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Erythropoietin ( EPO) rapidly decreases on return to sea level ( SL) after chronic altitude exposure. Acute hypoxia may provide an additional stimulus to prevent the decline in EPO. Proinflammatory cytokines, interleukin-6 ( IL-6), and tumor necrosis factor alpha ( TNFα) have been shown to inhibit EPO production. Optimal normobaric hypoxic exposure has not been established; therefore, investigation of methods eliciting the greatest response in EPO to limit physiological stress is required. Eight men (age 27 ± 4 years, body mass 77.5 ± 9.0 kg, height 179 ± 6 cm) performed four passive exposures to different normobaric hypoxic severities [FiO2: 0.209 ( SL), FiO2: ~0.135 (3600 m), FiO2: ~0.125 (4200 m) and FiO2: ~0.115 (4800 m)] in a hypoxic chamber for 2 h. Venous blood was drawn pre-exposure and then at 1, 2, 4, 6, and 8 h to determine EPO concentration ([ EPO]), IL-6, and TNFα. During 4200 and 4800 m, [ EPO] increased from 5.9 ± 1.5 to 8.1 ± 1.5 mU/ mL ( P = 0.009) and 6.0 ± 1.4 to 8.9 ± 2.0 mU/ mL ( P = 0.037), respectively, with [ EPO] increase peaking at 4 h (2 h post-exposure). There were no differences in IL-6 or TNFα during or post-exposure. Increased [ EPO] was found 2 h post hypoxic exposure as result of 2 h of normobaric hypoxia ≥4200 m. There was no dose-response relationship in [ EPO] between simulated hypoxia severities. [ABSTRACT FROM AUTHOR]

The present study examined the use of the maximal lactate steady state (MLSS) as an exercise training stimulus in moderately trained runners. Fourteen healthy individuals (12 male, 2 female; age 25 ± 6 years, height 1.76 ± 0.05 m, body mass 76 ± 8 kg mean ± SD) took part in the study. Following determination of the lactate threshold (LT), VO2max, running velocity at MLSS (vMLSS) and a control period of 4 weeks, participants were pair matched and split into two cohorts performing either continuous (CONT: 2 sessions/ week at vMLSS) or intermittent treadmill running (INT: 2 sessions/week, 3-mm repetitions 0.5 km·h-1 above and below vMLSS). vMLSS increased in CONT by 8% from 12.3 ± 1.5 to 13.4 ± 1.6 km · h-1 (p <0.05) and in INT by 5% from 12.2± 1.9 km · h-1 to 12.9 ± 1.9 km · h-1 (p<0.05). Running speed at the LI increased by 7% in the CONT group (p <0.05) and by 9% in the INT group (p<0.05). VO2max increased by 10% in the CONT group (p <0.05) and by 6% in INT (p <0.05). Two sessions per week at vMLSS are capable of eliciting improvements in the physiological responses at LT, MLSS, and VO2max in moderately trained runners. [ABSTRACT FROM AUTHOR]

Accurate classification of VO2 kinetics is essential to correctly interpret its control mechanisms. The purpose of this study was to examine VO2 kinetics in severe and supra-maximal intensity running exercise using two modelling techniques. Nine subjects (mean +/- S.D: age, 27 +/- 7 years; mass, 69.8 +/- 9.0 kg; VO2max, 59.1 +/- 1.8 mL x kg x min(-1)) performed a series of "square-wave" exercise transitions to exhaustion at running speeds equivalent to 80% of the difference between the VO2 at LT and VO2max (delta), and at 100%, 110% and 120% VO2max. The VO2 response was modelled with an exponential model and with a semi-logarithmic transformation, the latter assuming a certain steady state VO2. With the exponential model there was a significant reduction in the "gain" of the primary component in supra-maximal exercise (167 +/- 5 mL x kg(-1) x km(-1) at 80% delta to 142 +/- 5 mL x kg(-1) x km(-1) at 120% VO2max, p = 0.005). The time constant of the primary component also reduced significantly with increasing intensity (17.8 +/- 1.1 s at 80% delta to 12.5 +/- 1.2 s at 120% VO2max, p < 0.05). However, in contrast, using the semi-log model, the time constant significantly increased with intensity (30.9 +/- 13.5 s at 80% delta to 72.2 +/- 23.9 s at 120% VO2max, p < 0.05). Not withstanding the need for careful interpretation of mathematically modelled data, these results demonstrate that neither the gain nor the time constant of the VO2 primary component during treadmill running are invariant across the severe and supra-maximal exercise intensity domains when fit with an exponential model. This suggests the need for a reappraisal of the VO2/work rate relationship in running exercise.

Eighty-three MR studies for primary bone tumors, performed with both spin echo and short time inversion recovery (STIR) sequences, were reviewed. Twenty-six patients underwent surgery within 10 days after MR imaging. Specimens were cut and directly compared with MR images. In the remainder, pathologic slides were compared in order to obtain a better understanding of MR pattern. All MR images were examined with a traditional morphologic approach and, upon comparison with surgical macroslides and with pathology samples, some MR distinctive patterns were identified: the bulky appearance of osteosarcoma surrounded by muscle edema, the multilobular high signal intensity (SI) chondroid lesions, the subtle infiltration of Ewing's sarcoma, rarely accompanied by muscle edema and prone to MR underestimation, the well defined "multiple shells" pattern of giant cell tumor, and the ill defined "storiform" appearance of malignant fibrous histocytoma are all typical MR features strictly corresponding to pathologic findings. The chondroid origin tumors may be identified based on the lobular high SI pattern whereas a benign fibrous lesion was the only one in this series to be distinguished relying on the SI. Peritumoral soft tissue edema was found by the STIR sequence only in malignant tumors (69%) of this series, and particularly in osteosarcoma (96%), chondrosarcoma (83%), and giant cell tumor (100%): this associate finding may further contribute to the diagnosis.

The accuracy of preoperative MRI in detecting tumor extent has been evaluated in 35 patients with primary bone neoplasms; intra-osseous extent was measured on MR images and compared with macroslides of surgical specimens in 26 cases. An almost completely accurate prediction of tumor size was obtained with the combined employment of Spin-Echo (SE) and Short Inversion Time Inversion Recovery (STIR) sequences in the various tumors, with the exception of two Ewing's sarcomas. Changes in Signal Intensity (SI) and tumor morphology were identified in those cases which had undergone presurgical chemotherapy; the reduction in SI and in tumor size or the appearance of a more homogeneous signal was correlated with a positive response to cytotoxic therapy. MR imaging fully satisfies surgeon's preoperative requirements in the assessment of therapy-responding neoplasms as well as in local tumor staging in all types of neoplasms, with the exception of Ewing's sarcoma.

The management of a case of Ewing's sarcoma of the left proximal humerus in a 15-year-old girl is presented, and the radiological and pathological findings are described. The chemotherapeutic, radiotherapeutic and surgical management of Ewing's sarcoma are discussed with reference to the case.

Sixty patients with primary bone tumours were evaluated with magnetic resonance imaging (MRI) at 0.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. The results have been reviewed in order to evaluate the accuracy of STIR and conventional SE sequences in the detection of tumours, the definition of intramedullary extent and soft-tissue involvement. The intraosseous neoplastic extent has been compared with macroslides of surgical specimens in 24 cases. The role of the STIR sequence in detection of recurrences in the post-surgical follow-up was also evaluated. The STIR sequence, designed to suppress signal from fat, also enhances the signal from tissue with long T1 and T2 relaxation times, such as neoplastic and inflammatory tissue. The STIR sequence with T1 of 120-130 ms in all cases suppressed the high signal from fatty bone marrow, giving a clear depiction of tumour extent, in both its intramedullary and soft-tissue components, and is superior to conventional SE images. The high sensitivity (100% of our cases) of this technique is counterbalanced by its lack of specificity: on STIR sequences both tumour and peritumorous oedema give an increase of signal intensity, limiting assessment of tumour extent. Peritumoral oedema, only present in our series in malignant neoplasms, may however be differentiated on the basis of the configuration of the abnormal areas, and by comparing STIR images with short repetition time/echo time sequence results.