Interventionist videothermometry: a new model of cardiac ischemia evaluation.

BACKGROUND: The purpose of the present study was to evaluate, through videothermometry, the temperature variation in the hearts of rabbits, that underwent induced myocardial ischemia and reperfusion. RESULTS: A total of 20 female rabbits were divided into two groups: a treated group and a sham group, the treatment group underwent 5 min of cardiac arrest and reperfusion, using the inflow occlusion technique. Throughout the experiment, the animals were monitored by videothermometry, observing the thermal variations of the myocardial tissue. During the experiment, at different times, blood gas tests and tests to evaluate the lactate concentrations were performed. At the end of the experiment, each heart was submitted to histopathological evaluation. In the treated group, there was a reduction in temperature of the myocardial tissue during the circulatory arrest compared to the sham group. Additionally, a colder area next to the caudal vena cava ostium and the right atrium was observed. Notably, despite the 5 min of cardiac arrest in the treated group, both the lactate and bicarbonate levels were maintained without significant variation. However, there was an increase in PaCO2 and pH reduction, featuring respiratory acidosis. In relation to the histopathological study, the presence of hydropic degeneration in the myocardium of animals in the treated group was observed. CONCLUSIONS: Based on these results, the videothermometry was efficient in identifying the range of myocardial tissue temperature, suggesting that the first areas to suffer due to cardiac arrest were the caudal vena cava ostium and the right atrium. However, in regard to the angiographic coronary thermography, the study was not feasible due to the small size of the coronary. There was no variation between the groups regarding the presence of myocardial infarction, myocardial congestion, myocardial edema and myocardial hemorrhage.

Ability of different assay platforms to measure renal biomarker concentrations during ischaemia-reperfusion acute kidney injury in dogs.

Several protein biomarkers have been shown to be useful for the early diagnosis of acute kidney injury (AKI) in animals and people. Multiplex assays for measurement of a panel of renal biomarkers in canine samples have recently become available. This study compared the use of two such assays, versus previously validated ELISAs, to measure five biomarkers in canine samples during ischaemia-reperfusion (IR) AKI. Blood and urine was collected from six male anaesthetised greyhounds that underwent 1-h of renal ischaemia (severe hypotension induced by acute haemorrhage) and 2-h of reperfusion (intravenous fluid resuscitation). Histology confirmed presence of acute tubular injury at 2 h of reperfusion. Concentrations of clusterin, cystatin C, kidney-injury molecule 1 (KIM-1), monocyte chemoattractant protein 1, and neutrophil gelatinase-associated lipocalin (NGAL) at baseline and following IR, measured by two different multiplex assays and previously-validated single analyte immunoassays, were compared. Only NGAL was significantly elevated following IR with all assays investigated. Whether concentrations of the other four biomarkers were significantly increased following IR depended on the assay used. Concentrations of cystatin C and KIM-1 measured with the multiplex assays were of a vast magnitude lower than those measured with the corresponding single analyte ELISAs. We conclude that further validation is required before these assays can reliably be used to measure AKI biomarkers in canine samples.

Epiphyseal cartilage canal blood supply to the distal femur of foals.

REASONS FOR PERFORMING STUDY: The developmental pattern of the cartilage canal blood supply to epiphyseal growth cartilage has been linked to osteochondrosis (OC) in the tarsus of foals. This pattern has not yet been described in the distal femur, another site frequently affected by OC. OBJECTIVE: To describe the developmental pattern of the blood supply to the distal femoral epiphyseal growth cartilage in 8 Standardbred foals age 0-7 weeks. METHODS: One foal was sacrificed weekly from birth to age 7 weeks (n=8) to undergo a barium perfusion procedure to demonstrate vessels within cartilage canals of one hindlimb. The distal end of the femur was cleared in methyl salicylate and perfused vessels were studied in the intact bones. Each distal femur was then sawed into 5 mm thick slabs in the transverse plane, and the slabs decalcified and radiographed. Finally, the lateral trochlear ridge was separated from each slab and examined histologically. RESULTS: The cartilage canal blood supply regressed with increasing age, but several regions remained vascularised in the oldest foal at age 7 weeks. Vessels arose from perichondrial and subchondral arterial sources, and coursed perpendicular or parallel to the ossification front. The midsection of parallel vessels became incorporated into the ossification front during growth. Anastomoses formed and vessels within the distal portion of canals with an original perichondrial source shifted to use subchondral vessels as their arterial source. Both parallel and perpendicular vessels therefore traversed the ossification front to enter cartilage canals. No histological lesions were observed in sections from any of the foals. CONCLUSION: The same anatomical feature (traversing the ossification front to enter cartilage canals) reported to render vessels vulnerable to failure in the tarsus was also present in the distal femur of foals. POTENTIAL RELEVANCE: OC may occur by the same pathogenetic mechanism in the distal femur as in the tarsus of foals.

Epiphyseal cartilage canal blood supply to the tarsus of foals and relationship to osteochondrosis.

REASON FOR PERFORMING STUDY: Pathological changes in the blood supply to growth cartilage have been implicated in the pathogenesis of osteochondrosis (OC) in horses, but have not been reported using vascular perfusion techniques. OBJECTIVE: To describe the developmental pattern of cartilage canal vessels in the distal tibial epiphysis and talar growth cartilage of foals. METHODS: Nine foals bred from parents with OC were sacrificed between the ages of 0 and 7 weeks to undergo a barium perfusion procedure. The distal end of the tibia and the entire talus were cleared in methyl salicylate and perfused vessels studied in the intact bones. Slabs with a thickness of 4-5 mm from 3 predilection sites for OC were examined in the stereomicroscope and with light microscopy. RESULTS: Cartilage canals were present for a limited period of growth. Perfused vessels initially entered canals from the perichondrium. Vessels in the proximal portion of canals retained their perichondrial arterial source throughout. With time, the ossification front advanced to incorporate the mid-portion of canals; and anastomoses formed between canal vessels and subchondral vessels. A shift occurred and vessels in the distal terminus of canals came to use subchondral vessels as their arterial source. Twelve histological lesions were found in 7 foals. All contained necrotic vessels surrounded by necrotic growth cartilage and 3 caused macroscopically visible delay in endochondral ossification. Lesions were located where vessels traversed the ossification front to enter the distal terminus of canals. CONCLUSION: Cartilage canal vessels are particularly susceptible to failure at the point where they cross the ossification front, with consequences for the viability of those chondrocytes that depend on them. POTENTIAL RELEVANCE: A better understanding of how lesions of OC arise may improve the ability to identify, monitor, prevent and treat this disorder. Involvement of cartilage canals in the pathogenesis of equine tarsal OC plausibly explains several clinical features of this disease.

Attenuation of ischaemic injury in the equine jejunum by administration of systemic lidocaine.

REASONS FOR PERFORMING STUDY: Absorption of endotoxin across ischaemic-injured mucosa is a major cause of mortality after colic surgery. Recent studies have shown that flunixin meglumine retards mucosal repair. Systemic lidocaine has been used to treat post operative ileus, but it also has novel anti-inflammatory effects that could improve mucosal recovery after ischaemic injury. HYPOTHESIS: Systemic lidocaine ameliorates the deleterious negative effects of flunixin meglumine on recovery of mucosal barrier function. METHODS: Horses were treated i.v. immediately before anaesthesia with either 0.9% saline 1 ml/50 kg bwt, flunixin meglumine 1 mg/kg bwt every 12 h or lidocaine 1.3 mg/kg bwt loading dose followed by 0.05 mg/kg bwt/min constant rate infusion, or both flunixin meglumine and lidocaine, with 6 horses allocated randomly to each group. Two sections of jejunum were subjected to 2 h of ischaemia by temporary occlusion of the local blood supply, via a midline celiotomy. Horses were monitored with a behavioural pain score and were subjected to euthanasia 18 h after reversal of ischaemia. Ischaemic-injured and control jejunum was mounted in Ussing chambers for measurement of transepithelial electrical resistance (TER) and permeability to lipopolysaccharide (LPS). RESULTS: In ischaemic-injured jejunum TER was significantly higher in horses treated with saline, lidocaine or lidocaine and flunixin meglumine combined, compared to horses treated with flunixin meglumine. In ischaemic-injured jejunum LPS permeability was significantly increased in horses treated with flunixin meglumine alone. Behavioural pain scores did not increase significantly after surgery in horses treated with flunixin meglumine. CONCLUSIONS: Treatment with systemic lidocaine ameliorated the inhibitory effects of flunixin meglumine on recovery of the mucosal barrier from ischaemic injury, when the 2 treatments were combined. The mechanism of lidocaine in improving mucosal repair has not yet been elucidated.

Pin1 aggravates renal injury induced by ischemia and reperfusion in rats via Nrf2/HO-1 mediated endoplasmic reticulum stress

Purpose: To investigate the role of peptidyl-prolyl cis/trans isomerase 1 (Pin1) on renal ischemia-reperfusion (I/R) injury and underlying mechanism. Methods: By establishing the in vitro and in vivo models of renal I/R, the role of Pin1 was explored by using molecular assays. Results: In renal I/R, endogenous Pin1 level was up-regulated in I/R-impaired kidney. Suppression of Pin1 with juglone afforded protection against I/R-mediated kidney dysfunction, and reduced I/R-induced endoplasmic reticulum (ER) stress in vivo. Consistent with the in vivo results, repression of Pin1 with juglone or gene knockdown with si-Pin1 conferred cytoprotection and restricted hypoxia/reoxygenation (H/R)-driven ER stress in HK-2 cells. Simultaneously, further study uncovered that Nrf-2/HO-1 signals was the association between Pin1 and ER stress in response to renal I/R. In addition, Nrf-2/HO-1 signal pathway was inactivated after kidney exposed to I/R, as indicated by the down-regulation of Nrf-2/HO-1 levels. Furthermore, inhibition of Pin1 remarkably rescued the inactivation ofNrf-2/HO-1. Conclusions: Pin1 modulated I/R-mediated kidney injury in ER stress manner dependent on Nrf2-HO-1 pathway in I/R injury.

Effect of defocused CO2 laser on equine tissue perfusion.

Treatment with defocused CO2 laser can have a therapeutic effect on equine injuries, but the mechanisms involved are unclear. A recent study has shown that laser causes an increase in equine superficial tissue temperature, which may result in an increase in blood perfusion and a stimulating effect on tissue regeneration. However, no studies have described the effects on equine tissue perfusion. The aim of the present study was to investigate the effect of defocused CO2 laser on blood perfusion and to correlate it with temperature in skin and underlying muscle in anaesthetized horses. Differences between clipped and unclipped haircoat were also assessed. Eight horses and two controls received CO2 laser treatment (91 J/cm2) in a randomised order, on a clipped and unclipped area of the hamstring muscles, respectively. The significant increase in clipped skin perfusion and temperature was on average 146.3 +/- 33.4 perfusion units (334%) and 5.5 +/- 1.5 degrees C, respectively. The significant increase in perfusion and temperature in unclipped skin were 80.6 +/- 20.4 perfusion units (264%) and 4.8 +/- 1.4 degrees C. No significant changes were seen in muscle perfusion or temperature. In conclusion, treatment with defocused CO2 laser causes a significant increase in skin perfusion, which is correlated to an increase in skin temperature.

Effects of cyclooxygenase inhibitors flunixin and deracoxib on permeability of ischaemic-injured equine jejunum.

REASONS FOR PERFORMING STUDY: Recent studies have shown that flunixin prevented recovery of equine jejunum post ischaemia. However, the use of a purported cyclooxygenase (COX)-2 preferential inhibitor, etodolac, also prevented recovery. These findings may have implications for the use of nonsteroidal anti-inflammatory drugs in colic patients. OBJECTIVE: To compare the effects of deracoxib, a highly selective canine COX-2 inhibitor, with flunixin on in vitro recovery of ischaemic-injured equine jejunum. METHODS: Six horses underwent 2 h jejunal ischaemia, after which mucosa was mounted in Ussing chambers and recovered for 240 mins. Transepithelial electrical resistance (TER) and mucosal-to-serosal fluxes of 3H-mannitol were monitored as indices of barrier function in the presence of flunixin or deracoxib. RESULTS: The TER of ischaemic-injured tissue recovered significantly over 240 mins in the presence of no treatment, but not in the presence of flunixin or deracoxib. In addition, flunixin-treated ischaemic jejunum was significantly more permeable to mannitol when compared with untreated tissue by the end of the recovery period, whereas deracoxib treatment did not increase permeability. Addition of the PGE1 analogue misoprostol to flunixin-treated tissue restored recovery of TER. CONCLUSIONS AND POTENTIAL RELEVANCE: Treatment of horses with ischaemic jejunal disease with flunixin may result in a prolonged permeability defect in recovering mucosa. Addition of misoprostol or replacement of flunixin with deracoxib may ameliorate effects of COX inhibitors on recovering mucosa.

Brief topical and intraluminal use of Carolina rinse solution does not attenuate experimental ischemia and reperfusion injury in rabbit jejunum / [O uso tópico breve e intraluminal da solução de Carolina rinse não atenua a injúria de isquemia e reperfusão experimental no jejuno de coelhos ]

Fifteen New Zealand adult rabbits were randomly allocated into three groups: Sham-operated (group A), Ischemia and Reperfusion (group B) and Carolina Rinse Solution (CRS) (group C). Groups B and C were subjected to one hour of ischemia and two hours of reperfusion. In group C, ten minutes before reperfusion, the bowel lumen was filled with CRS, and the segment immersed in CRS. Necrosis and loss of integrity of the villi were visible in groups B and C. Edema of the submucosa and circular muscle was observed in all groups. Hemorrhage was observed in different layers for groups B and C, but group C showed more severe hemorrhage in different layers during reperfusion. All groups showed polymorphonuclear leukocyte infiltration on the base of the mucosa, submucosa, and longitudinal muscle, in addition to polymorphonuclear leukocytes margination in the mucosal and submucosal vessels. Necrosis of enterocytes, muscles, crypts of Lieberkühn and myenteric plexus was observed in groups B and C during reperfusion. Topical and intraluminal Carolina Rinse Solution did not attenuate the effects of ischemia and reperfusion in the small intestine of rabbits.(AU)

Quinze coelhos da raça Nova Zelândia foram alocados em três grupos: instrumentado (grupo A), isquemia e reperfusão (grupo B) e solução de Carolina rinse (CRS) (grupo C). Os grupos B e C foram submetidos a uma hora de isquemia e a duas horas de reperfusão. No grupo C, 10 minutos antes da reperfusão, o segmento isolado foi imerso e teve seu lúmen preenchido com CRS. Os grupos B e C apresentaram necrose e perda progressiva da integridade das vilosidades. Foi observado edema na submucosa e na camada muscular circular em todos os grupos. Nos grupos B e C, foi observada hemorragia em diferentes camadas, mas, no grupo C, a hemorragia foi mais intensa durante a reperfusão. Todos os grupos apresentaram infiltrado de PMN na base da mucosa, na submucosa e na camada muscular longitudinal e marginação de PMN nos vasos da mucosa e da submucosa. Durante a reperfusão, foi observada necrose dos enterócitos, das camadas musculares, das criptas de Lieberkühn e do plexo mioentérico nos grupos B e C. O uso tópico e intraluminal de CRS não atenuou os efeitos da isquemia e da reperfusão no intestino delgado de coelhos.(AU)

Treatment of ischaemic jejunum with topical and intraluminal Carolina Rinse.

Carolina Rinse Solution (CRS) was applied topically and intraluminally to ischaemic (Group 1; n = 5) and distended equine jejunum (Group 2; n = 5). Mesenteric blood flow, ORC (osmotic reflection coefficient), wet weight to dry weight ratios (WW/DW), serosal thickness, and neutrophil accumulation in the serosa were measured. After 60 min ischaemia followed by reperfusion (Group 1), mesenteric blood flow remained greater than baseline values. The mean ORC was similar to that previously reported in normal bowel or ischaemic intestine treated with CRS by arterial perfusion. The ORC after distention and decompression (Group 2) increased and was similar to that previously reported in a comparable untreated experimental model. The WW/DW after both ischaemia and distention increased compared to specimens collected from noninstrumented jejunum proximal to the experimental segments in the same horses. There was no difference in neutrophil numbers in the serosa of either ischaemic or distended intestine compared to the noninstrumented proximal jejunum. CRS-treated ischaemic intestine maintained microvascular permeability similar to that reported for normal intestine whereas treated distended intestine did not. Combined topical and intraluminal application of CRS to ischaemic intestine may reduce complications due to acute inflammation during reperfusion.

Microvascular circulation of the ascending colon in horses.

Microvascular circulation of the ascending colon in healthy horses was studied using microangiography, light microscopy, and scanning electron microscopy. The pelvic flexure with 30 cm of ventral and dorsal colon attached was removed from 14 adult horses immediately after horses were euthanatized. The lumen was flushed with warm water, and this section of the ascending colon was placed in a 37-C bath of isotonic NaCl. In sections from 8 horses, colic vessels were perfused with a radio-opaque medium for microangiography. After angiographic evaluation, tissue sections were prepared for light microscopic observation, using standard histologic methods. In sections from 6 horses, injection replicas were made by perfusing the vessels with 2 types of plastics. The results of microangiography, light microscopy, and scanning electron microscopy of vascular replicas were correlated, providing a comprehensive documentation of the microvasculature of the ascending colon at the pelvic flexure. Arteries branched from mesenteric colic vessels approximately every 2 cm toward the colonic tissue. Immediately after branching, arterial vessels formed an anastomotic plexus, the colonic rete. However, each branch from the colic vessel eventually continued into the colonic tissue. A second set of vessels originated from the colonic tissue. A second set of vessels originated from the colonic rete and supplied the mesenteric lymph nodes. Arterial vessels penetrated the tunica muscularis into the submucosa 3 to 4 cm toward the antimesenteric border forming a submucosal vascular network. From the submucosal arterioles, branching took place at right angles to supply the mucosal capillaries. Capillaries surrounded the colonic glands and anastomosed at the luminal surface, forming a superficial luminal honeycomb-appearing vascular plexus.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphologic and ultrastructural evaluation of effect of ischemia and dimethyl sulfoxide on equine jejunum.

Morphologic changes in equine jejunal segments subjected to 1 hour of ischemia and 1 hour of reperfusion, and protective effects of systemic administration of dimethyl sulfoxide (DMSO; 1 g/kg of body weight) were investigated in 18 ponies, using light microscopy and scanning and transmission electron microscopy. Ponies were allotted to 4 groups: group 1--control (n = 3); group 2--DMSO (n = 3); group 3--ischemia (n = 6); and group 4--ischemia and DMSO (n = 6). In each pony, 2 jejunal sections were evaluated. The first section was obtained prior to induction of ischemia, and the second was obtained 2 hours later after reperfusion. Mucosal lesions were graded from 0 (normal) to 5 (most severe). Combined ischemia and reperfusion of 2 hours' duration induced moderately severe mucosal injury to the equine jejunum (group 3; grade 1.5 to 2.5), characterized principally by disruption of enterocyte attachment from the basement membrane and lamina propria. Fluid accumulation disrupted enterocyte cell-to-cell adhesion toward cell bases, while apical tight junctions and desmosomal junctions toward the luminal surface remained intact. Intracytoplasmic organellar changes within enterocytes were not a prominent feature of the injury. The aforementioned processes were marked at the villus tip and progressed down the villus sides. These findings support the importance of mechanisms leading to early subepithelial fluid accumulation rather than that of direct severe enterocyte injury. Further, fluid accumulation does not appear to arise from intercellular migration from the luminal surface. In this model, a pathomechanical effect caused by vigorous villus retraction appears to exacerbate epithelial lifting toward the villus tip.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and colonic venous hemostatic alterations in horses during low-flow ischemia and reperfusion of the large colon.

Twenty-four horses were randomly allocated to 3 groups. All horses underwent a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls, group-2 horses underwent 6 hours of colonic ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline blood samples were collected, then low-flow colonic ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. All horses were monitored for 6 hours. Citrated systemic venous (SV) blood samples were collected from the main pulmonary artery, and colonic venous (CV) samples were collected from the colonic vein draining the ventral colon. Samples were collected at 0, and 2, 3, 3.25, 4, and 6 hours for determination of one-stage prothrombin time, activated partial thromboplastin time, antithrombin III activity, and fibrinogen concentration. Data were analyzed statistically, using two-way ANOVA for repeated measures, and post-hoc comparisons were made by use of Student Newman Keul's test. Statistical significance was set at P < 0.05. There were significant decreases in all hemostatic variables by 2 hours in SV and CV samples from horses of all 3 groups, but there were no differences among the 3 groups for any of these variables. These hemostatic alterations could have been secondary to a hypercoagulable state or to fluid therapy-induced hemodilution. Colonic ischemia-reperfusion was not the cause of these alterations because these alterations also were observed in the sham-operated control horses. Significant temporal alterations existed even after accounting for the hemodilution.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and colonic venous plasma eicosanoid and endotoxin concentrations, and colonic venous serum tumor necrosis factor and interleukin-6 activities in horses during low-flow ischemia and reperfusion of the large colon.

Twenty-four horses were randomly allocated to 3 groups. Horses were anesthetized, subjected to a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls. Group-2 horses were subjected to 6 hours of low-flow colonic arterial ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline (BL) samples were collected, then low-flow ischemia was induced by reducing ventral colonic arterial blood flow to 20% of BL. All horses were monitored for 6 hours after BL data were collected. Blood samples were collected from the colonic vein and main pulmonary artery (systemic venous [SV]) for measurement of plasma endotoxin, 6-keto prostaglandin F1 alpha (6-kPG), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2) concentrations. Tumor necrosis factor and interleukin-6 activities were measured in colonic venous (CV) serum samples. Data were analyzed, using two-way ANOVA, and post-hoc comparisons were made, using Dunnett's and Tukey's tests. Statistical significance was set at P < 0.05. Endotoxin was not detected in CV or SV plasma at any time. There was no detectable tumor necrosis factor or interleukin-6 activity in CV samples at any time. There were no differences at BL among groups for CV or SV 6-kPG, PGE2, or TXB2 concentrations, nor were there any changes across time in group-1 horses.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the microcirculation of the equine jejunum and ascending colon after ischemia and reperfusion.

Intramural vascular patterns of the jejunum and colon were evaluated during ischemic strangulation obstruction (ISO, 70 minutes) and subsequent reperfusion (60 minutes) in 7 adult anesthetized horses. Microvasculature of experimental and control segments was described by comparison of results from microangiography, light microscopy, and scanning electron microscopy of vascular replicas. Experimental and control segments with isolated vascular arcades were removed either immediately after the experimental period or after 60 minutes of reperfusion. Blood was flushed from the vascular system by use of isotonic NaCl, and the segments were divided. Half of each segment was perfused with a modified radiopaque medium for microangiographic evaluation, and half was perfused with dilute methyl-methacrylate to create a vascular replica to be studied by scanning electron microscopy. Microangiographic section also were evaluated for histologic changes. Microvasculature of jejunal control segments and all colon segments was similar to described normal microvasculature of the equine jejunum and ascending colon. In jejunal ISO segments, intramural perfusion was redistributed away from the mucosa. In the villi, the central arteriole was short and convoluted and the subepithelial capillaries were not filled. The submucosal vessels and crypt capillaries were congested, compared with those of controls, and the serosal vessels were not filled in the ischemic segments. Histologic grade II-III mucosal lesion was seen in jejunal ISO segments. Reperfused jejunal segments had a transmural hyperemic response, and previously unfilled capillaries were observed in all intestinal layers. After reperfusion, the mucosal lesion progressed to grade III-IV and a cellular infiltrate and edema formation were observed in the serosa. The intramural vasculature of the ischemic and reperfused colon remain unchanged. Minimal histologic damage was observed in the colon after 70 minutes of ISO or after 60 minutes of reperfusion.

Effects of flunixin meglumine or etodolac treatment on mucosal recovery of equine jejunum after ischemia.

OBJECTIVE: To examine the effects of flunixin meglumine and etodolac treatment on recovery of ischemic-injured equine jejunal mucosa after 18 hours of reperfusion. ANIMALS: 24 horses. PROCEDURE: Jejunum was exposed to 2 hours of ischemia during anesthesia. Horses received saline (0.9% NaCl) solution (12 mL, i.v., q 12 h), flunixin meglumine (1.1 mg/kg, i.v., q 12 h), or etodolac (23 mg/kg, i.v., q 12 h). Tissue specimens were obtained from ischemic-injured and nonischemic jejunum immediately after ischemia and 18 hours after recovery from ischemia. Transepithelial electric resistance (TER) and transepithelial flux of tritium-labeled mannitol measured mucosal permeability. Denuded villous surface area and mean epithelial neutrophil count per mm2 were calculated. Western blot analysis for cyclooxygenase (COX)-1 and -2 was performed. Pharmacokinetics of flunixin and etodolac and eicosanoid concentrations were determined. RESULTS: Ischemic-injured tissue from horses treated with flunixin and etodolac had significantly lower TER and increased permeability to mannitol, compared with that from horses treated with saline solution. Epithelial denudation after ischemia and 18 hours after recovery was not significantly different among treatments. Both COX-1 and -2 were expressed in ischemic-injured and nonischemic tissues. Ischemia caused significant upregulation of both COX isoforms. Eicosanoid concentrations were significantly lower in tissues from flunixin and etodolac-treated horses, compared with that from horses treated with saline solution. CONCLUSIONS AND CLINICAL RELEVANCE: Flunixin and etodolac treatment retarded recovery of intestinal barrier function in jejunal mucosa after 18 hours of reperfusion, whereas tissues from horses treated with saline solution recovered baseline values of TER and permeability to mannitol.

A new porcine model of reperfusion injury after lung transplantation.

Rodent models have been described to investigate lung preservation and reperfusion injury but have significant disadvantages. In large animals single lung transplant studies are probably optimal but problems remain over the ability to rigorously separate the lungs for assessment while promoting medium to long-term animal survival for meaningful investigation. Our aim was to develop a novel and refined large animal model to assess reperfusion injury in the transplanted lung, overcoming the difficulties associated with existing models. Specifically, small animal models of lung transplantation usually have short perfusion times (often one hour) and include extracorporeal circuits while larger animal models often require the contralateral lung to be excluded after transplantation-an unphysiological situation under which to evaluate the graft. A porcine model of left lung allotransplantation was developed in which native and donor lungs are individually ventilated. Sampling catheters placed within the graft lung allowed specimen withdrawal without mixing of blood from the contralateral lung after reimplantation. The model permits a variety of clinical scenarios to be simulated with the native lung supporting the animal irrespective of function in the graft. This model has been used in over 60 transplant procedures with a postoperative survival time of 12 h being readily achieved. The mean operating time was 2.6 h. The mortality rate is 4% in our series. We have found the model to be reliable, reproducible and flexible. We propose this model as an adaptable investigation for evaluating lung reperfusion injury and preservation.

The assessment of brain injury with measurement of calcium fluorescent intensity of a vital brain slice.

Retrograde cerebral perfusion (RCP) is one of cerebral protection methods during deep hypothermic circulatory arrest (DHCA). However, the mechanism is unclear. In this study with laser confocal scanning microscope (LCSM), calcium fluorescent intensity of vital brain slice was compared between RCP and DHCA group. Sixteen swine, weighing from 19 to approximately 20 kg and supplied by Beijing College of Agriculture, were used for the experiment. After 90 min of DHCA or RCP through the superior vena cava, the animals were rewarmed for 120 min. Through tentorium of the cerebellum and enucleation of the eyeball, vital brain slices (cerebellula and retina) were obtained and fluorescein labeled in artificial cerebrospinal fluid containing 5 micromol/L Fluo-3/AM (fluoresence probe). The calcium fluorescent intensity was examined by LCSM. The results indicated that calcium fluorescent intensity of vital brain slice was lower in the RCP group (cerebellula, 9.16 +/- 3.98; retina, 21.48 +/- 14.27) than that in the DHCA group (cerebellula, 31.97 +/- 20.59; retina, 44.07 +/- 21.01) (p < .05). More moderate and severe eosinophilic degeneration was found in the DHCA group than in the RCP group (p < .05) through morphological examination. The statistical analysis also indicated the calcium fluorescent intensity of the vital brain slice was correlated with the level of moderate and severe eosinophilic degeneration of thee neuron (r = 0.86, p < .05). So "calcium overload" contributes to the injury of neuron after DHCA. RCP is able to attenuate "calcium overload," which has the effect of cerebral protection.