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L J Felice

Publications and source records attributed to L J Felice.

32 records · Page 2Linked to original sources
PubMed1988

Optimization of high-performance liquid chromatography-radioimmunoassay protocols for the analyses of substance P and some of its metabolic fragments.

A reversed-phase high-performance liquid chromatographic procedure combined with radioimmunoassay (HPLC-RIA) was developed and optimized for the concomitant quantitation of substance P (SP) and some of its C- and N-terminal fragments in the extracts of the spinal cord of mice. A selective and efficient solid-phase extraction protocol was used for preparative purification of sample homogenates prior to analyses. The sensitivity of the HPLC assay was 18.75 ng for SP and some of its fragments of interest. Recoveries of peptides were calculated from spiked aqueous standards carried through the experimental protocol and ranged from 53 to 98%. The precision of the peptide recoveries from aqueous-based standards, expressed as coefficient of variation, ranged from 2 to 28%. The sensitivities for the RIA procedure using SP antiserum were 1.5, 3.4 and 4.6 fmol SP1-11, SP2-11 and SP5-11, respectively. The percentage cross-reactivity of SP1-11 antiserum with the C-terminal fragments was complete whereas the cross-reactivities of the N-terminal fragments were essentially zero. The molar limits of detectability of SP and some of its C-terminal fragments determined by HPLC alone were several orders of magnitude greater than those determined from the same spinal cord samples using RIA after HPLC fractionation.

Animals↗
PubMed1988

Toxicity of a vitamin D3 rodenticide to dogs.

As a follow-up to an investigation of 2 dogs that died as a result of apparent toxicosis attributable to a cholecalciferol-containing rodenticide, we tested the toxicity of this product in dogs. Two groups of 2 dogs each were fed amounts of rodenticide that provided 20 and 10 mg of cholecalciferol/kg of body weight (approx one fourth and one eighth of the published LD50, respectively). All dogs developed hypercalcemia and hyperphosphatemia and then died. Major lesions were gastrointestinal hemorrhage, myocardial necrosis, and mineralization of vascular walls. Our data indicate that cholecalciferol-containing rodenticides pose a much greater hazard to dogs than was previously believed.

Animals↗
PubMed1986

Siderophore production by Pasteurella multocida.

Pasteurella multocida grown under conditions of iron deprivation secreted into the culture medium a growth-enhancing factor which functioned as a siderophore. The siderophore was found to be neither a phenolate nor a hydroxamate by chemical tests and bioassays and was given the trivial name multocidin. Multocidin was partially purified and found to be a highly polar, nonaromatic, and dialyzable compound. This is the first report demonstrating the production of a siderophore by P. multocida.

Culture Media↗
PubMed1977

Modification of the Pisano method for vanilmandelic acid using high pressure liquid chromatography.

A method for the measurement of urinary vanilmandelic acid (VMA) is described based on a modification of the colorimetric procedure of Pisano. VMA is oxidized to vanillin with subsequent measurement of the vanillin by high pressure liquid chromatography with electrochemical detection (LCEC). The technique has been successfully applied to a number of human and animal urine samples. Urinary VMA values obtained by the LCEC method are in good agreement with those determined by the method of Pisano. The new method is both more selective and more sensitive than the colorimetric procedure.

Chromatography, High Pressure Liquid↗
PubMed1977

Recent developments in the clinical assessment of the metabolism of aromatics by high-performance, reversed-phase chromatography with amperometric detection.

High-performance liquid chromatography with electrochemical detection has developed into a tool with excellent capability to monitor picomole amounts of individual metabolites in both tissue and body-fluid specimens. Significant technical advances in the area of microparticle chemically-bonded stationary phases have led to dramatic improvements in both sensitivity and resolution. Reversed-phase systems can be modified to include charged exchange sites by addition of detergents to the mobile phase. Adjustment of the surface charge in this manner permits capacity factors for ionic sample components to be increased or decreased. This concept is quite compatible with electrochemical detection and has provided the foundation for several clinical assays now in routine use. Examples of additional applications are presented for the determination of catecholamines in tissue, 3-methoxy-4-hydroxyphenylglycol in urine, and dopamine-beta-hydroxylase activity in human serum.

Animals↗
PubMedDate not supplied

The determination of the anticoagulant rodenticide brodifacoum in blood serum by liquid chromatography with fluorescence detection.

A sensitive method utilizing reversed-phase liquid chromatography with fluorescence detection has been developed for the analysis of the anticoagulant rodenticide brodifacoum in blood serum. The serum proteins are precipitated with acetonitrile and the supernatant mixed with ethyl ether. The organic phase is separated, evaporated to dryness, and the residue subjected to chromatographic analysis. Extraction efficiencies of brodifacoum at concentrations of 20, 60, and 300 ng/mL were 82.9, 93.4, and 93.8%, respectively, with coefficients of variation (CVs) of 3.52, 4.07, and 3.68%, respectively. The intrarun precision (CV) without an internal standard at concentrations of 20, 60, and 300 ng/mL were 1.93, 4.89, and 1.51%, respectively, and 3.56, 5.94, and 3.66% with an internal standard. The interrun precision over the concentration range of 20-1000 ng/mL ranged from 1.88-6.22% without an internal standard and from 2.07-12.6% with an internal standard. Brodifacoum was measurable to at least the 1-ng/mL level.

4-Hydroxycoumarins↗
PubMedDate not supplied

Multicomponent determination of 4-hydroxycoumarin anticoagulant rodenticides in blood serum by liquid chromatography with fluorescence detection.

A sensitive liquid chromatographic method was developed for the analysis of 4-hydroxycoumarin anticoagulant rodenticides in blood serum. The method can simultaneously measure the serum levels of five anticoagulant rodenticides: brodifacoum, bromadiolone, coumatetralyl, difenacoum, and warfarin. Serum proteins are precipitated with acetonitrile and the supernatant is mixed with ethyl ether. The organic phase is separated, evaporated to dryness, and the residue subjected to chromatographic analysis. The anticoagulants are separated by reversed-phase gradient chromatography with fluorescence detection at an excitation wavelength of 318 nm and emission wavelength of 390 nm. Extraction efficiencies of 68.1 to 98.2% were obtained. The within-run precision (CV) ranged from 2.19 to 3.79% and the between-run precision (CV) from 3.72 to 9.57%. The anticoagulants can be quantitated at serum levels of 10 to 20 ng/mL.

4-Hydroxycoumarins↗
PubMedDate not supplied

Simultaneous determination of eight anticoagulant rodenticides in blood serum and liver.

A liquid chromatographic method was developed for the analysis of indandione and 4-hydroxycoumarin anticoagulant rodenticides in blood serum and liver. The method enabled the measurement of serum and liver concentrations of eight anticoagulant rodenticides: brodifacoum, bromadiolone, chlorophacinone, coumafuryl, coumatetralyl, diphacinone, difenacoum, and warfarin. Anticoagulants were extracted from serum and liver with acetonitrile. Extracts were applied to solid-phase extraction columns, which contained mixed packings. Column eluates were evaporated to dryness, reconstituted, and subjected to reversed-phase liquid chromatography. Hydroxycoumarins were detected by fluorescence at an excitation wavelength of 318 nm and an emission wavelength of 390 nm. Indandiones were detected by UV absorption at 285 nm. Extraction efficiencies of greater than 75% for serum and greater than 69% for liver were obtained. The within-run precision (CV) ranged from 2.4 to 8.6% for serum and 2.6 to 8.7% for liver. The between-run precision (CV) ranged from 1.5 to 12.2% for serum and from 2.1 to 11.8% for liver. Hydroxycoumarin rodenticides were detected at 1 ng/mL of serum and 1 ng/g of liver. Indandiones were detected at 10 ng/mL of serum and 10 ng/g of liver.

4-Hydroxycoumarins↗