New developments in automated cytogenetic imaging: unattended scoring of dicentric chromosomes, micronuclei, single cell gel electrophoresis, and fluorescence signals.

The quantification of DNA damage, both in vivo and in vitro, can be very time consuming, since large amounts of samples need to be scored. Additional uncertainties may arise due to the lack of documentation or by scoring biases. Image analysis automation is a possible strategy to cope with these difficulties and to generate a new quality of reproducibility. In this communication we collected some recent results obtained with the automated scanning platform Metafer, covering applications that are being used in radiation research, biological dosimetry, DNA repair research and environmental mutagenesis studies. We can show that the automated scoring for dicentric chromosomes, for micronuclei, and for Comet assay cells produce reliable and reproducible results, which prove the usability of automated scanning in the above mentioned research fields.

t(11;14)-positive mantle cell lymphomas exhibit complex karyotypes and share similarities with B-cell chronic lymphocytic leukemia.

Until now, few data on additional chromosomal aberrations in t(11;14)-positive mantle cell lymphomas (MCLs) have been published. We analyzed 39 t(11;14)-positive MCLs by either comparative genomic hybridization (CGH; n = 8), fluorescence in situ hybridization (FISH) with a set of DNA probes detecting the most frequent aberrations in B-cell neoplasms (n = 12), or both techniques (n = 19). The t(11;14) was present in all cases. In 37 of 39 cases, chromosomal imbalances were found. In 27 cases, complex karyotypes, i.e., >/= 3 aberrations, were identified. The most frequent aberrations were losses of 13q14-21 or 13q32-34 (27 cases), 9p21 (16 cases), and 11q22-23 (12 cases) and gains of 3q26-29 (19 cases), 8q22-24 (11 cases), and 18q21-22 (9 cases). In 26% of cases (7 of 27) analyzed by CGH, a total of 10 high-level DNA amplifications were identified. Although in comparison with B-cell chronic lymphopcytic leukemia (B-CLL) MCL is characterized by a much higher complexity of chromosomal aberrations, there are striking similarities: 13q14 deletions were identified in more than 50% of both MCL and B-CLL cases. In contrast, in our CGH database containing 293 B-cell lymphomas, this aberration was found in only 11% of other nodal lymphomas. Even more strikingly, 11q deletions, which are present in 20%-30 % of MCL and B-CLL, were found very rarely in other nodal B-cell lymphomas (CGH: 1 of 208 cases; FISH: 1 of 69 cases). These data show that MCL is characterized by specific secondary aberrations and that there may be similarities in the pathogenesis of MCL and B-CLL. Genes Chromosomes Cancer 27:285-294, 2000.

High resolution multicolor-banding: a new technique for refined FISH analysis of human chromosomes.

A new multicolor-banding technique has been developed which allows the differentiation of chromosome region specific areas at the band level. This technique is based on the use of differently labeled overlapping microdissection libraries. The changing fluorescence intensity ratios along the chromosomes are used to assign different pseudo-colors to specific chromosome regions. The multicolor banding of human chromosome 5 is presented as an example.

Minimal sizes of deletions detected by comparative genomic hybridization.

Comparative genomic hybridization (CGH) has been used widely for the molecular cytogenetic analysis of tumors. Until now, the spatial resolution of this technique for diagnosing deletions of chromosomal sequences has not been assessed in detail. In the present study, we performed CGH analyses on five DNA samples derived from B-cell leukemias with 11q deletions, the sizes of which ranged from 3 Mbp to 14-18 Mbp. CGH experiments were evaluated by two established commercial analysis systems. Deletions down to a size of 10-12 Mbp were diagnosed based on a diagnostic threshold value of 0.8, if the vast majority of cells carried the deletion. For cases with smaller deletions, the ratio profiles were shifted toward underrepresentation at the respective chromosomal bands; however, the diagnostic threshold value was not reached. In all five cases, there was complete agreement between the two image analysis systems.

[Use of the scanning laser ophthalmoscope for recording pattern electroretinography and visual evoked cortical potentials]. / Anwendung des Scanning Laser-Ophthalmoskops zur Registrierung des Muster-Erg und Vecp.

With a scanning laser ophthalmoscope (SLO) variable patterned stimuli can be projected onto the retina. During alternation of these patterns visual evoked cortical potentials and pattern ERGs can be recorded. The configurations of the SLO-elicited potentials and peak latencies correspond to those evoked during conventional stimulation. During pattern stimulation the fundus and alternating pattern stimuli are observed simultaneously on a video monitor. Thus the examiner always knows the exact location of the stimulus on the retina. Scanning laser ophthalmoscopy could be a clinically interesting method of recording evoked potentials, because it enables the patient's retina to be viewed continuously at low light levels and makes electrophysiological examination of a defined region of the retina possible.

Digital laser scanning fundus camera.

Imaging and documentation of the human retina for clinical diagnostics are conventionally achieved by classical optical methods. We designed a digital laser scanning fundus camera. The optoelectronical instrument is based on scanning laser illumination of the retina and a modified video imaging procedure. It is coupled to a digital image buffer and a microcomputer for image storage and processing. Aside from its high sensitivity the LSF incorporates new ophthalmic imaging methods like polarization differential contrast. We give design considerations as well as a description of the instrument and its performance.