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Biomedical subjects

Luca Perfetti

Publications and source records attributed to Luca Perfetti.

6 recordsLinked to original sources
PubMed2005

Strongly coupled optical phonons in the ultrafast dynamics of the electronic energy and current relaxation in graphite.

Ultrafast charge carrier dynamics in graphite has been investigated by time-resolved terahertz spectroscopy. Analysis of the transient dielectric function and model calculations show that more than 90% of the initially deposited excitation energy is transferred to a few strongly coupled lattice vibrations within 500 fs. These hot optical phonons also substantially contribute to the striking increase of the Drude relaxation rate observed during the first picosecond after photoexcitation. The subsequent cooling of the hot phonons yields a lifetime estimate of 7 ps for these modes.

Journal Article↗
PubMed2005

Mott phase at the surface of 1T-TaSe2 observed by scanning tunneling microscopy.

In this Letter we report the observation, by scanning tunneling microscopy, of a Mott metal to insulator transition at the surface of 1T-TaSe2. Our spectroscopic data compare considerably well with previous angle-resolved photoemission spectroscopy measurements and confirm the presence of a large hysteresis related to a first order process. The local character of the tunneling spectroscopy technique allows a direct visualization of the surface symmetry and provides spectroscopic measurements on the defect-free region of the sample. It follows that the electronic localization is driven purely by the enhancement of the charge density wave amplitude which drives a bandwidth controlled metal-insulator transition.

Journal Article↗
PubMed2005

Occupational asthma and occupational rhinitis in hairdressers.

BACKGROUND: Hairdressers are at risk for occupational respiratory diseases, but the risk factors, causal agents, and underlying mechanisms are not completely defined. AIM: To describe the features of a large group of hairdressers consecutively referred to our center for suspected occupational asthma (OA) over an 8-year period, the type of occupational respiratory diseases, the etiologic agents, and the diagnostic tests. RESULTS: Forty-seven hairdressers (mean age, 25 years; range, 17 to 52 years) were studied. On the basis of the response to the specific inhalation challenge (SIC), 24 patients received a diagnosis of OA (51.1%), which was due to persulfate salts in 21 patients (87.5%), permanent hair dyes in 2 patients (8.3%), and latex in 1 patient (4.2%). Thirteen of these 24 patients (54.2%) also received a diagnosis of occupational rhinitis, which was due to persulfate salts in 11 patients (84.6%) and to paraphenylenediamine in two patients (15.4%). Patients with persulfate asthma had a long period of exposure to bleaching agents, a long latent period between the start of exposure and the onset of symptoms, and a prevalent eosinophilic airway inflammation in induced sputum. The skin-prick test with ammonium persulfate performed in a subset of patients gave negative results CONCLUSIONS: In the present study, we confirmed that persulfate salts are the major agents involved in OA and occupational rhinitis in hairdressers. The positive response to the SIC in only a part of the population of symptomatic exposed workers, the period between the starting of exposure and the onset of symptoms, the type of response to the SIC, and the high frequency of association of asthma with other diseases such as dermatitis and rhinitis suggest an immunologic mechanism that remains to be elucidated.

Adolescent↗
PubMed2005

Irritant vocal cord dysfunction at first misdiagnosed as reactive airway dysfunction syndrome.

OBJECTIVES: This report describes a case of vocal cord dysfunction at first misdiagnosed as reactive airway dysfunction syndrome (RADS). METHODS: A woman developed recurrent episodes of cough, dyspnea, and wheezing unresponsive to asthma therapy after irritant exposure to glutaraldehyde. Direct laryngoscopy was performed immediately after the induction of symptoms. RESULTS: Laryngoscopy showed a paradoxical adduction of the vocal cord on inspiration. Vocal cord dysfunction was diagnosed. CONCLUSIONS: A case of vocal cord dysfunction occurred after exposure to glutaraldhyde in a person with a history highly suggestive of RADS. Vocal cord dysfunction should always be considered in the differential diagnosis of patients with acute respiratory symptoms after exposure to irritants and with asthma-like symptoms that fail to respond to conventional asthma therapy.

Asthma↗
PubMed2003

Occupational asthma (OA) with sensitization to diphenylmethane diisocyanate (MDI) presenting at the onset like a reactive airways dysfunction syndrome (RADS).

BACKGROUND: Two types of OA are distinguished: immunological (OA with sensitization) and non-immunological, i.e., irritant induced asthma or reactive airways dysfunction syndrome (RADS). METHODS: We describe the case of a worker who developed respiratory symptoms after a spill of diphenylmethane diisocyanate (MDI) at the workplace. RADS was initially diagnosed and the worker resumed working. The progressive worsening of symptoms and the appearance of symptoms-work relationship one year later, when concentrations of isocyanates were no longer "irritant," suggested immunological OA. RESULTS: The diagnosis was confirmed by specific inhalation challenge test, followed by removal from exposure and complete recovery. CONCLUSIONS: In the case of RADS due to an agent with both irritant and sensitizing properties, history should be repeatedly assessed for a possible symptom-work relationship. If this is found, further investigations should be carried out, including specific inhalation challenges, to confirm the possibility of immunological OA.

Asthma↗