Dose Of Glycerol Research Articles

Co-digestion of sewage sludge and crude glycerol for on-demand biogas production

Pilot scale experiments, biomethane potential (BMP) evaluation, and BioWin simulations were conducted to evaluate the intermittent co-digestion of sewage sludge and crude glycerol for on-demand biogas production. BMP tests revealed that both pure and crude glycerols were readily biodegradable. BioWin simulations showed that intermittent glycerol injection at a high (3% v/v) dose might lead to an increase in chemical oxygen demand of the digestate. Results from the pilot scale experiments confirmed that intermittent injection of crude glycerol at both low (0.63% v/v) and high (3%v/v) doses could be used for on-demand biogas production to match the daily fluctuation in energy consumption at a typical wastewater treatment plant. However, in terms of additional biogas production per volume of added glycerol, the lower dose (0.63% v/v) was more effective. The additional methane yield (at the glycerol dose of 0.63% v/v) was 1.3 m3 per litre of crude glycerol. This value obtained from the pilot scale experiment was higher than that from the BMP test but lower compared to that predicted from the BioWin simulation.

Biochemical and Biological Study on The Effect of Flaxseed on Rats Suffer from Nephropathy.

The present study was conducted to investigate the effect supplemented diets with different doses of flaxseed on some biological, biochemical and histopathology changes in rats suffering from nephropathy. Thirty adult male albino rats Sprague Dawley strain weighing (170-175g) were divided into two main groups, the first main group fed on basal diet as a (negative control group). The second main group (24 rats) injection with 10 ml glycerol /kg dissolve in saline solution (glycerol / saline solution v/v) to induce renal failure, the dose of glycerol were injected under slight diethyl ether anesthesia. The second main group divided into four subgroups, the first subgroup fed standard diet (positive control group). The second subgroup fed standard diet containing 3% flaxseed. The third subgroup fed standard diet containing 5% flaxseed. The forth subgroup fed standard diet containing 7% flaxseed. At the end of the experiment (4 weeks), blood samples were taken; serum was separated and subjected to biochemical analysis (renal function). Glutathione, Malondialdehyde and histopathology were exanimated in kidney tissue in all groups. The results indicated that all treated groups get better in body weight gain%, Kidney functions (urea, uric acid and creatinine in serum) and GSH and MDA renal tissue ameliorated especially in renal failure rats fed on diet containing 5% and 7% flaxseed.

Effects of oral isosorbide and glycerol on intraocular pressure, serum osmolality, and blood glucose in normal dogs

To evaluate and compare the effects of oral isosorbide and glycerol on intraocular pressure (IOP), serum osmolality (SOSM), and blood glucose (BG) in normal dogs. Ten normal dogs were administered an oral dose of either isosorbide (1.5 g/kg), glycerol (1.5g/kg) or control (water, 2 mL/kg) in a double blind protocol. Prior to dosing, baseline IOP, SOSM, and BG were measured in all dogs. IOP was subsequently evaluated every 30 min for 6h post-dosing. BG and SOSM were reassessed at times 1, 2, 4, and 6h post-dosing. After 1-week washout periods, every dog was subject to each of the three treatments. The dogs were held NPO for 4h after dosing. The maximal decrease in IOP was 17% by 1h and 13.5% by 30min after glycerol and isosorbide administration, respectively. However, the overall changes in IOP were not significant when compared to the controls. SOSM increased above baseline after dosing with glycerol but decreased after isosorbide, which difference was significant at 1, 2, and 4 h post-administration. BG significantly increased after administration of glycerol relative to the control but was not significantly affected by isosorbide. Neither glycerol nor isosorbide significantly affected IOP when compared to the control. However, glycerol induced significant elevations in both BG relative to the control and SOSM relative to isosorbide.

Identifying Plasma Glycerol Concentration Associated with Urinary Glycerol Excretion in Trained Humans*†

Glycerol has been used as a means to legitimately hyperhydrate the body in an attempt to offset the deleterious effects of dehydration. It has the potential to mask blood doping practices and as a result has been added to the WADA prohibited substance list. The purpose of this study was to identify the plasma glycerol concentration coinciding with urinary glycerol excretion. Twelve healthy, trained male subjects completed five separate trials under resting conditions. For each trial, subjects consumed a different glycerol dose (0.025, 0.05, 0.10, 0.15, or 0.20 g glycerol/kg LBM) of a 5% glycerol solution in order to determine at what plasma glycerol concentration an increase in urine glycerol concentration becomes apparent. Based on regression analysis, plasma glycerol concentrations > 0.327 ± 0.190 mmol/L and a glycerol dose > 0.032 ± 0.010 g glycerol/kg LBM would be associated with urinary glycerol excretion. There were significant linear relationships between peak plasma glycerol concentration and time to reach peak plasma glycerol concentration to the ingested glycerol doses. Our findings illustrate the importance of considering the effect of urinary glycerol excretion on legitimate hyperhydration regimens as well as suggesting that it is possible to detect surreptitious use of glycerol as a masking agent through urinary analysis.

Anaerobic treatment of biodiesel by-products in a pilot scale reactor

AbstractIn this work, long-term operation of a pilot scale mixed anaerobic reactor processing crude glycerol and rapeseed meal is discussed. These materials are generated as by-products of biodiesel production. Mixed reactor was operated under mesophilic conditions for the period of 654 days. Total cumulative production of biogas reached 379 m3 (at atmospheric pressure and ambient temperature). Maximum volumetric loading achieved during the operation was 2.17 kg m−3 d−1 for the crude glycerol dose of 2 L. When dosing crude glycerol as a single substrate, average specific production of biogas of 0.76 m3 per L of the g-phase was achieved. The lack of nutrients in the g-phase had to be compensated by an addition of ammonium nitrogen in the form of urea into the reactor. Long term processing of crude glycerol demonstrated that accumulation of dissolved inorganic salts in the reactor can lead to inhibition of the methanogenic activity of microorganisms, causing breakdown of the system. Co-fermentation of crude glycerol with rapeseed meal provided stable biogas production and it was shown to be a feasible way of anaerobic degradation of these substrates. At the maximum volumetric load of 1.33 kg m−3 d−1 (500 mL of g-phase and 500 g of rapeseed meal), the average biogas production reached 0.58 m3 d−1.

Chronic metabolic responses of postpartal dairy cows to subcutaneous glucagon injections, oral glycerol, or both

We examined the long-term effects of daily subcutaneous injections of 15mg of glucagon during the first 14 d postpartum with or without coadministration of 400mL of pure glycerol orally on blood metabolites and hormones and liver composition of Holstein dairy cows during early lactation. Fourteen multiparous cows with body condition score of ≥3.5 points (1–5 point scale) were assigned randomly to one of 4 treatment groups—saline, glucagon, glycerol, or glucagon plus glycerol. Fatty liver syndrome was induced by feeding cows a dry-cow ration supplemented with 6kg of cracked corn daily during the last 6 wk of the dry period. Compared with saline treatment (n=3), coadministration of glucagon and glycerol (n=4) increased plasma glucose and insulin and decreased plasma nonesterified fatty acid concentrations in both treatment weeks, whereas glucagon alone (n=3) produced similar changes plus a decrease in plasma β-hydroxybutyrate in the second week only. No significant changes were observed for the glycerol alone treatment (n=4). We conclude that a single daily dose of glycerol for the first 14 d postpartum may potentiate the action of glucagon in the first treatment days to alleviate some symptoms of fatty liver syndrome, such as the increase in plasma nonesterified fatty acids and the decrease in plasma glucose and insulin, in Holstein dairy cows after parturition.

Identifying Serum Glycerol Concentration Associated With Urinary Glycerol Excretion

Glycerol has been used as a means to hyperhydate the body in attempts to offset deleterious effects of dehydration in addition to purported ergogenic effects on performance and thermoregulation. However, results of studies have been equivocal. Animal studies have reported serum glycerol saturations of 1.1 to 1.6 mmol/L associated with urinary glycerol excretion. When supplemental glycerol is lost through urination, the osmotic gradients associated with a given serum glycerol concentration that drive hyperhyration begin to diminish. Other than the animal studies of urinary glycerol excretion, little is known about similar responses in humans. PURPOSE: To identify the serum glycerol concentration coinciding with urinary glycerol excretion to determine if this may be a factor that may explain equivocal findings in glycerol hyperhydration studies. METHODS: Twelve healthy, trained male subjects completed five separate trials under resting conditions in a balanced predetermined sequence. During the trials, the subjects consumed a different glycerol dose (0.025, 0.05, 0.10, 0.15, or 0.20 g glycerol/kg LBM) of a 5% glycerol solution in order to determine at what serum glycerol concentration an increase in urine glycerol concentration becomes apparent. RESULTS: Based on regression analysis, serum glycerol concentrations 0.327 ± 0.190 mmol/L and a glycerol dose 0.032 ± 0.010 g glycerol/kg LBM would be associated with urinary glycerol excretion. There were significant (p < 0.001) linear relationships between peak serum glycerol response and time to reach peak serum glycerol response to ingested glycerol doses. CONCLUSIONS: This was the first study to identify the serum glycerol concentration associated with urinary glycerol excretion in humans. Since hyperhydration studies typically utilize a glycerol dose of 1.0 to 1.2 g/kg BW, urinary glycerol excretion becomes an issue in the maintenance of hyperhydration. Further research is warranted to examine maintenance doses of glycerol in hyperhydration applications in order to preserve serum glycerol concentrations required for sustained hyperhydation. This research was funded by grants from the UNM OGS and GPSA. Disclaimer: the views expressed are those of the authors and do not reflect the official policy or position of the USAF, the DoD, or the US Government.

In vivo confocal microscopy reveals new skin moisturizing system that hydrates all levels of stratum corneum more effectively than equivalent dose of glycerol

In vivo confocal microscopy reveals new skin moisturizing system that hydrates all levels of stratum corneum more effectively than equivalent dose of glycerol

In vitro gas production and ruminal fermentation of glycerol, propylene glycol and molasses

Ruminal fermentation pattern and in vitro gas production was determined for three energy sources for ruminants, glycerol, propylene glycol and molasses with ruminal fluid from sheep. Substrates incubated were alfalfa, corn silage, glycerol (320 and 640 μl), propylene glycol (320 and 640 μl) and molasses (320 μl). The greater volume of gas produced was observed at the highest dose of glycerol which also showed the slowest rate of gas production and the longest lag time ( P<0.05). Propylene glycol presented the minor volume of gas and was rapidly metabolized with short lag time. Molasses presented typical characteristics of a rapidly available substrate, with the fastest rate of gas production ( P<0.05). Glycerol fermentation resulted in a reduction of acetate, a slight increase in propionate and an increment in percentage of butyrate. Incubations with propylene glycol also reduced acetate and butyrate, but increased propionate ( P<0.05). Molasses fermentation reduced acetate and increased propionate and butyrate. Increasing dose of energy sources resulting in a greater volume of gas produced. In conclusion, glycerol fermentation reduced acetate and increased the molar proportion of butyrate and propionate was the main product of fermentation of propylene glycol.

The Role for Osmotic Agents in Children with Acute Encephalopathies: A Systematic Review.

Raised intracranial pressure (ICP) is a common complication in children with acute encephalopathies. It compromises cerebral perfusion leading to ischaemia and may cause death when the brainstem is compressed during trans-tentorial herniation. Osmotic agents are widely used to control raised ICP. Their use in children is mainly guided by studies in adults. We carried out this review to determine the best available evidence of the effectiveness of various osmotic agents and their effect on resolution of coma and outcome (neurological sequelae and mortality) in children with acute encephalopathies. We searched literature published between January 1966 and January 2008 on the use of osmotic agents in children aged between 0 and 16 years with acute encephalopathies. We searched Medline, Cochrane Library, EMBASE, Cumulative Index to Nursing and Allied Health Literature and other databases for both published and unpublished literature. We identified four randomized controlled trials (RCTs), three prospective observational studies, two retrospective studies and one case report. The use of hypertonic saline appeared to achieve greater reduction in ICP compared to mannitol, normal saline and ringer's lactate. This effect was sustained when it was given as a continuous infusion. Boluses of glycerol and mannitol achieved transient reduction in ICP. Use of repeated doses of oral glycerol was associated with lower mortality and neurological sequelae when compared to placebo in children with acute bacterial meningitis. Hypertonic saline was associated with lower mortality when compared to mannitol in children with non-traumatic encephalopathies. All agents resulted in reduction of ICP, albeit transient in a number of occasions. A sustained reduction in ICP is desirable and could be achieved by modifying the modes and rates of administration, factors that need further investigation. Hypertonic saline appears to boost cerebral perfusion pressure, an important determinant of outcome in acute encephalopathies. Hypertonic saline appears to achieve greater reduction in ICP than other osmotic agents. Oral glycerol seems to improve outcome among children with acute bacterial meningitis. However, the evidence is not sufficient to guide change of practice. More studies are needed to examine the safest and most efficacious concentrations of the various agents and the most effective routes and rates of administration of these agents.

The Role for Osmotic Agents in Children with Acute Encephalopathies: A Systematic Review

Background - Raised intracranial pressure (ICP) is a common complication in children with acute encephalopathies. It compromises cerebral perfusion leading to ischaemia and may cause death when the brainstem is compressed during trans-tentorial herniation. Osmotic agents are widely used to control raised ICP. Their use in children is mainly guided by studies in adults. Objective - We carried out this review to determine the best available evidence of the effectiveness of various osmotic agents and their effect on resolution of coma and outcome (neurological sequelae and mortality) in children with acute encephalopathies. Selection criteria - We searched literature published between January 1966 and January 2008 on the use of osmotic agents in children aged between 0 and 16 years with acute encephalopathies. Search strategy - We searched Medline, Cochrane Library, EMBASE, Cumulative Index to Nursing and Allied Health Literature and other databases for both published and unpublished literature. Results - We identified four randomized controlled trials (RCTs), three prospective observational studies, two retrospective studies and one case report. The use of hypertonic saline appeared to achieve greater reduction in ICP compared to mannitol, normal saline and ringer’s lactate. This effect was sustained when it was given as a continuous infusion. Boluses of glycerol and mannitol achieved transient reduction in ICP. Use of repeated doses of oral glycerol was associated with lower mortality and neurological sequelae when compared to placebo in children with acute bacterial meningitis. Hypertonic saline was associated with lower mortality when compared to mannitol in children with non-traumatic encephalopathies. Discussion - All agents resulted in reduction of ICP, albeit transient in a number of occasions. A sustained reduction in ICP is desirable and could be achieved by modifying the modes and rates of administration, factors that need further investigation. Hypertonic saline appears to boost cerebral perfusion pressure, an important determinant of outcome in acute encephalopathies. Conclusion - Hypertonic saline appears to achieve greater reduction in ICP than other osmotic agents. Oral glycerol seems to improve outcome among children with acute bacterial meningitis. However, the evidence is not sufficient to guide change of practice. More studies are needed to examine the safest and most efficacious concentrations of the various agents and the most effective routes and rates of administration of these agents.

Effects of glycerol on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers

The objective of this study was to evaluate the effects of glycerol supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers (450 ± 12 kg) were used in a replicated 4 × 4 Latin Square arrangement of treatments with experimental period of 21 days long. The treatments were: control (without glycerol), LG, MG and HG with 100, 200 and 300 g glycerol per head per day, respectively. Diet consisted of 60% corn stover and 40% concentrate (dry matter [DM] basis). Dry matter intake (averaged 9 kg/day) was restricted to a maximum of 90% of ad libitum intake. Ruminal pH (range of 6.58 to 6.23) was linearly ( P < 0.05) decreased, whereas total VFA concentration (range of 93.40 to 99.61 mM) was linearly ( P < 0.03) increased with increasing glycerol supplementation. Ratio of acetate to propionate decreased linearly ( P < 0.02) from 4.56 to 3.64 as glycerol supplementation increased due to the increased in propionate production. In situ ruminal NDF degradation of corn stover was improved but the CP degradability of concentrate mix was decreased with increasing doses of glycerol. Urinary excretion of purine derivatives was quadratically ( P < 0.02) changed with altering glycerol supplementation (65.0, 65.7, 71.1 and 67.2 mmol/d for control, LG, MG and HG, respectively). Similarly, digestibilities of OM, NDF and CP in the total tract were also linearly increased with increasing glycerol. The results indicate that glycerol supplementation potentially improves rumen fermentation with increased propionate production and feed digestibility in the total digestive tract of beef cattle. It suggests that feeding glycerol stimulates the ruminal microorganisms or digestive enzymes in a dose-dependent manner. Under the current experimental conditions, the optimum glycerol dose was about 200 g glycerol per head per day.

Differences in ability of jennies and mares to conceive with cooled and frozen semen containing glycerol or not

A suitable method for the cryopreservation of donkey semen would be very valuable for the ex situ management of genetic diversity in this species. This report uses a variety of observation and trials to evaluate the effect of cryoprotectants in per-cycle pregnancy rates (PC) in equids females (jennies (donkey) and mares (horse)). This was explored by (1) comparing the results of insemination of jennies and mares with cooled or frozen donkey semen, (2) examining the possible toxic effect of the cryoprotectant (CPA) glycerol in these two species and (3) studying alternative solutions. Donkey and horse semen was either used immediately, or cooled according to some steps of the pre-freezing procedure or frozen and thawed. The pre-freezing procedure included semen dilution, centrifugation, resuspension in milk or in INRA82 + 2% egg yolk + various % CPA (expressed as final concentrations in extended semen (v/v)) and then cooling to 4 °C. PC was similar in mares and jennies inseminated with donkey semen cooled to 4 °C in milk. However, the PC was significantly higher in mares than in jennies when donkey semen was frozen with 2.2% glycerol (36%, n = 50 cycles vs. 11%, n = 38 cycles; P < 0.01). Increasing the concentrations of glycerol (0, 2.2, 3.5, 4.8%) before cooling stallion semen resulted in a progressive decrease in mare PC (87, 53, 53, 13% ( n = 15 cycles for each concentration); P < 0.0001). The addition of 2.2% glycerol before cooling donkey semen decreased the PC measured in jennies to 0. The replacement of glycerol by 2% dimethylformamide increased the fertility obtained in jennies with cooled donkey semen (PC: 67%, n = 12 cycles) but did not increase the fertility obtained with frozen-thawed donkey semen (PC: 11%, n = 28 cycles with dimethylformamide vs. 0%, n = 16 cycles with glycerol). In conclusion, this study clearly shows that the ability of jennies to conceive after AI with donkey frozen semen is lower than that of mares. Glycerol affects the fertility of donkey and stallion spermatozoa as early as during the pre-freezing procedure. In consequence, the glycerol level must be low in frozen equine semen to provide good fertility. The toxic dose of glycerol for donkey spermatozoa seems to be almost half that for stallion spermatozoa. Whether this greater sensitivity of donkey spermatozoa to glycerol is responsible for the low success of semen cryopreservation in jennies is not so obvious because replacement of glycerol by dimethylformamide was not much more effective in terms of fertility.

Exploring the Potential Ergogenic Effects of Glycerol Hyperhydration

During athletic competition or recreational pursuits, a body's hydration level can become compromised, resulting in a decrement in performance. Glycerol (1,2,3-propanetriol) has been used to induce hyperhydration in an attempt to offset the deleterious effects of dehydration. When glycerol is consumed orally, it is rapidly absorbed primarily in the small intestine. It is reported to be evenly distributed among all fluid compartments, with the exception of the cerebral spinal fluid and aqueous humour, and promotes hyperhydration by inducing an osmotic gradient. Through an increase in the kidney's medullary concentration gradient, water absorption in the nephron is enhanced. When glycerol is consumed, the plasma glycerol concentration increases in proportion to the dose ingested, which easily exceeds the glycerol saturation point resulting in urinary glycerol excretion. Thus, without supplemental glycerol ingestion, there will be a decrease in the osmotic gradient resulting in a loss of hyperhydration. The ergogenic nature of glycerol has been investigated as to its effect on fluid retention, thermoregulation, cardiovascular responses and performance. While many studies provide evidence of hyperhydration, others do not. Only two studies reviewed showed a thermoregulatory advantage. Furthermore, the preponderance of evidence neither weighed for or against cardiovascular or performance advantages. What makes one study provide favourable results while another study does not is unclear. Possible explanations may include subject characteristics, environmental factors, research design, whether fluids with or without glycerol were given during exercise, the rate at which fluids are initially given to induce hyperhydration, the time between peak hyperhydration/peak plasma glycerol concentration and the trial (i.e. exercise), the glycerol dose (i.e. 1.0 g/kg body mass) and what it is based upon, the percentage glycerol solution (i.e. 5%, 20%), the variation of time between the end of the hydration protocol and the beginning of exercise, or perhaps the intensity of exercise (fixed, variable, percentage maximum oxygen uptake). What is clear is that glycerol has the capacity to enhance fluid retention. In so doing, glycerol hyperhydration may be a logistically preferred method due to concomitant decrease in urine output and free-water clearance, which may give a performance advantage by offsetting dehydration. Future research should focus on maintaining plasma glycerol concentrations at levels necessary to maintain osmotic forces required to support continued hyperhydration. Potential benefits of glycerol should be further explored to identify the circumstances or factors that may contribute to an ergogenic effect.

Effect of stabilizers on the shelf-life of Penicillium frequentans conidia and their efficacy as a biological agent against peach brown rot

Stabilizers were added to conidia of Penicillium frequentans at two different points of the production–formulation process to improve shelf-life of conidia stored at different temperatures. Effects were also tested on conidial germination and production. Germination of conidia without additives was 90.2%; sodium chloride, potassium chloride, triton TX100, dimethyl sulphoxide, peroxidase, 0.375% and 0.075% ascorbic acid, 7.5% and 3.75% sucrose, and 7.5% and 3.75% d-sorbitol reduced significantly ( P = 0.05) conidial germination, while no effect was observed with glucose, lactose, maltose, sodium glutamate, glycerol, peptone, sodium alginate, carboximethylcellulose, Tween 80, and gelatine. Production of P. frequentans conidia in solid-state fermentation without additives was 1.07 conidia × 10 8 g − 1 of dry substrate. The highest tested doses of glucose, lactose, maltose, sodium glutamate, and glycerol enhanced production of P. frequentans, while the lowest tested doses of d-sorbitol and ascorbic acid reduced it. No significant effect was observed with sucrose, peptone, sodium alginate, carboximethylcellulose, gelatine and Tween 80. Conidial germinability after one year of storage at different temperatures was studied in some formulations. It was lower than 18% after 365 days of storage at room temperature in control samples (without any additive), being enhanced when 7.5% glucose, 7.5% glycerol, or 1.5% sodium alginate was added to the substrate in bags before fermentation; or when 7.5% glucose, 7.5% sodium glutamate, or 1.5% sodium alginate was added to conidia before drying. Germinability of conidia produced without any additive and stored at 4 °C was significantly higher (38%) than at room temperature, being enhanced when 7.5% glycerol or 1.5% sodium alginate was added to the substrate in bags before fermentation; and when 7.5% glucose, or 1.5% sodium alginate was added to conidia before drying. No effect was observed with the presence or absence of light or high vacuum. Four formulations of P. frequentans conidia reduced disease incidence by more than 55%. The relationship of the disease control with the viability of P. frequentans was discussed.

Glycerol Suppresses Proliferation of Rat Hepatocytes and Human HepG2 Cells

Background. In fulminant hepatic failure (FHF), the ability of surviving hepatocytes to proliferate is diminished. Therefore, it is important that medical therapy cause no further impairment of liver regeneration. In FHF, intracranial hypertension secondary to brain edema is the most common cause of brain injury and death and glycerol is used in some countries to treat this complication. Glycerol has been long known to suppress the growth of various cell types. We therefore decided to examine the effect of glycerol on hepatocyte proliferation in vitro and in vivo in rats subjected to partial (2/3) hepatectomy. Additionally, we investigated the effect of glycerol on the proliferation of HepG2 cells.Materials and methods. Mitogen-induced primary rat hepatocytes were cultured in a hormonally defined Dulbecco's modified Eagle's medium containing increasing amounts of glycerol (0.5, 1.0, 2.0, 4.0%). HepG2 cells were cultured in minimal essential medium/10% FBS. After 2 days, HepG2 cells were exposed to glycerol (1.0–2.0–4.0%) and harvested after 48 h. Control dishes contained no glycerol. Cell proliferation was measured by the incorporation of [3H]thymidine and/or bromodeoxyuridine (BrdU). In vivo, Sprague–Dawley rats were subjected to standard partial 2/3 hepatectomy and assigned to intraportal administration of either 400 μl of glycerol or saline. Rats were killed after 1, 2, 3, 5, and 7 days. Liver weight/body weight ratio and BrdU uptake were measured.Results. In all cultures tested, glycerol suppressed the growth of cells in a dose-dependent manner. In vivo, a single intraportal dose of glycerol slowed the liver regenerative response.Conclusions. This study demonstrated that glycerol has a potent growth-inhibitory effect on hepatocyte proliferation in vivo and in vitro. Remarkably, glycerol inhibited the proliferation of liver cancer cells as well. The results of this study have important clinical implications.

Acute cholestatic liver disease protects against glycerol-induced acute renal failure in the rat

It is widely held that liver disease predisposes toward acute tubular necrosis. The present study examines the effect of acute cholestatic liver disease on the susceptibility to glycerol-induced acute tubular necrosis in the rat. Acute cholestatic liver disease was induced by ligation of the common bile duct, while the intramuscular injection of hypertonic glycerol was used to induce acute tubular necrosis. Renal injury was assessed by plasma creatinine concentration and renal histology. An in vitro model of heme protein-induced renal injury (hemoglobin in conjunction with glutathione depletion) was employed to assess the cytoprotective effects of bilirubin. Ligation of the common bile duct markedly reduced acute renal injury that occurs in the glycerol model (7.5 mL/kg body weight), as evidenced by a lower plasma creatinine concentration and less severe renal histologic injury. At a higher dose of glycerol (10 mL/kg body weight), ligation of the common bile duct again reduced renal injury and cumulative mortality that occurs five days after the induction of this model of acute renal failure. These protective effects of ligation of the common bile duct could not be ascribed to less severe muscle injury or red cell damage. Ligation of the common bile duct induced heme oxygenase-1 in the kidney and markedly so in the liver. Inhibition of heme oxygenase significantly attenuated, but did not prevent, the protective effects conferred by ligation of the common bile duct. Bilirubin, in low micromolar concentrations, was cytoprotective against heme protein-induced cell injury in vitro. Ligation of the common bile duct confers resistance to glycerol-induced acute tubular necrosis in the rat, actions that arise, in part, from the induction of heme oxygenase-1 in the kidney and liver. Bilirubin, in micromolar concentrations, protects against heme protein-induced renal injury. Our studies uncover a novel form of acquired resistance to renal injury, occurring, unexpectedly, in the setting of acute cholestatic liver disease. We speculate that such potentially cytoprotective alterations may safeguard the kidney against irreversible functional and structural injury in the hepatorenal syndrome.

Dose-dependent toxicity of a commercially available demineralized bone matrix material.

A relative risk assessment was performed to determine the safety of three commercially available Grafton demineralized bone matrix quantities used in athymic rats. To evaluate the possible dose-dependent adverse effects of a commercially available demineralized bone matrix containing glycerol. Commercially available Grafton demineralized bone matrix contains glycerol. The toxic effects of glycerol leading to acute renal failure have been documented. The toxicity of this glycerol-containing substance in higher doses has not been reported. Three doses of Grafton putty were implanted in the upper hind limb muscles of athymic nude rats. The rats were observed for adverse effects and early death. Histologic studies were performed. All eight of the rats implanted with the highest dose of Grafton putty (0.008 mL/g) died, five of them within 12 hours of implantation and three in 48 to 72 hours. One rat with the intermediate dose (0.004 mL/g) died within 12 hours of implantation. By 72 hours after implantation, three of the six rats (50%) with the intermediate dose had died. All six of the rats receiving the lowest dose (0.002cc/g) survived. The median lethal dose of Grafton putty in athymic rats was estimated to be 0.00469 mL/g body weight. Histologic analysis of the animals that received the high dose showed acute tubular necrosis, probably secondary to rhabdomyolysis. In athymic rats, large amounts of Grafton putty lead to death in a dose-dependent manner. Because the median lethal doses of Grafton putty (0.00469 mL/g) and glycerol (0.00442 mL/g) are comparable, a potential source of toxicity is the glycerol contained in the material. The results of this study suggest that high doses have the potential to cause acute renal failure. The authors suggest that clinical usage of Grafton putty in humans should be limited to no more than 2 mL/kg body weight of this material.

Effects of glycerol in tris extender on frozen semen quality of crossbred Etawah bucks

Bucks semen is easily damaged during freezing process, due to the formation of ice crystals. Consequently, semen quality decreases particularly the post-thaw sperm motility, viability, intack plasma membrane and intack acrosomal cap. The objectives of this research are to determine the optimum dose of glycerol in Tris extender in maintaining frozen semen quality of crossbred Etawah bucks. Four head of PE buck of 2 - 4 years old were used in this experiment. Doses of glycerol used were 5%, 6% and 7%. Semen was collected once a week using artificial vagina. Results of this experiment indicated that the mean percentage of pre-freezing motility, live sperm, sperm with intact plasma membrane and intact acrosomal cap in 5%, 6% and 7% glycerol were not significantly different (P>0.05). After freezing, the mean percentage of motility, live sperm, sperm with intact plasma membrane and intact acrosomal cap in 6% glycerol (52.60%, 65.03%, 45.63% and 47.54% respectively) were significantly higher (P<0.05) than in 5% (44.31%, 52.00%, 37.60% and 37.00% respectively) and in 7% glycerol (45.28%, 52.10%, 37.97% and 37.14% respectively). However, there were not significant differences in 5% and 7% glycerol for any parameter measured. It was concluded that supplementation of glycerol 6% in Tris extender effective to protect of sperm from various shock during the process of semen cryopreservation, so that it could maintain of frozen semen quality (sperm motility, viability, intack plasma membrane and intack acrosomal cap) that suitable used in AI program of crossbred Etawah bucks. Key words : Glycerol, PE bucks, semen quality

Hyperhydrating with Glycerol: Implications For Athletic Performance

Small decreases in hydration status can result in a dramatic decrement in athletic performance and greatly increase the risk of thermal injury. Because of its osmotic properties, which enable greater fluid retention than the ingestion of water alone, glycerol has been proposed as a hyperhydrating agent. In fact, glycerol is now commercially available and marketed as a sport supplement to be ingested with water or sport drinks; thus, dietitians need to be cognizant of this new addition to the sports nutrition table. The results of glycerol-induced hyperhydration research have been equivocal, most likely because of methodologic differences between studies, such as variations in the intensity of exercise, environmental conditions, and concentration or dose of glycerol administered. Although the suggested dosage of glycerol depends on body size and varies between manufacturers, 1 g/kg body weight with an additional 1.5 L fluid taken 60 to 120 minutes before competition is standard. Some test subjects reported feeling bloated or nauseated after ingesting glycerol. This review examines glycerol-induced hyperhydration research and the safety of ingesting glycerol, discusses commercial availability of glycerol, and makes recommendations for glycerol-induced hyperhydration research. J Am Diet Assoc. 1999;99:207–212.