PubMed Health⌕ Search

Biomedical subjects

S Guzzetti

Publications and source records attributed to S Guzzetti.

52 records · Page 3Linked to original sources
PubMed1988

Cerebral complications of coronary by-pass surgery. A prospective study.

A prospective study was undertaken of cerebral complications in 91 patients undergoing coronary by-pass surgery. Patients showing clinically relevant neurological complications had longer pump-times but did not differ in pre-operative variables. Worsening of neurological state correlated with duration of pump-time but not with pre-operative variables. Duration of pump-time appears to be the main predictor of neurological complications after coronary by-pass surgery.

Adult↗
PubMed1987

[Statistical survey of the hourly incidence of acute myocardial infarction: reduction of frequency during the nighttime hours].

The time of onset of acute myocardial infarction was analysed in 245 patients admitted to the Fatebenefratelli Hospital in Milan over 18 months. A significant decrease in the incidence of this pathology (P less than 0.01) was noted between midnight and 6 am. No significant difference was noted over the rest of the day. These results suggest the existence of a period of relative protection against the onset of myocardial infarction during the day.

Humans↗
PubMed1987

Sleeping hours: a relatively protected period for impending myocardial infarction.

We have retrospectively investigated the time of the onset of acute myocardial infarction in 2046 patients admitted to six coronary care units in a two-year period. A significantly reduced number of patients (P less than 0.01) showed the beginning of acute myocardial infarction during the 0 to 6 a.m. period, while, during the remaining periods, no difference in frequency distribution was observed. Our results suggest that an impending myocardial infarction is more likely to occur at certain times of the day than others, suggesting a period of relative protection from onset.

Circadian Rhythm↗
PubMed1987

Effects of verapamil, nifedipine, and dilazep on left ventricular relaxation in the conscious dog.

The cardiac systolic and diastolic effects of the two major calcium blockers, verapamil and nifedipine, were studied and compared with those produced by dilazep, a relatively new vasodilator with calcium blocking properties, in conscious instrumented dogs to avoid the complications of anaesthesia and recent surgery. Mean arterial pressure was reduced by nifedipine and dilazep but not by verapamil, whereas peak left ventricular pressure was reduced only by dilazep and verapamil. Consistent tachycardia occurred, the rate being highest with nifedipine and lowest with dilazep. Left ventricular dP/dt was unaffected by dilazep, reduced by verapamil, and increased by nifedipine; this increase was no longer observed after beta adrenergic blockade. Ventricular relaxation was assessed by calculating the time relaxation constant, tau. Verapamil increased tau significantly only after beta adrenergic blockade, whereas nifedipine and dilazep reduced it both before and after beta adrenergic blockade. These data suggest that reflex beta adrenergic mechanisms may modulate the effects of calcium blockade on both systolic and diastolic performance.

Animals↗
PubMed1986

Lack of association between prodromes nausea and vomiting, and specific electrocardiographic patterns of acute myocardial infarction.

We conducted an observational study on 164 patients consecutively admitted to our coronary care unit in order to evaluate the predictive role of cardiac prodromes nausea and vomiting, in distinguishing a particular electrocardiographic pattern (Q wave versus non-Q wave and localisation) of an acute myocardial infarction. Patients with the prodromes made up 47.0% of all Q wave myocardial infarction and 59.4% in those without Q wave myocardial infarction. Furthermore, patients had nausea and vomiting in 25.0% of all Q wave myocardial infarction and in 31.2% of all non-Q wave infarction. No significant differences were found in the patients who experienced nausea and vomiting in the localisation (anterior versus inferior) of myocardial infarction. Our findings indicate that the cardiac prodromes of nausea and vomiting do not play any particular role in predicting a specific electrocardiographic pattern of acute myocardial infarction.

Electrocardiography↗
PubMed1986

Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dog.

In 57 normal subjects (age 20-60 years), we analyzed the spontaneous beat-to-beat oscillation in R-R interval during control recumbent position, 90 degrees upright tilt, controlled respiration (n = 16) and acute (n = 10) and chronic (n = 12) beta-adrenergic receptor blockade. Automatic computer analysis provided the autoregressive power spectral density, as well as the number and relative power of the individual components. The power spectral density of R-R interval variability contained two major components in power, a high frequency at approximately 0.25 Hz and a low frequency at approximately 0.1 Hz, with a normalized low frequency:high frequency ratio of 3.6 +/- 0.7. With tilt, the low-frequency component became largely predominant (90 +/- 1%) with a low frequency:high frequency ratio of 21 +/- 4. Acute beta-adrenergic receptor blockade (0.2 mg/kg IV propranolol) increased variance at rest and markedly blunted the increase in low frequency and low frequency:high frequency ratio induced by tilt. Chronic beta-adrenergic receptor blockade (0.6 mg/kg p.o. propranolol, t.i.d.), in addition, reduced low frequency and increased high frequency at rest, while limiting the low frequency:high frequency ratio increase produced by tilt. Controlled respiration produced at rest a marked increase in the high-frequency component, with a reduction of the low-frequency component and of the low frequency:high frequency ratio (0.7 +/- 0.1); during tilt, the increase in the low frequency:high frequency ratio (8.3 +/- 1.6) was significantly smaller. In seven additional subjects in whom direct high-fidelity arterial pressure was recorded, simultaneous R-R interval and arterial pressure variabilities were examined at rest and during tilt. Also, the power spectral density of arterial pressure variability contained two major components, with a relative low frequency:high frequency ratio at rest of 2.8 +/- 0.7, which became 17 +/- 5 with tilt. These power spectral density components were numerically similar to those observed in R-R variability. Thus, invasive and noninvasive studies provided similar results. More direct information on the role of cardiac sympathetic nerves on R-R and arterial pressure variabilities was derived from a group of experiments in conscious dogs before and after bilateral stellectomy. Under control conditions, high frequency was predominant and low frequency was very small or absent, owing to a predominant vagal tone. During a 9% decrease in arterial pressure obtained with IV nitroglycerin, there was a marked increase in low frequency, as a result of reflex sympathetic activation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic beta-Antagonists↗
PubMed1985

Analysis of the pressor sympathetic reflex produced by intracoronary injections of bradykinin in conscious dogs.

The reflex hemodynamic effects of intracoronary bradykinin were tested in 20 conscious instrumented dogs. When the experiments were performed after full recovery from surgery and anesthesia, graded doses (10-300 ng/kg) of bradykinin always produced graded pressor responses, in the absence of any pain reaction. At the maximum pressor response obtained with 100 ng/kg, mean arterial pressure rose 28 +/- 3% from 89 +/- 4 mm Hg, left ventricular pressure 20 +/- 3% from 121 +/- 2 mm Hg, heart rate 30 +/- 4% from 88 +/- 5 beats/min, rate of change of left ventricular pressure 18 +/- 3% from 2812 +/- 65 mm Hg/sec (P less than 0.01). Higher doses of bradykinin did not produce greater responses. The magnitude of the response was similar when the injection was performed in either the left anterior descending (change in mean arterial pressure 29 +/- 3%) or circumflex (change in mean arterial pressure 27 +/- 2%) coronary artery. The reflex nature of the response was proved by its disappearance after appropriate pharmacological blockades; moreover, after vagotomy, the pressor rise was maintained, the heart rate response was reduced (change in heart rate 10 +/- 2%), and the inotropic response was enhanced (rate of change of left ventricular pressure 24 +/- 3%). This suggested that the afferent pathway of the pressor reflex was in the sympathetic nerves and that a subordinate vagal depressor reflex was also operative. No pain reaction was obtained even when injecting very large amounts (1000-2000 ng/kg) of bradykinin, which, instead, induced arterial hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1984

Power spectral density of heart rate variability as an index of sympatho-vagal interaction in normal and hypertensive subjects.

Instantaneous heart rate reflects sympatho-vagal influences on pace-maker activity. Hence computer analysis of heart rate variability might provide a quantitative index of that interaction. The power spectral density (PSD) estimate of heart rate variability was obtained in normal controls and in uncomplicated hypertensives, both at rest and during a non-hypotensive sympathetic stimulus (tilting). In normal controls PSD shows three major peaks of frequencies P1 = 0.07, P2 = 0.12, P3 = 0.25 cycles/beat. P1, which is associated with sympathetic activity, represents only a minor portion of total variability at rest, while becoming predominant with tilting. P2 and P3 are associated with vagal activity, and represent the major part of variability at rest, while they are reduced by tilting. In hypertensive patients PSD is altered, as P1 is already predominant at rest and increases only slightly with tilting. Thus PSD of heart rate variability is capable of detecting an early alteration in sympatho-vagal balance of cardiac control present in uncomplicated hypertension.

Adult↗
PubMed1983

[Difference in the behavior of T-lymphocyte populations in heroin and methadone addicts].

An assessment of T-lymphocyte populations was performed in two groups of drug addicts by the technique of monoclonal antibodies. Group I was composed of 11 asymptomatic heroin addicts, group II being in heroin withdrawal program from at least six months. Homosexual subjects, partners of patients with AIDS and patients with liver abnormalities or with recent infectious diseases were excluded from the present study. In all the examined subjects the antibody pattern to Toxoplasma gondii, Epstein-Barr virus, Cytomegalovirus was either negative or slightly positive as after old infections. All subjects were HBsAg negative and HBsAb positive. Group I patients showed a significant inversion of OKT4/OKT8 ratio (p less than 0.01), due to a reduction in T helper lymphocytes (p less than 0.05) and an increase in T suppressors (p less than 0.05). Both groups showed a not significantly different proliferative response to Phytohemagglutinin (PHA) and Concanavalin A (Con A), although 8 out of 11 patients of group I exhibited a reduced proliferative response to PHA. Group I patients also showed a reduced proliferative response to Pokeweed mitogen (PWM). These results might suggest an involvement of B-lymphocytes in immunological changes of heroin addicts. In group II patient all the examined variables, OKT4/OKT8 ratio, absolute number as well as percentage of T-lymphocytes subpopulations and proliferative responses to the employed mitogens, resulted in the normal range. These data seem to exclude that methadone, in contrast with heroin, may induce a cell-mediated immunodepression.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1981

A sympathetic hypertensive reflex from the heart of conscious dogs.

1. The aim of the present experiment was to study in conscious animals the effect of chemical stimulation of cardiac sensory innervation by bradykinin, a physiological substance known to activate both vagal and sympathetic cardiac sensory nerve endings, at doses devoid of systemic haemodynamic effects. 2. In conscious dogs with implanted catheters bradykinin (100 ng/kg) injected into a cannulated branch of the left coronary artery induced significant (P less than 0.01, n = 5) reflex increases in mean arterial pressure and heart rate as well as increases in left ventricular pressure, left ventricular dP/dt max. and coronary blood flow. 3. These changes were obtained in the absence of pain reactions. 4. The concept, derived from experiments on anaesthetized animals, that chemical stimulation of the intact sensory supply of the heart always elicits a cardiovascular depressor reflex mediated by cardiac vagal afferents has to be modified, as pressor sympathetic reflexes may occur after an appropriate stimulus to the fully innervated heart of conscious dogs.

Animals↗
PubMedDate not supplied

Cardiovascular reflexes mediated by sympathetic afferent fibers.

In this paper the experimental evidence supporting the hypothesis that excitatory sympathetic reflexes may participate in the tonic control of the cardiovascular system is discussed. Positive feedback pressor sympathetic reflexes can be obtained with physiological distensions of the descending thoracic aorta in conscious dogs with all nerves intact in absence of any pain reaction. These excitatory reflexes interact with supraspinal regulatory mechanisms, inhibitory in nature. A massive excitation of cardiac sympathetic afferents, produced by intracoronary injections of bradykinin, also elicits a pressor reflex, without pain reactions. In the absence of anesthesia and recent surgery, the cardiovascular excitatory reflexes, subserved by sympathetic afferent fibers, can easily prevail. We suggest that negative and positive feedback mechanisms interact continuously to achieve the most adequate neural cardiovascular control.

Animals↗
PubMedDate not supplied

Ultrastructural studies in the lytic phase of progressive multifocal leukoencephalopathy in AIDS patients.

Brain fragments from eight cases (four autopsies and four biopsies) of patients with acquired immune deficiency syndrome (AIDS) with JC virus (JCV) lytic infections were examined ultrastructurally. Particular efforts were made to look for virions and their subcellular distribution in cells not usually involved by papovavirus infection. The cellular and subcellular distribution of virions was investigated with emphasis on cell types not normally associated with papovavirus infection. The pattern of JCV infection was as follows: 1) oligodendrocytes; nucleus only, 7 cases; cytoplasm only, no cases; 2) astrocytes (normal and "bizarre"); nucleus and cytoplasm, two cases; cytoplasm only, four cases; 3) macrophages; nucleus and cytoplasm, one case; cytoplasm only, four cases; and 4) neurons; nucleus and cytoplasm, two cases; cytoplasm only, three cases. Perivascular, endothelial, ependymal, and microglial cells were never infected. Our ultrastructural data indicate that cell types other than oligodendrocytes can be involved productively by JCV in the lytic phase of progressive multifocal leukoencephalopathy (PML) in AIDS patients. Neuronal cells, especially, can be infected productively by the JCV, and this should be considered in clinical interpretation of cortical symptoms and signs in suspected or proven cases of PML.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Adrenal metastasis of choroidal melanoma: a case report].

We report on the case of a 32 years old man submitted to right eye enucleation twelve years before for a choroidal melanoma. We observe a metastases located in the left adrenal gland. The blood-tests, the TAC of the abdomen did not show other localizations, while during laparotomy were discovered metastases in the pancreas and in the omentum. In this case, the age of tumor's development, the age of clinical manifestation, the period between the enucleation and the appearance of the metastases and their localization are exceptions to the normal biological behaviour of the choroidal melanoma.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Recurrence of goitre after operation in euthyroid patients.

OBJECTIVE: To try and resolve some of the problems associated with the treatment of goitre in euthyroid patients. DESIGN: Retrospective open study SETTING: University hospital SUBJECTS: 106 out of a total of 161 euthyroid patients operated on for goitre from 1974-1988. Those who underwent total thyroidectomy (n = 14), in whom the histological diagnosis was thyroiditis (n = 10), or who were lost to follow up (n = 31) were excluded from the study. MAIN OUTCOME MEASURES: Recurrence of goitre, and correlation with type of operation, age, and histological type. RESULTS: 62 Patients underwent unilateral, and 44 bilateral resections. There were 24 recurrences (23%), 13 of which were subclinical; 19 occurred after unilateral, and 5 after bilateral, resections (p = 0.02). There were no significant associations between recurrence and age or histological type. CONCLUSION: Subtotal thyroidectomy is the treatment of choice for goitre in euthyroid patients.

Adenoma↗