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)

1. Difference spectra of tryosyl residues obtained on denaturation of tropomycosin with urea or guanidinium chloride indicate that strong hydrophobic environments exist in the native coiled-coil state. 2. Solvent perturbation difference spectra indicate that tyrosyl residues are partially accessible to the solvent. The accessiblity decreases with increasing size of the solvent molecules. 3. Spectral pH titration of tyrosyl residues cannot provide information on the tyrosyl accessibility because conformational change accompanies the increase in pH. 4. Circular dichroism of tyrosyl and phenylalanyl residues is consistent with the effect of imposed conformational rigidity on the partially asymmetrical vibrational fine structure of the 1Lb absorption band of phenyl and benzyl chromophores; the effect is reduced by 70% on unfolding of tropomyosin.
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PMID:Circular dichroic and perturbation spectra of aromatic chromophores in rabbit tropomyosin. Topography of tyrosine residues. 1

Erythroycte ghosts fixed in glutaraldehyde were dehydrated in (a) alcohol or acetone, (b) propylene glycol followed by Epon and embedded in an epoxy resin. A water-soluble urea/glutaraldehyde mixture was also used. The aim was to study the structure of the peripheral protein layer, which contains spectrin and actin, in the absence of OsO4 induced denaturation changes. Ghost membranes prepared in this way had an asymmetrical quadrilaminar structure. A layer of amorphous peripheral protein +/- 18 nm in width covered the entire inner face of the membrane in the form of a coarse meshwork in both Wash I (haemoglobin-containing) and haemoglobin-free ghosts. Cations (Mg2+ or Ca2+, or Mg2+ plus ATP) had no apparent effect on its fine structure. In contrast, the corresponding layer in OsO4-fixed membranes was represented by scanty, fuzzy material attached to the unit membrane only at irregular intervals. The results demonstrate the superior ability of glutaraldehyde to preserve the peripheral protein layer in thin sections, and afford further support for the view that much of this protein normally exists in an unpolymerized state.
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PMID:The ultrastructural organization of the contractile peripheral protein layer of the human erythroycte membrane. 10 28

In 15 lithium-treated psychotic patients, the following variables were examined over two years at 6-monthly intervals; seru lithium levels, serum electrolytes, thyroid function, urinary creatinine and urea, and clinical EEG. The mean serum lithium level was 0.64 mval/l and did not change during the two years. When compared to the pretreatment EEG, visual analysis did not indicate any specific potentials, focal signs, or asymmetrical phenomena such as have been reported in the literature. Only at the beginning of treatment could a small increase in unspecific, abnormal changes be demonstrated, which, however, decreased during the following 18-month period of investigation.
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PMID:[Routine EEG examinations accompanying lithium therapy over two years (author's transl)]. 38 2

The development of rat transitional epithelial cells grown on conventional non-permeable surfaces was compared with development on permeable collagen supports. On glass or plastic surfaces, cells grew as expanding nomolayer sheets. Once confluent, growth continued with a bilayer being formed in most areas and apical cells being continuously sloughed off. Although most cells were interconnected by desmosomes, and junctional complexes were formed, no other indications of differentiation were observed. After 2-3 wk of growth, division stopped and cel death ensued. In contrast, single-cell suspensions plated on collagen-coated nylon disks reassociated into multicellular islands and commenced growth. Mitoses were confined to the basal cells in contact with the permeable substrate. The islands developed into epithelial trilayers, tapering to monolayers along spreading edges. Once the islands were confluent, stratification was completed and appeared similar to that observed in vivo. Germinal cells formed a basal lamina, and the upper layer was composed of large, flattened cells with an unusually thick asymmetrical plasma membrane on the apical surface. Electron microscopic and radioactive tracers demonstrated "leaky" zonulae occludentes with a restricted permeability to small molecules. The movement of urea was retarded in comparison to water. Unlike the slow turnover of adult epithelium in vivo, maturation and sloughing of apical cells were measurable. Transfer of cells could be effected and growth maintained for up to 4 mo. These results may indicate the necessity of a nutrient-permeable growth surface for the polarized differentiation of adult transitional epithelium.
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PMID:The growth and differentiation of transitional epithelium in vitro. 57 72

Renal and ureteral stones may cause asymmetrical renal damage that is not measured accurately by serum creatinine and blood urea nitrogen studies, excretory urography, nephrotomography and arteriography. We evaluated with a renal scintillation camera study 77 patients who had renal or ureteral calculi. The radionuclide procedure provided an accurate measure of total effective renal plasma flow and differential effective renal plasma flow. It had the additional advantages of being a non-invasive procedure, causing no allergic reactions, requiring no patient preparation and producing low radiation exposure.
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PMID:Radionuclide kidney function evaluation in the management of urolithiasis. 67 97

Phloretin dramatically increases cation conductances and decreases anion conductances of membranes treated with ion carriers (nonactin, valinomycin, carbonyl-cyanide-m-chlorophenylhydrazone [CCCP], and Hg(C6F5)2) or lipophilic ions (tetraphenylarsonium [tphAs+] and tetraphenylborate [TPhB-]). For example, on phosphatidylethanolamine membranes, 10(-4) M phloretin increases K+ -nonactin and TPhAs+ conductances and decreases CCCP- and TPhB- conductances 10(3)-fold; on lecithin: cholesterol membranes, it increases K+-nonactin conductance 10(5)-fold and decreases CCCP- conductance 10(3)-fold. Similar effects are obtained with p- and m-nitrophenol at 10(-2) M. These effects are produced by the un-ionized form of phloretin and the nitrophenols. We believe that phloretin, which possesses a large dipole moment, adsorbs and orients at the membrane surface to introduce a dipole potential of opposite polarity to the preexisting positive one, thus increasing the partition coefficient of cations into the membrane interior and decreasing the partition coefficient of anions. (Phloretin may also increase the fluidity of cholesterol-containing membranes; this is manifested by its two- to three-fold increase in nonelectrolyte permeability and its asymmetrical effect on cation and anion conductances in cholesterol-containing membranes.) It is possible that pholoretin's inhibition of chloride, urea, and glucose transport in biological membranes results from the effects of these intense intrafacial dipole fields on the translocator(s) of these molecules.
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PMID:Effect of phloretin on the permeability of thin lipid membranes. 94 75

In five patients with chronic renal failure, rapid correction by dialysis of hypertension and/or high blood urea levels provoked acute neurological disorders, followed by slowly reversible neuropsychiatric disturbances. Focal EEG alterations were noted in three patients with normal carotid angiograms. Our cases differed from those usually described as suffering from the dialysis disequilibrium syndrome because of their duration, the severity of mental disturbances, and the asymmetrical pattern of EEG abnormalities. We propose that the symptoms observed could be due to cerebral ischemia. This possibility emphasizes the importance of limiting the duration and efficiency of the first dialyses in patients with severe hypertension and high nitrogen retention, especially if high performance dialyzers are used.
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PMID:Unusual aspects of the dialysis disequilibrium syndrome. 95 37

The authors report 22 cases of uretero-ileo-plasty for uretero-hydronephrosis due to schistosomiasis. The indications for operation depend on the following criteria: the degree of dilatation which varies from simple atonia to very large hydronephrosis which one must not wait for, ureteral stenosis, vesico-ureteral reflux, the degree of renal failure assessed by studies of creatinine and urea clearance and the resistance to treatment. The operative technique which is not specific for bilharziasis includes uretero-ileo-plasty which is often bilateral, for even in asymmetrical cases, the least affected ureter is often of poor quality. There were failures in two cases due to irreversible renal failure, and in two cases, due to peritonitis. The late results of the other cases appear very favourable: increased vesical capacity, diminution of cystalgia, comfort and improved, general health, were the main factors. Stenosis of the anastomosis, vesico-ureteral reflux and urinary infection, acidosis, lithiasis are rare or not very severe.
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PMID:[Uretero-ileoplasty in bilharzian uretero-hydronephrosis]. 95 96

Experimental results on the transcription of Balbiani rings BR 1 and BR 2 of Chironomus thummi salivary gland chromosomes are presented. The DNA of Balbiani ring 2, which is the most active puff in larvae, is transcribed into large RNA molecules of about 22 X 10(6) D which resist degradation by heating, formamide or urea treatment. The asymmetrical distribution of electrophoretic profiles of BR 2 RNA and the appearence of a symmetrical BR RNA peak in the nucleoplasm suggest the synthesis of (mainly) one RNA fraction in BR 2. The gel electrophoretic patterns of BR 1 RNA are, on the other hand, characterized by the appearance of two main fractions of high molecular weight RNA, one of which corresponds in molecular weight (about 22 X 10(6) D) to BR 2 RNA. The second RNA fraction is significantly smaller in molecular size (molecular weight: about 10 X 10(6) D) and, like the 22 X 10(6) D RNA fractions of the two Balbiani rings, resistant against heating in 8 M urea. Binding to poly (U) sepharose of a significant part of Balbiani ring RNA suggests the existence of poly (A) and/or oligo (A) sequences in the Balbiani ring RNA. -- In situ hybridization of BR RNA to the salivary gland chromosomes reveals accumulation of silver grains over the Balbiani ring regions only and demonstrates the restriction of BR DNA sequences to the corresponding Balbiani ring.
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PMID:The transcripts of Balbiani rings from Chironomus thummi. Giant RNA molecules with messenger characteristics. 100 Nov 42

The surface tension of glycerylmonooleate-hexadecane lipid bilayer membranes and the lifetime of gramicidin A channels were measured at various concentrations of the surrounding solutions. For HCl the surface tension is essentially constant at approximately 5 mN/m up to approximately 1 M, whereas the average lifetime increases approximately 40-fold. At higher concentrations the surface tension decreases markedly. For CsCl the surface tension is constant up to about 1 M then increases with salt level. The average lifetime in this case increases about sixfold. In both cases the lifetime levels off and even decreases at higher salt levels. The increase in lifetime observed with ion activity is therefore qualitatively different from, and not explained by, the established dependence of lifetime on membrane properties (Elliot, J.R., D. Needham, J.P. Dilger, and D.A. Haydon. 1983. Biochim. Biophys. Acta. 735:95-103). We have previously proposed that ion occupancy is a determinant of channel stability, and to test this hypothesis the voltage dependence of channel lifetime was measured in asymmetrical solutions. For the case of a potassium chloride solution on one side of the membrane and a hydrogen chloride solution, on the other, the voltage dependence of the lifetime is asymmetrical. The asymmetry is such that when the electrical field is applied in the direction of the chemical gradient for each of the ions, the channel lifetime approaches, at increasing field strengths, that of a symmetrical solution of the respective ion. The voltage dependence of the surface tension, on the other hand, is negligible for the range of voltages used. These results, and the earlier findings that the order of the lifetimes for the alkali cations generally agree with the order of the permeability selectivity of the gramicidin A channel, support the hypothesis that ion occupancy is a major factor determining the lifetime of gramicidin A channels. The effects of multivalent blockers and osmotic agents were also tested. Ba2", La3+,and Mg2" decrease the lifetime and conductance markedly. Sucrose and urea increase the lifetime and decrease the conductance. The voltage dependence of the lifetime in symmetrical solutions was examined. Contrary to previous reports it was found that the lifetimes for K+, Cs', and H+ are voltage dependent. For 0.5 M HCI the lifetime decreases monotonically by .60% at 150 mV, and for 0.5 M KCI the lifetime increases by -60% at 200 mV. Below 10 mM there is no effect of voltage for H+, K+, and Cs+. These effects of blockers, osmotic agents, and voltage on the lifetime, as well as the lack of effect of voltage at low salt levels, are consistent with the occupancy hypothesis.
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PMID:Evaluation of surface tension and ion occupancy effects on gramicidin A channel lifetime. 245 76


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