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Unique Example (unique + example)
Selected AbstractsMagnetic and Electrochemical Properties of a Heterobridged ,-Phenoxido,,1,1 -Azide Dinickel(II) Compound: A Unique Example Demonstrating the Bridge Distance Dependency of Exchange IntegralEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2009Rajesh Koner Abstract The synthesis, structure, magnetic and electrochemical properties of the heterobridged ,-phenoxido,,1,1 -azide dinickel(II) compound [NiII2(HL1)3(,1,1 -N3)]·3H2O (1) derived from the tetradentate Schiff base ligand N -(2-hydroxyethyl)-3-methoxysalicylaldimine (H2L1) are described. The title compound crystallizes in the triclinic system (space group P). Electrochemical analyses reveal that compound 1 exhibits two-step quasireversible couples in the reduction window with E1/2 values of ,1412 and ,1762 mV. The variable-temperature (2,300 K) magnetic susceptibilities at 1 T of the title compound were measured. The interaction between the metal centres is weak ferromagnetic (J = 5.0 cm,1, g = 2.23, D1 = 29.2 cm,1 and D2 = 10.7 cm,1). Comparison of the exchange integral of 1 with that of the only reported ,-phenoxido,,1,1 -azide dinickel(II) compound results in the emergence of a unique example of the dependence of strength of magnetic exchange interaction on the metal,ligand bridge distance. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Genetics of dermatofibrosarcoma protuberans family of tumors: From ring chromosomes to tyrosine kinase inhibitor treatmentGENES, CHROMOSOMES AND CANCER, Issue 1 2003Nicolas Sirvent Dermatofibrosarcoma protuberans (DP) is a rare, slow-growing, infiltrating dermal neoplasm of intermediate malignancy, made up of spindle-shaped tumor cells often positive for CD34. The preferred treatment is wide surgical excision with pathologically negative margins. At the cytogenetic level, DP cells are characterized by either supernumerary ring chromosomes, which have been shown by using fluorescence in situ hybridization techniques to be derived from chromosome 22 and to contain low-level amplified sequences from 17q22-qter and 22q10,q13.1, or t(17;22), that are most often unbalanced. Both the rings and linear der(22) contain a specific fusion of COL1A1 with PDGFB. Similar to other tumors, the COL1A1-PDGFB fusion is occasionally cryptic, associated with complex chromosomal rearrangements. Although rings have been mainly observed in adults, translocations have been reported in all pediatric cases. DP is therefore a unique example of a tumor in which (i) the same molecular event occurs either on rings or linear translocation derivatives, (ii) the chromosomal abnormalities display an age-related pattern, and (iii) the presence of the specific fusion gene is associated with the gain of chromosomal segments, probably taking advantage of gene dosage effects. In all DP cases that underwent molecular investigations, the breakpoint localization in PDGFB was found to be remarkably constant, placing exon 2 under the control of the COL1A1 promoter. In contrast, the COL1A1 breakpoint was found to be variably located within the exons of the ,-helical coding region (exons 6,49). No preferential COL1A1 breakpoint and no correlation between the breakpoint location and the age of the patient or any clinical or histological particularity have been described. The COL1A1-PDGFB fusion is detectable by multiplex RT-PCR with a combination of forward primers designed from a variety of COL1A1 exons and one reverse primer from PDGFB exon 2. Recent studies have determined the molecular identity of "classical" DP, giant cell fibroblastoma, Bednar tumor, adult superficial fibrosarcoma, and the granular cell variant of DP. In approximately 8% of DP cases, the COL1A1-PDGFB fusion is not found, suggesting that genes other than COL1A1 or PDGFB might be involved in a subset of cases. It has been proposed that PDGFB acts as a mitogen in DP cells by autocrine stimulation of the PDGF receptor. It is encouraging that inhibitory effects of the PDGF receptor tyrosine kinase antagonist imatinib mesylate have been demonstrated in vivo; such targeted therapies might be warranted in the near future for treatment of the few DP cases not manageable by surgery. © 2003 Wiley-Liss, Inc. [source] Matrix dependence of blue light emission from a novel NH2 -functionalized dicyanoquinodimethane derivativeJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 3 2006Marek Szablewski Abstract The reactions of primary and secondary amines with (cyclohexa-2,5-diene-1,4-diylidene)-dimalononitrile (TCNQ) lead to mono- and disubstituted dicyanoquinodimethane derivatives and fluorescence emission has been observed for several of these compounds. We report the luminescence properties, synthesis and crystal structure of the novel dicyanoquinodimethane derivative 2-{4-[amino-(2,6-dimethyl-morpholin-4-yl)-methylene]-cyclohexa-2,5- dienylidene}-malononitrile (Ammor), a unique example of an asymmetric dicyanoquinodimethane derivative in which one of the nitrile groups has been replaced with an NH2 moiety, which provides a reactive centre for potential further substitution or tethering to larger molecules or polymers. The luminescence properties of the title compound were investigated in a variety of environments, including alcohol solutions at room temperature and a glass-forming solvent at low temperature. The fluorescence quantum yields and Stokes' shifts of the blue emission were found to be very sensitive to the matrix. The crystal structure of the subject compound was determined, revealing that the molecules are non-planar in the ground state. The environmentally sensitive emission is discussed in terms of the conformational change during photoexcitation and the constraint imposed on this by the matrix. This behaviour is also compared with that of other related amino-functionalized dicyanoquinodimethane derivatives. Copyright © 2006 John Wiley & Sons, Ltd. [source] Implementing and sustaining science curriculum reform: A study of leadership practices among teachers within a high school science departmentJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 7 2009Douglas B. Larkin Abstract This study presents a description and analysis of a ninth-grade integrated science curriculum developed and implemented by teachers within a high school science department and subsequently sustained for over 25 years. The Integrated Science Program (ISP) at Lakeside Southwest High School depicted here offers a unique example of longitudinal science education reform. In this study, we examined ISP as an artifact of teacher leadership. Findings affirmed the importance of shared philosophical purpose among teachers, attention to public perceptions, staff stability, the distribution of responsibilities, and instructional coherence. This study also demonstrated how curricular reforms might change over time in response to contextual pressures as was the case with the equity challenges faced by the current teachers of ISP. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 813,835, 2009 [source] Malignant solitary fibrous tumor arising from the pineal region: case study and literature reviewNEUROPATHOLOGY, Issue 3 2010Jing Zhang We report a case of malignant solitary fibrous tumor involving the pineal region in a 49-year-old woman. The patient presented with headache, slowly progressive weakness of the right lower extremities and upgaze palsy over the past year. Histologically, the tumor was composed of moderately hypercellular proliferated spindle cells with eosinophilic collagen bands. These cells were diffusely and strongly immunoreactive with CD34, CD99, and vimentin, but were negative with epithelial membrane antigen, S-100 protein, Bcl-2, smooth muscle actin, cytokeratin and glial fibrillary antigenic protein. MIB-1 labeling indices and mitosis rates were 7.3 ± 1.8% and 5 per 10 high power fields, respectively. Ultrastructural examination revealed that the neoplastic cells had features of fibroblastic differentiation. Differential diagnoses included fibrous meningioma and hemangiopericytoma. The present case provides one unique example of a rare entity to the already diverse spectrum of the pineal region neoplasms encountered in neuropathology. [source] OC7 Trigeminal neuropathy and autonomic neuropathy , a rare combinationORAL DISEASES, Issue 2006C Frezzini Introduction, Idiopathic trigeminal neuropathy is an uncommon orofacial symptom giving rise to paraesthesia and/or anaesthesia of one or more divisions of the trigeminal nerve in the absence of an obvious aetiology. Idiopathic autonomic neuropathy is a rare disorder giving rise to cholinergic and/or adrenergic dysfunction of the autonomic nervous system. The combination of trigeminal and autonomic neuropathy in the absence of diabetes mellitus is unusual. Signs and symptoms, A 45-year-old male was referred to the Oral Medicine Unit of UCL Eastman Dental Institute and UCLHT Eastman Dental Hospital for assessment of possible xerostomia secondary to autonomic neuropathy. Medical history & social history. The patient had long-standing trigeminal neuropathy, long-standing autonomic neuropathy giving rise to dysphagia, gastrointestinal and bladder function and orthostatic hypotension. There was a previous history of Hodgkin's disease. Oral disease history, Clinical examination revealed neurotrophic destruction of the nasal septum (trigeminal trophic syndrome), chronic periodontitis, but no features of long-standing xerostomia. Resting sialometry was >0.1 ml min,1. Diagnosis, Trigeminal trophic syndrome secondary to trigeminal neuropathy and partial autonomic neuropathy. Treatment, The patient was referred for appropriate periodontal therapy. Conclusion, This is a unique example of trigeminal sensory neuropathy and autonomic neuropathy in the absence of diabetes mellitus. Early diagnosis of both disorders is important to ensure avoidance of facial complications such as trigeminal trophic syndrome and the oral consequences of long-standing xerostomia. [source] Intracellular parasitism with Toxoplasma gondii stimulates mammalian-target-of-rapamycin-dependent host cell growth despite impaired signalling to S6K1 and 4E-BP1CELLULAR MICROBIOLOGY, Issue 6 2009Yubao Wang Summary The Ser/Thr kinase mammalian-target-of-rapamycin (mTOR) is a central regulator of anabolism, growth and proliferation. We investigated the effects of Toxoplasma gondii on host mTOR signalling. Toxoplasma invasion of multiple cell types rapidly induced sustained mTOR activation that was restricted to infected cells, as determined by rapamycin-sensitive phosphorylation of ribosomal protein S6; however, phosphorylation of the growth-associated mTOR substrates 4E-BP1 and S6K1 was not detected. Infected cells still phosphorylated S6K1 and 4E-BP1 in response to insulin, although the S6K1 response was blunted. Parasite-induced S6 phosphorylation was independent of S6K1 and did not require activation of canonical mTOR-inducing pathways mediated by phosphatidylinositol 3-kinase,Akt and ERK. Host mTOR was localized in a vesicular pattern surrounding the parasitophorous vacuole, suggesting potential activation by phosphatidic acid in the vacuolar membrane. In spite of a failure to phosphorylate 4E-BP1 and S6K1, intracellular T. gondii triggered host cell cycle progression in an mTOR-dependent manner and progression of infected cells displayed increased sensitivity to rapamycin. Moreover, normal cell growth was maintained during parasite-induced cell cycle progression, as indicated by total cellular S6 levels. The Toxoplasma -infected cell provides a unique example of non-canonical mTOR activation supporting growth that is independent of signalling through either S6K1 or 4E-BP1. [source] Recurring main-chain anion-binding motifs in short polypeptides: nestsACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2004E. James Milner-White A novel tripeptide motif called a nest has recently been described in proteins with the function of binding anionic, or partially anionic, atoms such as carbonyl O atoms. In the present work, a search for nests in small polypeptides stored in the Cambridge Structural Database is reported. 37 unique examples were found: over half form part of hydrogen-bond arrangements resembling those in proteins, such as Schellman/paperclip loop motifs, various types of ,-turn and Asx-turns or Ser/Thr-turns, while a third are in novel situations, some involving binding to anionic groups from other molecules within the crystal complex. An example is the antibiotic vancomycin, which incorporates a prominent nest forming part of a peptide-binding site. This nest binds the carboxylate of the C-terminal d -alanine of the bacterial cell-wall precursor peptide, thereby inhibiting the final step of bacterial cell-wall synthesis. As in proteins, a number of nests occur in short peptides with an alternating glycine/l -amino-acid sequence but, uniquely to non-ribosomally synthesized short peptides, several nests within them are constructed from alternating d - and l -amino acids, and such sequences seem to specially favour nests. [source] | |||||||||||||