J Trauma
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The pin-bone interface is the weakest link in the mechanical stability of external skeletal fixation. In this investigation, a canine model was used to characterize the nature of cortical bone reactions at the pin-bone interface. Unilateral external fixators were applied to the tibiae of 61 dogs using six tapered cortical half-pins. ⋯ In inherently unstable oblique osteotomies, and less in stable rigidly fixed transverse osteotomies, immediate postoperative weight bearing caused bone thread resorption and adverse cortical bone remodeling at the entry cortex of external fixation half-pins. The unicortical loosening of half-pins that became evident during the first month of fixation obviously represents a consequence of micromotion and local bone yielding failure caused by high dynamic stresses of the pin-bone interface. Effective precautions should be taken to reduce such stresses.
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Prolonged hemorrhagic shock is characterized by the progression from hyperglycemia to hypoglycemia and failure to respond to standard methods of resuscitation. Previous studies have shown that the transition to irreversible shock is accompanied by attenuation of hepatic gluconeogenic capacity and a rising level of intracellular calcium. Additionally, it has been observed that diltiazem improves survival following prolonged hemorrhagic shock in rats. ⋯ In group A, hepatic glucose production was significantly elevated in DZ animals when compared with controls (p < 0.05). A similar significant improvement in gluconeogenesis was observed following 120 minutes of hemorrhagic shock in group B (p < 0.05). Additionally, treated rats (DZ, both groups A and B) demonstrated improved gluconeogenic response to substrate when compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)