The influence of intracranial hypertension on static cerebral autoregulation.

OBJECTIVES: To analyze the influences of mild and severe intracranial hypertension on cerebral autoregulation (CA). PATIENTS AND METHODS: Duroc piglets were monitored with an intracranial pressure (ICP) catheter. Intracranial hypertension was induced via infusion of 4 or 7 ml of saline solution by a bladder catheter that was inserted into the parietal lobe. The static cerebral autoregulation (sCA) index was evaluated via cerebral blood flow velocities (CBFv). Piglets with ICPs ≤ 25 and > 25 mmHg were considered as group 1 and 2, respectively. Continuous variables were evaluated using the Kolmogorov-Smirnov goodness-of-fit test. The main parameters were collected before and after ICH induction and compared using two-factor mixed-design ANOVAs with the factor of experimental group (mild and severe ICH). RESULTS: In group 1 (ICP ≤ 25 mmHg), there were significant differences in sCA (p = .01) and ICP (p = .0002) between the basal and balloon inflation conditions. In group 2 (ICP > 25 mmHg), there were significant differences in CBFv (p = .0072), the sCA index (p = .0001) and ICP (p = .00001) between the basal and balloon inflation conditions. CONCLUSION: We conclude that intracranial hypertension may have a direct effect on sCA.

Large-for-size liver transplantation: a flowmetry study in pigs.

BACKGROUND: Ischemia-reperfusion injury is partly responsible for morbidity in pediatric liver transplantation. Large-for-size (LFS) liver transplantation has not been fully studied in the pediatric population, and the effects of reperfusion injury may be underestimated. MATERIALS AND METHODS: Thirteen Landrace-Large white pigs weighing 23 kg (range, 17-38 kg) underwent orthotopic liver transplantation. They were divided into two groups according to the size of the donor body: LFS and control (CTRL). After transplantation, the abdominal cavity of the recipient was kept open and portal venous flow (PVF) was measured after 1 h. The ratio of recipient PVF (PVFr) to donor PVF was used to establish correlations with ischemia and reperfusion parameters. Liver biopsies were taken 1 h after transplantation to assess ischemia and reperfusion and to quantify the gene expression of endothelial nitric oxide synthase, interleukin 6, BAX, and BCL. RESULTS: Recipient weight, total ischemia time, and warm ischemia time were similar between groups. Among hemodynamic and metabolic analyses, pH, central arteriovenous PCO2 difference, and AST were statistically worse in the LFS group than in the CTRL group. The same was found with endothelial nitric oxide synthase (0.41 ± 0.18 versus 1.56 ± 0.78; P = 0.02) and interleukin 6 (4.66 ± 4.61 versus 16.21 ± 8.25; P = 0.02). In the LFS group, a significant decay in the PVFr was observed in comparison with the CTRL group (0.93 ± 0.08 and 0.52 ± 0.11, respectively; P < 0.001). CONCLUSIONS: The implantation of a graft was responsible for poor hemodynamic status of the recipient 1 h after transplantation. Furthermore, the LFS group demonstrated markers of ischemia and reperfusion that were worse when compared with the CTRL group and exhibited a more significant decrease in PVF from donor to recipient.

Post-COVID-19 condition: systemic inflammation and low functional exercise capacity.

Introduction: Post-COVID-19 condition (PCC) is characterised by a plethora of symptoms, with fatigue appearing as the most frequently reported. The alterations that drive both the persistent and post-acute disease newly acquired symptoms are not yet fully described. Given the lack of robust knowledge regarding the mechanisms of PCC we have examined the impact of inflammation in PCC, by evaluating serum cytokine profile and its potential involvement in inducing the different symptoms reported. Methods: In this cross-sectional study, we recruited 227 participants who were hospitalised with acute COVID-19 in 2020 and came back for a follow-up assessment 6-12 months after hospital discharge. The participants were enrolled in two symptomatic groups: Self-Reported Symptoms group (SR, n = 96), who did not present major organ lesions, yet reported several debilitating symptoms such as fatigue, muscle weakness, and persistent loss of sense of smell and taste; and the Self-Reported Symptoms and decreased Pulmonary Function group (SRPF, n = 54), composed by individuals with the same symptoms described by SR, plus diagnosed pulmonary lesions. A Control group (n = 77), with participants with minor complaints following acute COVID-19, was also included in the study. Serum cytokine levels, symptom questionnaires, physical performance tests and general clinical data were obtained in the follow-up assessment. Results: SRPF presented lower IL-4 concentration compared with Control (q = 0.0018) and with SR (q = 0.030), and lower IFN-α2 serum content compared with Control (q = 0.007). In addition, SRPF presented higher MIP-1ß serum concentration compared with SR (q = 0.029). SR presented lower CCL11 (q = 0.012 and q = 0.001, respectively) and MCP-1 levels (q = 0.052 for both) compared with Control and SRPF. SRPF presented lower G-CSF compared to Control (q = 0.014). Female participants in SR showed lower handgrip strength in relation to SRPF (q = 0.0082). Male participants in SR and SRPF needed more time to complete the timed up-and-go test, as compared with men in the Control group (q = 0.0302 and q = 0.0078, respectively). Our results indicate that different PCC symptom profiles are accompanied by distinct inflammatory markers in the circulation. Of particular concern are the lower muscle function findings, with likely long-lasting consequences for health and quality of life, found for both PCC phenotypes.

Acute and chronic changes in porcine rete mirabile after embolization with the Menox system: angiographic and histopathological analyses.

Objective: To evaluate acute and chronic changes seen on angiographic and histopathological studies of porcine rete mirabile, comparing those treated with the Menox liquid embolic system (LES) and those treated with the Onyx LES. Materials and Methods: Five pigs, each weighing approximately 35 kg, were submitted to rete mirabile embolization under general anesthesia and fluoroscopic guidance, with the Menox LES or Onyx LES. Four animals were treated with the Menox LES and underwent cerebral angiography, followed by euthanasia, at 1, 30, 60, and 90 days after embolization. One animal was treated with the Onyx LES underwent the same procedures at 30 days after embolization. In a subsequent histopathological analysis, we compared the Menox LES and Onyx LES in terms of the acute and chronic changes observed. Results: We observed no significant changes in blood pressure, heart rate, or electrocardiographic parameters that could be attributed to the super-selective infusion of dimethyl sulfoxide or the Menox embolic agent. Fluoroscopy showed adequate material opacity, appropriate progression to the center of the rete mirabile and complete unilateral embolization. Microcatheters were uneventfully detached from the embolized nidus. We observed mild to moderate intravascular and extravascular inflammatory responses, without histological evidence of necrotizing arteritis. There were no adverse neurovascular events. Conclusion: The Menox LES appears to be safe and effective, as well as being apparently equivalent to the Onyx LES in terms of the postprocedure angiographic and histopathological findings.

Objetivo: Avaliar as alterações angiográficas e histopatológicas agudas e crônicas em rete mirabile suína tratadas com o Menox liquid embolic system (LES) e comparar essas alterações com a embolização com Onyx LES. Materiais e Métodos: A embolização da rete mirabile com Menox LES e Onyx LES foi realizada em cinco suínos pesando cerca de 35 kg sob anestesia geral e orientação fluoroscópica. Quatro animais tratados com Menox LES foram submetidos a angiografia cerebral seguida de eutanásia após 1, 30, 60 e 90 dias e um animal tratado com Onix LES foi submetido ao mesmo procedimento após 30 dias. A análise histopatológica subsequente para alterações agudas e crônicas avaliou o desempenho do Menox LES comparado ao Onyx LES. Resultados: Não foram observadas alterações significativas atribuíveis à infusão superseletiva de dimetilsulfóxido ou Menox nos parâmetros de pressão arterial, frequência cardíaca ou eletrocardiograma. A fluoroscopia mostrou opacidade adequada do material, progressão adequada para o centro da rete mirabile e embolização unilateral completa. Os microcateteres foram retirados do nidus embolizado sem complicações. Observou-se resposta inflamatória intravascular e extravascular leve a moderada, sem indício histológico de arterite necrosante. Nenhum dos casos apresentou eventos neurovasculares adversos. Conclusão: A injeção de Menox LES mostrou-se segura e eficaz, além de ser equivalente ao Onyx LES em relação aos achados angiográficos e histopatológicos pós-procedimento.

Assessing ultrasonographic optic nerve sheath diameter in animal model with anesthesia regimens.

PURPOSE: To determine the normal optical nerve sheath (ONS) diameter ultrasonography (ONSUS) and evaluate the possible effects of drugs on ONS diameter during anesthetic induction in healthy pigs. METHODS: Healthy piglets were divided into three groups: a control group, that received xylazine and ketamine (X/K); other that received xylazine, ketamine and propofol (X/K/P); and a third group that received xylazine, ketamine, and thiopental (X/K/T). The sheath diameter was assessed by ultrasonography calculating the average of three measurements of each eye from the left and right sides. RESULTS: 118 animals were anesthetized (49 X/K 33 X/K/P and 39 X/K/T). Mean ONS sizes on both sides in each group were 0.394 ± 0.048 (X/K), 0.407 ± 0.029 (X/K/P) and 0.378 ± 0.042 cm (X/K/T) (medians of 0.400, 0.405 and 0.389, respectively). The ONS diameter varied from 0.287-0.512 cm (mean of 0.302 ± 0.039 cm). For group X/K, the mean diameter was 0.394 ± 0.048 cm. Significant differences in ONS sizes between the groups P and T (X/K/P > X/K/T, p = 0.003) were found. No statistically significant differences were detected when other groups were compared (X/K = X/K/P, p = 0.302; X/K = X/K/T, p = 0.294). CONCLUSIONS: Sedation with thiopental lead to significative ONS diameter reduction in comparison with propofol. ONSUS may be useful to evaluate responses to thiopental administration.

Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension.

BACKGROUND: Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation. OBJECTIVE: To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model. METHODS: An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed. RESULTS: Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution. CONCLUSIONS: These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.

Impact of Three Methods of Ischemic Preconditioning on Ischemia-Reperfusion Injury in a Pig Model of Liver Transplantation.

BACKGROUND: Ischemic preconditioning (IPC), either direct (DIPC) or remote (RIPC), is a procedure aimed at reducing the harmful effects of ischemia-reperfusion (I/R) injury. OBJECTIVES: To assess the local and systemic effects of DIPC, RIPC, and both combined, in the pig liver transplant model. MATERIALS AND METHODS: Twenty-four pigs underwent orthotopic liver transplantation and were divided into 4 groups: control, direct donor preconditioning, indirect preconditioning at the recipient, and direct donor with indirect recipient preconditioning. The recorded parameters were: donor and recipient weight, graft-to-recipient weight ratio (GRWR), surgery time, warm and cold ischemia time, and intraoperative hemodynamic values. Blood samples were collected before native liver removal (BL) and at 0 h, 1 h, 3 h, 6 h, 12 h, 18 h, and 24 h post-reperfusion for the biochemical tests: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), creatinine, BUN (blood urea nitrogen), lactate, total and direct bilirubin. Histopathological examination of liver, gut, kidney, and lung fragments were performed, as well as molecular analyses for expression of the apoptosis-related BAX (pro-apoptotic) and Bcl-XL (anti-apoptotic) genes, eNOS (endothelial nitric oxide synthase) gene, and IL-6 gene related to inflammatory ischemia-reperfusion injury, using real-time polymerase chain reaction (RT-PCR). RESULTS: There were no differences between the groups regarding biochemical and histopathological parameters. We found a reduced ratio between the expression of the BAX gene and Bcl-XL in the livers of animals with IPC versus the control group. CONCLUSIONS: DIPC, RIPC or a combination of both, produce beneficial effects at the molecular level without biochemical or histological changes.

Inflammatory markers assessment in an animal model of intracranial hypertension: a randomized trial.

BACKGROUND: Intracranial hypertension (ICH) is a common final pathway of most neurosurgical pathologies and leads to poor prognosis if not detected and treated properly. Inflammatory markers have been assessed in clinical scenarios of neurological injuries, in which systemic and brain tissue aggressions may introduce bias. There is a lack of studies under controlled settings to isolate the ICH effect on inflammation. This study aims to evaluate the effects of ICH on the serum concentration of cytokines as biomarkers of neuroinflammation in an experimental model which isolates ICH from potential confounding variables. METHODS: An established model of ICH using an intracerebral pediatric bladder catheter and a multisensor intraparenchymal catheter was used in adult pigs (Sus domesticus). The animals were randomly allocated to 2 groups based on the catheter balloon volume used to simulate the ICP increase (4 ml or 7 ml). Cytokines were measured in 4 timepoints during the experiment: (1) 15 min before balloon insufflation; (2) 5 min after insufflation; (3) 125 min after insufflation; (4) 60 min after deflation. The following cytokines were measured IL-1α; IL-1ß; IL-1ra; IL-2; IL-4; IL-6; IL-8; IL-10; IL-12; IL-18; TNFα. Generalized estimating equations were modeled to compare the ICP and cytokines values between the groups along the experiment. The study sample size was powered to detect interactions between the groups and the study moments with an effect size (f) of at least 0.3. The ARRIVE checklist was followed. RESULTS: A total of 20 animals were studied (10 in each group, 4 ml or 7 ml balloon volume insufflation). The animal model was successful in increasing the ICP along the moments of the experiment (p < 0,001) and in creating an ICP gradient between the groups (p = 0,004). The interaction term (moment × group) was also significant (p < 0,001). There was a significant association between ICP elevation and most cytokines variation. The cytokines IL-1α, IL-1ß, IL1-ra, IL-6, IL-12, and IL-18 increased, whereas IL-2, IL-4, and TNF-α decreased. IL-10 did not vary significantly in response to the ICP elevation. CONCLUSION: The serum concentration of cytokines varied in response to intracranial hypertension. The study demonstrated the specific changes in each cytokine after intracranial hypertension and provides key information to guide neuroinflammation clinical research. The proposed experiment was successful as an animal model to the study of neuroinflammation biomarkers.

Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension.

BACKGROUND: Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels. METHODS: An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter. RESULTS: All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: -80.5 + 238.2 × AON. CONCLUSION: In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.

The Effects of Induction and Treatment of Intracranial Hypertension on Cerebral Autoregulation: An Experimental Study.

BACKGROUND: This study aimed to analyse cerebral autoregulation (CA) during induction and treatment of intracranial hypertension (ICH) in an experimental model. MATERIALS AND METHODS: Landrace and Duroc piglets were divided into mild and severe ICH groups. Four or seven millilitres of saline solution was infused into paediatric bladder catheter inserted in the parietal lobe (balloon inflation). After 1.5 h, a 3% saline solution was infused via venous catheter, and 30 min later, the bladder catheter balloon was deflated (surgery). The cerebral static autoregulation (sCA) index was evaluated using cerebral blood flow velocities (CBFV) obtained with Doppler ultrasound. RESULTS: Balloon inflation increased ICP in both groups. The severe ICH group showed significantly lower sCA index values (p=0.001, ANOVA) after balloon inflation (ICH induction) and a higher sCA index after saline injection (p=0.02) and after surgery (p=0.04). ICP and the sCA index were inversely correlated (r=-0.68 and p<0.05). CPP and the sCA index were directly correlated (r=0.74 and p<0.05). CONCLUSION: ICH was associated with local balloon expansion, which triggered CA impairment, particularly in the severe ICH group. Moreover, ICP-reducing treatments were associated with improved CA in subjects with severe ICH.

Acute and chronic changes in porcine rete mirabile after embolization with the Menox system: angiographic and histopathological analyses / Alterações angiográficas e histopatológicas agudas e crônicas da rete mirabile no modelo suíno com sistema embólico líquido Menox

Abstract Objective: To evaluate acute and chronic changes seen on angiographic and histopathological studies of porcine rete mirabile, comparing those treated with the Menox liquid embolic system (LES) and those treated with the Onyx LES. Materials and Methods: Five pigs, each weighing approximately 35 kg, were submitted to rete mirabile embolization under general anesthesia and fluoroscopic guidance, with the Menox LES or Onyx LES. Four animals were treated with the Menox LES and underwent cerebral angiography, followed by euthanasia, at 1, 30, 60, and 90 days after embolization. One animal was treated with the Onyx LES underwent the same procedures at 30 days after embolization. In a subsequent histopathological analysis, we compared the Menox LES and Onyx LES in terms of the acute and chronic changes observed. Results: We observed no significant changes in blood pressure, heart rate, or electrocardiographic parameters that could be attributed to the super-selective infusion of dimethyl sulfoxide or the Menox embolic agent. Fluoroscopy showed adequate material opacity, appropriate progression to the center of the rete mirabile and complete unilateral embolization. Microcatheters were uneventfully detached from the embolized nidus. We observed mild to moderate intravascular and extravascular inflammatory responses, without histological evidence of necrotizing arteritis. There were no adverse neurovascular events. Conclusion: The Menox LES appears to be safe and effective, as well as being apparently equivalent to the Onyx LES in terms of the postprocedure angiographic and histopathological findings.

Resumo Objetivo: Avaliar as alterações angiográficas e histopatológicas agudas e crônicas em rete mirabile suína tratadas com o Menox liquid embolic system (LES) e comparar essas alterações com a embolização com Onyx LES. Materiais e Métodos: A embolização da rete mirabile com Menox LES e Onyx LES foi realizada em cinco suínos pesando cerca de 35 kg sob anestesia geral e orientação fluoroscópica. Quatro animais tratados com Menox LES foram submetidos a angiografia cerebral seguida de eutanásia após 1, 30, 60 e 90 dias e um animal tratado com Onix LES foi submetido ao mesmo procedimento após 30 dias. A análise histopatológica subsequente para alterações agudas e crônicas avaliou o desempenho do Menox LES comparado ao Onyx LES. Resultados: Não foram observadas alterações significativas atribuíveis à infusão superseletiva de dimetilsulfóxido ou Menox nos parâmetros de pressão arterial, frequência cardíaca ou eletrocardiograma. A fluoroscopia mostrou opacidade adequada do material, progressão adequada para o centro da rete mirabile e embolização unilateral completa. Os microcateteres foram retirados do nidus embolizado sem complicações. Observou-se resposta inflamatória intravascular e extravascular leve a moderada, sem indício histológico de arterite necrosante. Nenhum dos casos apresentou eventos neurovasculares adversos. Conclusão: A injeção de Menox LES mostrou-se segura e eficaz, além de ser equivalente ao Onyx LES em relação aos achados angiográficos e histopatológicos pós-procedimento.

Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension / Avaliação da hemodinâmica encefálica utilizando Doppler transcraniano e sua correlação com a pressão intracraniana em um modelo animal de hipertensão intracraniana

ABSTRACT Background: Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation. Objective: To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model. Methods: An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed. Results: Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution. Conclusions: These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.

RESUMO Antecedentes: O Doppler transcraniano (DTC) é uma técnica não invasiva para a avaliação da hemodinâmica cerebral, porém existem controvérsias na literatura sobre sua aplicabilidade preditiva em situações de elevada pressão intracraniana (PIC). Objetivo: Investigar o fluxo sanguíneo cerebral pelo DTC e correlacioná-lo com as variações da PIC na fase aguda da hipertensão intracraniana em modelo animal. Métodos: Dois grupos de animais (suínos) foram submetidos a hipertensão intracraniana secundária à indução de diferentes volumes de hematoma, por meio da insuflação de balão intracraniano controlado com 4 e 7 mL de solução salina fisiológica (grupos A e B, respectivamente). Em seguida, administrou-se infusão venosa de solução salina hipertônica (SSH 3%). Foram coletados os valores dos parâmetros de PIC e DTC (velocidade sistólica [FVs], diastólica [FVd] e média [FVm] do fluxo sanguíneo cerebral), bem como o índice de pulsatilidade (IP). Comparações entre os parâmetros do DTC e o monitoramento da PIC foram realizadas. Resultados: Vinte porcos foram estudados, dez no grupo A e dez no grupo B. Correlação significativa entre IP e PIC foi obtida, principalmente logo após a elevação abrupta da PIC. Não houve correlação entre PIC e FVs, FVd ou FVm separadamente. Também não houve alteração significativa na PIC após a infusão de SSH. Conclusões: Esses resultados demonstram o potencial do IP como um bom parâmetro para a avaliação de pacientes com suspeita de elevação da PIC.

Effects of ischemic preconditioning in a pig model of large-for-size liver transplantation.

OBJECTIVE: In most cases of pediatric liver transplantation, the clinical scenario of large-for-size transplants can lead to hepatic dysfunction and a decreased blood supply to the liver graft. The objective of the present experimental investigation was to evaluate the effects of ischemic preconditioning on this clinical entity. METHODS: Eighteen pigs were divided into three groups and underwent liver transplantation: a control group, in which the weights of the donors were similar to those of the recipients, a large-for-size group, and a large-for-size + ischemic preconditioning group. Blood samples were collected from the recipients to evaluate the pH and the sodium, potassium, aspartate aminotransferase and alanine aminotransferase levels. In addition, hepatic tissue was sampled from the recipients for histological evaluation, immunohistochemical analyses to detect hepatocyte apoptosis and proliferation and molecular analyses to evaluate the gene expression of Bax (pro-apoptotic), Bcl-XL (anti-apoptotic), c-Fos and c-Jun (immediate-early genes), ischemia-reperfusion-related inflammatory cytokines (IL-1, TNF-alpha and IL-6, which is also a stimulator of hepatocyte regeneration), intracellular adhesion molecule, endothelial nitric oxide synthase (a mediator of the protective effect of ischemic preconditioning) and TGF-beta (a pro-fibrogenic cytokine). RESULTS: All animals developed acidosis. At 1 hour and 3 hours after reperfusion, the animals in the large-for-size and large-for-size + ischemic preconditioning groups had decreased serum levels of Na and increased serum levels of K and aspartate aminotransferase compared with the control group. The molecular analysis revealed higher expression of the Bax, TNF-alpha, I-CAM and TGF-beta genes in the large-for-size group compared with the control and large-for-size + ischemic preconditioning groups. Ischemic preconditioning was responsible for an increase in c-Fos, IL-1, IL-6 and e-NOS gene expression. CONCLUSION: Ischemia-reperfusion injury in this model of large-for-size liver transplantation could be partially attenuated by ischemic preconditioning.

Pentoxifylline associated to hypertonic saline solution attenuates inflammatory process and apoptosis after intestinal ischemia/reperfusion in rats.

PURPOSE: To evaluate intestinal inflammatory and apoptotic processes after intestinal ischemia/reperfusion injury, modulated by pentoxifylline and hypertonic saline. METHODS: It was allocated into four groups (n=6), 24 male Wistar rats (200 to 250 g) and submitted to intestinal ischemia for 40 min and reperfusion for 80 min: IR (did not receive any treatment); HS group (Hypertonic Saline, 4 ml/kg-IV); PTX group (Pentoxifylline, 30 mg/kg-IV); HS+PTX group (Hypertonic Saline and Pentoxifylline). All animals were heparinized (100 U/kg). At the end of reperfusion, ileal fragments were removed and stained on hematoxylin-eosin and histochemical studies for COX-2, Bcl-2 and cleaved caspase-3. RESULTS: The values of sO2 were higher on treated groups at 40 minutes of reperfusion (p=0.0081) and 80 minutes of reperfusion (p=0.0072). Serum lactate values were lower on treated groups after 40 minutes of reperfusion (p=0.0003) and 80 minutes of reperfusion (p=0.0098). Morphologic tissue injuries showed higher grades on IR group versus other groups: HS (p=0.0006), PTX (p=0.0433) and HS+PTX (p=0.0040). The histochemical study showed lesser expression of COX-2 (p=0.0015) and Bcl-2 (p=0.0012) on HS+PTX group. A lower expression of cleaved caspase-3 was demonstrated in PTX (p=0.0090; PTXvsIR). CONCLUSION: The combined use of pentoxifylline and hypertonic saline offers best results on inflammatory and apoptotic inhibitory aspects after intestinal ischemia/reperfusion.

A simplified experimental model of large-for-size liver transplantation in pigs.

OBJECTIVE: The ideal ratio between liver graft mass and recipient body weight for liver transplantation in small infants is unknown; however, if this ratio is over 4%, a condition called large-for-size may occur. Experimental models of large-for-size liver transplants have not been described in the literature. In addition, orthotopic liver transplantation is marked by high morbidity and mortality rates in animals due to the clamping of the venous splanchnic system. Therefore, the objective of this study was to create a porcine model of large-for-size liver transplantation with clamping of the supraceliac aorta during the anhepatic phase as an alternative to venovenous bypass. METHOD: Fourteen pigs underwent liver transplantation with whole-liver grafts without venovenous bypass and were divided into two experimental groups: the control group, in which the weights of the donors were similar to the weights of the recipients; and the large-for-size group, in which the weights of the donors were nearly 2 times the weights of the recipients. Hemodynamic data, the results of serum biochemical analyses and histological examination of the transplanted livers were collected. RESULTS: The mortality rate in both groups was 16.5% (1/7). The animals in the large-for-size group had increased serum levels of potassium, sodium, aspartate aminotransferase and alanine aminotransferase after graft reperfusion. The histological analyses revealed that there were no significant differences between the groups. CONCLUSION: This transplant method is a feasible experimental model of large-for-size liver transplantation.

Experimental model of intracranial hypertension with continuous multiparametric monitoring in swine.

OBJECTIVE: Intracranial hypertension (IH) develops in approximately 50% of all patients with severe traumatic brain injury (TBI). Therefore, it is very important to identify a suitable animal model to study and understand the pathophysiology of refractory IH to develop effective treatments. METHODS: We describe a new experimental porcine model designed to simulate expansive brain hematoma causing IH. Under anesthesia, IH was simulated with a balloon insufflation. The IH variables were measured with intracranial pressure (ICP) parenchymal monitoring, epidural, cerebral oximetry, and transcranial Doppler (TCD). RESULTS: None of the animals died during the experiment. The ICP epidural showed a slower rise compared with parenchymal ICP. We found a correlation between ICP and cerebral oximetry. CONCLUSION: The model described here seems useful to understand some of the pathophysiological characteristics of acute IH.

Endovascular treatment of peripheral arterial injury with covered stents: an experimental study in pigs.

OBJECTIVE: To evaluate the feasibility of using endovascular repair to treat penetrating arterial injuries with covered stents. Feasibility was examined according to the circumferential extent of the injury. INTRODUCTION: Surgical trauma often increases the risk of major morbidity and mortality associated with vascular injury, and endovascular repair has many advantages in such situations. METHODS: Twenty white male domestic pigs weighing 28-38 kg with controlled vascular injuries were divided into four equal groups according to the circumferential extent of their vascular lesion (i.e., no lesion, lesion <50%, lesion >50%, and complete lesion). The left common carotid artery was dissected with proximal and distal control, and this procedure was followed by controlled sectioning of the arterial wall. Local manual compression was applied for 10 min and was followed by endovascular repair with the placement of a 5x50 mm VIABHAN TM covered stent using the femoral approach. We also monitored additional variables, such as the duration of the procedures (the mean was 56.3 ± 19.1 min), ultrasound parameters (e.g., maximum arterial diameter, peak systolic and diastolic velocity, and resistance index), arteriography findings, and fluctuations in vital signs (e.g., cardiac output, arterial pressure, and central venous pressure). RESULTS: The experimental procedure was found to be feasible and reproducible. Repairs were successful in all animals in the control (no lesion) and <50% lesion groups. Success was also achieved in four out of five pigs in the >50% group and in one pig in the complete lesion group. DISCUSSION: The endovascular repair of an arterial injury is possible, but success depends on the circumferential extent of the arterial lesion. The present experimental model, which involved endovascular techniques, highlighted important factors that must be considered in future studies involving similar animals and materials.

Effects of ischemic preconditioning in a pig model of large-for-size liver transplantation

OBJECTIVE: In most cases of pediatric liver transplantation, the clinical scenario of large-for-size transplants can lead to hepatic dysfunction and a decreased blood supply to the liver graft. The objective of the present experimental investigation was to evaluate the effects of ischemic preconditioning on this clinical entity. METHODS: Eighteen pigs were divided into three groups and underwent liver transplantation: a control group, in which the weights of the donors were similar to those of the recipients, a large-for-size group, and a large-for-size + ischemic preconditioning group. Blood samples were collected from the recipients to evaluate the pH and the sodium, potassium, aspartate aminotransferase and alanine aminotransferase levels. In addition, hepatic tissue was sampled from the recipients for histological evaluation, immunohistochemical analyses to detect hepatocyte apoptosis and proliferation and molecular analyses to evaluate the gene expression of Bax (pro-apoptotic), Bcl-XL (anti-apoptotic), c-Fos and c-Jun (immediate-early genes), ischemia-reperfusion-related inflammatory cytokines (IL-1, TNF-alpha and IL-6, which is also a stimulator of hepatocyte regeneration), intracellular adhesion molecule, endothelial nitric oxide synthase (a mediator of the protective effect of ischemic preconditioning) and TGF-beta (a pro-fibrogenic cytokine). RESULTS: All animals developed acidosis. At 1 hour and 3 hours after reperfusion, the animals in the large-for-size and large-for-size + ischemic preconditioning groups had decreased serum levels of Na and increased serum levels of K and aspartate aminotransferase compared with the control group. The molecular analysis revealed higher expression of the Bax, TNF-alpha, I-CAM and TGF-beta genes in the large-for-size group compared with the control and large-for-size + ischemic preconditioning groups. Ischemic preconditioning was responsible for an increase in c-Fos, IL-1, IL-6 and e-NOS ...

Pentoxifylline associated to hypertonic saline solution attenuates inflammatory process and apoptosis after intestinal ischemia/reperfusion in rats

PURPOSE: To evaluate intestinal inflammatory and apoptotic processes after intestinal ischemia/reperfusion injury, modulated by pentoxifylline and hypertonic saline. METHODS: It was allocated into four groups (n=6), 24 male Wistar rats (200 to 250g) and submitted to intestinal ischemia for 40 min and reperfusion for 80 min: IR (did not receive any treatment); HS group (Hypertonic Saline, 4ml/kg-IV); PTX group (Pentoxifylline, 30mg/kg-IV); HS+PTX group (Hypertonic Saline and Pentoxifylline). All animals were heparinized (100U/kg). At the end of reperfusion, ileal fragments were removed and stained on hematoxylin-eosin and histochemical studies for COX-2, Bcl-2 and cleaved caspase-3. RESULTS: The values of sO2 were higher on treated groups at 40 minutes of reperfusion (p=0.0081) and 80 minutes of reperfusion (p=0.0072). Serum lactate values were lower on treated groups after 40 minutes of reperfusion (p=0.0003) and 80 minutes of reperfusion (p=0.0098). Morphologic tissue injuries showed higher grades on IR group versus other groups: HS (p=0.0006), PTX (p=0.0433) and HS+PTX (p=0.0040). The histochemical study showed lesser expression of COX-2 (p=0.0015) and Bcl-2 (p=0.0012) on HS+PTX group. A lower expression of cleaved caspase-3 was demonstrated in PTX (p=0.0090; PTXvsIR). CONCLUSION: The combined use of pentoxifylline and hypertonic saline offers best results on inflammatory and apoptotic inhibitory aspects after intestinal ischemia/reperfusion. .

Considerações sobre o modelo experimental de hipertensão intracranianae avaliação do sistema de microchip para monitoração de pressão epidural / Experimental model of intracranial hypertension and evaluation of the microchip system for epidural pressure monitoring of epidural pressure

Objetivo: Neste trabalho temos o objetivo de avaliar a acura?cia do sistema de aferic?a?o da pressão intracraniana (PIC) epidural com microchip. Me?todos: Foram estudados 27 sui?nos sob anestesia geraI, devidamente assistidos com monitoração ventilatória e hemodina?mica. Durante o experimento foi reproduzido um processo expansivo intracerebral programado no lobo frontal direito. O experimento constou de tre?s grupos (A, B e C) com hipertensão intracraniana gerada com balão reproduzindoum hematoma intracerebral. Em todos os grupos foram calibrados os para?metros normais: os dois sistemas de PIC foram comparados e estudados quanto a? correlação dos valores aferidos. Resultados: O comportamento médio da PIC ao longo dos momentos de avaliac?a?o foi estatisticamente diferente entre os grupos (p < 0,001). A reprodução de ressangramento resultou em elevac?a?o significativa da PIC (p < 0,001). Avaliando-se a acura?cia comparativa geral, verificou-se um coeficiente de correlação intraclasse de 0,8. Conclusa?o: O modelo de hipertensa?o intracraniana por bala?o em sui?nos e? facti?vel e confia?vel na gerac?a?o de hipertensa?o intracraniana. O sistema de aferic?a?o de pressa?o intracranianaepidural apresenta elevado coeficiente de correlac?a?o com o sistema de aferic?a?o parenquimatoso na avaliac?a?o global.

Objective: In this paper we aim to evaluate the accuracy of the measurement with microchip epidural system. Methods: Twenty-seven pigs with were studied, under generaI anesthesia, properly assisted with ventilation and hemodynamic monitoring. During the experiment, we have simulated frontal intracerebral expansive process. The experiment consisted of three groups (A, B and C) with intracranial hypertension generated with the simulation of an intracerebral hematoma. The two systems were compared andstudied as the correlation of the measured values. Results: The average behavior of the increased intracranial pressure (ICP) over the time points are statistically different between groups (p < 0.001). The simulation of rebleeding resulted in a significant increase in ICP (p < 0.001). Evaluating the overall comparative accuracy there was an intraclass correlation coefficient of 0.8. Conclusion: The model of intracranial hypertension balloon in pigs is feasible and reliable in generating intracranial hypertension. The system for measuring intracranial epidural pressure has a high correlation coefficient with the system parenchymal gauging the overall evaluation.