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)

Differential lung ventilation (DLV) with PEEP has been used to oxygenate patients with severe unilateral or asymmetrical lung disease. Many different ventilator systems have been used to deliver DLV, but the question of whether or not to synchronize the ventilation of the 2 lungs has not been answered. Twelve mongrel dogs were given a unilateral hydrochloric acid (HCl) injury and divided into 2 groups, one receiving synchronous and the other receiving asynchronous DLV. The assignment of synchronization and side of injury was allocated randomly. A computer-controlled DLV system was used to ventilate the dogs with equal tidal volumes to each lung. The respiratory rate was feedback controlled to maintain PaCO2 at 35 torr. After injury, 10 cm H2O of PEEP was applied to the injured lung and the dogs were ventilated with FIO2 = 0.40 for 4 h. There was no statistically significant difference in gas exchange ([PaO2, Qva/Qt, PaCO2, P(A-a)O2] or hemodynamics [mean arterial pressure (MAP), CVP, mean pulmonary arterial pressure (MPAP), mean pulmonary arterial wedge pressure (WP), cardiac output in triplicate (Q), heart rate (HR)] between the 2 groups. With this particular model, there is no need to synchronize the 2 ventilators when using DLV with unilateral PEEP.
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PMID:Synchronous versus asynchronous differential lung ventilation with PEEP after unilateral acid aspiration in the dog. 634 44

Bilirubin is a linear tetrapyrrole whose conformation is affected by internal hydrogen bonds formed between the carboxyl side chains and dipyrromethenone rings. Structural variations include: constitutional isomerism of the vinyl or carboxyethyl side chains, geometric isomerism of the methene bridges, tautomerism of the lactam groups, conformational rotations about the central methylene bridge and ionization of one or both carboxyl groups. Aggregation of the dianion into dimers and multimers may occur. The pKa' values of the two carboxyl groups are affected greatly by the environment and may differ widely in micellar solutions like bile. Solubility of bilirubin in water is less than 1 nM at pH = 7 and about 0.1 microM at pH = 8. Nonetheless, it dissolves poorly in most lipid solvents, except for asymmetrical chloroalkanes. Hydrogen bond-breaking solvents, especially dimethyl sulfoxide, are most effective in solubilizing bilirubin. In bile salt solutions, solubility of bilirubin is well above the concentrations of unconjugated bilirubin found in normal human gallbladder bile, and is impaired by lecithin but unaffected by cholesterol. At physiological pH in bile salt solutions, bilirubin is predominantly in its monoanion form that binds readily to the micelles. In such solutions, addition of physiological concentrations of calcium precipitates calcium bilirubinate, leaving residual bilirubin concentrations of up to 15 microM in 50 mM taurocholate or close to the maximum bilirubin concentrations in normal bile. Studies in which disodium bilirubinate is dissolved in bile salt solutions and pH is adjusted to the physiological range reveal that metastable supersaturation with bilirubin may occur and that a mesophase may also form in the presence of lecithin, akin to that seen with cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Bilirubin chemistry, ionization and solubilization by bile salts. 647 84

The synergistic interaction between odor and taste in flavor-toxicosis conditioning was tested in two experiments. The temporal interval between a 2-min odor and a 2-min taste was varied for thirsty rats licking at a water spout. In the first experiment, taste was presented at time zero, and odor was presented at -10, -1, 0, 1 and 10 min to independent groups in a simple compartment. In the second experiment, taste was presented at 0, and odor was presented at -5, -2, and 0 min in a "wind tunnel" apparatus. The results indicated that odor alone is an ineffective conditioned stimulus for a toxic unconditioned stimulus under our conditions, simultaneous (0-min) presentation of odor with taste potentiates the odor component so that it becomes more effective than the taste component, a 2-min interval between odor and taste attenuates potentiation, and a 5-min interval disrupts the effect, and the interaction in asymmetrical, that is, odor has no such systematic effect on the conditioning of taste.
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PMID:Taste potentiation of poisoned odor by temporal contiguity. 648 15

The Fleisch pneumotachometer (PTM) gives the instantaneous respiratory gas flow, and when integrated provides the volume of gas displaced. Its output signal is proportional to the product of the flow and the viscosity of the gas. The calibration factor is thus different for inspiration and expiration. Since the exact value of the viscosity is unknown, accurate figures for flow cannot be obtained. This study examines the use of a precisely sinusoidal pump with adjustable speed and capacity, displacing air in a thermostatically controlled chamber containing water at 37 degrees C stirred by a propellor. Thus air at ambient temperature flows through the PTM on inspiration, and on expiration the gas exactly simulates in temperature and humidity that normally expired by a human subject. This makes the output signal asymmetrical, with the expired volume VTE being greater than the inspired value, the ratio VTE/VTI = 1.035. Other sources of error, notably temperature and pressure changes in the chamber and differences in the proportions of O2 and CO2 in the expired gas, have been considered from both a theoretical and experimental standpoint. Their combined effects produce a less than 0.5% error. Using this pump, the Fleisch PTM can be calibrated empirically without making any assumptions about the temperature and viscosity of the expired gas mixture.
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PMID:BTPS calibration of heated Fleisch pneumotachometer. 665 70

Exposure to inescapable shock disrupted performance in both shock- and water-escape tasks. These deficits were prevented in mice that were previously trained in the same task. However, an asymmetrical immunization effect was seen in a cross-stressor paradigm. Whereas deficits of water-escape performance engendered by inescapable shock were prevented by prior shock-escape training, the deficits of shock-escape performance were not eliminated by prior water-escape training. Evidently, the immunization effect occurs when initial training and subsequent testing are conducted in the same task, or when the initial training and uncontrollable stress session involve the same aversive stimulus. Norepinephrine determinations revealed that reductions of the amine introduced by inescapable shock were unaffected by prior shock-escape training and were enhanced by prior exposure to the stress of water immersion. Thus, although the performance deficit introduced by inescapable shock may be related to variations of norepinephrine, the immunization effect probably was unrelated to alterations of this transmitter. Rather, the data provisionally suggested that the immunization stems from two independent factors: Namely, initially training animals in an active escape task may (a) disrupt subsequent learning that the inescapable stress actually is uncontrollable and (b) limit the influence of the motor deficits introduced by uncontrollable shock on subsequent escape performance.
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PMID:Cross-stressor immunization against the behavioral deficits introduced by uncontrollable shock. 668 62

We assessed hemodynamics, total lung and chest wall compliance (CT) and gas exchange using two different levels of PEEP during controlled ventilation in two different groups of patients with ARF; in the first group (Group 1, 12 patients) chest X-Rays showed a symmetrical pattern of bilateral alveolar infiltrates; in the second group (Group 2, 5 patients) chest X-Ray showed a asymmetrical pattern with unilateral lobar consolidation. A first level of PEEP (best PEEP = 9 +/- 3 cm H2O) produced an improvement in CT and in gas exchange with a slight decrease in cardiac index in both groups; but improvement in PaO2 (from 64 +/-33 to 122 +/- 76 torr, p less than 0.001 in Group 1, and from 76 +/- 39 to 91 +/- 33 torr, p less than 0.05 in Group 2) and decrease in QS/QT were not as well marked in Group 2 as i Group 1. A second level of PEEP (high level PEEP: 20 +/- 4 cm H2O) produced a sharp decrease in CT and required hemodynamic support in each case (blood volume expansion with or without Dopamine infusion) to maintain cardiac index within a normal range. In Group 1 this high level PEEP produced a greater improvement in gas exchange (PaO2 increased from 122 +/- 76 to 194 +/- 76, p less than 0.01) but in Group 2 it had a deleterious effect, producing a decrease in PaO2 (from 91 +/- 33 to 76 +/- 41 torr, p less than 0.05), and an increase in QS/QT; with this higher PEEP we also noted an increase of alveolar dead space in Group 2. This study demonstrates the efficiency of high levels of PEEP to reduce QS/QT in ARF but also shows its limitations: namely reduction in cardiac performance and in efficiency if the damage to one lung is significantly more pronounced than that to the other lung.
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PMID:Controlled ventilation with best positive end-expiratory pressure (PEEP) and high level PEEP in acute respiratory failure (ARF). 702 32

The bidirectional fluxes and energetics of methotrexate transport in Ehrlich ascites tumor cells were profoundly altered in a high [K+], low [Na+] buffer (K+ buffer). Incubation of cells for 30 min in K+ buffer reduced influx by 27% and the efflux rate constant by 53%. This asymmetrical inhibition of bidirectional fluxes increased the net exchangeable intracellular methotrexate level per cell, but the actual intracellular methotrexate concentration at the steady state was similar to that in Na+ buffer, since the high [K+] caused an increase in intracellular water. Because cells exposed to K+ buffer were depolarized, the apparent electrochemical potential difference for methotrexate was markedly reduced. However, the steady-state intracellular methotrexate level was still related to the extracellular concentration by an absorption isotherm, indicating asymmetry in the bidirectional fluxes similar to that observed in Na+ buffer and thus predicting that transmembrane gradients would be produced at very low extracellular methotrexate concentrations. Glucose, which had little effect on bidirectional fluxes and reduced the steady-state level of methotrexate in Na+ buffer, stimulated influx, inhibited efflux and rapidly increased the steady state in K+ buffer similar to the effects of glucose in the presence of glucose in the presence of iodoacetate in Na+ buffer. Finally, cells exposed to k+ buffer exhibited trans-stimulation of [3H]methotrexate influx when loaded with non-labeled methotrexate, a phenomenon not observed in Na+ buffer. The results indicate that although methotrexate transport is not affected by transient changes in the cationic composition of the extracellular compartment, prolonged exposure of cells to a high [K+], low [Na+] environment markedly alters the physical properties of the cells and the transport parameters for methotrexdate and reveals characteristics of the methotrexate carrier system that are not evident in other buffer systems.
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PMID:K+-induced alterations of energetics and exchange diffusion in the carrier-mediated transport of the folic acid analog, methotrexate, in Ehrlich ascites tumor cells. 719 70

Spinach chloroplasts are spread at a heptane-water interface. Applying a novel capacitative electrode introduced in the preceding paper (Trissl, H.-W. (1980) Biochim. Biophys. Acta 595, 82-95) the changes of the interface potential induced by single laser flashes are investigated. The following results are obtained: (1) The chloroplasts spread at the interface form a thin layer with asymmetrical orientation. The structural state of this layer is discussed. (2) The photovoltage from the interfacial layer shows similar characteristics as the field-indicating absorption change of chloroplast suspensions, the latter reflecting the photosynthetic primary charge separation: (a) Both can be abolished by addition of 3-(3',4'-dichlorophenyl)-1,1-dimethylurea. (b) About one half of the signals can be reactivated by addition of N-methyl-phenazonium methosulfate. (c) Both signals saturate at low flash light intensities. (d) Both signals can be abolished by background illumination of comparable intensities. (e) Both signals are independent of the ionic strength. (3) The half-rise time of the photovoltage is determined to be less than 3 ns. It is suggested from these results that the photovoltage from the interfacial layer reflects the primary charge separation process in photosynthesis, i.e. the latter is accomplished also within less than 3 ns.
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PMID:II. Electrical measurements in the nanosecond range of the charge separation from chloroplasts spread at a heptane-water interface. Application of a novel capacitive electrode. 734 87

L-[3H]Glutamate binding sites with characteristics resembling that of membrane-bound alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate-subtype L-glutamate receptors have been solubilized from pig brain synaptic junctions by Triton X-114. Binding of [3H]AMPA to these soluble sites in the presence of KSCN results in a curvilinear Scatchard plot that can be resolved into a high-affinity component and a low-affinity component. These Triton-X-114-solubilized sites can be further separated into two species of binding sites by gel-filtration chromatography or sucrose-density-gradient centrifugation. The pharmacological profiles of these two species of binding site are almost identical, and the rank orders of potency for glutamatergic drugs in displacing L-[3H]glutamate binding to these sites are quisqualate > 6,7-dinitroquinoxaline-2,3-dione > 6-cyano-7-nitroquinoxaline-2,3-dione > AMPA > L-glutamate > kainate >> N-methyl-D-aspartate = L-2-amino-4-phosphonobutyrate. Both sites are found to bind [3H]AMPA, and in the presence of KSCN the binding activities are significantly enhanced. Analysis of the hydrodynamic behaviour of these binding sites by sucrose-density-gradient centrifugation in H2O- and 2H2O-based solvents and gel-filtration chromatography has revealed that one of these sites (Stokes radius 8.3 nm, sedimentation coefficient 18.5 S) consists of 562 kDa protein and 281 kDa detergent, and the other site (Stokes radius 9.6 nm, sedimentation coefficient 13.4 S) consists of 352 kDa protein and 569 kDa detergent. Frictional coefficients of these sites indicate that these receptor-detergent complexes are asymmetrical in structure, consistent with large transmembrane proteins.
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PMID:Hydrodynamic and pharmacological characterization of putative alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate-sensitive L-glutamate receptors solubilized from pig brain. 751 51

Isolated single chicken hair cells and pieces of epithelium without the tectorial membrane, either freshly isolated or in tissue culture, were studied using water-jet stimulation of their stereovillar bundles and current injection. Responses were measured under enhanced video-microscopic observation or while using a differential photodiode technique sensitive down into the nanometer range. When stimulated with a water jet at low displacement amplitudes up to about 200 nm, the stereovillar bundle displacement was asymmetrical, indicating a lower stiffness in the excitatory direction, but the reverse was true at higher displacement amplitudes. Undamaged bundles showed no mechanical resonances below 1 kHz. In damaged bundles, however, such resonances were prominent and accompanied by splaying of the stereovilli. Hair cells in the epithelium showed small bundle movements (0.6 nm/mV) whose polarity depended on the polarity of the injected current. These movements probably resulted from activation of the bundle's adaptation motors.
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PMID:Mechanical and electromechanical properties of the stereovillar bundles of isolated and cultured hair cells of the chicken. 792 7


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