Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissues regulated by thyroid hormones contain chromatin-localized "receptors" that may be involved in the actions of these hormones. In this report, we describe some properties of these receptors after their solubilization from rat liver nuclei and their separation from nucleic acids and basic proteins. The nuclear extract and partially purified preparations contain a dominant class of binding sites which have a high affinity for triiodothyronine (3,5,3'-triiodo-L-thyronine, Kd approximately 1 nM) and for the biologically potent isopropyl diiodothyronine (3,5-diiodo-3'-isopropyl-L-thyronine, Kd congruent to 1 nM) and also bind thyroxine (3,5,3',5'-tetraiodo-L-thyronine, Kd approximately 5 nM) and reverse triiodothyronine (3,3',5'-triiodo-L-thyronine, Kd approximately nM). This binding activity elutes on Sephadex G-100 in an included peak which has a Stokes radius of 35 A and sediments on glycerol gradients at 3.5 S. From these data a molecular weight ratio of 50,500 and a frictional ratio of 1.4 were calculated, suggesting that the receptor is somewhat asymmetrical. There was a sharp decline in triiodothyronine binding by this component above pH 8.7 (optimum around pH 7.6) where there is marked dissociation of the 4' phenolic hydroxyl of triiodothyronine (pKalpha approximately 8.5). A similar decrease in thyroxine (pKalpha approximately 6.7) binding with pH increases in this range was not observed. Thus, ionization of the phenolic hydroxyl may influence binding. The solubilized preparations can also contain a minor specific-binding component that can be identified by binding analyses, and by G-100 or quaternary aminoethyl Sephadex chromatography. this component has a much lower affinity for triiodothyronine and isopropyl diiodothyronine than for thyroxine as compared to the major component. It probably has a pH optima around 6.0 and demonstrates and apparent tendency to aggregate. The minor component was not always identified by direct Scatchard analysis and may be generated in part from the major component as it was more commonly observed after storage or purification of the nuclear extract. Thus, at least two thyroid hormone-binding components can be present in extracts of purified rat liver nuclei; the minor component may be an altered form or subunit of the major component. The relative binding activities of triiodothyronine, isopropyl diiodothyronine, and thyroxine by the major component, similar to those in intact nuclei, parallel the biological potencies of these compounds, and suggest that the dominant binding is by biologically relevant receptors. Since ionization of the phenolic hydroxyl may influence binding, the lower activity of thyroxine relative to triiodothyronine may in part be due to the fact that at physiological pH, the phenolic hydroxyl of thyroxine is more dissociated than is that of triiodothyronine. The finding that this receptor is somewhat asymmetrical provides an indication of the shape of an intrinsic chromatin protein implicated in specific gene regulation...
J Biol Chem 1976 Dec 10
PMID:Solubilized nuclear "receptors" for thyroid hormones. Physical characteristics and binding properties, evidence for multiple forms. 1 62

Spatial distributions of visual potentials (VEPs) evoked by half-field checkerboard pattern-reversal and pattern-onset stimuli were studied in 13 subjects, using an 11 lead unipolar array. The main aim was to confirm findings, obtained by previous workers with bipolar recordings, that half-field pattern-reversal VEP's are confined to the contralateral hemisphere and that half-field pattern-onset VEPs are asymmetrical, with greater right hemisphere involvement. Pattern-reversal VEP's contained four consistent peaks, designated here by polarity and peak latency as: (a) P95, positivity contra-lateral and negativity ipsilateral to the field stimulated; (b) P125, predominantly ipsilateral positivity; (c) N165, predominantly ipsilateral negativity; (d) P225; predominantly midline positivity. Pattern-onset VEPs contained three consistent peaks: (a) P125, mainly contraleteral positivity; (B) N175, mainly contralateral negativity; (c) P225, midline positivity. Distributions of pattern-reversal and pattern-onset peaks resembled one another only for P225, suggesting different cortical representation for the other events of the two kinds of VEP. Bipolar pattern-reversal VEPs were largely contralateral, but unipolar recordings showed that this was due to steeper contralateral potential gradients, as ipislateral activity was widespread. Pattern-onset peaks did not differ in amplitude with respect to the half-field stimulated. Previously reported asymmetries were not confirmed. The P125 and N175 pattern-onset peaks were almost entirely restricted to the contralateral hemisphere, but the distributions by half-field were mirror-images of one another. Half-field pattern-onset stimuli could be used to investigate the responsiveness of each hemisphere, although differential hemispheric involvement was not shown. Several differences in amplitude and distribution resulted from varying the width of the vertical central dark strip.
Electroencephalogr Clin Neurophysiol 1976 Dec
PMID:Spatial distribution of potentials evoked by half-field pattern-reversal and pattern-onset stimuli. 6 55

One type of striatonigral neuron in the rat has been characterized. Golgi impregnation of striatal neurons that had been retrogradely labeled by horseradish peroxidase has shown that the medium-sized, densely spiny neurons project to the substantia nigra. Some of the synapses on three of these identified striatonigral neurons have been studied in the electron microscope following replacement of the Golgi deposit by means of the 'gold-toning' method. Synapsing axonal boutons were found on the following sites: soma and axon initial segment (symmetrical, with flattened or pleomorphic vesicles); primary and secondary dendritic shafts (symmetrical with pleomorphic vesicles); dendritic spines (asymmetrical, with spheroidal vesicles). These findings show that new information concerning neuronal connectivity can be obtained by combining three classical procedures in the same material: first, the Golgi method, that characterizes the type of neuron on the basis of its dendritic morphology; second, a retrograde tracing method, that identifies the projection area of the neuron; and, third, ultrastructural analysis of the nature of afferent terminals on the neuron.
Brain Res 1979 Dec 07
PMID:Projection of neostriatal spiny neurons to the substantia nigra. Application of a combined Golgi-staining and horseradish peroxidase transport procedure at both light and electron microscopic levels. 9 16

Echocardiographic patterns in 15 patients with hypertrophic cardiomyopathy were compared with those in 30 healthy persons. Correlations with angiocardiographic data indicated that most of the anatomical abnormalities in hypertrophic cardiomyopathy can be assessed reliably by echocardiography. These include abnormal mitral valve motion, a reduction of the anteroposterior dimension of the left ventricular outflow tract and of the left and right ventricular cavities, increased thickness of the interventricular septum and the posterior left ventricular wall. Comparision of the haemodynamic and echocardiographic data showed that some degree of abnormal mitral valve motion during systole may occur in the absence of left ventricular outflow tract obstruction. On the other hand, it need not always be present with left ventricular outflow tract obstruction. Other, hitherto unrecognized, abnormalities in hypertrophic cardiomyopathy detected by this technique were: (1) Aortic valve regurgitation in three out of nine patients with evidence of left ventricular cutflow tract obstruction at cardiac catheterization. (2) Left ventricular inflow tract obstruction at the mitral valve level associated with gross septal hypertrophy (five cases). (3) Abnormal forward displacement of the posterior mitral valve leaflet and of the chordae tendineae during systole in 10 patients, in seven of whom there was confirmatory angiocardiographic evidence. Seven patients with miscellaneous cardiac disorders are described in whom asymmetric septal hypertrophy was revealed by echocardiography. In one of these patients coexisting hypertrophic cardiomyopathy was excluded histologically; thus asymmetrical septal hypertrophy is not confined to patients with hypertrophic cardiomyopathy.
Br Heart J 1975 Dec
PMID:Echocardiographic spectrum of hypertrophic cardiomyopathy. 13 64

Thum of colon induced by repeated subcutaneous injections of 1,2-dimethyl-hydrazine dihydrochloride in mice were studied by scanning electron microscopy. In addition, the surface composition of normal and malignant colonic epithelial cells were investigated by ultrastructural cytochemistry. The neoplastic, nodular tumour masses which protruded into the lumen of colon displayed an asymmetrical, irregular growth pattern and surface contour. In contrast to the normal surface structure, the shape of crypt openings in malignant areas was distorted and they were irregularly spaced. Cells varying in size and shape in the intercrypt regions often formed random patterns of elevations and depressions. Microvilli on neoplastic cells were larger, more club-shaped and showed more disorderly arrangement than their normal counterparts. The distribution and quantity of surface acid mucopolysaccharide content and adenosine triphosphatase activity varied considerably from cell to cell in the neoplastic epithelium while they were more uniform in the normal colonic surface cells.
Br J Exp Pathol 1976 Dec
PMID:Production of intestinal and other tumours by 1,2-dimethylhydrazine dihydrochloride in mice. II. Scanning electron microscopic and cytochemical study of colonic neoplasms. 13 35

Seventy-five children were examined in tasks involving matching figures in order to establish whether there exists a specific attraction to symmetrical or Gestalt type "good form" displays in mentally handicapped children and particularly in Down's Syndrome or if the tendency was towards image reversal. Twenty-five children with Down's Syndrome were matched on M.A. with twenty-five non-Down's Syndrome subnormals and twenty-five normal children. Symmetrical and asymmetrical displays were presented to the groups for reproduction and reproduction from memory. The results supported the hypothesis that mentally handicapped children have a significant attraction to symmetrical arrangements and that Down's Syndrome children are more significantly attracted than other handicapped children. Evidence is presented to show that what often is mistaken for a tendency to image reversal is in fact an attraction to "monotonicity" and is more related to "good form" than to reversal.
J Ment Defic Res 1979 Dec
PMID:Attraction to "good form" in Down's syndrome. 16 24

In order to assess the liability of proprioceptive information, an experiment on kinaesthetic after-effects was carried out. Matched groups of severely subnormal and Down's syndrome subjects were compared with normal children of either the same chronological or the same mental age. No difference was found between the normal and the severely subnormal children, but the magnitude of the after-effect measures in Down's syndrome children suggests that asymmetrical pointing produced kinaesthetic after-effects which disrupted these subjects' total frame of spatial reference.
J Ment Defic Res 1979 Dec
PMID:Kinaesthetic movement after-effects in children with Down's syndrome. 16 27

Temperature-induced conformational changes in the anticodon region of yeast tRNATyr were studied by EPR spectroscopy. The spin label 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl was attached to the N6-(delta2-isopentenyl)-adenosine residue in tRNATyr, previously made reactive by iodination. The labelled tRNATyr gave an asymmetrical triplet spectrum typical of rapidly tumbling nitroxide, with a rotational correlation time (tauc) of 0.65 ns. Spin-labelled tRNATyr was exposed to heating and cooling in three different buffers each with or without MgCl2. In each case the Arrhenius plot of --log tauc vs. inverse absolute temperature gave two straight lines, intersecting at a critical temperature (tcr). Above tcr, the anisotropy of the spectrum was not reduced and the activation energy of motion increased, indicating that the transition is associated with a conformational change of the macromolecule. Transitions in 0.05 M potassium phosphate (pH 8.0) and 0.02 M Tris - HC1 (pH 7.0) were observed at potassium phosphate (pH 8.0) and 0.02 M Tris - Hc1 (pH 7.0) were observed at approx. 37 degrees C. When 0.01 M mgCl2 was present in these buffers, transitions were shifted to 46 degrees and 53 degrees C, respectively. Transitions in 0.01 M sodium cacodylate were observed at temperatures which are significantly lower. Since all these transitions occur at temperatures considerably below those required to melt the helical regions of tRNA, and at least approximately 10 degrees C below those reported to break tertiary interactions, it is supposed that they reflect some reorientation of the anticodon region, e.g. a change in tilt of the bases.
Biochim Biophys Acta 1977 Dec 02
PMID:Conformational changes in yeast tRNATyr revealed by EPR spectra of spin-labelled N6-(delta2-isopentenyl)-adenosine residue. 20 Feb 69

Ipsilateral stapedius reflex testing has been evaluated in 166 patients. It proves of value in defining the state of an ear (1) opposite to a unilateral conductive loss; (2) the less hard-of-hearing ear in the presence of bilateral asymmetrical sensorineural hearing losses where the worse ear has sufficiently severe loss to prevent a contralateral reflex from being elicited; (3) in patients with absent contralateral acoustic reflexes at 500, 1000, and 2000 Hz; and (4) in suspected central lesions. The test is still bedevilled by artifacts which are produced in the ear rather than the machine; atypical results must be evaluated with extreme caution.
J Otolaryngol 1977 Dec
PMID:The clinical utility of ipsilateral stapedius reflex tests. 20 15

Electron spin resonance study of Mn (II) binding to chromatin and derivatives, including core particles, shows that Mn (II) is a good probe for testing the overall electrostatic balance of the nucleoproteic complex as well as DNA accessibility. Experimental results are in good agreement with a recent model proposed (Mirzabekov A. D. and Rich A. (1979) Proc. Natl. Acad. Sci. USA 76, 1118-1121), for the core particle, in which an asymmetrical shielding of DNA by the protein core is assumed. Furthermore, it was found that the histone H1 hinders a number of charges on the linker DNA in a proportion equal to the net positive charge of the histone itself. This result is interpreted as due to a tighter interaction between the linker DNA and the core histones in the presence of histone H1.
Nucleic Acids Res 1979 Dec 20
PMID:Experimental evidence for asymmetrical shielding of nucleosomal DNA by histones. 23 Apr 66


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