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Biomedical subjects

L Leonardi

Publications and source records attributed to L Leonardi.

At least 19 recordsLinked to original sources
PubMed1992

Esophageal electrodes allow precise assessment of cardiac output by bioimpedance.

OBJECTIVES: To analyze the impact of the position of the thoracic external electrodes on the values of cardiac output measured by electrical bioimpedance and to compare the results obtained by bioimpedance with those values determined by thermodilution in critically ill patients. DESIGN: Open, prospective, comparative trial. SETTING: ICU of a teaching hospital. PATIENTS: Twenty healthy volunteers and ten critically ill patients. INTERVENTIONS: Measurements of cardiac output by bioimpedance at rest and after physical activity in normal volunteers and after changing the neck or xiphoid electrodes. Comparisons of cardiac output obtained by thermodilution and bioimpedance with internal and external electrodes in patients. MEASUREMENTS AND MAIN RESULTS: Mean +/- SD values are presented. Cardiac output values at rest and after exercise were 6.7 +/- 1.3 and 10.8 +/- 2.6 L/min at rest and after exercise, respectively (p less than .001). Displacement of the xiphoid electrodes 3 cm in the caudal direction was accompanied by a decrease of the mean cardiac output from 7.1 +/- 1.2 to 5.8 +/- 1.3 L/min (p less than .001) and displacement 3 and 6 cm cranially was accompanied by increases in cardiac output from 7.1 +/- 1.2 to 8.1 +/- 1.4 L/min (p less than .001) and 8.6 +/- 1.5 L/min (p less than .001), respectively. In the ten patients, cardiac output measurements were virtually identical when results obtained by thermodilution (6.7 +/- 3.1 L/min) were compared with those results obtained by bioimpedance using internal esophageal (6.6 +/- 3.1 L/min), but not external (4.7 +/- 1.6 L/min) electrodes. CONCLUSIONS: a) The values of cardiac output derived from measurements obtained by bioimpedance using internal electrodes were comparable with those values derived from thermodilution. b) Values of cardiac output from bioimpedance studies with external electrodes were dependent on the position of the xiphoid electrodes.

Adult↗
PubMed1992

A computer-assisted automatic method for myelinated nerve fiber morphometry.

This paper describes a computer-assisted automatic method developed for myelinated nerve fiber morphometry. IBAS image analysis system was used. One-micron thick sections of sural nerve were stained with p-phenylenediamine. Dark myelin sheaths, standing out against a pale background, were identified by a binary transformation of the computer-stored image. Different parameters of the fibers as well as of the axons can be measured. The automatic system allows operator-interactive manipulation, if required, to avoid inclusion of wrong histologic structures. A large spectrum of statistics facilities are available. We performed a comparison between automatic and semi-automatic analysis. Measurements resulted virtually overlapping, but time was three to four times shorter with automatic procedure. The method here described is accurate and reliable, and permits economy of time and effort.

Biopsy↗
PubMed1991

[Preventive cytolytic treatment following heart transplantation: ATG versus OKT3].

The postoperative prophylactic cytolytic therapy with rabbit-ATG and OKT3 after heart transplantation are compared. The first 20 recipients were treated with ATG (5 days), the next 20 with OKT3 (14 days). The medium histological rejection grade (Texas classification) was significantly higher after 2 weeks in ATG group and after 4 weeks in OKT3 group. The linearised rejection rate was 7.1 (ATG) vs. 0.7 (OKT3) (p less than 0.005) at 2 weeks, resp. 3.6 vs. 8.6 (p less than 0.05) and 1.3 vs. 2.9 (p less than 0.005) at 4 weeks and 2 months. After 3 months there was no difference in histological rejection grade (3.6 +/- 1.5 vs. 3.3 +/- 1.7) and linearised rejection rate (2.4 vs. 2.6 per 100 days and patient) between the two groups. Severe rejections are more frequent after OKT3 (6 vs. 11) and probability of rejection free survival is higher after ATG (25% vs. 0%, resp. 21% vs. 0% after 2 resp. 3 months; p less than 0.05). In this study we find no short and medium term benefit of a rejection prophylaxis with OKT3 (14 days) compared with ATG (5 days). Acute allograft rejections in OKT3 group tend to be more severe with a higher mortality.

Antibodies, Monoclonal↗
PubMed1990

[Cytomegalovirus (CMV) infection: a frequent and life-threatening complication in heart transplant patients].

We investigated the clinical relevance of cytomegalovirus infection in our heart transplant recipients (n = 48). There was a high incidence of CMV-infection in patients where IgG positive donor versus IgG negative recipient was present. A total of 5/8 patients (= 62.5%) showed severe clinical CMV-infection with pneumonitis, colitis or tonsillitis besides general malaise, requiring long hospital treatment (2 to 24 weeks). CMV-infection is a frequent and threatening complication in patients after heart transplant (HTPL). We discuss the various managements in diagnosis, prophylaxis and treatment.

Antibodies, Viral↗
PubMed1990

[Graft rejection reaction and immunosuppression following heart transplantation].

Acute rejection is the most important factor influencing mortality after heart transplant. Acute rejection occurs at least once in over 95% of the patients in the early phase after heart transplant. In the vast majority of episodes of acute rejection clinical symptoms are absent. The regular performance of endomyocardial biopsy after heart transplant allows histological diagnosis of rejection episodes as well as follow-up control of rejection treatment. This overview points to the major problems regarding acute rejection and immunosuppressive regimen in heart transplant recipients.

Graft Rejection↗
PubMed1990

[Toxoplasmosis in the heart transplant patient].

Toxoplasmosis is a well-known problem under immunosuppressive conditions in cardiac transplant patients. In our series 12% of the patients (8 of 65) had clinical and/or serological signs of active toxoplasmosis. Due to its serious prognosis once the clinical process has started we favor a generous diagnostic interpretation of the serological results and a broad indication to drug therapy.

Animals↗
PubMed1990

[Long-term follow-up after heart transplantation].

Actuarial survival rate two years after heart transplant in our patients is 90%. The most patients report excellent quality of life (NYHA I) and present definitely improved work load capacity as well as normal cardiac hemodynamic assessment two years after transplant. The major problems in the long follow-up of heart transplant recipients are accelerated coronary disease (graft atherosclerosis), arterial hypertension and renal function impairement.

Cause of Death↗
PubMed1987

Cardiovascular effects of verapamil in essential hypertension.

Calcium antagonists may affect the regulation of body sodium and adrenergic-dependent mechanisms. Exchangeable sodium, blood volume, plasma norepinephrine, renin, aldosterone, pressor responsiveness to norepinephrine, heart rate responses to isoproterenol, and lipid metabolism were studied in 15 patients with essential hypertension after 8 weeks of treatment with verapamil (348 +/- 68 (SD) mg/day). Supine blood pressure decreased from 153/103 +/- 19/12 mm Hg to 140/95 +/- 14/12 mm Hg (P less than 0.01). Exchangeable sodium, blood volume, plasma norepinephrine, renin and aldosterone, serum total cholesterol, the lipoprotein fractions, and apoprotein levels were unchanged. The norepinephrine pressor and the isoproterenol chronotropic doses tended to increase, whereas the dose-response curve of blood pressure related to plasma norepinephrine was significantly displaced to the right (F = 5.34; P less than 0.05). The antihypertensive effect of verapamil is associated with a decreased cardiovascular pressor responsiveness to norepinephrine without changes in endogenous noradrenergic activity. Moreover, verapamil does not modify the sodium/fluid volume state, the activity of the renin-angiotensin aldosterone axis, or lipid metabolism.

Adult↗
PubMed1986

"In vitro" fibril formation of type I collagen from different sources: biochemical and morphological aspects.

Acid soluble type I collagen was prepared from foetal and adult bovine tendon and skin and from adult bovine cornea. The degree of hydroxylysine glycosylation and the hydroxylysine di-to monoglycoside ratio as well as the "in vivo" fibril diameters, were shown to be tissue and age-dependent. Fibrils of type I collagens were reconstituted "in vitro" monitoring at 313 nm. The fibrils obtained were examined by electron microscopy. It was shown that the "in vitro" lateral growth of collagen fibrils leads to the formation of fibrils with maximum diameters which may be correlated to those of the corresponding native fibrils. Moreover it is suggested that one of the factors controlling the lateral growth of collagen may be at the level of hydroxylysine glycosylation.

Animals↗
PubMed1985

Ultrastructural aspects of rat tail tendon sheaths.

An investigation was carried out on the sheaths which envelop rat tail tendons. The samples were processed for observation by light and electron microscopy. In the case of electron microscopy, thin sections of specimens embedded in epoxy resin and replicas of freeze etched samples were used. On the basis of histological and ultrastructural observations, four distinct connective tissue sheaths have been detected. The paratendineum is a thick fibrous sheath that covers externally the four groups of tendons arranged around the vertebrae of the tail; the epitendineum is a distinct fibrous sheath surrounding each tendon group; the peritendineum is composed of concentric cellular laminae enveloping each tendon; lastly, the endotendineum is made up of one cellular lamella which adheres to the fibres of the tendon, projecting trabeculae between the individual tendon fascicles. In the para- and epitendineum, thick bundles of collagen fibrils, running parallel to the fibres of the tendon, were visible. The collagen fibrils had a wide variability of diameters (from 35 to 220 nm) and, when examined in replica, their microfibrillar arrangement appeared to be straight. In the peri- and endotendineum, thin bundles of collagen fibrils were visible between the cellular laminae, parallel to the main axis of the tendon. Among these collagen bundles, elastic fibres and numerous glycoproteins containing microfibril-like filaments were visible. The collagen fibrils were small and of uniform diameter (50 nm) and, when observed on replica, showed a helicoidal microfibrillar arrangement. The cell layers of the peri- and endotendineum were made up of flattened fibroblasts which were connected by specialised junctions and which contained numerous micropinocytotic vesicles. A thin layer of granular electron-dense material, with ultrastructural characteristics similar to those of a basement membrane, was visible on the surface of the most external cellular layer of the peritendineum and on the outer surface of the cellular lamella of the endotendineum. Due to their morphological characteristics it is supposed that the four tendon sheaths are involved in different and special functions. Moreover, collagen Type I and collagen Type III, demonstrated by means of immunofluorescence techniques in previous investigations, show respectively a close similarity in distribution to the thick collagen fibrils, with a straight microfibrillar arrangement, of the two external sheaths, and to the thin collagen fibrils, with a helicoidal microfibrillar arrangement, of the two internal sheaths.

Animals↗
PubMed1975

Influence of sulpiride on gastrointestinal motility: experimental radiological study in the dog.

A radiological study has been carried out in the dog to control the influence of N-ethyl-2(2-methoxy-5-sulfamido-benzamidomethyl)-pyrrolidine (sulpiride) on the motility of the gastrointestinal tract. The drug was administered orally and parenterally at different doses for each pharmaceutical form and for such route of doses for each pharmaceutical form and for each route of administration. In doses which were considered optimal, the results have demonstrated that sulpiride exerts hypertonic and hyperphasic effects on the smooth musculature of the gastrointestinal tract. Consequently, there is a reduction of the transit time and of the emptying of the opaque meal in the various sectors of the gastrointestinal tract, which is in the order of about 50% with respect to normal. Using doses which are inferior to those considered optimal, no significant results were obtained, while following higher doses the action of sulpiride is manifested by an inhibitory effect on gastrointestinal motility.

Administration, Oral↗