Purpose To investigate sex differences in the effect of a military field exercise on physical performance, body composition, and blood biomarkers. Methods Measurements were done in 23 male and 12 female conscripts before, and 0, 1, 3, 7, and 14 days after a 6‐day military field exercise. Results During the field exercise, body mass decreased more in men (−6.5 ± 1.1 kg) than in women (−2.7 ± 0.7 kg), and muscle mass decreased only in men (−2.7 ± 1.0 kg). Body composition recovered within one week. Performance decreased, with no differences between men and women for countermovement jump (CMJ,‐19 ± 8 vs. −18 ± 11%), medicine ball throw (MBT, −11 ± 7 vs. −11 ± 7%), and an anaerobic performance test (EVAC, −55 ± 22 vs. −47 ± 31%, men and women, respectively). MBT and EVAC performance recovered within two weeks, whereas CMJ performance was still reduced in men (−17 ± 6%) and women (−9 ± 8%) after two weeks recovery, with a larger reduction in men. Both men and women decreased [IGF‐1] (−28 ± 9 vs. −41 ± 8%) and increased [cortisol] (26 ± 26 vs. 66 ± 93%, men and women, respectively) during the exercise. Most biomarkers returned to baseline values within one week. Conclusions Men lost more body mass and muscle mass than women during a field exercise, but these differences did not lead to sex differences in changes in explosive strength and anaerobic performance. However, women recovered explosive strength in the legs faster than men.

Patients with highly hypoxic primary tumors show increased frequency of locoregional treatment failure and poor survival rates and may benefit from particularly aggressive treatment. The potential of gadolinium diethylene-triamine penta-acetic acid-based dynamic contrast-enhanced-MRI in assessing tumor hypoxia was investigated in this preclinical study. Xenografted tumors of eight human melanoma lines were subjected to dynamic contrast-enhanced-MRI and measurement of the fraction of radiobiologically hypoxic cells and the fraction of pimonidazole-positive hypoxic cells. Tumor images of K trans (the volume transfer constant of gadolinium diethylene-triamine penta-acetic acid) and v e (the fractional distribution volume of gadolinium diethylene-triamine penta-acetic acid) were produced by pharmacokinetic analysis of the dynamic contrast-enhanced-MRI data, and K trans and v e frequency distributions of the non-necrotic tumor tissue were established and related to the extent of hypoxia. Tumors showing high K trans values and high v e values had low fractions of hypoxic cells, whereas tumors showing both low K trans values and low v e values had high hypoxic fractions. K trans differentiated better between tumors with low and high hypoxic fractions than did v e . This study supports the current attempts to establish dynamic contrast-enhanced-MRI as a method for assessing the extent of hypoxia in human tumors, and it provides guidelines for the clinical development of valid assays. Magn Reson Med 67:519-530,

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been suggested to be a valuable method for characterizing the physiological microenvironment of tumors and thus a promising method for individualizing cancer treatment. The aim of this study was to test the hypothesis that valid parametric images of the tumor microenvironment can be obtained by pharmacokinetic analysis of DCE-MRI series. Cells of four human melanoma xenograft lines (A-07, D-12, R-18 and T-22) were used as preclinical models of human cancer. DCE-MRI was performed at 1.5 T at a spatial resolution of 0.23 x 0.47 x 2.0 mm(3) and a time resolution of 14 s. Gadolinium diethylene-triamine penta-acetic acid (Gd-DTPA) was used as contrast agent. The DCE-MRI data were analyzed on a voxel-by-voxel basis by using a pharmacokinetic model recommended for analysis of clinical DCE-MRI series. Parametric DCE-MR images were compared with tumor blood perfusion measured by the (86)Rb uptake method, and fractional volume of the extravascular extracellular space assessed by analysis of histological preparations. Parametric images reflecting tumor blood perfusion and fractional volume of the extravascular extracellular space were obtained. The numerical values of the DCE-MRI-derived parameters were not significantly different from the absolute values of tumor blood perfusion or fractional volume of the extravascular extracellular space in any of the tumor lines. This study shows that DCE-MRI can provide valid quantitative parametric images of the tumor microenvironment in preclinical cancer models and thus supports the suggestion that DCE-MRI may be developed to be a clinically useful method for individualization of microenvironment-based cancer treatment, a possibility that merits increased clinical interest.

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