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R Barbieri

Publications and source records attributed to R Barbieri.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cytogenetic damage and induction of pro-oxidant state in human lymphocytes exposed in vitro to gliphosate, vinclozolin, atrazine, and DPX-E9636.

We analyzed chromosome aberrations (CAs), sister chromatid exchanges (SCEs), mitotic index (MI), and glucose 6-phosphate dehydrogenase (G6PD) enzyme activity in human peripheral lymphocytes from three healthy donors exposed in vitro to different concentrations of gliphosate, vinclozolin, atrazine, and DPX-E9636. The pesticides gliphosate, vinclozolin, and atrazine have been studied in a broad range of genetic tests with predominantly conflicting or negative results, whereas little is known about the genotoxicity of DPX-E9636. In our experimental conditions, each chemical compound tested produced a dose-related increase in the percent of aberrant cells and an increase of SCE/cell. Furthermore, at the highest concentrations of vinclozolin, atrazine, and DPX-E9636, we observed a significant reduction of the mitotic index. The increase of G6PD activity in exposed lymphocyte cultures strongly indicated an induction of a pro-oxidant state of the cells as an initial response to pesticide exposure.

Atrazine↗
PubMed1997

A multivariate time-variant AR method for the analysis of heart rate and arterial blood pressure.

This paper approaches the problem of short-term mechanisms that regulate heart rate and blood pressure variability signals, by focusing the evident changes of their frequency content during transients (dynamic situations in which the behaviour of these control mechanisms may vary on a beat-to-beat basis). In this study, we suggest an autoregressive time-variant spectral estimation method, which is able to follow such dynamic changes in the signals. This method has also been extended to a multivariate approach in order to take into account more than one process at a time, and to assess the mutual influences between the different controlling systems. The algorithms successfully tested on simulated series have also been used to analyse series recorded during a vaso-vagal syncope episode in a tilt manoeuvre and a physical exercise stress test protocol. The results show how this method is able to follow the changing dynamics of the signals on the basis of a closed-loop model of their interaction on a beat-to-beat basis. After a proper identification procedure of the blocks forming the model, it is possible, therefore, to obtain the classical spectral parameters and the gain of the transfer function between the signals. Such parameters constitute new time series that describe the physiopathology of the cardiovascular control systems, even during non-stationary epochs.

Algorithms↗
PubMed1997

High heterochromatin content in somatic chromosomes of two unrelated species of Diplopoda (Myriapoda).

For the first time, a conventional analysis of C-banded karyotypes was carried out in two distantly related diplopod species; this revealed an impressive percentage of heterochromatin in both genomes. In Acanthopetalum sicanum (Order Callipodida) (2n = 12), heterochromatin constitutes about 60% of the total DNA in females and 56% in males, whereas in Enologus oxypygum (Order Julida) (2n = 22) it is about 67% in both sexes. Heterochromatin of the two species was found to be similar in base composition (AT rich) and heterochromatin distribution, indicating that it has accumulated in a species-specific manner. Sex-determining mechanisms of the XY type were detected in both A. sicanum and E. oxypygum. In A. sicanum, the Y presented the lowest heterochromatic content of all chromosomes in the karyotype, whereas the X presented the highest.

Animals↗
PubMed1997

Multivariate time-variant identification of cardiovascular variability signals: a beat-to-beat spectral parameter estimation in vasovagal syncope.

In this paper a bivariate, time-variant model able to continuously measure the mutual interactions between heart rate and systolic blood pressure variability signals is presented. A recursive identification of the model parameters makes it possible to estimate, on a beat-to-beat basis, spectral low-frequency (LF) and high-frequency (HF) power, (LF/HF ratio) and cross-spectral (coherence and phase relationships between spectral peaks) indexes during nonstationary events. These indexes can be helpful in: 1) physiological study of autonomic nervous system mechanisms of cardiovascular control and 2) quantification and clinical evaluation of the neural and mechanical links between the two signals. In addition, an estimate of baroreceptive activation (alpha-gain) is continuously extracted. Before applying the model to cardiovascular signals, the reliability of the estimated parameters was tested on simulated signals. Subsequently, the model was applied to investigating vasovagal syncope episodes, aiming at the assessment of autonomic nervous system status and autonomic role in the dynamic phenomena which lead to syncope. The proposed model, which provides noninvasive beat-to-beat evaluation of the autonomic events, may be useful in the description of the syncopal episodes and in the comprehension of the complex physiological mechanisms of syncope.

Algorithms↗
PubMed1996

Hybrid external fixation in the treatment of tibial plafond fractures.

From 1992 to 1994, 37 fractures (36 patients) were treated with hybrid external fixation for tibial plafond or distal tibial fractures. The fractures were classified according to the AO classification: A1 (3), A2 (3), A3 (4), C1 (6), C2 (12), C3 (9). There were 11 open injuries, and in 27 patients (75%) the mechanism of injury was high energy trauma. Results were evaluated based on a subjective and objective rating system. Thirty-four patients were available for followup at an average of 15.2 months. All fractures in this series united with an average time to healing of 4.6 months. Anatomic or good alignment was obtained in all but 1 fracture. There were 12 excellent, 9 good, 7 fair, and 6 poor results. In the 18 C2 and C3 fractures there were 8 good to excellent, 4 fair, and 6 poor results. Degenerative changes were seen on followup radiographs in 4 of these patients. Complications occurred in 12 patients (35%) and included 1 skin slough, 5 pin tract infections, 3 deep infections, 3 nonunions, and 3 loss of reductions necessitating frame revision. This method yielded results comparable with previous studies while decreasing the number of complications resulting from treatment.

Adolescent↗
PubMed1995

Cross-sectional and case-controlled analyses of the association between smoking and early menopause.

To examine potential confounders and dose-response data for the association between smoking and menopause, we used both a cross-sectional and case-controlled approach. In total, 10,606 middle-aged women residing in eastern Massachusetts were surveyed about their age at menopause and smoking history; 344 women (cases) with natural menopause prior to age 47 and 344 age-matched women (controls) who were still menstruating or who had a menopause after age 46 were selected for further study. Risk for menopause was assessed by Kaplan-Meier, Cox proportional hazards, or logistic regression models. From cross-sectional data on 8657 women aged 45-54, the hazards odds ratio for a natural menopause among women who ever smoked compared to non-smokers was 1.31 (95% C.L. 1.21-1.42) and among women who had accumulated 30 or more pack-years was 1.87 (95% C.L. 1.67-2.04) after adjustment for parity and weight. An additional potential confounder from the case-controlled study was lower educational attainment, and after adjustment for this variable, significant trends persisted for risk of early menopause associated with age began smoking (P = 0.03), years of smoking (P = 0.01) and pack-years of smoking (P = 0.03). This study demonstrates an association between smoking and early menopause in both cross-sectional and case-controlled data that is not confounded by parity, weight, socio-economic status, or nutritional variables.

Adult↗
PubMed1995

Insulin response of women athletes in relation to body fat quantified by magnetic resonance imaging.

We report the glucose and insulin response to a 300-min glucose tolerance test among 17 women athletes as compared with 11 normal, nonatheletic controls. Also reported is the relationship of the insulin area under the curve as a function of percentages of total fat (TF), subcutaneous fat, and internal fat of total volume (TV) quantified by magnetic resonance imaging overall and at six regional sites. Athletes had a more sensitive insulin response to the glucose tolerance test as compared with controls. The insulin area under the curve of athletes and controls was significantly (p = 0.05) related to their overall TF/TV%; athletes had significantly less TF/TV% compared with the controls.

Adipose Tissue↗
PubMed1994

Rhein enhances the effect of adriamycin on mitochondrial respiration by increasing antibiotic-membrane interaction.

The effect of the combination of Adriamycin (ADM) with rhein (RH), an anti-inflammatory drug, on the electron flow through site III and IV of the respiratory chain of rat liver mitochondria was investigated. RH, even at high concentrations, does not inhibit either duroquinol (DHQ) oxidation or cytochrome oxidase activity both of which are decreased by ADM in a dose-dependent manner. The analysis of interaction, performed with the isobolar method, shows a strong synergistic effect that cannot be ascribed to increased permeability of the mitochondrial membranes brought about by RH. The mechanism by which RH potentiates the effect of ADM on DHQ oxidation and cytochrome oxidase activity is most likely to be changes induced in the physical status of the inner mitochondrial membrane such as to permit low ADM concentrations to bind and segregate enough cardiolipin to inhibit electron transport through complex III and IV.

Animals↗
PubMed1994

Corticotrophin releasing hormone levels in human plasma and amniotic fluid during gestation.

OBJECTIVE: Corticotrophin releasing hormone, a hypothalamic neuropeptide also made in placenta, may regulate fetal maturation in a stress-responsive manner. The objectives of this study were: (1) to determine if levels of corticotrophin releasing hormone in the amniotic fluid correlate with fetal lung maturation; (2) to confirm that third trimester plasma levels of corticotrophin releasing hormone are increased in patients with pregnancy-induced hypertension compared to normotensives, and (3) to increase the recovery of extracted corticotrophin releasing hormone from plasma and amniotic fluid. DESIGN: (1) Levels of corticotrophin releasing hormone in amniotic fluid during the third trimester were compared with those of saturated phosphatidyl choline. (2) Corticotrophin releasing hormone levels were measured in a group of normotensive pregnant women during the entire gestation period. Corticotrophin releasing hormone levels during the third trimester were compared in normotensives and patients with pregnancy-induced hypertension. PATIENTS: Twenty-one non-pregnant normal volunteers and 63 pregnant women. MEASUREMENTS: Blood pressure, corticotrophin releasing hormone in plasma and amniotic fluid, and saturated phosphatidyl choline in amniotic fluid. RESULTS: Corticotrophin releasing hormone levels in amniotic fluid samples during the third trimester ranged from 12 to 98 pmol/l and positively correlated with the saturated phosphatidyl choline levels, but not with gestational age. A significant difference existed in plasma corticotrophin releasing hormone concentration between gestational age-matched third trimester normotensive and hypertensive gravids: corticotrophin releasing hormone levels were significantly lower in normotensives (223 +/- 65 pmol/l) than in patients with pregnancy-induced hypertension (544 +/- 106 pmol/l, P = 0.001). Plasma corticotrophin releasing hormone increased with gestational age from 51 pmol/l (range 8.4-85) at 25-32 weeks to 375 pmol/l (range 35-1386) at 33-40 weeks. During the third trimester the rise in plasma corticotrophin releasing hormone conformed to an exponential mathematical model of a positive feedback loop between placental corticotrophin releasing hormone and fetal adrenal cortisol. CONCLUSIONS: During the third trimester of pregnancy there is a positive correlation between the level of amniotic fluid corticotrophin releasing hormone and that of saturated phosphatidyl choline. The positive correlation between amniotic fluid corticotrophin releasing hormone and saturated phosphatidyl choline, but not between amniotic fluid corticotrophin releasing hormone and gestational age, suggests that a factor(s), such as stress, may affect both amniotic fluid corticotrophin releasing hormone and saturated phosphatidyl choline in parallel. Furthermore, our data are consistent with the hypothesis that the rise in placental corticotrophin releasing hormone is coupled to an increase in fetal glucocorticoid and lung maturation, and that stresses such as pregnancy-induced hypertension may accelerate this process.

Amniotic Fluid↗
PubMed1994

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

The effect of the local anesthetic bupivacaine on the energy metabolism of Ehrlich ascites tumor cells has been investigated. Even at low concentrations, bupivacaine decreased the oxygen uptake rate, but its effect was remarkably higher on the uncoupled respiration. Experiments on specific segments of the respiratory chain have shown that bupivacaine did not inhibit electron transport from Q to oxygen. Spectroscopic evidences demonstrated a NAD(P)H oxidation in bupivacaine-treated cells respiring on endogenous substrates, indicating that the inhibition of oxygen depended on a reduced electron transport from site 1-entering substrates to respiratory chain. The aerobic glycolysis was stimulated by low and inhibited by high bupivacaine concentrations. The increased lactate production rate was due to an activation of mitochondrial ATPase, whereas its decrease was related to an inhibition of the hexokinase activity.

Adenosine Triphosphate↗
PubMed1993

Methods for recovering nucleic acid fragments from agarose gels.

Agarose gel electrophoresis is a powerful technique for the separation of nucleic acids on the basis of their size and conformation. The development of methods to recover size-fractionated nucleic acids molecules from agarose gels has greatly facilitated recombinant DNA technologies. Although several methods for recovering DNA and RNA molecules have been developed during the past fifteen years, none of them has been universally accepted. In this review we describe, discuss and evaluate the most common procedures with which we have had experience. Our evaluation is based on the criteria of yield, purity, speed, simplicity and low cost. We have considered three different approaches to the problem of recovering nucleic acids: chemical gel dissolution, physical gel disruption and physical extrusion from intact gels.

Animals↗
PubMed1993

Voltage gradient electrophoresis of nucleic acids on agarose gels.

A very simple method is described which allows the separation of DNA molecules in a wide molecular weight range (from 0.6 to about 30 kb) in the same electrophoresis agarose gel. This is based on the achievement of a voltage gradient through a simple device consisting of a Plexiglas plate placed slantwise with respect to the gel surface plane, submerged in the electrophoretic running buffer. Further applications of our system are also described.

DNA↗
PubMed1993

Sequence analysis of the rDNA spacer of Paracentrotus lividus and observations about pre-rRNA processing. NTS sequence of Paracentrotus lividus rDNA.

We have isolated and sequenced one intergenic region and a small part of the flanking regions (18S and 26S rRNA coding regions) of the rRNA-encoding genes (rDNA) from the sea urchin Paracentrotus lividus. This region is about 3.8 Kb long. Northern blot hybridizations and S1 mapping experiments demonstrated the presence of a partially processed 21S rRNA precursor while has the same 5' terminus as the 32S primary precursor, also in developmental stages characterized by a low rate of rRNA synthesis.

Animals↗
PubMed1993

Magnetic resonance imaging of overall and regional body fat, estrogen metabolism, and ovulation of athletes compared to controls.

The association of menstrual dysfunction of athletes with changes in body composition has been controversial, because most estimations of body fatness have been indirect. Using magnetic resonance imaging, we quantified the sc and internal fat over a specific volume from the fifth thoracic vertebra to femoral fat in the upper thigh and at 4 other anatomical landmarks of 17 athletes (13 oarswomen and 4 runners) compared to that in 11 nonathletic controls. The magnetic resonance imaging data were also analyzed for the athletes and controls in relation to ovulatory status, which was determined by assay of urinary pregnanediol glucuronide, and in relation to the extent of 2-hydroxylation of estradiol to a nonpotent metabolite, 2-hydroxyestrone, which was evaluated by radiometric analysis. We found that 1) the relative and absolute body fat values of the athletes were significantly less (P < 0.05) than those of the controls overall and at each of the six regional sites, although the body weights of the rowers were significantly heavier than those of the controls, and the runners did not differ from the controls; 2) the ratio of sc fat to internal fat was 80%:20% among both athletes and controls, even though the athletes had significantly less fat; 3) the extent of estradiol 2-hydroxylation was significantly (P = 0.005) inversely related to total fat as a percentage of the total volume and to sc fat as a percentage of the total volume (P = 0.004) overall and at each of the regional fat depots; 4) athletes with menstrual disorders had significantly decreased sc and internal fat overall and at all regional sites compared to controls; and 5) a subgroup of ovulatory rowers had an apparent increase or lack of decrease in internal fat at the level of vertebrae lumbar 4, sacral 1, and sacral 4, compared to controls, whereas their sc fat was decreased at these sites compared to that in controls. Changes in regional fat deposits of both sc and internal fat may be involved in the menstrual dysfunction of the athletes in addition to their decreased overall fatness. The body weight and body mass index of well trained athletes can be a misleading index of body composition.

Adipose Tissue↗
PubMed1992

Evidence for polynuclear aggregates of ferric daunomycin. A Mössbauer, EPR, X-ray absorption spectroscopy and magnetic susceptibility study.

The interaction of the antitumor agent daunomycin (DN) with ferric iron has been analysed by Mössbauer spectroscopy, EPR, extended X-ray absorption fine structure (EXAFS), and magnetic susceptibility measurements. In contrast to literature data, at millimolar iron and anthracycline concentrations no solitary Fe(DN)3 complexes are formed in appreciable amounts. The Mössbauer spectroscopic analysis revealed severe dependencies on temperature, on the preparation procedure, the time allowed for equilibration, and on the metal/ligand ratio. The Mössbauer spectra exhibit two components: a broad magnetic sextet and a quadrupole doublet at an Fe/DN molar ratio of 1:3 and exclusively a doublet at a molar ratio of 1:20, indicating an equilibrium of these two spectral components. The EPR spectra are dominated by a signal at g(eff) = 2. Double integration of the EPR signals enabled the determination of their spin density and a correlation between EPR and Mössbauer spectra. The Mössbauer sextet species is EPR invisible and corresponds to magnetically ordered polynuclear aggregates with high magnetic anisotropy. EXAFS and susceptibility measurements provide additional evidence for the formation of polynuclear aggregates of ferric daunomycin. The quadrupole doublet species in the Mössbauer spectra correlates with the g = 2 signal in EPR. This species is also related to a magnetically ordered system, exhibiting, however, superparamagnetic behavior due to less magnetic anisotropy. Since daunomycin forms dimers in aqueous solution at millimolar concentrations, we conclude that the cooperative phenomena observed in EPR and Mössbauer spectra are a consequence of its stacking effects.

Daunorubicin↗