Craig L. Wardrip

Induced hypothermia by central venous infusion: Saline ice slurry versus chilled saline

Objective:Surface cooling improves outcome in selected comatose survivors of cardiac arrest. Internal cooling with considerable volumes of intravenous cold saline may accelerate hypothermia induction. This study compares core temperatures in swine after central catheter infusions of saline ice slurry (saline with smoothed 100-&mgr;m-size ice particles) vs. an equal volume of chilled saline. We hypothesized that slurry would achieve core hypothermia (32–34°C) more consistently and at a faster rate. Design:A total of 11 swine were randomized to receive microparticulate ice slurry, chilled saline infusion, or anesthesia alone in a monitored laboratory setting. Interventions:Intravenous bolus (50 mL/kg) of slurry or chilled 1.5% NaCl saline. Slurry was composed of a 1:1 mixture of ice and distilled H2O plus NaCl. Measurements:Cerebral cortex, tympanic membrane, inferior vena cava, rectal temperatures, electrocardiogram, arterial blood pressure, and arterial oxygen saturation were recorded for 1 hr after bolus. Main Results:Compared with anesthetized controls, core brain temperatures of the saline and slurry groups dropped by 3.4 ± 0.4°C and 5.3 ± 0.7°C (p = .009), respectively. With an infusion rate of 120 mL/min, cooling rates for the saline and slurry groups were −11.6 ± 1.8°C/hr and −18.2 ± 2.9°C/hr, respectively, during the first 20 mins. Four of four animals in the slurry group vs. zero of four animals in the saline group achieved target cortical temperatures of <34°C. Conclusions:Cold intravenous fluids rapidly induce hypothermia in swine with intact circulation. A two-phase (liquid plus ice) saline slurry cools more rapidly than an equal volume of cold saline at 0°C. Ice-slurry could be a significant improvement over other cooling methods when rate of cooling and limited infusion volumes are important to the clinician.

Electron paramagnetic resonance oxygen imaging of a rabbit tumor using localized spin probe delivery.

PURPOSE Application ofin vivo electron paramagnetic resonance (EPR) oxygen imaging (EPROI) to tumors larger than those of mice requires development of both instrumental and medical aspects of imaging. METHODS 250 MHz EPR oxygen imaging was performed using a loop-gap resonator with a volume exceeding 100cm3. The paramagnetic spin probe was injected directly into the femoral artery feeding the rabbit leg/tumor. RESULTS The authors present continuous wave and electron spin echo EPR oxygen images of a large size (4 cm) VX-2 tumor located on the leg of a New Zealand white rabbit. CONCLUSIONS This study demonstrates the feasibility of continuous wave and electron spin echo oxygen imaging modalities for investigation of volumes of tumor and normal tissue relevant to large animals. The injection of the spin probe directly into the artery feeding a rabbit leg will allow one to reduce, by over one order of magnitude, the amount of spin probe used as compared to whole animal IV injection.

Respiratory Diseases of Rodents and Rabbits

This article is written to provide differential diagnostic help for the practitioner who suspects respiratory disease in rodents or rabbits. The authors are laboratory animal veterinarians who work with rodents and rabbits on a herd health basis but also have considerable experience dealing with individual mice, rats, guinea pigs, hamsters, gerbils, and rabbits. The article presents descriptions of the presentation, pathology, treatment, and control of the primary respiratory pathogens of these species, along with an explanation of conditions that may confuse the diagnostic efforts. The article also mentions reported pathogens of secondary importance and provides extensive references.

Comparison of thyroidectomized calf serum and stripped serum for the study of thyroid hormone action in human skin fibroblasts in vitro.

BACKGROUND Knowledge on the action of thyroid hormone (TH) is augmented by the study of tissue responses to TH in vitro. In order to support the growth of cells in vitro, calf serum (CS) is usually added to the medium to provide necessary nutrients and growth factors. However, the content of endogenous TH in the CS may obfuscate changes with small doses of TH. We therefore compared the use of TH-depleted medium, either by resin treatment (stripped-CS) or by the use of CS from a thyroidectomized calf (TxCS) for gene expression studies. METHODS We describe the method for preparing a thyroidectomized calf, harvesting the blood and preparing the serum. We utilized methimazole in conjunction with the thyroidectomy to prevent TH synthesis in the event of regrowth of the thyroid remnant. RESULTS Total triiodothyronine (T(3)) and thyroxine concentrations in TxCS were low at <30 ng/dL and <1 microg/dL, respectively. We compared the effect of T(3) on basic transcription element-binding protein (BTEB)1 and stanniocalcin (STC)-1 mRNA expression in human fibroblasts from a normal individual and a subject with resistance to TH (RTH) cultured in stripped-CS to TxCS and demonstrated that with stripped-CS and TxCS differences in the BTEB1 and STC-1 expression of normal and RTH fibroblasts could be detected. CONCLUSIONS Both stripped-CS and TxCS are suitable to detect subtle differences in TH responsiveness between normal and RTH human skin fibroblasts, yet TxCS is not as costly as stripped-CS and relatively easy to prepare.

Cavernosal nerve functionality evaluation after magnetic resonance imaging-guided transurethral ultrasound treatment of the prostate

AIM To evaluate the feasibility of using therapeutic ultrasound as an alternative treatment option for organ-confined prostate cancer. METHODS In this study, a trans-urethral therapeutic ultrasound applicator in combination with 3T magnetic resonance imaging (MRI) guidance was used for real-time multi-planar MRI-based temperature monitoring and temperature feedback control of prostatic tissue thermal ablation in vivo. We evaluated the feasibility and safety of MRI-guided trans-urethral ultrasound to effectively and accurately ablate prostate tissue while minimizing the damage to surrounding tissues in eight canine prostates. MRI was used to plan sonications, monitor temperature changes during therapy, and to evaluate treatment outcome. Real-time temperature and thermal dose maps were calculated using the proton resonance frequency shift technique and were displayed as two-dimensional color-coded overlays on top of the anatomical images. After ultrasound treatment, an evaluation of the integrity of cavernosal nerves was performed during prostatectomy with a nerve stimulator that measured tumescence response quantitatively and indicated intact cavernous nerve functionality. Planned sonication volumes were visually correlated to MRI ablation volumes and corresponding histo-pathological sections after prostatectomy. RESULTS A total of 16 sonications were performed in 8 canines. MR images acquired before ultrasound treatment were used to localize the prostate and to prescribe sonication targets in all canines. Temperature elevations corresponded within 1 degree of the targeted sonication angle, as well as with the width and length of the active transducer elements. The ultrasound treatment procedures were automatically interrupted when the temperature in the target zone reached 56 °C. In all canines erectile responses were evaluated with a cavernous nerve stimulator post-treatment and showed a tumescence response after stimulation with an electric current. These results indicated intact cavernous nerve functionality. In all specimens, regions of thermal ablation were limited to areas within the prostate capsule and no damage was observed in periprostatic tissues. Additionally, a visual analysis of the ablation zones on contrast-enhanced MR images acquired post ultrasound treatment correlated excellent with the ablation zones on thermal dose maps. All of the ablation zones received a consensus score of 3 (excellent) for the location and size of the correlation between the histologic ablation zone and MRI based ablation zone. During the prostatectomy and histologic examination, no damage was noted in the bladder or rectum. CONCLUSION Trans-urethral ultrasound treatment of the prostate with MRI guidance has potential to safely, reliably, and accurately ablate prostatic regions, while minimizing the morbidities associated with conventional whole-gland resection or therapy.

Surgery in Nonhuman Primates

Nonhuman primates (NHPs) are an attractive animal model not only in basic research, but also in studies of human disease conditions and select therapies. Historically, much has been learned from NHPs and applied to human medicine and surgery. NHPs offer phylogenetic proximity, and physical and cognitive similarities to man, well-defined anatomy and physiology, high intelligence and ease of adaptation. Researchers often rely on veterinarians’ general knowledge of surgery adapted to NHP manipulations. This chapter is a review of general surgical concepts and many procedures applied in contemporary biomedical research. It has been designed as a practical resource for veterinarians and researchers who work with NHPs. The text describes nonclinical concerns including ethics, safety, facilities, and cost. General principles of surgery and perioperative considerations are discussed in chronological fashion primarily using neuroscience surgical research techniques.

Focused post mortem dissection technique for harvest of rete mirabile in domestic swine (Sus scrofa)

Background Rete mirabile (RM) of the domestic pig is a popular animal model of arteriovenous malformations. The RM (Latin for ‘wonderful net)’ comprises the arterioarterial portal connecting ascending pharyngeal arteries and the internal carotid arteries, which exists in the skull base of even-toed ungulates. Although angiographic access of the RM is relatively easy, its post mortem procurement is complicated and its detailed technique has not been well described. Objective To present our focused post mortem dissection technique for undamaged and complete harvest of the RM. Materials and methods Fourteen domestic (40–70 lb (18–32 kg)) swine were used in this study. Angiographies were performed under general anesthesia in all animals. A 5F Berenstein catheter was used for angiography and a 014 microcatheter was used to obtain superselective angiography. A stepwise surgical dissection technique has been developed to efficiently harvest RM. Angiographic and surgical anatomy were also compared. Results The RM was supplied by bilateral ascending pharyngeal arteries. Bilateral anterior cerebral arteries, middle cerebral arteries, and the basilar system were identified rostral to the RM. Our surgical dissection technique was developed during a project to streamline harvesting of the RM and a stepwise description is as follows: (1) decapitate the swine by removing the head through the plane of the occiput and C1 vertebral body; (2) remove the tongue and oropharynx via a ventral approach; (3) dissect through the posterior pharyngeal wall identifying bilateral tympanic bullae and the basisphenoid bone; and (4) remove the basisphenoid bone about one and half inches above the rostral end of the tympanic bullae to fully expose the rete. Conclusions The RM can be procured efficiently and effectively with our technique, without requiring any sophisticated surgical devices.

Prostate tissue ablation with MRI guided transurethral therapeutic ultrasound and intraoperative assessment of the integrity of the neurovascular bundle

OBJECTIVES: Evaluation of the precision of prostate tissue ablation with MRI guided therapeuticultrasound by intraoperative objective assessment of the neurovascular bundle in canines in-vivo. METHODS: In this ongoing IACUC approved study, eight male canines were scanned in a clinical 3T Achieva MRI scanner (Philips) before, during, and after ultrasound therapy with a prototype MR-guided ultrasound therapy system (Philips). The system includes a therapy console to plan treatment, to calculate real-time temperature maps, and to control ultrasound exposures with temperature feedback. Atransurethral ultrasound applicator with eight transducer elements was used to ablate canine prostate tissue in-vivo. Ablated prostate tissue volumes were compared to the prescribed target volumes to evaluate technical effectiveness. The ablated volumes determined by MRI (T1, T2, diffusion, dynamic contrast enhanced and 240 CEM43 thermal dose maps) were compared to H&E stained histological slides afterprostatectomy. Potential ...