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Human amniotic membrane as a physiologic wound dressing
ANNUAL
MEETING
85. Limitations of Cryosurgical Techniques for tumors. A. A. GAGE (Department of Surgery, Veterans Administration Hospital, Buffalo, NY 14215). Experience with the treatment of over 200 patients with malignant tumors by freezing in situ in the past 8 years has revealed several problems which must be considered if cryosurgery is to gain a place in surgical practice. One is the difficulty in determining the extent of freezing, especially when treatment is given via endoscopy. Even when vision is good, determination of depth of freezing is difficult to ascertain. Formulas have been developed to predict the thermodynamic growth of ice balls around cryoprobes but these are not practical for use in clinical cryosurgery. Considerable reliance must be based on the use of needle thermocouples in the tissues. Although in general, the results of treatment have been good, it has become evident that further progress in the development of the technique depends on the solution of problems related to freezing limitations of the cryosurgical apparatus. Faulty freezing of tumors led to experiments with three types of cryosurgical apparatus using liquid nitrogen. Closed cryogenic systems and spray techniques were used, yet there always existed the difficulty of freezing the large volumes of tissues necessary in cancer treatment. Vagaries in liquid nitrogen flow were seen in some experiments. Unsuspected variations in the quality of cont,act between probe and tissues due to faulty technique resulted in considerable differences in surface and deep tissue temperatures. Our experience, experimental and clinical, has shown that cryosurgical equipment needs considerable improvement in design and function and cryosurgical t,echnique must be carefully learned and applied. Human Amniotic Membrane as a Physiologic Wound Dressing. G. COLLOCHO,’ W. P. GRAHAM .4m W. GREEN (Lovelace Clinic, Albuquerque, New Mexico 87108 and Department of Surgery, Milton S. Hershey Medical Center. Hershey, PA 17033).
86.
Twenty split thickness skin donor sites were partially covered by fresh or frozen human amniotic membrane (HAM) obtained from vaginal deliveries as a physiologic dressing. The HAM had been separated from the chorion, washed and stored in 1% neomycin. Those frozen were stored in liquid N after slow freezing in 20% glycerol. Punch biopsies of the donor wound were done at 3, 5 and 7 days after application. No vascularization of the HAM occurred. No evidence of
ABSTRACTS
333
accelerated donor site epithelialization occurred. The loss of cellular architecture in succeeding biopsies confirmed that the HAM became nonviable and dessicated while remaining adherent to the wound. All patients have noted less discomfort than usual. Seventeen patients with partial thickness burns have been similarly treated with excellent pain relief. Twenty rats had fresh or frozen HAM placed on open wounds on the panniculus carnosus. A similar implant was placed in a subcutaneous pocket on the other side. Intracardiac injections of India ink were made. No vasculariaation occurred after 3-5 days. A thick fibrous capsule developed after 5 days. Twenty other rats had fresh or frozen HAM placed in a single layer beneath a bipedicle thoracic flap. No vascularization occurred 5-7 days postimplantation. The reactions around the two types of implants were comparable, although cellular preservation of the fresh HAM was better. Tissue cultures of the frozen HAM showed cellular growth after thawing. Applied to open wounds, HAM adhere without becoming vascularized and provide a protective dressing. The pain of donor sites and partial thickness burns is reduced. Acceleration in wound healing could not be substantiated. 87. Effects of low Acetylcholinesterase
Temperature Acclimation on Activity in Insect Central
Tissue. J. G. BAUST (Department of Biology, State Universit.y of New York. Geneseo, NY 14454).
Nervous
The properties of acetylcholinesterase from the central nervous tissue of two Alaskan beetles, Upis ceramboides and Pterostichus brevicornis, were examined over the above freezing physiological temperature range. Specimens acclimated to ‘(summer” conditions (1520°C) demonstrated temperature optima approximating the ambient exposure. Low temperature acclimat.ed specimens, however, demonstrated no temperature optima for act.ivity, and hence, the acetylcholinesterase syst,em appeared independent of exposure temperatures. The activation energies, calculated form Arrhenius plots (log V,,, vs l/temperature) did not correlate with acclimation temperature. It is suggested that the evolutionary adaptation of this enzyme to temperature change has involved enzyme affinity for substrate. 88. Variations in Receptor and Central Nervous Excitability in Low Temperature-Acclimated Insects. J. G. BAUST (Department of Biology, State
University of New York, Geneseo, NY 14454).
MEETING
85. Limitations of Cryosurgical Techniques for tumors. A. A. GAGE (Department of Surgery, Veterans Administration Hospital, Buffalo, NY 14215). Experience with the treatment of over 200 patients with malignant tumors by freezing in situ in the past 8 years has revealed several problems which must be considered if cryosurgery is to gain a place in surgical practice. One is the difficulty in determining the extent of freezing, especially when treatment is given via endoscopy. Even when vision is good, determination of depth of freezing is difficult to ascertain. Formulas have been developed to predict the thermodynamic growth of ice balls around cryoprobes but these are not practical for use in clinical cryosurgery. Considerable reliance must be based on the use of needle thermocouples in the tissues. Although in general, the results of treatment have been good, it has become evident that further progress in the development of the technique depends on the solution of problems related to freezing limitations of the cryosurgical apparatus. Faulty freezing of tumors led to experiments with three types of cryosurgical apparatus using liquid nitrogen. Closed cryogenic systems and spray techniques were used, yet there always existed the difficulty of freezing the large volumes of tissues necessary in cancer treatment. Vagaries in liquid nitrogen flow were seen in some experiments. Unsuspected variations in the quality of cont,act between probe and tissues due to faulty technique resulted in considerable differences in surface and deep tissue temperatures. Our experience, experimental and clinical, has shown that cryosurgical equipment needs considerable improvement in design and function and cryosurgical t,echnique must be carefully learned and applied. Human Amniotic Membrane as a Physiologic Wound Dressing. G. COLLOCHO,’ W. P. GRAHAM .4m W. GREEN (Lovelace Clinic, Albuquerque, New Mexico 87108 and Department of Surgery, Milton S. Hershey Medical Center. Hershey, PA 17033).
86.
Twenty split thickness skin donor sites were partially covered by fresh or frozen human amniotic membrane (HAM) obtained from vaginal deliveries as a physiologic dressing. The HAM had been separated from the chorion, washed and stored in 1% neomycin. Those frozen were stored in liquid N after slow freezing in 20% glycerol. Punch biopsies of the donor wound were done at 3, 5 and 7 days after application. No vascularization of the HAM occurred. No evidence of
ABSTRACTS
333
accelerated donor site epithelialization occurred. The loss of cellular architecture in succeeding biopsies confirmed that the HAM became nonviable and dessicated while remaining adherent to the wound. All patients have noted less discomfort than usual. Seventeen patients with partial thickness burns have been similarly treated with excellent pain relief. Twenty rats had fresh or frozen HAM placed on open wounds on the panniculus carnosus. A similar implant was placed in a subcutaneous pocket on the other side. Intracardiac injections of India ink were made. No vasculariaation occurred after 3-5 days. A thick fibrous capsule developed after 5 days. Twenty other rats had fresh or frozen HAM placed in a single layer beneath a bipedicle thoracic flap. No vascularization occurred 5-7 days postimplantation. The reactions around the two types of implants were comparable, although cellular preservation of the fresh HAM was better. Tissue cultures of the frozen HAM showed cellular growth after thawing. Applied to open wounds, HAM adhere without becoming vascularized and provide a protective dressing. The pain of donor sites and partial thickness burns is reduced. Acceleration in wound healing could not be substantiated. 87. Effects of low Acetylcholinesterase
Temperature Acclimation on Activity in Insect Central
Tissue. J. G. BAUST (Department of Biology, State Universit.y of New York. Geneseo, NY 14454).
Nervous
The properties of acetylcholinesterase from the central nervous tissue of two Alaskan beetles, Upis ceramboides and Pterostichus brevicornis, were examined over the above freezing physiological temperature range. Specimens acclimated to ‘(summer” conditions (1520°C) demonstrated temperature optima approximating the ambient exposure. Low temperature acclimat.ed specimens, however, demonstrated no temperature optima for act.ivity, and hence, the acetylcholinesterase syst,em appeared independent of exposure temperatures. The activation energies, calculated form Arrhenius plots (log V,,, vs l/temperature) did not correlate with acclimation temperature. It is suggested that the evolutionary adaptation of this enzyme to temperature change has involved enzyme affinity for substrate. 88. Variations in Receptor and Central Nervous Excitability in Low Temperature-Acclimated Insects. J. G. BAUST (Department of Biology, State
University of New York, Geneseo, NY 14454).