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Biomedical subjects

F Morvan

Publications and source records attributed to F Morvan.

At least 37 records · Page 2Linked to original sources

4'-Thio-RNA: synthesis of mixed base 4'-thio-oligoribonucleotides, nuclease resistance, and base pairing properties with complementary single and double strand.

4'-Thio-beta-D-oligoribonucleotides (12 mer and 16 mer) containing a mixed base sequence were synthesized via the phosphoramidite solid support approach. These RNA analogs showed very good nuclease resistance as compared with wild-type RNA. Furthermore, 4'-thio-beta-D-oligoribonucleotides were shown to hybridize with a complementary DNA or RNA strand to form a duplex or with a DNA hairpin to form a triple helix. 4'-Thio-RNA binds more tightly to its complementary RNA strand than to its complementary DNA strand. A 4'-thio-RNA:RNA duplex is as stable as a 2'-O-methyl-RNA:RNA duplex. 4'-Thio-RNA, however, forms a 4'-thio-RNA:DNA:DNA triplex with a stability similar to the corresponding triplex with all wild-type DNA.

Amides↗

[Classification of cancers for clinical use].

The clinical classification of cancers has become necessary along the past decades to optimize treatments according pronostic and to allow scientific exchanges among the medical oncology community. The TNM staging system, with the derivates classifications, and the use of pronostic models, is now universal and applied to almost all human neoplasms. Therefore, the classification of cancers is now become an evoluting instrument of long-term evaluation of neoplastic diseases as well as medical oncology practice.

Humans↗

Phase II randomized study of paclitaxel versus mitomycin in advanced breast cancer.

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has been shown to be an effective agent in the treatment of metastatic breast carcinoma. This multicenter randomized study compared paclitaxel 175 mg/m2 given as a 3-hour infusion every 3 weeks with mitomycin 12 mg/m2 given as an intravenous infusion every 6 weeks. Eighty-one patients have been randomized, and preliminary results of a planned analysis of the first 36 evaluable patients per arm are reported. Pretreatment characteristics were well balanced between the two groups. All patients previously have received chemotherapy for metastatic disease, and half had both adjuvant therapy and chemotherapy for metastatic disease. All but one patient previously had received anthracyclines. Of the first 81 randomized patients, 72 were evaluable for response and toxicity (four never treated, five concomitant hormonotherapy). Partial responses were seen in 17% of patients in the paclitaxel arm and 6% in the mitomycin arm (P = .14). Crossover to paclitaxel therapy following progression on mitomycin achieved an objective response rate of 24% (five of 21 patients). Responses to paclitaxel therapy lasted for a median duration of 9.1 months (range, 6.2 to 12+ months). Median time to progression was significantly longer in the paclitaxel arm (3.5 months v 1.6 months; P = .026). The quality-of-life-adjusted analysis confirmed the advantage of paclitaxel therapy, even when the delay of disease progression was adjusted for important adverse events. Adverse events, most importantly neutropenia and neuropathy, were more frequently observed in the paclitaxel arm. However, patients remained on paclitaxel therapy for many more courses than did those treated in the mitomycin arm. In conclusion, paclitaxel 175 mg/m2 given as a 3-hour intravenous infusion has been demonstrated to be an active agent in the treatment of chemotherapy-refractory advanced breast cancer, even after therapy with mitomycin has failed.

Adult↗

[Inflammatory cancer of the breast: review and experience at Saint-Louis hospital].

Inflammatory breast cancer represents about 1 to 6% of all breast cancers. It has a sudden onset and affects women of the same age as other breast cancers. Its particular feature is the almost constant development of metastases. The 5-year survival after surgery or surgery and radiotherapy varies between 0 and 28% with a median survival of 18 months. The use of anthracycline-based chemotherapy has doubled the median survival, but has not achieved cure. Clinical research is directed towards therapeutic intensification with or without autologous bone marrow transplantation. The authors report their experience at Hôpital Saint-Louis.

Adolescent↗

Sequence-specific interaction of alpha-beta-anomeric double-stranded DNA with the p50 subunit of NF kappa B: application to the decoy approach.

The potential use of alpha-beta-anomeric duplex oligonucleotides to inhibit transcription factor activity by the decoy approach is investigated in this report. Indeed, several alpha-beta-anomeric heteroduplexes display a sequence-specific interaction with the p50 subunit of the transcription factor NF kappa B. Used in a decoy approach, these duplexes interact strongly enough with this transcription factor to modulate the expression of a reporter gene, under the control of NF kappa B. However, all the alpha-beta-anomeric heteroduplexes do not interact with the p50 subunit; the sequence of the chirally natural beta-anomeric strand may explain the different recognition properties of the protein. The analysis of the appropriate beta-anomeric sequences is consistent with a preferential interaction of the p50 subunit with one strand of double-stranded DNA.

Base Sequence↗

Rapid determination of the affinity of 28- and 14-mer phosphorothioate oligonucleotides for HIV-1 reverse transcriptase by fluorescence spectroscopy.

Intrinsic fluorescence of human immunodeficiency virus type 1 reverse transcriptase (E.C. 2.7.7.49) and displacement experiments of a fluorescent template.primer probe were used to study the interaction of the enzyme with several types of 28- and 14-mer normal or phosphorothioate oligodeoxycytidinylates and their duplexes with poly(rI). The two methods gave convergent results and allowed in each case fast determinations of ligand affinities for the enzyme. The dissociation constants (Kd) obtained from intrinsic fluorescence changes were slightly lower than those determined from the less direct competitive displacement experiments. In all cases, the enzyme displayed better recognition of the hybrid than of the unannealed oligonucleotide. The Kd values of phosphorothioate oligomers and their hybrids were lower than those of the corresponding normal oligomers and hybrids, but the difference was not as significant as in the case of the Ki constants for (dC)28 and S(dC)28 (Majumdar et al. (1989) Biochemistry 28, 1340). The affinities of the annealed phosphorothioate oligodeoxycytidinylates for the enzyme were found to be larger than for any other compounds in this series (Kd of poly(rI).S(dC)28: 0.28 nM at 25 degrees C). Changing the beta stereochemistry of the oligomer bases to alpha did not alter the affinity of the oligodeoxycytidinylate and its hybrids for the enzyme.

Base Sequence↗

Triple helix formation by alpha-oligodeoxynucleotides: a vibrational spectroscopy and molecular modeling study.

The structures of triple helices alpha dT6.beta dAn.beta dTn, alpha dT12.beta dAn.beta dTn, alpha dC12+.beta dGn.beta dCn, and alpha dC12+.beta rGn.beta rCn have been studied by Fourier transform infrared spectroscopy, Raman spectroscopy, and molecular mechanics calculations. The sugar conformations in these triplexes have been determined by vibrational spectroscopy. Our results show the existence of only S-type sugars in the alpha dT12.beta dAn.beta dTn triple helix. Both S- and N-type sugar infrared and Raman markers have been detected in the spectra of alpha dC12+.beta dGn.beta dCn. Molecular mechanics refinements taking into account vibrational spectroscopy data constraints allow us to propose third strand hydrogen-bonding schemes and third strand polarities in triple helix models. For alpha dT12.beta dA12.beta dT12 the third strand forms reverse Hoogsteen hydrogen bonds with the beta dA12 strand and therefore is parallel to the purine strand. In contrast, for alpha dC12+.beta dG12.beta dC12 calculations show that only a model in which the third strand is Hoogsteen base paired and antiparallel to the purine strand of the Watson-Crick duplex is compatible with spectroscopic data.

Hydrogen Bonding↗

Comparative evaluation of seven oligonucleotide analogues as potential antisense agents.

12-Mer analogues, representative of seven different classes of structurally modified oligonucleotides and complementary to the same target, have been compared for their binding affinity for both single-stranded DNA and RNA, resistance to hydrolysis by nucleases in culture medium (RPMI 1640 + 10% inactivated fetal calf serum), and inhibition of HIV-1 replication in de novo infected MT4 T lymphocytes. The viral target was the splice acceptor site of the premessenger coding for the regulatory protein tat. The oligo(2'-O-alkyl)ribonucleotides (beta-2'O-allyl-RNA and beta-2'OMe-RNA) were shown to form the most stable hybrids with complementary RNA strands whereas the alpha-anomeric oligodeoxynucleoside phosphorothioate analogue displayed the highest stability in the culture medium. All the modified oligonucleotides examined in the present study exhibited a sequence-nonspecific inhibitory effect on HIV-1 replication, the phosphorothioate analogues being the most active ones (ED50 < 1 microM).

Antiviral Agents↗

[Promising results of bimonthly chemotherapy with high dose cyclophosphamide and epirubicin in induction treatment of inflammatory cancer of the breast].

Forty-eight patients with inflammatory breast cancer were treated by an induction regimen with cyclophosphamide (1200 mg/m2), and epirubicin (75 mg/m2). Four to six courses were given every two weeks, whatever the absolute leukocyte counts, before mastectomy, loco-regional radiation, and conventional, or reinforced, for selected patients, chemotherapy. Main toxicity was leukopenia, with grade IV in 25% of cases. However, febrile neutropenia was rare, and relative dose intensity was 102% after four courses, and 97% after six courses. Complete disappearance of inflammatory signs was observed in 90% of patients. Three patients had a pathological complete response, and ten patients had negative axillary lymph nodes. Furthermore, 13 patients had a major pathological response. With a median follow-up of 42 months, progression-free survival and overall survival are 48% and 66%, respectively.

Adolescent↗

Template. Phosphorothioate oligonucleotides duplexes as inhibitors of HIV-1 reverse transcriptase.

We have investigated the interaction between a number of 14 mers phosphorothioate oligonucleotides and HIV-1 reverse transcriptase. Two methods were used to measure the affinity of the analogs for the enzyme. In the first, the oligonucleotide or its duplex with Poly(rl) were used as inhibitors of the enzyme using Poly(rA).(dT)14 as template primer. In the second, the oligonucleotides or their duplexes were used to displace a fluorescent template primer complex of known affinity from its binding site on reverse transcriptase. The two methods gave the same relative order of affinity. Phosphorothioate oligodeoxyribonucleotides had a much higher affinity than oligo(dC)14 and it was increased on hybridization. Quantitatively similar results were obtained for S(dC)14 or its analog with bases in the alpha-configuration. Of the analogs tested, only S(dC)14 showed priming activity.

Antiviral Agents↗

Sugar modified oligonucleotides: synthesis, nuclease resistance and base pairing of oligodeoxynucleotides containing 1-(4'-thio-beta-D-ribofuranosyl)-thymine.

XdT12 and dT5XdT6, where X is 1-(4'-thio-beta-d-ribofuranosyl)-thymine, were synthesized. The first oligonucleotide presents a better stability against calf spleen phosphodiesterase than natural dT12. The second one hybridizes with complementary sequence. However the X:A base pairing stability is lower than natural T:A one.

Animals↗

Structure and conformation in solution of the parallel-stranded hybrid alpha-d(CGCAATTCGC).beta-d(GCGTTAAGCG) by high-resolution 2D NMR.

The unnatural duplex oligonucleotide alpha-d(CGCAATTCGC).beta-d(GCGTTAAGCG) was analyzed by high-resolution NMR methods. All of the exchangeable imino and nonexchangeable protons of the duplex were assigned. Detection of all 10 of the exchangeable imino protons confirms that a parallel, unsymmetrical duplex is formed. The thermal stability of the parallel duplex is similar to the analogous antiparallel beta-beta duplex. The right handedness of the helix is confirmed by inter-residue [H8/H6-H1'] and [H8/H6-H2"] NOEs to the 5'-neighbor in the beta-strand and [H8/H6-H1'] NOEs to the 3'-neighbor in the alpha-strand. Intra-residue and inter-residue distances between base protons and deoxyribose protons in both strands were determined using the isolated spin-pair approximation for NOESY cross peaks acquired with mixing times 50 ms or less. The NOE data are consistent with a B-form geometry adopted by the alpha/beta hybrid decamer.

Base Sequence↗

Phase II study of tetrahydropyranyl adriamycin (pirarubicin) in elderly patients with advanced breast cancer.

Thirty elderly (over 70 years) women with measurable advanced breast cancer entered into this Phase II study. An initial dose of 30 mg/m2 of pirarubicin (THP) every 3 weeks was given intravenously. THP was escalated by levels of 10 mg/m2 according to the blood cell count done at day 14 and day 21 until a maximum dose per cycle of 70 mg/m2 was reached. The mean total cumulative dose of THP received was 204 mg/m2 (range 30-710 mg/m2). The mean number of cycles given was 5.5 (range 1-24). Of 28 evaluable patients, 1 achieved a complete response (CR), 6 had a partial response (PR) (CR + PR = 25%; 95% confidence interval 9-41%), 13 showed no change, and 5 had a progressive disease. The median time to progression was 3 months (range 0.5-18+ months). Of 28 patients evaluable for toxicity, the hematologic toxicity at day 15 was neutropenia grade 3 and 4 in 61% of the patients and thrombopenia grade 3 and 4, 0% of cycles. No cumulative hematologic toxicity was detected. Nonhematologic toxicities consisted of nausea and vomiting in 50% of patients (WHO grade 3 = 5%) and alopecia in 64% (WHO grade 2-3 = 36%). No stomatitis occurred. No cardiac toxicity was observed. The results of this study show that THP is an active drug in elderly patients with advanced breast cancer. Because of its safety, THP deserves further investigation in this application.

Adenocarcinoma↗

Alpha-oligonucleotides: a unique class of modified chimeric nucleic acids.

alpha-Anomeric oligonucleotides are resistant to nucleases and display parallel hybridization with complementary DNA and RNA sequences. Although alpha-DNA/beta-RNA duplexes are not substrates for RNases H, alpha-oligos are able to inhibit translation through a RNase H independent mechanism. alpha-Oligos and their alpha-phosphorothioate analogs (12 mer) targeted against the splice acceptor site of the HIV-TAT gene were potent inhibitors of de novo HIV infection. Furthermore alpha-phosphorothioate and dithioate homo-oligomers exhibit an in vitro, nonsequence-specific, inhibitory effect on HIV reverse transcriptase.

Base Sequence↗

Polarity of annealing and structural analysis of the RNase H resistant alpha-5'-d[TACACA].beta-5'-r[AUGUGU] hybrid determined by high-field 1H, 13C, and 31P NMR analysis.

The novel hybrid duplex alpha-5'-d[TACACA]-3'.beta-5'-r[AUGUGU]-3' was analyzed extensively by 1D and 2D NMR methods. Two forms of the duplex exist in about an 80:20 ratio. Analysis of the exchangeable imino protons of the major component revealed that three AU and one AT base pair are present in addition to two GC base pairs, confirming that the duplex anneals in parallel orientation. The presence of the AT base pair, which can only be accounted for by a parallel duplex, was confirmed by a selective INEPT experiment, which correlated the thymidine imino proton to its C5 carbon. The lesser antiparallel form could be detected by exchangeable and nonexchangeable proton resonances in both strands. An exchange peak was observed in the NOESY spectrum for the thymidine methyl group resonance in both the predominant and lesser conformations, indicating the lifetime of the individual structures was on the millisecond time scale. The nonexchangeable protons of the predominant duplex were assigned by standard methods. The sugar pucker of the ribonucleosides was determined to be of the "S" type by a pseudorotation analysis according to Altona, with the J-couplings measured from the multiplet components of the phase-sensitive COSY experiment. The NOE pattern observed for the alpha-deoxynucleosides also suggested an S-type sugar pucker. The adoption of an S-type sugar pucker for both strands indicates that, in contrast to RNA.DNA duplexes formed exclusively from beta-nucleotides, the alpha-DNA.beta-RNA duplex may form a B-type helix. The 31P resonances of the alpha and beta strands have very different chemical shifts in the hybrid duplex and the difference persists above the helix melting temperature, indicating an intrinsic difference in 31P chemical shift for nucleotides differing only in the configuration about the glycosidic bond.

Base Composition↗