Hemodynamic recovery after hypovolemic shock with lactated Ringer's and keratin resuscitation fluid (KRF), a novel colloid.

Death after severe hemorrhage remains an important cause of mortality in people under 50 years of age. Keratin resuscitation fluid (KRF) is a novel resuscitation solution made from keratin protein that may restore cardiovascular stability. This postulate was tested in rats that were exsanguinated to 40% of their blood volume. Test groups received either low or high volume resuscitation with either KRF or lactated Ringer's solution. KRF low volume was more effective than LR in recovering cardiac function, blood pressure and blood chemistry. Furthermore, in contrast to LR-treated rats, KRF-treated rats exhibited vital signs that resembled normal controls at 1-week.

Vasoactive properties of keratin-derived compounds.

OBJECTIVE: Keratin proteins have been utilized as biomaterials for decades, and are currently under investigation for a variety of tissue regeneration and trauma applications. It has been suggested that certain keratins may have the capacity to act as a colloid in fluid resuscitation applications, providing viscosity and oncotic properties that may be beneficial during acute ischemic events. Oxidized keratin derivatives, also known as keratoses, show good blood and cardiovascular compatibility and thus are the subject of this study. METHODS: The effects of keratose compounds will be assessed using a topload i.v. infusion model and observation of changes in the microvasculature of the cremaster muscle of rats. RESULTS: Keratose resuscitation fluid (KRF) administration resulted in significant vasodilation in the cremaster muscle. This effect was blocked with pretreatment of l-NA to inhibit NO. Another keratin fraction, alpha-keratose, which is the primary viscosic compound, was not found to induce vasodilation. CONCLUSIONS: The apparent mechanism of vasodilation was found to be NO-mediated and isolated to a particular purified fraction, the KAP.

Chemical denervation with botulinum neurotoxin a improves the surgical manipulation of the muscle-tendon unit: an experimental study in an animal model.

PURPOSE: The chemical denervation that results from botulinum neurotoxin A (BoNT-A) causes a temporary, reversible paresis that can result in easier surgical manipulation of the muscle-tendon unit in the context of tendon rupture and repair. The purpose of the study was to determine whether BoNT-A injections can be used to temporarily and reversibly modulate active and passive skeletal muscle properties. METHODS: Male CD1 mice weighing 40-50 g were divided into a 1-week postinjection group (n = 13: n = 5 saline and n = 8 BoNT-A) and a 2-week postinjection group (n = 17: n = 7 saline and n = 10 BoNT-A). The animals had in vivo muscle force testing and in vivo biomechanical evaluation. RESULTS: There was a substantial decline in the maximal single twitch amplitude (p < .05) and tetanic amplitude (p < .05) at one week and at 2 weeks after BoNT-A injection, when compared to saline-injected controls. BoNT-A injection significantly reduced the peak passive properties of the muscle-tendon unit as a function of displacement at one week (p < .05). Specifically, the stiffness of the BoNT-A injected muscle-tendon unit was 0.417 N/mm compared to the control saline injected group, which was 0.634 N/mm, a 35% reduction in stiffness (p < .05). CONCLUSIONS: Presurgical treatment with BoNT-A might improve the surgical manipulation of the muscle-tendon unit, thus improving surgical outcomes. The results implicate neural tone as a substantial contributor to the passive repair tension of the muscle-tendon unit. The modulation of neural tone through temporary, reversible paresis is a novel approach that might improve intraoperative and postoperative passive muscle properties, allowing for progressive rehabilitation while protecting the surgical repair site.