Comparison of the electrophysiological pattern of fatigue between athletes required to perform explosive and endurance sports

The electrophysiological behavior of an isometric contraction sustained to fatigue, was examined in 6 long distance runners and 9 athletes involved in explosive (burst) sports, by on line computer analysis of the electrical activity of vastus medialis, rectus femoris and vastus lateralis. The experiments were carried out with a counterload of 50% of the maximal strength of the muscle. The duration of spike increased and the frequency decreased in the 3 examined muscles, in both types of sport. In the burst sports the changes of value of both parameters were statistically significant in the 3 muscles. In endurance sports the variations of duration were not significant and the changes of frequency were statistically significant only in the vastus lateralis. These results could be explained by the gradual activation of motor units of more strikingly different sizes in burst sports. Thus it may be speculated that prolonged training in burst sports may result in the automatic mobilization of higher number of small motor units, for the initiation of contraction while in endurance sports the onset of contraction is more gradual and carried out by large motor units.     

Material surfaces affect the protein expression patterns of human macrophages: A proteomics approach

Monocyte-derived macrophages (MDM) are key inflammatory cells and are central to the foreign body response to implant materials. MDM have been shown to exhibit changes in actin cytoskeleton, multinucleation, cell size, and function in response to small alterations in polycarbonate-urethane (PCNU) surface chemistry. Although PCNU chemistry has an influence on de novo protein synthesis, no assessments of the protein expression profiles of MDM have yet been reported. The rapid emerging field of expression proteomics facilitates the study of changes in cellular protein profiles in response to their microenvironment. The current study applied proteomic techniques, 2-dimensional electrophoresis (2-DE) combined with MALDI-ToF (matrix assisted laser desorption ionization-time of flight) mass spectrometry, to determine differences in MDM protein expression influenced by PCNU. Results indicated that MDM responded to material chemistry by modulation of structural proteins (i.e. actin, vimentin, and tubulin). Additionally, intracellular protein modulation which requires proteins responsible for trafficking (i.e. chaperone proteins) and protein structure modification (i.e. bond rearrangement and protein folding) were also altered. This study demonstrated for the first time that a proteomics approach was able to detect protein expression profile changes in MDM cultured on different material surfaces, forming the basis for utilizing further quantitative proteomics techniques that could assist in elucidation of the mechanisms involved in MDM-material interaction.     

Air-fluid levels within lung bullae associated with pneumonitis

Although air-fluid levels occur commonly within lung bullae, this entity in association with non-tuberculous pneumonitis has received neither adequate nor recent emphasis. We observed ten male patients with pre-existing bullous disease whose chest radiographs showed a pulmonary infiltrate adjacent to thin-walled air space(s) with one or more air-fluid levels. Six patients were symptomatic and only one was acutely ill. Fiberoptic bronchoscopy (8/10 patients) revealed no evidence of endobronchial disease, tuberculosis, or cancer. Air-fluid levels disappeared within 3 days to 36 weeks (mean, 11 weeks), while the alveolar infiltrate cleared at a slower rate. Although the mechanism of fluid formation within a bulla is unknown, it may be analogous to the development of a parapneumonic pleural effusion. Fiberoptic bronchoscopy is useful to exclude the presence of an obstructing endobronchial lesion and to obtain secretions for cytology and culture of specific organisms. Recognition of this entity is important since radiographic resolution can be expected to be slow and surgical intervention is unnecessary.     

Use of ketoconazole in the treatment of a virilizing adrenocortical carcinoma

Ketoconazole, an oral antimycotic agent, is known to have a potent inhibitory effect on adrenal steroid production. It was given at a dose of 1200 mg/day to a 52-year-old female patient with a virilizing adrenocortical carcinoma in order to achieve better metabolic control pre-operatively. Together with a rapid normalisation of hypertension and hyperglycemia, a dramatic fall was noticed in serum and urinary adrenal steroids after a few days. Levels of total testosterone (20 nmol/l), androstenedione (greater than 35 nmol/l) and DHEA-sulphate (greater than 28 nmol/l) fell to normal levels in 6 days. By contrast, levels of 17-OH-progesterone (30 nmol/l) and progesterone (2.45 nmol/l) increased slightly, indicating inhibition of adrenal 17,20-lyase. Cortisol (620 nmol/l at 08.00 h) fell to very low levels (50 nmol/l) on day 6 of the trial. We conclude that ketoconazole is very effective in suppression of adrenal tumoural steroidogenesis and merits consideration in pre-operative use. We warn against dangerous hypoadrenalism which seems to occur earlier in tumoural than in normal adrenal metabolism.     

Coupling Between Mitochondrial Mutation and Energy Transduction

Upon incubation with ethidium bromide (Etd Br) isolated mitochondria of Saccharomyces cerevisiae have been shown to be capable of performing five novel reactions: (a) a single scission of their DNA (mtDNA) coincident with (b) the incorporation of Etd Br into the product (mtDNA --> 2 mtDNA'-Etd Br); (c) an energy- (and probably ATP-) requiring degradation of mtDNA'-Etd Br to acid-labile products. These reactions acting in series generate (d) a DNase dependent on both Etd Br and an energy supply with mtDNA'-Etd Br as an obligatory intermediate. Coincident with (d) there occurs (e) an activation of adenosinetriphosphatase. Experiments with specific inhibitors suggest that the enzyme responsible is the mitochondrial adenosinetriphosphatase complex itself, and that it and the ability to carry out reactions (a) through (e) are tightly coupled to the energy-transducing functions of the particle.