The effect of the N-methyl-D-aspartate receptor antagonist dextromethorphan on perioperative brain injury in children undergoing cardiac surgery with cardiopulmonary bypass: results of a pilot study.

Experimental evidence indicates a role of the N-methyl-D-aspartate receptor in the pathogenesis of brain injury occurring during cardiac surgery with cardiopulmonary bypass (CPB). Dextromethorphan is a noncompetitive antagonist of this receptor with a favorable safety profile. Thirteen children age 3-36 months undergoing cardiac surgery with expected CPB of 60 minutes or more were randomly assigned to treatment with dextromethorphan (36-38 mg/kg/day) or placebo administered by naso-gastric tube. Dextromethorphan was absorbed well and reached putative therapeutic levels in blood and cerebrospinal fluid. Adverse effects were not observed. Mild hemiparesis developed after operation in one child of each group, and severe encephalopathy in one of the placebo group. Sharp waves were recorded in postoperative continuous electroencephalography in all placebo (n = 7) but only in 2/6 dextromethorphan treated children (p = 0.02). Pre- and postoperative cranial magnetic resonance imaging (MRI) revealed less pronounced ventricular enlargement in the dextromethorphan group (not significant). An increase of periventricular white matter lesions was visible in two placebo-treated children only. No elevations of cerebrospinal fluid enzymes were observed in either group. Although children with dextromethorphan showed less abnormalities in electroencephalography and MRI, dissimilarities of the treatment groups by chance diminished conclusions to possible protective effects of dextromethorphan at this time.

Accuracy of Brain Multimodal Monitoring to Detect Cerebral Hypoperfusion After Traumatic Brain Injury.

OBJECTIVE:: To examine the accuracy of brain multimodal monitoring-consisting of intracranial pressure, brain tissue PO2, and cerebral microdialysis-in detecting cerebral hypoperfusion in patients with severe traumatic brain injury. DESIGN:: Prospective single-center study. PATIENTS:: Patients with severe traumatic brain injury. SETTING:: Medico-surgical ICU, university hospital. INTERVENTION:: Intracranial pressure, brain tissue PO2, and cerebral microdialysis monitoring (right frontal lobe, apparently normal tissue) combined with cerebral blood flow measurements using perfusion CT. MEASUREMENTS AND MAIN RESULTS:: Cerebral blood flow was measured using perfusion CT in tissue area around intracranial monitoring (regional cerebral blood flow) and in bilateral supra-ventricular brain areas (global cerebral blood flow) and was matched to cerebral physiologic variables. The accuracy of intracranial monitoring to predict cerebral hypoperfusion (defined as an oligemic regional cerebral blood flow < 35 mL/100 g/min) was examined using area under the receiver-operating characteristic curves. Thirty perfusion CT scans (median, 27 hr [interquartile range, 20-45] after traumatic brain injury) were performed on 27 patients (age, 39 yr [24-54 yr]; Glasgow Coma Scale, 7 [6-8]; 24/27 [89%] with diffuse injury). Regional cerebral blood flow correlated significantly with global cerebral blood flow (Pearson r = 0.70, p < 0.01). Compared with normal regional cerebral blood flow (n = 16), low regional cerebral blood flow (n = 14) measurements had a higher proportion of samples with intracranial pressure more than 20 mm Hg (13% vs 30%), brain tissue PO2 less than 20 mm Hg (9% vs 20%), cerebral microdialysis glucose less than 1 mmol/L (22% vs 57%), and lactate/pyruvate ratio more than 40 (4% vs 14%; all p < 0.05). Compared with intracranial pressure monitoring alone (area under the receiver-operating characteristic curve, 0.74 [95% CI, 0.61-0.87]), monitoring intracranial pressure + brain tissue PO2 (area under the receiver-operating characteristic curve, 0.84 [0.74-0.93]) or intracranial pressure + brain tissue PO2+ cerebral microdialysis (area under the receiver-operating characteristic curve, 0.88 [0.79-0.96]) was significantly more accurate in predicting low regional cerebral blood flow (both p < 0.05). CONCLUSION:: Brain multimodal monitoring-including intracranial pressure, brain tissue PO2, and cerebral microdialysis-is more accurate than intracranial pressure monitoring alone in detecting cerebral hypoperfusion at the bedside in patients with severe traumatic brain injury and predominantly diffuse injury.

Transcriptional response to cardiac injury in the zebrafish: systematic identification of genes with highly concordant activity across in vivo models.

BACKGROUND: Zebrafish is a clinically-relevant model of heart regeneration. Unlike mammals, it has a remarkable heart repair capacity after injury, and promises novel translational applications. Amputation and cryoinjury models are key research tools for understanding injury response and regeneration in vivo. An understanding of the transcriptional responses following injury is needed to identify key players of heart tissue repair, as well as potential targets for boosting this property in humans. RESULTS: We investigated amputation and cryoinjury in vivo models of heart damage in the zebrafish through unbiased, integrative analyses of independent molecular datasets. To detect genes with potential biological roles, we derived computational prediction models with microarray data from heart amputation experiments. We focused on a top-ranked set of genes highly activated in the early post-injury stage, whose activity was further verified in independent microarray datasets. Next, we performed independent validations of expression responses with qPCR in a cryoinjury model. Across in vivo models, the top candidates showed highly concordant responses at 1 and 3 days post-injury, which highlights the predictive power of our analysis strategies and the possible biological relevance of these genes. Top candidates are significantly involved in cell fate specification and differentiation, and include heart failure markers such as periostin, as well as potential new targets for heart regeneration. For example, ptgis and ca2 were overexpressed, while usp2a, a regulator of the p53 pathway, was down-regulated in our in vivo models. Interestingly, a high activity of ptgis and ca2 has been previously observed in failing hearts from rats and humans. CONCLUSIONS: We identified genes with potential critical roles in the response to cardiac damage in the zebrafish. Their transcriptional activities are reproducible in different in vivo models of cardiac injury.

Skeletal Muscle Mitochondrial and Lipid Droplet Volume Density: Validity of Electron Microscopy Point-counting Measurements

Mitochondrial (M) and lipid droplet (L) volume density (vd) are often used in exercise research. Vd is the volume of muscle occupied by M and L. The means of calculating these percents are accomplished by applying a grid to a 2D image taken with transmission electron microscopy; however, it is not known which grid best predicts these values. PURPOSE: To determine the grid with the least variability of Mvd and Lvd in human skeletal muscle. METHODS: Muscle biopsies were taken from vastus lateralis of 10 healthy adults, trained (N=6) and untrained (N=4). Samples of 5-10mg were fixed in 2.5% glutaraldehyde and embedded in EPON. Longitudinal sections of 60 nm were cut and 20 images were taken at random at 33,000x magnification. Vd was calculated as the number of times M or L touched two intersecting grid lines (called a point) divided by the total number of points using 3 different sizes of grids with squares of 1000x1000nm sides (corresponding to 1µm2), 500x500nm (0.25µm2) and 250x250nm (0.0625µm2). Statistics included coefficient of variation (CV), 1 way-BS ANOVA and spearman correlations. RESULTS: Mean age was 67 ± 4 yo, mean VO2peak 2.29 ± 0.70 L/min and mean BMI 25.1 ± 3.7 kg/m2. Mean Mvd was 6.39% ± 0.71 for the 1000nm squares, 6.01% ± 0.70 for the 500nm and 6.37% ± 0.80 for the 250nm. Lvd was 1.28% ± 0.03 for the 1000nm, 1.41% ± 0.02 for the 500nm and 1.38% ± 0.02 for the 250nm. The mean CV of the three grids was 6.65% ±1.15 for Mvd with no significant differences between grids (P>0.05). Mean CV for Lvd was 13.83% ± 3.51, with a significant difference between the 1000nm squares and the two other grids (P<0.05). The 500nm squares grid showed the least variability between subjects. Mvd showed a positive correlation with VO2peak (r = 0.89, p < 0.05) but not with weight, height, or age. No correlations were found with Lvd. CONCLUSION: Different size grids have different variability in assessing skeletal muscle Mvd and Lvd. The grid size of 500x500nm (240 points) was more reliable than 1000x1000nm (56 points). 250x250nm (1023 points) did not show better reliability compared with the 500x500nm, but was more time consuming. Thus, choosing a grid with square size of 500x500nm seems the best option. This is particularly relevant as most grids used in the literature are either 100 points or 400 points without clear information on their square size.

Contribution of TIR domain-containing adapter inducing IFN-beta-mediated IL-18 release to LPS-induced liver injury in mice.

BACKGROUND/AIMS: After treatment with heat-killed Propionibacterium acnes mice show dense hepatic granuloma formation. Such mice develop liver injury in an interleukin (IL)-18-dependent manner after challenge with a sublethal dose LPS. As previously shown, LPS-stimulated Kupffer cells secrete IL-18 depending on caspase-1 and Toll-like receptor (TLR)-4 but independently of its signal adaptor myeloid differentiation factor 88 (MyD88), suggesting importance of another signal adaptor TIR domain-containing adapter inducing IFN-beta (TRIF). Nalp3 inflammasome reportedly controls caspase-1 activation. Here we investigated the roles of MyD88 and TRIF in P. acnes-induced hepatic granuloma formation and LPS-induced caspase-1 activation for IL-18 release. METHODS: Mice were sequentially treated with P. acnes and LPS, and their serum IL-18 levels and liver injuries were determined by ELISA and ALT/AST measurement, respectively. Active caspase-1 in LPS-stimulated Kupffer cells was determined by Western blotting. RESULTS: Macrophage-ablated mice lacked P. acnes-induced hepatic granuloma formation and LPS-induced serum IL-18 elevation and liver injury. Myd88(-/-) Kupffer cells, but not Trif(-/-) cells, exhibited normal caspase-1 activation upon TLR4 engagement in vitro. Myd88(-/-) mice failed to develop hepatic granulomas after P. acnes treatment and liver injury induced by LPS challenge. In contrast, Trif(-/-) mice normally formed the hepatic granulomas, but could not release IL-18 or develop the liver injury. Nalp3(-/-) mice showed the same phenotypes of Trif(-/-) mice. CONCLUSIONS: Propionibacterium acnes treatment MyD88-dependently induced hepatic granuloma formation. Subsequent LPS TRIF-dependently activated caspase-1 via Nalp3 inflammasome and induced IL-18 release, eventually leading to the liver injury.

Chronic exercise preserves lean muscle mass in masters athletes.

Aging is commonly associated with a loss of muscle mass and strength, resulting in falls, functional decline, and the subjective feeling of weakness. Exercise modulates the morbidities of muscle aging. Most studies, however, have examined muscle-loss changes in sedentary aging adults. This leaves the question of whether the changes that are commonly associated with muscle aging reflect the true physiology of muscle aging or whether they reflect disuse atrophy. This study evaluated whether high levels of chronic exercise prevents the loss of lean muscle mass and strength experienced in sedentary aging adults. A cross-section of 40 high-level recreational athletes ("masters athletes") who were aged 40 to 81 years and trained 4 to 5 times per week underwent tests of health/activity, body composition, quadriceps peak torque (PT), and magnetic resonance imaging of bilateral quadriceps. Mid-thigh muscle area, quadriceps area (QA), subcutaneous adipose tissue, and intramuscular adipose tissue were quantified in magnetic resonance imaging using medical image processing, analysis, and visualization software. One-way analysis of variance was used to examine age group differences. Relationships were evaluated using Spearman correlations. Mid-thigh muscle area (P = 0.31) and lean mass (P = 0.15) did not increase with age and were significantly related to retention of mid-thigh muscle area (P < 0.0001). This occurred despite an increase in total body fat percentage (P = 0.003) with age. Mid-thigh muscle area (P = 0.12), QA (P = 0.17), and quadriceps PT did not decline with age. Specific strength (strength per QA) did not decline significantly with age (P = 0.06). As muscle area increased, PT increased significantly (P = 0.008). There was not a significant relationship between intramuscular adipose tissue (P = 0.71) or lean mass (P = 0.4) and PT. This study contradicts the common observation that muscle mass and strength decline as a function of aging alone. Instead, these declines may signal the effect of chronic disuse rather than muscle aging. Evaluation of masters athletes removes disuse as a confounding variable in the study of lower-extremity function and loss of lean muscle mass. This maintenance of muscle mass and strength may decrease or eliminate the falls, functional decline, and loss of independence that are commonly seen in aging adults.

Trypanosoma cruzi recognition by macrophages and muscle cells: perspectives after a 15-year study

Macrophages and muscle cells are the main targets for invasion of Trypanosoma cruzi. Ultrastructural studies of this phenomenon in vitro showed that invasion occurs by endocytosis, with attachment and internalization being mediated by different components capable of recognizing epi-or trypomastigotes (TRY). A parasitophorus vacuole was formed in both cell types, thereafter fusing with lysosomes. Then, the mechanism of T. cruzi invasion of host cells (HC) is essentially similar (during a primary infection in the abscence of a specific immune response), regardless of wether the target cell is a professional or a non-professional phagocytic cell. Using sugars, lectins, glycosidases, proteinases and proteinase inhibitors, we observed that the relative balance between exposed sialic acid and galactose/N-acetyl galactosamine (GAL) residues on the TRY surface, determines the parasite's capacity to invade HC, and that lectin-mediated phagocytosis with GAL specificity is important for internalization of T. cruzi into macrophages. On the other hand, GAL on the surface to heart muscle cells participate on TRY adhesion. TRY need to process proteolytically both the HC and their own surface, to expose the necessary ligands and receptors that allow binding to, and internalization in the host cell. The diverse range of molecular mechanisms which the parasite could use to invade the host cell may correspond to differences in the available "receptors"on the surface of each specific cell type. Acute phase components, with lectin or proteinase inhibitory activities (a-macroglobulins), may also be involved in T. cruzi-host cell interaction.

In vitro growth of human urinary tract smooth muscle cells on laminin and collagen type I-coated membranes under static and dynamic conditions.

This study investigates in vitro growth of human urinary tract smooth muscle cells under static conditions and mechanical stimulation. The cells were cultured on collagen type I- and laminin-coated silicon membranes. Using a Flexcell device for mechanical stimulation, a cyclic strain of 0-20% was applied in a strain-stress-time model (stretch, 104 min relaxation, 15 s), imitating physiological bladder filling and voiding. Cell proliferation and alpha-actin, calponin, and caldesmon phenotype marker expression were analyzed. Nonstretched cells showed significant better growth on laminin during the first 8 days, thereafter becoming comparable to cells grown on collagen type I. Cyclic strain significantly reduced cell growth on both surfaces; however, better growth was observed on laminin. Neither the type of surface nor mechanical stimulation influenced the expression pattern of phenotype markers; alpha-actin was predominantly expressed. Coating with the extracellular matrix protein laminin improved in vitro growth of human urinary tract smooth muscle cells.

Protective effects of hypercapnic acidosis on ventilator-induced lung injury.

To investigate whether respiratory acidosis modulates ventilator-induced lung injury (VILI), we perfused (constant flow) 21 isolated sets of normal rabbit lungs, ventilated them for 20 min (pressure controlled ventilation [PCV] = 15 cm H(2)O) (Baseline) with an inspired CO(2) fraction adjusted for the partial pressure of CO(2) in the perfusate (PCO(2) approximately equal to 40 mm Hg), and then randomized them into three groups. Group A (control: n = 7) was ventilated with PCV = 15 cm H(2)O for three consecutive 20-min periods (T1, T2, T3). In Group B (high PCV/normocapnia; n = 7), PCV was given at 20 (T1), 25 (T2), and 30 (T3) cm H(2)O. The targeted PCO(2) was 40 mm Hg in Groups A and B. Group C (high PCV/hypercapnia; n = 7) was ventilated in the same way as Group B, but the targeted PCO(2) was approximately equal to 70 to 100 mm Hg. The changes (from Baseline to T3) in weight gain (Delta WG: g) and in the ultrafiltration coefficient (Delta K(f) = gr/min/ cm H(2)O/100g) and the protein and hemoglobin concentrations in bronchoalveolar lavage fluid (BALF) were used to assess injury. Group B experienced a significantly greater Delta WG (14.85 +/- 5.49 [mean +/- SEM] g) and Delta K(f) (1.40 +/- 0.49 g/min/cm H(2)O/100 g) than did either Group A (Delta WG = 0.70 +/- 0.43; Delta K(f) = 0.01 +/- 0.03) or Group C (Delta WG = 5.27 +/- 2.03 g; Delta K(f) = 0.25 +/- 0.12 g/min/cm H(2)O/ 100 g). BALF protein and hemoglobin concentrations (g/L) were higher in Group B (11.98 +/- 3.78 g/L and 1.82 +/- 0.40 g/L, respectively) than in Group A (2.92 +/- 0.75 g/L and 0.38 +/- 0.15 g/L) or Group C (5.71 +/- 1.88 g/L and 1.19 +/- 0.32 g/L). We conclude that respiratory acidosis decreases the severity of VILI in this model.