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PubMed2004

Interstitial glycerol increase in microdialysis after glycerol enema.

Microdialysis allows the measurement of extracellular concentrations of various endogenous substances, such as excitotoxic amino acids or metabolic end products. Recent advances in microdialysis techniques have led to widespread use in patients with brain disorders. Microdialysis has proved to be a useful tool for monitoring cerebral biochemical metabolism and secondary brain damage in severe head injury, subarachnoid haemorrhage, stroke, and epilepsy. In our neurosurgical intensive care unit, microdialysis was performed on 42 patients. Four patients received a glycerol enema for therapy of a paralytic ileus. A glycerol peak was observed in both intracerebral and subcutaneous microdialysis occurring three to four hours after the glycerol enema in all four patients. The highest glycerol value was 1187micromol/l cerebral and 2997micromol/l in the subcutaneous tissue. Our study indicates that besides the measurement of serum osmolality and serum glycerol level, microdialysis may be an additional valuable tool to control glycerol therapy in patients with cerebral oedema and elevated intracranial pressure.

Adult↗
PubMed1988

A simple chromatographic procedure for the detection of cyclized archaebacterial glycerol-bisdiphytanyl-glycerol tetraether core lipids.

Archaebacterial glycerol-bisdiphytanyl-glycerol tetraether core lipids containing from one to eight cyclopentane rings could be resolved from each other and from the parent uncyclized C40, C40 lipid by TLC. The core lipids of examples from the genera Methanobacterium, Methanobrevibacter, Methanogenium and Methanoplanus did not contain cyclized forms of glycerol-bisdiphytanyl-glycerol tetraethers, whereas the core lipids of Methanosarcina barkeri contained glycerol-bisdiphytanyl-glycerol tetraethers with from one to three cyclopentane rings in each C40 isopranoid chain.

Archaea↗
PubMed1990

Neuraminic acid and related compounds. V. Syntheses of biologically active sialosyl-glycerol derivatives and galactosyl-glycerol derivative.

New 1-acyl-sialosyl-glycerol derivatives (1a--d alpha, 1a--d beta, 2 alpha, 2 beta, which mimic the structure of the capsular polysaccharide of group C meningococcal were synthesized by the use of a chiral glycerol derivative, and were found to have phospholipases A2 and C inhibitory activities. Furthermore, synthesis of 2-palmitoyl-sialosyl-glycerol derivative (4 alpha, 4 beta, 5 alpha, 5 beta), galactosyl-glycerol derivative (6), and sialosyl-galactosyl-glycerol derivative (7) were carried out to examine the difference between these activities. Among these sialosyl derivatives, 3-palmitoyl-sialosyl-glycerol derivatives (1--3 alpha, 1--3 beta) demonstrated the most potent inhibitory activities.

Galactosides↗
PubMed1975

Combinations of glycerol percent, glycerol equilibration time, and thawing rate upon freezability of bull spermatozoa in plastic straws.

Twelve ejaculates were used in a central composite experiment to test 15 combinations of glycerol (7, 9, 11, 13, or 15%), glycerol equilibration times (1, 2, 4, 8, or 16 h) and thawing rates (water at 35 C for 15 s, 50 C for 13 s, 65 C for 11 s, 80 C for 9 s, or 95 C for 7 s). Semen was diluted in heated skim milk-glycerol, packaged in .3-ml. Continental U.S. straws and frozen in liquid nitrogen vapor. Based on post-thaw progressive sperm motility after storage at -196 C for 9 to 11 days, estimated optima from multiple regression were 10.7% for glycerol, 2.0 h for glycerol equilibration time, and 76 C for thawing bath temperature. Only the linear effect for each variable was significant. Much faster thawing rates and shorter glycerol equilibration times than those for freezing bull spermatozoa in glass ampules should be used for maximum post-thaw sperm motility in straws.

Animals↗
PubMed1985

Glycerol neurolysis: neurophysiological effects of topical glycerol application on rat saphenous nerve.

The effect of topical glycerol application on normal and previously injured saphenous nerves was tested in 20 Sprague-Dawley rats. Anhydrous glycerol treatment of five normal nerves showed a rapid loss of C-fiber conduction within 5 minutes of application, while after 10 to 30 minutes, a complete conduction blockade in all fiber types was produced. The effect of anhydrous glycerol on both spontaneous firing from the neuroma and impulse propagation within the nerve was examined in 11 rats that had undergone saphenous neurotomy 7 days previously. In these animals, cessation of spontaneous action potential production from the neuroma was the earliest electrophysiological change noted, followed by loss first of C-fiber, then of A-fiber conduction. Graded concentrations of glycerol (25%, 50%, 75%, and 100%) were used in four rats with saphenous neuromas, which allowed selective blockade of spontaneous action potential generation and C-fiber conduction with minimal effect on A-fibers. The neurophysiological mechanism of glycerol neurolysis appears to be a nonspecific conduction blockade of large and small fibers, which is established within minutes of its application. Spontaneous firing within damaged axons, which may play a role in a variety of cranial and peripheral nerve sensorimotor syndromes, is also exquisitely sensitive to glycerol application.

Action Potentials↗
PubMed1999

Metabolism of [1,3-(13)C]glycerol-1,2,3-tris(methylsuccinate) and glycerol-1,2,3-tris(methyl[2,3-(13)C]succinate) in hepatocytes from Goto-Kakizaki rats.

The metabolism of [1,3-(13)C]glycerol-1,2,3-tris(methylsuccinate) and glycerol-1,2,3-tris(methyl[2,3-(13)C] succinate) was examined in hepatocytes prepared from hereditarily diabetic Goto-Kakizaki rats. Over 120 min incubation in the presence of one of the two (13)C-labelled esters (2.5 mM), the output of (13)C-enriched glucose averaged 57.1 +/- 18.5 and 54.1 +/- 22.7 nmol per 10(6) cells, when expressed as [1,3-(13)C]glycerol and [2,3-(13)C] succinate equivalent, respectively. In the case of [1,3-(13)C]glycerol-1,2,3-tris(methyl-succinate), the molecules of glucose were symmetrically labelled. In the case of glycerol-1,2,3-tris(methyl[2,3-(13)C] succinate), however, both the single-labelled and double-labelled isotopomers of glucose contained more (13)C atoms in their C(6)-C(5)-C(4) than C(1)-C(2)-C(3) moiety. These findings indicate that glycerol-1,2,3-tris(methylsuccinate), recently proposed as a novel insulinotropic tool for the treatment of non-insulin-dependent diabetes mellitus, is efficiently metabolized in hepatocytes from diabetic rats, the high rate of gluconeogenesis coinciding with channelling of D-glyceraldehyde-3-phosphate between glyceraldehyde-3-phosphate dehydrogenase and phosphofructoaldolase.

Animals↗
PubMed1991

[Perineural application of glycerol and phenol-glycerol. Histomorphologic-morphometric study].

In a long-term study the effect of glycerol and phenol-glycerol on rats mandibular nerve was analysed. The substances were applicated perineurally. Nerves treated with glycerol did not show any severe pathological changes. Only the number of desintegrations of myelin seemed to be more pronounced. This, however, was a transitary effect. On the contrary, nerves treated with phenol-glycerol showed the familiar picture of degeneration and regeneration. According to our results it can be stated that the perineural application of glycerol has no toxic and destructive effect on the nerve. Therefore, the perineural glycerol blocking will not cause severe side-effects and the method can be recommended in the therapy of chronic facial pain.

Animals↗
PubMed1986

Distribution of metabolic fluxes towards glycerol phosphate and L-lactate from fructose 1,6-biphosphate in vitro: effect of glycerol phosphate dehydrogenase.

A metabolic system in vitro, which converts fructose 1,6-biphosphate into the two alternative products, lactate and glycerol phosphate, was designed to study the distribution of metabolic fluxes and, specifically, the control of glycerol phosphate production rate in rat muscle extract. Experiments were carried out at several protein concentrations by dilution of rat muscle extract, showing non-linear behaviours of flux versus protein concentration. These were hyperbolic for glycerol phosphate and logarithmic for L-lactate. The influence of the flux towards any alternate product on the rate giving the other was studied by stimulation of each. Results obtained show that in this system, flux towards glycerol phosphate is not affected by lactate production and the same occurs for the contrary case. Glycerol phosphate dehydrogenase seems to be the only enzyme in this system whose activity controls the flux towards glycerol phosphate.

Animals↗
PubMed1979

Biosynthesis in Escherichia coli of sn-glycerol 3-phosphate, a precursor of phospholipid. Palmitoyl-CoA inhibition of the biosynthetic sn-glycerol-3-phosphate dehydrogenase.

Homogeneous biosynthetic sn-glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) of Escherichia coli was potently inhibited by palmitoyl-CoA and other long chain acyl-CoA thioesters. The concentration dependence of this inhibition was not cooperative. Enzyme activity was inhibited 50% at 1 microM palmitoyl-CoA; thus, this inhibition occurred at concentrations below the critical micellar concentration of palmitoyl-CoA. Palmitoyl-CoA was a reversible, noncompetitive inhibitor with respect to both NADPH and dihydroxyacetone phosphate. Palmitoyl-CoA did not affect the quaternary structure of the enzyme. This inhibition could be prevented or reversed by the addition of phospholipid vesicles prepared from E. coli phospholipids. Palmitoyl-CoA did not alter the kinetics of inhibition by sn-glycerol 3-phosphate, which is a proven physiological regulator of this enzyme. Decanoyl-CoA, dodecanoyl-CoA, myristoyl-CoA, palmitoyl-(1,N6-etheno)CoA, stearoyl-CoA, and oleoyl-CoA inhibited sn-glycerol-3-phosphate dehydrogenase at concentrations below their critical micellar concentrations. Palmitate inhibited sn-glycerol-3-phosphate dehydrogenase activity 50% at 200 microM. Palmitoyl-carnitine, deoxycholate, taurocholate, and dodecyl sulfate were more potent inhibitors than Triton X-100, Tween-20, or Tween-80. Palmitoyl-acyl carrier protein at concentrations up to 50 microM had no effect on sn-glycerol-3-phosphate dehydrogenase activity. The possible physiological role of long chain fatty acyl-CoA thioesters in the regulation of sn-glycerol 3-phosphate and phospholipid biosynthesis in E. coli is discussed.

Acyl Coenzyme A↗
PubMed2004

Structures of enterococcal glycerol kinase in the absence and presence of glycerol: correlation of conformation to substrate binding and a mechanism of activation by phosphorylation.

The first structure of a glycerol kinase from a Gram-positive organism, Enterococcus casseliflavus, has been determined to 2.8 A resolution in the presence of glycerol and to 2.5 A resolution in the absence of substrate. The substrate-induced closure of 7 degrees is significantly smaller than that reported for hexokinase, a model for substrate-mediated domain closure that has been proposed for glycerol kinase. Despite the 78% level of sequence identity and conformational similarity in the catalytic cleft regions of the En. casseliflavus and Escherichia coli glycerol kinases, remarkable structural differences have now been identified. These differences correlate well with their divergent regulatory schemes of activation by phosphorylation in En. casseliflavus and allosteric inhibition in E. coli. On the basis of our structural results, we propose a mechanism by which the phosphorylation of a histidyl residue located 25 A from the active site results in a 10-15-fold increase in the activity of the enterococcal glycerol kinase.

Amino Acid Sequence↗
PubMed1981

Renal glycerol metabolism and the distribution of glycerol kinase in rabbit nephron.

Glycerol and dihydroxyacetone are metabolized by rabbit kidney-cortex tubules, isolated by collagenase treatment. Half-maximal concentrations of both substrates were determined with regard to uptake rates and product formations. Maximal uptake rates were 643 and 329 mumol/h per g of protein for dihydroxyacetone and glycerol respectively. Glucose and lactate were found as major metabolic products. Glycerol kinase, the enzyme catalysing the first step in renal glycerol and dihydroxyacetone metabolism, was measured radiochemically as described by Newsholme, Robinson & Taylor [(1967) Biochim, Biophys. Acta 132, 338-346] and adapted for studies of the localization of this enzyme along the different structures of rabbit nephron. The results show that glycerol kinase is located exclusively in the proximal segments, i.e. the proximal convoluted tubules and the pars recta, but is negligible in the other structures studied. The activities were close to the maximal dihydroxyacetone uptake rates measured in tubule suspensions.

Animals↗
PubMed2000

AluY insertion (IVS4-52ins316alu) in the glycerol kinase gene from an individual with benign glycerol kinase deficiency.

Glycerol kinase deficiency has three distinct forms: an isolated form which may be benign or symptomatic, and a complex form which is symptomatic and part of an Xp21 contiguous gene syndrome. Here we report the case of a male with benign isolated glycerol kinase deficiency who was incidentally identified after observation of pseudohypertriglyceridemia. DNA sequencing of this subject's glycerol kinase gene showed the insertion of an AluY sequence in intron 4 of the glycerol kinase gene. Although Alu insertions have been implicated in other diseases, and a closely related AluY element is found as an insert in the C1 inhibitor gene in patients with hereditary angioedema, this is the first case of glycerol kinase deficiency caused by an Alu insertion.

Adult↗
PubMed1995

Stereospecific labeling of the glycerol moiety: synthesis of 1,2-dioleoyl-sn-[3-3H]glycero-3-phospho(1-rac-glycerol).

1,2-Dioleoyl-sn-[3-3H]glycero-3-phospho(1-rac-glycerol) was synthesized from 1,2-dioleoyl-sn-glycerol using a new radiosynthetic procedure. 1,2-Dioleoyl-sn-glycerol was oxidized to the corresponding aldehyde using pyridinium dichromate and pyridine. The aldehyde was reduced to the radiolabeled alcohol using tritiated sodium borohydride and crown ether. This material was then converted to the phosphocholine derivative using 2-chloro-2-oxo-1,3,2-dioxaphospholane, followed by displacement with trimethylamine. In the last step, the 1,2-dioleoyl-sn-[3-3H]glycero-3-phosphocholine was converted to 1,2-dioleoyl-sn-[3-3H]glycero-3-phospho-(1-rac-glycerol) via a classic transphosphatidylation reaction using glycerol and cabbage phospholipase D. A theoretical explanation of unusual chemical behavior of the primary alcohol of diglycerides is also given, based on semi-empirical calculations.

Diglycerides↗
PubMed1980

Effects of indomethacin on the metabolism of glycerol by rat-kidney tubules: an alternative explanation for the enhancement of glycerol-induced acute renal failure by indomethacin.

1. The metabolism of glycerol by isolated rat-kidney tubules was investigated. 2. Indomethacin, at a concentration of 0.1 mmol/l, markedly inhibited the utilization of glycerol and its conversion into glucose and CO2. 3. The glycerol 3-phosphate production rose significantly when indomethacin was present, indicating a fall in the rate at which glycerol 3-phosphate was oxidized. 4. The results are discussed in relation to the observation that indomethacin increases the severity of glycerol-induced acute renal failure.

Acute Kidney Injury↗
PubMed2003

Targeted gene disruption of glycerol-3-phosphate dehydrogenase in Colletotrichum gloeosporioides reveals evidence that glycerol is a significant transferred nutrient from host plant to fungal pathogen.

Unidirectional transfer of nutrients from plant host to pathogen represents a most revealing aspect of the parasitic lifestyle of plant pathogens. Whereas much effort has been focused on sugars and amino acids, the identification of other significant metabolites is equally important for comprehensive characterization of metabolic interactions between plants and biotrophic fungal pathogens. Employing a strategy of targeted gene disruption, we generated a mutant strain (gpdhDelta) defective in glycerol-3-phosphate dehydrogenase in a hemibiotrophic plant pathogen, Colletotrichum gloeosporioides f.sp. malvae. The gpdhDelta strain had severe defects in carbon utilization as it could use neither glucose nor amino acids for sustained growth. Although the mutant mycelia were able to grow on potato dextrose agar medium, they displayed arrhythmicity in growth and failure to conidiate. The metabolic defect of gpdhDelta could be entirely ameliorated by glycerol in chemically defined minimal medium. Furthermore, glycerol was the one and only metabolite that could restore rhythmic growth and conidiation of gpdhDelta. Despite the profound defects in carbon source utilization, in planta the gpdhDelta strain exhibited normal pathogenicity, proceeded normally in its life cycle, and produced abundant conidia. Analysis of plant tissues at the peripheral zone of fungal infection sites revealed a time-dependent reduction in glycerol content. This study provides strong evidence for a role of glycerol as a significant transferred metabolite from plant to fungal pathogen.

Althaea↗
PubMed1980

In situ reactivation of glycerol-inactivated coenzyme B12-dependent enzymes, glycerol dehydratase and diol dehydratase.

The catalytic properties of coenzyme B12-dependent glycerol dehydratase and diol dehydratase were studied in situ with Klebsiella pneumoniae cells permeabilized by toluene treatment, since the in situ enzymes approximate the in vivo conditions of the enzymes more closely than enzymes in cell-free extracts or cell homogenates. Both dehydratases in situ underwent rapid "suicidal" inactivation by glycerol during catalysis, as they do in vitro. The inactivated dehydratases in situ, however, were rapidly and continually reactivated by adenosine 5'-triphosphate (ATP) and Mn2+ in the presence of free adenosylcobalamin, although in cell-free extracts or in cell homogenates they could not be reactivated at all under the same reaction conditions. ATP was partially replaced by cytidine 5'-triphosphate or guanosine 5'-triphosphate but not by the beta, gamma-methylene analog of ATP in the in situ reactivation. Mn2+ was fully replaced by Mg2+ but only partially by Co2+. Hydroxocoblamin could not replace adenosylcobalamin in reactivation mixtures. The ability to reactivate the glycerol-inactivated dehydratases in situ was only seen in cells grown anaerobically in glycerol-containing media. This suggests that some factor(s) required for in situ reactivation is subject to induction by glycerol. Of the two possible mechanisms of in situ reactivation, i.e., the regeneration of adenosylcobalamin by Co-adenosylation of the bound inactivated coenzyme moiety (B12-adenosylation mechanism) and the displacement of the bound inactivated coenzyme moiety by free adenosyl-cobalamin (B12-exchange mechanism), the former seems very unlikely from the experimental results.

Adenosine Triphosphate↗
PubMed1984

Measurement of glycerol turnover by infusion of nonisotopic glycerol in normal and injured subjects.

A new technique for measuring glycerol turnover in human subjects is presented using a staged infusion of unlabeled glycerol. A total of 105 measurements was made in normal subjects and postoperative or acutely ill patients. The relation between glycerol turnover rate (R tau) and concentration (C) (R tau = 31 + 2.07C) from 80 staged infusion measurements in 21 normal subjects did not differ significantly from observations of others made by isotope dilution. In 11 patients, glycerol turnover was also measured by dilution of isotopic glycerol. Mean values did not differ significantly between the two methods. The average difference, regardless of sign, for individual values was 17%. This agreement tends to validate the assumptions of both methods. Advantages of the staged infusion method are that it is quicker and easier to perform and does not entail a risk due to administration of radioactive materials. Evidence obtained in this study from a three-stage procedure indicates that satisfactory information may be obtained from a two-stage infusion at successive rates of 250 and 600 mumol/min for 70 min each, with a prime of 2 mmol given as a bolus at the start of each stage.

Adult↗
PubMedDate not supplied

Comparison of the effects of hypertonic glycerol and urea on brain edema, energy metabolism and blood flow following cerebral microembolism in the rat. Deleterious effect of glycerol treatment.

Cerebral microembolism was performed in rats by injecting radioactive calibrated 50 mu microspheres into the left internal carotid artery. The use of radioactive microspheres as embolic agents enabled the number of microspheres to be determined in each cerebral hemisphere. Edema was assessed 24 h after embolization by measuring brain water, sodium, and potassium content. Equiosmolal doses (40 mmol/kg) of glycerol or urea were injected i.p. at various times before sacrifice. Both treatments caused similar changes in water and electrolyte content, brain dehydration being maximal 30 min after urea and 2 h after glycerol injection. Cerebral energy metabolism and regional blood flow were evaluated at the times of maximal brain dehydration. Urea treatment resulted in an improvement of the cerebral circulation whereas glycerol treatment led to a deterioration of cerebral blood flow which cannot be explained by failure to reduce edema and the consequent microcirculatory impairment. Urea treatment had no marked effect on cerebral energy metabolism whereas glycerol injection resulted in an important increase in brain lactate level which may be relevant to the impairment of cerebral reperfusion. These results point out that administration of a metabolized solute like glycerol may exert deleterious effects on the ischemic brain.

Animals↗