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At least 811 records · Page 45Linked to original sources
PubMed1989

Effect of ether lipids on mouse granulocyte-macrophage progenitor cells.

In this study we determined the potential bone marrow toxicity of the ether lipid derivatives 1-0-octadecyl-2-0-methyl-rac-glycero-3-phosphocholine (OcMe-G-3-PC), 1-0-hexadecyl-propanediol-2-phosphocholine (He-Pr-2-PC), and hexadecylphosphocholine (He-PC). OcMe-G-3-PC inhibited the proliferation of mouse granulocyte-macrophage progenitor cells (GM-CFCs) at a dose of 1 micrograms/ml, whereas He-Pr-2-PC and He-PC started to inhibit the growth of hemopoietic precursors at 5 micrograms/ml. In contrast to this finding, NMRI mice given 10 mg/kg i.v. daily for 4 weeks and 20 or 30 mg/kg for 5 days showed no bone marrow toxicity. We conclude that the dose-dependent toxic effects observed in vitro are within the physiological tolerance in vivo.

Animals↗
PubMed1986

Dynamic nuclear polarisation of biological matter.

Polarised targets as used in high energy physics experiments may be of considerable interest in biological structure research using polarized neutrons. So far, this promising method has been facing difficulties in getting reasonable polarization of the target nuclei. We report on a polarized "frozen spin" target which has been prepared from an enzyme dissolved in a mixture of heavy water and deuterated propanediol doped with a completely deuterated paramagnetic radical. Clusters of 700 protons defined by the structure of lysozyme embedded in a fully deuterated matrix were polarized to 75% within an hour by 4 mm microwave irradiation in a magnetic field of 2.5 tesla at a temperature of 0.3 K. The polarisation behaviour of biological targets can be compared to the best frozen spin target materials in high energy physics research.

Biophysical Phenomena↗
PubMed1991

Acetonema longum gen. nov. sp. nov., an H2/CO2 acetogenic bacterium from the termite, Pterotermes occidentis.

A previously undescribed, H2-oxidizing CO2-reducing acetogenic bacterium was isolated from gut contents of the wood-feeding termite, Pterotermes occidentis. Cells of representative strain APO-1 were strictly anaerobic. Gram-negative, endospore-forming motile rods which measured 0.30-0.40 x 6-60 microm. Cells were catalase positive, oxidase negative, and had 51.5 mol percent G + C in their DNA. Optimum conditions for growth on H2 + CO2 were at 30-33 degrees C and pH (initial) 7.8, and under these conditions cells formed acetate according to the equation: 4 H2 + 2 CO2----CH3COOH + 2 H2O. Other energy sources supporting good growth of strain APO-1 included glucose, ribose, and various organic acids. Acetate and butyrate were major fermentation products from most organic compounds tested, however propionate, succinate, and 1,2-propanediol were also formed from some substrates. Based on comparative analysis of 16S rRNA nucleotide sequences, strain APO-1 was related, to but distinct from, members of the genus Sporomusa. Moreover, physiological and morphological differences between strain APO-1 and the six known species of Sporomusa were significant. Consequently, it is proposed herewith that a new genus, Acetonema, be established with strain APO-1 as the type strain of the new species, Acetonema longum. A. longum may contribute to the nutrition of P. occidentis by forming acetate, propionate and butyrate, compounds which are important carbon and energy sources for termites.

Acetates↗
PubMed1988

Identification and quantification of ethylene glycol and diethylene glycol in plasma using gas chromatography-mass spectrometry.

A method for the gas chromatographic-mass spectrometric identification and quantification of ethylene glycol and diethylene glycol in plasma is described. Such a method is necessary in clinical and forensic toxicology to diagnose probable intoxication and to control the efficacy of detoxification. For sample preparation, the glycols were isolated using acetone after the addition of 1,3-propylene glycol as internal standard. The glycols were then esterified by pivalic acid (pivalic acid anhydride, triethylamine and methanol, 70 degrees C, 15 min) to improve their gas chromatographic characteristics. The glycols were first identified by a comparison of the full mass spectra with reference spectra and then quantified. Therefore, the peak area ratio in the total ion chromatogram (ethylene glycol or diethylene glycol/1,3-propanediol) of the sample was compared with the calibration curve in which the peak area ratios of the standards (0.05, 0.1, 0.5, 1 and 2 g/l), prepared in the same way, were plotted versus their concentrations. The method was linear at least from 0.05 to 2 g/l, with a detection limit of less than 0.01 g/l. The analytical recoveries were 99.2-102.9% for the different concentrations. Precision studies show coefficients of variation of 3.0-6.3% for the different concentrations.

Ethylene Glycols↗
PubMed1987

The organization of the fuc regulon specifying L-fucose dissimilation in Escherichia coli K12 as determined by gene cloning.

In Escherichia coli the six known genes specifying the utilization of L-fucose as carbon and energy source cluster at 60.2 min and constitute a regulon. These genes include fucP (encoding L-fucose permease), fucI (encoding L-fucose isomerase), fucK (encoding L-fuculose kinase), fucA (encoding L-fuculose 1-phosphate aldolase), fucO (encoding L-1,2-propanediol oxidoreductase), and fucR (encoding the regulatory protein). In this study the fuc genes were cloned and their positions on the chromosome were established by restriction endonuclease and complementation analyses. Clockwise, the gene order is: fucO-fucA-fucP-fucI-fucK-fucR. The operons comprising the structural genes and the direction of transcription were determined by complementation analysis and Southern blot hybridization. The fucPIK and fucA operons are transcribed clockwise. The fucO operon is transcribed counterclockwise. The fucR gene product activates the three structural operons in trans.

Chromosome Mapping↗
PubMed1983

Uptake and dissimilation of glycerol by wild type and glycerol nonutilizing strains of Neurospora crassa.

Seven mutant strains defective for utilization of glycerol, glyceraldehyde or dihydroxyacetone were isolated. One strain was deficient for NAD-linked glycerol-3-phosphate dehydrogenase, two for glycerol kinase, and four had no detected enzymatic deficiency, although one of the latter strains was deficient in glycerol uptake. Glycerol uptake was increased by incubation in glycerol, glycerol-3-phosphate, erythritol, and propanediol, and was protein-mediated below 0.14 mM glycerol, but at higher concentrations free diffusion predominated. Glycerol uptake was decreased by cycloheximide and was more sensitive to sodium azide than to iodoacetate.

Glycerol↗
PubMed1995

Evidence for a glycerol pathway through aquaporin 1 (CHIP28) channels.

Permeabilities to glycerol and small non-electrolytes of three Aquaporin 1 CHIP (AQP1) water channels were measured in AQP1 cRNA-injected Xenopus laevis oocytes and in human AQP1 channels reconstituted in proteoliposomes. By an "osmotic" swelling assay, significant increases of ethylene glycol, glycerol and 1,3-propanediol apparent permeability coefficients (P'solutes) were found in oocytes expressing human, rat and frog AQP1. p-Chloromercuribenzene sulphonate (pCMBS) and CuSO4 inhibited, by 95% and 58% respectively, apparent glycerol permeability (P'gly) in oocytes expressing human AQP1. pCMBS inhibition was reversed by beta-mercaptoethanol and CuSO4 inhibition was partly reversed by the Cu(2+)-binding peptide Gly-Gly-His. Tritiated glycerol uptakes confirmed the augmented P'gly value of AQP1 cRNA-injected oocytes. In contrast, no increases of urea, meso-erythritol, D-or L-threitol, xylitol and mannitol uptakes were detected. Stopped-flow light scattering experiments performed with human AQP1 proteoliposomes also revealed a much greater increase of P'gly than did those with protein-free liposomes; the initial rate of proteoliposomes also swelling was inhibited by 96.2% with HgCl2 and by 72.5% with CuSO4. In AQP1 cRNA-injected oocytes and in proteoliposomes, the value of the glycerol reflection coefficient was 0.74-0.80, indicating that water and glycerol share the same pathway. All these results provide strong evidence that water and certain small solutes permeate the AQP1 channels expressed at the surface of X. laevis oocytes or reconstituted in proteoliposomes. The urea exclusion suggests that the selectivity of the AQP1 channels not only depends on the size of the solutes but probably also on their flexibility and their ability to form H-bonds.

Animals↗
PubMed1989

High haemodialysis clearance of ornidazole in the presence of a negligible renal clearance.

The pharmacokinetics of ornidazole was studied in 6 patients treated by haemodialysis and in 8 subjects with a creatinine clearance between 4 and 99 ml/min x 1.73 m2. Blood and urine collections were performed for 72 h after i.v. and oral administration of 1.0 g ornidazole. Total body clearance, half-life, volume of distribution and systemic availability were independent of renal function and did not differ from previously reported values in normal volunteers. The haemodialysis clearance of ornidazole was greater than 100% higher than the total body clearance. The renal clearance of ornidazole accounted for less than 7% of the total body clearance. The percentage of the dose of ornidazole recovered in urine as parent compound or as the biologically active metabolites [alpha-(chloromethyl)-2 hydroxymethyl-5 nitroimidazole-1 ethanol and 3-(2 methyl-5 nitroimidazole-1-yl)1,2 propanediol] decreased linearly with decreasing renal function. Although the sum of those three compounds recovered in urine accounted for less than 10% of the total dose of ornidazole administered, they yielded therapeutic concentrations (greater than 4 micrograms/ml) in urine over 24 h after dosing. Due to the peculiar pharmacokinetic behaviour of ornidazole, i.e. high haemodialysis clearance in the absence of significant renal clearance, no dosage adjustment is necessary while renal function declines, but an increased dose is mandatory while patients are on dialysis.

Administration, Oral↗
PubMed1979

Isolation of an enzyme from soil that degrades the organophosphorus insecticide, crotoxyphos.

An enzyme which catalyzed the hydrolysis of crotoxyphos ((E)-1-phenylethyl 3-[(dimethoxyphosphinyl)oxy]-2-butenoate) was isolated from nonsterile and radiation-sterilized Chehalis clay loam with 1.5M Tris (2-(hydroxymethyl)-2-nitro-1,3-propanediol) and partially purified with lead acetate treatment. Two soil-g equivalents of lead acetate purified enzyme in pH 8 buffer hydrolyzed 0.13 mumol of substrate to dimethyl phosphate and alpha-methylbenzyl 3-hydroxycrotonate in 16 hr at 37 degrees C. The enzyme exhibited maximal activity around pH 8.0 and was irreversibly inactivated below pH 5.0 or above pH 10.0. The Km value for crotoxyphos was calculated to be 4.63 x 10(-3) M. The enzyme was stable at 60 degrees C for 10 min, retained activity indefinitely at -10 degrees C, and was completely inactivated within a week at room temperature. When applied to autoclayed Chehalis clay loam, purified enzyme lost 75% of its activity after one week and the remainder within two weeks.

Biodegradation, Environmental↗
PubMed1986

The metabolism of acetone in the pregnant rat.

The administration of a single dose of acetone (100 mg/kg bw) to virgin and 21-day pregnant rats resulted in the appearance of relatively high concentrations of 1,2-propanediol, acetol and methylglyoxal in plasma and liver. In the fetuses no methylglyoxal was detectable. The acetone metabolism curves tend to indicate that the capacity for acetone disposal may be enhanced in the 48 hr-fasted pregnant rat, thus enabling the animal to re-use acetone metabolically, possibly for accelerated gluconeogenesis.

Acetone↗
PubMed1991

Developmental capacities of two-cell mouse embryos frozen by three methods.

The following three methods were evaluated in order to obtain a most efficient freezing protocol for the preservation of two-cell mouse embryos: (a) slow cooling and slow thawing in 1.5 M dimethyl sulfoxide, (b) slow cooling and fast thawing in 1.5 M propanediol (PROH), and (c) ultrarapid freezing and fast thawing in either 3.5 M DMSO or 3.0 M PROH. In the slow-cooling procedures (a and b) ice nucleation (seeding) was induced manually or automatically. With method a, only a slight difference, 51.8% for manual and 58.9% for automatic seeding, was observed in survival rates, while the development to blastocysts was significantly affected: 35.4% with manual and less than 10% with automatic induction (P less than 0.001). Method b gave high survival (86.2%) and developmental rates (69.0%) with manual seeding compared with automatic seeding (20.7 and 9.8%, respectively; P less than 0.001). Using protocol c, higher survival and developmental rates were obtained with DMSO (84.8 and 55.9%) than with PROH (39.8 and 19.4%, P less than 0.001). These results demonstrate that inducing nucleation manually is superior to the use of a highly sophisticated autoseeding system and that method b with manual seeding is most effective in preserving the developmental capacity of two-cell mouse embryos after freezing and thawing. There is evidence that this is also true of human embryo cryopreservation.

Animals↗
PubMed1982

Physiochemical studies of indocyanine green (ICG): absorbance/concentration relationship, pH tolerance and assay precision in various solvents.

Indocyanine green (ICG) obeyed the Beer-Lambert law within the concentration range 1.25 micrograms/ml-10.0 micrograms/ml in distilled water, methanol, dimethylformamide (DMF), 1.2-propanediol and aqueous buffers (pH 9.0), but only up to 7.5 micrograms/ml in human bile and 0.5% human albumin, and only to 5.0 micrograms/ml in human duodenal fluid. ICG was rapidly (less than 1 h) decomposed to a colorless derivative at pH less than 5 and greater than 11, but remained relatively stable for 48 h at pH 8-10. ICG is an indicator and a weak acid with a pKa of 3.27. In bile stabilized with 25% methanol, the precision of the method (CV) is 5% and the accuracy is 106-127%.

Bile↗
PubMed1991

In vitro biotransformation of 2-methylpropene (isobutene): epoxide formation in mice liver.

Until now, no data are available concerning the biotransformation and toxicity of 2-methylpropene (or isobutene), a gaseous alkene widely used in industry (rubber, fuel additives, plastic polymers, adhesives, antioxidants). In this work, the biotransformation of 2-methylpropene (MP) has been studied, using total liver homogenates of mice, supplemented with a NADPH-generating system. In analogy to other olefins, 2-methylpropene is metabolized to its epoxide 2-methyl-1,2-epoxypropane (MEP), as proved by the identification by gas chromatography coupled with mass spectrometry. The epoxidation is cytochrome P-450 dependent, as shown by experiments in the absence of the NADPH-generating system and in the presence of various concentrations of metyrapone and SKF 525-A, two known inhibitors of the mono-oxygenases. A simple gas chromatographic headspace method has been developed for the quantitative determination of the epoxide formed. The formation of MEP is never linear in function of time and it reaches a maximum after 20 min. Thereafter is decreases continuously to undetectable levels. This observation can be explained by the immediate action of epoxide hydrolase and glutathione S-transferase, converting the epoxide to 2-methyl-1,2-propanediol and to the glutathione conjugate respectively. The involvement of both enzymes has been demonstrated by the addition of 3,3,3-trichloropropene oxide and indomethacin. These inhibitors of, respectively, epoxide hydrolase and glutathione S-transferase increase the epoxide formation in a significant way. The actual concentration of MEP is therefore not only dependent on its formation by cytochrome P-450 dependent mono-oxygenases, but also on its conversion by epoxide hydrolase and glutathione S-transferase, both very active in liver tissue.

Alkenes↗
PubMed1990

Decomposition of pilocarpine eye drops assessed by a highly efficient high pressure liquid chromatographic method.

A rapid high-resolution high pressure liquid chromatographic method was developed for assaying pilocarpine. Pilocarpine in ophthalmic solutions decomposes fairly rapidly to give isopilocarpine, pilocarpic acid and isopilocarpic acid. The quality of an ophthalmic solution can be assessed by assaying these decomposition products. Existing high pressure liquid chromatographic methods suffer from long analysis times and poor resolution. The new method uses as the mobile phase 6 ml/l of triethylamine in water (pH 2.3, adjusted with 85% phosphoric acid) at a flow of 1.5 ml/min and as the stationary phase a C18-silica 125 x 4.6 mm column. 2-Amino-1-phenyl-1,3-propanediol is used as an internal standard. Complete separation was obtained within 8 min. Pilocarpine eye drops were stored under different conditions and then analysed for decomposition products. During heat treatment, decomposition to isopilocarpine predominated over decomposition to pilocarpic or isopilocarpic acid. However, when stored at room temperature or in a refrigerator, formation of pilocarpic acid clearly prevailed. Thus, from assessment of decomposition products, the cause of decomposition can be established.

Chromatography, High Pressure Liquid↗
PubMed1996

Pregnancy achieved with pronuclear-stage embryos that were cryopreserved and thawed twice: a case report.

PURPOSE: Our purpose was to determine if pronuclear-stage embryos (2PN) could be thawed, then frozen again with subsequent survival and cleavage after thawing. METHODS: A simplified cryopreservation protocol was used in which a slow cooling program is started at the seeding temperature of -6 degrees C in an alcohol-bath controlled-rate freezer. 1,2-Propanediol (1.5 M) was added to embryos before cooling. A fast thawing technique at room temperature was used. The cryoprotectant was removed in one step using a 1 M sucrose solution. RESULTS: Three months after refreezing, the three 2PN embryos were thawed and all three cleaved after 24 hr in culture. Following embryo transfer a pregnancy was achieved and a healthy full-term baby girl was born. CONCLUSIONS: This is the third case reported of successful pregnancies after transfer of human embryos that were frozen twice before transfer and the first case where the second freeze occurred at the pronuclear stage. This is also the first successful refreezing of human embryos using a simplified freezing and thawing technique with one-step addition and removal of cryoprotectant.

Adult↗
PubMed1991

Antitumor activity of Ilmofosine (BM 41.440) in the 3Lewis-lung carcinoma model.

Ilmofosine (1-hexadecylthio-2-methoxymethyl-1,3-propanediol-phosphocholine, BM 41.440) is a thioether phospholipid with cytostatic/cytotoxic properties. The antineoplastic activity of this compound was investigated in vivo in the 3Lewis-lung carcinoma system. 3Lewis lung tumor-bearing C57Bl/6 mice were treated with 0.625 to 40 mg Ilmofosine/kg per day p.o. either from days 1 to 9 or from days 11 to 28 after intrafoot-pad tumor cell inoculation. Ilmofosine caused a significant dose-related response on tumor growth and metastases, expressed in terms of tumor diameter, tumor weight, survival time and number of metastases-free animals as compared to sham-treated and positive (cyclophosphamide) controls. The results suggest that direct cytostatic/cytotoxic effects, rather than immune-modulatory mechanisms, preferentially contribute to the antitumor activity of Ilmofosine in vivo.

Animals↗
PubMed1987

An improved method for the colorimetric assay of lipase activity using an optically clear medium.

Lipase activity can be spectrophometrically measured in an optically clear medium using long chain fatty thioesters of 1-mercapto-2,3-propanediol or 2-mercaptoethanol as substrates. With hexamethylphosphoric triamide solutions of these thiosubstrates, the Michaëlis-Menten constants of lipase from Rhizopus arrhizus were determined. The effects of calcium chloride and of bovine serum albumin on the enzyme activity were established.

Colorimetry↗
PubMed1984

Monoacylglycerol lipase. Regulation and increased activity during hypoxia and ischemia.

The presence of monoacylglycerol lipase was established in extracts of acetone-dried powders from rat and bovine brains using thioester substrate analogs. At pH 7.4, the apparent Km and Vmax values for 1-S-decanoyl-1-mercapto-2,3-propanediol were 56 microM and 227 nmol/h/mg protein in bovine gray matter. The divalent metal ions Ca2+ and Mg2+ had no effect on enzymic activity, but Zn2+ at 500 microM produced a 50% inhibition of this enzyme. Free fatty acids also caused a marked inhibition of monoacylglycerol lipase activity. Norepinephrine and 5-hydroxytryptamine slightly stimulated the enzymic activity. Hypoxic-hypoxia and 30-s postdecapitation ischemia resulted in a considerable increase in monoacylglycerol lipase activity of rat brain. However, the increased activity of monoacylglycerol lipase returned to normal after 5 min of ischemia. The increased activity of monoacylglycerol lipase during hypoxic-hypoxia and short-time ischemia may be partially responsible for increased levels of free fatty acids during these processes.

Acetylcholine↗