Study of calcium dipicolinate release during bacterial spore germination by using a new, sensitive assay for dipicolinate.

The release of calcium and dipicolinic acid from spores of Bacillus megaterium KM during L-alanine-induced triggering of germination has been studied using a new, simple, and rapid assay for dipicolinic acid capable of detecting a concentration of 0.5 micron. The release of both calcium and dipicolinate started within seconds of exposure of the spores to L-alanine, thus preceding other measurable changes associated with germination. From the earliest times, the two substances were released in equimolar quantities, although later in germination calcium predominated.     

Membrane permeability of the human granulocyte to water,dimethyl sulfoxide,glycerol, propylene glycol and ethylene glycol

Granulocytes are currently transfused as soon as possible after collection because they rapidly deteriorate after being removed from the body. This short shelf life complicates the logistics of granulocyte collection, banking, and safety testing. Cryopreservation has the potential to significantly increase shelf life; however, cryopreservation of granulocytes has proven to be difficult. In this study, we investigate the membrane permeability properties of human granulocytes, with the ultimate goal of using membrane transport modeling to facilitate development of improved cryopreservation methods. We first measured the equilibrium volume of human granulocytes in a range of hypo- and hypertonic solutions and fit the resulting data using a Boyle-van’t Hoff model. This yielded an isotonic cell volume of 378 μm³ and an osmotically inactive volume of 165 μm³. To determine the permeability of the granulocyte membrane to water and cryoprotectant (CPA), cells were injected into well-mixed CPA solution while collecting volume measurements using a Coulter Counter. These experiments were performed at temperatures ranging from 4 to 37 °C for exposure to dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol. The best-fit water permeability was similar in the presence of all of the CPAs, with an average value at 21 °C of 0.18 μm atm⁻¹ min⁻¹. The activation energy for water transport ranged from 41 to 61 kJ/mol. The CPA permeability at 21 °C was 6.4, 1.0, 8.4, and 4.0 μm/min for dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol, respectively, and the activation energy for CPA transport ranged between 59 and 68 kJ/mol.     

Kinetics of propylene glycol elimination and metabolism in rat

The kinetics of 1,2-propanediol (PD) metabolism in vivo have been determined by employing the Michaelis-Menten rate equation; it was found that maximum metabolizing capacity was 8.33 mmole PD/kg/hr in the rat, which is equivalent to 1.06 kg/day for an average 70-kg human. The rate equation could be suitably used for optimizing the dosage schedule of a drug from the linear elimination pattern; in the present case this gave a Km value of 17.86 mmole/kg on the basis of the elimination rate of PD. The competitive inhibition of PD elimination by preadministration of pyrazole (Ki = 44 mumole/kg) demonstrated that the first step of the biotransformation of PD catalyzed by the NAD-dependent dehydrogenase might be the rate-limiting step for its in vivo metabolism. The low threshold level of the compound and significant rate of metabolism suggested that the CNS toxicity reported in clinical studies might be due to some of its metabolites such as lactaldehyde and other oxo compounds. Thus, PD could not be considered as an inert and innocuous substance.     

Electric-field orientation of sodium poly(l-glutamate) in methanol/water and ethylene glycol/water mixtures

Transient electric birefrinqence and circular dichroism measurements have been made on sodium poly(l-glutamate) in methanol/waer and ethylene glycol/water mixtures of various compositions. The specific Kerr constant increased upon the transition from coil to helix, but decreased with further increase in methanol or ethylene glycol content on the helix side.     

Vitrification of rabbit tissues with propylene glycol and trehalose

A previous study had suggested the use of a mixture of propanediol and trehalose for the preservation of tissues by vitrification. In this paper, we describe experiments in which stepwise procedures were developed for adding these cryoprotectants to high final concentrations in two rabbit tissues—carotid artery and cornea. The tissue concentration of the additives was measured at the end of each step so that the temperature of the next step could be chosen to reduce toxicity but avoid freezing. This process was arrested when a concentration had been reached that should permit vitrification if the tissues were cooled rapidly to −175 °C. They were stored at that temperature; warmed rapidly by conduction; the cryoprotectants removed by stepwise dilution; and appropriate active functions measured. These were contraction and relaxation for arteries and endothelial integrity and ability to control stromal swelling for the corneas. In control experiments the exposure and functional assays were carried out without vitrification. It was shown that the tissue concentration of propanediol was 33%w/w in artery and 30% in cornea. These permitted cooling to −175 °C without freezing but devitrification occurred during the warming of the arteries, though not of the corneas, despite the lower tissue concentration reached in the cornea. The function of the vitrified arteries was severely reduced but the endothelium of the corneas was substantially intact although we were unable to demonstrate any ability to control stromal swelling during normothermic perfusion. It appears that concentrations of cryoprotectants sufficient to prevent freezing in these tissues during cooling were well tolerated so long as appropriate stepwise means of addition and removal were used. Devitrification during warming remained a major problem with arteries, but not with corneas. We suggest that the composition of the aqueous phase in the tissue with respect to components other than the vitrifying agents may be crucial here and that the search for agents that will suppress devitrification is an important avenue for further study.     

Aerobic biodegradation of propylene glycol by soil bacteria

Propylene glycol (PG) is a main component of aircraft deicing fluids and its extensive use in Northern airports is a source of soil and groundwater contamination. Bacterial consortia able to grow on PG as sole carbon and energy source were selected from soil samples taken along the runways of Oslo Airport Gardermoen site (Norway). DGGE analysis of enrichment cultures showed that PG-degrading populations were mainly composed by Pseudomonas species, although Bacteroidetes were found, as well. Nineteen bacterial strains, able to grow on PG as sole carbon and energy source, were isolated and identified as different Pseudomonas species. Maximum specific growth rate of mixed cultures in the absence of nutrient limitation was 0.014 h^?1 at 4 °C. Substrate C:N:P molar ratios calculated on the basis of measured growth yields are in good agreement with the suggested values for biostimulation reported in literature. Therefore, the addition of nutrients is suggested as a suitable technique to sustain PG aerobic degradation at the maximum rate by autochthonous microorganisms of unsaturated soil profile.     

The measurement of water activity in allogeneic skin grafts preserved using high concentration glycerol or propylene glycol

In the presence of free water, many degradation reactions can occur within stored tissues including enzymatic digestion, oxidation (peroxidation) and hydrolytic reactions, as well as the detrimental effects of microbial growth, therefore most long-term banking techniques are designed to avoid free water. One method currently used for banking of skin grafts is the use of high concentration (85%) glycerol as a preservative. In this case, the glycerol was assumed to dehydrate the skin by osmosis and diffusion out of the cells and skin matrix respectively. We have recently shown that this assumption is incorrect and the converse occurs, i.e. glycerol enters the skin and sequesters the water. It was therefore essential to determine whether enough water had been immobilised to prevent degradation of the tissue. Using an instrument (Pawkit) designed to measure water activity (aw) it was shown that a stepwise reduction in aw was achieved when the skin was immersed in 50 and 85% glycerol or propylene glycol, respectively. At the end of the glycerolisation process, the final aw was shown to be circa 0.3. An aw of 0.3 is known to minimise lipid peroxidation and reduce other degradation reaction rates to very low levels. It was concluded that the current glycerolisation protocol results in effective sequestration of water avoiding degradation of the skin during storage. The method presented should be used as a quality control step to confirm adequacy of preservation for each batch of glycerolised skin.     

Protection from oxygen-induced seizures by clonazepam and propylene glycol

General anesthetics, ganglionic blocking agents, anticonvulsants, and antioxidants have been shown to afford protection from seizures caused by exposure to hyperbaric oxygen. In the present study cats were exposed to 5 ATA oxygen in pairs in a hyperbaric chamber until both the control and pretreated cat convulsed or for a maximum 120 min exposure. Small amounts of four common antiepileptic agents and propylene glycol in amounts far less than previously reported (0.1 to 0.2 ml/kg) were initially tested for potential anticonvulsant activity. Two agents, clonazepam and propylene glycol, offered significant protection in delaying the onset of seizures whereas carbamazepine, valproic acid, and trimethadione appeared to hasten the onset of seizure activity. The time to seizures was increased nearly five times by clonazepam and over three times by very small amounts of propylene glycol.     

Intravenous injection of propylene glycol causes pulmonary hypertension in sheep

Propylene glycol (30%) is the carrier base for pentobarbital sodium in preparations often used in research laboratories. It has caused pulmonary hypertension in calves, and we found it caused pulmonary hypertension in sheep as well. To investigate the mechanism of pulmonary hypertension with propylene glycol, we injected an average loading dose of 30% propylene glycol (0.5 ml/kg) into adult sheep, which was followed by a rise in thromboxane levels (P less than 0.05) in systemic arterial plasma and lung lymph and by a dramatic increase in pulmonary arterial pressure (17 +/- 1 to 35 +/- 4 mmHg, P less than 0.05) and a fall in cardiac output (2.7 +/- 0.5 to 1 +/- 0.2 l/min). Indomethacin pretreatment blocked the rise in thromboxane in lung lymph and arterial plasma and substantially, although not entirely, blocked the rise in pulmonary arterial pressure. Pulmonary intravascular macrophages (PIMS), which are present in sheep and calves, can release thromboxane in response to a stimulus. To test whether PIMS might be the source of the thromboxane and pulmonary hypertension, we injected propylene glycol into guinea pigs and dogs, which are reported to have no PIMS, as well as into newborn lambs, which are not believed to develop many PIMS until the 2nd wk of life. In dogs and guinea pigs there was no response to propylene glycol. In lambs there was a rise in pulmonary vascular resistance but significantly less than in adult sheep; indomethacin blocked this response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Stimulation of gluconeogenesis by propylene glycol in the fasting rat

Propylene glycol, a compound metabolically active as a carbohydrate, is often employed as part of the vehicle for pharmacological preparations. Since the latter may be administered to experimental animals which are used in studies concerned with carbohydrate metabolism, the effects of small doses of propylene glycol on gluconeogenesis were determined.The intramuscular administration of propylene glycol provoked a dose dependent increase in liver glycogen, rate of glycogen synthesis, and blood glucose concentration. Maximal effects occured within 90 minutes and the values returned to control levels within 3 hours. Quinolinic acid, a weak inhibitor of basal gluconeogenesis, was found to markedly inhibit the increased gluconeogenesis resulting from propylene glycol administration.These findings suggest that the elevated gluconeogenesis produced by propylene glycol does not follow the same metabolic pattern as the basal gluconeogenesis and that rats receiving this compound cannot be considered as metabolic equivalents to untreated animals with respect to carbohydrate metabolism.     

Simultaneous determination of ethylene glycol, propylene glycol, 1,3-butylene glycol and 2,3-butylene glycol in human serum and urine by wide-bore column gas chromatography

A method has been developed for the separation and measurement of ethylene glycol and three other glycols (propylene glycol, 1,3-butylene glycol and 2,3-butylene glycol) in biological samples by wide-bore column gas chromatography with a flame ionization detector. The method used 1,3-propylene glycol (1,3-propanediol) as an internal standard. The method was linear at least from 2 to 1000 μg/ml, with a detection limit of 1 μg/ml. Analytical recoveries were 89–98% for the different concentrations. Precision studies showed coefficients of variation of 1.5–7.7% for the different concentrations. The assay was applied to the analysis of biological samples from two patients who had ingested ethylene glycol and/or other glycols in a suicide attempt.     

Effects of feeding propylene glycol to mid-lactating dairy cows

Propylene glycol (PG) is a gluconeogenic precursor widely used to prevent and treat ketosis postpartum. The study has investigated the effects of PG administration to dairy cows at mid stage of lactation. According to a 3 × 3 latin square design, three Italian Brown lactating cows (125 ± 7 days in milk) fitted with rumen cannula were fed a corn silage based diet (CP 14.7%, NDF 41.1% DM) with 0, 200 or 400 g day⁻¹ PG added. Dry matter intake was increased by feeding PG with a significant quadratic component per dose (16.2, 17.2 and 16.5 kg day⁻¹ for 0, 200 and 400 g PG day⁻¹, respectively). Milk yield was not affected by PG, averaging 17.1 kg day⁻¹. Average daily gain increased from 64 to 206 and 302 g day⁻¹ when cows received 200 and 400 g day⁻¹ of PG (linear component per dose P < 0.05). Digestibility of the diet did not differ among treatments, whereas repeated rumen fluid samples, taken 0, 2, 4, 6 and 8 h after the meal, showed a consistently lower acetate to propionate ratio when feeding PG. Blood insulin was not affected by PG administration. Except for therapeutic treatments, PG administration to dairy cows at mid stage of lactation should be advised against. Despite the positive effect on intake, administration of the additive, increasing the molar percentage of rumen propionate, contributes to shift the energy partition from milk production to liveweight gain.