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Biomedical subjects

S Di Luzio

Publications and source records attributed to S Di Luzio.

10 recordsLinked to original sources
PubMed1997

The study of steady magnetic fields associated with primary and secondary ST shift in ischaemic rabbit hearts.

The study of injury potentials associated with DC currents that generate the primary or secondary ST shifts during cardiac ischaemia is possible only through the invasive technique of the DC electrogram. Clinical surface ECG recordings are AC coupled and cannot be used. This paper reports the use of non-invasive and unshielded magnetocardiographic measurements to evaluate the DC injury currents associated with ST shifts during coronary artery occlusions in the isolated rabbit heart. The effect on the magnetic ST shift is studied under different ischaemic conditions including regional ischaemia, global ischaemia, global ischaemia following long periods of regional ischaemia, regional ischaemia after repeated episodes of reversible global ischaemia, and bilateral regional ischaemia. Recording of DC magnetic fields allows the characterization of primary and secondary ST displacement for each induced ischaemic condition. Our measurements show that the ST shift starts earlier when inducing ischaemia in hearts previously subjected to ischaemic episodes than in hearts where the ischaemia was produced for the first time.

Animals↗
PubMed1997

[Implanting of coronary stents in patients with unstable angina].

In the present study, we retrospectively examined our experience with the Palmaz-Schatz stent in patients with unstable angina to determine: a) different outcomes between patients with stable and unstable angina, b) correlation between the class of unstable angina and 1-month and 6-month results, c) correlation between lesion morphology and procedural complications. From January 1994 to January 1996, 160 patients with unstable angina (Group A) and 104 with stable angina (Group B) underwent coronary stenting. According to the modified Braunwald classification patients with unstable angina were divided into four classes. Lesion morphology was classified in simple and complex. Procedural success was 98% in Group A patients and 99% in Group B patients. We observed 9 (5.6%) major complications in Group A vs 2 (1.9%) in Group B. Subacute thrombosis occurred in 9 patients in Group A and in 2 patients in Group B and these different rates were responsible for the higher number of acute myocardial infarction and urgent revascularization procedures in Group A patients. At 6-month follow-up there were no differences between Group A and Group B patients. Patients in different classes of angina showed a similar cardiac event rate at 1-month and 6-month follow-up. We found 108 complex lesions in patients with unstable angina vs 20 in patients with stable angina (p = 0.0001). Among the 9 patients with unstable angina and subacute thrombosis, 6 had a complex lesion and 3 a simple lesion (NS). In conclusion, patients with unstable angina receiving intracoronary stent have similar clinical outcome at 1-month and 6-month follow-up as compared to patients with stable angina. The class of unstable angina and the complex morphology of the lesion are not related to procedural complications.

Angina, Unstable↗
PubMed1996

A SQUID based AC susceptometer for the investigation of large samples.

We developed a SQUID based susceptometer with a large available magnetized volume for the investigation of large objects. The magnetizing field is generated by a pair of Helmoltz coils. To achieve a high signal-to-noise ratio, the susceptometer is operated in a lock-in mode with an AC magnetizing field. A negative feedback control allows the rejection of the applied field with a relative residual of 1 x 10(-7). The apparatus was tested with substances of known magnetic susceptibility. The overall sensitivity, stated in terms of the magnetic moment, is better than 7 x 10(-11) A m2 for small samples.

Humans↗
PubMed1995

Detection and counting of specific cell populations by means of magnetic markers linked to monoclonal antibodies.

We report on experiments aimed at the assessment of a new method for cell marking. This method combines superparamagnetic particles, commonly used for cell separation, linked to monoclonal antibodies, and biomagnetic instrumentation featuring an extremely high magnetic field sensitivity. The final goal of the method is to locate and estimate specific cell populations in the human body. In this experiment, quantitative features of the method are evaluated in vitro with lymphocytes and carcinoma cells. Comparison between estimation and direct counting of cells is quite satisfactory and motivates further development of the technique.

Antibodies, Monoclonal↗
PubMed1994

Magnetocardiography and exercise testing.

Twenty healthy male subjects (age range, 15-25 years; median, 21 years) underwent magnetocardiography during physical exercise. Significant ST-segment displacements of the magnetic signal were found during exercise at a heart rate of 120 beats/min compared to the magnetic signal at rest (P < .001). Since no significant ST-segment changes were found in the electrocardiogram recorded simultaneously with the magnetocardiogram, it is concluded that the magnetocardiogram shows junctional ST-T segment changes earlier than the electrocardiogram.

Adolescent↗
PubMed1992

Measurement of segmental transit through the gut in man. A novel approach by the biomagnetic method.

The techniques commonly used to evaluate the transit of contents through the gut feature some limitations for being either inaccurate, invasive, inconvenient, or potentially dangerous for the subjects. Aim of this study was to establish a safe, noninvasive and accurate technique for the measurement of segmental oroanal transit time. We localized an orally ingested magnetic marker by means of a biomagnetic instrumentation that allows us to identify in a three-dimensional pattern the position of a biomagnetic source inside the body. The biomagnetic localizations were compared with the anatomical data obtained by magnetic resonance imaging investigations. The study was performed in 12 healthy subjects, and scans were taken every hour up to the arrival of the marker into the cecum; thereafter, scans were taken every 4 hr up to the elimination of the marker. In 99% of the isofield maps obtained from each field scan, the marker was localized within the bowel walls. The mean oroanal transit time was 56 +/- 5 hr, the mouth-to-cecum transit time was 13 +/- 1.7 hr, and the total colonic transit time was 43.5 +/- 5 hr (mean +/- SEM). Segmental colon transit did not show major differences among the regions considered, although most of the time was spent in the right colon. In fact, a good correlation was found between transit time through the right colon and oroanal and total colonic transit (r = 0.77, P < 0.02, r = 0.79, P < 0.02 respectively). In conclusion, this method might be a safe alternative to the techniques presently used in the clinical setting for the measurement of intestinal transit.

Administration, Oral↗
PubMed1983

On the interpretation of the early part of the liver time-activity curve: double tracer experiment.

A double tracer experiment was performed in one normal subject and in one cirrhotic patient to better understand the tracer kinetics in the liver area during the first minute after injection. From a comparison of the time-activity curves obtained in each subject by subsequent iv administration of a nonextracted and an extracted (colloidal) tracer it was possible to distinguish the contribution due to the transport mechanism through intrahepatic and extrahepatic circulation and that due to reticuloendothelial extraction. Three main phases were identified on the curves and an attempt was made to interpret their significance. Results of the study may be of interest for the development of models which could possibly provide more reliable noninvasive quantitation of liver hemodynamics and reticuloendothelial function with the use of one or both types of tracer.

Hemodynamics↗
PubMed1979

[Spectral properties of perselenosulfide].

The riductive scission of a diselenide (selenocystamine) produced by disulfide gives the perselenosulfide, a new compound. Its formation kinetics, carried out a several pH values, were recorded spectrophotometrically at 375 nm. The lability of perselenosulfide bond by cianolysis has been demonstrated.

Selenium↗
PubMedDate not supplied

[Percutaneous aortic valvuloplasty in the adult. When and why is now useful?].

Percutaneous aortic valvuloplasty was introduced into clinical practice in 1986 and widely applied in elderly patients with symptomatic aortic stenosis. Nevertheless its results have been unsatisfactory over the mid to long term due to a high incidence of restenosis after 6-12 months. At the same time, patients over 70 years are more frequently undergoing surgical aortic valve replacement with low immediate postoperative mortality and good long term results. Although randomized trials are not available, aortic valve replacement seems to be a definitive therapeutic treatment when compared to the palliative result of aortic percutaneous valvuloplasty. However, since the complication rate of valvuloplasty carried out in cardiological centers with experienced personnel is low, this procedure is still indicated in selected patients. The very old (> 80 years) patients with associated systemic disease, and candidates for major surgery are referred for this procedure. Another indication for aortic valvuloplasty is severe aortic stenosis with cardiogenic shock; in this case, valve dilatation improves clinical status and acts as a "bridge" to surgery, enabling surgical intervention to be carried out at a later date. Nowadays, aortic percutaneous valvuloplasty is a possible alternative to surgical treatment in patients with an absolute surgical contraindication and in those who are in such poor clinical condition that they cannot be immediately referred to surgery. It is also useful for patients requiring urgent non-cardiac surgery (e.g., subjects with gastrointestinal bleeding). We discuss our results with this procedure which concord with those presented in the literature.

Aged↗