N-acetyl-L-cysteine improves the performance of chronic cyclic heat-stressed finisher broilers but has no effect on tissue glutathione levels.

1. It was hypothesised that dietary N-acetyl-L-cysteine (NAC) in feed, as a source of cysteine, could improve the performance of heat-stressed finisher broilers by fostering glutathione (GSH) synthesis. GSH is the most abundant intracellular antioxidant for which the sulphur amino acid cysteine is rate limiting for its synthesis.2. In the first experiment, four levels of NAC: 0, 500, 1000 and 2000 mg/kg were added to a diet with a suboptimal level of sulphur amino acids in the finisher phase. In the second experiment, NAC was compared to other sulphur amino acid sources at equal molar amounts of digestible sulphur amino acids. Birds were allocated to four groups: control, 2000 mg/kg NAC, 1479 mg/kg L-cystine, and 2168 mg/kg Ca-salt of 2-hydroxy-4-(methylthio)butanoic acid. A chronic cyclic heat stress model (temperature was increased to 34°C for 7 h daily) was initiated at 28 d of age.3. In the first experiment, growth performance and feed efficiency in the finisher phase were significantly improved by graded NAC. ADG was 88.9, 92.2, 93.7 and 97.7 g/d, and the feed-to-gain ratio was 2.18, 1.91, 1.85 and 1.81 for the 0, 500, 1000 and 2000 mg/kg NAC treatments, respectively. However, liver and heart GSH levels were not affected by NAC. On d 29, liver gene transcript of cystathionine-beta-synthase like was reduced by NAC, which suggested reduced trans-sulphuration activity. The second experiment showed that L-cystine and Ca-salt of 2-hydroxy-4-(methylthio) butanoic acid were more effective in improving performance than NAC.4. In conclusion, N-acetyl-L-cysteine improved dose-dependently growth and feed efficiency in heat-stressed finishing broilers. However, this was not associated with changes in tissue GSH levels, but more likely worked by sparing methionine and/or NAC's and cysteine's direct antioxidant properties.

In vitro stability and ex vivo absorption of thymol monoglucosides in the porcine gut.

Thymol α-D-glucopyranoside (TαG) and thymol ß-D-glucopyranoside (TßG) are believed to have different kinetic behaviours in the porcine gut than its parent aglycon thymol. However, recently, it was shown that concentrations of both glucosides decreased rapidly in the stomach and proximal small intestine following oral supplementation to piglets as did thymol. Yet, the stability of thymol glucosides in gut contents and their absorption route remains obscure. Therefore, a series of in vitro incubations were performed, simulating the impact of pH, digestive enzymes, bacterial activity and mucosal extracts on stability of these glucosides. Their absorption mechanisms were investigated using the Ussing chamber model in the presence or the absence of inhibitors of sodium-dependent glucose linked transporter 1 and lactase phlorizin hydrolase. Both glucosides remained intact at physiological pH levels in the presence of digestive enzymes. Recoveries from TαG and TßG were below 90% when incubated with small intestinal homogenates from the distal jejunum or from all sampled sites, respectively. However, no aglycon could be detected in these samples. Bacterial inoculum of the small intestine, on the other hand, hydrolysed TßG quickly with up to 44% of free aglycon appearing. TαG proved more resistant to porcine gastro-intestinal bacterial glucosidases with only trace amounts (<1%) of free thymol at the end of the incubations. Electrophysiological measurements in Ussing chambers did not suggest active transport of the glucosides. Mucosal TαG and TßG concentrations were unchanged between start and end of the absorption measurements. Additionally, no TαG and only a very limited amount of TßG were retrieved from the serosal side. Tissue associated concentrations, although marginal (<1% of luminal concentration), were mainly as intact glucoside or as aglycon for TαG and TßG, respectively. Addition of both inhibitors significantly increased the amount of intact glucosides retrieved from the mucosal tissues as compared to controls. In conclusion, bacterial hydrolysis was identified as the most important source of TßG loss, whereas TαG seemed less prone to degradation or absorption in these in vitro and ex vivo models.

Impact of a dietary challenge with peroxidized oil on the glutathione redox status and integrity of the small intestine in weaned piglets.

Glutathione (GSH) is considered to play an important role in maintaining the integrity of the small intestine. In piglets, altered mucosal GSH levels might therefore be involved in weaning-induced changes of the small intestinal morphology and barrier function. To test this hypothesis, we aimed to challenge the mucosal GSH redox status during the first 28 days after weaning, by feeding diets containing 5% fresh linseed oil (CON), or 2.5% (OF1) or 5% (OF2) peroxidized linseed oil (peroxide value 225 mEq O2/kg oil) and exploring the effects on gut integrity. Piglets were pair-fed and had a total daily feed allowance of 32 g/kg BW. A fourth treatment included animals that were fed the control diet ad libitum (ACON). Animals were sampled at days 5 and 28 post-weaning. The malondialdehyde (MDA) concentration and GSH redox status (GSH/GSSG Eh) were determined in blood, liver and small intestinal mucosa. Histomorphology of the duodenal and jejunal mucosa was determined, and Ussing chambers were used to assess fluorescein isothiocyanate dextran (FD4) and horseradish peroxidase (HRP) fluxes across the mucosa. Results show that peroxidized linseed oil imposed an oxidative challenge at day 28, but not at day 5 post-weaning. At day 28, increasing levels of dietary peroxides to pair-fed pigs linearly increased MDA levels in duodenal and jejunal mucosa. Moreover, FD4 fluxes were significantly increased in OF1 (+75%) and OF2 (+64%) in the duodenum, and HRP fluxes tended (P=0.099) to show similar differences, as compared to CON. This co-occurred with a significant 11 mV increase of the hepatic GSH/GSSG Eh, potentiated by a significantly increased GSH peroxidase activity for treatments OF1 (+47%) and OF2 (+63%) in liver as compared to CON. Furthermore; duodenal HRP flux significantly correlated with the hepatic glutathione disulphide (GSSG) level (r=0.650), as also observed in the jejunum for hepatic GSSG (r=0.627) and GSH/GSSG Eh (r=0.547). The jejunal permeability was not affected, but FD4 and HRP fluxes significantly correlated with the local GSH (r=0.619; r=0.733) and GSSG (r=0.635; r=0586) levels. Small intestinal histomorphology was not affected by dietary lipid peroxides, nor were there any correlations found with the GSH redox system. To conclude, under oxidative stress conditions, jejunal barrier function is related to the local and hepatic GSH redox system. It is suggested that the hepatic GSH system participates in the elimination of luminal peroxides, and thereby impacts on duodenal barrier function.

Patient-specific CFD models for intraventricular flow analysis from 3D ultrasound imaging: Comparison of three clinical cases.

BACKGROUND: As the intracardiac flow field is affected by changes in shape and motility of the heart, intraventricular flow features can provide diagnostic indications. Ventricular flow patterns differ depending on the cardiac condition and the exploration of different clinical cases can provide insights into how flow fields alter in different pathologies. METHODS: In this study, we applied a patient-specific computational fluid dynamics model of the left ventricle and mitral valve, with prescribed moving boundaries based on transesophageal ultrasound images for three cardiac pathologies, to verify the abnormal flow patterns in impaired hearts. One case (P1) had normal ejection fraction but low stroke volume and cardiac output, P2 showed low stroke volume and reduced ejection fraction, P3 had a dilated ventricle and reduced ejection fraction. RESULTS: The shape of the ventricle and mitral valve, together with the pathology influence the flow field in the left ventricle, leading to distinct flow features. Of particular interest is the pattern of the vortex formation and evolution, influenced by the valvular orifice and the ventricular shape. The base-to-apex pressure difference of maximum 2mmHg is consistent with reported data. CONCLUSION: We used a CFD model with prescribed boundary motion to describe the intraventricular flow field in three patients with impaired diastolic function. The calculated intraventricular flow dynamics are consistent with the diagnostic patient records and highlight the differences between the different cases. The integration of clinical images and computational techniques, therefore, allows for a deeper investigation intraventricular hemodynamics in patho-physiology.

Patient-specific CFD simulation of intraventricular haemodynamics based on 3D ultrasound imaging.

BACKGROUND: The goal of this paper is to present a computational fluid dynamic (CFD) model with moving boundaries to study the intraventricular flows in a patient-specific framework. Starting from the segmentation of real-time transesophageal echocardiographic images, a CFD model including the complete left ventricle and the moving 3D mitral valve was realized. Their motion, known as a function of time from the segmented ultrasound images, was imposed as a boundary condition in an Arbitrary Lagrangian-Eulerian framework. RESULTS: The model allowed for a realistic description of the displacement of the structures of interest and for an effective analysis of the intraventricular flows throughout the cardiac cycle. The model provides detailed intraventricular flow features, and highlights the importance of the 3D valve apparatus for the vortex dynamics and apical flow. CONCLUSIONS: The proposed method could describe the haemodynamics of the left ventricle during the cardiac cycle. The methodology might therefore be of particular importance in patient treatment planning to assess the impact of mitral valve treatment on intraventricular flow dynamics.

Unstructured hexahedral mesh generation of complex vascular trees using a multi-block grid-based approach.

The trend towards realistic numerical models of (pathologic) patient-specific vascular structures brings along larger computational domains and more complex geometries, increasing both the computation time and the operator time. Hexahedral grids effectively lower the computational run time and the required computational infrastructure, but at high cost in terms of operator time and minimal cell quality, especially when the computational analyses are targeting complex geometries such as aneurysm necks, severe stenoses and bifurcations. Moreover, such grids generally do not allow local refinements. As an attempt to overcome these limitations, a novel approach to hexahedral meshing is proposed in this paper, which combines the automated generation of multi-block structures with a grid-based method. The robustness of the novel approach is tested on common complex geometries, such as tree-like structures (including trifurcations), stenoses, and aneurysms. Additionally, the performance of the generated grid is assessed using two numerical examples. In the first example, a grid sensitivity analysis is performed for blood flow simulated in an abdominal mouse aorta and compared to tetrahedral grids with a prismatic boundary layer. In the second example, the fluid-structure interaction in a model of an aorta with aortic coarctation is simulated and the effect of local grid refinement is analyzed.

Influence of valve size, orientation and downstream geometry of an aortic BMHV on leaflet motion and clinically used valve performance parameters.

The aim of this study was to reconcile some of our own previous work and the work of others to generate a physiologically realistic numerical simulation environment that allows to virtually assess the performance of BMHVs. The model incorporates: (i) a left ventricular deformable model to generate a physiological inflow to the aortic valve; (ii) a patient-specific aortic geometry (root, arch and descending aorta); (iii) physiological pressure and flow boundary conditions. We particularly studied the influence of downstream geometry, valve size and orientation on leaflet kinematics and functional indices used in clinical routine. Compared to the straight tube geometry, the patient-specific aorta leads to a significant asynchronous movement of the valve, especially during the closing of the valve. The anterior leaflet starts to close first, impacts the casing at the closed position and remains in this position. At the same time, the posterior leaflet impacts the pivoting mechanisms at the fully open position. At the end of systole, this leaflet subsequently accelerates to the closed position, impacting the casing with an angular velocity of approximately -477 rad/s. The valve size greatly influences the transvalvular pressure gradient (TPG), but does not change the overall leaflet kinematics. This is in contrast to changes in valve orientation, where changing valve orientation induces large differences in leaflet kinematics, but the TPG remains approximately the same.

Validation of a numerical FSI simulation of an aortic BMHV by in vitro PIV experiments.

In this paper, a validation of a recently developed fluid-structure interaction (FSI) coupling algorithm to simulate numerically the dynamics of an aortic bileaflet mechanical heart valve (BMHV) is performed. This validation is done by comparing the numerical simulation results with in vitro experiments. For the in vitro experiments, the leaflet kinematics and flow fields are obtained via the particle image velocimetry (PIV) technique. Subsequently, the same case is numerically simulated by the coupling algorithm and the resulting leaflet kinematics and flow fields are obtained. Finally, the results are compared, revealing great similarity in leaflet motion and flow fields between the numerical simulation and the experimental test. Therefore, it is concluded that the developed algorithm is able to capture very accurately all the major leaflet kinematics and dynamics and can be used to study and optimize the design of BMHVs.

Haemodynamic impact of stent-vessel (mal)apposition following carotid artery stenting: mind the gaps!

Carotid artery stenting (CAS) has emerged as a minimally invasive alternative to endarterectomy but its use in clinical treatment is limited due to the post-stenting complications. Haemodynamic actors, related to blood flow in the stented vessel, have been suggested to play a role in the endothelium response to stenting, including adverse reactions such as in-stent restenosis and late thrombosis. Accessing the flow-related shear forces acting on the endothelium in vivo requires space and time resolutions which are currently not achievable with non-invasive clinical imaging techniques but can be obtained from image-based computational analysis. In this study, we present a framework for accurate determination of the wall shear stress (WSS) in a mildly stenosed carotid artery after the implantation of a stent, resembling the commercially available Acculink (Abbott Laboratories, Abbott Park, Illinois, USA). Starting from angiographic CT images of the vessel lumen and a micro-CT scan of the stent, a finite element analysis is carried out in order to deploy the stent in the vessel, reproducing CAS in silico. Then, based on the post-stenting anatomy, the vessel is perfused using a set of boundary conditions: total pressure is applied at the inlet, and impedances that are assumed to be insensitive to the presence of the stent are imposed at the outlets. Evaluation of the CAS outcome from a geometrical and haemodynamic perspective shows the presence of atheroprone regions (low time-average WSS, high relative residence time) colocalised with stent malapposition and stent strut interconnections. Stent struts remain unapposed in the ostium of the external carotid artery disturbing the flow and generating abnormal shear forces, which could trigger thromboembolic events.

Magnetic resonance imaging of the sternal extremity of the clavicle in forensic age estimation: towards more sound age estimates.

OBJECTIVES: The development of the sternal extremity of the clavicle was examined prospectively with magnetic resonance imaging (MRI) for forensic bone age assessment. The objectives were to examine whether these results were comparable with the literature on plain radiography and CT, to provide age prediction intervals that correctly reflect the high variability in clavicular growth among individuals and to investigate whether MRI of the clavicle can be used to differentiate between individuals younger or older than 18 years. METHODS: The clavicles of 220 volunteers (16-26 years) were examined with 3-T MRI and evaluated according to the Schmeling and Kreitner classification (Schmeling, Int J Legal Med 118:5-8, 2004; Kreitner, Eur Radiol 8:1116-1122, 1998). An additional hand/wrist radiograph was taken and evaluated according to Greulich and Pyle (1959). After a descriptive analysis, a multivariate ordinal regression model was fitted and embedded in a Bayesian framework based on Thevissen et al. (Int J Legal Med 124:35-42, 2009). RESULTS: The descriptive results were concordant with the literature, although the Kreitner classification is recommended and simultaneous evaluation of the hand is considered a basic requirement (Schmeling, Int J Legal Med 118:5-8, 2004). The 95 % credibility interval for both genders with bilateral stage IV is 20-26 years. The corresponding estimated probability of being younger than 18 years is 0.8 % in females and 0.2 % in males. CONCLUSION: MRI of the sternal extremity of the clavicle can be used to differentiate between being younger or older than 18, but a simultaneous evaluation of the hand/wrist is essential. Future evaluation of the predictive performance of the model, using comparable but larger reference samples, is necessary to validate these results.

FSI simulation of asymmetric mitral valve dynamics during diastolic filling.

In this article, we present a fluid-structure interaction algorithm accounting for the mutual interaction between two rigid bodies. The algorithm was used to perform a numerical simulation of mitral valve (MV) dynamics during diastolic filling. In numerical simulations of intraventricular flow and MV motion, the asymmetry of the leaflets is often neglected. In this study the MV was rendered as two rigid, asymmetric leaflets. The 2D simulations incorporated the dynamic interaction of blood flow and leaflet motion and an imposed subject-specific, transient left ventricular wall movement obtained from ultrasound recordings. By including the full Jacobian matrix in the algorithm, the speed of the simulation was enhanced by more than 20% compared to using a diagonal Jacobian matrix. Furthermore, our results indicate that important features of the flow field may not be predicted by the use of symmetric leaflets or in the absence of an adequate model for the left atrium.

Changes in the pig small intestinal mucosal glutathione kinetics after weaning.

Glutathione (GSH) serves as a major endogenous antioxidant and its kinetics have been poorly described in the weaned pig. This study was to assess the effect of birth weight, sex, and days postweaning on the small intestine (SI) mucosal GSH kinetics. At weaning (18.8 ± 0.44 d) 34 pairs of intrauterine growth restricted (IUGR) and normal birth weight sex-matched littermates were selected and fed a starter diet ad libitum until 1 h before sampling at 0, 2, 5, 12 and 28 d postweaning. Mucosa was collected from 2 SI sites, at 5% and at 75% of total length, to determine GSH and glutathione disulfide (GSSG), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), and plasm GSH-Px and MDA. At both 5 and 75% of total length, the GSH-Px activity and GSH concentrations increased gradually with increasing days postweaning to peak at day 12 (P < 0.05). The GSH-Px activity and GSH concentrations at 5% of SI length were consistently higher as compared to 75% of SI length (e.g., at day 12, 43.2 and 28.9 units/mg protein and 21.5 and 15.4 µmol/g protein, respectively). The GSSG:GSH ratio at 5% of total length was 2-fold higher at day 5 compared to all other days (P < 0.05), possibly indicating that the mucosal redox balance was disturbed in that time window. The higher GSH-Px activity, GSH content, and GSSG:GSH ratio in the proximal SI might illustrate the higher need for antioxidant action at that site. Plasma MDA and GSH-Px activity followed a comparable pattern as in the small intestine.

Modelling nitrate losses from agricultural activities on a national scale.

The Nitrogen Risk Assessment Model for Scotland (NIRAMS) has been developed as a screening tool for prediction of streamwater N concentrations draining from agricultural land in Scotland. The objective of the model is to be able to predict N concentrations for ungauged catchments, to fill gaps in monitoring data and provide guidance in relation to policy development. The model uses national land use, soils and meteorology data sets and has been developed within an ArcView GIS user interface. The model includes modules to calculate N inputs to the land, residual N remaining at the end of the growing season, weekly time-series of leached N and transport of N at the catchment scale. The N leaching and transport are. controlled by hydrological modules, including a national water balance model and a catchment scale transport model. Preliminary testing of NIRAMS has been carried out on eight Scottish catchments, diverse in terms of geographic location as well as land use. The model is capable of predicting the correct mean level of stream N concentrations, as well as the basic characteristics of seasonal variation. As such the model can be of value for providing estimates of N concentrations in ungauged areas.

The prolonged P(300) latency in recently detoxified alcohol-dependent patients is related to activation of the inflammatory response system.

The aims of this study were to examine the late components of the auditory event-related potentials (AERPs), i.e. N(100), P(200) and P(300), in recently detoxified alcohol-dependent patients compared to normal controls and to investigate whether there is a relationship between alterations in these AERPs and signs of activation of the inflammatory response system (IRS). The study subjects consisted of 14 healthy volunteers and 14 recently detoxified alcohol-dependent patients. All subjects performed a two-tone auditory discrimination task, using a standard "oddball" paradigm. The alcohol-dependent patients had their blood sampled to examine IRS markers, such as erythrocyte sedimentation rate (ESR), serum copper concentrations and the number of leukocytes. The P(300) latency was significantly greater in recently detoxified alcohol-dependent patients than in normal controls. There were significant correlations between the P(300) latency and the ESR (r = 0.84, p = 0.009), serum copper concentrations (r = 0.73, p = 0.01) and number of monocytes (r = 0.71, p = 0.006). It is concluded that the P(300) latency is prolonged in detoxified, chronic alcohol-dependent patients and is positively related to indicators of IRS activation. It is hypothesized that activation of the IRS may play a role in the delayed P(300) latency in recently detoxified, alcohol-dependent patients.

Linear CT-scan measurements in alcohol-dependent patients with and without delirium tremens.

The aims of the present study were to examine whether chronic alcohol dependence and the development of delirium tremens are characterized by changes in linear CT measurements of brain liquor spaces and intracranial distances indicative of prefrontal atrophy, and frontal (sub)cortical or temporal (sub)cortical atrophy. Toward this end linear measurements were performed in 47 alcohol dependent patients with and without a history of delirium tremens and in 10 healthy volunteers using CT-scanning. The following linear measurements were calculated: (1) the Evans ratio; (2) the cella media index (CMI); (3) the maximum width of the third ventricle; (4) the maximum width of the fourth ventricle; (5) the maximum frontal subarachnoid space (MFSS); (6) the maximum width of the anterior interhemispheric fissure (MIF), and (7) the maximum width of the Sylvian fissure (MSF). The alcoholics were divided into subgroups according to the Münchner Alkoholismus Test (MALT) and the presence of delirium tremens. The MFSS of the alcohol-dependent patients was significantly larger than that of the controls. The MIF and MSF of high MALT scorers were significantly larger than those of low scorers and controls. Alcohol-dependent patients with a known history of delirium tremens had significantly larger MIF and MSF than did patients without delirium tremens and controls. The results suggest that alcohol dependence is characterized by prefrontal atrophy, and that frontal cortical and temporal (sub)cortical atrophy may be related to the development of delirium tremens.

Lower activity of serum peptidases in abstinent alcohol-dependent patients.

This study examines i) the activity of serum prolyl endopeptidase (PEP) and dipeptidlyl peptidase IV (DPP IV) in detoxified alcohol-dependent patients without liver disease versus normal controls, and ii) the relationships between serum DPP IV and PEP activity and the production of cytokines or cytokine receptors, such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), interferon-y (IFN-y), IL-1 receptor antagonist (IL-1RA), and IL-10, and granulocyte-macrophage colony stimulatory factor (GM-CSF). Alcohol-dependent patients had significantly lower serum PEP and DPP IV activity than normal controls. We found that 58.3% and 50.0% of the alcohol-dependent patients, respectively, had PEP and DPP IV activities, which were lower than the mean control values minus 2 SD. There were significant inverse correlations between lowered serum DPP IV and PEP activity and the increased production of IL-6, INF-gamma, IL-IRA, IL-10, and GM-CSF. These results show that lower serum DPP IV and PEP activity may be related to the pathophysiology of alcohol dependence.

Detection of human papilloma virus (HPV) genomes by the primed in situ (PRINS) labelling technique.

Primed in situ Labelling, a technique based on primer mediated DNA synthesis, has become a useful tool in cytogenetics, especially for chromosome mapping, banding and the investigation of sequence organization in fresh metaphase preparations. Its application in the routine surgical pathology laboratory has been hampered by the fact that the technique did not work on paraffin-embedded, formalin-fixed tissue. We investigated cervical biopsies (n = 20) with morphological signs of HPV infection and found that the PRINS method is at least as sensitive as a classical in situ hybridization assay for detecting HPV DNA in paraffin-embedded, formalin-fixed tissue. In all investigated cases (n = 20), HPV DNA was found by both methods. The PRINS method was able to demonstrate HPV DNA not only in superficial koilocytotic squamous cells but also in non-koilocytotic cells in the deeper spinous cell layers, and even in some basal cells. We describe an economical protocol using conventional consensus HPV oligonucleotide DNA primers. The described method is rapid (approximately 3 hours) and easy to perform for screening and subtyping HPV infection in the routine surgical pathology laboratory.

Vibrio vulnificus wound infections from the Mississippi Gulf coastal waters: June to August 1993.

Vibrio vulnificus, part of the normal marine flora of the Gulf of Mexico, is being increasingly recognized as an important human pathogen. V vulnificus contamination of superficial wounds can cause a severe, rapidly progressive, necrotizing cellulitis with bullous skin lesions that may require surgical debridement and is occasionally fatal. We summarize information about six cases of V vulnificus wound infection reported to the Mississippi State Department of Health from June to August 1993. Five of the six patients required hospitalization for intravenous antibiotic treatment and, in two cases, surgery. Two patients died from septicemia, despite aggressive antibiotic treatment; both had preexisting medical conditions that could have contributed to immune compromise and fulminant infection. This report underscores the virulence of this organism and the need for awareness by both the clinician and diagnostic laboratory personnel when dealing with superficial wounds occupationally or recreationally exposed to seawater.

Gastric leiomyoblastoma with metastases to the liver. A 36-year follow-up study.

A patient presented with large intrahepatic tumoral masses 36 yr after the initial detection of multiple liver metastases during a gastrectomy. The operation had been performed to remove four ulcerated polypoid gastric lesions. Reexamination of the previous liver and gastric biopsy specimens revealed a gastric leiomyoblastoma with metastases to the liver. The smooth muscle origin of this tumor was confirmed by positive staining for desmin intermediate filaments. This very long survival is extremely unusual in cases of metastatic gastric leiomyoblastoma.