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PubMedDate not supplied

Subcortical structural changes in ECT-induced delirium.

A prolonged (interictal) delirium was induced by electroconvulsive therapy (ECT) in 6/36 (17%) elderly depressed patients. Brain magnetic resonance imaging or brain computerized axial tomography revealed structural changes in the basal ganglia and white matter in all six patients who developed delirium. These findings are consistent with our previous work and with several lines of data that have implicated the basal ganglia and subcortical white matter in the development of delirium from other causes. These result suggest that lesions in these areas may predispose one to developing an interictal delirium during a course of ECT.

Age Factors↗

PubMed1982

Structural changes in human pituitary tumor after bromocriptine therapy.

The histological appearance of a prolactin-producing tumor and of a growth hormone-producing tumor after short term bromocriptine therapy was studied in detail using light microscopy with conventional and immunocytochemical methods and using transmission electron microscopy. The findings were correlated with clinical, radiological, and biochemical data. Histological changes consisting of clumping of nuclear chromatin and a marked reduction in cytoplasmic volume due to loss of ribosomes, rough endoplasmic reticulum, and Golgi complexes were observed only in the prolactin-producing tumor. Normalization of elevated serum prolactin levels and reduction in size of the tumor observed in serial computed tomograms correlated with striking histological changes found in the tumor. These changes were interpreted to represent a reversible inhibition of the protein-synthetic machinery of the neoplastic cell. Comparable clinical, biochemical, radiological, or structural changes were not observed in the growth hormone-secreting tumor.

Bromocriptine↗

PubMed1994

[Carotid vascular structural changes and left ventricular hypertrophy].

In the literature there are few studies evaluating carotid vascular atherosclerotic involvement in patients with essential arterial hypertension. Nowadays with new non-invasive methodological methods, such as Doppler-echotomography, it is possible to evaluate accurately structural vascular and cardiac changes. In this study we evaluated the relationship between carotid vascular structural changes and cardiac left ventricular mass index in 15 normotensive subjects and in 15 patients with essential hypertension. We performed a B-mode echotomography (7.5 MHz) of a common carotid in order to measure the diameter of the vessel and intima-media wall thickness. In the same subjects we determined echocardiographic left ventricular mass index and we measured arterial pressure by sphygmomanometric method. There was no statistical significant difference in the two groups except that in systolic, diastolic and mean arterial pressure (96 +/- 2 vs 123 +/- 2 mmHg, p < 0.01), left ventricular mass index (102 +/- 3 vs 118 +/- 3 g/m2, p < 0.01) and in the common carotid intima media wall thickness (0.91 +/- 0.01 vs 2.23 +/- 0.02 mm). In the normotensive subject mean arterial pressure correlated significantly with age (r = 0.699) and with common carotid arterial diameter (r = 0.523) (both p < 0.05). In hypertensive patients, on the contrary, mean arterial pressure correlated with left ventricular mass index (r = 0.523), carotid arterial diameter (r = 0.627) and common carotid intima media wall thickness (r = 0.847). These results demonstrate that in hypertensive patients cardiac abnormalities accompanied vascular structural changes.

Carotid Arteries↗

PubMed1992

[Significance of left ventricular structural changes in arterial hypertension for the prolongation of electric cardiac systole].

Echocardiography was used to examine 93 patients with Stages I and II arterial hypertension with a view to clarifying the impact of structural changes occurring in the left ventricle in the course of the disease on the duration of electric systole. Left ventricular muscle mass was found to become larger with an increase in corrected Q-T interval duration, the upper dependence correlating better with concentric hypertrophy. The duration of electric systole increased with deteriorated left ventricular function. It was empirically concluded that the left ventricular mass index of 200 g was associated with prolonged Q-T interval, which was more than the normal parameters.

Female↗

PubMed1996

Raman spectroscopic evidence for structural changes in poly-L-lysine induced by an approximately 50 mT static magnetic field.

We have explored the mechanism of coupling of an approximately 50 mT static magnetic field with the alpha helices of poly-L-lysine. Structural changes in poly-L-lysine were determined by Raman spectroscopy. Our testable hypothesis is that static magnetic fields of this magnitude can couple with the alpha-helical segments of the polypeptide, and, as a result, the structure of the polypeptide is significantly altered. Our model further suggests that a static magnetic field can promote protein unfolding and can prevent refolding.

Magnetics↗

PubMed1998

Antigen processing of two H2-IEd-restricted epitopes is differentially influenced by the structural changes in a viral glycoprotein.

The factors that influence the intracellular location(s) of MHC class II-restricted epitope loading remain poorly understood. We present evidence that two I-Ed-restricted epitopes of the influenza hemagglutinin (HA) molecule, termed site 1 (S1; encompassing amino acid residues 107-119) and site 3 (S3; encompassing amino acid residues 302-313), are generated in distinct endocytic compartments. By means of an epitope-specific mAb, we show that S1 becomes detectable in late endocytic/lysosomal vesicles; using a mutant cell line, we also show that the presentation of S1 is dependent upon H2-DM expression. In contrast, S3; presentation is H2-DM-independent and appears in early endosomes as a result of acid-induced structural changes in HA. Presentation of both epitopes can be made H2-DM-independent by denaturing HA and made H2-DM-dependent by preventing the acid-induced conformational changes from occurring. These findings indicate that the structural context of a given epitope can determine where it is processed.

Animals↗

PubMed2005

Cerebral structural changes in severe obstructive sleep apnea.

Obstructive sleep apnea is associated with abnormalities in neuropsychologic function, and defects in respiratory control may contribute to pathogenesis. Abnormalities may be reflected in structural brain changes. Twenty-seven male untreated patients with severe sleep apnea without comorbidities, and 24 age-matched control subjects, had T1-weighted brain imaging in a high-resolution magnetic resonance scanner. Twenty-three patients with sleep apnea had repeat imaging after 6 months of continuous positive airways pressure treatment. No areas of gray matter volume change were found in patients using an optimized voxel-based morphometry technique, at p < 0.05 adjusted for multiple comparisons (despite the method being sensitive to changes in gray matter fraction of 0.17 or less in all voxels). Furthermore, no differences were seen in bilateral hippocampal, temporal lobe, or whole brain volumes, assessed by manual tracing of anatomical borders. No longitudinal changes were seen in gray matter density or regional volumes after treatment, but whole brain volume decreased slightly. We have found no gray matter volume deficits nor focal structural changes in severe obstructive sleep apnea. Whole brain volume decreases without focal changes after 6 months of continuous positive airways pressure treatment.

Adult↗

PubMed2004

Oxidation of the Mn cluster induces structural changes of NO3- functionally bound to the Cl- site in the oxygen-evolving complex of photosystem II.

Cl(-) is an indispensable cofactor for photosynthetic O(2) evolution and is functionally replaced by NO(3)(-). Structural changes of an isotopically labeled NO(3)(-) ion, induced by the oxidation of the Mn cluster (S(1)-to-S(2)), were detected by FTIR spectroscopy. NO(3)(-)-substituted photosystem II core particles showed (14)N(16)O(3)(-)/(15)N(16)O(3)(-) and (14)N(16)O(3)(-)/(14)N(18)O(3)(-) isotopic bands in the S(2)/S(1) spectra with markedly high signal/noise ratio. These bands appeared only in the region from 1415 to 1284 cm(-1), indicating that the bands do not arise from a metal-bound NO(3)(-) but from an ionic NO(3)(-). The intensity of the bands exhibited a quantitatively proportional relationship with the O(2) activity. These results demonstrate that the NO(3)(-) functionally bound to the Cl(-) site couples to the Mn cluster structurally, but is not associated with the cluster as a direct ligand. Comparison of the bands for two isotopes ((15)N and (18)O) and their simulations enable us to assign each band to the S(1) and S(2) states. The results indicate that the NO(3)(-) ion bound to the Cl(-) site is highly asymmetric in S(1) but rather symmetric in S(2). Since NO(3)(-) functionally replaces Cl(-), most of the conclusions drawn from this study will be also applicable to Cl(-).

Binding Sites↗

PubMed1986

[Structural changes in the contractile proteins of muscle fiber studied by polarization ultraviolet fluorescence microscopy. IX. The effect of the pH and ionic strength of the solution on the conformational restructurings of F-actin induced by the binding of heavy meromyosin].

The dependence of F-actin conformational changes induced by the F-actin-HMM complex on pH and ionic strength was found by polarized ultraviolet fluorescence microscopy. It is discovered that pH affects sufficiently the cooperativity of F-actin structural changes, while the ionic strength affects their depth. The actomyosin complex was supposed to be at least in two structural states, differing in their orientation as well as in flexibility of F-actin monomers.

Actins↗

PubMed2006

Structure change of liquid GaSb under pressure: an ab initio molecular-dynamics simulation.

We have performed ab initio molecular-dynamics simulation of liquid GaSb (l-GaSb) up to 20.0 GPa. The calculated structure factors are consistent with the recent experimental results, and the partial structure parameters show that the structure of l-GaSb under pressure contracts nonuniformly. In the whole calculated pressure region, the contraction of l-GaSb can be divided into three substages: 1.8-5.4, 5.4-10.0, and 10.0-20.0 GPa. It is further confirmed by analyzing the bond-angle distributions of Ga-Ga-Ga and Sb-Sb-Sb that the rearrangement of Sb atoms under pressure plays a crucial role in the structure change of l-GaSb.

Journal Article↗

PubMed1993

Structural changes in the apical membrane of lamprey chloride cells after acclimation to seawater.

Freeze-fracture replicas demonstrate that the apical membrane of the chloride cells of young adult lampreys (Geotria australis) undergoes a structural change when the animal is acclimated from freshwater to seawater. Although the particles on both the P face and the E face of this membrane are randomly distributed in freshwater animals, they are usually arranged in clusters on both fracture faces in seawater-acclimated animals. Light optical diffraction analysis demonstrates that the particles forming the clusters are periodically arranged. Although comparable clusters of particles have not been recorded in other epithelial membranes that are engaged in transporting ions into a hypertonic environment, they may be involved in the final step of Cl- secretion by the chloride cells of lampreys in seawater.

Adaptation, Physiological↗

PubMed1984

Linkage of subunit interactions, structural changes, and energetics of coenzyme binding in tryptophan synthase.

The energetics of binding of the coenzyme pyridoxal 5'-phosphate (PLP) to both the apo beta 2 subunit and the apo alpha 2 beta 2 complex of tryptophan synthase from Escherichia coli has been investigated as a function of pH and temperature by direct microcalorimetric methods. At 25 degrees C, pH 7.5, the binding process proceeds in the time range of minutes and shows a biphasic heat output which permits resolution of the overall reaction into different reaction steps. Binding studies on the coenzyme analogues pyridoxal (PAL), pyridoxine 5'-phosphate (PNP), and pyridoxine (POL) to the protein as well as a comparison of these results with data from studies on PLP binding to epsilon-aminocaproic acid have led to a deconvolution of the complex heat vs. time curves into fast endothermic contributions from electrostatic interaction and Schiff base formation and slow exothermic contributions from the interactions between PLP and the binding domain. The pH-independent, large negative change in heat capacity of about -9.1 kJ/(mol of beta 2 X K) when binding PLP to beta 2 is indicative of major structural changes resulting from complex formation. The much smaller value of delta Cp = -1.7 kJ/(mol of beta 2 X K) for binding of PLP to alpha 2 beta 2 clearly demonstrates the energetic linkage of protein-protein and protein-ligand interactions. Calorimetric titrations of the apo beta 2 subunit with PLP at 35 degrees C have shown that also at this temperature positive cooperativity between the two binding sites occurs. On the basis of these measurements a complete set of site-specific thermodynamic parameters has been established.(ABSTRACT TRUNCATED AT 250 WORDS)

Calorimetry↗

PubMed2006

Structural change in decorin with skin aging.

Decorin, the main proteoglycan in skin, has a small size with a core protein of approximately 40kDa and one chondroitin sulfate/dermatan sulfate glycosaminoglycan (GAG) chain. The main function of decorin is to regulate the collagen matrix assembly. Decorin is distributed along collagen fibrils with the core protein and the decorin GAG chain controls the distance between the collagen fibrils. Reducing the length of the decorin GAG chain reduces the distance between the collagen fibrils. Age-related changes in decorin are apparent in the GAG chain in respect to the molecular size and sulfate position but not in the core protein. Structural changes in the decorin GAG chain may be involved in changes in collagen matrix assembly during the aging process.

Aging↗

PubMed1987

X-ray- and neutron-induced chromosome damage detected by flow cytometry compared to cell lethality and chromosome structural changes.

V79 Chinese hamster cells were irradiated in G0 phase with 200 kV X rays or 14 MeV neutrons, and dose-response curves were determined for three end points: chromosome damage detected by flow cytometric analysis of chromosomes isolated from metaphase cells in irradiated cultures; loss of clonogenic capacity; and induction of dicentric, tricentric, and ring chromosomes. The changes observed in the flow karyotypes from irradiated cultures were quantitatively evaluated by computer analysis. Estimates of the frequencies of chromosome lesions were derived from an analysis of the flow cytometric measurements by means of a comparison with model calculations simulating the effect of chromosome changes on flow karyotypes. The results indicate that lesions assayed by flow cytometry occur three times more frequently than lethal lesions, while the chromosomal structural changes detected by microscopic analysis were about 10 times less frequent than the lesions detected by flow cytometry. Dose-response curves for X rays and neutrons show that cell reproductive death and changes in flow karyotypes result from damage, induced with a similar relative biological effectiveness. Dose-effect relations derived from changes in flow karyotypes, which can be obtained within 24 h after irradiation, might be of value as a predictive test for the sensitivity of cells for loss of clonogenic capacity.

Animals↗

PubMedDate not supplied

[The physicochemical status of the plasma membranes of rat fatty tissue and liver in the late periods after gamma irradiation at a dose of 1 Gy. Structural changes in the membranes].

The structural status of plasma membranes of adipose tissue and liver of rats was investigated at remote times (from 15 to 380 days) after single 1-Gy gamma irradiation. The structural status was estimated by pyrene excimerisation parameters and also by both induction resonance energy transfer method and membrane tryptophan fluorescence spectral characteristics. On days 50-100 following irradiation the microviscosity of a lipid phase of membranes increased and the mode of lipid/protein interactions changed, whereas at later times the indices under study did not vary from the controls. Comparison of the data obtained with the former results on lipid content changes indicates that the physicochemical status of plasma membranes in rat adipose tissue and liver is modified at remote times following 1-Gy gamma irradiation.

Adipose Tissue↗

PubMed2006

Crystal structures of a poxviral glutaredoxin in the oxidized and reduced states show redox-correlated structural changes.

Glutaredoxins act as reducing agents for the large subunit of ribonucleotide reductase (R1) in many prokaryotes and eukaryotes, including humans. The same relationship has been proposed for the glutaredoxin and R1 proteins expressed by all orthopoxviruses, including vaccinia, variola, and ectromelia virus. Interestingly, the orthopoxviral proteins share 45% and 78% sequence identity with human glutaredoxin-1 (Grx-1) and R1, respectively. To study structure-function relationships of the vertebrate Grx-1 family, and reveal potential viral adaptations, we have determined crystal structures of the ectromelia virus glutaredoxin, EVM053, in the oxidized and reduced states. The structures show a large redox-induced conformational rearrangement of Tyr21 and Thr22 near the active site. We predict that the movement of Tyr21 is a viral-specific adaptation that increases the redox potential by stabilizing the reduced state. The conformational switch of Thr22 appears to be shared by vertebrate Grx-1 and may affect the strictly conserved Lys20. A crystal packing-induced structural change in residues 68-70 affects the GSH-binding loop, and our structures reveal a potential interaction network that connects the GSH-binding loop and the active site. EVM053 also exhibits a novel cis-proline (Pro53) in a loop that has been shown to contribute to R1-binding in Escherichia coli Grx-1. The cis-peptide bond of Pro53 may be required to promote electrostatic interactions between Lys52 and the C-terminal carboxylate of R1. Finally, dimethylarsenite was covalently attached to Cys23 in one reduced EVM053 structure and our preliminary data show that EVM053 has dimethylarsenate reductase activity.

Animals↗

PubMed1986

Fine structural changes in the rat brain after local injections of gliotoxin, alpha-aminoadipic acid.

Toxic effects of locally injected gliotoxin, L-alpha-aminoadipic acid, were examined in the adult rat brain at the fine structural level. Astrocytes were the only cell type in the corpus striatum that showed clear structural degeneration 1 to 3 days after the treatment. With a 7 day survival period, two major structural changes were detectable, including tremendous invasion of astrocytes and their processes, and an appearance of a large number of microglia around injection sites. Both the stereospecificity and cellular specificity were firmly established on the toxic effects of this chemical.

2-Aminoadipic Acid↗

PubMed1988

Structural changes in vesicle membranes and mixed micelles of various lipid compositions after binding of different bile salts.

Binding equilibria of common bile salts (BS) and different mixtures of membrane lipids were correlated with BS-induced structural changes of large unilamellar vesicles, with transition of vesicles to mixed micelles (MM), and with successive transformations of MM. At very low BS concentrations, in the outer vesicle monolayer definite BS/lipid aggregates are formed, the size and BS binding strength of which depend on the BS and lipid species involved. At increasing BS concentrations, binding to the membranes is hampered, and above a critical BS content, membrane stress due to asymmetric BS binding leads to formation of transient membrane holes, as shown by inulin release from the vesicles. Independent of the BS and lipid species, membrane solubilization starts at a ratio r = 0.3 of bound BS/lipid. Increasing phosphatidylserine, phosphatidylethanolamine, and cholesterol contents stabilize the lecithin membrane against BS to different degrees and in different ways, whereas the destabilization by sphingomyelin is probably due to the enhancement of the membrane gel-liquid transition temperature. Conjugation of the BS with glycine or taurine has a modulating effect on membrane hole formation, rather than on lipid solubilization. Diphenylhexatriene fluorescence anisotropy indicates a BS-induced drop of the internal membrane order and its restoration during membrane solubilization. At higher concentrations ursodeoxycholate induces additional condensation, whereas the other BS cause internal disorder in the MM. Above ratios r of approximately 8:1, we found a release of BS from these MM and suggest a rodlike structure for them. The results were discussed with respect to BS/membrane interactions during lipid excretion from the liver cell.

Bile Acids and Salts↗