Chemistry: molecular biology and microbiology – Apparatus – Including condition or time responsive control means
Reexamination Certificate
1999-02-17
2001-07-31
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Including condition or time responsive control means
C435S286400, C435S307100, C435S040510, C422S065000, C422S105000
Reexamination Certificate
active
06268208
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a specimen preparation system and associated method for preparing blood-cell smears or the like for examination; in particular the invention relates to time-reduction improvement in the drying process part of a smear specimen preparation procedure carried out by the system prior to staining the specimens.
2. Description of Related Art
An example of a smear specimen preparation apparatus in which the processes from smearing blood onto glass slides to staining are automated is disclosed in Japanese Laid-Open Pat. Publ. No. 8-271390. This apparatus uses cassettes for housing glass slides and solutions, smears blood on the glass slides to prepare smear specimens, stores the smear specimens into empty cassettes that are sent in one by one, and dispenses staining solutions into the cassettes to stain the blood cells.
To prepare neat, stably stained specimens, the smears on the glass slides must be sufficiently dried before staining. If there is no concern with process time, the specimens may be dried naturally for some length of time, for example, from one to a few hours. Toward raising processing speed, however, it is necessary to shorten the time for the drying procedure, which is prior to staining.
There is one method, for example, in which the specimens are cool-air dried in air blown by a fan. However, changes in the surrounding environment give rise somewhat to variations in the drying conditions (in hot or humid situations, insufficient drying is likely). Inconsistencies in the drying conditions will appear as inconsistencies in the staining conditions, which ultimately will affect the outcome of the stained specimens. Carrying out the staining process on an insufficiently dried smear specimen leads to unsatisfactorily stained, unclear specimens.
Sir John V. Dacie and S. M. Lewis describe a rapid staining method on pp. 54-55 of
Practical Haematology
, Sixth Edition (Churchill Livingstone, London, 1984). Nevertheless, what they note is related not to shortening drying procedure time, but rather to shortening the time for the subsequent staining procedure.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to shorten the time interval in which smear specimens are dried in a system and associated method for preparing smear specimens, thereby enabling satisfactory staining results in the subsequent staining process.
In a smear preparation system of the present invention, the following procedures are carried out by corresponding devices of the system: 1) a smearing procedure wherein subject particles for examination are smeared onto an element for smear specimens; 2) a drying procedure wherein, after the smear specimen—the element for smear specimens onto which the subject particles for examination have been smeared—is contacted with alcohol, the liquid present on the smear specimen is evaporated and dried; and 3) a staining procedure wherein the particles on the subject smear specimen for examination are stained.
Important to the present invention is the distinction between drying and fixing in the preparation of subject smear samples for examination. Drying removes water from smear cells to prepare them osmotically to accept the stain. In other words, dehydration makes the cells hypertonic with respect to the stain solution. Fixing preserves tissue morphology and molecular composition.
The staining procedure includes fixing, staining and rinsing processes. For example, one process of the staining procedure is to immerse a smear specimen into methyl alcohol or May-Grünwald solution, which contains methyl alcohol at high concentration. Because this is a fixing process in the staining procedure, however, the sample is normally immersed 2 or 3 minutes or more.
In contrast, contacting with alcohol in the present invention is for a far shorter interval. Moreover, because the liquid component on the smear specimen is evaporated and dried, the effect on the cells is different from that noted above. Accordingly, the present invention is a means for solving the problem of inconsistencies in the pre-staining drying process.
“Short interval” herein means an extent of time that does not lead to the cells subject to observation becoming fixed. Further, “short interval” signifies 30 seconds or less, preferably 10 seconds or less.
Although the dehydration mechanism of cells is not altogether precisely understood, the present invention arose through trial and error, and is based on the finding that if a smear specimen is briefly contacted with methyl alcohol, and the liquid component on the smear specimen is soon evaporated and dried, in the succeeding staining process stabilized suitable results are obtained.
It is probable that the alcohol, in particular short-chain alcohol, increases osmotic pressure external to the cells, thereby dehydrating them. Accordingly, “liquid component on the smear specimen” herein signifies alcohol or alcohol in solution, together with water content that has passed from the smear cells.
In an apparatus for preparing smear specimens that stains subject cells for observation by immersing the smear specimens, which are substrates for smear specimens onto which subject cells for observation have been smeared, into a staining solution, a smear specimen preparation system of the present invention is characterized in being fitted with a smear specimen drying mechanism that, at the earlier phase portion of the above-noted staining process, immerses the smear specimen into alcohol and then evaporates and dries the liquid component on the smear specimen.
From an automation standpoint, the smear specimen preparation apparatus preferably is furnished with cassettes for housing the smear specimens; a conveyance section for conveying the cassettes; a stowing section for stowing the smear specimens into the cassettes; and a staining section that dispenses staining solution into the cassettes to stain the subject cells on the smear specimen for observation. Herein, the staining solution is dispensed into the cassettes and the smear specimens are thus stained within the cassettes. The present invention employs these cassettes for carrying out drying of the smear specimens prior to staining.
Accordingly, a smear specimen drying method of the present invention makes it possible to dry smear specimens in a short time interval to be in suitable condition for staining.
By applying this technique to an automated smear specimen preparation apparatus, smear specimens in satisfactory condition for staining can be stably obtained, without requiring much time for drying and irrespective of changes in temperature, humidity and like environmental conditions.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings.
REFERENCES:
patent: 3995022 (1976-11-01), Heanley et al.
patent: 4302480 (1981-11-01), Fischer et al.
patent: 5779982 (1998-07-01), Aota et al.
Beisner William H.
Shinjyu Intellectual Property Firm
Sysmex Corporation
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