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Biomedical subjects

G Bordin

Publications and source records attributed to G Bordin.

At least 19 recordsLinked to original sources
PubMed2005

Determination of (fluoro)quinolone antibiotic residues in pig kidney using liquid chromatography-tandem mass spectrometry. Part II: intercomparison exercise.

A recently in-house validated method for the liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of eleven (fluoro)quinolone antibiotics (FQs) in pig kidney has been fully validated through an intercomparison exercise. This ring trial involved eight European laboratories and was based on the Commission Decision 2002/657/CE for validation of method and on the IUPAC protocol for method-performances studies. The laboratories data were submitted to a one-way analysis of variance. Satisfactory results were obtained for each FQ with regards to within- and between-laboratory reproducibility and accuracy. The method was validated for the simultaneous qualitative and quantitative determination of the eleven FQs in pig kidney around their maximum residue limit (MRL) as defined in the European Council Regulation 2377/90/EEC.

Animals↗
PubMed2005

Determination of (fluoro)quinolone antibiotic residues in pig kidney using liquid chromatography-tandem mass spectrometry. I. Laboratory-validated method.

A new LC-MS/MS method has been developed for the multiresidue determination of 11 (fluoro)quinolone antibiotics (FQs), including acidic and amphoteric species, around their maximum residue level (MRL) in pig kidney. The procedure involves a common sample preparation by solid-phase extraction on disposable extraction cartridges followed by a fast reversed-phase liquid chromatography-tandem mass spectrometry analysis. The method was validated according to the Commission Decision 2002/657/CE. The accuracy of the method was satisfactory with recoveries included in the interval 80-100%. The precision results showed mean repeatability and reproducibility coefficients of 7.4% and 11.8%, respectively. Limits of quantification much lower than the MRLs could be obtained.

Animals↗
PubMed2003

Study of the feasibility of using a pellicular anion-exchange column for separation of transferrin isoforms in human serum by HPLC with UV detection.

A method has been optimised for the separation of glycoforms of human serum transferrin, using a high-performance pellicular anion-exchange chromatographic column. The effect of the eluent pH and of the column temperature on the separation of transferrin glycoforms was studied using a standard solution of commercially available human serum transferrin. An HPLC system equipped with an ultraviolet detector was used for the analysis. No immunoassay was used after the anion-exchange chromatographic separation of the glycoforms, in contrast with most currently used methods. The method was applied to the separation and quantification of transferrin glycoforms in serum from a healthy, non-pregnant woman, after saturation of transferrin with iron and further precipitation of lipoproteins. The whole chromatographic run, including re-equilibration of the column, took 35 min.

Chromatography, High Pressure Liquid↗
PubMed2003

The two hit hypothesis in the antiphospholipid syndrome: acute ischaemic heart involvement after valvular replacement despite anticoagulation in a patient with secondary APS.

A patient with the antiphospholipid syndrome (APS), in whom a nonfatal myocardial infarction ensued after valvular heart replacement despite anticoagulation, is described. The report further stresses the role of concomitant risk co-factors in inducing thrombotic events and points out that cardiosurgery might represent a potential major risk for myocardial ischaemic damage in APS.

Abortion, Spontaneous↗
PubMed2002

Development of new analytical methods for selenium speciation in selenium-enriched yeast material.

A sequential extraction allowing the discrimination of water-soluble and non-soluble selenium fractions has been developed to evaluate the availability of selenium (Se) in an Se-enriched yeast candidate reference material. The fractionation of selenium-containing compounds in the extracts was achieved on preparative grade 200 Superdex 75 and columns. It showed that water-soluble selenium is present in several fractions with a large mass distribution. Low-molecular- (< or = 10,000) and high-molecular-mass selenocompounds (range 10,000-100,000) were considered separately for further experiments. The analytical approach for low-molecular-mass selenocompounds was based onanion-exchange HPLC with on-line inductively coupled plasma (ICP) MS for quantitative analysis. Selenocystine, selenomethionine, selenite and selenate were quantified in the fractions isolated in preparative chromatography. The study revealed the existence of various unidentified Se species in yeast material. The Se-containing proteins in the yeast material have been further separated and selenium quantified by the combination of gel electrophoresis and electrothermal vaporization-ICP-MS. This new approach allows the separation of the proteins with high resolution by sodium dodecylsulfate-polyacrylamide gel electrophoresis and the sensitive determination of selenium in the protein bands.

Calibration↗
PubMed2002

Validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of 11 (fluoro)quinolone antibiotics in swine kidney.

A LC-MS-MS method has been validated for the simultaneous quantification of 11 (fluoro)quinolone antibiotics at the maximum residue level (MRL) in swine kidney. The studied compounds were danofloxacine, cinoxacine, ciprofloxacine, noxacine, enrofloxacine, flumequine, marbofloxacine, nalidixic acid, norfloxacine, ofloxacine and oxolinic acid. The method involves solid-phase extraction of these compounds followed by LC-MS-MS analysis using an electrospray ionisation interface. Limits of quantification < or = 50 microg/kg could be obtained in swine kidney, much lower than every MRL. The validation is discussed. This work was carried out in order to support the European Union policy on consumer health

Animals↗
PubMed2002

Identification, characterization and determination of metal-binding proteins by liquid chromatography. A review.

The use of liquid chromatography in the separation and determination of metal-binding proteins is reviewed. Advantages and drawbacks of different chromatographic techniques based on various principles: size exclusion, ion exchange (cationic and ionic), reversed phase and affinity, are presented and discussed. The topic "metal-binding proteins" is considered and presented from two different points of view. The first one regards metal speciation in biological samples (serum and blood). In metal speciation studies, the exact identity of the protein to which the metal is bound often remains unknown. The second point of view is that, frequently, the interest of analyzing metal-binding proteins is not related anymore to the metallic fraction of the protein, but to other chemical structures attached to the protein, such as carbohydrates, which indirectly determine how good the function of the protein is. In this review, special attention is paid to studies dealing with the glycosylation of transferrin, and with the glycated isoform of haemoglobin.

Chromatography, Liquid↗
PubMed2001

Identification and quantification of major bovine milk proteins by liquid chromatography.

In the field of food quality, bovine milk products are of particular interest due to the social and economic importance of the dairy products market. However, the risk of fraudulent manipulation is high in this area, for instance, replacing milk powder by whey is very interesting from an economic point of view. Therefore, there is a need to have suitable analytical methods available for the determination of all milk components, which is currently not the case, especially for the main proteins. The detection of potential manipulations requires then a clear analytical characterisation of each type of bovine milk, what constitutes the goal of this work. The separation of the major milk proteinic components has been carried out by ion-pair reversed-phase HPLC with photodiode array detection, using a C4 column. The overall optimisation has been achieved using a statistical experimental design procedure. The identification of each protein was ascertained using retention times, peak area ratios and second derivative UV spectra. Quantification was based on calibration curves drawn using purified proteins. Major sources of uncertainty were identified and the full uncertainty budget was established. The procedure was initially developed using the skimmed milk powder certified reference material CRM 063R and then applied to various types of commercial milks as well as to raw milk. The method is able to separate and quantify the seven major proteins (K-casein, alphas2-casein, alphas1-casein, beta-casein, alpha-lactalbumin, beta-lactoglobulin B and beta-lactoglobulin A) in one run and also to provide precise determinations of the total protein concentration. These are important results towards the further development of a reference method for major proteins in milk. In addition, the use of a certified material reference is suggested in order to make comparisons of method performances possible.

Animals↗
PubMed2001

How to overcome matrix effects in the determination of pesticides in fruit by HPLC-ESI-MS-MS.

A high-performance liquid chromatographic method, with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS-MS) for detection, has been developed for the determination of thiabendazole, carbendazime, and phenylurea pesticides in fruit matrices. During the validation process the method was tested for matrix effects, blanks, and the stability of the system. Considerable unspecific matrix effects in the ESI (+) process were detected by comparing standard calibration, and matrix calibration, although blank values were very low and the specific calibration functions showed only small standard deviations. This effect was overcome by using a more complex clean-up, i.e. an additional size-exclusion step.

Calibration↗
PubMed2001

Uncertainty estimation on the quantification of major milk proteins by liquid chromatography.

A detailed uncertainty budget is evaluated for the quantification of major milk proteins separated by reversed phase ion-pair high performance liquid chromatography (RP-IP HPLC). Recommendations from the International Organisation for Standardisation, Guide to the Expression of Uncertainty and the EURACHEM/CITAC Guide "Quantifying Uncertainty in Analytical Measurement" were followed resulting in the expression of combined uncertainties as an expanded uncertainty. The authors have identified the lack of a detailed description on all possible sources of uncertainty on chromatographic milk protein separations. Up to now, uncertainty has only been expressed as a random chromatographic variability, being exclusively measured by regression equations. On the contrary, the establishment of a full uncertainty budget permits a complete identification of all sources of uncertainty associated with the measurement. Thus, a better comprehension of the method is obtained. Having identified all sources of uncertainty, to the best of our knowledge, they are minimised (whenever possible) and combined. The importance of this identification is crucial, in particular, concerning previously neglected sources, in this example the combination of the interpolated injected mass of protein and its purity, having a dominant influence on the total combined uncertainty. The quality of the measurement (measured by its associated uncertainty statement, which should be based on a full uncertainty budget evaluation) is demonstrated. Moreover, due to the high precision of the proposed method, the total protein content, in addition to the group protein composition (i.e. total casein and whey protein content) is calculated with high reliability, which is an extremely useful factor regarding the establishment of milk provenance/adulteration. Combined relative standard uncertainties ranging from 3.3 up to 12.5% for individual protein concentration were found, whereas for total protein content, an overall combined relative standard uncertainty of 2.7% (liquid) and 3.3% (powdered samples) was achieved.

Animals↗
PubMed2001

Tachykinin activation of human monocytes from patients with rheumatoid arthritis: in vitro and ex-vivo effects of cyclosporin A.

Three types of tachykinin receptors, namely NK1, NK2 and NK3, are known to preferentially interact with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), respectively. We previously demonstrated that NK1 and NK2 receptors are present on human monocytes, SP and NKA inducing superoxide anion production and tumor necrosis factor-alpha (TNF-alpha) mRNA expression. NK2 receptor stimulation also triggered an enhanced respiratory burst in monocytes isolated from rheumatoid arthritis (RA) patients. This study was aimed to evaluate the in vitro and ex-vivo effects of cyclosporin A (CsA) on tachykinins-evoked TNF-alpha release from monocytes of healthy donors and RA patients. CsA (100 ng/ml) potently inhibited phorbol ester- and tachykinin-evoked TNF-alpha secretion. In RA patients treated with CsA (Sandimmun Neoral 2.5 mg/kg/day, a significant time-dependent reduction in TNF-alpha secretion from monocytes was measured. This may contribute to the CsA therapeutic activity in RA.

Arthritis, Rheumatoid↗
PubMed2001

A comparison of cyclosporine, sulfasalazine, and symptomatic therapy in the treatment of psoriatic arthritis.

OBJECTIVE: To compare the efficacy and tolerability of cyclosporine (CSA) with that of symptomatic therapy (ST) alone and sulfasalazine (SSZ) in the treatment of psoriatic arthritis (PsA). METHODS: Twelve rheumatology centers recruited 99 patients with active PsA in a 24 week, prospective, randomized, open, controlled study. The patients were treated with CSA (3 mg/kg/day) or SSZ (2,000 mg/day) plus ST, or ST alone (nonsteroidal antiinflammatory drugs, analgesics, and/or prednisone < or = 5 mg/day). The primary endpoint was the 6 month change in pain. Analyses were on the basis of the intention-to-treat principle. RESULTS: In comparison with both SSZ and ST, there was a statistically significant difference in favor of CSA in terms of the mean changes in the pain score (p < 0.05), which was considered the primary response variable. A significant decrease in favor of CSA versus ST alone was also observed for swollen joint count (p = 0.05), tender joint count (p = 0.01), joint/pain tenderness score (p = 0.002), patient and physician global assessment by at least one point (p = 0.04 and 0.01, respectively), total Arthritis Impact Measurement Scale score (p = 0.002), and spondylitis functional index (p = 0.002). There was a statistically significant difference in the ACR 50% and ACR 70% response rates between the CSA and ST groups (p = 0.02, 0.05). Comparing the SSZ and ST alone groups, only the spondylitis functional index decreased significantly in the SSZ treated patients (p = 0.03). The Psoriasis Area and Severity Index was significantly lower in the CSA than in the ST and SSZ groups (p = 0.0001 and 0.01, respectively). Decrease in erythrocyte sedimentation rate was significant only in the SSZ versus the ST group (p = 0.02), whereas reduction in C-reactive protein was significant in the CSA treated patients compared with the ST group (p = 0.006). The most common adverse event in the CSA group was mild, reversible kidney dysfunction. CONCLUSION: The results of this open trial confirm that CSA is well tolerated by patients with PsA and suggest that it is more efficacious than ST or SSZ.

Adult↗
PubMed1998

Tachykinin receptors on human monocytes: their involvement in rheumatoid arthritis.

Three types of tachykinin receptors, namely NK1, NK2 and NK3, are known to preferentially interact with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), respectively. Experimental evidence indicates that SP and NKA modulate the activity of inflammatory and immune cells, including mononuclear ones. This study evaluated the effects of mammalian tachykinins and selective tachykinin agonists and antagonists on human monocytes isolated from healthy donors: SP, NKA and NKB all evoked a dose-dependent superoxide anion (O2-) production and the NK2 selective agonist [beta-Ala8]-NKA(4-10) induced a full response. The NK3 selective agonist senktide was inactive, while the NK1 selective agonists septide and [Sar9Met(O2)11]SP displayed some effects. These results indicate that NK2 and also some NK1 receptors are present in monocytes isolated from healthy donors. The role of tachykinin receptor activation in rheumatoid arthritis was also investigated, by measuring O2- production and TNF-alpha mRNA expression in monocytes isolated from rheumatoid patients. Tachykinins enhanced the expression of this cytokine in both control and rheumatoid monocytes and NK2 receptor stimulation was shown to trigger an enhanced respiratory burst in monocytes from rheumatoid patients. In conclusion, these results indicate that NK2 and NK1 receptors are present on human monocytes, the former being preferentially involved in rheumatoid arthritis.

Aged↗