A B S T R A C T We have previously described a 14-yrold boy with hyperuricemia, renal failure, and accelerated purine production resistant in vivo and in vitro to purine analogs. This patient demonstrated normal red cell hypoxanthine-guanine phosphoribosyltransferase (HPRT) heat stability, electrophoresis at high pH, and activity at standard substrate levels. In the present report an abnormal H...

Unlike the development of drugs based on small chemical entities there are no conventional regulatory toxicity studies established for DNA-based products. As the potential for insertional mutagenesis is of particular concern for gene therapy, we have investigated the mutagenicity of model non-viral DNA-based products at the HPRT locus in Chinese hamster V79 cells. Cultures were transfected with...

A purine nucleotide (inosinate) cycle is demonstrated with human lymphoblasts. The lymphoblast requires approximately 50 nmol of purine/10(6) cell increment. When the inosinate cycle is interrupted by the genetic, severe deficiency of either or both purine nucleoside phosphorylase (PNP) or hypoxanthine phosphoribosyltransferase (HPRT), purine accumulates in the culture medium as inosine, guanos...

To study the in vivo expression of the murine Tie2 gene, we have targeted the hypoxanthine phosphoribosyltransferase (Hprt) gene locus to generate two single-copy transgenic mice: T1, containing the 2,100-bp Tie2 promoter upstream from the beta-galactosidase (LacZ) gene, and T5, which also included an enhancing element originating from the first intron of the Tie2 gene. Comparing T1 and T5 embr...

Excess of uric acid is mainly treated with xanthine oxidase (XO) inhibitors, also called uricostatics because they block the conversion of hypoxanthine and xanthine into urate. Normally, accumulation of upstream metabolites is prevented by the hypoxanthine-guanine phosphoribosyltransferase (HPRT) enzyme. The recycling pathway, however, is impaired in the presence of HPRT deficiency, as observed...

Development of experimental models by genetic manipulation in mice has proven to be very useful in determining the significance of particular genes in the development of or susceptibility to hypertension. Advances in molecular genetics, transgenic mouse technology, and physiological measurements in mice provided an opportunity to go a step further and develop models to analyze the physiological...

Human artificial chromosome (HAC) vectors are an important gene transfer system for expression and complementation studies. We describe a significant advance in HAC technology using infectious herpes simplex virus type 1 (HSV-1) amplicon vectors for delivery. This highly efficient method has allowed gene-expressing HACs to be established in glioma-, kidney- and lung-derived cells. We also devel...

Genetic events leading to the loss of heterozygosity (LOH) have been shown to play a crucial role in the development of cancer. However, LOH events do not occur only in genetically unstable cancer cells but also have been detected in normal somatic cells of mouse and man. Mice, in which one of the alleles for adenine phosphoribosyltransferase (Aprt) has been disrupted by gene targeting, were us...

Interleukin (IL)-1beta is a pleiotropic cytokine implicated in a variety of activities, including damage of insulin-producing cells, brain injury, or neuromodulatory responses. Many of these effects are mediated by nitric oxide (NO) produced by the induction of NO synthase (iNOS) expression. We report here that IL-1beta provokes a marked repression of genes, such as fragile X mental retardation...