conditions. Since lactic acid has a pK of 3.7 it(More)
1. In the non-steady state of moderate intensity exercise, pulmonary O2 uptake (Vp,O2) is temporally dissociated from muscle O2 consumption (Vm,O2) due to the influence of the intervening venous blood volume and the contribution of body O2 stores to ATP synthesis. A monoexponential model of Vp,O2 without a delay term, therefore, implies an obligatory(More)
PURPOSE To determine if short echo time (TE) (1)H magnetic resonance spectroscopy (MRS) can distinguish between intracranial metastases and glioblastomas. MATERIALS AND METHODS TE 30-msec spectra were acquired (1.5 T) from voxels entirely within tumors from 23 glioblastoma patients and 24 metastases patients (3 breast carcinomas, 1 bladder carcinoma, 8(More)
The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient(More)
The dynamics of pulmonary O(2) uptake (Vo(2)) during the on-transient of high-intensity exercise depart from monoexponentiality as a result of a "slow component" whose mechanisms remain conjectural. Progressive recruitment of glycolytic muscle fibers, with slow O(2) utilization kinetics and low efficiency, has, however, been suggested as a mechanism. The(More)
Automated pattern recognition techniques are needed to help radiologists categorize MRS data of brain tumors according to histological type and grade. A major question is whether a computer program "trained" on spectra from one hospital will be able to classify those from another, particularly if the acquisition protocol is different. A subset of 144(More)