The functional outcome with metallic radial head implants in the treatment of unstable elbow fractures: a long-term review.

BACKGROUND: A long-term review of metal prosthetic radial head replacement in patients with radial head fractures associated with gross instability of the elbow has been performed. METHOD: Twenty patients were reviewed using a modified Mayo Clinic functional rating index system. The mean follow-up was 12.1 years, with a range from 6 to 29 years. RESULTS: Results were excellent in 12 patients, good in 4 patients, fair in 2 patients, and poor in 2 patients. A metal radial head replacement restored elbow stability when fracture of the radial head occurred in combination with dislocation of the elbow, rupture of the medial collateral ligament, fracture of the proximal ulna, and/or fracture of the coronoid process. CONCLUSION: We conclude that a metal radial head prosthesis has select indications. We advocate its use when the radial head cannot be reconstructed in the setting of a clinically unstable elbow. Results suggest that it functions well on a long-term basis.

Antiviral activity of 3-methyleneoxindole.

3-Methyleneoxindole (MO), an oxidation product of the plant auxin indole-3-acetic acid, can selectively inhibit the replication of herpes-, mengo-, polioviruses, and Sindbis virus. The antiviral action of MO, a sulfhydryl binding compound, is neutralized by 2-mercaptoethanol if the latter is added soon after exposure of infected cells to MO. If addition of 2-mercaptoethanol is delayed, the antiviral action of MO appears to be irreversible. Data are presented which indicate that the antiviral action of MO is not mediated by interferon.

Mechanism of the antiviral action of 3-methyleneoxindole.

The biochemical basis underlying the antiviral action of 3-methyleneoxindole (MO), a plant metabolite, was examined in HeLa cells infected with poliovirus. In the presence of antiviral concentrations of MO, poliovirus-specific ribonucleic acid (RNA) synthesis can proceed normally, and the RNA synthesized under such conditions is infectious. It is suggested that the ability of MO to bind to ribosomes of HeLa cells may underlie the antiviral affect. Data are presented which indicate that poliovirus messenger RNA cannot attach to those ribosomes which already are bound to MO. Consequently, virus-specific polysomes cannot be recovered from infected cells treated with antiviral concentrations of MO. In contrast, antiviral concentrations of MO do not prevent the formation of polysomes in uninfected HeLa cells.

Bactericidal action of sulfhydryl binding compounds.

An oxidation product of indole-3-acetic acid, 3-methyleneoxindole, is highly reactive with free sulfhydryl groups. It has been shown to be a potent bactericidal agent in actively growing cultures. The bactericidal action of 3-methyleneoxindole was found to be independent of protein or deoxyribonucleic acid synthesis but to require the capacity for ribonucleic acid synthesis. The reactions underlying the bactericidal effect of 3-methyleneoxindole are not unique to it among compounds which can bind free SH groups, since N-ethylmaleimide appeared to have a similar mode of action.

Auxin activity of 3-methyleneoxindole in wheat.

A product of the enzymatic oxidation of indole-3-acetic acid, 3-methyleneoxindole, is at least 50-fold more effective than indole-3-acetic acid in stimulating the growth of wheat (Triticum vulgare, red variety) coleoptiles. Ethylenediaminetetra-acetic acid can antagonize the growth-stimulating properties of the parent compound, indole-3-acetic acid, presumably by chelating Mn(2+), which is required for the enzymatic oxidation of indole-3-acetic acid. The growth stimulating effect of 3-methyleneoxindole, a product of the blocked reaction, on the other hand, is still evident in the presence of ethylenedia-minetetraacetic acid. In the presence of 2-mercaptoethanol, indole-3-acetic acid fails to stimulate the elongation of wheat coleoptiles. The property of binding to sulfhydryl compounds including 2-mercaptoethanol is unique to 3-methyleneoxindole among indole-3-acetic acid and its oxidation products. These findings suggest that 3-methyleneoxindole is an obligatory intermediate in indole-3-acetic acid induced elongation of wheat coleoptiles.

Enzymatic dehydration of 3-hydroxymethyloxindole.

Crude and partially purified extracts of wheat (Triticum vulgare, red variety) germ catalyze the dehydration of 3-hydroxymethyloxindole to 3-methyleneoxindole. Examination of the ultraviolet absorption spectrum of a reaction mixture consisting of either the extract or partially purified enzyme and 3-hydroxymethyloxindole, shows that this oxindole has undergone complete dehydration to 3-methyleneoxindole. TPNH-linked 3-methyleneoxindole reductase, also a constituent of the wheat germ extract, can be separated from the dehydrase by passage through an Agarose 15 column. Utilizing these partially purified enzymes, it can be demonstrated that the dehydrase activity found in wheat germ is a discrete enzymatic function.

The Binding of Indole-3-acetic Acid and 3-Methyleneoxindole to Plant Macromolecules.

Homogenates of pea (Pisum sativum L., var. Alaska) seedlings exposed to (14)C-indole-3-acetic acid or (14)C-3-methyleneoxindole, an oxidation product of indole-3-acetic acid, were extracted with phenol. In both cases 90% of the bound radioactivity was found associated with the protein fraction and 10% with the water-soluble, ethanol-insoluble fraction. The binding of radioactivity from (14)C-indole-3-acetic acid is greatly reduced by the addition of unlabeled 3-methyleneoxindole as well as by chlorogenic acid, an inhibitor of the oxidation of indole-3-acetic acid to 3-methyleneoxindole. Chlorogenic acid does not inhibit the binding of (14)C-3-methyleneoxindole. The labeled protein and water-soluble, ethanol-insoluble fractions of the phenol extract were treated with an excess of 2-mercaptoethanol. Independently of whether the seedlings had been exposed to (14)C-indole-3-acetic acid or (14)C-3-methyleneoxindole, the radioactivity was recovered from both fractions in the form of a 2-mercaptoethanol-3-methyleneoxindole adduct. These findings indicate that 3-methyleneoxindole is an intermediate in the binding of indole-3-acetic acid to macromolecules.

Inhibitory oxidation products of indole-3-acetic Acid: 3-hydroxymethyloxindole and 3-methyleneoxindole as plant metabolites.

Extracts of pea seedlings (Pisum sativum, variety Alaska) oxidize indole-3-acetic acid to a bacteriostatic compound which has been identified as 3-hydroxymethyloxindole. At physiological pH this compound is readily dehydrated to 3-methyleneoxindole, another bacteriostatic agent. The extracts of pea seedlings also contain a reduced triphosphopyridine nucleotide-linked enzyme which reduces 3-methyleneoxindole to 3-methyloxindole, a non-toxic compound.These enzymatic reactions also take place in intact seedlings; thus, a pathway of indole-3-acetic acid degradation via oxindoles appears to be pertinent to plant metabolism.The significance of such metabolism lies in the fact that a key intermediate of this pathway, 3-methyleneoxindole, is a sulfhydryl reagent capable of profound effects on metabolism and growth.