Retrospective comparison of rat recovery weights using inhalation and injectable anaesthetics, nutritional and fluid supplementation for right unilateral neurosurgical lesioning.

Current veterinary standards of biomedical research support include refinements in animal models that are targeted at enhancing humane care and decreasing inter-animal variability. This ultimately results in fewer numbers of animals being used and reduction in animal experimentation through mitigation of waste as well as faster research results. 6-hydroxydopamine-lesioning of the substantia nigra using a stereotactic frame device is a common procedure and is routinely performed under pentobarbital anaesthesia with monitoring by 8 h workforces. Our programme supports the humane care and use of several protocols involving the unilateral stereotactic-lesioning of rats for the purposes of creating research models of Parkinsonianism. Such procedures are commonly performed as unilateral in order to minimize aphagia and other untoward effects of the lesion. Generally, this procedure is considered minor because it involves a small incision, a cranial burrhole, and penetration of the dura. Inflammation and/or irritation of the ear canal can occur secondarily to the earbar placement procedure. Human patients undergoing similar procedures typically complain of headaches from loss of intracranial pressure; which is a transient outcome. Despite the perception of minor insult, we provided aggressive periprocedural care, and our veterinary staff documented weight loss that was often greater than 15% body weight during the first 3 days. The goal of this study was to evaluate refinements to improve this outcome. For humane concerns, and because of the need to begin experimental testing one week following surgery, a goal in the recent past has been to enhance outcome for researchers and animals by refining postoperative support modalities as well as by seeking the best anaesthetic regimen to shorten postoperative deviations from baseline. Analysis of three groups of rat patients lesioned by the same investigative group over the course of refinements made in our programme indicate that an early return of homeostasis was achieved by the use of inhalation anaesthetics as replacements for barbiturates in these models. Comparison with pentobarbital recipients also indicated that homeostasis is achieved earlier when barbiturates are utilized with fluid therapy and analgesics immediately after operative procedures rather than the next morning.

Handheld digital equipment for weight composite distress paradigms: new considerations and for rapid documentation and intervention of rodent populations.

Animal care in the third millennium will require a melding of scientific and humane interests to achieve optimal care of genetically engineered mice and to expedite scientific and medical advances by using these mammals. Undoubtedly, rodent patients present certain difficulties for those who wish to assess their daily well-being and to contribute to efficient and successful scientific discovery. High-density housing, large experimental groups, and low-lux room lighting makes the application of large-animal care standards to rodents seem daunting to researchers and veterinary care programs. In addition, great variability in training and experience among those responsible for the direct application of humane care to rodents exists. Most of the direct animal care in small animal facilities occurs in decentralized locales by personnel who have completed obligatory but relatively minimal animal care training. Examples of personnel in this category include postdoctoral fellows, junior-level scientists, summer students, and assistant laboratory animal technologists. Some programs even use the husbandry staff to perform health checks of high-risk populations on a daily basis. For this reason, the extrapolation of performance-based intervention in rodent care is difficult to apply practically. Early efforts to enhance humane outcome in rodents have been published by scientists and veterinarians and are largely directed at singular endpoints, such as weight loss and declining temperatures, in specific models. Scientists often are reluctant to accept such standards because of concern about premature intervention or variability between scorers and to reservations regarding a lack of procedural likeness with their proposed study. This paper highlights a digital method for melding current advanced animal scoring standards using palm pilot user-friendly methods that account for composite weight scoring, behavioral or physiologic attributes, and interventions. Information is rapidly downloaded and results in quick storage of large rodent population monitoring. This minimizes interpretative variability between caregivers and greater standardization of procedures. These considerations facilitate the rapid diagnosis of outliers and make possible intervention that streamlines the delivery of humane care to large experimental populations.

Challenges in small animal noninvasive imaging.

The current status and challenges of small animal non-invasive imaging is briefly reviewed. The advantages of non-invasive studies on living animals versus post-mortem studies are evaluated. An argument is advanced that even in post-mortem situations, non-invasive imaging may play an important role in efficiently characterizing small animal phenotypes as well as pathology. Issues of data interpretation under anesthetized conditions in live animal studies are also reviewed. The five imaging technologies covered include CT, PET, ultrasound, MRI and optical imaging. The structural and physiological information content of these different modalities is reviewed along with the ability of these techniques to scale down for use in small mammals such as mice and rats. In general, it was found that most of these technologies scale favorably to the study of small mammals, generally providing more physiological information than when used on the larger human scale. This suggests that these types of small mammal imaging capabilities will play a very significant role in the full utilization of these important animal models in biomedical research.

Thoracoscopy as a nonpharmacotherapeutic research modification for limiting postoperative chest pain.

Diminished tissue injury and shortened clinical recovery are benefits of using an endoscopic approach for patients needing operative procedure. In the course of developing an experimental model requiring procurement of topographically precise lung biopsy specimens, we sought to apply thoracoscopy as a research alternative to thoracotomy. In addition, we investigated the influence of thoracoscopy on postprocedure recovery practices using rabbits divided into four treatment groups. Rabbit groups 1 and 2 underwent thoracoscopy and lung biopsy while maintained by one-lung anesthesia. Additionally, group 2 had ketoprofen and bupivacaine HCl analgesics injected for treatment during postprocedure recovery. These two groups were compared to control rabbits in groups 3 and 4, which underwent inhalant anesthesia without thoracoscopy. Control group 3 also received the injection analgesic combination. During recovery, rabbit behavior was systematically assessed for evidence of pain. No behavior considered indicative of pain needing intervention was observed regardless of treatment group. Limited changes in plasma corticosterone, catecholamines, and prostaglandin E2 levels measured during recovery were difficult to associate with any treatment. Unexpectedly, significantly different mean corticosterone and catecholamines levels were detected in rabbits given the injection analgesic combination in the absence of thoracoscopic procedure, as compared to other treatment groups. The results highlight the importance of awareness that analgesic drug administration has the potential to alter homeostasis and affect interpretation of some study findings by its own guise. Correlation of the mean pain study results with plasma biochemical data supports preferential use of thoracoscopy as a refinement for limiting postprocedural pain in research models.

Red-carpet rodent care: making the most of dollars and sense in the animal facility.

Cutting-edge biomedical research programs have entered an era in which phenotypic characterizations for genetically altered rodents can facilitate appropriate care. The veterinary care requirements necessary to support such animal models can include the procedures already adapted as standard practice in companion animal hospitals, and can decrease data variability while increasing survival rates.

Technical team approaches to rodent care: cost savings, reduced risk, and improved stewardship.

With the increasing decentralization of animal care operations, lack of training and higher-density animal rooms make achieving humane assurances difficult. To offset these problems, some facilities have developed centralized animal care programs, including dispersed teams of qualified animal care specialists.

Chronic intermittent stimulation of the thyroarytenoid muscle maintains dynamic control of glottal adduction.

Patients with laryngeal motor control disorders need improved dynamic glottal closure for speech and swallowing. To evaluate the functional outcome of intermittent chronic thyroarytenoid muscle stimulation in an animal model, 6 canines were implanted with bilateral Medtronic Xtrel systems containing Peterson-type electrodes in the inferior and superior portions of the thyroarytenoid muscle. Stimulation was on one side only at 60 Hz, for 5 s on and 5 s off, over 8 h, 5 days per week, up to 8 months. Monthly videorecordings were done under anesthesia to measure the voltage threshold for detectable movement on each side, and vocal fold displacement and velocity during maximal stimulation of each side. Movement thresholds were lower in the inferior portion of the thyroarytenoid muscle (P

Three-dimensional changes in the upper airway during neuromuscular stimulation of laryngeal muscles.

During swallowing, airway protection depends upon adequate glottal closure and laryngeal elevation to prevent the entry of substances into the airway. Three-dimensional changes in the upper airway during laryngeal muscle stimulation in a canine model were quantified in animals implanted with Peterson type stimulating electrodes in the inferior and superior portions of the thyroarytenoid muscle, together with a reference electrode. Computer tomography scanning was performed on an IMATRON scanner with a 3 mm slice thickness advanced at overlapping 1 mm increments. Stimulation of the thyroarytenoid muscle produced adductions of the vocal fold towards the midline and changes in the supraglottic region as well as the glottis; the glottic wall was compressed medially above and below the glottis. These results suggest that chronic neuromuscular stimulation can effect glottic protection by reducing the glottal opening and may be beneficial for patients with central control disorders affecting airway protection during swallowing.

Protection of mitomycin C induced skin extravasation with the nitroxide, 3-carbamoyl-PROXYL (3-CP).

Extravasation tissue injury from chemotherapeutic drugs is a serious clinical problem. A swine model has been useful for studying skin extravasation and evaluating potential antidotes. Mitomycin C (MMC) skin extravasation was studied. Nitroxides, a class of compounds which are protective against a variety of oxidative stresses in vitro, including MMC, were tested as antidotes. Miniature swine were anesthetized and given intradermal (ID) injections of MMC. MMC alone caused skin necrosis and ulceration. Several nitroxides were screened as protectors of MMC induced skin necrosis. 3-carbamoyl-PROXYL (3-CP) was the lone nitroxide which protected if given 5 min after extravasation. Administration of 3-CP 10 min after MMC injection was not protective. In vitro studies with monolayered V79 cells showed that 3-CP had a direct protective effect against MMC cytotoxicity in a concentration-dependent fashion. Therefore, in the swine model doses of 3-CP ranging from 25-100 mM were tested and found to protect against MMC skin necrosis 90 days after injection. Histologic sections of the 3-CP- and MMC-treated pig skin showed a marked reduction in the degree of acute inflammation and the absence of deep dermal scarring when compared to MMC alone.

The derivation and characterization of pig keratinocyte cell lines that retain the ability to differentiate.

Pig skin may be a very useful model for studying human skin biology, since its morphology closely resembles that of human skin. To manipulate pig keratinocytes in vitro, we have analyzed different culture conditions for optimal pig keratinocyte growth and describe here a simple method for culture and extended passage of primary pig keratinocytes on collagen substrates. The colony-forming efficiency and proliferative capacity of primary pig keratinocytes were readily supported by Type I collagen and a final calcium concentration of 0.075 microM. These culture conditions permitted efficient gene transfer into keratinocytes using various cationic lipids at a 4:1 ratio (lipid: DNA). In addition, immortalized pig keratinocyte cell lines, which maintained a normal phenotype, were derived using these optimized culture conditions. By karyotype analysis, two independently derived cell lines had the same chromosomal abnormalities, suggesting a causal role in their immortalization. The keratinocyte cell lines exhibited a differentiated phenotype in response to elevated calcium concentration and were nontumorigenic in in vivo tumor assays. Immortalized pig keratinocyte cell lines that maintain the ability to differentiation may become a valuable tool in the study of epidermal differentiation both in vitro and in vivo. In addition, methods using keratinocytes to deliver genes to pigs in vivo could also be enhanced with these pig keratinocyte cell lines.

Clinical toxicity of peripheral nerve to intraoperative radiotherapy in a canine model.

PURPOSE: The clinical late effects of intraoperative radiotherapy (IORT) on peripheral nerve were investigated in a foxhound model. METHODS AND MATERIALS: Between 1982 and 1987, 40 animals underwent laparotomy with intraoperative radiotherapy of doses from 0-75 Gy administered to the right lumbosacral plexus. Subsequently, all animals were monitored closely and sacrificed to assess clinical effects to peripheral nerve. This analysis reports final clinical results of all animals, with follow-up to 5 years. RESULTS: All animals treated with > or = 25 Gy developed ipsilateral neuropathy. An inverse relationship was noted between intraoperative radiotherapy dose and time to neuropathy, with an effective dose for 50% paralysis (ED50) of 17.2 Gy. One of the animals treated with 15 Gy IORT developed paralysis, after a much longer latency than the other animals. CONCLUSIONS: Doses of 15 Gy delivered intraoperatively may be accompanied by peripheral neuropathy with long-term follow-up. This threshold is less than that reported with shorter follow-up. The value of ED50 determined here is in keeping with data from other animal trials, and from clinical trials in humans.

Effects of intraoperative radiotherapy on vascular grafts in a canine model.

PURPOSE: The effects of intraoperative radiotherapy +/- external beam radiotherapy on prosthetic vascular grafts were investigated in a canine model. METHODS AND MATERIALS: In 1986 and 1987, 30 adult beagles underwent laparotomy with transection and segmental resection of the infrarenal aorta followed by immediate reconstruction with a prosthetic graft. Intraoperative radiotherapy at varying doses from 0-30 Gy was then administered to all animals. Half of the dogs received 36 Gy external beam radiotherapy in 10 fractions postoperatively. Animals were sacrificed and necropsied at predetermined intervals and as clinically indicated to assess early (< or = 6 months) and late (> 6 months) effects to the vascular graft and surrounding normal tissue. RESULTS: Histopathologic analyses of irradiated vascular structures were performed and correlations were made with the clinical outcome. The most frequent early clinical toxicity was graft thrombosis, occurring in 7 of 10 animals followed for < or = 6 months. Early graft thrombus formation appeared unrelated to radiotherapy dose and probably represented a technical surgical complication. Anastomotic stenosis of varying severity occurred in most animals followed > 6 months. Late (> 6 months) graft stenosis was correlated with intraoperative radiotherapy dose. At < or = 20 Gy of intraoperative irradiation, 3 of 14 animals developed late graft occlusion; at > 25 Gy, five of six animals developed late occlusion. On histopathologic review, increasing intraoperative dose and increasing total radiotherapy dose (intraoperative+external beam) appeared to correspond with increasing severity of graft changes seen after 6 months of follow-up. CONCLUSIONS: Thrombus formation is a frequent early complication of vascular graft placement of the infrarenal aorta in our beagle dog model. Intraoperative doses up to 20 Gy appear to contribute minimally to late graft occlusion, while doses > or = 25 Gy contribute to late occlusion with high likelihood. Both intraoperative dose and total radiotherapy dose correlated with late graft occlusion, and with histopathologic changes in the graft and anastomoses.

Hemodynamics and metabolism during surface-induced hypothermia in the dog: a comparison of pH management strategies.

The management of blood pH during hypothermia remains controversial. The present study was designed to determine whether hemodynamics and oxygen consumption during hypothermia are different between the alpha-stat and pH-stat strategies. Theoretical considerations of enzyme kinetics suggest that the alpha-stat strategy would result in a higher oxygen consumption during hypothermia. Because hypothermia is used to decrease oxygen consumption for protection during ischemia, a pH scheme that results in a greater oxygen demand for any level of ischemia would be detrimental. The core temperature of 22 dogs was lowered to 26 degrees C by combined surface cooling and gastric irrigation. Either the alpha-stat (N = 9) or the pH-stat (N = 13) pH strategy was used. The arterial pressure was different between the two groups at 26 degrees C (65 +/- 6 vs 85 +/- 6 mm Hg, alpha-stat vs pH-stat, respectively, P less than 0.05). Neither systemic oxygen consumption nor the Q10 was different between groups. There were no differences in any other hemodynamic parameters. In summary, during moderate hypothermia alpha-stat pH management results in an arterial pressure lower than that of pH-stat management, possibly resulting in improved peripheral perfusion. Despite theoretical predictions, the alpha-stat pH scheme does not result in an oxygen consumption higher than that of the pH-stat scheme.