Rapid tissue processor

Details Rapid tissue processor Rapid tissue processor

2000-12-14

2004-09-21

Warden, Jill (Department: 1743)

Chemical apparatus and process disinfecting, deodorizing, preser

Analyzer, structured indicator, or manipulative laboratory...

Means for analyzing gas sample

C422S062000, C422S063000, C422S105000, C435S040500, C435S040510, C435S040520, C436S046000, C436S063000, C436S064000, C436S174000, C436S176000

Reexamination Certificate

active

06793890

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the rapid, continuous flow, processing of tissue for histology, from fixation to impregnation. In particular, it relates to an automated tissue processing system that can be operated with continuous throughput and uses a sequential series of different non-aqueous chemical solutions to harden a tissue specimen and to produce a wax-impregnated tissue specimen suitable for embedding and sectioning.
2. Description of the Related Art
Conventional methods prepare tissues for histology by incubation in separate solutions of phosphate-buffered 10% formaldehyde for fixation, a series of increasing concentrations of ethanol for dehydration, and xylene for clearing tissue of dehydration agent, prior to impregnation. Because of the time required for this process, usually 8 hours or longer, it is customary to complete these separate steps—fixation, dehydration, clearing, and impregnation—overnight in automated mechanical instruments designed for those tasks (see, for example, U.S. Pat. Nos. 3,892,197; 4,141,312; and 5,049,510).
Automated tissue processors implementing such conventional processes are manufactured and sold by, for example, Shandon (HYPERCENTER and PATHCENTRE models), Miles-Sakura (TISSUE-TEK models), and Mopec-Medite (TPC15 model).
A disadvantage of the prior art is that such automated systems have not been capable of continuous throughput. Given the time required to complete tissue processing, cassettes containing tissues are loaded into the system during the day and tissue processing is completed in an overnight cycle. Thus, operation of the prior art systems did not allow tissue-containing cassettes to be processed to completion during the work day.
For example, the TISSUE-TEK vacuum infiltration processor (VIP) series requires more than eight hours for completion of processing. Baskets holding the cassettes are placed in a retort in which tissue is processed. In addition, 14 stations supply solutions of various compositions to the retort. User-programmable software controls this automated process. A rotary valve regulates the movement of solutions between the retort and the various stations; applying pressure or vacuum to the retort when the valve is open causes solution to be pumped out of or pumped into the retort, respectively. Upon completion of a processing run, the instrument automatically prompts the use for a cleaning cycle; this requirement can be overridden only if no paraffin is used. Typically, tissue specimens are batch processed according to the following program:
Set
Set
Volume
Concen-
Time
Tempera-
P/V
of
Solution
tration
(min)
ture
**
Agitation
Solution
1
Buffered
10%
50
40° C.
On
On
2.2-3.2 L
formalin
2
Buffered
10%
50
40° C.
On
On
2.2-3.2 L
formalin
3
Alcohol*
80%
50
40° C.
On
On
2.2-3.2 L
4
Alcohol
95%
50
40° C.
On
On
2.2-3.2 L
5
Alcohol
95%
50
40° C.
On
On
2.2-3.2 L
6
Alcohol
100%
50
40° C.
On
On
2.2-3.2 L
7
Alcohol
100%
50
40° C.
On
On
2.2-3.2 L
8
Alcohol
100%
50
40° C.
On
On
2.2-3.2 L
9
Xylene
100%
50
40° C.
On
On
2.2-3.2 L
10
Xylene
100%
50
40° C.
On
On
2.2-3.2 L
11
Paraffin
50
60° C.
On
On
4 L
12
Paraffin
50
60° C.
On
On
4 L
13
Paraffin
50
60° C.
On
On
4 L
14
Paraffin
50
60° C.
On
On
4 L
**P/V (Pressure/Vacuum): agitation is provided by alternating the application of pressure and vacuum to the retort when “P/V” is On. Otherwise, when “Agitation” is On, agitation can also be provided by pumping in and then pumping out the same solution every 20 minutes.
*The alcohol used in most laboratories is a mixture of 90% ethyl, 5% methyl, and 5% isopropyl alcohol.
Typically such conventional methodology demands sending tissue specimens from the operating room, medical office or other sites, to a pathology laboratory sometime during the working day; overnight batch processing of the specimens, so that a tissue specimen suitable for blocking and sectioning is only available on the morning of the next day; and rendering a diagnosis by a pathologist based on microscopic examination of sections prepared from a blocked and sectioned specimen later on that next day (FIG.
1
). This requires almost 24 hours between receipt of the specimen and delivery of the pathologist's report. Although a shortened version of the conventional method is presently practiced, it is feasible only for small biopsies. These biopsies need to be fixed for at least about 30 minutes before initiating the processing cycle. The instrument processing cycle can be programmed to last a minimum of 70 minutes, but is preferably 2 to 2½ hours.
In addition to the minimum one-day delay in giving a surgeon the benefit of a report from the pathologist, there are also problems associated with impeded work flow in the pathology laboratory necessitated by the requisite batch processing of specimens, the safety concerns that attend having instruments operating overnight, the risk of possible instrument failures and the need to monitor the instruments, and the waste of using large volumes of reagents for such processing when automated. Moreover, expensive measures are required to prevent exposure of laboratory personnel to noxious fumes and toxic substances associated with the reagents used in this process. Also, the large volumes of solvent waste and paraffin debris produced by the conventional methodology will pollute the environment if not properly disposed.
Conventional fixation and processing also cause irreversible damage (e.g., hydrolysis of a phosphodiester bond and/or deamidation) to the structure of nucleic acids (e.g., DNA, and especially RNA) that limits the application of genetic techniques for diagnosis and research. Consequently, most DNA and certainly RNA analysis require special precautions with handling of material, such as immediate freezing of fresh tissues to prevent degradation, because retrospective genetic analysis is impaired by the conventional methodology.
Histological diagnosis of a frozen section suffers from multiple disadvantages in comparison to sections prepared from paraffin blocks. U.S. Pat. No. 3,961,097 cautions that the slide prepared from a frozen section “does not possess . . . uniformity of quality;” “it is technically more difficult for serial sections of the same specimen to be examined;” “extreme caution must be exercised in cutting the specimen in order to ensure a sufficiently thin section and to avoid the possibility of damaging details of the specimen;” and all the slides must be prepared “while the tissue is in the initial frozen state” because “[i]f the tissue is thawed and refrozen for sectioning, it is severely damaged.”
There is an ever present interest in expediting tissue processing and analysis for diagnostic purposes. Furthermore, recent healthcare focus has been directed to lessening the cost of various procedures including tissue processing. The costs of tissue processing are related to the time for processing and analysis of the specimens, the space required for the personnel and equipment in the laboratory, the volume of reagents (both the purchase price of the pure chemicals and the charges for discarding waste), and the number of personnel required. More importantly, patients and their physicians depend on evaluation and diagnosis by the pathologist to guide treatment. Reducing the amount of time needed to complete tissue processing would lessen the anxiety experienced during the period between obtaining the specimen and delivering the pathologist's report to the surgeon.
Others have recognized the need to shorten the time required for tissue processing, but they have made only modest improvements in the conventional methods. To accelerate tissue processing, U.S. Pat. Nos. 4,656,047, 4,839,194, and 5,244,787 use microwave energy; U.S. Pat. Nos. 3,961,097 and 5,089,288 use ultrasonic energy; and U.S. Pat. No. 5,023,187 uses infrared energy. U.S. Pat. No. 5,104,640 disclosed a non-aqueous composition of a fixative, a stabilizing agent, and a solubilizing agent that adheres a blood smear to a slide. But the aforementioned patents do

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