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Biomedical subjects

L Bernardi

Publications and source records attributed to L Bernardi.

At least 145 records · Page 8Linked to original sources
PubMed1986

Radiosurgery using a 4MV linear accelerator. Technique and radiobiologic implications.

In the authors' technique, the stereotactically localized target is fixed to the isocenter of a 4 MV linear accelerator. The irradiation is carried out along 9-17 non-coplanar arcs distributed on a 160 degrees cylindrical sector. High doses (10-50 Gy) are delivered in one or two sessions. From 1982, 65 patients have been treated (shortest follow-up 6 months). The dose was chosen according to the pathology and to the volume of the lesion. Good clinical results have been obtained in low-grade gliomas, acoustic neuromas, arteriovenous malformations, and other selected types of intracranial lesions. Therapeutic effects in terms of clinical condition and size of the lesions have been plotted in relation to time elapsed and dose employed.

Adolescent↗
PubMed1986

Heart rate-respiration relationship: computerized method for early assessment of cardiac autonomic damage in diabetic patients.

This study compares the sensitivity of electrocardiographic R-R methods, used alone and with respiration, for diagnosis of cardiac disautonomy in diabetic patients. In 12 diabetic subjects with laboratory signs of neuropathy (45 +/- 10.4 years) (group A), 24 diabetic subjects without neuropathy (45 +/- 11.9 years) (group B) and 16 normal subjects (43 +/- 12.6 years) (group C), electrocardiogram and respiration were on-line digitized during spontaneous breathing and hyperpnea at 3-18 breaths/minute. Heart rate, R-R standard deviation (SD), R-R range (RG) and cross-correlation function (CC) were computed. Reproducibility was tested in 10 normal volunteers (age 22-28 years, mean 25.2). During spontaneous breathing, heart rate was 87.5 +/- 11.8 beats/min in group A, 77.3 +/- 10.8 in group B, and 71.6 +/- 14.9 in group C (p less than 0.05); RG was 102 +/- 51 msec in group A, 166 +/- 78 in group B and 272 +/- 168 in group C (p less than 0.005); SD was 18.2 +/- 10.1 msec in group A, 29.3 +/- 13.7 in group B and 49.2 +/- 26.5 in group C (p less than 0.001); CC was 2.38 +/- 0.66 units in group A, 3.00 +/- 0.72 in group B and 3.85 +/- 0.59 in group C (p less than 0.0001). During hyperpnea the difference between A and B increased for SD, RG (p less than 0.01) and CC (p less than 0.001). CC better discriminates between normals and diabetics without neuropathy during normal breathing; hyperpnea enhances the relationship heart rate-respiration in normal and, at a lesser degree, in diabetic subjects, thus slightly improving the method. The CC method had better reproducibility and lower intersubject variability than traditional methods of R-R variability.

Adult↗
PubMed1986

[Reproducibility of the measurement of thoracic electric impedance].

Recordings of thoracic electrical impedance were consecutively taken in 10 normal subjects (age 18-48 years, mean 38.6) two times during the same day, during the following day and after 1 month. The following parameters were evaluated: heart rate, systolic blood pressure, diastolic blood pressure, left ventricular ejection time, pre-ejection time, baseline electrical impedance, DZ positive peak, Q-dZ/dt interval and Heather Index. Data were processed in order to quantify the different source of variability: subjects or biological variability, days, beats. Total variability was expressed in absolute units as coefficient of variation. Results were as follows: Q-dZ/dt interval had the lowest coefficient of variation (7.7%). Inter subject was the largest source of variability for all the indices showed, ranging from 70.5% to 89.3%. On the contrary intraindividual variability was moderate racing from 1% to 2.6% for various impedance measurements. In conclusion, thoracic electrical impedance measurements showed good reproducibility, especially when successive measurements were compared in a same subject.

Adult↗
PubMed1986

Automatic on-line measurement of systolic time intervals using a personal computer.

A personal computer-based system for automatically evaluating external systolic time intervals (STI) suitable for practical clinical use is presented. In 56 consecutive unselected subjects, ranging in age from 16 to 77 years (mean = 51 years), the STI recorded with standard technique were computed manually and automatically. Manual and automatic techniques correlated closely in all indices studied (Q-Q interval: r = 0.995; electromechanical systole: r = 0.975; pre-ejection period (PEP): r = 0.985; left ventricular ejection time (LVET): r = 0.973, PEP/LVET: r = 0.981, p less than 0.001). These results demonstrate that automatic evaluation of STI can be effectively made with good reliability using inexpensive hardware.

Adolescent↗
PubMed1985

Modeling the isovolumic relaxation period.

The isovolumic relaxation period of the left ventricular pressure curve in man has been assumed to be best represented by an exponential decay. To determine which model most closely approximates the empiric pressure data of isovolumic relaxation in man, several models were compared. They included linear, exponential with a zero mmHg pressure asymptote, exponential with a variable asymptote, and second-to fifth-order polynomials. In addition, four different methods of computing parameters of isovolumic relaxation by the exponential model with a variable asymptote were tested. It was found that the isovolumic relaxation period approximates an exponential, that the theoretic asymptote is variable, and that the Levenburg-Marquardt algorithm can be used efficiently to model this period.

Adult↗
PubMed1985

Heart sound propagation in the human thorax.

Simultaneous quantitative recordings of pressure in the aorta near a prosthetic valve and at two locations externally on the chest provide data on certain aspects of sound propagation in the human thorax. On the basis of the different speeds of propagation, it is possible to distinguish between the longitudinal and transverse vibrations contributing to the external phonocardiographic signal. Digital signal processing was employed to derive transfer functions, correlations and power spectra.

Acoustics↗
PubMed1985

Visual evoked potential recordings in hepatic encephalopathy and their variations during branched chain amino-acid treatment.

In fourteen subjects with various stages of hepatic encephalopathy (HE), Visual Evoked Potential (VEP) recording and blood ammonia (NH3), octopamine (OCT) and phenylethanolamine (PEA) determinations were performed before and during a four-day treatment with branched chain amino acid (BCAA) i.v. infusion. All the subjects with HE showed significant basal VEP alterations, namely an increased latency and a lowered amplitude of the P100 wave, in comparison with a control group of 26 normal subjects. A significant improvement in P100 wave amplitude occurred just about 60' after the beginning of BCAA infusion, while P100 latency was still unaffected, as were OCT, PEA and NH3 levels. After the fourth day of BCAA treatment, both P100 wave amplitudes and latencies were strongly improved, together with OCT, PEA and NH3 levels. VEP improvements seemed to be well correlated with HE clinical evolution, and were able to detect modifications of central nervous system reactivity earlier than serum parameters.

Adult↗
PubMed1984

[Apex cardiography calibrated by an infinite-time constant. Technic and methodology].

A new apexcardiographic transducer system is presented. The device features infinite time constant, absolute pressure calibration and measurement of thorax coupling pressure (PO). The sensing element is an estensimetric bridge, mounted on the internal surface of a rigid membrane, coupled to the chest by a 4 x 7 mm plastic cylinder. The system is linear within the range of 0 to 1350 mmHg; the frequency response of the transducer is linear between 0 and 3500 Hz. The electronic filtering circuits allow simultaneous output of apexcardiogram, first apexcardiographic derivative and three phonocardiographic bands. Measurements carried out on 6 volunteers using the new apparatus and a traditional transducer system demonstrate that control of the coupling pressure is necessary not only for absolute amplitude, but also for accurate amplitude ratio measurements because the transmission of pressure signal across the thorax changes with different coupling pressures.

Calibration↗
PubMed1984

[The apex cardiogram in normal aged subjects].

In 25 healthy subjects aged 60-88 years (mean 74.5) and in 20 healthy subjects aged 16-32 years (mean 23.6) apexcardiographic indices were studied as a function of age. The apex cardiograms (ACG) were obtained using a non-calibrated displacement transducer. With the help of an interactive computer program, 17 ACG indices of systolic and diastolic function were computed. The indices were divided into 2 groups (according to the nomenclature proposed by their Authors): a) systolic indices: electromechanical ventricular interval q-C, systolic upstroke time C-E, time from the beginning of ventricular depolarization to the peak of the first ACG derivative q-dA/dt, time from the onset of systolic slope to the peak of first ACG derivative C-dA/dt, ejection fraction according to Antani et al. 1979 E.F.; b) diastolic indices: electromechanical atrial interval P-a, atrial wave length d.a., height of atrial wave as percent of total ACG deflection a/H, height of atrial wave as percent of total diastolic deflection a/D, ratio of the diastolic wave to the total ACG height D/H, total rapid filling cR, early filling period EFP, rapid filling period RFP, total apexcardiographic relaxation time TART, duration of diastolic period A2-C, total apexcardiographic relaxation time index TARTI and diastolic amplitude time index DATI. Several diastolic indices (a/D, a/H, TART, electromechanical atrial time) were markedly higher (p less than 0.001) or lower (TART and DATI, p less than 0.001) in the older group. Systolic indices showed less significant differences: the electromechanical interval lengthened in the older group (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Comparative clinical evaluation of left ventricular ejection time using carotid and ear pulses].

The aim of this study was to verify if in the clinical use the relationship between the morphology of the carotid pulse and of the ear densitogram was constant enough to validate the measurement of left ventricular ejection time from the ear densitogram. In 92 subjects, aged 5-84 years, carotid pulse and ear densitogram were simultaneously recorded. The ear densitogram was electronically processed with 3 different filters, in an effort to duplicate the carotid pulse and thus to facilitate the measurements of the ejection time. Mean ejection time was 265.5 +/- 24.87 msec. for carotid pulse, and 265.7 +/- 24.19, 265.2 +/- 24.25, 266.2 +/- 24.78 for the ear densitographic methods. Analysis of variance did not show any differences among the 4 methods. We conclude that quite a constant relationship between carotid pulse and ear densitogram is present in clinical measurements. Thus, the carotid pulse can be reliably substituted by the ear densitogram.

Adolescent↗
PubMed1984

Kinetocardiographic detection of ventricular dyssynergy after myocardial infarction. Correlations with two-dimensional echocardiography.

The aim of this study was to determine if kinetocardiography can detect regional abnormalities of left ventricular kinetics, as occurs in coronary patients. Kinetocardiogram, M-mode and two-dimensional echocardiograms were recorded in 33 subjects (mean age 63, range 29-75 years), who previously had a myocardial infarction. On two dimensional echocardiograms, long axis, short axis, apical 4-chamber and apical 2-chamber projections were studied. Regional contractile abnormalities were rated as hypokinesis, akinesis, dyskinesis and aneurysm. In 6 subjects two dimensional echocardiogram was normal, in 5 it showed hypokinesis with left ventricular normal dimension or dilatation, and in the remaining 22 patients various regional kinetic abnormalities were observed. The kinetocardiogram showed paradoxical systolic movements in all patients with ventricular dyssynergy and was normal in all patients with normal ventricular kinetics, with or without left ventricular dilatation and global hypokinesis. There were no correspondences between echocardiography and kinetocardiography, regarding sites and amount of abnormalities. Kinetocardiography can thus noninvasively detect qualitative left ventricular kinetics abnormalities, in patients with myocardial infarction.

Adult↗
PubMed1983

Antihypertensive ergolinepropionamides.

The synthesis and the antihypertensive activity in rats of a series of 6-methylergolin-8 beta-yl-propionic acid derivatives are reported. The prolactin lowering activity (nidation inhibition test) in rats and the acute toxicity in mice were also studied as a measure of the specificity and safety of the potential antihypertensive compounds. From the structure-activity considerations reported here it is clear how modifications at the C8 side chain can improve the selectivity of the antihypertensive effects, whilst introducing substituents in other positions of the ergoline skeleton afforded unfavourable results in this respect. Compound 5, namely 2(R,S)-cyano-3-(6-methylergolin-8 beta-yl)-propionamide, emerged as the most interesting antihypertensive derivative.

Animals↗
PubMed1983

Intestinal absorption of S-adenosyl-L-methionine in humans.

S-adenosyl-L-methionine (SAM) has proven to be fairly stable in gastric and duodenal juices as well as in bile. It was, therefore, administered orally to six healthy subjects. No increase in SAM levels was observed in the systemic blood. SAM was then directly injected into a jejunal loop of nine patients undergoing cholecystectomy. SAM concentrations increased significantly in venous mesenteric and systemic blood. Infusions of methionine directly into the jejunum by the same method used for SAM did not induce any increase in SAM concentrations in the mesenteric or systemic blood.

Female↗