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M Patriarca

Publications and source records attributed to M Patriarca.

At least 19 recordsLinked to original sources
PubMed2006

Fractional Fokker-Planck dynamics: Numerical algorithm and simulations.

Anomalous transport in a tilted periodic potential is investigated numerically within the framework of the fractional Fokker-Planck dynamics via the underlying continuous-time random walk. An efficient numerical algorithm is developed which is applicable for an arbitrary potential. This algorithm is then applied to investigate the fractional current and the corresponding nonlinear mobility in different washboard potentials. Normal and fractional diffusion are compared through their time evolution of the probability density in state space. Moreover, we discuss the stationary probability density of the fractional current values.

Journal Article↗
PubMed2006

Current and universal scaling in anomalous transport.

Anomalous transport in tilted periodic potentials is investigated within the framework of the fractional Fokker-Planck dynamics and the underlying continuous time random walk. The analytical solution for the stationary, anomalous current is obtained in closed form. We derive a universal scaling law for anomalous diffusion occurring in tilted periodic potentials. This scaling relation is corroborated with precise numerical studies covering wide parameter regimes and different shapes for the periodic potential, being either symmetric or ratchetlike.

Journal Article↗
PubMed1999

A Novel Dinuclear Diaminoplatinum(II) Glutathione Macrochelate.

Both oxidized and reduced glutathione (gamma-L-Glu-L-Cys-Gly) react with the anticancer complex [Pt(en)Cl(2)] to form the bicyclic complex illustrated (en=ethylenediamine). This unprecedented structure, which was determined from extensive NMR experiments, contains a ten-membered macrochelate ring.

Journal Article↗
PubMed1999

Determination of low concentrations of potentially toxic elements in human liver from newborns and infants.

One hundred and fifty-seven liver samples from newborns and infants who had died from sudden infant death syndrome (SIDS) or other known causes have been analysed by ICP-MS for Ag, Cd, Co, Pb and Sb. The median concentrations found were: 15.4 (Ag), 2.9 (Cd), 15.9 (Co), 65.2 (Pb) and 1.8 (Sb) ng g-1 wet mass. There was no measurable difference in the concentrations of any of these elements between the SIDS and non-SIDS groups. The validity of the results was assessed by analysis of appropriate reference materials, interlaboratory comparison and isotope dilution analysis. The instrumental limits of detection were 0.25 (Ag), 0.14 (Cd), 0.21 (Co), 3.8 (Pb) and 0.38 (Sb) ng g-1 wet mass. The limits of detection of the method depend on the reagent blank and the extent of background contamination.

Antimony↗
PubMed1999

[The role of biological monitoring in the evaluation of the risk of from chemical compounds].

Over the years, the assessment of the risk to human health from occupational and environmental exposure to chemicals has become increasingly important. Exposure to chemicals, their biochemical effects and individual susceptibility can be estimated by biological monitoring carried out on potentially exposed subjects. Valid markers are needed to be effectively used within the framework of biological monitoring programs. Quality assurance, which includes all those activities necessary to provide adequate confidence that the results of laboratory test are reliable, is of the utmost importance. Among these activities the participation in external quality assessment schemes is strongly recommended. Biological monitoring has a key role also in the field of human reproduction since the level of exposure to many chemicals which are known or suspected to be reproductive toxicants can be assessed by specialized laboratories.

Environmental Monitoring↗
PubMed1998

[Quality control of data produced in biological population surveillance studies on the risk of environmental lead poisoning].

The biological surveys of the general population against the risk of lead intoxication carried out in Italy--in accomplishment both of the EEC directive EEC 77/312 and the Presidential Decree 496/1982--have been always conceived as multicentric activities. Therefore, starting from the first campaign carried out in 1979, strict quality control procedures have been adopted. In brief, each participant laboratory used internal quality control samples and took part in external quality assessment exercises. In addition, ten percent of the blood samples collected during the campaign were analyzed as blind duplicate by both participating laboratories and a reference laboratory. In this paper the quality control procedures adopted will be presented and discussed in detail together with the quality of results obtained in each campaign.

Environmental Exposure↗
PubMed1998

[Lead exposure: risk evaluation for the general Italian population in 1990].

The second Italian campaign for the biological surveillance of the general population against the risk of lead intoxication has been carried out according to the regulations contained in the Presidential Decree DPR 496/82. The investigations of the second campaign--based on the measurement of blood lead levels (PbB)--have been carried out mainly between 1992 and 1996 by various operating centers in some Italian regions. A work group from the Istituto Superiore di Sanità (Italian National Institute of Health) coordinated the activity of the various centers and organised an appropriate quality control program to guarantee the quality of the analytical data collected. A total of 7749 non exposed subjects (4346 females and 3403 males) has been examined, 1170 of which (559 females and 611 males) were under 15 years of age. The median PbB was, for adults, 86 micrograms/l in males and 53.5 micrograms/l in females. As for subjects under the age of 15, PbB levels were 50 micrograms/l and 43 micrograms/l in males and females, respectively. Our investigation confirms the correlation between blood lead levels, wine, and cigarette smoking. The comparison with the results of previous investigations shows a reduction between 40% and 50% of PbB in the general Italian population during the 1985-96 period. It should be pointed out that in certain areas more than 5% of subjects under 15 years of age had PbB exceeding the level (100 micrograms/l) considered safe for avoiding irreversible injury to the central nervous system.

Adolescent↗
PubMed1998

Use of the stable isotope 65Cu test for the screening of Wilson's disease in a family with two affected members.

BACKGROUND/AIMS: An improved method for the study of copper metabolism in Wilson's disease, using a stable, rather than radioactive, copper isotope (65Cu) has recently been described. We report on the use of this method for the study of a family with two members affected by Wilson's disease. SUBJECTS: The family comprised parents and four siblings: one 20-year-old male and three females, aged 22, 17 and 5 years, respectively. The boy and the 17-year-old girl both presented with liver cirrhosis. Diagnosis of Wilson's disease was suggested by elevated liver copper content and/or low caeruloplasmin levels and Kayser-Fleischer ring. METHODS: All family members were given an oral dose of 3 mg of 65Cu. Blood samples were taken at 0, 1, 2, 6, 24, 48, and 72 hours. In 4 subjects, additional blood samples were drawn at 7, 14 and 21 days after dosage. The ratio 65Cu:63Cu in serum was determined in all samples by means of Inductively Coupled Plasma Mass Spectrometry. RESULTS: The diagnosis of Wilson's disease was confirmed in the two symptomatic members by the unequivocal decrease observed in the 65Cu percent enrichment, which approached zero by 72 hours. In contrast, Wilson's disease could be definitely excluded in both siblings, one of whom only 5 years old, on the evidence of net secondary peaks, showing normal incorporation of 65Cu into caeruloplasmin. These findings were later confirmed by genetic analysis. Parents, who carried defective genes with different mutations, also showed different abnormalities of copper metabolism. CONCLUSIONS: The oral test with the stable copper isotope 65Cu is a safe, non invasive option able to exclude Wilson's disease in patients with a difficult diagnosis or in a presymptomatic stage. However, positive tests must still be confirmed by copper dosage in liver biopsies, as heterozygotes can present with severe alterations of copper metabolism, without developing symptoms of the disease. The use of this test in conjunction with genetic analysis on a larger number of heterozygous subjects may add to the understanding of the Wilson's disease defect.

Adolescent↗
PubMed1997

Nickel metabolism in humans investigated with an oral stable isotope.

We report the results of the first complete study of nickel metabolism in human subjects using a stable nickel isotope (62Ni) as tracer. Four healthy adult subjects (two women and two men) fasted overnight before ingesting 10 microg 62Ni/kg body wt. Blood samples were drawn after fixed intervals of time and the total daily output of urine and feces was collected for the first 5 d after dose ingestion. 62Ni in plasma, urine, and feces was determined by isotope-dilution inductively coupled plasma-mass spectrometry with 61Ni. The direct measurement of the fecal excretion of the tracer allowed a reliable assessment of nickel absorption from the gastrointestinal tract and we found no evidence of the excretion of absorbed nickel via the gut. The percentage absorption calculated from the amount of 62Ni excreted in the feces ranged from 29% to 40%. Urinary excretion over 5 d ranged from 51% to 82% of the absorbed dose. Plasma 62Ni peaked between 1.5 and 2.5 h after ingestion and decreased by a factor of > 10 over the next few days. We observed low between-subject variability of nickel absorption and excretion. Confounding factors such as contamination and dietary intake of nickel, which hampered earlier measurements in subjects dosed with naturally abundant nickel, were eliminated by using the tracer isotope 62Ni.

Administration, Oral↗
PubMed1996

First steps toward harmonisation of European EQAS in occupational and environmental laboratory medicine: from Dublin to Rome.

Laboratories performing analyses in the field of occupational and environmental medicine (OELM) must provide reliable results for an increasing number of analytes related to exposure to chemicals. Participation in external quality assessment schemes (EQAS) allows laboratories to assess their performance and is regarded as a pre-requisite for accreditation from appropriate national and supranational bodies. Within the framework of the European Union, harmonisation of procedures for evaluation of laboratory performance in EQAS is desirable, in order to achieve a similar degree of excellence within Europe. Collaboration among different countries would also be profitable to compare experiences, develop new schemes, covering a wider range of analytes, and to devise common research on specific problems. We report on initiatives developed to meet this objective, in collaboration with the Standards, Measurements & Testing (SM&T) programme of the European Commission (EC), Directorate General XII. Meetings were held in Dublin and Rome which allowed experience among European EQAS organisers in OELM to be shared. Discussion focused on the identification of common needs and areas where collaborative work could be carried out.

Environmental Health↗
PubMed1996

The Italian external quality assessment scheme for trace element analysis in body fluids.

We describe the operative procedures of the Italian external quality assessment scheme (EQAS) for the determination of trace elements in body fluids. The aims of the scheme are both the education of participants and the continuous development and optimization of procedures for collaborative EQA trials. Participation is free of charge. Interlaboratory exercises for EQA are organised every three or four months for the determination of cadmium and lead in blood; aluminium, copper, selenium and zinc in serum; chromium and nickel in urine. Freeze-dried control materials are prepared in the laboratory from animal blood or human urine. In each trial, each participant receives from six to eight samples, chosen from among the pools selected for that occasion using a randomised strategy and including unknown duplicate specimens. Laboratory performances are evaluated on the basis of proximity to target values, differences in results for duplicate samples and comparison with established acceptability limits. The development of dedicated software for the bidirectional transmission of data between the organising centre and the peripheral laboratory gives the participants the chance to verify immediately the quality of their results and take action without delay, if needed.

Environmental Monitoring↗
PubMed1996

Prospects of harmonisation of European external quality assessment schemes in occupational and environmental laboratory medicine.

Since 1979, twelve external quality assessment schemes (EQAS) in occupational and environmental laboratory medicine (OELM) have been developed in nine European countries. These schemes cover a broad range of analytes and matrices and have developed differing procedures for the evaluation of laboratories' performances. Collaboration among EQAS in OELM and harmonisation of methods for evaluation of laboratory performance would be advantageous to cope with the demand for assessment of quality of analytical results for an increasing number of analytes and the need to guarantee comparability and consistency of conclusions on health and regulatory issues in different countries and at an international level. This paper compares the different features of the existing EQAS, to highlight critical points for further discussions, and to make some suggestions for possible further collaboration.

Environmental Medicine↗
PubMed1995

Organization and results of a pilot scheme for external quality assessment in clinical chemistry carried out in the Latium region, Italy.

The results of an external quality assessment scheme (EQAS), carried out in the Latium region between October 1987 and December 1988, are reported. Ninety-four laboratories, both public and private, took part in the scheme. Aim of the scheme was to estimate the reliability of the clinical chemistry services in this region. The participating laboratories received eight control samples for EQA, every two months. The analytes to be determined in each sample were: glucose (GLU), urea (UR), total protein (TP), uric acid (UA), creatinine (CR), bilirubin (BIL), cholesterol (CHO), triglycerides (TRI), sodium (Na), potassium (K), calcium (Ca), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CPK), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP). Global laboratory performances were evaluated in terms of interlaboratory precision, accuracy--as deviation per cent from the target values and coefficient of variation (CV)--and percentage of results within pre-set acceptability limits. The deviations were reasonably low, whereas the CVs were rather high. The percentage of acceptable results was lower than 50% for the analytes urea, calcium, uric acid, creatine kinase and alkaline phosphatase. The performance of the examined laboratories was worse than those obtained in other regional and national EQAS, both in terms of CVs and percentage of acceptable results.

Chemistry, Clinical↗
PubMed1995

Quality assurance in the determination of metals in clinical chemistry and toxicology: the METOS project. Metalli Tossici.

National external quality assessment schemes (EQAS) for the determination of trace elements in blood (Al, Cd, Cu, Pb, Zn) have been promoted in Italy since 1983. They were organized by a working group of the Istituto Superiore di Sanità and known as "METOS (Metalli Tossici, toxic metals) project". The organization of the schemes included the preparation of suitable control materials by the promoting centre and the elaboration of valuable strategies of sample distribution, treatment of data and evaluation of results, that could be applied even to a small number of participants. The procedures used and the results obtained in ten years of activity of the METOS project are reported. Within the framework of the programme some information has been obtained, confirming the validity of the procedures used for sample preparation, sample distribution and evaluation of laboratories performance.

Chemistry, Clinical↗
PubMed1995

[Quality control for trace elements in occupational and environmental medicine].

The adoption of procedures warranting the quality of the results obtained in the laboratory is of the utmost importance, whatever the reason these analyses are required for. We discuss some of the fundamentals of quality assurance, as recommended by the International Federation of Clinical Chemistry, IFCC. Procedures for the preparation of control and calibration materials, the evaluation of analytical methods and the assessment of laboratory performance by means of internal quality control procedures, including control charts, are reviewed. Finally, we report the organisation and the strategies use in programmes for external quality assurance for the determination of trace elements in biological fluids.

Calibration↗
PubMed1993

The quality of analytical determinations of copper and zinc in serum. A collaborative study in a sample of Italian laboratories.

An external quality assurance scheme for Cu and Zn analysis in serum was carried out in Italy between 1989 and 1990. It included: preparation of control materials by the organizing centre; distribution of control samples to the participants according to a random selection; elaboration of results and evaluation of laboratory performance. Inter-laboratory variability was 16.9% and 16.4%, at concentrations of 0.94 and 1.08 mg/l, for Cu and Zn, respectively. Laboratory performance in terms of percentage of results within the limits of acceptability, improved for Cu, but not for Zn analysis.

Blood Chemical Analysis↗