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At least 271 records · Page 15Linked to original sources
PubMed2001

Characterization of compression-molded UHMWPE, PMMA and PMMA/MMA treated UHMWPE: density measurement, FTIR-ATR, and DSC.

Considered one of the weak links in the total hip replacement (THR), efforts to enhance the interfacial strength between bone cement and ultra-high molecular weight polyethylene (UHMWPE) acetabular cup had been conducted in this laboratory. Following the successful demonstration of high interfacial strengths for our new acetabular component design, the nature of physical, chemical, and thermal property of the compression-molded specimens, including UHMWPE, PMMA/MMA treated UHMWPE, and PMMA has been investigated in this study. Density results from a density gradient column showed that the molding processes and conditions were adequate for complete sintering of UHMWPE and PMMA powders. FTIR-ATR results gave a direct evidence that PMMA did exist in the PMMA/MMA treated UHMWPE matrix. It also revealed a clear diffusion-related behavior across the interface. Under the high temperature and pressure, the UHMWPE powders undergo drastic changes of their morphology and crystalline structures. These changes were examined by differential scanning calorimeter (DSC) which showed a large difference in terms of % crystallinity. The percent of PMMA deposited in the treated UHMWPE was 17.8%, 18.8%, and 24.3% from the analyses of density, FTIR-ATR, and DSC, respectively. Finally, an evidence of diffusive behavior at the interface exhibited diffusion of PMMA occurring across the interfaces between the treated UHMWPE and UHMWPE or PMMA.

Bone Cements↗
PubMed1993

De novo truncation of chromosome 16p and healing with (TTAGGG)n in the alpha-thalassemia/mental retardation syndrome (ATR-16).

We have previously described a series of patients in whom the deletion of 1-2 megabases (Mb) of DNA from the tip of the short arm of chromosome 16 (band 16p13.3) is associated with alpha-thalassemia/mental retardation syndrome (ATR-16). We now show that one of these patients has a de novo truncation of the terminal 2 Mb of chromosome 16p and that telomeric sequence (TTAGGG)n has been added at the site of breakage. This suggests that the chromosomal break, which is paternal in origin and which probably arose at meiosis, has been stabilized in vivo by the direct addition of the telomeric sequence. Sequence comparisons of this breakpoint with that of a previously described chromosomal truncation (alpha alpha)TI do not reveal extensive sequence homology. However, both breakpoints show minimal complementarity (3-4 bp) to the proposed RNA template of human telomerase at the site at which telomere repeats have been added. Unlike previously characterized individuals with ATR-16, the clinical features of this patient appear to be solely due to monosomy for the terminal portion of 16p13.3. The identification of further patients with "pure" monosomy for the tip of chromosome 16p will be important for defining the loci contributing to the phenotype of this syndrome.

Adult↗
PubMed1996

Splicing mutation in the ATR-X gene can lead to a dysmorphic mental retardation phenotype without alpha-thalassemia.

We have previously reported the isolation of a gene from Xq13 that codes for a putative regulator of transcription (XNP) and has now been shown to be the gene involved in the X-linked alpha-thalassemia with mental retardation (ATR-X) syndrome. The widespread expression and numerous domains present in the putative protein suggest that this gene could be involved in other phenotypes. The predominant expression of the gene in the developing brain, as well as its association with neuron differentiation, indicates that mutations of this gene might result in a mental retardation (MR) phenotype. In this paper we present a family with a splice junction mutation in XNP that results in the skipping of an exon and in the introduction of a stop codon in the middle of the XNP-coding sequence. Only the abnormal transcript is expressed in two first cousins presenting the classic ATR-X phenotype (with alpha-thalassemia and HbH inclusions). In a distant cousin presenting a similar dysmorphic MR phenotype but not having thalassemia, approximately 30% of the XNP transcripts are normal. These data demonstrate that the mode of action of the XNP gene product on globin expression is distinct from its mode of action in brain development and facial morphogenesis and suggest that other dysmorphic mental retardation phenotypes, such as Juberg-Marsidi or some sporadic cases of Coffin-Lowry, could be due to mutations in XNP.

Abnormalities, Multiple↗
PubMed1998

[Three Japanese children with X-linked alpha-thalassemia/mental retardation syndrome (ATR-X)].

X-linked alpha-thalassemia/mental retardation syndrome (ATR-X), which was first reported by Wilkie, et al. in 1991, is a disorder with severe mental retardation, characteristic facial appearance, genital abnormalities, and mild form of alpha-thalassemia. At present, about 50 cases have been reported in the world, but few in Japan. We report 3 cases of this disorder in 2 families. All cases prefer a peculiar posture and show unique movements, such as self-induced vomiting or self-hanging, which can be diagnostic. ATR-X should be considered as a differential diagnosis in all male patients with severe mental retardation.

Child↗
PubMed2026

Anoxia tolerant DNA replication is supported by ATR kinase in the annual killifish Austrofundulus limnaeus.

Hypoxia and anoxia suppress cell proliferation due to an increase in replication stress and activation of DNA damage checkpoints. Embryos of the annual killifish Austrofundulus limnaeus tolerate prolonged anoxia, indicating improved genomic stability under oxygen starvation. We investigated the cell cycle regulation of the anoxia tolerant killifish embryonic cell line PSU-AL-WS40NE during anoxia. Live-cell imaging confirms continued proliferation of WS40NE cells for the first 24 h of anoxia with minimal cell death. Fluorescence imaging shows that cells accumulate in G1 after the first day in anoxia with a rapid entry into S phase upon reoxygenation. Pharmacological inhibition shows a reliance on ataxia telangiectasia and Rad3 related (ATR) signaling, suggesting that increased γH2AX levels are driven by replication stress instead of DNA damage. This conclusion is supported by a lack of induction of a G2 checkpoint, suggesting minimal DNA damage during anoxic exposure. Maintaining cellular proliferation during anoxia and accumulating cells in the G1 phase for extended anoxic exposure is likely one way that embryos of the killifish can survive prolonged anoxia, which provides insight into mechanisms that enable cells to proliferate under metabolic stress.

Animals↗
PubMed2000

Molecular-clinical spectrum of the ATR-X syndrome.

Since the identification of the ATRX gene (synonyms XNP, XH2) in 1995, it has been shown to be the disease gene for numerous forms of syndromal X-linked mental retardation [X-linked alpha thalassemia/mental retardation (ATR-X) syndrome, Carpenter syndrome, Juberg-Marsidi syndrome, Smith-Fineman-Myers syndrome, X-linked mental retardation with spastic paraplegia]. An attempt is made in this article to review the clinical spectrum associated with ATRX mutations and to analyse the evidence for any genotype/phenotype correlation.

Abnormalities, Multiple↗
PubMed1995

Male pseudohermaphroditism in sibs with the alpha-thalassemia/mental retardation (ATR-X) syndrome.

Genital abnormalities have been noted in several patients with the X-linked form of alpha-thalassemia and mental retardation syndrome (ATR-X). The initial clinical report of the condition documented a phenotypic female with 46,XY karyotype. To this we now add 2 further siblings with abnormalities of the external genitalia, manifesting as male pseudohermaphroditism.

Abnormalities, Multiple↗
PubMed1995

Clinical and hematologic aspects of the X-linked alpha-thalassemia/mental retardation syndrome (ATR-X).

The hallmarks of the X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome are severe psychomotor retardation, minor facial anomalies, genital abnormalities, and an unusual form of alpha-thalassemia. The demonstration of HbH inclusions in red blood cells after incubation with brilliant cresyl blue confirms the diagnosis. We describe 15 previously unreported cases and analyse the phenotypic and hematologic findings in these subjects and compare them with previously published cases. This study demonstrates the consistency of the main characteristics of this syndrome and extends the phenotype. Developmental changes in phenotype, in particular the coarsening of the facial appearance, are illustrated. The hematologic findings are shown to vary widely; in some cases the manifestation of alpha-thalassemia may be subtle and missed without repeated examination.

Abnormalities, Multiple↗
PubMed1986

Quantitative surface analysis of Cardiothane 51 by FT-IR-ATR spectroscopy.

Surface analysis has been carried out for Cardiothane 51 samples as commercially available balloon pumps and cast films prepared from the solution. Silicone contents on surfaces have been quantitatively determined by FT-IR-ATR spectroscopy coupled with a subtraction technique. The contents on the air-facing surface vary from 0.7 to 5.3% among six balloon pumps examined; three of them contain less silicone on the air-facing surface than on the substrate-facing surface, whereas just the opposite is true for one, and the other two have nearly and quite an equal content of it between the two surfaces. Silicone contents on surfaces of cast films vary also from a sample to another even when sample films were prepared from the same Cardiothane solution, indicating difficulty in quality control of Cardiothane surfaces. An appreciable fraction of silicone was found not to be covalently bonded to polyurethane in Cardiothane 51 for the cast film samples.

Biocompatible Materials↗
PubMedDate not supplied

Detection of creatinine enriched on a surface imprinted polystyrene film using FT-ATR-IR.

The surface of polystyrene (PS) was chemically modified by coating a thin layer of polyaniline (PANI) by oxidizing aniline using ammonium persulfate. Affinity sites for creatinine, a clinically relevant molecule, were created in the coated layer by adding creatinine as print molecules during the oxidation. The imprinted layer adsorbed creatinine was compared to non-imprinted surface reflecting the creation of creatinine-specific sites on the surface. The equilibrium was attained rapidly, indicating that a material of this kind is suitable for sensing applications. The adsorbed creatinine on the surface was detected using the technique of Fourier transform attenuated total internal reflection infra red spectroscopy (FT-ATR-IR). The results show that molecularly imprinted surface can enrich molecules of interest and the enriched molecules can be detected using FT-IR.

Adsorption↗
PubMed2004

The effect of solvent on permeant diffusion through membranes studied using ATR-FTIR and chemometric data analysis.

One method of improving the bioavailability of a topical formulation is to add an appropriate solvent that will act as a solubilizer for the permeant and, at the same time, modify the barrier properties of the stratum corneum. It has proved very difficult to determine the precise mechanisms of action involved; this is complicated by the concurrent diffusion of the solvent and the permeant into the skin. Under these circumstances the barrier function may well be changing as a function of time as the solvent disrupts it. We have observed this phenomenon in a model silicone membrane system that we have chosen to study initially to avoid the complexity of the heterogeneous nature of skin and its inherent biological variability. Diffusion experiments were conducted using an established ATR-FTIR approach but the data interpreted using sophisticated chemometric approaches that allowed us to deconvolve the IR signals from the permeant, the solvent, and the membrane. Data are presented that show the concurrent diffusion of benzoic acid (permeant), octanol (solvent), and how the octanol modifies the characteristics of the silicone membrane. Initial data are then presented using human skin to show the power of the diffusion approach coupled to the data deconvolution technique.

Diffusion↗
PubMed1999

An in Situ ATR-FTIR Investigation of Sulfate Bonding Mechanisms on Goethite.

The mechanism of sulfate adsorption on goethite was investigated in situ using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Sulfate adsorption was investigated at ionic strengths between 0.005 and 0.1 M, reactant concentrations between 5 and 500 µM, and pH values between 3.5 and 9.0. It was determined that sulfate forms both outer-sphere and inner-sphere surface complexes on goethite at pH less than 6. At pH values greater than 6, sulfate adsorbs on goethite only as an outer-sphere complex. The relative amount of outer-sphere sulfate surface complexation increased with decreasing ionic strength. The spectrum of sulfate adsorbed on goethite was also compared to the infrared spectrum of synthetic schwertmannite, an iron(III) oxy-hydroxy-sulfate. It was determined that in situ spectra of both schwertmannite and adsorbed sulfate are quite similar, suggesting that a continuum of outer- and inner-sphere sulfate occurs in both cases. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

ATR-FTIR Study of IgG Adsorbed on Different Silica Surfaces.

Thesecondary structure of adsorbed immunoglobulin G (IgG) on different silica surfaces (hydrophilic, hydrophobic, hydrophobic with preadsorbed triblock-copolymers consisting of a polypropylene oxide buoy and two polyethylene oxide chains dangling in the solution) is studied by ATR-FTIR. Some results for adsorbed bovine serum albumin (BSA) are also presented. The secondary structure of adsorbed IgG was quantified using second-derivative spectra for the input parameters of the curve-fitting analysis of the original spectra. The secondary structure of adsorbed IgG on a hydrophilic silica surface resembles that of IgG in solution (about 60% beta-sheet and almost no alpha-helix content). There is some loss in the helix content of BSA after adsorption on the hydrophilic surface, but this structural element is still the most important one in the adsorbed protein. The IR spectra of the adsorbed proteins on the hydrophobic silica surface can not be interpreted, probably because of a large contribution to the IR signal of water molecules that are exchanged against the proteins during adsorption. The presence of preadsorbed triblock-copolymers reduces the adsorbed amount and causes an effect on the adsorbed proteins similar to that exerted by ethylene glycol: a different type of beta-sheet structure in IgG and a more ordered alpha-helix structure in BSA are provoked. Copyright 1999 Academic Press.

Journal Article↗
PubMed2000

Secondary structure of chorion proteins of the teleostean fish Dentex dentex by ATR FT-IR and FT-Raman spectroscopy.

FT-Raman spectroscopy and ATR-IR spectroscopy were applied to study the secondary structure of the eggshell (chorion) proteins of the teleostean fish Dentex dentex. Raman and IR spectra clearly indicate an abundance of antiparallel beta-pleated sheet conformation in chorion proteins. This finding is further supported by analysis of the vibrational data by regression techniques and deconvolution procedures. Thus, the common morphological characteristics of D. dentex, Salmo gairdneri, and other teleostean fish chorions may be explained on the basis of common secondary structure features of their constituent proteins. A detailed understanding of the interactions that dictate the self-assembly of fish chorion proteins to form the fish eggshell awaits determination of amino acid sequences.

Animals↗
PubMed2006

Evaluation of the application of attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) and chemometrics to the determination of nutritional parameters of yogurt samples.

A critical evaluation of the application of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and partial least squares (PLS) to the determination of several nutritional parameters, such as the energetic value and the carbohydrate, protein and calcium contents, in commercially available yogurt samples was carried out. To this end, a highly heterogeneous population of 48 samples covering a wide range of yogurts obtained from the Spanish market was used. After correcting the spectra, hierarchical cluster analysis was performed in order to select a representative calibration set and the corresponding validation sample set. Different PLS models and several spectral windows were tested in order to evaluate their prediction capabilities for the validation set. For all nutritional parameters, with the exception of fat content, the procedure developed here provided good precision; the values obtained complied with the statutory values declared by the US FDA.

Calcium↗
PubMed1999

pH-dependent secondary conformation of bovine lens alpha-crystallin: ATR infrared spectroscopic study with second-derivative analysis.

BACKGROUND: In order to simulate the usage of different formulations of ophthalmic solution, the protein conformational changes of lens alpha-crystallin in buffer solutions of different pH were investigated. METHODS: The secondary structure of bovine lens alpha-crystallin in different Mcllvaine buffer solutions (pH 2.2, 4.0, 6.0, 7.2 and 8.0) was determined by attenuated total reflection (ATR)/Fourier transform infrared (FT-IR) spectrometry with second-derivative technique. The turbidity of alpha-crystallin in different buffer solutions was observed. RESULTS AND CONCLUSION: The results indicate that alpha-crystallin exists mainly in beta-sheet structure at 1627-1637 cm-1. The conformational components of alpha-crystallin may be closely similar in pH 7.2 buffer solution and in pH 8.0 buffer solution. Once alpha-crystallin dissolved in pH 6.0 and 4.0 buffer solution, the appearance of a component at 1618 or 1620 cm-1, associated with the presence of intermolecular beta-sheet structure or beta-turn structure or amino acid side chains, implied the denaturation of alpha-crystallin, which was even more marked in pH 4.0 buffer solution. Due to the effect of dissociation and stability of alpha-crystallin in pH 2.2 buffer solution, the secondary structure of the intact alpha-crystallin was difficult to evaluate. This study demonstrates that different pH can vary secondary conformational structure of alpha-crystallin, particularly if the pH is below 6.0. This suggests that the secondary structure of alpha-crystallin in buffer solution exhibits pH-dependent characteristics.

Acids↗
PubMed1993

Interaction of myelin basic protein with single bilayers on a solid support: an NMR, DSC and polarized infrared ATR study.

The interaction of myelin basic protein (MBP) with single bilayers on a solid support (planar and spherical support) is studied by deuterium nuclear magnetic resonance (2H-NMR), differential scanning calorimetry (DSC) and polarized attenuated total reflection infrared spectroscopy (ATR-IR). The single bilayer consisted of either DMPC or of a binary mixture of DMPC with 10-20 mol% of an acidic phospholipid (DMPG, DMPS or DMPA). All methods applied indicate that MBP strongly interacts with the binary lipid systems but not with the pure DMPC bilayers. The interaction is predominantly electrostatic in nature and does not depend on the choice of a particular acidic lipid (for the binary systems). In particular, the results give no indication for a hydrophobic interaction of MBP with the membrane. Our data provide evidence that, in contrast to previous findings, no demixing and/or domain formation in the binary systems is induced due to the MBP coupling. The infrared order parameter was determined for both lipid components of the binary systems and shows a remarkable change for both lipids due to the interaction with MBP while the NMR order parameter remained essentially unchanged. This is discussed in terms of the different timescales characteristic for both methods. The single supported bilayer responds to the MBP coupling as a whole although only 50% of the bilayer surface is accessible to the protein, indicating a strong coupling between the two bilayer leaflets via the hydrophobic chain region. Moreover, the asymmetric coupling of MBP to the single supported bilayer does not result in a significant redistribution of lipids between the two bilayer leaflets. NMR relaxation time measurements in the headgroup and chain region of DMPG and DMPC suggest that the lateral diffusion coefficient of the acidic lipid decreases significantly due to the coupling with MBP while the zwitterionic DMPC is not affected.

Aniline Compounds↗
PubMed1986

FTIR-ATR studies of the effect of shear rate upon albumin adsorption onto polyurethaneurea.

The effect of wall shear rate upon albumin adsorption onto a polyurethaneurea, Biomer, was studied using FTIR-ATR spectroscopy. In these experiments, nondiffusion controlled adsorption was observed from 10 mg/ml solutions at known wall shear rates. Results show that increasing wall shear rate during adsorption does not significantly affect the adsorption kinetics, but does decrease the rate of protein desorption. These results suggest that albumin adsorbed at higher shear rates is more tightly bound to the surface. Comparison of the data to simple mathematical models suggests that more than one layer of protein adsorbs in 2 h.

Adsorption↗