Xenotransplantation of porcine progenitor cells in an epileptic California sea lion (Zalophus californianus): illustrative case.

BACKGROUND: Domoic acid (DA) is a naturally occurring neurotoxin harmful to marine animals and humans. California sea lions exposed to DA in prey during algal blooms along the Pacific coast exhibit significant neurological symptoms, including epilepsy with hippocampal atrophy. OBSERVATIONS: Here the authors describe a xenotransplantation procedure to deliver interneuron progenitor cells into the damaged hippocampus of an epileptic sea lion with suspected DA toxicosis. The sea lion has had no evidence of seizures after the procedure, and clinical measures of well-being, including weight and feeding habits, have stabilized. LESSONS: These preliminary results suggest xenotransplantation has improved the quality of life for this animal and holds tremendous therapeutic promise.

An MRI protocol for anatomical and functional evaluation of the California sea lion brain.

BACKGROUND: Domoic acid (DOM) is a neurotoxin produced by some harmful algae blooms in coastal waters. California sea lions (Zalophus californianus) exposed to DOM often strand on beaches where they exhibit a variety of symptoms, including seizures. These animals typically show hippocampal atrophy on MRI scans. NEW METHOD: We describe an MRI protocol for comprehensive evaluation of DOM toxicosis in the sea lion brain. We intend to study brain development in pups exposed in utero. The protocol depicts the hippocampal formation as the primary region of interest. We include scans for quantitative morphometry, functional and structural connectivity, and a cerebral blood flow map. RESULTS: High-resolution 3D anatomical scans facilitate post hoc slicing in arbitrary planes and accurate morphometry. We demonstrate the first cerebral blood flow map using MRI, and the first structural tractography from a live sea lion brain. COMPARISON WITH EXISTING METHODS: Scans were compared to prior anatomical and functional studies in live sea lions, and structural connectivity in post mortem specimens. Hippocampal volumes were broadly in line with prior studies, with differences likely attributable to the 3D approach used here. Functional connectivity of the dorsal left hippocampus matched that found in a prior study conducted at a lower magnetic field, while structural connectivity in the live brain agreed with findings observed in post mortem studies. CONCLUSIONS: Our protocol provides a comprehensive, longitudinal view of the functional and anatomical changes expected to result from DOM toxicosis. It can also screen for other common neurological pathologies and is suitable for any pinniped that can fit inside an MRI scanner.

The relationship between physician humility, physician-patient communication, and patient health.

OBJECTIVE: Cultural portrayals of physicians suggest an unclear and even contradictory role for humility in the physician-patient relationship. Despite the social importance of humility, however, little empirical research has linked humility in physicians with patient outcomes or the characteristics of the doctor-patient visit. The present study investigated the relationship between physician humility, physician-patient communication, and patients' perceptions of their health during a planned medical visit. METHODS: Primary care physician-patient interactions (297 patients across 100 physicians) were rated for the physician's humility and the effectiveness of the physician-patient communication. Additionally, patients reported their overall health and physicians and patients reported their satisfaction with the interaction. RESULTS: Within-physician fluctuations in physician humility and self-reported patient health positively predicted one another, and mean-level differences in physician humility predicted effective physician-patient communication, even when controlling for the patient's and physician's satisfaction with the visit and the physician's frustration with the patient. CONCLUSIONS: The results suggest that humble, rather than paternalistic or arrogant, physicians are most effective at working with their patients. PRACTICE IMPLICATIONS: Interventions to improve physician humility may promote better communication between health care providers and patients, and, in turn, better patient outcomes.

Algal toxin impairs sea lion memory and hippocampal connectivity, with implications for strandings.

Domoic acid (DA) is a naturally occurring neurotoxin known to harm marine animals. DA-producing algal blooms are increasing in size and frequency. Although chronic exposure is known to produce brain lesions, the influence of DA toxicosis on behavior in wild animals is unknown. We showed, in a large sample of wild sea lions, that spatial memory deficits are predicted by the extent of right dorsal hippocampal lesions related to natural exposure to DA and that exposure also disrupts hippocampal-thalamic brain networks. Because sea lions are dynamic foragers that rely on flexible navigation, impaired spatial memory may affect survival in the wild.

People Claim Objectivity After Knowingly Using Biased Strategies.

People tend not to recognize bias in their judgments. Such "bias blindness" persists, we show, even when people acknowledge that the judgmental strategies preceding their judgments are biased. In Experiment 1, participants took a test, received failure feedback, and then were led to assess the test's quality via an explicitly biased strategy (focusing on the test's weaknesses), an explicitly objective strategy, or a strategy of their choice. In Experiments 2 and 3, participants rated paintings using an explicitly biased or explicitly objective strategy. Across the three experiments, participants who used a biased strategy rated it as relatively biased, provided biased judgments, and then claimed to be relatively objective. Participants in Experiment 3 also assessed how biased they expected to be by their strategy, prior to using it. These pre-ratings revealed that not only did participants' sense of personal objectivity survive using a biased strategy, it grew stronger.

Comparison of transdermal administration of fentanyl versus intramuscular administration of butorphanol for analgesia after onychectomy in cats.

OBJECTIVE: To compare postoperative discomfort assessed by subjective pain score and plasma cortisol concentrations in cats undergoing onychectomy that received analgesia by use of transdermal fentanyl (TDF) patches or an i.m. injection of butorphanol. DESIGN: Randomized prospective clinical trial. ANIMALS: 22 client-owned cats weighing 2.2 to 5 kg (4.84 to 11 lb) undergoing onychectomy. PROCEDURE: Researchers were blinded to which cats received a TDF patch (25 microg/h) 18 to 24 hours prior to surgery or an i.m. injection of butorphanol (0.2 mg/kg (0.09 mg/lb]) at the time of sedation, immediately following extubation, and at 4-hour intervals thereafter for 12 hours. Clinical variables, plasma cortisol concentration, and pain scores were evaluated and recorded 24 hours prior to surgery, at extubation, and 2, 4, 8, 12, 24, 36, and 48 hours after surgery. RESULTS: The TDF group had a lower pain score than the butorphanol group only at 8 hours after surgery. Both groups had significantly lower mean plasma cortisol concentrations 0, 24, 36, and 48 hours after surgery, compared with mean plasma cortisol concentrations prior to surgery. No significant differences in appetite or response to handling the feet were observed between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Our data did not reveal a difference in pain relief between administration of TDF and butorphanol. Plasma cortisol concentrations were not different between groups. Fentanyl appeared to provide equivalent analgesia to butorphanol in cats undergoing onychectomy. The primary advantage of using a TDF patch is that repeated injections are not required.

Effect of inhaled endotoxin on cardiopulmonary function and E-selectin expression in pigs.

OBJECTIVE: To evaluate the effect of controlled exposure to inhaled lipopolysaccharides (LPS) on the pulmonary inflammatory response of anesthetized pigs. ANIMALS: Forty-seven 8- to 12-week-old domestic pigs. PROCEDURE: Pigs were anesthetized with pentobarbital, instrumented for measurement of cardiopulmonary function, and randomly assigned to receive saline (0.9% NaCI) solution or 0.25, 0.5, or 1.0 microg of LPS/kg/h for 2 or 6 hours via nebulization through the endotracheal tube. Cardiopulmonary variables were measured, ex vivo neutrophil superoxide production determined, and postmortem assessment for pulmonary neutrophil influx and modulation of adhesion molecule (E-selectin) expression was done. RESULTS: Mild changes in cardiopulmonary function were observed in response to inhaled LPS in the 2-and 6-hour groups. In pigs inhaling LPS (0.5 or 1.0 microg/kg/h) for 6 hours, there was significant pulmonary neutrophil influx observed postmortem. An increase in expression of E-selectin on pulmonary endothelial cells after 6 hours of LPS inhalation (0.5 microg/kg/h) was also observed. In contrast, there was no significant influx of neutrophils or expression of E-selectin in lungs from pigs inhaling LPS for 2 hours. CONCLUSIONS AND CLINICAL RELEVANCE: inhalation of LPS resulted in localized pulmonary inflammation characterized by neutrophil influx and increased expression of the endothelial cell adhesion molecule, E-selectin. It may be possible to relate our experimental findings to the clinical consequences of airborne LPS exposure in swine confinement facilities.

Modulation of endotoxin-induced cardiopulmonary dysfunction by S-nitroso-albumin.

Nitric oxide (NO) is an endogenous vasodilator and modulator of inflammation. During endotoxemia, the beneficial effects of NO are overwhelmed by the inflammatory cascade, resulting in a functional depletion of NO. S-nitroso-albumin (S-NO-alb) exists as a novel and highly stable NO thiol complex that slowly releases NO into the vascular micro-environment. Using a porcine model, we examined the ability of intravenous S-NO-alb to modulate cardiopulmonary dysfunction characteristic of endotoxemia. Pigs were anesthetized, instrumented for standard cardiopulmonary function measurements, and randomly assigned to receive: (i) albumin + saline; (ii) albumin + LPS; or (iii) S-NO-alb + LPS. Cardiopulmonary parameters were evaluated every 30 min and ex vivo phorbol myristate acetate (PMA)-stimulated superoxide release was serially determined as a marker of in vivo neutrophil priming. Lung myeloperoxidase (MPO) activity was measured as a marker of neutrophil migration into the lung. LPS-induced cardiopulmonary dysfunction was characterized by a sustained elevation in mean pulmonary arterial pressure, pulmonary vascular resistance, and peak intratracheal pressure, as well as a reduction in cardiac index, stroke volume index and PaO(2) over 6 h. Pretreatment with S-NO-alb attenuated LPS-induced cardiopulmonary dysfunction without adversely affecting systemic hemodynamics. Moreover, S-NO-alb blunted the LPS-induced hypoxemic response and reduced neutrophil activation. S-NO-alb did not, however, attenuate LPS-induced increases in lung MPO. Our results suggest that S-NO-alb can selectively modulate endotoxin-induced pulmonary dysfunction, attenuate neutrophil priming and block the early mortality (40%) in this model.

Regulation of leukocyte function by nitric oxide donors: the effect of S-nitroso-thiol complexes.

The aim of this study was to evaluate the effectiveness of a novel protein-bound S-nitroso-thiol, S-nitroso-albumin (S-NO-alb), in modulating neutrophil-endothelial cell adhesion, activation, and interactions. Due to the highly variable kinetics of NO release from the low-molecular-weight thiol adducts S-nitroso-N-acetylpenicillamine (SNAP) and S-nitroso-glutathione (GSNO), we expected S-NO-alb to be a more effective modulator of inflammatory interactions through its slow, steady, and prolonged release of NO. Human umbilical-vein endothelial cells (HUVECs) challenged with lipopolysaccharide (LPS) demonstrated upregulated adhesion of neutrophils that was significantly attenuated by pretreatment with S-NO-alb (1.0-100 microM) (p < .05), but not SNAP or GSNO. Pretreatment with S-NO-alb, SNAP, or GSNO attenuated tumor necrosis factor-alpha primed *O2- release from neutrophils and increased neutrophil cGMP accumulation. On a molar basis, S-NO-alb expressed a 10-fold greater potency than SNAP or GSNO at modulating these effects. Kinetics studies confirmed the relative stability of spontaneous NO release from S-NO-alb compared with highly variable kinetic profiles of SNAP and GSNO. Our results demonstrate that S-NO-alb more effectively modulates endothelial-cell and neutrophil immunoinflammatory responses versus its related low-molecular-weight thiol complexes.

A comparison of transdermal fentanyl versus epidural morphine for analgesia in dogs undergoing major orthopedic surgery.

Postoperative analgesia provided by transdermal fentanyl was compared with that provided by epidural morphine in dogs undergoing major orthopedic surgery. Dogs randomly were assigned to receive either a 100 microg per hour transdermal fentanyl patch 24 hours prior to surgery (n=8) or epidural morphine (0.1 mg/kg body weight) administered following induction of anesthesia (n=10). Temperature, heart rate, respiratory rate, and pain score were recorded prior to surgery and zero, six, 18, 30, and 42 hours after surgery. Blood samples were collected from the dogs in the transdermal fentanyl group beginning 24 hours preoperatively to 42 hours postoperatively. Fentanyl concentrations were determined by radioimmunoassay. When all time periods after surgery were combined, dogs in the transdermal fentanyl group were experiencing significantly less pain after surgery than dogs given epidural morphine. The transdermal fentanyl provided analgesia after major orthopedic surgery greater than or equivalent to that of epidural morphine.

Low molecular weight heparin alters porcine neutrophil responses to platelet-activating factor.

Because platelet-activating factor (PAF) is an important mediator of inflammation and heparin has anti-inflammatory effects, we hypothesized that low molecular weight heparin (LMWH) would inhibit PAF-induced activation and chemotaxis in porcine neutrophils. Citrated blood was obtained from pentobarbital-anesthetized pigs, and neutrophils were isolated over a 55%/65% Percoll gradient. The effect of LMWH on basal phorbol myristate acetate (PMA)-induced superoxide (SO) release, as well as its effect on PAF priming for PMA-induced SO release, were investigated. Additionally, the effect of LMWH on PAF-induced chemotaxis of neutrophils across transwell membranes was evaluated. Baseline SO release in response to PMA was .351+/-.046 nmol/10(6) cells/min, and this was decreased to .289+/-.034 nmol/10(6) cells/min by pretreatment with 50 U/mL LMWH. PMA-induced SO production was increased by .240+/-.042 nmol/10(6) cells/min when cells were primed with 10 microM PAF. This priming effect of PAF was reduced significantly by pretreatment of neutrophils with LMWH at 10 and 50 U/mL. Chemotaxis of neutrophils in response to 100 microM PAF was significantly decreased to 70.02+/-6.4% (n = 8) of the control response by pretreatment of cells with 50 U/mL LMWH. We conclude that LMWH has anti-inflammatory effects on porcine neutrophils, which includes attenuation of cell activation and chemotaxis in response to the lipid-derived inflammatory mediator, PAF.

Low molecular weight heparin prevents the pulmonary hemodynamic and pathomorphologic effects of endotoxin in a porcine acute lung injury model.

Tumor necrosis factor alpha (TNF-alpha) activity, platelet and neutrophil degranulation and margination, and increased vascular permeability are central to the pathophysiology of endotoxin-mediated acute lung injury. Nonanticoagulant activities of low molecular weight heparin (LMWH) include solubilization of the TNF-alpha receptor protein, inhibition of neutrophil adhesion, and regulation of thromboxane B2 (TXB2) biosynthesis. In this study, we evaluated the ability of LMWH to modulate TNF-alpha and TXB2 activity during endotoxemia and the subsequent effects on pulmonary hemodynamics. Domestic pigs 8-10 weeks old were anesthetized and catheterized for standard cardiopulmonary measurements and the lungs harvested for cuff:vessel ratio, myeloperoxidase activity, and permeability index. Pigs were randomly assigned to one of four groups: lipopolysaccharide (LPS) (n = 6), given .5 microg/kg/h Escherichia coli LPS intravenously for 6 h; saline control (n = 5); LMWH (n = 5), given .5 mg/kg LMWH for 30 min, followed by .5 mg/kg/h; and LMWH + LPS (same dosages, n = 6). Administration of LPS resulted in increased plasma TNF-alpha and TXB2 activity; increased pulmonary arterial pressure, pulmonary vascular resistance, and alveolar-arterial oxygen tension; decreased systemic arterial oxygen tension; and pulmonary edema. The cardiopulmonary parameters for the LMWH-treated pigs did not differ from those of the saline-treated control pigs. Pretreatment with LMWH attenuated the LPS-mediated TNF-alpha and TXB2 activity and attenuated LPS-mediated pulmonary hypertension, hypoxemia and neutrophil emigration, and edema formation. In conclusion, the data show that the protective effects of LMWH in this model of acute lung injury are associated with altered neutrophil adhesion and TNF-alpha and thromboxane activity.

Role of lipid-derived mediators in tumor necrosis factor-induced endothelin-1 release in vivo.

We hypothesized that endothelin (ET) may be released in response to tumor necrosis factor-alpha (TNF) and that platelet-activating factor (PAF) and cyclooxygenase products modulate TNF-induced ET-1 release in vivo. Anesthetized and instrumented pigs were randomly assigned to receive: 1) saline + TNF (n = 8); 2) saline + heat-inactivated TNF (control group, n = 5); 3) WEB 2086 (PAF receptor antagonist) + TNF (n = 7); or 4) indomethacin + TNF (n = 6). Infusion of TNF was associated with increases in mean aortic, mean pulmonary artery, and intratracheal pressures, increases in systemic and pulmonary vascular resistances, and elevated plasma thromboxane B2 concentration. Plasma ET-1 concentrations were unchanged in controls and significantly increased in TNF-treated pigs at 2 to 4 h. WEB 2086 did not modify plasma levels of ET-1 during exogenous infusion of TNF. In contrast, the cyclooxygenase inhibitor, indomethacin, mildly, but not significantly, reduced plasma ET-1 levels. In addition, indomethacin (but not WEB 2086) blocked or attenuated the TNF-induced increases in mean aortic pressure, systemic vascular resistance, mean pulmonary artery pressure, pulmonary vascular resistance, and intratracheal pressure. We conclude that in the pig, cyclooxygenase products modulate some of the cardiovascular responses to TNF and may mildly affect ET-1 biosynthesis. On the other hand, PAF neither significantly influences TNF-induced biosynthesis of ET-1 nor its associated cardiovascular responses.

Pulmonary and neutrophil responses to priming effects of platelet-activating factor in pigs.

OBJECTIVE: To investigate whether platelet-activating factor (PAF) primes the porcine pulmonary response to lipopolysaccharide (LPS), and what effect PAF priming has on porcine neutrophil superoxide (SO) release. ANIMALS: 8- to 10-week old pigs. PROCEDURES: After pigs were anesthetized with sodium pentobarbital and instrumented for standard cardiopulmonary hemodynamic measurements, they were randomly assigned to receive PAF (0.1 ng/kg of body weight/min, 0 to 2 hours) plus saline solution (2 to 6 hours), saline solution (0 to 2 hours) plus LPS (0.25 microgram/kg/h, 2 to 6 hours), or PAF plus LPS. Cardiopulmonary variables were measured throughout the study. Neutrophils were isolated from saline- or PAF-treated pigs at 0 (baseline) and 2 hours, and the effect of in vivo PAF exposure on ex vivo phorbol myristate acetate (PMA)-induced SO release was measured. Additionally, neutrophils isolated from immune-naive pigs were primed in vitro for 10 minutes with 10 microM PAF, and PMA-induced SO release was measured. RESULTS: PAF infusion significantly enhanced the increase in mean pulmonary arterial pressure, pulmonary vascular resistance, and hypoxemia associated with LPS administration. The infusion increased ex vivo neutrophil SO release, and in vitro PAF exposure primed neutrophils for enhanced SO release that was inhibited by pretreatment of cells with indomethacin. CONCLUSIONS: PAF primes the porcine pulmonary system for the response to LPS. It primes porcine neutrophils in vivo and in vitro for PMA-induced SO release, and in vitro priming is mediated by cyclooxygenase products of arachidonic acid metabolism. CLINICAL RELEVANCE: PAF may modulate the porcine inflammatory response by acting as a priming agent, making pigs more responsive to the negative effects of bacterial LPS.

Craniad migration of differing doses of new methylene blue injected into the epidural space after death of calves and juvenile pigs.

OBJECTIVE: To determine the relation between epidural injectate volume (ml/kg of body weight) and its craniad migration in calves and pigs. ANIMALS: 23 neonatal calves and 26 feeder pigs. PROCEDURE: Animals were randomly assigned to receive different volumes of new methylene blue (NMB, 1.2 mg/ml in 0.9% saline solution). Injections were made into the sacrococcygeal intervertebral space in calves and the lumbosacral intervertebral space in pigs, immediately after euthanasia. Sagittal sections of the spine were made at necropsy, and craniad migration of NMB was determined and rounded to the nearest intervertebral space. RESULTS: In calves treated with 0.05, 0.1, or 0.15 ml of NMB/kg, mean +/- SEM number of stained spinal segments was 5 +/- 0.3, 8 +/- 0.6, and 8 +/- 0.6, respectively. Craniad migration of NMB was significantly greater for 0.15 and 0.1 ml/kg volumes versus 0.05 ml/kg. In pigs treated with 0.05, 0.1, 0.2, of 0.3 ml of NMB/kg, mean number of stained spinal segments was 8 +/- 1.1, 8 +/- 0.9, 10 +/- 1.2, and 18 +/- 2.0. Craniad dye migration was significantly greater in the 0.3 ml/kg group versus the 3 lower volume groups. Linear regression performed on both sets of data after logarithmic transformation of spaces migrated to correct for non-normality was significant (P < 0.05), and R2 values of 0.49 and 0.55 were obtained for calves and pigs, respectively. CONCLUSIONS: There is a significant correlation between volume (ml/kg) of NMB injected in the epidural space and its craniad migration in calves and pigs. CLINICAL RELEVANCE: Results provide a basis for determination of volume of injectate to be given to reach a minimal desired level and should be a useful baseline for future investigations of epidural drug administration.

Morphometric analysis of oleic acid-induced permeability pulmonary edema: correlation with gravimetric lung water.

The technique used most commonly to quantitate pulmonary edema in in vivo animal models is postmortem gravimetric analysis (wet:dry) ratio. To determine whether lung water can be quantitated morphometrically, as accurately as by the commonly used gravimetric analysis, perivascular edema (cuff) area to vessel area ratio was correlated to wet:dry ratio. Anesthetized pigs were given either oleic acid (20 mg/kg/h, intravenously) or physiologic saline. At 4 h, lungs were excised and cuff:vessel and wet:dry ratio analysis was performed. The intermediate lobe was clamped across its main stem bronchus to maintain peak inspiratory inflation, excised, frozen in liquid nitrogen, and stored at -70 degrees C until cryostat sectioning and quantification of perivascular interstitial edema (cuff) area. Gravimetric analysis (wet:dry ratio) was performed on the remaining lung. Mean cuff:vessel and wet:dry analyzes showed that lung water increased significantly (p < .01) in the oleic-acid treated group (4.9 +/- .22 and 6.78 +/- .47, respectively), compared with the saline group (.03 +/- .02 and 2.55 +/- .27, respectively). The correlation coefficient between mean cuff:vessel and wet:dry ratios was .86 (p = .0016). This study demonstrates that cuff:vessel ratio analysis can be used to identify the distribution of edema fluid versus vessel diameter, and seems to be as effective a technique as gravimetric analysis to quantitate lung water changes in acute lung injury models. Moreover cuff:vessel ratio analysis can differentiate modest changes in pulmonary edema by direct quantitation, an important end-point not provided by wet:dry analysis. Therefore, it may be a more sensitive technique when investigating therapeutic interventions in in vivo models of acute lung injury.

SK&F 86002, a dual cytokine and eicosanoid inhibitor, attenuates endotoxin-induced cardiopulmonary dysfunction in the pig.

Cytokines and eicosanoids are well documented important mediators of endotoxemia. Bicyclic imidazoles are a novel class of nonsteroidal anti-inflammatory compounds that display unique pharmacological profiles by reducing cytokine production and arachidonic acid metabolism. In this study, we evaluated the ability of the bicyclic imidazole, SK&F 86002, to attenuate endotoxin-induced cardiopulmonary dysfunction. Pigs were randomly assigned to one of four groups: LPS (n = 5), given .5 microgram/kg/h 055:B5 Escherichia coli lipopolysaccharide (LPS) intravenously (i.v.) for 6 h; saline (n = 5); SK&F 86002 (n = 3), given 50 mg/kg SK&F 86002 orally 30 min prior to anesthesia; and SK&F 86002 + LPS (n = 5). Administration of LPS resulted in cardiopulmonary dysfunction characterized by decreased stroke volume and arterial oxygen tension, and increased room air alveolar-arterial oxygen gradient, pulmonary arterial pressure, pulmonary vascular resistance, and peak intratracheal pressure. Additionally, LPS administration was associated with leukopenia and increased pulmonary myeloperoxidase activity. Pretreatment with SK&F 86002 attenuated LPS induced hypotension, hypoxemia and bronchoconstriction and blocked the pulmonary hypertension. SK&F 86002 blocked the LPS-induced increase in myeloperoxidase activity, indicating a reduction in pulmonary neutrophil infiltration, but had no effect on systemic leukopenia. Pretreatment with SK&F 86002 significantly attenuated LPS-induced increases in plasma thromboxane B2 and tumor necrosis factor-alpha. We hypothesize that ameliorating effects of SK&F 86002 in this endotoxin model of cardiopulmonary dysfunction are related to inhibition of cytokine and eicosanoid biosynthesis.

Management and emergency intervention during anesthesia.

Proper management and monitoring during anesthesia minimizes the need for emergency intervention. Monitoring of circulation, ventilation, and oxygenation allows for early recognition of problems such as airway obstruction, hypotension, acid-base disturbances, or cardiac arrest, and is discussed. Appropriate therapies are instituted early for best success and are described in this article.

Cephalad distribution of three differing volumes of new methylene blue injected into the epidural space in adult goats.

Epidural anesthesia and analgesia are popular regional anesthetic techniques in many animal species. However, we have not found any reports of studies in animals that have investigated the extent of cephalad migration and level of sensory blockade achieved based only on the volume of drug injected into the epidural space. The purpose of this study was to determine if there is a relationship between the volume (mL/kg) of an injectate injected epidurally and the extent of its cephalad migration within the epidural space. Twelve adult goats were randomly assigned to three treatment groups based on the volume of 0.12% New Methylene Blue (NMB), 0.1, 0.2, or 0.3 mL/kg, injected into the epidural space. The site and speed of injection, animal position, and direction of needle bevel were held constant. All injections were performed at the lumbo-sacral space immediately following euthanasia. At necropsy, the vertebral columns were transected longitudinally. The extent of cephalad migration of dye within the epidural space was easily determined by staining of the dura. Measurements were rounded to the nearest intervertebral space to which the dye had migrated. The individual making assessments was blinded to all treatments. In goats treated with 0.1, 0.2, or 0.3 mL/kg NMB, the number of stained spinal segments was 3.5 +/- 0.6, 6.5 +/- 0.9, and 8.8 +/- 0.6, (mean +/- SEM), respectively. Linear regression performed on the data was significant (P < .05) with R2 = 0.86. There was a strong linear relationship between volume (mL/kg) of epidurally injected NMB and cranial migration, with the larger volumes producing more cephalad spread within the epidural space. These results provide evidence for the volume of epidural injectate needed to produce a desired level of sensory blockade in adult goats.

Attenuation of endotoxin-induced pathophysiology by a new potent PAF receptor antagonist.

The role of platelet-activating factor (PAF) as a mediator of endotoxin-induced pathophysiology has been studied in several animal models with conflicting results. We evaluated the effect of a new, potent, and specific PAF receptor antagonist, ABT-299 (Abbott Laboratories) against endotoxin (lipopolysaccharide; LPS)-induced cardiopulmonary dysfunction in a porcine model. In initial experiments, the potency of ABT-299 was confirmed in vitro by its ability to inhibit PAF-induced porcine platelet aggregation at an IC50 of .047 +/- .01 microM, and in vivo by the ability of low doses (.12 mg/kg + .03 mg/kg/h) to block the cardiopulmonary pathologic response to exogenous PAF infusion. To evaluate the effect of ABT-299 administration during endotoxemia, pigs were randomly assigned to one of three groups: controls (n = 7), LPS (n = 9), or ABT-299 + LPS (n =7). ABT-299 was given at 1.0 mg/kg from -0.5 to 0 h plus .3 mg/kg/h from 0 to 6 h. LPS was given at .5 micrograms/kg/hr from 0 to 6 h. ABT-299 reduced the early LPS-induced fall in cardiac index and stroke volume, pulmonary hypertension and vasoconstriction, bronchoconstriction, and hypoxemia. Administration of LPS resulted in 44% mortality (before 6 h), which was blocked by ABT-299. Results with this antagonist indicate that PAF contributes to endotoxin-induced cardiopulmonary dysfunction in the pig, and is associated with mortality in this model.