SEARCH · PubMed Health

Results for “Spectroscopy, Fourier Transform Infrared”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources

PubMed1994

Structure and orientation of apo B-100 peptides into a lipid bilayer.

Peptides corresponding to lipid binding domains of Apo B-100 were synthesized, purified, and incubated with dimyristoylphosphatidylcholine (DMPC) liposomes. The secondary structure of the apo B-100 peptide-lipid complexes was evaluated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Those peptides belonging to the hydrophobic "core" domain of apo B-100 when associated with phospholipids were rich in beta sheet structure; a predominant alpha helical conformation was shown to be associated with one peptide located in a surface region of apo B-100. IR dichroic spectra revealed, in the case of the "core" peptides, that the beta sheet component is the only oriented structure with respect to the phospholipid acyl chains. This orientation of the beta sheet was recently found in LDL particles after proteolytic digestion by trypsin (Goormaghtigh, E., Cabiaux, V., De Meutter, J., Rosseneu, M., and Ruysschaert, J. M., 1993, Biochemistry 32, 6104-6110). Altogether, the data suggest that beta sheet, present in a high proportion in the native apo B-100, is probably another protein structure in addition to the amphipathic helix which strongly interacts with the lipid outer layer surrounding the LDL particle.

Apolipoprotein B-100↗

PubMed2006

Characterization of itraconazole semisolid dosage forms prepared by hot melt technique.

The objective of this study was to formulate itraconazole semisolid dosage forms and characterize their physicochemical properties. Itraconazole and excipients such as polysorbate 80, fatty acids, fatty alcohols, oils and organic acids were melted at 160 degrees C. The fused solution was then cooled immediately at -10 degrees C to make wax-like semisolid preparations. Their physicochemical attributes were first characterized using differential scanning calorimetry, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectrometry. The solubility of itraconazole in semisolid preparations and their dispersability in the simulated gastric fluid were also determined. Our semisolid preparations did not show any distinct endothermic peak of a crystalline form of itraconazole around 160-163 degrees C. This suggested that it was changed into amorphous one, when it was formulated into semisolid preparations. In addition, the distinctive functional peaks and chemical shifts of itraconazole were well retained after processing into semisolid preparations. It could be inferred from the data that itraconazole was stable during incorporation into semisolid preparations by the hot melt technique. In particular, itraconazole semisolid preparations composed of polysorbate 80, fatty acids and organic acids showed good solubility and dissolution when dispersed in an aqueous medium. It was anticipated that the semisolid dosage forms would be industrially applicable to improving the bioavailability of poorly water-soluble drugs.

Calorimetry, Differential Scanning↗

PubMed2006

Application of FT-IR for assessment of the biological stability of landfilled municipal solid waste (MSW) during in situ aeration.

Disposal of untreated municipal solid waste leads to gaseous emissions as well as liquid degradation products. In situ aeration is an emerging means for remediation of abandoned landfills. It aims at an accelerated mineralization and stabilization of waste organic matter and thus reduces significantly the emission potential of the site. In order to prove the success of the technique, evaluation of the biological stability of the aerated material has been suggested. Fourier Transform Infrared Spectroscopy (FT-IR) provides comprehensive information on the chemical composition of solid waste samples. Different stages of organic matter degradation are reflected by changes in the infrared spectral pattern. In the present study the feasibility of applying FT-IR for assessment of the stability of waste material derived from abandoned landfills and for in situ aeration process control was investigated. Waste samples derived in the course of pilot-scale and lab-scale aeration experiments were characterized by FT-IR (4000-400 cm(-1), KBr-technique, transmission mode) and a set of conventional parameters describing biological stability. The occurrence of distinct indicator bands was correlated with chemical and biological waste properties using 206 solid waste samples. Visual spectra interpretation was found to be appropriate in proving a reduced emission potential of initially rather reactive waste (respiration activity over 4 days (RA(4)) > 7 mg O(2) g(-1) DM) during aeration. Furthermore, cluster analysis was applied successfully to differentiate between original and aerated waste samples, even for rather stable material (RA(4) < 7 mg O(2) g(-1) DM), when visual spectra interpretation was limited.

Cluster Analysis↗

PubMed2006

Multifunctional polyvinylpyrrolidinone-polyacrylic acid copolymer hydrogels for biomedical applications.

Copolymers of N-vinylpyrrolidinone and acrylic acid, crosslinked with ethylene glycol dimethacrylate and polyethylene glycol 600 dimethacrylate were prepared by UV-polymerisation. These polymers were analysed for their extractable content by Soxhlet extraction of the samples at 100 degrees C for 72 h. Aspirin and paracetamol were incorporated into the polymer structure at 25 wt.% during the curing process and their presence confirmed by Fourier transform infrared spectroscopy. It was found that the release rate of the drug from the polymer matrix was dependent on intermolecular bonding between the polymer and active agent with aspirin being released slower than paracetamol in all cases. Results showed that paracetamol was completely released after 24h whereas complete release of aspirin took up to 70 h. Finally preliminary in vitro biocompatibility testing was performed for crosslinked polyvinylpyrrolidinone, by determining human hepatoma HepG2 cell viability in the MTT assay and DNA damage in the comet assay following direct contact with various concentrations of polyvinylpyrrolidinone-containing media. Cytotoxicity data suggests a dose-dependent effect for both crosslinkers, with concentrations in the range 0.025-2.5 mg ml(-1) showing a marginal decrease in viability to, at most, 70% that of untreated cells. Again DNA migration in the comet assay following short-term exposure to EGDMA crosslinked hydrogels correlates with MTT data.

Acetaminophen↗

PubMedDate not supplied

Lipid phase separation correlates with activation in platelets during chilling.

When human platelets are chilled below 22 degrees C, they spontaneously activate, a phenomenon that severely limits their storage life. It has previously been proposed that there is a correlation between cold-induced platelet activation and passage of the membranes through a liquid-crystalline to gel phase transition. Because animal models are essential for developing methods for cold storage of platelets, it is necessary to investigate such a correlation in animal platelets. In this work, horse platelets were used as a model, and it was found that cold-induced morphological activation is related to the lipid phase transition. Using fluorescence microscopy with the lipophilic fluorescent dye 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (Dil-C18), and Fourier transform infrared spectroscopy (FTIR), it was found that lipid phase separation occurs during cooling and low temperature storage. Furthermore, removal of cholesterol from the plasma membrane also induced a phase separation, possibly between specific phospholipid classes. Steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and trimethylammonium-DPH (TMA-DPH) were compared in cells and multilamellar vesicles (MLV) composed of platelet lipids. Cholesterol depletion led to a decrease in the fluorescence anisotropy of the two probes, which can be explained by changes in the order of the phospholipid molecules. In addition, the lipid composition and fatty acid profile of the cellular phospholipids were determined. Based of the similarities between horse and human platelets, it is suggested that horse platelets may be used as a model for studying cold-stored platelets. The results are discussed in relation to the possible role of phase separation during cell signalling.

Animals↗

PubMedDate not supplied

Chemical dissolution of gallstones in Taiwan: an in vitro study.

To evaluate the potential for the chemical dissolution of gallstones, 480 stones from 214 patients were studied. The stones were obtained via surgery or endoscopically. They were classified into cholesterol-rich mixed stones, brown pigment stones and black stones. The composition of bilirubin and cholesterol was determined by Fourier transformed infrared spectroscopy. Two per cent tetrasodium ethylenediamine acetate (EDTA), dimethylsulfoxide (DMSO) or methyl-tert-butyl-ethylene (MTBE) were used to dissolve the stones. To enhance solubility, surfactant polysorbate-20 was used to mix two of the individual three solvents. Methyl-tert-butyl-ethylene was found to have the best dissolution ability (by dry weight) 94, 13.4 and 20% for mixed, brown and black stones, respectively. Dimethylsulfoxide resulted in 13, 14 and 25% dissolution and EDTA 9.5, 13 and 16.5%. In contrast, pure water dissolved 4, 6 and 10.4% of the stones, respectively. A combination of the dissolution agents did not enhance the dissolution rate. In fact, the combination of solvents unexpectedly reduced the solubility of the stones: EDTA/MTBE was 17.5, 6.7 and 16.0%; DMSO/MTBE 43.2, 21.9 and 18.0%; DMSO/EDTA 9.1, 7.0 and 9.6%. In conclusion, cholesterol-rich mixed stones were able to be dissolved using MTBE but results of contact dissolution for gallstones are still far from satisfactory.

Cholelithiasis↗

PubMed1995

Intracerebral implantation of hydrogel-coupled adhesion peptides: tissue reaction.

Arg-Gly-Asp peptides (RGD) were synthesized and chemically coupled to the bulk of N-(2-hydroxypropyl) methacrylamide-based polymer hydrogels. Fourier Transform Infrared Spectroscopy (FTIR) and amino acid analysis confirmed the peptide coupling to the polymer. Activated and control (unmodified) polymer matrices were stereotaxically implanted in the striata of rat brains, and two months later the brains were processed for immunohistochemistry using antibodies for glial acidic fibrillary protein (GFAP), laminin and neurofilaments. RGD-containing polymer matrices promoted stronger adhesion to the host tissue than the unmodified polymer matrices. In addition, the RGD-grafted polymer implants promoted and supported the growth and spread of GFAP-positive glial tissue onto and into the hydrogels. Neurofilament-positive fibers were also seen running along the surface of the polymer and, in some instances, penetrating the matrix. These findings are discussed in the context of using bioactive polymers as a new approach for promoting tissue repair and axonal regeneration of damaged structures of the central nervous system.

Adhesives↗

PubMed1996

Characterization of the apatite crystals of bone and their maturation in osteoblast cell culture: comparison with native bone crystals.

Calcium phosphate crystals deposited in the organic matrix synthesized by chick bone osteoblasts in culture were studied by x-ray and electron diffraction, Fourier transform infrared spectroscopy and chemical composition. The amounts of mineral phase deposited with time and the extent of calcification (% of mineral phase in the tissue) were also determined as a function of time, as were the nature of the changes in the short range order of the crystals. The amount of mineral deposited and the extent of calcification increased with time; the tissue not only contained more crystals of apatite, but the extent of calcification also increased with time as it does in vivo. After 30 days of culture the extent of calcification in the cell culture matrix was similar to that in late chick embryonic and early postnatal chick tibiae. The nature of the CO3 and HPD4 environments were similar to those found in vivo although the concentrations of these ions and the changes in their concentrations with time appeared to develop more slowly in cell culture than they do in vivo. However, the general overall pathway of maturation was similar in cell culture to that observed in vivo.

Animals↗

PubMed2006

The in-vitro bioactivity of mesoporous bioactive glasses.

Ordered mesoporous bioactive glasses (MBGs) with different compositions were prepared by using nonionic block copolymer surfactants as structure-directing agents through an evaporation-induced self-assembly process. Their in-vitro bioactivities were studied in detail by electron microscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma (ICP) atomic emission spectroscopy. The ICP element analysis results were further calculated in terms of the total consumption of Ca and P, Delta[Ca]/Delta[P] ratios, and ionic activity product (IP) of hydroxyapatite. Through the above analysis, it is clear that MBGs show a different structure-bioactivity correlation compared to conventional sol-gel-derived BGs. The in vitro bioactivity of MBGs is dependent on the Si/Ca ratio in the network when the other material parameters such as the mesostructure and texture properties (pore size, pore volume) are controlled. MBG 80S15C with relatively lower calcium content exhibits the best in vitro bioactivity, in contrast to conventional sol-gel-derived BGs where usually higher calcium percentage BGs (e.g. 60S35C) show better bioactivity. Calcination temperature is another important factor that influences the in vitro bioactivity. According to our results, MBGs calcined at 973K may possess the best in vitro bioactivity. The influences of the composition and calcination temperature upon bioactivity are explained in terms of the unique structures of MBGs.

Bone Substitutes↗

PubMed1995

Microbial attachment on orthodontic appliances: I. Wettability and early pellicle formation on bracket materials.

The objectives of this study were to investigate the wettability of orthodontic bracket material surfaces and the composition of salivary films adsorbed onto them after 30 and 60 minutes in vivo exposure. Specimens from stainless steel, fiber-reinforced polycarbonate, and polycrystalline alumina bracket manufacturing raw materials were subjected to (a) contact angle measurements with a homologous series of liquids, (b) micro multiple internal reflection Fourier transform infrared spectroscopy (microMIR FTIR) for the characterization of the molecular composition of the in vivo adsorbed groups, and (c) incident light optical microscopy of the acquired films. The highest critical surface tension was obtained from stainless steel (40.8 +/- 0.4 dynes/cm) followed by polycarbonate (32.8 +/- 1.3 dynes/cm) and alumina (29.0 +/- 0.9 dynes/cm), suggesting a higher potential for increased plaque-retaining capacity for the stainless steel brackets. Accordingly, the total work of adhesion and its polar and nonpolar components were consistent with the surface tension ranking. The nonpolar component of the work of adhesion was higher than its polar counterpart for all materials tested, implying a possible higher attachment prevalence for those microorganisms using dispersive forces, such as van der Waals forces, as the predominant attachment mechanism to surfaces. Qualitative and quantitative variations were observed in the adsorbed films after 30 and 60 minutes intraoral exposure that may reflect the influence of the surface properties of these substrates on the structure of the pellicle formed in vivo.

Adhesiveness↗

PubMed2006

Interaction and properties of highly exfoliated soy protein/montmorillonite nanocomposites.

The soy protein isolate (SPI)/ Na+ -montmorillonite (MMT) plastics were successfully prepared, and their structures and properties were characterized with X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and tensile testing. The interactions between the soy protein macromolecules and MMT in aqueous media were analyzed with zeta-potential measurements, Fourier transform infrared spectroscopy, and electrostatic surface potential calculations. The results revealed that the heterogeneous distribution of the surface positive charges provided the positive-charge-rich domains for the soy globulins bearing net negative charges to anchor into the negatively charged MMT galleries. There were electrostatic attraction and hydrogen bonding interactions on the interfaces of the soy protein and MMT, which led to the good dispersion of the phyllosilicate layers in the protein matrix. The highly exfoliated MMT layers with a dimension of 1-2 nm in thickness were randomly dispersed in the protein matrix containing MMT lower than 12 wt %, whereas the intercalated structure was predominant when the MMT content was higher than 12 wt %. Consequently, the fine dispersion of the MMT layers and the strong interactions between SPI and MMT created the significant improvement of the mechanical strength and thermo-stability of the SPI/MMT plastics. In addition, a schematic illustration was proposed to describe the electrostatic interaction between SPI and MMT as well as the correlation between the interaction and structure in protein/clay systems.

Bentonite↗

PubMed2001

Intraoral aging of the inner headgear component: a potential biocompatibility concern?

The effect of intraoral aging of biomaterials on the modification of their surface properties has mostly been unknown. The purpose of this study was to investigate and characterize surface alterations of retrieved inner face-bow headgear components. Specimens were prepared from 3 areas of retrieved headgear wires: inner-outer face-bow soldered junction, buccal segment, and projection entering the buccal tube. Specimens from as-received headgear wires that matched the brand and size of the retrieved wires were also fabricated; all specimens were then subjected to multitechnique characterization. Optical microscopy revealed extensive biofilm islands of amorphous precipitants and accumulated microcrystalline particles. Micro-multiple internal reflectance Fourier transform infrared spectroscopy investigation of the retrieved wire samples demonstrated the presence of a proteinaceous biofilm, the organic constituents of which were mainly amide, alcohol, and carbonate. Scanning electron microscopy and radiographic microanalysis showed that the elemental species precipitated on the material surface were mainly calcium and phosphorus, forming calcium-phosphorus precipitates with thicknesses reaching 300 microm, whereas radiograph fluorescence spectrometry provided evidence of integument calcification through identification of calcium and phosphorus peaks. The clinical implication of the aging pattern that was identified relates to the potential protective role or induction of disintegration by the biofilm adsorbed on the wire that affected the biocompatibility of the alloy. Whereas further investigation is suggested for the clarification of the effect of intraoral aging on ionic release, the results of this study emphasize the necessity for the incorporation of in vivo approaches, including retrieval analyses, in the study of the biologic performance of orthodontic materials.

Adolescent↗

PubMedDate not supplied

Influence of interchanging adhesive resins and self-etching primers on the mechanical properties of adhesive resins.

This study determined the influence of interchanging adhesive resins and self-etching primers on the mechanical properties of adhesive resins. Four commercially available two-step self-etching primer systems were used. To measure microtensile strength, 0.5-mm thick dumbbell-shaped slabs of each combination of adhesive resin and self-etching primer were prepared. After 24 hours storage in 37 degrees C distilled water, these specimens were subjected to microtensile testing at a crosshead speed of 1.0 mm/minute. Fourier transformation infrared spectroscopy was used to determine the degree of conversion. The percentage of residual double bonds, including pendant and monomeric double bonds, was calculated by comparing the obtained ratio against uncured adhesive resin. The degree of conversion of the adhesive resins was obtained by subtracting the %C=C from 100%. Two-way ANOVAs, followed by Tukey tests, were done. The microtensile strengths and degree of conversion varied with different combinations of self-etching primer and adhesive resin. Numerically, the highest microtensile strengths were obtained when the primer/adhesive resin combinations from the same manufacturer were used. When the different combinations of self-etching primers and adhesive resins were mixed, the microtensile strength and degree of conversion of the adhesive resins tended to decrease for some combinations. Within the limitations of this study, which was far removed from clinical situations, the role of the self-etching primers on the mechanical properties of adhesive resins should be considered to create an authentic resin-dentin interface.

Analysis of Variance↗

PubMed1995

An infrared investigation of palmitoyl-coenzyme A and palmitoylcarnitine interaction with perdeuterated-chain phospholipid bilayers.

Mixtures of di-(perdeuteropalmitoyl)-sn-glycero-3 choline ([2H62]Pam2GroPCho) with palmitoylcarnitine or palmitoyl-CoA in aqueous suspension have been examined by Fourier-transform infrared spectroscopy. The C-H (or C-D) region of the spectrum shows that an order-disorder transition exists in pure aqueous palmitoylcarnitine at 45 degrees C; palmitoylcarnitine mixes with [2H62]Pam2GroPCho without perturbing the gel-fluid transition of the phospholipid even at [2H62]Pam2GroPCho/palmitoylcarnitine 1:2 molar ratios; and palmitoyl-CoA, however, at similar proportions, smears out the [2H62]Pam2GroPCho transition as detected from C-D stretching vibrations. Relevant data from the carbonyl region include; the high-frequency (non-hydrogen bound) carbonyl subpopulation, but not the low frequency one, detects the gel-to-fluid transition of the phospholipid; the carbonyl region detects the thermotropic transition over a wider temperature range than the methylene stretching region, i.e. detects changes starting well below and ending several degrees above the methylene transition temperature, and a significant interaction may occur between some coenzyme A group and the carbonyl groups of the phospholipid. The latter interaction may contribute to explain the coenzyme A/carnitine exchange during mitochondrial fatty acid import.

Deuterium↗

PubMed2006

Spectroscopic and biochemical analysis of regions of the cell wall of the unicellular 'mannan weed', Acetabularia acetabulum.

Although the Dasycladalean alga Acetabularia acetabulum has long been known to contain mannan-rich walls, it is not known to what extent wall composition varies as a function of the elaborate cellular differentiation of this cell, nor has it been determined what other polysaccharides accompany the mannans. Cell walls were prepared from rhizoids, stalks, hairs, hair scars, apical septa, gametophores and gametangia, subjected to nuclear magnetic resonance and Fourier transform infrared spectroscopy, and analyzed for monosaccharide composition and linkage, although material limitations prevented some cell regions from being analyzed by some of the methods. In diplophase, walls contain a para-crystalline mannan, with other polysaccharides accounting for 10-20% of the wall mass; in haplophase, gametangia have a cellulosic wall, with mannans and other polymers representing about a quarter of the mass. In the walls of the diplophase, the mannan appears less crystalline than typical of cellulose. The walls of both diploid and haploid phases contain little if any xyloglucan or pectic polysaccharides, but appear to contain small amounts of a homorhamnan, galactomannans and glucogalactomannans, and branched xylans. These ancillary polysaccharides are approximately as abundant in the cellulose-rich gametangia as in the mannan-rich diplophase. In the diplophase, different regions of the cell differ modestly but reproducibly in the composition of the cell wall. These results suggest unique cell wall architecture for the mannan-rich cell walls of the Dasycladales.

Acetabularia↗

PubMed2005

Co-adsorption of cadmium(II) and glyphosate at the water-manganite (gamma-MnOOH) interface.

The co-adsorption of Cd(II) and glyphosate (N-(phosphonomethyl)glycine, PMG) at the manganite (gamma-MnOOH) surface has been studied in the pH range 6-10 at 25 degrees C and with 0.1 M Na(Cl) as ionic medium. Batch adsorption experiments, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used for the quantitative analysis and the determination of the molecular structure of the surface complexes. The adsorption of Cd(II) and PMG in the ternary Cd(II)-PMG-manganite system was compared with the adsorption in the binary Cd(II)-manganite and PMG-manganite systems. The formation of three inner sphere surface complexes was observed, a ternary Cd(II)-PMG-manganite complex, a binary Cd(II)-manganite complex and a binary PMG-manganite complex. The surface concentration of the ternary complex and the Cd(II)-manganite complex was more or less constant throughout the pH range studied. However, the surface concentration of the binary PMG-manganite complex decreased with increasing pH. The major part of the binary PMG-surface complex was protonated. The ternary surface complex displayed a type B structure (Cd(II)-PMG-manganite). The average Cd-Mn distance obtained from EXAFS (3.26 A) indicates that the binary and ternary Cd(II)-surface complexes are formed by edge-sharing of Mn and Cd octahedra on the (010) plane of the manganite crystals.

Adsorption↗

PubMed2006

Removal of cadmium from aqueous solutions by adsorption onto orange waste.

The use of orange wastes, generated in the orange juice industry, for removing cadmium from aqueous solutions has been investigated. The material was characterized by Fourier transform infrared spectroscopy and batch experiments were conducted to determine the adsorption capacity of the biomass. A strong dependence of the adsorption capacity on pH was observed, the capacity increasing as pH value rose. Kinetics and adsorption equilibrium were studied at different pH values (4-6). The adsorption process was quick and the equilibrium was attained within 3h. The maximum adsorption capacity of orange waste was found to be 0.40, 0.41 and 0.43 mmol/g at pH 4-6, respectively. The kinetic data were analysed using various kinetic models - pseudo-first order equation, pseudo-second order equation, Elovich equation and intraparticle diffusion equation - and the equilibrium data were tested using four isotherm models - Langmuir, Freundlich, Sips and Redlich-Peterson. The data were fitted by non-linear regression and five error analysis methods were used to evaluate the goodness of the fit. The Elovich equation provides the greatest accuracy for the kinetic data and the Sips model the closest fit for the equilibrium data.

Adsorption↗

PubMed2000

Age-related changes in the chemical composition of gallstones.

BACKGROUND: The association between pigment cholelithiasis and advancing age has been previously described but little is known about the time-course of these changes. AIM: To determine the specific changes that occur in the chemical composition of gallstones with increasing age. METHODS: Gallstones were collected from 387 non-cirrhotic patients and visually classified as either cholesterol or pigment. All stones were quantitatively analyzed by Fourier transform infrared spectroscopy for cholesterol, bilirubin, carbonate and phosphate and the results correlated with stone type and patient age. RESULTS: Forty-five patients had pigment stones (12 %) and 342 had cholesterol stones (88 %). No patient had both types. There was a reciprocal relationship between the mean cholesterol and bilirubin contents of stones over time with cholesterol accounting for 54% of the weight of gallstones before age 30 and only 17% after age 70. Similarly, the mean content (by weight) of bilirubin was 35% before age 30 but 61% after age 70. In addition, the fraction of gallstones containing carbonate or phosphate salts increased sequentially with age (6% at age 30 to 57% at age 70). CONCLUSIONS: (1). The ratio of pigment to cholesterol gallstones increases directly with age. (2) The cholesterol content of stones steadily decreases after age 50 while the content of bilirubin, phosphate and carbonate gradually increases. (3) These data suggest that, during aging, cholesterol may become solubilized and may be replaced by calcium salts of carbonate, phosphate or bilirubinate.

Adult↗