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Biomedical subjects

A Raffaelli

Publications and source records attributed to A Raffaelli.

At least 19 recordsLinked to original sources
PubMed2004

The Metabolic Syndrome is an independent predictor of cardiovascular disease in Type 2 diabetic subjects. Prospective data from the Verona Diabetes Complications Study.

AIMS: To evaluate the cardiovascular risk associated with the presence of the Metabolic Syndrome in Type 2 diabetic subjects. METHODS: Subjects with the Metabolic Syndrome, defined by WHO criteria, were identified in a large sample of non-insulin-treated Type 2 diabetic patients examined within the Verona Diabetes Complications Study (n = 946). At baseline and after a mean of 4.5 years follow-up, cardiovascular disease (CVD) was assessed by medical history, physical examination, electrocardiogram (ECG) and echo-duplex of carotid and lower limb arteries. Death certificates and medical records of subjects who died during the follow-up were scrutinized in order to identify CVD deaths. In statistical analyses, CVD was considered as an aggregate end-point, including fatal and non-fatal coronary, cerebrovascular and peripheral vascular disease as well as ischaemic ECG abnormalities and vascular lesions at the echo-duplex. RESULTS: The proportion of subjects with the Metabolic Syndrome was very high (92.3%). At the baseline, 31.7% of subjects were coded positive for CVD, which was more prevalent in subjects with the Metabolic Syndrome (32.9 vs. 17.8%, P = 0.005). Among subjects free of CVD at the baseline (n = 559), CVD events during the follow-up were significantly increased in patients with the Metabolic Syndrome as compared with those without it (19.9% vs. 3.9%, P < 0.001). Multiple logistic regression analysis showed that, along with sex, age, smoking and HbA1c, the presence of the Metabolic Syndrome independently predicted prevalent (OR 2.01, P = 0.045) and incident CVD (OR 4.89, P = 0.031). CONCLUSIONS: In Type 2 diabetes, the presence of the Metabolic Syndrome is associated with an almost 5-fold increase in CVD risk.

Aged↗
PubMed2002

Predictors of insulin sensitivity in Type 2 diabetes mellitus.

AIMS: To identify the independent predictors of insulin sensitivity in Type 2 diabetes, and to establish whether isolated Type 2 diabetes (i.e. diabetes without overweight, dyslipidaemia and hypertension) is a condition of insulin resistance. METHODS: We examined 45 patients with non-insulin-treated Type 2 diabetes undergoing a 4-h euglycaemic hyperinsulinaemic clamp (20 mU/m2 per min) combined with 3H-3-D-glucose and 14C-U-glucose infusions and indirect calorimetry. We also examined 1366 patients with non-insulin-treated Type 2 diabetes randomly selected among those attending the Diabetes Clinic and in whom insulin resistance was estimated by Homeostasis Model Assessment (HOMA-IR). RESULTS: In the 45 patients undergoing glucose clamp studies, insulin-mediated total glucose disposal (TGD) was independently and negatively associated with systolic blood pressure (standardized beta coefficient = -0.407, P = 0.003), plasma triglycerides (beta= -0.355, P = 0.007), and HbA1c (beta= -0.350, P = 0.008). The overall variability of TGD explained by these variables was 53%. Overweight diabetic subjects with central fat distribution, hypertension, hypertriglyceridaemia and poor glycometabolic control had insulin-mediated TGD values markedly lower than their lean counterparts without hypertension, with normal triglycerides, and with good glycometabolic control (16 +/- 5 vs. 31 +/- 10 micromol/min per kg lean body mass, P < 0.01). Nevertheless, the latter still were markedly insulin-resistant when compared with sex- and age-matched non-diabetic control subjects (31 +/- 10 vs. 54 +/- 13 micromol/min per kg lean body mass, P < 0.01). In the 1366 Type 2 diabetic patients of the epidemiological study, HOMA-IR value was independently associated with HbA1c (beta = 0.283, P < 0.0001), plasma triglycerides (beta = 0.246, P < 0.0001), body mass index (beta = 0.139, P < 0.001), waist girth (beta = 0.124, P < 0.001) and hypertension (beta = 0.066, P = 0.006). CONCLUSION: Overweight, central fat distribution, dyslipidaemia, hypertension and poor glycometabolic control are strong independent predictors of insulin resistance in Type 2 diabetes. However, reduced insulin sensitivity can be found even when Type 2 diabetes is isolated and well controlled.

Adult↗
PubMed2001

Binding properties of human albumin modified by covalent binding of penicillin.

Derivatisation of lysine residues in human albumin was performed in vitro by reaction with penicillin G. This modification reaction has been reported to occur in patients treated with high dosages of the antibiotic. The structure of the modified protein was characterised by mass spectrometry and circular dichroism. The number of the lysine residues involved depends on the time of incubation and on the drug/protein molar ratio. The secondary structure of the modified protein does not change significantly with respect to the native protein. Furthermore, the binding properties of the modified albumin were characterised by CD spectroscopy. Phenylbutazone, diazepam and bilirubin, known to bind to specific binding areas, were used as markers. A decrease of the affinity to the high-affinity binding sites was observed after the modification.

Albumins↗
PubMed2001

Determination of benzene at trace levels in air by a novel method based on solid-phase microextraction gas chromatography/mass spectrometry.

A new method for the determination of benzene at trace levels in air is presented. The method consists of the collection of air samples on adsorbent cartridges with simultaneous adsorption of pre-established amounts of D6-labeled internal standard. Desorption from the cartridge is performed by solid-phase microextraction (SPME) with analysis by gas chromatography/mass spectrometry (GC/MS) using an ion trap mass spectrometer. The influence of several parameters (type of SPME fiber, temperature, time, for example) was investigated, and good linearity in the range 10-400 ng of C6D6, with a coefficient of variance (CV) around 3-5%, was obtained. The method was tested by sampling air in a town center in Italy, and a benzene concentration of approximately 50 microg/m(3) was determined. The maximum limit recommended by the European Community is 10 microg/m(3).

Air Pollutants, Occupational↗
PubMed2000

Virtual freezing of the hemiacetal-aldehyde equilibrium of the aglycones of oleuropein and ligstroside present in olive oils from Carolea and Coratina cultivars by ionspray ionization tandem mass spectrometry

The composition of the equilibrium between aldehydes and hemiacetals was evaluated by ionspray ionization tandem mass spectrometry. The methanolic extracts of virgin olive oil from Carolea and Coratina cultivars contain a complex mixture of hydroxytyrosol (3) and tyrosol (4) derivatives (5, 6) characterized by the presence of aldehyde moieties in equilibrium with their hydrated form (8) or with the corresponding methanol hemiacetals 9 and 10. The equilibrium was frozen by droplet evaporation, thus allowing the structure determination of each component. The formation of the decarboxylated species 11-14, reported previously, was not observed.

Journal Article↗
PubMed2000

Identification and characterization of fenton oxidation products of surfactants by electrospray mass spectrometry and by solid phase microextraction gas chromatography mass spectrometry. 2. Fatty alcohol polyethoxy sulphates

The Fenton reaction for the degradation of surfactants has been investigated and partial degradation products have been identified and characterized by mass spectrometry for the case of fatty alcohol polyethoxy sulphates. The polar water-soluble products were investigated by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI), and the volatile products leaving the mixture during the reaction were trapped by means of solid phase microextraction (SPME) and investigated by gas chromatography/mass spectrometry (GC/MS) with electron and chemical ionization. The oxidation leads to the formation of products with hydroxyl and epoxide groups due to insertion of oxygen atoms or with terminal ethoxylic moieties deriving from the loss of the hydrophilic sulphate group. The formation of volatile aldehydes is also observed, corresponding to the fragmentation between hydrocarbon and ethoxylic chains. The extent of mineralization is dependent on peroxide and iron(II) concentrations. Copyright 2000 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Investigation on the iodination reaction of methylene blue by liquid chromatography-mass spectrometry with ionspray ionisation.

Radioactive iodine (131I and 123I) labelled methylene blue is used for the early diagnosis of melanoma metastases. We studied the iodination reaction of methylene blue (using "cold" iodine) in order to characterise the iodination product(s) as far as number and position of iodine atoms introduced on the aromatic ring(s) is concerned. The reaction was carried out under the same experimental conditions used for the radioactive one, that is in a large excess of methylene blue. The ionspray HPLC-MS analysis of the reaction mixture showed that the iodinated methylene blue was present only in a very small amount and the main iodinated product was a demethylated one, coming out from the iodination of an impurity azure B. We also studied the iodination reaction of azure B in order to better explain the reaction pathway. Commercial azure B contains impurities of methylene blue and all the possible demethylated derivatives. HPLC-MS analysis of the reaction mixture allowed a complete characterisation of the iodinated and bis-iodinated products.

Chromatography, High Pressure Liquid↗
PubMed1999

A simple method for the extraction of volatile organic compounds contained in air samples from adsorbent materials by solid phase microextraction and their analysis by gas chromatography/mass spectrometry.

The monitoring of air pollution requires simple, rapid and sensitive sampling and analytical techniques with minimal sample manipulation that are usable for routine analyses. In our laboratories we have developed a method for the analysis of air samples collected by adsorbent cartridges based on solid phase microextraction (SPME) coupled to gas chromatography/mass spectrometry. We investigated the influence of some variables (time and temperature) using toluene as analyte (one of the most common air pollutants) and toluene-d(8) on the SPME extraction, and the sensitivity (LOQ) of the method. We then tested the method on an air sample collected in an industrial area and carried out characterisation of the volatile organic compounds present.

Adsorption↗
PubMed1999

Identification and characterization of fenton oxidation products of surfactants by ionspray mass spectrometry and solid-phase microextraction gas chromatography mass spectrometry 1. Lauryl sulphate

The Fenton reaction for the degradation of surfactants has been investigated and partial degradation products have been identified and characterized by mass spectrometry for the case of lauryl sulphate. The polar soluble products were investigated by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI), and the volatile products leaving the mixture during the reaction were trapped by means of solid-phase microextraction (SPME) and investigated by gas chromatography/mass spectrometry (GC/MS) with electron and chemical ionization. The oxidation leads to the formation of products with hydroxyl and epoxide groups due to insertion of oxygen atoms or to aldehydes derived from the loss of the hydrophilic sulphate group. The extent of mineralization is dependent on peroxide and iron concentrations. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Quantitation of oleuropein in virgin olive oil by ionspray mass spectrometry-selected reaction monitoring.

This work describes the unambiguous evaluation of the presence of oleuropein in virgin olive oils by ionspray tandem mass spectrometry (ISI-MS/MS). The oil samples obtained from different cultivars, such as Carolea, Cassanese, Coratina, Dolce di Rossano, Roggianella, and Tonda di Strongoli, grown in different geographical areas of Calabria, Italy, have shown an average content of oleuropein ranging from 1 ppb to 11 ppm. Commercial virgin oil samples, blended in some cases, contain significant amounts of this pharmacologically important antioxidant. The MS/MS methodology was applied in a triple-quadrupole instrument, through continuous scanning of the third analyzer to detect oleuropein in methanol extracts and in selected ion monitoring (SRM) for its quantitative assay.

Free Radical Scavengers↗
PubMed1998

Characterization of psoralen-oleic acid cycloadducts and their possible involvement in membrane photodamage.

By UVA irradiation of an ethanol solution of psoralen and oleic acid, four main photoproducts have been isolated and characterized: two have cis,cis structure; the other two are trans,cis. The same adducts have been isolated from the photoreaction of psoralen with beta-oleoyl-gamma-stearoyl-1-alpha-phosphatidylcholine followed by enzymatic hydrolysis with phospholipase A2. The four isomers stimulate protein kinase C to almost the same extent.

Blood Platelets↗
PubMed1998

Chemical modification of human albumin at cys34 by ethacrynic acid: structural characterisation and binding properties.

Derivatization of the free cys3,4 in human albumin, which is reported to occur under physiological conditions, has been performed in vitro by reaction of the protein with ethacrynic acid. This modification has been investigated by mass spectrometry and circular dichroism. Ethacrynic acid has been proven to bind human albumin either covalently and non-covalently. This post-translational modification does not determine significant changes in the secondary structure of the protein, as shown by the comparable circular dichroism spectra of the native and the modified proteins. Furthermore, the binding properties of the human albumin samples have been investigated by circular dichroism and equilibrium dialysis. The affinity to the higher affinity binding sites does not change either for drugs binding to site I, like phenylbutazone, or to site II, like diazepam, while a small but significant increase has been observed for bilirubin, known to bind to site III. Nevertheless significant decreases of the affinity at the lower affinity binding sites of the modified protein were observed for both drugs binding to site I or to site II.

Albumins↗
PubMed1997

Secondary structure and Ca2+-induced conformational change of calexcitin, a learning-associated protein.

Calexcitin/cp20 is a low molecular weight GTP- and Ca2+-binding protein, which is phosphorylated by protein kinase C during associative learning, and reproduces many of the cellular effects of learning, such as the reduction of potassium currents in neurons. Here, the secondary structure of cloned squid calexcitin was determined by circular dichroism in aqueous solution and by Fourier transform infrared spectroscopy both in solution and on dried films. The results obtained with the two techniques are in agreement with each other and coincide with the secondary structure computed from the amino acid sequence. In solution, calexcitin is one-third in alpha-helix and one-fifth in beta-sheet. The conformation of the protein in solid state depends on the concentration of the starting solution, suggesting the occurrence of surface aggregation. The secondary structure also depends on the binding of calcium, which causes an increase in alpha-helix and a decrease in beta-sheet, as estimated by circular dichroism. The conformation of calexcitin is independent of ionic strength, and the calcium-induced structural transition is slightly inhibited by Mg2+ and low pH, while favored by high pH. The switch of calexcitin's secondary structure upon calcium binding, which was confirmed by intrinsic fluorescence spectroscopy and nondenaturing gel electrophoresis, is reversible and occurs in a physiologically meaningful range of Ca2+ concentration. The calcium-bound form is more globular than the apoprotein. Unlike other EF-hand proteins, calexcitin's overall lipophilicity is not affected by calcium binding, as assessed by hydrophobic liquid chromatography. Preliminary results from patch-clamp experiments indicated that calcium is necessary for calexcitin to inhibit potassium channels and thus to increase membrane excitability. Therefore the calcium-dependent conformational equilibrium of calexcitin could serve as a molecular switch for the short term modulation of neuronal activity following associative conditioning.

Amino Acid Sequence↗
PubMed1997

Non-covalent complexes between DNA-binding drugs and double-stranded deoxyoligonucleotides: a study by ionspray mass spectrometry.

The non-covalent complexes between some DNA-binding drugs and duplex oligodeoxynucleotides were studied by ionspray mass spectrometry, with the aim of evaluating the suitability of this technique to screen rapidly a series of drugs exerting their activity through non-covalent binding to specific base sequences of DNA. Two classes of drugs were considered, distamycins (which show affinity for the minor groove of DNA) and anthracyclines (which interact through intercalation between bases). For the former, d(CGCGAATTCGCG)2 was chosen as the model oligodeoxynucleotide. Following optimization of sample preparation and instrumental conditions, the complexes of different distamycins were observed; depending on the ligand considered, 1:1 or 2:1 complexes were formed preferentially. A semi-quantitative evaluation of the relative affinities was made by measuring the ratio of the complexes signals to those of the duplex, and also by competitive binding with equimolar amounts of distamycin. For anthracyclines, the daunorubicin-d(CGATCG)2 complex was chosen as the model for a preliminary mass spectrometric study; however, the signals of the duplex and the complex were very low compared with the monomer signal. Since the complex was known to be stable in solution, this was ascribed to gas-phase instability, probably caused by electrostatic repulsion between negatively charged phosphate groups.

Anti-Bacterial Agents↗
PubMed1994

Revealing the mammalian lignan precursor secoisolariciresinol diglucoside in flax seed by ionspray mass spectrometry.

Ionspray mass spectrometry allowed the rapid detection and unambiguous identification of secoisolariciresinol diglucoside, an important mammalian lignan precursor occurring in flax seed. It was observed that this compound is embedded in a complex form, probably a complex glucoside of still undisclosed structure, among the polar solvent extractables of flax seed from which it could not be released as such without the intervention of alkaline methanolysis. Comparison of ionspray mass spectra of untreated and methanolysed flax-seed extracts confirmed methanolysis as the crucial step in setting up any further analytical or preparative procedure concerned with secoisolariciresinol diglucoside.

Butylene Glycols↗
PubMed1994

Investigation of mammalian lignan precursors in flax seed: first evidence of secoisolariciresinol diglucoside in two isomeric forms by liquid chromatograph/mass spectrometry.

A strong research effort has been devoted in recent years to the mammalian lignans enterolactone and enterodiol because of their claimed protective effects against breast and colon cancer. Some plant lignans appear to be precursors of these molecules. This paper reports a novel identification procedure for one of these precursors, the secoisolariciresinol diglucoside, in the extracts of defatted flax-seed meal. The procedure is based on high-performance liquid chromatography coupled with either ionspray or continuous-flow fast-atom bombardment mass spectrometry. The application of these techniques allowed the identification in flax seed of two isomeric forms of this precursor for the first time. The isomers are reasonable the two diastereoisomers, due to the two equivalent stereogenic centers present in the molecule.

Butylene Glycols↗
PubMed1990

Injections of 6-hydroxydopamine in the substantia nigra of the rat brain: morphological and biochemical effects.

Rats with unilateral injections of 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta were classified as active and inactive according to the intensity of their spontaneous and/or apomorphine-induced turning behavior (TB), and sacrificed at different survival times for morphological and biochemical analysis. In active rats, at any survival time, dopaminergic fluorescence in the nigrostriatal system as well as dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) content of the nucleus caudatus-putamen drastically decreased on the brain side ipsilateral to the injection. Dopaminergic fluorescence as well as DA and DOPAC content of the mesolimbic system ipsilateral to the injection also decreased. In inactive rats, at any survival time, 6-OHDA-induced lesions only partially involved both nigrostriatal and mesolimbic systems. Our results are indicative of a good correlation between the intensity of TB and the extent of 6-OHDA-induced lesions, as assessed by morphological and biochemical analysis.

3,4-Dihydroxyphenylacetic Acid↗