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1.
Int J Pharm ; 640: 123018, 2023 Jun 10.
Article in English | MEDLINE | ID: mdl-37149113

ABSTRACT

Tuberculosis is a major health issue globally and a leading cause of death due to the infective microorganism Mycobacterium tuberculosis. Treatment of drug resistance tuberculosis requires longer treatment with multiple daily doses of drugs. Unfortunately, these drugs are often associated with poor patient compliance. In this situation, a need has been felt for the less toxic, shorter, and more effective treatment of the infected tuberculosis patients. Current research to develop novel anti-tubercular drugs shows hope for better management of the disease. Research on drug targeting and precise delivery of the old anti-tubercular drugs with the help of nanotechnology is promising for effective treatment. This review has discussed the status currently available treatments for tuberculosis patients infected with Mycobacterium alone or in comorbid conditions like diabetes, HIV and cancer. This review also highlighted the challenges in the current treatment and research on the novel anti-tubercular drugs to prevent multi-drug-resistant tuberculosis. It presents the research highlights on the targeted delivery of anti-tubercular drugs using different nanocarriers for preventing multi-drug resistant tuberculosis. Report has shown the importance and development of the research on nanocarriers mediated anti-tubercular delivery of the drugs to overcome the current challenges in tuberculosis treatment.


Subject(s)
Mycobacterium tuberculosis , Tuberculosis, Multidrug-Resistant , Tuberculosis , Humans , Antitubercular Agents/pharmacology , Tuberculosis/drug therapy , Tuberculosis, Multidrug-Resistant/drug therapy , Drug Delivery Systems
2.
Biologia (Bratisl) ; 77(5): 1373-1389, 2022.
Article in English | MEDLINE | ID: mdl-35250036

ABSTRACT

The COVID-19 infection by Novel Corona Virus (SARS-CoV-2) has become one of the largest pandemic diseases, with cumulative confirmed infections of 275,233,892 and 5,364,996 deaths to date according to World Health Organization. Due to the absence of any approved antiviral drug to treat COVID-19, its lethality is getting severe with time. The main protease of SARS-CoV-2, Mpro is considered one of the potential drug targets because of its role in processing proteins translated from viral RNA. In the present study, four of the plant metabolites, 14-deoxy-11,12-didehydroandrographolide, andrograpanin, quinine, cinchonine from two eminent medicinal plants Andrographis paniculata and Cinchona officinalis, have been evaluated against the main protease of SARS-CoV-2 through in-silico molecular docking and molecular dynamics simulation study. From the result interpretations, it is found that andrograpanin has strong binding affinities with the target protein in its active site with potential negative energies. Molecular Dynamic simulation and MMGBSA studies suggest that earlier reported N3 inhibitor and andrograpanin exhibit effective binding interactions involving identical amino acid residues with the same binding pockets of the main protease of SARS-CoV-2. Therefore, the theoretical experiment suggests that andrograpanin, could be considered the promising inhibitor against SARS-CoV-2 Mpro. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11756-022-01012-y.

3.
J Can Assoc Gastroenterol ; 5(1): 32-38, 2022 Feb.
Article in English | MEDLINE | ID: mdl-35118225

ABSTRACT

BACKGROUND: Choosing Wisely Canada (CWC) recommends not to perform gastroscopy for dyspepsia in otherwise healthy adults less than 55 years of age (2014). The aim of this study was to evaluate the use of gastroscopy in a young, healthy population with uncomplicated dyspepsia. METHODS: A retrospective review of gastroscopies completed during 3-month periods in 2015, 2016, and 2017 identified all patients undergoing gastroscopy for the primary indication of dyspepsia. Low-risk patients for dyspepsia were defined as adults, aged 18 to 54 years without alarm symptoms, comorbidities and/or abnormal imaging findings or laboratory values. Gastroscopy and pathology reports were reviewed to identify clinically actionable findings. Clinical outcomes were followed to December 31, 2018 including gastroenterology referrals, emergency room visitation and hospitalization. RESULTS: Among 1358 patients having a gastroscopy for dyspepsia, 480 (35%) were low-risk patients. Sixteen patients 3.3% (16/480) had a clinically actionable result found on gastroscopy or biopsy. No malignant lesions were detected. Low-risk patients were followed up for an average of 2.75 years, 8% (39/480) visited the emergency department (ED), 1% (3/480) of patients were admitted to hospital and 12% (59/480) of patients were re-referred for a dyspepsia-related concern. INTERPRETATION: A high rate of low yield, high cost, invasive endoscopic investigations were performed in this population of otherwise healthy patients under age 55 years. These data suggest limited uptake of current recommendations against the routine use of gastroscopy to investigate dyspepsia.

4.
World J Microbiol Biotechnol ; 36(10): 143, 2020 Aug 27.
Article in English | MEDLINE | ID: mdl-32851551

ABSTRACT

Microbial infections have become a global threat to drug-tolerant phenomena due to their biofilm formatting capacity. In many cases, conventional antimicrobial drugs fail to combat the infection, thus necessitating the discovery of some alternative medicine. Over several decades, plant metabolites have played a critical role in treating a broad spectrum of microbial infections due to its low cytotoxicity. Andrograpanin, a secondary metabolite, is a diterpenoid present in the leaf of Andrographis paniculata. In this study, andrograpanin (0.15 mM) exhibited significant inhibition on biofilm production by Pseudomonas aeruginosa in the presence of gentamicin (0.0084 mM). The impaired production of extracellular polymeric substances and several virulence factors of Pseudomonas aeruginosa were investigated to understand the mechanism of action mediated by andrograpanin. The structural alteration of biofilm was evaluated by using fluorescence microscopy, atomic force microscopy and field emission scanning electron microscopy. The in silico molecular simulation studies predicted interaction of andrograpanin with quorum sensing proteins such as RhlI, LasI, LasR, and swarming motility protein BswR of Pseudomonas aeruginosa. Overall the studies indicate that andrograpanin could be used as a therapeutic molecule against biofilm development by Pseudomonas aeruginosa.


Subject(s)
Andrographis/chemistry , Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Diterpenes/pharmacology , Plant Extracts/pharmacology , Pseudomonas aeruginosa/drug effects , Bacterial Proteins/chemistry , Bacterial Proteins/drug effects , Biofilms/growth & development , Diterpenes/chemistry , Gentamicins/pharmacology , Ligases , Microbial Sensitivity Tests , Molecular Docking Simulation , Plant Extracts/chemistry , Quorum Sensing/drug effects , Secondary Metabolism , Trans-Activators , Transcription Factors , Virulence Factors
5.
Spectrochim Acta A Mol Biomol Spectrosc ; 234: 118240, 2020 Jun 15.
Article in English | MEDLINE | ID: mdl-32172188

ABSTRACT

In an accomplishment of development of silver nanoparticles (AgNPs) based nanosensor for cysteine in its anionic and neutral forms, we have preferred N-(1-naphthyl)ethylenediamine cation (NEDA+) stabilized AgNPs (NEDA-AgNPs), because NEDA+ is a fluorescent active ion and it imparts excellent stability to AgNPs. Surface Plasmon resonance (SPR) of AgNPs and fluorescence property of NEDA+ are thus useful for presenting NEDA-AgNPs as a dual-tool nanosensor for cysteine molecules. The surface adsorbed NEDA+ cations interact selectively with cysteine as a consequence, the particles get aggregated, which was monitored using spectrophotometric method. The fluorescence property of NEDA+ is heavily quenched in NEDA-AgNPs, which could be reversed in presence of cysteine. The spectrofluorimetric method was thus used for quantification of cysteine as well. The detection limits (LOD to LOL) of anionic cysteine are 0.1784-1.598 µM and 0.0842-2.0 µM, respectively in spectrophotometric and spectrofluorimetric methods. From a real sample matrix, the recovery results are excellent, >95%. For neutral cysteine, the sensitivity is a bit low; 0.308-2.8 µM for spectrophotometric and 0.131-2.8 µM for spectrofluorimetric methods. It is found that the anionic cysteine (Kasso = 2.24 × 105 M-1/4.02 × 105 M-1) binds surface adsorbed NEDA+ cations strongly than that of neutral cysteine (Kasso = 3.69 × 104 M-1/1.24 × 105 M-1). Thus, NEDA-AgNPs show its potentials for being a dual-tool nanosensor as well as dual-form nanosensor for quantification of cysteine in a sample which may be the attractive system to an analyst.


Subject(s)
Biosensing Techniques/instrumentation , Cysteine/analysis , Ethylenediamines/chemistry , Metal Nanoparticles/chemistry , Silver/chemistry , Calibration , Cations , Cross-Linking Reagents/chemistry , Dynamic Light Scattering , Fluorescence , Hydrogen-Ion Concentration , Kinetics , Metal Nanoparticles/ultrastructure , Particle Size , Spectrophotometry, Ultraviolet
6.
Braz J Microbiol ; 51(1): 15-27, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31691922

ABSTRACT

14-Deoxy-11,12-didehydroandrographolide is a biologically active molecule present in the extract of Andrographis paniculata (Kalmegh), a classic ethnic herbal formula, which has been used for over thousand years as therapeutics to treat numerous infectious diseases like upper respiratory tract infection, urinary tract infection, and many more health issues. The present study is designed to ascertain an inhibitor against biofilm formation from the major metabolites of Andrographis paniculata, because the extract of this herb shows inhibition of bacterial quorum sensing (QS) communication and biofilm development against microorganisms. 14-Deoxy-11,12-didehydroandrographolide at 0.1 mM (sub-MIC dose) with azithromycin (6 µg/mL, sub-MIC) or gentamicin (4 µg/mL, sub-MIC) synergistically inhibits 92% biofilm production by a 48-h treatment against Pseudomonas aeruginosa. Further investigation carried out by atomic force microscopy shows promising reduction in roughness and height of biofilm in the presence of 14-deoxy-11,12-didehydroandrographolide compared with the control group. The content of extracellular polymeric substances, level of pyocyanin production, and synthesis of extracellular protease by P. aeruginosa have also been reduced significantly at around 90% in 14-deoxy-11,12-didehydroandrographolide-treated group. In conclusion, 14-deoxy-11,12-didehydroandrographolide could be used as a drug molecule against biofilm development by inhibiting QS pathway in Pseudomonas aeruginosa.


Subject(s)
Andrographis/chemistry , Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Diterpenes/pharmacology , Pseudomonas aeruginosa/drug effects , Azithromycin/pharmacology , Gentamicins/pharmacology , Microbial Sensitivity Tests , Plants, Medicinal/chemistry , Pseudomonas aeruginosa/physiology , Quorum Sensing/drug effects
7.
J Mol Recognit ; 29(9): 452-61, 2016 09.
Article in English | MEDLINE | ID: mdl-27146323

ABSTRACT

In this report, we have studied the recognition of citrate anions adsorbed on the surface of silver nanoparticles (cit-Ag-NPs), by macrocyclic polyammonium cations (MCPACs): Me6 [14]ane-N4 H8 (4+) (Tet-A/Tet-B cations) and [32]ane-N8 H16 (8+) , which are well reputed anion recognizers and are treated as to mimic of biological polyamines. The study was monitored on ultraviolet-visible spectroscopy by performing a titration of the aqueous dispersion of the cit-Ag-NPs by the aqueous solution of MCPACs. The ultraviolet-visible time-scan plots over the reduction of the absorption band of surface plasmon resonance of cit-Ag-NPs at 390 nm are well fitted with fourth-order polynomial equation and are employed to determine the initial aggregation rate constants. It has been stated that the aggregation is the result in electrostatic attraction followed by H-bond formation between the surface-adsorbed citrate anions and added MCPACs. The atomic force microscopy results have evidenced aggregation of cit-Ag-NPs in presence of MCPACs. The evaluated H-bonded association constant (Kasso ) using Benesi-Hildebrand method reveals that [32]ane-N8 H16 (8+) cations form stronger association complex, as expected, with the citrate anions than the Me6 [14]ane-N4 H8 (4+) cations. The study would thus provide the insight of molecular interactions involved in nanoparticle surface-adsorbed anions with biological polyamines. Copyright © 2016 John Wiley & Sons, Ltd.


Subject(s)
Ammonium Compounds/chemistry , Anions/chemistry , Cations/chemistry , Citric Acid/chemistry , Metal Nanoparticles/chemistry , Hydrogen Bonding , Microscopy, Atomic Force , Polyamines/chemistry , Silver/chemistry
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 140: 185-97, 2015 Apr 05.
Article in English | MEDLINE | ID: mdl-25594208

ABSTRACT

Azo dyes, 1,3-dimethyl-5-(arylazo)-6-aminouracil (aryl=-C6H5 (1), -p-CH3C6H4 (2), -p-ClC6H4 (3), -p-NO2C6H4 (4)) were prepared and characterized by UV-vis, FT-IR, 1H NMR, 13C NMR spectroscopic techniques and single crystal X-ray crystallographic analysis. In the light of spectroscopic analysis it evidences that of the tautomeric forms, the azo-enamine-keto (A) form is the predominant form in the solid state whereas in different solvents it is the hydrazone-imine-keto (B) form. The study also reveals that the hydrazone-imine-keto (B) form exists in an equilibrium mixture with its anionic form in various organic solvents. The solvatochromic and photophysical properties of the dyes in various solvents with different hydrogen bonding parameter were investigated. The dyes exhibit positive solvatochromic property on moving from polar protic to polar aprotic solvents. They are fluorescent active molecules and exhibit high intense fluorescent peak in some solvents like DMSO and DMF. It has been demonstrated that the anionic form of the hydrazone-imine form is responsible for the high intense fluorescent peak. In addition, the acid-base equilibrium in between neutral and anionic form of hydrazone-imine form in buffer solution of varying pH was investigated and evaluated the pKa values of the dyes by making the use of UV-vis spectroscopic methods. The determined acid dissociation constant (pKa) values increase according to the sequence of 2>1>3>4.


Subject(s)
Azo Compounds/chemistry , Coloring Agents/chemistry , Hydrazones/chemistry , Uracil/analogs & derivatives , Azo Compounds/chemical synthesis , Coloring Agents/chemical synthesis , Crystallography, X-Ray , Hydrazones/chemical synthesis , Magnetic Resonance Spectroscopy , Models, Molecular , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform Infrared , Stereoisomerism , Uracil/chemical synthesis , Uracil/chemistry
10.
J Colloid Interface Sci ; 344(1): 137-43, 2010 Apr 01.
Article in English | MEDLINE | ID: mdl-20060538

ABSTRACT

Water-dispersed, spherical, underivatized Au-NPs with particle size less than 5 nm were synthesized from an aqueous solution of 32-macrocyclic polyammonium chloride, [32]ane-(NH(2)(+))(8).8Cl(-) (32-MCPAC) using sodium borohydride (NaBH(4)) as the reducing agent. The bioconjugation of the synthesized Au-NPs at different pHs (3.6-5.6) with bovine serum albumin (BSA) protein was studied using UV-Vis, fluorescence, and Raman spectroscopy. These studies support that the Au-NPs were incorporated into the protein moiety and bound to it chemically. The binding constants (K(b)) and stoichiometries (n) (i.e., the number of Au-NPs bound by the proteins) of BSA protein to the Au-NPs at different pHs were determined by measuring the quenching of the fluorescence intensity of the tryptophan residues of the protein molecules after conjugation. The values for K(b) (n) were found to be 1.05 x 10(10) M(-1) (1.66), 2.09 x 10(10) M(-1) (2.30), and 1.86 x 10(10) M(-1) (1.75) at pH 3.60, 4.60, and 5.60 for BSA-Au-NPs conjugations, respectively. The results show that BSA binds to the Au-NPs strongly at pH 4.60, which is equivalent to its isoelectric point (pI 4.6).


Subject(s)
Gold/chemistry , Macrocyclic Compounds/chemistry , Nanoparticles/chemistry , Quaternary Ammonium Compounds/chemistry , Serum Albumin, Bovine/chemistry , Animals , Cations , Cattle , Nanoparticles/ultrastructure , Spectrometry, Fluorescence , Spectrophotometry , Spectrum Analysis, Raman
11.
J Chromatogr A ; 1215(1-2): 177-84, 2008 Dec 26.
Article in English | MEDLINE | ID: mdl-19036384

ABSTRACT

A metallomesogen of a polycatenar oxazoline copper(II) complex, [Cu(S-C(12))(2)], that exhibited a columnar mesophase with a helical organization was prepared and employed as the stationary phase for the GC separation with polycyclic aromatic hydrocarbons (PAHs) as model compounds. For introducing the mesogen into the capillary column, an ionic liquid (BeMIM-TfO) was used as the vehicle. The results of thermal analyses and UV-vis spectroscopy indicated that some beneficial interactions occurred between the metallomesogen and the ionic liquid. Various parameters affecting the separation efficiency were studied. Different ratios of BeMIM-TfO and Cu(S-C(12))(2) (1:0, 1:1, 1:2 and 1:3 (w/w)) were tested for the separation of the PAHs. As the amount of Cu(S-C(12))(2) was increased, complete separation could be achieved. The stationary phase with the ratio of 1:1 provided the most satisfactory result having average theoretical plate number of 5.2 x 10(3)plates/m. With an optimized temperature program, 11 PAH mixtures were completely separated within 27 min. The interaction between PAH and these fascinating and interesting stationary phases was discussed.


Subject(s)
Chromatography, Gas/instrumentation , Metals/chemistry , Calorimetry, Differential Scanning , Temperature
12.
J Colloid Interface Sci ; 326(2): 411-9, 2008 Oct 15.
Article in English | MEDLINE | ID: mdl-18657823

ABSTRACT

A new synthesis of underivatized gold nanoparticles (Au-NPs) in water stabilized by the highly water soluble 28-membered macrocyclic polyammonium chloride, [28]ane-(NH(2)(+))(6)O(2)6Cl(-) (28-MCPAC) is reported. In addition to providing stability, 28-MCPAC with its cationic form functionalizes the Au-NPs for sensing anions in water. The 28-MCPAC-Au-NPs show a surface plasmon band in the visible region (>520 nm). By tuning the 28-MCPAC:HAuCl(4) ratio, Au-NPs with different core diameters ranging from 4 nm to 6 nm, as determined by TEM analysis, can be obtained. Particles are spherical, discrete, and appeared to have narrow size distributions. Raman spectroscopy confirms that the physisorption is responsible for the interaction between Au-NP surface and 28-MCPAC. The potential of the as-synthesized particles for sensing monophosphorylated nucleosides (nucleotides): 5-adenosine monophosphate (5-AMP), 5-cytosine monophosphate (5-CMP), 5-guanine monophosphate (5-GMP), and 5-uridine monophosphate (5-UMP) is investigated spectroscopically. Nucleotides-assisted agglomerations of 28-MCPAC-Au-NPs follow the order: 5-UMP>5-GMP>5-CMP>5-AMP. An attempt is taken to prepare Au-NPs in water at pH 4.55 without an added stabilizer. Particles without an added stabilizer are short lived, and the TEM image shows that the particles aggregate following a quasi-two-dimensional self-assembly array.


Subject(s)
Gold/chemistry , Macrocyclic Compounds/chemistry , Metal Nanoparticles/chemistry , Nanotechnology/methods , Nucleotides/analysis , Quaternary Ammonium Compounds/chemistry , Cations/chemistry , Hydrogen-Ion Concentration , Microscopy, Electron, Transmission , Solubility , Spectrum Analysis, Raman , Surface Properties , Water/chemistry
13.
Electrophoresis ; 29(8): 1651-7, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18383032

ABSTRACT

A macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N(8)), in the bonded phase was employed as a molecular receptor for CEC separation of oligopeptides. Parameters affecting the performance of the separations were considered. Baseline separation for the mixture of angiotensin I, angiotensin II, [Sar(1), Thr(8)]-angiotensin II, beta-casomorphin bovine, beta-casomorphin human, oxytocin acetate, tocinoic acid, vasopressin, and FMRF amide could be achieved using phosphate buffer (30 mM, pH 7) as the mobile phase. Column efficiency with average theoretical plate numbers of 69 000 plates/m and RSDs of <1% (n = 6) was achieved. [Met(5)]-enkephalin and [Leu(5)]-enkephalin, which have identical pI values and similar masses could be completely separated using acetate buffer (30 mM) with pH gradient (pH 3 inlet side and pH 4 outlet side). The results suggest that the mechanism for the peptide separation was mediated by a combination of electrophoretic migration and chromatographic retention involving anion coordination and anion exchange. After long-term use, the deviation of the EOF of the column after more than 600 injections was still within 6.0% of that for a freshly prepared column.


Subject(s)
Chromatography, Micellar Electrokinetic Capillary/methods , Macrocyclic Compounds/chemistry , Peptides/isolation & purification , Polyamines/chemistry , Amino Acid Sequence , Hydrogen-Ion Concentration , Molecular Sequence Data , Spectrophotometry, Ultraviolet
14.
J Chromatogr A ; 1154(1-2): 407-15, 2007 Jun 22.
Article in English | MEDLINE | ID: mdl-17451724

ABSTRACT

An analytical approach of the 32-membered macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N8) was described for the capillary electrochromatographic (CEC) separation of derivatized mono- and disaccharides. The column displayed reversal electroosmotic flow (EOF) at pH below 7.0, while a cathodic EOF was shown at pH above 7.0. The reductive amination of saccharides was carried out with p-aminobenzoic acid. Some parameters that affect the CEC separations were investigated. Several competitive ligands, such as Tris, EDTA and phosphate were also examined for the effect on the performance. We achieved a complete separation of all compounds as well as the excess derivatizing agent by using borate buffer (pH 9.0) in a mode of concentration gradient (60 mM inlet side and 70 mM outlet side). The relative standard deviation of the retention time measured for each sample was less than 4% in six continuous runs, suggesting that the bonded phase along with the gradient formed inside the column was quite stable. With the mixing modes of anion coordination, anion exchange, and shape discrimination, the interaction adequately accomplishes the separation of carbohydrates which are epimers or have different glycosidic linkage, although the electrophoretic migration is also involved in the separation mechanism.


Subject(s)
Capillary Electrochromatography/methods , Carbohydrates/isolation & purification , Diacetyl/analogs & derivatives , Disaccharides/isolation & purification , Polyamines/chemistry , Borates , Buffers , Diacetyl/chemical synthesis , Diacetyl/chemistry , Edetic Acid , Electroosmosis , Hydrogen-Ion Concentration , Methanol , Phosphates , Polyamines/chemical synthesis , Tromethamine
15.
J Colloid Interface Sci ; 310(1): 178-83, 2007 Jun 01.
Article in English | MEDLINE | ID: mdl-17350029

ABSTRACT

C-undodecylcalix[4]-resorcinarene (C(11)-resorcinarene)-capped anatase TiO(2) nanoparticles have been synthesized and could be isolated and redispersed in different nonaqueous solvents. The adsorption of C(11)-resorcinarene onto the surface of TiO(2) nanoparticles led the shifting of the onset wavelength of the optical absorption in the visible range along with a broad band centered at 422 nm corresponding to ligand-to-metal charge transfer transition within the surface titanium(IV)-C(11)-resorcinarene complex. The interaction of TiO(2) nanoparticle with C(11)-resorcinarenes was investigated by photoluminescence (PL). Proton nuclear magnetic resonance ((1)H NMR) spectroscopy study revealed that the C(11)-resorcenarene molecules adsorbed chemically onto the surfaces of TiO(2) nanoparticles. The average particle diameter of bare anatase TiO(2) and C(11)-resorcinarene-capped TiO(2) was determined using transmission electron microscopy (TEM) and was found to be equal to ca. 5 nm.

16.
J Colloid Interface Sci ; 297(2): 584-8, 2006 May 15.
Article in English | MEDLINE | ID: mdl-16343525

ABSTRACT

Citrate-capped gold nanoparticles (NPs) in aqueous solution were transferred directly into the organic solution mesitylene containing C-undecylcalix[4]-resorcinarene (C11-resorcinarene). C11-resorcinarene, which has long hydrophobic tails and phenolic hydroxyl groups, acted as both a phase-transfer and a capping agent. The C11-resorcinarene-capped gold particles could be isolated and dispersed in different organic solvents. Optical absorption spectra corresponding to surface plasmon resonance provided a broad band centered at 534 nm for C11-resorcinarene-capped gold NPs in mesitylene. High-resolution transmission electron micrograph images revealed that the average particle diameter of C11-resorcinarene-capped gold NPs is approximately 12 nm.


Subject(s)
Gold/chemistry , Metal Nanoparticles/chemistry , Phenylalanine/analogs & derivatives , Calixarenes , Particle Size , Phenylalanine/chemistry , Solvents , Spectrum Analysis , Surface Plasmon Resonance , Water
17.
J Chromatogr A ; 1043(2): 255-63, 2004 Jul 23.
Article in English | MEDLINE | ID: mdl-15330100

ABSTRACT

The preparation and mesomorphic properties of a substituted bis(dithiolene)nickel complex derived from 4, 4'-dimethoxybenzil are reported. The phase transition temperatures were based on data obtained by polarized light microscopy and differential scanning calorimetry. The mesogenic phase existed over the temperature range from 77 to 175 degrees C. A novel micropacked column (1.5 or 3 m x 1 mm i.d.) prepared from the slurry of bis[1,2-bis(4-n-undecyloxyphenyl)ethane-1,2-dithiolene] nickel(II) (5%, w/w), coated on Chromosorb W was applied for the separation of dialkyl sulfides. The non-linearity (discontinuity) of Van't Hoff plots suggests that the liquid crystal property existed even in the coated phase. Factors affecting the retention and the sample selectivity on the prepared column were examined by using a flame photometric detector (FPD). The separation might be based on the mechanism of ligand exchange, shape selectivity and polarity interaction besides the vapor pressure. LOD for the determination of dialkyl sulfides was below 1 ng for most of the analytes.


Subject(s)
Chromatography, Gas/instrumentation , Nickel/chemistry , Organometallic Compounds/chemistry , Calibration , Chromatography, Gas/methods , Ligands , Magnetic Resonance Spectroscopy , Sensitivity and Specificity , Spectrophotometry, Infrared
18.
Can J Gastroenterol ; 18(4): 221-6, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15054498

ABSTRACT

BACKGROUND: Despite advances in training, operative techniques and endoscopic technology, upper and lower endoscopic procedures continue to have potential for intestinal perforation. Perforation rates provided to patients at the time of consent have frequently been derived from historical cohorts and survey datasets. OBJECTIVE: This study examined the perforation rates of upper and lower endoscopic procedures at a major Canadian tertiary care centre. METHODS: Inpatient and outpatient gastroscopies and colonoscopies performed during a three year period were evaluated. Endoscopies with perforations occurring within 14 days of procedure were retrospectively isolated using the International Classification of Diseases - 9th Revision code descriptions, then retrieved and hand searched to confirm a procedure-related perforation. Data were extracted to identify risk factors and patient outcomes. RESULTS: A total of 21,217 endoscopies (13,792 gastroscopies and 7425 colonoscopies) were reviewed. Of these, 359 were identified, isolated and hand searched for confirmation of a perforation event. Eighteen were found to have an endoscopy-associated perforation. Ten perforations occurred with colonoscopy (0.13%) (incidence, 1.3/1000 procedures), resulting in one death (0.013%) (incidence, 0.13/1000 procedures). Eight perforations occurred with gastroscopy (0.06%) (incidence, 0.6/1000 procedures), resulting in zero mortality. Of colonoscopy procedures the rate of perforation with diagnostic colonoscopy was 0.13% (incidence, 1.3/1000 procedures) and with therapeutic colonoscopy was 0.14% (incidence, 1.4/1000 procedures). Of gastroscopy procedures the rate with therapeutic gastroscopy was 0.15% (incidence, 1.5/1000 procedures). No perforations occurred with diagnostic gastroscopy. CONCLUSION: Gastroscopy and colonoscopy procedures, especially those with therapeutic maneuvers, continue to carry morbidity and mortality risks associated with perforation.


Subject(s)
Colonoscopy/adverse effects , Gastroscopy/adverse effects , Hospitals, University/statistics & numerical data , Intestinal Perforation/epidemiology , Adult , Aged , Alberta/epidemiology , Female , Gastrointestinal Diseases/diagnosis , Gastrointestinal Diseases/surgery , Humans , Intestinal Perforation/etiology , Intestinal Perforation/therapy , Intestines/injuries , Male , Middle Aged , Retrospective Studies , Time Factors
19.
Electrophoresis ; 24(6): 970-7, 2003 Mar.
Article in English | MEDLINE | ID: mdl-12658684

ABSTRACT

The parameters influencing the electrochromatographic separation of aliphatic organic acids in a capillary column with a wall-coated macrocyclic polyamine have been studied. Indirect detection using chromate, pyromellitate, trimellitate, o-phthalate, benzoate and acetate as background electrolytes has been tested. A complete separation of polyprotic acids could be achieved with pyromellitate buffer (7.5 mM, pH 6.5), and satisfactory results for the simultaneous separation of monoprotic acids and polyprotic acids were found using a capillary column of 70 cm (50 cm effective length)x75 microm inner diameter, electrokinetic injection (-10 kV, 10 s), benzoate buffer (6 mM, pH 4.6), separation voltage of -10 kV, and detection at 220 nm. For the separation of the geometric isomers fumarate and maleate, acetate buffer was found the best choice among the background electrolytes tested. The method so established has been applied to the determination of organic acids in soy sauce, brandy, lemon juice, spinach juice and cigarette. From the retention behavior, it was found that the separation mechanism on the bonded phase was influenced by the macrocyclic effect, electrostatic attraction, hydrogen bonding, van der Waals forces, and anion exchange, in addition to the differences in electrophoretic mobility.


Subject(s)
Carboxylic Acids/analysis , Electrophoresis, Capillary/methods , Fatty Acids/analysis , Beverages/analysis , Chromatography, High Pressure Liquid , Food, Organic/analysis , Hydrogen-Ion Concentration
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