Synthesis and evaluation of pyrido-thieno-pyrimidines as potent and selective Cdc7 kinase inhibitors.

Cdc7 kinase plays a critical role in the regulation of DNA replication in eukaryotic cells and has been proposed as a target for cancer therapy. We have identified a class of Cdc7/Dbf4 inhibitors with a pyrido-thieno-pyrimidine core structure. Synthesis of a focused pyrido-thieno-pyrimidine library yielded potent and selective Cdc7 inhibitors with antiproliferative activity against cancer cells in vitro. Their synthesis and SAR data are presented herein.

Technical nuances of subtemporal approach for the treatment of basilar tip aneurysm.

BACKGROUND: Basilar tip aneurysms are one of the most complex vascular lesions to treat surgically because of their location, depth of the approach, and close proximity of vital neurovascular structures such as the mesencephalon, cranial nerves, perforating arteries to the thalamus. There are different surgical approaches utilized to reach basilar tip aneurysms, namely, pterional, pretemporal, orbitozygomatic, subtemporal, and anterior petrosectomy. Each of them has its advantages and limitations. METHODS: In this paper, we present our personal experience with the use of subtemporal approach. The technique is described in detail including its nuances and potential pitfalls. RESULTS: The subtemporal approach is indicated for basilar tip aneurysms located at the level of the floor of the sella turcica to 1 cm above the dorsum sellae. CONCLUSION: Subtemporal approach offers good surgical corridor for the management of these complex vascular lesions.

Identification of the V genes encoding xenoantibodies in non-immunosuppressed rhesus monkeys.

The major immunological barrier that prevents the use of wild-type pig xenografts as an alternative source of organs for human xenotransplantation is antibody-mediated rejection. In this study, we identify the immunoglobulin variable region heavy (IgV(H)) chain genes encoding xenoantibodies to porcine heart and fetal porcine islet xenografts in non-immunosuppressed rhesus monkeys. We sought to compare the IgV(H) genes encoding xenoantibodies to porcine islets and solid organ xenografts. The immunoglobulin M (IgM) and IgG xenoantibody response was analysed by enzyme-linked immunosorbent assay and cDNA libraries from peripheral blood lymphocytes were prepared and sequenced. The relative frequency of IgV(H) gene usage was established by colony filter hybridization. Induced xenoantibodies were encoded by the IGHV3-11 germline progenitor, the same germline gene that encodes xenoantibodies in humans mounting active xenoantibody responses. The immune response to pig xenografts presented as solid organs or isolated cells is mediated by identical IgV(H) genes in rhesus monkeys. These animals represent a clinically relevant model to identify the immunological basis of pig-to-human xenograft rejection.

Mammalian nuclei become licensed for DNA replication during late telophase.

Mcm 2-7 are essential replication proteins that bind to chromatin in mammalian nuclei during late telophase. Here, we have investigated the relationship between Mcm binding, licensing of chromatin for replication, and specification of the dihydrofolate reductase (DHFR) replication origin. Approximately 20% of total Mcm3 protein was bound to chromatin in Chinese hamster ovary (CHO) cells during telophase, while an additional 25% bound gradually and cumulatively throughout G1-phase. To investigate the functional significance of this binding, nuclei prepared from CHO cells synchronized at various times after metaphase were introduced into Xenopus egg extracts, which were either immunodepleted of Mcm proteins or supplemented with geminin, an inhibitor of the Mcm-loading protein Cdt1. Within 1 hour after metaphase, coincident with completion of nuclear envelope formation, CHO nuclei were fully competent to replicate in both of these licensing-defective extracts. However, sites of initiation of replication in each of these extracts were found to be dispersed throughout the DHFR locus within nuclei isolated between 1 to 5 hours after metaphase, but became focused to the DHFR origin within nuclei isolated after 5 hours post-metaphase. Importantly, introduction of permeabilized post-ODP, but not pre-ODP, CHO nuclei into licensing-deficient Xenopus egg extracts resulted in the preservation of a significant degree of DHFR origin specificity, implying that the previously documented lack of specific origin selection in permeabilized nuclei is at least partially due to the licensing of new initiation sites by proteins in the Xenopus egg extracts. We conclude that the functional association of Mcm proteins with chromatin (i.e. replication licensing) in CHO cells takes place during telophase, several hours prior to the specification of replication origins at the DHFR locus.