PubMed Health⌕ Search

Biomedical subjects

P Rossini

Publications and source records attributed to P Rossini.

At least 37 records · Page 2Linked to original sources
PubMed1997

Spectral analysis of intercycle heart fluctuations in Xenopus laevis, conscious or spinalized, treated with calcium channel blockers. Part I.

1. In this study, electrocardiographic second lead tracings were recorded and analyzed online and offline in the conscious and spinalized Xenopus laevis under control conditions and after treatment with at least two effective doses of racemic diltiazem, nifedipine and racemic verapamil hydrochlorides. 2. Heart rates (HR) and intercycle heart rate power spectra (IHRPS) were calculated in the various experimental conditions. 3. Dose-dependent bradycardia was found in most cases, which was associated with dose-related increases in the overall dynamic range of the largest peak of HR variability (increased IHRPS), this being particularly marked at the higher nifedipine dose. The frequency position of the largest peak was unchanged in the spinalized preparation, as well as in the various treatments. 4. These findings may contribute toward a more complete pharmacodynamic definition of calcium channel blockers in their current therapeutic use.

Animals↗
PubMed1997

Spectral analysis of intercycle heart fluctuations in the diethyl-ether-anaesthetized or pithed rat treated with l-hyoscyamine.

1. Within the context of neural regulation of the activity of sinus node pacemaker cells, the study of heart rate variability, as explored in the frequency domain by spectral analysis, was proposed about 15 years ago as a quantitative tool for the evaluation of short-term autonomic cardiovascular control. It has since been postulated that the two main oscillations observed, one at low and the other at high frequency, may respectively be markers of sympathetic vs. vagal efferent cardiac activity, and that the low- and high-frequency signals may reflect a reciprocal or 'push-pull' relationship between sympathetic and parasympathetic control. 2. In our power spectra assessment, ECG R-R intervals were submitted to fast Fourier transformation analysis in order to study the mechanisms underlying the control of heart beats in rats. Data were acquired in conditions of steady arterial blood pressure and cardiac and respiratory activity (spontaneous or artificially stimulated) in diethyl-ether-anaesthetized and pithed rats, as well as in a group of control rats, all in the presence and absence of l-hyoscyamine. 3. With increasing doses of the parasympathetic antagonist, the fractal dimension of the time-series structure remained stable in most cases. The low-frequency spectral component narrowed with increasing drug doses and the high-frequency band underwent either no, or only very slight, changes. 4. In these rodent assays, the low- and high-frequency signals cannot be interpreted as a push-pull relationship between sympathetic and parasympathetic control.

Anesthetics, Inhalation↗
PubMed1996

Synovial fluid levels of proinflammatory interleukins and their inter-relationships in elderly vs younger onset rheumatoid arthritis.

Elderly-onset rheumatoid arthritis (EORA) is thought to be different from younger-onset disease (YORA) for many reasons, including a more elevated acute phase response and a more abrupt onset; both events are mainly regulated by pro-inflammatory interleukins (ILs), in particular, IL-1, IL-6 and IL-8. To compare the synovial fluid (SF) levels of these ILs, and their relationship to local inflammation as well as the acute phase response, erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) in the two RA subsets, we determined white blood cell (WBC) number, total protein (TP), IL-1beta, IL-6 and IL-8 concentrations in the SF of 50 patients, 15 with EORA and 35 with YORA. Both ESR and CRP were higher in EORA than in YORA. IL-6 was higher in SF of EORA (2111.37 +/- 1425.03 pg/mL) than YORA (1077.53 +/- 757.62 pg/mL, p = 0.002), while no difference was observed for SF IL-1beta and IL-8. There was a weak correlation between SF IL-6 and IL-1beta in EORA, whereas SF ILs and CRP and/or ESR did not show any correlation in both groups. Our study indicates that in EORA, as in other diseases occurring in the elderly, there are elevated levels of IL-6. Higher SF levels of IL-6 may be, at least in part, responsible for the different behavior of EORA with respect to YORA.

Acute-Phase Reaction↗
PubMed1996

Neuromagnetic localization of the late component of the contingent negative variation.

The contingent negative variation (CNV) in a warned choice reaction time task was studied in 24 healthy subjects by use of magnetoencephalography (MEG). Special interest was focused on the late component of the CNV, CNVL. Source localization of the magnetically recorded CNVL, mCNVL was performed on 13 subjects, selected on the basis of the strength and stationarity of the electrically recorded CNV, eCNVL. To achieve whole head mapping, up to 500 epochs from different scalp positions were recorded, including a pretrial learning period of 40 epochs. The neuromagnetic signals studied in this experimental protocol are thus related to neurological processes that are present after an initial learning period has occurred. In 11 subjects, a goodness of fit between 88% and 95% was achieved using a two-dipole model with one equivalent source localized close to the precentral cortex contralateral to the side of movement, at mean a depth of 30 mm. Estimates of ipsilateral equivalent sources were less consistent across subjects. In 9 subjects the estimated ipsilateral sources were located symmetrically to the contralateral source. The results of this study suggest that the dominant source of the mCNVL is located near the bottom of the sulcus precentralis at the anterior bank of the gyrus precentralis, close to the sulcus frontalis superior. This supports previous findings that the CNVL is closely related to the readiness potential, and that the major cortical activity is symmetrically located in the left and right premotor areas.

Adult↗
PubMed1996

Value of synovial fluid interleukin-1 beta determination in predicting the outcome of psoriatic monoarthritis.

OBJECTIVE: To investigate the value of synovial fluid analysis in predicting the outcome of psoriatic monoarthritis. METHODS: In synovial fluid from knee joints of 18 patients with psoriatic monoarthritis lasting less than six months, white blood cell count, acid phosphatase, lysozyme, and interleukin (IL)-1 beta were determined. ESR and serum C reactive protein were also measured. To define the outcome, the patients were monitored for at least three years and then subdivided into those with polyarthritis and those without. RESULTS: Among the blood and synovial fluid indices considered, synovial fluid IL-1 beta was the only variable which differed between the patients who developed polyarthritis, within three years and those without polyarthritis after this time, at 20.82(SD 8.79) v 4.19(4.73) pg ml-1, P < 0.0001). A correlation was found between synovial fluid IL-1 beta concentrations and the number of affected joints after three years (r = 0.739, P < 0.0001). CONCLUSIONS: Determination of synovial fluid IL-1 beta at disease onset may be useful in revealing the outcome of psoriatic monoarthritis since, among the variables considered in our study, this was the only one capable of predicting the evolution of monoarticular psoriatic arthritis to polyarthritis.

Adolescent↗
PubMed1995

Evaluation of technetium-99m-sestamibi lung uptake: correlation with left ventricular function.

UNLABELLED: Lung uptake of 201Tl is a reliable marker of left ventricular dysfunction. The goal of our study was to establish whether the evaluation of lung-to-heart uptake ratios (LHR) with 99mTc-sestamibi imaging may provide valuable information. METHODS: We studied 72 male subjects with recent anterior myocardial infarction undergoing 99mTc-sestamibi first-pass ventriculography and SPECT perfusion imaging. A group of 46 gender-matched subjects with low pre-test likelihood of CAD and normal exercise and rest 99mTc-sestamibi perfusion images was used as a control. The lung-to-heart count ratios (LHR) were calculated on planar projections from the sets of SPECT images. RESULTS: Both groups were studied at rest and after a symptom-limited exercise tolerance test. In the control group a significant decrease in LHR was observed during stress (p < 0.001). The infarcted group showed significantly higher LHR values both at rest and at stress. Exercise and rest LHR values did not differ significantly. A positive correlation was observed between LHR values and left ventricular ejection fraction at rest and stress. CONCLUSION: LHR, measured by 99mTc-sestamibi imaging, gives clinically useful information. Both resting and postexercise values are correlated with ejection fraction and should predict left ventricular dysfunction.

Adult↗
PubMed1993

A 31P NMR spectroscopy study of Xenopus laevis heart perfused in vitro with creatinol-O-phosphate, phosphocreatine, adenosine triphosphate, fructose diphosphate and ouabain.

Xenopus laevis heart was studied by 31P NMR using a 200 MHz proton spectrometer; hearts were perfused, at pH 7.35 and room temperature, with normal oxygenated or K(+)-enriched Ringer. Solution was later added with creatinol-O-phosphate (COP), phosphocreatine (PCr), adenosine triphosphate (ATP), fructose-1,6-diphosphate (FDP) and ouabain. NMR spectra of the heart show organic phosphomono- and phosphodi-esters, inorganic phosphate, PCr, overlapping alpha-ATP/ADP and gamma-ATP/beta-ADP, and beta-ATP signals. Their chemical shift positions and areas showed no significant changes in the course of 1.5 h perfusions with either solution, except in a few preparations, whether the heart was beating or reversibly arrested. While COP reduced the signals in beating hearts, the same spectra exhibited no consistent, substantial changes under PCr, ATP and FDP 1 to 10 mM, pH 7.35 perfusion with either solution, nor when ouabain mumol was added. The spectra are briefly discussed in comparison with those observed in the perfused heart of mammals (mostly rat), and particularly with those obtained in the frog (Rana temporaria) heart, both by analysing the bioenergetic equilibria on the basis of total tissue substrate levels measured in extracts of freeze-clamped tissue, and by evaluating cytochrome-b, flavin and pyridine nucleotide in vitro oxido-reduction read-outs in separate, similar experimental settings.

Adenosine Triphosphate↗
PubMed1991

Continuous read-out of cytochrome b, flavin and pyridine nucleotide oxido-reduction processes in the perfused frog heart and contracting skeletal muscle.

The time-sharing instrument for continuous read-out of the fluorescence levels of NAD(P)H and oxidized-flavoproteins, which also makes simultaneous dual beam differential absorption measurements of cytochrome b, has been applied to the study of the metabolic control of the frog heart, perfused in vitro with normal and variously modified Ringer solutions, and to the frog skeletal muscle in situ. In the ionically depolarized resting heart, the long term kinetic analysis of the redox processes during oxygen/anoxia transitions has proved to be an adequate method for identifying and following three fundamental intracellular redox compartments: (1) the respiratory system, (2) the microsomal system, and (3) the glycolytic system. The provision of substrates and/or suitable inhibitors has allowed the description of functional interrelationships within the mitochondrial and the cytoplasmic spaces. The ouabain major site of response has been located on the cytosolic pyridine nucleotides, with a very small response in the mitochondrial space. The switching on and off of substantial fractions of the NAD(P)+/NAD(P)H and Fpoxidized/Fpreduced pools has been observed, which helps to clarify the large phase shift between the overall pyridine nucleotide and flavin oxidation-reduction processes, during the cycle of the spontaneously beating heart and during skeletal muscle contraction and recovery, here originally prompted out.

Animals↗
PubMed1991

Renal and hemodynamic effects of atrial natriuretic peptide infusion are not mediated by peripheral dopaminergic mechanisms.

The possible involvement of peripheral dopaminergic mechanisms in the action of atrial natriuretic peptides was investigated in 10 subjects by administering 200 micrograms h-ANP 99-126 intravenously for 30 min during treatment with 50 mg carbidopa, a peripheral inhibitor of dopamine synthesis, every 8 h, or during placebo. Atrial natriuretic peptide (ANP) infusion during placebo was associated with a significant increase of diuresis, natriuresis, kaliuresis, urinary noradrenaline, and dopamine excretion. Plasma aldosterone significantly decreased. Blood pressure was slightly reduced. The administration of carbidopa significantly reduced urinary dopamine excretion but did not modify natriuresis, diuresis, indexes of adrenergic and renin-aldosterone system activity, blood pressure, or heart rate, both in basal conditions and in response to ANP infusion. We conclude that the effects of exogenous ANP administration are independent from dopaminergic mechanisms that involve the synthesis of dopamine outside the central nervous system, particularly in the kidney.

Adult↗
PubMed1990

[Stellate ganglion block in the treatment of ischemic syndrome in an upper limb due to accidental intra-arterial injection of pharmacologic substances or narcotics].

The paper describes five cases of accidental intraarterial injection of pharmacological drugs (diazepam or thiopentone) or dope (heroin) in an upper limb. Following a review of the physiopathological mechanisms which led to ischemic damage, the Authors outline a protocol of continuous pharmacological sympathicolysis in the affected limb, using repeated anesthetic blocks of the homolateral stellate ganglion.

Arm↗
PubMed1990

[Increase by ANP and ADH of the duration of activation and deactivation of the cardiopulmonary baroreceptor reflex: modification in the presence of left ventricular hypertrophy].

The involvement of cardiopulmonary and arterial sinoaortic receptors in the control of antidiuretic hormone (ADH) and atrial natriuretic peptide (ANP) release is still controversial in humans. Moreover, it is not clear if this control may be impaired in hypertensive patients with left ventricular hypertrophy (LVH). We studied 17 male subjects, age 18-58 (6 normotensives and 9 mild hypertensives, 5 without and 4 with LVH). Each subject underwent selective loading and unloading of cardiopulmonary receptors, in a randomized sequence, by application of a positive (LBPP) or negative (LENP) pressure to the lower body (steps: +10, +20, +40, -10, -40 mmHg, each for about 30 min), through a plexyglass-constructed tubular apparatus with a rubber adhesion round the patients' waist. Blood samples were taken at the end of every step for measurement of ADH, ANP, PRA, immunoreactive renin, aldosterone, noradrenaline and adrenaline. Cuff arterial pressure was measured every 5 min, while heart rate was evaluated by continuous ECG recording. Hypertensive subjects underwent right atrial pressure measurement by an iv catheter and forearm blood flow evaluation at rest and during the different steps (venous occlusion plethysmography). During LBNP, ADH plasma levels increased progressively, but the increase became statistically significant only at the step of -40 mmHg. ANP increased significantly during LBPP. Taking into account only hypertensive patients, a consistent reduction in the changes of ADH and ANP plasma levels, respectively during LBNP and LBPP in patients with LVH in respect to those without LVH was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[A clinical case of severe megaloblastic anemia during treatment with primidone].

The case of a patient who developed megaloblastic anemia caused by folate deficiency during treatment with primidone is reported. The serum level of folic acid was significantly low. Two causes able to produce folate deficiency have been discovered: chronic assumption of primidone, and low dietary intake of folic acid. The anemia was completely reversed by oral supplementation of folic acid. It has already been recognized that additional nutritional deficiency is required to precipitate a frank megaloblastic anemia during therapy with antiepileptic drugs.

Administration, Oral↗
PubMed1988

Neuromagnetic functional localization: principles, state of the art, and perspectives.

The neuromagnetic method has been providing impressive results in the understanding of the functions and of some pathologies of the human brain. The possibility of achieving three-dimensional source localization represents a fundamental step forward in the study of the organization of cortical areas, in that of focal disorders and, in general, in the investigation of brain information processing. The development of large multichannel systems to achieve real time functional localization is being carried on in several countries and the first prototypes are already operating for a full assessment of the benefits of the technique. The use of time-varying magnetic pulses provides the opportunity for non-invasive stimulation of the central nervous system toward the achievement of functional imaging of the motor cortices.

Brain↗
PubMed1988

Electrical stimulation of the motor cortex: theoretical considerations.

The aim of this paper is to present the results of a theoretical analysis of the intracranial fields produced by electrical stimulation of the unexposed motor cortex with surface electrodes in humans. Simulations of a first approximation model of the head indicate that the intensity and the spatial configuration of the intracranial fields can be controlled, to a great extent, by proper choice of the location and of the number of the stimulating electrodes. Fields are shown to be reasonably insensitive to changes of some crucial parameters, like the number of the stimulating electrodes and the ratio between the conductivity of the skull and that of the other tissues.

Electric Conductivity↗