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Biomedical subjects

D Mazzotti

Publications and source records attributed to D Mazzotti.

9 recordsLinked to original sources
PubMed2005

Frequency-comb-based absolute frequency measurements in the mid-infrared with a difference-frequency spectrometer.

We demonstrate the possibility of extending the well-established metrological performance of optical frequency-comb synthesizers to the mid-IR region by phase locking the pump and signal lasers of a difference-frequency source to two near-IR teeth of an optical comb. An uncertainty of 800 Hz (1.1 x 10(-11)) in the absolute frequencies of CO2 transitions near 4.2 microm has been measured by cavity-enhanced saturated-absorption spectroscopy. Prospects for the creation of a new dense set of high-quality molecular frequency standards in the IR are discussed.

Journal Article↗
PubMed2001

Spatial mode control of radiation generated by frequency difference in periodically poled crystals.

We demonstrate the possibility to control the spatial mode of a narrow-linewidth, continuous-wave, infrared radiation beam generated by difference frequency in a periodically poled crystal. This can be achieved by acting directly on a few experimental parameters. We show that hollow beams can be generated. A numerical routine has been developed and results agree with experimental observations, without requiring any free parameters. The relevance of these results for high-resolution spectroscopy and atom manipulation is discussed.

Journal Article↗
PubMed2001

Search for exchange-antisymmetric states for spin-0 particles at the 10(-11) level.

We set a new upper limit of 1.7x10(-11) to the probability that two spin-0 16O nuclei are in forbidden exchange-antisymmetric states, testing the validity of fundamental principles of quantum mechanics. A newly designed difference-frequency spectrometer is used to look for the existence of these states. The experimental test was performed by tuning the spectrometer across a molecular transition of 12C 16O (2) belonging to the rovibrational band at 4.25 microm, connecting the forbidden states (00(0)0,J = 25) and (00(0)1,J = 26).

Journal Article↗
PubMed1990

Louis-Bar syndrome: spontaneous and induced chromosomal aberrations in lymphocytes and micronuclei in lymphocytes, oral mucosa and hair root cells.

Louis-Bar (L-B) syndrome, also called ataxia-telangiectasia, is cytogenetically characterized by an increased frequency of spontaneous and induced chromosomal aberrations (CA) in cultured lymphocytes and skin fibroblasts. However, it is not yet clear whether the chromosomal instability is also present in uncultured cells. The spontaneous and bleomycin-induced CA in peripheral lymphocytes of 8 L-B patients were evaluated. The micronucleus test was also performed, for the first time in lymphocytes by the cytokinesis-block method, and in uncultured cells of the oral cavity and hair root. The spontaneous frequency of CA and micronuclei in lymphocytes was about 3 times higher in L-B patients than in controls, these two cytogenetic parameters being highly correlated. Moreover, the induction by bleomycin of CA was higher in patients than in controls. The micronuclei in buccal and hair root cells of patients were normal. It remains to be determined whether the different responses obtained with cultured and uncultured cells are the result of the different L-B gene expression of chromosomal instability or whether they arise because of a particular cell sensitivity to culture conditions. The spontaneous and induced CA in lymphocytes of heterozygotes cultured in the presence of L-B serum were studied to evaluate a possible increased sensitivity of heterozygotes to a possible diffusible clastogenic factor present in the plasma of L-B patients. We could not demonstrate the presence of any factor that enhances CA in normal subjects or in heterozygote carriers.

Adolescent↗
PubMed1989

Chromosomal alterations in peripheral blood lymphocytes, urinary mutagenicity and excretion of polycyclic aromatic hydrocarbons in six psoriatic patients undergoing coal tar therapy.

Six male non-smoking subjects treated for psoriasis with topical applications of pure coal tar or 4% coal tar-containing ointment were examined in order to assess the genotoxic risk associated with this type of therapy. Mutagenicity in urine samples collected before and during the coal tar therapy was evaluated in the plate incorporation assay on Salmonella typhimurium strain TA98 in the presence of S9 mix and beta-glucuronidase. Total urinary polycyclic aromatic hydrocarbon (PAH) levels were evaluated in parallel by high resolution gas chromatography/mass spectrometry. In addition, sister chromatid exchanges and chromosomal aberrations were also analysed in peripheral blood lymphocytes collected before, during and after the end of the coal tar applications. The results suggest that urinary mutagenicity levels as well as the frequencies of chromosome aberrations and sister chromatid exchanges in lymphocytes are related to the levels of exposure to coal tar. Moreover the kinetics of repair of chromosome damage in relation to different exposure levels and the capacity of the urinary mutagenicity assay to correctly identify the exposure to significant levels of PAH are discussed.

Administration, Topical↗
PubMed1987

Variations of SCE frequencies in peripheral lymphocytes of ex-smokers.

We measured SCE frequencies over a period of 8 months in 14 smokers who stopped smoking at the start of the study. In a first group of 10 subjects, who did not resume smoking during the period of cytogenetic follow-up, a lowering of SCE frequencies was already evident after 18 days and this became statistically significant after 78 days. SCE decrease was related to the logarithm of the period (in days) for which smoking was interrupted (r = 0.98; p less than 0.001). In a second group of 4 subjects, who at various times resumed smoking, the decrease of SCE followed the same pattern as in the first group during the period of nonsmoking, but SCE frequencies rose even higher once smoking was resumed. Our study indicates that the decrease of SCE in ex-smokers is rather rapid during the first 78 days after stopping smoking, and much slower from the 78th to the 233rd day.

Adult↗
PubMed1987

The micronucleus assay in exfoliated cells of the human buccal mucosa.

The frequency of micronuclei resulting from chromosome breaks, and that of micronuclei deriving from spindle disturbances was determined in exfoliated cells of the human buccal mucosa in 50 normal individuals. Several confounding factors, such as age, smoking habits, alcohol consumption, etc., were taken into account. While the frequencies of micronuclei resulting from chromosome breaks and of cells with this kind of micronuclei were about double in smokers as compared with non-smokers, the difference being highly statistically significant, the frequencies of cells with spindle disturbances were almost the same in the two groups. No statistically significant correlation was found for any of the other variables examined. In two patients suffering from cancer of the oral cavity the variation of the frequency of the micronuclei during the progress of radiotherapy and following its interruption was determined. It was found that gamma rays induced only micronuclei resulting from chromosome breaks, whose frequency increased linearly with the applied dose, and was lowered to the initial background level 7-12 days after the end of radiotherapy.

Adult↗
PubMedDate not supplied

No evidence of chromosomal instability in nevoid basal-cell carcinoma syndrome.

The nevoid basal-cell carcinoma syndrome (NBCCS) is a rare multisystem disorder characterized by several alterations of the skin, skeletal, nervous, endocrine system. These patients are more susceptible to cancer and suggestions have been made about an association with the chromosomal breakage syndromes. We studied the induction of chromosomal aberrations by mitomycin C (MMC) and bleomycin and that of sister-chromatid exchanges by MMC and 4-nitroquinoline N-oxide in lymphocytes of 4 NBCCS patients. The frequencies of both spontaneous and induced cytogenetic effects were within normal ranges, suggesting that there is no chromosomal instability in NBCCS patients.

4-Nitroquinoline-1-oxide↗