Iacuc review of genetic engineering.
IACUC approval of research using genetically engineered animals must balance research needs with humane treatment of the animals, safety of animals and personnel, and compliance with regulations.
Journal Article↗
Biomedical subjects
M B Dennis
Publications and source records attributed to M B Dennis.
1998 ACLAM forum: "Bioethics and the Use of Laboratory Animals: Ethics in Theory and Practice".
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Animals↗
Sepsis of vascular catheters. II: In vitro disinfection of colonized tubing.
Preparatory to development of in situ disinfection of implanted catheters, silicone rubber tubing colonized by incubation with Staphylococcus aureus, Staphylococcus epidermidis, or Klebsiella pneumoniae was used to test the efficacy of various chemicals in vitro. Protocols sterilizing all segments colonized for 24 h (n = 30) were immersion into 50% povidone iodine for 5 and 60 min, 100% povidone iodine for 5, 15, and 60 min, 1.2 x 10(3) ppm chlorine dioxide for 15 and 60 min, and 1.2 x 10(3) ppm chlorine dioxide buffered to pH 5.1 for 60 min. Immersion in up to 2% chlorhexidine, 7.4% formaldehyde, or 6% sodium hypochlorite for up to 60 min failed to sterilize all segments. None of 117 control segments were sterilized. Segments colonized for seven days were sterilized by immersion into 100% povidone iodine for 15 or 60 min. Use of 1.2 x 10(3) ppm chlorine dioxide for 60 min sterilized 97% of segments tested. Lower concentrations and shorter exposure times failed to sterilize all segments. Eighteen silicone rubber catheters, colonized on the outer surface, were all sterilized within 24 h by a chlorine dioxide solution placed in the lumen and diffusing through the wall to kill the bacteria.
Catheterization↗
The synthesis of L-tryptophan degrading bioreactors.
To design a bioreactor for removing the potential cancer nutrient L-tryptophan from blood, the L-tryptophan degrading enzyme tryptophan side chain oxidase (TSO) was chemically bound to glutaraldehyde activated gamma amino silane silica and to Zetaffinity microcolumns consisting of a glutaraldehyde activated polyacrylic-cellulose copolymer. Five experiments were carried out in sheep and six experiments in rabbits using a closed circuit plasmapheresis bioreactor system. L-tryptophan in sheep was degraded by the silica bioreactor in a single pass to undetectable levels as measured by high performance liquid chromatography (HPLC). Zetaffinity bioreactors degraded L-tryptophan in rabbits to more than 95% in a single pass. Whole blood L-tryptophan levels changed little throughout the experiment indicating a vast extravascular tryptophan pool. Enzyme leakage from the bioreactor was less than 10(-5) IU TSO per ml plasma. The procedures were tolerated well by the animals without any change in vital signs.
Animals↗
Chlorine dioxide sterilization of implanted right atrial catheters in rabbits.
The disinfection of right atrial catheters in situ using chlorine dioxide was investigated. Catheters were implanted into rabbits (Oryctolagus cuniculi) and colonized by inoculation of Staphylococcus aureus, Sa-80, into the lumen. All of the catheters were colonized and the difference in numbers of bacteria recovered from animals destined for the control and disinfection groups was not significant. Animals were assigned randomly to the control or disinfection group. Treatment consisted of filling the catheter lumen of the disinfection group with chlorine dioxide and of the control group with sterile physiological saline daily for 15 minutes. In addition, both groups received systemic antimicrobial therapy. Cultures of blood withdrawn from the catheters and by venipuncture were negative for five of the nine control group animals after treatment for 5 days. Four control group catheters failed, after from 3 to 21 treatments, without ever achieving negative cultures. All nine animals in the disinfection group had negative cultures after treatment for 5 days. Subsequently, one animal from each group reverted to positive cultures. All nine control group catheters failed during the study, compared to only three disinfection group catheters (p less than 0.01). At necropsy, culture of cardiac blood, thrombi and catheter tubing sections demonstrated colonization of six in the control group and only one in the disinfection group (p less than 0.05). Rabbits tolerated the chlorine dioxide disinfection well and no adverse signs were noted.
Animals↗
Use of captive bolt as a method of euthanasia in larger laboratory animal species.
The penetrative captive bolt pistol was tested on dogs (Canis familiaris) and rabbits (Oryctolagus cunniculi) to assess if it is a humane method of euthanasia to use when a physical method is required. The bolt was placed directly on the skull at the intersection of lines drawn from the lateral canthus of each eye to the opposite ear, and fired. In all cases, consciousness appeared to be lost immediately as evidenced by motoric collapse of the animal and loss of the corneal reflex. The only movement noted appeared to be reflex in nature. In order to determine the time of onset of brain death, the auditory evoked potential (AEP) and electroencephalogram (EEG) were measured in dogs. Within 15 seconds after firing the pistol, organized AEP activity could not be detected above the medulla and EEG activity became isoelectric. These findings suggest that cerebral death occurred almost immediately and, therefore, the captive bolt pistol is a humane method of euthanasia.
Animals↗
Optic nerve head axonal transport in rabbits with hereditary glaucoma.
Rabbits with hereditary glaucoma develop ocular changes that resemble human congenital glaucoma and buphthalmia. The inheritance is autosomal recessive (bu). Previous research was performed primarily on albino bu/bu rabbits that were unhealthy and bred poorly. We have bred pigmented bu/bu rabbits to determine if this would improve hardiness and provide a better model for the disease in humans. First-generation offspring from matings of bu/bu albino with bu/bu pigmented rabbits were all affected, indicating that the bu gene is found at the same locus in both strains. The pigmented bu/bu offspring had a high degree of mortality, as reported previously for albino bu/bu rabbits. Newborn bu/bu rabbits initially had normal intraocular pressure (IOP; 15-23 mmHg); after 1- to 3 months, the IOP increased to 26-48 mmHg. The eyes became buphthalmic and the IOP returned to normal or sub-normal levels after 6-10 months. Since the lamina cribrosa is absent or poorly formed in the rabbit optic nerve head (ONH), this model was used to test the role of mechanical factors in the etiology of ONH pathology caused by increased IOP. Orthograde axonal transport was evaluated in both eyes from eight normal and 24 bu/bu rabbits of different ages, using intravitreal injections of [3H]leucine to mark orthograde axonal transport, followed by light- and electron-microscopic radioautography of the ONHs and superior colliculi. Normal rabbits of all ages showed no blockage of axonal transport in the ONH. All optic axons from young bu/bu rabbits with normal IOP and most axons from older buphthalmic rabbits that previously had elevated IOP were normal morphologically. Small zones of transport blockage occurred in bu/bu eyes while IOP was elevated; most affected axons lay immediately adjacent to ONH connective tissue beams that radiate outward from the central retinal vessels to the optic-nerve sheath. Thus, the rabbit, which lacks a true lamina cribrosa, does not show marked blockage of axonal transport as occurs in the LS of the monkey and cat ONH when IOP is elevated acutely. This anatomic difference appears to be protective against axonal damage, since bu/bu rabbits with chronic IOP elevation did not show significant loss of optic axons. These results are consistent with the proposed 'mechanical' theory of ONH damage resulting from increased IOP. Electron-microscopic radioautography revealed that chronically elevated IOP in bu/bu rabbits, which caused small foci of blocked ONH axonal transport against ONH beams, also caused degeneration of a few optic nerve terminals in the superior colliculi as the disease progressed.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Hereditary glaucoma and buphthalmia in the rabbit.
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Animals↗
Natriuretic effect of digoxin-like immunoreactive substance on dog kidney.
We previously reported that digoxin-like immunoreactive substance (DLIS) was found only in the blood of those dialysis patients who were hypertensive and had high systemic vascular resistance. In order to determine whether the DLIS was a marker for the natriuretic hormone, renal infusion studies were carried out in anesthetized dogs. When ultrafiltrates from patients with high blood DLIS levels were infused into the renal artery of one kidney there was a significant increase in the fractional excretion of sodium (FE Na) from its baseline value. Further, the FE Na of these kidneys were significantly higher than the FE Na noted for the contralateral kidneys which were simultaneously infused with ultrafiltrates obtained from dialysis patients lacking DLIS activity in their blood. We conclude that the DLIS is or represents a marker for natriuretic hormone. Since the natriuresis noted was independent of renal plasma flow and glomerular filtration rate and since the fractional excretion of potassium was not influenced by the infusion, we believe that DLIS is different from atrial natriuretic factor.
Animals↗
An animal model for fungal peritonitis: evaluation of therapeutic options.
An animal model for fungal peritonitis was developed and is described. This model was used to compare various therapeutic options for Candida albicans peritonitis. Twenty-four rabbits were treated on three different protocols. Results from these protocols confirm the clinical observation that removal of the catheter is necessary for successful treatment of fungal peritonitis. Further, the combination of catheter replacement and imidazole anti-fungal therapy appears to be curative in this animal model, and suggests that by using this protocol, discontinuation of peritoneal dialysis may not be necessary.
Administration, Oral↗
Comparison of four methods of cleaning hollow-fiber dialyzers for reuse.
Four methods of cleaning hollow-fiber artificial kidneys (HFAKs) for reuse were compared in a prospective study. Each cleaning method was randomly assigned and HFAKs were reused until volume loss was greater than or equal to 15 ml, unless discarded for other reasons. HFAKs cleaned with 0.3 M sodium hydroxide averaged 14.5 uses, significantly better (p less than 0.01) than reverse ultrafiltration (6.4 uses), 3% hydrogen peroxide (5.7 uses), or water flush (4.7 uses). Only 1 of 10 HFAKs cleaned with NaOH was discarded owing to volume loss, whereas 25 of 30 HFAKs cleaned by the other methods were rejected for this reason. To relate changes in solute clearance to volume loss, urea and creatinine clearances were determined on HFAKs cleaned by water flush. By the fifth use the average volume had declined to 86.3% of original, but creatinine and urea clearances were reduced, respectively, to 97 and 95% of the original values.
Disposable Equipment↗
Long-term blood access by catheters implanted into arteriovenous fistulas of sheep.
Reliable long-term blood access in sheep was provided by implanting one or two catheters into the high velocity blood flow in the vein draining an arteriovenous fistula created in the neck. Thrombosis of the catheterized vein occurred in only one of 31 cases in which a catheter with rounded intravascular tip was used, as compared with seven in 10 cases using a sharp-tipped catheter. The mean duration of placement for all rounded-tip catheters was 228.6 days. Extrusion from the vessel occurred with 3 of 8 short catheters (2 cm intravascular length), but only after a period of more than seven months of implantation. Using a program of trice-weekly disinfection of the skin exit site, exterior portion of the catheter, and catheter lumen resulted in failure of only two catheters due to infection. Rounded-tip catheters with 5 cm intravascular length had 75% life table functional rate at 15 months. Implantation of two catheters permitted extracorporeal circulation at flows of up to 300 ml/min using a blood pump to withdraw blood from one catheter while simultaneously returning it through the second.
Animals↗
Successful long-term use of a plasmapheresis reactor system in dogs with lymphoma.
The successful long-term use of asparaginase-glutaminase reactor in dogs with lymphoma is described. The limitations of the system consisting of an activation of enzymes leading to rapid neosynthesis of asparagine and glutamine are outlined. The possible beneficial effect of future combination therapy with amino acid analogues is discussed.
Animals↗
Successful in vivo experiments in sheep using a new nonhydrolyzable enzyme reactor resistant against tryptic digestion.
Blockage of E-amino groups of asp-ase bound to cellulose by succinylation results in a greatly enhanced resistance against tryptic digestion by "plasma enzymes." Plasmapheresis in sheep by plasma filters connected to asp-ase Cellulose cartridges led to decrease of asp-NH2 and glut-NH2 in plasma over 21 hrs with undetectable enzyme leakage from the solid phase.
Animals↗
Glutaraldehyde-treated xenocells: a specific adsorbent for complement factors.
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Adsorption↗
Synthesis of enzyme reactors consisting of xenocells.
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Adsorption↗
Evaluation of Nd:YAG photocoagulation using a new experimental ulcer model with a single bleeding artery.
A new model of an acute bleeding gastric ulcer with a single bleeding artery in its base has been developed. A suction ulcer defect is created over a large, submucosal artery. Small bleeding marginal vessels are electrocoagulated with a fine-tipped bipolar forceps. The artery in the base of the ulcer is dissected free and then incised longitudinally; brisk bleeding results. A combination of heparin, aspirin, and dipyridamole is used to prevent spontaneous hemostasis. Bleeding from the incised artery of the single vessel ulcer does not decrease over a 10-min interval. No damage to the muscularis externa of the underlying gastric wall results from preparation of the ulcer. The effect of Nd:YAG laser photocoagulation in this new model was compared with the results of photocoagulation in the standard suction ulcer model. In both models the Nd:YAG laser stopped equivalent bleeding from all ulcers. However, there was a marked difference in the depth of tissue injury, with much less damage observed in the single vessel ulcer. This model may provide a better method to assess depth of tissue injury resulting from endoscopic hemostatic techniques.
Animals↗
The bio-artificial organ: review and progress report.
A definition and a review is given for the bioartificial organ. In addition new developments are reported with the successful lyophilization of enzyme filled RCG with cryoprotective polyethylene glycol (PEG). The successful use of an enzyme reactor consisting of crosslinked fibrin with asparaginase covalently attached is reported in sheep. The small organ (0.4 m2) removes 70% of the animal's asparagine in 6 hours. No enzyme leakage down to 10(-5) units per ml. plasma could be found. The highly preserved substrate affinity of insolubilized asparaginase as well as its high activity and stability when bound to fibrin are additional outstanding features of this system.
Animals↗