Tests of performance of four semi-automatic metaphase-finding and karyotyping systems.

Four commercially-available semi-automatic cytogenetic systems (Cytoscan, Ibas, Magiscan and Miamed) have been evaluated for both metaphase-finding and karyotyping performances, using a common set of test slides and uniform criteria. Comparisons have been made in respect of timings, number and nature of operator interactions, and false positive and negative rates. Amongst the general conclusions are the importance, for metaphase-finding performance, of a facility for ranking candidate metaphases according to their 'analysability', the need for some systems to reduce the time taken to relocate candidate metaphases, and the ability of all systems tested to detect analysable metaphases that were initially overlooked by a skilled cytogeneticist. In spite of automation, karyotyping remains a highly interactive process, strongly dependent on the skill and judgment of the operator, and therefore difficult to evaluate fully objectively.

An improved fixation method for chromosome preparation of Chinese hamster, Chinese hamster-human hybrid, and mouse cell lines.

Lowering the proportion of acetic acid in the standard 1:3 acetic acid:methanol chromosome fixative used both during initial fixation and subsequent washing produced up to a 20-fold increase in the yield of intact metaphases from cultures of several permanent cell lines. Although this inhibited chromosome spreading, addition of various acetic acid-methanol mixtures immediately after the cell suspension was dropped onto slides increased the degree of spreading and resulted in well-spread, cytoplasm-free metaphases.

The automation of culturing and harvesting of human chromosome specimens.

This paper describes the development of a machine for the automated culturing and harvesting of human chromosome specimens. The machine is capable of handling different preparation methods simultaneously, such as standard blood cell, blast cell and bone marrow cultures, and can be programmed to perform the prophase synchronization techniques. It is composed of a culture tray, centrifuge, mixer, input and output station and a head assembly capable of transporting samples between the various stations and which is equipped with an aspirator needle to suck off the supernatant and fluid dispensers for the dosing of the various chemicals. A microprocessor system controls all hardware functions and schedules the manipulations of all samples thereby preventing, that more than one sample requires servicing at the same time. The samples (up to a maximum of 255) are processed by the machine in small batches of maximal 16, which can be activated at any time according to one of 16 culture procedures. The cytogeneticist can modify these procedures using a simple interpretive language specifying both the types of manipulations, such as centrifugation, addition of chemicals, sucking of supernatant and the minimal and maximal variation in time, which is allowed between two sequential manipulations. Besides the hardware setup and software organization of the machine, the first preliminary results and future prospects for the machine are presented.