Publications by authors named "Konar S"

Introduction: The present study investigates outcomes in patients undergoing elective primary versus revision fusion surgery for lumbar degenerative pathologies with the use of a large population based database.

Methods: A total of 126,044 patients registered in the National Inpatient Sample (NIS) database were identified to have undergone elective fusion of the lumbar spine (primary fusion: 94%; redo fusion: 6%) for degenerative pathologies, between 2002 and 2011. A multivariable logistic regression model was built that adjusted for patient demographics and clinical and hospital characteristics to explore clinical outcomes and postoperative complications.

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Background: Meningiomas of the foramen magnum are among the most challenging of all skull base lesions. Controversies continue regarding the most appropriate approach to this critical anatomic region. The authors report a first case in English literature about twin meningiomas arising from both sides of the ventrolateral dura at the foramen magnum.

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Three isostructural lanthanide-based two- dimensional coordination polymers (CPs) {[Ln2(L)3(H2O)2]n⋅2n CH3OH)⋅2n H2O} (Ln=Gd(3+) (1), Tb(3+) (2), Dy(3+) (3); H2L=cyclobutane-1,1-dicarboxylic acid) were synthesized by using a low molecular weight dicarboxylate ligand and characterized. Single-crystal structure analysis showed that in complexes 1-3 lanthanide centers are connected by μ3-bridging cyclobutanedicarboxylate ligands along the c axis to form a rod-shaped infinite 1D coordination chain, which is further linked with nearby chains by μ4-connected cyclobutanedicarboxylate ligands to form 2D CPs in the bc plane. Viewing the packing of the complexes down the b axis reveals that the lattice methanol molecules are located in the interlayer space between the adjacent 2D layers and form H-bonds with lattice and coordinated water molecules to form 1D chains.

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Herein, the synthesis, structural characterization, magnetic properties and guest binding activities of four Fe(3+) based double-stranded helicates namely; [Fe2(L)2](ClO4)(Cl)·4(CH3OH)·2(H2O) (), [Fe2(L)2](BF4)2·2(H2O) (), [Fe2(L)2](NO3)2·3(CH3OH)·2(H2O) (), and [Fe2(L)2](Cl)2·2(CH3OH)·4(H2O) () are reported. Complexes have been synthesized using the hydrazide-based ligand H2L (H2L = N'1,N'4-bis(2-hydroxybenzylidene)succinohydrazide) and the corresponding Fe(2+) salts. Each of the independent cationic complexes [Fe2(L)2](2+) shows double-stranded helicates from the self-assembly of the ligand and metal ions in a 2 : 2 ratio, where the individual Fe(3+) centre is lying on a C2-axis and the ligand strands wrap around it.

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OBJECT Because of the limited data available regarding the associations between risk factors and the effect of hospital case volume on outcomes after resection of intradural spine tumors, the authors attempted to identify these associations by using a large population-based database. METHODS Using the National Inpatient Sample database, the authors performed a retrospective cohort study that involved patients who underwent surgery for an intradural spinal tumor between 2002 and 2011. Using national estimates, they identified associations of patient demographics, medical comorbidities, and hospital characteristics with inpatient postoperative outcomes.

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Objective: The proximal segment of the anterior cerebral artery (A1) is among the most uncommon locations for occurrence of an intracranial aneurysm. These aneurysms may be missed if small or misinterpreted when they are near the internal cerebral artery bifurcation or Anterior Communicating Artery region. The association with congenital vascular anomalies and multiplicity makes them unique.

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Dr. Ralph Bingham Cloward, an American neurosurgeon, revolutionized the field of modern spine surgery with his lifelong innovative and pioneering contribution. He described the posterior lumbar interbody fusion and anterior cervical discectomy and fusion.

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Low pH in the tumor micromilieu is a recognized pathological feature of cancer. This attribute of cancerous cells has been targeted herein for the controlled release of chemotherapeutics at the tumour site, while sparing healthy tissues. To this end, pH-sensitive, hollow ZnO-nanocarriers loaded with paclitaxel were synthesized and their efficacy studied in breast cancer in vitro and in vivo.

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Robert H. Pudenz was a renowned neurosurgeon in North America in the 20th century, famous for his contributions in the evolution of the shunt valve and ventriculoatrial shunt surgery. With his innovative idea and help from Heyer, in 1955, he demonstrated that a venous catheter worked best when in the right atrium and that the slit valve should be located at the most distal portion of the shunt system to prevent retrograde filling and thrombosis.

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The sufferers of complete androgen insensitivity syndrome (CAIS) are phenotypic females despite of having functional testes and normal male karyotype. They usually present late with primary amenorrhea but delayed diagnosis increases chance of gonadal malignancy. Alertness for this entity is crucial as with early diagnosis such disorder can be managed more appropriately for a better future.

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The increasing prevalence and gloomy socioeconomic consequence of spine injury remain a concern in modern medicine. In this article, we highlight the infamous gunshot spinal injuries of a few eminent personalities across multiple centuries and their sociopolitical impact in context with the evolution of modern medicine. The role of available medicine in these victims was not more than a mere watcher, thus substantiating an infamous quote from ancient literature that describes spine injury as "an ailment not to be treated.

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A Zn(II) based luminescent metal organic framework is synthesized, which acts as a dual functional fluorescent sensor to selectively detect picric acid and palladium(II).

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The reaction of 2,6-bis(1-salicyloylhydrazonoethyl)pyridine [H4daps] with Dy(NO3)3·5H2O led to the formation of two new Dy(III) based complexes with formulae [Dy(H4daps)(H2O)3(NO3)] (NO3)2 (H2O) (1) and [Dy(H3daps)(H2O)2(NO3)] (NO3) (MeOH) (2). Complexes 1 and 2 were characterized by crystal structure determination, magnetic measurements and photoluminescence studies. In comparison with complex , complex 2 shows a slight difference of local symmetry around the Dy(III) center which is attributed to deprotonation of the ligand and also to different binding modes of the peripheral NO3(-) anion.

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Two unprecedented oxonate based 1D coordination polymers with Fe(II) and Co(II) have been synthesized. A detailed magnetic investigation revealed that these complexes are the first oxonate based systems to exhibit spin canted antiferromagnetic ordering at low temperatures. Proton conductivity studies of the complexes showed good proton conduction ability at elevated temperatures and under high humidity conditions.

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We report the proton conduction properties of a 2D flexible MOF and a 1D coordination polymer having the molecular formulas {[Zn(C10H2O8)0.5(C10S2N2H8)]·5H2O]}n (1) and {[Zn(C10H2O8)0.5(C10S2N2H8)]·2H2O]}n (2), respectively.

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Single drug therapies for cancer are often suboptimal and may not provide long term clinical benefits. To overcome this obstacle for effective treatment the applications of two or more drugs are preferable. A limitation of multidrug use is the varying pharmacokinetics of different drugs.

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The synthesis and characterization of two isoreticular metal-organic frameworks (MOFs), {[Cd(bdc)(4-bpmh)]}n⋅2 n(H2O) (1) and {[Cd(2-NH2bdc)(4-bpmh)]}n⋅2 n(H2O) (2) [bdc = benzene dicarboxylic acid; 2-NH2bdc = 2-amino benzene dicarboxylic acid; 4-bpmh = N,N-bis-pyridin-4-ylmethylene-hydrazine], are reported. Both compounds possess similar two-fold interpenetrated 3D frameworks bridged by dicarboxylates and a 4-bpmh linker. The 2D Cd-dicarboxylate layers are extended along the a-axis to form distorted square grids which are further pillared by 4-bpmh linkers to result in a 3D pillared-bilayer interpenetrated framework.

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We present a robust two dimensional coordination polymer, [Ni2(L)2(N(CN)2)2]n (1) (LH = 2-((1-(pyridin-2-yl)ethylimino)methyl)phenol; N(CN)2(-) = dicyanamide ion) using a chiral Schiff base (LH), which shows diastereoselectivity in the structure via a chiral self-discrimination process, ferro- and antiferromagnetic interactions among the metal centers and unusual CO2 uptake behavior as a porous framework.

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Pathogenesis of amyloid-related diseases is related to nonnative folding of proteins with the formation of insoluble deposits in the extracellular space of various tissues. Having the unique properties of small size, large surface area, biodegradability, and relative nontoxicity, magnetic nanoparticles have drawn a lot of attention in biomedical applications. Herein, we demonstrate the effect of bare and differently functionalized magnetic MnFe2O4 nanoparticles on fibrillation of human serum albumin in vitro.

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Two types of heterometallic aggregates of the general formula [(Co(II))3(Co(III))2Ln3(μ3-OH)5(O2C(t)Bu)12(L)2]·2H2O (Ln = Gd(III) (), Dy(III) ()) and [(Co(III))3Ln3(μ3-OH)4(O2C(t)Bu)6(L)3](NO3)2·2CH3CN·2H2O (Ln = Gd(III) (), Dy(III) ()) were successfully isolated in reactions with [Co2(μ-OH2)(O2C(t)Bu)4]·(HO2C(t)Bu)4, Ln(NO3)3 and n-N-butyldiethanolamine (H2L) under ambient conditions by a change in the stoichiometry of the reactants from 1 : 1 : 1 to 1 : 1 : 2 in order. Bond Valence Sum (BVS) calculations and bond lengths indicate the presence of mixed valent Co (Co(II), Co(III)) centres in compounds and and only Co(III) centres in and as required for the charge balances and supported by the magnetic measurements. Isostructural crab shaped complexes and feature distorted cubane cores that edge share to each other whereas the metallic core of or displays hemicubane like arrangement of metal centres and oxygen atoms.

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Since zinc ions (Zn(2+)) are involved in numerous biological phenomena and go through subsequent interactions with zinc-binding proteins, we have attempted a sensitive fluorescence based detection of this second most abundant metal ion using an engineered and synthesized Schiff-base ligand, namely 2,4-bis((Z)-2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)pyrimidine (PyHP). The ligand exhibits a zinc-induced fluorescence response when investigated in a MeOH-buffer (10 mM HEPES, pH = 7) (4 : 1) solvent mixture. The presence of zinc ions (λ(ex) = 410 nm, quantum yield, ϕ = 0.

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We present here a simple, milder, and environmentally benign heterogeneous catalytic method for the transformation of tetrazines to oxadiazole derivatives at room temperature (25 °C) using our earlier synthesized iron-squarate based 3D metal organic framework, [Fe3(OH)3(C4O4)(C4O4)0.5]n (FeSq-MOF).

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The synthesis, crystal structure and magnetic properties of four polynuclear lanthanide coordination complexes having molecular formulae, [Gd3(2)(1)L(H2O)8(Cl)](Cl)4·10H2O (1), [Dy3L(2)(1)(H2O)9](Cl)5·6H2O (2) [Gd6L(2)(2)(HCO2)4(μ3-OH)4(DMF)6(H2O)2](Cl)2·4H2O (3) and [Dy6L(2)(2)(HCO2)4(μ3-OH)4(DMF)6(H2O)2](Cl)2·4H2O (4) (where H2L(1) = bis[(2-pyridyl)methylene]pyridine-2,6-dicarbohydrazide and H4L(2) = bis[2-hydroxy-benzylidene]pyridine-2,6-dicarbohydrazide) are reported. Structural investigation by X-ray crystallography reveals similar structural features for complexes 1 and 2 and they exhibit butterfly like shapes of the molecules. Non-covalent interactions between the molecules create double helical arrangements for both molecules.

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Two isostructural lanthanide-based 3D coordination networks [Ln = Gd(3+) (1), Dy(3+)(2)] with densely packed distorted cuboid nanoscopic cages are reported for the first time. Magnetic characterization reveals that complex 1 shows a significant cryogenic magnetocaloric effect (-ΔSm = 44 J kg(-1) K(-1)), whereas 2 shows slow relaxation of magnetization.

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