Why should you consider using a Microwave Processing System from Ted Pella, Inc.?
Because PELCO is a leading innovator in the field of microwave technology for sample processing.
What is meant by the term "microwave technology"? "Microwave technology", simply stated, is the combination of features built into a microwave system to control heat generation during irradiation. PELCO's success in creating a wide range of easily implemented microwave protocols is based on this premise. All the functional features they have developed (i.e. microwave technology), when combined, provide the best control of the microwave environment available today.
These features include:
Microwave Transparent and Chemically Resistant Vacuum Chamber:
Greatly facilitates small sample fixation and reduces resin and paraffin infiltration times in the microwave.
True Variable Wattage:
Magnetron output can be selected from six different power/wattage levels, calibrated in 100W increments from 250 to 750W. This feature should not be confused with partial or intermittent power levels which are described as % power (full power for a percentage of the time, i.e. 20% power for an 800W microwave is 800W for 12 sec./min.).
Temperature Restrictive Temperature Probe:
The temperature probe is accurate to /- 1 degree C. A PTFE coated probe is available for special stains and decalcification. Maximum temperature can be preset prior to runs ensuring that protocol parameters are not exceeded. This is especially important during fixation, decalcification and special stain applications.
Adjustable Temperature Water Recirculation System:
The temperature of the water load(s) can be maintained at a constant temperature (about 10 degrees C above ambient) for any time period. This ensures a uniform microwave cavity environment during long periods of irradiation. This aspect is critical for temperature control during decalcification, dehydration, fixation and special stains.
Automatic Magnetron Prewarming:
The magnetron filament is automatically preheated prior to every run to ensure that 100% of the power selected is delivered for 100% of the time chosen.
Programmable Key Pads:
When programmed, the 10 numbered key pads provide "one touch" operation of the system. This eliminates the need to use the time entry, numeric and start keys to begin a microwave run.
Other Features:
Digital timing (accurate to the second); intermittent power settings (0%, 20%, 50%, 70%); RS232 port and cable for PC attachment with software for temperature and time monitoring.
The Development of the Features listed above have been the Precursors to the Development of easy to use Microwave Protocols for:
- rapid formalin fixation of tissue (<1.25 hours for tissues <5mm thick)
- rapid decalcification of bone in either acids or salts (from 2X to >10X times savings)
- rapid colour development in special stain applications (one step development)
- rapid processing of tissue into paraffin blocks (biopsies <45 min.; 2mm thick samples in 2 hours)
- improved immunolabeling results (due to rapid processing and microwave fixation)
- rapid processing of needle biopsies (fresh tissue to stained slide in under 2 hours)
- rapid processing of tissue for electron microscopy (fresh tissue to sectioning in under 2 hours)
Each of the protocols listed above relies on a different combination of variables (i.e. power level, temperature restriction, constant microwave environment, time) which, through our research and that of others, has been demonstrated to be necessary for the successful use of microwave technology on a routine basis. Time is a commodity of which we never have enough. Microwave technology in your laboratory offers a multi-functional piece of equipment that will improve productivity, reduce turnaround times, maintain quality and keep you competitive. Microwave technology works.
Notes:
The importance of PELCO's advanced microwave processing technology (variable wattage, precise temperature control, and water load recirculation) to the success of microwave-assisted formalin fixation of fresh tissue must be addressed. Previous attempts to fix fresh tissue (<5mm thick) in formalin have met with little success. Researchers report being able to fix only the periphery of the tissue block. Apparently, the crosslinking of formaldehyde to the tissue forms an effective diffusion barrier to further movement of the fixative.
Formalin fixation is believed to proceed in the following three steps:
- diffusion of methylene glycol into the tissue
- conversion of methylene glycol to formaldehyde
- crosslinking of formaldehyde to the tissue
PELCO research shows that using variable wattage, along with precise temperature control (37°C) and recirculated water loads, allows complete fixation of fresh tissue, under 5mm thick, in less than one and one half hours. This result is not possible without variable wattage. Precise temperature control is absolutely required if one wishes to distinguish between chemical fixation and heat stabilisation in the interior of the tissue block.
Conclusion:
Based on past and current research, the PELCO Microwave Processing Systems are the best choice for histological applications. They have all the features necessary to meet the demands of today's clinical environment. The protocols which have been developed are based on ease and simplicity. The features of the microwave are easy to understand and use. Support for either the science or the product is simply a phone call away.
PELCO product development and scientific research is producing solutions where problems have previously existed. The evidence is in. Technology is the key to success when using a microwave in the laboratory.
Microwave Literature:
Chicoine, L., and Webster, P. (1998) The effect of microwave irradiation on antibody labeling efficiency when applied to ultrathin cryosections through fixed biological material. Micros. Res. Tech. 42:24-32.
Demaree, R.S., Jr., Giberson, R.T., Smith, R.L. (1995) Routine microwave polymerization of resins for transmission electron microscopy. Scanning 17 (Suppl. 5):25-26.
Giberson, R.T., Gaffney, C.A., Chau, C-K. (Submitted) Increased diffusion rates during fixation by non-thermal effects of microwave radiation. Microsc. Res. Tech.
Giberson, R.T., Demaree, R.S., Jr. (In Press) Microwave processing techniques for electron microscopy: A four-hour protocol. In: Electron Microscopy Methods and Protocols. N. Hajibagheri, ed. Humana Press, Inc., Totowa, NJ
Giberson, R.T., Demaree, R.S., Jr., Nordhausen, R.W. (1997) Four-hour processing of clinical/diagnostic specimens for electron microscopy. J. Vet. Diagn. Invest., 9:61-67.
Giberson, R.T., Smith, R.L., Demaree, R.S. (1995) Three hour microwave tissue processing for transmission electron microscopy: from unfixed tissues to sections. Scanning 17(suppl. 5):26-27.
Giberson, R.T., Demaree, R.S., Jr. (1995) Microwave fixation: Understanding the variables to achieve rapid reproducible results. Microsc. Res. Tech., 32:246-254.
Madden, V.J. (1998) Microwave processing of cell monolayers in situ for post-embedding immunocytochemistry with retention of ultrastructure and antigenicity. Microsc. Microanal. 4(Suppl 2:Proceedings):854-55.
Madden, V.J., Henson, M.M. (1997) Rapid decalcification of temporal bones with preservation of ultrastructure. Hearing Research, 111;76-84.
Petrali, J.P., Mills, K.R. (1998) Microwave-assisted immunoelectron microscopy of skin. Microsc. Microanal. 4(Suppl 2:Proceedings):1114-15.
Rassner, U.A., Crumrine, D.A., Nau, P., Elias, P.M. (1997) Microwave incubation improves lipolytic enzyme preservation for ultrastructural cytochemistry. Histochem. J., 29:387-392.