Medical and Veterinary Importance of the Moonlighting Functions of Triosephosphate Isomerase.

Triosephosphate isomerase is the fifth enzyme in glycolysis and its canonical function is the reversible isomerization of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Within the last decade multiple other functions, that may not necessarily always involve catalysis, have been described. These include variations in the degree of its expression in many types of cancer and participation in the regulation of the cell cycle. Triosephosphate isomerase may function as an auto-antigen and in the evasion of the immune response, as a factor of virulence of some organisms, and also as an important allergen, mainly in a variety of seafoods. It is an important factor to consider in the cryopreservation of semen and seems to play a major role in some aspects of the development of Alzheimer's disease. It also seems to be responsible for neurodegenerative alterations in a few cases of human triosephosphate isomerase deficiency. Thus, triosephosphate isomerase is an excellent example of a moonlighting protein.

Leukocyte adhesion deficiency II syndrome, a generalized defect in fucose metabolism.

Leukocyte adhesion deficiency II has been described in only 2 patients; herein we report extensive investigation of another patient. The physical stigmata were detected during prenatal ultrasonographic investigation. Sialyl-Lewis X (sLex) was absent from the surface of polymorphonuclear neutrophils, and cell binding to E- and P-selectin was severely impaired, causing an immunodeficiency. The elevation of peripheral neutrophil counts occurred within several days after birth. A severe hypofucosylation of glycoconjugates bearing fucose in different glycosidic links was present in all cell types investigated, demonstrating that leukocyte adhesion deficiency II is not only a disorder of leukocytes but a generalized inherited metabolic disease affecting the metabolism of fucose.

Parenteral galactose therapy in the glucose-intolerant premature infant.

Blood galactose concentrations were measured in 55 neonates consuming at least 80 ml/kg/day of lactose-containing formula. The range of galactose concentration immediately after feeding was 0.8 to 4.2 mg/dl, with a mean of 1.5 +/- 0.2 mg/dl. Galactose concentration fell rapidly after feeding, and normal values for the population fell with a half-life of 45 minutes. Considering galactose as a potential intravenous nutrient, six glucose-intolerant premature infants were given galactose-containing solutions intravenously using a double-blind randomized crossover protocol. Infants were chosen who had sustained hyperglycemia (150 mg/dl) and glucosuria (2+ Clinitest) requiring glucose infusion at a rate below 7 mg/kg/minute for more than 24 hours. Compared to the control glucose period, intravenous alimentation with a solution containing carbohydrate as 50% glucose and 50% galactose resulted in a 65% increase in total carbohydrate infusion rate, normalization of the blood glucose concentration, and decreased glucosuria. Blood galactose concentration averaged 15 mg/dl, and no clinical or biochemical evidence of galactose toxicity was noted.