遗传学实验技术

Vertebrate chromosomes end in a variable number of T2AG3 repeats (1), which, jointly with associated proteins, are essential for chromosomal stability (for reviews, see refs. (2–4). Telomeres have important roles in essential cellular processes like replication, malignant transf ...

The most desirable properties of any therapeutic agent must be selectivity and potency (1). Of the two, potency is less critical, though in terms of potential administration it is important to recognize that patients should not be expected to take grams of material nor can the costs of producing lar ...

Modern biology provides a plethora of experimental evidence that points to the chaotic and heterogenous nature of cancer, making it necessary to tackle each type of cancer as a unique problem in terms of treatment. The existence of a labyrinth of multiple backup networks for every biological ev ...

The ability of tumor cells to grow indefinitely contrasts sharply with the growth of normal cells. When normal human cells are grown in vitro, they undergo a limited number of divisions. This property, termed replicative senescence, is lost when cells become tumorigenic. However, whole-cell ...

The activation of telomerase, proposed as a critical set for cell immortalization to overcome cellular senescence, was believed to be associated with the malignant progression of human tumours (1-4). Therefore human telomerase appears to be an attractive new target for designing anti- ...

In 1994, a highly sensitive assay to detect telomerase activity, called a telomeric repeat amplification protocol (TRAP) assay, was reported by Kim et al. (1) with the precise method described in 1995 by Piatyszeck et al (2). Many modifications of the original TRAP assay were made later. One example is ...

Numerous studies on telomerase expression have consistently demonstrated the presence of telomerase activity in the vast majority of different types of cancer, as well as immortalized cells, but have failed to detect telomerase in most normal tissues (1). Examples include breast canc ...

Telomerase is now a significant factor in the fight against cancer and antiaging (1). It is becoming a valuable prognostic tool to determine if a particular tissue is likely to develop cancer (2). The ability to detect telomerase activity in patients with cancer has also been correlated with clini ...

In 1985, telomerase activity was identified in the macronuclei of the ciliate Tetrahymena and was found to add telomeric repeats onto telomeric oligonucleotide primers (1). The radiolabeled elongated products were detected easily as a 6-bp ladder on an electrophoresis gel. In 1989, using ...

The polymerase chain reaction (PCR) based telomeric repeat amplification protocol (TRAP) assay, to detect telomerase activity was originated by Kim et al. in late 1994 (1) and revolutionized the field of telomere/telomerase research in aging, but particularly in cancer. Thus, the TRAP as ...

Telomeres are specialized DNA/protein structures, located at the ends of eukaryotic chromosomes, that consist of small, tandemly repeated DNA sequences. They have an essential role in the stable maintenance of the eukaryotic chromosome by preventing nucleolytic degradation, en ...

The polymerase chain reaction (PCR) is a very powerful technique for the in vitro amplification of nucleic acid sequences (1) PCR relies on the principle that oligonucleotide sequences hybridize to a template DNA specifically, given the appropriate conditions. Conditions such as ionic ...

The regulation of telomerase activity is likely to be a complex issue, involving the transcriptional activity of the telomerase RNA component gene, (hTR) and the telomerase catalytic component gene (hTRT), as well as the interaction of telomerase with other telomere-associated prote ...

Cytochrome P450 (CYP) is comprosed of a family of hemeprotein monooxygenases that catalyze reactions as diverse as the biosynthesis of steroid hormones, metabolism of fat-soluble vitamins, oxidation of unsaturated fatty acids, and metabolism of drugs, pollutants, and other xenob ...

This chapter describes an approach to destroying malignant cells by effectively changing the tumor phenotype through the delivery of Escherichia coli purine nucleo-side phosphorylase (PNP). In the presence of nucleoside prodrugs, this nonhuman enzyme in purine metabolism caus ...

The development of enzyme-prodrug approaches for targeted treatment of human tumors has gained momentum in the last decade, especially with the advent of antibodies, viral vectors, and nonviral delivery systems that might be suitable for use in vivo. However, relatively few novel enzyme ...

Thymidine phosphorylase (E.C. 2.4.2.4) (TP), also described as the angiogenic platelet-derived endothelial cell growth factor (PD-ECGF) (1–4), is a homodimeric enzyme with a monomeric molecular mass of about 55 kDa (5,6) that phosphorolytically cleaves thymidine to yield thymine and de ...

With recent progress in determining the crystal structures of type I and type II topoisomerases (topo I and topo II, respectively) (1,2), an understanding of the binding of DNA-cleavage-inducing inhibitors at the atomic level is within reach. A very useful approach for investigating the natu ...

DNA topoisomerase I and II catalyze topological changes of DNA by transient breakage of the nucleic acid backbone. Topoisomerase I transiently cleaves one DNA strand and allows the passage of single-stranded DNA through the generated nick, whereas topoisomerase II introduces a trans ...

Topoisomerase enzymes catalyze changes in DNA topology by a concerted breakage and reunion of the DNA phosphodiester backbone (1,2). This process occurs via sequential transesterification reactions involving a tyrosyl hydroxyl group present in the active site of the enzyme. A novel a ...