Nicholas B. Vedder

Leukocytes have been shown to play an important role in the development of isolated organ injury after experimental ischemia and reperfusion. To examine the role of leukocytes in generalized ischemia-reperfusion injury we used the MAb 60.3 (directed to the human leukocyte adherence glycoprotein, CD18) to block leukocyte adherence functions in a rabbit model of hemorrhagic shock and resuscitation. In control animals subjected to 1 h of shock (mean blood pressure 45 torr and mean cardiac output 30% of baseline) followed by resuscitation, only 29% survived 5 d. All had gross and histologic evidence of injury to lungs, liver, and gastrointestinal mucosa. In contrast, 100% of the MAb 60.3-treated animals survived 5 d (P less than 0.01) and organ injury was absent or markedly attenuated. The control animals also had a persistent acidosis, lost more weight, and had evidence of continued gastrointestinal bleeding in contrast to MAb 60.3-treated animals. We conclude that increased leukocyte adhesiveness plays an important role in the development of multiple organ injury and death after generalized ischemia-reperfusion and that this injury may be significantly reduced by blocking leukocyte adherence functions with the MAb 60.3.

BACKGROUND: It is essential to identify patients at high risk of death and complications for future studies of interventions to decrease reperfusion injury. METHODS: We conducted an inception cohort study at a Level I trauma center to determine the rates and predictors of death, organ failure, and infection in trauma patients with systolic blood pressure < or = 90 mm Hg in the field or in the emergency department. RESULTS: Among the 208 patients with hemorrhagic shock (blood pressure < or = 90 mm Hg), 31% died within 2 hours of emergency department arrival, 12% died between 2 and 24 hours, 11% died after 24 hours, and 46% survived. Among those who survived > or = 24 hours, 39% developed infection and 24% developed organ failure. Increasing volume of crystalloid in the first 24 hours was strongly associated with increased mortality (p = 0.00001). CONCLUSION: Hemorrhage-induced hypotension in trauma patients is predictive of high mortality (54%) and morbidity. The requirement for large volumes of crystalloid was associated with increased mortality.

The mechanism whereby the human neutrophil membrane heterodimer, CD11b/CD18 (Mac-1, Mo1), mediates neutrophil adherence is not known. We studied the role of CD11b/CD18 surface expression in the promotion of neutrophil adhesiveness. We found that phorbol myristate acetate (PMA), calcium ionophore (A23187), and FMLP caused a three- to sevenfold increase in surface expression of both CD11b (alpha M) and CD18 (beta) as assayed by binding of MAbs 60.1 (anti-CD11b) and 60.3 (anti-CD18). Increased binding of MAbs was temporally associated with the promotion of neutrophil aggregation and adherence to cultured endothelial monolayers. Pretreatment of neutrophils with the anion channel-blocking agent, DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid), inhibited the increased surface expression of CD11b and CD18 after stimulation by PMA, A23187, or FMLP and resulted in nearly complete inhibition of neutrophil aggregation. However, pretreatment with DIDS did not diminish either PMA-, A23187-, or FMLP-stimulated neutrophil adherence to endothelial monolayers. We also observed that stimulation of granule-depleted neutrophil cytoplasts by PMA, A23187, or FMLP induced aggregation and adherence to endothelial monolayers without increasing surface expression of CD11b or CD18. We conclude that the increased surface expression of CD11b/CD18 that occurs after stimulation is neither sufficient nor necessary for enhanced adherence to endothelium. Moreover, though both are CD11b/CD18-dependent, the mechanisms involved in neutrophil aggregation are different from those involved in neutrophil adherence to endothelium.

Metacarpal fractures comprise between 18-44 % of all hand fractures. Non-thumb metacarpals account for around 88 % of all metacarpal fractures, with the fifth finger most commonly involved [19]. The majority of metacarpal fractures are isolated injuries, which are simple, closed, and stable. While many metacarpal fractures do well without surgery, there is a paucity of literature and persistent controversy to guide the treating physician on the best treatment algorithm. The purpose of this article is to review non-thumb metacarpal anatomy and treatment protocols for nonoperative management of stable fractures, and compare existing literature on surgical techniques for treatment of acute fractures and complications.