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Biomedical subjects

S Strano

Publications and source records attributed to S Strano.

At least 37 records · Page 2Linked to original sources
PubMed1997

A multivariate time-variant AR method for the analysis of heart rate and arterial blood pressure.

This paper approaches the problem of short-term mechanisms that regulate heart rate and blood pressure variability signals, by focusing the evident changes of their frequency content during transients (dynamic situations in which the behaviour of these control mechanisms may vary on a beat-to-beat basis). In this study, we suggest an autoregressive time-variant spectral estimation method, which is able to follow such dynamic changes in the signals. This method has also been extended to a multivariate approach in order to take into account more than one process at a time, and to assess the mutual influences between the different controlling systems. The algorithms successfully tested on simulated series have also been used to analyse series recorded during a vaso-vagal syncope episode in a tilt manoeuvre and a physical exercise stress test protocol. The results show how this method is able to follow the changing dynamics of the signals on the basis of a closed-loop model of their interaction on a beat-to-beat basis. After a proper identification procedure of the blocks forming the model, it is possible, therefore, to obtain the classical spectral parameters and the gain of the transfer function between the signals. Such parameters constitute new time series that describe the physiopathology of the cardiovascular control systems, even during non-stationary epochs.

Algorithms↗
PubMed1997

Mapping pathophysiological features of breast tumors by MRI at high spatial resolution.

Magnetic resonance imaging (MRI) is a noninvasive method that reveals anatomical details in vivo and detects lesions for diagnosis. Although standard breast MRI cannot clearly delineate breast cancer, contrast-enhanced MRI enables the detection of breast masses with high sensitivity. Dynamic studies demonstrated that malignant lesions were characterized by a faster signal enhancement rate than benign ones. Dynamic MRI of human breast cancer in mice revealed high heterogeneity in the distribution of contrast-enhanced curves and derived pathophysiological features, indicating the importance of high spatial resolution. With clinical MRI, it is difficult to achieve simultaneously high spatial and temporal resolution. In previous dynamic studies, the emphasis was on high temporal resolution and mainly empiric analyses. We describe here a new model-based method that optimizes spatial resolution by using only three time points, and yet characterizes tumor heterogeneity in terms of microvascular permeability and extracellular fraction. Mapping these pathophysiological features may aid diagnosis and prognosis assessment, while the high spatial resolution may improve the capacity to detect smaller lesions. The method was tested in human breast tumors implanted in mice and in a limited number of benign and malignant breast lesions of patients.

Animals↗
PubMed1997

BCL-2: the pendulum of the cell fate.

The homeostasis of normal tissues is a balance between cell proliferation and cell death. Alterations of both pathways contribute to a clonal expansion of cancer cells. Bcl-2 and its family play an important role in the regulation of the apoptotic pathway. Apoptosis or programmed cell death is an active form of cell suicide that is characterized by specific morphological and biochemical events. These include cleavege of genomic DNA into oligonucleosome-length DNA fragments by endonucleases, chromatin condensation and marginalization, nuclear fragmentation, plasma membrane blebbing, and cell shrinkage. Though the role of apoptosis is clearly defined in the maintaining of physiological tissue homeostasis, several pathological conditions and external factors cause apoptosis. Anticancer drugs and radiation, two of the most important tools in the cancer treatment, cause apoptotic cell death. The understanding of the mechanisms underlying the regulation of the apoptosis in response to different types of DNA damage might provide relevant information to improve cancer treatment. In this review we mainly discuss bcl-2 and its partners in human cancers and how their disregulation might contribute to the development and the difficult treatment of cancer.

Animals↗
PubMed1996

Power spectrum analysis contribution to the detection of cardiovascular dysautonomia in multiple sclerosis.

In multiple sclerosis (MS) autonomic cardiovascular dysfunction is an uncommon, but potentially dangerous event, to which studies of spectral analysis of heart rate variability have not been applied, yet. MATERIAL AND METHODS--We studied 16 patients with definite MS (11 women and 5 men, mean age 30.3 +/- 7.4 yrs., mean EDSS 2.06 +/- 1.42) and 16 sex- and age-matched healthy controls. Besides cardiovascular reflex tests (valsalva manoeuvre, deep breathing, lying to standing, Blood Pressure response to standing and sustained handgrip), each underwent spectral analysis of the R-R interval short-term variability at rest and after tilting, to detect three components: very low frequency (VLF), low frequency (LF) and high frequency (HF). A recent brain MRI was obtained from patients, to compare plaque characteristics with spectral parameters. RESULTS--At cardiovascular reflexes, only four patients (25%) showed an impairment, mostly of a mild degree. VLF and LF at rest were lower in MS subjects than in controls (p < 0.01). No significant correlation was found between spectral parameters and lesion area or localization as detected on MRI. CONCLUSIONS--Spectral analysis could usefully flank reflex tests to detect autonomic subclinical cardiovascular abnormalities.

Adult↗
PubMed1996

Cardiac autonomic dysfunction in relapsing-remitting multiple sclerosis during a stable phase.

The autonomic cardiovascular system was studied by means of autonomic tests and heart rate variability related to body movements during sleep, in 20 patients with relapsing-remitting multiple sclerosis in a stable phase and in 9 normal subjects. Responses to autonomic tests in multiple sclerosis and control subjects were similar. Heart rate variability, instead, showed a lower degree of adaptability in patients with multiple sclerosis than in controls during sleep, because of sympathetic system dysfunction. No significant correlation between magnetic resonance lesions and cardiovascular sleep indexes was found.

Adult↗
PubMed1995

Sympathetic-parasympathetic activation during spontaneous attacks of cluster headache: evaluation by spectral analysis of heart-rate fluctuations.

Twenty-four hour ECG Holter and blood-pressure monitorings were performed in eight patients suffering from cluster headache. Spectral analysis of heart-rate fluctuation was used to assess the autonomic balance under basal conditions, after head-up tilt, and during a spontaneous attack. Normal autonomic balance was found at rest and during sympathetic activation obtained with head-up tilt in the interparoxysmal period. Before the onset of headache, an increase in the low-frequency (LF) component of the power spectrum was apparent in all patients. This sign of sympathetic activation was followed by an increase in the high-frequency (HF) component that developed about 2000 beats after the onset of headache and rapidly overcame the LF component until the end of pain. Significant differences were found when comparing the spectral parameters [total spectral values (TP), power of the LF and HF components and LF/HF ratio] obtained before, during and after headache. During the attack, blood pressure increased and heart rate decreased in all subjects. There appears to be a primary activation of both sympathetic and parasympathetic functions in cluster headache attacks. The sympathetic component seems to be involved mostly in the development of the attack, whereas the parasympathetic activation seems to occur, following the onset of the attack, independently of the pain.

Adult↗
PubMed1992

Nocturnal headache-hypertension syndrome: a chronobiologic disorder.

The study of blood pressure (BP) monitoring in essential hypertensive patients recurrently suffering from nocturnal headache revealed a rhythmic elevation of sphygmomanometric values during the night. Such a finding was not detected in essential hypertensive patients suffering from occasional headache. The nocturnal elevation of BP was seen to be paralleled by the circadian peak of heart rate, suggesting that the disorder is a systemic phenomenon. Importantly, the headache episodes were seen to disappear after antihypertensive therapy that was adjusted to lower the nocturnal increase of BP. The therapeutic results suggested that the nocturnal headache was dependent on the phasic elevation of BP. The beneficial effects further suggested that the nocturnal headache and the nocturnal elevation of BP may represent a particular syndrome with a cause-effect relationship. The term "nocturnal headache-hypertension syndrome" is proposed.

Adolescent↗
PubMed1992

[Modification of the sympatho-vagal interaction in mitral valve prolapse syndrome. Evaluation of heart rate variability by spectrum analysis].

To determine whether clinical manifestations in patients with mitral valve prolapse (MVP) are associated with altered sympatho-vagal tone, 46 patients (mean age 27 +/- 6, range 20-45 years; 18 males and 28 females) were studied by power spectrum analysis of RR variability. Patients were divided in 2 groups, according to echocardiographic criteria: Group A: 11 patients with classical MVP; Group B: 35 patients with non classical MVP. These patients were compared with 30 healthy subjects (Group C) well matched for age, body surface area and heart rate. Our findings indicate that at rest there is a significant difference in the high-frequency component between Group A and Group C. Similarly, during the increase in sympathetic activity induced by 70 degrees head-up tilt all groups showed an increase in the low-frequency component, that was more evident in Group A. The data generated from our laboratory suggest that mitral regurgitation (Group A) is a probable cause of vagal tone increase and that there is an adaptive long-term mechanism towards sympathetic conditions. In addition, probably the normalization, demonstrable by the effect of sympathetic activity in tilt, can mask a dysfunction that may be differently evoked.

Adult↗
PubMed1991

Effect of stress on cardiovascular regulation in neurological diseases with dysautonomia.

Ten patients with Multiple Sclerosis (MS) and ten with Myotonic Dystrophy (MD) underwent an evaluation of cardiovascular reflexes by classic tests, tilt table test and mental stressors. Sympathetic and parasympathetic changes were detected by classical tests in MS patients. Mental stressors appeared able to reveal blood pressure control impairment in MD patients. Lower differential blood pressure was observed during mental stressors administration in MS with brainstem lesions at MRI.

Adult↗
PubMed1991

[Noninvasive evaluation of left ventricular function in alcoholics before and after suspension of ethanol abuse].

It is known that chronic alcoholism causes morphological changes of the myocardium before the development of a specific dilated cardiomyopathy. We studied a group of chronic alcoholics, with normal arterial pressure and without clinical evidence of liver cirrhosis, to evaluate left ventricular function, both before and after withdrawal of ethanol. A M-B mode echo recording of the left ventricle and left ventricular inflow Doppler velocimetry with carotid pulse tracing was performed in each patient within 24 hours of the last alcohol consumption and after a period of abstinence at least 3 weeks. We analysed parameters of left ventricular systolic and diastolic functions, in comparison with a group of normal subjects well matched for age, body surface area and heart rate. The results showed that, in the group of alcoholics, a cardiac hypertrophy exists with increased left ventricular mass and normal parameters of left systolic ventricular function, but with altered ratio PEP/LVET. This last result is the consequence of an abnormal left diastolic ventricular function, as demonstrated from the analysis of the Doppler indexes of left ventricular filling (lower ratio E/A). Left ventricular inflow Doppler velocimetry showed different results in alcoholics and control subjects in the early diastolic flow velocity peak (61 +/- 12 vs 84 +/- 8) and in the peak flow velocity in the atrial contraction phase (62 +/- 10 vs 40 +/- 5.6). We have not observed any change of the echocardiographic parameters after the short period of alcohol withdrawal. We advance the hypothesis that there is an altered diastolic function depending, not only on the hypertrophy of the myocardium, but also on the myocardial interstitial involvement caused by ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Transhiatal blunt esophagectomy.

The operation of transhiatal esophagectomy has been revived in recent years, and several series have reported upon some of the advantages of this procedure over esophagectomy by way of a thoracotomy. Because part of the technique involves a "blind" dissection, it is important that the surgeon is completely familiar with the anatomic relations of the esophagus. A careful anatomic review of these relations was undertaken and important anatomic landmarks have been highlighted with the aid of anatomic dissection. Areas of anatomic fixation are found particularly at the tracheal bifurcation, the dome of the right pleura and the arch of the aorta. The right pleura also crosses the midline between the levels corresponding to the fifth and tenth thoracic vertebrae, and at the eighth thoracic vertebra, there is close proximity of pleurae. A better appreciation of these anatomic features will help the surgeon to decrease the morbidity of the transhiatal esophagectomy.

Esophageal Neoplasms↗
PubMed1987

Pressor effects from daily events and laboratory complex stimuli relating personality factors.

Our preliminary research has attempted to establish a series of methods to study the complex interactions occurring between pressor reactivity and personality profile. Ten untreated mild hypertensives (age 42.9 +/- 8) without damaged target organs were recruited from an outpatient hypertension center along with an equal number of normotensive volunteers (age 38.2 +/- 8.1). We performed a sequence of stressor types under laboratory conditions (sensory perceptual activities, psychomotor responses, and cognitive behavior) following an order ranging from inferior levels to superior levels of systemic integration. The subjects also underwent a 24-h automatic noninvasive blood pressure recording which took into account the situational reactivity. They filled in MMPI and STAI questionnaires before and after the stressor batteries. Only the sensory-perceptual test (Stroop color test modified), the arithmetic test, and the psychomotor test provoked a significant increase in blood pressure and, in the latter test, also a significant increase of the heart rate. The test batteries' mean differences were not significant between the two groups. Similarly, the answers to the trait-anxiety questionnaires did not allow us to make a substantial division between normotensive and hypertensive subjects. On the contrary, the situational anxiety questionnaires showed a significant difference in the score reading preceding and following a task performed by the hypertensive subjects. We observed significant differences for both systolic and diastolic 24-h blood pressure data in transition from a working situation to the sleeping period. However, there was not a significant difference in hypertensive blood pressure readings recorded during work and at home.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗