The management of delayed union and nonunion of the metacarpals and phalanges

Nonunion and delayed union of the tubular bones of the hand are uncommon occurrences, but are often associated with functional deficits. Twenty-five consecutive phalangeal and metacarpal nonunions and delayed unions in patients seen at the Massachusetts General Hospital were reviewed and classified by the criteria of Weber and Cech. Most of the patients treated had inadequate or improper primary Kirschner wire fixation. Secondary treatment depended upon the associated disability. In seven cases treatment was by bone excision, arthrodesis, or arthroplasty. No treatment was given in four cases. Fourteen patients had operations to gain skeletal union. Rigid skeletal fixation with plates or lag screws was used in seven cases and permitted rapid postoperative mobilization of soft tissue and joint.

Effects of soluble stimuli on human monocyte secretion

We report here that the chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP), and the mitogenic phorbol ester, phorbol myristate acetate (PMA) cause a time- and concentration-dependent, selective, extracellular release of N-acetyl-beta-glucosaminidase and lysozyme from freshly isolated, adherent human peripheral blood monocytes. The inability of the protein synthesis inhibitor, cycloheximide, to influence enzyme release indicates that these enzymes are constitutive secretory products. 1-O-Hexadecyl-/octadecyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine demonstrated moderate secretory activity, whereas pepstatin A, concanavalin A, and leukotriene B4 were essentially inactive. FMLP- and PMA-induced enzyme release were inhibited with the intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-(3,4,5-trimethoxy)benzoate hydrochloride and the anion channel blocker, 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene. These results demonstrate the capacity of soluble, surface-active stimuli to activate the human monocyte secretory process.

Effects of glucocorticoids on glutamine metabolism in visceral organs

The effect of dexamethasone on interorgan glutamine exchange was studied in order to gain further understanding of the changes in nitrogen metabolism that occur following catabolic illness. In addition to studying glutamine, which transports as much as 40% of whole blood amino acid nitrogen, we determined the fluxes of glutamate, alanine, and glucose across the gastrointestinal tract, liver, and kidneys in 25 awake, chronically-catheterized dogs. Studies were performed during a control period and after dexamethasone (DEX) treatment (0.44 mg/kg X day) for two (DEX 2) and nine (DEX 9) days. Following dexamethasone treatment, arterial concentration of glutamine and glutamate fell, while alanine and glucose levels increased. Glutamine uptake by the intestine doubled with DEX (control 0.96 +/- 0.13 mumol/kg X min v 2.23 +/- 0.24 on DEX 2, P less than 0.001, and 1.59 +/- 0.20 on DEX 9, P less than 0.05). Alanine was produced by the intestine in controls (1.96 +/- 0.30 mumol/kg X minute), and release rate increased twofold on DEX 2 (4.10 +/- 0.66, P less than 0.01). The liver remained in balance for glutamine during both the control state and following DEX treatment, while renal glutamine uptake and renal glucose release were significantly increased after DEX. Glucocorticoids influence amino acid and glucose metabolism in the gastrointestinal tract, liver, and kidneys. The marked increase in glutamine extraction and alanine production by the intestine in response to glucocorticoids suggests that altered gastrointestinal amino acid metabolism may contribute to both the low glutamine levels and the accelerated gluconeogenesis that occur during catabolic illness.

Allograft bone for metacarpal reconstruction

Banked allograft bone has been used for metacarpal reconstruction in 10 patients. In one patient, allograft replaced the shafts of the fourth and fifth metacarpals that were lost as the result of an injury from an explosion. In the remaining nine, allograft was used as an intercalary bone after distraction lengthening of the metacarpal. The first metacarpal was lengthened in seven patients; four had hypoplasia of the thumb and three had partial thumb amputation. One patient with hypoplasia of the ulnar side of the hand had the fourth and fifth metacarpals lengthened, and the fifth metacarpal was lengthened in another. Of the 12 allografts used, radiographic and clinical evidence of bone union occurred at 23 of the 24 allograft/recipient bone interface sites. Most patients had no callus formation. This suggested primary bone healing. Recipient new bone appeared to cross the recipient/donor interface and replace the allograft by "creeping substitution" within 6 months to 1 year. The density and trabecular pattern of the allograft bone gradually assumed that of the recipient's bone. There was no clinical or radiographic evidence of rejection and no evidence of infection, abnormal swelling, or bone resorption. Nine of the 10 patients had improved function as determined by objective and subjective evaluation. Banked allograft bone offers two advantages over autogenous bone for reconstructive hand surgery: There is no donor site morbidity, and large defects can be filled with cylindric cortical bone of appropriate size and shape, which offers excellent stability as an intercalary graft.

Regulation of glutamine production by skeletal muscle cells in culture

Cells of the L6 rat myogenic line consume glutamine in contrast to skeletal muscle in vivo, which produces glutamine. The basis of glutamine consumption in the cultured cells and the conditions under which net glutamine production occurs were investigated. After treating cultures with cytosine-1-beta-D-arabinofuranoside to eliminate replicating myoblasts remaining after differentiation, the L6 cells continued to consume glutamine from medium containing normal plasma levels (650 microM). Consumption declined when cells were incubated with 325 microM glutamine, and, at 0 microM, net production occurred. In addition to the tendency to consume glutamine, the cells rapidly consumed glutamic acid. When medium glutamic acid was increased from 70 to 150, 500, and 1,000 microM, glutamine production increased. Alterations in levels of NH3, the other substrate for glutamine synthesis, did not have this effect. The L6 cells were found to have glutamine synthetase activity similar to normal rat skeletal muscle but markedly increased glutaminase activity. In spite of the imbalance in synthetic and degradative activities, however, inhibitor studies with L-methionine sulfoximine and 6-diazo-5-oxo-L-norleucine showed that flux through both pathways influenced net glutamine production.