Effect of surgical stress on nuclear and mitochondrial DNA from healthy sections of colon and rectum of patients with colorectal cancer

Surgical resection at any location in the body leads to stress response with cellular and subcellular change, leading to tissue damage. The intestine is extremely sensitive to surgical stress with consequent postoperative complications. It has been suggested that the increase of reactive oxygen species as subcellular changes plays an important role in this process. This article focuses on the effect of surgical stress on nuclear and mitochondrial DNA from healthy sections of colon and rectum of patients with colorectal cancer. Mitochondrial DNA copy number, mitochondrial common deletion and nuclear and mitochondrial 8-oxo-2'-deoxyguanosine content were measured. Both the colon and rectal tissue were significantly damaged either at the nuclear or mitochondrial level. In particular, mitochondrial DNA was more damaged in rectum than in colon. The present investigation found an association between surgical stress and nuclear and mitochondrial DNA damage, suggesting that surgery may generate an increase in free radicals, which trigger a cascade of molecular changes, including alterations in DNA.

Adult and fetal galactokinases in human red blood cells

This paper reports the biochemical properties of galactokinase from fetal and adult human red blood cells. The specific activity of galactokinase is three times higher in the fetal red cells than in adult cells, shows a significant difference in the Michaelis constant toward galactose, and is more thermostable. On the other hand, no differences were found in molecular weight, electric charge, temperature and pH dependence between the two enzymes partly purified from fetal and adult erythrocytes. The possibility that these differences could be due to the shorter lifespan of the fetal erythrocytes (which could result in a higher proportion of young cells in the blood samples utilized) was investigated. Fetal and adult red blood cells were separated into fractions of different mean age by ultracentrifugation through density gradients. The kinetic properties and thermostability of galactokinase from fetal erythrocytes do not show any similarity with the same properties of the enzyme from young red blood cells. These results indicate that galactokinase from fetal erythrocytes show some biochemical properties that are typical signs distinguishing a fetal enzyme.

Comparative studies of galactokinase activity on mammal's red blood cells

1. ATP: D-galactose-1-phosphotransferase activity was measured in human, pig, cow, rabbit, mouse and rat red blood cells. Mean values of galactokinase activity was markedly lower in the human and pig erythrocyte as compared to those of the other species. 2. The permeability to galactose of the red cells studied was always higher than galactose phosphorylation. 3. The affinity constants of galactokinase for galactose ranged from 119 to 291 microM and from 178 to 406 microM for ATPMg2-. 4. The thermostability values of the galactokinase of the species studied were similar. The pH-optimum is pH 7.5 for the human, mouse and rabbit enzyme and pH 8.0 for cow, pig and rat galactokinase.