In first-trimester chorionic villus sampling (CVS) for prenatal diagnosis, abnormal chromosomal findings, such as mosaicism, trisomies, or suspect abnormal karyotypes, are found more frequently than at amniocentesis. The fact that these chromosomal abnormalities do not always reflect the fetal karyotype but may be restricted to the placenta is a major problem in diagnosis and counselling. In this paper we present the results of fluorescence in situ hybridization (FISH) studies on interphase nuclei of three term placentae investigated because of false-positive findings at first-trimester CVS. The chorionic villi of the first case showed a mosaic chromosome pattern involving a trisomy 10 cell line and a normal cell line, those of the second case a total trisomy 8 cell line, while in the third case a complete monosomy X was found. Follow-up amniocentesis in each of these three cases revealed a normal karyotype. By using FISH, we were able to confirm the presence of the aberrant cell lines, which were all confined to one part of the placenta. FISH on interphase nuclei allows the investigation of large numbers of cells for the existence of numerical chromosome aberrations in a quick and reliable way. 相似文献
The oxygenated species, massively produced in the energy production plants based on combustion processes, constitute one of the most numerous categories of hazardous air pollutants. Therefore, development of real time diagnostic tools are needed in order to study their formation during combustion processes and to reveal their presence both in the exhaust and in the atmosphere. In this work, oxygenated compounds were identified inside fuel-rich premixed ethylene/air flames by means of ultraviolet fluorescence spectroscopy with the support of qualitative chemical analysis of the sampled combustion gases.
Strong band progression, typical of aldehydic functionality, were recognized in fluorescence spectra (λexc=355 nm) measured in the early oxidation region of premixed flames varying the equivalence ratio from 3.0 up 21.6. Downstream of the oxidation region, spectroscopic signatures of pyrolytic species were found to prevail on those peculiar of oxygenated compound. The position and the extension of the two main flame zones were found to depend on the flame conditions (C/O ratio) due to the effect of the C/O ratio on the temperature history along the flame axis. This correlation was interpreted on the basis of the measured axial temperature profiles. 相似文献
The fluorescence spectroscopic behavior of bromadiolone (anticoagulant rodenticide), a substituted 4-hydroxycoumarin derivative, was investigated in water and in organized media like micelles and cyclodextrins. A detailed study on various photophysical parameters like fluorescence intensity (IF), quantum yield (), lifetime (τ) and steady state fluorescence anisotropy (r) of bromadiolone in aqueous and in organized media was carried out. Bromadiolone in aqueous solution was observed to be in an aggregated state, thereby showing weak emission due to self-quenching. Marked enhancement of fluorescence intensity was observed in organized media like micelles and β-cyclodextrin. A preliminary investigation has been done to find out whether this enhancement of fluorescence can be used to develop a sensitive analytical method for determination of bromadialone in aqueous media. A linear relationship between the fluorescence intensity and concentration of bromadiolone was observed in the range of 0.15–7.9 μg ml−1 in cetyltrimethylammonium bromide (CTAB) and 0.5–26.4 μg ml−1 in β-cyclodextrin medium. The lower detection limit was found to be 37 ng ml−1 in presence of CTAB and 23 ng ml−1 in β-cyclodextrin. Comparison with 4-hydroxycoumarin, an unsubstituted analogue, was made. 相似文献