Dynamic and Postural Changes in Forelimb Amputee Dogs: A Pilot Study.

The amputation of a limb in quadrupeds can overload the remaining limbs, especially the contralateral one. The compensatory effort is especially high if it is a forelimb. It is, therefore, important to objectively know the changes in weight redistribution that occur in the animal while walking and standing still. With this objective, static (postural) and dynamic kinetic examinations were carried out on five French bulldogs with an amputated forelimb and five intact French bulldogs. For this examination, force and pressure platforms were used. The results were statistically compared using the student t-test. The parameters derived from the ground reaction forces were significantly higher in the amputee group. Surprisingly, postural examination showed that amputated dogs reached the same stability as healthy ones. Tripedal support in dogs does not objectively imply a loss of balance in quantitative terms; although the increase in force used by the remaining limb, as well as its altered cranial disposition during the support phase, may potentially predispose the animal to additional injuries in the future due to an overuse of different musculoskeletal units.

Multiparametric Comparison of Two TTA-Based Surgical Techniques in Dogs with Cranial Cruciate Ligament Tears.

Tearing of the cranial cruciate ligament causes hindlimb lameness in dogs. Different surgical procedures have been proposed to treat this condition. In this study, two different TTA-based techniques and implants were compared. A total of 30 dogs were separated into two groups according to the technique and implant used (Porous TTA® or Model Xgen®). The aim of the study was to assess whether one of these techniques has better functional recovery of the joint, better bone consolidation after the osteotomy procedure and fewer osteoarthritic changes. We compared both groups up to 3 months after surgery. No significant differences were found in any of the assessed parameters. Thus, both procedures were found to be equally effective and safe.

Effects of testosterone and exercise training on bone microstructure of rats.

Background and Aim: Male hypogonadism results from failure to produce physiological levels of testosterone. Testosterone in men is essential in masculine development, sperm production, and adult man's health. Osteoporosis is one of the consequences of hypogonadism. Regular physical exercise and exogenous testosterone administration are frequently used to prevent or treat this condition. This study aimed to understand the effects of lifelong exercise training and testosterone levels (isolated and together) in the main bone structure parameters. Materials and Methods: A total of 24 rats were used and randomly divided into four groups: Control group (CG; n=6), exercised group (EG, n=6), testosterone group (TG, n=6), and testosterone EG (TEG, n=6). A micro-computed tomography equipment was used to evaluate 15 bone parameters. Results: Both factors (exercise training and testosterone) seem to improve the bone resistance and microstructure, although in different bone characteristics. Testosterone influenced trabecular structure parameters, namely, connectivity density, trabecular number, and trabecular space. The exercise promoted alterations in bone structure as well, although, in most cases, in different bone structure parameters as bone mineral density and medullar mineral density. Conclusion: Overall, exercise and testosterone therapy seems to have a synergistic contribution to the general bone structure and resistance. Further studies are warranted, comparing different individual factors, as gender, lifestyle, or testosterone protocols, to constantly improve the medical management of hypogonadism (and osteoporosis).

Development and Evaluation of a Disease Large Animal Model for Preclinical Assessment of Renal Denervation Therapies.

New-generation catheters-based renal denervation (RDN) is under investigation for the treatment of uncontrolled hypertension (HTN). We assessed the feasibility of a large animal model of HTN to accommodate the human RDN devices. Ten minipigs were instrumented to measure blood pressure (BP) in an awake-state. HTN was induced with subcutaneous 11-deoxycorticosterone (DOCA, 100 mg/kg) implants. Five months after, the surviving animals underwent RDN with the Symplicity® system. Norepinephrine (NE) renal gradients were determined before and 1 month after RDN. Renal arteries were processed for histological (hematoxylin-eosin, Movat pentachrome) and immunohistochemical (S100, tyrosine-hydroxylase) analyses. BP significantly rose after DOCA implants. Six animals died prematurely, mainly from infectious causes. The surviving animals showed stable BP levels after 5 months. One month after RDN, nerve damage was showed in three animals, with impedance drop >10%, NE gradient drop and reduction in BP. The fourth animal showed no nerve damage, impedance drop <10%, NE gradient increase and no change in BP. In conclusion, the minipig model of DOCA-induced HTN is feasible, showing durable effects. High mortality should be addressed in next iterations of this model. RDN may partially offset the DOCA-induced HTN. Impedance drop and NE renal gradient could be markers of RDN success.

Salubrinal and robenacoxib treatment after global cerebral ischemia. Exploring the interactions between ER stress and inflammation.

BACKGROUND: Blood reperfusion of the ischemic tissue after stroke promotes increases in the inflammatory response as well as accumulation of unfolded/misfolded proteins in the cell, leading to endoplasmic reticulum (ER) stress. Both Inflammation and ER stress are critical processes in the delayed death of the cells damaged after ischemia. The aim of this study is to check the putative synergic neuroprotective effect by combining anti-inflammatory and anti-ER stress agents after ischemia. METHODS: The study was performed on a two-vessel occlusion global cerebral ischemia model. Animals were treated with salubrinal one hour after ischemia and with robenacoxib at 8 h and 32 h after ischemia. Parameters related to the integrity of the blood-brain barrier (BBB), such as matrix metalloproteinase 9 and different cell adhesion molecules (CAMs), were analyzed by qPCR at 24 h and 48 h after ischemia. Microglia and cell components of the neurovascular unit, including neurons, endothelial cells and astrocytes, were analyzed by immunofluorescence after 48 h and seven days of reperfusion. RESULTS: Pharmacologic control of ER stress by salubrinal treatment after ischemia, revealed a neuroprotective effect over neurons that reduces the transcription of molecules involved in the impairment of the BBB. Robenacoxib treatment stepped neuronal demise forward, revealing a detrimental effect of this anti-inflammatory agent. Combined treatment with robenacoxib and salubrinal after ischemia prevented neuronal loss and changes in components of the neurovascular unit and microglia observed when animals were treated only with robenacoxib. CONCLUSION: Combined treatment with anti-ER stress and anti-inflammatory agents is able to provide enhanced neuroprotective effects reducing glial activation, which opens new avenues in therapies against stroke.

Safety and Efficacy of New Biodegradable Polymer-based Sirolimus-Eluting Stents in a Preclinical Model.

INTRODUCTION AND OBJECTIVES: New drug-eluting stents (DES) designed to overcome the limitations of existing devices should initially be tested in preclinical studies. Our objective was to analyze the safety and efficacy of new biodegradable polymer-based DES compared with bare-metal stents (BMS) and commercially available DES in a model of normal porcine coronary arteries. METHODS: We randomly implanted 101 stents (BMS and biodegradable polymer-based sirolimus-eluting stents: 3 test stent iterations [BD1, BD2, and BD3], Orsiro, Biomime and Biomatrix) in the coronary arteries of 34 domestic pigs. Angiographic and histomorphometric studies were conducted 1 month (n = 83) and 3 months (n = 18) later. RESULTS: The stents were implanted at a stent/artery ratio of 1.31 ± 0.21, with no significant differences between groups. At 1 month, the new test stents (BD1, BD2 and BD3) showed less late loss and angiographic restenosis, as well as lower histologic restenosis and neointimal area (P < .0005), than the BMS. There were no differences in endothelialization, vascular injury, or inflammation between the new test stents and BMS, although the new stents showed higher fibrin deposition (P = .0006). At 3 months, all these differences disappeared, except for a lower neointimal area with the new BD1 stent (P = .027). No differences at any time point were observed between the new test stents and commercially available controls. CONCLUSIONS: In this preclinical model, the new biodegradable polymer-based DES studied showed less restenosis than BMS and no significant differences in safety or efficacy vs commercially available DES.

Magnetic resonance imaging and immunohistochemistry of primary vertebral hemangiosarcoma in a dog and implications for diagnosis and therapy.

A vertebral mass in a dog with an acute onset paraparesis was identified by magnetic resonance imaging. A poorly differentiated hemangiosarcoma was diagnosed by histopathology and immunohistochemistry. Endothelial nitric oxide synthase could be a new differential marker for poorly differentiated hemangiosarcoma in dogs. Immunohistochemical detection of p53 phosphorylated at Serine392, p53, CD117, and CD44 suggest targets for design of therapeutic strategies.

Imagerie par résonance magnétique et immunistochimie d'un hémangiosarcome vertébral primaire chez un chien et répercussions pour le diagnostic et le traitement. Une masse vertébrale chez un chien atteint d'une manière soudaine d'une paraparésie a été identifiée à l'aide d'imagerie par résonance magnétique. Un hémangiosarcome mal différencié a été diagnostiqué par histopathologie et immunohistochimie. La synthase à l'oxyde nitrique endothélial pourrait être un nouveau marqueur différentiel pour l'hémangiosarcome mal différencié chez les chiens. La détection immunohistochimique de p53 phosphorylé à la sérine392, p53, CD117 et CD44 suggère des cibles pour la conception de stratégies thérapeutiques.(Traduit par Isabelle Vallières).

Post-ischemic salubrinal treatment results in a neuroprotective role in global cerebral ischemia.

This study describes the neuroprotective effect of treatment with salubrinal 1 and 24 h following 15 min of ischemia in a two-vessel occlusion model of global cerebral ischemia. The purpose of this study was to determine if salubrinal, an enhancer of the unfolded protein response, reduces the neural damage modulating the inflammatory response. The study was performed in CA1 and CA3 hippocampal areas as well as in the cerebral cortex whose different vulnerability to ischemic damage is widely described. Characterization of proteins was made by western blot, immunofluorescence, and ELISA, whereas mRNA levels were measured by Quantitative PCR. The salubrinal treatment decreased the cell demise in CA1 at 7 days as well as the levels of matrix metalloprotease 9 (MMP-9) in CA1 and cerebral cortex at 48 h and ICAM-1 and VCAM-1 cell adhesion molecules. However, increases in tumor necrosis factor α and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) inflammatory markers were observed at 24 h. Glial fibrillary acidic protein levels were not modified by salubrinal treatment in CA1 and cerebral cortex. We describe a neuroprotective effect of the post-ischemic treatment with salubrinal, measured as a decrease both in CA1 cell demise and in the blood-brain barrier impairment. We hypothesize that the ability of salubrinal to counteract the CA1 cell demise is because of a reduced ability of this structure to elicit unfolded protein response which would account for its greater ischemic vulnerability. Data of both treated and non-treated animals suggest that the neurovascular unit present a structure-dependent response to ischemia and a different course time for CA1/cerebral cortex compared with CA3. Finally, our study reveals a high responsiveness of endothelial cells to salubrinal in contrast to the limited responsiveness of astrocytes. The alleviation of ER stress by enhancing UPR with salubrinal treatment reduces the ischemic damage. This effect varies across the different neurovascular unit cell types. The salubrinal neuroprotective effect on CA1 supports differences in neurovascular unit for different brain regions and involves the inflammatory response and its time course. Thus, UPR modulation could be a therapeutic target in cerebral ischemia.

Safety and Efficacy of New Sirolimus-eluting Stent Models in a Preclinical Study.

INTRODUCTION AND OBJECTIVES: Initial preclinical studies are required during the process of improving polymers, platforms, and drug-eluting systems for new coronary stent designs. Our objective was to analyze the efficacy and safety of new drug-eluting stent models compared with a conventional stent and commercialized drug-eluting stents in an experimental model with healthy porcine coronary arteries. METHODS: Sixty stents (conventional stent, new sirolimus-eluting stents: drug-eluting stents 1, 2 and 3; Cypher(®) and Xience(®)) were randomly placed in the coronary arteries of 20 Large White domestic pigs. Angiographic and histomorphometric studies were done 28 days later. RESULTS: The stents were implanted at a stent/artery ratio of 1.34±0.15, with no significant differences between groups. The new stents showed less late loss and angiographic restenosis than conventional stents (P=.006 and P<.001, respectively). Histologically, restenosis and neointimal area were lower with all the new platforms than with the conventional stents (P<.001 for each variable), and no differences were found vs the drug-eluting stents on the market. Safety data showed that endothelialization was lower with drug-eluting stents than with conventional stents, except for drug-eluting stent 3 (P=.084). Likewise, inflammation was lower with drug-eluting stent 3 than with other stents. CONCLUSIONS: The new drug-eluting stent platforms studied are associated with less restenosis than conventional stents and showed no significant differences in safety or efficacy vs commercialized drug-eluting stents.

Age-dependent modifications in vascular adhesion molecules and apoptosis after 48-h reperfusion in a rat global cerebral ischemia model.

Stroke is one of the leading causes of death and permanent disability in the elderly. However, most of the experimental studies on stroke are based on young animals, and we hypothesised that age can substantially affect the stroke response. The two-vessel occlusion model of global ischemia by occluding the common carotid arteries for 15 min at 40 mmHg of blood pressure was carried out in 3- and 18-month-old male Sprague-Dawley rats. The adhesion molecules E- and P-selectin, cell adhesion molecules (CAMs), both intercellular (ICAM-1) and vascular (VCAM-1), as well as glial fibrillary acidic protein (GFAP), and cleaved caspase-3 were measured at 48 h after ischemia in the cerebral cortex and hippocampus using Western blot, qPCR and immunofluorescence techniques. Diametric expression of GFAP and a different morphological pattern of caspase-3 labelling, although no changes in the cell number, were observed in the neurons of young and old animals. Expression of E-selectin and CAMs was also modified in an age- and ischemia/reperfusion-dependent manner. The hippocampus and cerebral cortex had similar response patterns for most of the markers studied. Our data suggest that old and young animals present different time-courses of neuroinflammation and apoptosis after ischemic damage. On the other hand, these results suggest that neuroinflammation is dependent on age rather than on the different vulnerability described for the hippocampus and cerebral cortex. These differences should be taken into account in searching for therapeutic targets.

Safety and efficacy of different paclitaxel-eluting balloons in a porcine model.

INTRODUCTION AND OBJECTIVES: Paclitaxel-eluting balloons have shown high antiproliferative efficacy in the treatment and prevention of restenosis. Nevertheless, not all available devices are equally effective, which makes it interesting to compare results in a preclinical model. Our objective was to assess the preclinical efficacy and safety of different devices. METHODS: We implanted 51 metallic stents (Architect(®), iVascular) in 17 domestic swine (mean, 25 [3] kg), inserting 1 stent per major coronary artery. Stent postdilatation was performed with different control balloons (n=10) or paclitaxel-eluting balloons: paclitaxel-eluting balloon 1 (iVascular) (n=15); paclitaxel-eluting balloon 2 (iVascular) (n=16) and In.Pact Falcon(®) (Medtronic) (n=10). The restenosis rate (using angiography and histomorphometry) and vascular healing parameters (balloon-related vascular injury score, endothelialization rate, and fibrin and inflammation scores) were analyzed at 28 days. RESULTS: The distinct paclitaxel-eluting balloons showed a similar degree of stenosis at follow-up, which was significantly lower than that in the control group: diameter stenosis was 9% (12%) vs 34% (18%) by angiography (P<.0001) and was 22% (8%) vs 51% (18%) by histomorphometry (P<.0001). Scores for vascular injury (mean, 0.6 [0.5]) and inflammation (mean, 0.8 [0.3]) were uniformly low across all groups. Drug effect markers differed significantly between the paclitaxel-eluting balloons and control groups, with lower endothelialization rates (87% [10%] vs 99% [2%]; P=.0007) and higher fibrin scores (2.1 [0.7] vs 0.4 [0.5]; P<.0001) in the paclitaxel-eluting balloons groups. There were no differences between the different paclitaxel-eluting balloons. CONCLUSIONS: In this preclinical model, the paclitaxel-eluting balloons studied significantly reduced in-stent restenosis compared with the control balloons. Although there were no findings of persistent vascular injury or inflammation, delayed endothelialization and fibrin aggregate suggest a drug deposition response.

Histology and immunochemistry evaluation of autologous translocation of retinal pigment epithelium-choroid graft in porcine eyes.

PURPOSE: To evaluate structure and cellular functionality of retinal pigment epithelium (RPE)-choroid grafts after autologous translocation in porcine eyes. METHODS: Retinal pigment epithelium-choroid grafts were obtained from the nasal midperiphery donor site and translocated to the central area in 12 pigs (12 eyes). Grafts were placed under the central retina through a retinotomy. Ophthalmoscopic and pathological evaluations were performed immediately (n = 1) and at 15 (n = 3) and 30 (n = 3) days after surgery. Untranslocated nasal RPE-choroid grafts were obtained at time of surgery and used as controls. Specimens were evaluated by standard histology and by immunochemical studies of RPE65, CRALBP and GFAP. RESULTS: Five animals were lost to follow-up owing to surgery or anaesthesia complications. Ophthalmoscopic examination revealed that the grafts remained in place at all time-points studied. Fifteen and thirty days postsurgery, some areas of the transplanted RPE maintained a monolayered structure. Retinal pigment epithelium cells were firmly attached to Bruch's membrane and predominantly preserved polarity and pigment distribution. However, RPE65, CRALBP and GFAP patterns of expression and distribution were diminished and modified during follow-up. Ophthalmoscopic retinal detachment and proliferative vitreoretinopathy (PVR), confirmed by microscopic evaluation, complicated all cases at 30 days of follow-up. CONCLUSION: Autologous RPE-choroid grafts survived up to 30 days in porcine eyes. Histological and immunochemical evaluation revealed preserved transplanted RPE cells morphology accompanied by alterations in the immunoreactivity expression of functional proteins, and development of significant PVR. The data presented in this manuscript provide insights into the fate, viability and cellular functionality of the transplanted RPE-choroid graft, serving as foundation for further knowledge and improvement of this technique.

Ventricular arrhythmias and mortality associated with isoflurane and sevoflurane in a porcine model of myocardial infarction.

Ischemia of the myocardium can lead to reversible or irreversible injury depending on the severity and duration of the preceding ischemia. Here we compared sevoflurane and isoflurane with particular reference to their hemodynamic effects and ability to modify the effects of acute severe myocardial ischemia and reperfusion on ventricular arrhythmias and mortality in a porcine model of myocardial infarction. Female Large White pigs were premedicated with ketamine, midazolam, and atropine. Propofol was given intravenously for the anesthetic induction, and anesthesia was maintained with isoflurane or sevoflurane. Endovascular, fluoroscopy-guided, coronary procedures were performed to occlude the midleft anterior descending artery by using a coronary angioplasty balloon. After 75 min, the balloon catheter system was withdrawn and the presence of adequate reperfusion flow was verified. The pigs were followed for 2 mo, and overall mortality rate was calculated. The isoflurane group showed lower arterial pressure throughout the procedure, with the difference reaching statistical significance after induction of myocardial ischemia. The ventricular fibrillation rate was higher in isoflurane group (81.3%) than the sevoflurane group (51.7%; relative risk, 1.57 [1.03 to 2.4]). Overall survival was lower in the isoflurane group (75%) than the sevoflurane group (96.4%). In conclusion, in this porcine model of myocardial ischemia and reperfusion, sevoflurane was associated with higher hemodynamic stability and fewer ventricular arrhythmias and mortality than was isoflurane.

Scanning electron microscopy analysis of luminal inflammation induced by different types of coronary stent in an animal model.

There is histological evidence that drug-eluting stents are associated with delayed endothelialization and a persistent inflammatory state. Moreover, clusters of inflammatory cells have been observed on luminal surfaces by scanning electron microscopy. With the aim of quantifying this inflammatory response, we implanted one bare-metal stent and two drug-eluting stents containing different doses of vinblastine embedded in the same polymer into the coronary arteries of 12 domestic pigs. The density of inflammatory cells in a representative area (100 x 100 µm) was quantified at 3 and 7 days. Endothelialization was more complete in bare-metal stents than in drug-eluting stents at both 3 days (P=.016) and 7 days (P=.0001). The degree of inflammation induced by the drug-eluting stents was higher than that induced by the bare-metal stents at both 3 days (11.8±3.5% vs. 4.5±2%; P=.001) and 7 days (26.3±4.4% vs. 1.2±1.5%; P=.0001). In addition, the time sequence was inverted: the inflammatory response increased over time with the drug-eluting stents, while the opposite occurred with the bare-metal stents.

Age and meloxicam attenuate the ischemia/reperfusion-induced down-regulation in the NMDA receptor genes.

This study describes the effect of global brain ischemia followed by 48 h reperfusion, when delayed neuronal death can be already observed. We quantified the mRNA levels of the N-methyl-D-aspartate receptor (NMDAR) subunits and those of the astroglia (glial fibrilar acidic protein, GFAP) and microglia (CD11b) markers using real time PCR on the cerebral cortex and hippocampus of 3- and 18-month-old Sprague-Dawley rats. Data show an ischemia/reperfusion-induced decrease in the mRNA levels of the NMDAR NR1, NR2A and NR2B subunits genes, which contrasts with the increase in the CD11b and GFAP mRNA levels. These effects are attenuated in all the genes studied in 18-month-old animals, suggesting that this mechanism of response is less efficient in aged animals. Western blot assays of NR1, NR2A and NR2B show parallels with the real time PCR data, indicating that the down-regulation of these genes is controlled at the transcriptional level. We suggest that a decrease in the efficiency in the control of the NMDAR transcription could account for the higher vulnerability in aged animals, but it cannot explain by itself differences in the vulnerability to ischemia in different areas of the brain. In the assays of ischemia/reperfusion followed by a treatment with the anti-inflammatory agent meloxicam, we observed that ischemic insult was unable to elicit changes in the NMDAR transcription, thus suggesting that inflammation plays a crucial role in the transcriptional control of these genes.

Global ischemia-induced modifications in the expression of AMPA receptors and inflammation in rat brain.

Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPAR) and inflammatory processes have been related to ischemia-induced damage, but there are few studies addressing their response in different brain areas. Here we compare AMPAR expression after ischemia in several brain areas (hippocampus, cerebral cortex and caudate-putamen) in an attempt to correlate it with their different vulnerabilities. We found outstanding decreases in GluR1 and GluR2 mRNA levels after global ischemia and 48 h reperfusion (I/R) in all the areas studied, however, protein levels maintained in some areas such as CA3, suggesting different post-transcriptional control in different areas of the brain. To characterize the inflammatory response in these areas, we measured the mRNA levels of CD11b/CD18 membrane integrin (a reactive microglia marker), which showed an important but similar up-regulation in all brain areas studied, which was confirmed by immunohistochemistry. We conclude that the down-regulation of AMPAR gene expression following I/R does not explain differences in the vulnerability of different areas. Additionally, our data indicate that the level of inflammation is independent of the vulnerability of the different brain areas and does not explain differences in the AMPAR expression observed in the brain areas studied.

Closed-chest experimental porcine model of acute myocardial infarction-reperfusion.

INTRODUCTION: Progress in cardiovascular regenerative medicine research requires the availability of appropriate experimental animal models that are as close to humans as feasible. Our objective was to assess the validity of a porcine endovascular model of myocardial infarction and reperfusion. METHODS: Fifteen domestic pigs (Large White race) were anesthetized and pre-medicated with amiodarone. Endovascular fluoroscopy-guided coronary procedures were performed to occlude the mid-left anterior descending artery using a coronary angioplasty balloon. Occlusion was confirmed by angiography and electrocardiography. After 75 min the balloon catheter system was withdrawn and the presence of reperfusion flow was verified. The animals were sacrificed after 1 and 2 weeks of follow-up, the hearts were explanted, and the extent of myocardial infarction with respect to the left ventricle was quantified. RESULTS: Overall survival rate was 67%. Five animals died prematurely: 3 showing signs of heart failure, 1 had reperfusion failure (final TIMI flow grade 1) and 1 succumbed to acute stress. The most common adverse event was ventricular fibrillation (87% of the animals) and defibrillation was effective in all affected animals. The extent of myocardial infarct in the animals followed-up for 1 and 2 weeks was similar (20.4+/-4.3% vs. 20.9+/-2.8%, respectively; p=0.8) but was significantly greater in the animals that died prematurely (29.5+/-3.6%, p=0.02). CONCLUSIONS: The endovascular porcine model we have explored constitutes a feasible and reproducible alternative for the evaluation of human myocardial infarction and reperfusion.

Endothelialization of nonapposed stent struts located over the origin of a side branch: results with different carbofilm-coated stents.

OBJECTIVE: To evaluate the degree of endothelialization of the nonapposed struts located at the ostia of side branches. BACKGROUND: Endothelialization of coronary stents has got considerable relevance because of the phenomenon of late thrombosis. Bifurcation location and incomplete stent apposition have been linked to this complication. METHODS: Domestic pigs (n = 11; weight: 25 +/- 3 kg) were anesthetized and had one stent per coronary artery implanted: one stainless steel (Tecnic), one cobalt-chromium (Chrono), and one tacrolimus-eluting stent (Janus), all of them being Carbofilm-coated (Sorin). One, three, or seven days postprocedure, the pigs were sacrificed, the hearts explanted, and longitudinal sections examined by surface electron microscopy to quantify the percentage of the strut endothelialized over the branches and in the total surface. RESULTS: Forty-four side branches (25 stents) that had stent struts over their origin were evaluated. Different patterns of endothelialization were observed, from the total absence to the complete endothelialization. There were no significant differences in relation to type of stent or to the artery treated. The predictors of higher percentage of endothelialization were the ratio of metal to branch diameter (P = 0.04) and better endothelialization in the rest of the stent (P = 0.0002), only this parameter maintaining significant correlation (P = 0.03) in multivariate analysis. CONCLUSIONS: Carbofilm-coated stent struts located over the origin of side branches follow the pattern of endothelialization for the rest of the stent, even in the case of tacrolimus-eluting stent.

Transient global ischemia in rat brain promotes different NMDA receptor regulation depending on the brain structure studied.

The mRNA expression of the major subunits of N-methyl-d-aspartate receptors (NR1, NR2A and NR2B) following ischemia-reperfusion was studied in structures with different vulnerabilities to ischemic insult in the rat brain. The study was performed using quantitative real-time PCR on samples from 3-month-old male Sprague-Dawley rats after global transient forebrain ischemia followed by 48h of reperfusion. Expression of NMDA receptor subunits mRNAs decreased significantly in all structures studied in the injured animals as compared to the sham-operated ones. The hippocampal subfields (CA1, CA3 and dentate gyrus) as well as the caudate-putamen, both reported to be highly ischemic-vulnerable structures, showed outstandingly lower mRNA levels of NMDA receptor subunits than the cerebral cortex, which is considered a more ischemic-resistant structure. The ratios of the mRNA levels of the different subunits were analyzed as a measure of the NMDA receptor expression pattern for each structure studied. Hippocampal areas showed changes in NMDA receptor expression after the insult, with significant decreases in the NR2A with respect to the NR1 and NR2B subunits. Thus, the NR1:NR2A:NR2B (1:1:2) ratios observed in the sham-operated animals became (2:1:4) in insulted animals. This modified expression pattern was similar in CA1, CA3 and the dentate gyrus, in spite of the different vulnerabilities reported for these hippocampal areas. In contrast, no significant differences in the expression pattern were observed in the caudate-putamen or cerebral cortex on comparing the sham-operated animals with the ischemia-reperfused rats. Our results support the notion that the regulation of NMDA receptor gene expression is dependent on the brain structure rather than on the higher or lower vulnerability of the area studied.