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Results for “Spectroscopy, Fourier Transform Infrared”

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PubMed1999

Effects of sciatic neurectomy on the femur in growing rats: application of peripheral quantitative computed tomography and Fourier transform infrared spectroscopy.

The effects of unilateral sciatic neurectomy (USN) on the development of the femur were studied in 15 growing Wistar-derived rats (age, 5 weeks). The rats were divided into four groups: USN-operated group (right femur), USN-nonoperated group (left femur), sham-operated group (right femur), and sham-nonoperated group (left femur). Bone mineral density (BMD), bone mineral content (BMC), bone area, periosteal circumference, and endosteal circumference were measured by peripheral quantitative computed tomography (pQCT) and the mineral/matrix ratio was evaluated by Fourier transform infrared spectroscopy (FTIR). The USN-operated group showed a significant decrease in cortical BMC, bone area, and periosteal circumference compared with the other groups (P < 0.05). The cortical BMD did not vary significantly between the groups. In the cancellous bone, the USN-operated group showed a significant decrease in BMD and BMC at the metaphysis compared with the other groups (P < 0.05). The mineral/matrix ratio of the cortical bone did not differ significantly between the USN-operated and USN-nonoperated groups. These results suggest that in cortical bone, USN inhibits periosteal bone formation but has no significant effect on the mineral/matrix ratio of cortical bone in femurs. In cancellous bone, USN induces bone loss at the metaphysis.

Animals↗

PubMed2004

Identification of iso- and n-propylphosphonates using liquid chromatography-tandem mass spectrometry and gas chromatography-Fourier transform infrared spectroscopy.

Organophosphorus nerve agents and their precursors, specifically listed in the schedules of chemicals in the Annex to the Chemical Weapons Convention (CWC), include analogues with C1-C3 alkyl groups on phosphorus. The Organisation for the Prohibition of Chemical Weapons (OPCW) requires designated laboratories to unequivocally identify isomeric propyl groups bonded to phosphorus in analytes that may be present in samples submitted for analysis. Homologous series of isomeric pairs of dialkyl iso- and n-propylphosphonates, alkyl iso- and n-propylphosphonochloridates, and alkyl iso- and n-propylphosphonofluoridates, have been analysed by liquid chromatography-ion trap tandem mass spectrometry and/or by gas chromatography-Fourier transform infrared spectroscopy. The results show that P-propyl isomers can be reliably differentiated by collision induced dissociation (CID) of selected fragment ions and by their infrared P=O stretching and C-H deformation frequencies.

Chromatography, Gas↗

PubMed2001

Silver(I) complexes with DNA and RNA studied by Fourier transform infrared spectroscopy and capillary electrophoresis.

Ag(I) is a strong nucleic acids binder and forms several complexes with DNA such as types I, II, and III. However, the details of the binding mode of silver(I) in the Ag-polynucleotides remains unknown. Therefore, it was of interest to examine the binding of Ag(I) with calf-thymus DNA and bakers yeast RNA in aqueous solutions at pH 7.1-6.6 with constant concentration of DNA or RNA and various concentrations of Ag(I). Fourier transform infrared spectroscopy and capillary electrophoresis were used to analyze the Ag(I) binding mode, the binding constant, and the polynucleotides' structural changes in the Ag-DNA and Ag-RNA complexes. The spectroscopic results showed that in the type I complex formed with DNA, Ag(I) binds to guanine N7 at low cation concentration (r = 1/80) and adenine N7 site at higher concentrations (r = 1/20 to 1/10), but not to the backbone phosphate group. At r = 1/2, type II complexes formed with DNA in which Ag(I) binds to the G-C and A-T base pairs. On the other hand, Ag(I) binds to the guanine N7 atom but not to the adenine and the backbone phosphate group in the Ag-RNA complexes. Although a minor alteration of the sugar-phosphate geometry was observed, DNA remained in the B-family structure, whereas RNA retained its A conformation. Scatchard analysis following capillary electrophoresis showed two binding sites for the Ag-DNA complexes with K(1) = 8.3 x 10(4) M(-1) for the guanine and K(2) = 1.5 x 10(4) M(-1) for the adenine bases. On the other hand, Ag-RNA adducts showed one binding site with K = 1.5 x 10(5) M(-1) for the guanine bases.

Animals↗

PubMed2000

Liposome-based formulations for the antibiotic nonapeptide Leucinostatin A: Fourier transform infrared spectroscopy characterization and in vivo toxicologic study.

Leucinostatin-A is a nonapeptide isolated from Paecilomyces marquandii, Paecilomyces lilacinus A257, and Acremonium sp., exerting remarkable phytotoxic, antibacterial (especially against Gram-positive) and antimycotic activities. With the aim to find alternative formulation for in vivo administration, a number of Leucinostatin-A-loaded liposomal formulations have been prepared and characterized. Both large unilamellar vesicles and multilamellar vesicles consisting of synthetic and natural lipids were evaluated. In addition, to determine the nature of peptide-membrane interactions and the stability of liposomes loaded with Leucinostatin-A, a Fourier Transform Infrared Spectroscopy study was performed. The results suggest that the mode of interaction of the peptide is dependent on its concentration, on bilayer fluidity, and on liposome type. Finally, the LD50 of both free and liposome-delivered Leucinostatin-A was determined in mice. These results suggest that the incorporation of Leucinostatin-A into liposomes may result in decreased Leucinostatin-A toxicity, as the intraperitoneal administration of Leucinostatin-A-loaded liposomes reduced the LD50 of Leucinostatin-A 15-fold.

Animals↗

PubMed2005

Differentiation of carbohydrate gums and mixtures using fourier transform infrared spectroscopy and chemometrics.

Guar gum, a nonionic galactomannan, is used as an economical thickener and stabilizer in the food industry and is often combined with xanthan, locust bean gum (LBG), or carboxymethylcellulose (CMC) to promote synergistic changes in viscosity or gelling behavior via intermolecular interactions; however, the adulteration of LBG with guar gum is a well-known industrial problem. The ability to identify the purity of gums and concentrations of individual gums in mixtures would be advantageous for quality control in the food industry. Fourier transform infrared spectroscopy (FTIR) methods are rapid and require minimum sample preparation. The objectives of this study were to evaluate the ability of FTIR techniques to (1) differentiate LBG with a variety of mannose/galactose (M/G) ratios, (2) differentiate guar, LBG, tara, and fenugreek gums, (3) differentiate pure guar gum from guar gum mixed with LBG, xanthan gum, or CMC, (4) quantify LBG, xanthan gum, and CMC in guar gum, and (5) quantify guar gum in LBG. Two FTIR methods were used: diffuse reflectance (DRIFT) on powdered gum samples added to KBr at 5%, w/w, and attenuated total reflectance (ATR) on 1%, w/w, gum solutions. Spectra were collected and then analyzed by multivariate statistical procedures (chemometrics). The DRIFT method provided better discrimination and quantitative results than the ATR method. Canonical variate analysis (CVA) of DRIFT spectra (1200-700 cm(-1)) was able to classify LBG with various M/G ratios, pure galactomannans, and pure versus mixtures of gums with 100% accuracy. Quantification of an individual gum in gum mixtures (0.5-15%, w/w) was possible using partial least-squares (PLS) analysis of DRIFT spectra with R2 > 0.93 and using this approach for quantifying guar gum added to LBG resulted in an R2 > 0.99, RMSEC = 0.29, and RMSEP = 3.31. Therefore, the DRIFT FTIR method could be a useful analytical tool for quality control of select gums and gum mixtures used in the food industry.

Carboxymethylcellulose Sodium↗

PubMed2006

Role of solvent on protein-matrix coupling in MbCO embedded in water-saccharide systems: a Fourier transform infrared spectroscopy study.

Embedding protein in sugar systems of low water content enables one to investigate the protein dynamic-structure function in matrixes whose rigidity is modulated by varying the content of residual water. Accordingly, studying the dynamics and structure thermal evolution of a protein in sugar systems of different hydration constitutes a tool for disentangling solvent rigidity from temperature effects. Furthermore, studies performed using different sugars may give information on how the detailed composition of the surrounding solvent affects the internal protein dynamics and structural evolution. In this work, we compare Fourier transform infrared spectroscopy measurements (300-20 K) on MbCO embedded in trehalose, sucrose, maltose, raffinose, and glucose matrixes of different water content. At all the water contents investigated, the protein-solvent coupling was tighter in trehalose than in the other sugars, thus suggesting a molecular basis for the trehalose peculiarity. These results are in line with the observation that protein-matrix phase separation takes place in lysozyme-lactose, whereas it is absent in lysozyme-trehalose systems; indeed, these behaviors may respectively be due to the lack or presence of suitable water-mediated hydrogen-bond networks, which match the protein surface to the surroundings. The above processes might be at the basis of pattern recognition in crowded living systems; indeed, hydration shells structural and dynamic matching is first needed for successful come together of interacting biomolecules.

Carbohydrate Conformation↗

PubMed2006

Evaluation of fetal bone structure and mineralization in IGF-I deficient mice using synchrotron radiation microtomography and Fourier transform infrared spectroscopy.

The role of insulin like growth factor-I (IGF-I) during pre-natal development has not been evaluated in detail. However, the high degree of growth retardation and peri-natal mortality in IGF-I deficient mouse models indicates that it plays a critical role during this time. Techniques to assess the structure and quality of bone in small animal fetuses could be beneficial in better understanding its role in bone metabolism and skeletal development. Synchrotron microtomography (SR-microCT) and Fourier transform infrared spectroscopy (FTIR) may provide methods to visualize and quantify differences in the structure and mineral density of bone in small animal fetuses. Tibia and spine from IGF-I deficient and wildtype fetal mice (18th day gestation) were imaged using SR-microCT. Three-dimensional structural indices and the degree of mineralization were determined for each sample. Mineralization was also assessed using FTIR and von Kossa staining. Bone volume was systematically lower in IGF-I -/- animals (tibia: -15%, p<0.05) while both sites were found to have a more rod-like architecture (24%, p<0.05; 113%, p<0.01) and lower trabecular separation (-16%, p<0.05; -21%, p<0.05). These structural results were mostly consistent with those seen in adult models of IGF-I deficiency. The degree of mineralization as measured by SR-microCT was higher in the IGF-I tibial metaphysis (11.7%, p<0.0001), while FTIR of the whole bone showed mineralization to be lower in the knockout group (-11%, p<0.05). Interestingly, von Kossa staining revealed no mineral content in the IGF-I -/- spinal ossification center while SR-microCT clearly indicated the presence of highly attenuating components, if somewhat lower in IGF-I -/- animals (-2.2%, p<0.05). This indicates that IGF-I deficiency is linked to subtle differences in the mineral environment and mineralization progression. The advantages unique to SR-microCT allow for 3D visualization and quantification of pre-natal bone microstructure and mineral density in mice which was not previously possible.

Animals↗

PubMed2003

Fourier transform infrared spectroscopy application to vascular biology: comparative analysis of human internal mammary artery and saphenous vein wall.

Saphenous vein (SV) and internal mammary artery (IMA) are used for aorto-coronary bypass grafting. IMA is considered to be the graft of choice for coronary revascularization having a long-term patency compared to SV. The aim of this study is to investigate the structure of vascular wall using a new technical approach. We analysed the chemical composition of vessel wall layers (total lipid, lipid ester and protein) of 25 vascular segments (19 SV and 6 IMA) using Fourier transform infrared spectroscopy (FTIR). FTIR analysis showed that in intima layer lipid ester and protein concentration (expressed as arbitrary units) was significantly higher in SV (lipid ester = 0.020 +/- 0.002; protein = 0.449 +/- 0.022) than in IMA (lipid ester = 0.014 +/- 0.002; protein = 0.342 +/- 0.032). Moreover, the percentage of lipid ester on total lipid was significantly higher in SV (intima = 54.7 +/- 2.9%; media = 78.4 +/- 4.9%; adventitia = 83.9 +/- 8.3%) wall layers compared to IMA ones (intima = 37.3 +/- 4.9%; media = 45.4 +/- 3.8; adventitia = 57.1 +/- 4.8). These data suggest that a different chemical composition of wall layers could also be responsible for the morphological modifications observed in SV after grafting.

Aged↗

PubMed2004

Differentiation of Micromonospora isolates from a coastal sediment in Wales on the basis of Fourier transform infrared spectroscopy, 16S rRNA sequence analysis, and the amplified fragment length polymorphism technique.

A number of actinomycetes isolates were recovered from coastal sediments in Aberystwyth (Wales, United Kingdom) with standard isolation techniques. Most of them were putatively assigned to the genera Streptomyces and Micromonospora on the basis of their morphological characteristics, and there appeared to be no difference whether the isolation media contained distilled water or seawater. A group of 20 Micromonospora isolates was selected to undergo further polyphasic taxonomic investigation. Three approaches were used to analyze the diversity of these isolates, 16S rDNA sequencing, fluorescent amplified fragment length polymorphism (AFLP), and Fourier transform infrared spectroscopy (FT-IR). The 16S rDNA sequence analysis confirmed that all of these isolates should be classified to the genus Micromonospora, and they were analyzed with a group of other Micromonospora 16S rDNA sequences available from the Ribosomal Database Project. The relationships of the 20 isolates were observed after hierarchical clustering, and almost identical clusters were obtained with these three techniques. This has obvious implications for high-throughput screening for novel actinomycetes because FT-IR spectroscopy, which is a rapid and reliable whole-organism fingerprinting method, can be applied as a very useful dereplication tool to indicate which environmental isolates have been cultured previously.

Bacterial Typing Techniques↗

PubMed1991

Secondary structure of the membrane-bound form of the pore-forming domain of colicin A. An attenuated total-reflection polarized Fourier-transform infrared spectroscopy study.

The structure of the pore-forming domain of the bacterial toxin colicin A was studied by attenuated total-reflection polarized Fourier-transform infrared spectroscopy. This channel-forming fragment interacts with dimyristoylglycerophosphoglycerol (Myr2GroPGro) vesicles and forms disk-like complexes. Analysis of the shape of the amide I' band indicates that its secondary structure is not affected by the pH 5.0-7.2. However, 5-10% of the peptide amino acids adopt an alpha-helical structure upon complex formation with Myr2GroPGro, while the random-coil and beta-sheet structure contents decrease. Interestingly, the increase in alpha-helical content is essentially due to an increase in the high-frequency component of the alpha-helical domain of amide I'. The fact that only this component was 90 degrees polarized (i.e. the helix is parallel to the acyl chain) suggests that only this particular type of helix is associated with the Myr2GroPGro bilayer.

Colicins↗

PubMed2004

Effects of unilateral sciatic neurectomy on growing rat femur as assessed by peripheral quantitative computed tomography, Fourier transform infrared spectroscopy and bending test.

We studied the effects of unilateral sciatic neurectomy (USN) on the development of the femoral shaft in the 30 growing Wistar-derived rats aged 5 weeks. Rats were allocated to three groups. One of these was immediately used for measurements, and the remaining 2 groups underwent USN of internal control. Specimens obtained from each group were divided into 2 subgroups: left femurs of each group served as the control subgroup (CONT) and right femurs from each group as the USN-operated subgroup (USN-OP). The bone mineral density (BMD), bone mineral content (BMC), bone area, periosteal circumference and endosteal circumference were measured by peripheral quantitative computed tomography (pQCT) and the mineral/matrix ratio was evaluated by Fourier transform infrared spectroscopy (FTIR). A three-point bending test was performed to analyze the biomechanical effects of sciatic neurectomy. USN-OP showed a significant decrease in cortical BMC, bone area, and periosteal circumference compared with CONT. The mineral/matrix ratio of cortical bone did not differ significantly between USN-OP and CONT. Strength and stiffness were significantly decreased in USN-OP compared with CONT. The results showed that USN inhibited periosteal bone formation, but has no significant effects on the mineral/matrix ratio of cortical bone in femurs.

Animals↗

PubMed1996

Structural properties of the putative fusion peptide of hepatitis B virus upon interaction with phospholipids. Circular dichroism and Fourier-transform infrared spectroscopy studies.

A peptide corresponding to the N-terminal sequence of the S protein from hepatitis B virus (Met-Glu-Asn-Ile-Thr-Ser-Gly-Phe-Leu-Gly-Pro-Leu-Leu-Val-Leu-Gln) has been previously shown to interact with phospholipids and promote vesicle aggregation, phospholipid mixing, and liposome leakage, as well as erythrocyte lysis [Rodríguez-Crespo, I., Núñez, E., Gómez-Gutiérrez, J., Yélamos, B., Albar, J. P., Peterson, D. L. & Gavilanes, F. (1995) J. Gen. Virol. 76, 301-308]. The conformation of this putative fusion peptide has been studied, both at low and high peptide concentrations, by means of circular dichroism and Fourier-transform infrared spectroscopy, respectively. When the peptide is dissolved in trifluoroethanol, a significant population of alpha-helical structure is found in spite of the proline residue at position 11. In contrast, this hydrophobic oligopeptide has a high tendency to form large beta-sheet aggregates in aqueous buffers. Most of these aggregates can be eliminated by centrifugation. The peptide remaining in the supernatant adopts a non-ordered conformation. The aggregates can be dissociated by the anionic detergent sodium cholate, but the peptide still maintains an extended conformation. In the presence of acidic phospholipid vesicles, the putative fusion peptide adopts a highly stable beta-sheet conformation. Thus, unlike the fusion peptides of other viruses, an extended conformation seems to be the preferred structure when interacting with phospholipids. Such a conformation should be responsible for its membrane destabilization properties.

Amino Acid Sequence↗

PubMed2000

Relationship between serum leptin immunoreactivity and body fat mass as estimated by use of a novel gas-phase Fourier transform infrared spectroscopy deuterium dilution method in cats.

OBJECTIVE: To validate a recently developed commercially available leptin radioimmunoassay (RIA) for use with feline serum and evaluate the relationship between serum leptin concentrations and body fat mass in domestic cats. ANIMALS: 19 sexually intact male specific-pathogen-free domestic cats that weighed 3.8 to 7.1 kg and were 1.1 to 3.5 years old. PROCEDURE: Specificity for feline leptin was evaluated by use of gel filtration chromatography and reverse-phase high-performance liquid chromatography fractionation of serum. Body fat mass was determined by use of the deuterium oxide (D2O) dilution method. Serum water D2O enrichment was measured by use of gas-phase Fourier transform infrared spectroscopy. RESULTS: Body fat mass and percentage body fat ranged from 0.3 to 2.3 kg and 7.5 to 34.9%, respectively. Serum leptin concentrations were lower in the unfed versus the fed state and ranged between 1.6 and 4.9 ng/ml human equivalent (HE); mean +/- SD value was 2.9 +/- 0.2 ng/ml HE. Leptin concentrations increased with increasing body fat mass and percentage of body fat. CONCLUSIONS: Leptin is in the serum of domestic cats in free (> 78%) and apparently bound forms. The relationship between body fat and serum leptin concentration was similar to that observed in humans and rodents and indicative of a lipostatic role for leptin in cats. Cats that have an overabundance of body fat appear to be less sensitive to the weight-normalizing action of leptin than cats of ideal body condition.

Adipose Tissue↗

PubMed2003

Fourier transform infrared spectroscopy studies of alginate-PLL capsules with varying compositions.

Microencapsulation of cells is a promising approach to prevention of rejection in the absence of immunosuppression. Clinical application, however, is hampered by insufficient insight into the factors that influence the biocompatibility of the capsules. Capsules prepared of alginates with a high guluronic (G) acid content proved to be more adequate for clinical application since they are more stable, but, unfortunately, they are less biocompatible than capsules prepared of intermediate-G alginate. In order to get some insight into the physicochemical factors that influence the biocompatibility of capsules for the encapsulation of living cells, the chemical compositions of alginate[bond]Ca beads and alginate[bond]PLL capsules were studied by Fourier transform infrared spectroscopy. We found that during the transition of the alginate[bond]Ca beads to alginate[bond]PLL capsules, Ca connecting the alginate molecules, disappeared at the surface of both high-G and intermediate-G alginate[bond]PLL capsules. At the same time, it turned out that high-G alginate[bond]PLL capsules contained more hydrogen bonding than did intermediate[bond]G alginate capsules. Thus the well-known higher stability of high-G alginate[bond]PLL compared to intermediate-G alginate[bond]PLL capsules is not caused by a higher degree of binding to Ca of the alginate molecules but rather by the presence of more hydrogen bonds. Another observation was that after the transition from bead to capsule, high-G alginate[bond]PLL capsules contained 20% more PLL than the intermediate-G alginate[bond]PLL capsules. Finally, we show that in both high-G and intermediate-G alginate[bond]PLL capsules, the PLL exists in the alpha-helix, in the antiparallel beta-sheet, and in the random coil conformation. This study shows that FT-IR allows for successful analyses of the chemical factors essential for understanding differences in the biocompatibility of alginate[bond]PLL capsules.

Alginates↗

PubMed2004

Fourier transform infrared spectroscopy on the Rap.RapGAP reaction, GTPase activation without an arginine finger.

GTPase activating proteins (GAPs) down-regulate Ras-like proteins by stimulating their GTP hydrolysis, and a malfunction of this reaction leads to disease formation. In most cases, the molecular mechanism of activation involves stabilization of a catalytic Gln and insertion of a catalytic Arg into the active site by GAP. Rap1 neither possesses a Gln nor does its cognate Rap-GAP employ an Arg. Recently it was proposed that RapGAP provides a catalytic Asn, which substitutes for the Gln found in all other Ras-like proteins (Daumke, O., Weyand, M., Chakrabarti, P. P., Vetter, I. R., and Wittinghofer, A. (2004) Nature 429, 197-201). Here, RapGAP-mediated activation has been investigated by time-resolved Fourier transform infrared spectroscopy. Although the intrinsic hydrolysis reactions of Rap and Ras are very similar, the GAP-catalyzed reaction shows unique features. RapGAP binding induces a GTP(*) conformation in which the three phosphate groups are oriented such that they are vibrationally coupled to each other, in contrast to what was seen in the intrinsic and the Ras.RasGAP reactions. However, the charge shift toward beta-phosphate observed with RasGAP was also observed for RapGAP. A GDP.P(i) intermediate accumulates in the GAP-catalyzed reaction, because the release of P(i) is eight times slower than the cleavage reaction, and significant GTP synthesis from GDP.P(i) was observed. Partial steps of the cleavage reaction are correlated with structural changes of protein side groups and backbone. Thus, the Rap.RapGAP catalytic machinery compensates for the absence of a cis-Gln by a trans-Asn and for the catalytic Arg by inducing a different GTP conformation that is more prone to be attacked by a water molecule.

Arginine↗

PubMed2000

Perspectives in the utilisation of Fourier-transform infrared spectroscopy of serum in sports medicine: health monitoring of athletes and prevention of doping.

Doping prevention is mainly directed to providing information on the dangers of doping to young athletes and to every profession concerned with athletic performance. Unfortunately, repression is also necessary in the fight against doping. Measurement of performance-enhancing drugs is complex, partly because of the large number of prohibited substances. A number of sophisticated analytical techniques are increasingly being used to provide the maximum detection time window. However, the effectiveness of methods to separate exogenous from endogenous biological molecules and the cost of antidoping analyses makes controls invalid or impossible. Moreover, most athletes, because of the metabolic and psychological stresses caused, legitimately refuse blood testing. It is becoming crucial to introduce new methods in the form of longitudinal health monitoring, since this is probably the most effective tool to prevent the use of doping agents when athletes become overtrained and/or overstressed. This paper describes new methods using Fourier-transform infrared spectroscopy to analyse serum from 50 microl samples of capillary blood. This technique has been shown to allow determination of the concentration of a wide range of biological molecules in a single microsample with clinically useful accuracy, and to provide a 'discriminatory biomolecular profile' to differentiate individuals on the basis of their physiological status. A specific application of this methodology is to perform longitudinal health monitoring in athletes, allowing prevention of overtraining. It is proposed to apply such methods in longitudinal studies for health monitoring and prevention of doping.

Doping in Sports↗

PubMed2001

Analysis of pulmonary surfactant by Fourier-transform infrared spectroscopy following exposure to Stachybotrys chartarum (atra) spores.

Lung cells are among the first tissues of the body to be exposed to air-borne environmental contaminants. Consequently the function of these cells may be altered before other cells are affected. As gas exchange takes place in the lungs, changes in cellular function may have serious implications for the processes of oxygen uptake and carbon dioxide elimination. In order for these processes to occur, the lung must maintain a high degree of expandability. This latter function is accomplished in part by the pulmonary surfactant which is synthesized and released by alveolar type II cells. Earlier studies have shown that exposure to gas phase materials such as smoke or organic solvents can alter the composition and function of the surfactant. The present study examines the ability of highly toxigenic mold spores to alter surfactant composition. Stachybotrys chartarum spores suspended in saline were instilled into mouse trachea as described earlier. After 24 h, the lungs were lavaged and the different processing stages of surfactant isolated by repeated centrifugation. Intracellular surfactant was isolated from the homogenized lung tissue by centrifugation on a discontinuous sucrose gradient. Samples were extracted into chloroform-methanol, dried and analyzed by Fourier-Transform infrared spectroscopy (FTIR). Exposure to S. chartarum induced an overall reduction of phospholipid among the three surfactant subfractions. The intermediate and spent surfactant fractions in particular were reduced to about half of the values observed in the saline-treated group. The relative distribution of phospholipid was also altered by spore exposure. Within the intracellular surfactant pool, higher levels of phospholipid were detected after spore exposure. In addition, changes were observed in the nature of the phospholipids. In particular strong intramolecular hydrogen bonding, together with other changes, suggested that spore exposure was associated with absence of an acyl chain esterified on the glycerol backbone, resulting in elevated levels of lysophospholipid in the samples. This study shows that mold spores and their products induce changes in regulation of both secretion and synthesis of surfactant, as well as alterations in the pattern of phospholipid targeting to the pulmonary surfactant pools.

Animals↗

PubMed1995

Molecular interaction of tubulin with 1-deaza-7,8-dihydropteridines: a comparative study of enantiomers NSC 613862 (S) and NSC 613863 (R) by Raman and Fourier transform infrared spectroscopy.

Pre-resonance Raman spectroscopy has been applied to compare the vibrational modes of the R and S chiral isomers of 1-deaza-7,8-dihydropteridine when they are bound to tubulin. The main Raman bands are due to the chromophore and are coupled with the pi-pi electronic transition of C = C and C = N vibrational stretching. On binding to tubulin, the Raman spectra of both isomers are modified. However, the modifications induced are different for each isomer. The Raman bands due to C = C stretching from the phenyl ring are more strongly modified for the bound R isomer than for the S isomer. This leads us to suggest that R and S isomers differ in terms of their orientation in front of the binding locus of tubulin. In fact, with respect to the orientation of the bulky methyl group, the chromophore of the R isomer is more likely to be positioned against the external surface of either tubulin or GTPase proteins, while that of the S isomer is likely to be positioned away from the surface. The conformational changes induced in tubulin by R and S isomers have also been studied by Fourier transform infrared spectroscopy and by the analysis of amide I and II absorption bands. Both enantiomers induce similar minor changes to the tubulin secondary structure, corresponding to a decrease in the disordered alpha-helical content and accompanied by an increase in the undefined conformation content.

Animals↗