Cortical venous disease severity in MELAS syndrome correlates with brain lesion development.

PURPOSE: MELAS syndrome is a mitochondrial disorder typified by recurrent stroke-like episodes, seizures, and progressive brain injury. Abnormal mitochondria have been found in arterial walls implicating a vasculogenic etiology. We have observed abnormal cortical vein T2/FLAIR signal in MELAS patients, potentially representing wall thickening and sluggish flow. We sought to examine the relationship of hyperintense veins and brain lesions in MELAS. METHODS: Imaging databases at two children's hospitals were searched for brain MRIs from MELAS patients. Artifact, sedated exams, and lack of 2D-T2/FLAIR sequences were exclusion criteria. Each exam was assigned a venous score based on number of T2/FLAIR hyperintense veins: 1 = <10, 2 = 10 to 20, 3 = >20. Cumulative brain lesions and venous score in MELAS and aged-matched normal exams were compared by Mann-Whitney test. RESULTS: A total of 106 exams from 14 unique MELAS patients (mean 16 ± 3 years) and 30 exams from normal aged-matched patients (mean 15 ± 3 years) were evaluated. Median venous score between MELAS and control patients significantly differed (3 versus 1; p < 0.001). In the MELAS group, venous score correlated with presence (median = 3) or absence (median = 1) of cumulative brain lesions. In all 8 MELAS patients who developed lesions, venous hyperintensity was present prior to, during, and after lesion onset. Venous score did not correlate with brain lesion acuity. CONCLUSION: Abnormal venous signal correlates with cumulative brain lesion severity in MELAS syndrome. Cortical venous stenosis, congestion, and venous ischemia may be mechanisms of brain injury. Identification of cortical venous pathology may aid in diagnosis and could be predictive of lesion development.

Patterns of Brain Injury in Newborns Treated with Extracorporeal Membrane Oxygenation.

BACKGROUND AND PURPOSE: Neonates treated with extracorporeal membrane oxygenation are at risk for brain injury and subsequent neurodevelopmental compromise. Advances in MR imaging and improved accessibility have led to the increased use of routine MR imaging after extracorporeal membrane oxygenation. Our objective was to describe the frequency and patterns of extracorporeal membrane oxygenation-related brain injury based on MR imaging findings in a large contemporary cohort of neonates treated with extracorporeal membrane oxygenation. MATERIALS AND METHODS: This was a retrospective study of neonatal patients treated with extracorporeal membrane oxygenation from 2005-2015 who underwent MR imaging before discharge. MR imaging and ultrasound studies were reviewed for location and type of parenchymal injury, ventricular abnormalities, and increased subarachnoid spaces. Parenchymal injury frequencies between patients treated with venoarterial and venovenous extracorporeal membrane oxygenation were compared by χ2 tests. RESULTS: Of 81 neonates studied, 46% demonstrated parenchymal injury; 6% showed infarction, mostly in vascular territories (5% anterior cerebral artery, 5% MCA, 1% posterior cerebral artery); and 20% had hemorrhagic lesions. The highest frequency of injury occurred in the frontal (right, 24%; left, 25%) and temporoparietal (right, 14%; left, 19%) white matter. Sonography had low sensitivity for these lesions. Other MR imaging findings included volume loss (35%), increased subarachnoid spaces (44%), and ventriculomegaly (17% mild, 5% moderate, 1% severe). There were more parenchymal injuries in neonates treated with venoarterial (49%) versus venovenous extracorporeal membrane oxygenation (29%, P = .13), but the pattern of injury was consistent between both modes. CONCLUSIONS: MR imaging identifies brain injury in nearly half of neonates after treatment with extracorporeal membrane oxygenation. The frontal and temporoparietal white matter are most commonly affected, without statistically significant laterality. This pattern of injury is similar between venovenous and venoarterial extracorporeal membrane oxygenation, though the frequency of injury may be higher after venoarterial extracorporeal membrane oxygenation.

Almonds vs complex carbohydrates in a weight reduction program.

OBJECTIVE: To evaluate the effect of an almond-enriched (high monounsaturated fat, MUFA) or complex carbohydrate-enriched (high carbohydrate) formula-based low-calorie diet (LCD) on anthropometric, body composition and metabolic parameters in a weight reduction program. DESIGN: A randomized, prospective 24-week trial in a free-living population evaluating two distinct macronutrient interventions on obesity and metabolic syndrome-related parameters during weight reduction. SUBJECTS: In total, 65 overweight and obese adults (age: 27-79 y, body mass index (BMI): 27-55 kg/m(2)). INTERVENTION: A formula-based LCD enriched with 84 g/day of almonds (almond-LCD; 39% total fat, 25% MUFA and 32% carbohydrate as percent of dietary energy) or self-selected complex carbohydrates (CHO-LCD; 18% total fat, 5% MUFA and 53% carbohydrate as percent of dietary energy) featuring equivalent calories and protein. MAIN OUTCOME MEASUREMENTS: Various anthropometric, body composition and metabolic parameters at baseline, during and after 24 weeks of dietary intervention. RESULTS: LCD supplementation with almonds, in contrast to complex carbohydrates, was associated with greater reductions in weight/BMI (-18 vs -11%), waist circumference (WC) (-14 vs -9%), fat mass (FM) (-30 vs -20%), total body water (-8 vs -1%) and systolic blood pressure (-11 vs 0%), P=0.0001-0.05. A 62% greater reduction in weight/BMI, 50% greater reduction in WC and 56% greater reduction in FM were observed in the almond-LCD as compared to the CHO-LCD intervention. Ketone levels increased only in the almond-LCD group (+260 vs 0%, P<0.02). High-density lipoprotein cholesterol (HDL-C) increased in the CHO-LCD group and decreased in the almond-LCD group (+15 vs -6%, P=0.05). Glucose, insulin, diastolic blood pressure, total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C) and LDL-C to HDL-C ratio decreased significantly to a similar extent in both dietary interventions. Homeostasis model analysis of insulin resistance (HOMA-IR) decreased in both study groups over time (almond-LCD: -66% and CHO-LCD: -35%, P<0.0001). Among subjects with type 2 diabetes, diabetes medication reductions were sustained or further reduced in a greater proportion of almond-LCD as compared to CHO-LCD subjects (96 vs 50%, respectively) [correction]. CONCLUSION: Our findings suggest that an almond-enriched LCD improves a preponderance of the abnormalities associated with the metabolic syndrome. Both dietary interventions were effective in decreasing body weight beyond the weight loss observed during long-term pharmacological interventions; however, the almond-LCD group experienced a sustained and greater weight reduction for the duration of the 24-week intervention. Almond supplementation of a formula-based LCD is a novel alternative to self-selected complex carbohydrates and has a potential role in reducing the public health implications of obesity.

The Fusion glycoprotein shell of Semliki Forest virus: an icosahedral assembly primed for fusogenic activation at endosomal pH.

Semliki Forest virus (SFV) has been extensively studied as a model for analyzing entry of enveloped viruses into target cells. Here we describe the trace of the polypeptide chain of the SFV fusion glycoprotein, E1, derived from an electron density map at 3.5 A resolution and describe its interactions at the surface of the virus. E1 is unexpectedly similar to the flavivirus envelope protein, with three structural domains disposed in the same primary sequence arrangement. These results introduce a new class of membrane fusion proteins which display lateral interactions to induce the necessary curvature and direct budding of closed particles. The resulting surface protein lattice is primed to cause membrane fusion when exposed to the acidic environment of the endosome.

Determinants in the envelope E protein and viral RNA helicase NS3 that influence the induction of apoptosis in response to infection with dengue type 1 virus.

One mechanism by which dengue (DEN) virus may cause cell death is apoptosis. In this study, we investigated whether the genetic determinants responsible for acquisition by DEN type 1 (DEN-1) virus of mouse neurovirulence interfere with the induction of apoptosis. Neurovirulent variant FGA/NA d1d was generated during the adaptation of the human isolate of DEN-1 virus strain FGA/89 to grow in newborn mouse brains and mosquito cells in vitro [Desprès, P. Frenkiel, M. -P. Ceccaldi, P.-E. Duarte Dos Santos, C. and Deubel, V. (1998) J. Virol., 72: 823-829]. Genetic determinants possibly responsible for mouse neurovirulence were studied by sequencing the entire genomes of both DEN-1 viruses. Three amino acid differences in the envelope E protein and one in the nonstructural NS3 protein were found. The cytotoxicity of the mouse-neurovirulent DEN-1 variant was studied in different target cells in vitro and compared with the parental strain. FGA/NA d1d was more pathogenic for mouse neuroblastoma cells and attenuated for human hepatoma cells. Changes in virus replicative functions and virus assembly may account, in a large part, for the differences in the induction of apoptosis. Our data suggest that identified amino acid substitutions in the envelope E protein and viral RNA helicase NS3 may influence DEN-1 virus pathogenicity by altering viral growth.

Breathlessness and exercise in spinal cord injury.

After spinal cord injury (SCI), breathlessness during daily activities is common. In 308 individuals with SCI, the authors measured pulmonary function and administered a survey regarding health status, participation in wheelchair athletics, and breathlessness during different activities. The following questions were included: A. Are you troubled by shortness of breath when hurrying on the level or going up a slight hill?; B. Do you have to go slower than people of your own age on the level because of breathlessness?; C. Do you ever have to stop for breath when going at your own pace on the level?; and D. Do you ever have to stop for breath after going about 100 yards on the level? The analysis was restricted to 183 subjects with neurologically motor complete or incomplete SCI who, to get around, used hand-propelled wheelchairs more than 50% of the time. Of these, 56 (31%) reported breathlessness during some types of activities. Subjects with neurologically motor complete cervical or high thoracic SCI (T-6 and above) were more likely to report breathlessness than others (39% compared with 25%, p = .039). Among wheelchair athletes, the prevalence of breathlessness was 8/49 (16%) versus 48/134 (36%) for non-athletes (p = .011). Adjusting for smoking, neurological level, and history of obstructive lung disease, non-athletes were 2.3 times more likely to report breathlessness than athletes were (p = .049 to .075, depending on regression model). This relationship persisted when adjusted for percent predicted forced expiratory volume (FEV1) and maximal expiratory and inspiratory pressures. Therefore in SCI, wheelchair athletes are less likely to report breathlessness than non-athletes, but the mechanism does not appear to be improvement in respiratory muscle performance or pulmonary function.

Breathlessness in spinal cord injury depends on injury level.

Little is known about the prevalence and predictors of breathlessness in individuals with neurologically complete chronic spinal cord injury (SCI). Between December 1992 and September 1993, we mailed a respiratory questionnaire to 1,147 community-based individuals with chronic SCI. The questionnaire included four questions about the presence of breathlessness during activities related to moving about. Of the 485 who replied (42 percent response rate), analysis was limited to adult males with neurologically complete motor injuries who reported using a hand-propelled wheelchair more than 50 percent of the time to get around. Of 130 subjects (33 tetraplegics, 53 high thoracic SCI, 44 lower injury levels), the patients with tetraplegia reported breathlessness more frequently (range for the four questions, 21-33%) than those with high thoracic (range, 9-15%) or lower injury levels (range, 2-11%). For each of the four questions there was a significant trend (p < 0.05) for subjects with higher levels of injury to report the greatest prevalence of breathlessness (tetraplegia > high thoracic > lower). The frequency of breathlessness was greatest in those with neurologically complete cervical injuries, an effect that was independent of obesity, smoking, age, and years since SCI. The mechanisms of breathlessness in SCI are unclear but elucidation might lead to strategies for providing relief.

Structure determination of echovirus 1.

The atomic structure of echovirus 1 (a member of the enterovirus genus of the picornavirus family) has been determined using cryo-crystallography and refined to 3.55 A resolution. Echovirus 1 crystallizes in space group P22121 with a = 352.45, b = 472.15 and c = 483.20 A. The crystals contain one full virus particle in the asymmetric unit allowing for 60-fold noncrystallographic symmetry averaging. The diffraction pattern shows strong pseudo-B-centering with reflections with h + l = 2n + 1 being systematically weak or absent below about 6 A resolution. The size of the unit cell and presence of pseudo-B-centering placed strong constraints on the allowed packing of the icosahedral particle in the crystal lattice. These constraints greatly facilitated the determination of the orientation and position of the virus by reducing the dimensionality of the search, but interactions between the crystallographic and noncrystallographic symmetries rendered the choice of space group ambiguous until very late in the structure determination. This structure determination provides a striking example of the power of packing analysis in molecular replacement and illustrates how subtle interactions between crystallographic and noncrystallographic symmetries can be resolved.

Structural studies of poliovirus mutants that overcome receptor defects.

In order to better understand the process of cell entry for non-enveloped viruses, we have solved the crystal structures of five poliovirus mutants which can infect cells expressing mutant poliovirus receptors. Four of these structures have been solved from frozen crystals using cryocrystallographic data collection methods. The mutations have a range of structural consequences, from small local perturbations to significant loop rearrangements. All of the mutant viruses are more labile to conversion to an apparent cell entry intermediate, suggesting that these mutant viruses could compensate for the suboptimal receptors by lowering the thermal energy required to undergo the receptor-mediated conformational change.

Poliovirus: new insights from an old paradigm.

A combination of structural and genetic studies of poliovirus suggests that the final stages of viral assembly lock the virus in a metastable structure primed to undergo the receptor-catalyzed conformational changes required for cell entry. Future studies promise to provide detailed insights into the conformational dynamics of the virion during its life cycle.

Structure of the complex between the Fab fragment of a neutralizing antibody for type 1 poliovirus and its viral epitope.

The crystal structure of the complex between the Fab fragment of C3, a neutralizing antibody for poliovirus, and a peptide corresponding to the viral epitope has been determined at 3.0 A resolution. Although this antibody was originally raised to heat inactivated (noninfectious) virus particles, it strongly neutralizes the Mahoney strain of type 1 poliovirus. Eleven peptide residues are well-defined in the electron-density map and form two type I beta-turns in series. At the carboxyl end, the peptide is bound snugly in the antibody-combining site and adopts a conformation that differs significantly from the structure of the corresponding residues in the virus. Structural comparisons between the peptide in the complex and the viral epitope suggests that on binding to infectious virions, this antibody may induce structural changes important for neutralization.

Homolog-scanning mutagenesis reveals poliovirus receptor residues important for virus binding and replication.

Poliovirus initiates infection of primate cells by binding to the poliovirus receptor, Pvr. Mouse cells do not bind poliovirus but express a Pvr homolog, Mph, that does not function as a poliovirus receptor. Previous work has shown that the first immunoglobulin-like domain of the Pvr protein contains the virus binding site. To further identify sequences of Pvr important for its interaction with poliovirus, stable cell lines expressing mutated Pvr molecules were examined for their abilities to bind virus and support virus replication. Substitution of the amino-terminal domain of Mph with that of Pvr yields a molecule that can function as a poliovirus receptor. Cells expressing this chimeric receptor have normal binding affinity for poliovirus, yet the kinetics of virus replication are delayed. Results of virus alteration assays indicate that this chimeric receptor is defective in converting native virus to 135S altered particles. This defect is not observed with cells expressing receptor recombinants that include Pvr domains 1 and 2. Because altered particles are believed to be an intermediate in poliovirus entry, these findings suggest that Pvr domains 2 and 3 participate in early stages of infection. Additional mutants were made by substituting variant Mph residues for the corresponding residues in Pvr. The results were interpreted by using a model of Pvr predicted from the known structures of other immunoglobulin-like V-type domains. Analysis of stable cell lines expressing the mutant proteins revealed that virus binding is influenced by mutations in the predicted C'-C" loop, the C" beta-strand, the C"-D loop, and the D-E loop. Mutations in homologous regions of the immunoglobulin-like CD4 molecule alter its interaction with gp120 of human immunodeficiency virus type 1. Cells expressing Pvr mutations on the predicted C" edge do not develop cytopathic effect during poliovirus infection, suggesting that poliovirus-induced cytopathic effect may be induced by the virus-receptor interaction.