Effects of hydroxyethyl-starch-bound deferoxamine on ischemia/reperfusion injury in chronic nerve compression.

The authors have demonstrated previously that pretreatment with deferoxamine, an iron chelator and antioxidant, at the time of release in acute nerve compression, provided protection against ischemia/reperfusion (I/R) injury. In the present study, they evaluated whether therapeutic intervention with hydroxyethyl-starch-bound deferoxamine (HES-DFO) at the time of release of the chronically-compressed peripheral nerve protects the nerve from I/R injury. The sciatic nerves of 43 male Sprague-Dawley rats, weighing 325 to 350 g, were subjected to 8 weeks of compression with Silastic tubing. The treatment group received intravenous HES-DFO (70 mg/kg) at the time of decompression, while the control group received an equal volume of intravenous hetastarch vehicle at the same time schedule and route. Nerve-tissue samples from the compression site, as well as contralateral noncompressed nerves, were assayed for malondialdehyde (MDA), a marker of I/R injury. The control group exhibited MDA levels up to five times normal, and did not return to normal for 21 days. In contrast, the HES-DFO group had MDA levels that were not statistically significantly different from normal levels. The results confirm that pretreatment with HES-DFO prior to the surgical decompression of chronically-compressed nerve provides marked protection against I/R injury.

The histologic anatomy of the volar plate.

The volar plate (VP) is critical to the stability of the proximal interphalangeal joint. This study clarifies the macro- and micro-architectural structure of the VP and correlates these findings with its functional properties. Microscopic evaluation of cadaver specimens revealed a trilaminar structure of the VP with differential orientation and organization of collagen fibers in the volar, central core, and dorsal check rein sections of the plate. This description differs from the existing literature and adds to the understanding of the functional properties of the VP. The most important finding is a dense "basket weave" of collagen fibers oriented in 2 perpendicular planes within the central core of the VP. This orientation may contribute primarily to the resistance of the VP to both longitudinal and torsional stress. This study adds to the understanding of the histologic basis for the function of the VP and the mechanisms involved in its injury.

Efficacy of magnetic resonance angiography in the evaluation of vascular malformations of the hand.

Conventional arteriography has been the accepted standard technique for demonstrating the anatomic details in vascular malformations of the hand. The technique of magnetic resonance angiography provides detailed anatomy for vascular anomalies of the hand without the use of an invasive technique or contrast enhancement. When magnetic resonance angiography is combined with magnetic resonance imaging, the extent of the lesion with respect to the surrounding tissues and the flow characteristics of the lesion can be determined noninvasively. In our institution, magnetic resonance angiography has replaced conventional arteriography as the technique of choice for the evaluation of these lesions. This report evaluates the efficacy of magnetic resonance imaging/ magnetic resonance angiography in the management of vascular malformations of the hand. Ten consecutive patients over 30 months (median age 37 years) underwent magnetic resonance imaging/magnetic resonance angiography evaluation after the clinical diagnosis of a vascular malformation of the hand was made. Four patients in the group had conventional arteriography performed before referral. Magnetic resonance imaging/magnetic resonance angiography clearly defined the anatomic extent of the lesion, its relationship to surrounding tissues, and the flow characteristics in each patient. In the four patients in whom conventional arteriography had been performed, the magnetic resonance angiography findings matched the arteriographic findings. On the basis of the magnetic resonance imaging/magnetic resonance angiography findings, six patients were treated nonoperatively with compressive garments and four patients had operative treatment (resection of lesion n = 2, digital ray resection n = 2). In this series, magnetic resonance imaging/magnetic resonance angiography was efficacious in the management of vascular malformations of the hand. This technique provides detailed images of both the arterial and venous components of the lesions without the requirements of contrast enhancement, ionizing radiation, or an invasive procedure. Furthermore, the resectability can be determined based on the extent of involvement and the flow characteristics.

Effects of deferoxamine on ischemia/reperfusion injury after peripheral nerve compression.

We have demonstrated previously that acute nerve compression produces ischemia/reperfusion injury in rat sciatic nerve. In this study, we evaluated the effects of deferoxamine, an antioxidant, on recovery from ischemia/reperfusion injury after nerve compression. The sciatic nerves of male Sprague-Dawley rats, 370 to 430 g, were subjected to 24 hours of compression with Silastic tubing. The control group received intravenous saline solution at the time of decompression. The therapeutic group received intravenous deferoxamine (50 mg per kilogram) at the time of removal of the Silastic tubing. Nerve tissues within and distal to the compression site were assayed for malondialdehyde (MDA) levels and for growth-associated protein 43 (GAP-43) expression, as markers of ischemia/reperfusion injury and nerve regeneration, respectively. In the control group (injury alone), the MDA levels were three times higher than normal during the initial 10 days and returned to normal by 14 days. In contrast, the deferoxamine treatment group had MDA levels that were not significantly different from precompression levels. In the control group, enhanced GAP-43 expression persisted until late in the recovery period. In the deferoxamine treatment group, the increased GAP-43 expression subsided early. The results suggest that the treatment of compressed peripheral nerve with deferoxamine at the time of surgical decompression reduces ischemia/reperfusion injury.

Intestinal flora of the medicinal leech Hirudinaria manillensis.

Medicinal leeches are widely used to treat venous congestion in microvascular surgery. Aeromonas hydrophila infection, following application of the leech species Hirudo medicinalis, is a recognized complication. Administration of antibiotics directed at Aeromonas has been successful in minimizing complications of infection from this organism. A different leech species, Hirudinaria manillensis, has recently been introduced for microsurgical use. A study of the enteric content of 30 of these leeches showed that Aeromonas hydrophila was isolated in only 20 percent of animals, while the majority of remaining positive cultures were single and mixed gram-negative rods. All organisms isolated were sensitive to current recommended coverage for Aeromonas hydrophila. This study suggests that the enteric flora of different leech species may be variable and should be carefully characterized, to direct appropriate prophylactic therapy prior to release of new species for clinical use.

Efficacy of rapamycin and FK 506 in prolonging rat hind limb allograft survival.

OBJECTIVE: Graft rejection and the toxicity of current immunosuppressive regimens preclude the application of microsurgical advances to transplantation of limbs or other nonessential parts. If limb transplantation is to become a clinical reality, newer, safer, more effective immunosuppressive agents are needed. SUMMARY BACKGROUND DATA: Rapamycin (RPM) and FK 506 are fungal macrolide antibiotics with effective immunosuppressive properties demonstrated in several animal models. RPM is more potent and effective than is FK 506 in rat cardiac allografts and has demonstrated synergy with cyclosporine (CsA) in limb allograft models. METHODS: An orthotopic rat hind limb allograft model (Brown-Norway [RT-1n] to Lewis [RT-1(1)] rats was used. RPM (doses, 3.0, 4.5, and 6.0 mg/kg/day) was administered intraperitoneally on postoperative days 1 to 14. FK 506 (6 mg/kg/day) was administered orally on postoperative 1 to 14 and 1 to 90 and at rejection onset (10 mg/kg/day for salvage). CsA with RPM (postoperative days 1 to 14) was used to assess synergy, with CsA alone serving as the control. Other controls included untreated and placebo-treated allografted animals. The permutation test and Mann-Whitney test were applied to the data. RESULTS: The mean survival times were assessed as follows: (1) control (placebo, untreated), 5 days; (2) RPM groups, 9.5, 10.6, and 8.7 days; (3) 14-day FK 506, 28 days; (4) 90-day FK 506, > 90 days; (5) CsA, 17.3 days; and (6) CsA with RPM, 19.3 days. FK 506 significantly prolonged graft survival compared with RPM (Permutation Test, p < 0.001 and Mann-Whitney Test, p < 0.05). FK 506 salvage reversed early rejection. High-dose RPM produced significant toxicity. Synergy between CsA and RPM was not demonstrated. CONCLUSIONS: FK 506 prolongs allograft survival, reverses early rejection, and prevents rejection without clinical toxicity when given continually. RPM does not prevent rejection in this model and produces significant toxicity at high doses. FK 506 may be a first step in making limb transplantation a clinical reality in reconstructive surgery.

Successful treatment of coccidioidomycosis osteomyelitis in an infant.

A 10-month-old Hispanic male infant with expansile lesions of the third metacarpal and proximal phalanx positively diagnosed as Coccidioides immitis osteomyelitis is presented. Treatment consisted of combined surgical debridement and systemic antifungal therapy and resulted in complete resolution of the lesions. Treatment was guided by clinical response and complement fixation titers. Osteomyelitis is a relatively infrequent manifestation of disseminated coccidioidomycosis. Neonates and infants appear to be more susceptible to the development of dissemination, but less likely to develop toxicity due to systemic therapy. Current therapy consists of concomitant surgical excision of involved lesions and systemic antifungal therapy. Complement fixation titers correlate closely with clinical response to therapy and are useful in detecting subclinical recurrences.