A PREVIOUSLY UNKNOWN UNIQUE CHALLENGE FOR INHIBITORS OF SYK ATP-BINDING SITE: ROLE OF SYK AS A CELL CYCLE CHECKPOINT REGULATOR.

The identification of SYK as a molecular target in B-lineage leukemia/lymphoma cells prompted the development of SYK inhibitors as a new class of anti-cancer drug candidates. Here we report that induction of the SYK gene expression in human cells causes a significant down-regulation of evolutionarily conserved genes associated with mitosis and cell cycle progression providing unprecedented evidence that SYK is a master regulator of cell cycle regulatory checkpoint genes in human cells. We further show that SYK regulates the G checkpoint by physically associating with and inhibiting the dual-specificity phosphatase CDC25C via phosporylation of its S216 residue.

KU HAPLOINSUFFIENCY CAUSES A LYMPHOPROLIFERATIVE DISORDER OF IMMATURE T-CELL PRECURSORS DUE TO IKAROS MALFUNCTION.

Ikaros (IK) malfunction has been implicated in the pathogenesis of acute lymphoblastic leukemia (ALL), the most common form of childhood cancer. Therefore, a stringent regulation of IK activity is very important. Here we provide unique genetic and biochemical evidence that the Ku protein components Ku70 and Ku80 act as positive regulators of IK function via formation of IK-Ku70 and IK-Ku80 heterodimers with augmented sequence-specific DNA binding activity.

Therapeutic nanoparticle constructs of a JAK3 tyrosine kinase inhibitor against human B-lineage ALL cells.

WHI-P131 (CAS 202475-60-3) is a dual-function inhibitor of JAK3 tyrosine kinase that demonstrated potent in vivo anti-inflammatory and anti-leukemic activity in several preclinical animal models. This is the first report of the development of nanoparticle (NP) constructs ofWHI-P131. Fourty-eight distinct NP formulations were prepared and WHI-P131 encapsulation efficiencies > 95% and intraliposomal WHI-P131 concentrations >10 mg/mL were achieved in lead NP formulations.

Gene expression profiles of infant acute lymphoblastic leukaemia and its prognostically distinct subsets.

This study compared the gene expression profiles of primary leukaemic cells from infants versus children with acute lymphoblastic leukaemia (ALL). Our analyses provided unprecedented evidence that remarkably different pathognomonic transcriptomes dominate the biology of infant versus paediatric high risk ALL. The genetic signature of infant ALL is characterized by concomitant overexpression of mitogenic and anti-apoptotic genes, some of which have been associated with early relapse in ALL.

Targeting JAK3 tyrosine kinase-linked signal transduction pathways with rationally-designed inhibitors.

Inhibitors of Janus Kinase 3 (JAK3) show potential as a new class of apoptosis-inducing anti-cancer drugs. In addition, JAK3 inhibitors may also be useful as immunosuppressive agents. Rationally designed selective inhibitors of JAK3 such as JANEX-1, that do not inhibit other Janus kinases have recently undergone extensive preclinical testing that revealed a favorable pharmacodynamic profile.

Mechanism of psychoactive drug action in the brain: simulation modeling of GABAA receptor interactions at non-equilibrium conditions.

Synaptic transmission requires that the binding of the transmitter to the receptor to occur under rapidly changing transmitter levels, and this binding interaction is unlikely to be at equilibrium. We have sought to numerically solve for binding kinetics using ordinary differential equations and simultaneous difference equations for use in stochastic conditions. The reaction scheme of GABA interacting with the ligand-gated ion-channel demonstrates numerical stiffness.

Limitations of the human-PBL-SCID mouse model for vaginal transmission of HIV-1.

Problem: SCID mice reconstituted with human peripheral blood lymphocytes (PBL) are amenable to vaginal transmission of HIV-1. We investigated the effectiveness of this model to establish systemic HIV-1 infection.

Method Of Study: Eighty progesterone-primed C.

Anti-retroviral activity of GMP-grade stampidine against genotypically and phenotypically nucleoside reverse transcriptase inhibitor resistant recombinant human immunodeficiency virus. An in vitro study.

The in vitro potency of GMP-grade stampidine (CAS 217178-62-6) was examined against 3 clinical HIV-1 isolates and 6 recombinant HIV-1 clones with multi-NRTI 'resistance (NRTI: nucleoside reverse transcriptase inhibitors). GMP-grade stampidine active drug substance (Lot #'s MPR-M0008.00-01 and MPR-M0008.

Novel tight binding PETT, HEPT and DABO-based non-nucleoside inhibitors of HIV-1 reverse transcriptase.

Non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are a key component of effective combination antiretroviral therapies for HIV/AIDS. NNRTIs despite their chemical diversity, bind to a common allosteric site of HIV-1 RT, the primary target for anti-AIDS chemotherapy, and noncompetitively inhibit DNA polymerization. NNRTIs currently in clinical use have a low genetic barrier to resistance and therefore, the need for novel NNRTIs active against drug-resistant mutants selected by current therapies is of paramount importance.

Influence of long-term stability conditions on microbicidal nucleoside prodrug (WHI-07)-loaded gel-microemulsion.

The objective of this study was to evaluate the long-term stability of the antiretroviral spermicide WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate) in a polymer-based microemulsion. The recovery and stability of WHI-07 in gel-microemulsion was examined by a validated high-performance liquid chromatography (HPLC) method. The stability was examined over a period of 24 weeks at 3 controlled temperatures (4 degrees C, 25 degrees C, and 40 degrees C).

Clinical activity of folinic acid in patients with chronic fatigue syndrome.

A high incidence of severe B-cell immunodeficiency and chronic reactivated Epstein-Barr virus (EBV) infection in patients with chronic fatigue syndrome (CFS) is reported herein. Of the 58 patients evaluated, 100% had evidence of prior EBV exposure and 72% had evidence for reactivated EBV infection. Notably, 94% of CFS patients had B-cell immunodeficiency with a marked depletion of their CD19+IgM+ mature B-lymphocyte population.

Novel broad-spectrum thiourea non-nucleoside inhibitors for the prevention of mucosal HIV transmission.

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTI) are an integral part of combination therapy comprising three classes of antiretroviral drugs for the management of HIV/AIDS. NNRTIs are chemically diverse compounds that bind to a common allosteric site of HIV-1 RT and noncompetitively inhibit DNA polymerization. Resistance to NNRTIs arises rapidly upon drug treatment and results from mutation of the amino acids lining the HIV-1 RT binding pocket.

Effect of alkyl groups on the cellular hydrolysis of stavudine phosphoramidates.

We examined the effect of cellular metabolism of three alkyl-substituted amino acid ester phosphoramidate derivatives of stavudine in different cell lines. Marked cell-to-cell differences were found in both the rate of hydrolysis and chiral selectivity. This selectivity implies that different enzymes may be involved in the metabolism of these compounds depending on the cell type involved.

Synthesis and metabolism of naphthyl substituted phosphoramidate derivatives of stavudine.

The synthesis of naphthylphosphoramidate derivatives of stavudine was achieved using a four-step procedure. The derivatives were subjected to several different enzymes including lipase, esterase, Subtilisin Carlsberg, and Carica papaya, and their hydrolysis rates were determined. Based on the rates of hydrolysis, we were able to differentiate between the chiralities at the phosphorus center of the phosphoramidate compounds.

Potency of stampidine against multi-nucleoside reverse transcriptase inhibitor resistant human immunodeficiency viruses.

The in vitro potency of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) was examined against 8 clinical non-B subtype HIV-1 isolates with resistance to stavudine (STV, d4T), adefovir and tenofovir, 19 clinical zidovudine-resistant HIV-1 isolates, and 6 recombinant HIV-1 clones with multi-resistance against nucleoside reverse transcriptase inhibitors. Stampidine exhibited potent anti-HIV activity against each one of these 33 HIV-1 isolates with subnanomolar to nanomolar IC50 values.

In vivo pharmacokinetics and toxicity profile of the anti-HIV agent stampidine in dogs and feline immunodeficiency virus-infected cats.

The pharmacokinetics and toxicity profile of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were studied in beagle dogs and feline immunodeficiency virus-infected domestic cats. Therapeutic plasma concentrations of STAMP 3-4 logs higher than its IC50 value can be achieved after its p.o.

Site-specific enzymatic activation of the anti-HIV agent stampidine.

Stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) and two stampidine analogs containing ethyl or t-butyl groups were synthesized and their rates of enzymatic activation were compared side-by-side. Enzymes such as lipase, esterase and protease did not hydrolyze the butyl substituted STAMP analog. These experimental results show that the site of attack for the enzymatic hydrolysis of STAMP is the ester side chain of the molecule.

Developmental safety profile of the anti-HIV agent stampidine in rabbits.

Stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) is a novel aryl phosphate derivative of stavudine (STV, d4T, 2',3'-didehydro-3'-deoxythymidine, CAS 3056-17-5) with potent anti-HIV activity. The reproductive and developmental safety profile of STAMP was evaluated in mated New Zealand white rabbits. STAMP did not adversely affect the reproductive health of female rabbits and it lacked teratogenicity or other developmental toxicity in their progeny.

Synthesis, separation and anti-HIV activity of distereoisomers of N-[p-(4-bromophenyl) -2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester (stampidine).

The distereoisomers of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2'3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were separated using two different procedures. The first method involved separation of the isomers by fractional crystallization, and the second method utilized a preparative HPLC. Both isomers were active against the HIV-1 strain HTLV(IIIB) and neither isomer was more or less active than distereoisomeric mixture of stampidine.

Large-scale synthesis and formulation of GMP-grade stampidine, a new anti-HIV agent.

The arylphosphoramidate derivative of stavudine (STV, d4T, 2,3'-didehydro-3'-deoxythymidine, CAS 3056-17-5), stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6), is a novel anti-HIV agent. STAMP was prepared under current Good Manufacturing Practice (cGMP) conditions on the scale of kilograms. Solid STAMP was subsequently formulated as a capsule under GMP conditions for oral administration.

Stampidine as a novel nucleoside reverse transcriptase inhibit with potent anti-HIV activity.

Stavudine (STV, d4T, 2',3'-didehydro-3'-deoxythymidine, CAS 3056-17-5) is a standard anti-HIV drug. Stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) is a novel aryl phosphate derivative of stavudine with more potent anti-HIV activity and more favorable pharmacodynamic features. The remarkable potency of stampidine against clinical HIV-1 isolates with NRTI- or NNRTI-resistance (NRTI, nucleoside reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase inhibitor) warrants the further development of this new anti-HIV agent.

Targeting JAK3 and BTK tyrosine kinases with rationally-designed inhibitors.

Multifunctional rational drug design of protein tyrosine kinases inhibitors allows a potent drug to be utilized to treat more than one disease for greater patient benefits. Many protein tyrosine kinases (PTK), including Janus kinase 3 (JAK3) and Bruton's tyrosine kinase (BTK), have been identified as potential drug targets to treat diverse diseases including cancer and disorders of the immune system. Here we review advances in JAK3 and BTK inhibitors and describe the therapeutic potential of these potent agents in the clinical setting.

Dawn of non-nucleoside inhibitor-based anti-HIV microbicides.

The emergence of HIV/AIDS as a disease spread through sexual intercourse has prompted the search for safe and effective vaginal and rectal microbicides for curbing mucosal viral transmission via semen. Since endogenous reverse transcription is implicated in augmenting the sexual transmission of HIV-1 infection, potential microbicides should have the inherent ability to optimally inhibit both wild-type and drug-escape mutants. The non-nucleoside reverse transcriptase inhibitors (NNRTIs), which bind to an allosteric site on RT, are an important arsenal of drugs against HIV-1.