[Avascular jaw osteonecrosis in a hemodialysis patient treated with bisphosphonates]. / Osteonecrosi avascolare mandibolare in un paziente in trattamento emodialitico sostitutivo trattato con bifosfonati.

Bisphosphonates are molecules derived from pyrophosphates,but, unlike pyrophosphates, they are resistant to enzymatic hydrolysis. Bisphosphonates are used in the treatment of Paget's disease, cancer-related osteolysis, myeloma, primary hyperparathyroidism, and osteoporosis. In dialysis patients bisphosphonates may be used to reduce bone pain due to renal osteodystrophy. We describe the case of a 60-year-old woman with a history of breast cancer who had been on dialysis for 8 years. She had been receiving clodronic acid at 100 mg per week intravenously for the last 2 years. A year ago, the patient underwent surgical extraction of the lower right second molar. Her jaw pain increased in the following days. An orthopanthograph and a CT scan of the head showed osteolysis, and a surgical osteotomy was performed. Histological examination led to a diagnosis of avascular osteonecrosis of the jaw. Avascular osteonecrosis is typically described in the jaw. In this case, prolonged bisphosphonate treatment may have worsened the osteonecrosis.

[Quality in dialysis]. / La qualità in dialisi.

BACKGROUND: Several clinical and laboratory dialysis parameters have been suggested by national and international guidelines. Our study aimed to evaluate a series of quality indicators in the dialytic treatment of a group of patients in our two dialytic centers. PATIENTS AND METHODS: In a population of 159 patients on renal replacement therapy (RDT) we performed a 1-yr prospective observational study, with common parameters to indicate cardiovascular pathologies (PAS, LVMI), calcium-phosphorous metabolism (Ca, PO 4 , Ca x PO 4 ), dialytic adequacy (Kt/V, URR%), nutritional status (nPCR, Alb, K), and anemia (hemoglobin (Hb)). For each parameter we evaluated the mean average with the standard deviation and the score percentages below and above the acceptable range (AR). RESULTS: The results demonstrated a substantial stability, with a gradual improvement, in dialytic adequacy, in anemic status and in PAS. The LVMI, calculated at the beginning and at the end of the period, did not demonstrate any significant changes. No significant changes were observed in the calcium-phosphorous metabolism parameters. Serum albumin and nPCR demonstrated the presence of malnutrition in 15-20% of patients. CONCLUSIONS: There was a more than adequate correlation between the target guidelines and that concerning the dialytic adequacy and the corrected anemic status. The improvement in parameters related to cardiovascular pathology, the risk of ectopic calcifications and malnutrition status, represented an achievable target.

Synthesis and antitumor activity of new benzoheterocyclic derivatives of distamycin A.

The design, synthesis, and in vivo and in vitro antileukemic activity of a novel series of compounds (13-22 and 34), in which different benzoheterocyclic rings, bearing a nitrogen mustard or a benzoyl nitrogen mustard or an alpha-bromoacryloyl group as alkylating moieties, are tethered to a distamycin frame, are reported, and structure-activity relationships are discussed. The new derivatives were prepared by coupling nitrogen mustard-substituted, benzoyl nitrogen mustard-substituted, or alpha-bromoacryloyl-substituted benzoheterocyclic carboxylic acids 23-32 with desformyldistamycin (33) or in one case with its two-pyrrole analogue 35. With very few exceptions, the activities of compounds bearing the same alkylating moiety are slightly affected by the kind of the heteroatom present on the benzoheterocyclic ring. All novel compounds, with one exception, showed in vitro activity against L1210 murine leukemia cell line comparable to or better than that of tallimustine. The compounds in which the nitrogen mustard and the alpha-bromoacryloyl moieties are directly linked to benzoheterocyclic ring showed potent cytotoxic activities (IC(50) ranging from 2 to 14 nM), while benzoyl nitrogen mustard derivatives of benzoheterocycles showed reduced cytotoxic activities, and one compound (16) of this cluster was the sole derivative devoid of significant activity. Compound 18, a 5-nitrogen mustard N-methylindole derivative of distamycin, showed the best antileukemic activity in vivo, with a very long survival time (%T/C = 457), significantly increased in comparison to tallimustine (%T/C = 133), and was selected for further extensive evaluation. Arrested polymerase chain reaction and direct DNA fragmentation assays were performed for compound 18 and the structurally related compounds 13-17 and 19. The results obtained have shown that both alkylating groups and oligopeptide frames play a crucial role in the sequence selectivity of these compounds.

Synthesis and immunosuppressive activity of novel prodigiosin derivatives.

Prodigiosins (Ps) represent a family of naturally occurring red pigments characterized by a common pyrrolylpyrromethene skeleton. Some members of this family have been shown to possess interesting immunosuppressive properties exerted with a novel mechanism of action, different from that of currently used drugs. In fact, Ps inhibit phosphorylation and activation of JAK-3, a cytoplasmic tyrosine kinase associated with a cell surface receptor component called common gamma-chain, which is exclusive of all IL-2 cytokine family receptors. Blocking common gamma-chain transduction activity results in a potent and specific immunosuppressive activity. With respect to the interesting and unexploited immunomodulating properties of this family of compounds we initiated a medicinal chemistry program aimed at finding novel prodigiosin derivatives with improved immunosuppressive activity and lower toxicity. Utilizing an unprecedented and flexible way of assembling the prodigiosin frame, a number of new derivatives have been prepared and tested leading to the choice of 4-benzyloxy-5-[(5-undecyl-2H-pyrrol-2-ylidene)methyl]-2, 2'-bi-1H-pyrrole (PNU-156804, 16) as a lead immunosuppressant.

Cytotoxic halogenoacrylic derivatives of distamycin A.

The design, synthesis, in vitro and in vivo activities of a series of halogenoacrylic derivatives of distamycin A are described. The structure-activity relationships indicate a key role of the reactivity of alpha-halogenoacrylic moiety. The reactivity and the putative alkylating mechanism of these compounds are different from those of the nitrogen mustards and possibly based on a Michael type reaction. This supports the hypothesis that these compounds represent a class of minor groove binders mechanistically different from tallimustine.

Cytotoxic alpha-bromoacrylic derivatives of distamycin analogues modified at the amidino moiety.

The design, synthesis, in vitro and in vivo activities of novel alpha-bromoacrylic derivatives of distamycin A, modified at the amidino moiety by the replacement with basic or non-basic groups are reported. In spite of the relevance of these modifications of distamycin frame, the new derivatives are potent cytotoxics. The presence of the amidino moiety, is, therefore; not an absolute requirement for the activity. In particular due to a favorable myelotoxicity/cytotoxicity ratio, guanidino derivative PNU 166196 was selected for clinical development.

Research on anti-HIV-1 agents. Investigation on the CD4-Suradista binding mode through docking experiments.

Sulfonated distamycin (Suradista) derivatives exhibit anti-HIV-1 activity by inhibiting the binding of the viral envelope glycoprotein gp120 to its receptor (CD4). With the aim to propose a possible binding mode between Suradistas and the CD4 macromolecule, molecular docking experiments, followed by energy minimization of the complexes thus obtained, were performed. Computational results show that ligand binding at the CD4 surface involves two or three positively charged regions of the macromolecule, in agreement with the results of X-ray crystallographic analysis of a ternary complex (CD4/gp120/neutralizing antibody) recently reported in the literature. Our findings account well for the structure-activity relationship found for Suradista compounds.

DNA sequence-recognizing properties of minor groove alkylating agents. Effects of the replacement of N-methylpyrrole by an N-methylimidazole on tallimustine and its own homologue.

The linkage of an heterocycle, like N-methylimidazole, to minor DNA groove binders containing two or three pyrroles lead to a new class of oligopeptides with reduced antitumor activity both in vitro and in vivo if compared to tallimustine (CAS 115308-98-0) and its tetrapyrrole homologue 9. In the present paper is reported the correlation between the cytoxicity of tallimustine and its derivatives 9-11 with their ability to inhibit polymerase chain reaction (PCR) amplification of oestrogen receptor and Ha-ras gene sequences, containing A + T rich and G + C rich regions, respectively. Tallimustine and its tetrapyrrole homologue 9 were found to have higher sequence selectivity for the human oestrogen receptor (ER) gene with respect to the relative imidazole-containing analogues.

PNU 157977: a new potent antitumour agent exhibiting low in vivo toxicity in mice injected with L1210 leukaemia cells.

The design, synthesis, in vitro and in vivo activity against L1210 murine leukaemia of the dibromo nitrogen mustard derivative of 2, called PNU 157977, is described and the structure-activity relationship discussed. This dibromo derivative is almost two orders of magnitude more cytotoxic than the dichloro counterpart having the same oligopeptidic chain (IC50 2.7 ng/ml versus 225 ng/ml), and it showed in vivo an increased survival time which is 5- and 3-fold longer than that of tallimustine and 2 (and T/C 750 versus 133 and 213) respectively. Moreover PNU 157977 shows activity against the M5076 solid tumour markedly inferior to that of the closely analogous 2. Footprinting experiments conducted using the oestrogen receptor PCR probe as the footprinting target molecule show that PNU 157977 possesses a different sequence-specific alkylation and greater cleavage activity than either 2 or tallimustine.

Novel benzoyl nitrogen mustard derivatives of pyrazole analogues of distamycin A: synthesis and antileukemic activity.

The design and synthesis of novel benzoic acid mustard (BAM) derivatives of distamycin A bearing one or more pyrazole rings replacing the pyrrole rings of the latter are described. In vitro and in vivo activities against L1210 leukemia are reported and discussed. Some of these compounds show an activity profile comparable to tallimustine 1. All the compounds bearing the pyrazole ring close to the BAM moiety show reduced cytotoxicity in comparison to derivatives characterized by the BAM linked to a pyrrole: the same effect has not been observed when occurring at the amidine terminus of the oligopeptidic frame.

Synthesis and binding mode of heterocyclic analogues of suramin inhibiting the human basic fibroblast growth factor.

The design, synthesis, and biological evaluation of a series of pyrrole and pyrazole congeners 2 of suramin, directed toward the development and identification of new ligands that complex the human fibroblast growth factor (bFGF), thereby inhibiting tumor-promoted angiogenesis, is reported. Compounds 2 were evaluated for their ability to inhibit binding of bFGF to its receptor, in vivo bFGF-induced angiogenesis, and neovascularization of the chorioallantoic membrane in comparison with suramin. These assays showed that ligands 2 exhibit moderate to good activity, comparable to that of suramin, and are less toxic than suramin itself. In this study, affinity data of ligands in combination with the crystal structure of bFGF were used to explain structure-affinity relationships and to gain an insight into the possible mode of ligand-protein interaction. Due to the lack of experimental structural data on the ligand-bFGF complexes, molecular mechanics techniques were used to obtain putative bioactive conformations and to generate docked complexes with the three-dimensional structure of bFGF. These experiments led to suggest that compounds 2 give rise to 1:1 complexes with bFGF through an unprecedented, bidentate attachment of their naphthylsulfonate groups to two main domains, commonly referred to as the heparin binding site and the receptor binding site, on bFGF, thus preventing the interaction of the growth factor with its receptor.

Design, synthesis and biological activity of a pyrrolo [2,1-c][1,4]benzodiazepine (PBD)-distamycin hybrid.

We report the synthesis of a new hybrid 13 which is a combination of the naturally occurring antitumor agent distamycin A 1 and the pyrrolo[2,1-c][1,4]benzodiazepine 11, related to the naturally occurring anthramycin 2. The antitumor activity of the hybrid 13 was tested in vitro and compared to the natural product distamycin 1 and the PBD 11.

Cytotoxics derived from distamycin A and congeners.

Distamycin A is an antibiotic, characterised by an oligopeptidic pyrrolocarbamoyl frame ending with an amidino moiety, which binds reversibly to DNA minor groove with high selectivity for TA-rich sequences and shows antiviral and antiprotozoal activity. Distamycin was used as DNA sequence selective vector of alkylating functions, leading to a substantial increase of cytotoxicity in comparison to that, very weak, of distamycin itself. The benzoyl nitrogen mustard derivative of desformyldistamycin, tallimustine, was selected as a candidate antineoplastic drug in view of its strong activity against a series of experimental tumors. Tallimustine, like distamycin, shows DNA selective binding to TA-rich sequences but its cytotoxicity is not associated with DNA strand breaks and interstrand crosslinking, at variance with classical phenyl nitrogen mustards. Tallimustine represents an important model for the design of new minor groove alkylating agents derived from distamycin and analogues, including the so-called lexitropsins, sequence-reading oligopeptides in which one or more N-methyl-pyrrole units of distamycin are replaced by imidazole or other rings. The structural features of the alkylating moieties and binding frames, the antitumor activities and the mechanism of action of most representative cytotoxics derived from distamycin and congeners are discussed. Some of these, recently reported, show an activity profile apparently superior to tallimustine. Finally, a concise survey of representative hybrid compounds in which known non-alkylating cytotoxic agents or their active moieties have been tethered to distamycin and congeners is presented and briefly discussed. These compounds witness the attention paid to this approach on the basis of the interest for the DNA binding features of distamycin A.

Synthesis, cytotoxicity, antitumor activity and sequence selective binding of two pyrazole analogs structurally related to the antitumor agents U-71,184 and adozelesin.

Two pyrazole analogs structurally related to the antitumor agents adozelesin and U-71,184 respectively were synthesized. By using a polymerase chain reaction approach, both compounds show selective binding to A + T rich sequences exactly as reference compound U-71,184. In in vitro assays, against L1210 cell lines, both derivatives showed cytotoxicity in the pM range, values comparable with the natural target compound (+)-CC-1065. The most active compound showed very high antitumor activity in mice implanted with L1210 cells (ILS% 363).

Synthesis, solvolytic stability and cytotoxicity of a modified derivative of CPzI, a pyrazole analog of the alkylation subunit of the antitumor agent CC-1065: effect of the nitrogen substitution on the functional reactivity.

The synthesis and the comparative preliminary biological evaluation of a new pyrazole analog (16) of the CC-1065 alkylating unit (CPI) are described. This new derivative showed low cytotoxicity against L1210 murine leukemia (IC50 3064 nM) with respect to reference compound, but contrarily to literature data, was found to be more stable to solvolysis than the natural derivative (+/-)-N-Boc-CPI (pH 3, t1/2 = 212 h vs. 37 h). The results of such investigation showed that alkylation of the pyrazole nitrogen caused a loss of cytotoxic activity in vitro against tumor cells. This experimental observation allowed us to confirm the importance of free N-H for the anticellular activity.

Synthesis, cytotoxicity and antitumor activity of some new simplified pyrazole analogs of the antitumor agent CC-1065. Effect of an hydrophobic group on antitumor activity.

Three simplified pyrazole analogs (7-9) of the antitumor agents CC-1065, were synthesized. In in vitro assays, against L1210 cell lines all derivatives showed a cytotoxicity in a pM range, values close to the natural target compound (+)-CC-1065. In in vivo tests, against disseminate L1210 leukemia cells, synthesized compounds showed a good potency (O.D. 300 micrograms/Kg) but no activity. These observations further validate the effect of the hydrophilic and/or hydrophobic characteristics of the substituents present on the molecules, confirming the relevance of this phenomena on in vivo activity. In fact in this case the increase of hydrophobic characteristics of the molecules produce the loss of activity, probably due to a worse bioavailability of the drugs in animals.

Effects of a novel DNA-damaging agent on the budding yeast Saccharomyces cerevisiae cell cycle.

We have investigated the effects on Saccharomyces cerevisiae of a novel antitumour agent (FCE24517 or Tallimustine) which causes selective alkylations to adenines in the minor groove of DNA. Tallimustine, added to wild-type cells for short periods, reduced the growth rate and increased the percentage of budded cells and delayed the cell cycle in the late S + G2 + M phases. In the rad9 delta null mutant cells, Tallimustine treatment did not affect growth rate and the percentage of budded cells but greatly reduced cell viability compared to isogenic cells. Consistent with a role of RAD9 in inducing a transient delay in G2 phase which preserves cell viability, the potent cytotoxic effect of the drug on rad9 delta cells was alleviated by treatment with nocodazole. Tallimustine was also found to delay the resumption from G1 arrest of wild-type but not of rad9 delta cells. These data indicate that the effects of Tallimustine on cell cycle progression in yeast are mediated by the RAD9 gene product. From our data it appears that yeast could be a valuable model system to study the mode of action of this alkylating drug and of minor groove alkylators in general.

CCAAT-box binding protein NF-Y (CBF, CP1) recognizes the minor groove and distorts DNA.

The CCAAT box is one of the most common promoter elements. The evolutionarily conserved heteromeric factor NF-Y binds this sequence with high affinity and specificity. By comparing the methylation interference patterns of different sites, performing electrophoretic mobility shift assays (EMSA) with IC-substituted oligonucleotides and competition experiments with the minor groove binding (MGB) drugs distamicin A, tallimustine and Hoechst 33258 we show that NF-Y makes key minor groove interactions. Circular permutation assays on four CCAAT boxes, MHC Class II Ea, HSP70, epsilon-globin and MSV, indicate that NF-Y is able to distort the double helix by angles of 62-82 degrees, depending on the site used, and suggest that nucleotides flanking the CCAAT pentanucleotide influence the degree of bending.

Novel sulfonated and phosphonated analogs of distamycin which inhibit the replication of HIV.

A series of novel distamycin-related polyanionic compounds were compared for their anti-HIV activity. Several were highly potent inhibitors of HIV virus-induced cell killing and viral replication of a wide variety of laboratory isolates, as well as a monocytotropic virus and a clinical isolate in human peripheral blood lymphocytes. These compounds are structurally different from other sulfonic acid containing compounds reported to be potent inhibitors of the human immunodeficiency virus (HIV) in two respects: (1) they are structurally related to the non-toxic minor groove DNA binder distamycin; and (2) a number of them contain the aromatic phosphonic acid group. The compounds that were evaluated can be categorized into monomeric or dimeric ureido structural classes incorporating the bisamido-N-methylpyrrolenaphthalene-sulfonic acid group, with differences in the number and position of the sulfonic acids on the naphthalene rings. Broader structure-activity studies were made possible through the synthesis and evaluation of the compounds containing only a single N-methylpyrrole unit, those incorporating the N-methylpyrazole structure, and compounds having the isosteric phosphonic acid group substituted for the sulfonic acid group. One of the most potent of the inhibitors was 2,2'[4,4'[[aminocarbonyl]amino]bis[N,4'-di[pyrrole-2-carboxamide- 1,1'-dimethyl]]-4,6,8 naphthalenetrisulfonic acid] hexasodium salt, NSC 651015. This compound, the phosphonic acid analog NSC 662162, and the monomeric compound NSC 651018 were studied to determine the mechanism of their inhibitory activity. Mechanistic studies revealed that inhibition was due to the disruption of virus attachment to CD(4+)-susceptible cells and a further restraint on fusion of virus and cell membranes. The relative tolerance of these compounds in mice suggests that sufficient antiviral concentrations could be reached in vivo and thus may prove valuable in the treatment of AIDS patients.