Lasso locomotion expands the climbing repertoire of snakes

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Sway-dependent modulation of the triceps surae H-reflex during standing.

Previous research has shown that changes in spinal excitability occur during the postural sway of quiet standing. In the present study, it was of interest to examine the independent effects of sway position and sway direction on the efficacy of the triceps surae Ia pathway, as reflected by the Hoffman (H)-reflex amplitude, during standing. Eighteen participants, tested under two different experimental protocols, stood quietly on a force platform. Percutaneous electrical stimulation was applied to the posterior tibial nerve when the position and direction of anteroposterior (A-P) center of pressure (COP) signal satisfied the criteria for the various experimental conditions. It was found that, regardless of sway position, a larger amplitude of the triceps surae H-reflex (difference of 9-14%; P = 0.005) occurred when subjects were swaying in the forward compared with the backward direction. The effects of sway position, independent of the sway direction, on spinal excitability exhibited a trend (P = 0.075), with an 8.9 +/- 3.7% increase in the H-reflex amplitude occurring when subjects were in a more forward position. The observed changes to the efficacy of the Ia pathway cannot be attributed to changes in stimulus intensity, as indicated by a constant M-wave amplitude, or to the small changes in the level of background electromyographic activity. One explanation for the changes in reflex excitability with respect to the postural sway of standing is that the neural modulation may be related to the small lengthening and shortening contractions occurring in the muscles of the triceps surae.     

ATP-content and shape of erythrocytes during preservation with adenine and nucleosides]

ACD blood with additions of adenine (A, 0.5 mM in blood), ademine + guanosine ((AG, 0.5 mM each) and adenine + guanosine + inosine (IAG, 0.5: 0.5: 18 mM) was stored for 6 weeks at 4 degrees C and the morphological changes in connection with the ATP content were observed. After a storage of 6 weeks 2--3% of the cells were present as diskocytes, 60% as echinocytes, and 40% as spherocytes. The delayed morphological alterations in the ACD-AG blood in comparison with ACD-A blood were also reflected by a higher ATP content of the ACD-AG blood during its storage. The alterations in the form of erythrocytes recorded in the morphological index Im (a subdivision was made according to 6 different stages of form) correlated with the ATP content. The coefficient of correlation amounted to r = 0.85. Thus, Im is a reliable criterium for evaluating possible storage damages of stored erythrocytes.     

Individual recognition of contact calls by pygmy marmosets

Individual recognition by voice has been frequently assumed to be an important phenomenon in the social species. The present study on pygmy marmosets (Cebuella pygmaea) demonstrated that there are distinctive acoustic features in each of two contact calls by which individuals could be distinguished from each other. Individual pygmy marmosets responded differently depending on which type of contact call was given and on the identity of the vocalizing animal. Playbacks of individual calls through hidden speakers produced some evidence for differential individual responses, but only when they originated from familiar locations. These results indicate that pygmy marmosets recognize each other on the basis of their contact calls.     

Comparative morphology of the semispinalis-spinalis muscle of snakes and correlations with locomotion and constriction

Segments of the spinalis portion of the M. semispinalis-spinalis (SSP) were examined in 107 snakes representing 94 species, 85 genera, and 11 families. Allowing for slight variation within individuals and species, the following generalizations can be made. (1) Three major types of segments of the SSP were found in Typhlops, booids, and colubroids. (2) Within each type, differences in the segmental length of the spinalis result primarily from different lengths of the anterior tendons. (3) Specializations in habitat and locomotor modes usually account for variations in the segmental lengths of the spinalis. (4) Constrictors seem to have undergone selection for increased flexibility which is gained by having relatively more vertebrae and, in some cases, shorter muscle segments.     

How swimming fish use slow and fast muscle fibers: implications for models of vertebrate muscle recruitment

We quantified the intensity and duration of electromyograms (emgs) from the red and white axial muscles in five bluegill sunfish (Lepomis macrochirus) which performed three categories of behavior including steady swimming and burst and glide swimming at moderate and rapid speeds. Steady swimming (at 2 lengths/s) involved exclusively red muscle activity (mean posterior emg duration = 95 ms), whereas unsteady swimming utilized red and white fibers with two features of fiber type recruitment previously undescribed for any ectothermic vertebrate locomotor muscle. First, for moderate speed swimming, the timing of red and white activity differed significantly with the average onset time of white lagging behind that of red by approximately 40 ms. The durations of these white emgs were shorter than those of the red emgs (posterior mean = 82 ms) because offset times were effectively synchronous. Second, compared to steady and moderate speed unsteady swimming, the intensity of red activity during rapid unsteady swimming decreased while the intensity of white muscle activity (mean white emg duration = 33 ms) increased. Decreased red activity associated with increased white activity differs from the general pattern of vertebrate muscle recruitment in which faster fiber types are recruited in addition to, but not to the exclusion of, slower fiber types.     

Ibuprofen 400 mg is effective in women, and women are well represented in trials

Background  

A recent article in the New Scientist argued that women were under-represented in clinical trials which, until now, had masked the finding that ibuprofen 400 mg was ineffective in women.