Comparison of new iron chelating agents in the prevention of ischemia/reperfusion injury: a swine model of heart-lung transplantation.

The preservation of the heart and lung for transplantation remains a major concern in extended ischemic intervals. This experimental endeavor evaluates and compares the efficacy of iron chelating agents such as high molecular weight deferoxamine and 21-aminosteroid (U74006F) in a swine model of heart-lung transplantation. Heat-lung blocks were exposed to 4 h and 45 min of ischemia and 2 h of reperfusion. Animals were divided into three groups. Group A was a control without pharmacological intervention. In groups B and C, 21-aminosteroid (U74006F), 10 mg/kg, and high molecular weight deferoxamine, 50 mg/kg, were used, respectively. The results of functional parameters (cardiac index, stroke index, lung water, PO2, PCO2, alveolar-arterial gradient, and alveolar-arterial ratio) demonstrated superior heart and lung function for group C, where high molecular weight deferoxamine was used. Alterations of heart and lung function were significantly more (p less than .001) for control animals and for group B where U74006F was used. This study suggests that formation of hydroxyl radicals was affected by chelation of iron with high molecular weight deferoxamine, which reflects better heart and lung function and consequently less damage to this group of animals. The compound 21-aminosteroid U74006F failed to protect the heart and lung from ischemic-reperfusion injury in this model of heart-lung transplantation.     

Response to allopurinol pretreatment in a swine model of heart-lung transplantation

The role of allopurinol in the prevention of ischemia-reperfusion injury was assessed in a model of heart-lung transplantation. Fourteen swine were divided into two groups (seven donors and seven recipients). All heart and lung blocks were placed in hypothermic storage after perfusion with cold iso-osmolar cardioplegic solution and modified Collins solution, respectively (t = 8-10 degrees C for heart and t = 16-18 degrees C for lungs). The total ischemic time including the orthotopic transplantation was 6 h. Animals (donors and recipients) were pretreated with allopurinol given orally at a dosage of 50 mg/kg for 4 days. Animals were assessed by monitoring heart and lung function, including extravascular lung water at three time intervals, which included pretransplantation (donor), and 30 min and 2 h posttransplantation (recipient). Erythrocyte peroxidation susceptibility was assessed for 3 days, and surgery was performed on day 4. The malondialdehyde levels determined from erythrocyte exposure to in vitro peroxidative challenge classified three paired donor and recipient animals as responders and four paired donor and recipient animals as nonresponders to the allopurinol pretreatment. A persistent deterioration of lung function was observed over time in nonresponders (p less than .05) (increase of lung water, decrease of partial pressure of oxygen, increase in alveolar-arterial gradient, and decrease in arterial-alveolar tension ratio). Responders showed no significant alterations in lung function. This study in swine, a species devoid of myocardial xanthine oxidase activity, indicates that allopurinol may have a mechanism of action other than xanthine oxidase inhibition in the prevention of ischemia-reperfusion injury. The parallelism between protection of lung function and of red blood cells suggests the involvement of a generalized increase in tissue antioxidant capacity.     

Reversibility of opioid receptor occupancy of buprenorphine in vivo

The slow association and incomplete dissociation of buprenorphine from opioid receptors observed in vitro have been suggested to reduce the accessibility of opioid receptors in vivo. If so, it might be expected that buprenorphine continues to occupy opioid receptors long after the antinociceptive activity has dissipated. To examine this hypothesis, buprenorphine (46.4 microg/kg i.v.) was administered to rats 1, 2, 4 or 8 h before isolation of their forebrain membranes and the maximal binding capacity (Bmax) for [3H]-[D-Ala2, N-methyl-Phe4-Gly5-ol]-enkephalin ([3H]DAMGO) was determined to measure the number of mu-opioid receptor binding sites remaining. Extent and duration of the reduction of Bmax by buprenorphine (ED50 11.2 microg/kg 1 h post-application) correlated with the antinociceptive activity in the rat tail flick (ED50 16.4 microg/kg i.v. 1 h post-application). At 8 h after administration there was still residual antinociception but no further attenuation of Bmax was detectable. Thus receptor occupancy by buprenorphine does not cause impairment of mu-opioid receptor accessibility beyond the duration of its antinociceptive activity. Therefore, no impairment of antinociception in the case of an opioid switch is to be expected.     

Extremity salvage with a free musculocutaneous latissimus dorsi flap and free tendon transfer after resection of a large congenital fibro sarcoma in a 15-week-old infant. A case report

A case of complex microsurgical reconstruction of the dorsum of the foot, including tendon transfer following tumor resection, in a 15-week-old male infant is presented. After birth, a 5.5 x 4 cm large tumor was observed on the dorsum of the right foot. Biopsy showed a congenital malignant fibro sarcoma. After initial chemotherapy a radical excision of the tumor at the age of 14 weeks was followed. To cover the defect a musculocutaneous latissimus dorsi flap was taken, the cutaneous part being large enough to cover the defect. Extensor tendons were reconstructed with free tendon transplants. Amputation is usually indicated in these cases. To the best of our knowledge, microsurgical reconstruction in infants at this age with congenital malignant tumors has not yet been reported. The case shows that Plastic surgery can play an important role in pediatric oncology and should routinely be integrated into the multi-modal treatment concepts.     

Explosionsverletzungen der Hände

BACKGROUND: Blast injuries of the hand represent a demanding surgical emergency for the reconstructive hand surgeon. Commercially available fireworks are often regarded as less dangerous compared to combat ammunition, but the following examples demonstrate their real potential for devastating hand injuries. Some of the closed injuries can represent a pitfall for correct assessment of trauma severity. PATIENTS AND METHODS: Fifty patients who were seen after fireworks explosions from December 1995 until April 2005 were analyzed in respect to their patterns of injury and their subsequent surgical treatment. The severity was graded using the Hand Injury Severity Score (HISS). The majority of patients were injured during the New Year's day celebrations and presented with complex blast injuries due to commercially available, CE-certified fireworks. RESULTS: Depending on the size of the explosives comparable patterns of injury were seen. Larger shells led to traumatic subtotal amputations of the exposed fifth finger ray and thenar ray. Complex destructions with multiple fractures and avulsions of the midhand were also present. Smaller explosives caused multiple lacerations in the palm of the hand, subcutaneous flexor tendon ruptures, and closed fingertip fractures. DISCUSSION: Acute neurapraxias and neural compartment syndromes were clinically present. All patients (50) had to be operated primarily, and subsequent operations were necessary in 19 cases (number of operations 1-4, med. 1). In the HISS grading, 18 "minor" (HISS <20), 16 "moderate" (HISS 21-50), 7 "severe" (HISS 51-100), and 9 "major" (HISS >100) explosion injuries were present (range: 2-155, med. 47). CONCLUSION: Blast injuries of the hand need a fast, strategically planned surgical approach. This is also true for presumably harmless, CE-certified fireworks. In a multiple patient scenario, triage based on surgical urgency may be necessary. A detailed clinical examination and surgical exploration is mandatory to avoid possible pitfalls like in closed injuries. Profound skills in reconstructive and microvascular hand surgery are essential to achieve an optimal clinical outcome.     

Revitalization of cortical bone allograft by application of vascularized scaffolds seeded with osteogenic induced adipose tissue derived stem cells in a rabbit model

Background  

Adipogenous tissue derived stem cells (ASC) are available in abundance in the human body and can differentiate in the presence of lineage-specific induction factors, for example, in myogenic, adipogenic, chondrogenic and osteogenic cells. The aim of this study was to evaluate the impact of osteogenic induced ASC’s (O-ASC) on revascularization and cellular repopulation of avital cortical bone employing a vascularized bovine scaffold.     

Revision surgery after trapeziometacarpal arthroplasty

Background  

The majority of patients with trapeziometacarpal joint (TMJ) arthritis can be successfully treated with some form of arthroplasty. Residual pain therefore is rather uncommon, but particularly difficult to treat. The aims of this study were to determine the number of patients in need of additional surgery; to identify the most common causes for persistent pain and to establish a treatment algorithm.