Some properties of diploid cell strains developed from the tissues of patients with inherited biochemical disorders

Glutamine dependency of human skin fibroblasts: modulation by hexoses

The combined effects of carbohydrates and glutamine were investigated in diploid strains of normal human skin fibroblasts cultured for 21 days under eight different culture conditions: hexose-free medium or medium containing D-glucose, D-galactose, or D-fructose, with or without added glutamine. Cell growth, hexose consumption, lactate production, intracellular glycogen content and extracellular amino acid levels were measured every third to fourth day. In the presence of glutamine, cells reached a higher saturation density in fructose medium than in glucose or galactose medium but per cell consumption of fructose and galactose was much less than that of glucose. Consumption of all three carbohydrates per unit cell growth exhibited three distinct phases: Days 1-3, 3-10, and 10-20, respectively. In the absence of glutamine the rate of cell growth was not altered in glucose or galactose medium, but slowed down considerably in fructose medium. Glutamine deprivation also led to changes in hexose consumption. In hexose-free media the cell growth rate at first was very slow, but rose after 2 or 3 weeks of culture. The levels of extracellular nonessential amino acids varied according to medium and growth phase. One of the most exciting findings was that human fibroblasts are able to maintain a slight excess of glutamine in all media not supplemented with glutamine and, more surprisingly, to synthesize it in a medium containing galactose and glutamine.

Molecular defect in human acatalasia fibroblasts

The human hereditary disease Acatalasia (AC) is characterized by low or no catalase activity in all body tissues. We have studied the molecular basis of AC. In order to assess their antioxidant defense status we measured the enzyme activities, protein levels and m-RNA concentrations of catalase, superoxide dismutase and glutathione peroxidase in fibroblasts from a Japanese (AC65) and a Swiss (AC64) patient and several normal individuals. Our results point to genetic heterogeneity. While strain AC64 contained normal levels of catalase mRNA and -protein, strain AC65 was completely devoid of both. A structural mutation in the catalase gene is probably responsible for the inactivation of the enzyme in AC64. Since AC65 contains at least a major portion of the catalase gene it may represent a regulatory mutation in which the gene is not transcribed.

Studies on the regulation of the three enzymes of the Leloir pathway in cultured mammalian cells. I. Effect of substitution of galactose for glucose as the sole hexose in the medium in human diploid cell strains and in a rat hepatoma line

In human diploid cell strains, the substitution of galactose for glucose as the sole hexose in the medium had no measurable effect on the specific activity of the cell protein for any of the three enzymes of the Leloir pathway. These enzymes are galactokinase, alpha-D-galactose-1-phosphate: UDP glucose uridyl transferase and UDP galactose 4-epimerase. A cell strain from a patient with galactosemia had no detectable activity for the transferase. The substitution of galactose for glucose in the medium of these cells (which has been shown to cause the cells to accumulate galactose-1-phosphate) also failed to affect cellular activity for the three enzymes. Similarly, the three activities failed to respond to the substitution of galactose for glucose in cultures of a rat hepatoma line. Cells of this line have been shown by others to perform a number of the tissue-specific functions of liver. The failure of galactose to stimulate increasd cellular activity for the three enzymes represents a striking difference between the behavior of these enzymes in human diploid cell strains and their behavior in E. coli.