Design and characterization of a binary CT complex of imidazole-oxyresveratrol: exploring its pharmacological and computational aspects

A new binary charge transfer (CT) complex between imidazole (IMZ) and oxyresveratrol (OXA) was synthesized and characterized experimentally and theoretically. The experimental work was carried out in solution and solid state in selected solvents such as chloroform (CHL), methanol (Me-OH), ethanol (Et-OH), and acetonitrile (AN). The newly synthesized CT complex (D1) has been characterized by various techniques such as UV-visible spectroscopy, FTIR, 1H-NMR, and powder-XRD. The 1:1 composition of D1 is confirmed by Jobs' method of continuous variation and spectrophotometric (at λmax 554 nm) methods at 298 K. The infrared spectra of D1 confirmed the existence of proton transfer hydrogen bond beside charge transfer interaction. These findings indicate that the cation and anion are joined together by the weak hydrogen bonding as N+-H-O-. Reactivity parameters strongly recommended that IMZ behaves as a good electron donor and OXA an efficient electron acceptor. Density functional theory (DFT) computations with basis set B3LYP/6-31G (d,p) was applied to support the experimental results. TD-DFT calculations gives HOMO (-5.12 eV) → LUMO (-1.14 eV) electronic energy gap (Δ E ) to be 3.80 eV. The bioorganic chemistry of D1 was well established after antioxidant, antimicrobial, and toxicity screening in Wistar rat. The type of interactions between HSA and D1 at the molecular level was studied through fluorescence spectroscopy. Binding constant along with the type of quenching mechanism, was investigated through the Stern-Volmer equation. Molecular docking demonstrated that D1 binds perfectly with human serum albumin and EGFR (1M17) and exposes free energy of binding (FEB) values of -295.2 and -283.3 kcal/mol, respectively. The D1 fits successfully into the minor groove of HAS and 1M17, the results of molecular docking show that the D1 binds perfectly with the HAS and 1M17, the higher value of binding energy shows stronger interaction between HAS and 1M17 with D1. Our synthesized complex shows good binding results with HAS compared to 1M17.Communicated by Ramaswamy H. Sarma.

Design, synthesis, characterizing and DFT calculations of a binary CT complex co-crystal of bioactive moieties in different polar solvents to investigate its pharmacological activity

Imidazole (IM) and salicylic acid (SA) have a significant class among the medical compound. These are widely used as topical drugs like antifungal, antibacterial, anticancer, immunosuppressive agent, etc. These two bioactive organic moieties are combined by a weak hydrogen bond formed by hydrogen transfer. The charge transfer (CT) complex of acceptor (SA) and donor (IM), has been synthesized at room temperature in methanol and confirmed by signal-crystal XRD, conductance and UV-visible spectroscopy. The X-ray crystallography provides the original structural information of CT complex and displays the existence of N+-H--O- bond between IM and SA. The physical properties such as (ECT), (RN), (ID), (f), (D) and (Δ G0) along with molar extinction coefficient (εCT) and formation constant (KCT) were estimated through UV-visible spectroscopy. Job's method and Benesi-Hildebrand equation suggested 1:1 stoichiometry of ([IM]+[SA]-). The results indicate a complete transfer of hydrogen atom and CT complex formation with 1:1 molar ratio of IM and SA. Antimicrobial activity was veiled against different bacteria like Escherichia coli, Bacillus subtilis and Staphylococcus aureus; and different fungi as Fusarium oxysporum, Candida albicans and Aspergillus niger by disc diffusion method. CT complex was also tested for cytotoxic activity against lung cancer cell lines in comparison to breast cancer cell lines. Molecular docking provides the information of binding of [(IM)+(SA)-] with the cancer marker (1M17), which has substantial application for drug designing. The investigational studies were supplemented through time-dependent density functional theory (TD-DFT) using basis set B3LYP/6-311G**. Through DFT calculations, HOMO→LUMO electronic energy gap (Δ E ) was obtained.

Protective effect of the newly synthesized and characterized charge transfer (CT) complex against arecoline induced toxicity in third-instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg9: experimental and theoretical mechanistic insights

Agents that suppress the toxic effect of arecoline (a chemical present in the Areca nut fruit) have become a need of the hour owing to its several harmful effects on human beings. Although some drug molecules have been developed for this purpose, yet, simple, easy to prepare, and economical molecules with remarkable potency are still a challenge to design. The present work thus becomes important as it involves the synthesis of a new charge transfer complex (CTC) material, which has, for the first time, been screened to investigate its effect on the toxic effects of arecoline. The newly designed material (CL), which is generated from the reaction between 2,4,6-trinitrophenol (TNP) and pyrazole (PYZ), has been crystallized by a slow evaporation method and characterized by employing spectral studies including single crystal X-ray crystallography. Spectrophotometry studies with the inclusion of the Benesi-Hildebrand equation reveal 1 : 1 stoichiometry and physical parameters of CL. Assays were used for determining the protective effect of CL against arecoline. CL was found to (dose-dependently) decrease β-galactosidase activity, damage in tissue and DNA damage caused by arecoline (80 μM) in the third-instar larvae of the transgenic Drosophila melanogaster (hsp70-lacZ)Bg⁹. The possible mechanism of this effect was explored through fluorescence and UV-vis spectroscopy. The possibility of suppression of arecoline action on the muscarinic acetylcholine receptor 1-G11 protein complex (found in the cell membrane) in the presence of CL was studied theoretically by molecular docking. Density functional theory (DFT) also theoretically supported various aspects of the designed material concerning the energy profile of the orbitals (HOMO-LUMO) as well as the energy minimized structure. Furthermore, time dependent (TD) DFT corroborated the electronic properties of the designed material.

Biochemical and histopathological analysis after sub-chronic administration of oxyresveratrol in Wistar rats

Oxyresveratrol (OXY) is a naturally occurring phenolic compound; however, there are no toxicity studies reported on its long term use. The aim of our work was to demonstrate the evaluation of acute and sub-chronic toxicity of oxyresveratrol in rats to assess its safety profile. To evaluate the LD₅₀ value, 2000 mg/kg of oxyresveratrol was administered to Wistar rats by oral gavage. For sub-chronic toxicity assessment, 80 Wistar rats were randomly divided into four groups (10 animal/sex/group) and oxyresveratrol administered at a dose of 50, 100, 150 mg/kg/day by oral gavage. Bodyweight, food, and water consumption were monitored every week. At the end of the experiments, biochemical and hematological parameters were analyzed. Gross and microscopic organ analyses were also carried out. LD₅₀ of oxyresveratrol was greater than 2000 mg/kg sub-chronic administration of oxyresveratrol did not influence any mortality. Doses of 50 and 100 mg/kg of oxyresveratrol did not produce any sign of toxicity. However, the 150 mg/kg oxyresveratrol group depicted changes in multiple biochemical and hematological parameters with changes in the pathology of cardiac, hepatic, and renal tissues when compared with control. Therefore, no observed adverse effect level (NOAEL) of oxyresveratrol was observed to be 100 mg/kg per day for both male and female rats.

Synthesis, spectroscopic characterization, antimicrobial activity, molecular docking and DFT studies of proton transfer (H-bonded) complex of 8-aminoquinoline (donor) with chloranilic acid (acceptor)

The proton transfer complex has been synthesized by mixing 1:1 ratio of 8-aminoquinoline (donor) and chloranilic acid (acceptor) in methanol. FTIR, ¹³C NMR, ¹H NMR, Powder XRD and UV-visible studies confirmed the formation of the newly synthesized compound. These methods ascertain that cations and anions combine to form weak hydrogen bonds as N⁺-H----O^-. The physical properties such as energy of interaction (E_CT), resonating energy (R_N), Ionization potential (I_D), and oscillator strength (f), transition dipole strength (D) and free energy (Δ G) were estimated through UV-visible spectroscopy. The thermal stability of this complex and extensive erosion was analyzed by TGA/DTA study. Benesi-Hildebrand equation was used to determine 1:1 stoichiometry of this complex and to calculate the molar extinction coefficient (ε_CT), the formation constant (K_CT) and other physical parameters. The nature of transfer of charge relations plays a vital role in chemistry and in biological systems. The synthesized proton transfer complex has been screened for antibacterial activities against different bacteria and antifungal activities against different fungi. The proton transfer complex also displays outstanding interaction with the human protein (globulin) protein. The DFT calculations by B3LYP/6-311G** basis set gave theoretical establishment and HOMO (-5.468 eV) to LUMO (-3.328 eV) electronic energy gap (ΔE) as 2.140 eV. Theoretical analysis proves the biological characteristics as well. Molecular docking displays that CT complex is fully bound to the protein and determines the free binding energy value of -290.18 kcal/mol (FEB).A new organic charge transfer complex has been prepared, characterized and explored for antibacterial, antifungal and protein binding properties. The experimental results are supported by theoretical analysis.Communicated by Ramaswamy H. Sarma.

Charge transfer complexes: Emerging and promising colorimetric real-time chemosensors for hazardous materials

After introducing the concept of charge transfer (CT) complex formation by Mulliken and the discovery of crystalline picrate (association of picric acid and aromatic hydrocarbons) by Fritzsches, a large interest has been drawn in this field. CT complexes have been explored and exploited for different applications for several decades. The research has been aimed mostly for discovering and characterizing new CT materials and exploring applications mainly in the field of optoelectronic properties, antimicrobial activities and DNA/protein binding properties for the last six years. However, nowadays, CT complexes are exploited for their photocatalytic activities and designing chemosensors for the colorimetric real-time detection of hazardous materials like nitro explosives, anions and toxic heavy metal ions in an aqueous medium. This review sheds light on updates on CT complexes, their types, synthesis and applications. The brief discussion on the emergence of CT complexes as highly potential chemosensors along with the explanation of sensing mechanism through article summarization is the centerpiece of this review. The final outcomes are discussed and concluded.

Synthesis, characterization, antimicrobial and DNA binding properties of an organic charge transfer complex obtained from pyrazole and chloranilic acid

The chemistry of an organic charge transfer complex (CT complex) between pyrazole (donor) and chloranilic acid (acceptor) has been explored in ethanol at room temperature. The synthesized complex has been characterized by various techniques such as FTIR, NMR, Single crystal X-ray diffraction and UV-visible spectroscopy. These techniques indicate that the cation and anion are joined together by the weak hydrogen bonding. This molecular framework is a result of inter N⁺-H⋯O^- bonding between donor and acceptor moieties. The elemental analysis and FTIR spectrum of semi-crystal complex along with Job's plot indicate the formation of 2: 1 HBCT-complex. The bioorganic chemistry of the present CT complex is established well toward antimicrobial screening and DNA binding capabilities. Antimicrobial activity was screened for gram positive and gram negative bacteria and various fungi. Molecular docking shows that the CT complex binds perfectly with the B-DNA and reveals free energy of binding (FEB) value of -198.4 kcal mol^-1. TD-DFT calculations using basis set B3LYP/6-311G^** give theoretical confirmation along with HOMO (-3.9421 eV) → LUMO (-2.4903 eV) electronic energy gap (ΔE) to be 1.4521 eV. Theoretical analysis corroborates well the biological properties.

Exploring solvent dependent catecholase activity in transition metal complexes: an experimental and theoretical approach

Four coordination compounds are designed with pyridinemethanol ligands, characterized with spectral, magnetic and X-ray analyses, and assessed for catecholase activity in various solvents.

Exploring Colorimetric Real-Time Sensing Behavior of a Newly Designed CT Complex toward Nitrobenzene and Co2+: Spectrophotometric, DFT/TD-DFT, and Mechanistic Insights

An exceptionally unique, easy-to-prepare, and economic charge transfer complex (CTC), [(IMH)⁺(PA)^-], was synthesized as a highly selective real-time colorimetric chemosensor material for nitro explosive nitrobenzene (NB) and Co²⁺ ion. Co²⁺ and NB are highly potential toxic and hazardous beyond the exposure limits and also classified as carcinogens (group 2B) by IARS and United States Environmental Protection Agency. Unusual sensing ability with appreciatively low detection limits of 0.114 and 0.589 ppb for NB and Co²⁺ ion, respectively, in the aqueous medium of dimethyl sulfoxide has been reported for the first time among this class of complexes reported so far. The mechanism of the tremendous sensing behavior of this material as chemosensor was ascertained by static quenching mechanism, Dexter electron transfer, and Forster resonance energy transfer dynamic quenching mechanism, which was supported by spectral overlapping and density functional theory (DFT) (B-3LYP/def2-SVP) calculations. Real-time colorimetric sensing behavior of chemosensor was demonstrated by the naked eye test and prestained paper Co²⁺ strip test. Job's plot and comparative Fourier transform infrared (FTIR) study between CTC and CTC-Co²⁺ complex revealed the coordination mode between CTC and Co²⁺ ion and 2:1 stoichiometry. This sensing material [(IMH)⁺(PA)^-] was synthesized with donor imidazole (IM) and acceptor picric acid (PA), and its characterization was achieved by experimental (single-crystal X-ray diffraction, thermal gravimetric analysis-differential thermal analysis, FTIR, and UV-vis studies) and theoretical methods [DFT/TD-DFT calculations, comparing experimental-theoretical data and obtaining MEP map along with electronic energy gap of HOMO → LUMO (ΔE = 3.545 eV) and Hirshfeld surfaces analysis]. The SC-XRD confirms the composition and bonding features, which show hydrogen bond via N⁺-H···O^- between IM and PA. This N⁺-H···O^- interaction plays a significant role in Co²⁺ binding, proving this method of synthesizing CTC as a chemosensor to be a novel approach.

Spectrophotometric and photocatalytic studies of H-bonded charge transfer complex of oxalic acid with imidazole: single crystal XRD, experimental and DFT/TD-DFT studies

The photocatalytic activity of a new CT complex was tested. Spectrophotometric studies were performed to understand its formation through N⁺–H⋯O⁻ hydrogen bonding, and the structure was confirmed by single crystal XRD.

A combined experimental and theoretical approach to investigate the structure, magnetic properties and DNA binding affinity of a homodinuclear Cu(ii) complex

A dicopper(ii) complex of a flexible amino alcohol anchored with an acetate auxiliary was designed and characterized by spectral, X-ray crystallographic, magnetic and DFT studies; moreover, it was evaluated for its DNA binding properties. The experimental results are supported by theoretical analyses.

Progenitor cells in auricular cartilage demonstrate cartilage-forming capacity in 3D hydrogel culture

Paramount for the generation of auricular structures of clinically-relevant size is the acquisition of a large number of cells maintaining an elastic cartilage phenotype, which is the key in producing a tissue capable of withstanding forces subjected to the auricle. Current regenerative medicine strategies utilize chondrocytes from various locations or mesenchymal stromal cells (MSCs). However, the quality of neo-tissues resulting from these cell types is inadequate due to inefficient chondrogenic differentiation and endochondral ossification, respectively. Recently, a subpopulation of stem/progenitor cells has been identified within the auricular cartilage tissue, with similarities to MSCs in terms of proliferative capacity and cell surface biomarkers, but their potential for tissue engineering has not yet been explored. This study compared the in vitro cartilage-forming ability of equine auricular cartilage progenitor cells (AuCPCs), bone marrow-derived MSCs and auricular chondrocytes in gelatin methacryloyl (gelMA)-based hydrogels over a period of 56 d, by assessing their ability to undergo chondrogenic differentiation. Neocartilage formation was assessed through gene expression profiling, compression testing, biochemical composition and histology. Similar to MSCs and chondrocytes, AuCPCs displayed a marked ability to generate cartilaginous matrix, although, under the applied culture conditions, MSCs outperformed both cartilage-derived cell types in terms of matrix production and mechanical properties. AuCPCs demonstrated upregulated mRNA expression of elastin, low expression of collagen type X and similar levels of proteoglycan production and mechanical properties as compared to chondrocytes. These results underscored the AuCPCs' tissue-specific differentiation potential, making them an interesting cell source for the next generation of elastic cartilage tissue-engineered constructs.

Synthesis and dynamics of a novel proton transfer complex containing 3,5-dimethylpyrazole as a donor and 2,4-dinitro-1-naphthol as an acceptor: crystallographic, UV-visible spectrophotometric, molecular docking and Hirshfeld surface analyses

A CT complex is synthesized and characterized by spectral and crystallographic techniques. The Hirshfeld and molecular docking studies are also performed.

Should average SNOT 22 scores be calculated regionally?

CONCLUSION

The average SNOT 22 score should be calculated locally and be used as a reference when managing patients with nasal symptoms.

OBJECTIVE

To calculate the average Sino Nasal Outcome Test (SNOT) 22 score across Lanarkshire and to compare it with similar studies.

METHODOLOGY

Prospective data collection in which SNOT 22 forms were filled by the Lanarkshire population who had no history of sinonasal disease. Participants included patient attendants and hospital staff across multiple hospital sites in NHS Lanarkshire. All patients with hay fever, previous nasal surgeries, or any history of use of topical steroid sprays were excluded from the study.

RESULTS

This study included 118 participants, out of which three had to be excluded due to unclear data entry. The total number for SNOT forms included for analysis was 115. This included 85 females and 29 males, while one form remained unanswered. The mean age was 49 (range = 15-81) years. The mean SNOT 22 score was 18 (range = 0-89).

Synthesis, and spectroscopic studies of charge transfer complex of 1,2-dimethylimidazole as an electron donor with π-acceptor 2,4-dinitro-1-naphthol in different polar solvents

The charge transfer (CT) complex of 1,2-dimethylimidazole (DMI) as an electron donor with π acceptor 2,4-dinitro-1-naphthol (DNN) has been studied spectrophotometrically in different solvents like chloroform, acetonitrile, methanol, methylene chloride, etc. at room temperature. The CT complex which is formed through the transfer of lone pair electrons from DMI to DNN exhibits well resolved CT bands and the regions of these bands were remarkably different from those of the donor and acceptor. The stoichiometry of the CT complex was found to be 1:1 by a straight-line method between donor and acceptor with maximum absorption bands. The novel CT complex has been characterized by FTIR, TGA-DTA, powder XRD, (1)H NMR and (13)C NMR spectroscopic techniques. The Benesi-Hildebrand equation has been used to determine the formation constant (K(CT)), molar extinction coefficient (ε(CT)), standard gibbs free energy (ΔG°) and other physical parameters of the CT complex. The formation constant recorded higher values and molar extinction coefficient recorded lower values in chloroform compared with methylene chloride, methanol and acetonitrile, confirming the strong interaction between the molecular orbital's of donor and acceptor in the ground state in less polar solvent. This CT complex has been studied by absorption spectra of donor 1,2-dimethylimidazole (DMI) and acceptor 2,4-dinitro-1-naphthol (DNN) by using the spectrophotometric technique in various solvents at room temperature.

Synthesis, spectroscopic investigations, antimicrobial and DNA binding studies of a new charge transfer complex of o-phenylenediamine with 3,5-dinitrosalicylic acid

A charge transfer complex of o-phenylenediamine (OPD) as donor with 3,5-dinitrosalicylic acid (DNSH) as acceptor, was synthesized and characterized by FTIR, (1)H NMR, (13)C NMR, mass spectroscopy, elemental analysis and X-ray crystallography. The structural investigations exhibit that the cation and anion are joined together by strong N(+)H⋯O(-) type hydrogen bonds and stoichiometry of CT complex was found to be 1:1. The CT (charge transfer) complex shows remarkable interaction with Calf thymus DNA, and the CT complex was also screened for its microbial activity such as antimicrobial and antifungal activities. A molecular frame work through H-bonding interactions via n→π(*) transitions between neighboring moieties is found which is responsible for high melting point of resulting CT complex. This has been attributed to the formation of 1:1 CT complex.

Interleukin-1β enhances cartilage-to-cartilage integration

The failure of cartilages to fuse, particularly in the case of articular cartilage under conditions of repair is due to morphological and structural constraints of the tissue. Factors that impede integration include, non-vascularisation, low cellularity, and proteoglycan in the surrounding extracellular matrix acting as a natural barrier to cellular migration. We hypothesised that brief activation of a catabolic cascade by cytokines followed by culture under anabolic conditions would promote tissue fusion in a ring-disk model of cartilage integration. Our results show that transient exposure to 10 ng mL(-1) interleukin-1β, followed by two weeks post-culture under anabolic conditions, enhanced cartilage-cartilage integration compared to untreated explants. Quantitative PCR analysis of catabolism-related genes ADAMTS4 and MMP13 showed both were transiently upregulated and these findings correlated with evidence of extracellular matrix remodelling. At the level of histology, we observed chondrocytes readily populated the interfacial matrix between fused explants in interleukin-1β treated explants, whereas in control explants this region was relatively acellular in comparison. Catabolic cytokine treated explants exhibited 29-fold greater adhesive strength (0.859 MPa versus 0.028 MPa, P 〈 0.05) than untreated counterparts. Collectively, our results demonstrate that a single short catabolic pulse followed by an anabolic response is sufficient to generate mechanically robust, integrative cartilage repair.

Synthesis, characterization, spectrophotometric, structural and antimicrobial studies of the newly charge transfer complex of p-phenylenediamine with π acceptor picric acid

Charge transfer complex (CTC) of donor, p-phenylenediamine (PPD) and acceptor, 2,4,6-trinitrophenol (picric acid) has been studied in methanol at room temperature. The CT complex was synthesized and characterized by elemental analysis, FTIR spectra, 1H NMR spectroscopy and electronic absorption spectra which indicate the CT interaction associated with proton migration from the acceptor to the donor followed by hydrogen bonding via N+-H⋯O-. The thermal stability of CT complex was studied using TGA and DTA analyses techniques. The CT complex was screened for its antifungal activity against Aspergillus niger (Laboratory isolate), Candida albicans (IQA-109) and Penicillium sp. (Laboratory isolate) and antibacterial activity against two Gram-positive bacteria Staphylococcus aureus (MSSA 22) and Bacillus subtilis (ATCC 6051) and two Gram-negative bacteria Escherichia coli (K 12) and Pseudomonas aeruginosa (MTCC 2488). It gives good antimicrobial activity. The stoichiometry of the CT complex was found to be 1:1. The physical parameters of CT complex were evaluated by the Benesi-Hildebrand equation. On the basis of the studies, the structure of CT complex is [(PPDH)+(PA)-], and a general mechanism for its formation is proposed.

Synthesis, spectral and thermal studies of the newly hydrogen bonded charge transfer complex of o-phenylenediamine with pi acceptor picric acid

Newly proton or charge transfer complex [(OPDH)(+)(PA)(-)] was synthesized by the reaction of the donor, o-phenylenediamine (OPD) with acceptor, 2,4,6-trinitrophenol (PAH). The chemical reaction has occurred via strong hydrogen bonding followed by migration of proton from acceptor to donor. UV-vis, (1)H NMR and FTIR spectra, in addition to the thermal and elemental analysis were used to confirm the proposed occurrence of the chemical reaction and to investigate the newly synthesized solid CT complex. The stoichiometry of the CT complex was found to be 1:1. The formation constant and molar extinction coefficient of the CT complex were evaluated by the Benesi-Hildebrand equation.

Synthesis, spectrophotometric, structural and thermal studies of the charge transfer complex of p-phenylenediamine, as an electron donor with pi acceptor 3,5-dinitrobenzoic acid

The interaction between p-phenylenediamine (PPD) as a donor with the pi acceptor 3,5-dinitrobenzoic acid (DNB) has been investigated spectrophotometrically in methanol at room temperature. CT complex formed as a result of transfer of lone pair of electrons and exhibits well resolved charge transfer bands in the regions where neither donor nor acceptor have any absorption. The stoichiometry of the charge transfer complex (CTC) was found to be 1:1. The solid state CTC has also been synthesized, and has been characterized by elemental analysis, FTIR spectra, (1)H NMR spectroscopy and electronic absorption. The thermal stability of CT complex was studies using TGA and DTA analyses techniques. On the basis of the studies, the structure of CT complex is [(PPD)(DNB)], and a general mechanism for its formation is proposed. The formation constant and other physical parameters of the CT complex were determined by the Benesi-Hildebrand equation.

The role of surface microtopography in the modulation of osteoblast differentiation

The osteoinductive and conductive capabilities of commercially pure titanium and its alloys is well documented, as is their ability to provide long-term stability for permanent implantable devices. Fracture fixation in paediatric and trauma patients generally requires transient fixation after which the implant becomes redundant and requires removal. Removal can be complicated due to excessive bony over-growth which is encouraged by the standard micro-rough implant surface. We have shown in vivo that removal related morbidity can be significantly reduced with surface polishing, a technique which reduces the micro-roughness of clinically available materials. However, tissue integration at the bone-implant interface requires activation of key regulatory pathways which influences osteoblastic differentiation and maturation therefore we do not believe this effect to be purely mechanical. To elucidate potential mechanisms by which surface polishing exerts its effect on bone regeneration this study assessed in vitro the effect of surface polishing commercially pure titanium on cell growth, morphology and on the regulation of core binding factor 1, osterix, collagen I, alkaline phosphatase, bone sialoprotein and osteocalcin for primary rat calvarial osteoblasts. Results indicate that polishing differentially influences osteoblast differentiation in a surface dependent manner and that these changes are potentially linked to surface dependent morphology, but not to differences in cell proliferation.

Spectrophotometric and spectroscopic studies of charge transfer complexes of p-toluidine as an electron donor with picric acid as an electron acceptor in different solvents

The charge transfer complexes of the donor p-toluidine with pi-acceptor picric acid have been studied spectrophotometrically in various solvents such as carbon tetrachloride, chloroform, dichloromethane acetone, ethanol, and methanol at room temperature using absorption spectrophotometer. The results indicate that formation of CTC in non-polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands. The data are discussed in terms of formation constant (K(CT)), molar extinction coefficient (epsilon(CT)), standard free energy (DeltaG(o)), oscillator strength (f), transition dipole moment (mu(EN)), resonance energy (R(N)) and ionization potential (I(D)). The results indicate that the formation constant (K(CT)) for the complex was shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents that were used.

Fibroblast growth factor-2 induced chondrocyte cluster formation in experimentally wounded articular cartilage is blocked by soluble Jagged-1

INTRODUCTION

Basic fibroblast growth factor (FGF2) is a mitogen for articular chondrocytes. Cell death frequently occurs upon cartilage wounding and is evident during the progression of osteoarthritis. We hypothesised that incubation of wounded articular cartilage with exogenously added FGF2 would enhance cartilage repair, replacing dead cells through increased cell proliferation.

METHODS

Articular cartilage from the metacarapalphalangeal joint of immature bovine steers was wounded in situ, then incubated in vitro in the continual presence or absence of FGF2. Cellular proliferation was expressed as a ratio of cell density of a fixed area between wounded and adjacent cartilage. Immunolabelling revealed the incorporation of bromodeoxyuridine and localisation of collagen type VI and Notch1 epitopes. gamma-secretase inhibitor N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester and soluble Jagged1 ligand (sJ1) were used to analyse the function of Notch signalling in this wound model.

RESULTS

FGF2 induced cellular proliferation at the margins of wounded articular cartilage, where proliferative chondrocytes adopted a cluster configuration. Collagen type VI protein was expressed by chondrocytes in clusters, as was Notch1. Cellular proliferation was not affected by inhibition of gamma-secretase dependent Notch1 signalling. Binding of sJ1 to Notch1 receptors in FGF2 treated cartilage inhibited proliferation.

CONCLUSION

Addition of FGF2 induces rapid chondrocyte proliferation in wounded cartilage, chondrocytes adopt a cluster morphology and also express Notch1. Binding of sJ1 to Notch1 causes apoptosis overriding a proliferative response. This study may shed some light on the significance of increased Notch1 expression and its localisation in chondrocyte clusters in osteoarthritic cartilage.

Spectrophotometric and spectroscopic studies of complexation of 8-hydroxyquinoline with pi acceptor metadinitrobenzene in different polar solvents

The complexation of electron donor-acceptor complexes of 8-hydroxyquinoline (8HQ) and metadinitrobenzene (MNB) have been studied spectrophotometrically and thermodynamically in different polar solvent at room temperature. A new absorption band due to charge transfer (CT) transition is observed in the visible region. A new theoretical model has been developed which take into account the interaction between electronic subsystem of 8HQ and MNB. The results indicate the extent of charge transfer complexes (CTCs) formation to be more in less polar solvents. Stoichiometry of the complex was found to be 1:1 by straight line method and (1)H NMR between donor and acceptor at the maximum absorption bands. Ionization potential (I(D)) and resonance energy (R(N)) were determined from the CT transition energy in different solvents. The formation constants of the complexes were determined in different polar solvents from which Delta G degrees formation of the complexes was estimated and also extinction coefficient of the charge transfer complex (CTC) was calculated. Oscillator strength, transition dipole strengths and maximum wavelength of the CTC (lambda(CT)) in various solvents and IR spectra of the CTC have also been discussed. It has been observed that all parameters described above changed with change in polarity and concentration of donor.

Clonal chondroprogenitors maintain telomerase activity and Sox9 expression during extended monolayer culture and retain chondrogenic potential

OBJECTIVE

Articular cartilage contains mesenchymally derived chondroprogenitor cells that have the potential to be used for stem cell therapy. The aim of this study was to characterise the growth kinetics and properties of in vitro expanded cloned chondroprogenitors and determine if critical determinants of the progenitor phenotype were maintained or lost in culture.

METHODS

Chondroprogenitors were isolated from immature bovine metacarpalphalangeal joints by differential adhesion to fibronectin. Cloned colonies were expanded in vitro up to 50 population doublings (PD). Growth characteristics were assessed by cell counts, analysis of telomere length, telomerase activity, expression of senescence-associated beta-galactosidase activity and real-time quantitative polymerase chain reaction to analyse the gene expression patterns of sox9 and Notch-1 in chondroprogenitors.

RESULTS

Cloned chondroprogenitors exhibited exponential growth for the first 20 PD, then slower linear growth with evidence of replicative senescence at later passages. Mean telomere lengths of exponentially growing chondroprogenitors were significantly longer than dedifferentiated chondrocytes that had undergone a similar number of PD (P<0.05). Chondroprogenitors also had 2.6-fold greater telomerase activity. Chondroprogenitors maintained similar sox9 and lower Notch-1 mRNA levels compared to non-clonal dedifferentiated chondrocytes. Chondroprogenitors were induced to differentiate into cartilage in 3D pellet cultures, immunological investigation of sox9, Notch-1, aggrecan and proliferating cell nuclear antigen (PCNA) expression showed evidence of co-ordinated growth and differentiation within the cartilage pellet.

CONCLUSION

Clonal chondroprogenitors from immature articular cartilage provide a useful tool to understand progenitor cell biology from the perspective of cartilage repair. Comparisons with more mature progenitor populations may lead to greater understanding in optimising repair strategies.

Outcome of palliative esophageal stenting for malignant dysphagia: a retrospective analysis

Greater than 50% of patients with esophageal carcinoma are found to be incurable at the time of diagnosis, leaving only palliative options. Self-expanding metal stents (SEMs) are effective for relieving symptoms and complications associated with esophageal carcinoma and improving quality of life. We undertook a retrospective analysis to evaluate the experience of palliative esophageal stenting for symptomatic malignant dysphagia in our institution over a period of 7 years. Between January 1999 and January 2006, 126 patients who received SEMs for malignant dysphagia were identified using an upper gastrointestinal specialist nurse clinician database. Data were obtained from patient case notes, endoscopy, histopathology, radiology, and external agency databases. Of the 126 identified, 36 patients were excluded from the analysis. A number of variables including age, sex, presenting complaints, type of stent, indications of stenting, success or failure of stent insertion, survival rate, and complication rate were analyzed. Of the 90 patients, 55 (61%) were male and 35 (39%) were female. The mean age of patients was 70.79 (range 40-97) years. The predominant presenting complaints were dysphagia (n = 81) and weight loss (n = 48). The indication for stenting was worsening dysphagia in all patients. Tumors were confined to the distal esophagus and esophagogastric junction in 73 patients (81%), and the mid-esophagus in 17 (19%). Adenocarcinoma was identified in 61 patients (67.8%) and squamous cell carcinoma in 29 (32.2%). Stenting numbers were comparable in endoscopic and radiologic groups (47 vs. 43), with successful stent deployment in 89 patients. The 7- and 30-day mortality was 9% (n = 8) and 28% (n = 25), respectively. Comparable numbers of early deaths were seen in both radiologic (n = 13) and endoscopic (n = 12) groups. Causes of early inpatient death included hemorrhage (n = 5), pneumonia (n = 7), exhaustion (n = 2), cardiac causes (n = 3), perforation (n = 1), and sepsis (n = 1). The number of patients with complications was 41 (45.6%), 25 in the surgical group and 15 in the radiologic group; the difference was not significant (P = 0.13). The mean survival time was 92.5 (0-638) days and median survival time was 61 days. A subgroup of patients with complete dysphagia (score 4) gained a mean survival of 59 days. Those patients receiving adjuvant chemotherapy or radiotherapy survived significantly longer than those receiving stenting alone (152.8 days vs. 71.8 days). There is no significant difference in complications or survival when using endoscopic or radiologic methods to deploy SEMs in patients with inoperable esophageal cancer. Mortality is low; however, the morbidity rate is significant. Patients receiving adjuvant chemotherapy or radiotherapy, in addition to stenting, survived significantly longer than those with a stent only.

Cartilage integration: evaluation of the reasons for failure of integration during cartilage repair. A review

Articular cartilage is a challenging tissue to reconstruct or replace principally because of its avascular nature; large chondral lesions in the tissue do not spontaneously heal. Where lesions do penetrate the bony subchondral plate, formation of hematomas and the migration of mesenchymal stem cells provide an inferior and transient fibrocartilagenous replacement for hyaline cartilage. To circumvent the poor intrinsic reparative response of articular cartilage several surgical techniques based on tissue transplantation have emerged. One characteristic shared by intrinsic reparative processes and the new surgical therapies is an apparent lack of lateral integration of repair or graft tissue with the host cartilage that can lead to poor prognosis. Many factors have been cited as impeding cartilage:cartilage integration including; chondrocyte cell death, chondrocyte dedifferentiation, the nature of the collagenous and proteoglycan networks that constitute the extracellular matrix, the type of biomaterial scaffold employed in repair and the origin of the cells used to repopulate the defect or lesion. This review addresses the principal intrinsic and extrinsic factors that impede integration and describe how manipulation of these factors using a host of strategies can positively influence cartilage integration.

Oxidative stress induces expression of osteoarthritis markers procollagen IIA and 3B3(-) in adult bovine articular cartilage

OBJECTIVE

Oxidative stress occurs when the metabolic balance of a cell is disrupted through exposure to excess pro-oxidant. Whilst it is known that unregulated production or exposure to exogenous sources of pro-oxidants induces chondrocyte cell death and degrades matrix components in vitro, relatively little is known of the effects of pro-oxidants on articular cartilage in situ. The objective of this study was to determine if a single exposure to the pro-oxidant hydrogen peroxide (H(2)O(2)) induces a degenerative phenotype.

METHODS

Articular cartilage explants were obtained from skeletally mature bovine steers and exposed to a single dose of hydrogen peroxide (0.1-1.0 mM) and cultured for up to 21 days. Cell death, and sulfated glycosaminoglycan loss into the medium and gene expression were quantitatively determined. Adoption of an abnormal chondrocyte phenotype was analyzed through the expression of 3B3(-), nitrotyrosine and procollagen type IIA epitopes in cartilage explants.

RESULTS

Cell death occurred primarily at the surface zone of cartilage in a dose-dependent manner in H(2)O(2) treated explants, and supplementation of standard serum-free medium with insulin-selenium-transferrin significantly reduced cell death (>fourfold). Nitric oxide synthase-2 gene expression and proteoglycan loss increased in oxidant treated explants in a concentration-dependent manner. Antibody labeling to 3B3(-), procollagen type IIA and nitrotyrosine was present in all treated explants but absent in untreated explants.

CONCLUSIONS

This study demonstrates that a single exposure to high levels of pro-oxidant causes the expression of genes and antibody epitopes that are associated with early degenerative changes observed in experimental osteoarthritis.

The development of synovial joints

During vertebrate evolution, successful adaptation of animal limbs to a variety of ecological niches depended largely on the formation and positioning of synovial joints. The function of a joint is to allow smooth articulation between opposing skeletal elements and to transmit biomechanical loads through the structure, and this is achieved through covering the ends of bones with articular cartilage, lubricating the joint with synovial fluid, using ligaments to bind the skeletal elements together, and encapsulating the joint in a protective fibrous layer of tissue. The diversity of limb generation has been proposed to occur through sequential branching and segmentation of precartilaginous skeletal elements along the proximodistal axis of the limb. The position of future joints is first delimited by areas of higher cell density called interzones initially through an as yet unidentified inductive signal, subsequently specification of these regions is controlled hierarchically by wnt14 and gdf5, respectively. Joint-forming cell fate although specified is not fixed, and joints will fuse if growth factor signaling is perturbed. Cavitation, the separation of the two opposing skeletal elements, and joint morphogenesis, the process whereby the joint cells organize and mature to establish a functional interlocking and reciprocally shaped joint, are slowly being unraveled through studying the plethora of molecules that make up the unique extracellular matrix of the forming structure. The joint lining tissue, articular cartilage, is avascular, and this limits its reparative capacity such that arthritis and associated joint pathologies are the single largest cause of disability in the adult population. Recent discoveries of adult stem cells and more specifically the isolation of chondroprogenitor cells from articular cartilage are extending available therapeutic options, though only with a more complete understanding of synovial joint development can such options have greater chances of success.

Spinal nicotinic receptor activity in a genetic model of hypertension

Intrathecal cytisine, a nicotinic receptor agonist, elicits greater dose-dependent increases in blood pressure, heart rate and nociceptive responses in SHR than normotensive rat strains. Similar to adult rats, cardiovascular and nociceptive responses were augmented in prehypertensive SHR than age-matched WKY. While hydralazine or captopril pretreatment significantly lowered blood pressure in both SHR and WKY rats, responses to i.t. cytisine were still greater in SHR. By contrast, i.t. cytisine elicited responses were not exaggerated in DOCA-salt hypertensive WKY rats. Pressor and irritation responses to i.t. cytisine can be divided into a transient, initial and persisting, late phases. Both are augmented in SHR. In F1 rats, only the late phase pressor and pain responses to i.t. cytisine are similar in magnitude to those observed in SHR suggesting a possible dominant trait in the SHR. Overall, our findings suggest that hyper-responsiveness in nociception and pressor activity to spinal cytisine in SHR may be pathogenetically associated, but not a consequence, of hypertension.

Expression of clusterin in the superficial zone of bovine articular cartilage

OBJECTIVE

To investigate the differences between chondrocytes of the superficial and underlying zones of articular cartilage at the level of gene expression.

METHODS

Messenger RNA (mRNA) was isolated from chondrocytes harvested from the superficial and deep zones of immature bovine articular cartilage. This mRNA was reverse transcribed, radiolabeled, and then each complementary DNA (cDNA) sample was used to screen duplicate filters of a bovine chondrocyte cDNA library. By comparing autoradiographic signals on matching filter sets, clones exclusively expressed in the superficial zone of articular cartilage were isolated and characterized further.

RESULTS

Of the superficial-specific gene clones isolated, 25% were found to be a single gene product, clusterin. Northern hybridization was used to show that clusterin is expressed specifically in the superficial zone of articular cartilage and that its expression is up-regulated in mature cartilage. In situ hybridization was used to precisely localize clusterin transcripts in articular cartilage, where it was found that clusterin expression was confined to the articular surface in both immature and mature samples.

CONCLUSION

The discovery of clusterin expression at the articular cartilage surface extends previous observations that superficial articular chondrocytes are highly specialized cells. Clusterin is a multifunctional, secreted glycoprotein that has been shown to be expressed in diverse locations that have in common a tissue-fluid boundary. Additionally, clusterin has been implicated in regulating complement activation and cell death in injured and degenerating tissues.

A-85380 and epibatidine each interact with disparate spinal nicotinic receptor subtypes to achieve analgesia and nociception

Nicotinic agonists, such as epibatidine (EPI) and A-85380, when administered systemically, elicit analgesia. Intrathecal EPI also produces analgesia accompanied by nociceptive and pressor responses. Since spinal administration of drugs offers a well defined pathway connecting the site of administration with behavioral and autonomic responses, we have compared the responses to intrathecal epibatidine and A-85380 to delineate the role of nicotinic acetylcholine receptors in spinal neurotransmission. Following implantation of intrathecal catheters in rats, we monitored cardiovascular, nociceptive, and antinociceptive responses after administration of various nicotinic receptor agonists. Consistent with A-85380 displacement of epibatidine from isolated spinal cord membranes, A-85380 elicited pressor, nociceptive, and antinociceptive responses similar to EPI. Antinociception was preceded by nociception. Both antinociception and nociception were blocked by mecamylamine, methyllycaconitine, and alpha-lobeline, but dihydro-beta-erythroidine only blocked the antinociceptive response. Whereas prior administration of EPI desensitized the nociceptive and antinociceptive responses to EPI, A-85380 pretreatment only desensitized EPI-elicited nociception and not antinociception. 2-Amino-5-phosphopentanoic acid pretreatment blocked the nociceptive response to A-85380, indicating A-85380 stimulated release of glutamate onto N-methyl-D-aspartate receptors to produce the irritant response of nociception. Intrathecal phentolamine virtually abolished A-85380 antinociception, but had no effect on EPI antinociception. Hence, analgesia can be produced by stimulation of distinct spinal preterminal nicotinic receptor subtypes, resulting in the release of neurotransmitters. In the case of A-85380, these sites primarily appear to be localized on adrenergic bulbospinal terminals. Our data suggest that A-85380 and EPI act at separate preterminal spinal sites as well as on distinct nicotinic receptor subtypes to elicit an antinociceptive response at the spinal level.

Organization and conservation of the GART/SON/DONSON locus in mouse and human genomes

The SON gene, which maps to human chromosome 21q22.1-q22.2, encodes a novel regulatory protein. Here we describe the organization of the Son locus in the mouse genome. The mouse Son gene spans a region of approximately 35 kb. The coding region is more than 8 kb in length and has been completely sequenced. The gene is organized into 11 coding exons and 1 noncoding 3'UTR exon, with over 70% of the coding region residing in one 5.7-kb exon. The gene contains at least one alternative exon, N/C exon 1, which can be used, by splicing, to generate a truncated form of the SON protein. Further investigation of the mouse Son locus has identified the genes directly flanking Son. The glycinamide ribonucleotide formyltransferase gene, Gart, is encoded 5' of Son in a head-to-head arrangement, with the start of both genes lying within 899 bp. Sequence comparison with the expressed sequence tagged database identified a novel gene within 65 bp of the 3' end of Son, which we have named Donson. In this unusually compact gene cluster, we have found overlap in the pattern of expression between Gart, Son, and Donson. However, at least two of these genes have very different functions. While GART is involved in purine biosynthesis, we find that SON shows the characteristics of "SR- type" proteins, which are involved in mRNA processing and gene expression.

Nociceptive and antinociceptive responses to intrathecally administered nicotinic agonists

Activation of spinal nicotinic receptors evokes a prominent algogenic response. Recently, epibatidine, a potent nicotinic agonist, was found to display an antinociceptive response after systemic administration. To examine the spinal component of this action, effects of three nicotinic agonists epibatidine, cytisine and nicotine--were given intrathecally (IT) and their antinociceptive activity was subsequently assessed. All agents elicited dose-dependent algogenic activity, characterized at lower doses by touch-evoked hyperactivity and at higher doses by intermittent vocalization and marked behavioral activity, with the rank order of potency being epibatidine > cytisine > nicotine. In addition, intrathecal epibatidine elicited a short-lasting, dose-dependent thermal antinociception. In contrast, the other nicotinic agonists at the highest usable dose failed to produce a significant antinociception. Mecamylamine, a nicotinic channel blocker, completely abolished the antinociceptive and algogenic responses of epibatidine. The competitive antagonist, alpha-lobeline, blocked both the analgesic and algogenic responses, but methyllycaconitine inhibited only the algogenic effects of epibatidine. Dihydro-beta-erythroidine, also a competitive antagonist, had no effect on the initial intense algogenic responses. The analgesic response to epibatidine was neither inhibited by naloxone nor by atropine. 2-Amino-5-phosphopentanoic acid, a competitive N-methyl-D-aspartate receptor antagonist, did not affect the analgesic response to intrathecal epibatidine or the intense initial algogenic response. Upon repeated administration (30-min interval), epibatidine (1 microg, IT) exhibited marked and rapid desensitization to both the analgesic and algogenic responses which recovered within 8 h. Pretreatment with two consecutive doses of cytisine (5 microg, IT, 30-min apart) inhibited the agitation and analgesic actions of intrathecal epibatidine. Thus, we contend that in addition to the typical nociceptive response elicited by spinal nicotinic agonists, intrathecal epibatidine also exhibits a pronounced but short-lasting antinociception. The analgesic and algogenic responses to intrathecal epibatidine may be mediated by distinct subtypes of spinal nicotinic receptors as suggested by the antagonist studies.

Catalytic thiol and carboxylate: role of cysteine and glutamic acid in the xylosidic activity of endoxylanase from Chainia sp. (NCL 82-5-1)

Chemical modification of the endoxylanase from Chainia sp. with group-specific chemical modifiers in the absence and presence of substrate and kinetics of modification revealed the involvement of a thiol and a carboxylate in the catalytic function of the enzyme. The active-site peptides were chemically labeled and sequenced. The sequence alignment of the chemically labeled peptide with other family G/11 xylanases showed that the catalytic glutamate of Chainia xylanase is located in a highly homologous region and may function as an acid/base catalyst while thiol of the Cys may function as a nucleophile.