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Biomedical subjects

E Benfenati

Publications and source records attributed to E Benfenati.

At least 37 records · Page 2Linked to original sources
PubMed1993

Urinary excretion of platelet activating factor in patients with immune-mediated glomerulonephritis.

We have investigated whether human immune-mediated glomerulonephritis is associated with changes in platelet activating factor (PAF) biosynthesis. Urinary PAF, taken as a marker of its renal synthesis, was significantly higher in patients with membranous nephropathy (N = 9) than in healthy controls (N = 8). This was not due to a lower degradation of PAF since urinary acetylhydrolase activity was comparable in patients and controls. A significant positive correlation between urinary excretion of PAF and proteinuria was observed. PAF generation was comparable in polymorphonuclear cells isolated from patients with membranous nephropathy and controls. PAF levels in blood from patients with membranous nephropathy were significantly lower than in controls, suggesting that the excessive generation of PAF is confined to the kidney. The results document that signs of renal disease activity in human membranous nephropathy are associated with an excessive renal synthesis of PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1992

Specific gas chromatography-mass spectrometry analytical method for the determination of cyhexatin in animal feed.

The acaricide tricyclohexyltin hydroxide (cyhexatin) was determined in animal feed samples, using gas chromatographic--mass spectrometry in the electron impact mode. Sample extraction and derivatization (converting the analyte to an alkylated derivative) were performed using a tricyclopentyl analogue of this acaricide as internal standard to obtain a better analytical precision.

Animal Feed↗
PubMed1992

Analysis by fast atom bombardment mass spectrometry of phospholipids from tubuli, glomeruli, and urine of normal rats and rats with acute renal failure.

Fast atom bombardment mass spectrometry was used to characterize phospholipids from tubuli and glomeruli of normal rats and rats with acute renal failure. It was possible to assess the molecular species of the principal phospholipidic classes. In all of them, the most abundant species contained a residue of arachidonic acid. The phospholipids of urine were also analyzed, showing the presence of the major molecular species of several phospholipid classes. Excretion of phospholipids was greater in urine from rats with acute renal failure.

Acute Kidney Injury↗
PubMed1991

Simultaneous determination of isbufylline and its major metabolites in rabbit blood and urine by reversed-phase high-performance liquid chromatography.

A sensitive high-performance liquid chromatographic assay for isbufylline and its major metabolites in rabbit blood and urine is described. After extraction, samples were eluted by a linear reversed-phase gradient. Specimens obtained after intravenous administration of isbufylline to rabbits were analysed to identify and subsequently quantify the potential metabolites. Using the ultraviolet absorption trace on the recorder as a reference, elution fractions were collected and analysed by mass spectrometry with the direct inlet system and gas chromatography-mass spectrometry after derivatization. Seven metabolites were identified and another five quantified. The method is specific, accurate, reproducible and recommended for pharmacokinetic studies.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Dictyostelium cells produce platelet-activating factor in response to cAMP.

Evidence is provided that Dictyostelium discoideum cells produce 1-O-alkyl-2-delta-acetyl-O-sn-glycero-3-phosphocholine (platelet-activating factor, PAF). D. discoideum PAF has been characterized as being identical with mammalian platelet-activating factor, based on its stimulation of rabbit platelet aggregation, its physicochemical properties and mass spectrum. The basal activity of PAF increases after starvation and during aggregation and declines at the slug stage. PAF is not detected in the extracellular space. Cell treatment with cAMP pulses stimulates a transient accumulation of PAF, probably via activation of a cAMP-dependent acetyltransferase, suggesting a possible involvement of PAF in cAMP-regulated processes in Dictyostelium.

Cyclic AMP↗
PubMed1991

Increased urinary excretion of platelet activating factor in mice with lupus nephritis.

Platelet activating factor (PAF) is present in urine from humans and experimental animals in normal conditions. Very little is known about changes in PAF urinary excretion under pathologic conditions and no data are available about the origin of PAF in the urine. In the present study we explored the possibility that immunologic renal disease is associated with an increase in PAF urinary excretion using gas chromatography-mass spectrometry technique. To clarify the renal or extrarenal origin of urinary PAF we evaluated whether exogenously administered PAF (1-[1', 2'-3H]alkyl) is filtered through the glomerulus and excreted in the urine. The results show that: 1) urine from mice with lupus nephritis in the early phase of the disease contained amounts of PAF comparable to those excreted in normal mouse urine, 2) PAF levels increased when animals started to develop high grade proteinuria, 3) after intravenous injection of [3H] PAF in nephritic mice, a negligible amount of [3H] ether lipid, corresponding to [3H]1-alkyl -2-acyl-3-phosphocholine (alkyl-2-acyl-GPC), was recovered from the 24 h urine extract.

Animals↗
PubMed1991

Migration of vinyl chloride into PVC-bottled drinking-water assessed by gas chromatography-mass spectrometry.

The migration of vinyl chloride (VC) into drinking-water bottled in polyvinyl chloride (PVC) was studied in relation to storage time, using a gas chromatographic-mass spectrometric method. Trideuterated vinyl chloride was used as internal standard. VC concentrations in the water rose progressively in direct (linear) relation to the time after bottling (about 1 ng/litre/day). The time of storage of PVC-packaged foodstuffs may affect the daily oral intake of this monomer, which in some cases may exceed 100 ng/person/day.

Drinking↗
PubMed1989

Molecular species analysis of phospholipids by negative ion fast atom bombardment mass spectrometry: application of surface precipitation technique.

Eight phospholipidic classes from bovine brain cortex and soybean were prepared and purified by preparative high-performance and liquid chromatography, and their molecular species were identified by negative ion fast atom bombardment mass spectrometry using the 'surface precipitation' method. Its main advantages are: (i) clear-cut and abundant diagnostic ions for structural elucidation of the species; (ii) fragments characteristic of the main fatty acids, the polar head-group and the molecule frame in phospholipids; (iii) less background caused by the liquid matrix.

Animals↗
PubMed1989

A gas chromatographic mass spectrometric assay for the determination of aphidicolin in plasma of cancer patients.

A gas chromatographic-mass spectrometric (GC-MS) method is described for the determination of the novel anticancer agent aphidicolin in plasma. The extraction was carried out in a solvent mixture of hexane:isopropanol (10:1) and the external standard aphidicolane was added after evaporation of the organic phase. The residue was then redissolved in a derivatizing mixture containing bis(trimethylsilyl)trifluoracetamide as sililating agent, pyridine, and trimethylchlorosilane, and allowed to react at 80 degrees C for 2 h. After GC separation of the derivatized samples, selected ion recording analysis was done, monitoring the ions at mass 523.3 and 448.3 for aphidicolin and aphidicolane, respectively. The mean recovery +/- SD of aphidicolin from plasma was 73.5 +/- 11.6% in the range from 5 to 800 ng. This method was applied to determine aphidicolin plasma levels in three cancer patients in Phase I clinical trials of aphidicolin-17-glycinate administered as a 1-h iv infusion. Two patients received dose of 290 mg/m2 and the third received 435 mg/m2. Aphidicolin plasma levels at the end of infusion were very low, and the drug rapidly disappeared from plasma with a terminal (beta) half-life of 2 h.

Adult↗
PubMed1989

Metabolism and pharmacokinetics of p-(3,3-dimethyl-1-triazeno) benzoic acid in M5076 sarcoma-bearing mice.

The pharmacokinetics of the anticancer agent p-(3,3-dimethyl-1-triazeno) benzoic acid (pCOOH-DMT), a drug now in phase I clinical trial in Europe, was investigated in C57Bl female mice with M5076 reticulum-cell sarcoma that were treated i.v. with 200 mg/kg pCOOH-DMT. The drug disappeared from plasma with a terminal half-life of about 2.5 h. Plasma clearance was approximately 6 ml/min per kg. Distribution studies showed some differences in drug levels in different tissues. The highest levels were found in the tumor, liver, kidney and lung; lower levels were found in the spleen and gut, and the lowest, in the brain. The N-desmethyl derivative of pCOOH-DMT was not detectable in plasma or tissues of mice treated with the drug. Therefore, the previous evidence of low N-demethylation of pCOOH-DMT was confirmed. pCOOH-DMT glucuronide was identified by mass spectrometry and quantified by high-performance liquid chromatography (HPLC) in plasma, tissues and urine samples. pCOOH-DMT glucuronide appears to be the major urinary metabolite of pCOOH-DMT in mice. Another metabolite identified by mass spectrometry and quantified by HPLC in some tissues and urine was pCOOH-DMT glycinate.

Animals↗
PubMed1989

Development of a mass spectrometric method to quantitate platelet activating factor in mouse urine.

Platelet activating factor (PAF) is a lipid mediator of inflammation released by a variety of stimulated inflammatory cells. It may be involved in immune glomerulonephritis. Thus, its measurement in urine could give information on the mechanism of this disease. We present here a method to measure PAF in mouse urine, using gas-liquid chromatography-mass spectrometry (GLC-MS) in the selected ion recording (SIR) mode. Before instrumental analysis, the extracted and purified samples were hydrolyzed and derivatized with pentafluorobenzoyl chloride. Different experimental conditions are presented and discussed to corroborate the analytical findings. PAF levels in mouse urine were 2.08 +/- 0.46 ng/24 h. This procedure might represent a new experimental tool to establish the possible role of PAF as mediator of tissue damage in renal disease.

Animals↗
PubMed1989

A fast atom bombardment-mass spectrometric method to quantitate lysophosphatidylserine in rat brain.

A method to quantitate lysophosphatidylserine by fast atom bombardment-mass spectrometry using 1-hexa-decanoyl-sn-glycero-3-phospho-L-serine as internal standard is described. The standard curve is linear with a correlation coefficient r2 = 0.999 from 10 to 1000 ng. This curve has been used to quantitate LPS in rat brain using phosphorus assay as a test control. We found 475 +/- 70 ng of LPS in 1 mg of tissue (n = 3). This method presents advantages due to its sensitivity and its capability to give molecular information of the unmodified compound.

Animals↗
PubMed1988

Reaction of 2-amino-2-deoxy-D-glucose and lysine: isolation and characterization of 2,5-bis(tetrahydroxybutyl)pyrazine.

The reaction of 2-amino-2-deoxy-D-glucose with lysine in water under simulated physiological conditions gave several browning products, with characteristic optical (lambda max 340 nm) and fluorescent properties (emission at 430 nm for excitation at 362 nm). The major product was isolated and characterized by mass spectrometry and n.m.r. spectroscopy as 2,5-bis(tetrahydroxybutyl)pyrazine derived by the condensation of two molecules of 2-amino-2-deoxy-D-glucose.

Chemical Phenomena↗
PubMed1988

Identification of metabolites of tiropramide in human urine.

The metabolites of tiropramide were extracted from the urine of healthy volunteers given tiropramide hydrochloride orally. Eight metabolites of tiropramide were found by gas chromatography/mass spectrometry. Three were identified on the basis of their mass spectra, retention times and comparison with synthetic standards. For the others a probable structure is proposed on the basis of their mass spectra.

Adult↗
PubMed1988

Mass spectrometric identification of urinary and plasma metabolites of 9-hydroxy-19,20-bis-nor-prostanoic acid (rosaprostol).

9-Hydroxy-19,20-bis-nor-prostanoic acid (Rosaprostol) is an antiulcer compound with antisecretory and cytoprotective action. We studied the metabolites of Rosaprostol found in human plasma and in human and rat urine. Sixteen different metabolites were tentatively identified on the basis of their mass spectra. Two presumed metabolites were synthesized. To clarify the identities of some of them, deuterated Rosaprostol was administered to rats and mass spectra of the deuterated and protonated metabolites were examined. Rosaprostol is metabolized following three metabolic pathways leading, combined, to oxidized compounds with a lower number of carbons than the parent drug.

Animals↗