Rome, Italy
Rome, Italy

Time filter

Source Type

Moleti A.,University of Rome Tor Vergata | Mohsin Al-Maamury A.,University of Rome Tor Vergata | Bertaccini D.,University of Rome Tor Vergata | Botti T.,University of Insubria | Sisto R.,INAIL Research
Journal of the Acoustical Society of America | Year: 2013

Time-domain numerical solutions of a nonlinear active cochlear model forced by click stimuli are analyzed with a time-frequency wavelet technique to identify the components of the otoacoustic response associated with different generation mechanisms/places. Previous experimental studies have shown evidence for the presence of at least two components in the transient otoacoustic response: A long-latency response, growing compressively with increasing stimulus level, and a shorter-latency response, characterized by faster growth. The possible mechanisms for the generation of the two components are discussed using the results of the numerical simulations. The model is a one-dimensional (1-D) transmission line model with nonlinear and nonlocal active terms representing the anti-damping action of the "cochlear amplifier." The dependence on the stimulus level of latency and level was measured for the different components of the response. The generation mechanisms/places of the different components were identified by varying the stimulus level and by turning off the cochlear roughness in well-defined cochlear regions. The results suggest that reflections from roughness coming from basal regions of the cochlea may give a relevant contribution to the early otoacoustic response, whereas nonlinear mechanisms seem to produce a much smaller additional contribution. © 2013 Acoustical Society of America.


Moleti A.,University of Rome Tor Vergata | Botti T.,University of Insubria | Sisto R.,INAIL Research
Journal of the Acoustical Society of America | Year: 2012

This study focuses on the theoretical prediction and experimental evaluation of the latency of transient-evoked otoacoustic emissions. Response components with different delay have been identified in several studies. The main generator of the transient response is assumed to be coherent reflection from cochlear roughness near the resonant place. Additional components of different latency can be generated by different mechanisms. Experimental data are re-analyzed in this study to evaluate the dependence of the latency on stimulus level, for each component of the response, showing that previous estimates of the otoacoustic emission latency were affected by systematic errors. The latency of the emission from each generator changes very little with stimulus level, whereas their different growth rate causes sharp changes of the single-valued latency, estimated as the time of the absolute maximum of the bandpass filtered response. Results of passive linear models, in which gain and bandwidth of the cochlear amplifier are strictly related, are incompatible with the observations. Although active linear models including delayed stiffness terms do predict much slower dependence of latency on the stimulus level, a suitable nonlinear model should be designed, capable of decoupling more effectively the dependence on stimulus level of amplitude and phase of the otoacoustic response. © 2012 Acoustical Society of America.


Moleti A.,University of Rome Tor Vergata | Sisto R.,INAIL Research
Proceedings of Forum Acusticum | Year: 2014

Otoacoustic emissions are conveniently represented in the time-frequency domain, where the cochlear scaling symmetry, and its breaking, manifest themselves in a particularly clear fashion. Scale-invariance means that the physics of the cochlear mechanisms is independent of frequency, so the same behavior is found at different frequency scales, in the corresponding, longitudinally shifted, cochlear regions. Full scale-invariance would imply constant phase of the BM vibration for all frequencies at the corresponding cochlear places, and cochlear characteristic delay times scaling as the reciprocal of frequency. The constant phase of the DPOAE generator component is a consequence of the scaling symmetry and of the wave-fixed nature of the nonlinear distortion OAE generation mechanism. The approximately inverse relation between SFOAE phase gradient delay and frequency is expected instead as a consequence of the place-fixed (therefore, symmetry breaking) nature of the roughness reflection mechanism. In the time-frequency representation of the OAE response it is possible to identify a family of curves along which the scaling symmetry predicts one would find the same OAE physical generation mechanisms and corresponding equivalent generation places at different frequencies and corresponding delays. Another family of curves can also be identified, orthogonal to the first ones, along which different physical mechanisms are aligned at different frequencies, relative to the same cochlear place. This representation helps achieving an immediate and meaningful theoretical interpretation of the OAE experiments, and designing optimal filtering strategies.


Tranfo G.,INAIL Research | Papaleo B.,INAIL Research | Caporossi L.,INAIL Research | Capanna S.,INAIL Research | And 4 more authors.
International Journal of Hygiene and Environmental Health | Year: 2013

The main objective of this study was to determine the average concentrations for the metabolites of the four more common phthalates, industrial chemicals widely used in commercial products and potential endocrine disruptors, in the urine of a control population living in Central Italy. The study population consisted of 157 healthy subjects, not occupationally exposed to phthalates (74 males and 83 females). Urinary levels of the analytes were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) with isotopic dilution. The reference values (geometric mean) for males and females were estimated for each metabolite:. Females: for MEP was 72.94 μg/g creatinine (CI 95% 3.63-149.51), for MEHP was 3.37 μg/g creatinine (CI 95% 1.85-4.89), for MEHHP was 12.74 μg/g creatinine (CI 95% 9.45-22.19), for MnBP was 20.26 μg/g creatinine (CI 95% 8.17-28.43) and for MBzP was 14.74 (CI 95% 2.94-17.68). Males: for MEP was 56.35 μg/g creatinine (CI 95% 2.32-110.39), for MEHP was 2.80 μg/g creatinine (CI 95% 1.08-4.52), for MEHHP was 10.77 μg/g creatinine (CI 95% 6.18-16.95), for MnBP was 17.59 μg/g creatinine (CI 95% 5.72-29.45) and for MBzP was 16.44 (CI 95% 7.90-29.45).To obtain reference values for these chemicals is without doubt an important topic for evaluate the exposure of population and their possible health effects. Information from different geographical areas are important to understand the real different background concentrations. © 2012 Elsevier GmbH.


Carbonari D.,INAIL Research | Proietto A.,INAIL Research | Fioretti M.,INAIL Research | Tranfo G.,INAIL Research | And 3 more authors.
Toxicology Letters | Year: 2014

This study investigated the effect of polymorphic genes GSTT1, GSTM1, GSTA1, EHPX1, NQO1, CYP2E1, CYP1A and MPO on the urinary concentrations and ratio (R) of the benzene metabolites trans,. trans-muconic acid (t, t-MA) and S-phenyl mercapturic acid (S-PMA) in 301 oil refinery workers. The metabolites' concentrations are lower and R is higher (100.66) in non-smokers (n= 184) than in smokers (n= 117, R= 36.54). Non-smokers have lower S-PMA and a higher R in GSTT1 null genotypes than in positive, and a higher S-PMA and a lower R in GSTA1 wild type genotypes. In smokers the GSTT1 null genotype effect on both S-PMA and R is confirmed, and is also shown in GSTM1 null, but not in GSTA1 wild type genotypes. GSTT1 null polymorphism reduces the conjugation rate of benzene epoxide with GSH, and to a lesser extent also GSTTA1 mutant, GSTM1 null and NQO1 mutant genotypes. The activity of one GST is compensated by another in GSTM1 and GSTA1 defective subjects, but not in GSTT1 null genotypes, whose average S-PMA excretion is about 50% with respect to the positive ones, for the same benzene exposure. R showed to be a more sensitive marker for these effects than the metabolite levels. © 2014 Elsevier Ireland Ltd.


Sisto R.,INAIL Research | Moleti A.,University of Rome Tor Vergata
ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics | Year: 2016

A new technique is proposed for the objective estimate of cochlear tuning, starting from measurements of the delay function of Stimulus Frequency (SF) and Transiently Evoked (TE) Otoacoustic Emissions (OAEs). The technique is quick and reliable, also in not cooperating subjects, while the psychoacoustic tuning measurements are time consuming and based on a large number of assumptions. It is well known that OAEs originate from two main backscattering mechanisms: coherent reflection and nonlinear wave-fixed distortion. The main TEO-AE and SFOAE sources are supposed to be linear reflection from the peak region, due to randomly distributed roughness. Recent experiments found evidence of OAE sources more basally located with respect to the CP (characteristic place) on the basilar membrane (BM). The origin of the basal sources is due to the multiple-peak nature of the coherent local reflectivity function generated by the roughness. The OAE components generated at different places of the BM can be effectively separated in the time-frequency domain, being characterized by different phase-gradient delay. A time-frequency technique was proposed to identify the curved time-frequency region corresponding to single-reflection SFOAE and TEOAE components, to get, for each frequency, a weighted average of the delay over this region, weighted by the square of the wavelet coefficient. This average delay is assumed to scale as the square root of the tuning factor. The estimated spectral tuning values turned out to decrease significantly with increasing stimulus level, confirming that at high stimulus levels a saturation process occurs in which a widening of the BM excitation patterns takes place. This increase of the BM response width increases the relative importance of the shorter-delay more basal peaks of the reflectance and, consequently, a reduction of the average delay. The proposed technique is based on the idea that a smooth relation exists between the average delay and the BM tuning, which is correctly exploited to get reliable and stable tuning estimates only if: 1) multiple reflections are filtered out, and 2) a weighted average of the delay is considered instead of a single delay value associated with the most intense of the OAE components, which is that picked up by standard measurements of the phase-gradient delay.


Martini A.,INAIL Research | Iavicoli S.,INAIL Research | Corso L.,INAIL Research
Oxidative Medicine and Cellular Longevity | Year: 2013

Multiple chemical sensitivity, commonly known as environmental illness, is a chronic disease in which exposure to low levels of chemicals causes correlated symptoms of varying intensity. With the continuous introduction of new substances, people with MCS suffer significant limitations to their living environment and frequently to their workplace. This paper describes the current situation as regards MCS and the critical points in its case definition, which is still not generally agreed upon; this makes it difficult to recognize with certainty, especially, its precise relationship with work. Other problems arise in relation to the occupational physician's role in diagnosing and managing the worker with the disorder, the question of low levels of exposure to chemicals, and the best measures possible to prevent it. A diagnostic "route" is proposed, useful as a reference for the occupational physician who is often called in first to identify cases suspected of having this disease and to manage MCS workers. Work-related problems for people with MCS depend not only on occupational exposure but also on the incompatibility between their illness and their work. More occupational physicians need to be "sensitive" to MCS, so that these workers are recognized promptly, the work is adapted as necessary, and preventive measures are promoted in the workplace. © 2013 A. Martini et al.


Davolos D.,INAIL Research | Pietrangeli B.,INAIL Research
Mycotoxin Research | Year: 2014

Aspergillus affinis (section Circumdati) is a novel ochratoxin A (OTA)-producing species found in submerged riparian decomposing leaves. However, very little is known about its role on the breakdown of plant debris and its ability to degrade carbohydrate polymers. Moreover, its OTA biosynthetic pathway has not yet been explored. In the present paper, we investigated the gene encoding the extracellular alpha-amylase (amyAa) of A. affinis within the evolution of the Aspergillus lineages in relation to the possible use of this enzyme in starch processing. The novel amyAa, despite being related to branches of the Aspergillus species of the sections Terrei and Flavi, formed a distinct phylogenetic branch, which may be of outstanding importance from a biotechnological point of view. Moreover, we identified the polyketide synthase gene (pks) putatively required for the first step of OTA biosynthesis in A. affinis. This otapks was examined in relation to a limited number of orthologous genes available from Aspergillus species of the sections Circumdati and Nigri. Our study highlights the importance of otapks as target genes in the treatment of ochratoxigenic Aspergillus species on a more comprehensive evolutionary basis. © 2014 Society for Mycotoxin Research and Springer-Verlag.


Davolos D.,INAIL Research | Pietrangeli B.,INAIL Research
Ecotoxicology and Environmental Safety | Year: 2013

Latium, a region in central Italy, is known for its extensive volcanic areas that make a significant contribution to the arsenic (As) contamination of freshwater environments, even though some degree of As water pollution may be caused by human activities. The information available on indigenous As-resistant prokaryotes in aquatic environments of Latium is, however, still limited. In this study, we describe new bacteria that are resistant to arsenic toxicity and were isolated from the surface waters of Lake Vico and the Sacco River, two groundwater systems in Latium, as well as from bottled natural mineral water from the same region. The 16S rRNA gene sequence analysis for the As-resistant strains in lake and river waters points to a prevalence of β- and γ-. Proteobacteria, while α-. Proteobacteria, Firmicutes and Bacteroidetes are represented to a lesser extent. By contrast, solely γ-. Proteobacteria were isolated from groundwater samples. The presence of Actinobacteria was documented exclusively in bottled mineral water. In addition, we conducted a DNA sequence-based study on the gene codifying arsB, an As(III) efflux membrane protein pump related to arsenic resistance, for all the As-resistant bacterial isolates. A phylogenetic analysis was carried out on the newly sequenced 16S rRNA genes and arsB in the present study as well as on an additional 16S rRNA/. arsB dataset we obtained previously from Lake Albano, from the Tiber and from a well in Bassano Romano located in Latium (Davolos and Pietrangeli, 2011). Overall, the phylogenetic diversity of As-resistant bacteria in underground water was very limited if compared with lentic and lotic waters. Lastly, our molecular data support the hypothesis that the horizontal gene transfer of ars in As-containing freshwater environments is not limited to closely-related genomes, but also occurs between bacteria that are distant from an evolutionary viewpoint, thereby indicating that such genetic events may be considered a source of microbial resistance to arsenic-toxicity. © 2013 Elsevier Inc.


Moleti A.,University of Rome Tor Vergata | Sisto R.,INAIL Research
JARO - Journal of the Association for Research in Otolaryngology | Year: 2016

The generation of stimulus-frequency otoacoustic emission (SFOAE) residuals in humans is analyzed both theoretically and experimentally to investigate the relation between the frequency difference between the probe and the suppressor tone and the localization of the residual source. Experimental measurements of the SFOAE residual were performed using suppressors of increasing frequency to separate the otoacoustic response from the probe stimulus. From the response to the probe alone, the SFOAE response was also estimated, using spectral smoothing, and compared with the residuals obtained for different frequency suppressors. A nonlinear delayed-stiffness active cochlear model was used to compute the spatial distribution of the residual sources according to a recent model of the local reflectivity from roughness, as a function of the suppressor frequency. The simulations clarified the role of high-frequency suppressors, showing that in humans, with increasing suppressor frequency, the generation region of the residual is only slightly basally shifted with respect to the case of a near-frequency suppressor, near the basal edge of the peak of the resonant basilar membrane response. As a consequence, the hierarchy among different-delay components correspondingly changes, gradually favoring short-delay components, with increasing suppressor frequency. Good agreement between the experimental and theoretical dependence of the level of otoacoustic components of different delay on the frequency shift between probe and suppressor confirms the validity of this interpretation. © 2016 Association for Research in Otolaryngology

Loading INAIL Research collaborators
Loading INAIL Research collaborators