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Biomedical subjects

B Martini

Publications and source records attributed to B Martini.

At least 37 records · Page 2Linked to original sources
PubMed1992

Proliferative vitreo-retinal disorders: experimental models in vivo and in vitro.

The aim of the present thesis was to develop, refine, and assess experimental models for the study of proliferative vitreo-retinal disorders. An intravitreal injection of a colloidal solution of microparticles was used in the primate eye to produce pathologic changes including intraocular cell invasion, cell proliferation, neovascularization, collagen synthesis, and tractional retinal detachment. In a separate primate model for laser-induced subretinal neovascularization, the origin and the occurrence of macrophages was evaluated. Examinations were performed using ophthalmoscopy, slit-lamp microscopy, light microscopy, and transmission electron microscopy. Cell cultures were employed to study the effects of vitreous humor and macrophages on the proliferation of cultured retinal pigment epithelial (RPE) cells and cultured fibroblasts using a Coulter counter. Morphologic changes were documented by phase micrography. A quantitative estimation of the extracellular matrix deposition of fibrous proteins by macrophage-modulated RPE cells as well as by vitreous-modulated RPE cells was done using enzymatic digestion and radioactive labeling techniques. A qualitative analysis of the types of collagen that was deposited in the extracellular matrices by vitreous modulated cultures was also made using indirect immunofluorescence. Using a newly developed RPE cell specific monoclonal antibody, the avidin-biotin-peroxidase labeling technique was finally employed to test the phenotypic epitope expression of macrophage-modulated and non-modulated RPE cells. A new experimental in vivo model for pathologic changes that characterize proliferative vitreo-retinal disorders was developed in the primate eye. In the model for laser-induced subretinal neovascularization, macrophages were shown to be principally recruited from the systemic circulation. Using cell cultures, it was found that both macrophage-conditioned medium and vitreous humor, separately or combined, exert mitogenic effects on RPE cells and fibroblasts. The combined effect of the two stimuli was additive, but not synergistic, on both cell lines. When incubated with macrophage-conditioned culture medium or vitreous humor, RPE cells exhibited a metaplastic transformation towards fusiform, spindle-shaped cells that were morphologically indistinguishable from fibroblasts. The extracellular matrices of RPE cells modulated by macrophage-conditioned medium also appeared converted to a more striated pattern as compared to non-modulated controls. The metaplastic transformation of cultured RPE cells reverted when experimental stimuli, macrophage-conditioned medium or vitreous humor, were withdrawn. A new in vitro method for evaluating fibrous protein deposition in the extracellular matrix by RPE cells was also described. RPE cells, that were modulated by macrophage-conditioned medium or vitreous humor, deposited less fibrous proteins per cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Cultures of human retinal pigment epithelium. Modulation of extracellular matrix.

The extracellular matrix of retinal pigment epithelial (RPE) cells is an important component of the fibroelastic membranes formed in proliferative vitreoretinopathy (PVR). These membranes consist of cells intermingled with fibrillar proteins, such as elastin and collagen. Because RPE cells may be exposed to vitreous and serum-derived factors in conditions that lead to PVR, the effects of vitreous and serum on the deposition of fibrillar proteins by RPE cells were studied using radioactive labeling and indirect immunofluorescence techniques. The RPE cells, modulated by combined vitreous and serum into a fibrocytic-like appearance, deposited less fibroelastic proteins per cell. However, as a result of simultaneous cell proliferation, the total deposition of fibroelastic proteins per culture was increased. Indirect immunofluorescence studies suggest that it is type I collagen that is altered in the matrix of these modulated cell cultures. This information is important in pathologic conditions characterized by intraocular cell proliferation and fibroelastic membrane formation; these phenomena are seen in many vitreoproliferative disorders.

Cell Count↗
PubMed1991

Synthesis of extracellular matrix by macrophage-modulated retinal pigment epithelium.

In proliferative vitreoretinopathy, macrophages and retinal pigment epithelial cells are associated with microfibrillar matrix proteins in the vitreous cavity, but the contribution of this extracellular matrix to the pathophysiology is not known. We used radiolabeling techniques on cultured human retinal pigment epithelial cells to correlate the secretion of extracellular matrix proteins with macrophage-induced modulation of cell proliferation and morphologic features. Retinal pigment epithelial cells incubated in a macrophage-conditioned medium assumed fibrocytelike morphologic characteristics, grew faster, and exhibited a decreased cellular release of fibrillar and nonfibrillar matrix components. However, due to a simultaneous greater increase in cell numbers in these modulated cultures, the total production of fibrillar and nonfibrillar matrix components by the culture population was increased.

Cell Division↗
PubMed1991

Coexistence of kent accessory pathway, enhanced AV node conduction, and various conduction disturbances in a young athlete with tricuspid valve dysplasia.

An asymptomatic 19-year-old top-level athlete had electrocardiographic evidence of intermittent cardiac preexcitation and intermittent left bundle branch block. The electrophysiologic study demonstrated the presence of a direct accessory pathway and enhanced atrioventricular node conduction that resulted in infrahisian and intraventricular conduction disturbances. The echocardiogram disclosed tricuspid valve dysplasia.

Adult↗
PubMed1991

Arrhythmia development in a young subject with right ventricular cardiomyopathy (right ventricular dysplasia).

In right ventricular cardiomyopathy the relationship between the progression of structural abnormalities and arrhythmia development is not yet well known. This report describes a case in which severe ventricular arrhythmias appeared 3 years after the demonstration of right ventricular (RV) structural and dynamic abnormalities. In this interval of time structural changes were not detectable with the commonly used diagnostic methods, but endocavitary RV late fractionated QRS potentials appeared suggesting the development of an arrhythmic component of the disease.

Adult↗
PubMed1990

Giant P wave in a patient with right ventricular cardiomyopathy.

A P wave of 7.5 mm in lead I and 12.5 in V1 was detected in a 28-year-old man, with a progressive cardiomegaly since the age of 14 years. At last admission he had minor symptoms, and a systolic murmur consistent with tricuspid regurgitation. The electrocardiogram showed an extremely tall P wave and a QRS of a very low amplitude; T waves were inverted on the precordial leads. These ECG features, and subsequent investigations, were consistent with right ventricular cardiomyopathy with massive tricuspid regurgitation, and right atrial abnormality.

Adult↗
PubMed1990

Monomorphic repetitive rhythms originating from the outflow tract in patients with minor forms of right ventricular cardiomyopathy.

We studied in detail 17 patients presenting with monomorphic repetitive ventricular rhythms having left bundle branch block morphology and right axis deviation. All had an apparently normal heart at physical examination. At chest radiography, three patients had mild cardiomegaly, and at electrocardiography, five patients had inverted T waves beyond V2. Five patients had syncope or near syncope. In seven patients the tachycardia occurred on effort. One patient died suddenly. The patients were extensively investigated, using cross-sectional echocardiography, complete haemodynamic and angiographic studies, electrophysiology and histology, to search for any structural basis of the arrhythmias. Tachycardia was sustained in 8 patients, nonsustained in 3, and consistent with accelerated idioventricular rhythm and repetitive paroxysmal ventricular tachycardia in 5 and 1 patients, respectively. Despite the differences in clinical and arrhythmologic features, similar abnormalities of right ventricular structure and/or wall motion were detected in all patients, consistent with localized forms of right ventricular cardiomyopathy. Different antiarrhythmic drugs were successfully used in twelve patients (the four patients with accelerated idioventricular rhythm were not treated). The patient who died suddenly had previously had a sustained ventricular tachycardia and was being treated by beta-blockade. Postmortem study revealed massive fibro-adipose substitution of the right ventricular free wall and pulmonary infundibulum.

Adolescent↗
PubMed1990

[Electro-vectorcardiographic study of ventricular extrasystole in arrhythmogenic dysplasia of the right ventricle].

The morphology of ventricular extrasystole (VES) in 46 cases of arrhythmogenic dysplasia of the right ventricle (ADRV) was correlated with the point of origin located by intracavitary mapping. The cases concerned 41 of left bundle-branch block (LBB) with various axes on the frontal plane (FP), 4 of right bundle-branch block (RBB), and 5 of atypical morphology (frontal plane shifted inferiorly and increased R from V1 to V6; on the horizontal plane, clockwise rotation of the loop oriented anteriorly and leftward). There is a good correlation with the site of origin: VESs which were LBB in appearance originated in the right ventricle (apex, septum, infundibulum); VESs which were RBB in appearance originated in the apex of the left ventricle, while the atypical VESs started in the upper posterior septum. A study of morphology may therefore also give an indication of the location of the disease.

Adolescent↗
PubMed1990

[Analysis of the mode of transmission of right ventricular dysplasia].

A formal analysis of the mode of transmission of right ventricular cardiomyopathy was performed in seven families with this condition. Ninety-six subjects (81 family members, 15 connected) were studied. The index cases were family members who had died suddenly in their youth with autopsy evidence of massive fibrous-adipose right ventricular myocardial replacement. Pedigree analysis showed that 58 per cent of the family members were affected, with a male predominance (63% of men vs 53% of women). The kindreds were all normal and in none of the families were both parents affected. Carrier states were observed in both males and females and vertical transmission was demonstrated. Clinically, the disease was very variable with some cases showing widespread right ventricular involvement with or without cardiomegaly, and other cases showing localised right ventricular abnormalities. These data are consistent with a congenital disease with an autosomal dominant mode of inheritance with incomplete penetrance and variable expression.

Angiocardiography↗
PubMed1989

Ventricular fibrillation without apparent heart disease: description of six cases.

Since 1977, six patients (five males and one female), aged 14 to 35 years, resuscitated from ventricular fibrillation, were referred to our department for detailed evaluation, after exclusion of major cardiac pathologic conditions. Four patients had a family history of heart disease. Basic ECGs showed sinus rhythm in all of them. PR interval was prolonged in one. Two patients had complete and one had incomplete right bundle branch block. One patient had inverted t waves in V1-3 and late potentials. Three had an upsloping ST-T segment elevation in V1-2. The cardiothoracic index was less than 0.5 in five and 0.50 in one. In one of the five patients studied, the clinical episode of ventricular fibrillation was reproduced by stimulation of the right ventricular outflow tract during electrophysiologic study. Results of cross-sectional echocardiography and angiography showed predominantly structural and wall motion abnormalities of the right ventricle in five patients and slight wall motion abnormalities of the left ventricle in two. Two patients also had mitral and tricuspid valve prolapse. Coronary arteries were normal in all five patients examined. Results of endomyocardial biopsy showed no abnormalities in one patient, fibrosis in two, and fibrolipomatosis in one. Two patients died during follow-up: autopsy was performed in one and results showed right ventricular cardiomyopathy. Thus in five of these selected patients with apparent idiopathic ventricular fibrillation, some abnormalities, predominantly of the right ventricle, were documented only after detailed investigation; however, clinical history and some nonspecific ECG abnormalities were factors in the diagnostic procedure.

Adolescent↗
PubMed1989

Unexpected sudden death during acute myocardial infarction: role of primary electromechanical dissociation.

The causes of death during the acute phase of myocardial infarction were studied in 128 patients. Forty-three of these, who had no clear signs of cardiocirculatory failure, were considered to be cases of sudden and unexpected death. Thirty-two of these patients (74%) had electromechanical dissociation, defined as a sudden disappearance of an effective arterial pressure in the presence of adequate electrocardiographic complexes. Twenty-three patients who had been given this diagnosis were males and 9 females; 53% presented with anterior infarction, 31% with infero-posterior infarction, 3.5% with both anterior and infero-posterior and 12.5% with non-Q wave infarction. A previous episode of infarction was recorded in 31.2% of patients with electromechanical dissociation. Autopsy was performed in 84 patients, 23 of whom died with electromechanical dissociation. Half of the latter cases revealed cardiac rupture (secondary electromechanical dissociation), whereas in the other half death was due to primary electromechanical dissociation. The study stresses the relatively high incidence of this cause of death and the need to differentiate between the two different forms. Although at present the pathophysiology of primary electromechanical dissociation is not completely understood, we believe that recurrence of global or local ischemia may play a more important role than cardiovascular inhibitory reflexes.

Acute Disease↗
PubMed1989

Right ventricular dysplasia: a familial cardiomyopathy?

268 preselected subjects were extensively studied and the diagnosis of right ventricular dysplasia (RVD) was made in 108 living and 18 deceased patients, 35% of cases being familial. Subsequently we studied 72 subjects from nine families in which a case of sudden death had occurred with the autoptic diagnosis of RVD. In 42 out of 72 cases the autoptic (11 patients), clinical-echocardiographic (30 patients) and haemodynamic (15 patients) data supported the diagnosis of RVD. In all but one deceased patient, death was sudden, while in all the living family members we observed ventricular arrhythmias, mostly with left bundle branch block morphology. Both manifest and concealed forms were documented with polymorphic presentation and with clinical-pathologic findings similar to the non-familial RVD cases. This study confirms the presence of a familial form of RVD that is probably more frequent than previously thought. Preliminary data seem to indicate an autosomal dominant inheritance with incomplete penetrance and variable expression.

Arrhythmias, Cardiac↗
PubMed1989

Asystole with syncope secondary to hyperventilation in three young athletes.

We describe three athletes who had syncope after (case 1) or during (cases 2, 3) hyperventilation. During the episode, ECG showed prolonged sinus arrest. Clinical data and noninvasive investigations were normal and the phenomenon was not reproducible. Electrophysiological study after autonomic blockade allowed a prolonged intrinsic heart rate in case 1, and abnormal corrected sinus node recovery time in cases 1 and 2. During follow-up, symptomatic sinus arrest provoked by deep inspiration occurred in case 3. These cases document prolonged asystole of unknown etiology, secondary to hyperventilation, and probably caused by different vagally-mediated mechanisms.

Adolescent↗
PubMed1989

[Incidence of conduction disorders in patients who underwent surgery for hypertrophic obstructive cardiomyopathy].

Thirteen non-consecutive patients, aging 7 to 61 (average 27) years, underwent left ventricular myotomy-myectomy for a severely symptomatic idiopathic hypertrophic subaortic stenosis (IHSS). In all patients the resting ECG before surgery showed P-R less than 0.18 sec, QRS duration less than 0.11 sec, QRS axis ranging from +10 to +80 degrees. In the immediate post-surgical period 3 patients has complete heart block and 1 had 2nd degree type 2 atrio ventricular block. Lesion was infra-Hisian in 3 patients and intra-Hisian in 1 patient. In the remaining 9 patients an immediate post-surgical left bundle branch block appeared; in 3 out of these patients ECG and an electrophysiologic study documented severe infra-Hisian conduction impairments after an average period of 4 years from surgery. During follow-up 3 patients died suddenly.

Adolescent↗
PubMed1989

[Cardiac echinococcosis. Description of a case with cysts localized in the free wall of the left ventricle].

A case of isolated cardiac echinococcosis is reported. A 19-year-old man was hospitalized for chest pain with electrocardiographic pathological Q waves in D1, aVL, V5, V6. Two-dimensional echocardiography and chest computed tomography documented pericardial effusion and an intramyocardial cyst. Casoni's reaction and immunological tests completed the diagnosis of cardiac hydatidosis. The localization and the etiology of the cyst were confirmed during cardiac surgery.

Adult↗