The repair of psoralen interstrand cross-links in the yeast Saccharomyces cerevisiae involves the DNA repair groups nucleotide excision repair (NER), homologous recombination (HR), and post-replication repair (PRR). In repair-proficient yeast cells cross-links induce double-strand breaks, in an NER-dependent process; the double-strand breaks are then repaired by HR. An alternate error-prone rep...

Potorous tridactylis (PTK2) cells growing in culture were treated with psoralen derivatives and dividing cells were located by phase-contrast microscopy. Psoralens, light-sensitive DNA-photoadducting drugs, were reacted with mitotic chromosomes through exposure to 365-nm light from an argon laser microbeam system. It was found that following mitosis and photoreaction, cells without nuclear enve...

The light-activated, nucleic acid-binding drugs, psoralens, were used in conjunction with a 365-nm laser microbeam to selectively bind to any nucleic acids in the centriolar region. 4'-aminomethyl-4,5',8--trimethyl-psoralen (AMT) has a high affinity for both RNA and DNA and can be shown to cause mitotic abortion when centriolar regions of prophase PTK2 cells and reacted with AMT and 365-nm lase...

AIM Evaluation of narrow band ultraviolet B (NB UVB 311 nm) in the treatment of vitiligo by two independent studies. The first study compared NB UVB with a well-established therapeutic modality, psoralen ultraviolet A (PUVA), and the second study was conducted to find out whether psoralen might add to its efficacy. METHODS In the first study, 15 patients were exposed on the left half of their...

We have developed a new biochemical method to isolate a homogeneous population of RNA polymerase II (RNA pol II) elongation complexes arrested at a DNA damage site. The method involves triple-helix formation at a predetermined site in DNA template with a third strand labeled with psoralen at its 5'-end and a biotin at the 3'-end. After triplex formation and near-ultraviolet irradiation (360 nm)...

Triple helix forming oligonucleotides can direct DNA damaging agents at specific sites in an intact double helix. In our study, triple helix formation was demonstrated in a SV40 based shuttle vector treated with psoralen linked to a 22-mer purine rich oligonucleotide. UVA irradiation caused a covalent linkage of the oligonucleotide through the psoralen to the mutational supF marker gene of the ...

Psoralea corylifolia L. (Fabaceae) is a widely used medical plant in China. This study was designed to screen and identify bioactive compounds with anticancer activity from the seeds of Psoralea corylifolia L. One volatile fraction (fraction I) and three other fractions (fraction II, III, IV) from methanol extraction of P. corylifolia L. were obtained. Bioactivities of these fractions were eval...

Interstrand crosslink (ICL)-inducing agents block the separation of the two DNA strands. They prevent transcription and replication and are used in clinics for the treatment of cancer and skin diseases. Here, we have introduced a single psoralen ICL at a specific site in plasmid DNA using a triplex-forming-oligonucleotide (TFO)-psoralen conjugate and studied its repair in Xenopus egg extracts t...

High level quantum mechanical methods were used to study the intercalation complexes of psoralen and 8-methoxy psoralen with DNA. The energetics, structures and properties of isolated psoralen and 8-methoxy psoralen have been investigated. Their interactions with DNA bases and base pair were studied aiming to understand more about the nature of the intercalation binding forces between these int...

The effect of arachidonic acid (AA) combined with UVA irradiation was studied in a model system mimicking phototherapy PUVA (psoralen+UVA) ex vivo in vitro. The contribution of damage to the plasma membrane by PUVA was tested on human lymphocytes derived from healthy donors. The effect of arachidonic acid (AA) combined with UVA irradiation was compared with that of a psoralen photoadduct to AA ...