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Results for “Spectroscopy, Fourier Transform Infrared”

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PubMed1996

Short-term effects of secretagogues on the mouse parotid and sublingual gland tissular water.

The effects of isoproterenol and pilocarpine on the tissular water of mouse parotid and sublingual glands were studied by thermogravimetry (TG) coupled with Fourier transform infrared spectroscopy (FTIR). Results demonstrated that the short-term effects partly resemble the long-term action of these substances on the above-mentioned organs. Due to the different stages examined, it is difficult to speculate on the comparison between previous and the present findings. The original data resulting from the present research corresponded to the dimorphism expressed in the thermoanalytical profile of the parotid glands treated with secretagogues.

Adrenergic beta-Agonists↗

PubMed2001

In vivo assessment of enhanced topical delivery of terbinafine to human stratum corneum.

PURPOSE: The objective of this study was to evaluate, using attenuated total reflectance Fourier transform infrared spectroscopy, the stratum corneum (SC) bioavailability of terbinafine (TBF) following topical treatment with four different formulations. METHODS: Four skin sites on the ventral forearms of five healthy volunteers were treated for 2 h using one of four formulations based on a vehicle consisting of 50% ethanol and 50% isopropyl myristate. Three of these formulations included a percutaneous penetration enhancer: either 5% oleic acid, 10% 2-pyrrolidone or 1% urea. The SC concentration profile of TBF was measured by repeated infrared spectroscopic measurements while sequentially stripping off the layers of this barrier membrane with adhesive tape. This method was validated by HPLC analysis of TBF extracted from the stripped tapes. Transepidermal water loss (TEWL) measurements were also performed, to permit facile estimation of SC thickness. RESULTS: The SC concentration profiles of TBF were fitted to the appropriate solution of Fick's second law of diffusion, thereby allowing determination of the characteristic diffusion and partitioning parameters of the permeating drug. This analysis enabled the efficacies of the different formulations tested to be compared to the no-enhancer control. While it was found that the formulation containing 5% oleic acid significantly enhanced the SC availability of TBF, the other formulations did not improve the apparent drug delivery. CONCLUSIONS: A facile and minimally invasive methodology to evaluate an important aspect of topical drug bioavailability has been described. The analytical methods used (infrared spectroscopy and HPLC) allow estimates of both relative and absolute drug bioavailability in the SC and may be useful, therefore, in the critical determination of bioequivalence between topical formulations.

Administration, Topical↗

PubMed2006

Spectroscopic study of substrate binding to the carbonmonoxy form of dehaloperoxidase from Amphitrite ornata.

Dehaloperoxidase (DHP) is a globular heme enzyme found in the marine worm Amphitrite ornata that can catalyze the dehalogenation of halophenols to the corresponding quinones by using hydrogen peroxide as a cosubstrate. Its three-dimensional fold is surprisingly similar to that of the oxygen storage protein myoglobin (Mb). A key structural feature common to both DHP and Mb is the existence of multiple conformations of the distal histidine. In DHP, the conformational flexibility may be involved in promotion of substrate and cosubstrate entry and exit. Here we have explored the dynamics of substrate binding in DHP using Fourier transform infrared spectroscopy and flash photolysis. A number of discrete conformations at the active site were identified from the appearance of multiple CO absorbance bands in the infrared region of the spectrum. Upon photolysis at cryogenic temperatures, the CO molecules are trapped at docking sites within the protein matrix, as inferred from the appearance of several photoproduct bands characteristic of each site. Substrate binding stabilizes the protein by approximately 20 kJ/mol. The low yield of substrate-bound DHP at ambient temperature points toward a steric inhibition of substrate binding by carbon monoxide.

Animals↗

PubMed2006

Osteopetrosis complicated by osteomyelitis of the mandible: a case report including characterization of the osteopetrotic bone.

A case of a 53-year-old Japanese man with osteopetrosis complicated by osteomyelitis of the mandible is presented. The patient experienced frequent exacerbations and remissions of osteomyelitis of the mandible, despite undergoing several surgical debridements and sequesterectomies with appropriate antimicrobial therapy, for 3 years. Finally, the patient underwent mandibular segmental resection followed by reconstruction with a titanium reconstruction plate. Fifty-one months after surgery there is no evidence of recurrent osteomyelitis of the mandible, suggesting that a more radical surgical approach is preferable for patients with severe complications resulting from osteopetrosis. Also presented here are the histopathological and biochemical features of the osteopetrotic bone. The osteopetrotic cortical bone was morbidly sclerotic with compact and irregular laminations. Degradation of osteocytes in the osteopetrotic bone was due to hypoxia and lack of nutrition resulting from osteosclerosis. There were no significant differences between osteopetrotic and normal bone according to X-ray diffraction, Fourier transform infrared spectroscopy, collagen content or mineral content. Micro-Vickers hardness measurements showed that osteopetrotic bone was significantly harder than normal bone, and the standard deviation of hardness was greater in osteopetrotic bone. Such a loss of integrity in osteopetrotic bone is considered to be a primary reason for the greater risk of a variety of complications such as pathological fracture and refractory osteomyelitis.

Bone Plates↗

PubMed2003

On the contribution of intramolecular H-bonding entropy to the conformational stability of alanine conformations.

The experimental and theoretical rotamerization constants for the rotameric equilibrium between the two most stable conformations of the alpha-amino acid alanine are compared. The experimental technique of matrix-isolation Fourier transform infrared spectroscopy in combination with the density functional theory (DFT) (B3LYP) and the 6-31++G** basis set is used for this study. A large disagreement between the experimental and theoretical value of the equilibrium constant is found. A relatively strong intramolecular H-bond in conformation II is at the origin of this discrepancy. From the difference between the experimental and theoretical rotamerization constant, a DeltaS degrees value of -6.6 J K(-1) mol(-1) is found for the intramolecular H-bond formation.

Alanine↗

PubMed2001

Structure-activity relationships of mineral dusts as heterogeneous nuclei for ammonium sulfate crystallization from supersaturated aqueous solutions.

Mineral inclusions, present in aqueous atmospheric salt droplets, regulate crystallization when relative humidity decreases by providing a surface for heterogeneous nucleation and thus reducing the critical supersaturation. Although laboratory studies have quantified these processes to some extent, the diverse atmospheric mineralogy presents more chemical systems than practically feasible for direct study. Structure--activity relationships are necessary. To that end, in the present work the interactions of ammonium sulfate with corundum, hematite, mullite, rutile, anatase, and baddeleyite were studied by diffuse reflectance fourier transform infrared spectroscopy (DRIFTS) and by epitaxial modeling. The spectroscopic results show that shifts in sulfate peak positions due to chemisorption are not a correlative indicator of the efficacy of heterogeneous nucleation. In contrast, epitaxial modeling results of unreconstructed surfaces explain the sequence of critical supersaturations for constant particle size. If validated by further work, this computer modeling method would provide an important structure--activity tool for the estimation of heterogeneous nucleation properties of the atmospheric mineralogy.

Aluminum Oxide↗

PubMed1999

Destructive tophaceous calcium hydroxyapatite tumor of the infratemporal fossa. Case report and review of the literature.

Tophaceous pseudogout is one of the rarest forms of crystal deposition disease, typically presenting as a destructive and invasive mass involving the temporomandibular joint or the infratemporal fossa region in the absence of any other articular manifestations. Previous cases have been assumed to be caused by calcium pyrophosphate dihydrate (CPPD) crystal deposition, based on finding weakly birefringent crystals in the involved tissues. The authors present the unique case of a 65-year-old woman with a destructive and invasive facial mass extending to the middle cranial fossa with microscopic and clinical features consistent with tophaceous pseudogout. High-resolution x-ray crystallographic powder diffraction and Fourier transformed infrared spectroscopy subsequently revealed that the crystals were composed of calcium hydroxyapatite without CPPD. The patient was later found to have primary hyperparathyroidism and mild hypercalcemia. This case demonstrates that tissue deposits of calcium hydroxyapatite can cause a destructive and invasive mass containing weakly birefringent crystals and raises the question of whether previous cases attributed to tophaceous pseudogout resulting from CPPD actually were composed of birefringent calcium hydroxyapatite.

Aged↗

PubMed2002

Characterization of carbamazepine-Gelucire 50/13 microparticles prepared by a spray-congealing process using ultrasounds.

In this work, the utilization of a spray-congealing technique using a new ultrasonic atomizer to prepare enhanced-release, solvent-free microspheres of carbamazepine (CBZ)-Gelucire 50/13 in different drug-to-polymer ratios was considered. Scanning electron microscopy analysis showed that it was possible to obtain spherically shaped and nonaggregated microparticles; the prevalent particle size was in the range 150-250 microm and the microspheres had a good encapsulation efficiency (> 90% in the prevalent size fraction). The in vitro dissolution tests displayed a significant increase of the CBZ dissolution rate from microspheres compared with pure drug and to drug-Gelucire 50/13 physical mixture. Differential scanning calorimetry, hot stage microscopy, X-ray powder diffractometry, and diffuse reflectance Fourier transform infrared spectroscopy demonstrated phase stability of the original polymorph of CBZ in all the systems; moreover, no interactions between the drug and Gelucire 50/13 were found. The results of this study suggested that the spray-congealing technique using the ultrasonic atomizer could be considered as a new and interesting method to enhance the dissolution rate of a poorly water-soluble drug as CBZ.

Calorimetry, Differential Scanning↗

PubMed2004

The evidential value of cosmetic foundation smears in forensic casework.

Cosmetic foundation products are easily transferred to clothing and other surfaces as a result of contact with such objects. Examination of past cases involving cosmetics in New Zealand has shown cosmetic foundation to be one of the more common cosmetic products encountered. The aim of this research was to determine the most discriminating method for the comparison of transferred foundation with samples obtained from a known source in forensic casework. Fifty-three foundation samples were analyzed by Fourier transform infrared spectroscopy (FTIR), gas chromatography with a flame ionization detector (GC-FID) and scanning electron microscopy-energy dispersive X-Ray analysis (SEM-EDX). It was found that a 5 mm2 section of a light smearing was enough to provide detectable results. The discriminating powers for FTIR, SEM-EDX and GC-FID were 98.3, 93.8, and 82.0% respectively. A combination of all three techniques provided a discriminating power of 99.7%, meaning that almost complete discrimination was achieved between the foundation samples.

Cosmetics↗

PubMed2006

Characterization of Pb, Cu, and Cd adsorption on particulate organic matter in soil.

Evidence exists for significant metal enrichment in particulate organic matter (POM) compared to other soil constituents, but the relevant mechanisms are poorly understood. In the present study, adsorption of the heavy metals Pb, Cu, and Cd on a loamy soil and on POM separated from this soil was investigated. The adsorption kinetic data can be well described with a pseudo-second order model, whereas the equilibrium data are well fitted by a Langmuir model. Adsorption isotherms and kinetics data, in addition to the influence of pH on metal adsorption, showed that POM had a much higher adsorption capacity for Pb, Cu, and Cd compared to the whole soil. Ionic strength effects on metal adsorption, Fourier transform infrared spectroscopy, x-ray absorption spectroscopy x-ray absorption spectroscopy including x-ray absorption near-edge structure and extended x-ray absorption fine-structure spectroscopy were employed to elucidate the adsorption mechanisms. The results suggested that Pb and Cu adsorption on POM was mainly through inner-sphere complexes with carboxyl and hydroxyl groups. Cadmium was possibly adsorbed via outer-sphere complexation, indicated by the influence of ionic strength on Cd adsorption.

Adsorption↗

PubMed2000

Montmorillonite-phenyltrimethylammonium yields environmentally improved formulations of hydrophobic herbicides.

This study aimed to design formulations of hydrophobic herbicides, alachlor and metolachlor, by adsorbing them on the clay mineral montmorillonite preadsorbed by the small organic cation phenyltrimethylammonium (PTMA). An adsorption model that considers electrostatics and specific binding and the possibility of cation adsorption above the cation exchange capacity (CEC) could explain and yield predictions for PTMA adsorption in the presence of NaCl concentrations from 0 to 500 mM. Adsorption of alachlor and metolachlor from aqueous solution on a clay mineral preadsorbed by PTMA was determined by GC and modeled by Langmuir equation. Herbicide interactions with the organoclay were studied by Fourier transform infrared spectroscopy. Leaching of herbicides was determined by a bioassay using a column technique and Setaria viridis as a test plant. The adsorbed amounts of alachlor and metolachlor on montmorillonite preadsorbed by PTMA at a loading of 0. 5 mol/kg (Mont-PTMA0.5) were higher than at a loading up to the CEC, that is, 0.8 mol/kg, and were higher than those obtained by using several other organic cations. Herbicide formulations based on Mont-PTMA0.5 yielded the largest shifts of the infrared peaks of the herbicides. These formulations based on Mont-PTMA0.5 gave slower release and showed improved weed control in comparison with formulations based on other organoclays. These formulations maintained herbicidal activity in the topsoil and yielded the most significant reduction in herbicide leaching.

Adsorption↗

PubMed2005

Classification of chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride and glucosamine 6 sulfate using chemometric techniques.

Chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride and glucosamine sulfate are natural products that are becoming increasingly popular in the treatment of arthritis. They belong to a class of compounds known as glycosaminoglycans (GAGs). They are available over the counter as nutritional supplements. However, increasing use has led to increasing scrutiny of the quality of products on the market. There is also interest in the pharmacological properties of these compounds. To facilitate this, there is a need for better qualitative and quantitative methods of analysis. This paper describes methods for achieving the qualitative identification of chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride or glucosamine sulfate. Fourier transform infrared spectroscopy coupled with a variety of chemometric methods successfully classified these compounds. Using soft independent modeling of class analogies (SIMCA), hierarchical cluster analysis (HCA) and principal components analysis (PCA) samples were classified as either chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride or glucosamine sulfate. This work also examined the discriminating ability of different sections of the spectrum. It was found that for the classification of these compounds that using the finger print region of the spectrum (below 2000 cm(-1)) gave the best discrimination.

Chondroitin Sulfates↗

PubMedDate not supplied

Hardness and degree of conversion of posterior packable composites.

Knoop microhardness and the degree of conversion of three packable composites (SureFil, Alert and Solitaire), a microfil composite (Heliomolar), a microhybrid composite (Herculite) and an indirect laboratory-processed composite (Belleglass) were evaluated as a function of distance from the irradiated surface. Cylindrical specimens (5.0 mm [diameter] x 6.0 mm [length]) of each material were visible light cured for 60 seconds in black-backed Teflon molds and sectioned. Knoop microhardness values were then obtained at 0-, 2- and 4-mm using a 50-gram load and 20 second dwell time. Degree of conversion was determined using Fourier Transform Infrared Spectroscopy. ANOVA (p<0.001) and Tukey Multiple Comparison Test (p<0.05) showed the indirect laboratory-processed composite Belleglass exhibited the highest mean values for both hardness and degree of conversion. Alert exhibited significantly greater hardness than SureFil and Solitaire at 0-mm depth. SureFil had significantly greater hardness than Alert at 4-mm depth. The degree of conversion of SureFil packable composite at 4-mm depth was significantly higher than any of the other direct composites tested.

Acrylic Resins↗

PubMed2006

Fabrication of hydroxyapatite ultra-thin layer on gold surface and its application for quartz crystal microbalance technique.

We present a method for coating gold quartz crystal microbalance with dissipation (QCM-D) sensor with ultra-thin layer of hydroxyapatite nanocrystals evenly covering and tightly bound to the surface. The hydroxyapatite layer shows a plate-like morphology and less than 20 nm in thickness. The hydroxyapatite sensor operated in liquid with high stability and sensitivity. The in-situ adsorption mechanism and conformational change of fibrinogen on gold, titanium and hydroxyapatite surfaces were investigated by QCM-D technique and Fourier-transform infrared spectroscopy. The change of secondary structures of fibrinogen adsorbed on the surfaces depended on the adsorbed amounts of protein. The secondary structure of fibrinogen adsorbed on the surfaces changes with increasing coverage. This is explained by repulsion among fibrinogens, affecting water structure and thus the strength of fibrinogen interactions on the surface. The study indicates that the hydroxyapatite sensor is applicable for qualitative and conformational analysis of protein adsorption.

Adsorption↗

PubMed1998

Surface chemical studies of Thiobacillus ferrooxidans with reference to copper tolerance.

A strain of Thiobacillus ferrooxidans was adapted to grow at higher concentrations of copper by single step culturing in the presence of 20 g/L (0.314 mol/L) cupric ions added to 9K medium. Exposure to copper results in change in the surface chemistry of the microorganism. The isoelectric point of the adapted strain (pI = 4.7) was observed to be at a higher pH than that of the wild unadapted strain (pI = 2.0). Compared to the wild strain, the copper adapted strain was found to be more hydrophobic and showed enhanced attachment efficiency to the pyrite mineral. The copper adsorption ability of the adapted strain was also found to be higher than that of the wild strain. Fourier transform infrared spectroscopy of adapted cells suggested that a proteinaceous new cell surface component is synthesized by the adapted strain. Treatment of adapted cells with proteinase-K, resulted in complete loss of tolerance to copper, reduction in copper adsorption and hydrophobicity of the adopted cells. These observations strongly suggest a role played by cell surface modifications of Thiobacillus ferrooxidans in imparting the copper tolerance to the cells and bioleaching of sulphide minerals.

Acidithiobacillus thiooxidans↗

PubMed2001

Hydrocarbon contamination of coastal sediments from the Sfax area (Tunisia), Mediterranean Sea.

The coastal area off the city of Sfax (730,000 inhabitants), well-known for fisheries and industrial activities, receives high inputs of organic matter mostly anthropogenic. Eighteen stations were selected in the vicinity of the direct discharge of industrial sewage effluents in the sea in order to study the spatial distribution of the organic contamination. Surface sediments sampled in the shallow shelf were analysed for hydrocarbons by Fourier transform infrared spectroscopy, gas chromatography and gas chromatography/mass spectrometry. Total hydrocarbon distributions revealed high contamination as compared to other coastal Mediterranean sites, with an average concentration of 1865 ppm/dry weight sediment. Gas chromatographic distribution patterns, values of unresolved mixture/n-alkane ratio and distributions of steranes and hopanes confirmed a petroleum contamination of the Arabian light crude oil type. Biogenic compounds were also identified with a series of short-chain carbon-numbered n-alkenes in the carbon range 16-24.

Demography↗

PubMed2005

Comparison of glycosphingolipids and antibodies as receptor molecules for ricin detection.

Glycosphingolipids (GSLs) have been shown to undergo strong interactions with a number of protein toxins, including potential bioterrorism agents such as ricin and botulinum neurotoxin. Characterization of this interaction in recent years has led to a number of studies where GSLs were used as the recognition molecules for biosensing applications. Here, we offer a comparison of quartz crystal microbalance (QCM) sensors for the detection of ricin using antibodies and the GSLs GM1 and asialoGM1, which have been shown to undergo strong interactions with ricin. The presence, orientation, and activity of the GSL and antibody films were confirmed using ellipsometry, Fourier transform infrared spectroscopy (FT-IR), and QCM. It was found that the GSLs offered more sensitive detection limits when directly compared with antibodies. Both GSLs had lower detection limits at 5 microg/mL, approximately 5 times lower than were found for antibodies (25 microg/mL), and their linear detection range extended to the highest concentrations tested (100 microg/mL), almost an order of magnitude beyond the saturation point for the antibody sensors. Potential sites for nonspecific adsorption were blocked using serum albumin without sacrificing toxin specificity.

Biosensing Techniques↗

PubMed2006

Water-soluble oligomer formation from acid-catalyzed reactions of levoglucosan in proxies of atmospheric aqueous aerosols.

Herein is reported the first laboratory observation of the oligomerization of levoglucosan studied under atmospherically relevant conditions. Oligomers up to 1458 Da (9-mer) were measured by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. A rational mechanism is proposed based on both the acid-catalyzed cationic ring-opening of levoglucosan and nucleophilic attack of ROH from levoglucosan on the hemi-acetal carbon to produce pyranose oligomers through the formation of glycosidic bonds. Oligomer formation is further supported by attenuated total reflectance Fourier transform infrared spectroscopy. Levoglucosan is a viable tracer for biomass burning aerosols, and the observed products may serve as secondary tracers for these types of aerosols, possibly providing additional information to facilitate source apportionment and better understand atmospheric processing of the aerosol parcel. Also, the processes supported here may contribute to the saccharide character of humic-like substances, which are proposed to be formed through the atmospheric processing of biomass burning aerosols.

Aerosols↗