Long-term AZT exposure alters the metabolic capacity of cultured human lymphoblastoid cells.

The antiretroviral efficacy of 3'-azido-3'-deoxythymidine (AZT) is dependent upon intracellular mono-, di-, and triphosphorylation and incorporation into DNA in place of thymidine. Thymidine kinase 1 (TK-1) catalyzes the first step of this pathway. MOLT-3, human lymphoblastoid cells, were exposed to AZT continuously for 14 passages (P(1)-P(14)) and cultured for an additional 14 passages (P(15)-P(28)) without AZT.

Intra-articular calcaneal fracture: closed reduction and balloon-assisted augmentation with calcium phosphate cement: a case report.

Introduction: For decades, open reduction and internal fixation was the surgical treatment of choice for intra-articular calcaneal fractures, either with or without any augmentation. Delayed weight bearing and wound-related complications are still unresolved. Aiming at a minimally invasive therapy with accelerated mobilization, we applied closed reduction and balloon-assisted augmentation with calcium phosphate cement.

A deletion within glycoprotein L of Marek's disease virus (MDV) field isolates correlates with a decrease in bivalent MDV vaccine efficacy in contact-exposed chickens.

We examined the functional role of a naturally occurring deletion within the glycoprotein L (gL) gene of Marek's disease virus (MDV) field isolates. We previously showed that this mutation incrementally increased the virulence of an MDV in contact-exposed SPF leghorn chickens, when chickens shedding this virus were co-infected with herpesvirus of turkeys (HVT). In our present study, we examined this mutation using two stocks of the very virulent plus (vv+)MDV strain TK, one of which harbored this deletion (TK1a) while the other did not (TK2a).

Future perspectives for the treatment of pulmonary arterial hypertension.

Over the past 2 decades, pulmonary arterial hypertension has evolved from a uniformly fatal condition to a chronic, manageable disease in many cases, the result of unparalleled development of new therapies and advances in early diagnosis. However, none of the currently available therapies is curative, so the search for new treatment strategies continues. With a deeper understanding of the genetics and the molecular mechanisms of pulmonary vascular disorders, we are now at the threshold of entering a new therapeutic era.

Directed discovery of agents targeting the Met tyrosine kinase domain by virtual screening.

Hepatocyte growth factor (HGF) is an important regulator of normal development and homeostasis, and dysregulated signaling through the HGF receptor, Met, contributes to tumorigenesis, tumor progression, and metastasis in numerous human malignancies. The development of selective small-molecule inhibitors of oncogenic tyrosine kinases (TK) has led to well-tolerated, targeted therapies for a growing number of cancer types. To identify selective Met TK inhibitors, we used a high-throughput virtual screen of the 13.

Coordinating the initial steps of base excision repair. Apurinic/apyrimidinic endonuclease 1 actively stimulates thymine DNA glycosylase by disrupting the product complex.

DNA glycosylases initiate base excision repair by removing damaged or mismatched bases, producing apurinic/apyrimidinic (AP) DNA. For many glycosylases, the AP-DNA remains tightly bound, impeding enzymatic turnover. A prominent example is thymine DNA glycosylase (TDG), which removes T from G.

Bortezomib-induced enzyme-targeted radiation therapy in herpesvirus-associated tumors.

We investigated the possibility of using a pharmacologic agent to modulate viral gene expression to target radiotherapy to tumor tissue. In a mouse xenograft model, we had previously shown targeting of [(125)I]2'-fluoro-2'-deoxy-beta-D-5-iodouracil-arabinofuranoside ([(125)I]FIAU) to tumors engineered to express the Epstein-Barr virus thymidine kinase (EBV-TK). Here we extend those results to targeting of a therapeutic radiopharmaceutical [(131)I]FIAU to slow or stop tumor growth or to achieve tumor regression.

Embryotoxicity of artesunate in animal species related to drug tissue distribution and toxicokinetic profiles.

Background: Injectable artesunate (AS) can cause fetal death and teratogenic effects in animals at levels below the human therapeutic dose. Similar toxicity has also been found for oral artemisinins in various animal species, but has not been found in humans.

Methods: Studies on tissue distribution (5 mg/kg) and toxicokinetics (TK, 30 mg/kg x 3) were conducted in pregnant (GD11-13) and non-pregnant rats.

Rearranging the bicyclo[3.1.0]hexane template of carbocyclic nucleosides to improve binding recognition by kinases.

A novel bicyclo[3.1.0]hexane carbocyclic nucleoside (4) with a south-like conformation amenable to interact with the herpes thymidine kinase (HSV-tk) was synthesized with an endo-hydroxyl group positioned at the tip of the bicyclo[3.

Relationship of EGFR mutations, expression, amplification, and polymorphisms to epidermal growth factor receptor inhibitors in the NCI60 cell lines.

Purpose: The mechanism of sensitivity and resistance to epidermal growth factor receptor (EGFR) inhibitors is incompletely understood, particularly in cancers other than non-small-cell lung cancer (NSCLC). To understand the variable response to this class of drugs, we used the NCI60 cancer cell lines. We aimed to determine if there are interactions between EGFR expression, mutations, polymorphisms, and gene amplification, and whether these factors are associated with variability in response to EGFR inhibitors.

Imaging of musculoskeletal bacterial infections by [124I]FIAU-PET/CT.

Background: Traditional imaging techniques for the localization and monitoring of bacterial infections, although reasonably sensitive, suffer from a lack of specificity. This is particularly true for musculoskeletal infections. Bacteria possess a thymidine kinase (TK) whose substrate specificity is distinct from that of the major human TK.

Adenoviral gene transfer in bovine adrenomedullary and murine pheochromocytoma cells: potential clinical and therapeutic relevance.

Recombinant adenoviruses (rAd) have been widely used as gene transfer vectors both in the laboratory and in human clinical trials. In the present study, we investigated the effects of adenoviral-mediated gene transfer in primary bovine adrenal chromaffin cells (BACC) and a murine pheochromocytoma cell line (MPC). Cells were infected with one of three nonreplicating E1/E3-deleted (E1(-)/E3(-)) rAd vectors: Ad.

Virus-associated tumor imaging by induction of viral gene expression.

Purpose: EBV and other herpesviruses are associated with a variety of malignancies. The EBV thymidine kinase (TK) is either not expressed or is expressed at very low levels in EBV-associated tumors. However, EBV-TK expression can be induced in vitro with several chemotherapeutic agents that promote viral lytic induction.

Noninvasive molecular imaging to detect transgene expression of lentiviral vector in nonhuman primates.

Unlabelled: Noninvasive imaging of a reporter gene is a new and promising technique to quantify transgene expression after gene therapy. This study was performed to demonstrate visualization of lentiviral-marked cells by PET.

Methods: We transduced nonhuman primate CD34+ hematopoietic cells with a lentiviral vector expressing a PET reporter gene, the mutant viral herpes simplex virus type 1-thymidine kinase (HSV1-sr39tk) gene.

Targeting the c-Met signaling pathway in cancer.

On binding to the cell surface receptor tyrosine kinase (TK) known as c-Met, hepatocyte growth factor (HGF) stimulates mitogenesis, motogenesis, and morphogenesis in a wide range of cellular targets including, epithelial and endothelial cells, hematopoietic cells, neurons, melanocytes, and hepatocytes. These pleiotropic actions are fundamentally important during development, homeostasis, and tissue regeneration. HGF signaling also contributes to oncogenesis and tumor progression in several human cancers and promotes aggressive cellular invasiveness that is strongly linked to tumor metastasis.

A compilation of two decades of mutagenicity test results with the Ames Salmonella typhimurium and L5178Y mouse lymphoma cell mutation assays.

As previously reported [Cameron, T. P., Rogers-Back, A.

Mechanisms of genotoxicity of nucleoside reverse transcriptase inhibitors.

Nucleoside analogs were first approved by the U.S. Food and Drug Administration for use against HIV-AIDS in 1987.

Evaluation of (76)Br-FBAU as a PET reporter probe for HSV1-tk gene expression imaging using mouse models of human glioma.

Unlabelled: The utility of 5-(76)Br-bromo-2'-fluoro-2'-deoxyuridine ((76)Br-FBAU), a uracil analog, as a PET reporter probe for use with the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene system for gene expression imaging was evaluated in vivo and in vitro using human and rat glioma cells.

Methods: Human glioma cell lines U87 and U251 were transduced with replication-defective adenovirus constitutively expressing HSV1-tk (Ad.TK) or a control expressing green fluorescent protein (Ad.

Understanding how the herpes thymidine kinase orchestrates optimal sugar and nucleobase conformations to accommodate its substrate at the active site: a chemical approach.

The herpes virus thymidine kinase (HSV-tk) is a critical enzyme for the activation of anti-HSV nucleosides. However, a successful therapeutic outcome depends not only on the activity of this enzyme but also on the ability of the compound(s) to interact effectively with cellular kinases and with the target viral or cellular DNA polymerases. Herein, we describe the synthesis and study of two nucleoside analogues built on a conformationally locked bicyclo[3.

Asymmetric fluid criticality. I. Scaling with pressure mixing.

The thermodynamic behavior of a fluid near a vapor-liquid and, hence, asymmetric critical point is discussed within a general "complete" scaling theory incorporating pressure mixing in the nonlinear scaling fields as well as corrections to scaling. This theory allows for a Yang-Yang anomaly in which mu(")(sigma)(T), the second temperature derivative of the chemical potential along the phase boundary, diverges like the specific heat when T-->T(c); it also generates a leading singular term, /t/(2beta), in the coexistence curve diameter, where t[triple bond](T-T(c))/T(c). The behavior of various special loci, such as the critical isochore, the critical isotherm, the k-inflection loci, on which chi((k))[triple bond]chi(rho,T)/rho(k) (with chi=rho(2)k(B)TK(T)) and C((k))(V)[triple bond]C(V)(rho,T)/rho(k) are maximal at fixed T, is carefully elucidated.

Toxicokinetics and hydrolysis of artelinate and artesunate in malaria-infected rats.

Comparative toxicokinetic (TK) and hydrolysis studies of intravenously administered two new antimalarial agents, artelinate (AL) and artesunate (AS), were performed in malaria-infected rats using three daily equimolar doses (96 micromoles/kg). The TK evaluation was related to select one drug for severe malaria treatment in U.S.

Synthesis and biological evaluation of 5-substituted derivatives of the potent antiherpes agent (north)-methanocarbathymine.

The conformationally locked nucleoside, (north)-methanocarbathymine (1a), is a potent and selective anti-herpes agent effective against herpes simplex type 1 (HSV1) and type 2 (HSV2) viruses. Hereby, we report on the synthesis and biological evaluation of a small set of 5-substituted pyrimidine nucleosides belonging to the same class of bicyclo[3.1.

Actinomycin D induces high-level resistance to thymidine analogs in replication of human immunodeficiency virus type 1 by interfering with host cell thymidine kinase expression.

Actinomycin D (ActD) is a transcription inhibitor and has been used in the treatment of certain forms of cancer. ActD has been reported to be a potential inhibitor of human immunodeficiency virus type 1 (HIV-1) replication due to its ability to inhibit reverse transcription. In contrast to what was expected, low concentrations of ActD (1 to 10 nM) upregulated HIV-1 replication 8- to 10-fold in MT-2 cells and had no effect on HIV-2 replication or on HIV-1 replication in MT-4, Jurkat, or peripheral blood mononuclear cells.

Quantification of brain lesions using interactive automated software.

We developed an interactive program, Analysis of Brain Lesions (ABLe) so that researchers studying the effects of brain lesions on cognition could have a user-friendly tool that could quantitatively characterize such lesions. The program was prepared in Tcl/Tk and will run on any UNIX or PC LINUX platform with the MEDx medical imaging software package. The ABLe is almost completely automated and determines the brain lesion size as well as which cytoarchitectonic brain regions (Brodmann areas) are contained within the boundaries of the lesion.

Systemic cancer therapy with a tumor-selective vaccinia virus mutant lacking thymidine kinase and vaccinia growth factor genes.

We have demonstrated previously the oncolytic effects of a systemically delivered, replicating vaccinia virus. To enhance the tumor specificity of this vector, we have developed a combined thymidine kinase-deleted (TK-) and vaccinia growth factor-deleted (VGF-) vaccinia virus and investigated its properties in vitro and in vivo. The gene for enhanced green fluorescent protein (EGFP) was inserted into the TK locus of a VGF- vaccinia virus by homologous recombination creating a double-deleted mutant vaccinia virus (vvDD-GFP).