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Biomedical subjects

L Molteni

Publications and source records attributed to L Molteni.

14 recordsLinked to original sources
PubMed1992

The hypertrophied myocardium and coronary disease. Structural changes in patients submitted to aortocoronary bypass surgery.

Seventeen patients with coronary disease submitted to myocardial revascularization were studied. Ten patients had a hypertrophied ventricle, and 7 had normal ventricular mass. Myocardial biopsies were obtained before ischemia and at the time of reperfusion and were assessed for: volume fraction of fibrous tissue, myocyte diameter, morphometric mitochondrial studies and ultrastructural changes. The volume fraction of fibrous tissue in patients with hypertrophied ventricle was 1.9 +/- 0.04, and in patients with normal ventricular mass was 0.9 +/- 0.01 (p less than 0.05). The diameter of the myocyte was 23 +/- 0.3 microns and 18 +/- 1.2 microns for patients with hypertrophied and normal ventricular mass, respectively (p less than 0.01). The value of volumetric density for pre-ischemia samples in patients with a hypertrophied ventricle was 23 +/- 2.2 and in patients with normal ventricular mass was 35 +/- 2.7 (p less than 0.02). Grades 3 and 4 of damaged mitochondria were significantly increased in reperfusion samples from patients with a hypertrophied ventricle compared to pre-ischemia samples. Collagen growth was increased in hypertrophied hearts which were also more sensitive to the ischemia/reperfusion mechanism.

Biopsy↗
PubMed1991

The value of the echo-Doppler in cardiomyoplasty procedures.

UNLABELLED: Echo-Doppler determinations were performed in patients submitted to cardiomyoplasty procedure using the latissimus dorsi muscle graft (LDMG). In four patients who had 1 year of follow-up or more the left ventricular internal dimension in diastole (LVIDd), left ventricular internal dimension in systole (LVIDs), septal-E point separation (E-septum), distance of the mitral valve (E-E'), maximal aortic cuspid separation (MACS) and left atrium dimension (LA) were determined by two-dimensional echocardiogram. With a pulsed Doppler in the aortic root the following parameters were obtained: aortic peak flow (AoPF), velocity time integral (VTI), and ejection period (EP). With the stimulator on, the determinations were done using a ventricle muscle (VM) delay of 25, 75, and 250 msec. RESULTS: No significant differences were observed by Echo determinations between the stimulator off and on. With the supporting contraction of the LDMG the best hemodynamic performance was obtained when the VM delay ranged between 75 and 250 msec. Values with the stimulator off and on were as follows: AoPF: 90.8 +/- 8 cm/sec and 104.5 +/- 9 cm/sec; VTI: 14.8 +/- 2 cm and 19.2 +/- 2 cm; EP: 230 +/- 10 msec and 245 +/- 20 msec. A decrease in the systolic pressure of the pulmonary artery and a decreased functional regurgitation of the mitral and tricuspid valve were observed in the follow-up determinations. All patients showed restricted mitral flows that remained unchanged during the follow-up. CONCLUSIONS: In this group of patients the echo-Doppler showed an improvement of the systolic function of the left ventricle when it is supported by the LDMG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Clinical experience with dynamic cardiomyoplasty.

Dynamic cardiomyoplasty using the latissimus dorsi muscle graft (LDMG) was applied to 11 patients with dilated cardiomyopathy of different etiologies. Our first case was operated on July 1987. All patients were in Functional Class (FC) IV New York Heart Association (NYHA) and had multiple previous admissions in intensive care units for intractable cardiac insufficiency. Two patients died during the procedure, the perioperative mortality was 18%. One patient died of recurrent acute myocarditis at the fourth postoperative month and a second patient died in the sixteenth postoperative month. Both patients were asymptomatic, in FC I-II, and the cause of death was sudden arrhythmia (ventricular fibrillation). The remaining seven patients (63.6%) were in FC I-II and the longest follow-up was 30 months. In all patients, the ejection fraction (EF) by radioisotopic ventriculography improved an average of 50% as well as their ergometric test. Dynamic cardiomyoplasty appears to be a satisfactory alternative for the treatment of patients with severe cardiac insufficiency secondary to dilated cardiomyopathy. Its main advantage seems to be a significant improvement in the quality of life for these patients.

Adult↗
PubMed1990

Effect of supplementing cardioplegic solution with deferoxamine on reperfused human myocardium.

Fourteen randomized patients undergoing myocardial revascularization were divided into group A standard hypothermic cardioplegic solution) and group B (the same cardioplegic solution supplemented with deferoxamine 1000 mg/L). In all patients myocardial biopsy specimens were obtained before ischemia and during reperfusion and were assessed for chemiluminescence (to indirectly determine oxygen-free radical activity) and for electron microscopic studies. Chemiluminescence in group A showed a photoemission of 36.5 +/- 1.5 cpm/mg protein X10(-3) for the preischemia samples and 72 +/- 5.7 cpm/mg protein X10(-3) for the reperfusion samples (p less than 0.01). In the patients who received deferoxime (group B), values for chemiluminescence for preischemia and reperfusion samples were not significantly different. Electron microscopic studies showed a significant increase in grade 4 (severely damaged) mitochondria in reperfusion biopsy specimens from both groups as compared with preischemia samples. However, reperfusion samples from group B showed a better preservation of myocardial cells with marked reduction of grade 4 (severely damaged) mitochondria. These results support the hypothesis that oxygen-free radicals are responsible in part for the production of reperfusion injury in the human heart. They suggest that this mechanism may be at least partially controlled by adding an iron chelating agent such as deferoxime.

Cardioplegic Solutions↗
PubMed1989

Reduction of reperfusion injury with mannitol cardioplegia.

Forty consecutive patients undergoing myocardial revascularization were divided into two equal groups: group 1 received standard cardioplegic solution, and group 2 received a solution containing mannitol, 59.8 mmol/L. In 6 patients in each group, myocardial biopsies were done before ischemia and at the time of reperfusion. Samples were assessed by chemiluminescence to determine oxidative stress and by electron microscopic studies. A significant reduction in atrial arrhythmias was observed in the mannitol group. Chemiluminescence in group 1 showed a photoemission of 37.6 +/- 3.5 cpm/mg of protein x 10(-3) for the preischemia samples and 74.8 +/- 16 cpm/mg of protein x 10(-3) for the reperfusion samples (p less than 0.001). In group 2, the values for chemiluminescence were 37.7 +/- 3.4 cpm/mg of protein x 10(-3) and 40 +/- 6.1 cpm/mg of protein x 10(-3), respectively (p = not significant). Electron microscopic studies showed, for group 1, increased grades of damaged mitochondria in the reperfusion biopsy specimens compared with the preischemia biopsy specimens (p less than 0.01). In group 2, differences for damaged mitochondria were not significant. These results support the hypothesis that mannitol reperfusate significantly reduces myocardial damage in patients undergoing open heart procedures. They also suggest that this protective effect may be in part secondary to the antioxidant property of mannitol, although other mechanisms may have accounted for or contributed to the improved outcome after ischemia.

Biopsy↗
PubMed1989

Synaptonemal complexes analysis in a bull carrying a 4;8 Robertsonian translocation.

Synaptonemal complexes analysis was performed using electron microscopy on surface-spread spermatocytes of a bull heterozygous for the 4;8 Robertsonian translocation. In 19 cells examined, the longest autosomal complex showed kinetochores in a central position whereas the remaining autosomal complexes showed terminal kinetochores. Synapsis in the trivalent appeared complete in all cells, and the trivalents usually showed a CIS configuration. The arm ratio varied from 1.05 to 2.04 with an average of 1.32 +/- 0.43. Out of 47 cells showing X-Y bivalents, 34 showed a small synaptonemal complex at one extremity of the X chromosome, and an unstained gap in the Y chromosome. There was no association between the X-Y bivalent and the trivalent. The absence of association would explain the normal spermatogenesis noted in this bull, in contrast to human and mouse carriers of translocations which show impaired spermatogenesis due to the association between the rearranged chromosomes and the sex vesicle. Further studies involving bulls carrying one or more Robertsonian translocations are needed to determine whether this absence of association is a constant feature in cattle.

Animals↗
PubMed1989

Synchronously stimulated skeletal muscle graft for left ventricular assistance. Case report.

A 56-year-old man with chronic dilatation of the heart caused by cardiomyopathy (New York Heart Association functional class IV) was selected for cardiomyoplasty. The procedure was divided into two separate stages. In stage I the latissimus dorsi muscle was prepared for progressive stimulation. For this purpose two pacing leads were attached to the muscle, one at the proximal and the other at the distal end, and connected to a pulse-train generator, which was placed subcutaneously. A stimulation protocol was initiated in which the requirements of the latissimus dorsi muscle were periodically increased. In stage II the latissimus dorsi muscle was dissected to make a pedicle graft, which was introduced into the thorax and wrapped around the left ventricle. Pacing electrodes were sewn onto the pedicle graft in the same fashion as in stage I. Two sensing electrodes were fixed to the epicardium of the right ventricle, and the four leads were connected to a double-chambered pacemaker. Twelve days later, the pacemaker was programmed to a bipolar mode, VAT, and the latissimus dorsi muscle graft was synchronously stimulated in a 1:1 assist mode. The patient's status improved to New York Heart Association functional class II. Echocardiographic studies showed better contraction of the posterior wall of the left ventricle, as well as reduction in its diameters. Radioisotopic studies demonstrated a significant improvement in hemodynamic parameters. Cardiomyoplasty seems to be an alternative in those patients with severe cardiac insufficiency caused by cardiac dilation owing to cardiomyopathy.

Cardiac Surgical Procedures↗
PubMed1988

Assessment of myocardial oxidative stress in patients after myocardial revascularization.

A homogeneous group of six patients, who underwent coronary artery bypass surgery, was studied to determine the presence of oxidative stress caused by oxygen-derived free radicals and its relationship with reperfusion cell damage. Biopsies were performed before ischemia and 10 minutes after reperfusion. The samples were assayed for hydroperoxide-initiated chemiluminescence and histochemical succinic dehydrogenase activity; the specimens were also studied by electron microscopy. The preischemic biopsy specimens showed chemiluminescence of 40 +/- 2 (cpm/mg protein) x 10(3), normal succinic dehydrogenase activity (grade 4), and generally preserved ultrastructure (necrotic/normal cells 5/100). However, the reperfusion biopsy specimens showed an increase in chemiluminescence to 91 +/- 19 (cpm/mg protein) x 10(3) (p less than 0.025), a partial loss of enzymatic activity (grade 2.6), and ultrastructural changes characterized by mitochondrial swelling and focal myofibrillar disorganization (necrotic/normal cells: 15/100; p less than 0.001). These observations seem to indicate the presence of oxidative stress during reoxygenation, a situation that may play a major role in the genesis of reperfusion injury. It appears to be the first observation relating free radical-induced oxidative stress to reperfusion injury in humans.

Adult↗
PubMed1976

Taxonomical examination and characterization of a methanol-utilizing yeast.

The morphological, cultural, and physiological characteristics are described of a yeast, LI70, which uses methanol as its source of energy and carbon; these characteristics have made it possible to identify the strain as Candida boidinii Ramirez. The identification was confirmed by a DNA-DNA genetic homology of 99.43% with the type strain of C. boidinii. Strain LI70 is not pathogenic.

Animals↗