Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ATR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 703 records · Page 39Linked to original sources
PubMed2004

Non-invasive assessment of the effect of formulation excipients on stratum corneum barrier function in vivo.

The objective of the present work was to investigate the effect of formulation excipients on human stratum corneum (SC) barrier function in vivo. Two formulations, an ointment and an oil-in-water cream, were applied to the skin of human volunteers under both occlusive and non-occlusive conditions. The effects of each treatment were then evaluated using three non-invasive biophysical techniques: transepidermal water loss (TEWL), impedance spectroscopy (IS) and attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. These measurements were combined with a simple tape-stripping protocol to allow information to be derived across the entire SC. IS and TEWL provided basic information on the effect of each formulation on skin barrier function, while ATR-FTIR enabled (i) the tracking of formulation excipients and evaluation of their concentration profiles within the SC, and (ii) deduction of mechanistic detail with which to explain the TEWL and IS results. It was found that occlusion of the skin either in the presence or absence of the cream caused TEWL to be increased when the treatment was terminated at 6 h. Uptake of ointment into the SC, on the other hand, inhibited the post-application TEWL rate. In parallel, treatment with the ointment caused an increase in relative low-frequency skin impedance, consistent with the entry of additional lipophilic constituents into the SC. The latter was confirmed by ATR-FTIR spectroscopic measurements. Overall, the combined use of the three biophysical measurements allowed formulation effects on, and uptake into, the SC to be deduced and evaluated, and the approach may prove useful for the future selection and optimization of topical drug delivery vehicles.

Administration, Cutaneous↗
PubMed2006

Surface complexes of phthalic acid at the hematite/water interface.

The adsorption of o-phthalic acid at the hematite/water interface was investigated experimentally using batch adsorption experiments and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy over a wide range of solution pH, surface loading, and ionic strength conditions. Molecular orbital calculations for several possible surface complexes were also performed to assign atomistic structures to the features observed in the ATR-FTIR spectra. The results of the batch adsorption experiments exhibit typical anionic characteristics with high adsorption at low pH and low adsorption at high pH. The adsorption of phthalic acid also exhibits a strong dependence on ionic strength, which suggests the presence of outer-sphere complexes. ATR-FTIR spectra provide evidence of three fully deprotonated phthalate surface complexes (an outer-sphere complex and two inner-sphere complexes) under variable chemical conditions. A fully deprotonated outer-sphere complex appears to dominate adsorption in the circumneutral pH region, while two fully deprotonated inner-sphere complexes that shift in relative importance with surface coverage increase in importance at low pH. Comparison of experimental and theoretical calculations suggests the two inner-sphere complexes are best described as a mononuclear bidentate (chelating) complex and a binuclear bidentate (bridging) complex. The mononuclear bidentate inner-sphere complex was favored at relatively low surface coverage. With increasing surface coverage, the relative contribution of the binuclear bidentate inner-sphere complex increased in importance.

Journal Article↗
PubMed2006

Analysis of patients with good uncorrected distance and near vision after monofocal intraocular lens implantation.

PURPOSE: To analyze factors contributing to uncorrected visual acuity of at least 6/12 for distance and at least J4 for near (pseudoaccommodation) after monofocal intraocular lens (IOL) implantation. SETTING: Iladevi Cataract and IOL Research Center, Ahmedabad, India. METHODS: In a case-controlled study of 30 eyes (30 patients) that had phacoemulsification, those with pseudoaccommodation were assigned to cases and 30 eyes (30 patients) without pseudoaccommodation were designated as controls. Controls were matched by identical best corrected visual acuity, age, and postoperative duration. Subjective refraction was done with retinoscopy. Factors analyzed included corneal astigmatism, pupil size, axial IOL movement, amplitude of accommodation, axial length (AL), and age. Corneal astigmatism was noted on topography and interpreted as against the rule (ATR) (180 +/- 15 degrees), with the rule (WTR) (90 +/- 15 degrees), and oblique (OB) (45/135 +/- 30 degrees). Pupil size was noted on topographic display and AL and anterior chamber depth (ACD) on immersion A-scan. The axial IOL movement was calculated as the difference in ACD after instillation of cyclopentolate 1% (Cyclopent) and subsequently pilocarpine nitrate 2% (Carpinol) at separate visits, and amplitude of accommodation was measured with static and dynamic retinoscopy. Multivariate logistic regression and odds ratio with 95% confidence intervals were determined. RESULTS: Mean spherical equivalent was -0.45 +/- 0.63 diopter (D) in cases and -0.35 +/- 0.83 D (P = .61) in controls. Multivariate logistic regression in cases versus controls: corneal astigmatism (ATR versus WTR and OB collectively): 10.19 [1.8,57.44], P = .009; pupil size: 0.45 [0.07,2.71], P = .38; axial IOL movement: 1.39 [0.51,0.77], P = .514; amplitude of accommodation: 2.95 [0.93,9.3], P = .065; AL: 0.55 [0.29,1.02], P = .058; and age: 0.98 [0.5,1.95], P = .963. CONCLUSION: The study suggests a significant role of ATR corneal astigmatism in good uncorrected distance and near vision after monofocal IOL implantation.

Accommodation, Ocular↗
PubMed2005

Ectopic expression of the human adenine nucleotide translocase, isoform 3 (ANT-3). Characterization of ligand binding properties.

The adenine nucleotide translocase (ANT) is a key component in maintaining cellular energy homeostasis, and has also been implicated in formation of the mitochondrial permeability transition pore. Human ANT-3 was cloned from a human heart cDNA library and expressed as a histidine-tagged fusion protein in the mitochondria of the Trichoplusia ni. cell line. Overexpression resulted in a concomitant decrease in the endogenous ANT content, allowing for the characterization of binding of known ANT ligands to the human protein. Binding affinities for bongkrekic acid (BKA), ADP, and atractyloside (ATR) were measured in mitochondria from the human ANT-3 expressing cell line, and compared to similar preparations from bovine heart mitochondria by use of a novel radioiodinated derivative of ATR. Binding to ANT-3 by the high affinity inhibitors BKA and ATR, as well as the lower affinity natural ligand ADP, was similar to that measured in bovine heart mitochondria, and to that previously reported for mammalian heart mitochondria. Characterizations such as these of human ANT isoforms may lead to drug development for enhanced mitochondrial function and cellular viability.

Adenine Nucleotide Translocator 3↗
PubMed2006

Receptor activated bladder and spinal ATP release in neurally intact and chronic spinal cord injured rats.

Neurally intact (NI) rats and chronic spinal cord injured (SCI) rats were studied to determine how activation of mechanosensory or cholinergic receptors in the bladder urothelium evokes ATP release from afferent terminals in the bladder as well as in the spinal cord. Spinal cord transection was performed at the T(9)-T(10) level 2-3 weeks prior to the experiment and a microdialysis fiber was inserted in the L(6)-S(1) lumbosacral spinal cord one day before the experiments. Mechanically evoked (i.e. 10 cm/W bladder pressure) ATP release into the bladder lumen was approximately 6.5-fold higher in SCI compared to NI rats (p<0.05). Intravesical carbachol (CCh) induced a significantly greater release of ATP in the bladder from SCI as compared to NI rats (3424.32+/-1255.57 pmol/ml versus 613.74+/-470.44 pmol/ml, respectively, p<0.05). However, ATP release in NI or SCI rats to intravesical CCh was not affected by the muscarinic antagonist atropine (Atr). Spinal release of ATP to bladder stimulation with 10 cm/W pressure was five-fold higher in SCI compared to NI rats (p<0.05). CCh also induced a significantly greater release of spinal ATP in SCI rats compared to controls (4.3+/-0.9 pmol versus 0.90+/-0.15 pmol, p<0.05). Surprisingly, the percent inhibitory effect of Atr on CCh-induced ATP release was less pronounced in SCI as compared to NI rats (49% versus 89%, respectively). SCI induces a dramatic increase in intravesical pressure and cholinergic receptor evoked bladder and spinal ATP release. Muscarinic receptors do not mediate intravesical CCh-induced ATP release into the bladder lumen in NI or SCI rats. In NI rats sensory muscarinic receptors are the predominant mechanism by which CCh induces ATP release from primary afferents within the lumbosacral spinal cord. Following SCI, however, nicotinic or purinergic receptor mechanisms become active, as evidenced by the fact that Atr was only partially effective in inhibiting CCh-induced spinal ATP release.

Adenosine Triphosphate↗
PubMed2004

Small interacting peptides. Part II: Interaction of cyclohexapeptides with immobilised model peptides. Comparison of infrared investigations, principal components analysis and force field calculations.

The interaction of cyclic peptides with surface-bound model peptides was investigated by ATR-FTIR spectroscopy, principal components analysis and force field calculations. Information about the interacting functional COOH, COO-, and NH3+ groups and the peptide backbone was gained through a set of cyclohexapeptides (seven of the type c(X1KX2KX3K) (K = L-lysine) and one of the type c(X1KX2KX3k) (k = D-lysine), which are interacting with L-arginine- or tripeptide-coated Si-ATR crystals. All measurements were performed in aqueous solutions. Spectra evaluation in the range 1800-1500 cm(-1) was done by band and principal components analysis (PCA). Only adsorbed molecules were present in these spectra. The coatings were investigated by ATR-FTIR spectroscopy too in order to characterise their functional groups. Based on this knowledge, the spectra of the interacting partners could be evaluated in relation to cyclohexapeptides and coatings. As a result, it was possible to identify the distinct differences in the bonding behaviour of the various peptides.

Amino Acid Sequence↗
PubMed2004

Infrared study of HDTMA+ intercalated montmorillonite.

In this paper, FTIR spectroscopy using attenuated total reflection (ATR) and KBr pressed disk techniques has been used to characterize sorbed water and HDTMA+ in organo-clay. Sorbed water content decreases with the intercalation of HDTMA+. With the decrease of the sorbed water content, the position of the nu2 mode shifts to higher frequency dramatically while the stretching vibration shifts to lower frequency slightly, indicating that H2O is less strongly hydrogen bonded. This might be resulted from the polarization of H2O molecules by the changeable cations and HDTMA+. FTIR spectra show that both antisymmetric and symmetric CH2 stretching absorption bands shift to low frequencies with increase of amine concentration within the galleries of montmorillonite, elucidating the increase of ordered conformation. Furthermore, the present study demonstrates that the antisymmetric CH2 stretching mode is more sensitive to the conformational ordering than the symmetric stretching mode. When KBr pressed disk technique used, two well resolved absorption bands at 730 and 720 cm(-1), and at 1473 and 1463 cm(-1), corresponding to the methylene scissoring and rocking modes, respectively, could be observed in FTIR spectra of organo-clays with relative higher concentration of surfactant. However, the FTIR spectra using ATR technique only display singlets and they are independent of amine concentration and chain conformation. Our present study demonstrates that FTIR spectroscopy using KBr pressed disk technique is more suitable to probe the conformational ordering of surfactant in organo-clays than that suing ATR technique does.

Bentonite↗
PubMed2005

Inhibition of HIV-1 replication by caffeine and caffeine-related methylxanthines.

Human immunodeficiency virus type I (HIV-1) DNA integration is an essential step of viral replication. We have suggested recently that this stage of HIV-1 life-cycle triggers a cellular DNA damage response and requires cellular DNA repair proteins for its completion. These include DNA-PK (DNA-dependent protein kinase), ATR (ataxia telangiectasia and Rad3-related), and, at least in some circumstances, ATM (ataxia telangiectasia mutated). Host cell proteins may constitute an attractive target for anti-HIV-1 therapeutics, since development of drug resistance against compounds targeting these cellular cofactor proteins is unlikely. In this study, we show that an inhibitor of ATR and ATM kinases, caffeine, can suppress replication of infectious HIV-1 strains, and provide evidence that caffeine exerts its inhibitory effect at the integration step of the HIV-1 life-cycle. We also demonstrate that caffeine-related methylxanthines including the clinically used compound, theophylline, act at the same step of the HIV-1 life-cycle as caffeine and efficiently inhibit HIV-1 replication in primary human cells. These data reveal the feasibility of therapeutic approaches targeting host cell proteins and further support the hypothesis that ATR and ATM proteins are involved in retroviral DNA integration.

Ataxia Telangiectasia Mutated Proteins↗
PubMed2006

Molecular activation of PPARgamma by angiotensin II type 1-receptor antagonists.

OBJECTIVE AND DESIGN: Elevated blood pressure and insulin resistance are strongly associated in patients. We explored the potential for the anti-hypertensive angiotensin II type 1-receptor (ATR(1)) antagonists to improve insulin sensitivity through modulation of the nuclear receptor PPARgamma, in vitro and in vivo compared to the potent insulin sensitizer, rosiglitazone. METHODS: PPARgamma modulation by ATR(1) antagonists was measured first by direct recruitment of PGC-1, followed by trans-activation reporter assays in cells, and promotion of adipogenesis in fibroblast and pre-adipocyte cell lines. Improvement of insulin sensitivity was measured as changes in levels of glucose, insulin, and adiponectin in ob/ob mice. RESULTS: Telmisartan, candesartan, irbesartan, and losartan (but not valsartan or olmesartan) each served as bona fide PPARgamma ligands in vitro, with EC(50) values between 3 and 5 micro mol/l. However, only telmisartan, and to a lesser extent candesartan, resulted in significant PPARgamma agonism in cells. In vivo, although rosiglitazone significantly lowered both glucose (33%, p<0.01) and insulin (61%, p<0.01) levels and increased expression of adiponectin (74%, p<0.001), sartan treatment had no effect. CONCLUSIONS: Many members of the sartan family of ATR(1) antagonists are PPARgamma ligands in cell-free assays but their modulation of PPARgamma in cells is relatively weak. Furthermore, none appear to improve insulin sensitivity in a rodent model under conditions where other insulin sensitizers, including rosiglitazone, do. These results question whether reported effects of sartans on insulin sensitivity may be through other means, and should guide further efforts to develop dual agents to treat hypertension and insulin resistance.

3T3-L1 Cells↗
PubMed1990

Intravenous nitroglycerin-induced heparin resistance: a qualitative antithrombin III abnormality.

An ability of intravenous nitroglycerin to interfere with the anticoagulant properties of intravenous heparin would have profound clinical implications. To investigation nitroglycerin-heparin interactions, the following pilot study was performed. Patients (N = 18) admitted to the coronary care unit with a diagnosis of either acute myocardial infarction or unstable angina were divided into four treatment groups: (1) intravenous nitroglycerin and intravenous heparin; (2) intravenous nitroglycerin alone; (3) intravenous heparin alone; or (4) neither intravenous nitroglycerin nor intravenous heparin. Serial determinations of activated partial thromboplastin time (APTT), serum heparin concentration, antithrombin III (ATIII) antigen (ATA), and ATIII activity (ATC) were obtained over a 72-hour period. Overall, patients receiving intravenous nitroglycerin did not differ significantly from other patients in APTT, heparin dose, heparin concentration, ATA, ATC, or ATA/ATC ratio (ATR). However, patients receiving intravenous nitroglycerin at a rate exceeding 350 micrograms per minute had a lower APTT (p less than 0.05), lower ATC (p = 0.02), higher ATR (p = 0.004), and a larger heparin dose requirement than patients receiving lower infusion rates. ATR correlated directly (r = 0.91; p less than 0.05) and ATC inversely (r = -0.78; p less than 0.05) with the intravenous nitroglycerin dose. Serum heparin concentration did not correlate with the intravenous nitroglycerin dose. Intravenous nitroglycerin-induced heparin resistance occurs at a critical nitroglycerin dose. A nitroglycerin-induced qualitative ATIII abnormality may be the underlying mechanism.

Adult↗
PubMed1987

Conformational changes in bacteriorhodopsin studied by infrared attenuated total reflection.

We report on a new method based on Fourier transform infrared (FTIR)-difference spectroscopy for studying the conformational changes occurring during the photocycle of bacteriorhodopsin. Previous studies have been made by measuring the absorbance of an infrared (IR) beam transmitted through a thin hydrated purple membrane film. In contrast, the present study utilizes the technique of attenuated total reflection (ATR). Purple membrane is fixed on the surface of a germanium internal reflection crystal and immersed in a buffer whose pH and ionic composition can be varied. Measurements of the amide I and II absorbance with light polarized parallel and at 45 degrees to the crystal surface reveals that the membrane is highly oriented. An ATR-FTIR-difference spectrum of the light to dark (bR570 to bR548) transition is similar but not identical to the transmittance FTIR-difference spectrum. This disagreement between the two methods is shown to be due in the ATR case to the absorption of transition moments oriented predominantly out of the membrane plane. Raising the pH of La3+ substituted purple membrane films from 6.8 to 8.0 slows the M-decay rate sufficiently so that a bR570 to M412 difference spectrum can be obtained with steady state illumination at room temperature. A comparison of this difference spectrum with that obtained at -23 degrees C using the transmittance method reveals several changes that cannot be attributed to out-of-plane transition moments. An increase in the intensity of peaks in the amide I and II regions agrees with recent time-resolved kinetic FTIR-difference measurements and indicates that a localized protein conformational change involving the peptide backbone of bR occurs which is not evident at the lower temperature.

Bacteriorhodopsins↗
PubMed1988

Analysis of rhodamine and fluorescein-labeled F-actin diffusion in vitro by fluorescence photobleaching recovery.

Properties of filamentous acetamidofluorescein-labeled actin and acetamidotetramethylrhodamine-labeled actin (AF and ATR-actin, respectively) were examined to resolve discrepancies in the reported translational diffusion coefficients of F-actin measured in vitro by FPR and other techniques. Using falling-ball viscometry and two independent versions of fluorescence photobleaching recovery (FPR), the present data indicate that several factors are responsible for these discrepancies. Gel filtration chromatography profoundly affects the viscosity of actin solutions and filament diffusion coefficients. ATR-actin and, to a lesser degree, AF-actin show a reduction in viscosity in proportion to the fraction labeled, presumably due to filament shortening. Actin filaments containing AF-actin or ATR-actin are susceptible to photoinduced damage, including a covalent cross-linking of actin protomers within filaments and an apparent cleavage of filaments detected by a decrease of the measured viscosity and an increase in the measured filament diffusion coefficients. Quantum yields of the two photoinduced effects are quite different. Multiple cross-links are produced relative to each photobleaching event, whereas less than 1% filament cleavage occurs. Substantial differences in the filament diffusion coefficients measured by FPR are also the result of differences in illumination geometry and sampling time. However, under controlled conditions, FPR can be used as a quantitative tool for measuring the hydrodynamic properties of actin filaments. Incremented filament shortening caused by photoinduced cleavage or incremental addition of filament capping proteins produces a continuous and approximately linear increase of filament diffusion coefficients, indicating that filaments are not associated in solution. Our results indicate that actin filaments exhibit low mobilities and it is inferred that actin filaments formed in vitro by column-purified actin, under standard conditions, are much longer than has conventionally been presumed.

Actins↗
PubMed1996

Fluorescent probes of the orientation of myosin regulatory light chains in relaxed, rigor, and contracting muscle.

The orientation of the light-chain region of myosin heads in relaxed, rigor, and isometrically contracting fibers from rabbit psoas muscle was studied by fluorescence polarization. Cysteine 108 of chicken gizzard myosin regulatory light chain (cgRLC) was covalently modified with iodoacetamidotetramethylrhodamine (iodo-ATR). Native RLC of single glycerinated muscle fibers was exchanged for labeled cgRLC in a low [Mg2+] rigor solution at 30 degrees C. Troponin and troponin C removed in this procedure were replaced. RLC exchange had little effect on active force production. X-ray diffraction showed normal structure in rigor after RLC exchange, but loss of axial and helical order in relaxation. In isolated myofibrils labeled cgRLC was confined to the regions of the sarcomere containing myosin heads. The ATR dipoles showed a preference for orientations perpendicular to the fiber axis, combined with limited nanosecond rotational motion, in all conditions studied. The perpendicular orientation preference was more marked in rigor than in either relaxation or active contraction. Stretching relaxed fibers to sarcomere length 4 microns to eliminate overlap between actin- and myosin-containing filaments had little effect on the orientation preference. There was no change in orientation preference when fibers were put into rigor at sarcomere length 4.0 microns. Qualitatively similar results were obtained with ATR-labeled rabbit skeletal RLC.

Animals↗
PubMed2002

Atropine prevents the changes in the hindlimb cortical area induced by hypodynamia-hypokinesia.

It has been demonstrated that hypodynamia-hypokinesia (HH), a model of sensory disruption, induced a decrease in the cortical hindpaw representation and an enlargement of the cutaneous receptive fields (RFs). The present study was carried out to determine whether chronic application of atropine could prevent this reorganisation. The extent of the hindlimb representation on the somatosensory cortex was determined in control rats (C), rats submitted to HH (HH), and rats submitted to HH with a chronic cortical infusion of atropine (70 mM, HH-ATR). Our results show that the hindpaw cortical area was similar for the HH-ATR and C rats, and was smaller for the HH rats. The distribution of RFs was comparable for the C and HH-ATR groups with a high percentage of small RFs. In contrast, for the HH rats, the percentage of large RFs was higher. Atropine can thus prevent the reduction in the hindlimb cortical area induced by HH. These results suggest that cholinergic mechanisms contribute to cortical plasticity.

Animals↗
PubMed1997

Bradykinin modulation of isolated rabbit heart function is mediated by intrinsic cardiac neurons.

OBJECTIVE: Bradykinin (BK) is an endogenous peptide exerting a potent influence on the behavior of the heart. The local regulatory mechanisms responsible for BK modulation of cardiac automaticity and contractility remain poorly understood. The role of the intrinsic cardiac nervous system (ICNS) in mediating the BK-induced regulatory effect was investigated. METHODS: Heart rate (HR) and intramyocardial pressure (IMP) changes in response to BK (1.2-80 nmol) were studied in isolated rabbit hearts (n = 37). The intrinsic neural mechanisms underlying the cardiac effects of BK were characterized by use of atropine (ATR, 10(-6) M), timolol (TIM, 10(-5) M), hexamethonium (HEX, 10(-4) M), and tetrodotoxin (TTX, 10(-7) M). Modulation of beta-adrenergic tone by dobutamine (DOB, 1.6 x 10(-6) M) was used to expose the physiological importance of intrinsic cholinergic systems in mediating the cardiac action of BK. RESULTS: A single dose of BK induced an increase in IMP and a biphasic HR response. The negative chronotropic response to BK was correlated with negative HR change induced by nicotine activation of ICNS. BK-elicited 'bradycardia' was abolished by ATR and TTX, and attenuated (approximately 50%) by HEX. ATR and TTX potentiated the positive HR-response which was not affected by TIM. BK selectively antagonized [by 48.1(5.1)%] the DOB-induced tachycardia but did not modify the accompanied inotropic potentiation. CONCLUSIONS: These findings are the first demonstration that in the autonomically decentralized heart, the negative chronotropic action of BK is mediated by intrinsic cardiac cholinergic neurons. It would appear that the intrinsic neural network response, and not merely the BK-induced potentiation of cardiac postganglionic neural activity is involved in the local neuromodulatory action of BK. This intrinsic cardiac regulatory mechanism seems to play a major role in mitigating the adrenergically induced tachycardia, thus endowing this peptide with the capacity for cardioprotection.

Adrenergic beta-Agonists↗
PubMed2003

Detection of structural and functional asymmetries in P-glycoprotein by combining mutagenesis and H/D exchange measurements.

During the last few years, Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) has become one of the most powerful methods to determine the structure of biological materials and in particular of components of biological membranes, like proteins which cannot be studied by X-ray crystallography and NMR. Indeed, ATR-FTIR method requires little amount of material, gives valuable information about the secondary structure, orientation and tertiary structure changes in peptides and proteins. Moreover, this technique can be used in the presence of lipids and hence provides an excellent tool to study membrane proteins in their natural environment. In this review, we describe how structural information about the catalytic cycle of membrane proteins can be gained by combining ATR-FTIR spectroscopy and mutagenesis. In particular, results obtained about the structure and function of the nucleotide binding domains (NBD) of P-glycoprotein (Pgp), a multidrug transporter involved in cancer cells resistance to chemotherapy, are described.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Is high concentration of serum lipids a risk factor for Achilles tendon rupture?

BACKGROUND: The incidence of the Achilles tendon ruptures (ATR) seems to be increasing due to changes in life style and intensified sports activities in recent years. Intrinsic and extrinsic factors have been implicated as predisposing risk factors to rupture. The purpose of this study was to investigate whether the high serum lipid concentrations could be an intrinsic factor in patient with complete ruptures of Achilles tendon. METHODS: The data were collected from the records of 47 patients with complete rupture of Achilles and the control group consisted of 26 subjects. RESULTS: Total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) concentrations of the patients with ATR were higher (p<0.001), and their high-density lipoprotein cholesterol (HDL-C) was lower than the control group (p<0.05). Moreover, the concentrations of triglyceride (TG) and very low-density lipoprotein cholesterol (VLDL-C) were significantly higher than controls (p<0.05). CONCLUSIONS: The causes of ATR are multifactorial and still unclear. However, high serum lipid concentrations might be considered, as a predisposing factor in patients with complete rupture of Achilles tendon and further investigations with larger groups would be better.

Achilles Tendon↗
PubMed2001

Perfusion-induced redox differences in cytochrome c oxidase: ATR/FT-IR spectroscopy.

Attenuated total reflection (ATR) spectroscopy brings an added dimension to studies of structural changes of cytochrome c oxidase (CcO) because it enables the recording of reaction-induced infrared difference spectra under a wide variety of controlled conditions (e.g. pH and chemical composition), without relying on light or potentiometric changes to trigger the reaction. We have used the ATR method to record vibrational difference spectra of CcO with reduction induced by flow-exchange of the aqueous buffer. Films of CcO prepared from Rhodobacter sphaeroides and beef heart mitochondria by reconstitution with lipid were adhered to the internal reflection element of the ATR device and retained their full functionality as evidenced by visible spectroscopy and time-resolved vibrational spectroscopy. These results demonstrate that the technique of perfusion-induced Fourier-transform infrared difference spectroscopy can be successfully applied to a large, complex enzyme, such as CcO, with sufficient signal/noise to probe vibrational changes in individual residues of the enzyme under various conditions.

Animals↗