Effect of Molecular Interactions on Electron-Transfer and Antioxidant Activity of Bis(alkanol)selenides: A Radiation Chemical Study.

Understanding electron-transfer processes is crucial for developing organoselenium compounds as antioxidants and anti-inflammatory agents. To find new redox-active selenium antioxidants, we have investigated one-electron-transfer reactions between hydroxyl ((.) OH) radical and three bis(alkanol)selenides (SeROH) of varying alkyl chain length, using nanosecond pulse radiolysis. (.) OH radical reacts with SeROH to form radical adduct, which is converted primarily into a dimer radical cation (>Se∴Se<)(+) and α-{bis(hydroxyl alkyl)}-selenomethine radical along with a minor quantity of an intramolecularly stabilized radical cation. Some of these radicals have been subsequently converted to their corresponding selenoxide, and formaldehyde. Estimated yield of these products showed alkyl chain length dependency and correlated well with their antioxidant ability. Quantum chemical calculations suggested that compounds that formed more stable (>Se∴Se<)(+) , produced higher selenoxide and lower formaldehyde. Comparing these results with those for sulfur analogues confirmed for the first time the distinctive role of selenium in making such compounds better antioxidants.

Platinum-Mediated Activation of Coordinated Organonitriles by Telluroethers in Tetrahydrofuran: Isolation, Structural Characterization, and Density Functional Theory Analysis of Intermediate Complexes.

The reactions of [PtCl2(NCR)2] with telluroethers (ArAr'Te) in organic solvents have been investigated. The reactions in dichloromethane yield [PtCl2(TeArAr')2], while those in tetrahydrofuran (THF) give different products depending on the steric demands of the aryl groups on tellurium, the molarity of the reactants, and the reaction conditions. The reactions between [PtCl2(PhCN)2] and TeArAr' in 1:1 molar ratio at room temperature in THF yield several products, like [PtCl2(TeArAr')2] (Ar/Ar' = Ph/Ph, o-tol/Mes, Mes/Mes), [PtCl2(PhCN){NC(O)Ph[TeMes(o-tol)]}], and [PtCl2{NC(O)Ph(TeMes2)}2]. The reaction with TeMes2 in refluxing THF gave [PtCl2{NC(Ph)C4H7O}{NC(O)Ph(TeMes2)}] and [PtCl(TeMes2){Te(Mes)CH2C6H2Me2}], depending on the duration of heating. Reaction of [PtCl2(PhCN)2] with TeArMes afforded [PtCl2(TeArMes)2] (Ar = Ph, o-tol, and Mes), the formation of which decreased with increasing steric demand of the Ar group, together with [PtCl2{NC(O)Ph(TeArMes)}2]. The telluroether in the latter binds to nitrogen, and tellurium exists in the formal oxidation state of +4 (from XPS). The tellurium in these complexes exhibits secondary interactions with platinum (J((195)Pt-(125)Te) = 309-347 Hz) and with the carbonyl oxygen. These complexes slowly dissociate in solution to give [PtCl2(TeMesAr){NC(O)Ph(TeMesAr)}], finally leading to the formation of [PtCl2(TeMesAr)2]. Molecular structures of trans-[PtCl2(PhCN){NC(O)Ph[TeMes(o-tol)]}], trans-[PtCl2{NC(O)Ph(TeMes2)}2], trans-[PtCl2{NC(Ph)C4H7O}{NC(O)Ph(TeMes2)}], trans-[PtCl2{NC(O)Ph[TeMes(o-tol)]}2], trans-[PtCl2(TeMes2){NC(O)Ph(TeMes2)}], trans-[PtCl2{NC(O)Me(TeMes2)}2], and [PtCl(Te-o-tol){NC(O)Ph}2] have been unambiguously established by single-crystal X-ray diffraction analyses. Density functional theory calculations for some of the complexes were performed, and geometrical parameters are in good agreement with the values obtained from X-ray analyses.

Stable selones in glutathione-peroxidase-like catalytic cycle of selenonicotinamide derivative.

Selenonicotinamide, 2,2'-diselenobis[3-amidopyridine] (NictSeSeNict) exhibits glutathione-peroxidase (GPx)-like activity, catalyzing the reduction of hydrogen peroxide (H2O2) by glutathione (GSH). Estimated reactivity parameters for the reaction of selenium species, according to the Dalziel kinetic model, towards GSH (ϕGSH) and H2O2 (ϕH2O2), indicated that the rate constant for the reaction of NictSeSeNict with GSH is higher as compared to that with H2O2, indicating that the activity is initiated by reduction. (77)Se NMR spectroscopy, HPLC analysis, mass spectrometry (MS) and absorption spectroscopy were employed to understand the nature of selenium intermediates responsible for the activity. The (77)Se NMR resonance at 525 ppm due to NictSeSeNict disappeared in the presence of GSH with the initial appearance of signals at δ 364 and 600 ppm, assigned to selone (NictC=Se) and selenenyl sulfide (NictSeSG), respectively. Reaction of H2O2 with NictSeSeNict produced a mixture of selenenic acid (NictSeOH) and seleninic acid (NictSeO2H) with (77)Se NMR resonances appearing at 1069 and 1165 ppm, respectively. Addition of three equivalents of GSH to this mixture produced a characteristic (77)Se NMR signal of NictSeSG. HPLC analysis of the product formed by the reaction of NictSeSeNict with GSH confirmed the formation of NictC=Se absorbing at 375 nm. Stopped-flow kinetic studies with global analysis revealed a bimolecular rate constant of 4.8 ± 0.5 × 10(3) M(-1) s(-1) and 1.7 ± 0.6 × 10(2) M(-1) s(-1) for the formation of NictC=Se produced in two consecutive reactions of NictSeSeNict and NictSeSG with GSH, respectively. Similarly the rate constant for the reaction of NictC=Se with H2O2 was estimated to be 18 ± 1.8 M(-1) s(-1). These studies clearly indicated that the GPx activity of NictSeSeNict is initiated by reduction to form NictSeSG and a stable selone, which is responsible for its efficient GPx activity.

Pulse radiolysis studies of 3,5-dimethyl pyrazole derivatives of selenoethers.

One electron redox reaction of two asymmetric 3,5-dimethyl pyrazole derivatives of selenoethers attached to ethanoic acid (DPSeEA) and propionic acid (DPSePA) were studied by pulse radiolysis technique using transient absorption detection. The reaction of the hydroxyl ((•)OH) radical with DPSeEA or DPSePA at pH 7 produced transients absorbing at 500 nm and at 300 nm, respectively. The absorbance at 500 nm increased with increasing parent concentration indicating formation of dimer radical cations. From the absorbance changes, the equilibrium constants for the formation of dimer radical cation of DPSeEA and DPSePA were estimated as 2020 and 1608 M(-1), respectively. The rate constants at pH 7 for the reaction of the (•)OH radical with DPSeEA and DPSePA were determined to be 9.6 × 10(9) and 1.4 × 10(10) M(-1) s(-1), respectively. The dimer radical cation of DPSeEA and DPSePA decayed by first order kinetics with a rate constant of 2.8 × 10(4) and 5.5 × 10(3) s(-1), respectively. The yield of radical cations of DPSeEA and DPSePA were estimated from the secondary electron transfer reaction, which corresponds to 38% and 48% of (•)OH radical yield, respectively. Some fraction of monomer radical cation undergoes decarboxylation reaction, and the yield of decarboxylation was 25% and 20% for DPSeEA and DPSePA, respectively. These results have implication in understanding their antioxidant activity. The reaction of trichloromethyl peroxyl radical, glutathione, and ascorbic acid further support their antioxidant behavior.

Selenium-containing amino acids are targets for myeloperoxidase-derived hypothiocyanous acid: determination of absolute rate constants and implications for biological damage.

Elevated MPO (myeloperoxidase) levels are associated with multiple human inflammatory pathologies. MPO catalyses the oxidation of Cl-, Br- and SCN- by H2O2 to generate the powerful oxidants hypochlorous acid (HOCl), hypobromous acid (HOBr) and hypothiocyanous acid (HOSCN) respectively. These species are antibacterial agents, but misplaced or excessive production is implicated in tissue damage at sites of inflammation. Unlike HOCl and HOBr, which react with multiple targets, HOSCN targets cysteine residues with considerable selectivity. In the light of this reactivity, we hypothesized that Sec (selenocysteine) residues should also be rapidly oxidized by HOSCN, as selenium atoms are better nucleophiles than sulfur. Such oxidation might inactivate critical Sec-containing cellular protective enzymes such as GPx (glutathione peroxidase) and TrxR (thioredoxin reductase). Stopped-flow kinetic studies indicate that seleno-compounds react rapidly with HOSCN with rate constants, k, in the range 2.8×10(3)-5.8×10(6) M-1·s-1 (for selenomethionine and selenocystamine respectively). These values are ~6000-fold higher than the corresponding values for H2O2, and are also considerably larger than for the reaction of HOSCN with thiols (16-fold for cysteine and 80-fold for selenocystamine). Enzyme studies indicate that GPx and TrxR, but not glutathione reductase, are inactivated by HOSCN in a concentration-dependent manner; k for GPx has been determined as ~5×105 M-1·s-1. Decomposed HOSCN did not induce inactivation. These data indicate that selenocysteine residues are oxidized rapidly by HOSCN, with this resulting in the inhibition of the critical intracellular Sec-dependent protective enzymes GPx and TrxR.

Rare malignant adnexal tumour of the skin involving distal phalanx of right thumb with co-existing primary lung cancer in a 72-year-old patient: A case report.

INTRODUCTION AND IMPORTANCE: Malignant adnexal tumours of the skin are a group of rare malignancies. These tumours can further differentiate into eccrine, apocrine, sebaceous, sweat duct, or ceruminous glands within the skin or follicular cells. Sebaceous carcinoma, a malignant adnexal tumour of the skin, is a rare and malignant tumour of the sebaceous glands. They can occur anywhere in the body where sebaceous glands are present, the most common being the head and neck region. CASE REPORT: Here we report a case of a 72-year-old man who presented with a bleeding ulcer on the distal right thumb, which was progressively increasing in size. Biopsy and histology confirmed the diagnosis of MATS with sebaceous differentiation. He had been diagnosed with metastatic non-small cell lung carcinoma six months back. CLINICAL DISCUSSION AND CONCLUSION: SC is a rare and unusual tumour amounting to less than 1% of all cutaneous malignancies. Phalanges are an infrequent extra-ocular site of involvement, and initial presentation can be mistaken for a benign occurrence. Any patient presenting with extra-ocular SC is advised to undergo genetic and immunohistochemistry testing to rule out complex genetic syndromes like Muir Torre syndrome and Cowden syndrome.

Synthesis, characterization and structures of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives and their probable glutathione peroxidase (GPx) like activity.

A series of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives has been synthesized. The glutathione peroxidase like catalytic activity of these compounds has been studied in a model system, in which reduction of hydrogen peroxide with dithiothreitol (DTT(red)), in the presence of an organoselenium compound was investigated by (1)H NMR spectroscopy. All these compounds exhibit GPx like catalytic activities and the catalytic reaction proceeds through a selenoxide intermediate, identified by (77)Se{(1)H} NMR spectroscopy.

Horseshoe kidney leading to ERCP failure; innovative use of guide wire during laparoscopic CBD exploration: A case report.

INTRODUCTION: Horseshoe kidneys are the most common fusion defect of the kidneys, which amounts to about 0.25% of the population. They are usually asymptomatic and are often identified incidentally. The horseshoe kidney can push the second and third part of the duodenum anteriorly, leading to an altered CBD course. Choledocholithiasis is seen in approximately 10-15% of patients with cholelithiasis. Presently, the most preferred approach for managing CBD stones is ERCP. However, in ERCP failure cases, Laparoscopic CBD exploration is the primary treatment modality, with or without T-tube use, with all the advantages of minimally invasive surgery. CASE PRESENTATION AND DISCUSSION: A 65-year-old female presented with complaints of pain in the right hypochondriac region for three months associated with nausea, jaundice, and loss of appetite and weight. Her USG abdomen showed cholelithiasis with dilated CBD with horseshoe kidney with severe hydronephrosis of the left kidney. They are usually asymptomatic and are often identified incidentally. In this patient, it was believed that the horseshoe kidney had pushed the second and third part of the duodenum anteriorly, leading to an altered CBD course leading to ERCP failure. MRCP confirmed cholelithiasis with choledocholithiasis with dilated CBD of 11.3 mm with horseshoe kidney. ERCP was attempted but was unsuccessful due to non-visualization of the papilla due to overcrowding of duodenal folds. For patients with ERCP failure, laparoscopic CBD exploration is mandatory. For this patient, the CBD was cannulated with a guidewire, if needed, for repeat ERCP and was closed with T-tube in situ. CONCLUSION: There are no particular preoperative indicators that can predict the failure of ERCP. However, in ERCP failure cases, laparoscopic CBD exploration (with or without T-tube use) is the primary treatment modality.

3,3'-Diselenodipropionic acid (DSePA): A redox active multifunctional molecule of biological relevance.

BACKGROUND: Extensive research is being carried out globally to design and develop new selenium compounds for various biological applications such as antioxidants, radio-protectors, anti-carcinogenic agents, biocides, etc. In this pursuit, 3,3'-diselenodipropionic acid (DSePA), a synthetic organoselenium compound, has received considerable attention for its biological activities. SCOPE OF REVIEW: This review intends to give a comprehensive account of research on DSePA so as to facilitate further research activities on this organoselenium compound and to realize its full potential in different areas of biological and pharmacological sciences. MAJOR CONCLUSIONS: It is an interesting diselenide structurally related to selenocystine. It shows moderate glutathione peroxidase (GPx)-like activity and is an excellent scavenger of reactive oxygen species (ROS). Exposure to radiation, as envisaged during radiation therapy, has been associated with normal tissue side effects and also with the decrease in selenium levels in the body. In vitro and in vivo evaluation of DSePA has confirmed its ability to reduce radiation induced side effects into normal tissues. Administration of DSePA through intraperitoneal (IP) or oral route to mice in a dose range of 2 to 2.5 mg/kg body weight has shown survival advantage against whole body irradiation and a significant protection to lung tissue against thoracic irradiation. Pharmacokinetic profiling of DSePA suggests its maximum absorption in the lung. GENERAL SIGNIFICANCE: Research work on DSePA reported in fifteen years or so indicates that it is a promising multifunctional organoselenium compound exhibiting many important activities of biological relevance apart from radioprotection.

Di-tert-butyltin(IV) 2-pyridyl and 4,6-dimethyl-2-pyrimidyl thiolates: versatile single source precursors for the preparation of SnS nanoplatelets as anode material for lithium ion batteries.

New air and moisture stable di-tert-butyltin complexes derived from 2-mercaptopyridine (HSpy), [tBu2Sn(Spy)2], [tBu2Sn(Cl)(Spy)] and 4,6-dimethyl-2-mercaptopyrimidine (HSpymMe2) [tBu2Sn(Cl)(SpymMe2)], have been prepared and utilized as single-source molecular precursors for the preparation of orthorhombic SnS nanoplatelets by a hot injection method and thin films by aerosol assisted chemical vapour deposition (AACVD). The complexes were characterized by NMR (1H, 13C, 119Sn) and elemental analysis and their structures were unambiguously established by the single crystal X-ray diffraction technique. Thermolysis of these complexes in oleylamine (OAm) produced SnS nanoplatelets. The morphologies, elemental compositions, phase purity and crystal structures of the resulting Oam-capped nanoplatelets were determined by electron microscopy (SEM, TEM), energy dispersive X-ray spectroscopy (EDS) and pXRD, while the band gaps of the nanoplatelets were evaluated by diffuse reflectance spectroscopy (DRS) and were blue shifted relative to the bulk material. The morphology and preferential growth of the nanoplatelets were found to be significantly altered by the nature of the molecular precursor employed. The synthesized SnS nanoplatelets were evaluated for their performance as anode material for lithium ion batteries (LIBs). A cell comprised of an SnS electrode could be cycled for 50 cycles. The rate capability of SnS was investigated at different current densities in the range 0.1 to 0.7 A g-1 which revealed that the initial capacity could be regained.

Tellurium(0) as a ligand: synthesis and characterization of 2-pyridyltellurolates of platinum(II) and structures of [Pt{2-Te-3-(R)C5H3N}2Te(PR'3)] (R = H or Me).

Treatment of toluene solutions of the ditellurides [Te(2){C(5)H(3)N(R)-3}(2)] (R = H or Me) with [Pt(PPh(3))(4)] yielded two types of complexes, [Pt{2-Te-3-(R)C(5)H(3)N}(2)(PPh(3))(2)] (1a-d) as the major products and [Pt{2-Te-3-(R)C(5)H(3)N}(2)Te(PPh(3))] (2a-d) as minor products. The above complexes can also be obtained by the reaction of [PtCl(2)(PR'(3))(2)] (PR'(3) = PPh(3) or PPh(2)(2-C(5)H(4)N)) with 2 equiv of Na(2-Te-C(5)H(3)R). The complexes were characterized by elemental analyses and UV-vis, NMR ((1)H and (31)P), and (in part) XPS spectroscopy. The molecular structures of [Pt(2-Te-C(5)H(4)N)(2)Te(PPh(3))] (2a) and [Pt{2-Te-C(5)H(3)(Me)N}(2)Te(PPh(3))] (2b) were established by single crystal X-ray diffraction. Both complexes exhibit a distorted square-planar configuration at the platinum(II) centers. The two mutually trans positioned 2-pyridinetellurolate ligands [2-Te-C(5)H(3)(R)N] coordinate to the central platinum atom in a monodentate fashion through the tellurium atoms. The tellurium(0) atom adopts a "bent T" configuration as it is bridging the 2-Te- C(5)H(3)(R)N molecules via N-Te-N bonds (166 degrees angle) and coordinates to Pt(II) in the trans position to PPh(3). The novel bis(pyridine)tellurium(0) arrangement resembles the bis(pyridine)iodonium structure. The calculated NICS indices and ELF functions clearly show that the compounds 2a and 2b are aromatic in the region defined by the Te-C-N-Te-Pt five-membered rings.

Internally functionalized multifaceted organochalcogen compounds.

Two families of internally functionalized multifaceted organochalcogen compounds based on flexible and rigid backbones, viz., N,N-dimethylaminoalkyl and pyridyl/pryrimidyl groups, have been designed and developed in the author's group. These compounds exhibit remarkable ligand chemistry and often show unprecedented reactivity leading to the formation of several serendipitous products. The presence of both soft (chalcogen) and hard (nitrogen) donor atoms makes them hemilabile ligands which facilitates the design of palladium based homogeneous catalysts for C-C coupling and other related reactions. Pyridyl and pyrimidyl based chalcogenolato complexes of Group 10-15 metals have been successfully employed as molecular precursors for the preparation of metal chalcogenide nano-crystals and for deposition of thin films. By making a suitable choice of chalcogenolate ligands and reaction conditions, a single phasic material can be isolated conveniently. 2-Pyridyl and 2-pyrimidyl ring systems, being important constituents of several biological molecules, several selenium based 2-pyridyl and 2-pyrimidyl compounds show promising GPx mimicking activity. The substituents at the C-3 position play a key role in governing the molecular structure as well as GPx activity.

Synthesis of undoped and manganese-doped hgte nanoparticles using [Hg(TeCH2CH2NMe2)2] as a single source precursor.

The Reaction of [HgCl2(tmeda)] with NaTeCH2CH2NMe2 gave a mercury tellurolate, [Hg(TeCH2CH2. NMe2)2] (1) as a yellow crystalline solid, which was characterized by elemental analysis, UV-vis, mass and NMR (1H, 13C, 125Te, 199Hg) spectroscopy. Thermolysis of 1 in hexadecylamine (HDA) at 90 degrees C in the absence and presence of Mn(OAc)2.4H2O gave undoped and Mn-doped HgTe nanoparticles which were characterized by XRD, EDAX, TEM, EPR and magnetic measurements. These particles could be synthesized with mean particle size of 6-7 nm (from TEM). Manganese substitution at Hg site in HgTe lead to a linear decrease in lattice parameter with increasing concentration of Mn. Magnetization measurements showed ferromagnetic ordering at room temperature with very small coercive field (Hc, 50 Oe) for Hg0.973 Mn0.027 Te sample. This sample also exhibited distinct ferromagnetic resonance (FMR) in the EPR spectrum.

Synthesis and characterization of metal selenide (ZnSe, CdSe, HgSe) nanoparticles.

Thermolysis of [M(SeCH2CH2CH2NMe2)2] (M = Zn, Cd, Hg), prepared by the reactions of sodium salt of 3-(N,N-dimethylamino)propaneselenolate with metal acetates, afforded metal selenides (MSe). The metal selenides were characterized by XRD, EDAX, SEM, AFM, and TEM techniques. Nanoparticles of HgSe were prepared by pyrolysis in a quartz boat, solvothermal, and sonochemical methods. EDAX showed 1:1 Hg/Se ratio, while XRD and SAED patterns confirmed the formation of cubic HgSe. These particles are spherical in nature with an average diameter of 15 nm (from TEM).

Synthesis and characterization of indium xanthates and their use for the preparation of beta-In2S3 nanoparticles.

Synthesis and characterization of various classical indium xanthate complexes of the type [InCl(3-n)(S2COR)n] (n = 1, 2, or 3; R = Me, Et, Pr(i), and Bu(s)) have been discussed. Crystalline beta-ln2S3 nanoparticles were obtained by the solvent thermolysis of indium tris-alkylxanthates in ethylene glycol at 196 degrees C, and were characterized by elemental analysis, IR, powder XRD, and XPS techniques. TEM results showed that the size of beta-In2S3 nanoparticles depended on the nature of the precursor used. The optical properties of beta-In2S3 nanocrystals have shown quantum confinement of the excitonic transition.

Coordination Polymers of Palladium Bridged by Carboxylate and Dimethylaminoalkylselenolate Ligands.

Coordination polymers of palladium stabilized by dimethylaminoalkylselenolate and carboxylate ligands are reported. The reaction of [PdCl(SeCH2 CH2 NMe2 )]3 with AgOTf followed by treatment with sodium acetate afforded [Pd(0) Pd(II) 4 (SeCH2 CH2 NMe2 )3 (OAc)3 ](OTf)2 (1) in which one of the Pd atoms is in the zero oxidation state. In the absence of NaOAc, a tetranuclear complex, [Pd(II) 4 (SeCH2 CH2 NMe2 )4 (OTf)](OTf)3 (2), is isolated from the same reaction. Subsequent treatment with NaO2 CR afforded [Pd4 (SeCH2 CH2 NMe2 )4 (O2 CR)4 ] (R=tBu (3) and Ph (4)). The reaction of [PdCl(SeCH2 CH2 CH2 NMe2 )]2 with AgOTf and NaOAc yielded an ionic binuclear complex, [Pd(II) 2 (SeCH2 CH2 CH2 NMe2 )2 (OAc)](OTf) (5). These complexes have been characterized by NMR spectroscopy, crystal structures, and in some cases by X-ray photoelectron spectroscopy, cyclic voltammetry and mass spectrometry. Complexes 1 and 5 are associated through secondary interactions and coordinate bonds, respectively, to generate polymeric structures in the solid state.

Biodistribution and Pharmacokinetic Study of 3,3' Diseleno Dipropionic Acid (DSePA), A Synthetic Radioprotector, in Mice.

BACKGROUND AND OBJECTIVES: 3,3' Diseleno dipropionic acid (DSePA), a synthetic compound has been shown to have radioprotective activity, especially as a lung radioprotector. In this study, the pharmacokinetics and biodistribution of DSePA in MX-1 tumour bearing SCID mice were evaluated. METHODS: Twenty SCID mice were administered DSePA (50 mg/kg bodyweight) by oral gavage following which four animals each were sacrificed at 15, 30 min, 1, 2 and 4 h. Blood and tissue samples were collected for determination of DSePA concentration by graphite furnace atomic absorption spectrometry (GFAAS) method. The control group (n = 4) was administered sterile water and sacrificed at 4 h. RESULTS: Peak plasma concentration (C max) of 2.7 µg/ml was observed at 15 min which returned to near baseline (baseline = 0.6 µg/ml) at 1 h following drug administration. Biphasic pharmacokinetics characterized by rapid distribution phase and a slower elimination phase were observed. Highest maximal concentration (C max) of the drug was observed in lung (19.2 µg/g at 30 min) followed by intestine (14.64 µg/g at 15 min) and kidney (12.96 µg/g at 15 min). There was negligible uptake in tumor tissue and no uptake in brain. CONCLUSIONS: DSePA has a favorable pharmacokinetic profile which makes it a potentially good candidate for further development as a radioprotective agent.

Endoscopic dacryocystorhinostomy in cases of dacryocystitis due to atrophic rhinitis.

Atrophic rhinitis is a chronic inflammatory disease of the nose, which is more common in India. Chronic dacryocystitis is its rare complication. The authors found four cases of chronic dacryocystitis from March 2002 to October 2003 due to atrophic rhinitis. It was diagnosed clinically by the regurgitation test and lacrimal syringing. These cases were treated conservatively for a period of six weeks to make the nasal mucosa healthier and were then subjected to endoscopic dacryocystorhinostomy (end-DCR) under local anaesthesia. The procedure was found to be more difficult due to bleeding and the healing time was prolonged as compared to other cases of end-DCR. After one to one and half years of follow-up the primary success rate was 75 per cent but after revision surgery in one case, all cases were successful. Hence it was concluded that atrophic rhinitis is no more a contraindication for end-DCR. However, meticulous initial preparation and post-operative follow-up is necessary to improve the result.

Cyclopalladation of telluro ether ligands: synthesis, reactivity and structural characterization.

Treatment of [PdCl2(PhCN)2] with diaryl telluride in 1 : 2 molar ratio gave mononuclear palladium complexes, trans-[PdCl2(TeR2)2] () (R = Mes () (Mes = 2,4,6-trimethylphenyl), Ph (), o-tol () (o-tol = ortho-tolyl)). Reaction of [PdCl2(TeMes2)2] with one equivalent of [PdCl2(PhCN)2] or Na2PdCl4 with TeRR' afforded chloro-bridged binuclear complexes, [Pd2(µ-Cl)2Cl2(TeRR')2] () (R/R' = Mes/Mes (); Mes/Ph (); Ph/Ph ()). A toluene-methanol solution of trans-[PdCl2(TeMes2)2] on refluxing for 30 minutes yielded a binuclear cyclopalladated complex, [Pd2(µ-Cl)2{CH2C6H2(4,6-Me2)TeMes)}2] (). When the refluxing was prolonged, a mononuclear complex cis-[PdCl2{MesTeCH2C6H2(4,6-Me2)TeMes}] () was isolated. Treatment of palladium acetate with TeMes2 afforded an acetato-bridged analogue of , [Pd2(µ-OAc)2{CH2C6H2(4,6-Me2)TeMes}2] () together with a very minor component, a tetranuclear complex, [Pd(µ-OAc)(µ-TeMes)]4 (). This reaction with unsymmetrical tellurides, MesTeR, also gave cyclopalladated complexes [Pd2(µ-OAc)2{CH2C6H2(4,6-Me2)TeR}2] (R = o-tol () and Ph ()) in which 2-methyl of the mesityl group of the telluride was exclusively metallated. The complex trans-[PdCl2(TeMes2)2] on refluxing in xylene gave palladium telluride, Pd7Te3. These complexes were characterized by elemental analyses, IR and NMR ((1)H, (13)C and (125)Te) spectroscopy. The molecular structures of trans-[PdCl2(TeMes2)2] (), [Pd2(µ-Cl)2Cl2(TeMes2)2]·2acetone (·2acetone), cis-[PdCl2{MesTeCH2C6H2(4,6-Me2)TeMes}] (), [Pd2(µ-OAc)2{CH2C6H2(4,6-Me2)TeMes)}2]·toluene (·toluene), [Pd2(µ-OAc)2{CH2C6H2(4,6-Me2)Tetol-o}2] () and [Pd(µ-OAc)(µ-TeMes)]4 () were established by single crystal X-ray diffraction analyses. The mononuclear complex was isolated in two polymorphic forms each with the trans configuration.

Cyto-genotoxicity assessment of potential radioprotector, 3,3'-diselenodipropionic acid (DSePA) in Chinese Hamster Ovary (CHO) cells and human peripheral blood lymphocytes.

Our previous study showed that 3,3'-diselenodipropionic acid (DSePA), a simple, stable, and water-soluble organoselenium exhibiting glutathione peroxidase (GPx)-like activity offered good radioprotection under in vitro and in vivo conditions. Herein, we investigated the anti-genotoxic effect of DSePA in model cellular systems such as Chinese Hamster Ovary (CHO) cell line and human peripheral lymphocytes after exposure to γ-radiation. The measurements on the induction of γ-H2AX foci and micronuclei frequency in the cell nuclei indicated that pretreatment with DSePA significantly prevented the radiation induced DNA damage or genotoxicity and subsequent cytotoxicity without exerting its own toxicity. The maximum protective effect of DSePA was seen at a pre-treatment concentration of 3 µg/ml. The mechanistic investigations in CHO cells revealed that DSePA pretreatment prevented the radiation induced ROS generation, lipid peroxidation and subsequent apoptosis in these cells. Further, it was seen to augment the mRNA expressions of GPx2 significantly and GPx4 marginally without causing much change in the total GPx activity after radiation exposure. These results suggested the roles of GPx2 and GPx4 in DSePA mediated radioprotection. In conclusion our results confirm the nongenotoxic nature of the DSePA and validate its radioprotective efficacy and mechanisms of action in model cellular systems.