Water metabolic parameter changes in rhesus monkeys during exposure to prolonged restriction of motor activity

The objective of this investigation was to determine the effect of prolonged restriction of motor activity (hypokinesia [HK]) on several parameters of water metabolism in primates. The studies were performed on 12 rhesus monkeys aged 4–5 yr (5.10–6.85 kg) during the hypokinetic period of 90 d and during the prehypokinetic period of 30 d. They were divided into two equal groups: the first group was placed under ordinary vivarium conditions (vivarium control animals) and the second group was subjected to 90 d of HK (hypokinetic animals). For the simulation of the hypokinetic effect, the primates were immobilized on their abdomens in special tables. The legs of the monkeys were immobilized with hip and knee joints extended. The primates retained freedom of movement at elbow, wrist, and ankle. During the preexperimental period of 30 d and during the experimental period of 90 d, the following variables were determined: body weight, total body fluid content, specific total body fluid, mean fluid consumed and eliminated in urine, specific plasma resistance, hematocrit level, and plasma concentrations of sodium (Na) and potassium (K). In the hypokinetic primates, body weight decreased significantly when compared to the controls. Mean fluid intake, total body fluid, and specific total body fluid decreased, whereas mean daily fluid loss and specific mean daily fluid elimination increased significantly. Specific plasma resistance, hematocrit level, and plasma electrolyte concentrations increased significantly when compared to the control primates. It was concluded that prolonged restriction of motor activity induces significant changes in water metabolic parameters of primates leading in decreased total water content of the body.     

Emergency Preservation and Resuscitation Trial: A Philosophical Justification for Non‐Voluntary Enrollment

In a current clinical trial for Emergency Preservation and Resuscitation (EPR), Dr. Samuel Tisherman of the University of Maryland aims to induce therapeutic hypothermia in order to ‘buy time’ for operating on victims of severe exsanguination. While recent publicity has framed this controversial procedure as ‘killing a patient to save his life’, the US Army and Acute Care Research appear to support the study on the grounds that such patients already face low chances of survival. Given that enrollment in the trial must be non‐voluntary, the study has received an exemption from federal standards for obtaining informed consent. How exactly, if at all, is non‐voluntary enrollment morally justifiable? In this essay, I appeal to the notable work of Hans Jonas in an effort to defend the EPR trial's use of non‐voluntary enrollment. It is often thought and, as I show, it may appear that Jonas has called for the end of experimental medical practice. Still, I derive from Jonas a principle of double‐effect upon which physicians may be seen as morally permitted to pursue innovations in emergency medicine but only as a byproduct of pursuing therapeutic success. With this position, I argue that the EPR trial can be granted a stronger philosophical justification than simply waiving the requirement of obtaining informed consent. The double‐effect justification would obtain, perhaps regardless of the success of such innovative procedures as therapeutic hypothermia.     

The fish tail as a derivation from axial musculoskeletal anatomy: an integrative analysis of functional morphology

The adult morphology of the tail varies greatly among extant fishes despite sharing both ontogenetic similarities and the functional need to propel the body through a fluid medium. Both sharks (Chondrichthyes) and ray-finned fishes (Actinopterygii) control caudal fin musculature independently of axial body myomere activity to modify the stiffness and shape of their tails. For example, sharks and bony fishes possess different structural elements and muscles and move their tails in different ways, resulting in different locomotory hydrodynamic effects and a range of performance variables including speed and maneuverability. The stiffness of the heterocercal, lobate tail of the shark can be modulated during the tail beat resulting in nearly continuous thrust production. In contrast, the highly flexible tail of ray-finned fishes can be manipulated into many different shape conformations enabling increased maneuverability for these fishes. Consequently, the developmental, morphological, and functional derivation of the tail from the axial trunk has resulted in a diversity of form, the attributes of which may be of ecological and evolutionary significance.