A comparative study of interval and conventional training in thoroughbred racehorses

Eight horses with previous racing experience were used in a comparative study of training methods for Thoroughbred racehorses. They were randomly assigned to two groups of four horses each. One group was trained using an interval training method (IT) and the other using conventional training (CT) methods. Peak heart rates, heart rate recovery curves, peak plasma lactate levels, plasma lactate clearance rates and run times were used to evaluate differences in the training methods. Peak heart rates, heart rate recovery curves, and run times were not significantly different between the groups. However, higher lactate production and increased plasma lactate clearance by the IT group demonstrated an increased anaerobic capacity.     

A two-step, two-signal model for the primary activation of precursor helper T cells

I present here a new model for the primary activation of precursor helper T cells. Observations demonstrate that the immune system learns not to respond to extrathymic, organ-specific self-antigens because of their early appearance in development. The immune system thus discriminates between peripheral self-antigens and foreign antigens and, when mature, usually makes an immune response against only the latter. Contemporary models for the activation and inactivation of T helper (Th) function do not account for such discrimination. The model proposed here is consistent with contemporary findings and incorporates a mechanism of peripheral self-nonself discrimination.     

Modulation of mitochondrial respiration by nitric oxide: investigation by single cell fluorescence microscopy

With the electro-driven import of rhodamine 123, we used single cell fluorescence microscopy to single out the contribution of nitric oxide (NO) in controlling mitochondrial membrane potential expressed by (stationary growing) rhabdomyosarcoma and neuroblastoma cells in culture. The experimental design and the computer-aided image analysis detected and quantitated variations of fluorescence signals specific to mitochondria. We observed that 1) the two cell lines display changes of fluorescence dependent on mitochondrial energization states; 2) mitochondrial fluorescence decreases after exposure of the cells to a NO releaser; 4) the different fluorescence intensity measured under stationary growing conditions, or after activation and inhibition of constitutive NO synthase, is consistent with a steady-state production of NO. Direct comparison of single cell fluorescence with bulk cytofluorimetry proved that the results obtained by the latter method may be misleading because of the intrinsic-to-measure lack of information about distribution of fluorescence within different cell compartments. The kinetic parameters describing the reactions between cytochrome oxidase, NO, and O2 may account for the puzzling (20-fold) increase of the KM for O2 reported for cells and tissues as compared to purified cytochrome c oxidase, allowing an estimate of in vivo NO flux.