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The effects of glycerol were investigated in guinea pigs in which the endolymphatic sac (ES) and duct (ED) had been obliterated unilaterally. Twenty-four hours after obliteration of the right ES and ED, glycerol was injected intraperitoneally. One to two hours after administration of glycerol, collapse or folding of Reissner's membrane was observed in the operated cochlea. No remarkable change was found in the nonoperated ear. The lumen of the ES of the nonoperated ear collapsed with intraluminal stainable substance within 1 h. The volume of the stainable substance increased with time and could still be seen 4 h after the injection of glycerol. Twenty-four hours after the injection of glycerol, the configuration of the ES was normal again. In addition, the animals showed marked unilateral (operated side) vestibular dysfunction after injection of glycerol. These findings suggest that the ES also has a secretory capacity and plays an important role in inner ear fluid volume and pressure regulation.
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PMID:Effect of glycerol on the guinea pig inner ear after removal of the endolymphatic sac. 770 Jun 12

Exposure of yeast cells to high osmolarities leads to dehydration, collapse of ion gradients over the plasma membrane and decrease in cell viability. The response of yeast cells to high external osmolarities is designated osmostress response. It is likely that both osmoregulatory and general stress reactions are involved in this so far poorly understood process. Part of the response aims at raising the internal osmotic potential, i.e. the production of osmolytes such as glycerol, and exclusion of toxic solutes. In addition, heat-shock proteins and trehalose are synthesized, probably to protect cellular components and to facilitate repair and recovery. Recent analyses of osmosensitive yeast mutants strongly suggest the involvement of protein kinase-mediated signal-transduction pathways in the maintenance of the osmotic integrity of the cell. This has stimulated interesting hypotheses as to the actual osmosensing mechanism.
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PMID:Osmostress response of the yeast Saccharomyces. 793 16

Previous work showed that the clearance from plasma of chylomicron-like emulsions injected intravenously was affected by the acyl chains of the constituent triacylglycerols. Compared with emulsions containing triolein (OOO) as the only triacylglycerol, clearances were decreased by a single saturated chain in emulsions containing 1,3-dioleoyl-2-stearoyl-sn-glycerol (OSO), 1,2-dioleoyl-3-stearoyl-sn-glycerol (OOS) or 1-stearoyl-2,3-dioleoyl-sn-glycerol (SOO). The differences in clearance may reflect physical differences at the oil-water interface related to chain interactions of the triacylglycerol structures with other lipid components. In the present work lipid monomolecular films at the air-water interface were used to establish the capacity of OOO to interact with the pure synthetic triacylglycerols OOS and SOO, and the capacity of OOS and SOO to co-exist in monolayers of lecithin and of cholesterol was compared with OOO. Substituting one oleoyl chain by a stearoyl chain induced a 20% condensation in monomolecular films of the pure triacylglycerols. Mixtures of OOO with either pure egg yolk phosphatidylcholine or cholesterol also showed substantial condensing effects. In contrast substituting one oleoyl chain by a stearoyl chain substantially lessened the condensing effects. At surface pressures above the collapse pressure of the pure triacylglycerols, substantially more OOO than OOS or SOO was retained in mixed monolayers with phosphatidylcholine. These differences could underlie the effects on metabolism of saturated chains in emulsion triacylglycerols.
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PMID:The condensing effects of egg lecithin and cholesterol on triolein monolayers are inhibited by substitution of one saturated acyl chain in the triacylglycerol. 811 51

Replacement of the tracheal conduit remains a difficult and unresolved surgical problem. We present an experimental study of 20 pigs undergoing replacement of the cervical trachea using glutaraldehyde (n = 5), glycerol (n = 5), lyophilized (n = 5) and cryopreserved (n = 5) pretreated allogenic grafts (AGs). In the lyophilized group, a stainless steel spiral endoprosthesis was used as stent. A segment of native trachea measuring 3.2 +/- 0.3 cm (range: 1-5 cm) in length and 1.4 +/- 0.02 cm in diameter was resected and replaced with AGs measuring 3.8 +/- 0.2 cm in length and 1.4 +/- 0.2 cm in diameter. Neither immunosuppressive agents nor steroids were given. Animals were followed up with weekly bronchoscopy, and trachea and chest roentgenography. Those receiving glutaraldehyde AG (21.6 +/- 6.4 days) and lyophilized AG (19.5 +/- 7.8 days) had a longer survival than those receiving glycerol AG (6.8 +/- 0.3 days) and cryopreserved AG (5 +/- 0.5 days). At postmortem, grafts were examined grossly and with light microscopy. The cause of death was always airway obstruction, and the underlying processes were: 1) collapse due to cartilaginous microscopic necrosis in cryopreserved and glycerol AGs; 2) necrosis of allograft which crossed the spiral stent for lyophilized AGs; 3) granulation formation, tissue necrosis and anastomosis leakage in glutaraldehyde AGs. Results demonstrate that passage of necrotic tissue across the grafts represent the common failure denominator, making the different AGs studied unsuitable for long-segment tracheal replacement.
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PMID:Tracheal allograft replacement. An unsuccessful method. 812 58

Two cases of bilateral Lermoyez's syndrome and one case of unilateral Lermoyez's syndrome are reported. The patients had recurrent episodes of vertigo with improvement of hearing or tinnitus, which is characteristic is Lermoyez's syndrome. In case 1, a 48-year-old female, dehydration with glycerol or furosemide induced nystagmus and improved bilateral hearing and the gain of the vestibulo-ocular reflex, while overhydration with drinking water impaired bilateral hearing with disappearance of nystagmus. These findings indicate that she had endolymphatic hydrops in both ears, suggesting that simultaneous changes in bilateral cochlear and vestibular function induce Lermoyez's syndrome. In case 3, a 52-year-old female, which we already reported, endolymphatic collapse in both ears may have changed bilateral inner ear function, resulting in Lermoyez's syndrome. On the other hand, patients 2, a 47-year-old male, experienced a vertigo attack with improvement of unilateral hearing after defibrinogenation therapy. In this case, slowly developing insufficiency of the inner ear blood supply may have caused the gradual hearing loss. It seemed that decreasing blood viscosity by defibrinogenation allowed blood to rush into the labyrinth, causing vertigo but at the same time improving hearing. We proposed that there are two types of Lermoyez's syndrome, bilateral (cases 1 and 3) and unilateral (case 2).
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PMID:[Three cases of Lermoyez's syndrome and its pathophysiology]. 885 32

Rhodanese is used widely as a model for protein folding, since the enzyme as usually studied refolds poorly unless the process is assisted. Here, the influence of the partitioning of the folding intermediates of bovine rhodanese on the efficiency of its refolding has been investigated. Metastable intermediates can be formed during unfolding of the enzyme. The stabilities of these intermediates and the native protein with respect to chemical unfolding can be greatly increased by high concentrations of glycerol. The concentration dependence of the protein folding kinetics indicates that associative processes occur during renaturation. It is suggested that, during enzyme refolding, rhodanese undergoes fast collapse to an intermediate state I' which partitions to at least two other states (I" and I"'). One of these states (I"') is able to refold to the native enzyme, while the other state (I") is in equilibrium with I' and is prone to slow irreversible aggregation. Stabilization of I" against irreversible aggregation by glycerol results in increased yield of the protein refolding and a complex temperature dependence of the protein renaturation. The nature of the I" type intermediate has been investigated. Based on the fact that extensive hydrophobic surfaces are exposed during formation of the intermediates, it is suggested that partial dissociation of the two structural domains of rhodanese is an early event in unfolding. Interactions of different folding intermediates of rhodanese with the chaperonin GroEL were investigated, and the results suggest that the more extensively unfolded intermediates bind tighter than those that appear later on the rhodanese refolding pathway.
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PMID:Rhodanese folding is controlled by the partitioning of its folding intermediates. 950 86

Rodlike amphiphilic molecules that contain exclusively aromatic building-blocks and no flexible alkyl chains have been synthesized and their mesomorphic properties investigated. These novel compounds bear diol head groups of different size (2,3-dihydroxypropyloxy or 5,6-dihydroxy-3-oxahexyloxy groups) at one end of a biphenyl unit, various aromatic segments (benzyloxy, 4-, 3-, or 2-methylbenzyloxy, phenoxy groups) at the other, and additional methyl substituents in different positions. They were synthesized by using Suzuki cross-coupling reactions as the key steps. Their thermotropic mesomorphism was investigated by means of polarized light optical microscopy, differential scanning calorimetry, and, for enantiotropic phases, by X-ray scattering. The liquid crystallinity of this class of compounds is influenced by protic solvents, such as water and glycerol. Dependent on the temperature and the solvent content, different SA phases were found. Several mesophases resulting from the frustration of these layer structures (e.g., different columnar phases, optical isotropic mesophases, and nematic phases) were also present. The smectic phases have different degrees of intercalation (SAd, SA2). The columnar phases are supposed to be ribbon structures that result from the collapse of the smectic layers. They occur in some pure compounds or they are induced upon the addition of protic solvents. The particular phase sequences of the different compounds depend mainly on the position of the methyl substituents at the biphenyl cores and are largely determined by the degree of intercalation of the aromatic cores.
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PMID:Thermotropic and lyotropic liquid crystalline phases of rigid aromatic amphiphiles 1107 53

The release of a model volatile (diacetyl) from a system based on a starch matrix, in which the volatile is dispersed, was studied. Kneading was used to obtain a homogeneous mixture (melt) composed of starch, glycerol alpha-amylase, and diacetyl. Samples were then ground to powders. When the starch powders were exposed to 30% relative humidity (RH) at 20 degreesC, no degradation of the starch matrix occurred. The samples only showed an initial burst release of diacetyl (around 10% of the loaded dose), whereas the remaining amount of diacetyl was not released, most likely due to the glassy character of the matrix and the low solubility of diacetyl in the matrix. However, when the samples were incubated at 90% RH, due to the uptake of moisture by the particles full release of the entrapped volatile occurred. The release of diacetyl from the matrix without enzyme followed first-order kinetics and, as expected, the release rate increased with decreasing particle size. Due to absorption of water, the enzyme became active and starch degradation occurred. The initial release of diacetyl from amylase-containing matrixes followed first-order kinetics as well. However, once the matrix was degraded to a certain extent, the particles collapsed, which was associated with concomitant rapid increase in release. The time at which the particle collapse occurred decreased with increasing enzyme concentration in the matrix. In conclusion, it is demonstrated that the release of a volatile from starch matrixes can be modulated both by the amount of coencapsulated matrix-degrading enzyme and by the humidity of the environment.
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PMID:Modulated release of a volatile compound from starch matrixes via enzymatically controlled degradation. 1188 16

At high concentration (98% or higher, v/v), glycerol induces collapse of acid-denatured cytochrome c into a compact state, the G(U) state, showing a molten globule character. The G(U) state possesses a nativelike alpha-helix structure but a tertiary conformation less packed with respect to the native state. The spectroscopic properties of the G(U) state closely resemble those of the molten globule stabilized by the organic solvent from the native protein (called the G(N) state), indicating that glycerol can stabilize the molten globule of cytochrome c either from the native or the acid-denatured protein. The G(U) and the G(N) states show spectroscopic (and, thus, structural) properties and stabilities comparable to those of molten globules stabilized by different effectors, despite the fact that the mechanisms involved in the molten globule formation may significantly differ. This implies in cytochrome c a hierarchy for the rupture (native-to-molten globule) or the formation (unfolded-to-molten globule) of intramolecular interactions leading to the stabilization of the molten globule state of the protein, independently from the effector responsible for the structural transition, in accord with the sequential model proposed by Englander and collaborators.
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PMID:Glycerol-induced formation of the molten globule from acid-denatured cytochrome c: implication for hierarchical folding. 1190 65

The effect of sodium tetraborate (Na(2)B(4)O(7), borax) on the thermal property of frozen aqueous sugar and polyol solutions was studied through thermal analysis. Addition of borax raised the thermal transition temperature (glass transition temperature of maximally freeze-concentrated solutes; T(g)') of frozen sucrose solutions depending on the borax/sucrose concentration ratios. Changes in the T(g)' of frozen mono- and disaccharide solutions suggested various forms of complexes, including those of a borate ion and two saccharide molecules. Borax exerted the maximum effect to raise the oligosaccharide and dextran T(g)'s at borax/saccharide molar ratios of approximately 1-2 (maltose and maltooligosaccharides), 2 (dextran 1060), 5 (dextran 4900), and 10 (dextran 10200). Further addition of borax lowered T(g)'s of the saccharide solutions. Borax also raised T(g) and T(g)' temperatures of frozen aqueous glycerol solutions. The decreased solute mobility in frozen solutions by the borate-polyol complexes suggested higher collapse temperature in the freeze-drying process and improved stability of biological systems in frozen solutions.
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PMID:Effect of sodium tetraborate (borax) on the thermal properties of frozen aqueous sugar and polyol solutions. 1280 43


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