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C Lucarelli

Publications and source records attributed to C Lucarelli.

At least 37 records · Page 2Linked to original sources
PubMed1991

High-performance liquid chromatographic determination of L-3-(3,4-dihydroxyphenyl)-2-methylalanine (alpha-methyldopa) in human urine and plasma.

A procedure is described for the determination of alpha-methyldopa (MD) [L-3-(3,4-dihydroxyphenyl)-2-methylalanine], its metabolite and catecholamines in the urine and plasma of patients undergoing MD therapy, by high-performance liquid chromatography with dual working electrode coulometric detection. An efficient sample preparation procedure is presented for the isolation of endogenous MD, its metabolite and catecholamines from plasma or urine. After deproteinization of a plasma sample with methanol containing 2% of 0.5 M perchloric acid and dilution of a urine sample (1:200), MD, dihydroxyphenylacetic acid (DOPAC), 3-O-methylmethyldopa (3-OMMD) and homovanillic acid (HVA) were separated with a Supelcosil LC-18 column. Catecholamines were extracted from the supernatant of deproteinized plasma or from urine by ion exchange on a Sephadex CM-25 column and subsequent adsorption on alumina. The use of the same mobile phase for the concurrent assay of MD, its metabolite and catecholamines increased considerably the efficiency of sample separation. Recoveries were close to 100% for MD, DOPAC, 3-OMMD and HVA and 70% for catecholamines. The effects of various experimental parameters related to mobile phase composition on chromatographic performance are reported. The purity of the eluted compounds was tested by recording both the first detector response (oxidation current) and the second detector response (reduction current). The ratio of the detector responses yielded a chemical reversibility ratio for the detected compound. A number of applications such as monitoring data from patients under MD therapy are presented.

Chromatography, High Pressure Liquid↗
PubMed1991

Rapid and simple high-performance liquid chromatographic determination of tricyclic antidepressants for routine and emergency serum analysis.

An isocratic reversed-phase high-performance liquid chromatographic procedure is presented for the simultaneous detection of desipramine, nortriptyline, imipramine, amitriptyline and clomipramine in serum. Drugs are extracted after sample alkalinization and separated from each other on an octyl reversed-phase with n-butylamine as mobile phase modifier. Detection is achieved at 254 nm. The recovery of tricyclic antidepressants (92-110%) has good precision, with a relative standard deviation of less than 5%. Being rapid and simple, the method is suitable for the emergency clinical laboratory.

Antidepressive Agents, Tricyclic↗
PubMed1991

High-performance liquid chromatographic method for the determination of prolyl peptides in urine.

A rapid and accurate method is described for the determination of prolyl peptides in urine, with specific reference to the dipeptide prolylhydroxyproline, and free hydroxyproline and proline. Free amino acids and peptides were isolated from urine on cation-exchange minicolumns, and free imino acids and prolyl-N-terminal peptides were selectively derivatized with 4-chloro-7-nitrobenzofurazan, after reaction of amino acids and N-terminal aminoacyl peptides with o-phthalaldehyde. The highly fluorescent adducts of imino acids and prolyl peptides were separated on a Spherisorb ODS 2 column by isocratic elution for 12 min using as mobile phase 17.5 mM aqueous trifluoracetic acid solution containing 12.5% acetonitrile (eluent A), followed by gradient elution from eluent A to 40% of 17.5 mM aqueous trifluoroacetic acid solution containing 80% acetonitrile in 20 min. Analytes of interest, in particular the dipeptide prolylhydroxyproline, can be easily quantified by fluorimetric detection (epsilon ex = 470 nm, epsilon em = 530 nm) without interference from primary amino-containing compounds.

Chromatography, High Pressure Liquid↗
PubMed1991

Functionally active ganglioneuroma with increased plasma and urinary catecholamines and positive iodine 131-meta-iodobenzylguanidine scintigraphy.

Ganglioneuromas are usually considered not to be functionally active. Studies of their catecholamine excretory pattern and of their imaging by means of the adrenergic tracing agent 131-I-MIBG have been therefore sparse. We report on a case of secretory ganglioneuroma, as demonstrated by the increased urinary excretion of the catecholamine metabolites HVA and VMA, increased plasma dopamine and epinephrine levels, and positive 131-I-MIBG scintigraphy. We must therefore be aware that a functionally active tumor is not necessarily a neuroblastoma, and that the diagnosis should be biopsy proven.

3-Iodobenzylguanidine↗
PubMed1991

Plasma catecholamine responses during a personalized physical stress as a dynamic characterization of essential hypertension.

High performance liquid chromatography (HPLC) with electrochemical detection proves to be a reliable method for determination of plasma catecholamines (CA) to assess the possible role of the sympathetic nervous system (SNS) in essential hypertension (EH). The present investigation in a group of 15 normotensive (N) and 13 stable EH patients, homogeneous for age and duration of hypertension, was carried out without treatment in the supine position, up-right position and during a personalized bicycle exercise. Mean blood pressure, mean heart rate, plasma renin activity and plasma aldosterone were also evaluated at the various exertion phases. Norepinephrine (NE) and epinephrine (E) showed a progressive increase in N and in EH patients, reaching the highest values at maximum effort. However, EH patients showed higher E plasma levels than N before maximum effort. Dopamine (DA) reached the highest values in N at maximum effort and in EH patients at recovery time. These findings allow us to foresee the possibility of a better characterization of the SNS role in EH.

Adult↗
PubMed1991

Teicoplanin does not modify the hypoglycemic effects of phenformin or glibenclamide, nor the anticoagulant action of warfarin. Experimental study.

Eventual pharmacological interactions induced by teicoplanin administration associated with oral hypoglycemic (phenformin and glibenclamide) and oral anticoagulant (warfarin) drugs have been experimentally evaluated. The administration of teicoplanin (3-15 mg/kg/die by endoperitoneal route) to the rat for 4 days did not significantly (P greater than 0.05) modify glycemia, prothrombin and partial thromboplastin times, the hypoglycemic effect of phenformin (2.5 mg/kg/die/4 days) or glibenclamide (0.5 mg/kg/die/4 days) nor the anticoagulant effect of warfarin (0.5 mg/kg/die/4 days). In conclusion, our results document that teicoplanin does not interfere with the activity of phenformin, glibenclamide or sodium warfarin.

Administration, Oral↗
PubMed1991

Antagonist effect of terguride in Parkinson's disease.

The effects of the partial dopamine agonist terguride (9,10 transdihydrolisuride; THDL) on striatal dopamine receptors were studied by its i.v. administration to 13 patients with Parkinson's disease. Patients were maintained in a steadily mobile state with abnormal involuntary movements by a constant i.v. infusion of levodopa. Terguride showed dopamine antagonist properties in nine patients. In two of these nine patients, a decrease in dyskinesia score was observed without a concomitant worsening of parkinsonian symptoms, whereas in the remaining seven, full parkinsonian akinesia followed THDL administration. The subsequent i.v. injection of the dopamine agonist lisuride reversed THDL-induced akinesia in these seven patients. In the remaining four patients, no clinically significant motor effects were observed. These results show dopamine antagonist activity of terguride in patients with Parkinson's disease treated with Levodopa. Further studies using a wider dose titration are required to evaluate the possible role of dopamine partial agonists in the therapy of levodopa-induced dyskinesias.

Adult↗
PubMed1991

5-substituted 4-isoxazolecarboxamides with platelet antiaggregating and other activities.

The synthesis of a series of 5-substituted 4-isoxazolecarboxamides by reaction of eight 5-substituted 4-isoxazolecarbonyl chlorides with pyrrolidine, piperidine, morpholine and 4-trifluoromethylaniline is described. Some of these amides showed platelet antiaggregating activity in vitro slightly inferior to that of acetylsalicylic acid, as well weak antiinflammatory, analgesic and antipyretic activities in rats and mice.

Aniline Compounds↗
PubMed1990

Micro-scale liquid chromatographic method for the determination of bamifylline and its major metabolite in human plasma.

A sensitive micro-scale method based on isocratic elution reversed-phase ion-pair chromatography for the determination of bamifylline and its major metabolite (AC 119) in human plasma is described. The method is based on a liquid-liquid extraction clean-up followed by analysis on an LC-Packings Fusica (Delta Pak, RP-18, 5 microns, 300 A) column (15 cm x 330 microns. I.D.) with 0.03 M heptanesulphonate (pH 3.5)-acetonitrile (7:3, v/v) as the mobile phase. Data with respect to recovery, reproducibility and limits of detection are reported and discussed.

Chromatography, Liquid↗
PubMed1990

Applications of high-performance liquid chromatography in bacteriology. I. Determination of metabolites.

The chemotaxonomic approach to the identification of pathogenic bacteria for clinical purposes is surveyed. Primary interest is focused on the applications of HPLC to the determination of metabolic products from anaerobic bacteria. The use of HPLC is attractive as different classes of short-chain acids can be determined in a single analysis. Chromatographic conditions are extensively described, emphasizing the effects of changing variables on the HPLC profiles of analytes. The application of labelling procedures to bacterial metabolites can markedly increase the sensitivity of the analysis of pathological fluids. HPLC appears to be potentially useful in clinical bacteriology for the diagnosis of anaerobic infections.

Bacteria, Anaerobic↗
PubMed1990

Simultaneous measurement of L-dopa, its metabolites and carbidopa in plasma of parkinsonian patients by improved sample pretreatment and high-performance liquid chromatographic determination.

A procedure is described for the determination of L-3,4-dihydroxyphenylalanine (L-DOPA), its metabolites and carbidopa (CD) in plasma of Parkinsonian patients by high-performance liquid chromatography with dual working-electrode coulometric electrochemical detection. An efficient sample preparation scheme is presented for the isolation of L-DOPA, its metabolites and the catecholamines from the same plasma aliquot. After a simple deproteinization with methanol containing 2% of 0.5 M perchloric acid and evaporation of the solvent, L-DOPA, its metabolites and CD were separated with a 5-micron Nucleosil C18 column. Catecholamines were extracted from the supernatant of the deproteinized plasma by ion exchange on small columns and adsorption on alumina. Recoveries were close to 100% for L-DOPA, its metabolites and CD and 70% for catecholamines. The use of the same mobile phase for the concurrent assay of L-DOPA, its metabolites and catecholamines considerably increased the throughput of samples in the chromatographic system. The dual-electrode coulometric detector afforded peak identification by comparing current ratios. Monitoring of data from patients under L-DOPA therapy is reported.

Carbidopa↗
PubMed1990

Development and validation of a high-performance liquid chromatographic method for the determination of desmosines in tissues.

The development and the validation of a general strategy for the simple and accurate analysis of desmosines (isodesmosine and desmosine) in tissues coupled with the determination of collagen (as hydroxyproline) is described. The method is based on simplified sample (i.e., lung) pretreatment which involves, in a PTFE screw-capped Pyrex tube, homogenization, collagen extraction with hot 5% trichloroacetic acid and hydrolysis of the elastin-containing residue with 6 M hydrochloric acid, followed by cellulose minicolumn purification of desmosines from the hydrolysates, dansyl chloride pre-column derivatization of the purified desmosines and reversed-phase high-performance liquid chromatographic (HPLC) analysis of the dansyl derivatives using a Spherisorb ODS-2 column, an on-column enrichment sample device and a linear gradient of organic modifier (acetonitrile) in phosphate buffer. The simple sample pretreatment, the optimized chromatographic conditions and the short HPLC analysis time (less than 15 min) allow the accurate and rapid determination of desmosine and isodesmosine, thus permitting the determination of elastin in several kinds of tissues with a minimum of sample manipulation.

Amino Acids↗
PubMed1990

Modified high-performance liquid chromatographic determination of diamine oxidase activity in plasma.

A previous high-performance liquid chromatographic determination of diamine oxidase activity suitable for tissue homogenates was modified in order to adapt it to plasma samples. Simple additional steps were introduced after the enzyme reaction and before the chromatographic separation, both according to the previous method. In this way the sensitivity and the reproducibility of the overall procedure was suitable for routine plasma diamine oxidase estimations.

Amine Oxidase (Copper-Containing)↗
PubMed1990

High-pressure liquid chromatographic evaluation of cyclic paracetamol-acetylsalicylate and its active metabolites with results of a comparative pharmacokinetic investigation in the rat.

Like benorilate, its correlated open ester, MR 897, a cyclic ester between acetylsalicylic acid and paracetamol, gives rise to acetylsalicylic acid, salicylic acid and paracetamol by enzymatic hydrolysis. An analytical method was developed, which detects parent drugs and active metabolites, in order to compare the pharmacokinetic and metabolic behaviour of the two products. The method was specifically validated for quantitative analysis of salicylic acid and paracetamol, which are the main systemic metabolites of both MR 897 and benorilate. Extraction from plasma or tissue homogenate was carried out in two steps with diethyl ether and acetate. Recovery of the analytical substances ranged from 82.7% for paracetamol to 98.5% for salicylic acid. The results of a comparative pharmacokinetic investigation of MR 897 and benorilate in the rat confirm higher bioavailability and a more favourable plasma level profile with MR 897.

Acetaminophen↗
PubMed1990

Absorption, distribution, metabolism and excretion of 2-[2-thiophenecarboxythio]-N-[dihydro-2-(3H)-thiophenone-3-yl]-propiona mide in the rat.

2-[2-Thiophenecarboxythio]-N-[dihydro-2-(3H)-thiophenone-3-y l]- propionamide (MR 889) was administered orally to rats in order to investigate its pharmacokinetics. 1-2 h after the administration, MR 889 was detected as unchanged compound in plasma only in traces whereas some catabolites, i.e. 2-thiophene carboxylic acid and its glycinate were detected with a tmax of 2 h. The thiolic component of MR 889 induced an evident and sustained increase of total sulfhydryl groups in plasma (tmax 2 h), tissues and urine. Relevant concentrations of 2-thiophene carboxylic acid were found in small intestine and gastric wall followed by liver, lungs and kidneys. The thiolic component also increased, mainly in liver and lungs followed by small intestine and gastric wall. Homocysteine thiolactone S-methyl thiolactamide was identified as a minor metabolite of MR 889.

Administration, Oral↗
PubMed1990

Evaluation of ibuprofen dimethyl aminoethanol octyl bromide and related active metabolites in biological samples.

AF 150 is ibuprofen dimethyl aminoethanol octyl bromide, endowed with antibacterial and antiinflammatory activities. An indirect HPLC analytical method for AF 150 with UV detection, to be used for pharmacokinetic studies, has been validated in terms of linearity, reproducibility, specificity and sensitivity. Using this method the bioavailability of AF 150 and its active metabolite ibuprofen was investigated following parenteral administration and topical application.

Animals↗
PubMed1988

Rapid identification of Bacteroides species by high-performance liquid chromatography.

High-performance liquid chromatography was evaluated for the rapid identification of Bacteroides species of clinical interest. Each isolate was inoculated into a defined chemical medium containing primarily carbohydrates and was incubated aerobically at 37 degrees C for 1 h. After centrifugation, the supernatants were placed on ice to stop further enzymatic reactions. Specimens were injected into an Aminex HPX-87H column in order to determine carbohydrates and acid metabolic products. Peak areas of carbohydrates for each isolate were compared with those for uninoculated medium. As the utilization indexes of raffinose, lactose and arabinose were found to be particularly significant, the patterns of carbohydrate utilization could be used for the identification of Bacteroides species. This method can be adapted for diagnostic laboratory use and has good potential for automated microbial identification.

Bacteroides↗