Role of Excited States In High-order Harmonic Generation.

We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

The use of ultrasound in intracranial tumor surgery.

BACKGROUND: As an intraoperative imaging modality, ultrasound is a user-friendly and cost-effective real-time imaging technique. Despite this, it is still not routinely employed for brain tumor surgery. This may be due to the poor image quality in inexperienced hands, and the well-documented learning curve. However, with regular use, the operator issues are addressed, and intraoperative ultrasound can provide valuable real-time information. The aim of this review is to provide an understanding for neurosurgeons of the development and use of ultrasound in intracranial tumor surgery, and possible future advances. METHODS: A systematic search of the electronic databases Embase, Medline OvidSP, PubMed, Cochrane, and Google Scholar regarding the use of ultrasound in intracranial tumor surgery was undertaken. RESULTS AND DISCUSSION: Intraoperative ultrasound has been shown to be able to accurately account for brain shift and has potential for regular use in brain tumor surgery. Further developments in probe size, resolution, and image reconstruction techniques will ensure that intraoperative ultrasound is more accessible and attractive to the neuro-oncological surgeon. CONCLUSIONS: This review has summarized the development of ultrasound and its uses with particular reference to brain tumor surgery, detailing the ongoing challenges in this area.

Identification of early and intermediate biomarkers for ARDS mortality by multi-omic approaches.

The lack of successful clinical trials in acute respiratory distress syndrome (ARDS) has highlighted the unmet need for biomarkers predicting ARDS mortality and for novel therapeutics to reduce ARDS mortality. We utilized a systems biology multi-"omics" approach to identify predictive biomarkers for ARDS mortality. Integrating analyses were designed to differentiate ARDS non-survivors and survivors (568 subjects, 27% overall 28-day mortality) using datasets derived from multiple 'omics' studies in a multi-institution ARDS cohort (54% European descent, 40% African descent). 'Omics' data was available for each subject and included genome-wide association studies (GWAS, n = 297), RNA sequencing (n = 93), DNA methylation data (n = 61), and selective proteomic network analysis (n = 240). Integration of available "omic" data identified a 9-gene set (TNPO1, NUP214, HDAC1, HNRNPA1, GATAD2A, FOSB, DDX17, PHF20, CREBBP) that differentiated ARDS survivors/non-survivors, results that were validated utilizing a longitudinal transcription dataset. Pathway analysis identified TP53-, HDAC1-, TGF-ß-, and IL-6-signaling pathways to be associated with ARDS mortality. Predictive biomarker discovery identified transcription levels of the 9-gene set (AUC-0.83) and Day 7 angiopoietin 2 protein levels as potential candidate predictors of ARDS mortality (AUC-0.70). These results underscore the value of utilizing integrated "multi-omics" approaches in underpowered datasets from racially diverse ARDS subjects.

Factors affecting patient flow in a neurosurgery department.

INTRODUCTION: Patient flow is the process by which movement of patients and clinical productivity is achieved. The objectives of this study were to implement and evaluate the NHS Improvement SAFER patient flow bundle, evaluate the impact of the Red2Green initiative, and assess the impact of frailty on patient flow. MATERIALS AND METHODS: All patients admitted to a neurosurgery unit from 1 September to 30 November 2017 were included. Using guidance set out by NHS, data were prospectively collected from daily ward lists and patient notes, including demographics, admission and discharge details, length of stay, anticipated discharge date, red days with reasons and frailty (Rockwood Clinical Frailty Scale). NHS reference costs were used for cost analyses. RESULTS: A total of 420 patients (55% elective) were included, totalling 3909 bed days. All patients received daily senior reviews before midday, and anticipated discharge dates were set at daily multidisciplinary team meetings. Ten per cent of patients were discharged before midday. There were 21% (837) red days, significantly more (76%) for emergency patients (639 vs 198 elective; P < 0.001); 63% red days were attributed to awaiting a bed in a local hospital; 25% (106) patients were classed as frail (50 elective), which was associated with a significantly longer length of stay (17.3 vs 6; P < 0.01), and more red days (615 vs 222; p<0.01). Considering excess bed charges and lost revenue (with penalties), red days cost over £1 million per year. CONCLUSIONS: SAFER has identified areas for improvement in patient flow, with obvious cost implications. It has created a platform for discussion within the referral network and identified a role for a geriatric liaison service.

Synthetic analogs of FTY720 [2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol] differentially regulate pulmonary vascular permeability in vivo and in vitro.

Novel therapies are needed to address the vascular endothelial cell (EC) barrier disruption that occurs in inflammatory diseases such as acute lung injury (ALI). We previously demonstrated the potent barrier-enhancing effects of both sphingosine 1-phosphate (S1P) and the structurally similar compound FTY720 [2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol] in inflammatory lung injury. In this study, we examined the therapeutic potential of several novel FTY720 analogs to reduce vascular leak. Similar to S1P and FTY720, the (R)- and (S)-enantiomers of FTY720 phosphonate and enephosphonate analogs produce sustained EC barrier enhancement in vitro, as seen by increases in transendothelial electrical resistance (TER). In contrast, the (R)- and (S)-enantiomers of FTY720-regioisomeric analogs disrupt EC barrier integrity in a dose-dependent manner. Barrier-enhancing FTY720 analogs demonstrate a wider protective concentration range in vitro (1-50 microM) and greater potency than either S1P or FTY720. In contrast to FTY720-induced EC barrier enhancement, S1P and the FTY720 analogs dramatically increase TER within minutes in association with cortical actin ring formation. Unlike S1P, these FTY720 analogs exhibit differential phosphorylation effects without altering the intracellular calcium level. Inhibitor studies indicate that barrier enhancement by these analogs involves signaling via G(i)-coupled receptors, tyrosine kinases, and lipid rafts. Consistent with these in vitro responses, the (S)-phosphonate analog of FTY720 significantly reduces multiple indices of alveolar and vascular permeability in a lipopolysaccharide-mediated murine model of ALI (without significant alterations in leukocyte counts). These results demonstrate the capacity for FTY720 analogs to significantly decrease pulmonary vascular leakage and inflammation in vitro and in vivo.

Single gene encodes glycophospholipid-anchored and asymmetric acetylcholinesterase forms: alternative coding exons contain inverted repeat sequences.

Polymorphic forms of acetylcholinesterase are tethered extracellularly either as dimers membrane-anchored by a glycophospholipid or as catalytic subunits disulfidelinked to a collagen tail that associates with the basal lamina. Genomic clones of acetylcholinesterase from T. californica revealed that individual enzyme forms are encoded within a single gene that yields multiple mRNAs. Each enzyme form is encoded in three exons: the first two exons, bases -22 to 1502 and 1503 to 1669, encode sequence common to both forms, while alternative third exons encode a hydrophobic C-terminal region, to which a glycophospholipid is added upon processing, and a nonprocessed C-terminus, yielding a catalytic subunit that disulfide-links with a collagen-like structural unit. The 3' untranslated region of each alternative exon contains tandem repeat sequences that are inverted with respect to the other exon. This may either dictate alternative exon usage by formation of cis stem-loops or affect the abundance of translatable mRNA by trans-hybridization between the alternative spliced mRNA species.

Molecular cloning of mouse acetylcholinesterase: tissue distribution of alternatively spliced mRNA species.

We have isolated cDNA clones encoding acetylcholinesterase from mouse muscle and brain. The polymerase chain reaction was used to amplify cDNA clones from C2 myotubes encoding the entire open reading frame and large segments of the 5' and 3' untranslated regions. The muscle cDNA clones were used to isolate clones from a brain library encoding the same mRNA species. The mouse clones encode a catalytic subunit containing a C-terminal sequence similar to that of the hydrophilic species of Torpedo. The mouse acetylcholinesterase sequence shares approximately 88% and 61% amino acid identity with bovine and Torpedo acetylcholinesterases, respectively, but only 52% identity with mouse butyrylcholinesterase, the sequence of which we have also deduced by molecular cloning. Northern blot and RNAase protection analyses indicate that the cDNA clones were derived from the acetylcholinesterase transcript that predominates in most expressing tissues. In contrast, erythroid cells are enriched in an mRNA species whose sequence diverges from that of the cDNA in the region encoding the C-terminus of the enzyme.

Pulmonary endothelial cell barrier enhancement by FTY720 does not require the S1P1 receptor.

Novel therapeutic strategies are needed to reverse the loss of endothelial cell (EC) barrier integrity that occurs during inflammatory disease states such as acute lung injury. We previously demonstrated potent EC barrier augmentation in vivo and in vitro by the platelet-derived phospholipid, sphingosine 1-phosphate (S1P) via ligation of the S1P1 receptor. The S1P analogue, FTY720, similarly exerts barrier-protective vascular effects via presumed S1P1 receptor ligation. We examined the role of the S1P1 receptor in sphingolipid-mediated human lung EC barrier enhancement. Both S1P and FTY-induced sustained, dose-dependent barrier enhancement, reflected by increases in transendothelial electrical resistance (TER), which was abolished by pertussis toxin indicating Gi-coupled receptor activation. FTY-mediated increases in TER exhibited significantly delayed onset and intensity relative to the S1P response. Reduction of S1P1R expression (via siRNA) attenuated S1P-induced TER elevations whereas the TER response to FTY was unaffected. Both S1P and FTY rapidly (within 5 min) induced S1P1R accumulation in membrane lipid rafts, but only S1P stimulated S1P1R phosphorylation on threonine residues. Inhibition of PI3 kinase activity attenuated S1P-mediated TER increases but failed to alter FTY-induced TER elevation. Finally, S1P, but not FTY, induced significant myosin light chain phosphorylation and dramatic actin cytoskeletal rearrangement whereas reduced expression of the cytoskeletal effectors, Rac1 and cortactin (via siRNA), attenuated S1P-, but not FTY-induced TER elevations. These results mechanistically characterize pulmonary vascular barrier regulation by FTY720, suggesting a novel barrier-enhancing pathway for modulating vascular permeability.

Patients with congenital myasthenia associated with end-plate acetylcholinesterase deficiency show normal sequence, mRNA splicing, and assembly of catalytic subunits.

A congenital myasthenic condition has been described in several patients characterized by a deficiency in end-plate acetylcholinesterase (AChE). The characteristic form of AChE in the end-plate basal lamina has the catalytic subunits disulfide linked to a collagen-like tail unit. Southern analysis of the gene encoding the catalytic subunits revealed no differences between patient and control DNA. Genomic DNA clones covering exon 4 and the alternatively spliced exons 5 and 6 were analyzed by nuclease protection and sequencing. Although allelic differences were detected between controls, we found no differences in exonic and intronic areas that might yield distinctive splicing patterns in patients and controls. The ACHE gene was cloned from genomic libraries from a patient and a control. Transfection of the cloned genes revealed identical species of mRNA and expressed AChE. Cotransfection of the genes expressing the catalytic subunits with a cDNA from Torpedo encoding the tail unit yielded asymmetric species that require assembly of catalytic subunits and tail unit. thus the catalytic subunits of AChE expressed in the congenital myasthenic syndrome appear identical in sequence, arise from similar splicing patterns, and assemble normally with a tail unit to form a heteromeric species.

A longitudinal study of cognition in primary progressive multiple sclerosis.

There are few longitudinal studies of cognition in patients with multiple sclerosis, and the results of these studies remain inconclusive. No serial neuropsychological data of an exclusively primary progressive series are available. Cross-sectional analyses have revealed significant correlations between cognition and magnetic resonance imaging (MRI) parameters in primary progressive multiple sclerosis (PPMS). This study investigated cognitive and MRI change in 99 PPMS patients from five European centres for 2 years. They were assessed at 12 month intervals using the Brief Repeatable Battery, a reasoning test, and a measure of depression. The MRI parameters of T1 hypointensity load, T2 lesion load, and partial brain volume were also calculated at each time point. There were no significant differences between the mean cognitive scores of the patients at year 0 and year 2. However, one-third of the patients demonstrated absolute cognitive decline on individual test scores. Results indicated that initial cognitive status on entry into the study was a good predictor of cognitive ability at 2 years. There was only a small number of significant correlations between changes in cognition and changes on MRI, notably T1 hypointensity load with the two attentional tasks (r = -0.266, P = 0.017; r = -0.303, P = 0.012). It is probable that multiple factors underlie this weak relation between the cognitive and MRI measures.

Correction of acid beta-galactosidase deficiency in GM1 gangliosidosis human fibroblasts by retrovirus vector-mediated gene transfer: higher efficiency of release and cross-correction by the murine enzyme.

Mutations in the lysosomal acid beta-galactosidase (EC 3.2.1.23) underlie two different disorders: GM1 gangliosidosis, which involves the nervous system and visceral organs to varying extents, and Morquio's syndrome type B (Morquio B disease), which is a skeletal-connective tissue disease without any CNS symptoms. This article shows that transduction of human GM1 gangliosidosis fibroblasts with retrovirus vectors encoding the human acid beta-galactosidase cDNA leads to complete correction of the enzymatic deficiency. The newly synthesized enzyme is correctly processed and targeted to the lysosomes in transduced cells. Cross-correction experiments using retrovirus-modified cells as enzyme donors showed, however, that the human enzyme is transferred at low efficiencies. Experiments using a different retrovirus vector carrying the human cDNA confirmed this observation. Transduction of human GM1 fibroblasts and mouse NIH 3T3 cells with a retrovirus vector encoding the mouse beta-galactosidase cDNA resulted in high levels of enzymatic activity. Furthermore, the mouse enzyme was found to be transferred to human cells at high efficiency. Enzyme activity measurements in medium conditioned by genetically modified cells suggest that the human beta-galactosidase enzyme is less efficiently released to the extracellular space than its mouse counterpart. This study suggests that lysosomal enzymes, contrary to the generalized perception in the field of gene therapy, may differ significantly in their properties and provides insights for design of future gene therapy interventions in acid beta-galactosidase deficiency.

Soluble monomeric acetylcholinesterase from mouse: expression, purification, and crystallization in complex with fasciculin.

A soluble, monomeric form of acetylcholinesterase from mouse (mAChE), truncated at its carboxyl-terminal end, was generated from a cDNA encoding the glycophospholipid-linked form of the mouse enzyme by insertion of an early stop codon at position 549. Insertion of the cDNA behind a cytomegalovirus promoter and selection by aminoglycoside resistance in transfected HEK cells yielded clones secreting large quantities of mAChE into the medium. The enzyme sediments as a soluble monomer at 4.8 S. High levels of expression coupled with a one-step purification by affinity chromatography have allowed us to undertake a crystallographic study of the fasciculin-mAChE complex. Complexes of two distinct fasciculins, Fas1-mAChE and Fas2-mAChE, were formed prior to the crystallization and were characterized thoroughly. Single hexagonal crystals, up to 0.6 mm x 0.5 mm x 0.5 mm, grew spontaneously from ammonium sulfate solutions buffered in the pH 7.0 range. They were found by electrophoretic migration to consist entirely of the complex and diffracted to 2.8 A resolution. Analysis of initial X-ray data collected on Fas2-mAChE crystals identified the space group as P6(1)22 or P6(5)22 with unit cell dimensions a = b = 75.5 A, c = 556 A, giving a Vm value of 3.1 A3/Da (or 60% of solvent), consistent with a single molecule of Fas2-AChE complex (72 kDa) per asymmetric unit. The complex Fas1-mAChE crystallizes in the same space group with identical cell dimensions.

Acebutolol in supraventricular arrhythmias.

The effect of intravenous acebutolol on supraventricular arrhythmias was evaluated in 20 patients, 5 with chronic obstructive pulmonary disease. A rapid ventricular rate in atrial fibrillation was slowed greater than 15% in all of 10 patients by acebutolol and in none of 5 patients by saline. A rapid ventricular rate in atrial flutter was slowed greater than 15% in all of 6 patients by acebutolol and in none of 3 patients by saline. Frequent premature atrial beats were abolished or reduced by greater than 75% in each of 2 patients by acebutolol and not in a patient by saline. Acebutolol converted multifocal atrial tachycardia to sinus rhythm in a patient. Digitalis-induced nonparoxysmal atrioventricular junctional tachycardia was not affected by saline but was abolished by acebutolol in a patient. Acebutolol was well tolerated in each of 5 patients with chronic obstructive pulmonary disease. Acebutolol is useful in the treatment of supraventricular arrhythmias.

Perinuclear biogenesis of mutant torsin-A inclusions in cultured cells infected with tetracycline-regulated herpes simplex virus type 1 amplicon vectors.

TorsinA is a novel protein identified in the search for mutations underlying the human neurologic movement disorder, early onset torsion dystonia. Relatively little is understood about the normal function of torsinA or the physiological effects of the codon deletion associated with most cases of disease. Overexpression of wild-type torsinA in cultured cells by DNA transfection results in a reticular distribution of immunoreactive protein that co-localizes with endoplasmic reticulum resident chaperones, while the dystonia-related mutant form accumulates within concentric membrane whorls and nuclear-associated membrane stacks. In this study we examined the biogenesis of mutant torsinA-positive membrane inclusions using tetracycline-regulated herpes simplex virus amplicon vectors. At low expression levels, mutant torsinA was localized predominantly around the nucleus, while at high levels it was also concentrated within cytosolic spheroid inclusions. In contrast, the distribution of wild-type torsinA did not vary, appearing diffuse and reticular at all expression levels. These observations are consistent with descriptions of inducible membrane synthesis in other systems in which cytosolic membrane whorls are derived from multilayered membrane stacks that first form around the nuclear envelope. These results also suggest that formation of mutant torsinA-positive inclusions occurs at high expression levels in culture, whereas the perinuclear accumulation of the mutant protein is present even at low expression levels that are more likely to resemble those of the endogenous protein. These nuclear-associated membrane structures enriched in mutant torsinA may therefore be of greater relevance to understanding how the dystonia-related mutation compromises cellular physiology.

Treatment of premature ventricular complexes with acebutolol.

The effect of intravenous acebutolol versus saline solution on frequent premature ventricular complexes was evaluated in a double-blind, randomized study in 20 patients, including 3 with chronic obstructive pulmonary disease. Frequent premature ventricular complexes were abolished or reduced by 75% or more in none of 12 patients given saline solution but in 18 of 20 patients (90%) given acebutolol (P less than 0.001). This therapeutic effect of acebutolol persisted for at least 2.5 hours in 17 of 20 patients (85%), for at least 3.5 hours in 14 (70%) and for at least 4 hours in 8 (40%). Acebutolol was well tolerated by the three patients with chronic obstructive pulmonary disease. These data indicate that intravenous acebutolol is useful in the treatment of premature ventricular complexes.

Contraction tension and kinetics of the peroneus longus muscle in golden retriever muscular dystrophy.

Contraction tension and kinetics of the peroneus longus muscle were studied in dogs with the Duchenne homologue, golden retriever muscular dystrophy (GRMD), in advance of evaluating localized therapies such as myoblast transplantation. Absolute and both muscle- and body-weight-corrected twitch tension in GRMD dogs were low compared to normal litter mates at 3 months of age (p < 0.0005 for all). Tetanic tension was affected similarly. However, whereas absolute values were still reduced at 6 months (p < 0.0005 for twitch and 0.005 for tetany), twitch and tetanic tension corrected for either muscle or body weight was not statistically different, suggesting that the peroneus longus may be relatively spared in GRMD. Post-tetanic potentiation was more pronounced in GRMD versus normal dogs at both 3 (p < 0.0001) and 6 (p < 0.01) months. The degree of positive staircase at 3 months of age did not differ. Twitch contraction and relaxation times were dramatically prolonged, and there was concomitant sustained electrical activity, at, or before, 6 months of age in some severely affected dogs. Relatively few carriers were evaluated at these ages, but their values were similar to those of normal dogs. Apparent sparing of the peroneus longus muscle may limit application of this technique to evaluation of therapies administered early in life or in combination with toxins. Treatment to alter changes in contraction kinetics could also be assessed.

Nontraumatic sports death in high school and college athletes.

Nontraumatic deaths occur each year in organized high school and college athletics, resulting in considerable public concern. We conducted a study of the frequency and causes of nontraumatic sports deaths in high school and college athletes in the USA through the National Center for Catastrophic Sports Injury Research to define the magnitude of this problem and its causes. Over a 10-yr period, July 1983-June 1993, nontraumatic sports deaths were reported in 126 high school athletes (115 males and 11 females) and 34 college athletes (31 males and 3 females). Estimated death rates in male athletes were fivefold higher than in female athletes (7.47 vs 1.33 per million athletes per year, P < 0.0001), and twofold higher in male college athletes than in male high school athletes (14.50 vs 6.60 per million athletes per year, P < 0.0001). Cardiovascular conditions were more common causes of death than noncardiovascular conditions. Hypertrophic cardiomyopathy and congenital coronary artery anomalies were the most common causes of death. In high school and college athletes, males are at increased risk for nontraumatic sports deaths compared with females even after adjustment for participation frequency; college males are at greater risk than high school males. In all groups the deaths were primarily due to cardiovascular conditions.

Structure and regulation of expression of the acetylcholinesterase gene.

Acetylcholinesterase, an enzyme essential for the termination of the action of acetylcholine, is encoded by a single gene. Alternative mRNA processing gives rise to the expression of enzyme forms with three distinct carboxyl-termini. These structural differences govern the cellular disposition of the expressed enzyme but do not influence catalytic activity. Alternative polyadenylation signals give rise to distinct 3' non-coding regions which are likely to affect mRNA stability. Alternative splicing also occurs at the 5' end of the gene where two promoter regions can be identified. Hence, regulation of expression of the gene occurs at 3 levels, transcriptional through alternative promoters, translational by affecting mRNA stability and processing of distinct mRNAs and post-translationally by giving rise to distinct peptide chains which are processed differently. Recombinant DNA studies have also been extended to modifying protein structure through site-specific mutagenesis and studying the function of the mutant enzymes.

Structural bases for the specificity of cholinesterase catalysis and inhibition.

The availability of a crystal structure and comparative sequences of the cholinesterases has provided templates suitable for analyzing the molecular bases of specificity of reversible inhibitors, carbamoylating agents and organophosphates. Site-specific mutagenesis enables one to modify the structures of both the binding site and peptide ligand as well as create chimeras reflecting one type of esterase substituted in the template of another. Herein we define the bases for substrate specificity of carboxylesters, the stereospecificity of enantiomeric alkylphosphonates and the selectivity of tricyclic aromatic compounds in the active center of cholinesterase. We also describe the binding loci of the peripheral site and changes in catalytic parameters induced by peripheral site ligands, using the peptide fasciculin.

The benefits and risks of over-the-counter availability of levonorgestrel emergency contraception.

Removing the prescription requirement for Plan B will help ensure that the product plays a larger role nationally in the reduction of unintended pregnancy and abortion-important public health goals. Over-the-counter (OTC) sale of Plan B should present no serious safety issues. OTC consumers are able to understand and follow the instructions for proper use of Plan B. Efficacy of the OTC product is likely to be the same as, or better than, the prescription product, given more timely access to treatment. Based on the results of a growing body of literature and foreign marketing experience, the risk of unintended health consequences also appears to be minimal. There is no evidence to suggest that American women will abuse Plan B as an OTC product.