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Biomedical subjects

S Girotti

Publications and source records attributed to S Girotti.

At least 19 recordsLinked to original sources
PubMed2006

Trace metals in arcid clam Scapharca inaequivalvis: effects of molluscan extracts on bioluminescent bacteria.

The relationship between a supposed effect of molluscan extracts on bioluminescent bacteria and metal concentrations in the extracts was investigated. For this purpose a biotoxicological assay based on bioluminescent bacteria (BLB) and extracts from metal exposed molluscs, Scapharca inaequivalvis, was optimized to monitor Cd and Cu marine pollution. Cu and Cd concentrations increased in tissues of experimentally exposed molluscs. Molluscan extracts inhibited the bacterial luminescence, the inhibition decreasing as the time of mollusc exposure to metals increased, suggesting a reduction of the "bioactive" metals. In regard to the use of BLB test in environmental monitoring, the analysis of Cu, Cd, and metallothionein (MT) was first performed in tissues from molluscs collected in three different areas of Northern Adriatic Sea. Metal concentrations reached maximum values in the gills, while Cd was mostly bound to MT in the kidney. Significant differences in metals and MT concentrations were found depending on the sampling sites. The biotoxicological assay resulted slightly correlated with the biochemical parameters.

Animals↗
PubMed2006

Bioluminescent bacteria assay of veterinary drugs in excreta of food-producing animals.

The residues of pharmacological treatments on food-producing animals, present in the manure dispersed on agricultural land, can impact environmental and human health through toxic, genotoxic, and drug-resistance development effects. Biotoxicity assays can easily reveal the presence of noxious substances and those based on bioluminescent bacteria (BLB) are particularly simple and rapid. A BLB assay was developed as microplate format by using various strains of Vibrio sp. and was employed to evaluate their response to pure antibiotic solutions and to residues extracted from excreta of antibiotic treated pigs and turkeys. The residues were quantified by HPLC analysis. The BLB assay can be proposed as an easy-to-perform screening tool to assess the presence of residues due to undeclared current, or recently ended, pharmacological treatments, as well as to evaluate their permanence in manure.

Animals↗
PubMed2004

Occurrence and distribution of pesticides in the province of Bologna, Italy, using honeybees as bioindicators.

Samples of honeybees (Apis mellifera, n = 92) from 14 beehive monitoring stations located in 3 townships in the province of Bologna were analyzed from April to October 2000. The concentration of 32 organophosphorus pesticides and 5 carbamates was determined through liquid-liquid extraction followed by gas chromatography with a nitrogen-phosphorus detector and liquid chromatography coupled to mass spectrometry using atmospheric pressure chemical ionization in positive and negative ion modes. The most contaminated samples were from Granarolo Emilia where cereals (wheat, sorghum, and corn), sugar beets, and potatoes are the main agriculture products. Thirty-five pesticides were detected, with organophosphorus being the most abundant ones. Malathion was detected in 58% of the samples (mean level 0.360 mg/kg) followed by fenithrothion in 53% of the samples (mean level 0.544 mg/kg) and pirimiphos methyl in 48% of the samples (mean level 0.006 mg/kg). Temporal trends showed that the maximum detection frequency occurred in late spring and was associated with the use of treatment products and less rainfall. The obtained results demonstrated the feasibility of using honeybees for assessing pesticide exposure in agriculture settings.

Agriculture↗
PubMed2001

Determination of organophosphorus pesticides in honeybees after solid-phase microextraction.

A method based on solid-phase microextraction (SPME) followed by gas chromatography with nitrogen-phosphorus detection was developed for the purpose of determining 18 organophosphorus pesticide residues in honeybee samples (Apis mellifera). The extraction capacities of polyacrylate and poly(dimethylsiloxane) fibers were compared. The main factors affecting the SPME process, such as the absorption time profile, salt, and temperature, were optimized. The method involved honeybee sample homogenization, elution with an acetone:water solution (1:1) and dilution in water prior to fiber extraction. Moreover, the matrix effect on the extraction was evaluated. In samples spiked at the 0.2 mg kg(-1) level, the coefficient variation was between 1 and 13% and the detection limits were below 10 microg kg(-1). The SPME procedure was found to be quicker and more cost-effective than the solvent extraction method commonly used. The method was applied successfully to environmental screening. Parathion methyl was detected and confirmed in the real samples analyzed.

Animals↗
PubMed2001

Multiresidual method for the gas chromatographic analysis of pesticides in honeybees cleaned by gel permeation chromatography.

The analysis of several organophosphorus and carbamate pesticide residues in the bodies of honeybees using gas chromatography (GC) and gel permeation chromatography (GPC) clean-up is described. Freeze-dried or lyophilized insect samples were blended with diatomaceous earth (Extrelut) then underwent elution with methylene chloride. This extraction method has shown good recovery on various spike standard levels. Samples are cleaned up by GPC with a Bio Beads SX 3 column and a cyclohexane-ethylacetate (1:1) eluant. Organophosphorus and carbamate compounds are quantified using capillary gas chromatography. Good linearity ranges were observed for all compounds. The extraction process was rapid and results were good, despite the complexity of the matrix on which it was applied. It allowed a reduction both in cost and the consumption of solvents, thereby safeguarding the health of the analyst and the environment. Environmental monitoring using bees was confirmed to be a valid procedure.

Animals↗
PubMed2001

Analysis of organophosphorus pesticides in honeybee by liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry.

Pesticides applied in extended agricultural fields may be controlled by means of bioindicators, such as honeybees, in which are the pesticides bioaccumulate. Liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) experiments with positive (PI) and negative (NI) ion modes were optimized for the analysis of 22 organophosphorus pesticides in honeybee samples. The extraction required 3 g of sample, which was extracted with acetone. The extract was purified with coagulating solution and reextracted with Cl(2)CH(2). Pesticides studied could be detected by both ionization modes except for parathion, parathion-methyl, and bromophos, which did not give signals in PI mode, and triazophos, which was not detected in NI mode. Fragmentation voltage and vaporizer temperature were optimized to achieve the highest sensitivity. The spectra profile of each pesticide in PI mode showed the [M + H](+) ion as the main signal, whereas in NI mode only fragment ions were shown. The detection limit obtained in selected ion monitoring mode ranged from 1 to 15 microg kg(-1). The average recoveries from spiked honeybees at various concentration levels (0.5-5 mg kg(-1)) exceeded 65% with relative standard deviations of 4-15%. The method was applied to real samples, in which residues of coumaphos and dimethoate were detected.

Animals↗
PubMed1999

Chemiluminescent determination of xanthine oxidase activity in milk.

A chemiluminescent method for determining xanthine oxidase (XOD) activity was developed and applied to the assay of milk enzyme activity using a photomultiplier luminometer. Various kinds of milk and cream samples were analysed for XOD content. In pasteurized milk, XOD activity depended on the fat content and in UHT milk it disappeared owing to the heat treatment. Milk sample preparation was very simple, requiring only homogenization at 40 degrees C followed by a 1:10 dilution with UHT ('XOD-free') milk. The assay was carried out at 25 degrees C. The response obtained from XOD standard solutions in milk was linear from 0.1 to 500 enzyme units (U) l-1, but for the actual milk samples values ranged only from 1 to 135 U l-1. The detection limit at 2 SD was 0.1 U l-1 in milk, while in buffer it was 100 times lower. The intra-assay and interassay CV for XOD activity in milk were 6-12%.

Animals↗
PubMed1999

Development of a chemiluminescence competitive PCR for the detection and quantification of parvovirus B19 DNA using a microplate luminometer.

BACKGROUND: Quantitative PCR of viral nucleic acids can be useful clinically in diagnosis, risk assessment, and monitoring of antiviral therapy. We wished to develop a chemiluminescence competitive PCR (cPCR) for parvovirus B19. METHODS: Parvovirus DNA target sequences and competitor sequences were coamplified and directly labeled. Amplified products were then separately hybridized by specific biotin-labeled probes, captured onto streptavidin-coated ELISA microplates, and detected immunoenzymatically using chemiluminescent substrates of peroxidase. Chemiluminescent signals were quantitatively analyzed by a microplate luminometer and were correlated to the amounts of amplified products. RESULTS: Luminol-based systems displayed constant emission but had a higher detection limit (100-1000 genome copies) than the acridan-based system (20 genome copies). The detection limit of chemiluminescent substrates was lower (20 genome copies) than colorimetric substrates (50 genome copies). In chemiluminescence cPCR, the titration curves showed linear correlation above 100 target genome copies. Chemiluminescence cPCR was positive in six serum samples from patients with parvovirus infections and negative in six control sera. CONCLUSIONS: The chemiluminescence cPCR appears to be a sensitive and specific method for the quantitative detection of viral DNAs.

DNA, Viral↗
PubMed1997

A chemiluminescent flow sensing device for determination of choline and phospholipase D activity in biological samples.

A chemiluminescent flow-sensing device for the determination of phospholipase D (PLD) activity and/or choline (Ch) in biological samples using choline oxidase (ChO) and horseradish peroxidase (HRP) immobilized on Eupergit C (polymer beads of methacrylamide, N-methylene-bis-methacrylamide, and allyl-glycidyl-ether) was developed. The best results were obtained with immobilized ChO and HRP at a polymer beads wet weight ratio of 16:1. The optimized parameters of the developed sensing device were 56 microM luminol in working solution; sample volume, 60 microliters; flow rate, 0.3 ml/min; and sample throughput, 15/h. The detection limit (3 SD) using a luminescent enhancer was 1.2 microM for Ch, corresponding to 0.167 mIU of PLD activity per milliliter. Without enhancer the values were 3.0 microM and 0.417 mIU, respectively. The Ch recovery varied between 80.4 and 109%. The biological samples quenched the luminescent light to different extents, and this matrix effect was readily overcome by measuring the luminescent signal of added Ch standard. The flow biosensor was used for the determination of PLD in samples of different origin, including rape seeds during maturation.

Alcohol Oxidoreductases↗
PubMed1996

Chemiluminescent immunoperoxidase assay for the dot blot hybridization detection of Parvovirus B19 DNA using a low light imaging device.

A new synthesized stable trifluoro-substituted acridan (2',3',6'-trifluorophenyl 10-methylacridan-9-carboxylate known as Lumigen PS-3) has been applied as chemiluminescent substrate of the horseradish peroxidase (HRP) enzyme (neutral isoenzyme C) in a dot blot hybridization assay for the detection of B19 Parvovirus DNA. The dot blot hybridization assay uses digoxigenin-labeled DNA probes which are immunoenzymatically revealed by anti-digoxigenin Fab fragments conjugated with HRP. The results obtained using PS-3 reagent or the luminol-based enhanced chemiluminescence detection system (ECL Amersham and Renaissance DuPont NEN kits) were compared. A high-performance, low-intensity-light imaging luminograph apparatus to collect light emission was used. The detection systems using the different chemiluminescent substrates gave sensitive and reproducible results for calibration graphs, with high precision (relative standard deviation 5-18%). With the chemiluminescent assay it was possible to detect 0.5, 1, or 2 pg of target homologous DNA, using PS-3, ECL, or Renaissance (RE) reagents, respectively, while colorimetry had a detection limit of 5 pg. When clinical samples were analyzed the positive reference sera and the PCR-positive products gave light emissions with values higher than background at 2 sigma level, while the negative samples gave a signal comparable to the background noise for all chemiluminescent reagents. The PS-3 reagent detected one more dilution (1/256) than ECL and RE (1/128) of positive reference sera.

DNA, Viral↗
PubMed1995

Application of a low-light imaging device and chemiluminescent substrates for quantitative detection of viral DNA in hybridization reactions.

In this quantitative dot-blot hybridization assay for detecting B19 parvovirus DNA, we used three different chemiluminescent substrates [adamantyl-1,2-dioxetane phenyl phosphates (PPD and the new PPD-Plus) and the chloro-5-substituted adamantyl-1,2-dioxetane phosphate (CSPD) plus Emerald enhancer] and a high-performance, low-intensity-light imaging luminograph apparatus. The hybridization test uses digoxigenin-labeled DNA probes, which are immunoenzymatically revealed by anti-digoxigenin Fab fragments conjugated with alkaline phosphatase. All the detection systems with the various chemiluminescent substrates gave sensitive and reproducible results for calibrators and positive or negative reference clinical samples, with high reproducibility (CV 4-17%). The signal was measured after 45 min of incubation. The luminograph apparatus could detect 10 fg of homologous DNA with the PPD-Plus substrate, whereas the detection limit with the CSPD and PPD substrates was 20 fg and 20-50 fg, respectively. Analysis of 26 samples with the three substrates showed good sensitivity and specificity for viral detection.

DNA, Viral↗
PubMed1991

Chemiluminescent assay for the detection of viral and plasmid DNA using digoxigenin-labeled probes.

A dot-blot hybridization immunoenzymatic assay with a chemiluminescent endpoint was developed for the rapid and sensitive detection of viral and plasmid DNAs. Digoxigenin-labeled probes were used to detect cytomegalovirus, parvovirus B19, and plasmid pBR328 DNAs. Hybridized probes were immunoenzymatically visualized by anti-digoxigenin Fab fragments labeled with alkaline phosphatase, and adamantyl 1,2-dioxetane phenyl phosphate was used as chemiluminescent substrate. Results were recorded by instant photographic films. The chemiluminescent hybridization assay was performed in about 8 hr and was able to detect as little as 50-10 fg of homologous target DNA.

Cytomegalovirus↗
PubMed1991

Methodological problems of direct bioluminescent ADP assay in platelets and erythrocytes.

We have developed a method for ADP bioluminescent measurement in platelets and erythrocytes which complements our previous method for ATP assay. When the different parameters of the system under investigation are taken into account, a linea range between 10(-9) and 10(-7) g/ml can be obtained without incubation or troublesome extraction. This makes the method easy and useful for identifying any disease-induced alterations in ATP and/or ADP levels in these blood cells. The data obtained correlate well with those of a bioluminescent method requiring extraction with ethanol/EDTA and incubation, giving the reference intervals of 3.5-5.5 mumol/10(11) PLT for ATP determination and 1.9-3.7 mumol/10(11) PLT for ADP determination in platelets, and 3.2-3.8 mumol/g Hgb for ATP determination and 0.56-0.73 mumol/g Hgb for ADP in erythrocytes. This assay was applied to quality control on blood bags in transfusion centers and proved to be a rapid and reliable method for testing the viability of stored blood cells.

Adenosine Diphosphate↗
PubMed1991

Microdialysis and luminescent probe: analytical and clinical aspects.

Immobilized enzymes are widely used in the clinical laboratory to assay several analytes and enzymes. The use of immobilized enzymes makes these reagents recoverable, disposable and in most cases increases their stability and catalytic activity. In conjunction with bioluminescent enzymes (firefly and bacterial luciferases) and chemiluminescent catalyst (peroxidase) we set up high-sensitive flow sensors based on the use of nylon tube coil or epoxy methacrylate column as solid support. For in-vivo determination a suitable microdialysis probe inserted directly into brain or blood allows continuous measurement of extracellular lactate levels by means of a bioluminescent flow detector system. This procedure performs more measurements in the same time interval than other systems (HPLC), e.g. to give a detailed description of the effects of ischemia, or other pathological events, on lactate concentration in the brain.

Animals↗
PubMed1991

Chemiluminescence dot blot hybridization assay for detection of B19 parvovirus DNA in human sera.

A chemiluminescence dot blot hybridization assay was used for the detection of B19 parvovirus DNA in human sera by using digoxigenin-labeled probes. The probes were revealed immunoenzymatically by use of anti-digoxigenin Fab fragments conjugated with alkaline phosphatase. The chemiluminescence signal was obtained by reacting the labeled probe-target complex with an enzyme-triggerable dioxetane substrate. The emitted photons were detected with instant photographic films. In the search for B19 parvovirus DNA, 2,808 serum samples were analyzed.

DNA Probes↗
PubMed1990

Bioluminescent flow sensor for the determination of L-(+)-lactate.

The amount of L-lactate in biological fluids (serum, plasma and cerebrospinal fluid) was determined by monitoring the reduced form of nicotinamide adenine dinucleotide (NADH) produced by immobilised lactate dehydrogenase (LDH), with bacterial bioluminescent enzymes immobilised on a separate nylon coil. The LDH catalysed the reaction of L-lactate with NAD; this reaction took place in a nylon coil that preceded the coil for the bioluminescent detection. The co-immobilisation of alanine aminotransferase (ALT) with LDH improved the lactate transformation by 117-183%. The response was linear from 0.1 to 50 micron mol l(-1) at 25 degrees C for the LDH - ALT reactor. The intra- and inter-assay coefficients of variation were less than 5% and the recoveries ranged from 93 to 106%. The results agreed well with those obtained with a spectrophotometric method and with the normal reference values.

Alanine Transaminase↗
PubMed1989

Coupled reactions for the determination of analytes and enzymes based on the use of luminescence.

Immobilized enzymes are widely used in the clinical laboratory in the assay of several analytes and enzymes. The use of immobilized enzymes makes these reagents recoverable and re-usable, and in most cases increases their stability and catalytic activity. In conjunction with bioluminescent enzymes (firefly and bacterial luciferases) and chemiluminescent catalyst (peroxidase) we set up high-sensitive flow methods based on the use of nylon tube coil or epoxy methacrylate column as solid support. All the NAD(P)/NAD(P)H-dependent dehydrogenases (bacterial luciferase), ATP-dependent enzymes (firefly luciferase) and oxidases producing H2O2 (peroxidase) can be immobilized and a large variety of analytes have been sensitively measured. As an alternative format we also reported a dry chemistry method in which all the enzymes, substrates and cofactors are ready to use, supported on dry cellulose disks. Methodological problems such as flow conditions, stability, pH, ionic strength and analytical performances are also reported.

Animals↗