Temperature variations in pulp chamber: an in-vitro comparison between ultrasonic and rotating instruments in tooth preparation. Part 1.

Background: The purpose of this study was to analyze pulpal temperature increase generated by prosthodontic margin repositioning and finishing with ultrasonic and rotating instruments. The temperature changes recorded were also correlated with the residual dentin thickness.

Methods: A sample of 32 human extracted molars was selected.

4-Benzyl and 4-benzoyl-3-dimethylaminopyridin-2(1H)-ones: in vitro evaluation of new C-3-amino-substituted and C-5,6-alkyl-substituted analogues against clinically important HIV mutant strains.

In a program to optimize the anti-HIV activity of the 4-benzyl and 4-benzoyl-3-dimethylaminopyridinones 9 and 10, lead compounds in a new class of highly potent non-nucleoside type inhibitors of HIV-1 reverse transcriptase, modification of the alkyl substitutents at the C-5 and C-6 positions on the pyridinone ring and of the substitutents on the C-3 amino group has been studied. Of the 17 new 5/6-modified analogues prepared, compounds 31b and 32b substituted at C-5 by an extended nonpolar chain containing an ether function and a C-6 methyl group and compound 35 bearing a C-5 ethyl/C-6 hydroxymethyl substituent pattern were selected on the basis of their in vitro activity against wild-type HIV and the three principle mutant strains, K103N, Y181C, and Y188L. When tested further, it was shown that these molecules, and in particular compound 35, are globally more active than 9, 10, and efavirenz against an additional eight single [L100I, K101E, V106A, E138K, V179E, G190A/S, and F227C] and four double HIV mutant strains [L100I + K103N, K101E + K103N, K103N + Y181C, and F227L + V106A], which are clinically relevant.

Triple-helix directed cleavage of double-stranded DNA by benzoquinoquinoxaline-1,10-phenanthroline conjugates.

Oligonucleotide-directed triple-helix formation provides a rational means to interfere with genomic DNA targets and to direct modifications at specific sites. We have developed a new class of compounds that, at low concentrations, efficiently targets and damages double-stranded DNA specifically at the site where a triple-helical structure is formed. In these new compounds, a triple-helix-specific intercalator-benzoquinoquinoxaline (BQQ)-was coupled to one of two isomeric 1,10-phenanthrolinecarboxaldehyde derivatives.

4-benzyl- and 4-benzoyl-3-dimethylaminopyridin-2(1H)-ones, a new family of potent anti-HIV agents: optimization and in vitro evaluation against clinically important HIV mutant strains.

The 4-benzyl and 4-benzoyl-3-dimethylaminopyridinones 13 and 14 are representatives of a new class of highly potent non nucleoside type inhibitors of HIV-1 reverse transcriptase. To conduct SAR studies on these two lead compounds, 102 new analogues were prepared. Thirty-three compounds displayed nanomolar range activity in vitro against wild-type HIV-1, and among these, 18 were active against the 103N, Y181C, and Y188L mutant strains with IC50 values inferior to 1 microM.

Optimization of triple-helix-directed DNA cleavage by benzoquinoquinoxaline-ethylenediaminetetraacetic acid conjugates.

The formation of triple-helical structures of DNA is based on sequence-specific recognition of oligopyrimidine.oligopurine stretches of double-helical DNA. Triple-helical structures can be stabilized by DNA-binding ligands.

Synthesis and binding properties of oligo-2'-deoxyribonucleotides conjugated with triple-helix-specific intercalators: benzo[e] and benzo[g] pyridoindoles.

DNA binding compounds, such as benzo[e] (BePI) and benzo[g] pyridoindole (BgPI) derivatives, exhibit preferential stabilization of triple helices. We report here the synthesis of a series of pyrimidine triple-helix-forming oligo-2'-deoxyribonucleotides conjugated with these molecules. BePI was coupled to the 5-position of 2'-deoxyuridine via two linkers of different sizes attached to its 11-position and placed at either the 5'-end, inside the sequence, or at both the 5'-end and the internal positions using periodate oxidation of a diol-containing oligonucleotide followed by reductive coupling with amino-linked BePI.

Diphenyl quinolines and isoquinolines: synthesis and primary biological evaluation.

The synthesis of a series of 35 substituted 3,4-diphenyl quinolines and isoquinolines is described. The majority of these molecules differ from all other triphenylethylene based antiestrogens by a different spatial location of the aminoalkyl side chain. The binding affinity of the most representative molecules (8, 9, 19, 20, 21, 23 and 25), including analogues 8 and 21 without the side chain, for the estrogen receptor alpha (ER) was determined.

Synthesis and antiviral activity of 4-benzyl pyridinone derivatives as potent and selective non-nucleoside human immunodeficiency virus type 1 reverse transcriptase inhibitors.

Several 4-benzyl analogues of 5-ethyl-6-methyl-4-(phenylthio)pyridin-2(1H)-ones were synthesized and evaluated for their anti-HIV-l activities. Key transformations include metalation at the 4-C-position of 5-ethyl-2-methoxy-6-methyl-3-pivaloylaminopyridine (5) and its coupling with benzyl bromide or benzaldehyde derivatives. Biological studies revealed that some of the new 4-benzylpyridinones show potent HIV-1 specific reverse transcriptase inhibitory properties.

A new family of sequence-specific DNA-cleaving agents directed by triple-helical structures: benzopyridoindole-EDTA conjugates.

Sequence-specific DNA recognition can be achieved by oligonucleotides that bind to the major groove of oligopyrimidine x oligopurine sequences. These intermolecular structures could be used to modulate gene expression and to create new tools for molecular biology. Here we report the synthesis and biochemical characterization of triple helix-specific DNA cleaving reagents.

Synthesis and evaluation of "AZT-HEPT", "AZT-pyridinone", and "ddC-HEPT" conjugates as inhibitors of HIV reverse transcriptase.

To test the concept that HIV reverse transcriptase could be effectively inhibited by "mixed site inhibitors", a series of seven conjugates containing both a nucleoside analogue component (AZT 1, ddC 2) and a nonnucleoside type inhibitor (HEPT analogue 12, pyridinone 27) were synthesized and evaluated for their ability to block HIV replication. The (N-3 and C-5)AZT-HEPT conjugates 15, 22, and 23 displayed 2-5 microM anti-HIV activity, but they had no effect on the replication of HIV-2 or the HIV-1 strain with the Y181C mutation. The (C-5)AZT-pyridinone conjugates 34-37 were found to be inactive.

Design of a triple-helix-specific cleaving reagent.

Background: Double-helical DNA can be recognized sequence specifically by oligonucleotides that bind in the major groove, forming a local triple helix. Triplex-forming oligonucleotides are new tools in molecular and cellular biology and their development as gene-targeting drugs is under intensive study. Intramolecular triple-helical structures (H-DNA) are expected to play an important role in the control of gene expression.

Synthesis and in vitro evaluation of novel 2,6,9-trisubstituted purines acting as cyclin-dependent kinase inhibitors.

Novel C-2, C-6, N-9 trisubstituted purines derived from the olomoucine/roscovitine lead structure were synthesized and evaluated for their ability to inhibit starfish oocyte CDK1/cyclin B, neuronal CDK5/p35 and erk1 kinases in purified extracts. Structure activity relationship studies showed that increased steric bulk at N-9 reduces the inhibitory potential whereas substitution of the aminoethanol C-2 side chain by various groups of different size (methyl, propyl, butyl, phenyl, benzyl) only slightly decreases the activity when compared to (R)-roscovitine. Optimal inhibitory activity against CDK5, CDK1 and CDK2, with IC50 values of 0.

Synthesis of 9-O-substituted derivatives of 9-hydroxy-5, 6-dimethyl-6H-pyrido[4,3-b]carbazole-1-carboxylic acid (2-(dimethylamino)ethyl)amide and their 10- and 11-methyl analogues with improved antitumor activity.

Analogues of the antitumor drug S 16020-2 modified at the 9, 10, or 11 position were synthesized and evaluated in vitro and in vivo on the P388 leukemia and B16 melanoma models. Starting from 9-methoxy-5, 11-dimethyl-6H-pyrido[4,3-b]carbazole-1-carboxylic acid ethyl ester, the 11-CH3 analogue of 9-hydroxy-5,6-dimethyl-6H-pyrido[4, 3-b]carbazole-1-carboxylic (2-(dimethylamino)ethyl)amide (1), compound 4, was synthesized using a four-step sequence, whereas its 10-CH3 analogue 5 was prepared using a two-step pathway, starting from compound 1. Finally starting from the 9-OH compounds 1, 4, and 5, a series of variously 9-O-substituted derivatives were synthesized.

Synthesis of C2 alkynylated purines, a new family of potent inhibitors of cyclin-dependent kinases.

The synthesis of a new family of inhibitors of the cell cycle regulating cyclin-dependent kinases (CDK's) is reported. These compounds, related to the purines olomoucine and roscovitine, are characterised by the presence of alkynylated side chains at C2. They inhibit CDK's with IC50's in the 200 nM range.

Triple helices formed at oligopyrimidine*oligopurine sequences with base pair inversions: effect of a triplex-specific ligand on stability and selectivity.

Oligonucleotide-directed triple helix formation is mostly restricted to oligopyrimidine*oligopurine sequences of double helical DNA. An interruption of one or two pyrimidines in the oligopurine target strand leads to a strong triplex destabilisation. We have investigated the effect of nucleotide analogues introduced in the third strand at the site opposite the base pair inversion(s).

Synthesis, properties and biological evaluation of substituted furo[3,2-e] and pyrano[3,2-e]pyrido[4,3-b]indoles.

Furo[3,2-e]- and pyrano[3,2-e]pyrido[4,3-b] indoles were synthesized from 1,4,5-trisubstituted 8-hydroxy-5H-pyrido[4,3-b]indoles. The intermediates, 10-chloro-6H-furo[3,2-e]pyrido[4,3-b]indole (11), 10-chloro-2,6-dihydro-1H-furo[3,2-e]pyrido-[4,3-b]indole (10) and 11-chloro-2,3-dihydro-3H,7H-pyrano[3,2-e]pyrido[4,3-b]indole (15), were substituted by diamines under thermal conditions (180 degrees C). In contrast, 11-chloro-3H,7H-pyrano[3,2-e]pyrido[4,3-b]indole (14), 9-allyl-1-chloro-4,5-dimethyl-5H-pyrido[4,3-b]indole (9a) and 8-propargyloxy-4,5-dimethyl-5H-pyrido[4,3-b]indole (8) led mainly to 1-aminosubstituted 8-hydroxy-5H-pyrido[4,3-b]indole derivatives resulting from an unexpected C3 unit elimination.

1-Amino-substituted 8-hydroxy-4,5-dimethyl-5H-pyrido[4,3-b]indoles with propyl- or methyl substituents at the 9-, and 7,9-positions: synthesis and biological evaluation.

The title compounds were synthesized in 9-10 steps in order to compare their cytotoxic properties to that for 1-(3-dimethylaminopropyl)-amino-4,5-dimethyl- 8-hydroxy-5H-pyrido[4,3-b]indole. Whereas the latter is a potent cytotoxic agent, displaying significant antitumour activity, the corresponding 9-propyl (and 7,9-dimethyl) derivatives were found to be > 10-fold less cytotoxic.

Rational design of a triple helix-specific intercalating ligand.

DNA triple helices offer new perspectives toward oligonucleotide-directed gene regulation. However, the poor stability of some of these structures might limit their use under physiological conditions. Specific ligands can intercalate into DNA triple helices and stabilize them.

Spectroscopic study of the interaction of pazelliptine with nucleic acids.

The antitumor drug pazelliptine (PZE) binds to natural and synthetic DNA sequences at 100 mM NaCl, pH 7.0, as deduced from the absorption and fluorescence data. Scatchard plots constructed from the results obtained with poly(dG-dC)-poly(dG-dC) give binding constants of base pairs in the range (2-6) x 10(5)M(-1).

Synthesis, DNA binding, and cleaving properties of an ellipticine-salen.copper conjugate.

The synthesis of a DNA-cutting agent that conjugates an ellipticine chromophore and a copper complex of bis(salicylidene)ethylenediamine, referred to as a salen, is reported. The presence of the salen.Cu complex allows cleavage of DNA via oxygen-based radicals, and the ellipticine moiety serves as a DNA anchor.

Genistein analogues: effects on epidermal growth factor receptor tyrosine kinase and on stress-activated pathways.

Two genistein analogues (MD831 and MD833) have been synthesized and analyzed for their biological properties and their mechanism of action im comparison to genistein either in vitro or in intact cells. We showed that, in vitro, one of these compounds (MD831) inhibits the tyrosine kinase activity associated with the epidermal growth factor receptor (EGFR) as efficiently as genistein. However, treatment of A431 cells with these compounds did not result in any significant modification of EGFR tyrosine phosphorylation.

Conjugates of oligonucleotides with triplex-specific intercalating agents. Stabilization of triple-helical DNA in the promoter region of the gene for the alpha-subunit of interleukin 2 (IL-2R alpha).

The stabilization of triple-helical DNA under physiological conditions is an important goal for the control of gene expression using the antigen strategy, an approach whereby an oligonucleotide binds to the major groove of double-helical DNA to fom a triple helix. To this end, triplex-specific intercalators, namely benzopyridoindole (BPI) and benzopyridoquinoxaline (BPQ) derivatives, have been conjugated to the 5' end or to an internucleotide position of a 15-mer oligonucleotide. These conjugates were then tested, using thermal denaturation experiments, for their ability to form and stabilize a triple-helical structure involving a 42-mer duplex target.

Synthesis and biological evaluation of 6-(9-hydroxy-5-methyl (and 5,6-dimethyl)-6H-pyrido[4,3-b]carbazol-1-yl)picolinic amides as new olivacine derivatives.

Starting from 2-(6-methoxy-1-methylcarbazol-2-yl)ethylamine and diethyl-2,6-pyridine dicarboxylate, the title compounds were obtained through five or six steps. The new compounds retained significant cytotoxicity towards various tumor cell lines, but in vivo studies on murine P388 leukemia, B16 melanoma and Lewis lung carcinoma showed a lowered antitumor activity with respect to that of the related olivacine lead compound 1.

Ligand-induced formation of triple helices with antiparallel third strands containing G and T.

We have examined the effects of benzopyridoindole derivatives on triple helices with antiparallel third strands. Absorption spectroscopy, footprinting, and gel retardation experiments demonstrate that a benzopyridoindole derivative (BePI) is able to induce formation of a triple helix with an antiparallel (G, T)-containing third strand, which does not form in the absence of this ligand. This triple-helical complex is very stable with a half-dissociation temperature as high as 51 degrees C, and its formation is pH independent.