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Biomedical subjects

R Barbieri

Publications and source records attributed to R Barbieri.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of genotoxic effects in human peripheral blood leukocytes following an acute in vitro exposure to 900 MHz radiofrequency fields.

Human peripheral blood leukocytes from healthy volunteers have been employed to investigate the induction of genotoxic effects following 2 h exposure to 900 MHz radiofrequency radiation. The GSM signal has been studied at specific absorption rates (SAR) of 0.3 and 1 W/kg. The exposures were carried out in a waveguide system under strictly controlled conditions of both dosimetry and temperature. The same temperature conditions (37.0 +/- 0.1 degrees C) were realized in a second waveguide, employed to perform sham exposures. The induction of DNA damage was evaluated in leukocytes by applying the alkaline single cell gel electrophoresis (SCGE)/comet assay, while structural chromosome aberrations and sister chromatid exchanges were evaluated in lymphocytes stimulated with phytohemagglutinin. Alterations in kinetics of cell proliferation were determined by calculating the mitotic index. Positive controls were also provided by using methyl methanesulfonate (MMS) for comet assay and mitomycin-C (MMC), for chromosome aberration, or sister chromatid exchange tests. No statistically significant differences were detected in exposed samples in comparison with sham exposed ones for all the parameters investigated. On the contrary, the positive controls gave a statistically significant increase in DNA damage in all cases, as expected. Thus the results obtained in our experimental conditions do not support the hypothesis that 900 MHz radiofrequency field exposure induces DNA damage in human peripheral blood leukocytes in this range of SAR.

Cell Phone↗
PubMed2004

Changes in cardiovascular function during the sleep onset period in young adults.

Blood pressure (BP) and heart rate (HR) are influenced by the sleep-wake cycle, with relatively abrupt falls occurring in association with sleep onset (SO). However, the pattern and rate of fall in BP and HR during SO and the processes that contribute to the fall in these variables have not been fully identified. Continuous BP and HR recordings were collected beginning 1 h before lights out (LO) until the end of the first non-rapid eye movement sleep period in 21 young, healthy participants maintained in a supine position. Five consecutive phases were defined: 1) the 30 min of wakefulness before LO; 2) LO to stage 1 sleep; 3) stage 1 to stage 2 sleep; 4) stage 2 sleep to the last microarousal before stable sleep; and 5) the first 30 min of undisturbed stable sleep. The data were analyzed on a beat-by-beat basis and reported as 2-min periods for phases 1 and 5 and 10% epochs for phases 2, 3, and 4 (as participants had variable time periods in these phases). The level of baroreflex (BR) activity was assessed by the sequence technique and an autoregressive multivariate model. Furthermore, during phases 3 and 4, the BP and HR responses to arousal from sleep were determined. There were substantial falls in BP and HR after LO before the initial onset of theta;-activity (phase 3) and again after the onset of stable sleep after the cessation of spontaneous arousals. During phases 3 and 4 when there were repeated arousals from sleep, the fall in both variables was retarded. Furthermore, both the rate and magnitude of the fall in BP were negatively associated with the number of arousals during phases 3 and 4. There was a small increase in the sensitivity of the BR and indirect evidence of a substantial fall in its set point.

Adaptation, Physiological↗
PubMed2004

Ochratoxin A and zearalenone: a comparative study on genotoxic effects and cell death induced in bovine lymphocytes.

Ochratoxin A (OTA) and zearalenone (ZEA), two naturally occurring contaminants of animal feed, have been implicated in several mycotoxicoses in farm livestock but there is little information on their genotoxicity and toxicity in these species. Therefore, we investigated on the cytogenetic and cytotoxic effects of both OTA and ZEA in in vitro cultures of bovine lymphocytes. We determined chromosome aberrations (CAs) and sister chromatid exchanges (SCEs) as well as the mitotic index (MI) and cell viability following OTA and ZEA treatment. This report is the first to provide evidence of a statistically significant increase of structural CAs and of SCEs/cell associated with a reduction of the MI in all OTA- and ZEA-treated bovine lymphocyte cultures and a clear reproducible reducing effect of OTA on cell viability mediated by enhanced apoptosis. OTA-induced programmed cell death was not limited to bovine lymphocytes, as comparable data were demonstrated in the human leukemic T-cell line Jurkat.

Animals↗
PubMed2002

Coordination properties of adenosine-5'-monophosphate and related ligands towards Me2Sn(IV)2+ in aqueous solution.

The coordination of Me2Sn(IV)2+ to adenosine-5'-monophosphate (AMP) and the related compounds D-ribose-5-phosphate (R5P), D-glucose-1-phosphate (G1P) and D-glucose-6-phosphate (G6P) in aqueous solution was investigated by means of potentiometric titration, and 1H-, 31P-NMR and Mössbauer spectroscopic methods in the pH range 2-11 (I=0.1 M NaClO4, 298 K). The complex of AMP and Me2Sn(IV)2+ precipitated at low pH was characterised by elemental analysis, FT-IR and Mössbauer spectroscopic methods. From a comparison of the pK values obtained in the presence and absence of metal ion and the stability constants for the different systems, the coordination of [N] is excluded, while bidentate coordination of the phosphate group is presumed. Mössbauer spectroscopic measurements recorded in the glassy state confirmed bidentate coordination of the phosphate and the formation of mixed hydroxo complexes in the weakly acidic, neutral and strongly basic pH range. With increasing pH, the phosphate groups were replaced by the deprotonated alcoholic [O] atoms of the sugar moiety. The solid complex proved to be tbp structure with bidentate phosphate coordination.

Adenosine Monophosphate↗
PubMed2002

Lack of amplification phenomena of ribosomal RNA genes in sea urchin.

Careful quantitative analyses by spot hybridization to homologous probes demonstrate that no rDNA amplification occurs during Paracentrotus lividus oogenesis. The same approach was used to measure the copy number of the genes involved in ribosome biogenesis. Surprisingly, differently from the organisms in which the lack of rDNA amplification phenomena was observed, a very low number of constitutive rDNA repeats was found in this organism.

Animals↗
PubMed2001

Construction and analysis of non-Poisson stimulus-response models of neural spiking activity.

A paradigm for constructing and analyzing non-Poisson stimulus-response models of neural spike train activity is presented. Inhomogeneous gamma (IG) and inverse Gaussian (IIG) probability models are constructed by generalizing the derivation of the inhomogeneous Poisson (IP) model from the exponential probability density. The resultant spike train models have Markov dependence. Quantile-quantile (Q-Q) plots and Kolmogorov-Smirnov (K-S) plots are developed based on the rate-rescaling theorem to assess model goodness-of-fit. The analysis also expresses the spike rate function of the neuron directly in terms of its interspike interval (ISI) distribution. The methods are illustrated with an analysis of 34 spike trains from rat CA1 hippocampal pyramidal neurons recorded while the animal executed a behavioral task. The stimulus in these experiments is the animal's position in its environment and the response is the neural spiking activity. For all 34 pyramidal cells, the IG and IIG models gave better fits to the spike trains than the IP. The IG model more accurately described the frequency of longer ISIs, whereas the IIG model gave the best description of the burst frequency, i.e. ISIs < or = 20 ms. The findings suggest that bursts are a significant component of place cell spiking activity even when position and the background variable, theta phase, are taken into account. Unlike the Poisson model, the spatial and temporal rate maps of the IG and IIG models depend directly on the spiking history of the neurons. These rate maps are more physiologically plausible since the interaction between space and time determines local spiking propensity. While this statistical paradigm is being developed to study information encoding by rat hippocampal neurons, the framework should be applicable to stimulus-response experiments performed in other neural systems.

Action Potentials↗
PubMed2001

Multiple voltage-gradient gel electrophoresis system.

A new device, based on the principle of voltage-gradient gel electrophoresis, was developed in order to enhance differentiation of the distance across the range of molecular masses in the electrophoretic fractionation of nucleic acids in an agarose matrix. The apparatus has a series of modular parallel plates, placed slantwise to allow reiteration of the voltage gradient effect along the gel. This subjects DNA fragments of variable length to differential runnings according to their original position in the gel. Both the number of slantwise plates and the distance between them can be changed to modify operating performance. Our system allows better fractionations as compared to conventional electrophoresis, since it forms gel areas in which distancing between the ranges of molecular masses is enhanced.

Bacteriophage lambda↗
PubMed2001

(2-Chlorobenzyl)tris(2-pyridinethiolato)tin(IV).

In the title compound, (2-chlorobenzyl)tris(pyridine-2-thiolato)-kappa(2)N,S;kappa2N,S;kappaS-tin(IV), [Sn(C7H6Cl)(C5H4NS)3], two of the three pyridine-2-thiolato ligands (SPy) are bidentate and one is monodentate. The bonding C atom of the 2-chlorobenzyl group, the S atom of the monodentate SPy and the S and N atoms of the two bidentate SPy ligands form a distorted octahedron around the Sn atom. The three S atoms and the N atom of one of the bidentate SPy ligands occupy the equatorial positions, while the N atom of the second bidentate SPy ligand and the C(CH2) atom are axial. The axial N-Sn-C angle of 157.9 (1) degree demonstrates the heavy distortion of the octahedron.

Journal Article↗
PubMed2000

Use of voltage gradient gel electrophoresis in apoptotic DNA analysis.

In this paper the use of voltage gradient gel electrophoresis (VGGE) in the electrophoretic analysis of apoptotic DNAs is described. The peculiarity of VGGE fractionation in enhancing DNA bands in the gel by reducing their thickness was used to obtain a rapid, more selective and higher-quality electrophoretic fractionation of apoptotic DNA with respect to conventional electrophoresis. The use of VGGE fractionations also allowed a reduced amount of DNA to be used to detect a characteristic apoptotic DNA ladder pattern, in a lower agarose gel concentration, with respect to conventional electrophoretic fractionation

Animals↗
PubMed2000

Global capitation at a women's health referral center: the challenge of patient selection.

Global risk capitation as a preferred payment method in heavily penetrated managed care markets poses important challenges for women's health care tertiary referral centers that employ participating primary care physicians. Global risk capitation agreements expose those centers to the adverse financial effects of high frequency of obstetric visits, costly infertility and neonatal care, and care of a disproportionate number of patients with complex, resource-intensive conditions.

Capitation Fee↗
PubMed2000

18S-28S rDNA is interspersed throughout heterochromatin in the millipede Enologus oxypygum (Diplopoda).

In the present study, somatic metaphase chromosomes of the millipede Enologus oxypygum (Diplopoda: Julida) were hybridized in situ with a sea urchin (Echinodermata) ribosomal probe (prR14) in order to map major RNA genes (rDNA). Chromosomal preparations were also silver stained (Ag-NOR) to evaluate the rDNA transcriptional activity. Our results indicate that RNA genes are throughout heterochromatin in eight chromosomes involving 1/4 of the total heterochromatin which, in this species, is about 67% of the total DNA. Ag-NOR and FISH patterns were not coincident.

Animals↗
PubMed1999

Effect of local anesthetic ropivacaine on isolated rat liver mitochondria.

Ropivacaine is a new long-acting aminoamide local anesthetic with a reduced systemic and cardiac toxicity. Since the latter seems to be related, at least partially, to an interference with mitochondrial energy transduction, the effect of ropivacaine on the metabolism of rat liver mitochondria was studied. Ropivacaine alone exhibited little effect on mitochondrial metabolism, whereas effects were strongly enhanced by tetraphenylboron (TPB-) anion. At low drug concentrations, state 4 respiration was stimulated and mitochondrial membrane potential collapsed. At higher concentrations, state 4 and uncoupled respiration were inhibited by impairment of electron transfer from NAD- and flavine adenine dinucleotide-linked substrates to the respiratory chain. The fact that TPB- increased drug effects indicated that stimulation of respiration was due to dissipation of the electrochemical proton gradient caused by its electrophoretic uptake, although a classical uncoupling mechanism cannot be excluded. The mechanism for the lower toxicity of ropivacaine in vivo was ascribed to low liposolubility leading to reduced access to the mitochondrial membrane, resulting in a minimal perturbation of mitochondrial metabolism.

Amides↗
PubMed1999

Modified apparatus for voltage gradient gel electrophoresis.

We built a modified version of voltage gradient gel electrophoresis system to correct distortions in nucleic acids electrophoretic migration patterns occurring at the edges of the gel when the original voltage gradient apparatus is used. The new device allows correct fractionation of nucleic acids also when electrophoresis is performed at high voltages.

Electrophoresis, Polyacrylamide Gel↗
PubMed1999

Ribosomal DNA location in the scarab beetle Thorectes intermedius (Costa) (Coleoptera: Geotrupidae) using banding and fluorescent in-situ hybridization.

Mitotic metaphase chromosomes of the scarab beetle Thorectes intermedius (Costa) (Coleoptera Scarabaeoidea: Geotrupidae) were analyzed using various banding methods and fluorescent in-situ hybridization (FISH) with a ribosomal probe. The results obtained indicate that silver and CMA3 staining are unable to localize the chromosome sites of nucleolar organizer regions (NORs). Such an inadequacy is a consequence of the extensive silver and CMA3 stainability of both constitutive heterochromatin and heterochromatin associated to the NORs.

Animals↗
PubMed1998

Genotoxicity and oxidative stress induced by pesticide exposure in bovine lymphocyte cultures in vitro.

The genotoxic activity of the pesticides gliphosate, vinclozolin and DPX-E9636 was studied in in vitro cultures of bovine lymphocytes, using chromosome aberration (CA) and sister chromatid exchange (SCE) frequencies as genetic end-points and a variation of glucose 6-phosphate dehydrogenase (G6PD) enzyme activity as a marker of changes in the normal cell redox state. Results indicated a statistically significant increase of structural aberrations, sister chromatid exchanges and G6PD activity, suggesting that the pesticides tested induce either oxidative stress or a mutagenic effect in this species. The evaluation of both mitotic index and cell viability, after pesticide exposure, demonstrates a high cytotoxic effect which is always associated with the observed genotoxic effect.

Animals↗
PubMed1998

Basal hormone levels in women who use acetaminophen for menstrual pain.

OBJECTIVE: To compare basal gonadotropin and estradiol levels between women using acetaminophen versus those using no or other types of analgesics. DESIGN: Observational study. SETTING: Three IVF clinics in greater Boston. PATIENT(S): Three hundred eighty-six women accepted for their first IVF treatment who completed questionnaires recording medical history, including analgesic use for menstrual pain, and who had blood drawn during the menstrual phase of a cycle before treatment. MAIN OUTCOME MEASURE(S): Basal FSH, LH, and estradiol. RESULT(S): Basal hormone levels, especially LH, were lower for women who regularly used acetaminophen compared with women who used no medication or other types of analgesics. Lower hormone levels in acetaminophen users were consistently observed when women were subdivided by age, body mass index, smoking history, and degree of menstrual pain-features that might have influenced analgesic use or hormone levels. CONCLUSION(S): This study provides preliminary evidence that acetaminophen may lower gonadotropin and estradiol levels and offers a biologic basis for the epidemiologic observation that acetaminophen use may reduce the risk of ovarian cancer.

Acetaminophen↗
PubMed1998

Effect of local anesthetic ropivacaine on the energy metabolism of Ehrlich ascites tumor cells.

The effect of local anesthetic ropivacaine on the energy metabolism of Ehrlich ascites tumor cells has been investigated. Ropivacaine impaired energy metabolism of Ehrlich ascites tumor cells by affecting primarily mitochondrial metabolism. Even at low concentrations ropivacaine decreased the rate of oxygen uptake, but its effect was remarkably higher on the uncoupled respiration and, in both cases, it was strongly enhanced by hydrophobic anion tetraphenylboron (TPB-). The decrease of oxygen uptake was ascribed to an impairment of electron transport from site 1- and 2-entering substrates to respiratory chain. The inhibition of respiration, coupled to a true uncoupling mechanism by an electrophoretic mechanism, impaired ADP phosphorylation, decreased ATP content, and collapsed mitochondrial membrane potential. Ropivacaine, at all concentrations tested, stimulated aerobic lactate production, and this increase, in addition to the inhibition of respiration, was also due to an activation of mitochondrial ATPase.

Adenosine Triphosphate↗