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BACKGROUND: Wolff-Parkinson-White (WPW) syndrome is a relatively common arrhythmia affecting ~1-3/1000 individuals. Mutations in PRKAG2 have been described in rare patients in association with cardiomyopathy. However, the genetic basis of WPW in individuals with a structurally normal heart remains poorly understood. Sudden death due to atrial fibrillation (AF) can also occur in these individuals. Several studies have indicated that despite ablation of an accessory pathway, the risk of AF remains high in patients compared to general population. METHODS: We applied exome sequencing in 305 subjects, including 65 trios, 80 singletons, and 6 multiple affected families. We used de novo analysis, candidate gene approach, and burden testing to explore the genetic contributions to WPW. RESULTS: A heterozygous deleterious variant in PRKAG2 was identified in one subject, accounting for 0.6% (1/151) of the genetic basis of WPW in this study. Another individual with WPW and left ventricular hypertrophy carried a known pathogenic variant in MYH7. We found rare de novo variants in genes associated with arrhythmia and cardiomyopathy (ANK2, NEBL, PITX2, and PRDM16) in this cohort. There was an increased burden of rare deleterious variants (MAF

We thank the EPSRC (EP/K025112/1) and the Leverhulme Trust (RPG-2016-323) for funding and Diamond Light Source for rapid access to synchrotron radiation facilities. The conjugated dicarboxylate, sodium naphthalene-2,6-dicarboxylate (Na2NDC), has been prepared by a low energy consumption reflux method and its performance as a negative electrode for sodium-ion batteries evaluated in electrochemical cells. The structure of Na2NDC was solved for the first time (monoclinic P21/c) from powder X-ray diffraction data and consists of π-stacked naphthalene units separated by sodium-oxygen layers. Through an appropriate choice of binder and conducting carbon additive Na2NDC exhibits a reversible two electron sodium insertion at around 0.4 V vs. Na+/Na with remarkably stable capacities of ca. 200 mA h g-1 at a rate of C/2 and good rate capability (~133 mA h g-1 at 5C). In parallel the high thermal stability of the material is demonstrated by HT-X-ray diffraction, the framework remaining intact to above 500 °C. Postprint

Objectives To report our experience with intravascular and hybrid intra-operative stent placement for baffle obstruction in patients with complete transposition of the great arteries (TGA) after the atrial switch (Mustard/Senning) operation. Background Venous baffle obstruction is a challenging complication after atrial switch operation in patients with TGA. Traditional treatment options include intravascular stenting or surgery. Methods A retrospective analysis of Mayo Clinic's electronic medical record was completed to identify consecutive pediatric and adult patients with TGA after atrial switch who underwent baffle stent implantation from 1994 to 2015. Results Overall, 64 patients were referred for cardiac catheterization, in whom 47 (73%) were noted to have hemodynamic and angiographic evidence of baffle obstruction. A total of 20 patients mean age 33 (range: 8–46) years old underwent stent implantation of baffle stenosis at a mean of 33 (range: 7.5–45) years after initial atrial switch operation (Mustard, n = 19; Senning, n = 1). Overall, 27 baffles were stented in 20 patients via the following approaches: intravascular (17); hybrid surgical (3); staged intravascular & hybrid (2). Sites of stent placement were: superior vena cava (SVC) (13); inferior vena cava (IVC) (9); pulmonary venous baffle (5). Three patients had stent placement in the SVC and IVC baffles during the same procedure. Procedural adverse events occurred in 2/22 cases (9%) including creation of unintentional baffle leak (n = 1) and stent migration (n = 1). There was no procedure-related mortality. At follow-up (median 2, range 0.02–10 years), significantly improved NYHA class and mean Doppler baffle gradient were demonstrated (P

Sudden Cardiac Arrest During Sex in Cardiac ChannelopathiesBackground Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) and long-QT syndrome (LQTS) are susceptible to cardiac events during sympathetic nervous system activation. Herein, we sought to determine the risk of cardiac events associated with sex in CPVT and LQTS patients. Methods and Results We reviewed the electronic medical record of patients seen in the Genetic Heart Rhythm Clinic. There were 445 patients ≥18 years diagnosed with LQTS (N = 402, age at diagnosis 30 ± 16 years) or CPVT (N = 43, age at diagnosis 25 ± 15 years). No sex-induced cardiac events occurred in the LQTS population, and 2 occurred in the CPVT population. Sex-induced events were more likely in CPVT (2/43, 4.7%) than LQTS (0/402, 0%, P = 0.008). One case involved a 22-year-old CPVT1 female with prior cardiac arrest, who experienced several appropriate implantable cardioverter defibrillator shocks during intercourse while taking β-blockers. The second case was a 52-year-old CPVT1 male with history of recurrent exercise-triggered syncope, who had syncope during sex in the setting of β-blocker noncompliance. Extrapolating from published estimates of intercourse frequency by age, the overall event rate was only 0.0004%, and 0.005% among the CPVT cohort. Conclusions Potentially life-threatening cardiac events during sex in patients with CPVT are rare and even rarer in LQTS. Overall, the cardiac event per intercourse rate is extremely low. Patients and their partners should be reassured that sex is a low-risk activity from a cardiac standpoint.

Muscle contraction is triggered by the spread of an action potential along the fibre. The ionic current to generate the action potential is conducted through voltage-activated sodium channels, and mutations of these channels are known to cause several human muscle disorders. Mouse models have been created by introducing point mutations into the sodium channel gene. This achievement has created the need for a high-fidelity technique to record sodium currents from intact mouse muscle fibres. We have optimized a two-electrode voltage clamp, using sharp microelectrodes to preserve the myoplasmic contents. The voltage-dependent behaviour of sodium channel activation, inactivation and slow-inactivation were characterized. The voltage range for these gating behaviours was remarkably hyperpolarized, in comparison to studies in artificial expression systems. These results provide normative data for sodium channels natively expressed in mouse muscle and illustrate the need to modify model simulations of muscle excitability to account for the hyperpolarized shift.

Mutations of voltage-gated ion channels cause several channelopathies of skeletal muscle, which present clinically with myotonia, periodic paralysis, or a combination of both. Expression studies have revealed both loss-of-function and gain-of-function defects for the currents passed by mutant channels. In many cases, these functional changes could be mechanistically linked to the defects of fibre excitability underlying myotonia or periodic paralysis. One remaining enigma was the basis for depolarization-induced weakness in hypokalaemic periodic paralysis (HypoPP) arising from mutations in either sodium or calcium channels. Curiously, 14 of 15 HypoPP mutations are at arginines in S4 voltage sensors, and recent observations show that these substitutions support an alternative pathway for ion conduction, the gating pore, that may be the source of the aberrant depolarization during an attack of paralysis.

The effect on spore germination of the entomopathogenic fungus Lecanicillium muscarium following direct exposure for 24 h to the insecticides Majestik, Spray Oil, Agri-50E, Savona and Oberon for the control of both egg and second instar stages of the sweetpotato whitefly, Bemisia tabaci, was determined. Exposure to both Agri-50E and Oberon was followed by acceptable spore germination. Infectivity rates of L. muscarium on poinsettia foliage in the presence of dry residues of the insecticides were also investigated. No significant detrimental effects on the levels of control of B. tabaci were recorded compared with fungus applied to residue-free foliage. Sequential application of the chemicals Savona, Spray Oil and Majestik with the fungus all produced mortalities of second instar B. tabaci above 90%. Incorporation of these chemicals with L. muscarium into integrated control programs for B. tabaci is discussed.

The combination of sarcolemmal depolarization and hypokalemia exhibited by the different forms of hypokalemic paralysis has been attributed to abnormalities of the K+ conductance governing the resting membrane potential (V(REST)). Supportive data have been observed in muscle fibers biopsied from patients with familial hypokalemic periodic paralysis (HypoPP) that paradoxically depolarize at low K+. Although this observation is consistent with anomalous K+ conductance, rigorous experimental support is lacking. To establish a foundation for understanding the pathophysiology of hypokalemic paralysis, we studied Ba2+-treated muscle fibers under voltage clamp. As anticipated, Ba2+ blocked inward rectifying K+ (IRK) currents, and thereby promoted depolarization, supporting the notion that the IRK conductance governs V(REST). The IRK conductance also declined when muscle was challenged with reduced external K+. When the external K+ declined below 1 mM, V(REST) became uncoupled from the K+ reversal potential and depolarized. Partial ( approximately 50%) block of the IRK conductance with Ba2+ potentiated this uncoupling threshold, such that depolarization could be elicited by exposure to 2 mM external K+. A quantitative computer model of resting ionic conductances was constructed, and simulations demonstrated that small alterations to resting conductances, such as adding a low-amplitude aberrant inward current flowing through "gating pores" in mutant Na+ channels causing HypoPP-2, can promote paradoxical depolarization in low K+. These findings offer a simple explanation for some of the heretofore poorly understood physiological abnormalities of HypoPP muscle and support the notion that pathological gating pore leakage currents may directly predispose to paralytic attacks.

Infants and small children with atrioventricular (AV) nodal disease frequently require pacing in order to maintain an adequate heart rate. The maintenance of AV synchrony is physiologically optimal in this setting. Unfortunately, small size and congenital anomalies often preclude the placement of standard transvenous dual chamber pacing systems. We report the case of a small child with a pre-existing dual chamber epicardial pacing system and subsequent ventricular lead dysfunction who underwent implantation of a new single chamber transvenous system which was programmed in VVT (triggered) mode in order to maintain AV synchrony.

Octahedral, six-coordinate Co2+ can exist in two spin states: S = 3/2 and S = 1/2. The difference in energy between high spin (S = 3/2) and low spin (S = 1/2) is dependent on both the ligand mix and coordination stereochemistry. B3LYP calculations on combinations of neutral imidazole, NH3, and H2O ligands show that low-spin isomers are stabilized by axial H2O ligands and in structures that also include trans pairs of equatorial NH3 and protonated imidazole ligands, spin crossover structures are predicted from spin state energy differences. Occupied Co d orbitals from the DFT calculations provide a means of estimating effective ligand strength for homoleptic and mixed ligand combinations. These calculations suggest that in a labile biological system, a spin crossover environment can be created. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Background: Because of venous occlusion, intracardiac shunting, previous surgery, or small size placement of implantable cardioverter-defibrillator (ICD) leads may not be possible using traditional methods. The purpose of this study was to evaluate and describe innovative methods of placing ICD leads. Methods: The records of all patients undergoing ICD implantation at our institution were reviewed to identify patients with nontraditional lead placement. Indications for ICD, method of lead and coil placement, defibrillation thresholds, complications, and follow-up results were reviewed retrospectively. Results: Eight patients (aged 11 months to 29 years) were identified. Six patients with limited venous access to the heart (four extracardiac Fontan, one bidirectional Glenn, one 8 kg 11-month-old) underwent surgical placement of an ICD coil directly into the pericardial sac. A second bipolar lead was placed on the ventricle for sensing and pacing. Two patients with difficult venous access had a standard transvenous ICD lead inserted directly into the right atrium (transatrial approach) and then positioned into the ventricle. All patients had a defibrillation threshold of

The integrative ambitions of systems biology and neuroinformatics—to construct working models of the machinery of living cells and brains—will flounder unless researchers have access to the huge amounts of diverse experimental data being collected. However, the vast majority of bioscience research data that is gathered is never made available to other researchers, partly for the want of an adequate software for annotating experimental data, and partly for social reasons (researchers are rarely rewarded for publishing the actual data sets—just for journal articles summarizing findings). We have developed a novel software solution aimed at making it simpler for researchers to annotate and publish their research data. The first part of this solution is a desktop application, Catalyzer, which lets researchers structure their data at source, and complements existing ad hoc solutions in use in labs (including cryptic filenames, Word, Excel, paper lab books) while being simpler and more flexible than relational databases, which are too complex for most bioscience researchers to set up. The catalogs produced by Catalyzer are stored in XML with a user defined schema, which will simplify future data mining efforts across large numbers of distributed data sets. The approach can be summarized as ‘structure at source, integrate as required’, with the initial focus on enabling the researchers to structure their own research data; only then will other researchers be able to integrate across data sets. Copyright © 2006 John Wiley & Sons, Ltd.

Missense mutations in the skeletal muscle sodium channel α-subunit gene (SCN4A) are associated with a group of clinically overlapping diseases caused by alterations in the excitability of the sarcolemma. Sodium channel defects may increase excitability and cause myotonic stiffness or may render fibres transiently inexcitable to produce periodic paralysis. A patient with cold-aggravated myotonia did not harbour any of the common SCN4A mutations. We therefore screened all 24 exons by denaturing high-performance liquid chromatography, followed by direct sequencing. Two novel missense changes were found with predicted amino acid substitutions: T323M in the DIS5-S6 loop and F1705I in the intracellular C-terminus. The functional impact of these substitutions was assessed by recording whole-cell Na+ currents from transiently transfected HEK293 cells. T323M currents were indistinguishable from wild-type (WT). Fast inactivation was impaired for F1705I channels, as demonstrated by an 8.6-mV rightwards shift in voltage dependence and a two-fold slowing in the rate of inactivation. Recovery from fast inactivation was not altered, nor was there an increase in the persistent current after a 50- ms depolarization. Activation and slow inactivation were not appreciably affected. These data suggest that T323M is a benign polymorphism, whereas F1705I results in fast inactivation defects, which are often observed for myotonia. This is the first example of a C-terminal mutation in SCN4A associated with human disease. Like the cardiac disorders (long QT syndrome type 3 or Brugada syndrome) and generalized epilepsy with febrile seizures plus (GEFS+) associated with C-terminal mutations in other NaV channels, the primary effect of F1705I was a partial disruption of fast inactivation.

Summary International actions to combat the threat posed by invasive alien species (IAS) to crops and biodiversity have intensifi ed in recent years. The formulation of 15 guiding principles on IAS by the Convention on Biological Diversity (CBD) stimulated the International Plant Protection Convention (IPPC) to review its role in protecting biodiversity. IPPC standards now demonstrate clearly that the risks posed by any organism that is directly or indirectly injurious to cultivated or uncultivated plants can be assessed and managed under the IPPC. Since the IPPC, unlike the CBD, constitutes an international legal instrument recognised by the World Trade Organization, greater protection from the introduction of IAS is now available. However, phytosanitary measures can only be enacted if they can be justifi ed by risk analysis and we outline some novel strategies to improve the assessment and management of the risks posed by IAS, highlighting some of the key challenges which remain.

SUMMARY The indigenous terrestrial planarian fauna (three species) of the UK is outnumbered by introduced exotics, of which there are at least nine species. The New Zealand flatworm, Arthurdendyus triangularis, is one of the most widespread and apparent of these non-indigenous earthworm predators, particularly in Northern Ireland and central Scotland. Despite its having been in the UK for at least 35 yr, our knowledge of the biology and ecology of this species remains somewhat limited. In Scotland, A. triangularis occurs predominantly in botanical and domestic gardens, and is not generally considered to be a problem on agricultural land. The situation in Northern Ireland is different; although predominantly found in domestic gardens, it appears to have colonised grass leys many localities although the impact on earthworm populations remains ambiguous. In England, records are increasing, predominantly from northern regions. Studies have indicated that earthworm species vary in terms of their vulnerability to predation by A. triangularis; surface-active and anecic species are considered to be most at risk. However, A. triangulatus and earthworm populations are known to coexist, apparently in a state of dynamic equilibrium, in a number of localities. Naturally-occurring planarian populations are often severely constrained by food supply, but individuals survive lengthy periods of starvation. Such behaviour may preclude the natural recolonisation of habitats by prey species. Very much higher rates of population growth can be achieved where food is not limited, and where favourable conditions result from horticultural practices. The mobility of the prey species may determine the dispersal strategy of the flatworm predator, and a propensity not to move away from centres of prey density might account for the relatively low rate of colonisation of agricultural land by A. triangulatus. Additionally, reliance on protected refuges, may explain the present, somewhat limited distribution in the UK, particularly in southern England. It is difficult to estimate the potential distribution of A. triangulatus, because of the lack of fundamental knowledge of its ecoclimatic requirements. A better understanding is needed of the precise habitat requirements (and constraints) of A. triangulatus, particularly where this species appears to have adapted to rural conditions.

Exchangeable apolipoproteins are proteins that reversibly bind lipoprotein particles to facilitate their transport in vivo. The structure/function relationship of apolipophorin-III (apo-III), the only insect exchangeable apolipoprotein, has been investigated by examining the association of this protein with lipid vesicles. The importance of a conserved leucine residue, reported to be essential for apo-III binding to lipids, has been evaluated through site-directed mutagenesis. A unique cysteine replaces the conserved leucine at position 30 in recombinant apo-III (L30C protein). This substitution results in the covalent dimerization of the apo-III mutant via a disulfide bond. The cysteine mutation causes no difference in surface hydrophobicity of the L30C proteins when compared to the wild type apo-III. Wild type apo-III, L30C monomer, and L30C dimer associate with dimyristoylphosphatidylcholine (DMAC) vesicles in a similar manner, resulting in a reduction of turbidity of a phospholipid vesicle suspension. Analysis with transmission electron microscopy (TEM) reveals disk-like complexes identical to those previously reported with the wild type apo-III. Because the mutation of the conserved leucine seems to affect the solution behavior and surface hydrophobicity of apo-III, this residue is likely to be exposed to the aqueous environment. However, the similar behaviors of the wild type protein, the L30C monomer, and L30C dimer with respect to the binding of phospholipid vesicles suggest that this residue is not absolutely required for the protein binding to hydrophobic or amphiphilic interfaces.

The number of quarantine pests listed in the Annexes of the EU Directive 77/93 is limited. However, many other unlisted organisms of phytosanitary potential are regularly intercepted by the EU member states, and new pests can confidently be expected to continue to appear. EU legislation provides the powers for certain actions to be taken to prevent the entry of unlisted pests into a member state. The initial action is often taken against a background of uncertainty, yet must be taken speedily in order to avoid pest spread and possible establishment. Emergency measures aim to eradicate the pest or contain the outbreak while detection surveys are carried out, and need to be sufficiently robust to meet possible threats. Such safeguarding measures may be modified as the uncertainties involved are minimized. The International Plant Protection Convention obliges contracting parties to recognize that phytosanitary measures should be technically justified, on the basis of pest risk analysis, as well as‘transparent’. In recognition of the uncertain and variable quarantine status of unlisted pests, the UK has adopted a systematic protocol to determine appropriate measures in each case. This approach is illustrated with reference to specific, unlisted invertebrate pests.

Recent estimates for global warming predict increases in global mean surface air temperatures (relative to 1990) of between 1 and 3.5 °C, by 2100. The impact of such changes on agricultural systems in mid- to high-latitude regions are predicted to be less severe than in low-latitude regions, and possibly even beneficial, although the influence of pests and diseases is rarely taken into account. Most studies have concluded that insect pests will generally become more abundant as temperatures increase, through a number of inter-related processes, including range extensions and phenological changes, as well as increased rates of population development, growth, migration and over-wintering. A gradual, continuing rise in atmospheric CO2 will affect pest species directly (i.e. the CO2 fertilization effect) and indirectly (via interactions with other environmental variables). However, individual species responses to elevated CO2 vary: consumption rates of insect herbivores generally increase, but this does not necessarily compensate fully for reduced leaf nitrogen. The consequent effects on performance are strongly mediated via the host species. Some recent experiments under elevated CO2 have suggested that aphids may become more serious pests, although other studies have discerned no significant effects on sap-feeding homopterans. However, few, if any of these experiments have fully considered the effects on pest population dynamics. Climate change is also considered from the perspective of changes in the distribution and abundance of species and communities. Marked changes in the distribution of well-documented species – including Odonata, Orthoptera and Lepidoptera – in north-western Europe, in response to unusually hot summers, provide useful indications of the potential effects of climate change. Migrant pests are expected to respond more quickly to climate change than plants, and may be able to colonize newly available crops/habitats. Range expansions, and the removal of edge effects, could result in the increased abundance of species presently near the northern limits of their ranges in the UK. However, barriers to range expansions, or shifts, may include biotic (competition, predation, parasitism and disease), as well as abiotic, factors. Climatic phenomena, ecosystem processes and human activities are interactive and interdependent, making long-term predictions extremely tenuous. Nevertheless, it appears prudent to prepare for the possibility of increases in the diversity and abundance of pest species in the UK, in the context of climate change.

1 Missense mutations in the α-subunit of the human skeletal muscle sodium channel (hSkM1) have been detected in some heritable forms of myotonia. By recording Na+ currents from cells transfected with cDNA encoding either wild-type or mutant hSkM1, we characterized the functional consequences of two myotonia-associated mutations that lie at the cytoplasmic end of the sixth transmembrane segment in domain II (S804F) or domain III (V1293I). 2 Both mutations caused modest, but unequivocal, alterations in the voltage-dependent gating behaviour of hSkM1. For S804F, the abnormalities were limited to fast inactivation: the persistent Na+ current at the end of a 50 ms depolarization was increased 3-fold, the rate of inactivation from the open state was slowed 2-fold, and the voltage dependence of fast inactivation (h∞) was shifted by +3 mV. V1293I also disrupted fast inactivation, as evidenced by a 3-fold faster rate of recovery at hyperpolarized potentials (

1. Cells derived from a rat pituitary tumour (GC cell line) that continuously release growth hormone behave as endogenous pacemakers. In simultaneous patch clamp recordings and cytosolic Ca2+ concentration ([Ca2+]i) imaging, they displayed rhythmic action potentials (44.7 +/- 2.7 mV, 178 +/- 40 ms, 0.30 +/- 0.04 Hz) and concomitant [Ca2+]i transients (374 +/- 57 nM, 1.0 +/- 0.2 s, 0.27 +/- 0.03 Hz). 2. Action potentials and [Ca2+]i transients were reversibly blocked by removal of external Ca2+, addition of nifedipine (1 microM) or Ni2+ (40 microM), but were insensitive to TTX (1 microM). An L-type Ca2+ current activated at -33.6 +/- 0.4 mV (holding potential (Vh), -40 mV), peaked at -1.8 +/- 1.3 mV, was reduced by nifedipine and enhanced by S-(+)-SDZ 202 791. A T/R-type Ca2+ current activated at -41.7 +/- 2.7 mV (Vh, -80 or -60 mV), peaked at -9.2 +/- 3.0 mV, was reduced by low concentrations of Ni2+ (40 microM) or Cd2+ (10 microM) and was toxin resistant. Parallel experiments revealed the expression of the class E calcium channel alpha1-subunit mRNA. 3. The K+ channel blockers TEA (25 mM) and charybdotoxin (10-100 nM) enhanced spike amplitude and/or duration. Apamin (100 nM) also strongly reduced the after-spike hyperpolarization. The outward K+ tail current evoked by a depolarizing step that mimicked an action potential reversed at -69. 8 +/- 0.3 mV, presented two components, lasted 2-3 s and was totally blocked by Cd2+ (400 microM). 4. The slow pacemaker depolarization (3.5 +/- 0.4 s) that separated consecutive spikes corresponded to a 2- to 3-fold increase in membrane resistance, was strongly Na+ sensitive but TTX insensitive. 5. Computer simulations showed that pacemaker activity can be reproduced by a minimum of six currents: an L-type Ca2+ current underlies the rising phase of action potentials that are repolarized by a delayed rectifier and Ca2+-activated K+ currents. In between spikes, the decay of Ca2+-activated K+ currents and a persistent inward cationic current depolarize the membrane, activate the T/R-type Ca2+ current and initiate a new cycle.

A DNA polymerase was partially purified and characterized from the photosynthetic organelles (cyanelles) of the protist, Cyanophora paradoxa. While cyanelles have several cyanobacterial features, such as a lysozyme-sensitive cell wall, unstacked thylakoids and light harvesting phycobilisomes, their genome size and structure resemble those of chloroplasts, suggesting that cyanelles occupy a unique intermediate position between chloroplasts and their phylogenetic ancestors, the cyanobacteria. When comparing the biochemical characteristics of the cyanelle DNA polymerase to those of its counterparts from higher plant chloroplasts and from a cyanobacterium, it is clear that the cyanelle enzyme resembles chloroplast DNA polymerases which are eukaryotic γ-type enzymes.

Recombinant DNA technology has been employed to produce a polypeptide capable of forming pH responsive hydrophobic microdomains. The design of this peptide is based upon an idealized conceptual model in which electrostatic, hydrophobic, and hydration forces are responsible for the association of amphipathic α-helical elements. Reduction in solution pH is responsible for reducing electrostatic repulsions between similarly charged residues, promoting the hydrophobic collapse of helical elements. A polymerizable synthetic element (dn31) has been synthesized and inserted into an appropriate expression vector. A clone containing a single copy of the dn31 gene (designated dn31x1) was isolated and the corresponding gene product DN3Lx1 isolated. The physical properties of DN3Lx1 were examined in solution by gel filtration chromatography, CD, and fluorescence probe analysis. It was determined that DN3Lx1 self-associates in solution with the degree of aggregation dependent on pH and ionic strength. An initial objective of this work was to examine domain organization in higher molecular weight species containing ten or more repetitive sequences. However, attempts to express multiple repeats of DN3Lxn from concatemers were unsuccessful. © 1997 John Wiley & Sons, Inc. Biopoly 41: 521–532, 1997.

Background Several studies have indicated an etiologic role for viruses in the development of sinonasal inverted papillomata (IP). A recent report demonstrates a strong relationship (65%) between Epstein-Barr virus (EBV) and these lesions using polymerase chain reaction (PCR) analysis. Methods The present study analyzes a series of paraffin-embedded tissues, comprising 25 surgically resected IPs and four fungiform papillomata (FP) for the presence of EBV using a sensitive in situ hybridization (ISH) assay and PCR. Results None of the specimens examined showed evidence of EBV infection by ISH, and only two papillomata (one sinonasal IP and one FP) gave positive reactions for EBV using PCR. Conclusions These data challenge the previous report and suggest that EBV is not a significant etiopathologic factor to be considered in the development of sinonasal IP. © 1997 John Wiley & Sons, Inc. Head Neck19: 98–106, 1997.

There is a sharp contrast between the profuse in vivo axonal arborization of CA3 pyramidal cells in the CA1 area and the low probability of finding pairs of connected CA3-CA1 pyramidal cells in vitro. These anatomical differences contribute to a connectivity argument for discrepancies between electrophysiological data recorded in vitro and in vivo. In order to investigate this issue, we have developed a realistic computer model of the Schaffer collateral pathway of the hippocampus and analyzed the spatio-temporal distribution of action potentials along this pathway following three different types of electrical test stimulus. Direct activation of mossy fibers, CA3 pyramidal cells and focal stimulation of CA1 stratum radiatum were investigated. The parameters of the model were selected from available biological data. Spikes in Schaffer collaterals were followed from their onset in the CA3 pyramidal cell initial segment to the last order branches of their axonal tree in two types of configuration: the whole hippocampus and the slice configuration. The anatomical and electropysiological characteristics of the mossy fibre and Schaffer collateral pathways were found to impose strong constraints on the spatio-temporal distribution of action potentials in the CA1 area. Specific projection zones are determined by the spatial localization of the emitting CA3 pyramidal cells. Their position also defines precise time windows during which some CA1 projection zones receive a large number of correlated signals. Moreover, the variability of the delay at the mossy fibre/CA3 pyramidal cell synapse seems to provide the CA1 projection zones with a background level of excitation. Finally, we show how the patterns of activation obtained in the whole hippocampus are different from those obtained in the slice.

Bacterial inclusions can be defined as discrete structures seen within the confines of prokaryotic cells, generally intracytoplasmic, but in some instances in the periplasmic region of the cell. Inclusions function as metabolic reserves, cell positioners, or as metabolic organelles. Some inclusions may contribute to more than one of these functions. Those that function as metabolic reserves are glycogen, polyhydroxyalkanoate, wax ester, triacylglycerol, cyanophycin, and polyphosphate granules, and sulfur globules. These reserves are commonly accumulated in response to a nutrient imbalance, for example, under conditions of excess carbon/energy. Magnetosomes and gas vesicles contribute to cell mobility thereby assisting the cells in attaining nutrient and/or redox needs. Carboxysomes, containing the enzyme ribulose bisphosphate carboxylase/oxygenase, and chlorosomes, sacs of self-aggregated bacterriochlorophyll are carbon-fixing and light-harvesting organelles, respectively. Key Concepts: The cytoplasmic region of prokaryotic cells can be much more complex than originally thought. In addition to flagella, many prokaryotes have developed mechanisms whereby they are capable of positioning/orienting themselves in an aqueous environment. Although not as complex as the well-known eukaryotic organelles, many prokaryotes possess simple organelles. Many of the inclusions may have useful properties for applications in biotechnology Keywords: granules; globules; vesicles; crystals; metabolic reserves; simple organelles; inclusions; mobility

Bacillus thuringiensis (Bt)-based insecticide products constitute the overwhelming majority of biopesticides but, despite having been commercially available for over 30 years, they have made little impact (

The thermal decomposition of NaClO3 in the presence of metal oxides was studied using thermogravimetric analysis. A number of metal oxides were prepared to have comparable surface areas, and their catalytic effects on NaClO3 decomposition were compared. It was found that the catalytic activity depends on the electron configurations of the metal cations. Oxides containing metal cations with partially filled d-orbitals are all active catalysts for NaClO3 decomposition. Transition metal cations with no d-electrons are moderately active. Metal oxides containing metal cations with completely filled d-orbitals or noble gas configurations have very little activity.

Methyl- and phenyl-substituted N-(ethoxycarbonyl)-2-azabicyclo[2.2.0]hex-5-enes 6 were reacted with NBS in wet DMSO to afford bromohydrins. Mixtures of unrearranged 6-exo-bromo-5-endo-hydroxy-2-azabicyclo[2.2.0]hexanes 7a,b and rearranged 5-anti-bromo-6-anti-hydroxy-2-azabicyclo[2.1.1]hexanes 8a,b were formed stereoselectively from the parent alkene 6a and 4-methyl alkene 6b. The 5-methyl alkene 6c affords only unrearranged bromohydrin 7c and dibromohydrin 9. By contrast, solely rearranged 3-endo-substituted-2-azabicyclo[2.1.1]hexane bromohydrins 8d-f result from additions to 3-endo-methyl alkene 6d, 3-endo-4-dimethyl alkene 6e, and 3-endo-phenyl alkene 6f. As an alternative route to bromohydrins, the parent 5,6-exo-epoxide 10a and 5-endo-methyl-5,6-exo-epoxide 10b were ring opened with bromine/triphenylphosphine to afford unrearranged 5-endo-bromo-6-exo-hydroxy-2-azabicyclo[2.2.0]hexanes 11a,b, while the 3-endo-methyl epoxide 10c afforded solely the rearranged 5-anti-bromo-6-anti-hydroxy-3-exo-methyl-2-azabicyclo[2.1.1]hexane isomer 8g. Tributyltin hydride reduction of bromohydrins 7a,b and 11a afforded novel 2-azabicyclo[2.2.0]hexan-5-ols 13a,b and -6-ol 14, and bromohydrins 8a,b, 8d-g afforded new 2-azabicyclo[2.1.1]-hexan-5-ols 15a,b and 15d-g.

This prospective study was undertaken to assess the predictive value of esophageal insufflation on the acquisition of tracheoesophageal (TE) speech. Fourteen total laryngectomy patients were evaluated prior to tracheoesophageal puncture (TEP) using objective esophageal pressure measurements. These patients then were followed prospectively for 6 to 13 months. Speech was assessed at the time of prosthesis fitting, at 1 month, at less than 6 months, and at greater than 6 months post-TEP. No patient underwent pharyngeal myotomy. Pre-TEP esophageal insufflation pressure was associated (P = .065) with successful TE speech at the time of prosthesis fitting, but was not associated with successful TE speech acquisition after 6 months. This study's results suggest that patients with poor pre-TEP esophageal insufflation test results will usually obtain successful TE speech given adequate time and training, even without pharyngeal myotomy.

Summary 1. Microarthropods (Acari and Collembola) are dominant components of the terrestrial fauna in the Antarctic. Their cold tolerance, which forms the mainspring of their adaptational strategy, is reviewed against a background of their structure and function, and by comparison with other arthropods. 2. Two species, the isotomid collembolan Cryptopygus antarcticus Willem and the oribatid mite Alaskozetes antarcticus (Michael), are examined in detail, and afford a comparative approach to the mechanisms underlying cold tolerance in insect and arachnid types. 3. All microarthropods appear to be freezing-susceptible (unable to tolerate tissue ice), and they utilize varying levels of supercooling to avoid freezing. Gut contents are considered to be the prime nucleation site in most arthropods when supercooled, particularly for Antarctic species. Moulting also increases individual supercooling ability especially in Collembola, and the activity of ice-nucleating bacteria in cold-hardy arthropods may be important. 4. Sources of ice nucleators are many and varied, originating externally (motes) or internally (ice-nucleating agents). They act either extracellularly (mainly in the haemolymph) to promote freezing in ice-tolerant life stages, or intracellularly in freezing-susceptible forms. Thermal hysteresis proteins, acting colligatively, occur in many arthropods including Collembola; they depress both the freezing point of body fluids and the whole-body supercooling point of freezing- susceptible and freezing-tolerant species. 5. Bimodal supercooling point distributions are a feature of microarthropods and water droplets. Samples of field populations of Antarctic mites and springtails show significant seasonal changes in these distributions, which in some respects are analogous to purely physical systems of water droplets. Supercooling points are confirmed as accurate measures of cold-hardiness and survival for Antarctic species, but not necessarily for other arthropods. The effects of constant sub-zero temperatures approaching the limit of the supercooling ability of arthropods require study. 6. Desiccation and dehydration influence microarthropod physiology in several ways; in Alaskozetes it triggers glycerol synthesis. Glycerol may aid binding of water in severely dehydrated insects, but the relationship of such ‘bound’ water to cold-hardiness is unclear. 7. Sugar alcohols (polyols) and sugars are accumulated as potential cryoprotectants in many arthropods at low temperatures, and antifreeze systems may be single or multi-component in structure. Cryoprotectant synthesis and regulation have been studied principally in insects, and fresh weight concentrations of 0–3-5 M of polyols have been found. Trehalose accumulation may also influence cold-hardiness. 8. Microarthropods fall within the spectrum of cold tolerance observed for arthropods and other invertebrates. No special adaptations are found in Antarctic species, and similar strategies and mechanisms are present in both insects and arachnids. The colonization and maintenance of microarthropod populations of polar land habitats seem not to have required the evolution of any novel features with respect to cold tolerance.

Experiments were performed to evalute reproductive and developmental toxicology in rats and rabbits exposed to styrene oxide by inhalation. Female rats were exposed to 100 or 300 ppm styrene oxide or to filtered air for 7 h/day, 5 days/week for 3 weeks. Extensive mortality occurred in rats that received prolonged exposure to 100 ppm styrene oxide while 300 ppm was rapidly lethal. As a result exposures were terminated in this latter group and the group was eliminated from further study. The rats of the 0 and 100 ppm groups were then mated and exposed to 0 or 100 ppm styrene oxide daily through 18 days of gestation (dg). Female rabbits were artificially inseminated and exposed for 7 h daily to 0, 15, or 50 ppm styrene oxide through 24 dg. Both of these lower concentrations used for exposure of the rabbits produced mortality of does. The rats were killed at 20 dg and the rabbits at 30 dg. Pregnant animals were examined for toxic changes including altered tissue weights and histopathologic effects. Litters were evaluated using several measures of embryotoxicity, and live fetuses were examined for external, visceral, and skeletal malformations. Exposure during gestatation appeared to increase preimplantation loss in rats, and tended to increase the incidence of resorptions in rabbits. In both species, fetal weights and crown-rump lengths were reduced by gestational exposure. The incidences of ossification defects of the sternebrae aned occipital bones were increased by gestational exposure of rats to styrene oxide. These results indicate that inhalation exposures at these concentrations produce reproductive and development toxicity, as well as maternal toxicity.

The translational initiation point for Rhizobium meliloti nifA, the specific activator for nitrogen fixation (nif) genes, was determined. When expressed in an Escherichia coli linked transcriptional-translational system the DNA coding for the R.meliloti nifA gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. There are three in-frame ATG codons at the N-terminus of the gene; by replacing the poor ribosome binding sites of the native DNA with a synthetic consensus ribosome binding site prior to each of ATG codons the polypeptides were produced at enhanced levels and related to each of the initiation codons. The ability of these specifically expressed polypeptides to activate nif promoters fused to lacZ was determined. Only the fulllength polypeptide activated the Klebsiella pneumoniae nifH, R.meliloti nifH and fixA and Bradyrhizobium japonicum nifH and nifD promoters. The R.meliloti fixA promoter, contrary to previous evidence, could be activated in E.coli. Deletion of the putative N-terminal domain of the R.meliloti nifA gene product greatly increased the ability of the protein to activate nif promoters. However, deletions retaining part of this domain were not functional. This shows that the N-terminal domain is not essential for activity and that its presence decreases the full potential function of the protein. Our results are consistent with the suggesting that this domain has a regulatory role. In contrast to K.pneumoniae nifA protein, the function of the full length and domain deleted forms of R.meliloti nifA gene product was sensitive to oxygen in E.coli.

The ten possible substitution patterns for N-Ethoxycarbonyl-2-methyl-1,2-dihydropyridines 5 in which one or two olefinic sites are alkyl substituted were synthesized and reacted with N-phenylmaleimide 2 to provide cycloadducts 6. N-Ethoxycarbonyl-5,6-cyclohexyl-2-methyl-1,2-dihydropyridine 51 provided the novel spirocycle 61.