Publications by authors named "Yousef Najajreh"

Introduction - The obesity pandemic is multifactorial. Nutritional, pharmacologic and surgical interventions are limited in reach and efficacy, raising need for new therapeutics. Aims - Characterization of anorexigenic and cognitive effect and central mechanism of action of novel N-acylethanolamide derivatives.

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CD5 is expressed on T cells and a subset of B cells (B1a). It can attenuate TCR signalling and impair CTL activation and is a therapeutic targetable tumour antigen expressed on leukemic T and B cells. However, the potential therapeutic effect of functionally blocking CD5 to increase T cell anti-tumour activity against tumours (including solid tumours) has not been explored.

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Background: Platinum-based drugs are used as cancer chemotherapeutics for the last 40 years. However, drug resistance and nephrotoxicity are the major limitations of the use of platinum-based compounds in cancer therapy. Platinum (IV) complexes are believed to act as platinum prodrugs and are able to overcome some of platinum (II) limitations.

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Newly synthesized acylethanolamide derivatives oleoyl-L-valinolamide (1), oleoyl-D-valinolamide (2), elaidoyl-L-valinolamide (3), elaidoyl-D-valinolamide (4) stearoyl-L-valinolamide (5), and palmitoyl-L-valinolamide (6) were investigated in mice as antiobesity compounds. Compounds 1, 2, 5, 6 significantly decreased body weight by 6.57% following eight injections of 1 mg/kg i.

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Facile strategies were developed for the versatile functionalization of platinum(IV) axial sites, allowing for easy accessibility to unsymmetric mono- and mixed-carboxylato, as well as symmetric di-substituted platinum(IV) complexes. The first method involves the direct oxidation and carboxylation of the platinum(II) center using an appropriate peroxide and the carboxylate of choice to firstly yield a monocarboxylato monohydroxido platinum(IV) complex. This platinum(IV) intermediate can undergo further carboxylation to give rise to a mixed-carboxylato platinum(IV) complex.

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Chronic myeloid leukemia (CML) is characterized by the presence of p210(Bcr-Abl) which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors have been successfully established for the treatment of CML. Despite high rates of clinical response, CML patients can develop resistance against these kinase inhibitors mainly due to point mutations within the Abl protein kinase domain.

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Background: Philadelphia positive leukemias are characterized by the presence of Bcr-Abl fusion protein which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors have been successfully established for the treatment of Ph (+) leukemias. Despite high rates of clinical response, Ph (+) patients can develop resistance against these kinase inhibitors mainly due to point mutations within the Abl protein.

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Background: Chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive (Ph+) acute lymphatic leukemia (Ph + ALL) are caused by the t(9;22), which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase "escapes" the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs) Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia.

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Background: The t(9;22) translocation leads to the formation of the chimeric breakpoint cluster region/c-abl oncogene 1 (BCR/ABL) fusion gene on der22, the Philadelphia chromosome. The p185(BCR/ABL) or the p210(BCR/ABL) fusion proteins are encoded as a result of the translocation, depending on whether a "minor" or "major" breakpoint occurs, respectively. Both p185(BCR/ABL) and p210(BCR/ABL) exhibit constitutively activated ABL kinase activity.

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The hallmark of chronic myeloid leukemia (CML) is the abnormal activity of p210(Bcr-Abl) kinase. Selective kinase inhibitors such as imatinib or nilotinib have been established successfully for the treatment of CML. Despite high rates of clinical response, CML patients can develop resistance to these kinase inhibitors mainly due to point mutations within the Abl kinase domain of the fusion protein.

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A new tetrafunctional dinuclear platinum complex trans,trans-[{PtCl2(NH3)}2(piperazine)] with sterically rigid linking group was designed, synthesized and characterized. In this novel molecule, the DNA-binding features of two classes of the platinum compounds with proven antitumor activity are combined, namely trans oriented bifunctional mononuclear platinum complexes with a heterocyclic ligand and polynuclear platinum complexes. DNA-binding mode of this new complex was analyzed by various methods of molecular biology and biophysics.

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The ability of low-frequency ultrasound (LFUS) to release encapsulated drugs from sterically stabilized liposomes in a controlled manner was demonstrated. Three liposomal formulations having identical lipid bilayer compositions and a similar size ( approximately 100 nm) but differing in their encapsulated drugs and methods of drug loading have been tested. Two of the drugs, doxorubicin and methylpredinisolone hemisuccinate, were remote loaded by transmembrane gradients (ammonium sulfate and calcium acetate, respectively).

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The determination of the structures and DNA interactions and the reactions with GSH and ubiquitin of complexes of the general formula trans-[PtCl2(Am)(pip-pip)] x HCl, where pip-pip is 4-piperidinopiperidine and Am is NH3, methylamine (MA), dimethylamine (DMA), n-propylamine (NPA), isopropylamine (IPA), n-butylamine (NBA), or cyclohexylamine (CHA), were performed. X-ray structures and NMR studies of the NH3 and MA complexes showed that both pip rings were in the chair conformation and that the second pip ring is fluxional. The DNA binding studies showed that these complexes bind to calf thymus DNA nearly an order of magnitude more quickly than cisplatin and form covalent adducts that stabilize the double helix.

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A series of complexes of the general formula trans-[PtCl2(Am)(pip-pip)] x HCl where pip-pip is 4-piperidinopiperidine and Am is NH3, methylamine (MA), dimethylamine (DMA), n-propylamine (NPA), isopropylamine (IPA), n-butylamine (NBA), or cyclohexylamine (CHA) were prepared and characterized, and their cytotoxic properties against ovarian and colon cancer cells were evaluated. The trans-[PtCl2(NH3)(pip-pip)] x HCl was significantly more potent than cisplatin in all the cisplatin-resistant ovarian cancer cell lines and was nearly as cytotoxic as cisplatin against colon cancer cells. In vivo studies in mice showed that the pip-pip complexes are significantly less toxic than cisplatin.

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trans-Diaminedicholoroplatinum(II) complexes with one planar and one non-planar heterocyclic amine ligand were designed as new potential antitumor drugs. The X-ray crystallographic structures of trans-[PtCl2(4-picoline)(piperidine)] and trans-[PtCl2(4-picoline)(piperazine)].HCl revealed that the piperidine and piperazine ligands bind to the platinum through the equatorial position and that the ligands adopt the chair conformation.

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Three isomeric complexes, trans-[PtCl2(NH3)(2-methylpiperidine)], trans-[PtCl2(NH3)(3-methylpiperidine)] and trans-[PtCl2(NH3)(4-methylpiperidine)], were prepared and their cytotoxicities against six ovarian cancer cell lines, three sensitive and three resistant to cisplatin, were measured. There were no significant differences in the cytotoxicities of the three isomers against these cell lines. The interactions of the three complexes with reduced glutathione (GSH) and with ubiquitin (Ub), as a model protein, were studied.

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We have evaluated the cytotoxic properties against the protozoan Leishmania infantum of four water soluble cationic trans-Pt(II)Cl(2) compounds containing as inert groups NH3 and piperazine (1), 4-picoline and piperazine (2), n-butylamine and piperazine (3), and NH3 and 4-piperidino-piperidine (4). The leishmanicidal activity of compounds 3 and 4 against promastigotes of the parasite Leishmania infantum was 2.5- and 1.

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MDA-MB-231 human breast cancer cells transfected with GFP were used as model to determine the reduction in proliferation, colony formation, and migration in response to agents with anti-metastatic properties. These agents consisted of antisense oligonucleotides (ASOs) directed against osteopontin (OPN), bone sialoprotein II (BSP II), and osteonectin (ON), as well as an antibody directed against BSP II. A bisphosphonate derivative (ibandronate) and an alkylphosphocholine (erucylphospho-NNN-trimethylpropanolamine; ErPC3) were used as positive controls.

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Replacement of the ammine group in antitumor cisplatin by a heterocyclic ligand (piperidine, piperazine, or 4-picoline) results in reduction of cytotoxicity in human ovarian cancer cells. DNA is generally believed to be a major pharmacological target of antitumor platinum complexes. Therefore, we examined conformation of oligodeoxyribonucleotide duplexes containing a cross-link of cis-[PtCl(2)(NH(3))(piperidine)], their recognition by high mobility group proteins, and nucleotide excision repair; that is, some of the processes that may mediate antitumor effects of platinum drugs.

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A paradigm for the structure-pharmacological activity relationship of bifunctional platinum antitumor drugs is that the trans isomer of antitumor cisplatin (transplatin) is clinically ineffective. To this end, however, several new complexes of the trans structure have been identified that exhibit cytotoxicity in tumor cells that is even better than that of the analogous cis isomers. We reported recently (Kasparkova, J.

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The global modification of mammalian and plasmid DNAs by novel platinum compounds, cis- or trans-[PtCl(2)(NH(3))(Am)], where Am = NH(3), nonplanar heterocycle piperidine, piperazine, or aromatic planar heterocycle 4-picoline, was investigated in cell-free media using various biochemical and biophysical methods. These modifications have been compared with the activity of these new compounds in several tumor cell lines including those resistant to antitumor cis-diamminedichloroplatinum(II) (cisplatin). The results show that the replacement of the NH(3) group in cisplatin by the heterocyclic ligands does not considerably affect the DNA binding mode of this drug.

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As part of a systematic study of the basic principles that govern the formation and reactivity of Pt-protein adducts, we report the effect of substituting the amine ligand of cis- and trans-[PtCl(2)(NH(3))(2)] complexes with bulkier planar aromatic or nonplanar cyclic amine ligands on the binding properties of the complexes to ubiquitin and to horse heart myoglobin. The ligand replacement had a different effect on the cis or trans isomers investigated. In the cis-Pt complexes, replacing one or both amine ligands by piperidine or 4-picoline dramatically decreased the binding of the complexes to the proteins studied, whereas in the substituted trans-Pt complexes replacement of the amine by a piperidine or 4-picoline increased the binding rate.

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The synthesis, chemical characterization, and interaction with cells of new sterically hindered trans- and cis-diaminedichloroplatinum(II) complexes are described. The amine ligands include monofunctional piperidine (pip) and piperazine (pz). The poor solubility of trans-diaminedichloroplatinum complexes was overcome by introducing the positively charged pz ligand, which allows retaining of the classic platinum coordination sphere.

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