Overproduction of alpha chains provides a proton-insensitive component to the bluefish hemoglobin system.

Expression of alpha and beta chains and their post-translational assembly into alpha(2)beta(2) tetramers is fundamental to the formation and function of most vertebrate hemoglobins. There is a strong evolutionary bias that favors expression of equal amounts of the two types of chains, because cooperativity, pH sensitivity, and anionic control of function occurs only for the alpha(2)beta(2) tetramers. Remarkably, an over-production of alpha chains, as in the pathological condition known as beta thalassemia in humans, is adaptive rather than pathological in the bluefish hemoglobin system.

Responses of normal and sickle cell hemoglobin to S-nitroscysteine: implications for therapeutic applications of NO in treatment of sickle cell disease.

Factors which govern transnitrosation reactions between hemoglobin (Hb) and low molecular weight thiols may define the extent to which S-nitrosated Hb (SNO-Hb) plays a role in NO in the control of blood pressure and other NO-dependent reactions. We show that exposure to S-nitrosylated cysteine (CysNO) produces equivalent levels of SNO-Hb for Hb A(0) and sickle cell Hb (Hb S), although these proteins differ significantly in the electron affinity of their heme groups as measured by their anaerobic redox potentials. Dolphin Hb, a cooperative Hb with a redox potential like that of Hb S, produces less SNO-Hb, indicating that steric considerations outweigh effects of altered electron affinity at the active-site heme groups in control of SNO-Hb formation.

Internal electron transfer between hemes and Cu(II) bound at cysteine beta93 promotes methemoglobin reduction by carbon monoxide.

Previous studies showed that CO/H2O oxidation provides electrons to drive the reduction of oxidized hemoglobin (metHb). We report here that Cu(II) addition accelerates the rate of metHb beta chain reduction by CO by a factor of about 1000. A mechanism whereby electron transfer occurs via an internal pathway coupling CO/H2O oxidation to Fe(III) and Cu(II) reduction is suggested by the observation that the copper-induced rate enhancement is inhibited by blocking Cys-beta93 with N-ethylmaleimide.

Plantar fibromatosis of the heel in children: a report of 14 cases.

Based on a study of 14 patients younger than 16 years, we found that lumps on the plantar aspect of the anteromedial portion of the heel pad can safely be observed. Many remained small and asymptomatic, some disappeared, and two that required repeated excision biopsy did not subsequently recur. The six patients who were subjected to excision biopsy were found to have plantar fibromatosis.

Biomechanical effects of gamma irradiation on fresh frozen allografts in vivo.

The effect of gamma irradiation on the mechanical properties of allograft in a rabbit model was examined. Tibial allografts were tested in torsion to failure to determine maximum torque and maximum stress. Statistically significant degradation in the torsional strength of irradiated tibias vs controls was demonstrated.