Intraadrenal steroid metabolism in the guinea pig: guinea pig adrenal microsomes metabolize androstenedione in a manner distinct from liver microsomes.

Several immunochemical homologs of hepatic cytochromes P450 (CYPs) capable of steroid catabolism have been identified in the guinea pig adrenal cortex. Their predominance in males suggests a role in sex-differentiated metabolism of androgens. Therefore, we examined the ability of microsomes from male guinea pig adrenals and liver to metabolize androstenedione. Microsomes were incubated in the presence of radiolabeled steroids, the products of the reaction extracted, separated by TLC, and visualized by autoradiography. Metabolites were identified by comigration with commercially available standards in several solvent systems, in one and two dimensional TLC. Microsomes from both tissues metabolized androstenedione. However, the products formed differed markedly in the two tissues. Liver microsomes formed one major metabolite, testosterone. It represented 85% of the metabolized androstenedione. 6 beta-Hydroxylated androstenedione and testosterone each comprised 3-4% of the liver metabolites. In addition, at least 10 other products were formed, but taken together they constituted less than 8% of the metabolized androdostenedione. Adrenal microsomes, on the other hand, produced several major metabolites: 16 alpha-, 16 beta-, and 6 beta-hydroxy-androstenedione, plus one unidentified product constituted 93% of the metabolized androstenedione. 16 alpha-Hydroxylation of androstenedione was 60 fold, 16 beta-hydroxylation 12 fold, and 6 beta-hydroxylation 2.5 fold greater in adrenal than in liver microsomes. The unidentified product, which was the least polar, was formed exclusively by adrenal microsomes. The hydroxylation reactions performed by adrenal tissue are consistent with the presence in adrenal microsomes of immunochemical homologues of members of the CYP1A, 2B, 2C and 3A families which have known steroid hydroxylation functions in liver. The Kms of the formation of 16 alpha-, 16 beta- and 6 beta-hydroxyandrostenedione by adrenal microsomes are in the range reported for steroid hydroxylation reactions in rat liver tissue. Their distinct values suggest that these hydroxylation steps are performed by different CYPs. However, assignment of site-specific steroid hydroxylation reactions to individual hepatic CYP homologs in the adrenal requires further investigation and is being pursued using combined techniques of biochemistry and molecular biology.

Reconstruction of the extensor mechanism after proximal tibia endoprosthetic replacement.

The proximal tibia is a difficult area in which to perform a wide resection of a bone tumor. This difficulty is due to the intimate relationship of tumor in this location to the nerves and blood vessels of the leg, inadequate soft tissue coverage after endoprosthetic reconstruction, and the need to reconstruct the extensor mechanism. Competence of the extensor mechanism is the major determinant of functional outcome of these patients. Between 1980 and 1997, 55 patients underwent proximal tibia resection with endoprosthetic reconstruction for a variety of malignant and benign-aggressive tumors. Reconstruction of the extensor mechanism included reattachment of the patellar tendon to the prosthesis with a Dacron tape, reinforcement with autologous bone-graft, and attachment of an overlying gastrocnemius flap. All patients were followed for a minimum of 2 years; 6 patients (11%) had a transient peroneal nerve palsy, 4 patients (7.2%) had a fasciocutaneous flap necrosis, and 2 patients (3.6%) had a deep wound infection. Full extension to extension lag of 20 degrees was achieved in 44 patients, and 8 patients required secondary reinforcement of the patellar tendon. Function was estimated to be good to excellent in 48 patients (87%). Reattachment of the patellar tendon to the prosthesis and reinforcement with an autologous bone-graft and a gastrocnemius flap are reliable means to restore extension after proximal tibia endoprosthetic reconstruction.

Palliative forequarter amputation for metastatic carcinoma to the shoulder girdle region: indications, preoperative evaluation, surgical technique, and results.

BACKGROUND AND OBJECTIVES: Uncontrolled metastatic carcinoma of the shoulder girdle is a difficult oncologic problem. This study reviews our experience with palliative forequarter amputation with emphasis on patient selection criteria, preoperative radiologic assessment, surgical technique, epineural postoperative analgesia, and clinical outcome. METHODS: Eight patients who underwent palliative forequarter amputation for metastatic carcinoma between 1980 and 1999 were analyzed retrospectively. Diagnoses included breast carcinoma (n = 3), squamous cell carcinoma (n = 2), hypernephroma (n = 2), and carcinoma of unknown origin (n = 1). All patients presented with severe, intractable pain and a useless extremity. Venography demonstrated obliteration of the axillary vein in each of the patients in whom this procedure was performed. Exploration of the brachial plexus confirmed tumor encasement and unresectability in all patients. Epineural catheters for bupivacaine infusion were placed for postoperative pain control. RESULTS: All patients experienced dramatic pain relief and improved mobility and overall function. Life-threatening hemorrhage and sepsis were alleviated. There were no instances of phantom limb pain or adverse psychological reactions, and no complications related to epineural analgesia. CONCLUSIONS: Palliative forequarter amputation is relatively safe and reliable and provides effective pain relief for selected patients with unresectable metastatic carcinoma to the axilla and bony shoulder girdle in whom radiotherapy and/or chemotherapy has not been effective. The triad of pain, motor loss, and an obliterated axillary vein is indicative of brachial plexus infiltration and unresectability.

Giant cell tumor of the hand: superior results with curettage, cryosurgery, and cementation.

At our institution giant cell tumors arising in all locations are treated with curettage, cryosurgery, and cementation to avoid resection or amputation, increase local tumor control over curettage alone, and avoid the morbidity associated with immobilization. We report the oncologic and functional results of 3 patients with giant cell tumors arising from the tubular bones of the hand who were treated in this manner. At a mean follow-up period of 54 months there were no local recurrences. No patient complained of pain. Digital range of motion and grip strength were within normal limits for all 3 patients. All patients returned to their previous occupational and recreational activities. One instance of minor wound necrosis was successfully treated conservatively. There were no other complications (fractures, infections, neuropraxias, or vascular damage). Curettage, cryosurgery, and cementation performed by experienced surgeons appears to be a safe, effective, and reliable method for treating selected giant cell tumors of the hand.