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Nav1.7 is an extensively investigated target for pain with a strong genetic link in humans, yet in spite of this effort, it remains challenging to identify efficacious, selective, and safe inhibitors. Here, we disclose the discovery and preclinical profile of GDC-0276 (1) and GDC-0310 (2), selective Nav1.7 inhibitors that have completed Phase 1 trials. Our initial search focused on close-in analogues to early compound 3. This resulted in the discovery of GDC-0276 (1), which possessed improved metabolic stability and an acceptable overall pharmacokinetics profile. To further derisk the predicted human pharmacokinetics and enable QD dosing, additional optimization of the scaffold was conducted, resulting in the discovery of a novel series of N-benzyl piperidine Nav1.7 inhibitors. Improvement of the metabolic stability by blocking the labile benzylic position led to the discovery of GDC-0310 (2), which possesses improved Nav selectivity and pharmacokinetic profile over 1.

Nonselective antagonists of voltage-gated sodium (NaV) channels have been long used for the treatment of epilepsies. The efficacy of these drugs is thought to be due to the block of sodium channels on excitatory neurons, primarily NaV1.6 and NaV1.2. However, these currently marketed drugs require high drug exposure and suffer from narrow therapeutic indices. Selective inhibition of NaV1.6, while sparing NaV1.1, is anticipated to provide a more effective and better tolerated treatment for epilepsies. In addition, block of NaV1.2 may complement the anticonvulsant activity of NaV1.6 inhibition. We discovered a novel series of aryl sulfonamides as CNS-penetrant, isoform-selective NaV1.6 inhibitors, which also displayed potent block of NaV1.2. Optimization focused on increasing selectivity over NaV1.1, improving metabolic stability, reducing active efflux, and addressing a pregnane X-receptor liability. We obtained compounds 30-32, which produced potent anticonvulsant activity in mouse seizure models, including a direct current maximal electroshock seizure assay.

Policy makers are increasingly attentive to the importance of supportive school climates, even as many students report that schools seem to be uncaring places. Using recent scholarship that foregrounds the organizational and contextual dimensions of educational caring and student engagement, we use qualitative case study interview data to examine these concepts in two schools. We find that organizational and contextual factors such as students’ sense of continuity and the manner and degree of staff collaboration have important implications for caring, student engagement, and school climate writ broadly. Implications for policy makers and education leaders are discussed.

Using structure- and ligand-based design principles, a novel series of piperidyl chromane arylsulfonamide Nav1.7 inhibitors was discovered. Early optimization focused on improvement of potency through refinement of the low energy ligand conformation and mitigation of high in vivo clearance. An in vitro hepatotoxicity hazard was identified and resolved through optimization of lipophilicity and lipophilic ligand efficiency to arrive at GNE-616 (24), a highly potent, metabolically stable, subtype selective inhibitor of Nav1.7. Compound 24 showed a robust PK/PD response in a Nav1.7-dependent mouse model, and site-directed mutagenesis was used to identify residues critical for the isoform selectivity profile of 24.

NBI-921352 (formerly XEN901) is a novel sodium channel inhibitor designed to specifically target NaV1.6 channels. Such a molecule provides a precision-medicine approach to target SCN8A-related epilepsy syndromes (SCN8A-RES), where gain-of-function (GoF) mutations lead to excess NaV1.6 sodium current, or other indications where NaV1.6 mediated hyper-excitability contributes to disease (Gardella and Moller, 2019; Johannesen et al., 2019; Veeramah et al., 2012). NBI-921352 is a potent inhibitor of NaV1.6 (IC50 0.051 µM), with exquisite selectivity over other sodium channel isoforms (selectivity ratios of 756X for NaV1.1, 134X for NaV1.2, 276X for NaV1.7, and >583X for NaV1.3, NaV1.4, and NaV1.5). NBI-921352 is a state-dependent inhibitor, preferentially inhibiting activated (inactivated or open) channels. The state dependence leads to potent stabilization of inactivation, inhibiting NaV1.6 currents, including resurgent and persistent NaV1.6 currents, while sparing the closed/rested channels. The isoform-selective profile of NBI-921352 led to a robust inhibition of action-potential firing in glutamatergic excitatory pyramidal neurons, while sparing fast-spiking inhibitory interneurons, where NaV1.1 predominates. Oral administration of NBI-921352 prevented electrically induced seizures in a Scn8a GoF mouse, as well as in wild-type mouse and rat seizure models. NBI-921352 was effective in preventing seizures at lower brain and plasma concentrations than commonly prescribed sodium channel inhibitor antiseizure medicines (ASMs) carbamazepine, phenytoin, and lacosamide. NBI-921352 was well tolerated at higher multiples of the effective plasma and brain concentrations than those ASMs. NBI-921352 is entering phase II proof-of-concept trials for the treatment of SCN8A-developmental epileptic encephalopathy (SCN8A-DEE) and adult focal-onset seizures.

NBI-921352 (formerly XEN901) is a novel sodium channel inhibitor designed to specifically target Na

We describe the synthesis and biological evaluation of a series of novel aryl sulfonamides that exhibit potent inhibition of Na

Na

Although volunteer community engagement has been recognized as promoting positive academic outcomes among college students, such experiences can be impractical for underrepresented students who often need to work. Community-engaged employment offers paid opportunities for students to earn money while participating in meaningful community initiatives. In this study, we explored the impact of community-engaged employment on the academic outcomes of underrepresented students. We created a comparison group using propensity score matching, which reduced selection bias and group differences on background characteristics, thus strengthening causal arguments. Results showed that underrepresented students who were employed in a community-engaged work program had significantly higher second-year retention rates, graduation rates, grade point averages, and number of credits completed compared to similar students not employed in the program. These findings indicate that community-engaged employment can provide positive academic outcomes similar to volunteer community engagement experiences, while also addressing financial barriers that many underrepresented students encounter. ____ A pesar de que se reconoce que la participación comunitaria voluntaria promueve resultados académicos positivos entre los estudiantes universitarios, estas experiencias pueden resultar no muy prácticas para los estudiantes infrarrepresentados, quienes a menudo necesitan trabajar. Los empleos comprometidos con la comunidad ofrecen oportunidades pagadas para que los estudiantes ganen dinero al mismo tiempo que participan en iniciativas comunitarias significativas. En este estudio, exploramos el impacto que tienen los empleos comprometidos con la comunidad en los resultados académicos de estudiantes infrarrepresentados. Para ello, creamos un grupo de comparación utilizando el pareamiento por puntaje de propensión (‘propensity score matching’ o ‘PSM’ en inglés), lo que redujo el sesgo de selección y las diferencias de grupo basadas en el entorno social, fortaleciendo así los argumentos causales. Al comparar los resultados académicos de estudiantes infrarrepresentados empleados en programas de participación comunitaria con estudiantes similares no empleados en dichos programas, observamos que tanto la tasa de retención en el segundo año de estudios, como la tasa de graduación, los promedios de calificaciones y el número de créditos completados fueron significativamente más altos en los primeros. Estos hallazgos indican que el empleo comprometido con la comunidad puede proporcionar resultados académicos positivos similares a las experiencias de participación comunitaria voluntaria, al tiempo que ofrece una solución a las barreras financieras que enfrentan muchos estudiantes infrarrepresentados.

Variants implicated in childhood epilepsy have been identified in all four voltage-gated sodium channels that initiate action potentials in the central nervous system. Previous research has focused on the functional effects of particular variants within the most studied of these channels (NaV1.1, NaV1.2 and NaV1.6); however, there have been few comparative studies across channels to infer the impact of mutations in patients with epilepsy. Here we compare patterns of variation in patient and public databases to test the hypothesis that regions of known functional significance within voltage-gated sodium (NaV) channels have an increased burden of deleterious variants. We assessed mutational burden in different regions of the Nav channels by (1) performing Fisher exact tests on odds ratios to infer excess variants in domains, segments, and loops of each channel in patient databases versus public "control" databases, and (2) comparing the cumulative distribution of variant sites along DNA sequences of each gene in patient and public databases (i.e., independent of protein structure). Patient variant density was concordant among channels in regions known to play a role in channel function, with statistically significant higher patient variant density in S4-S6 and DIII-DIV and an excess of public variants in SI-S3, DI-DII, DII-DIII. On the other hand, channel-specific patterns of patient burden were found in the NaV1.6 inactivation gate and NaV1.1 S5-S6 linkers, while NaV1.2 and NaV1.6 S4-S5 linkers and S5 segments shared patient variant patterns that contrasted with those in NaV1.1. These different patterns may reflect different roles played by the NaV1.6 inactivation gate in action potential propagation, and by NaV1.1 S5-S6 linkers in loss of function and haploinsufficiency. Interestingly, NaV1.2 and NaV1.6 both lack amino acid substitutions over significantly long stretches in both the patient and public databases suggesting that new mutations in these regions may cause embryonic lethality or a non-epileptic disease phenotype.

Herein, we report the discovery and optimization of a series of orally bioavailable acyl sulfonamide NaV1.7 inhibitors that are selective for NaV1.7 over NaV1.5 and highly efficacious in in vivo models of pain and hNaV1.7 target engagement. An analysis of the physicochemical properties of literature NaV1.7 inhibitors suggested that acyl sulfonamides with high fsp3 could overcome some of the pharmacokinetic (PK) and efficacy challenges seen with existing series. Parallel library syntheses lead to the identification of analogue 7, which exhibited moderate potency against NaV1.7 and an acceptable PK profile in rodents, but relatively poor stability in human liver microsomes. Further, design strategy then focused on the optimization of potency against hNaV1.7 and improvement of human metabolic stability, utilizing induced fit docking in our previously disclosed X-ray cocrystal of the NaV1.7 voltage sensing domain. These investigations culminated in the discovery of tool compound 33, one of the most potent and...

Summary: Selective block of NaV1.7 promises to produce non-narcotic analgesic activity without motor or cognitive impairment. Several NaV1.7-selective blockers have been reported, but efficacy in animal pain models required high multiples of the IC50 for channel block. Here, we report a target engagement assay using transgenic mice that has enabled the development of a second generation of selective Nav1.7 inhibitors that show robust analgesic activity in inflammatory and neuropathic pain models at low multiples of the IC50. Like earlier arylsulfonamides, these newer acylsulfonamides target a binding site on the surface of voltage sensor domain 4 to achieve high selectivity among sodium channel isoforms and steeply state-dependent block. The improved efficacy correlates with very slow dissociation from the target channel. Chronic dosing increases compound potency about 10-fold, possibly due to reversal of sensitization arising during chronic injury, and provides efficacy that persists long after the compound has cleared from plasma. : Bankar et al. show that acylsulfonamides produce analgesic activity at low multiples of the IC50 for inhibition of NaV1.7, in contrast to studies with arylsulfonamides that required >10 times the IC50. The improvement correlates with longer residency time on the target channels. Keywords: pain, sodium channel, inherited erythromelalgia, diabetic neuropathy, residence time

The sodium channel NaV1.7 has emerged as a promising target for the treatment of pain based on strong genetic validation of its role in nociception. In recent years, a number of aryl and acyl sulfonamides have been reported as potent inhibitors of NaV1.7, with high selectivity over the cardiac isoform NaV1.5. Herein, we report on the discovery of a novel series of N-([1,2,4]triazolo[4,3-a]pyridin-3-yl)methanesulfonamides as selective NaV1.7 inhibitors. Starting with the crystal structure of an acyl sulfonamide, we rationalized that cyclization to form a fused heterocycle would improve physicochemical properties, in particular lipophilicity. Our design strategy focused on optimization of potency for block of NaV1.7 and human metabolic stability. Lead compounds 10, 13 (GNE-131), and 25 showed excellent potency, good in vitro metabolic stability, and low in vivo clearance in mouse, rat, and dog. Compound 13 also displayed excellent efficacy in a transgenic mouse model of induced pain.

Nonselective antagonists of voltage-gated sodium (Na

Using structure- and ligand-based design principles, a novel series of piperidyl chromane arylsulfonamide Na

The sodium channel Na

We report on a novel series of aryl sulfonamides that act as nanomolar potent, isoform-selective inhibitors of the human sodium channel hNaV1.7. The optimization of these inhibitors is described. We aimed to improve potency against hNaV1.7 while minimizing off-target safety concerns and generated compound 3. This agent displayed significant analgesic effects in rodent models of acute and inflammatory pain and demonstrated that binding to the voltage sensor domain 4 site of NaV1.7 leads to an analgesic effect in vivo. Our findings corroborate the importance of hNaV1.7 as a drug target for the treatment of pain.

The unsteady flow field around two automotive outside rear-view mirrors is investigated. This study includes comprehensive experimental and computational approaches in order to characterize the complex flow structures in the wake of the mirrors. The experiments were carried out in a wind tunnel which included the measurements of the instantaneous and averaged velocity fields as well as mean and unsteady surface pressure distributions. The simulations were performed using Large Eddy Simulation (LES). The LES approach (particularly with the dynamic subgrid viscosity model) provided good agreements with the experiments for the velocity and the surface pressure distributions. The experimental and the computational results of this study will be used as a benchmark to validate the current and the future CFD development and the subsequent aero-acoustic computations.

Hemangiopericytoma (HPC) is a rare tumor of the central nervous system. Primary spinal occurrence of this tumor is extremely uncommon and cases involving the intramedullary spinal cord are even more rare. The purpose of this study was to explore the clinical features, surgical strategies, outcome and pathology in a consecutive series of patients treated at a single institution.The authors performed a retrospective review of the clinicopathological characteristics of four patients with a pathological diagnosis of spinal HPC.Four cases with intradural as well as intra/extra-medullary components were identified. Gross total resection with no recurrence at the operative site was achieved in the majority of patients with a spinal HPC. One patient had significant recurrence and eventually, succumbed to the disease.Increased awareness of these tumors' capability to occur intradurally and intramedullarly can help surgeons accurately diagnose and choose an effective plan of care. Gross total resection of hemangiopericytomas is the mainstay of treatment and should be pursued if feasible. Histopathology is essential to the diagnosis.

The effect of the shroud position on the performance of an automotive cooling fan with the radiator mounted at the front end has been studied on a test platform, and the characteristics of the flow field and phase-averaged velocity, vorticity, and turbulence intensity in five phases behind the cooling fan have been acquired by using digital particle image velocimetry. Moreover, a comparison of the flow field behind the fan with the shroud and that behind the fan without the shroud is made. The results of the performance experiment demonstrate that the fan with the shroud covering only the front part of the rotor possesses the highest performance, and the performance of the fan without the shroud seems to be less affected by the system flowrate. Flow field measurements show that the fan with the shroud has a larger exit radial component of the velocity than the fan without the shroud except at low system flowrates, and the vorticity and the turbulence intensity of the fan with the shroud are lower than those of the fan without the shroud.

From 2002 to 2007 fuel sulfur content in the Minneapolis/St Paul area decreased from about 325 ppm S to

The continuously regenerating trap (CRT) is a diesel exhaust emission control that removes nearly all diesel particulate matter on a mass basis, but under some circumstances oxidation of sulfur leads to the formation of nanoparticles. The objective of the four year study was to determine CRT performance under controlled, real-world, on-road conditions, and to develop quantitative relationships between fuel and lubrication oil sulfur concentration and particle number exhaust emissions. It was shown that nanoparticle emissions are minimized by the use of ultralow sulfur fuels and specially formulated low sulfur lubrication oil. Nanoparticle emissions increased with higher exhaust temperatures. Fuel and lubrication oil sulfur increased the particle concentration by, on average, 36 x 10(6) and 0.14 x 10(6) part/cm3 for each 1 ppm increase in sulfur. On the other hand there was a decrease in nanoparticle emissions by the CRT as the system aged.

The detailed chemical composition of particulate matter emissions from four non-smoking gasoline powered motor vehicles were measured using three different driving conditions: a cold-cold start Unified Driving Cycle (UDC), a hot UDC, and a steady state cruise driving cycle. The cold-cold start UDC tests were performed with a cold-cold start temperature of 0°C, which is significantly lower than the 24°C cold start temperature widely used for motor vehicle testing. Each vehicle was operated over three cold-cold UDC cycles, three hot UDC cycles, and a steady state driving cycle comprised of 2 hours at 100 kilometers per hour (kph) plus 1 hour at 50 kph. Particulate matter emissions were characterized for elemental carbon (EC), organic carbon (OC), sulfate ions, nitrate ions, ammonium ions, and organic compounds using gas chromatography mass spectrometry (GCMS). Mass emissions rates for the test vehicles using both the hot UDC and steady state driving cycles ranged from < 0.1 to 1.3 mg km −1 , while the avera...

Voltage-gated sodium (Nav) channels propagate action potentials in excitable cells. Accordingly, Nav channels are therapeutic targets for many cardiovascular and neurological disorders. Selective inhibitors have been challenging to design because the nine mammalian Nav channel isoforms share high sequence identity and remain recalcitrant to high-resolution structural studies. Targeting the human Nav1.7 channel involved in pain perception, we present a protein-engineering strategy that has allowed us to determine crystal structures of a novel receptor site in complex with isoform-selective antagonists. GX-936 and related inhibitors bind to the activated state of voltage-sensor domain IV (VSD4), where their anionic aryl sulfonamide warhead engages the fourth arginine gating charge on the S4 helix. By opposing VSD4 deactivation, these compounds inhibit Nav1.7 through a voltage-sensor trapping mechanism, likely by stabilizing inactivated states of the channel. Residues from the S2 and S3 helices are key determinants of isoform selectivity, and bound phospholipids implicate the membrane as a modulator of channel function and pharmacology. Our results help to elucidate the molecular basis of voltage sensing and establish structural blueprints to design selective Nav channel antagonists.

Two Diesel particulate matter emission control devices; the continuously regenerating trap ( CRT TM ) and the catalyzed continuously regenerating trap ( CCRT TM ) were evaluated using a mobile emissions laboratory. The source of emissions was the lab's engine that was fueled with 15 ppm sulfur fuel, and specially formulated, low sulfur (1300 ppm) lubrication oil. The objective was to characterize performance using real-time aerosol instrumentation, real-world dilution, and on-road driving conditions. The devices when combined with low S fuel and lube oil effectively removed Diesel particulate matter. The CRT produced large quantities of nuclei mode particles, the quantity of which increased as a function of exhaust temperature. The CCRT reduced the exhaust particle number concentration to levels not detectable above background storage sites, thus eliminating precursors that form nuclei mode particles. Use of low S fuel and lubrication oil prolongs the storage process. Over time it is expected that this material would be released.

The primary objective was to characterize exhaust aerosols from a small group of in-use, light-duty, spark ignition (SI) vehicles operated on-road, and on a chassis dynamometer. A significant particle signature above background was not measured at highway cruise condition. Number emissions were much higher during acceleration, at high-speed cruise, and during cold–cold starts. Group average fuel-specific number emissions range from 3.9 × 10 14 to 1.0 × 10 17 particles/kg of fuel. Cold–cold start temperatures, driving cycles and vehicular condition influence SI emissions. Elemental carbon was a major contributor to mass emissions measured in chassis dynamometer Unified Driving Cycle (UDC) tests averaging 64% and 34% of the mass emissions for cold–cold and hot start cycles, respectively. Average ratios of cold–cold to hot start emissions were 3.3, 7.6, and 22 for CPC number, filter mass and SMPS volume, respectively. Apportionment results showed that on a weekly weighted basis and on weekdays, the majority of observed particle number was attributed to heavy-duty diesel traffic. Weekend production of particles was attributable to light-duty automobiles. On a per vehicle basis, heavy-duty vehicles produced substantially greater number concentrations. On a fuel-specific basis, heavy-duty vehicles produce slightly higher concentrations of particles than light-duty vehicles. The relative contribution of light-duty vehicles to particle number emissions increased as particle size decreased, for the smallest particles apportioned number emissions were 1.3 × 10 16 and 7.1 × 10 15 particles/kg of fuel for heavy-duty and light-duty vehicles, respectively. Comparison of on-road chase and apportionment results with chassis dynamometer tests in a certification type facility suggests that the latter may underestimate real-world number emissions.

The objective was to characterize diesel exhaust aerosols on road and to duplicate the results in the laboratory without altering the physical characteristics of the nuclei mode. On-road emissions from four, heavy-duty diesel truck engines were measured. The same engines were reevaluated in the manufacturers’ laboratories. For highway cruise and acceleration conditions, all engines produced bimodal size distributions with the nuclei mode ranging in size from 6 to 11 nm and the accumulation mode from 52 to 62 nm. On-road size distribution measurements nearly always showed a nuclei mode while laboratory measurements showed a nuclei mode under many, but not all conditions. Laboratory studies showed that nuclei mode particles consisted mainly of heavy hydrocarbons. More than 97% of the volume of 12 and 30 nm particles disappeared on heating to 400 °C. The volatility resembled that of C24–C32 n -alkanes implying a significant contribution from lubricating oil.

The objective of this study was to evaluate the response of a suite of portable, real-time aerosol instruments to Diesel exhaust aerosol with and without a catalytic stripper (CS) to determine the change in response as a function of particle size and volatility. The response of the photoemission aerosol sensor (PAS) was strongly influenced by the physical and chemical nature of Diesel aerosol. The presence of a large, predominantly volatile nuclei mode, and/or the presence of volatile material on the surface of the solid carbonaceous agglomerates in the accumulation mode suppressed the PAS response. Removal of the volatile material by passage of the aerosol through the CS enhanced the response, and improved correlations between the PAS, the diffusion charger (DC) and the scanning mobility particle sizer (SMPS). Data on aerosol size distributions, number, volume, and surface area concentrations with and without the CS in the sample stream are reported.

Air quality measurements were made on interstate highways in the Minneapolis metropolitan area. Gas and aerosol concentrations were measured on weekdays and weekends. By exploiting the difference in the relative volumes of heavy duty (HD) diesel and light duty (LD) spark ignition (SI) vehicles on weekdays and weekends, we were able to estimate apportioned fuel specific emissions. The on-road, apportioned, fuel specific particle number emissions factors, estimated from condensation particle counter (CPC) measurements were 1.34±0.2×1016 particles kg−1 for diesels and 7.1±1.6×1015 particles kg−1 for spark ignition vehicles. Estimates from the scanning mobility particle sizer (SMPS) measurements were 2.1±0.3×1015 particles kg−1 for diesels and 3.9±0.6×1014 particles kg−1 for SI vehicles. The difference between CPC and SMPS measurements is mainly due to different lower size detection limits of the instruments, ∼3 and ∼10 nm, respectively. On a weekly weighted basis and on weekdays, the majority of particle number was attributed to HD diesel traffic. Weekend production of particles can be primarily attributed to light duty SI automobiles. On a per vehicle basis, HD vehicles produced substantially greater numbers of particles. On a fuel specific basis, HD vehicles produce slightly higher concentrations of particles than light duty vehicles. The relative contribution of LD vehicles to particle number emissions increased as particle size decreased. The HD apportioned size distributions were similar to size distributions measured during other on-road and laboratory studies. The LD apportioned size distribution was bounded by laboratory and on-road size distributions. Our work is representative of summer, highway cruise conditions. It is likely that under cold start and high load operating conditions LD emissions will increase relative to HD emissions.

On-road experiments were conducted to determine the sensitivities of rats to real-world aerosol. This article summarizes the on-road aerosol and gas measurements and provides background information for the companion paper on the rat exposures. Measurements were carried out over 10 days, 6 h/day, driving a route from Rochester to Buffalo. Aerosol instrumentation used in this study included two scanning mobility particle sizers (SMPS) to determine the aerosol size distribution from 10 to 300 nm, 2 stand-alone condensation particle counters to determine the total aerosol number concentration, and an electrical aerosol detector to determine the aerosol length concentration. A thermal denuder (TD) was used with one of the SMPS instruments to determine the size distribution of the non-volatile fraction. Filter samples were collected and analyzed for elemental carbon, and gas analyzers measured ambient levels of CO, CO(2), and NO. Average daily total aerosol number concentration ranged from 200,000 to 560,000 particles/cm(3). Past studies on urban highways have measured total number concentrations ranging between 10(4) and 10(6) particles/cm(3). The average daily NO concentration ranged from 0.10 to 0.24 ppm and the corresponding CO(2) concentration ranged from 400 to 420 ppm. The average daily geometric number mean particle size determined by the SMPS ranged from 15 to 20 nm. The TD reduced the average SMPS number concentration between 87 and 95% and the SMPS volume between 54 and 83%, suggesting that most of the particles consisted of volatile material. The TD also increased the geometric number mean diameter from 15 to 20 nm to 30 to 40 nm.

The objective of this project was to characterize on-road aerosol on highways surrounding the Minneapolis area. Data were collected under varying on-road traffic conditions and in residential areas to determine the impact of highway traffic on air quality. The study was focused on determining on-road nanoparticle concentrations, and estimating fuel-specific and particle emissions km−1. On-road aerosol number concentrations ranged from 104 to 106 particles cm−3. The highest nanoparticle concentrations were associated with high-speed traffic. At high vehicular speeds engine load, exhaust temperature, and exhaust flow all increase resulting in higher emissions. Less variation was observed in particle volume, a surrogate measure of particle mass. Most of the particles added by the on-road fleet were below 50 nm in diameter. Particles in this size range may dominate particle number, but contribute little to particle volume or mass. Furthermore, particle number is strongly influenced by nucleation and coagulation, which have little or no effect on particle volume. Measurements made in heavy traffic, speeds

Quantification of effects from factors known to modify vegetative development and growth in grasses is important in modeling biomass yield. The objective of this study was to measure the effects of increasing levels of N on leaf appearance (LAR) and lamina extension rates (LER) in switchgrass (Panicum virgatum L.) under field and controlled environmental conditions. Five nitrogen (N) fertilizer rates (0 to 268 kg N ha−1) were applied to a stand of “Alamo” switchgrass at Dallas, TX, and to potted plants (0 to 400 ppm) in a controlled environment. Quadratic regression models best described these responses to increasing rates of fertilizer N in both the field and controlled environment. In the field, LAR−1 decreased to a minimum of 241 growing degree days (GDD) leaf−1 at 163 kg N ha−1 and LER increased to a maximum of 0.188 cm GDD−1 at 164 kg N ha−1. In the controlled environment, LAR−1 decreased to a minimum of 155 GDD leaf−1 at 90 ppm N and LER increased to a maximum of 0.272 cm GDD−1 at 156 ppm N...

Few proteins have been described functionally in such detail as ion channels. All ion channels open and close their ion-conducting pores, a process referred to as gating. The recent crystallization of the P-loop-containing channel KcsA has cast channel function in a new light. Results relating to a variety of P-loop-containing channels are converging on a common mechanism in which separation of the inner helices that line the pore results in channel opening. At the same time, differences — some subtle and some perhaps more profound — have emerged between channel types. Here we highlight the evidence for a specific conformational change during the gating of cyclic nucleotide-gated channels, and compare and contrast this evidence to that obtained for other channels.

Potassium (K+) channels influence neurotransmitter release, burst firing rate activity, pacing, and critical dampening of neuronal circuits. Internal and external factors that further modify K+channel function permit fine-tuning of neuronal circuits. Humanether-à-go-go-related gene (HERG) K+channels are unusually sensitive to external calcium concentration ([Ca2+]o). Small changes in [Ca2+]oshift the voltage dependence of channel activation to more positive membrane potentials, an effect that cannot be explained by nonspecific surface charge screening or channel pore block. The HERG–calcium concentration–response relationship spans the physiological range for [Ca2+]o. The modulatory actions of calcium are attributable to differences in the Ca2+affinity between rested and activated channels. Adjacent extracellular, negatively charged amino acids (E518 and E519) near the S4 voltage sensor influence both channel gating and Ca2+dependence. Neutralization of these charges had distinct effects on channel gating and calcium sensitivity. A change in the degree of energetic coupling between these amino acids on transition from closed to activated channel states reveals movement in this region during channel gating and defines a molecular mechanism for protein state-dependent ligand interactions. The results suggest a novel extracellular [Ca2+]osensing mechanism coupled to allosteric changes in channel gating and a mechanism for fine-tuning cell repolarization.

We have studied the functional effects of extracellular Cd(2+) on human ether-a-go-go-related gene (HERG) encoded K(+) channels. Low concentrations (10-200 microM) of extracellular Cd(2+) increased outward currents through HERG channels; 200 microM Cd(2+) more than doubled HERG currents and altered current kinetics. Cd(2+) concentrations up to 200 microM did not change the voltage dependence of channel activation, but shifted the voltage dependence of inactivation to more depolarized membrane potentials. Cd(2+) concentrations >or=500 microM shifted the voltage dependence of channel activation to more positive potentials. These results are consistent with a somewhat specific ability of Cd(2+) to destabilize the inactivated state. We tested the hypothesis that channel inactivation is essential for Cd(2+)-induced increases in HERG K(+) currents, using a double point mutation (G628C/S631C) that diminishes HERG inactivation (Smith, P. L., T. Baukrowitz, and G. Yellen. 1996. Nature (Lond.). 379:833-836). This inactivation-removed mutant is insensitive to low concentrations of Cd(2+). Thus, Cd(2+) had two distinct effects on HERG K(+) channels. Low concentrations of Cd(2+) caused relatively selective effects on inactivation, resulting in a reduction of the apparent rectification of the channel and thereby increasing HERG K(+) currents. Higher Cd(2+) concentrations affected activation gating as well, possibly by a surface charge screening mechanism or by association with a lower affinity site.

Human ether-à-go-go–related gene (HERG) encoded K+ channels were expressed in Chinese hamster ovary (CHO-K1) cells and studied by whole-cell voltage clamp in the presence of varied extracellular Ca2+ concentrations and physiological external K+. Elevation of external Ca2+ from 1.8 to 10 mM resulted in a reduction of whole-cell K+ current amplitude, slowed activation kinetics, and an increased rate of deactivation. The midpoint of the voltage dependence of activation was also shifted +22.3 ± 2.5 mV to more depolarized potentials. In contrast, the kinetics and voltage dependence of channel inactivation were hardly affected by increased extracellular Ca2+. Neither Ca2+ screening of diffuse membrane surface charges nor open channel block could explain these changes. However, selective changes in the voltage-dependent activation, but not inactivation gating, account for the effects of Ca2+ on Human ether-à-go-go–related gene current amplitude and kinetics. The differential effects of extracellular Ca2+ on the activation and inactivation gating indicate that these processes have distinct voltage-sensing mechanisms. Thus, Ca2+ appears to directly interact with externally accessible channel residues to alter the membrane potential detected by the activation voltage sensor, yet Ca2+ binding to this site is ineffective in modifying the inactivation gating machinery.

Objective To assess factors influencing uptake of amniocentesis after a positive Down's syndrome screening result. Methods Interviews of 53 Montana women with screening risks ≥1 in 300 after delivery. Results Thirty had accepted amniocentesis (“yes” group) and 23 had declined (“no” group) (57% uptake). Age at delivery was significantly higher (p=0.02) for the “no” than the “yes” group (mean 35.3 v 31.7 years). The mean risk of Down's syndrome ascertained by screening was 1 in 190 for the “no” group and 1 in 115 for the “yes” group (p=0.05). Statistically significant differences (p≤0.05) between opinions in the two groups included: ( a) desire to know if the fetus had Down's syndrome; ( b) perception of the burden of care for an affected child; ( c) support of doctor, spouse, and relatives for choice about amniocentesis; ( d) attitudes toward abortion; ( e) importance of religion; and ( f) concerns about the amniocentesis procedure. The most important factor for those choosing amniocentesis was knowing if the fetus had Down's syndrome, and for those not choosing amniocentesis, attitude about abortion. Conclusion Our results show the need for prescreening education to enable pregnant women to make informed decisions about screening for Down's syndrome and diagnostic testing.

A family with X linked inheritance of mental retardation (XLMR) is presented. There are 10 mentally retarded males and two affected females in two generations. There are four obligatory carriers, one of whom is described as "slow". Most affected males show macrocephaly and macro-orchidism, which are typical signs of the fragile X syndrome, but have been tested cytogenetically and by analysis of the FMR1 gene and do not have this syndrome. However, some normal males in the family also exhibit macro-orchidism and macrocephaly. Linkage analysis using markers derived from the X chromosome indicates that the causative gene in this family is located in the proximal long arm of the X chromosome, in the interval Xp11-q21. Maximum lod scores of 2.96 with no recombination were found at three loci in Xq13-q21: DXS1111, DXS566, and DXS986. Recombination was observed with DXS1002 (Xq21.31) and DXS991 (Xp11.2), loci separated by about 30 Mb. Although isolation of the gene in this family will be difficult because of the size of the region involved, the localisation should be helpful in investigating other similar families with XLMR, macrocephaly, and macro-orchidism not attributable to FMR1.

This paper reviews the application of radiogenic isotopes to the study of four Cu‐U and Au deposits or deposit types in the Australasian region: Olympic Dam, Porgera, the Proterozoic Au deposits of the Tennant Creek district and the Archaean gold deposits of the Yilgarn Craton. In each case it has been possible to date the mineralisation and to correlate ore formation with a specific igneous event or stage in crustal evolution. In three cases it was also possible to use radiogenic isotopes to trace the source of the metal(s) or to constrain the fluid pathway. The results illustrate the power of radiogenic isotopes in ore‐genesis studies. At the Porgera gold deposit in Papua New Guinea K‐Ar and 39Ar/40Ar dating has shown that both the mineralisation, and the spatially associated Porgera Igneous Complex, have an age of ca 6 Ma. Sr and Pb isotopic tracing of the ore fluids indicate that these elements were derived from a mixed sedimentary‐igneous source, as might be expected for a large hydrothermal system d...

The past 20 years have seen major advances in the diagnosis and management of brain abscess, with a corresponding improvement in the survival rates. The advances in radiographic scanning, the availability of new antimicrobials, and the development of novel surgical techniques have all contributed to the decreases in associated morbidity and mortality. The relative rarity of brain abscess and the frequent delays in making the diagnosis render this condition a significant challenge for the clinician. A high index of suspicion is required so that effective therapy can be instituted as soon as possible. Close coordination of care between neurosurgeons and infectious diseases specialists is increasingly important in the complicated management of brain abscess. Adequate abscess drainage and appropriate antimicrobial therapy remain the cornerstones of proper treatment of this condition.

Among gastric cancer patients, the Rhesus D-negative phenotype correlated with increased tumour recurrence [all patients, n = 83, P = 0.026; curatively (R0) resected patients, n = 51, P = 0.093] and reduced overall survival time (all patients, log-rank P = 0.0028; R0 patients, log-rank P = 0.0003) and was identified in multivariate analysis as the most important independent prognostic marker in the R0 patient group (relative risk 9.1, P = 0.0013).

Diverse pathogenetic factors may lead to the complex syndrome of early graft dysfunction, an important determinant of later renal graft outcome. That humoral factors could play a prominent role in the development of the syndrome was suggested by the capillary deposition of complement fragment C4d in about 50% of graft biopsies. This study investigates whether the presumed classical activation of complement is derived from preformed antibodies that would possibly react against endothelial HLA-class II molecules. Such antibodies were detectable by flow cytometry using a representative collection of 11 DR-typed lymphoblastoid cell lines (LCL) as targets. Simultaneous discrimination between complement-activating and -nonactivating antibodies was achieved by two-color FACS analysis. Using this method, 44 out of 86 pretransplant serum samples from recipients with early dysfunction showed reactivity against LCL (18 complement-activating, 14 nonactivating, 12 complement-activating non-IgG). Conventional panel-reactivity was observed in 20 sera only (14 also LCL-reactive). Evaluation of corresponding graft biopsies revealed that capillary C4d was associated with LCL (P = 0.018) and panel reactivity (P = 0.015) alone and in combination (P = 0.001; Pearson's chi-square test). Thirteen subsequent graft losses within one year were observed in the LCL-reactive group as compared with seven losses in the nonreactive group (panel-reactive: 7; nonreactive: 13). Thus, measurement of LCL-reactive antibodies in prospective transplant recipients improves the assessment of an individual immunological risk. The results further demonstrate that performed antibodies do not simply reflect the enhanced overall immune reactivity of certain recipients but rather act locally in vivo, thus emphasizing the role of humoral factors in the development of early graft dysfunction.

We describe a family with recurrent 11q23-qter deletion Jacobsen syndrome in two affected brothers, with unique mosaic deletion 'rescue' through development of uniparental disomy (UPD) in the mother and one of the brothers. Inheritance studies show that the deleted chromosome is of maternal origin in both boys, and microarray shows a break near the ASAM gene. Parental lymphocyte chromosomes were normal. However, the mother is homozygous in lymphocytes for all loci within the deleted region in her sons, and presumably has UPD for this region. In addition, she is mosaic for the 11q deletion seen in her sons at a level of 20-30% in skin fibroblasts. We hypothesize that one of her #11 chromosomes shows fragility, that breakage at 11q23 occurred with telomeric loss in some cells, but 'rescue' from the deletion occurred in most cells by the development of mitotic UPD. She apparently carries the 11q deletion in her germ line resulting in recurrence of the syndrome. The older son is mosaic for the 11q cell line (70-88%, remainder 46,XY), and segmental UPD11 'rescue' apparently also occurred in his cytogenetically normal cells. This is a novel phenomenon restoring disomy to an individual with a chromosomal deletion.