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Biomedical subjects

Sergio Cerutti

Publications and source records attributed to Sergio Cerutti.

25 records · Page 2Linked to original sources
PubMed2003

The role of 3' UTRs in the mechanisms for segregating mitochondrial proteins.

The mitochondrial proteome, meant as the collection of proteins localized in the mitochondrion, whose fundamental function is the energy production for the life of the cell, is estimated to be constituted by at least 1000 proteins. Since the mitochondrial genome codes only for 13 polypeptides, in practice all of them are coded by nuclear genes and are imported in the mitochondrion by means of a sophisticated mechanism of sorting that is not completely known. Most classified mitochondrial proteins are synthesized as precursors with an amino-terminal extension (leader peptide), provided with peculiar physical and structural characteristics that are responsible for the recognition and import system. However, there is experimental evidence that complementary or alternative import systems exist. In particular, the 3' UnTranslated Regions (UTRs) of the mRNAs may be involved, through their secondary structure, in the mechanisms of recognition and localization. In this paper, the information content of different human mRNA sequences has been analyzed, and the results show that a significative short-term correlation exists in the 3' UTR sequences of the mRNA's coding for the proteins provided with leader peptides, probably representing the structural constraints that are necessary to the sorting machinery.

3' Untranslated Regions↗
PubMed2002

Hypertension-related hypoalgesia, autonomic function and spontaneous baroreflex sensitivity.

OBJECTIVE: The mechanisms involved in the relationship between pain perception and hypertension are poorly understood. This study has sought to investigate whether the spontaneous baroreflex sensitivity and the autonomic nervous system balance are related to hypertension-associated hypoalgesia. METHODS: In the morning, 73 untreated male subjects (45 hypertensives, 28 normotensives) were submitted to a simultaneous recording of electrocardiographic and blood pressure signals in resting condition. The tracings were analysed off-line to evaluate the spectral components of the low frequency (LF) and high frequency (HF) powers (autoregressive algorithm; LF/HF ratio used in subsequent analysis as an index of sympathovagal balance), and the alphaLF (alphaLF), an index of baroreflex sensitivity. After the rest period, the subjects underwent dental pain perception evaluation (pulpar tester: test current increasing from 0 to 0.03 mA, expressed in relative Units) to determine the dental pain threshold and tolerance. Afterwards, a 24-h ambulatory blood pressure monitoring was performed. RESULTS: A significant relationship was observed between alphaLF and pain threshold (r = -0.34; p = 0.003). When a multivariate analysis was computed to control for age, 24-h systolic pressure and LF/HF ratio, alphaLF was a predictive independent factor associated with pain threshold (model p = 0.019; r = -0.31; p = 0.025). Moreover, the 24-h systolic pressure was independently associated with pain threshold (model p = 0.019; r = 0.30, p = 0.031). The relationship between alphaLF and relative tolerance was not statistically significant. When the association between the LF/HF ratio and pain sensitivity was assessed as a secondary endpoint, no significant relationship was observed. Since no significant interaction was found, the effect of alphaLF and LF/HF ratio on pain perception was assumed to be similar in normotensive and hypertensive subjects. CONCLUSIONS: The relationship found between unstimulated baroreflex sensitivity and pain threshold suggests a modulation of pain perception by baroreflex pathways in hypertension-associated hypoalgesia. In a baseline condition, the autonomic nervous system balance does not seem to influence pain sensitivity.

Adult↗
PubMed2002

A wavelet packets decomposition algorithm for quantification of in vivo (1)H-MRS parameters.

In this paper a novel method for the extraction of magnetic resonance spectroscopy (MRS) parameters is presented. The method applies the traditional time-domain linear prediction singular value decomposition (LPSVD) on the set of orthonormal sub-signals obtained by wavelet packets (WP) decomposition of the original free induction decay (FID) signal. Using the properties of WP the desired, optimal, sub-band FID decomposition is obtained and used to progressively separate the different metabolic components in distinct sub-bands. A pseudo-optimal WP tree is obtained using the minimum description length (MDL) criteria. The proposed algorithm preserves all the advantages of the traditional LPSVD method, but the WP decomposition considerably improves the LPSVD performances in the presence of noise. The paper addresses this aspect in details by comparing the innovative sub-band and the traditional full-band approaches. Algorithms are tested on simulated signals that mimic real MRS data.

Algorithms↗
PubMed2002

Biomedical signal processing and modeling in cardiovascular systems.

This article revisits the subject of short-term heart-rate and arterial-pressure variability from the perspective of model structures that can be useful in defining signal processing algorithms. We draw a general scheme of the oscillation sources and interactions that contribute to cardiovascular control mechanisms and highlight the elements that were considered in different modeling works. The origin, superposition, and interaction of respiratory high-frequency (HF) and vasomotor low-frequency (LF) rhythms is presented as the integration of supraspinal and spinal circuits, vasomotor activity, and pressure control loops. We analyze in detail the necessity of considering all relevant interactions for the algorithms designed to estimate the baroreflex sensitivity. We also pinpoint the components of cardiorespiratory coupling in relation to the analysis of data from the acoustic quantification of the left ventricular volume. Finally, we analyze the tendency to produce complex behaviors even in extremely simplified systems involving interactions between oscillatory mechanisms.

Animals↗
PubMed2002

Time-frequency and time-varying analysis for assessing the dynamic responses of cardiovascular control.

Time-frequency or time-variant methods have been extensively applied in the study of the heart-rate variability (HRV) signal. In fact, the frequency content of HRV signal has a strong correlation with the control system assessing heart rate. In particular, the power related to the low-frequency (LF) and high-frequency (HF) components have been demonstrated to correlate to the action of sympathetic and parasympathetic branches of the autonomic nervous system. However, the analysis is restricted to stationary conditions, unless time-frequency methods are employed for detecting dynamic changes that may occur during physiological and pathological conditions. This article reviews the most diffused tools for time-frequency analysis, starting from linear decomposition of the signal (including short-time Fourier transform and wavelet and wavelet packet decomposition), to quadratic time-frequency distributions (including Wigner-Ville transform and Cohen's class of distributions), and finally to adaptive or time-variant autoregressive (AR) models, in both the mono- and bivariate forms. In the past few years, these approaches have been applied in several studies related to cardiovascular responses during nonstationary pathophysiological events. Among them, we will recall and discuss myocardial ischemia (spontaneous or induced), drug infusion, rest-tilt maneuver and syncope, neurophysiological, and sleep investigations.

Animals↗