Pronounced hypoxia in models of murine and human leukemia: high efficacy of hypoxia-activated prodrug PR-104

Recent studies indicate that interactions between leukemia cells and the bone marrow (BM) microenvironment promote leukemia cell survival and confer resistance to anti-leukemic drugs. There is evidence that BM microenvironment contains hypoxic areas that confer survival advantage to hematopoietic cells. In the present study we investigated whether hypoxia in leukemic BM contributes to the protective role of the BM microenvironment. We observed a marked expansion of hypoxic BM areas in immunodeficient mice engrafted with acute lymphoblastic leukemia (ALL) cells. Consistent with this finding, we found that hypoxia promotes chemoresistance in various ALL derived cell lines. These findings suggest to employ hypoxia-activated prodrugs to eliminate leukemia cells within hypoxic niches. Using several xenograft models, we demonstrated that administration of the hypoxia-activated dinitrobenzamide mustard, PR-104 prolonged survival and decreased leukemia burden of immune-deficient mice injected with primary acute lymphoblastic leukemia cells. Together, these findings strongly suggest that targeting hypoxia in leukemic BM is feasible and may significantly improve leukemia therapy.     

Synthesis and antitubercular activity of 2-hydroxy-aminoalkyl derivatives of diaryloxy methano phenanthrenes

A series of 2-hydroxy-aminoalkyl derivatives of diaryloxy methano phenanthrenes were synthesized from nucleophilic opening of oxirane with different amines. These compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis H(37)R(v) in vitro and showed MIC in the range of 3.12-25microg/ml.     

Comparison of the anti-influenza virus activity of cyclopentane derivatives with oseltamivir and zanamivir in vivo

Cyclopentane derivatives, designated as BCX-1812, BCX-1827, BCX-1898, and BCX-1923, were tested in parallel with oseltamivir carboxylate and zanamivir for the in vivo activity in mice infected with A/Turkey/Mas/76 X A/Beijing/32/92 (H6N2) influenza virus. The compounds were tested orally and intranasally at different dose levels. BCX-1812, BCX-1827, and BCX-1923 showed more than 50% protection at 1mg/kg/day dose level on oral treatment. The intranasal treatment was 100% effective even at 0.01 mg/kg/day for all four compounds. On comparison with oseltamivir carboxylate and zanamivir, these four cyclopentane derivatives have shown equal or better efficacies. The synthesis of two new compounds, BCX-1898 and BCX-1923, is also described.     

Identification of allergens in Indian fishes: hilsa and pomfret exemplified by ELISA and immunoblotting

Enzymed-linked immunosorbent assay of hilsa and pomfret muscle extracts showed specific IgE binding to ten allergic patients' sera, the results corroborated to that of skin prick test. Comparison of allergen profiles of the two fish extracts by immunoblotting revealed a common antigenic protein of 50 kDa and some high molecular weight fish allergens instead of low molecular weight parvalbumin found in several fishes. Purified and well characterized fish allergens are always considered better than crude fish extracts for diagnostic use.     

Synthesis of 9-[1-(substituted)-2-(phosphonomethoxy)ethyl]adenine derivatives as possible antiviral agents

Various C-1'-substituted acyclic N9 adenine nucleosides were prepared from 9-[(1-hydroxymethyl)(3-monomethoxytrityloxy)propyl]-N6-monomethoxytrityladenine. The hydroxymethyl was modified to the phosphonomethoxy derivative, and the 3-monomethoxytrityloxy was converted to hydroxyl, methoxy, azido, and amino. Other substituents, such as ethyl and ea-hydroxyethyl were also prepared. The resulting phosphonomethoxy derivatives were converted to prodrugs.     

K4, K9 and K18 in human histone H3 are targets for biotinylation by biotinidase

Histones are modified post-translationally, e.g. by methylation of lysine and arginine residues, and by phosphorylation of serine residues. These modifications regulate processes such as gene expression, DNA repair, and mitosis and meiosis. Recently, evidence has been provided that histones are also modified by covalent binding of the vitamin biotin. The aims of this study were to identify biotinylation sites in histone H3, and to investigate the crosstalk among histone biotinylation, methylation and phosphorylation. Synthetic peptides based on the sequence of human histone H3 were used as substrates for enzymatic biotinylation by biotinidase; biotin in peptides was probed using streptavidin peroxidase. These studies provided evidence that K4, K9 and K18 in histone H3 are good targets for biotinylation; K14 and K23 are relatively poor targets. Antibodies were generated to histone H3, biotinylated either at K4, K9 or K18. These antibodies localized to nuclei in human placental cells in immunocytochemistry and immunoblotting experiments, suggesting that lysines in histone H3 are biotinylated in vivo. Dimethylation of R2, R8 and R17 increased biotinylation of K4, K9 and K18, respectively, by biotinidase; phosphorylation of S10 abolished biotinylation of K9. These observations are consistent with crosstalk between biotinylation of histones and other known modifications of histones. We speculate that this crosstalk provides a link to known roles for biotin in gene expression and cell proliferation.