Recurrence quantification analysis of heart rate variability during continuous incremental exercise test in obese subjects

The present paper concerns a new description of changing in metabolism during incremental exercises test that permit an individually tailored program of exercises for obese subjects. We analyzed heart rate variability from RR interval time series (tachogram) with an alternative approach, the recurrence quantification analysis, that allows a description of a time series in terms of its dynamic structure and is able to identify the phase transitions. A transition in cardiac signal dynamics was detected and it perfectly reflects the aerobic threshold, as identified by gas exchange during an incremental exercise test, revealing the coupling from the respiratory system toward the heart. Moreover, our analysis shows that, in the recurrence plot of RR interval, it is possible to identify a specific pattern that allows to identify phase transitions between different dynamic regimes. The perfect match of the occurrence of the phase transitions with changes observed in the VO₂ consumption, the gold standard approach to estimate thresholds, strongly supports the possibility of using our analysis of RR interval to detect metabolic threshold. In conclusion, we propose a novel nonlinear data analysis method that allows for an easy and personalized detection of thresholds both from professional and even from low-cost wearable devices, without the need of expensive gas analyzers.

Vestibular rehabilitation and 6-month follow-up using objective and subjective measures

CONCLUSIONS

Vestibular rehabilitation improves quality of life by reducing the degree of handicap, improving the ability to perform everyday tasks and providing long-term rehabilitation stability (at 6 months). Recovery of the vestibulo-ocular reflex and the vestibulo-spinal reflex efficiency was proven by the objective results obtained in this study. Vestibular rehabilitation improves both subjective and objective parameters, although no significant correlation between these two indices was found.

OBJECTIVE

To determine the outcome of subjective and objective parameters and long-term rehabilitation stability after vestibular rehabilitation in 43 patients with vestibular disorders.

MATERIAL AND METHODS

The subjective tests used were the Medical Outcomes Study 36-item Short Form, the Dizziness Handicap Inventory and the Activity-specific Balance Confidence scale. The objective tests used were video-oculoscopy, dynamic visual acuity, the Equitest and the Dynamic Gait Index. All indices were evaluated before and after rehabilitation and at follow-up.

RESULTS

All patients showed an improvement in quality of life and a reduction in handicap due to dizziness. Improvement in objective test results was also seen. These results were stable at follow-up. A correlation was found between different subjective measures, but there was no correlation between subjective and objective measures.

Revealing deterministic structures in click-evoked otoacoustic emissions

Click-evoked otoacoustic emissions (CEOAEs) were studied by means of recurrence quantification analysis (RQA) and were found to be endowed with a relevant amount of deterministic structuring. Such a structure showed highly significant correlation with the clinical evaluation of the signal over a data set including 56 signals. Moreover, 1) one of the RQA variables, Trend, was very sensitive to phase transitions in the dynamical regime of CEOAEs, and 2) appropriate use of principal component analysis proved able to isolate the individual character of the studied signals. These results are of general interest for the study of auditory signal transduction and generation mechanisms.

The essential dynamics of Cu, Zn superoxide dismutase: suggestion of intersubunit communication

A 300-ps molecular dynamics simulation of the whole Cu, Zn superoxide dismutase dimer has been carried out in water, and the trajectory has been analyzed by the essential dynamics method. The results indicate that the motion is defined by few preferred directions identified by the first four to six eigenvectors and that the motion of the two monomers at each instant is not symmetrical. The vectors symmetrical to the eigenvectors are significantly sampled, suggesting that, on average, the motions of the two subunits will exchange. Large intra- and intersubunit motions involving different subdomains of the protein are observed. A mechanical coupling between the two subunits is also suggested, because displacements of the loops surrounding the active site in one monomer are correlated with the motion of parts of the second toward the intersubunit interface.

Conductometric properties of human erythrocyte membranes: dependence on haematocrit and alkali metal ions of the suspending medium

The electrical properties of the cytoplasmatic membrane of human erythrocyte cells have been evaluated by means of dielectric spectroscopy measurements in the radiowave frequency range, using the so-called "suspension method". Measurements have been carried out at different volume fractions of the corpuscular phase (the cell haematocrit) in order to investigate the influence of the cell-cell interactions on the electrical parameters (the membrane permittivity epsilon and the membrane conductivity sigma) of the cell membrane and a set of new values are proposed. Moreover, the influence of different alkali metal ions (Na+, K+, Cs+, Li+) on the ion permeation properties of the membrane are investigated and the structural alterations in the membrane organized briefly discussed.

Use of low-frequency electrical impedance measurements to determine phospholipid content in amniotic fluid

In this report we propose a new method for an in vitro test of the foetal lung maturity based on the measurement of the electrical conductivity of the overall amniotic fluid obtained from transabdominal amniocentesis, since this quantity can be linked to a first approximation in a very simple way to the phospholipid content. We have carried out measurements of 85 different samples of amniotic fluid as a function of gestation weeks and we have observed a pronounced change of the electrical conductivity that reflects the increase in the phospholipid concentration occurring at the end of normal pregnancies. The method could be further developed to obtain similar information on in vivo experiments by means of bioelectric impedance tomography, taking advantage of the frequency dependence of the tissue electrical impedance.

Choreoathetosis in acquired immune deficiency syndrome patients with cerebral toxoplasmosis

The aim of our study was to evaluate both the incidence and the pathologic and clinical features of extrapyramidal disorders in a population of acquired immune deficiency syndrome (AIDS) patients with cerebral toxoplasmosis. Of 240 AIDS patients evaluated in the 1985-1994 period, 50 of them were diagnosed to have cerebral toxoplasmosis on the basis of the following criteria: occurrence of specific antibodies, computed tomography and/or magnetic resonance imaging (MRI), and regression of the symptoms after specific therapy. Three of 50 (6%) had hemichoreoathetosis. In the first case, the disorder began as a dyskinesia of the left hand that subsequently spread to the whole ipsilateral arm and assumed the features of choreic athetotic movements. The other two cases were characterized by left hemisomatic distal choreic movements. Therapy with pyrimethamine and sulfadiazine led to a complete recovery of the extrapyramidal signs in two cases and to improvement in the third. According to our observations, the onset of these movement disorders could not be related to the dimension of the lesion or to the edema, but to a specific localization in subthalamic nucleus, in subthalamic/pallidal, and pallidal/thalamic pathways. MRI seems the elective tool to perform a more accurate study of the anatomic areas involved in this pathway and to verify their integrity. Cerebral toxoplasmosis in AIDS can be considered as a new etiopathogenic cause of choreoathetosis.

A dielectric relaxation study on the effects of the antitumor drugs Lonidamine and Rhein on the membrane electrical properties of Ehrlich ascites tumor cells

The effects of the anti-tumor drugs lonidamine and rhein on the plasma membrane electrical properties of Ehrlich ascites tumor cells were investigated and compared. Dielectric relaxation measurements in the radiowave frequency range (10(4) to 10(8) Hz) as well as at higher frequencies (10(4) to 10(9) Hz) were performed and the data elaborated using a "single-shell" fitting procedure. The results obtained in both frequency ranges indicate that membrane conductivity and membrane permittivity are altered by 200 microM Lonidamine while 150 microM rhein induces only very slight variations in these two plasma membrane parameters. The usefulness of the dielectric relaxation technique described here in evaluating antitumor drugs and improving clinical protocols is discussed.

Anti-hepatitis C antibody prevalence among intravenous drug addicts in the Catanzaro area

A higher seroprevalence of anti-HCV antibodies (63.4%) was found in 41 intravenous drug addicts (IVDA) when compared to 220 controls (1.8%). Life style is an important risk factor for HCV transmission among IVDA.

[Myocardial infarct associated with arterial hypertension. Case studies]

An examination of cases of infarct with arterial hypertension in a total series of 173 cases of infarct showed that they more commonly presented as premonitory syndromes and tended to be sited anteriorly (p less than 0.05). Such cases are best treated by reducing sympathetic hypertonia.