Experimental model for study of anorectal sphincter musculature by manometry and computerized tomography in piglets

There seems to be controversy on the anorectal sphincter presentation and anatomical division, as well as on its functional representation. Evaluation of the anorectal sphincter musculature has been achieved through several methods, including anorectal manometry and computerized tomography, but to date there is no experimental model allowing a detailed manometric study of this muscle complex. In this work, we have developed such a model, which should enable the manometric and radiographic study of the anatomical features and functional mechanisms of sphincteric injuries, as well as the assessment of drug effects on the anorectal musculature upon incontinence and constipation. Twenty-two piglets (aged 25-30 days, weighing 5-7 kg) were studied by anorectal manometry (rectoanal inhibitory reflex and vector volume) and computerized tomography (anorectal angle and anal canal length). The data obtained for the rectoanal inhibitory reflex, represented here as the average and standard deviation, were the following: relaxation duration = 14.75 +/- 3.62 s, sphincter basal pressure = 41.58 +/- 8.20 mmHg, relaxation index = 87.26 +/- 11.52%, speed of relaxation = 5.90 +/- 2.10 mm/s, and speed of relaxation recovery = 4.03 +/- 1.78 mm/s. As for the vector volume, results were as follows: vector volume = 2692.32 +/- 1298.12 mmHg(2) cm, sphincter length = 11.82 +/- 2.74 mm, high pressure zone length = 5.09 +/- 1.34 mm, maximum pressure = 61.50 +/- 20.58 mmHg, and asymmetry index = 43.50 +/- 10.03%. Radiographic evaluation led to the following results: anal canal length = 9.61 +/- 2.14 mm and anorectal angle = 137.91 +/- 7.75 degrees. The experimental model designed here allows both anorectal manometry and computerized tomography to be carried out in the same way it is performed in human beings, as long as animal sedation is strictly controlled.

Acute alterations in anorectal manometry induced by proximal and distal sphincterotomy. Experimental studies on piglets

Anal incontinence causes psychological, social and adaptive troubles prejudicial to the quality of life both in children and adults. Therefore, the detailed knowledge of its causes and the improvement of diagnostic and therapeutic methods increase the possibilities of a more adequate social life to patients with congenital anomalies or sphincteric lesions or degenerations. In this work, a manometric study was developed through an experimental model so as to analyze alterations in behavior of muscle groups responsible for the anorectal sphincteric mechanism, previous to and after proximal and distal lesions. Twenty-two pigs aged between 25 and 30 days, weighing 5-7 kg, were randomly divided into two groups. They were submitted to lesions of different levels in the anorectal muscle. The animals were studied by anorectal manometry (rectoanal inhibitory reflex and vector volume) before and after the lesions. The Student t test and the Wilcoxon test were applied for the statistical analyses, considered p <= 0.05. The proximal lesion preserved sphincter relaxation, retarding its closure [speed of relaxation recovery 4.35 +/- 2.10 vs. 2.70 +/- 1.32 mm/s (p = 0.001)], but it reduced the maximum pressure [62.45 +/- 20.02 vs. 40.36 +/- 12.59 mmHg (p = 0.004)] and vector volume [2,749 +/- 921 vs. 1,591 +/- 1,379 mmHg(2)cm (p = 0.005)]. There was an increment in the high-pressure zone [5.09 +/- 1.04 vs. 6.36 +/- 1.50 mm (p = 0.005)], but the asymmetry percentage and the sphincter length were maintained. The distal lesion did not alter the rectoanal inhibitory reflex, the high-pressure zone length, the asymmetry percentage, or the vector volume. Nevertheless, the sphincter length increased [11.82 +/- 2.82 vs. 14.09 +/- 2.39 mm (p = 0.022)] and the maximum pressure decreased [60.55 +/- 22.05 vs. 40.91 +/- 13.41 mmHg (p = 0.004)]. The alterations observed due to proximal lesion of the anorectal sphincter suggest a direct and more important interference of the levator ani muscle in the function of the sphincteric musculature than that caused by the distal lesion.

Evaluation of Cytokine Production from Peripheral Blood Mononuclear Cells of Type 1 Diabetic Patients

This study aims to evaluate the production of cytokines, tumor necrosis factor (TNF), and interleukin 10 (IL-10) in peripheral blood mononuclear cells (PBMCs) from type 1 diabetic (T1D) patients by means of intracellular staining, flow cytometry, and ELISA and to correlate it with inadequate (IN) and adequate (A) metabolic controls. We studied 28 patients with T1D and 20 healthy individuals (C) paired by sex and age. T1D patients were divided in patients with IN and A metabolic control. PBMC cultures were stimulated with LPS to evaluate TNF or were stimulated with PMA/ionomycin or concanavalin A to evaluate IL-10. The TNF levels in supernatant of stimulated cultures, evaluated by ELISA, of diabetic patients were similar to those of healthy individuals, although the percentage of CD 33(+) cells that were positive for TNF was higher in the T1D IN group compared to the T1D A group (P = 0.01). Similarly, the IL-10 levels evaluated by ELISA in stimulated cultures of T1D patients were not different from those in the control group; moreover, the percentage of CD3(+) cells positive for intracellular IL-10 were higher in the T1D IN group compared to C groups (P = 0.007). The increased levels of cytokines in T1D IN diabetic patients, with reduction in the A group, suggests that hyperglycemia stimulates an inflammatory state that can result in a deficient immune cellular response. The data suggest that assessment by intracellular staining seems to be more accurate than the ELISA technique in evaluating diabetic patients.

Sustained Ventricular Tachycardia Is Associated with Regional Myocardial Sympathetic Denervation Assessed with (123)I-Metaiodobenzylguanidine in Chronic Chagas Cardiomyopathy

Cardiac sympathetic denervation and ventricular arrhythmia are frequently observed in chronic Chagas cardiomyopathy (CCC). This study quantitatively evaluated the association between cardiac sympathetic denervation and sustained ventricular tachycardia (SVT) in patients with CCC. Methods: We prospectively investigated patients with CCC and left ventricular ejection fraction (LVEF) greater than 35% with SVT (SVT group: n = 5 15; mean age +/- SD, 61 +/- 8 y; LVEF, 51% +/- 8%) and patients without SVT (non-SVT group: n = 11; mean age +/- SD, 55 +/- 10 y; LVEF, 57% +/- 10%). Patients underwent myocardial scintigraphy with (123)I-metaiodobenzylguanidine ((123)I-MIBG) for the evaluation of sympathetic innervation and resting perfusion with (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) for the evaluation of myocardial viability. A visual semiquantitative score was attributed for regional uptake of each radiotracer using a 17-segment left ventricular segmentation model (0, normal; 4, absence of uptake). A mismatch defect was defined as occurring in segments with a 99mTc-MIBI uptake score of 0 or 1 and a (123)I-MIBG score of 2 or more. Results: Compared with the non-SVT group, the SVT group had a similar (99m)Tc-MIBI summed score (6.9 +/- 7.5 vs. 4.4 +/- 5.2, respectively, P = 0.69) but a higher (123)I-MIBG summed score (10.9 +/- 7.8 vs. 22.4 +/- 9.5, respectively, P = 0.007) and a higher number of mismatch defects per patient (2.0 +/- 2.2 vs. 7.1 +/- 2.0, respectively, P < 0.0001). The presence of more than 3 mismatch defects was strongly associated with the presence of SVT (93% sensitivity, 82% specificity; P = 0.0002). Conclusion: In CCC, the amount of sympathetically denervated viable myocardium is associated with the occurrence of SVT. Myocardial sympathetic denervation may participate in triggering malignant ventricular arrhythmia in CCC patients with relatively well-preserved ventricular function.

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Background The aim of this study was to validate a biomagnetic method (alternate current biosusceptometry, ACB) for monitoring gastric wall contractions in rats. Methods In vitro data were obtained to establish the relationship between ACB and the strain-gauge (SG) signal amplitude. In vivo experiments were performed in pentobarbital-anesthetized rats with SG and magnetic markers previously implanted under the gastric serosa or after ingestion of magnetic material. Gastric motility was quantified from the tracing amplitudes and frequency profiles obtained by Fast Fourier Transform. Key Results The correlation between in vitro signal amplitudes was strong (R = 0.989). The temporal cross-correlation coefficient between the ACB and SG signal amplitude was higher (P < 0.0001) in the postprandial (88.3 +/- 9.1 V) than in the fasting state (31.0 +/- 16.9 V). Irregular signal profiles, low contraction amplitudes, and smaller signal-to-noise ratios explained the poor correlation between techniques for fasting-state recordings. When a magnetic material was ingested, there was also strong correlation in the frequency and signal amplitude and a small phase-difference between the techniques. The contraction frequencies using ACB were 0.068 +/- 0.007 Hz (postprandial) and 0.058 +/- 0.007 Hz (fasting) (P < 0.002) and those using SG were 0.066 +/- 0.006 Hz (postprandial) and 0.059 +/- 0.008 Hz (fasting) (P < 0.005). Conclusions & Inferences In summary, ACB is reliable for monitoring gastric wall contractions using both implanted and ingested magnetic materials, and may serve as an accurate and sensitive technique for gastrointestinal motility studies.

A BALB/c mouse model shows that liver involvement in dengue disease is immune-mediated

In the present study, BALB/c mice were used to develop a model for the hepatic injury associated to dengue infection. Histological analysis after subcutaneous inoculation with a low viral dose of dengue-2 virus showed Kupffer cell hyperplasia and an increased inflammatory cellular infiltrate next to the bile ducts on days 5, 7 and 14 post-inoculation, mainly characterized by the presence of mononuclear cells. The liver mRNA transcription level of IL-1 beta was highest on the 5th day post-infection (p.i.) and decreased by the 21st day, TNF-alpha showed a peak of mRNA transcription after 14 days p.i. coinciding with the regression of cellular infiltrates and elevated expression of TGF-beta mRNA. Serum AST and ALT levels were slightly elevated at 7 and 14 days post-infection. Dengue-2 RNA levels were undetectable in the liver on any of the days following inoculation. Our observations suggest that, as it is true for humans, the animals undergo a transient and slight liver inflammation, probably due to local cytokine production and cellular infiltration in the liver. (C) 2010 Elsevier Inc. All rights reserved.

Anxiolytic-like effects induced by acute reversible inactivation of the bed nucleus of stria terminalis

There is conflicting evidence concerning the role of the bed nucleus of the stria terminalis (BNST) in fear and anxiety-elicited behavior. Most of the studies investigating this role, however, employed irreversible lesions of this nucleus. The objective of the present study was to investigate the effects of an acute and reversible inactivation of the BNST in rats submitted to the Vogel conflict test (VCT) and contextual fear conditioning, two widely employed animal models that are responsive to prototypal anxiolytic drugs. Male Wistar rats were submitted to stereotaxic surgery to bilaterally implant cannulae into the BNST. Ten minutes before the test they received bilateral microinjections of cobalt chloride (COCl(2)) (1 mM/100 nL), a nonselective synapse blocker. COCl(2) produced anxiolytic-like effects in tests, increasing the number of punished licks in the VCT and decreasing freezing behavior and the increase in mean arterial blood pressure and heart rate of animals re-exposed to the context where they had received electrical foot shocks 24 h before. The results indicate that the BNST is engaged in behavioral responses elicited by punished stimuli and aversively conditioned contexts, reinforcing its proposed role in anxiety. (C) 2008 IBRO. Published by Elsevier Ltd. All rights reserved.

Role of cytokines (TNF-alpha, IL-1 beta and KC) in the pathogenesis of CPT-11-induced intestinal mucositis in mice: effect of pentoxifylline and thalidomide

Introduction Irinotecan (CPT-11) is an inhibitor of DNA topoisomerase I and is clinically effective against several cancers. A major toxic effect of CPT-11 is delayed diarrhea; however, the exact mechanism by which the drug induces diarrhea has not been established. Purpose Elucidate the mechanisms of induction of delayed diarrhea and determine the effects of the cytokine production inhibitor pentoxifylline (PTX) and thalidomide (TLD) in the experimental model of intestinal mucositis, induced by CPT-11. Materials and methods Intestinal mucositis was induced in male Swiss mice by intraperitoneal administration of CPT-11 (75 mg/kg) daily for 4 days. Animals received subcutaneous PTX (1.7, 5 and 15 mg/kg) or TLD (15, 30, 60 mg/kg) or 0.5 ml of saline daily for 5 and 7 days, starting 1 day before the first CPT-11 injection. The incidence of delayed diarrhea was monitored by scores and the animals were sacrificed on the 5th and 7th experimental day for histological analysis, immunohistochemistry for TNF-alpha and assay of myeloperoxidase (MPO) activity, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and KC ELISA. Results CPT-11 caused significant diarrhea, histopathological alterations (inflammatory cell infiltration, loss of crypt architecture and villus shortening) and increased intestinal tissue MPO activity, TNF-alpha, IL-1 beta and KC level and TNF-alpha immuno-staining. PTX inhibited delayed diarrhea of mice submitted to intestinal mucositis and reduced histopathological damage, intestinal MPO activity, tissue level of TNF-alpha, IL-1 beta and KC and TNF-alpha immuno-staining. TLD significantly reduced the lesions induced by CPT-11 in intestinal mucosa, decreased MPO activity, TNF-alpha tissue level and TNF-alpha immuno-staining, but did not reduce the severity of diarrhea. Conclusion These results suggest an important role of TNF-alpha, IL-1 beta and KC in the pathogenesis of intestinal mucositis induced by CPT-11.

5-HT1A receptors in the dorsal hippocampus mediate the anxiogenic effect induced by the stimulation of 5-HT neurons in the median raphe nucleus

We evaluated the involvement of dorsal hippocampus (DH) 5-HT1A receptors in the mediation of the behavioral effects caused by the pharmacological manipulation of 5-HT neurons in the median raphe nucleus (MRN). To this end, we used the rat elevated T-maze test of anxiety. The results showed that intra-DH injection of the 5-HT1A/7 agonist 8-OH-DPAT facilitated inhibitory avoidance, an anxiogenic effect, without affecting escape. Microinjection of the 5-HT1A antagonist WAY-100635 was ineffective. In the elevated T-maze, inhibitory avoidance and escape have been related to generalized anxiety and panic disorders, respectively. Intra-MRN administration of the excitatory aminoacid kainic acid, which non-selectively stimulates 5-HT neurons in this brain area facilitated inhibitory avoidance and impaired escape performance, but also affected locomotion. Intra-MRN injection of WAY-100635, which has a disinhibitory effect on the activity of 5-HT neurons in this midbrain area, only facilitated inhibitory avoidance. Preadministration of WAY-100635 into the DH blocked the behavioral effect of intra-MRN injection of WAY-100635, but not of kainic acid. These results indicate that DH 5-HT1A receptors mediate the anxiogenic effect induced by the selective stimulation of 5-HT neurons in the MRN. (c) 2007 Elsevier B.V. and ECNP. All rights reserved.

Cannabidiol inhibits the hyperphagia induced by cannabinoid-1 or serotonin-1A receptor agonists

Delta 9-THC is a component of Cannabis sativa that increases food intake in animals and humans, an effect prevented by selective CB1 receptor antagonists. Cannabidiol (CBD) is another constituent of this plant that promotes several opposite neuropharmacological effects compared to Delta 9-THC. CBD mechanisms of action are still not clear, but under specific experimental conditions it can antagonize the effects of cannabinoid agonists, block the reuptake of anandamide and act as an agonist of 5-HT1A receptors. Since both the cannabinoid and serotoninergic systems have been implicated in food intake control, the aim of the present work was to investigate the effects caused by CBD on hyperphagia induced by agonists of CB1 or 5-HT1A receptors. Fed or fasted Wistar rats received intraperitoneal (i.p.) injections of CBD (1, 10 and 20 mg/kg) and food intake was measured 30 min later for 1 h. Moreover, additional fed or fasted groups received, after pretreatment with CBD (20 mg/kg) or vehicle, i.p. administration of vehicle, a CBI receptor agonist WIN55,212-2 (2 mg/kg) or a 5-HT1A receptor agonist 8-OH-DPAT (1 mg/kg) and were submitted to the food intake test for 1 h. CBD by itself did not change food intake in fed or fasted rats. However, it prevented the hyperphagic effects induced by WIN55,212-2 or 8-OH-DPAT. These results show that CBD can interfere with food intake changes induced by a CB1 or 5-HT1A receptor agonist, suggesting that its role as a possible food intake regulator should be further investigate. (C) 2011 Elsevier Inc. All rights reserved.

Severity dependent increases in circulating cardiac troponin I and MMP-9 concentrations after experimental acute pulmonary thromboembolism

Background: Making the diagnosis of acute pulmonary thromboembolism (APT) and assessing its severity is very challenging, While cardiac troponin I (cTnI) concentrations are promising in risk stratification, no previous study has examined whether there is a linear relation between cTnI concentrations and the severity of APT. Moreover, matrix metalloprotemases (MMPs) are involved in the pathophysiology of APT. However, it is unknown whether the increases in MMP concentrations after APT reflect the severity of this condition. We examined whether the circulating concentrations of these biomarkers increase in proportion to the severity of experimental APT induced in anesthetized dogs. Methods: APT was induced with autologous blood clots (saline, 1, 3, or 5 ml/kg) injected into the right atrium. Hemodynamic evaluations were carried out for 120 min. Gelatin zymography of MMP-2 and MMP-9 from plasma samples were performed and serum cTnI concentrations were determined at baseline and 120 min after APT. Results: While no significant increases in pro-MMP-2 concentrations were found after APT, pro-MMP-9 concentrations increased by 80% only after 5 ml/kg of clot embolization. Serum cTnI and plasma pro-MMP-9 concentrations correlated positively with pulmonary vascular resistance (P=0.007 and rs=0.833 for troponin 1, and P=0.034 and rs=0.684 for pro-MMP-9) and with pulmonary artery pressure (P=0.005 and rs=0.610 for troponin 1, and P=0.022 and rs=0.720 for pro-MMP-9). Conclusions: Circulating cTnI and pro-MMP-9 increase in proportion to the severity of APT, although the increases in plasma pro-MMP-9 are less clear with less severe APT. These findings may be relevant for clinical APT. (C) 2007 Elsevier B.V. All rights reserved.

Neutrophil migration induced by IL-1 beta depends upon LTB4 released by macrophages and upon TNF-alpha and IL-1 beta released by mast cells

In the present study, we investigate whether mast cells and macrophages are involved in the control of IL-1 beta-induced neutrophil migration, as well as the participation of chemotactic mediators. IL-1 beta induced a dose-dependent neutrophil migration to the peritoneal cavity of rats which depends on LTB4, PAF and cytokines, since the animal treatment with inhibitors of these mediators (MK 886, PCA 4248 and dexamethasone respectively) inhibited IL-1 beta-induced neutrophil migration. The neutrophil migration induced by IL-1 beta is dependent on mast cells and macrophages, since depletion of mast cells reduced the process whereas the increase of macrophage population enhanced the migration. Moreover, mast cells or macrophages stimulated with IL-1 beta released a neutrophil chemotactic factor, which mimicked the neutrophil migration induced by IL-1 beta. The chemotactic activity of the supernatant of IL-1 beta-stimulated macrophages is due to the presence of LTB4, since MK 886 inhibited its release. Moreover, the chemotactic activity of IL-1 beta-stimulated mast cells supernatant is due to the presence of IL-1 beta and TNF-alpha, since antibodies against these cytokines inhibited its activity. Furthermore, significant amounts of these cytokines were detected in the supernatant. In conclusion, our results suggest that neutrophil migration induced by IL-1 beta depends upon LTB4 released by macrophages and upon IL-1 beta and TNF alpha released by mast cells.

Gastric damage induced by different doses of indomethacin in rats is variably affected by inhibiting iNOS or leukocyte infiltration

Aim: To evaluate the effect of inhibiting inducible nitric oxide synthase (iNOS), by aminoguanidine, or leukocyte infiltration, by fucoidin, on gastropathy induced by two different doses of indomethacin in rats. Methods: Rats were treated with saline, aminoguanidine (50 or 100 mg.kg(-1), i. p.) or fucoidin (25 mg.kg(-1), i. v.). Indomethacin was then given at a dose of 5 or 20 mg.kg(-1). At the end of 3 h, macroscopic gastric damage and myeloperoxidase (MPO) activity were assessed. Results: Aminoguanidine reduced the gastric damage induced by indomethacin at 20 mg.kg(-1), but increased gastric MPO activity. However, aminoguanidine did not influence the gastric damage induced by indomethacin at 5 mg.kg(-1). Fucoidin prevented both the gastric damage and the increase in gastric MPO activity induced by indomethacin at 20 mg. kg(-1), but not at 5 mg.kg(-1). Conclusion: Indomethacin at a dose of 20 mg.kg(-1), but not at 5 mg.kg(-1), induced gastropathy dependent on neutrophil infiltration and iNOS-generated NO.

Neuromuscular activity of BaTX, a presynaptic basic PLA(2) isolated from Bothrops alternatus snake venom

We have previously isolated a Lys49 phospholipase A(2) homolog (BaTX) from Bothrops alternatus snake venom using a combination of molecular exclusion chromatography and reverse phase HPLC and shown its ability to cause neuromuscular blockade. In this work, we describe a one-step procedure for the purification of this toxin and provide further details of its neuromuscular activity. The toxin was purified by reverse phase HPLC and its purity and molecular mass were confirmed by SIDS-PAGE, MALDI-TOF mass spectrometry, amino acid analysis and N-terminal sequencing. BaTX (0.007-1.4 mu M) produced time-dependent, irreversible neuromuscular blockade in isolated mouse phrenic nerve-diaphragm and chick biventer cervicis preparations (time to 50% blockade with 0.35 mu M toxin: 58 +/- 4 and 24 +/- 1 min, respectively; n = 3-8; mean +/- S.E.) without significantly affecting the response to direct muscle stimulation. In chick preparations, contractures to exogenous acetylcholine (55 and 110 mu M) or KCl (13.4 mM) were unaltered after complete blockade by all toxin concentrations. These results, which strongly suggested a presynaptic mechanism of action for this toxin, were reinforced by (1) the inability of BaTX to interfere with the carbachol-induced depolarization of the resting membrane, (2) a significant decrease in the frequency and amplitude of miniature end-plate potentials, and (3) a significant reduction (59 +/- 4%, n=12) in the quantal content of the end-plate potentials after a 60 min incubation with the toxin (1.4 mu M). In addition, a decrease in the organ bath temperature from 37 degrees C to 24 degrees C and/or the replacement of calcium with strontium prevented the neuromuscular blockade, indicating a temperature-dependent effect possibly mediated by enzymatic activity. (C) 2009 Elsevier Inc. All rights reserved.

A combined study of behavior and Fos expression in limbic structures after re-testing Wistar rats in the elevated plus-maze

The elevated plus-maze is an animal model used to study anxiety. In a second session, rats show a reduction in the exploratory behavior even when the two sessions are separated by intervals as large as 7 days. The aim of the present study was to investigate whether the reduction in the exploratory behavior is maintained after intervals larger than 7 days. Additionally, we aimed at investigating eventual correlations between behaviors in the plus-maze and activation of limbic structures as measured by Fos protein expression after the second session. Rats were tested for 5 min in the elevated plus-maze and re-tested 3, 9 or 33 days later. Other groups were tested only once. The rat brains were processed for immunohistochemical detection of Fos protein. The results show a decrease in the open arms exploration in the second trial with intervals of 3, 9 and 33 days. The expression of Fos protein in the piriform cortex, septal nucleus and paraventricular hypothalamic nucleus in the groups tested with intervals of 9 and 33 days were statistically different from the other groups. The alterations observed in exploratory behavior in the second session in the plus-maze did not correlate with Fos expression. In conclusion, although the specific test conditions were sufficient to evoke behavioral alterations in exploration in the elevated plus-maze, they were enough to induce significant Fos protein expression in piriform cortex, septal nucleus and thalamic and hypothalamic paraventricular nuclei but not in other areas such as dorsomedial nucleus of the hypothalamus and amygdala nuclei, known to be also active participants in circuits controlling fear and anxiety. (C) 2010 Elsevier Inc. All rights reserved.